WO2022054889A1

WO2022054889A1 - Adhesive sheet and method for producing semiconductor device

Info

Publication number: WO2022054889A1
Application number: PCT/JP2021/033229
Authority: WO
Inventors: 康彦垣内; 康貴渡邉
Original assignee: リンテック株式会社
Priority date: 2020-09-14
Filing date: 2021-09-10
Publication date: 2022-03-17
Also published as: TW202216445A; CN116171220A; JPWO2022054889A1; KR20230069910A

Abstract

An adhesive sheet having a laminated structure including an adhesive layer (X1) and a base material layer (Y), wherein the adhesive layer (X1) and/or the base material layer (Y) is a heat-expandable layer that contains heat-expandable particles, the arithmetic mean waviness (Wa) of the adhesive layer (X1) on a surface (S_X1) on the opposite side of the surface facing the base material layer (Y) is 0.090 μm or less. A method for producing a semiconductor device using said adhesive sheet.

Description

Manufacturing method of adhesive sheet and semiconductor device

The present invention relates to an adhesive sheet and a method for manufacturing a semiconductor device using the adhesive sheet.

Adhesive sheets are not only used for semi-permanently fixing members, but also for processing and inspection of building materials, interior materials, electronic parts, etc. (hereinafter, "covered"). It may also be used as a temporary fixing sheet for temporarily fixing). For example, in the manufacturing process of a semiconductor device, a temporary fixing sheet is used when processing a semiconductor wafer.

In the manufacturing process of a semiconductor device, a semiconductor wafer is processed into a semiconductor chip through a grinding process of reducing the thickness by grinding, an individualizing process of cutting and separating and individualizing. At this time, the semiconductor wafer is subjected to predetermined processing in a state of being temporarily fixed to the temporary fixing sheet. The semiconductor chips obtained by performing the predetermined processing are separated from the temporary fixing sheet, and then, if necessary, an expanding process for widening the distance between the semiconductor chips and a re-arrangement of a plurality of semiconductor chips with the wide distance. After appropriately performing an arranging process, an inverting process of inverting the front and back of the semiconductor chip, etc., the semiconductor chip is mounted on the substrate. Also in each of the above steps, a temporary fixing sheet suitable for each application can be used. As such a temporary fixing sheet, a single-sided adhesive sheet or a double-sided adhesive sheet is used. In the case of the double-sided adhesive sheet, the object to be processed is attached to one surface and the other surface is attached to the support. Predetermined processing may be applied.

Patent Document 1 discloses a heat-releaseable pressure-sensitive adhesive sheet for temporarily fixing an electronic component when a heat-expandable pressure-sensitive adhesive layer containing heat-expandable microspheres is provided on at least one surface of the base material. .. According to the same document, the heat-removable adhesive sheet can secure a contact area of a predetermined size with respect to the adherend when cutting an electronic component, and thus exhibits adhesiveness capable of preventing adhesive defects such as chip skipping. On the other hand, there is a description that it can be easily peeled off by reducing the contact area with the adherend by inflating the heat-expandable microspheres by heating after use.

Japanese Patent No. 3594853

When the temporary fixing sheet is used in a mode in which the object to be processed is attached to one surface thereof and the support is attached to the other surface, and the object to be processed is subjected to predetermined processing, the temporary fixing sheet is used. Hard materials may be attached to both sides of the. At this time, for example, when the hard support is attached to the temporary fixing sheet attached to the hard object to be processed, the temporary fixing sheet and the support maintain a state in which the affixed surfaces are substantially parallel to each other. It will be necessary to attach it as it is.
The method of sticking the temporary fixing sheet and the adherend while maintaining a substantially parallel state is compared with the method of sticking while bending the temporary fixing sheet, and the adhesive interface between the temporary fixing sheet and the adherend. Air pools are likely to occur. The air pool at the bonding interface causes vibration of the adherend, misalignment, etc., and may cause a decrease in processing accuracy such as cracking or chipping when processing the object to be processed. On the other hand, when the adherend is attached to the temporary fixing sheet, it can be attached under the mildest possible conditions from the viewpoint of productivity and suppressing damage and deterioration of the adherend due to pressurization and heating. Desirably, it should be avoided to make the application conditions harsh in order to improve the application property. Therefore, the temporary fixing sheet itself is required to have excellent adhesiveness, but the heat-peeling adhesive sheet of Patent Document 1 does not sufficiently satisfy this requirement.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a pressure-sensitive adhesive sheet having excellent adhesiveness and a method for manufacturing a semiconductor device using the pressure-sensitive adhesive sheet.

The present inventors have focused on the arithmetic mean swell (Wa) on the surface of the adhesive sheet, and have found that the above problems can be solved by adjusting this to a specific range, and have completed the present invention.

That is, the present invention relates to the following [1] to [13].
[1] It has a laminated structure including an adhesive layer (X1) and a base material layer (Y).
At least one of the pressure-sensitive adhesive layer (X1) and the base material layer (Y) is a heat-expandable layer containing heat-expandable particles.
An adhesive sheet having an arithmetic mean swell (Wa) of 0.090 μm or less on the surface (SX1) of the pressure-sensitive adhesive layer ( _X1 ) opposite to the surface facing the base material layer (Y).
[2] The pressure-sensitive adhesive sheet according to the above [1], wherein the heat-expandable layer has a thickness of 30 to 300 μm before thermal expansion.
[3] The above [1] or that the content of the heat-expandable particles in the heat-expandable layer is 1 to 25% by mass with respect to the total mass (100% by mass) of the heat-expandable layer. The adhesive sheet according to [2].
[4] The pressure-sensitive adhesive sheet according to any one of [1] to [3] above, wherein the expansion start temperature (t) of the heat-expandable particles is 50 ° C. or higher and lower than 125 ° C.
[5] The base material layer (Y) is a base material laminate in which a heat-expandable base material layer (Y1) containing heat-expandable particles and a non-heat-expandable base material layer (Y2) are laminated. It has a laminated structure in which the pressure-sensitive adhesive layer (X1), the heat-expandable base material layer (Y1), and the non-heat-expandable base material layer (Y2) are arranged in this order. The adhesive sheet according to any one of [1] to [4].
[6] Further having a pressure-sensitive adhesive layer (X2), the pressure-sensitive adhesive layer (X1), the base material layer (Y), and the pressure-sensitive adhesive layer (X2) are arranged in this order. The adhesive sheet according to any one of the above [1] to [5].
[7] The pressure-sensitive adhesive sheet according to the above [6], wherein the pressure-sensitive adhesive layer (X2) is an energy ray-curable pressure-sensitive adhesive layer that is cured by irradiating with energy rays to reduce the adhesive strength.
[8] A method for manufacturing a semiconductor device, which comprises the following steps 1A, 2A, a first separation step and a second separation step, using the pressure-sensitive adhesive sheet according to the above [6] or [7].
Step 1A: A process of attaching a processing object to the pressure-sensitive adhesive layer (X2) of the pressure-sensitive adhesive sheet, and attaching a support to the pressure-sensitive adhesive layer (X1) of the pressure-sensitive adhesive sheet Step 2A: A process of attaching a support to the pressure-sensitive adhesive layer (X1). On the other hand, a step of performing one or more treatments selected from a grinding treatment and an individualization treatment. First separation step: The pressure-sensitive adhesive sheet is heated to a temperature (t) or higher at which the heat-expandable particles start to expand, and described above. Step of separating the pressure-sensitive adhesive layer (X1) and the support Second separation step: Step of separating the pressure-sensitive adhesive layer (X2) from the object to be processed [9] Expansion start temperature of the heat-expandable particles (9) t) is 50 ° C or higher and lower than 125 ° C,
After the step 2A, a step 3A of attaching a thermosetting film to the surface of the processed object to be processed, which is opposite to the pressure-sensitive adhesive layer (X2), is included.
The first separation step is a step of heating the pressure-sensitive adhesive sheet to a temperature equal to or higher than the expansion start temperature (t) and lower than 125 ° C. to separate the pressure-sensitive adhesive layer (X1) from the support.
The method for manufacturing a semiconductor device according to the above [8].
[10] In the step 1A, the step of attaching the support to the pressure-sensitive adhesive layer (X1) of the pressure-sensitive adhesive sheet is the adhesion between the surface (SX1) of the pressure-sensitive adhesive layer ( _X1 ) and the support. The surface (S _s ) of the support is attached to the surface (S _X 1) of the adhesive layer (X1) while maintaining a state in which the surface (S _s ) to which the sheet is attached is substantially parallel. The method for manufacturing a semiconductor device according to the above [8] or [9], which is a step.
[11] A method for manufacturing a semiconductor device, which comprises the following steps 1B, 2B, a first separation step and a second separation step, using the pressure-sensitive adhesive sheet according to the above [6] or [7].
Step 1B: A process of attaching a processing object to the pressure-sensitive adhesive layer (X1) of the pressure-sensitive adhesive sheet, and attaching a support to the pressure-sensitive adhesive layer (X2) of the pressure-sensitive adhesive sheet Step 2B: A process of attaching a support to the pressure-sensitive adhesive layer (X2). On the other hand, a step of performing one or more treatments selected from a grinding treatment and an individualization treatment. First separation step: The pressure-sensitive adhesive sheet is heated to a temperature (t) or higher at which the heat-expandable particles start to expand, and described above. Step of separating the pressure-sensitive adhesive layer (X1) and the object to be processed Second separation step: Step of separating the pressure-sensitive adhesive layer (X2) and the support [12] Expansion start temperature of the heat-expandable particles (12) t) is 50 ° C or higher and lower than 125 ° C,
After the step 2B, a step 3B of attaching a thermosetting film to the surface of the processed object to be processed, which is opposite to the pressure-sensitive adhesive layer (X1), is included.
The first separation step is a step of heating the pressure-sensitive adhesive sheet to a temperature equal to or higher than the expansion start temperature (t) and lower than 125 ° C. to separate the pressure-sensitive adhesive layer (X1) from the object to be processed.
The method for manufacturing a semiconductor device according to the above [11].
[13] In the step 1B, the step of attaching the processing object to the pressure-sensitive adhesive layer (X1) of the pressure-sensitive adhesive sheet is the surface (SX1) of the pressure-sensitive adhesive layer ( _X1 ) and the processing target. The surface (S _w ) of the object to be processed is attached to the surface (SX1) of the adhesive layer ( _X1 ) while maintaining a substantially parallel state with the surface (S _w ) to which the adhesive sheet is attached. The method for manufacturing a semiconductor device according to the above [11] or [12], which is the step of manufacturing the semiconductor device.

According to the present invention, it is possible to provide an adhesive sheet having excellent adhesiveness and a method for manufacturing a semiconductor device using the adhesive sheet.

It is sectional drawing which shows an example of the structure of the pressure-sensitive adhesive sheet of this invention. It is sectional drawing which shows another example of the structure of the pressure-sensitive adhesive sheet of this invention. It is sectional drawing explaining an example of the process of the manufacturing method of the semiconductor device of this invention. It is sectional drawing explaining an example of the process of the manufacturing method of the semiconductor device of this invention. It is sectional drawing explaining an example of the process of the manufacturing method of the semiconductor device of this invention. It is sectional drawing explaining an example of the process of the manufacturing method of the semiconductor device of this invention. It is sectional drawing explaining an example of the process of the manufacturing method of the semiconductor device of this invention. It is sectional drawing explaining an example of the process of the manufacturing method of the semiconductor device of this invention. It is sectional drawing explaining an example of the process of the manufacturing method of the semiconductor device of this invention. It is a three-dimensional surface shape image of the pressure-sensitive adhesive sheet produced in Example 1. It is a three-dimensional surface shape image of the pressure-sensitive adhesive sheet produced in Comparative Example 9. It is an example of the appearance photograph of the test sample corresponding to the evaluation A of the stickability evaluation. It is an example of the appearance photograph of the test sample corresponding to the evaluation F of the stickability evaluation.

As used herein, the term "active ingredient" refers to a component contained in a target composition excluding a diluting solvent.
Further, in the present specification, the mass average molecular weight (Mw) is a value in terms of standard polystyrene measured by a gel permeation chromatography (GPC) method, and is specifically measured based on the method described in Examples. It is the value that was set.

As used herein, for example, "(meth) acrylic acid" refers to both "acrylic acid" and "methacrylic acid", as well as other similar terms.
Further, in the present specification, the lower limit value and the upper limit value described stepwise can be independently combined with respect to a preferable numerical range (for example, a range such as content). For example, from the description of "preferably 10 to 90, more preferably 30 to 60", "preferably lower limit value (10)" and "more preferable upper limit value (60)" are combined to obtain "10 to 60". You can also.

In the present specification, the "energy beam" means an electromagnetic wave or a charged particle beam having an energy quantum, and examples thereof include ultraviolet rays, radiation, and electron beams. Ultraviolet rays can be irradiated by using, for example, an electrodeless lamp, a high-pressure mercury lamp, a metal halide lamp, a UV-LED, or the like as an ultraviolet source. The electron beam can be irradiated with an electron beam generated by an electron beam accelerator or the like.
As used herein, the term "energy ray polymerizable" means the property of polymerizing by irradiating with energy rays. Further, "energy ray curable" means a property of being cured by irradiating with energy rays.

In the present specification, whether the "layer" is a "non-thermally expandable layer" or a "thermally expandable layer" is determined as follows.
When the layer to be determined contains the heat-expandable particles, the layer is heat-treated at the expansion start temperature (t) of the heat-expandable particles for 3 minutes. If the volume change rate calculated from the following formula is less than 5%, the layer is judged to be a "non-thermally expandable layer", and if it is 5% or more, the layer is a "thermally expandable layer". Judge that there is.
Volume change rate (%) = {(volume of the layer after heat treatment-volume of the layer before heat treatment) / volume of the layer before heat treatment} × 100
The layer that does not contain the heat-expandable particles is referred to as a "non-heat-expandable layer".

In the present specification, the "front surface" of the semiconductor wafer and the semiconductor chip refers to the surface on which the circuit is formed (hereinafter, also referred to as the "circuit surface"), and the "back surface" of the semiconductor wafer and the semiconductor chip is the circuit formed. Refers to the surface that is not.

In the present specification, the thickness of each layer is the thickness at 23 ° C., and means the value measured by the method described in the examples.

In the present specification, the adhesive force of each layer means the adhesive force to the mirror surface of the silicon mirror wafer, and is peeled off by 180 ° based on JIS Z0237: 2000 in an environment of 23 ° C. and 50% RH (relative humidity). It means the adhesive force measured at a tensile speed of 300 mm / min by the method.

[Adhesive sheet]
The adhesive sheet according to one aspect of the present invention is
It has a laminated structure including a pressure-sensitive adhesive layer (X1) and a base material layer (Y).
At least one of the pressure-sensitive adhesive layer (X1) and the base material layer (Y) is a heat-expandable layer containing heat-expandable particles.
The arithmetic mean swell (Wa) of the surface (SX1) of the pressure-sensitive adhesive layer ( _X1 ) opposite to the surface facing the base material layer (Y) is 0.090 μm or less.

In the pressure-sensitive adhesive sheet of one aspect of the present invention, the heat-expandable particles contained in the heat-expandable layer, which is at least one of the pressure-sensitive adhesive layer (X1) and the base material layer (Y), have an expansion start temperature (t) or higher. By heating to a temperature and expanding, unevenness is formed on the adhesive surface of the adhesive layer (X1), and the contact area between the adherend attached to the adhesive surface of the adhesive layer (X1) and the adhesive surface. Is greatly reduced. As a result, the adhesiveness between the adhesive surface of the pressure-sensitive adhesive layer (X1) and the adherend can be significantly reduced, and the pressure-sensitive adhesive sheet and the adherend can be easily separated.
Further, in the pressure-sensitive adhesive sheet of one aspect of the present invention, the arithmetic mean swell (Wa) of the surface (SX1) of the pressure-sensitive adhesive layer ( _X1 ) opposite to the surface facing the base material layer (Y) is 0. When it is 090 μm or less, the adhesiveness is excellent.
The arithmetic average roughness (Ra) of the adhesive surface may be noted as a factor that affects the adhesion of the adhesive sheet. However, according to the study by the present inventors, the arithmetic average roughness (Ra) of the pressure-sensitive adhesive sheet containing the heat-expandable particles is particularly high in the case where the sticking surfaces are stuck while maintaining a substantially parallel state. It has been found that sufficient adhesion cannot always be obtained simply by keeping)) small. This is because the adhesive sheet containing the heat-expandable particles improves the partial adhesion by increasing the micro-smoothness grasped from the arithmetic mean roughness (Ra), but the presence of the heat-expandable particles is present in the pressure-sensitive adhesive sheet. It is considered that this is because there is a slight waviness on the adhesive surface, which causes an air pool at the adhesive interface. On the other hand, the pressure-sensitive adhesive sheet according to one aspect of the present invention is excellent because it can suppress the generation of air pools by adjusting the arithmetic mean swell (Wa) representing a more macroscopic surface shape to a specific range of 0.090 μm or less. It is considered that it exhibits stickability.

<Structure of adhesive sheet>
In the pressure-sensitive adhesive sheet of one aspect of the present invention, at least one of the pressure-sensitive adhesive layer (X1) and the base material layer (Y) may be a heat-expandable layer containing heat-expandable particles.
When the base material layer (Y) is a heat-expandable layer containing heat-expandable particles, the base material layer (Y) is a heat-expandable base material layer (Y1) containing heat-expandable particles. ) And the non-thermally expandable base material layer (Y2) are laminated, and the pressure-sensitive adhesive layer (X1), the heat-expandable base material layer (Y1), and the non-heat-expandable base material layer are laminated. (Y2) and a pressure-sensitive adhesive sheet having a laminated structure in which are arranged in this order can be mentioned. Hereinafter, the pressure-sensitive adhesive sheet having the said structure may be referred to as "the pressure-sensitive adhesive sheet of the first aspect".
Further, in the pressure-sensitive adhesive sheet according to one aspect of the present invention, when the pressure-sensitive adhesive layer (X1) is a heat-expandable layer containing heat-expandable particles, the pressure-sensitive adhesive layer (X1) is a heat-expandable layer. ), And a pressure-sensitive adhesive sheet having a laminated structure including a base material layer (Y). Hereinafter, the pressure-sensitive adhesive sheet having the said structure may be referred to as "the pressure-sensitive adhesive sheet of the second aspect".

The structure of the pressure-sensitive adhesive sheet according to one aspect of the present invention may be any one having a laminated structure including a pressure-sensitive adhesive layer (X1) and a base material layer (Y), but depending on the application, the pressure-sensitive adhesive layer ( It may have a layer other than X1) and the base material layer (Y).
For example, when the pressure-sensitive adhesive sheet of one aspect of the present invention is used for processing an object to be processed, the pressure-sensitive adhesive sheet of one aspect of the present invention further comprises an adhesive layer (X2) from the viewpoint of improving the processability of the object to be processed. It has a structure having a laminated structure in which the pressure-sensitive adhesive layer (X1), the base material layer (Y), and the pressure-sensitive adhesive layer (X2) are arranged in this order (that is, the structure of a double-sided pressure-sensitive adhesive sheet). Is preferable. By having this structure, the object to be processed is attached to one of the adhesive layers (X1) and the adhesive layer (X2), and the support is attached to the other adhesive layer. Can be done. By fixing the object to be processed to the support via the adhesive sheet, vibration, misalignment, damage to the fragile object to be processed, etc. are suppressed when the object to be processed is processed. However, the processing accuracy and processing speed can be improved.
In the following description, unless otherwise specified, in the "double-sided pressure-sensitive adhesive sheet", the pressure-sensitive adhesive layer (X1), the base material layer (Y), and the pressure-sensitive adhesive layer (X2) are arranged in this order. It shall mean an adhesive sheet having a laminated structure.

The pressure-sensitive adhesive sheet according to one aspect of the present invention may have a release material on the pressure-sensitive adhesive surface of the pressure-sensitive adhesive layer (X1). Further, when the pressure-sensitive adhesive sheet according to one aspect of the present invention has the structure of a double-sided pressure-sensitive adhesive sheet, it has a release material on the pressure-sensitive adhesive surface of at least one of the pressure-sensitive adhesive layer (X1) and the pressure-sensitive adhesive layer (X2). May be good.

Next, the configuration of the pressure-sensitive adhesive sheet according to one aspect of the present invention will be described more specifically with reference to the drawings.

Examples of the pressure-sensitive adhesive sheet according to one aspect of the present invention include a pressure-sensitive adhesive sheet 1a having a pressure-sensitive adhesive layer (X1) on a base material layer (Y) as shown in FIG. 1 (a). The pressure-sensitive adhesive sheet 1a has a surface (SX1) of the pressure-sensitive adhesive layer ( _X1 ) having an arithmetic mean swell (Wa) of 0.090 μm or less on the side opposite to the surface facing the base material layer (Y).
The pressure-sensitive adhesive sheet according to one aspect of the present invention may have a structure in which the release material 10 is further provided on the pressure-sensitive adhesive surface of the pressure-sensitive adhesive layer (X1), as in the pressure-sensitive adhesive sheet 1b shown in FIG. 1 (b).

Examples of the pressure-sensitive adhesive sheet according to another aspect of the present invention include those having the structure of the double-sided pressure-sensitive adhesive sheet.
As the pressure-sensitive adhesive sheet having such a structure, for example, as shown in FIG. 2A, the pressure-sensitive adhesive sheet has a structure in which the base material layer (Y) is sandwiched between the pressure-sensitive adhesive layer (X1) and the pressure-sensitive adhesive layer (X2). A double-sided adhesive sheet 2a can be mentioned. The double-sided pressure-sensitive adhesive sheet 2a has a surface (SX1) of the pressure-sensitive adhesive layer ( _X1 ) having an arithmetic mean swell (Wa) of 0.090 μm or less on the side opposite to the surface facing the base material layer (Y). ..
Further, as in the double-sided adhesive sheet 2b shown in FIG. 2B, the release material 10a is further provided on the adhesive surface of the adhesive layer (X1), and the release material is further provided on the adhesive surface of the adhesive layer (X2). It may be configured to have 10b.

In the double-sided pressure-sensitive adhesive sheet 2b shown in FIG. 2B, the peeling force when the release material 10a is peeled from the pressure-sensitive adhesive layer (X1) and the peeling force when the release material 10b is peeled off from the pressure-sensitive adhesive layer (X2). When both release materials are pulled outward and attempted to be peeled off, a phenomenon may occur in which the pressure-sensitive adhesive layer is separated and peeled off along with the two release materials. From the viewpoint of suppressing such a phenomenon, it is preferable to use two types of release materials designed so that the two

release materials

10a and 10b have different release forces from the pressure-sensitive adhesive layers attached to each other.

As another aspect of the pressure-sensitive adhesive sheet, in the double-sided pressure-sensitive adhesive sheet 2a shown in FIG. 2A, one of the pressure-sensitive adhesive layers (X1) and the pressure-sensitive adhesive layer (X2) is peeled off on both sides. A double-sided adhesive sheet having a structure in which a laminated release material is wound in a roll shape may be used.

The pressure-sensitive adhesive sheet according to one aspect of the present invention may or may not have another layer between the base material layer (Y) and the pressure-sensitive adhesive layer (X1). .. Further, when the pressure-sensitive adhesive sheet according to one aspect of the present invention is the double-sided pressure-sensitive adhesive sheet, in addition to the above, another layer is provided between the base material layer (Y) and the pressure-sensitive adhesive layer (X2). It may also have no other layers.
However, the pressure-sensitive adhesive sheet of the first aspect is non-heat-expandable on the surface of the heat-expandable base layer (Y1) opposite to the pressure-sensitive adhesive layer (X1) from the viewpoint of suppressing expansion on the surface. It is preferable that the base material layer (Y2) is directly laminated. Further, in the pressure-sensitive adhesive sheet of the second aspect, it is preferable that a layer capable of suppressing expansion on the surface of the pressure-sensitive adhesive layer (X1) is directly laminated on the surface opposite to the pressure-sensitive surface. It is more preferable that the layer (Y) is directly laminated.

<Arithmetic Mean Waviness (Wa)>
In the pressure-sensitive adhesive sheet of one aspect of the present invention, the arithmetic mean swell (Wa) of the surface (SX1) of the pressure-sensitive adhesive layer ( _X1 ) opposite to the surface facing the base material layer (Y) is 0.090 μm or less. Is.
When the arithmetic mean waviness (Wa) of the surface (SX1) of the pressure-sensitive adhesive layer ( _X1 ) is 0.090 μm or less, excellent adhesiveness can be obtained.
On the other hand, if the arithmetic mean waviness (Wa) of the surface (SX1) of the pressure-sensitive adhesive layer ( _X1 ) exceeds 0.090 μm, sufficient adhesiveness may not be obtained.
In the present specification, the arithmetic mean swell (Wa) is measured according to JIS B0601: 2013, and more specifically, it is measured by the method described in Examples described later.
The arithmetic mean swell (Wa) of the surface (SX1) of the pressure-sensitive adhesive layer ( _X1 ) is preferably 0.089 μm or less, more preferably 0.088 μm, from the viewpoint of further improving the adhesiveness of the pressure-sensitive adhesive sheet. Below, it is more preferably 0.087 μm or less, and even more preferably 0.086 μm or less. Further, the lower limit of the arithmetic mean waviness (Wa) of the surface (SX1) of the pressure-sensitive adhesive layer ( _X1 ) is not particularly limited and may be 0 μm, but it is easy to peel off the pressure-sensitive adhesive layer (X1). From the viewpoint of maintaining a good balance, it is preferably 0.010 μm or more, more preferably 0.020 μm or more, still more preferably 0.030 μm or more, still more preferably 0.040 μm or more.
The arithmetic mean swell (Wa) of the surface (SX1) of the pressure-sensitive adhesive layer ( _X1 ) is, for example, the thickness of the pressure-sensitive adhesive layer (X1) and the base material layer (Y), and the heat-expandable particles in the heat-expandable layer. Content, production conditions of the pressure-sensitive adhesive composition (x-1) which is a material for forming the pressure-sensitive adhesive layer (X1) described later, the resin composition (y-1) which is a material for forming the base material layer (Y), and the like. Can be adjusted to the above range.

<Thermal expandable particles>
The heat-expandable particles used in the pressure-sensitive adhesive sheet of one aspect of the present invention may be particles that expand by heating, and the expansion start temperature (t) is appropriately selected depending on the use of the pressure-sensitive adhesive sheet.

By the way, in recent years, when a semiconductor chip is mounted on a substrate, the semiconductor chip is attached to the substrate via a thermosetting film-like adhesive called a die attach film (hereinafter, also referred to as "DAF"). The process is adopted.
The DAF is attached to one surface of the semiconductor wafer or a plurality of fragmented semiconductor chips, and is divided into the same shape as the semiconductor chip at the same time as the semiconductor wafer is fragmented or after being attached to the semiconductor chip. The semiconductor chip with DAF obtained by fragmenting is attached (diatached) to the substrate from the DAF side, and then the semiconductor chip and the substrate are fixed by thermosetting the DAF. At this time, the DAF needs to maintain the property of adhering by pressure sensitivity or heating until it is attached to the substrate. However, when the semiconductor chip with DAF is used as an adherend of a heat-release type adhesive sheet, the DAF is cured before the die attachment due to the heating when the heat-expandable particles are expanded, and the DAF with respect to the substrate is cured. Adhesive strength may decrease. It is desirable to suppress the decrease in the adhesive strength of the DAF because it causes a decrease in the bonding reliability between the semiconductor chip and the substrate. That is, it is desirable that the thermal change of the adherend is suppressed at the time of heat peeling.
From this point of view, in the pressure-sensitive adhesive sheet of one aspect of the present invention, the expansion start temperature (t) of the heat-expandable particles is preferably less than 125 ° C., more preferably 120 ° C. or lower, still more preferably 115 ° C. or lower, still more preferably. Is 110 ° C. or lower, more preferably 105 ° C. or lower.

Further, if the heat-expandable particles of the heat-release type adhesive sheet having a low expansion start temperature are used, the heat-expandable particles expand due to the temperature rise when grinding the adherend. There is. It is desirable that such unintended expansion of the heat-expandable particles is suppressed because it leads to unintended separation of the adherend, misalignment, and the like.
From this point of view, in the pressure-sensitive adhesive sheet of one aspect of the present invention, the expansion start temperature (t) of the heat-expandable particles is preferably 50 ° C. or higher, more preferably 55 ° C. or higher, still more preferably 60 ° C. or higher, still more preferably. Is 70 ° C. or higher.
In the present specification, the expansion start temperature (t) of the heat-expandable particles means a value measured based on the following method.

(Measurement method of expansion start temperature (t) of thermally expandable particles)
To an aluminum cup with a diameter of 6.0 mm (inner diameter 5.65 mm) and a depth of 4.8 mm, 0.5 mg of the heat-expandable particles to be measured are added, and an aluminum lid (diameter 5.6 mm, thickness 0. Prepare a sample on which 1 mm) is placed.
Using a dynamic viscoelasticity measuring device, the height of the sample is measured with a force of 0.01 N applied to the sample from the upper part of the aluminum lid by a pressurizer. Then, with a force of 0.01 N applied by the pressurizer, it is heated from 20 ° C. to 300 ° C. at a heating rate of 10 ° C./min, the amount of displacement of the pressurizer in the vertical direction is measured, and the displacement in the positive direction is measured. The displacement start temperature is defined as the expansion start temperature (t).

The heat-expandable particles are microencapsulated foaming agents composed of an outer shell made of a thermoplastic resin and an inner shell component contained in the outer shell and vaporized when heated to a predetermined temperature. It is preferable to have.
Examples of the thermoplastic resin constituting the outer shell of the microencapsulating foaming agent include polyvinyl alcohol, polyvinyl butyral, polymethylmethacrylate, polyacrylonitrile, polyvinylidene chloride, polysulfone, and structural units contained in these thermoplastic resins. Examples thereof include a copolymer obtained by polymerizing two or more kinds of monomers to be formed.

Examples of the contained components that are contained in the outer shell of the microencapsulating foaming agent include propane, propylene, butene, n-butane, isopentane, isopentane, neopentane, n-pentane, n-hexane, isohexane, and n-. Examples thereof include low boiling point liquids such as heptane, n-octane, cyclopropane, cyclobutane and petroleum ether.
Among these, from the viewpoint of suppressing the thermal change of the adherend at the time of heat peeling and suppressing the unintentional expansion of the heat-expandable particles due to the temperature rise such as when grinding the adherend. When the expansion start temperature (t) of the expandable particles is 50 ° C. or higher and lower than 125 ° C., the contained components are preferably propane, isobutane, n-pentane, and cyclopropane.
One of these inclusion components may be used alone, or two or more thereof may be used in combination.
The expansion start temperature (t) of the heat-expandable particles can be adjusted by appropriately selecting the type of the inclusion component.

The average particle size of the heat-expandable particles used in one embodiment of the present invention before expansion at 23 ° C. is preferably 3 to 100 μm, more preferably 4 to 70 μm, still more preferably 6 to 60 μm, still more preferably 10 to. It is 50 μm.
The average particle size of the thermally expandable particles before expansion is the volume medium particle size ( _D50 ), and is a laser diffraction type particle size distribution measuring device (for example, manufactured by Malvern, product name “Mastersizer 3000”). In the particle distribution of the thermally expandable particles before expansion measured using the above, it means the particle diameter corresponding to the cumulative volume frequency of 50% calculated from the smaller particle diameter of the thermally expandable particles before expansion.

The 90% particle diameter (D ₉₀ ) of the heat-expandable particles used in one embodiment of the present invention before expansion at 23 ° C. is preferably 10 to 150 μm, more preferably 15 to 100 μm, still more preferably 20 to 90 μm. Even more preferably, it is 25 to 80 μm.
The 90% particle size (D ₉₀ ) of the thermally expandable particles before expansion is the expansion measured using a laser diffraction type particle size distribution measuring device (for example, manufactured by Malvern, product name “Mastersizer 3000”). In the particle distribution of the previous heat-expandable particles, it means the particle size in which the cumulative volume frequency calculated from the smaller particle size of the heat-expandable particles before expansion corresponds to 90%.

The maximum volume expansion rate when the thermally expandable particles used in one embodiment of the present invention are heated to a temperature equal to or higher than the expansion start temperature (t) is preferably 1.5 to 200 times, more preferably 2 to 150 times, and further. It is preferably 2.5 to 120 times, more preferably 3 to 100 times.

The content of the heat-expandable particles in the heat-expandable layer is preferably 1% by mass or more, more preferably 2% by mass or more, still more preferably 3 with respect to the total mass (100% by mass) of the heat-expandable layer. By mass or more, more preferably 4% by mass or more. The content of the heat-expandable particles in the heat-expandable layer is preferably 25% by mass or less, more preferably 23% by mass or less, still more preferably 23% by mass, based on the total mass (100% by mass) of the heat-expandable layer. Is 22% by mass or less, more preferably 21% by mass or less.
When the content of the heat-expandable particles is 1% by mass or more, the peelability at the time of heat peeling tends to be improved. Further, when the content of the heat-expandable particles is 25% by mass or less, the generation of unevenness caused by the heat-expandable particles before the heat expansion is suppressed, and the arithmetic of the surface (S _x1 ) of the pressure-sensitive adhesive layer (X1) is performed. The average swell (Wa) can be further reduced, and the stickability tends to be improved.

<Thickness of thermally expandable layer>
In one aspect of the present invention, the thickness of the thermally expandable layer before thermal expansion is preferably 30 to 300 μm, more preferably 40 to 270 μm, still more preferably 50 to 240 μm, still more preferably 55 to 220 μm.
When the thickness of the heat-expandable layer before thermal expansion is 30 μm or more, the generation of unevenness caused by the heat-expandable particles before thermal expansion is suppressed, and the arithmetic of the surface (S _x1 ) of the pressure-sensitive adhesive layer (X1) is performed. The average swell (Wa) can be further reduced, and the stickability tends to be improved. Further, when the thickness of the heat-expandable layer before thermal expansion is 300 μm or less, the pressure-sensitive adhesive sheet tends to be easy to handle.

Next, a preferred embodiment of each layer of the pressure-sensitive adhesive sheet according to one aspect of the present invention will be described.
Hereinafter, suitable embodiments of the pressure-sensitive adhesive sheet of the first aspect and the pressure-sensitive adhesive sheet of the second aspect will be described, but the present invention is not limited to these embodiments.

[Adhesive sheet of the first aspect]
The pressure-sensitive adhesive sheet of the first aspect has a laminated structure in which a pressure-sensitive adhesive layer (X1), a heat-expandable base material layer (Y1), and a non-heat-expandable base material layer (Y2) are arranged in this order. It is an adhesive sheet to have.
In the pressure-sensitive adhesive sheet of the first aspect, since the heat-expandable particles are contained in the base material layer (Y), irregularities due to the heat-expandable particles appear as waviness of the surface (S _x1 ) of the pressure-sensitive adhesive layer (X1). It becomes difficult to do. Further, since the pressure-sensitive adhesive layer (X1) does not have to contain thermally expandable particles, it has a high degree of freedom in designing the thickness, resin composition, etc., further reduces the arithmetic mean waviness (Wa), and has stickability. Tends to improve.

<Adhesive layer (X1)>
The pressure-sensitive adhesive layer (X1) included in the pressure-sensitive adhesive sheet of the first aspect may be a heat-expandable layer or a non-heat-expandable layer, but is preferably a non-heat-expandable layer.
When the pressure-sensitive adhesive layer (X1) is a non-thermally expandable layer, the volume change rate (%) of the pressure-sensitive adhesive layer (X1) calculated from the above formula is less than 5%, preferably less than 2%. It is preferably less than 1%, more preferably less than 0.1%, and even more preferably less than 0.01%.
The pressure-sensitive adhesive layer (X1) in the pressure-sensitive adhesive sheet of the first aspect preferably does not contain the heat-expandable particles, but may contain the heat-expandable particles within a range not contrary to the object of the present invention. When the pressure-sensitive adhesive layer (X1) contains thermally expandable particles, the smaller the content, the more preferable, and the content is preferably less than 3% by mass, based on the total mass (100% by mass) of the pressure-sensitive adhesive layer (X1). It is preferably less than 1% by mass, more preferably less than 0.1% by mass, still more preferably less than 0.01% by mass, and even more preferably less than 0.001% by mass.

The pressure-sensitive adhesive layer (X1) included in the pressure-sensitive adhesive sheet of the first aspect can be formed from the pressure-sensitive adhesive composition (x-1) containing a pressure-sensitive adhesive resin.
Hereinafter, each component contained in the pressure-sensitive adhesive composition (x-1) will be described.

(Adhesive resin)
Examples of the adhesive resin include polymers having adhesiveness by themselves and having a mass average molecular weight (Mw) of 10,000 or more.
The mass average molecular weight (Mw) of the adhesive resin is preferably 10,000 to 2 million, more preferably 20,000 to 1.5 million, still more preferably 30,000 to 100, from the viewpoint of improving the adhesive strength of the adhesive layer (X1). It is 10,000.

Specific examples of the adhesive resin include rubber-based resins such as acrylic resins, urethane-based resins, and polyisobutylene-based resins, polyester-based resins, olefin-based resins, silicone-based resins, and polyvinyl ether-based resins.
These adhesive resins may be used alone or in combination of two or more.
When these adhesive resins are copolymers having two or more kinds of structural units, the form of the copolymer is not particularly limited, and the block copolymer, the random copolymer, and the graft are co-polymerized. It may be any of the polymers.

Here, in one aspect of the present invention, it is preferable that the adhesive resin contains an acrylic resin from the viewpoint of exhibiting excellent adhesive force in the adhesive layer (X1).

The content of the acrylic resin in the adhesive resin is preferably 30 with respect to the total amount (100% by mass) of the adhesive resin contained in the adhesive composition (x-1) or the adhesive layer (X1). It is -100% by mass, more preferably 50 to 100% by mass, still more preferably 70 to 100% by mass, still more preferably 85 to 100% by mass.

In one aspect of the present invention, the acrylic resin that can be used as the adhesive resin includes, for example, a polymer containing a structural unit derived from an alkyl (meth) acrylate having a linear or branched alkyl group, and a cyclic structure. Examples thereof include a polymer containing a structural unit derived from (meth) acrylate having.

The mass average molecular weight (Mw) of the acrylic resin is preferably 100,000 to 1,500,000, more preferably 200,000 to 1,300,000, still more preferably 350,000 to 1,200,000, and even more preferably 500,000 to 1,100,000. ..

The acrylic resin used in one embodiment of the present invention includes a structural unit (a1) derived from an alkyl (meth) acrylate (a1') (hereinafter, also referred to as “monomer (a1 ′)”) and a functional group-containing monomer (a2). ') (Hereinafter, also referred to as “monomer (a2')”), an acrylic copolymer (A1) having a structural unit (a2) is more preferable.

The number of carbon atoms of the alkyl group of the monomer (a1') is preferably 1 to 24, more preferably 1 to 12, and even more preferably 2 from the viewpoint of exhibiting excellent adhesive strength in the pressure-sensitive adhesive layer (X1). It is -10, more preferably 4-8.
The alkyl group of the monomer (a1') may be a linear alkyl group or a branched chain alkyl group.

Examples of the monomer (a1') include methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, n-butyl (meth) acrylate, sec-butyl (meth) acrylate, and iso-butyl (meth). Examples thereof include acrylate, tert-butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, lauryl (meth) acrylate, tridecyl (meth) acrylate, and stearyl (meth) acrylate.
These monomers (a1') may be used alone or in combination of two or more.
As the monomer (a1'), n-butyl acrylate and 2-ethylhexyl acrylate are preferable.

The content of the structural unit (a1) is preferably 50 to 99.9% by mass, more preferably 60 to 99.0% by mass, based on the total structural unit (100% by mass) of the acrylic copolymer (A1). %, More preferably 70 to 97.0% by mass, still more preferably 80 to 95.0% by mass.

Examples of the functional group of the monomer (a2') include a hydroxyl group, a carboxy group, an amino group, an epoxy group and the like.
That is, examples of the monomer (a2') include a hydroxyl group-containing monomer, a carboxy group-containing monomer, an amino group-containing monomer, and an epoxy group-containing monomer.
These monomers (a2') may be used alone or in combination of two or more.
Among these, as the monomer (a2'), a hydroxyl group-containing monomer and a carboxy group-containing monomer are preferable, and a hydroxyl group-containing monomer is more preferable.

Examples of the hydroxyl group-containing monomer include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, and 3-hydroxybutyl (meth). ) Hydroxyalkyl (meth) acrylates such as acrylates and 4-hydroxybutyl (meth) acrylates; hydroxyl group-containing compounds such as unsaturated alcohols such as vinyl alcohols and allyl alcohols.

Examples of the carboxy group-containing monomer include ethylenically unsaturated monocarboxylic acids such as (meth) acrylic acid and crotonic acid; ethylenically unsaturated dicarboxylic acids such as fumaric acid, itaconic acid, maleic acid and citraconic acid and their anhydrides thereof. , 2- (Acryloyloxy) ethyl succinate, 2-carboxyethyl (meth) acrylate and the like.

The content of the structural unit (a2) is preferably 0.1 to 30% by mass, more preferably 0.5 to 20% by mass, based on the total structural unit (100% by mass) of the acrylic copolymer (A1). %, More preferably 1.0 to 15% by mass, still more preferably 3.0 to 10% by mass.

The acrylic copolymer (A1) may further have a structural unit (a3) derived from a monomer (a3') other than the monomers (a1') and (a2').
In the acrylic copolymer (A1), the total content of the structural units (a1) and (a2) is preferably relative to the total structural units (100% by mass) of the acrylic copolymer (A1). It is 70 to 100% by mass, more preferably 80 to 100% by mass, still more preferably 90 to 100% by mass, and even more preferably 95 to 100% by mass.

Examples of the monomer (a3') include olefins such as ethylene, propylene and isobutylene; halogenated olefins such as vinyl chloride and vinylidene chloride; diene monomers such as butadiene, isoprene and chloroprene; cyclohexyl (meth) acrylates, It has a cyclic structure such as benzyl (meth) acrylate, isobornyl (meth) acrylate, dicyclopentanyl (meth) acrylate, dicyclopentenyl (meth) acrylate, dicyclopentenyloxyethyl (meth) acrylate, and imide (meth) acrylate. (Meta) Acrylate; Examples thereof include styrene, α-methylstyrene, vinyltoluene, vinyl formate, vinyl acetate, acrylonitrile, (meth) acrylamide, (meth) acrylonitrile, (meth) acryloylmorpholine, and N-vinylpyrrolidone.

The content of the tacky resin in the pressure-sensitive adhesive composition (x-1) is preferably 35 to 100% by mass with respect to the total amount (100% by mass) of the active ingredient of the pressure-sensitive adhesive composition (x-1). It is more preferably 50 to 100% by mass, further preferably 60 to 100% by mass, and even more preferably 70 to 99.5% by mass.

(Crosslinking agent)
In one aspect of the present invention, when the pressure-sensitive adhesive composition (x-1) contains a pressure-sensitive adhesive resin having a functional group like the above-mentioned acrylic copolymer (A1), it further contains a cross-linking agent. Is preferable.
The cross-linking agent reacts with a pressure-sensitive adhesive resin having a functional group to cross-link the pressure-sensitive adhesive resins using the functional group as a cross-linking starting point.

Examples of the cross-linking agent include an isocyanate-based cross-linking agent, an epoxy-based cross-linking agent, an aziridine-based cross-linking agent, a metal chelate-based cross-linking agent, and the like.
These cross-linking agents may be used alone or in combination of two or more.
Among these cross-linking agents, isocyanate-based cross-linking agents are preferable from the viewpoint of increasing the cohesive force and improving the adhesive force, and from the viewpoint of easy availability.
Examples of the isocyanate-based cross-linking agent include aromatic polyisocyanates such as tolylene diisocyanate, diphenylmethane diisocyanate, and xylylene diisocyanate; dicyclohexylmethane-4,4'-diisocyanate, bicycloheptane triisocyanate, cyclopentylene diisocyanate, and cyclohexylene diisocyanate. Alicyclic polyisocyanates such as methylcyclohexylene diisocyanate, methylenebis (cyclohexyl isocyanate), 3-isocyanate methyl-3,5,5-trimethylcyclohexyl isocyanate, hydrogenated xylylene diisocyanate; hexamethylene diisocyanate, trimethylhexamethylene diisocyanate, lysine diisocyanate Such as acyclic aliphatic polyisocyanates; and the like, polyhydric isocyanate compounds and the like can be mentioned.
Examples of the isocyanate-based cross-linking agent include a trimethylolpropane adduct-type modified product of the polyhydric isocyanate compound, a burette-type modified product reacted with water, and an isocyanurate-type modified product containing an isocyanurate ring.
Among these, a polyhydric isocyanate compound is used from the viewpoint of suppressing a decrease in the elastic coefficient of the pressure-sensitive adhesive layer (X1) during heating and suppressing the adhesion of the residue derived from the pressure-sensitive adhesive layer (X1) to the adherend. It is preferable to use the trimethylolpropane adduct-type modified product of trimethylolpropane adduct type, more preferably to use the trimethylolpropane adduct type modified product of the aromatic polyisocyanate compound, and further to use the trimethylolpropane adduct type modified product of the trimethylolpropane adduct type product of tolylene diisocyanate. preferable.

The content of the cross-linking agent is appropriately adjusted depending on the number of functional groups of the adhesive resin, and is preferably 0.01 to 10 parts by mass with respect to 100 parts by mass of the adhesive resin having functional groups. It is more preferably 0.03 to 7 parts by mass, and further preferably 0.05 to 5 parts by mass.

(Adhesive)
In one aspect of the present invention, the pressure-sensitive adhesive composition (x-1) may further contain a pressure-sensitive adhesive from the viewpoint of further improving the pressure-sensitive adhesive strength.
As used herein, the term "adhesive-imparting agent" refers to a component that supplementarily improves the adhesive strength of the adhesive resin and has a mass average molecular weight (Mw) of less than 10,000, and is the above-mentioned adhesive resin. Is distinct from.
The mass average molecular weight (Mw) of the tackifier is less than 10,000, preferably 400 to 9,000, more preferably 500 to 8,000, still more preferably 800 to 5,000.

As the tackifier, for example, a C5 fraction such as rosin-based resin, terpene-based resin, styrene-based resin, pentene, isoprene, piperin, and 1,3-pentaziene produced by thermal decomposition of petroleum naphtha is copolymerized. Examples thereof include C5 petroleum resin, C9 petroleum resin obtained by copolymerizing C9 fractions such as inden produced by thermal decomposition of petroleum naphtha and vinyl toluene, and hydrides obtained by hydrogenating these.

The softening point of the tackifier is preferably 60 to 170 ° C, more preferably 65 to 160 ° C, and even more preferably 70 to 150 ° C.
In the present specification, the "softening point" of the tackifier means a value measured according to JIS K 2531.
As the tackifier, one type may be used alone, or two or more types having different softening points, structures, etc. may be used in combination. When two or more kinds of tackifiers are used, it is preferable that the weighted average of the softening points of the plurality of tackifiers belongs to the above range.

The content of the tackifier is preferably 0.01 to 65% by mass, more preferably 0.1 to 50% by mass, based on the total amount (100% by mass) of the active ingredient of the pressure-sensitive adhesive composition (x-1). %, More preferably 1 to 40% by mass, still more preferably 2 to 30% by mass.

(Additive for adhesive)
In one aspect of the present invention, the pressure-sensitive adhesive composition (x-1) is an additive for a pressure-sensitive adhesive used for a general pressure-sensitive adhesive in addition to the above-mentioned additives as long as the effect of the present invention is not impaired. May be contained.
Examples of such additives for adhesives include antioxidants, softeners (plasticizers), rust inhibitors, pigments, dyes, retarders, reaction promoters (catalysts), ultraviolet absorbers, and energy rays described later. Examples thereof include curable compounds and photopolymerization initiators.
These adhesive additives may be used alone or in combination of two or more.

When these adhesive additives are contained, the content of each adhesive additive is independently, preferably 0.0001 to 20 parts by mass, based on 100 parts by mass of the adhesive resin. It is preferably 0.001 to 10 parts by mass.

(Adhesive strength of the pressure-sensitive adhesive layer (X1) before the heat-expandable base material layer (Y1) is thermally expanded)
The adhesive strength of the pressure-sensitive adhesive layer (X1) before the heat-expandable base material layer (Y1) is thermally expanded is preferably 0.1 to 12.0 N / 25 mm, more preferably 0.5 to 9.0 N / 25 mm. It is more preferably 1.0 to 8.0 N / 25 mm, and even more preferably 1.2 to 7.5 N / 25 mm.
If the adhesive strength of the pressure-sensitive adhesive layer (X1) before the heat-expandable base material layer (Y1) is thermally expanded is 0.1 N / 25 mm or more, unintentional peeling or adhesion from the adherend during temporary fixing is performed. It is possible to more effectively suppress the displacement of the body. On the other hand, when the adhesive strength is 12.0 N / 25 mm or less, the peelability at the time of heat peeling can be further improved.
The adhesive force of the adhesive layer (X1) at 23 ° C. before thermal expansion can be measured by the above method.

(Adhesive strength of the pressure-sensitive adhesive layer (X1) at 23 ° C. after the heat-expandable base material layer (Y1) is thermally expanded)
The adhesive strength of the pressure-sensitive adhesive layer (X1) at 23 ° C. after the heat-expandable base material layer (Y1) is thermally expanded is preferably 1.5 N / 25 mm or less, more preferably 0.05 N / 25 mm or less, and further. It is preferably 0.01 N / 25 mm or less, and even more preferably 0 N / 25 mm. The adhesive force of 0 N / 25 mm means the adhesive force below the measurement limit in the method for measuring the adhesive force after thermal expansion described later, and the adhesive force is applied when the adhesive sheet is fixed for measurement. It also includes cases where it is too small to peel off unintentionally.
The adhesive strength of the pressure-sensitive adhesive layer (X1) at 23 ° C. after the heat-expandable base material layer (Y1) is thermally expanded is that of the heat-expandable particles contained in the heat-expandable base material layer (Y1). The pressure-sensitive adhesive sheet heated at the expansion start temperature of + 22 ° C. for 1 minute can be measured by the above method.

(Thickness of adhesive layer (X1))
The thickness of the pressure-sensitive adhesive layer (X1) contained in the pressure-sensitive adhesive sheet of the first aspect exhibits good adhesive strength, and when the heat-expandable particles are expanded by heating, the pressure-sensitive adhesive layer (X1) adheres to the pressure-sensitive adhesive layer (X1). From the viewpoint of satisfactorily forming irregularities on the surface, the thickness is preferably 3 to 10 μm, more preferably 3 to 8 μm, and even more preferably 3 to 7 μm.
By adjusting the thickness of the pressure-sensitive adhesive layer (X1) to the above range, it is possible to easily form the pressure-sensitive adhesive layer (X1), and the adhesive surface of the pressure-sensitive adhesive layer (X1) is satisfactorily formed with irregularities. It can be made easy.

<Thermal expandable base material layer (Y1)>
The heat-expandable base material layer (Y1) included in the pressure-sensitive adhesive sheet of the first aspect is a heat-expandable layer containing heat-expandable particles in a resin material, and is a pressure-sensitive adhesive layer (X1) and a non-heat-expandable group. It is a layer provided between the material layer (Y2) and the material layer (Y2).

The heat-expandable base material layer (Y1) is preferably a non-adhesive base material.
The probe tack value on the surface of the heat-expandable substrate layer (Y1) is usually less than 50 mN / 5 mmφ, preferably less than 30 mN / 5 mmφ, more preferably less than 10 mN / 5 mmφ, still more preferably less than 5 mN / 5 mmφ. ..
In the present specification, the probe tack value on the surface of the base material means a value measured by the following method.
<Probe tack value>
After cutting the base material to be measured into squares with a side of 10 mm, the test sample was allowed to stand in an environment of 23 ° C. and 50% RH (relative humidity) for 24 hours, and used as a test sample at 23 ° C. and 50% RH (relative humidity). ), The probe tack value on the surface of the test sample is measured according to JIS Z0237: 1991 using a tacking tester (manufactured by Nippon Special Instruments Co., Ltd., product name "NTS-4800"). be able to. Specifically, a stainless steel probe having a diameter of 5 mm is brought into contact with the surface of the test sample at a contact load of 0.98 N / cm ² for 1 second, and then the probe is brought into contact with the surface of the test sample at a speed of 10 mm / sec. The force required to separate from the surface can be measured and the resulting value can be used as the probe tack value for the test sample.

From the viewpoint of improving the interlayer adhesion between the heat-expandable base material layer (Y1) and other layers to be laminated, the surface of the heat-expandable base material layer (Y1) is surfaced by an oxidation method, an unevenness method, or the like. Treatment, easy adhesion treatment, or primer treatment may be performed.
Examples of the oxidation method include corona discharge treatment, plasma discharge treatment, chromic acid treatment (wet), hot air treatment, ozone, ultraviolet irradiation treatment and the like, and examples of the unevenness method include a sandblast method and a solvent treatment method. Can be mentioned.

The heat-expandable base material layer (Y1) is preferably formed from the resin composition (y-1) containing the resin and the heat-expandable particles.
Hereinafter, preferred embodiments of the resin composition (y-1) will be described. The preferred embodiment of the heat-expandable particles is as described above.

(resin)
The resin contained in the resin composition (y-1) may be a non-adhesive resin or an adhesive resin.
That is, even if the resin contained in the resin composition (y-1) is an adhesive resin, the adhesiveness is obtained in the process of forming the heat-expandable base material layer (Y1) from the resin composition (y-1). It is sufficient that the resin polymerizes with the polymerizable compound, the obtained resin becomes a non-adhesive resin, and the heat-expandable base material layer (Y1) containing the resin becomes non-adhesive.

The mass average molecular weight (Mw) of the resin contained in the resin composition (y-1) is preferably 1,000 to 1,000,000, more preferably 1,000 to 700,000, still more preferably 1,000 to 50. It is 10,000.
When the resin is a copolymer having two or more kinds of structural units, the form of the copolymer is not particularly limited, and any of a block copolymer, a random copolymer, and a graft copolymer is used. It may be.

The content of the resin is preferably 50 to 99% by mass, more preferably 60 to 95% by mass, and further preferably 65 to 65% by mass, based on the total amount (100% by mass) of the active ingredient of the resin composition (y-1). It is 90% by mass, more preferably 70 to 85% by mass.

The resin contained in the resin composition (y-1) is used from the viewpoint of facilitating the formation of irregularities on the adhesive surface of the pressure-sensitive adhesive layer (X1) and from the viewpoint of improving the sheet shape retention after thermal expansion. It is preferable to contain at least one selected from the group consisting of acrylic urethane-based resins and olefin-based resins. That is, the heat-expandable base material layer (Y1) preferably contains at least one selected from the group consisting of acrylic urethane-based resins and olefin-based resins.
Further, as the acrylic urethane resin, the following resin (U1) is preferable.
An acrylic urethane resin (U1) obtained by polymerizing a urethane prepolymer (UP) and a vinyl compound containing a (meth) acrylic acid ester.
In addition, in this specification, a prepolymer means a compound which is made by polymerizing a monomer, and can form a polymer by further polymerization.

[Acrylic urethane resin (U1)]
Examples of the urethane prepolymer (UP) that becomes the main chain of the acrylic urethane resin (U1) include a reaction product of a polyol and a polyhydric isocyanate.
The urethane prepolymer (UP) is preferably obtained by further performing a chain extension reaction using a chain extender.

Examples of the polyol which is a raw material of the urethane prepolymer (UP) include an alkylene type polyol, an ether type polyol, an ester type polyol, an ester amide type polyol, an ester ether type polyol, and a carbonate type polyol.
These polyols may be used alone or in combination of two or more.
As the polyol used in one aspect of the present invention, diols are preferable, ester-type diols, alkylene-type diols and carbonate-type diols are more preferable, and ester-type diols and carbonate-type diols are even more preferable.

Examples of the ester-type diol include alkanediols such as 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, neopentyl glycol, and 1,6-hexanediol; ethylene glycol, propylene glycol, and the like. One or more selected from diols such as diethylene glycol and alkylene glycol such as dipropylene glycol; and phthalic acid, isophthalic acid, terephthalic acid, naphthalenedicarboxylic acid, 4,4-diphenyldicarboxylic acid, diphenylmethane-4. , 4'-dicarboxylic acid, succinic acid, adipic acid, azelaic acid, sebacic acid, het acid, maleic acid, fumaric acid, itaconic acid, cyclohexane-1,3-dicarboxylic acid, cyclohexane-1,4-dicarboxylic acid, hexa Examples thereof include dicarboxylic acids such as hydrophthalic acid, hexahydroisophthalic acid, hexahydroterephthalic acid, and methylhexahydrophthalic acid, and a condensed polymer of one or more selected from these anhydrides.
Specifically, polyethylene adipate diol, polybutylene adipate diol, polyhexamethylene adipate diol, polyhexamethylene isophthalate diol, polyneopentyl adipate diol, polyethylene propylene adipate diol, polyethylene butylene adipate diol, polybutylene hexamethylene adipate diol, Polydiethylene adipate diol, poly (polytetramethylene ether) adipate diol, poly (3-methylpentylene adipate) diol, polyethylene azelate diol, polyethylene sebacate diol, polybutylene azelate diol, polybutylene sebacate diol, polyneo Examples thereof include pentyl terephthalate diol.

Examples of the alkylene-type diol include alkane diols such as 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, neopentyl glycol, and 1,6-hexanediol; ethylene glycol, propylene glycol, and the like. Examples thereof include alkylene glycols such as diethylene glycol and dipropylene glycol; polyalkylene glycols such as polyethylene glycol, polypropylene glycol and polybutylene glycol; and polyoxyalkylene glycols such as polytetramethylene glycol.

Examples of the carbonate type diol include 1,4-tetramethylene carbonate diol, 1,5-pentamethylene carbonate diol, 1,6-hexamethylene carbonate diol, 1,2-propylene carbonate diol, and 1,3-propylene carbonate diol. , 2,2-Dimethylpropylene carbonate diol, 1,7-heptamethylene carbonate diol, 1,8-octamethylene carbonate diol, 1,4-cyclohexane carbonate diol and the like.

Examples of the polyhydric isocyanate used as a raw material for the urethane prepolymer (UP) include aromatic polyisocyanates, aliphatic polyisocyanates, and alicyclic polyisocyanates.
These polyvalent isocyanates may be used alone or in combination of two or more.
Further, these polyvalent isocyanates may be a trimethylolpropane adduct-type modified product, a biuret-type modified product reacted with water, or an isocyanurate-type modified product containing an isocyanurate ring.

Among these, the polyvalent isocyanate used in one embodiment of the present invention is preferably diisocyanate, 4,4'-diphenylmethane diisocyanate (MDI), 2,4-tolylene diisocyanate (2,4-TDI), 2,6. -One or more selected from tolylene diisocyanate (2,6-TDI), hexamethylene diisocyanate (HMDI), and alicyclic diisocyanate are more preferable.

Examples of the alicyclic diisocyanate include 3-isocyanate methyl-3,5,5-trimethylcyclohexylisocyanate (isophorone diisocyanate, IPDI), 1,3-cyclopentane diisocyanate, 1,3-cyclohexanediisocyanate, and 1,4-cyclohexane. Examples thereof include diisocyanate, methyl-2,4-cyclohexanediisocyanate, methyl-2,6-cyclohexanediisocyanate, and isophorone diisocyanate (IPDI) is preferable.

In one embodiment of the present invention, the urethane prepolymer (UP) which is the main chain of the acrylic urethane resin (U1) is a reaction product of a diol and a diisocyanate, and is a straight chain having ethylenically unsaturated groups at both ends. Urethane prepolymers are preferred.
As a method of introducing an ethylenically unsaturated group into both ends of the linear urethane prepolymer, an NCO group at the terminal of the linear urethane prepolymer formed by reacting a diol and a diisocyanate compound and a hydroxyalkyl (meth) acrylate are used. There is a method of reacting with.

Examples of the hydroxyalkyl (meth) acrylate include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, and 3-hydroxy. Examples thereof include butyl (meth) acrylate and 4-hydroxybutyl (meth) acrylate.

The vinyl compound that becomes the side chain of the acrylic urethane resin (U1) contains at least (meth) acrylic acid ester.
As the (meth) acrylic acid ester, one or more selected from alkyl (meth) acrylates and hydroxyalkyl (meth) acrylates are preferable, and alkyl (meth) acrylates and hydroxyalkyl (meth) acrylates are more preferably used in combination.

When the alkyl (meth) acrylate and the hydroxyalkyl (meth) acrylate are used in combination, the mixing ratio of the hydroxyalkyl (meth) acrylate to 100 parts by mass of the alkyl (meth) acrylate is preferably 0.1 to 100 parts by mass. It is preferably 0.5 to 30 parts by mass, more preferably 1.0 to 20 parts by mass, and even more preferably 1.5 to 10 parts by mass.

The alkyl group of the alkyl (meth) acrylate has preferably 1 to 24 carbon atoms, more preferably 1 to 12, still more preferably 1 to 8, and even more preferably 1 to 3.

Further, as the hydroxyalkyl (meth) acrylate, the same hydroxyalkyl (meth) acrylate used for introducing an ethylenically unsaturated group into both ends of the above-mentioned linear urethane prepolymer can be mentioned.

Examples of vinyl compounds other than (meth) acrylic acid ester include aromatic hydrocarbon-based vinyl compounds such as styrene, α-methylstyrene and vinyltoluene; vinyl ethers such as methyl vinyl ether and ethyl vinyl ether; vinyl acetate and vinyl propionate. , (Meta) acrylonitrile, N-vinylpyrrolidone, (meth) acrylic acid, maleic acid, fumaric acid, itaconic acid, meta (acrylamide) and other polar group-containing monomers; and the like.
These may be used alone or in combination of two or more.

The content of the (meth) acrylic acid ester in the vinyl compound is preferably 40 to 100% by mass, more preferably 65 to 100% by mass, still more preferably, based on the total amount (100% by mass) of the vinyl compound. It is 80 to 100% by mass, more preferably 90 to 100% by mass.

The total content of the alkyl (meth) acrylate and the hydroxyalkyl (meth) acrylate in the vinyl compound is preferably 40 to 100% by mass, more preferably 65 to 100% by mass, based on the total amount (100% by mass) of the vinyl compound. It is 100% by mass, more preferably 80 to 100% by mass, and even more preferably 90 to 100% by mass.

The acrylic urethane resin (U1) used in one embodiment of the present invention is obtained by mixing a urethane prepolymer (UP) and a vinyl compound containing a (meth) acrylic acid ester and polymerizing both.
In the polymerization, it is preferable to further add a radical initiator.

In the acrylic urethane resin (U1) used in one embodiment of the present invention, the content ratio of the structural unit (u11) derived from the urethane prepolymer (UP) and the structural unit (u12) derived from the vinyl compound [(u11). ) / (U12)], preferably 10/90 to 80/20, more preferably 20/80 to 70/30, still more preferably 30/70 to 60/40, still more preferably 35 in terms of mass ratio. It is / 65 to 55/45.

[Olefin resin]
The olefin-based resin suitable as the resin contained in the resin composition (y-1) is a polymer having at least a structural unit derived from an olefin monomer.
The olefin monomer is preferably an α-olefin having 2 to 8 carbon atoms, and specific examples thereof include ethylene, propylene, butylene, isobutylene, and 1-hexene.
Among these, ethylene and propylene are preferable.

Specific olefin-based resins include, for example, ultra-low density polyethylene (VLDPE, density: 880 kg / m ³ or more and less than 910 kg / m ³ ), low density polyethylene (LDPE, density: 910 kg / m ³ or more and less than 915 kg / m ³ ). ), Medium density polyethylene (MDPE, density: 915 kg / m ³ or more and less than 942 kg / m ³ ), high density polyethylene (HDPE, density: 942 kg / m ³ or more), linear low density polyethylene and other polyethylene resins; polypropylene resin (PP); Polybutene resin (PB); Ethylene-propylene copolymer; Olefin-based elastomer (TPO); Poly (4-methyl-1-pentene) (PMP); Ethethylene-vinyl acetate copolymer (EVA); Ethylene -Vinyl alcohol copolymer (EVOH); olefin-based ternary copolymer such as polyethylene-propylene- (5-ethylidene-2-norbornen); and the like.

In one aspect of the present invention, the olefin-based resin may be a modified olefin-based resin that has been further modified by one or more selected from acid modification, hydroxyl group modification, and acrylic modification.

For example, the acid-modified olefin-based resin obtained by acid-modifying an olefin-based resin is a modified polymer obtained by graft-polymerizing an unsaturated carboxylic acid or an anhydride thereof with the above-mentioned non-modified olefin-based resin. Can be mentioned.
Examples of the unsaturated carboxylic acid or its anhydride include maleic acid, fumaric acid, itaconic acid, citraconic acid, glutaconic acid, tetrahydrophthalic acid, aconitic acid, (meth) acrylic acid, maleic anhydride, and itaconic anhydride. , Anhydrous glutaconic acid, anhydrous citraconic acid, anhydrous aconitic acid, norbornene dicarboxylic acid anhydride, tetrahydrophthalic acid anhydride and the like.
The unsaturated carboxylic acid or its anhydride may be used alone or in combination of two or more.

The acrylic-modified olefin-based resin obtained by subjecting the olefin-based resin to acrylic modification is a modification obtained by graft-polymerizing the above-mentioned non-modified olefin-based resin, which is the main chain, with an alkyl (meth) acrylate as a side chain. Examples include polymers.
The alkyl group of the above alkyl (meth) acrylate has preferably 1 to 20 carbon atoms, more preferably 1 to 16 carbon atoms, and even more preferably 1 to 12 carbon atoms.
Examples of the above-mentioned alkyl (meth) acrylate include the same compounds as those which can be selected as the above-mentioned monomer (a1').

Examples of the hydroxyl group-modified olefin resin obtained by subjecting the olefin resin to hydroxyl group modification include a modified polymer obtained by graft-polymerizing a hydroxyl group-containing compound onto the above-mentioned non-modified olefin resin which is the main chain.
Examples of the above-mentioned hydroxyl group-containing compound include the same as the above-mentioned hydroxyl group-containing compound.

[Resin other than acrylic urethane resin and olefin resin]
In one aspect of the present invention, the resin composition (y-1) may contain a resin other than the acrylic urethane-based resin and the olefin-based resin as long as the effects of the present invention are not impaired.
Examples of such resins include vinyl-based resins such as polyvinyl chloride, polyvinylidene chloride, and polyvinyl alcohol; polyester-based resins such as polyethylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate; polystyrene; acrylonitrile-butadiene-styrene co-weight. Combined; cellulose triacetate; polycarbonate; polyurethane not applicable to acrylic urethane resin; polysulfone; polyether ether ketone; polyether sulfone; polyphenylene sulfide; polyimide resin such as polyetherimide and polyimide; polyamide resin; acrylic resin; Fluorescent resin and the like can be mentioned.

However, from the viewpoint of facilitating the formation of irregularities on the adhesive surface of the adhesive layer (X1) and improving the sheet shape retention after thermal expansion, the acrylic urethane-based resin in the resin composition (y-1). The content of the resin other than the olefin-based resin is preferably small.
The content of the resin other than the acrylic urethane resin and the olefin resin is preferably less than 30 parts by mass, more preferably 20 parts by mass with respect to 100 parts by mass of the total amount of the resin contained in the resin composition (y-1). It is less than parts by mass, more preferably less than 10 parts by mass, even more preferably less than 5 parts by mass, and even more preferably less than 1 part by mass.

(Additive for base material)
The resin composition (y-1) may contain an additive for a base material, if necessary, as long as the effects of the present invention are not impaired.
Examples of the base material additive include an ultraviolet absorber, a light stabilizer, an antioxidant, an antistatic agent, a slip agent, an anti-blocking agent, and a colorant.
These base material additives may be used alone or in combination of two or more.
When these base material additives are contained, the content of each base material additive is independently, preferably 0.0001 to 20 parts by mass, more preferably with respect to 100 parts by mass of the resin. Is 0.001 to 10 parts by mass.

(Solvent-free resin composition (y-1a))
As one aspect of the resin composition (y-1) used in one aspect of the present invention, an oligomer having an ethylenically unsaturated group having a mass average molecular weight (Mw) of 50,000 or less, an energy ray-polymerizable monomer, and the above-mentioned Examples thereof include a solvent-free resin composition (y-1a) containing the heat-expandable particles of the above and not containing a solvent.
In the solvent-free resin composition (y-1a), no solvent is blended, but the energy ray-polymerizable monomer contributes to the improvement of the plasticity of the oligomer.
By irradiating the solvent-free resin composition (y-1a) with energy rays, an oligomer having an ethylenically unsaturated group, an energy ray-polymerizable monomer, etc. are polymerized, and a heat-expandable base material layer (Y1) is polymerized. ) Is formed.

The mass average molecular weight (Mw) of the oligomer contained in the solvent-free resin composition (y-1a) is 50,000 or less, preferably 1,000 to 50,000, and more preferably 2,000 to. It is 40,000, more preferably 3,000 to 35,000, and even more preferably 4,000 to 30,000.

The oligomer may be any resin contained in the above-mentioned resin composition (y-1) having an ethylenically unsaturated group having a mass average molecular weight of 50,000 or less, and the above-mentioned urethane prepolymer may be used. (UP) is preferable, and a linear urethane prepolymer having ethylenically unsaturated groups at both ends is more preferable.
As the oligomer, a modified olefin resin having an ethylenically unsaturated group can also be used.

The total content of the oligomer and the energy ray-polymerizable monomer in the solvent-free resin composition (y-1a) is based on the total amount (100% by mass) of the solvent-free resin composition (y-1a). It is preferably 50 to 99% by mass, more preferably 60 to 95% by mass, still more preferably 65 to 90% by mass, and even more preferably 70 to 85% by mass.

Examples of the energy ray-polymerizable monomer include isobornyl (meth) acrylate, dicyclopentenyl (meth) acrylate, dicyclopentanyl (meth) acrylate, dicyclopentenyloxy (meth) acrylate, cyclohexyl (meth) acrylate, and adamantan (). Alicyclic polymerizable compounds such as meth) acrylates and tricyclodecane acrylates; aromatic polymerizable compounds such as phenylhydroxypropyl acrylates, benzyl acrylates and phenolethylene oxide modified acrylates; tetrahydrofurfuryl (meth) acrylates, morpholine acrylates, N- Examples thereof include heterocyclic polymerizable compounds such as vinylpyrrolidone and N-vinylcaprolactam. Among these, isobornyl (meth) acrylate and phenylhydroxypropyl acrylate are preferable.
These energy ray-polymerizable monomers may be used alone or in combination of two or more.

The content ratio [oligomer / energy ray-polymerizable monomer] of the oligomer to the energy ray-polymerizable monomer in the solvent-free resin composition (y-1a) is preferably 20/80 to 20/80 in mass ratio. It is 90/10, more preferably 30/70 to 85/15, and even more preferably 35/65 to 80/20.

In one aspect of the present invention, the solvent-free resin composition (y-1a) is preferably further blended with a photopolymerization initiator.
By containing the photopolymerization initiator, the curing reaction can be sufficiently advanced even by irradiation with relatively low energy energy rays.
Examples of the photopolymerization initiator include 1-hydroxycyclohexylphenyl ketone, benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin propyl ether, benzylphenyl sulfide, tetramethylthium monosulfide, azobisisobutyronitrile and dibenzyl. , Diacetyl, β-chloroanthraquinone, bis (2,4,6-trimethylbenzoyl) phenylphosphin oxide and the like.
These photopolymerization initiators may be used alone or in combination of two or more.
The blending amount of the photopolymerization initiator is preferably 0.01 to 5 parts by mass, more preferably 0.01 to 4 parts by mass, and further, with respect to the total amount (100 parts by mass) of the oligomer and the energy ray-polymerizable monomer. It is preferably 0.02 to 3 parts by mass.

The resin composition (y-1) can be produced by mixing the above-mentioned components.
The method for mixing each component is not particularly limited, and may be appropriately selected from known mixing methods according to the type of component used, the viscosity of the resin composition, and the like.
Since the resin composition (y-1) contains the heat-expandable particles, it may be subjected to a dispersion treatment for improving the dispersibility of the heat-expandable particles. By improving the dispersibility of the heat-expandable particles in the resin composition (y-1), the surface of the heat-expandable base material layer (Y1) becomes smoother, and the surface of the heat-expandable base material layer (Y1) becomes smoother. The arithmetic mean swell (Wa) of the surface (S _x1 ) of the pressure-sensitive adhesive layer (X1) formed on the surface (S x1) can be made smaller.
As a method for dispersing the heat-expandable particles, for example, a stirring process for adding shear using a high-speed stirrer such as a homomixer, a homogenizer, a planetary mixer, or a ball mill; ultrasonic treatment; filtration for removing agglomerates with a filter. Processing and the like can be mentioned. From these, it is preferable to appropriately determine a method and conditions that can improve the dispersibility while maintaining the function of the heat-expandable particles.
The dispersion treatment of the heat-expandable particles may be carried out after the heat-expandable particles are mixed with other components, or may be carried out in a dispersion medium before being mixed with other components.

(Thickness of the heat-expandable base material layer (Y1))
In one aspect of the present invention, the thickness of the heat-expandable substrate layer (Y1) before thermal expansion is preferably 30 to 300 μm, more preferably 40 to 270 μm, still more preferably 50 to 240 μm, still more preferably 55. It is ~ 220 μm.
When the thickness of the heat-expandable base material layer (Y1) before thermal expansion is 30 μm or more, the generation of unevenness due to the heat-expandable particles before thermal expansion is suppressed, and the surface of the pressure-sensitive adhesive layer (X1) (X1). The arithmetic average swell (Wa) of S _x1 ) can be further reduced, and the stickability tends to be improved. Further, when the thickness of the heat-expandable base material layer (Y1) before thermal expansion is 300 μm or less, the pressure-sensitive adhesive sheet tends to be easy to handle.

<Non-thermally expandable base material layer (Y2)>
The non-thermally expandable base material layer (Y2) included in the pressure-sensitive adhesive sheet of the first aspect is provided on the surface of the heat-expandable base material layer (Y1) opposite to the laminated surface of the pressure-sensitive adhesive layer (X1).

The non-thermally expandable base material layer (Y2) is preferably a non-adhesive base material. The probe tack value on the surface of the non-thermally expandable base material layer (Y2) is usually less than 50 mN / 5 mmφ, preferably less than 30 mN / 5 mmφ, more preferably less than 10 mN / 5 mmφ, still more preferably less than 5 mN / 5 mmφ. be.

Examples of the material for forming the non-thermally expandable base material layer (Y2) include resins, metals, paper materials, etc., which can be appropriately selected depending on the use of the pressure-sensitive adhesive sheet.

Examples of the resin include polyolefin resins such as polyethylene and polypropylene; vinyl resins such as polyvinyl chloride, polyvinylidene chloride, polyvinyl alcohol, ethylene-vinyl acetate copolymer, and ethylene-vinyl alcohol copolymer; polyethylene terephthalate and poly. Polyester resins such as butylene terephthalate and polyethylene naphthalate; polystyrene; acrylonitrile-butadiene-styrene copolymer; cellulose triacetate; polycarbonate; urethane resins such as polyurethane and acrylic modified polyurethane; polymethylpentene; polysulfone; polyether ether ketone; Polyether sulfone; polyphenylene sulfide; polyimide resin such as polyetherimide and polyimide; polyamide resin; acrylic resin; fluororesin and the like can be mentioned.
Examples of the metal include aluminum, tin, chromium, titanium and the like.
Examples of the paper material include thin leaf paper, medium quality paper, high quality paper, impregnated paper, coated paper, art paper, parchment paper, glassin paper and the like.
Among these, polyester resins such as polyethylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate are preferable.

These forming materials may be composed of one kind, or two or more kinds may be used in combination.
As the non-thermally expandable base material layer (Y2) in which two or more kinds of forming materials are used in combination, a paper material laminated with a thermoplastic resin such as polyethylene, a resin film containing the resin, or a metal film is formed on the surface of the sheet. And so on.
As a method for forming the metal layer, for example, a method of vapor-depositing the metal by a PVD method such as vacuum deposition, sputtering, ion plating, or a method of attaching a metal foil made of the metal by a general adhesive is used. How to do it, etc.

When the non-thermally expandable base material layer (Y2) contains a resin, the non-thermally expandable base layer (Y2) is a non-thermally expandable group from the viewpoint of improving the interlayer adhesion between the non-thermally expandable base material layer (Y2) and other layers to be laminated. The surface of the material layer (Y2) may also be subjected to surface treatment by an oxidation method, an unevenness method or the like, easy adhesion treatment, or primer treatment in the same manner as the above-mentioned heat-expandable base material layer (Y1). ..

Further, when the non-thermally expandable base material layer (Y2) contains a resin, the above-mentioned base material additive which can be contained in the resin composition (y-1) may be contained together with the resin.

The non-thermally expandable base material layer (Y2) is a non-thermally expandable layer determined based on the above method.
Therefore, the volume change rate (%) of the non-thermally expandable base material layer (Y2) calculated from the above formula is less than 5%, preferably less than 2%, more preferably less than 1%, and further. It is preferably less than 0.1%, and even more preferably less than 0.01%.

Further, the non-thermally expandable base material layer (Y2) may contain thermally expandable particles as long as the volume change rate is within the above range. For example, by selecting the resin contained in the non-thermally expandable base material layer (Y2), it is possible to adjust the volume change rate within the above range even if the thermally expandable particles are contained.
However, the smaller the content of the heat-expandable particles in the non-heat-expandable base material layer (Y2), the more preferable.
The specific content of the heat-expandable particles is usually less than 3% by mass, preferably less than 1% by mass, more preferably with respect to the total mass (100% by mass) of the non-heat-expandable base material layer (Y2). Is less than 0.1% by mass, more preferably less than 0.01% by mass, and even more preferably less than 0.001% by mass. Even more preferably, it does not contain thermally expandable particles.

(Store elastic modulus E'(23) of the non-thermally expandable base material layer (Y2) at 23 ° C.)
The storage elastic modulus E'(23) of the non-thermally expandable substrate layer (Y2) at 23 ° C. is preferably 5.0 × 10 ⁷ to 5.0 × 10 ⁹ Pa, more preferably 5.0 × 10 ⁸ . It is ~ 4.5 × 10 ⁹ Pa, more preferably 1.0 × 10 ⁹ to 4.0 × 10 ⁹ Pa.
When the storage elastic modulus E'(23) of the non-thermally expandable base material layer (Y2) is 5.0 × ¹⁰⁷ Pa or more, it is easy to improve the deformation resistance of the pressure-sensitive adhesive sheet. On the other hand, when the storage elastic modulus E'(23) of the non-thermally expandable base material layer (Y2) is 5.0 × ¹⁰⁹ Pa or less, the handleability of the pressure-sensitive adhesive sheet can be easily improved.
In the present specification, the storage elastic modulus E'(23) of the non-thermally expandable base material layer (Y2) means a value measured by the method described in Examples.

(Thickness of non-thermally expandable base material layer (Y2))
The thickness of the non-thermally expandable base material layer (Y2) is preferably 5 to 500 μm, more preferably 15 to 300 μm, and even more preferably 20 to 200 μm. When the thickness of the non-thermally expandable base material layer (Y2) is 5 μm or more, it is easy to improve the deformation resistance of the pressure-sensitive adhesive sheet. On the other hand, when the thickness of the non-thermally expandable base material layer (Y2) is 500 μm or less, it becomes easy to improve the handleability of the pressure-sensitive adhesive sheet.

<Adhesive layer (X2)>
The pressure-sensitive adhesive sheet of the first aspect has the pressure-sensitive adhesive layer (X2) on the surface of the non-heat-expandable base layer (Y2) opposite to the laminated surface of the heat-expandable base layer (Y1). May be good. That is, the pressure-sensitive adhesive sheet of the first aspect includes a pressure-sensitive adhesive layer (X1), a heat-expandable base material layer (Y1), a non-heat-expandable base material layer (Y2), and a pressure-sensitive adhesive layer (X2). May be an adhesive sheet having a laminated structure arranged in this order.

The pressure-sensitive adhesive layer (X2) is preferably a non-thermally expandable layer.
When the pressure-sensitive adhesive layer (X2) is a non-thermally expandable layer, the volume change rate (%) of the pressure-sensitive adhesive layer (X2) calculated from the above formula is less than 5%, preferably less than 2%. It is preferably less than 1%, more preferably less than 0.1%, and even more preferably less than 0.01%.
The pressure-sensitive adhesive layer (X2) preferably does not contain the heat-expandable particles, but may contain the heat-expandable particles within a range not contrary to the object of the present invention.
When the pressure-sensitive adhesive layer (X2) contains thermally expandable particles, the smaller the content, the more preferable, and the content is preferably less than 3% by mass, based on the total mass (100% by mass) of the pressure-sensitive adhesive layer (X2). It is preferably less than 1% by mass, more preferably less than 0.1% by mass, still more preferably less than 0.01% by mass, and even more preferably less than 0.001% by mass.

The pressure-sensitive adhesive layer (X2) is preferably an energy ray-curable pressure-sensitive adhesive layer that is cured by irradiating with energy rays to reduce the adhesive strength. By using the pressure-sensitive adhesive layer (X2) as an energy ray-curable pressure-sensitive adhesive layer, the pressure-sensitive adhesive surface of the pressure-sensitive adhesive layer (X1) is reduced in adhesive strength by heating, and the pressure-sensitive adhesive surface of the pressure-sensitive adhesive layer (X2) is energy-based. The adhesive strength can be reduced by line irradiation, and the mechanism of action for reducing the adhesive strength between the adhesive layers can be different. This makes it possible to avoid unintentionally reducing the adhesive strength of the other pressure-sensitive adhesive layer when performing a treatment for reducing the adhesive strength of one of the pressure-sensitive adhesive layers.

The pressure-sensitive adhesive layer (X2) is preferably formed from the pressure-sensitive adhesive composition (x-2) containing the pressure-sensitive adhesive resin. Hereinafter, each component contained in the pressure-sensitive adhesive composition (x-2) will be described.

The pressure-sensitive adhesive composition (x-2) contains a pressure-sensitive adhesive resin, and if necessary, a cross-linking agent, a pressure-sensitive adhesive, a polymerizable compound, a polymerization initiator, and general pressure-sensitive adhesive other than the above-mentioned components. It may contain an additive for a pressure-sensitive adhesive used in the agent.

(Adhesive resin)
The adhesive resin may be a polymer having adhesiveness by itself and having a mass average molecular weight (Mw) of 10,000 or more.
The mass average molecular weight (Mw) of the adhesive resin is preferably 10,000 to 2 million, more preferably 20,000 to 1.5 million, and further preferably 30,000 from the viewpoint of further improving the adhesive strength of the adhesive layer (X2). ~ 1 million.

Examples of the pressure-sensitive adhesive resin include those similar to the pressure-sensitive adhesive resin contained in the pressure-sensitive adhesive composition (x-1).
These adhesive resins may be used alone or in combination of two or more.
Further, when these adhesive resins are copolymers having two or more kinds of structural units, the form of the copolymer may be any of a block copolymer, a random copolymer, and a graft copolymer. There may be.

The adhesive resin contained in the pressure-sensitive adhesive composition (x-2) has a side chain from the viewpoint of forming the obtained pressure-sensitive adhesive layer (X2) into a pressure-sensitive adhesive layer that is cured by irradiation with energy rays to reduce the adhesive strength. It is preferably an adhesive resin having an energy ray-polymerizable functional group.
Examples of the energy ray-polymerizable functional group include those having a carbon-carbon double bond such as a (meth) acryloyl group, a vinyl group, and an allyl group.

The adhesive resin preferably contains an acrylic resin from the viewpoint of exhibiting excellent adhesive strength.
The content of the acrylic resin in the pressure-sensitive adhesive composition (x-2) is preferably 30 to 30 with respect to the total amount (100% by mass) of the pressure-sensitive adhesive resin contained in the pressure-sensitive adhesive composition (x-2). It is 100% by mass, more preferably 50 to 100% by mass, still more preferably 70 to 100% by mass, and even more preferably 85 to 100% by mass.

The content of the tacky resin in the pressure-sensitive adhesive composition (x-2) is preferably 35 to 100% by mass with respect to the total amount (100% by mass) of the active ingredient of the pressure-sensitive adhesive composition (x-2). It is more preferably 50 to 100% by mass, further preferably 60 to 98% by mass, and even more preferably 70 to 95% by mass.

(Energy ray curable compound)
The pressure-sensitive adhesive composition (x-2) may contain a monomer or an oligomer that can be polymerized and cured by energy ray irradiation as an energy ray-curable compound together with the pressure-sensitive adhesive resin.
Examples of such energy ray-curable compounds include trimethylolpropane tri (meth) acrylate, pentaerythritol (meth) acrylate, pentaerythritol tetra (meth) acrylate, dipentaerythritol hexa (meth) acrylate, and 1,4-. Polyvalent (meth) acrylate monomers such as butylene glycol di (meth) acrylate, 1,6-hexanediol (meth) acrylate; polyfunctional urethane (meth) acrylate, polyfunctional polyester (meth) acrylate, polyfunctional polyether (polyfunctional polyether) Examples thereof include oligomers such as meth) acrylate and polyfunctional epoxy (meth) acrylate.
Among these, a polyfunctional urethane (meth) acrylate oligomer is preferable from the viewpoint of having a relatively high molecular weight and hardly lowering the elastic modulus of the pressure-sensitive adhesive layer (X2).
The molecular weight of the energy ray-curable compound (mass average molecular weight (Mw) in the case of an oligomer) is preferably 100 to 12,000, more preferably 200 to 10,000, still more preferably 400 to 8,000, and even more preferably. Is 600 to 6,000.

(Photopolymerization initiator)
The pressure-sensitive adhesive composition (x-2) preferably further contains a photopolymerization initiator.
By containing the photopolymerization initiator, the polymerization of the energy ray-polymerizable component can proceed more efficiently.
Examples of the photopolymerization initiator include the same as those exemplified in the description of the solvent-free resin composition (y-1a). Among these, 1-hydroxycyclohexylphenyl ketone is preferable.
The content of the photopolymerization initiator is preferably 0.01 to 10 parts by mass, more preferably 0.03 to 5 parts by mass, based on 100 parts by mass of the total amount of the pressure-sensitive adhesive resin having an energy ray-polymerizable functional group. More preferably, it is 0.05 to 2 parts by mass.

(Crosslinking agent)
In one aspect of the present invention, when the pressure-sensitive adhesive composition (x-2) contains a pressure-sensitive adhesive resin having a functional group, it is preferable that the pressure-sensitive adhesive composition (x-2) further contains a cross-linking agent.
The cross-linking agent reacts with a pressure-sensitive adhesive resin having a functional group to cross-link the pressure-sensitive adhesive resins using the functional group as a cross-linking starting point.

Examples of the cross-linking agent that may be contained in the pressure-sensitive adhesive composition (x-2) include the same or equivalent cross-linking agents that may be contained in the pressure-sensitive adhesive composition (x-1). An isocyanate-based cross-linking agent is preferable from the viewpoint of increasing the cohesive force and improving the adhesive force, and from the viewpoint of easy availability.

(Adhesive)
In one aspect of the present invention, the pressure-sensitive adhesive composition (x-2) may further contain a pressure-sensitive adhesive from the viewpoint of further improving the pressure-sensitive adhesive strength.
As the pressure-sensitive adhesive that may be contained in the pressure-sensitive adhesive composition (x-2), the same or equivalent as the pressure-sensitive adhesive that may be contained in the pressure-sensitive adhesive composition (x-1) is used. can do.

(Additive for adhesive)
Examples of the pressure-sensitive adhesive additive include the same pressure-sensitive adhesive additives that may be contained in the pressure-sensitive adhesive composition (x-1).

The pressure-sensitive adhesive composition (x-2) can be produced by mixing a pressure-sensitive adhesive resin, a cross-linking agent used as necessary, a pressure-sensitive adhesive, an additive for a pressure-sensitive adhesive, and the like.

(Adhesive strength of the adhesive layer (X2) before irradiation with energy rays)
The adhesive strength of the pressure-sensitive adhesive layer (X2) before irradiation with energy rays is preferably 1.1 to 30.0 N / 25 mm, more preferably 3.0 to 25.0 N / 25 mm, still more preferably 5.0 to 20. It is 0N / 25 mm.
If the adhesive force of the adhesive layer (X2) before irradiation with energy rays is 1.1 N / 25 mm or more, it is possible to more effectively suppress unintentional peeling from the adherend, misalignment of the adherend, and the like. can. On the other hand, when the adhesive strength is 30.0 N / 25 mm or less, the peelability after irradiation with energy rays can be further improved.
The adhesive strength of the adhesive layer (X2) before irradiation with energy rays can be measured by the above method.

(Adhesive strength of the adhesive layer (X2) after irradiation with energy rays)
The adhesive strength of the pressure-sensitive adhesive layer (X2) after irradiation with energy rays is preferably 1.0 N / 25 mm or less, more preferably 0.9 N / 25 mm or less, still more preferably 0.8 N / 25 mm or less, still more preferably 0. It is .7 N / 25 mm or less. The lower limit value of the pressure-sensitive adhesive layer (X2) after irradiation with energy rays is not particularly limited and may be 0N / 25 mm or more.
When the adhesive force of the adhesive layer (X2) after irradiation with energy rays is 1.0 N / 25 mm or less, the peelability from the adherend is more excellent.
The adhesive strength of the pressure-sensitive adhesive layer (X2) after irradiation with energy rays is as described above for a pressure-sensitive adhesive sheet irradiated with ultraviolet rays having an illuminance of 230 mW / cm ² and a light intensity of 90 mJ / cm ² with respect to the pressure-sensitive adhesive layer (X2). It can be measured by the method described above.

(Thickness of adhesive layer (X2))
The thickness of the pressure-sensitive adhesive layer (X2) contained in the pressure-sensitive adhesive sheet of the first aspect is preferably 5 to 150 μm, more preferably 8 to 100 μm, still more preferably 12 to 70 μm, and even more preferably 15 to 50 μm.
If the thickness of the pressure-sensitive adhesive layer (X2) is 5 μm or more, it becomes easy to obtain sufficient adhesive strength, and there is a tendency that unintentional peeling from the adherend and misalignment of the adherend at the time of temporary fixing can be suppressed. It is in. On the other hand, when the thickness of the pressure-sensitive adhesive layer (X2) is 150 μm or less, the pressure-sensitive adhesive sheet tends to be easy to handle.

<Method for manufacturing an adhesive sheet according to the first aspect>
The method for producing the pressure-sensitive adhesive sheet according to the first aspect is not particularly limited, and examples thereof include a method for manufacturing a pressure-sensitive adhesive sheet having the following steps (1a) to (3a).
Step (1a): A step of applying the pressure-sensitive adhesive composition (x-1) on the peeling treatment surface of the release material to form the pressure-sensitive adhesive layer (X1).
Step (2a): The resin composition (y-1) is applied to one side of the non-heat-expandable base layer (Y2) to form a non-heat-expandable base layer (Y2) and a heat-expandable base layer (Y-1). A step of forming a base material laminate in which Y1) is laminated.
Step (3a): The adhesive surface of the pressure-sensitive adhesive layer (X1) formed in the step (1a) and the surface of the base material laminate formed in the step (2a) on the heat-expandable base layer (Y1) side. , The process of laminating to obtain an adhesive sheet.

Further, the pressure-sensitive adhesive sheet of the first aspect has a structure in which a pressure-sensitive adhesive layer (X1), a base material layer (Y), and a pressure-sensitive adhesive layer (X2) are arranged in this order. If so, the pressure-sensitive adhesive sheet can be further produced by a method having the following steps (4a) and (5a).
Step (4a): A step of applying the pressure-sensitive adhesive composition (x-2) on the peeling treatment surface of the release material to form the pressure-sensitive adhesive layer (X2).
Step (5a): The adhesive surface of the pressure-sensitive adhesive layer (X2) formed in step (4a) is bonded to the surface of the pressure-sensitive adhesive sheet formed in step (3a) on the non-thermally expandable base material layer (Y2) side. Process.

In the method for producing the pressure-sensitive adhesive sheet, the resin composition (y-1), the pressure-sensitive adhesive composition (x-1), and the pressure-sensitive adhesive composition (x-2) are further blended with a diluting solvent to form a solution. May be good.
Examples of the coating method include a spin coating method, a spray coating method, a bar coating method, a knife coating method, a roll coating method, a blade coating method, a die coating method, a gravure coating method and the like.

Further, the step of drying the coating film formed from the resin composition (y-1), the pressure-sensitive adhesive composition (x-1), and the pressure-sensitive adhesive composition (x-2) causes the expansion of the heat-expandable particles. From the viewpoint of suppression, it is preferable that the drying temperature is lower than the expansion start temperature (t) of the heat-expandable particles.

[Adhesive sheet of the second aspect]
The pressure-sensitive adhesive sheet of the second aspect is a pressure-sensitive adhesive sheet having a laminated structure including a pressure-sensitive adhesive layer (X1) which is a heat-expandable layer and a base material layer (Y).
The pressure-sensitive adhesive sheet of the second aspect may have the pressure-sensitive adhesive layer (X2) on the surface of the base material layer (Y) opposite to the laminated surface of the pressure-sensitive adhesive layer (X1). That is, the pressure-sensitive adhesive sheet of the second aspect has a laminated structure in which a pressure-sensitive adhesive layer (X1), which is a heat-expandable layer, a base material layer (Y), and a pressure-sensitive adhesive layer (X2) are arranged in this order. It may be an adhesive sheet having.

The description of the base material layer (Y) included in the pressure-sensitive adhesive sheet of the second aspect is the same as the description of the non-thermally expandable base material layer (Y2) in the pressure-sensitive adhesive sheet of the first aspect. Further, the description of the pressure-sensitive adhesive layer (X2) that the pressure-sensitive adhesive sheet of the second aspect may have is the description of the pressure-sensitive adhesive layer (X2) that the pressure-sensitive adhesive sheet of the first aspect may have. Is the same as.

<Adhesive layer (X1)>
The pressure-sensitive adhesive layer (X1) of the second aspect is a heat-expandable layer containing heat-expandable particles, and preferably contains a polymer of an energy ray-polymerizable component and heat-expandable particles.
The polymer has a monomer (b1) having an energy ray-polymerizable functional group (hereinafter, also referred to as "(b1) component") and a prepolymer having an energy ray-polymerizable functional group (b2) as the energy ray-polymerizable component. ) (Hereinafter, also referred to as "(b2) component") is a polymer obtained by irradiating a polymerizable composition (hereinafter, also referred to as "polymerizable composition (x-1')") with energy rays. ..
In addition, in this specification, a prepolymer means a compound which is made by polymerizing a monomer, and can form a polymer by further polymerization.

The energy ray-polymerizable component contained in the polymerizable composition (x-1') is a component that polymerizes by irradiation with energy rays and has an energy ray-polymerizable functional group.
Examples of the energy ray-polymerizable functional group include those having a carbon-carbon double bond such as a (meth) acryloyl group, a vinyl group, and an allyl group. In the following description, a functional group containing a vinyl group or a substituted vinyl group as a part thereof, such as a (meth) acryloyl group, an allyl group, etc., and a vinyl group or a substituted vinyl group itself are referred to as a "vinyl group-containing group". May be collectively referred to as.
Hereinafter, each component contained in the polymerizable composition (x-1') will be described.

(Monomer having an energy ray-polymerizable functional group (b1))
The monomer (b1) having an energy ray-polymerizable functional group may be a monomer having an energy ray-polymerizable functional group, and in addition to the energy ray-polymerizable functional group, a hydrocarbon group or an energy ray-polymerizable functional group. It may have a functional group other than the above.

Examples of the hydrocarbon group contained in the component (b1) include an aliphatic hydrocarbon group, an aromatic hydrocarbon group, and a group combining these groups.
The aliphatic hydrocarbon group may be a linear or branched aliphatic hydrocarbon group, or may be an alicyclic hydrocarbon group.
Examples of the linear or branched aliphatic hydrocarbon group include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, a tert-butyl group, a sec-butyl group and an n-pentyl group. Group, n-hexyl group, 2-ethylhexyl group, n-octyl group, isooctyl group, n-decyl group, n-dodecyl group, n-myristyl group, n-palmityl group, n-stearyl group, etc. 20 aliphatic hydrocarbon groups are mentioned.
Examples of the alicyclic hydrocarbon group include an alicyclic hydrocarbon group having 3 to 20 carbon atoms such as a cyclopentyl group, a cyclohexyl group and an isobornyl group.
Examples of the aromatic hydrocarbon group include a phenyl group.
Examples of the group in which the aliphatic hydrocarbon group and the aromatic hydrocarbon group are combined include a phenoxyethyl group and a benzyl group.
Among these, the component (b1) has an energy ray-polymerizable functional group and a linear or branched aliphatic hydrocarbon group from the viewpoint of further improving the adhesive strength of the pressure-sensitive adhesive layer (X1). Monomer (b1-1) (hereinafter, also referred to as “(b1-1) component”), monomer (b1-2) having an energy ray-polymerizable functional group and an alicyclic hydrocarbon group (hereinafter, “(b1-b1-) component”). 2) It is preferable to contain "components") and the like.

When the component (b1) contains the component (b1-1), the content thereof is preferably 20 to 80% by mass, more preferably 40 to 40% by mass, based on the total amount (100% by mass) of the component (b1). It is 70% by mass, more preferably 50 to 60% by mass.
When the component (b1) contains the component (b1-2), the content thereof is preferably 5 to 60% by mass, more preferably 10 to 10 to the total (100% by mass) of the components (b1). It is 40% by mass, more preferably 20 to 30% by mass.

The monomer having an energy ray-polymerizable functional group and a functional group other than the energy ray-polymerizable functional group includes, for example, a hydroxy group, a carboxy group, a thiol group, 1 or a functional group other than the energy ray-polymerizable functional group. Examples thereof include a monomer having a secondary amino group and the like. Among these, the component (b1) is a monomer (b1-3) having an energy ray-polymerizable functional group and a hydroxy group from the viewpoint of further improving the formability of the pressure-sensitive adhesive layer (X1) (hereinafter, "(b1)". -3) It is preferable to contain (also referred to as “component”).
When the component (b1) contains the component (b1-3), the content thereof is preferably 1 to 60% by mass, more preferably 5 to 5 to the total amount (100% by mass) of the components (b1). It is 30% by mass, more preferably 10 to 20% by mass.

The number of energy ray-polymerizable functional groups contained in the component (b1) may be one or two or more. Further, from the viewpoint of further improving the peelability of the pressure-sensitive adhesive layer (X1), the component (b1) is a monomer (b1-4) having three or more energy ray-polymerizable functional groups (hereinafter, "(b1-4)). It is preferable to contain (also referred to as "ingredient").
When the component (b1) contains the component (b1-4), the content thereof is preferably 1 to 20% by mass, more preferably 2 to 2 to the total amount (100% by mass) of the components (b1). It is 15% by mass, more preferably 3 to 10% by mass.

As the monomer having one energy ray-polymerizable functional group, a monomer having one vinyl group-containing group (hereinafter, also referred to as "polymerizable vinyl monomer") is preferable.
As the monomer having two or more energy ray-polymerizable functional groups, a monomer having two or more (meth) acryloyl groups (hereinafter, also referred to as “polyfunctional (meth) acrylate monomer”) is preferable. When the component (b1) contains the above compounds, the cohesive force of the pressure-sensitive adhesive obtained by polymerizing them is improved, and a pressure-sensitive adhesive layer (X1) with less adhesion contamination after peeling can be formed. ..

[Polymerizable vinyl monomer]
The polymerizable vinyl monomer is not particularly limited as long as it has a vinyl group-containing group, and conventionally known ones can be appropriately used.
As the polymerizable vinyl monomer, one type may be used alone, or two or more types may be used in combination.

Examples of the polymerizable vinyl monomer include methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate, pentyl (meth) acrylate, hexyl (meth) acrylate, and 2-ethylhexyl (meth). ) Corresponds to the above (b1-1) component such as acrylate, isooctyl (meth) acrylate, decyl (meth) acrylate, dodecyl (meth) acrylate, myristyl (meth) acrylate, palmityl (meth) acrylate, and stearyl (meth) acrylate. Compounds; Compounds corresponding to the above (b1-2) components such as cyclohexyl (meth) acrylates and isobornyl (meth) acrylates; phenoxyethyl (meth) acrylates, benzyl (meth) acrylates, polyoxyalkylene-modified (meth) acrylates and the like. Examples thereof include (meth) acrylate having no functional group other than a vinyl group-containing group in the molecule. Among these, 2-ethylhexyl acrylate and isobornyl acrylate are preferable.

The polymerizable vinyl monomer may further have a functional group other than the vinyl group-containing group in the molecule. Examples of the functional group include a hydroxy group, a carboxy group, a thiol group, a primary amino group, a secondary amino group and the like. Among these, a polymerizable vinyl monomer having a hydroxy group corresponding to the above component (b1-3) is preferable.
Examples of the polymerizable vinyl monomer having a hydroxy group include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, and 3. -Hydroxyalkyl (meth) acrylates such as hydroxybutyl (meth) acrylates and 4-hydroxybutyl (meth) acrylates; hydroxy group-containing acrylamides such as N-methylol acrylamide and N-methylol methacrylic amide can be mentioned. Examples of the polymerizable vinyl monomer having a carboxy group include ethylenically unsaturated carboxylic acids such as acrylic acid, methacrylic acid, crotonic acid, maleic acid, itaconic acid and citraconic acid. Among these, 2-hydroxyethyl acrylate and 4-hydroxybutyl acrylate are preferable.

Examples of other polymerizable vinyl monomers include vinyl esters such as vinyl acetate and vinyl propionate; olefins such as ethylene, propylene and isobutylene; halogenated olefins such as vinyl chloride and vinylidene chloride; styrene and α. -Sterite-based monomers such as methylstyrene; diene-based monomers such as butadiene, isoprene, and chloroprene; nitrile-based monomers such as acrylonitrile and methacrylonitrile; acrylamide, methacrylicamide, N-methylacrylamide, and N-methyl. Amide-based monomers such as methacrylamide, N, N-dimethyl (meth) acrylamide, N, N-diethyl (meth) acrylamide, N-vinylpyrrolidone; N, N-diethylaminoethyl (meth) acrylate, N-( Meta) Examples thereof include a tertiary amino group-containing monomer such as acryloylmorpholine.

[Polyfunctional (meth) acrylate monomer]
The polyfunctional (meth) acrylate monomer is not particularly limited as long as it is a monomer having two or more (meth) acryloyl groups in one molecule, and conventionally known ones can be appropriately used.
One type of polyfunctional (meth) acrylate monomer may be used alone, or two or more types may be used in combination.

Examples of the polyfunctional (meth) acrylate monomer include 1,4-butanediol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, neopentyl glycol di (meth) acrylate, and polyethylene glycol di (meth) acrylate. ) Acrylate, neopentyl glycol adipate di (meth) acrylate, hydroxypivalate neopentyl glycol di (meth) acrylate, dicyclopentanyldi (meth) acrylate, caprolactone-modified dicyclopentenyldi (meth) acrylate, ethylene oxide-modified phosphoric acid Bifunctional (meth) acrylate monomers such as di (meth) acrylates, di (acryloxyethyl) isocyanurates, allylated cyclohexyldi (meth) acrylates, isocyanuric acid ethylene oxide-modified diacrylates; trimethyl propantri (meth) acrylates, Dipentaerythritol tri (meth) acrylate, propionic acid-modified dipentaerythritol tri (meth) acrylate, pentaerythritol tri (meth) acrylate, propylene oxide-modified trimethylolpropanetri (meth) acrylate, tris (acryloxyethyl) isocyanurate, Bis (acryloxyethyl) hydroxyethyl isocyanurate, isocyanuric acid ethylene oxide-modified triacrylate, ε-caprolactone-modified tris (acryloxyethyl) isocyanurate, diglycerin tetra (meth) acrylate, pentaerythritol tetra (meth) acrylate, propionic acid Polyfunctional (meth) acrylate monomers corresponding to the above (b1-4) components such as modified dipentaerythritol penta (meth) acrylate, dipentaerythritol hexa (meth) acrylate, and caprolactone modified dipentaerythritol hexa (meth) acrylate Can be mentioned.

<< Content of (b1) component >>
The total content of the polymerizable vinyl monomer in the polymerizable composition (x-1') is preferably 10 with respect to the total amount (100% by mass) of the active ingredient of the polymerizable composition (x-1'). It is -80% by mass, more preferably 30 to 75% by mass, still more preferably 50 to 70% by mass.
The total content of the polyfunctional (meth) acrylate monomer in the polymerizable composition (x-1') is preferable with respect to the total amount (100% by mass) of the active ingredient of the polymerizable composition (x-1'). Is 0.5 to 15% by mass, more preferably 1 to 10% by mass, still more preferably 2 to 5% by mass.
The total content of the component (b1) in the polymerizable composition (x-1') is preferably 15 to 15 to the total amount (100% by mass) of the active ingredient of the polymerizable composition (x-1'). It is 90% by mass, more preferably 35 to 80% by mass, and even more preferably 55 to 75% by mass.

(Prepolymer having an energy ray-polymerizable functional group (b2))
Examples of the prepolymer having an energy ray-polymerizable functional group (b2) include a prepolymer having one energy ray-polymerizable functional group, a prepolymer having two or more energy ray-polymerizable functional groups, and the like. Among these, the component (b2) contains a prepolymer having two or more energy ray-polymerizable functional groups from the viewpoint of forming a pressure-sensitive adhesive layer having excellent peelability and less contamination of the adherend after peeling. It is more preferable to contain a prepolymer having two energy ray-polymerizable functional groups, and a prepolymer having two energy ray-polymerizable functional groups and having the energy ray-polymerizable functional groups at both ends is preferable. It is more preferable to contain it.

As the component (b2), it is preferable to contain a prepolymer having two or more (meth) acryloyl groups as an energy ray-polymerizable functional group (hereinafter, also referred to as "polyfunctional (meth) acrylate prepolymer"). When the component (b2) contains the above compounds, the cohesive force of the pressure-sensitive adhesive obtained by polymerizing them is improved, the peelability is excellent, and the pressure-sensitive adhesive layer (X1) has less contamination of the adherend after peeling. Can be formed.

[Polyfunctional (meth) acrylate prepolymer]
The polyfunctional (meth) acrylate prepolymer is not particularly limited as long as it is a prepolymer having two or more (meth) acryloyl groups in one molecule, and conventionally known prepolymers can be appropriately used.
The polyfunctional (meth) acrylate prepolymer may be used alone or in combination of two or more.

Examples of the polyfunctional (meth) acrylate prepolymer include urethane acrylate-based prepolymers, polyester acrylate-based prepolymers, epoxy acrylate-based prepolymers, polyether acrylate-based prepolymers, polybutadiene acrylate-based prepolymers, and silicone acrylate-based prepolymers. Examples thereof include polyacrylic acrylate-based prepolymers.

The urethane acrylate-based prepolymer can be obtained by reacting a compound such as a polyalkylene polyol, a polyether polyol, a polyester polyol, a hydrogenated isoprene having a hydroxy group terminal, or a hydrogenated butadiene having a hydroxy group terminal with a polyisocyanate. It can be obtained by esterifying the polyurethane prepolymer with a (meth) acrylic acid or a (meth) acrylic acid derivative.

Examples of the polyalkylene polyol used for producing the urethane acrylate-based prepolymer include polypropylene glycol, polyethylene glycol, polybutylene glycol, polyhexylene glycol and the like, and among these, polypropylene glycol is preferable. When the number of functional groups of the obtained urethane acrylate-based prepolymer is 3 or more, for example, glycerin, trimethylolpropane, triethanolamine, pentaerythritol, ethylenediamine, diethylenetriamine, sorbitol, sucrose and the like may be appropriately combined.

Examples of the polyisocyanate used for producing the urethane acrylate-based prepolymer include aliphatic diisocyanates such as hexamethylene diisocyanate and trimethylene diisocyanate; aromatic diisocyanates such as tolylene diisocyanate, xylylene diisocyanate and diphenyldiisocyanate; dicyclohexylmethane diisocyanate. , Alicyclic diisocyanate such as isophorone diisocyanate, and the like, among these, aliphatic diisocyanate is preferable, hexamethylene diisocyanate is more preferable. The polyisocyanate is not limited to bifunctional ones, and trifunctional or higher functional ones can also be used.

Examples of the (meth) acrylic acid derivative used for producing the urethane acrylate-based prepolymer include hydroxyalkyl (meth) acrylates such as 2-hydroxyethyl acrylate and 4-hydroxybutyl acrylate; 2-isocyanate ethyl acrylate, 2-. Examples thereof include isocyanate ethyl methacrylate and 1,1-bis (acryloxymethyl) ethyl isocyanate, and among these, 2-isocyanate ethyl acrylate is preferable.

As another method for producing a urethane acrylate-based prepolymer, a hydroxy group contained in a compound such as a polyalkylene polyol, a polyether polyol, a polyester polyol, a hydrogenated isoprene having a hydroxy group terminal, and a hydrogenated butadiene having a hydroxy group terminal, and an isocyanate. Examples thereof include a method of reacting with the −N = C = O moiety of the alkyl (meth) acrylate. In this case, as the isocyanate alkyl (meth) acrylate, for example, the above-mentioned 2-isocyanate ethyl acrylate, 2-isocyanate ethyl methacrylate, 1,1-bis (acryloxymethyl) ethyl isocyanate and the like can be used.

The polyester acrylate-based prepolymer can be obtained, for example, by esterifying the hydroxy groups of a polyester prepolymer having hydroxy groups at both ends obtained by condensation of a polyvalent carboxylic acid and a polyhydric alcohol with (meth) acrylic acid. Can be done. It can also be obtained by esterifying the hydroxy group at the end of the prepolymer obtained by adding an alkylene oxide to a polyvalent carboxylic acid with (meth) acrylic acid.

The epoxy acrylate-based prepolymer can be obtained, for example, by subjecting an oxylan ring such as a relatively low molecular weight bisphenol type epoxy resin or a novolak type epoxy resin to esterification by reacting (meth) acrylic acid. Further, a carboxy-modified epoxy acrylate-based prepolymer obtained by partially modifying the epoxy acrylate-based prepolymer with a dibasic carboxylic acid anhydride can also be used.

The polyether acrylate-based prepolymer can be obtained, for example, by esterifying the hydroxy group of the polyether polyol with (meth) acrylic acid.

The polyacrylic acrylate-based prepolymer may have an acryloyl group in the side chain, or may have an acryloyl group at both ends or one end. A polyacrylic acrylate-based prepolymer having an acryloyl group in the side chain can be obtained, for example, by adding glycidyl methacrylate to the carboxy group of polyacrylic acid. Further, in the polyacrylic acrylate-based prepolymer having acryloyl groups at both ends, for example, an acryloyl group is introduced at both ends by utilizing the polymerization growth end structure of the polyacrylate prepolymer synthesized by the ATRP (Atom Transfer Radical Polymerization) method. You can get it by doing.

The mass average molecular weight (Mw) of the component (b2) is preferably 10,000 to 350,000, more preferably 15,000 to 200,000, and even more preferably 20,000 to 50,000.

<< Content of (b2) component >>
The total content of the polyfunctional (meth) acrylate prepolymer in the polymerizable composition (x-1') is based on the total amount (100% by mass) of the active ingredient of the polymerizable composition (x-1'). It is preferably 10 to 60% by mass, more preferably 15 to 55% by mass, and even more preferably 20 to 30% by mass.
The total content of the component (b2) in the polymerizable composition (x-1') is preferably 10 to 10 to the total amount (100% by mass) of the active ingredient of the polymerizable composition (x-1'). It is 60% by mass, more preferably 15 to 55% by mass, and even more preferably 20 to 30% by mass.

The content ratios of the component (b2) and the component (b1) in the polymerizable composition (x-1') [(b2) / (b1)] are preferably 10/90 to 70/30 on a mass basis. , More preferably 20/80 to 50/50, and even more preferably 25/75 to 40/60.

Among the above energy ray polymerizable components, the polymerizable composition (x-1') preferably contains a polymerizable vinyl monomer, a polyfunctional (meth) acrylate monomer and a polyfunctional (meth) acrylate prepolymer.
The total content of the polymerizable vinyl monomer, the polyfunctional (meth) acrylate monomer and the polyfunctional (meth) acrylate prepolymer in the energy ray-polymerizable component contained in the polymerizable composition (x-1') is the energy ray. With respect to the total amount (100% by mass) of the polymerizable component, it is preferably 80% by mass or more, more preferably 90% by mass or more, further preferably 95% by mass or more, still more preferably 99% by mass or more, and 100% by mass. May be%.

The total content of the energy ray-polymerizable component in the polymerizable composition (x-1') is preferably 70 with respect to the total amount (100% by mass) of the active ingredient of the polymerizable composition (x-1'). It is ~ 98% by mass, more preferably 75 to 97% by mass, still more preferably 80 to 96% by mass, still more preferably 82 to 95% by mass.

(Other ingredients)
The polymerizable composition (x-1') may contain other components other than the energy ray-polymerizable component and the heat-expandable particles.
Examples of the other components include a photopolymerization initiator, a tackifier, and an additive for a pressure-sensitive adhesive used in a general pressure-sensitive adhesive other than the above-mentioned components.
Examples of these components include the same as those described in the pressure-sensitive adhesive sheet of the first aspect.

The polymerizable composition (x-1') may contain a solvent such as a diluent as long as it does not contradict the object of the present invention, but it is preferably not contained. That is, the polymerizable composition (x-1') is preferably a solvent-free polymerizable composition.
Since the polymerizable composition (x-1') is a solvent-free polymerizable composition, it is possible to omit heating and drying the solvent when forming the pressure-sensitive adhesive layer (X1). It is possible to suppress the expansion of the heat-expandable particles in.
When the polymerizable composition (x-1') contains a solvent, the smaller the content, the more preferable, and it is preferable with respect to the total amount (100% by mass) of the active ingredient of the polymerizable composition (x-1'). Is 10% by mass or less, more preferably 1% by mass or less, still more preferably 0.1% by mass or less, still more preferably 0.01% by mass or less.

The polymerizable composition (x-1') can be produced by mixing an energy ray-polymerizable component, thermally expandable particles, and other components contained as necessary.
The method for mixing each component is not particularly limited, and may be appropriately selected from known mixing methods according to the type of component used, the viscosity of the resin composition, and the like.
Since the polymerizable composition (x-1') contains the heat-expandable particles, a dispersion treatment for improving the dispersibility of the heat-expandable particles in the polymerizable composition (x-1'). May be applied. By improving the dispersibility of the heat-expandable particles, the surface of the pressure-sensitive adhesive layer (X1) becomes smoother, and the arithmetic mean waviness (Wa) of the surface (S _x1 ) of the pressure-sensitive adhesive layer (X1) becomes smaller. be able to.
As the method for dispersing the heat-expandable particles, the same method as the method for treating the dispersion of the heat-expandable particles described in the "resin composition (y-1)" of the above-mentioned "adhesive sheet of the first aspect" can be mentioned. Be done.

Since the polymerizable composition (x-1') is made to have a high molecular weight by subsequent energy ray polymerization, the viscosity can be adjusted to an appropriate level by a low molecular weight energy ray polymerizable component when forming a layer. Is. Therefore, the polymerizable composition (x-1') can be used as it is as a coating solution for forming the pressure-sensitive adhesive layer (X1) without adding a solvent such as a diluent.
The pressure-sensitive adhesive layer (X1) formed by irradiating the polymerizable composition (x-1') with energy rays contains a wide variety of polymers obtained by polymerizing energy ray-polymerizable components and the weight thereof. There are circumstances in which the heat-expandable particles dispersed in the coalescence are included, but it is impossible or nearly impractical to directly identify them by structure and physical properties.

(Adhesive strength of the adhesive layer (X1))
The description of the adhesive force before thermal expansion and the adhesive force after thermal expansion of the pressure-sensitive adhesive layer (X1) in the pressure-sensitive adhesive sheet of the second aspect is described in the description of the heat-expandable base material layer in the description of the pressure-sensitive adhesive sheet of the first aspect. The same as the description of the adhesive strength of the adhesive layer (X1) before the thermal expansion of (Y1) and the adhesive strength of the adhesive layer (X1) after the thermal expansion of the thermally expandable base material layer (Y1). be.

(Thickness of adhesive layer (X1))
The thickness of the pressure-sensitive adhesive layer (X1) of the pressure-sensitive adhesive sheet of the second aspect before thermal expansion is preferably 20 to 270 μm, more preferably 30 to 240 μm, still more preferably 40 to 220 μm, still more preferably 50 to. It is 200 μm.
When the thickness of the pressure-sensitive adhesive layer (X1) before thermal expansion is 20 μm or more, the generation of irregularities due to the heat-expandable particles before thermal expansion is suppressed, and the surface (S _x1 ) of the pressure-sensitive adhesive layer (X1). The arithmetic mean swell (Wa) of the above can be further reduced, and the stickability tends to be improved. Further, when the thickness of the pressure-sensitive adhesive layer (X1) before thermal expansion is 270 μm or less, the pressure-sensitive adhesive sheet tends to be easy to handle.

<Method for manufacturing the adhesive sheet of the second aspect>
In the method for producing the pressure-sensitive adhesive sheet according to the second aspect, the method for forming the pressure-sensitive adhesive layer (X1) is a polymerizable composition (x-1') containing the energy ray-polymerizable component and the heat-expandable particles. A method for producing a pressure-sensitive adhesive sheet, which comprises a step of irradiating with energy rays to form a polymer of the energy ray-polymerizable component, is preferable, and specifically includes the following steps (1b) and (2b). It is more preferable that it is a manufacturing method.
Step (1b): A step of forming a polymerizable composition layer composed of the polymerizable composition (x-1') on one surface side of the base material (Y) Step (2b): On the polymerizable composition layer. A step of forming a polymer of the energy ray-polymerizable component by irradiating with energy rays to form a pressure-sensitive adhesive layer (X1) containing the polymer and the heat-expandable particles to obtain a pressure-sensitive adhesive sheet.

Further, the pressure-sensitive adhesive sheet of the second aspect has a structure in which the pressure-sensitive adhesive layer (X1), the base material layer (Y), and the pressure-sensitive adhesive layer (X2) are arranged in this order. If so, the pressure-sensitive adhesive sheet can be further produced by a method having the following step (3b).
Step (3b): A step of forming the pressure-sensitive adhesive layer (X2) on the surface of the base material layer (Y) of the pressure-sensitive adhesive sheet formed in step (2b) on the side opposite to the laminated surface of the pressure-sensitive adhesive layer (X1).

In the step (1b), for example, the polymerizable composition (x-1') is applied on the peeling surface of the release material to form a polymerizable composition layer, and the polymerizable composition layer is subjected to the process. Examples thereof include a method in which the first energy ray irradiation is performed to prepolymerize the energy ray-polymerizable component in the polymerizable composition layer, and then the base material (Y) is attached to the polymerizable composition layer after the prepolymerization. ..
As described above, the polymerizable composition (x-1') is preferably a solvent-free polymerizable composition. When the polymerizable composition (x-1') is a solvent-free polymerizable composition, it is not necessary to carry out the heat-drying step of the solvent in this step, and the expansion of the heat-expandable particles can be suppressed. ..

In the step (2b), the polymerizable composition layer formed in the step (1b) is irradiated with energy rays to form a polymer of the energy ray-polymerizable component, and the polymer and the heat-expandable particles are contained. This is a step of forming the pressure-sensitive adhesive layer (X1).
Here, when the first energy ray irradiation is performed in the step (1b), the energy ray irradiation in the step (2b) is the second energy ray irradiation performed on the polymerizable composition layer after the prepolymerization.
The energy ray irradiation in the step (2b) is different from the first energy ray irradiation, and it is preferable that the energy ray irradiation is performed to such an extent that the polymerization of the energy ray-polymerizable component does not substantially proceed even if the energy rays are further irradiated. By the energy ray irradiation in the step (2b), the polymerization of the energy ray-polymerizable component proceeds, and the polymer of the energy ray-polymerizable component constituting the pressure-sensitive adhesive layer (X1) is formed.

In the step (3b), the pressure-sensitive adhesive composition (x-2) is applied to one surface of the release material to form a pressure-sensitive adhesive layer (X2), and the pressure-sensitive adhesive layer (X2) is used as a base material (Y). A method of sticking to the other side of the surface can be mentioned.

In any of the above steps, it is preferable not to include a step of heating the polymerizable composition from the viewpoint of suppressing the expansion of the heat-expandable particles.
The term "heating" here means, for example, intentionally heating during drying, laminating, etc., and is a heat or energy ray-polymerizable composition imparted to the polymerizable composition by energy ray irradiation. The temperature rise due to the heat of polymerization generated by the polymerization is not included.

<Release material>
As the release material that the pressure-sensitive adhesive sheet of one aspect of the present invention may have, a release sheet that has been subjected to double-sided release treatment, a release sheet that has been subjected to single-sided release treatment, or the like is used, and the release material is peeled off onto a substrate for the release material. Examples thereof include those coated with an agent.
Examples of the base material for the release material include plastic films and papers. Examples of the plastic film include polyester resin films such as polyethylene terephthalate resin, polybutylene terephthalate resin, and polyethylene naphthalate resin; olefin resin films such as polypropylene resin and polyethylene resin, and examples of papers include high-quality paper. , Glassin paper, kraft paper, etc.

Examples of the release agent include rubber-based elastomers such as silicone-based resins, olefin-based resins, isoprene-based resins, and butadiene-based resins; long-chain alkyl-based resins, alkyd-based resins, and fluorine-based resins. As the release agent, one type may be used alone, or two or more types may be used in combination.

The thickness of the release material is preferably 10 to 200 μm, more preferably 20 to 150 μm, and even more preferably 35 to 80 μm.

[Use and usage of adhesive sheet]
Since the pressure-sensitive adhesive sheet according to one aspect of the present invention can be easily peeled off by heating the temporarily fixed adherend, it can be applied to various uses. Specifically, for example, a dicing sheet used when dicing an adherend such as a semiconductor wafer, a back grind sheet used in a process of grinding an adherend, a substrate such as a semiconductor chip individualized by dicing. Expanded tape used to increase the distance between the bodies, transfer tape used to invert the front and back of the adherend such as a semiconductor chip, and a temporary fixing sheet for temporarily fixing and inspecting the inspection object. Etc. are suitable.

The adherend of the pressure-sensitive adhesive sheet according to one aspect of the present invention is not particularly limited, and examples thereof include semiconductor chips, semiconductor wafers, compound semiconductors, semiconductor packages, electronic components, sapphire substrates, displays, and panel substrates.
In the pressure-sensitive adhesive sheet of one aspect of the present invention, when the expansion start temperature (t) of the heat-expandable particles is set to less than 125 ° C., heat peeling is possible at a low temperature, so that the heat changes in the semiconductor chip with DAF or the like. It is suitable for temporarily fixing an easily adherent body.
Further, in the pressure-sensitive adhesive sheet of one aspect of the present invention, when the expansion start temperature (t) of the heat-expandable particles is set to 50 ° C. or higher, the heat-expandable particles due to temperature rise such as when grinding the adherend. It is suitable for use as a back grind sheet used in the process of grinding an adherend because it can suppress unintended expansion.

The heating temperature at which the pressure-sensitive adhesive sheet according to one aspect of the present invention is heat-peeled from the adherend is equal to or higher than the expansion start temperature (t) of the heat-expandable particles, and is preferably “a temperature higher than the expansion start temperature (t)”. , More preferably "expansion start temperature (t) + 2 ° C." or higher, further preferably "expansion start temperature (t) + 4 ° C." or higher, and even more preferably "expansion start temperature (t) + 5 ° C." or higher. Further, from the viewpoint of energy saving and suppressing the thermal change of the adherend at the time of heat peeling, it is preferably "expansion start temperature (t) + 50 ° C." or less, more preferably "expansion start temperature (t) + 40 ° C." or less. More preferably, it is "expansion start temperature (t) + 20 ° C." or less.
Further, the heating temperature at the time of heat peeling is preferably less than 125 ° C., more preferably 120 ° C. or lower, and further, within the range of the expansion start temperature (t) or higher, from the viewpoint of suppressing the thermal change of the adherend. It is preferably 115 ° C. or lower, more preferably 110 ° C. or lower, and even more preferably 105 ° C. or lower.

The heating method is not particularly limited as long as it can be heated to a temperature higher than the temperature at which the heat-expandable particles expand, and for example, an electric heater; dielectric heating; magnetic heating; near-infrared rays, mid-infrared rays, and far-infrared rays. It is possible to appropriately use heating by electromagnetic waves such as infrared rays. The heating method may be any of a contact type heating method such as a heating roller and a heating press; a non-contact type heating method such as an atmosphere heating device and infrared irradiation.

[Manufacturing method of semiconductor devices]
The present invention also provides a method for manufacturing a semiconductor device using the pressure-sensitive adhesive sheet according to one aspect of the present invention.
As one aspect of the method for manufacturing a semiconductor device of the present invention, the pressure-sensitive adhesive sheet according to the present invention is used as a temporary fixing sheet for processing or inspecting an adherend at least one of them (hereinafter referred to as a temporary fixing sheet). , Also referred to as "a method for manufacturing a semiconductor device of the first aspect").
In addition, in this specification, a "semiconductor device" refers to a whole device which can function by utilizing a semiconductor characteristic. For example, a wafer with an integrated circuit, a thinned wafer with an integrated circuit, a chip with an integrated circuit, a thinned chip with an integrated circuit, an electronic component containing these chips, and an electronic component with the electronic component. Kind and the like.

<Manufacturing method of semiconductor device of the first aspect>
As a more specific aspect of the method for manufacturing a semiconductor device of the first aspect, a processing inspection object is attached to the pressure-sensitive adhesive sheet of one aspect of the present invention, and the processing inspection object is selected from processing and inspection. A method for manufacturing a semiconductor device, which comprises a step of heating the pressure-sensitive adhesive sheet to the expansion start temperature (t) or higher after applying the above-mentioned one or more.
Examples of the processing inspection object include semiconductor chips, semiconductor wafers, compound semiconductors, semiconductor packages, electronic components, LED elements, sapphire substrates, displays, panel substrates, and the like.
The processing performed on the object to be inspected is not particularly limited, and examples thereof include a grinding process and an individualization process.
The inspection performed on the object to be processed is not particularly limited, but for example, defect inspection using an optical microscope and a laser (for example, dust inspection, surface scratch inspection, wiring pattern inspection, etc.), visual surface inspection, etc. are performed. Can be mentioned.

In the method for manufacturing a semiconductor device according to the first aspect, the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet to which the object to be processed and inspected is attached may be the pressure-sensitive adhesive layer (X1), and when the pressure-sensitive adhesive sheet is a double-sided pressure-sensitive adhesive sheet, it is pressure-sensitive. It may be an agent layer (X2).
When the pressure-sensitive adhesive sheet is a double-sided pressure-sensitive adhesive sheet, it is preferable to attach the object to be processed and inspected to one pressure-sensitive adhesive layer and to attach a support to the other pressure-sensitive adhesive layer. By fixing the object to be inspected to the support via the adhesive sheet, vibration, misalignment, damage to the fragile object to be inspected, etc. are suppressed during the processing, and processing is performed. The accuracy and processing speed can be improved. Further, since the adhesive sheet according to one aspect of the present invention has excellent adhesiveness, vibration, misalignment, damage to the object to be processed, etc. due to the generation of air pools at the adhesive interface between the adhesive sheet and the adherend can be prevented. It can be suppressed more effectively. At this time, the support may be attached to the pressure-sensitive adhesive layer (X1) and the object to be processed and inspected may be attached to the pressure-sensitive adhesive layer (X2), or the object to be processed and inspected may be attached to the pressure-sensitive adhesive layer (X1). The support may be attached to the pressure-sensitive adhesive layer (X2).
When the support is attached to the pressure-sensitive adhesive layer (X1) and the object to be processed is attached to the pressure-sensitive adhesive layer (X2), the support has excellent peelability after heat treatment (X1). Even if the support is made of a hard material, it can be heat-peeled without bending the adhesive sheet and the support. Further, the composition of the pressure-sensitive adhesive layer (X2) may be appropriately selected according to the type of the object to be processed and the like. Then, the object to be processed and inspected can be peeled off without being contaminated by the residue derived from the heat-expandable particles.
On the other hand, when the object to be processed and inspected is attached to the pressure-sensitive adhesive layer (X1) and the support is attached to the pressure-sensitive adhesive layer (X2), the object to be processed and inspected is an adhesive having excellent peelability after heat treatment. By being attached to the layer (X1), the object to be processed and inspected can be easily peeled off from the adhesive sheet after processing, so that damage to the object to be processed and inspected can be reduced.

<Manufacturing method of semiconductor device of the second aspect>
In the method for manufacturing the semiconductor device of the second aspect, the pressure-sensitive adhesive layer (X1), the base material layer (Y), and the pressure-sensitive adhesive layer (X2) are arranged in this order as the pressure-sensitive adhesive sheet of one aspect of the present invention. Examples thereof include a manufacturing method (hereinafter, also referred to as “manufacturing method A”) including the following steps 1A, 2A, a first separation step, and a second separation step using the pressure-sensitive adhesive sheet having the laminated structure.
Step 1A: A process of attaching a processing object to the pressure-sensitive adhesive layer (X2) of the pressure-sensitive adhesive sheet, and attaching a support to the pressure-sensitive adhesive layer (X1) of the pressure-sensitive adhesive sheet Step 2A: A process of attaching a support to the pressure-sensitive adhesive layer (X1). On the other hand, a step of performing one or more treatments selected from a grinding treatment and an individualization treatment. First separation step: The pressure-sensitive adhesive sheet is heated to a temperature (t) or higher at which the heat-expandable particles start to expand, and described above. Step of separating the pressure-sensitive adhesive layer (X1) and the support Second separation step: A step of separating the pressure-sensitive adhesive layer (X2) and the object to be processed.

Hereinafter, the manufacturing method A will be described with reference to the drawings. In the following description, an example in which a semiconductor wafer is used as a processing object will be mainly described, but the same applies to other processing objects. Examples of other processing objects include the same objects as described above as processing inspection objects.

(Step 1A)
Step 1A is a step of attaching the object to be processed to the pressure-sensitive adhesive layer (X2) of the pressure-sensitive adhesive sheet and attaching a support to the pressure-sensitive adhesive layer (X1).
In FIGS. 3A and 3B, the semiconductor wafer W is attached to the pressure-sensitive adhesive layer (X2) of the pressure-sensitive adhesive sheet 2a, and the surface of the support 3 (S _x1 ) is attached to the surface (S x1) of the pressure-sensitive adhesive layer (X1). A cross-sectional view illustrating the process of attaching S _s ) is shown.
The semiconductor wafer W is attached so that the surface W1 which is the circuit surface is on the pressure-sensitive adhesive layer (X2) side.
The semiconductor wafer W may be a silicon wafer, a wafer such as gallium arsenic, silicon carbide, sapphire, lithium tantalate, lithium niobate, gallium nitride, indium phosphorus, or a glass wafer.
The thickness of the semiconductor wafer W before grinding is usually 500 to 1000 μm.
The circuit included in the surface W1 of the semiconductor wafer W can be formed by, for example, a conventionally used general-purpose method such as an etching method or a lift-off method.

The material of the support 3 may be appropriately selected in consideration of required characteristics such as mechanical strength and heat resistance according to the type of the object to be processed, the content of processing and the like.
Examples of the material of the support 3 include metal materials such as SUS; non-metal inorganic materials such as glass and silicon wafers; epoxy resin, ABS resin, acrylic resin, engineering plastic, super engineering plastic, polyimide resin, polyamideimide resin and the like. Resin materials; Composite materials such as glass epoxy resin are mentioned, and among these, SUS, glass, and silicon wafers are preferable.
Examples of the engineering plastic include nylon, polycarbonate (PC), polyethylene terephthalate (PET) and the like.
Examples of the super engineering plastic include polyphenylene sulfide (PPS), polyethersulfone (PES), and polyetheretherketone (PEEK).

The support 3 is preferably attached to the entire surface of the adhesive surface of the adhesive layer (X1). Therefore, the area of the surface of the support 3 on the side to be attached to the adhesive surface of the adhesive layer (X1) is preferably equal to or larger than the area of the adhesive surface of the adhesive layer (X1). Further, it is preferable that the surface of the support 3 on the side to be attached to the adhesive surface of the adhesive layer (X1) is flat.
The shape of the support 3 is not particularly limited, but is preferably plate-shaped.
The thickness of the support 3 may be appropriately selected in consideration of the required characteristics, but is preferably 20 μm or more and 50 mm or less, and more preferably 60 μm or more and 20 mm or less.

In the step of attaching the support 3 to the adhesive layer (X1) of the adhesive sheet 2a in the step 1A, the surface (SX1) of the adhesive layer ( _X1 ) and the adhesive sheet 2a of the support 3 are attached. A step of attaching the surface (S _s ) of the support 3 to the surface (SX1) of the adhesive layer ( _X1 ) while maintaining a state in which the surface (S _s ) is substantially parallel (hereinafter, "surface attachment"). Step A ”) is preferable.
Since the pressure-sensitive adhesive sheet according to one aspect of the present invention has excellent stickability, it is possible to suppress the generation of air pools at the bonding interface between the pressure-sensitive adhesive sheet 2a and the support 3 even if the surface-sticking step A is performed.
In the surface attachment step A, for example, after the object to be processed is attached to the adhesive layer (X2) of the adhesive sheet 2a, the surface of the adhesive layer (X1) of the adhesive sheet 2a attached to the object to be processed. (SX1) and the surface (S _s ) to which the adhesive sheet 2a of the support 3 is attached are maintained in a substantially parallel state, and the support is placed on the surface ( _SX1 ) of the adhesive layer ( _X1 ). The step of pasting the surface (S _s ) of 3 can be mentioned.
In the present specification, "substantially parallel" means a state of less than 0 degrees ± 10 degrees from the parallel direction, preferably within 0 degrees ± 5 degrees, and more preferably within 0 degrees ± 1 degrees. Is.

The sticking in the step 1A may be carried out while crimping, heating, depressurizing or the like, if necessary.
The crimping pressure is preferably 0.12 to 1.0 MPa, more preferably 0.15 to 0.7 MPa, and even more preferably 0.17 to 0.5 MPa from the viewpoint of stickability and productivity. When the crimping pressure is 0.12 MPa or more, more excellent stickability tends to be obtained. Further, when the crimping pressure is 1.0 MPa or less, more excellent productivity tends to be obtained. The crimping may be a method of pressing on a flat surface or a method of applying a linear pressure by a roll. The crimping pressure here means the pressure applied to the affixed object. For example, when both the pressure applied by the pressurizing mechanism of the device and the atmospheric pressure are applied to the affixed object, the pressurization of the device is applied. The total pressure of the pressure applied by the mechanism and the atmospheric pressure is the crimping pressure.
The heating temperature is preferably 40 to 88 ° C., more preferably 45 to 80 ° C., and even more preferably 50 to 70 ° C. from the viewpoint of stickability and productivity. When the heating temperature is 40 ° C. or higher, better stickability tends to be obtained. Further, when the heating temperature is 88 ° C. or lower, more excellent productivity tends to be obtained.
The crimping or heating time is preferably 5 to 120 seconds, more preferably 10 to 60 seconds, and even more preferably 20 to 40 seconds from the viewpoint of stickability and productivity. When the crimping time is 5 seconds or more, better adhesiveness tends to be obtained. Further, when the crimping time is 120 seconds or less, more excellent productivity tends to be obtained.
The atmospheric pressure when the pressure is reduced at the time of sticking is preferably 50 hPa or less, more preferably 10 hPa or less, still more preferably 5 hPa or less, from the viewpoint of stickability and productivity. The lower limit of the atmospheric pressure is not particularly limited and may be 0 hPa.

(Step 2A)
Step 2A is a step of performing one or more processes selected from a grinding process and an individualizing process on the object to be processed.
One or more processes selected from the grinding process and the individualizing process include, for example, a grinding process using a grinder or the like; an individualizing process by a blade dicing method, a laser dicing method, a stealth dicing (registered trademark) method; a blade tip. Examples include a dicing method, a grinding process and an individualization process by a stealth tip dicing method; and the like.
Among these, the individualization treatment by the stealth dicing method, the grinding treatment and the individualization treatment by the blade tip dicing method, the grinding treatment and the individualization treatment by the stealth tip dicing method are preferable, and the grinding treatment by the blade tip dicing method is preferable. Further, individualization treatment, grinding treatment by stealth dicing method, and individualization treatment are more preferable.

The stealth dicing method is a method in which a modified region is formed inside a semiconductor wafer by irradiation with laser light, and the semiconductor wafer is individualized using the modified region as a division starting point. The modified region formed on the semiconductor wafer is a portion brittled by multiphoton absorption, and the modified region is applied by applying stress in the direction in which the semiconductor wafer is parallel to the wafer surface and the wafer is expanded by expansion. As a starting point, cracks extend toward the front surface and the back surface of the semiconductor wafer, so that the wafer is individualized into a semiconductor chip. That is, the modified region is formed along the dividing line when it is fragmented.
The modified region is formed inside the semiconductor wafer by irradiation with a laser beam focused on the inside of the semiconductor wafer. The incident surface of the laser beam may be the front surface or the back surface of the semiconductor wafer. Further, the laser light incident surface may be a surface to which the adhesive sheet is attached, in which case the laser light is applied to the semiconductor wafer via the adhesive sheet.

The blade tip dicing method is also called the DBG method (Dicing Before Grinding). In the blade tip dicing method, a groove is formed in the semiconductor wafer in advance along the line to be divided at a depth shallower than the thickness, and then the semiconductor wafer is back-ground to make it thinner until the grinding surface reaches at least the groove. It is a method of individualizing while making it into individual pieces. The groove reached by the grinding surface becomes a notch penetrating the semiconductor wafer, and the semiconductor wafer is divided by the notch and individualized into semiconductor chips. The pre-formed groove is usually provided on the surface (circuit surface) of the semiconductor wafer, and can be formed by dicing using, for example, a conventionally known wafer dicing device provided with a dicing blade.

The stealth dicing method is also called the SDBG method (Stealth Dicing Before Grinding). Similar to the stealth dicing method, the stealth dicing method is a kind of a method of forming a modified region inside a semiconductor wafer by irradiation with laser light and using the modified region as a division starting point to individualize the semiconductor wafer. However, it differs from the stealth dicing method in that the semiconductor wafer is separated into semiconductor chips while thinning the semiconductor wafer by grinding. Specifically, while the semiconductor wafer having a modified region is ground on the back surface to be thinned, the pressure applied to the semiconductor wafer at that time causes the modified region as a starting point toward the surface to be attached to the pressure-sensitive adhesive layer of the semiconductor wafer. The cracks are extended and the semiconductor wafer is separated into semiconductor chips.
The grinding thickness after forming the modified region may be the thickness reaching the modified region, but even if it does not reach the modified region strictly, it is ground to a position close to the modified region. Then, it may be cut by the processing pressure of a grinding wheel or the like.

When the semiconductor wafer W is individualized by the blade tip dicing method, it is preferable to form a groove in advance on the surface W1 of the semiconductor wafer W to be attached to the pressure-sensitive adhesive layer (X2) in step 1A.
On the other hand, when the semiconductor wafer W is individualized by the stealth dicing method, the semiconductor wafer W to be attached to the pressure-sensitive adhesive layer (X2) is irradiated with laser light in step 1A to form a modified region in advance. Alternatively, the semiconductor wafer W attached to the pressure-sensitive adhesive layer (X2) may be irradiated with laser light to form a modified region.

FIG. 4 shows a cross-sectional view illustrating a step of forming a plurality of modified regions 5 on the semiconductor wafer W attached to the pressure-sensitive adhesive layer (X2) by using the laser light irradiation device 4.
The laser beam is irradiated from the back surface W2 side of the semiconductor wafer W, and a plurality of modified regions 5 are formed inside the semiconductor wafer W at substantially equal intervals.

FIGS. 5A and 5B show cross-sectional views illustrating a process of thinning the semiconductor wafer W and separating it into a plurality of semiconductor chip CPs.
As shown in FIG. 5A, the back surface W2 of the semiconductor wafer W on which the modified region 5 is formed is ground by a grinder 6, and at that time, the pressure applied to the semiconductor wafer W causes splitting starting from the modified region 5. Causes. As a result, as shown in FIG. 5B, a plurality of semiconductor chip CPs in which the semiconductor wafer W is thinned and fragmented can be obtained.
The back surface W2 of the semiconductor wafer W on which the modified region 5 is formed is ground, for example, with the support 3 supporting the semiconductor wafer W fixed on a fixed table such as a chuck table.

The thickness of the semiconductor chip CP after grinding is preferably 5 to 100 μm, more preferably 10 to 45 μm. Further, when the grinding process and the individualization process are performed by the stealth tip dicing method, the thickness of the semiconductor chip CP obtained by grinding can be easily set to 50 μm or less, more preferably 10 to 45 μm.
The size of the semiconductor chip CP after grinding in a plan view is preferably less than 600 mm ² , more preferably less than 400 mm ² , and even more preferably less than 300 mm ² . In addition, the plan view means to see in the thickness direction.
The shape of the semiconductor chip CP after being fragmented in a plan view may be a square shape or an elongated shape such as a rectangle.

(Step 3A)
The production method A preferably further includes the following step 3A.
Step 3A: A step of attaching a thermosetting film to the surface of the processed object to be processed, which is opposite to the pressure-sensitive adhesive layer (X2). However, in the manufacturing method A, the step 3A is an arbitrary step. The embodiment may not include step 3A.
When step 3A is performed, the expansion start temperature (t) of the heat-expandable particles contained in the pressure-sensitive adhesive sheet used in the production method A is preferably 50 ° C. or higher and lower than 125 ° C. This makes it possible to prevent the thermosetting film from being unintentionally cured when the first separation step described later is performed.

FIG. 6 illustrates a step of attaching a thermosetting film 7 provided with a support sheet 8 to a surface of a plurality of semiconductor chip CPs obtained by the above treatment on a surface opposite to the pressure-sensitive adhesive layer (X2). A cross-sectional view is shown.

The thermosetting film 7 is a film having thermosetting property obtained by forming a resin composition containing at least a thermosetting resin, and is used as an adhesive when mounting a semiconductor chip CP on a substrate. The thermosetting film 7 may contain a curing agent for the thermosetting resin, a thermoplastic resin, an inorganic filler, a curing accelerator, and the like, if necessary.
As the thermosetting film 7, for example, a thermosetting film generally used as a die bonding film, a die attach film, or the like can be used.
The thickness of the thermosetting film 7 is not particularly limited, but is usually 1 to 200 μm, preferably 3 to 100 μm, and more preferably 5 to 50 μm.
The support sheet 8 may be any as long as it can support the thermosetting film 7. For example, the resin, metal, or paper mentioned as the non-thermally expandable base material layer (Y2) included in the pressure-sensitive adhesive sheet of one aspect of the present invention. Materials and the like can be mentioned.

Examples of the method of attaching the thermosetting film 7 to a plurality of semiconductor chip CPs include a method of laminating.
Laminating may be performed while heating or may be performed without heating. The heating temperature when the laminating is performed while heating is preferably "a temperature lower than the expansion start temperature (t)" from the viewpoint of suppressing the expansion of the heat-expandable particles and suppressing the thermal change of the adherend. It is preferably "expansion start temperature (t) -5 ° C." or less, more preferably "expansion start temperature (t) -10 ° C." or less, and even more preferably "expansion start temperature (t) -15 ° C." or less.

(First separation process)
The first separation step is a step of heating the pressure-sensitive adhesive sheet to a temperature equal to or higher than the expansion start temperature (t) of the heat-expandable particles to separate the pressure-sensitive adhesive layer (X1) from the support.
FIG. 7 shows a cross-sectional view illustrating a step of heating the pressure-sensitive adhesive sheet 2a to separate the pressure-sensitive adhesive layer (X1) and the support 3.

The heating temperature in the first separation step is equal to or higher than the expansion start temperature (t) of the thermally expandable particles, preferably "a temperature higher than the expansion start temperature (t)", and more preferably "expansion start temperature (t) + 2 ° C." , More preferably "expansion start temperature (t) + 4 ° C." or higher, and even more preferably "expansion start temperature (t) + 5 ° C." or higher. Further, the heating temperature in the first separation step is preferably "expansion start temperature (t) + 50 ° C." or less in the range of less than 125 ° C. from the viewpoint of energy saving and suppressing the thermal change of the adherend at the time of heat peeling. , More preferably "expansion start temperature (t) + 40 ° C." or less, still more preferably "expansion start temperature (t) + 20 ° C." or less.
The heating temperature in the first separation step is preferably less than 125 ° C., more preferably 120 ° C. or lower, still more preferably 120 ° C. or higher within the range of the expansion start temperature (t) or higher from the viewpoint of suppressing the thermal change of the adherend. It is 115 ° C. or lower, more preferably 110 ° C. or lower, and even more preferably 105 ° C. or lower. In particular, when the heating temperature in the first separation step is less than 125 ° C., it is possible to prevent the thermosetting film from being unintentionally cured when the above-mentioned step 3A is performed.

(Second separation step)
The second separation step is a step of separating the pressure-sensitive adhesive layer (X2) and the object to be processed.
FIG. 8 shows a cross-sectional view illustrating a step of separating the pressure-sensitive adhesive layer (X2) and the plurality of semiconductor chip CPs.
The method for separating the pressure-sensitive adhesive layer (X2) and the plurality of semiconductor chip CPs may be appropriately selected according to the type of the pressure-sensitive adhesive layer (X2). For example, when the pressure-sensitive adhesive layer (X2) is a pressure-sensitive adhesive layer whose adhesive strength is reduced by irradiation with energy rays, the pressure-sensitive adhesive layer (X2) is irradiated with energy rays to reduce the pressure-sensitive adhesive strength. It should be separated.

Through each of the above steps, a plurality of semiconductor chip CPs attached on the thermosetting film 7 can be obtained.
Next, it is preferable to divide the thermosetting film 7 to which the plurality of semiconductor chip CPs are attached into the same shape as the semiconductor chip CP to obtain the semiconductor chip CP with the thermosetting film 7. As a method for dividing the thermosetting film 7, for example, a method such as laser dicing with laser light, expanding, and fusing can be applied.
FIG. 9 shows a semiconductor chip CP with a thermosetting film 7 divided into the same shape as the semiconductor chip CP.

The semiconductor chip CP with the thermosetting film 7 further includes an expanding step of widening the distance between the semiconductor chip CPs, a rearrangement step of arranging a plurality of semiconductor chip CPs having a wide distance, and a plurality of semiconductor chip CPs. After an appropriate inversion step of inverting the front and back of the above, the heat-curable film 7 is attached (diatached) to the substrate from the side. After that, the semiconductor chip and the substrate can be fixed by thermosetting the thermosetting film.

In the method for manufacturing the semiconductor device of the second aspect, the pressure-sensitive adhesive layer (X1), the base material layer (Y), and the pressure-sensitive adhesive layer (X2) are arranged in this order as the pressure-sensitive adhesive sheet of one aspect of the present invention. A manufacturing method including the following steps 1B to 2B, the following first separation step, and the second separation step (hereinafter, also referred to as “manufacturing method B”) may be used by using the pressure-sensitive adhesive sheet having the laminated structure.
Step 1B: A process of attaching a processing object to the pressure-sensitive adhesive layer (X1) of the pressure-sensitive adhesive sheet, and attaching a support to the pressure-sensitive adhesive layer (X2) of the pressure-sensitive adhesive sheet Step 2B: A process of attaching a support to the pressure-sensitive adhesive layer (X2). On the other hand, a step of performing one or more treatments selected from a grinding treatment and an individualization treatment. First separation step: The pressure-sensitive adhesive sheet is heated to a temperature (t) or higher at which the heat-expandable particles start to expand, and described above. Step of separating the pressure-sensitive adhesive layer (X1) and the object to be processed Second separation step: Step of separating the pressure-sensitive adhesive layer (X2) and the support.

The production method B preferably further includes the following step 3B.
Step 3B: A step of attaching a thermosetting film to the surface of the processed object to be processed, which is opposite to the pressure-sensitive adhesive layer (X1). However, in the manufacturing method B, step 3B is an arbitrary step. , The embodiment may not have step 3B.
When step 3B is performed, the expansion start temperature (t) of the heat-expandable particles contained in the pressure-sensitive adhesive sheet used in the production method B is preferably 50 ° C. or higher and lower than 125 ° C. This makes it possible to prevent the thermosetting film from being unintentionally cured when the first separation step described later is performed.

In the step of attaching the object to be processed to the pressure-sensitive adhesive layer (X1) of the pressure-sensitive adhesive sheet 2a in step 1B, the surface (SX1) of the pressure-sensitive adhesive layer ( _X1 ) and the pressure-sensitive adhesive sheet 2a of the object to be processed are attached. A process of attaching the surface (S _w ) of the object to be processed to the surface (SX1) of the adhesive layer ( _X1 ) while maintaining a state in which the surface (S _w ) is substantially parallel (hereinafter, "surface application"). Step B ”) is preferable.
In the surface attachment step B, for example, after the support 3 is attached to the adhesive layer (X2) of the adhesive sheet 2a, the surface of the adhesive layer (X1) of the adhesive sheet 2a attached to the support 3 is attached. (SX1) and the surface (S _w ) to which the adhesive sheet 2a of the object to be processed is attached are maintained in a substantially parallel state, and are processed on the surface ( _SX1 ) of the adhesive layer ( _X1 ). The process of pasting the surface (S _w ) of an object can be mentioned.
Since the pressure-sensitive adhesive sheet according to one aspect of the present invention has excellent stickability, it is possible to suppress the generation of air pools at the bonding interface between the pressure-sensitive adhesive sheet 2a and the object to be processed even if the surface-sticking step B is performed.

The application in step 1B may be carried out while pressurizing, heating, depressurizing, etc., if necessary, and the suitable conditions are the same as the suitable conditions described in step 1A.

Steps 1B to 3B are described by replacing the pressure-sensitive adhesive layer (X1) with the pressure-sensitive adhesive layer (X2) and the pressure-sensitive adhesive layer (X2) with the pressure-sensitive adhesive layer (X1) in the description of steps 1A to 3A. ..

The first separation step is a step of heating the pressure-sensitive adhesive sheet to the expansion start temperature (t) or higher to separate the pressure-sensitive adhesive layer (X1) from the object to be processed.
The heating conditions such as the heating temperature of the pressure-sensitive adhesive sheet in the first separation step are the same as those described in the manufacturing method A. In particular, when step 3B is performed, the first separation step is a step of heating the pressure-sensitive adhesive sheet to an expansion start temperature (t) or more and less than 125 ° C. to separate the pressure-sensitive adhesive layer (X1) from the object to be processed. Is preferable.
By the first separation step, a plurality of semiconductor chips attached on the thermosetting film are obtained. Then, as in the case of the above-mentioned manufacturing method A, the thermosetting film is divided to obtain a semiconductor chip with a thermosetting film.

The second separation step is a step of separating the pressure-sensitive adhesive layer (X2) and the support.
The method for separating the pressure-sensitive adhesive layer (X2) and the support may be appropriately selected according to the type of the pressure-sensitive adhesive layer (X2). For example, when the pressure-sensitive adhesive layer (X2) is a pressure-sensitive adhesive layer whose adhesive strength is reduced by irradiation with energy rays, the pressure-sensitive adhesive layer (X2) is irradiated with energy rays to reduce the pressure-sensitive adhesive strength. It should be separated.
The manufacturing method B may not include the second separation step.

<Manufacturing method of semiconductor device of another aspect>
The method for manufacturing a semiconductor device of the present invention is not limited to the method for manufacturing the semiconductor device according to the first and second aspects described above, and the manufacturing method for the semiconductor device according to the first aspect and the second aspect is different from the first aspect and the second aspect. It may be a method.

As another example of the method for manufacturing a semiconductor device of another aspect, there is a method of separating a processed object attached to another sheet from the other sheet by using the adhesive sheet of one aspect of the present invention. Can be mentioned.
For example, a plurality of semiconductor chips whose intervals are widened on the expand tape are attached to the adhesive surface of the expand tape, but the work of picking up these chips one by one is complicated. According to the method for manufacturing a semiconductor device according to an aspect of the present invention, the pressure-sensitive adhesive layer (X1) of the pressure-sensitive adhesive sheet according to the present invention is attached to the exposed surface of a plurality of semiconductor chips attached on the expanded tape, and then the adhesive layer (X1) of the adhesive sheet according to the present invention is attached. By peeling the expand tape from the plurality of semiconductor chips, the plurality of semiconductor chips can be separated from the expand tape at once.
Through the above steps, a plurality of semiconductor chips attached on the pressure-sensitive adhesive sheet according to one aspect of the present invention can be obtained. The plurality of semiconductor chips can be easily separated by subsequently heating the pressure-sensitive adhesive layer (X1) to a temperature equal to or higher than the expansion start temperature (t) of the heat-expandable particles.
The plurality of separated semiconductor chips may be transferred to another pressure-sensitive adhesive sheet, or may be subjected to a rearrangement step of aligning the plurality of semiconductor chips after being separated once.

The present invention will be specifically described with reference to the following examples, but the present invention is not limited to the following examples. The physical property values in each example are values measured by the following methods.

[Mass average molecular weight (Mw)]
It was measured under the following conditions using a gel permeation chromatograph device (manufactured by Tosoh Corporation, product name "HLC-8020"), and the value measured in terms of standard polystyrene was used.
(Measurement condition)
-Column: "TSK guard volume HXL-L""TSK gel G2500HXL""TSK gel G2000HXL""TSK gel G1000HXL" (all manufactured by Tosoh Corporation) are connected in sequence.-Column temperature: 40 ° C.
・ Developing solvent: Tetrahydrofuran ・ Flow rate: 1.0 mL / min

[Thickness of each layer]
Measurement was performed at 23 ° C. using a constant pressure thickness measuring instrument manufactured by Teclock Co., Ltd. (model number: "PG-02J", standard: JIS K6783, Z1702, Z1709 compliant).

[Average particle size of thermally expandable particles (D ₅₀ ), 90% particle size (D ₉₀ )]
The particle distribution of the heat-expandable particles before expansion at 23 ° C. was measured using a laser diffraction type particle size distribution measuring device (for example, manufactured by Malvern, product name “Mastersizer 3000”).
Then, the particle diameters corresponding to the cumulative volume frequencies of 50% and 90% calculated from the smaller particle diameter of the particle distribution are set to "average particle diameter of thermally expandable particles (D ₅₀ )" and "thermally expandable particles", respectively. 90% particle size (D ₉₀ ) ”.

[Measurement method of arithmetic mean swell (Wa)]
The arithmetic mean swell (Wa) was measured using a scanning white interference microscope (manufactured by Hitachi High-Tech Co., Ltd., product name "VS-1550") in accordance with JIS B0601: 2013. Observe the surface (SX1) of the adhesive layer ( _X1 ) under the conditions of measurement mode PSI and 10 times the objective lens, and make a total of 100 images in a grid pattern of 10 vertical × 10 horizontal (overlap with adjacent images). An image with a lap rate of 10%) was acquired. Next, compositing is performed by combining each image with an adjacent image, and the height data of the obtained composite image is processed by a Gaussian filter having a cutoff value of 100 μm and an amplitude transmission rate of 50%, and the arithmetic mean swell (arithmetic mean swell) ( The value of Wa) was obtained.

In the following examples, the details of the materials used to form each layer are as follows.

<Adhesive resin>
Acrylic copolymer (A1): n-butyl acrylate (BA) / methyl methacrylate (MMA) / acrylic acid (AA) / 2-hydroxyethyl acrylate (HEA) = 86/8/1/5 (mass ratio) A solution containing an acrylic copolymer of Mw 600,000 having a structural unit derived from a raw material monomer composed of, diluting solvent: ethyl acetate, solid content concentration: 40% by mass.

<Crosslinking agent>
-Isocyanate-based cross-linking agent (i): manufactured by Tosoh Corporation, product name "Coronate L", solution containing trimethylolpropane-modified tolylene diisocyanate, solid content concentration: 75% by mass

<Photopolymerization initiator>
-Photopolymerization initiator (i): 1-hydroxycyclohexylphenyl ketone

<Additives>
・ Phthalocyanine pigment

<Thermal expandable particles>
-Thermal expandable particles: manufactured by Nouryon, product name "Expancel (registered trademark) 031-40" (DU type), expansion start temperature (t) = 88 ° C., average particle diameter (D ₅₀ ) = 12.6 μm, 90. % Particle diameter (D ₉₀ ) = 26.2 μm

<Release material>
-Heavy release film: manufactured by Lintec Corporation, product name "SP-PET382150", polyethylene terephthalate (PET) film with a release agent layer formed from a silicone-based release agent on one side, thickness: 38 μm.

Examples 1 to 10, Comparative Examples 1 to 10: Formation of adhesive sheet (1) Formation of adhesive layer (X1) An isocyanate-based cross-linking agent (i) is added to 100 parts by mass of the solid content of the acrylic copolymer (A1). A pressure-sensitive adhesive composition (x-1) having a solid content concentration (active ingredient concentration) of 25% by mass was prepared by blending 1.38 parts by mass (solid content ratio), diluting with toluene, and stirring uniformly.
Then, the prepared pressure-sensitive adhesive composition (x-1) is applied onto the peeling surface of the heavy-release film to form a coating film, and the coating film is dried at 100 ° C. for 60 seconds to adhere to a thickness of 5 μm. An agent layer (X1) was formed.

(2) Preparation of Solventless Resin Composition (y-1a) 2-Hydroxyethyl acrylate is reacted with the terminal isocyanate urethane prepolymer obtained by reacting the ester type diol with isophorone diisocyanate (IPDI). A linear urethane prepolymer having ethylenically unsaturated groups at both ends, which is an oligomer having a mass average molecular weight (Mw) of 5,000, was obtained.
Then, 40 parts by mass (solid content ratio) of the urethane prepolymer synthesized above, 40 parts by mass (solid content ratio) of isobornyl acrylate (IBXA) and phenylhydroxypropyl acrylate (HPPA) as energy ray-polymerizable monomers. 20 parts by mass (solid content ratio) is blended, and 2.0 parts by mass (solid content ratio) of the photopolymerization initiator (i) is further added to the total amount (100 parts by mass) of the urethane prepolymer and the energy ray-polymerizable monomer. , 0.2 parts by mass (solid content ratio) of the phthalocyanine-based polymer and 20 parts by mass of cyclohexyl acrylate (CHA) were blended as additives to prepare an energy ray-curable composition.
Then, the content of the heat-expandable particles in the energy ray-curable composition is shown in Table 1 with respect to the total mass (100% by mass) of the obtained heat-expandable base material layer (Y1). It was blended so as to become. Then, any of the dispersion treatments shown in Table 1 was performed to prepare a solvent-free resin composition (y-1a) containing no solvent. The details of the distributed processing shown in Table 1 are as follows.
(Distributed processing)
Stirring treatment: Using a cylindrical stirring rod (manufactured by Engineering Test Service Co., Ltd., product name “PE05”, 30 mmΦ × 300 mm), stirring was performed at 200 rpm for 5 minutes.
Filtration treatment: Filtration was performed using a Tetron mesh (# 200).
High-speed stirring process: Using a stirring device (manufactured by Primix Corporation, product name "Lab Solution") equipped with a stirring blade (manufactured by Primix Corporation, product name "Homomixer MARKII"), the condition is 10,000 rpm. The mixture was stirred for 20 minutes while cooling with water at 10 ° C.

(3) Formation of a base material laminate in which a heat-expandable base material layer (Y1) and a non-heat-expandable base material layer (Y2) are laminated As a non-heat-expandable base material layer (Y2), a PET film (Toyobo Co., Ltd.) A company-made product name "Cosmo Shine A4300", thickness: 50 μm) was prepared.
Next, the solvent-free resin composition (y-1a) is applied to one side of the PET film so that the thickness of the heat-expandable base material layer (Y1) to be formed becomes the thickness shown in Table 1. To form a coating film.
Then, using an ultraviolet irradiation device (manufactured by Eye Graphics Co., Ltd., product name "ECS-401GX") and a high-pressure mercury lamp (manufactured by Eye Graphics Co., Ltd., product name "H04-L41"), an illuminance of 160 mW / cm ² The coating film is cured by irradiating ultraviolet rays under the condition of a light amount of 500 mJ / cm ² , and the heat-expandable base material layer (Y1) having the thickness shown in Table 1 is a non-heat-expandable base material layer (Y2). A substrate laminate formed on the PET film was obtained. The above illuminance and amount of light at the time of ultraviolet irradiation are values measured using an illuminance / photometer (manufactured by EIT, product name "UV Power Pack II").

(4) Formation of Adhesive Sheet The adhesive surface of the adhesive layer (X1) formed in (1) above and the surface of the heat-expandable substrate layer (Y1) of the substrate laminate formed in (2) above are formed. I pasted them together. As a result, an adhesive sheet having the following structure was produced.
<Heavy release film> / <Adhesive layer (X1), thickness: 5 μm> / <heat-expandable base material layer (Y1), thickness: thickness shown in Table 1> / <non-heat-expandable base material Layer (Y2), thickness: 50 μm>

FIG. 10 shows a three-dimensional surface shape image of a surface ( _SX1 ) obtained for calculating the arithmetic mean waviness (Wa) of the pressure-sensitive adhesive sheet of Example 1 and FIG. 11; 10 and 11 are both regions of about 16 mm in the x-axis direction and about 12 mm in the y-axis direction, and the scales in the z-axis direction are the same in FIGS. 10 and 11.
From FIGS. 10 and 11, the surface ( _SX1 ) of the adhesive sheet of Comparative Example 9 (FIG. 11) having a large arithmetic mean swell (Wa) is the adhesive of Example 1 (FIG. 10) having a small arithmetic mean swell (Wa). It can be seen that there is a swell larger than the surface of the sheet ( _SX1 ).

[Store elastic modulus E'(23) of the non-thermally expandable substrate layer (Y2) at 23 ° C.]
The test start temperature was used as a test sample using a non-thermally expandable base material layer (Y2) cut into a length of 30 mm and a width of 5 mm using a dynamic viscoelastic modulus measuring device (manufactured by TA Instruments, product name "DMAQ800"). The storage elastic modulus E'at 23 ° C. was measured under the conditions of 0 ° C., a test end temperature of 200 ° C., a heating rate of 3 ° C./min, a frequency of 1 Hz, and an amplitude of 20 μm. As a result, the storage elastic modulus E'(23) of the PET film, which is the non-thermally expandable base material layer (Y2), at 23 ° C. was 2.27 × 10 ⁹ Pa.

[Evaluation of stickability]
The adhesive sheet obtained in each example was cut out to a diameter of 300 mm, the heavy release film was removed, and the adhesive layer ( _X1 ) exposed was allowed to stand on a flat surface so as to face upward. .. A silicon mirror wafer having a diameter of 300 mm is placed on the silicon mirror wafer with a diameter of 300 mm so that the mirror surface is on the side in contact with the surface (S _x 1) of the pressure-sensitive adhesive layer ( _X1 ). Placed while maintaining a state of being substantially parallel to the mirror surface, crimping while reducing the atmospheric pressure to 2 hPa or less using a vacuum laminator (manufactured by Nikko Materials Co., Ltd., product name "V-130"). A test sample was prepared by pressing for 30 seconds under the conditions of a temperature of 60 ° C. and a set value of 0.2 MPa for pressing by the pressurizing mechanism of the apparatus. In the vacuum laminator, the total pressure of 0.2 MPa and the atmospheric pressure of 0.1 MPa by the pressurizing mechanism of the apparatus is 0.3 MPa, which is the crimping pressure.
The test samples obtained in each example were visually observed from the non-thermally expandable base material layer (Y2) side, and the presence of air pools was not confirmed at the adhesive interface between the adhesive layer (X1) and the silicon mirror wafer. Those with a confirmed rating of "A" and those with confirmed presence of air pools were rated with a rating of "F". Since a transparent material is used as the heat-expandable base layer (Y1) and the non-heat-expandable base layer (Y2), it can be visually observed from the non-heat-expandable base layer (Y2) side. It is possible to confirm the state of the adhesive interface between the silicon mirror wafer and the adhesive layer (X1).
The evaluation results of each example are shown in Table 1. Further, examples of external photographs of the test sample corresponding to the evaluation "A" are shown in FIGS. 12 (a) and 12 (b), and examples of the external photographs of the test sample corresponding to the evaluation "F" are shown in FIGS. 13 (a) and 13 (b). ).
In FIGS. 12 and 13, FIG. 12B is an enlarged photograph of the area surrounded by the black dotted line in FIG. In FIG. 12, the existence of an air pool is not confirmed, but in FIG. 13, it can be seen that a plurality of island-shaped air pools (parts having a relatively bright color) are present.

From Table 1, the adhesive sheets of Examples 1 to 10 have an arithmetic mean waviness (Wa) of 0.090 μm or less on the surface (SX1) of the adhesive layer ( _X1 ), and are excellent in stickability. I understand. On the other hand, in the adhesive sheets of Comparative Examples 1 to 10, the arithmetic mean waviness (Wa) of the surface (SX1) of the adhesive layer ( _X1 ) exceeds 0.090 μm, and the adhesiveness may be inferior. I understand.

1a, 1b, 2a,

2b Adhesive sheet

10, 10a, 10b Release material 3 Support 4 Laser light irradiation device 5 Modification area 6 Grinder 7 Thermocurable film 8 Support sheet W Semiconductor wafer W1 Semiconductor wafer circuit surface W2 Semiconductor wafer Back side CP semiconductor chip (X1) Adhesive layer (X1)
(X2) Adhesive layer (X2)
(Y) Base material layer (Y)
(S _x1 ) The surface (S _x1 ) of the adhesive layer (X1)
(S _s ) The surface to which the adhesive sheet of the support is attached (S _s )

Claims

It has a laminated structure including a pressure-sensitive adhesive layer (X1) and a base material layer (Y).
At least one of the pressure-sensitive adhesive layer (X1) and the base material layer (Y) is a heat-expandable layer containing heat-expandable particles.
An adhesive sheet having an arithmetic mean swell (Wa) of 0.090 μm or less on the surface (SX1) of the pressure-sensitive adhesive layer ( X1 ) opposite to the surface facing the base material layer (Y).
The pressure-sensitive adhesive sheet according to claim 1, wherein the heat-expandable layer has a thickness of 30 to 300 μm before thermal expansion.
The invention according to claim 1 or 2, wherein the content of the heat-expandable particles in the heat-expandable layer is 1 to 25% by mass with respect to the total mass (100% by mass) of the heat-expandable layer. Adhesive sheet.
The pressure-sensitive adhesive sheet according to any one of claims 1 to 3, wherein the expansion start temperature (t) of the heat-expandable particles is 50 ° C. or higher and lower than 125 ° C.
The base material layer (Y) is a base material laminate in which a heat-expandable base material layer (Y1) containing heat-expandable particles and a non-heat-expandable base material layer (Y2) are laminated. Claims 1 to 1, which have a laminated structure in which the pressure-sensitive adhesive layer (X1), the heat-expandable base material layer (Y1), and the non-heat-expandable base material layer (Y2) are arranged in this order. The adhesive sheet according to any one of 4.
Further, it has a pressure-sensitive adhesive layer (X2), and has a laminated structure in which the pressure-sensitive adhesive layer (X1), the base material layer (Y), and the pressure-sensitive adhesive layer (X2) are arranged in this order. The adhesive sheet according to any one of claims 1 to 5.
The pressure-sensitive adhesive sheet according to claim 6, wherein the pressure-sensitive adhesive layer (X2) is an energy ray-curable pressure-sensitive adhesive layer that is cured by irradiating with energy rays to reduce the adhesive strength.
A method for manufacturing a semiconductor device, which comprises the following steps 1A, 2A, a first separation step and a second separation step, using the pressure-sensitive adhesive sheet according to claim 6 or 7.
Step 1A: A process of attaching a processing object to the pressure-sensitive adhesive layer (X2) of the pressure-sensitive adhesive sheet, and attaching a support to the pressure-sensitive adhesive layer (X1) of the pressure-sensitive adhesive sheet Step 2A: A process of attaching a support to the pressure-sensitive adhesive layer (X1). On the other hand, a step of performing one or more treatments selected from a grinding treatment and an individualization treatment. First separation step: The pressure-sensitive adhesive sheet is heated to a temperature (t) or higher at which the heat-expandable particles start to expand, and described above. Step of separating the pressure-sensitive adhesive layer (X1) and the support Second separation step: A step of separating the pressure-sensitive adhesive layer (X2) and the object to be processed.
The expansion start temperature (t) of the heat-expandable particles is 50 ° C. or higher and lower than 125 ° C.
After the step 2A, a step 3A of attaching a thermosetting film to the surface of the processed object to be processed, which is opposite to the pressure-sensitive adhesive layer (X2), is included.
The first separation step is a step of heating the pressure-sensitive adhesive sheet to a temperature equal to or higher than the expansion start temperature (t) and lower than 125 ° C. to separate the pressure-sensitive adhesive layer (X1) from the support.
The method for manufacturing a semiconductor device according to claim 8.
In the step of attaching the support to the pressure-sensitive adhesive layer (X1) of the pressure-sensitive adhesive sheet in the step 1A, the surface (SX1) of the pressure-sensitive adhesive layer ( X1 ) and the pressure-sensitive adhesive sheet of the support are attached. This is a step of attaching the surface (S s ) of the support to the surface (SX 1) of the adhesive layer ( X1 ) while maintaining a state in which the surface (S s ) to be formed is substantially parallel to the surface (S s). The method for manufacturing a semiconductor device according to claim 8 or 9.
A method for manufacturing a semiconductor device, which comprises the following steps 1B, 2B, a first separation step and a second separation step, using the pressure-sensitive adhesive sheet according to claim 6 or 7.
Step 1B: A process of attaching a processing object to the pressure-sensitive adhesive layer (X1) of the pressure-sensitive adhesive sheet, and attaching a support to the pressure-sensitive adhesive layer (X2) of the pressure-sensitive adhesive sheet Step 2B: A process of attaching a support to the pressure-sensitive adhesive layer (X2). On the other hand, a step of performing one or more treatments selected from a grinding treatment and an individualization treatment. First separation step: The pressure-sensitive adhesive sheet is heated to a temperature (t) or higher at which the heat-expandable particles start to expand, and described above. Step of separating the pressure-sensitive adhesive layer (X1) and the object to be processed Second separation step: Step of separating the pressure-sensitive adhesive layer (X2) and the support.
The expansion start temperature (t) of the heat-expandable particles is 50 ° C. or higher and lower than 125 ° C.
After the step 2B, a step 3B of attaching a thermosetting film to the surface of the processed object to be processed, which is opposite to the pressure-sensitive adhesive layer (X1), is included.
The first separation step is a step of heating the pressure-sensitive adhesive sheet to a temperature equal to or higher than the expansion start temperature (t) and lower than 125 ° C. to separate the pressure-sensitive adhesive layer (X1) from the object to be processed.
The method for manufacturing a semiconductor device according to claim 11.
In the step of attaching the processing object to the pressure-sensitive adhesive layer (X1) of the pressure-sensitive adhesive sheet in the step 1B, the surface (SX1) of the pressure-sensitive adhesive layer ( X1 ) and the pressure-sensitive adhesive sheet of the processing object are formed. In the step of attaching the surface (S w ) of the object to be processed to the surface (SX1) of the adhesive layer ( X1 ) while maintaining a state in which the surface (S w ) to be attached is substantially parallel. The method for manufacturing a semiconductor device according to claim 11 or 12.