TWI841705B - Adhesive sheet and method for manufacturing semiconductor device - Google Patents

Abstract

The subject of the invention of this case is to provide an adhesive sheet which can be easily peeled off by heating a temporarily fixed object and can suppress the contamination of the surface of the object after peeling, and a method for manufacturing a semiconductor device using the adhesive sheet. The invention of this case is to provide an adhesive sheet having an adhesive layer (X1) arranged in sequence and a thermal expansion The present invention relates to a laminated structure of a heat-expandable substrate layer (Y1) of thermally expandable particles and a non-heat-expandable substrate layer (Y2), and the Young's modulus of the aforementioned adhesive layer (X1) at 23°C is less than 5.0 MPa, and the Young's modulus of the aforementioned non-heat-expandable substrate layer (Y2) at 23°C is higher than the Young's modulus of the aforementioned adhesive layer (X1) at 23°C.

Description

Adhesive sheet and method for manufacturing 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 to semi-permanently fix components, but are also sometimes used as temporary fixing sheets to temporarily fix components (hereinafter sometimes referred to as "attachment") to be processed or inspected when processing or inspecting building materials, interior materials, and electronic parts. For example, in the manufacturing process of semiconductor devices, temporary fixing sheets are used when processing semiconductor wafers.

In the manufacturing process of semiconductor devices, semiconductor wafers are processed into semiconductor chips through a grinding step to reduce the thickness by grinding, a slicing step to separate and separate the semiconductor wafers, etc. At this time, the semiconductor wafer is subjected to specific processing in a state of being temporarily fixed on a temporary fixing sheet. After the semiconductor chip obtained by the specific processing is separated from the temporary fixing sheet, it is mounted on the substrate after appropriately performing an expansion step to expand the intervals between semiconductor chips, a step of rearranging a plurality of semiconductor chips with expanded intervals, a step of reversing the inside and outside of the semiconductor chip, etc. as necessary. In each of the above steps, temporary fixing sheets suitable for various purposes can be used.

Patent document 1 discloses a heat-peelable adhesive sheet for temporary fixation when electronic components are cut, wherein a heat-expandable adhesive layer containing heat-expandable microspheres is provided on at least one side of a substrate. The same document states that when the electronic components are cut, the heat-peelable adhesive sheet can ensure a contact area of a certain size with the adherend to prevent poor adhesion such as chip detachment, and on the other hand, after use, the heat-expandable microspheres are expanded by heating, and the contact area with the adherend is reduced, so that the sheet can be easily peeled off. [Prior art] [Patent document]

[Patent Document 1] Japanese Patent No. 3594853

[Problems to be solved by the present invention]

However, as in the adhesive sheet disclosed in Patent Document 1, when the adhesive layer contains heat-expandable particles, residues from the heat-expandable particles may adhere to the surface of the adherend, or a portion of the adhesive layer may adhere to the surface of the adherend due to deformation or deterioration of the adhesive layer caused by the expansion of the heat-expandable particles (so-called "paste residue"), so that the surface of the adherend may be contaminated after being peeled off by heating.

In view of the above problems, the present invention aims to provide an adhesive sheet and a method for manufacturing a semiconductor device using the adhesive sheet, wherein the adhesive sheet can be easily peeled off by heating a temporarily fixed object, and can suppress contamination of the surface of the object after peeling. [Means for solving the problem]

The inventors of the present invention have found that the above-mentioned problems can be solved and the present invention can be further completed by making the adhesive sheet satisfy (1) a layered structure in which an adhesive layer, a heat-expandable substrate layer containing heat-expandable particles, and a non-heat-expandable substrate layer are arranged in sequence, (2) the Young’s modulus of the adhesive layer is adjusted to a specific range, and (3) the Young’s modulus of the adhesive layer and the Young’s modulus of the non-heat-expandable substrate layer are adjusted to a specific relationship.

That is, the present invention relates to the following [1] to [15]. [1] An adhesive sheet having a laminated structure in which an adhesive layer (X1), a heat-expandable substrate layer (Y1) containing heat-expandable particles, and a non-heat-expandable substrate layer (Y2) are arranged in sequence, the Young's modulus of the adhesive layer (X1) at 23°C being 5.0 MPa or less, and the Young's modulus of the non-heat-expandable substrate layer (Y2) at 23°C being higher than the Young's modulus of the adhesive layer (X1) at 23°C. [2] An adhesive sheet as described in [1] above, wherein the thickness of the adhesive layer (X1) at 23°C is 3 to 10 μm. [3] The adhesive sheet as described in [1] or [2] above, wherein the product of the Young's modulus (unit: MPa) of the adhesive layer (X1) at 23°C and the thickness (unit: μm) of the adhesive layer (X1) at 23°C is 0.3 to 50. [4] The adhesive sheet as described in any one of [1] to [3] above, wherein the adhesive layer (X1) is a layer formed by an adhesive composition (x-1) comprising an acrylic resin and an isocyanate crosslinking agent. [5] The adhesive sheet as described in [4] above, wherein the isocyanate crosslinking agent comprises an isocyanurate-type modified substance having an isocyanurate ring. [6] The adhesive sheet as described in any one of [1] to [5] above, wherein the Young's modulus of the non-thermally expandable substrate layer (Y2) at 23°C is 700 MPa or more. [7] The adhesive sheet as described in any one of [1] to [6] above, wherein the non-thermally expandable substrate layer (Y2) is a polyethylene terephthalate film. [8] The adhesive sheet as described in any one of [1] to [7] above, wherein the non-thermally expandable substrate layer (Y2) further has an adhesive layer (X2) on the surface opposite to the laminated surface of the thermally expandable substrate layer (Y1). [9] The adhesive sheet as described in any one of [1] to [7] above, wherein the expansion start temperature (t) of the thermally expandable particles is 50°C or higher and less than 125°C. [10] The adhesive sheet as described in [8] above, wherein the expansion start temperature (t) of the thermally expandable particles is 50°C or higher and less than 125°C. [11] The adhesive sheet as described in [10] above, wherein the adhesive layer (X2) is an adhesive layer whose adhesive force is reduced by curing by irradiation with energy rays. [12] A method for manufacturing a semiconductor device, comprising the steps of attaching an adhesive sheet as described in any one of [1] to [11] to an object to be inspected, subjecting the object to be inspected to at least one of processing and inspection, and then heating the adhesive sheet to a temperature above the expansion start temperature (t) of the thermally expandable particles in the adhesive sheet. [13] A method for manufacturing a semiconductor device, which uses an adhesive sheet as described above [10] or [11], and includes the following steps 1A to 3A, the following first separation step, and the following second separation step, Step 1A: attaching a processing object to the adhesive layer (X2) of the aforementioned adhesive sheet, and attaching a support to the adhesive layer (X1) of the aforementioned adhesive sheet Step 2A: subjecting the aforementioned processing object to one of a grinding process and a piece-by-piece process The above treatment steps Step 3A: A step of attaching a thermosetting film having thermosetting properties to the surface of the object to be processed which is opposite to the adhesive layer (X2) First separation step: A step of heating the adhesive sheet to a temperature above the expansion start temperature (t) but below 125°C, and separating the adhesive layer (X1) from the support Second separation step: A step of separating the adhesive layer (X2) from the object to be processed. [14] A method for manufacturing a semiconductor device, which uses an adhesive sheet as described above [10] or [11], and includes the following steps 1B to 3B, the following first separation step, and the following second separation step, Step 1B: attaching a processing object to the adhesive layer (X1) of the aforementioned adhesive sheet, and attaching a support to the adhesive layer (X2) of the aforementioned adhesive sheet Step 2B: subjecting the aforementioned processing object to one of a grinding process and a piece-by-piece process The above treatment steps Step 3B: A step of attaching a thermosetting film having thermosetting properties to the surface of the object to be processed which is opposite to the adhesive layer (X1) The first separation step: A step of heating the adhesive sheet to a temperature above the expansion start temperature (t) and below 125°C, and separating the adhesive layer (X1) from the object to be processed The second separation step: A step of separating the adhesive layer (X2) from the support. [15] A method for manufacturing a semiconductor device as described in [13] or [14] above, wherein the adhesive sheet as described in [11] above is used, and the second separation step includes a step of curing the adhesive layer (X2) by irradiating the adhesive layer (X2) with energy rays. [Effect of the invention]

The adhesive sheet of the present invention can be easily peeled off by heating the temporarily fixed adherend, and can suppress contamination of the adherend surface after peeling.

In this specification, "active ingredient" means the component contained in the target composition, excluding the diluent solvent. In addition, in this specification, the mass average molecular weight (Mw) is a value converted to standard polystyrene measured by gel permeation chromatography (GPC), and specifically, a value measured based on the method described in the embodiment.

In this specification, for example, "(meth)acrylic acid" means both "acrylic acid" and "methacrylic acid", and other similar terms are the same. In addition, in this specification, regarding the preferred numerical range (such as the range of content, etc.), the lower limit value and the upper limit value described in stages can be combined independently. For example, in the description of "preferably 10~90, more preferably 30~60", "preferably the lower limit value (10)" and "more preferably the upper limit value (60)" can be combined to set it to "10~60".

In this specification, "energy beam" means electromagnetic waves or charged particle beams with energy quanta, and examples thereof include ultraviolet rays, radiation, electron beams, etc. Ultraviolet rays can be irradiated by using, for example, electrodeless bulbs, high-pressure mercury bulbs, metal halide bulbs, UV-LEDs, etc. as ultraviolet ray sources. Electron beams can be irradiated by electron beam accelerators, etc. In this specification, "energy beam polymerization" means the property of polymerization by irradiation with energy beams.

In this specification, whether a "layer" is a "non-thermal expansion layer" or a "thermal expansion layer" is determined as follows. When the layer to be determined contains thermal expansion particles, the layer is heated for 3 minutes at the expansion start temperature (t) of the thermal expansion particles. When the volume change rate calculated by the following formula is less than 5%, the layer is determined to be a "non-thermal expansion layer", and when it is 5% or more, the layer is determined to be a "thermal expansion layer". ･Volume change rate (%) = {(volume of the previous layer after heat treatment - volume of the previous layer before heat treatment) / volume of the previous layer before heat treatment} × 100 In addition, the layer that does not contain thermal expansion particles is a "non-thermal expansion layer".

In this specification, the "surface" of a semiconductor wafer and a semiconductor chip refers to the side on which a circuit is formed (hereinafter sometimes referred to as the "circuit surface"), and the "inner surface" of a semiconductor wafer and a semiconductor chip refers to the side on which no circuit is formed.

[Adhesive sheet] The adhesive sheet of the present invention has a laminated structure in which an adhesive layer (X1), a heat-expandable base layer (Y1) containing heat-expandable particles, and a non-heat-expandable base layer (Y2) are sequentially arranged, and the Young's modulus of the adhesive layer (X1) at 23°C is 5.0 MPa or less, and the Young's modulus of the non-heat-expandable base layer (Y2) at 23°C is higher than the Young's modulus of the adhesive layer (X1) at 23°C.

The adhesive sheet of the present invention is a sheet that heats the heat-expandable particles contained in the heat-expandable base layer (Y1) to a temperature above the expansion start temperature (t) to expand the particles. The adhesive surface of the adhesive layer (X1) is well formed with unevenness, and the contact area between the adhered object and the adhesive surface of the adhesive layer (X1) is greatly reduced. In this way, the adhered object can be easily peeled off from the adhesive sheet. In addition, since the heat-expandable particles are contained in the heat-expandable base layer (Y1), contamination of the adhered object surface caused by the heat-expandable particles can be suppressed. Here, in the adhesive sheet of the present invention, the Young's modulus of the adhesive layer (X1) at 23°C is adjusted to be less than 5.0 MPa. Therefore, the surface irregularities on the adhesive layer (X1) side of the thermally expandable substrate layer (Y1) generated by the expansion of the thermally expandable particles will effectively follow the adhesive layer (X1), and the irregularities are well formed on the adhesive surface of the adhesive layer (X1). On the other hand, when the Young's modulus of the adhesive layer (X1) at 23°C exceeds 5.0 MPa, it is difficult to form unevenness on the adhesive surface of the adhesive layer (X1) because the adhesive layer (X1) cannot fully follow the unevenness on the surface of the adhesive layer (X1) side of the thermally expandable substrate layer (Y1) caused by the expansion of the thermally expandable particles, and the unevenness on the surface of the adhesive layer (X1) side of the thermally expandable substrate layer (Y1) is pressed into the adhesive layer (X1). Furthermore, since the Young's modulus of the non-thermally expandable substrate layer (Y2) at 23°C is higher than the Young's modulus of the adhesive layer (X1) at 23°C, when the thermally expandable particles expand, it is easier to form irregularities on the surface of the thermally expandable substrate layer (Y1) on the adhesive layer (X1) side than on the surface of the thermally expandable substrate layer (Y1) on the non-expandable substrate layer (Y2) side. Therefore, irregularities can be well formed on the adhesive surface of the adhesive layer (X1). When the Young's modulus of the non-thermal expansion base layer (Y2) at 23°C is the same as or lower than the Young's modulus of the adhesive layer (X1) at 23°C, it is difficult for unevenness to form on the surface of the thermal expansion base layer (Y1) on the adhesive layer (X1) side, and it is difficult for unevenness to form on the adhesive surface of the adhesive layer (X1).

Here, the adhesive sheet of the present invention can significantly reduce the adhesion between the adhesive sheet and the adherend by heating to a temperature above the expansion start temperature (t) of the thermally expandable particles contained in the thermally expandable substrate layer (Y1). Therefore, when the adhesive sheet of one type of the present invention is peeled off by heating, the adhesive sheet can be peeled off from the adherend without applying a force to pull off the adhesive sheet. Specifically, in a laminated body formed by attaching the adhesive sheet to the adherend, when peeling off by heating, the adhesive sheet can be peeled off by turning the adhesive sheet side downward and causing the adhesive sheet to fall from the adherend by gravity. In addition, in this specification, the state in which the adhesive sheet is peeled off or removed from the adhered body without applying a force to remove the adhesive sheet is called "self-peeling". Moreover, such a property is called "self-peeling property".

In the adhesive sheet of one embodiment of the present invention, the Young's modulus of the adhesive layer (X1) at 23°C is preferably 4.5 MPa or less, more preferably 4.0 MPa or less, more preferably 3.5 MPa or less, more preferably 3.0 MPa or less, and further preferably 2.5 MPa or less, more preferably 2.0 MPa or less, more preferably 1.5 MPa or less, and even more preferably 1.3 MPa or less, from the viewpoint of improving the followability of the adhesive layer (X1) to the deformation of the heat-expandable substrate layer (Y1) and making it easy to form unevenness on the adhesive surface of the adhesive layer (X1) when the heat-expandable particles expand. And, it is usually 0.1 MPa or more. In this specification, the Young's modulus of the adhesive layer (X1) at 23°C is measured by the method described in the examples described later.

[Structure of adhesive sheet] The adhesive sheet of the present invention may have a laminated structure in which an adhesive layer (X1), a heat-expandable base layer (Y1) containing heat-expandable particles, and a non-heat-expandable base layer (Y2) are arranged in sequence. The adhesive sheet of one type of the present invention may only have an adhesive layer (X1), a heat-expandable base layer (Y1) and a non-heat-expandable base layer (Y2), and may also have other layers as necessary. For example, when the adhesive sheet of one type of the present invention is used in one or more of the processing and inspection of the adherend, from the perspective of improving the processability and inspectionability of the adherend, it is preferable to further have an adhesive layer (X2) on the non-expandable base layer (Y2) on the side opposite to the laminated surface of the thermal expansion base layer (Y1). By having this structure, the adherend can be attached to either the adhesive layer (X1) or the adhesive layer (X2), and the support can be attached to the other adhesive layer. By fixing the adherend to the support through the adhesive sheet, when the adherend is subjected to one or more of the processing and inspection, vibration, positional displacement and damage of the adherend when it is fragile can be suppressed, and processing accuracy and processing speed as well as inspection accuracy and inspection speed can be improved. In the following description, unless otherwise specified, "double-sided adhesive sheet" means an adhesive sheet having a laminated structure in which an adhesive layer (X1), a heat-expandable base layer (Y1) containing heat-expandable particles, a non-heat-expandable base layer (Y2), and an adhesive layer (X2) are arranged in sequence.

The adhesive sheet of one embodiment of the present invention may also have a release material on the adhesive surface of the adhesive layer (X1). Furthermore, when the adhesive sheet of one embodiment of the present invention has a double-sided adhesive sheet structure, at least one of the adhesive layer (X1) and the adhesive layer (X2) may also have a release material on the adhesive surface.

Next, the structure of an adhesive sheet of the present invention will be described in more detail with reference to the drawings.

As an adhesive sheet of one type of the present invention, there is an adhesive sheet 1a having a layered structure in which an adhesive layer (X1), a heat-expandable base layer (Y1) containing heat-expandable particles, and a non-heat-expandable base layer (Y2) are arranged in sequence as shown in FIG1(a). In addition, an adhesive sheet of one type of the present invention may also be an adhesive sheet 1b as shown in FIG1(b), further having a release material 10 on the adhesive surface of the adhesive layer (X1).

As another type of adhesive sheet of the present invention, there is a sheet having the structure of the above-mentioned double-sided adhesive sheet. As an adhesive sheet having such a structure, there is an adhesive sheet 2a having a layered structure in which an adhesive layer (X1), a heat-expandable base layer (Y1) containing heat-expandable particles, a non-heat-expandable base layer (Y2), and an adhesive layer (X2) are arranged in sequence as shown in FIG2(a). In addition, a double-sided adhesive sheet 2b may be further provided with a release material 10a on the adhesive surface of the adhesive layer (X1), and a release material 10b on the adhesive surface of the adhesive layer (X2), as shown in FIG2(b).

Moreover, in the double-sided adhesive sheet 2b shown in FIG2(b), when the peeling force when peeling the peeling material 10a from the adhesive layer (X1) is the same as the peeling force when peeling the peeling material 10b from the adhesive layer (X2), if the two peeling materials are pulled outward to peel them, the adhesive layer may be cut off along with the two peeling materials, resulting in the phenomenon of being pulled off. From the viewpoint of suppressing such a phenomenon, it is better to design the two peeling materials 10a and 10b to have different peeling forces from the adhesive layers attached to each other.

As another type of adhesive sheet of the present invention, a double-sided adhesive sheet 2a as shown in FIG. 2( a) has a double-sided adhesive sheet having a structure in which a peeling material having been subjected to a peeling treatment is layered on both sides on the adhesive surface of one of the adhesive layers (X1) and (X2) and is rolled into a roll.

The adhesive sheet of one type of the present invention may or may not have other layers between at least one of the adhesive layer (X1) and the thermal expansion substrate layer (Y1) and between the thermal expansion substrate layer (Y1) and the non-thermal expansion substrate layer (Y2). Moreover, when the adhesive sheet of one type of the present invention is the above-mentioned double-sided adhesive sheet, in addition to the above, it may or may not have other layers between at least one of the adhesive layer (X1) and the thermal expansion substrate layer (Y1), between the thermal expansion substrate layer (Y1) and the non-thermal expansion substrate layer (Y2), and between the non-thermal expansion substrate layer (Y2) and the adhesive layer (X2). However, in the adhesive sheet of one type of the present invention, from the viewpoint that the deformation of the heat-expandable base layer (Y1) caused by the expansion of the heat-expandable particles is well transferred to the adhesive layer (X1), it is better to directly laminate the adhesive layer (X1) and the heat-expandable base layer (Y1).

Next, regarding the adhesive sheet of the present invention, after explaining the heat-expandable particles necessary for forming projections and depressions on the adhesive surface of the adhesive layer (X1) by heating, the adhesive layer (X1), the heat-expandable substrate layer (Y1), the non-heat-expandable substrate layer (Y2) and the adhesive layer (X2) are explained.

<Thermal expansion particles> Thermal expansion particles used in the adhesive sheet of the present invention can be particles that expand when heated, and the expansion start temperature (t) can be appropriately selected according to the purpose of the adhesive sheet.

Furthermore, in recent years, when a semiconductor chip is mounted on a substrate, a step is adopted in which the semiconductor chip is attached to the substrate via a film-like adhesive having thermosetting properties, called a die-bonding material film (hereinafter sometimes referred to as "DAF"). DAF is attached to one side of a semiconductor wafer or a plurality of individual semiconductor chips, and is separated into the same shape as the semiconductor chip at the same time as the individualization of the semiconductor wafer or after being attached to the semiconductor chip. The individualized semiconductor chip with DAF is attached to the substrate (die-bonding material) from the DAF side, and then the semiconductor chip and the substrate are fixed by thermosetting the DAF. At this time, the DAF must maintain the property of being bonded by pressure or heat until it is attached to the substrate. However, when a semiconductor chip with DAF is used as the adherend of a heat-peelable adhesive sheet, the DAF hardens before the solid-crystal material by heating the heat-expandable particles to expand, and the adhesion of DAF to the substrate is sometimes reduced. The reduction in the adhesion of DAF will lead to a reduction in the bonding reliability between the semiconductor chip and the substrate, so it is expected to be suppressed. That is, during heat peeling, it is expected that the thermal change of the adherend is suppressed. From a related point of view, in a type of adhesive sheet of the present invention, the expansion start temperature (t) of the heat-expandable particles is preferably less than 125°C, more preferably below 120°C, more preferably below 115°C, more preferably below 110°C, and further preferably below 105°C.

Furthermore, if a heat-expandable particle having a lower expansion start temperature is used as a heat-peelable adhesive sheet, the heat-expandable particle may expand due to the temperature rise when the adhered object is ground. Since such unintentional expansion of the heat-expandable particle may cause unintentional separation or positional displacement of the adhered object, it is desirable to suppress it. From a related point of view, in a type of adhesive sheet of the present invention, the expansion start temperature (t) of the heat-expandable particle is preferably 50°C or higher, more preferably 55°C or higher, more preferably 60°C or higher, and more preferably 70°C or higher. In this specification, the expansion start temperature (t) of the heat-expandable particle means a value measured by the following method.

(Method for measuring the expansion start temperature (t) of thermal expansion particles) Add 0.5 mg of the thermal expansion particles to be measured to an aluminum cup with a diameter of 6.0 mm (inner diameter of 5.65 mm) and a depth of 4.8 mm, and prepare a sample with an aluminum cover (diameter of 5.6 mm and thickness of 0.1 mm) placed on top. Use a dynamic viscoelasticity measuring device to apply a force of 0.01 N to the sample from the top of the aluminum cover with a pressurizer, and measure the height of the sample. In addition, heat the sample from 20°C to 300°C at a heating rate of 10°C/min while applying a force of 0.01 N with the pressurizer, and measure the displacement in the vertical direction of the pressurizer. The displacement start temperature in the positive direction is set as the expansion start temperature (t).

As heat-expandable particles, a microencapsulated foaming agent composed of an outer shell composed of a thermoplastic resin and an inner component encapsulated in the outer shell and vaporized after heating to a specific temperature is preferred. Examples of the thermoplastic resin constituting the outer shell of the microencapsulated foaming agent include vinylidene chloride-acrylonitrile copolymer, polyvinyl alcohol, polyvinyl butyral, polymethacrylate, polyacrylonitrile, polyvinylidene chloride, polysulfone, etc.

As the inner component of the component encapsulated in the outer shell of the microcapsule foaming agent, there are low-boiling liquids such as propane, propylene, butene, n-butane, isobutane, isopentane, neopentane, n-pentane, n-hexane, isohexane, n-heptane, n-octane, cyclopropane, cyclobutane, petroleum ether, etc. Among them, from the viewpoint of suppressing the thermal change of the adhered body during heat peeling and suppressing the unintentional expansion of the heat-expandable particles caused by the temperature rise when grinding the adhered body, when the expansion start temperature (t) of the heat-expandable particles is set to 50°C or more and less than 125°C, the inner component is preferably propane, isobutane, n-pentane and cyclopropane. These inner components may be used alone or in combination of two or more. The expansion start temperature (t) of the thermally expandable particles can be adjusted by appropriately selecting the type of inner components.

The average particle size of the heat-expandable particles used in one embodiment of the present invention before expansion at 23°C is preferably 3-100 μm, more preferably 4-70 μm, more preferably 6-60 μm, and even more preferably 10-50 μm. The average particle size of the heat-expandable particles before expansion refers to the volume median particle size (D ₅₀ ), and is equivalent to the particle size with a cumulative volume frequency of 50% calculated from the smaller particle size of the heat-expandable particles before expansion in the particle distribution of the heat-expandable particles before expansion measured using a laser diffraction particle size distribution measuring device (e.g., Mastersizer 3000 manufactured by Malvern).

The 90% particle size (D ₉₀ ) of the heat-expandable particles before expansion at 23° C. used in one embodiment of the present invention is preferably 10 to 150 μm, more preferably 15 to 100 μm, more preferably 20 to 90 μm, and even more preferably 25 to 80 μm. The 90% particle size (D ₉₀ ) of the heat-expandable particles before expansion refers to the particle size at which the cumulative volume frequency is 90% calculated from the smaller particle size of the heat-expandable particles before expansion in the particle distribution of the heat-expandable particles before expansion measured using a laser diffraction particle size distribution measuring device (e.g., Mastersizer 3000 manufactured by Malvern).

The maximum volume expansion rate when heated to a temperature above the expansion start temperature (t) of the heat-expandable particles used in one embodiment of the present invention is preferably 1.5 to 200 times, more preferably 2 to 150 times, more preferably 2.5 to 120 times, and even more preferably 3 to 100 times.

<Adhesive layer (X1)> The Young's modulus of the adhesive layer (X1) of the adhesive sheet of the present invention at 23°C is 5.0 MPa or less. Furthermore, the Young's modulus of the adhesive layer (X1) of the adhesive sheet of the present invention at 23°C is lower than the Young's modulus of the non-thermally expansive base layer (Y2) at 23°C.

The adhesive layer (X1) may be a thermal expansion layer or a non-thermal expansion layer, but is preferably a non-thermal expansion layer. When the adhesive layer (X1) is a non-thermal expansion layer, the volume change rate (%) of the adhesive layer (X1) calculated by the above formula is less than 5%, preferably less than 2%, more preferably less than 1%, more preferably less than 0.1%, and even more preferably less than 0.01%. The adhesive layer (X1) preferably does not contain thermal expansion particles, but may contain thermal expansion particles within the scope of not violating the purpose of the present invention. When the adhesive layer (X1) contains thermally expandable particles, the content thereof is preferably as small as possible, and is preferably less than 3 mass%, more preferably less than 1 mass%, more preferably less than 0.1 mass%, more preferably less than 0.01 mass%, and even more preferably less than 0.001 mass%, relative to the total mass of the adhesive layer (X1) (100 mass%).

The adhesive layer (X1) of the adhesive sheet of the present invention can be formed by an adhesive composition (x-1) containing an adhesive resin. The following describes each component contained in the adhesive composition (x-1).

(Adhesive resin) As the adhesive resin, there is cited a polymer having adhesiveness alone and a mass average molecular weight (Mw) of 10,000 or more. From the viewpoint of improving the adhesive force of the adhesive layer (X1), the mass average molecular weight (Mw) of the adhesive resin is preferably 10,000 to 2,000,000, more preferably 20,000 to 1,500,000, and even more preferably 30,000 to 1,000,000.

Specific examples of adhesive resins include rubber resins such as acrylic resins, urethane resins, and polyisobutylene resins, polyester resins, olefin resins, silicone resins, and polyvinyl ether resins. These adhesive resins may be used alone or in combination of two or more. Furthermore, when these adhesive resins are copolymers having two or more constituent units, the form of the copolymer is not particularly limited, and may be any of a block copolymer, a random copolymer, and a graft copolymer.

The adhesive resin may also be an energy-ray-curing adhesive resin that has a polymerizable functional group introduced into the side chain. As the polymerizable functional group, there are (meth)acrylic, vinyl, acryl, etc. having a carbon-carbon double bond. And, as the energy ray, ultraviolet rays are preferred because they are easy to handle among the above.

Here, in one embodiment of the present invention, from the viewpoint of making the adhesive layer (X1) exhibit excellent adhesion and adjusting the Young's modulus of the adhesive layer (X1) to the above range, the adhesive resin preferably includes an acrylic resin.

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

(Acrylic resin) In one embodiment of the present invention, examples of acrylic resins that can be used as adhesive resins include polymers containing constituent units derived from alkyl (meth)acrylates having a linear or branched alkyl group, polymers containing constituent units derived from (meth)acrylates having a cyclic structure, and the like.

The mass average molecular weight (Mw) of the acrylic resin is preferably 100,000 to 1.5 million, more preferably 200,000 to 1.3 million, more preferably 350,000 to 1.2 million, and even more preferably 500,000 to 1.1 million.

The acrylic resin used as one embodiment of the present invention is preferably an acrylic copolymer (A1) having a constituent unit (a1) derived from an alkyl (meth)acrylate (a1') (hereinafter sometimes referred to as "monomer (a1')") and a constituent unit (a2) derived from a monomer containing a functional group (a2') (hereinafter sometimes referred to as "monomer (a2')").

The carbon number of the alkyl group possessed by the monomer (a1') is preferably 1 to 24, more preferably 1 to 12, more preferably 2 to 10, and even more preferably 4 to 8, from the viewpoint of making the adhesive layer (X1) exhibit excellent adhesion and adjusting the Young's modulus of the adhesive layer (X1) to the above range. In addition, the alkyl group possessed by the monomer (a1') may be a straight chain alkyl group or a branched chain alkyl group.

Examples of monomers (a1') include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, lauryl (meth)acrylate, tridecyl (meth)acrylate, and stearyl (meth)acrylate. One of these monomers (a1') may be used alone, or two or more may be used in combination. Preferably, butyl (meth)acrylate and 2-ethylhexyl (meth)acrylate are monomers (a1').

The content of the constituent units (a1) is preferably 50-99.9 mass %, more preferably 60-99.0 mass %, more preferably 70-97.0 mass %, and even more preferably 80-95.0 mass % relative to the total constituent units (100 mass %) of the acrylic copolymer (A1).

As the functional group possessed by the monomer (a2'), there are hydroxyl group, carboxyl group, amino group, epoxy group, etc. That is, as the monomer (a2'), there are hydroxyl group-containing monomers, carboxyl group-containing monomers, amino group-containing monomers, epoxy group-containing monomers, etc. These monomers (a2') can be used alone or in combination of two or more. Among these, as the monomer (a2'), hydroxyl group-containing monomers and carboxyl group-containing monomers are preferred, and hydroxyl group-containing monomers are more preferred.

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

Examples of carboxyl group-containing monomers include ethylenically unsaturated monocarboxylic acids such as (meth)acrylic acid and crotonic acid; ethylenically unsaturated dicarboxylic acids such as butenedioic acid, itaconic acid, maleic acid, citric acid and their anhydrides; 2-(acryloyloxy)ethylsuccinic acid; 2-carboxyethyl(meth)acrylate; and the like.

The content of the constituent units (a2) is preferably 0.1-30 mass %, more preferably 0.5-20 mass %, more preferably 1.0-15 mass %, and even more preferably 3.0-10 mass % relative to the total constituent units (100 mass %) of the acrylic copolymer (A1).

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

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; (meth)acrylates having a cyclic structure such as cyclohexyl (meth)acrylate, benzyl (meth)acrylate, isoborneol (meth)acrylate, dicyclopentyl (meth)acrylate, dicyclopentenyl (meth)acrylate, dicyclopentenyloxyethyl (meth)acrylate, and imido (meth)acrylate; styrene, α-methylstyrene, vinyltoluene, vinyl formate, vinyl acetate, acrylonitrile, (meth)acrylamide, (meth)acrylonitrile, (meth)acryloylmorpholine, and N-vinylpyrrolidone.

Furthermore, the acrylic copolymer (A1) can also be an energy-ray-curable acrylic copolymer having a polymerizable functional group introduced into at least one of the main chain and the side chain. The polymerizable functional group and the energy line are as described above. Furthermore, the polymerizable functional group can be introduced by reacting the acrylic copolymer having the above-mentioned constituent units (a1) and (a2) with a polymerizable compound (Xa) having a substituent capable of bonding with the functional group possessed by the constituent unit (a2) of the acrylic copolymer and a polymerizable functional group. Examples of the polymerizable compound (Xa) include (meth)acryloyloxyethyl isocyanate, methyl-isopropenyl-α,α-dimethylbenzyl isocyanate, (meth)acryloyl isocyanate, acryl isocyanate, glycidyl (meth)acrylate, (meth)acrylic acid, and the like.

(Crosslinking agent) In one embodiment of the present invention, when the adhesive composition (x-1) contains an adhesive resin having a functional group, such as the acrylic copolymer (A1) described above, it is preferred that the adhesive composition further contains a crosslinking agent. The crosslinking agent reacts with the adhesive resin having a functional group, uses the functional group as a crosslinking starting point, and crosslinks the adhesive resins with each other.

As crosslinking agents, there are isocyanate crosslinking agents, epoxy crosslinking agents, aziridine crosslinking agents, metal chelate crosslinking agents, etc. These crosslinking agents can be used alone or in combination of two or more. Among these crosslinking agents, isocyanate crosslinking agents are preferred from the perspectives of increasing cohesion and adhesion, and being easy to obtain. Examples of isocyanate crosslinking agents include aromatic polyisocyanates such as toluene diisocyanate, diphenylmethane diisocyanate, and dimethylbenzene diisocyanate; dicyclohexylmethane-4,4'-diisocyanate, dicycloheptane triisocyanate, cyclopentyl diisocyanate, cyclohexyl diisocyanate, methyl cyclohexyl diisocyanate, methylene diisocyanate, and the like. Cyclic polyisocyanates such as cyclohexyl bis(cyclohexyl isocyanate), 3-isocyanate methyl-3,5,5-trimethylcyclohexyl isocyanate and dimethylbenzene diisocyanate; non-cyclic aliphatic polyisocyanates such as hexamethylene diisocyanate, trimethylhexamethylene diisocyanate and lysine diisocyanate; and polyisocyanate compounds such as the like. In addition, as isocyanate-based crosslinking agents, there are trihydroxymethylpropane adduct-type denatured products of the polyisocyanate compounds, diurea-type denatured products reacting with water, and isocyanuric acid ester-type denatured products containing an isocyanuric acid ester ring. Among these, from the viewpoint of suppressing the decrease in the elastic modulus of the adhesive layer (X1) during heating and suppressing the adhesion of residues from the adhesive layer (X1) to the adherend, it is preferred to use an isocyanurate type denatured substance containing an isocyanurate ring, it is more preferred to use an isocyanurate type denatured substance of a non-cyclic aliphatic polyisocyanate, and it is even more preferred to use an isocyanurate type denatured substance of hexamethylene diisocyanate.

The content of the crosslinking agent can be appropriately adjusted according to the number of functional groups of the adhesive resin, preferably 0.01 to 10 parts by mass, more preferably 0.03 to 7 parts by mass, and even more preferably 0.05 to 5 parts by mass relative to 100 parts by mass of the adhesive resin having the functional group. Moreover, by adjusting the content of the crosslinking agent to this range, the Young's modulus of the adhesive layer (X1) can be easily adjusted to the above range.

(Adhesion-imparting agent) In one embodiment of the present invention, the adhesive composition (x-1) may further have an adhesion-imparting agent from the viewpoint of further improving the adhesion. In this specification, "adhesion-imparting agent" means a component that supplementarily improves the adhesion of the adhesive resin, and has a mass average molecular weight (Mw) of less than 10,000, and is distinguished from the above-mentioned adhesive resin. The mass average molecular weight (Mw) of the adhesion-imparting agent is less than 10,000, preferably 400 to 9,000, more preferably 500 to 8,000, and even more preferably 800 to 5,000.

Examples of the tackifier include C5 petroleum resins obtained by copolymerizing C5 distillates such as pentene, isoprene, piperine, and 1,3-pentadiene produced by thermal decomposition of rosin resins, terpene resins, styrene resins, and naphtha, C9 petroleum resins obtained by copolymerizing C9 distillates such as indene and vinyltoluene produced by thermal decomposition of naphtha, and hydrogenated resins thereof.

The softening point of the adhesive agent is preferably 60 to 170°C, more preferably 65 to 160°C, and even more preferably 70 to 150°C. In this specification, the "softening point" of the adhesive agent means the value measured according to JIS K 2531. One adhesive agent may be used alone, or two or more adhesive agents having different softening points, structures, etc. may be used in combination. When two or more adhesive agents are used, it is preferred that the weighted average of the softening points of the multiple adhesive agents falls within the above range.

The content of the adhesion imparting agent relative to the total amount (100 mass %) of the active ingredient in the adhesive composition (x-1) is preferably 0.01-65 mass %, more preferably 0.1-50 mass %, more preferably 1-40 mass %, and even more preferably 2-30 mass %.

(Photopolymerization initiator) In one embodiment of the present invention, when the adhesive composition (x-1) contains an energy-ray-curable adhesive resin as the adhesive resin, it is preferable to further contain a photopolymerization initiator. By using an adhesive composition containing an energy-ray-curable adhesive resin and a photopolymerization initiator, the adhesive layer formed by the adhesive composition can fully proceed with the curing reaction even by irradiation with relatively low energy energy rays, and the adhesive force can be adjusted to a desired range. Moreover, as a photopolymerization initiator used in one form of the present invention, there are, for example, 1-hydroxy-cyclohexyl-phenyl ketone, benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin propyl ether, benzylbenzene sulfide, tetramethylthiuram monosulfide, azobisisobutyronitrile, dibenzyl, diacetyl, 8-chlorophosphathraquinone, etc. These photopolymerization initiators can be used alone or in combination of two or more.

The content of the photopolymerization initiator is preferably 0.01 to 10 parts by mass, more preferably 0.03 to 5 parts by mass, and even more preferably 0.05 to 2 parts by mass, relative to 100 parts by mass of the energy ray-curing adhesive resin.

(Adhesive additives) In one embodiment of the present invention, the adhesive composition (x-1) may contain adhesive additives used in general adhesives in addition to the above-mentioned additives, within the scope that does not impair the effect of the present invention. As such adhesive additives, there are antioxidants, softeners (plasticizers), anti-brown agents, pigments, dyes, delay agents, reaction accelerators (catalysts), ultraviolet absorbers, etc. And these adhesive additives may be used individually or in combination of two or more.

When such adhesive additives are contained, the content of each adhesive additive is independently 0.0001 to 20 parts by mass, more preferably 0.001 to 10 parts by mass, relative to 100 parts by mass of the adhesive resin.

(Thickness of adhesive layer (X1) at 23°C) In one embodiment of the present invention, the thickness of the adhesive layer (X1) at 23°C is preferably 3 to 10 μm, more preferably 3 to 8 μm, and even more preferably 3 to 7 μm, from the viewpoint of exhibiting good adhesion and forming good concavities and convexities on the adhesive surface of the adhesive layer (X1) when the heat-expandable particles expand by heating. By adjusting the thickness of the adhesive layer (X1) to the above range, the adhesive layer (X1) can be easily formed, and concavities and convexities can be easily formed on the adhesive surface of the adhesive layer (X1). The thickness of the adhesive layer (X1) at 23°C is a value measured by the method described in the examples described later.

(Product of Young's modulus of adhesive layer (X1) at 23°C and thickness of adhesive layer (X1) at 23°C) In one embodiment of the present invention, the product of Young's modulus (unit: MPa) of adhesive layer (X1) at 23°C and thickness (unit: μm) of adhesive layer (X1) at 23°C is preferably 0.3-50, more preferably 1.0-30, more preferably 1.5-20, and even more preferably 2.0-10 from the viewpoint of forming good concavities and convexities on the adhesive surface of adhesive layer (X1) when heat-expandable particles expand by heating.

<Thermal expansion base layer (Y1)> The thermal expansion base layer (Y1) is a base layer having thermal expansion particles, and is provided between the adhesive layer (X1) and the non-thermal expansion base layer (Y2). Here, in one form of the present invention, the thermal expansion base layer (Y1) preferably satisfies the following requirement (1). Requirement (1): At the expansion start temperature (t) of the thermal expansion particles, the storage elastic modulus E'(t) of the thermal expansion base layer (Y1) is 1.0×10 ⁷ Pa or less. In this specification, the storage elastic modulus E' of the thermal expansion base layer (Y1) at a specific temperature is a value measured by the method described in the embodiment.

The above requirement (1) is an index of the rigidity of the heat-expandable base layer (Y1) before the heat-expandable particles expand. Before the heat-expandable particles expand, the storage elastic modulus E' of the heat-expandable base layer (Y1) decreases with the temperature rise. However, before or after the expansion start temperature (t) of the heat-expandable particles is reached, the heat-expandable particles start to expand, which can suppress the decrease in the storage elastic modulus E' of the heat-expandable base layer (Y1). On the other hand, in order to easily form unevenness on the adhesive surface of the adhesive layer (X1), it is necessary to easily form unevenness on the surface of the adhesive layer (X1) side of the heat-expandable base layer (Y1) by heating to a temperature above the expansion start temperature (t). The heat-expandable base layer (Y1) that satisfies the above requirement (1) expands the heat-expandable particles at the expansion start temperature (t) and becomes sufficiently large, and it is easy to form unevenness on the surface of the adhesive layer (X1) side of the heat-expandable base layer (Y1). Therefore, it is easy to form unevenness on the adhesive surface of the adhesive layer (X1).

In one embodiment of the present invention, the storage elastic modulus E'(t) specified in the requirement (1) of the thermally expandable base layer (Y1) is preferably 9.0×10 ⁶ Pa or less, more preferably 8.0×10 ⁶ Pa or less, more preferably 6.0×10 ⁶ Pa or less, and even more preferably 4.0×10 ⁶ Pa or less from the above viewpoint. Furthermore, from the viewpoint of suppressing the flow of the expanded heat-expandable particles, improving the maintenance of the uneven shape of the surface formed on the adhesive layer (X1) side of the heat-expandable base layer (Y1), and facilitating the formation of unevenness on the adhesive surface of the adhesive layer (X1), the storage elastic modulus E'(t) specified in the requirement (1) of the heat-expandable base layer (Y1) is preferably 1.0×10 ³ Pa or more, more preferably 1.0×10 ⁴ Pa or more, and even more preferably 1.0×10 ⁵ Pa or more.

From the perspective of the heat expandable substrate layer (Y1) satisfying the above requirement (1), the content of the heat expandable particles in the heat expandable substrate layer (Y1) is preferably 1 to 40 mass %, more preferably 5 to 35 mass %, more preferably 10 to 30 mass %, and even more preferably 15 to 25 mass %, relative to the total mass of the heat expandable substrate layer (Y1) (100 mass %).

Furthermore, in one embodiment of the present invention, the Young's modulus of the heat-expandable substrate layer (Y1) at 23°C is greater than the Young's modulus of the adhesive layer (X1) at 23°C, and preferably greater than the Young's modulus of the non-heat-expandable substrate layer (Y2) at 23°C. Specifically, the Young's modulus of the heat-expandable substrate layer (Y1) at 23°C is preferably 100 MPa or more, more preferably 200 MPa or more, and more preferably 300 MPa or more. Furthermore, it is usually 600 MPa or less, preferably 500 MPa or less.

Furthermore, from the viewpoint of improving the interlayer adhesion between the thermally expansive substrate layer (Y1) and other laminated layers, the surface of the thermally expansive substrate layer (Y1) may be subjected to surface treatment such as oxidation or embossing, easy-to-attach treatment, or bottom layer treatment. As oxidation methods, there are examples of corona discharge treatment, plasma discharge treatment, chromic acid treatment (wet), hot air treatment, ozone and ultraviolet irradiation treatment, etc., and as embossing methods, there are examples of sandblasting, solvent treatment, etc.

The heat-expandable substrate layer (Y1) is preferably formed of a resin composition (y-1) containing a resin and heat-expandable particles. Furthermore, the resin composition (y-1) may also contain a substrate additive as necessary within the scope that does not impair the effect of the present invention. As substrate additives, there are ultraviolet absorbers, light stabilizers, antioxidants, antistatic agents, lubricants, anti-caking agents, coloring agents, etc. Furthermore, these substrate additives may be used individually or in combination of two or more. When such base material additives are contained, the content of each base material additive is independently preferably 0.0001 to 20 parts by mass, and more preferably 0.001 to 10 parts by mass, relative to 100 parts by mass of the resin.

The heat-expandable particles contained in the resin composition (y-1) of the forming material of the heat-expandable base layer (Y1) are as described above. The content of the heat-expandable particles is preferably 1 to 40 mass %, more preferably 5 to 35 mass %, more preferably 10 to 30 mass %, and even more preferably 15 to 25 mass % relative to the total amount (100 mass %) of the effective components of the resin composition (y-1).

The resin contained in the resin composition (y-1) as the forming material of the heat-expandable base layer (Y1) 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, in the process of forming the heat-expandable base layer (Y1) from the resin composition (y-1), the adhesive resin and the polymerizable compound undergo a polymerization reaction, and the resulting resin becomes a non-adhesive resin, and the heat-expandable base layer (Y1) containing the resin becomes non-adhesive.

The mass average molecular weight (Mw) of the aforementioned resin contained in the resin composition (y-1) is preferably 1,000 to 1,000,000, more preferably 1,000 to 700,000, and even more preferably 1,000 to 500,000. In addition, when the resin is a copolymer having two or more constituent units, the morphology of the copolymer is not particularly limited, and may be any of a block copolymer, a random copolymer, and a graft copolymer.

The content of the resin relative to the total amount (100 mass %) of the effective ingredients in the resin composition (y-1) is preferably 50-99 mass %, more preferably 60-95 mass %, more preferably 65-90 mass %, and even more preferably 70-85 mass %.

Furthermore, from the viewpoint of forming a thermally expandable substrate layer (Y1) satisfying the above requirement (1), the resin composition (y-1) preferably contains the above-mentioned resin, preferably at least one selected from acrylic urethane resins and olefin resins. Furthermore, as the acrylic urethane resin, the following resin (U1) is preferably used. ･Acrylic urethane resin (U1) obtained by polymerizing a urethane prepolymer (UP) and a vinyl compound containing (meth)acrylate.

(Acrylic Urethane Resin (U1)) The urethane prepolymer (UP) serving as the main chain of the acrylic urethane resin (U1) is preferably a reaction product of a polyol and a polyisocyanate. Furthermore, the urethane prepolymer (UP) is preferably obtained by subjecting the chain to a chain extension reaction using a chain extender.

Examples of polyols used as raw materials for urethane prepolymers (UP) include alkylene-type polyols, ether-type polyols, ester-type polyols, esteramide-type polyols, ester-ether-type polyols, and carbonate-type polyols. These polyols may be used alone or in combination of two or more. The polyol used in one embodiment of the present invention is preferably a diol, and ester-type diols, alkylene-type diols, and carbonate-type diols are more preferred, and ester-type diols and carbonate-type diols are more preferred.

Examples of the ester type diol include alkane diols selected from 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, neopentyl glycol, 1,6-hexanediol, etc.; alkylene glycols such as ethylene glycol, propylene glycol, diethylene glycol, dipropylene glycol, etc.; and one or more diols selected from phthalic acid, isophthalic acid, terephthalic acid, naphthalene dicarboxylic acid, 4,4-diphenylene glycol. Dicarboxylic acids such as diphenylmethane-4,4'-dicarboxylic acid, succinic acid, adipic acid, azelaic acid, sebacic acid, chloroformic acid, maleic acid, butenedioic acid, itaconic acid, cyclohexane-1,3-dicarboxylic acid, cyclohexane-1,4-dicarboxylic acid, hexahydrophthalic acid, hexahydroisophthalic acid, hexahydroterephthalic acid, methylhexahydrophthalic acid, and polycondensates of one or more of these anhydrides. Specifically, there are polyethylene adipate diol, polybutylene adipate diol, polyhexamethylene adipate diol, polyhexamethylene phthalate diol, polyneopentyl adipate diol, polyethylene propylene adipate diol, polyethylene butylene adipate diol, polybutylene hexamethylene adipate diol, polydivinyl adipate diol, poly(polytetramethylene ether) adipate diol, poly(3-methylpentyl adipate) diol, polyethylene azelaic acid diol, polyethylene sebacic acid diol, polybutylene azelaic acid diol, polybutylene sebacic acid diol and polyneopentyl terephthalate diol.

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

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

Examples of polyisocyanates that are raw materials for urethane prepolymers (UP) include aromatic polyisocyanates, aliphatic polyisocyanates, alicyclic polyisocyanates, and the like. These polyisocyanates may be used alone or in combination of two or more. Furthermore, these polyisocyanates may be trihydroxymethylpropane adduct-type denatured products, diuret-type denatured products that react with water, and isocyanurate-type denatured products containing an isocyanurate ring.

Among these, the polyisocyanate used as one embodiment of the present invention is preferably a diisocyanate, and more preferably at least one selected from 4,4′-diphenylmethane diisocyanate (MDI), 2,4-toluene diisocyanate (2,4-TDI), 2,6-toluene diisocyanate (2,6-TDI), hexamethylene diisocyanate (HMDI) and alicyclic diisocyanates.

Examples of the alicyclic diisocyanate include 3-isocyanate methyl-3,5,5-trimethylcyclohexyl isocyanate (isophorone diisocyanate, IPDI), 1,3-cyclopentane diisocyanate, 1,3-cyclohexane diisocyanate, 1,4-cyclohexane diisocyanate, methyl-2,4-cyclohexane diisocyanate, methyl-2,6-cyclohexane diisocyanate, etc., but isophorone diisocyanate (IPDI) is preferred.

In one embodiment of the present invention, the urethane prepolymer (UP) serving as the main chain of the acrylic urethane resin (U1) is preferably a linear urethane prepolymer which is a reaction product of a diol and a diisocyanate and has ethylenically unsaturated groups at both ends. As a method for introducing ethylenically unsaturated groups at both ends of the linear urethane prepolymer, there is a method of reacting the terminal NCO group of the linear urethane prepolymer formed by reacting a diol and a diisocyanate compound with a hydroxyalkyl (meth)acrylate.

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

The vinyl compound that serves as the side chain of the acrylic urethane resin (U1) contains at least (meth)acrylate. As the (meth)acrylate, at least one selected from alkyl (meth)acrylate and hydroxyalkyl (meth)acrylate is preferred, and a combination of alkyl (meth)acrylate and hydroxyalkyl (meth)acrylate is more preferred.

When alkyl (meth) acrylate and hydroxy alkyl (meth) acrylate are used together, the blending ratio of hydroxy alkyl (meth) acrylate is preferably 0.1 to 100 parts by mass, more 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 relative to 100 parts by mass of alkyl (meth) acrylate.

The carbon number of the alkyl group of the alkyl (meth)acrylate is preferably 1-24, more preferably 1-12, more preferably 1-8, and even more preferably 1-3.

Examples of the hydroxyalkyl (meth)acrylate include the same hydroxyalkyl (meth)acrylate used for introducing ethylenically unsaturated groups into both ends of the above-mentioned linear urethane prepolymer.

Examples of vinyl compounds other than (meth)acrylates include aromatic hydrocarbon vinyl compounds such as styrene, α-methylstyrene, and vinyl toluene; vinyl ethers such as methyl vinyl ether and ethyl vinyl ether; polar group-containing monomers such as vinyl acetate, vinyl propionate, (meth)acrylonitrile, N-vinyl pyrrolidone, (meth)acrylic acid, maleic acid, butenedioic acid, itaconic acid, and methyl (acrylamide); etc. These may be used alone or in combination of two or more.

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

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

The acrylic urethane resin (U1) used in one form of the present invention is obtained by mixing a urethane prepolymer (UP) and a vinyl compound containing (meth)acrylate and polymerizing the two. In the polymerization, a free radical initiator is preferably added to carry out the polymerization.

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

(Olefinic resin) As the resin contained in the resin composition (y-1), a suitable olefinic resin is a polymer having at least a constituent unit derived from an olefin monomer. As the above-mentioned olefin monomer, an α-olefin having 2 to 8 carbon atoms is preferred, and specifically, ethylene, propylene, butene, isobutylene, 1-hexene, etc. are listed. Among them, ethylene and propylene are preferred.

Specific examples of olefin resins include very 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 and less than 942 kg/m ³ ), and polyethylene with a density of 100 kg/m 3 or more. ³ or more), linear low-density polyethylene and other polyethylene resins; polypropylene resin (PP); polybutene resin (PB); ethylene-propylene copolymer; olefin elastomer (TPO); poly (4-methyl-1-pentene) (PMP); ethylene-vinyl acetate copolymer (EVA); ethylene-vinyl alcohol copolymer (EVOH); olefin terpolymers such as ethylene-propylene-(5-ethylidene-2-norbornene); etc.

In one embodiment of the present invention, the olefinic resin may be a modified olefinic resin further modified by one or more modifications selected from acid modification, hydroxy modification, and acrylic modification.

For example, as an acid-modified olefinic resin obtained by subjecting an olefinic resin to acid modification, there is a modified polymer obtained by graft-polymerizing the above-mentioned unmodified olefinic resin with an unsaturated carboxylic acid or its anhydride. As the above-mentioned unsaturated carboxylic acid or its anhydride, there are maleic acid, butenedioic acid, itaconic acid, liconic acid, glutaconic acid, tetra(hydro)phthalic acid, uronic acid, (meth)acrylic acid, maleic anhydride, itaconic anhydride, glutaconic anhydride, liconic anhydride, uronic anhydride, norbornene dicarboxylic anhydride, tetra(hydro)phthalic anhydride, etc. Moreover, the unsaturated carboxylic acid or its anhydride may be used alone or in combination of two or more.

As an acrylic modified olefin resin obtained by subjecting an olefin resin to acrylic modification, there is exemplified a modified polymer obtained by grafting the above-mentioned non-modified olefin resin as a main chain with an alkyl (meth) acrylate as a side chain. The carbon number of the alkyl group possessed by the above-mentioned alkyl (meth) acrylate is preferably 1 to 20, more preferably 1 to 16, and even more preferably 1 to 12. As the above-mentioned alkyl (meth) acrylate, there is exemplified the same compound as the compound that can be selected as the monomer (a1') described later.

As the hydroxy-modified olefinic resin obtained by modifying the olefinic resin with a hydroxyl group, there is exemplified a modified polymer obtained by graft-polymerizing the above-mentioned non-modified olefinic resin of the main chain with a hydroxyl-containing compound. As the above-mentioned hydroxyl-containing compound, there are exemplified the same ones as the above-mentioned hydroxyl-containing compound.

(Resins other than urethane acrylic resins and olefinic resins) In one embodiment of the present invention, the resin composition (y-1) may contain resins other than urethane acrylic resins and olefinic resins within a range that does not impair the effects of the present invention. Examples of such resins include vinyl resins such as polyvinyl chloride, polyvinyl chloride, and polyvinyl alcohol; polyester resins such as polyethylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate; polystyrene; acrylonitrile-butadiene-styrene copolymer; cellulose triacetate; polycarbonate; polyurethane that is not equivalent to acrylic urethane resin; polysulfone; polyetheretherketone; polyethersulfone; polyphenylene sulfide; polyimide resins such as polyetherimide and polyimide; polyamide resins; acrylic resins; fluorine resins, and the like.

However, from the viewpoint of forming a thermally expandable substrate layer (Y1) satisfying the above requirement (1), the content of resins other than urethane acrylic resins and olefinic resins in the resin composition (y-1) is preferably less than 30 parts by mass, more preferably less than 20 parts by mass, more preferably less than 10 parts by mass, more preferably less than 5 parts by mass, and even more preferably less than 1 part by mass, relative to 100 parts by mass of the total amount of the resin contained in the resin composition (y-1).

(Solvent-free resin composition (y-1a)) As one form of the resin composition (y-1) used in one form of the present invention, there is a solvent-free resin composition (y-1a) which is formed by mixing an oligomer having an ethylenic unsaturated group with a mass average molecular weight (Mw) of 50,000 or less, an energy ray polymerizable monomer, and the above-mentioned thermally expandable particles, and is not mixed with a solvent. Although the solvent-free resin composition (y-1a) is not mixed with a solvent, the energy ray polymerizable monomer is used to improve the plasticity of the above-mentioned oligomer. By irradiating the coating film formed of the solvent-free resin composition (y-1a) with energy rays, a thermally expandable base layer (Y1) satisfying the above-mentioned requirement (1) can be easily formed.

Furthermore, the type or shape and the blending amount (content) of the thermally expandable particles blended in the solvent-free resin composition (y-1a) are as described above.

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

Furthermore, the aforementioned oligomer may be any resin contained in the aforementioned resin composition (y-1) having a mass average molecular weight of 50,000 or less and having an ethylenically unsaturated group, but the aforementioned urethane prepolymer (UP) is preferred. Furthermore, as the oligomer, a modified olefin resin having an ethylenically unsaturated group may also be used.

In the solvent-free resin composition (y-1a), the total content of the oligomer and the energy beam polymerizable monomer is preferably 50-99 mass %, more preferably 60-95 mass %, more preferably 65-90 mass %, and even more preferably 70-85 mass % relative to the total amount (100 mass %) of the solvent-free resin composition (y-1a).

Examples of energy ray polymerizable monomers include alicyclic polymerizable compounds such as isoborneol (meth)acrylate, dicyclopentenyl (meth)acrylate, dicyclopentyl (meth)acrylate, dicyclopentenyloxy (meth)acrylate, cyclohexyl (meth)acrylate, adamantane (meth)acrylate, tricyclodecane acrylate, etc.; aromatic polymerizable compounds such as phenylhydroxypropyl acrylate, benzyl acrylate, ethylene oxide modified acrylate, etc.; heterocyclic polymerizable compounds such as tetra(hydroxy)furylmethyl (meth)acrylate, morpholine acrylate, N-vinylpyrrolidone, N-vinylcyclohexanone, etc. These energy ray polymerizable monomers may be used alone or in combination of two or more.

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

In one form of the present invention, the solvent-free resin composition (y-1a) is preferably further mixed with a photopolymerization initiator. By containing a photopolymerization initiator, the curing reaction can be fully carried out even by irradiation with relatively low energy energy rays.

As the photopolymerization initiator, there are listed the same ones as those that can be contained in the adhesive composition (x-1). These photopolymerization initiators can be used alone or in combination of two or more.

The amount of the photopolymerization initiator mixed is preferably 0.01 to 5 parts by mass, more preferably 0.01 to 4 parts by mass, and even more preferably 0.02 to 3 parts by mass relative to the total amount (100 parts by mass) of the aforementioned oligomer and energy-ray-polymerizable monomer.

(Thickness of the thermally expandable substrate layer (Y1)) In one embodiment of the present invention, the thickness of the thermally expandable substrate layer (Y1) is preferably 10 to 1000 μm, more preferably 20 to 500 μm, more preferably 25 to 400 μm, and even more preferably 30 to 300 μm.

<Non-thermal expansion base layer (Y2)> The non-thermal expansion base layer (Y2) of the adhesive sheet of the present invention is provided on the surface opposite to the laminated surface of the adhesive layer (X1) of the thermal expansion base layer (Y1). In the adhesive sheet of the present invention, the Young's modulus of the non-thermal expansion base layer (Y2) at 23°C is higher than the Young's modulus of the adhesive layer (X1) at 23°C. Therefore, when the heat-expandable particles are expanded, it is easier to form unevenness on the surface of the heat-expandable base layer (Y1) on the adhesive layer (X1) side than on the surface of the heat-expandable base layer (Y2) on the non-heat-expandable base layer (Y1). Therefore, unevenness can be well formed on the adhesive surface of the adhesive layer (X1). From a related point of view, the Young's modulus of the non-heat-expandable base layer (Y2) at 23°C is preferably 700 MPa or more, more preferably 1000 MPa or more, more preferably 1300 MPa or more, more preferably 1600 MPa or more, and further preferably 1800 MPa or more. And, it is usually 10000 MPa or less.

Examples of the material for forming the non-thermally expansive base layer (Y2) include resin, metal, and paper, and the material can be appropriately selected according to the purpose of the adhesive sheet of the present invention.

Examples of the resin include polyolefin resins such as polyethylene and polypropylene; vinyl resins such as polyvinyl chloride, polyvinyl chloride, polyvinyl alcohol, ethylene-vinyl acetate copolymer, and ethylene-vinyl alcohol copolymer; polyester resins such as polyethylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate; polystyrene; acrylonitrile-butadiene-styrene copolymer; cellulose triacetate; polycarbonate; urethane resins such as polyurethane and acrylic modified polyurethane; polymethylpentene; polysulfone; polyetheretherketone; polyethersulfone; polyphenylene sulfide; polyimide resins such as polyetherimide and polyimide; polyamide resins; acrylic resins; fluorine resins, etc. Examples of metals include aluminum, tin, chromium, and titanium. Examples of paper materials include thin paper, medium-quality paper, high-quality paper, impregnated paper, coated paper, copperplate paper, sulfate paper, and glass paper. Among these, polyester resins such as polyethylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate are preferred.

These forming materials may be composed of one kind or two or more kinds may be used in combination. As the non-thermal expansion base material layer (Y2) using two or more forming materials in combination, there are those in which a paper material is laminated with a thermoplastic resin such as polyethylene, or a resin film containing a resin, or a metal film is formed on the surface of a sheet. In addition, as a method for forming a metal layer, there are methods such as evaporating the above metal by a PVD method such as vacuum evaporation, sputtering, ion coating, etc., or a method of attaching the above metal using a general adhesive to form a metal foil.

Furthermore, from the viewpoint of improving the interlayer adhesion between the non-thermal expansion base layer (Y2) and other layers of the laminate, when the non-thermal expansion base layer (Y2) contains a resin, the surface of the non-thermal expansion base layer (Y2) is also subjected to surface treatment, easy-to-bond treatment or base layer treatment by oxidation method or embossing method in the same manner as the above-mentioned thermal expansion base layer (Y1).

Furthermore, when the non-thermally expandable base layer (Y2) includes a resin, the above-mentioned base additive that may also be contained in the resin composition (y-1) may be contained together with the resin.

The non-thermally expansive base layer (Y2) is a non-thermally expansive layer determined by the above method. Therefore, the volume change rate (%) of the non-thermally expansive base layer (Y2) calculated by the above formula is less than 5%, but preferably less than 2%, more preferably less than 1%, more preferably less than 0.1%, and even more preferably less than 0.01%.

Furthermore, the non-thermally expandable substrate layer (Y2) may also 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 substrate layer (Y2), the volume change rate can be adjusted to the above range even if thermally expandable particles are contained. However, the less the content of thermally expandable particles in the non-thermally expandable substrate layer (Y2), the better. Specifically, the content of the thermally expandable particles is generally less than 3 mass%, preferably less than 1 mass%, more preferably less than 0.1 mass%, more preferably less than 0.01 mass%, and even more preferably less than 0.001 mass%, relative to the total mass (100 mass%) of the non-thermally expandable base layer (Y2). Furthermore, it is preferred that the thermally expandable particles are not contained.

(Storage elastic modulus E'(23) of the non-thermal expansion base layer (Y2) at 23°C) The storage elastic modulus E'(23) of the non-thermal expansion base layer (Y2) at 23°C is preferably 5.0×10 ⁷ to 5.0×10 ⁹ Pa, more preferably 5.0×10 ⁸ to 4.5×10 ⁹ Pa, and even more preferably 1.0×10 ⁹ to 4.0×10 ⁹ Pa. As long as the storage elasticity E'(23) of the non-thermal expansion base layer (Y2) is 5.0×10 ⁷ Pa or more, the expansion of the surface of the non-thermal expansion base layer (Y2) side of the thermal expansion base layer (Y1) can be effectively suppressed, and the deformation resistance of the adhesive sheet can be improved. On the other hand, as long as the storage elasticity E'(23) of the non-thermal expansion base layer (Y2) is 5.0×10 ⁹ Pa or less, the handling property of the adhesive sheet can be improved. In this specification, the storage elasticity E'(23) of the non-thermal expansion base layer (Y2) means the value measured by the method described in the embodiment.

(Storage elastic modulus E'(t) of the non-thermally expansive base layer (Y2) at the expansion starting temperature (t)) The storage elastic modulus E'(t) of the thermally expansive particles of the non-thermally expansive base layer (Y2) at the expansion starting temperature (t) is preferably 5.0×10 ⁷ ~3.0×10 ⁹ Pa, more preferably 2.0×10 ⁸ ~2.5×10 ⁹ Pa, and even more preferably 5.0×10 ⁸ ~2.0×10 ⁹ Pa. When the storage elasticity E'(t) of the non-thermally expansive base layer (Y2) is 5.0×10 ⁷ Pa or more, the expansion of the surface of the non-thermally expansive base layer (Y2) side of the thermally expansive base layer (Y1) can be effectively suppressed, and the deformation resistance of the adhesive sheet can be easily improved. On the other hand, when the storage elasticity E'(t) of the non-thermally expansive base layer (Y2) is 3.0×10 ⁹ Pa or less, the handling property of the adhesive sheet can be easily improved. In this specification, the storage elasticity E'(t) of the non-thermally expansive base layer (Y2) means a value measured by the method described in the embodiment.

(Thickness of non-thermal expansion substrate layer (Y2)) The thickness of the non-thermal expansion substrate layer (Y2) is preferably 5 to 500 μm, more preferably 15 to 300 μm, and even more preferably 20 to 200 μm. As long as the thickness of the non-thermal expansion substrate layer (Y2) is 5 μm or more, the deformation resistance of the adhesive sheet can be easily improved. On the other hand, as long as the thickness of the non-thermal expansion substrate layer (Y2) is 500 μm or less, the operability of the adhesive sheet can be easily improved. In addition, in this specification, the thickness of the non-thermal expansion substrate layer (Y2) means the value measured by the method described in the embodiment.

<Adhesive layer (X2)> The adhesive layer (X2) is a layer arbitrarily provided on the surface of the non-thermally expansive base layer (Y2) opposite to the laminated surface of the thermally expansive base layer (Y1). The adhesive layer (X2) may be a thermally expansive layer or a non-thermally expansive layer, but is preferably a non-thermally expansive layer. By making the adhesive layer (X1) and the adhesive layer (X2) different in the mechanism of action for reducing the adhesive force of the adhesive layer, when the adhesive force of one adhesive layer is reduced, it is possible to suppress the adhesive force of the other adhesive layer from being reduced unintentionally.

When the adhesive layer (X2) is a non-thermally expandable layer, the volume change rate (%) of the adhesive layer (X2) calculated by the above formula is less than 5%, preferably less than 2%, more preferably less than 1%, more preferably less than 0.1%, and even more preferably less than 0.01%. The adhesive layer (X2) preferably does not contain thermally expandable particles, but may contain thermally expandable particles within the scope of the present invention. When the adhesive layer (X2) contains thermally expandable particles, the smaller the content, the better. It is preferably less than 3 mass%, more preferably less than 1 mass%, more preferably less than 0.1 mass%, more preferably less than 0.01 mass%, and even more preferably less than 0.001 mass%, relative to the total mass of the adhesive layer (X2) (100 mass%).

The adhesive layer (X2) is preferably formed of an adhesive composition (x-2) containing an adhesive resin. The following describes the components contained in the adhesive composition (x-2).

(Adhesive composition (x-2)) The adhesive composition (x-2) contains an adhesive resin and may also contain a crosslinking agent, an adhesive imparting agent, a polymerizable compound, a polymerization initiator, and adhesive additives used in general adhesives other than the above components as necessary.

(Adhesive resin) As the adhesive resin, any polymer having adhesive properties alone and a mass average molecular weight (Mw) of 10,000 or more is sufficient. From the viewpoint of further improving the adhesive force of the adhesive layer (X2), the mass average molecular weight (Mw) of the adhesive resin is preferably 10,000 to 2,000,000, more preferably 20,000 to 1,500,000, and even more preferably 30,000 to 1,000,000.

As the adhesive resin, there are those which are the same as the adhesive composition contained in the adhesive composition (x-1). These adhesive resins may be used alone or in combination of two or more. Furthermore, when these adhesive resins are copolymers having two or more constituent units, the copolymer may be in the form of a block copolymer, a random copolymer, or a graft copolymer.

From the viewpoint of changing the mechanism of action of reducing the adhesive force with the adhesive layer (X1), the adhesive resin contained in the adhesive composition (x-2) is preferably an adhesive composition that is hardened by irradiation with energy rays, and more preferably an adhesive composition that has energy ray polymerizable functional groups in the side chains. By forming the adhesive layer (X2) with the adhesive composition, it is possible to reduce the adhesive force by hardening the adhesive layer (X2) by irradiation with energy rays. Thereby, the adhesive surface of the adhesive layer (X1) becomes a type in which the adhesive force is reduced by heating, and the adhesive surface of the adhesive layer (X2) can become a type in which the adhesive force is reduced by energy ray irradiation, and the mechanism of action of reducing the adhesive force of each other adhesive layer can be changed. Therefore, when the treatment of reducing the adhesive force of any one adhesive layer is performed, the adhesive force of the other adhesive layer can be unintentionally suppressed. As energy ray polymerizable functional groups, there are carbon-carbon double bonds such as (meth)acryl, vinyl, and acryl. As energy rays, ultraviolet rays are preferred because they are easy to handle.

When the adhesive composition (x-2) is hardened by irradiation with energy beams, the adhesive composition preferably further contains a photopolymerization initiator. By containing a photopolymerization initiator, the polymerization of the energy beam polymerizable component can be carried out more effectively. As the photopolymerization initiator, the same photopolymerization initiator as that which can also be contained in the adhesive composition (x-1) can be cited. The content of the photopolymerization initiator is preferably 0.01 to 10 parts by mass, more preferably 0.03 to 5 parts by mass, and even more preferably 0.05 to 2 parts by mass relative to 100 parts by mass of the total amount of the adhesive resin having an energy beam polymerizable functional group.

From the viewpoint of exhibiting excellent adhesive force, the adhesive resin preferably contains an acrylic resin. The content of the acrylic resin in the adhesive composition (x-2) is preferably 30 to 100 mass %, more preferably 50 to 100 mass %, more preferably 70 to 100 mass %, and even more preferably 85 to 100 mass % relative to the total amount (100 mass %) of the adhesive resin contained in the adhesive composition (x-2).

The content of the adhesive resin in the adhesive composition (x-2) is preferably 35-100 mass %, more preferably 50-100 mass %, more preferably 60-98 mass %, and even more preferably 70-95 mass % relative to the total amount (100 mass %) of the active ingredients in the adhesive composition (x-2).

(Crosslinking agent) In one embodiment of the present invention, when the adhesive composition (x-2) contains an adhesive resin having a functional group, it is preferred that the adhesive composition (x-2) further contains a crosslinking agent. The crosslinking agent reacts with the adhesive resin having a functional group, uses the functional group as a crosslinking starting point, and crosslinks the adhesive resins with each other.

As the crosslinking agent that may be contained in the adhesive composition (x-2), the same crosslinking agents as those that may be contained in the adhesive composition (x-1) are exemplified, but from the viewpoint of increasing the cohesive force and the adhesive force and the ease of obtaining, isocyanate-based crosslinking agents are preferred.

The content of the crosslinking agent is appropriately adjusted according to the number of functional groups of the adhesive resin, but is preferably 0.01 to 10 parts by mass, more preferably 0.03 to 7 parts by mass, and even more preferably 0.05 to 5 parts by mass, relative to 100 parts by mass of the adhesive resin having the functional groups.

(Adhesion-imparting agent) In one embodiment of the present invention, the adhesive composition (x-2) may further contain an adhesion-imparting agent from the viewpoint of further enhancing adhesion. As the adhesion-imparting agent that the adhesive composition (x-2) may contain, the same adhesion-imparting agent as the adhesion-imparting agent that the adhesive composition (x-1) may contain may be used.

(Adhesive additive) As the adhesive additive, there are those which are the same as the adhesive additive that the adhesive composition (x-1) may also contain.

The adhesive composition (x-2) can be produced by mixing an adhesive resin, a crosslinking agent used as necessary, an adhesive imparting agent, an adhesive additive, and the like.

(Thickness of adhesive layer (X2) at 23°C) The thickness of the adhesive layer (X2) at 23°C is preferably 5 to 150 μm, more preferably 8 to 100 μm, more preferably 12 to 70 μm, and even more preferably 15 to 50 μm. As long as the thickness of the adhesive layer (X2) at 23°C is 5 μm or more, sufficient adhesion is easily obtained, and there is a tendency to suppress unintentional peeling of the adherend during temporary fixing and positional displacement of the adherend. On the other hand, as long as the thickness of the adhesive layer (X2) at 23°C is 150 μm or less, there is a tendency to facilitate the handling of the adhesive sheet.

<Release material> As the release material, there are peeling sheets with double-sided peeling treatment, peeling sheets with one-sided peeling treatment, etc., and peeling agents are applied to the base material for the release material. As the base material for the release material, there are plastic films, paper, etc. As plastic films, there are polyester resin films such as polyethylene terephthalate resin, polybutylene terephthalate resin, polyethylene naphthalate resin, etc.; olefin resin films such as polypropylene resin, polyethylene resin, etc., and as paper, there are high-quality paper, glass paper, kraft paper, etc.

Examples of the stripping agent include rubber elastomers such as silicone resins, olefin resins, isoprene resins, butadiene resins, long chain alkyl resins, alkyd resins, fluorine resins, etc. The stripping agent may be used alone or in combination of two or more.

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

[Method for producing adhesive sheet] The method for producing the adhesive sheet of the present invention is not particularly limited, and an example thereof includes the following steps (1a) to (3a). ･Step (1a): a step of applying an adhesive composition (x-1) on the peeling-treated surface of the peeling material to form an adhesive layer (X1). ･Step (2a): a step of applying a resin composition (y-1) on one side of a non-thermally expandable substrate layer (Y2) to form a substrate laminate having a laminated non-thermally expandable substrate layer (Y2) and a thermally expandable substrate layer (Y1). ･Step (3a): A step of bonding the adhesive surface of the adhesive layer (X1) formed in step (1a) to the surface of the thermally expandable substrate layer (Y1) side of the substrate laminate formed in step (2a).

Furthermore, as another method for manufacturing the adhesive sheet of the present invention, in addition to the above steps (1a) to (3a), there is provided a method for manufacturing a double-sided adhesive sheet having the above steps (4a) to (5a). ･Step (4a): a step of applying an adhesive composition (x-2) on the peeling-treated surface of the peeling material to form an adhesive layer (X2). ･Step (5a): a step of laminating the surface of the non-thermally expandable substrate layer (Y2) of the adhesive sheet formed in step (3a) to the adhesive surface of the adhesive layer (X2) formed in step (4a).

In the above-mentioned method for manufacturing the adhesive sheet, the resin composition (y-1), the adhesive composition (x-1) and the adhesive composition (x-2) may be further mixed with a dilute solvent to be in the form of a solution. As coating methods, there are, for example, spin coating, spray coating, rod coating, knife coating, roll coating, blade coating, mold coating and gravure coating.

Furthermore, in the step of drying the coating formed by the resin composition (y-1), the adhesive composition (x-1) and the adhesive composition (x-2), from the viewpoint of suppressing the expansion of the thermally expansive particles, it is preferred that the drying temperature be less than the expansion starting temperature (t) of the thermally expansive particles.

[Application and use method of the adhesive sheet of the present invention] The adhesive sheet of one type of the present invention can be easily peeled off by heating the temporarily fixed object, and can suppress the contamination of the surface of the object after peeling, and can be applied to various applications. Specifically, it is suitable for use as a dicing sheet used when cutting an object such as a semiconductor wafer, a backing sheet used in the step of grinding the object, an expansion tape used to increase the distance between individual semiconductor chips, a transfer tape used to reverse the inside and outside of a semiconductor chip, a temporary fixing sheet used to temporarily fix the inspection object, etc.

The adherend of the adhesive sheet of one form of the present invention is not particularly limited, but examples thereof include semiconductor chips, semiconductor wafers, compound semiconductors, semiconductor packages, electronic components, sapphire substrates, displays, and panel substrates. For example, when the expansion start temperature (t) of the thermally expandable particles of the adhesive sheet of one form of the present invention is set to less than 125°C, it can be thermally peeled off at a low temperature, so it is suitable for temporarily fixing the adherend that is easily thermally changed, such as a semiconductor chip with DAF. Moreover, in an adhesive sheet of one type of the present invention, when the expansion start temperature (t) of the heat-expandable particles is set to above 50°C, the unintentional expansion of the heat-expandable particles caused by the temperature rise when the adhered object is being ground can be suppressed, and therefore the adhesive sheet is suitable for use as a backing sheet used in the step of grinding the adhered object.

The heating temperature when one type of adhesive sheet of the present invention is heated and peeled off from the adhered body is above the expansion starting temperature (t) of the heat-expandable particles, preferably "a temperature higher than the expansion starting temperature (t)", more preferably "the expansion starting temperature (t) + 2°C" or above, more preferably "the expansion starting temperature (t) + 4°C" or above, and even more preferably "the expansion starting temperature (t) + 5°C" or above. Furthermore, from the viewpoint of suppressing the thermal change of the adhered body during heat peeling and energy saving, it is preferably below "expansion start temperature (t) + 50°C", more preferably below "expansion start temperature (t) + 40°C", and more preferably below "expansion start temperature (t) + 20°C". Furthermore, from the viewpoint of suppressing the thermal change of the adhered body during heat peeling, the heating temperature during heat peeling is preferably less than 125°C, more preferably below 120°C, more preferably below 115°C, more preferably below 110°C, and further preferably below 105°C within the range above the expansion start temperature (t).

The heating method is not particularly limited as long as it can heat to a temperature above the expansion temperature of the thermally expandable particles. For example, electric heating, induction heating, magnetic heating, infrared heating such as near infrared, mid infrared, and far infrared, etc. can be appropriately used. In addition, the heating method can also be any one of a contact heating method such as a heating drum and a heating spray, and a non-contact heating method such as an environmental heating device and infrared irradiation.

[Manufacturing method of semiconductor device] The present invention also provides a manufacturing method of a semiconductor device using an adhesive sheet of one type of the present invention. As one type of the manufacturing method of the semiconductor device of the present invention, there is a method in which the adhesive sheet of one type of the present invention is used as a temporary fixing sheet for processing and inspecting at least one of the attached objects (hereinafter also referred to as "the first type of manufacturing method of semiconductor device"). In addition, in this specification, "semiconductor device" means a device as a whole that can function by utilizing semiconductor characteristics. For example, a wafer having an integrated circuit, a wafer having an integrated circuit and being thinned, a chip having an integrated circuit, a chip having an integrated circuit and being thinned, an electronic component including such a chip, and an electronic device having such an electronic component, etc.

<First type of semiconductor device manufacturing method> As a more specific form of the first type of semiconductor device manufacturing method, there is a semiconductor device manufacturing method, which includes a step of attaching an adhesive sheet of one type of the present invention to a processing inspection object, applying one or more selected from processing and inspection to the processing inspection object, and then heating the adhesive sheet to a temperature above the expansion start temperature (t). As the processing inspection object, there are semiconductor chips, semiconductor wafers, compound semiconductors, semiconductor packages, electronic parts, LED components, sapphire substrates, displays, panel substrates, etc. The processing performed on the processing inspection object is not particularly limited, but examples include grinding processing, individual chip processing, etc. The inspection of the object to be inspected is not particularly limited, but examples include optical microscopes, defect inspections using lasers (such as scrap inspections, surface damage inspections, wiring pattern inspections, etc.), and visual surface inspections.

In the first type of manufacturing method for semiconductor devices, the adhesive layer of the adhesive sheet to which the processing inspection object is attached can also be an adhesive layer (X1), and when the adhesive sheet is a double-sided adhesive sheet, it can also be an adhesive layer (X2). Moreover, when the adhesive sheet is a double-sided adhesive sheet, it is preferred to attach the processing inspection object to the adhesive layer of either side and to attach the support body to the adhesive layer of the other side. By fixing the processing inspection object to the support body via the adhesive sheet, when at least one of processing and inspection is performed, vibration, positional deviation, and damage to the fragile processing inspection object can be suppressed, and processing accuracy and processing speed as well as inspection accuracy and inspection speed can be improved. At this time, the support may be attached to the adhesive layer (X1), and the object to be inspected may be attached to the adhesive layer (X2), or the object to be inspected may be attached to the adhesive layer (X1), and the support may be attached to the adhesive layer (X2). In the case where the support is attached to the adhesive layer (X1), and the object to be inspected may be attached to the adhesive layer (X2), by attaching the support to the adhesive layer (X1) having excellent releasability after heat treatment, even if the support is made of a hard material, heat-stripping can be performed without bending the adhesive sheet and the support. Furthermore, the adhesive layer (X2) can be appropriately composed according to the type of the object to be processed and inspected. For example, by setting the adhesive layer (X2) to an adhesive layer whose adhesive force is reduced by energy beam irradiation, the object to be processed will not be contaminated by residues from thermally expandable particles, and can be peeled off. On the other hand, in the case where the object to be inspected is attached to the adhesive layer (X1) and the support is attached to the adhesive layer (X2), the object to be inspected is attached to the adhesive layer (X1) having excellent releasability after heat treatment, and when the object to be inspected is heat-removed after processing, it is not necessary to pick up the object to be inspected individually, and the object can be removed in bulk and easily, thereby improving the productivity of the semiconductor device. In addition, when the adhesive sheet of one type of the present invention is used as a temporary fixing sheet for inspecting the object to be inspected in one of the manufacturing steps, it is possible to inspect a plurality of objects to be inspected attached to the adhesive layer (X1) of the adhesive sheet. After the inspection, for example, a portion of the adhesive sheet to which the plurality of inspection objects are attached can be locally heated, and the specific inspection objects attached to the portion can be selectively heat-peeled. In this case, the adhesive sheet of one embodiment of the present invention can be heat-peeled at a low temperature, so that the workability and energy saving of the heat-peeling operation are excellent. Even if the inspection object is susceptible to heat change, the heat change of the inspection object caused by heating during heat-peeling can be suppressed.

<Method for manufacturing semiconductor device of the second type> As a method for manufacturing semiconductor device of the second type, there is provided a manufacturing method (hereinafter also referred to as "manufacturing method A") using a double-sided adhesive sheet having an expansion start temperature (t) of thermally expandable particles of 50°C or more and less than 125°C as one type of adhesive sheet of the present invention, and comprising the following steps 1A to 3A, the following first separation step, and the following second separation step. Step 1A: a step of attaching a processing object to the adhesive layer (X2) and attaching a support to the adhesive layer (X1) Step 2A: a step of subjecting the aforementioned processing object to one or more treatments selected from grinding and individualization Step 3A: a step of attaching a thermosetting film to the surface of the processing object to which the aforementioned treatment is applied, which is opposite to the adhesive layer (X2) First separation step: a step of heating the aforementioned adhesive sheet to a temperature above the aforementioned expansion start temperature (t) and below 125°C, and separating the adhesive layer (X1) from the aforementioned support Second separation step: a step of separating the adhesive layer (X2) from the aforementioned processing object

Hereinafter, a method for manufacturing a semiconductor device including steps 1A to 3A, a first separation step, and a second separation step 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 is mainly described, but the same is true for other processing objects. As other processing objects, the same objects as those mentioned above as processing inspection objects are listed.

(Step 1A) Step 1A is a step of attaching an object to be processed to the adhesive layer (X2) of the adhesive sheet, and attaching a support to the adhesive layer (X1). Figure 3 is a cross-sectional view showing the step of attaching a semiconductor wafer W to the adhesive layer (X2) of the adhesive sheet 2b, and attaching a support 3 to the adhesive layer (X1). The surface W1 of the semiconductor wafer W attached as the conductive surface becomes the side of the adhesive layer (X2). The semiconductor wafer W can also be a silicon wafer, or a wafer of gallium arsenide, silicon carbide, sapphire, lithium tantalum, lithium niobate, gallium nitride, phosphorus indium, etc., or a glass wafer. The thickness of the semiconductor wafer W before grinding is usually 500~1000μm. The circuit on the surface W1 of the semiconductor wafer W can be formed by conventionally widely used methods such as etching and lift-off.

The material of the support 3 can be appropriately selected according to the type of the object to be processed, the processing content, etc., and the required characteristics such as mechanical strength and heat resistance. As the material of the support 3, there are metal materials such as SUS; non-metallic inorganic materials such as glass and silicon wafers; resin materials such as epoxy resin, ABS resin, acrylic resin, engineering plastic, super engineering plastic, polyimide resin, polyamide amide resin; composite materials such as glass epoxy resin, etc. Among them, SUS, glass, and silicon wafer are preferred. As the above-mentioned engineering plastics, there are nylon, polycarbonate (PC), polyethylene terephthalate (PET), etc. Examples of the super engineering plastics include polyphenylene sulfide (PPS), polyether sulfide (PES), and polyether ether ketone (PEEK).

The support 3 is preferably attached to the entire adhesive surface of the adhesive layer (X1). Therefore, the surface area of the support 3 attached to the adhesive surface of the adhesive layer (X1) is preferably greater than the area of the adhesive surface of the adhesive layer (X1). Moreover, the surface of the support 3 attached to the adhesive surface of the adhesive layer (X1) is preferably flat. The shape of the support 3 is not particularly limited, but a plate shape is preferred. The thickness of the support 3 is appropriately selected in consideration of the required characteristics, but is preferably greater than 20μm and less than 50mm, and more preferably greater than 60μm and less than 20mm.

(Step 2A) Step 2A is a step of subjecting the aforementioned processing object to one or more treatments selected from grinding and individualization. As one or more treatments selected from grinding and individualization, there are grinding using a grinder, etc.; individualization by blade cutting, laser cutting, invisible cutting (registered trademark) method; grinding and individualization by blade first cutting method, invisible first cutting method; etc. Among these, individualization processing by invisible cutting method, grinding processing by blade first cutting method and individualization processing, grinding processing by invisible first cutting method and individualization processing are more suitable, and grinding processing by blade first cutting method and individualization processing, grinding processing by invisible first cutting method and individualization processing are more suitable.

The invisible dicing method is a method of forming a modified area inside a semiconductor wafer by irradiating laser light, using the modified area as the starting point for segmentation, and singulating the semiconductor wafer. The modified area formed on the semiconductor wafer is a part that has become brittle due to multi-photon absorption. The semiconductor wafer will apply pressure in the direction parallel to the wafer surface and the direction of wafer expansion due to expansion, thereby using the modified area as the starting point, and the cracks will extend to the surface and inner surface of the semiconductor wafer, thereby singulating the semiconductor wafer. That is, the modified area is formed along the dividing line when being singulated. The modified area is formed inside the semiconductor wafer by irradiating the laser light with the focus concentrated on the inside of the semiconductor wafer. The incident surface of the laser light can also be the surface or inner surface of the semiconductor wafer. Furthermore, the laser light incident surface may also be the surface to which the adhesive sheet is attached. In this case, the laser light is irradiated to the semiconductor wafer through the adhesive sheet.

The dicing-before-grinding method is also called the DBG method (Dicing Before Grinding). The dicing-before-grinding method is a method of forming a groove in advance on the semiconductor wafer along the predetermined dividing line at a depth shallower than its thickness, and then grinding the inner surface of the semiconductor wafer so that the ground surface at least reaches the groove, thinning the semiconductor wafer while individualizing it. The groove reached by the ground surface will become a groove that passes through the semiconductor wafer, and the semiconductor wafer will be divided by the groove, and the semiconductor chip will be individualized. The pre-formed groove is usually set on the surface (conductor surface) of the semiconductor wafer, and can be formed, for example, by cutting using a conventionally known wafer cutting device equipped with a cutting blade.

Stealth Dicing Before Grinding is also called SDBG (Stealth Dicing Before Grinding). Stealth Dicing Before Grinding is a method of forming a modified area inside a semiconductor wafer by irradiating laser light in the same way as the stealth dicing method, and using the modified area as the starting point for division to separate the semiconductor wafer. However, it is different from the stealth dicing method in that the semiconductor wafer is thinned by grinding and the semiconductor wafer is separated into semiconductor chips. Specifically, while the semiconductor wafer with the modified area is thinned by grinding the inside, the pressure applied to the semiconductor wafer is used to set the modified area as the starting point, and the cracks extend to the bonding surface of the adhesive layer of the semiconductor wafer, and the semiconductor wafer is separated into semiconductor chips. Furthermore, the grinding thickness after forming the modified area may also be the thickness reaching the modified area, but strictly speaking, even if the modified area is not reached, the grinding is performed to a position close to the modified area, and the processing pressure of the grinding stone is used to cut it.

When the semiconductor wafer W is cut into pieces by the blade first dicing method, it is preferred to pre-form a groove on the surface W1 of the semiconductor wafer W attached to the adhesive layer (X2) in step 1A. On the other hand, when the semiconductor wafer W is cut into pieces by the invisible first dicing method, the semiconductor wafer W attached to the adhesive layer (X2) in step 1A may be irradiated with laser light to pre-form a modified region, and the semiconductor wafer W attached to the adhesive layer (X2) may be irradiated with laser light to form a modified region.

FIG4 is a cross-sectional view showing the step of forming a plurality of modified regions 5 using a laser light irradiation device 4 on a semiconductor wafer W attached to an adhesive layer (X2). The laser light is irradiated from the inner surface W2 side of the semiconductor wafer W, and a plurality of modified regions 5 are formed in the interior of the semiconductor wafer W at large intervals.

FIG5 is a cross-sectional view showing a step of grinding the inner surface W2 of the semiconductor wafer W having the modified region 5 by a grinder 6, thinning the semiconductor wafer W by cutting with the modified region 5 as the starting point, and dividing the semiconductor wafer W into a plurality of semiconductor chips CP. The semiconductor wafer W having the modified region 5 is ground with the inner surface W2 thereof being ground in a state where the support body 3 supporting the semiconductor wafer W is fixed on a fixed seat such as a chuck seat.

The thickness of the semiconductor chip CP after grinding is preferably 5-100 μm, more preferably 10-45 μm. Furthermore, when grinding and individualizing are performed by invisible pre-cutting method, it is easier to set the thickness of the semiconductor chip CP obtained after grinding to less than 50 μm, more preferably 10-45 μm. The size of the semiconductor chip CP after grinding is preferably less than 600 mm ² , more preferably less than 400 mm ² , and even more preferably less than 300 mm ² . Furthermore, the size viewed in the plane is viewed in the thickness direction. The shape of the semiconductor chip CP after individualizing in the plane may be a square, or a long and thin shape such as a rectangle. In addition, in the adhesive sheet used in the second type of semiconductor device manufacturing method, since the expansion start temperature (t) of the thermally expansive particles is above 50°C, the thermally expansive particles can be prevented from unintentionally expanding due to the temperature rise during grinding, etc., thereby preventing unintentional separation or positional displacement of the object to be processed.

(Step 3A) Step 3A is a step of attaching a thermosetting film to the surface of the object to be processed which is opposite to the adhesive layer (X2). FIG. 6 is a cross-sectional view showing a step of attaching a thermosetting film 7 having a supporting sheet 8 to the surface of the plurality of semiconductor chips CP obtained by the above-mentioned processing which is opposite to the adhesive layer (X2).

The thermosetting film 7 is a thermosetting film obtained by filming a resin composition containing at least a thermosetting resin, and is used as an adhesive when mounting the semiconductor chip CP on a substrate. The thermosetting film 7 may also contain a curing agent for the above-mentioned thermosetting resin, a thermoplastic resin, an inorganic filler, a curing accelerator, etc. as necessary. As the thermosetting film 7, a generally used thermosetting film such as a solid crystal film or a solid crystal material film 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 supporting sheet 8 may be any material that can support the thermosetting film 7, and examples thereof include resin, metal, and paper materials such as those provided as the non-thermal expansion base material layer (Y2) of the adhesive sheet of one embodiment of the present invention.

As a method of attaching the thermosetting film 7 to a plurality of semiconductor chips CP, there is a lamination method, for example. Lamination can be performed while heating or without heating. The heating temperature when performing lamination while heating is preferably "a temperature lower than the expansion start temperature (t)" from the viewpoint of suppressing the expansion of the thermally expansive particles and suppressing the thermal change of the adherend, more preferably "the expansion start temperature (t) - 5°C" or less, more preferably "the expansion start temperature (t) - 10°C" or less, and even more preferably "the expansion start temperature (t) - 15°C" or less from the viewpoint of suppressing the expansion of the thermally expansive particles and suppressing the thermal change of the adherend.

(First separation step) The first separation step is to heat the adhesive sheet to a temperature above the expansion start temperature (t) and below 125°C, and to separate the adhesive layer (X1) from the support. Figure 7 is a cross-sectional view showing the step of heating the adhesive sheet 2b and separating the adhesive layer (X1) from the support 3.

The heating temperature in the first separation step is above the expansion start temperature (t) of the heat-expandable particles and below 120°C, preferably "a temperature higher than the expansion start temperature (t)", more preferably "the expansion start temperature (t) + 2°C" or above, more preferably "the expansion start temperature (t) + 4°C" or above, and even more preferably "the expansion start temperature (t) + 5°C" or above. Moreover, the heating temperature in the first separation step is preferably below "expansion start temperature (t) + 50°C" in the range of less than 125°C, more preferably below "expansion start temperature (t) + 40°C", and more preferably below "expansion start temperature (t) + 20°C" from the viewpoint of energy saving and suppressing thermal changes of the adhered body during heat stripping. The heating temperature in the first separation step is preferably below 120°C, more preferably below 115°C, more preferably below 110°C, and more preferably below 105°C in the range above the expansion start temperature (t), from the viewpoint of suppressing thermal changes of the adhered body.

(Second separation step) The second separation step is a step of separating the adhesive layer (X2) from the aforementioned processing object. FIG8 shows a cross-sectional view of the step of separating the adhesive layer (X2) from the plurality of semiconductor chips CP. The method of separating the adhesive layer (X2) from the plurality of semiconductor chips CP can be appropriately selected according to the type of the adhesive layer (X2). For example, when the adhesive layer (X2) is an adhesive layer whose adhesive force is reduced by energy beam irradiation, the adhesive layer (X2) can be irradiated with energy beams to reduce the adhesive force before separation.

After the above steps 1A to 3A, the above first separation step and the above second separation step, a plurality of semiconductor chips CP attached to the thermosetting film 7 are obtained. Then, the thermosetting film 7 to which the plurality of semiconductor chips CP are attached is divided into the same shape as the semiconductor chip CP, and a semiconductor chip CP with a thermosetting film 7 is preferably obtained. As a method for dividing the thermosetting film 7, methods such as laser cutting, expansion, and dissolution using laser light 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 is further appropriately subjected to an expansion step of expanding the interval between the semiconductor chips CP, a rearrangement step of arranging the plurality of semiconductor chips CP with the expanded interval, a reversal step of reversing the inside and outside of the plurality of semiconductor chips CP, etc., as necessary, and then attached (bonding material) to the substrate from the thermosetting film 7 side. Thereafter, the semiconductor chip and the substrate can be fixed by thermally curing the thermosetting film.

The method for manufacturing a semiconductor device according to one aspect of the present invention may be a method that does not include step 3A in the manufacturing method A. When step 3A is not included, the first separation step may be a step of heating the adhesive sheet to a temperature above the expansion start temperature (t) and separating the adhesive layer (X1) from the support.

The manufacturing method of the second type of semiconductor device may also include the following steps 1B to 3B, the following first separation step and the following second separation step (hereinafter also referred to as "manufacturing method B"). Step 1B: A step of attaching a processing object to the adhesive layer (X1) of the adhesive sheet, and attaching a support to the adhesive layer (X2) of the aforementioned adhesive sheet Step 2B: A step of applying one or more treatments selected from grinding and individualization to the aforementioned processing object Step 3B: A step of attaching a processing object to the aforementioned processing object and the aforementioned adhesive layer (X2) to the aforementioned processing object. The step of attaching a thermosetting film having thermosetting properties to the surface opposite to the adhesive layer (X1) The first separation step: heating the adhesive sheet to a temperature above the expansion start temperature (t) and below 125°C, and separating the adhesive layer (X1) from the object to be processed The second separation step: separating the adhesive layer (X2) from the support

Steps 1B to 3B are explained by replacing the adhesive layer (X1) in the description of steps 1A to 3A with the adhesive layer (X2), and replacing the adhesive layer (X2) with the adhesive layer (X1).

The first separation step is a step of heating the aforementioned adhesive sheet to a temperature above the aforementioned expansion start temperature (t) and below 125°C, and separating the adhesive layer (X1) from the aforementioned object to be processed. The heating conditions such as the heating temperature of the adhesive sheet in the first separation step are the same as those described in the manufacturing method A. Through the first separation step, a plurality of semiconductor chips attached to the thermosetting film are obtained. Thereafter, the thermosetting film is divided in the same manner as in the above-mentioned manufacturing method A to obtain a semiconductor chip with a thermosetting film attached.

The second separation step is a step of separating the adhesive layer (X2) from the aforementioned support. The method of separating the adhesive layer (X2) from the support can also be appropriately selected according to the type of the adhesive layer (X2). For example, when the adhesive layer (X2) is an adhesive layer whose adhesive force is reduced by energy beam irradiation, the adhesive layer (X2) can be irradiated with energy beams to reduce the adhesive force before separation.

The method for manufacturing a semiconductor device according to one aspect of the present invention may be a method B that does not include step 3B. When step 3B is not included, the first separation step may be a step of heating the adhesive sheet to a temperature above the expansion start temperature (t) and separating the adhesive layer (X1) from the object to be processed.

<Manufacturing method of another type of semiconductor device> The manufacturing method of the semiconductor device of the present invention is not limited to the manufacturing method of the first type of semiconductor device mentioned above, and can also be a manufacturing method of another type of semiconductor device of the first type.

As another example of a method for manufacturing another type of semiconductor device, there is a method for separating a processing object attached to another sheet from the other sheet using an adhesive sheet of one type of the present invention. For example, a plurality of semiconductor chips with enlarged spacing on an expansion tape are attached to the adhesive surface of the expansion tape, but the operation of picking up these chips one by one is complicated. According to a method for manufacturing a semiconductor device of one type of the present invention, an adhesive layer (X1) of an adhesive sheet of one type of the present invention is attached to the exposed surface of a plurality of semiconductor chips attached to an expansion tape, and then, by peeling the expansion tape from the plurality of semiconductor chips, the plurality of semiconductor chips can be separated from the expansion tape at one time. Through the above steps, a plurality of semiconductor chips attached to an adhesive sheet of one type of the present invention are obtained. The plurality of semiconductor chips can be easily separated by subsequently heating the adhesive sheet to a temperature above the expansion start temperature (t) of the thermally expandable particles. At this time, since the adhesive sheet of one type of the present invention can be thermally peeled at a low temperature, the workability and energy saving of the thermal peeling operation are excellent. Even if the object to be processed is easily thermally changed, the thermal change of the object caused by heating during thermal peeling can be suppressed. The separated multiple semiconductor chips can also be transferred to another adhesive sheet, or after separation, they can be provided to the re-arrangement step of arranging multiple semiconductor chips. [Example]

The present invention is specifically described with reference to the following examples, but the present invention is not limited to the following examples. The physical property values in the following synthesis examples, production examples and examples are values measured by the following methods.

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

[Thickness of each layer] Measured using a constant pressure thickness tester manufactured by Teclock Co., Ltd. (model: "PG-02J", standard specifications: JIS K6783, Z1702, Z1709).

[Average particle size (D ₅₀ ) and 90% particle size (D ₉₀ ) of thermally expansive particles] The particle distribution of thermally expansive particles before expansion at 23°C is measured using a laser diffraction particle size distribution measuring device (e.g., manufactured by Malvern, product name “Mastersizer 3000”). The particle sizes corresponding to the 50% and 90% cumulative volume frequencies calculated from the smaller particle size of the particle distribution are set as the “average particle size (D ₅₀ ) of thermally expansive particles” and the “90% particle size (D ₉₀ ) of thermally expansive particles”, respectively.

[Storage elasticity E' of substrate] The thermal expansion substrate layer (Y1) and the non-thermal expansion substrate layer (Y2) cut into 5mm in length and 30mm in width were used as test samples. The storage elasticity E' at a specific temperature was measured using a dynamic viscoelasticity measuring device (manufactured by TA Instruments, product name "DMAQ800") with a test start temperature of 0℃, a test end temperature of 200℃, a heating rate of 3℃/min, a vibration frequency of 1Hz, and an amplitude of 20μm.

[Young's modulus of substrate at 23°C] The Young's modulus of the thermally expansive substrate layer (Y1) and the non-thermally expansive substrate layer (Y2) were measured at a test speed of 200 mm/min in accordance with JIS K-7127 (1999).

In the following manufacturing examples, the adhesive resin, additive, thermal expansion particles, and release material used in the formation of each layer are described in detail below.

<Adhesive resin> ･Acrylic acid copolymer (A1): containing a solution of acrylic acid copolymer with Mw 600,000, with constituent units of raw material monomers of n-butyl acrylate (BA)/methacrylate (MMA)/acrylic acid (AA)/2-hydroxyethyl acrylate (HEA) = 86/8/1/5 (mass ratio), diluent: ethyl acetate, solid content: 40 mass% ･Acrylic acid copolymer (A2 ): A solution of an acrylic copolymer with a composition unit of raw material monomers of 2-ethylhexyl acrylate (2EHA)/acrylic acid (AA)/2-hydroxyethyl acrylate (HEA) = 92.8/0.2/7 (mass ratio), and Mw 600,000, diluent: ethyl acetate, solid content: 35 mass% ･Acrylic copolymer (A3): Made by Nippon Synthetic Chemical Industry Co., Ltd., product name "COPONYL N-9177", adhesive solution containing acrylic copolymer ･Acrylic copolymer (A4): containing a raw material monomer unit composed of 2-ethylhexyl acrylate (2EHA)/methyl methacrylate (MMA)/2-hydroxyethyl acrylate (HEA) = 60/30/10 (mass ratio), and a solution of acrylic copolymer with Mw 60, diluent: ethyl acetate, solid content: 40 mass% ･Acrylic copolymer (A5): containing a raw material monomer unit composed of n- An acrylic copolymer of the raw material monomers of butyl acrylate (BA)/methacrylate (MMA)/2-hydroxyethyl acrylate (HEA) = 52/20/28 (mass ratio) is reacted with 2-methacryloyloxyethyl isocyanate (MOI) to make the addition rate of all hydroxyl groups in the acrylic copolymer 80% on a molar basis, and a solution of an energy-ray-curable acrylic copolymer with Mw 500,000 is prepared. The diluting solvent is ethyl acetate, and the solid content is 35% by mass.

＜Additives＞ ･Isocyanate crosslinking agent (i): Tosoh Co., Ltd., product name "CORONATE HX", a solution containing an isocyanurate-type denatured product of hexamethylene diisocyanate, solid content concentration: 75% by mass ･Isocyanate crosslinking agent (ii): Tosoh Co., Ltd., product name "CORONATE L", a solution containing trihydroxymethylpropane-denatured methylphenyl diisocyanate, solid content concentration: 75% by mass ･Energy ray curing compound: Nippon Synthetic Chemical Industry Co., Ltd., product name "Shikou UT-4332", multifunctional urethane acrylate Photopolymerization initiator (i): bis(2,4,6-trimethylbenzyl)phenylphosphine oxide Photopolymerization initiator (ii): 1-hydroxycyclohexylphenyl ketone Phthalocyanine pigment

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

<Release material> Heavy-duty release film: Lintec Co., Ltd., product name "SP-PET382150", a release layer formed by a silicone release agent is provided on one side of the polyethylene terephthalate (PET) film, thickness: 38μm Light-duty release film: Lintec Co., Ltd., product name "SP-PET381031", a release layer formed by a silicone release agent is provided on one side of the PET film, thickness: 38μm

Production Example 1-1: Formation of Adhesive Layer (X1-A1) 0.74 mass parts of isocyanate crosslinking agent (i) were mixed with 100 mass parts of solid content of acrylic copolymer (A1) (solid content ratio), diluted with toluene, and uniformly stirred to prepare an adhesive composition (x-1-A1) with a solid content concentration (active ingredient concentration) of 25 mass%. Thereafter, the prepared adhesive composition (x-1-A1) was applied to the release surface of the light peeling film to form a coating film, and the coating film was dried at 100°C for 60 seconds to form an adhesive layer (X1-A1) with a thickness of 5μm.

Preparation Example 1-2: Formation of Adhesive Layer (X1-A2) Except that the acrylic copolymer (A1) was replaced with the acrylic copolymer (A2) and the amount of the isocyanate crosslinking agent (i) was changed to 4.76 parts by mass (solid content ratio) relative to 100 parts by mass of the solid content of the acrylic copolymer (A2), an adhesive composition (X-1-A2) having a solid content concentration (active ingredient concentration) of 25% by mass was prepared by the same method as in Preparation Example 1-1 to form an adhesive layer (X1-A2) having a thickness of 5 μm.

Preparation Example 1-3: Formation of Adhesive Layer (X1-A3) Except that the acrylic copolymer (A1) was replaced with the acrylic copolymer (A3) and the amount of the isocyanate crosslinking agent (i) was changed to 3.85 parts by mass (solid content ratio) relative to 100 parts by mass of the solid content of the acrylic copolymer (A3), an adhesive composition (X-1-A3) having a solid content concentration (active ingredient concentration) of 25% by mass was prepared by the same method as in Preparation Example 1-1 to form an adhesive layer (X1-A3) having a thickness of 5 μm.

Preparation Example 1-4: Formation of Adhesive Layer (X1-A4) Except that the acrylic copolymer (A1) was replaced with the acrylic copolymer (A4) and the amount of the isocyanate crosslinking agent (i) was changed to 15.8 parts by mass (solid content ratio) relative to 100 parts by mass of the solid content of the acrylic copolymer (A4), an adhesive composition (X-1-A4) having a solid content concentration (active ingredient concentration) of 25% by mass was prepared by the same method as Preparation Example 1-1 to form an adhesive layer (X1-A4) having a thickness of 5 μm.

Preparation Example 2: Formation of Adhesive Layer (X2) Add 4.2 parts by mass of energy-ray-curable compound, 0.74 parts by mass of isocyanate crosslinking agent (ii), and 1 part by mass of photopolymerization initiator (i) to 100 parts by mass of the solid content of the acrylic copolymer (A5) of the energy-ray-curable adhesive resin, dilute with toluene, and stir evenly to prepare an adhesive composition (x-2-A5) with a solid content concentration (active ingredient concentration) of 30% by mass. Furthermore, the prepared adhesive composition (X-2-A5) was applied on the release surface of the heavy release film to form a coating film, and the coating film was dried at 100° C. for 60 seconds to form an adhesive layer (X2-A5) with a thickness of 20 μm.

Preparation Example 3: Formation of a substrate laminate of a laminated thermally expandable substrate layer (Y1) and a non-thermally expandable substrate layer (Y2) (1) Preparation of a solvent-free resin composition (y-1a) A terminal isocyanate urethane prepolymer obtained by reacting an ester diol with isophorone diisocyanate (IPDI) is reacted with 2-hydroxyethyl acrylate to obtain a bifunctional urethane acrylate oligomer having a mass average molecular weight (Mw) of 5000. In addition, 40 mass % (solid ratio) of isobornyl acrylate (IBXA) and 20 mass % (solid ratio) of phenylhydroxypropyl acrylate (HPPA) as energy ray polymerizable monomers are mixed into 40 mass % (solid ratio) of the urethane acrylate oligomer synthesized above, and further 2.0 mass % (solid ratio) of a photopolymerization initiator (ii) and 0.2 mass % (solid ratio) of a phthalocyanine pigment as an additive are mixed with the total amount (100 mass %) of the urethane acrylate oligomer and the energy ray polymerizable monomer to prepare an energy ray curable composition. In addition, thermal expansion particles (i) are mixed into the energy ray curable composition to prepare a solvent-free resin composition (y-1a) containing no solvent. Furthermore, the content of the heat-expandable particles (i) was 20% by mass relative to the total amount (100% by mass) of the solvent-free resin composition (y-1a). (2) Formation of a substrate laminate of a laminated heat-expandable substrate layer (Y1) and a non-heat-expandable substrate layer (Y2) A PET film (manufactured by Toyobo Co., Ltd., product name "Cosmo Shine A4300", thickness: 50 μm) was used as the non-heat-expandable substrate layer (Y2), and the solvent-free resin composition (y-1a) was applied on one side of the PET film to form a coating film. Then, the coating was cured by irradiating ultraviolet rays using an ultraviolet irradiation device (manufactured by Eyegraphics Co., Ltd., product name "ECS-401GX") and a high-pressure mercury bulb (manufactured by Eyegraphics Co., Ltd., product name "H04-L41") at an illuminance of 160 mW/ ^cm2 and a light quantity of 500 mJ/ ^cm2 , thereby forming a 100 μm thick thermal expansion base layer (Y1) on a PET film as a non-thermal expansion base layer (Y2). The above illuminance and light quantity during ultraviolet irradiation are values measured using an illuminance and light quantity meter (manufactured by EIT, product name "UV Power Puck II").

Furthermore, the storage modulus E' of the thermal expansion base layer (Y1) at 23°C was 5.0×10 ⁸ Pa. Furthermore, the Young's modulus of the thermal expansion base layer (Y1) at 23°C was 330 MPa, and the Young's modulus of the non-thermal expansion base layer (Y2) at 23°C was 2000 MPa.

Example 1 The adhesive surface of the adhesive layer (X1-A1) formed in Manufacturing Example 1-1 is bonded to the surface of the thermal expansion substrate layer (Y1) of the substrate laminate formed in Manufacturing Example 3. Then, the adhesive surface of the adhesive layer (X2-A5) formed in Manufacturing Example 2 is bonded to the PET film surface of the substrate laminate. In this way, an adhesive sheet having the following structure is prepared. <Light release film>/<Adhesive layer (X1-A1), thickness: 5μm>/<Thermal expansion base layer (Y1), thickness: 100μm>/<Non-thermal expansion base layer (Y2), thickness: 50μm>/<Adhesive layer (X2-A5), thickness: 20μm>/<Heavy release film>

Example 2 Except for using the adhesive layer (X1-A2) formed in Example 1-2, an adhesive sheet having the following structure is prepared in the same manner as in Example 1. <Light peeling film>/<Adhesive layer (X1-A2), thickness: 5μm>/<Thermal expansion base layer (Y1), thickness: 100μm>/<Non-thermal expansion base layer (Y2), thickness: 50μm>/<Adhesive layer (X2-A5), thickness: 20μm>/<Heavy peeling film>

Comparative Example 1 Except for using the adhesive layer (X1-A3) formed in Manufacturing Example 1-3, an adhesive sheet having the following structure is prepared in the same manner as in Example 1. <Light peeling film>/<Adhesive layer (X1-A3), thickness: 5μm>/<Thermal expansion base layer (Y1), thickness: 100μm>/<Non-thermal expansion base layer (Y2), thickness: 50μm>/<Adhesive layer (X2-A5), thickness: 20μm>/<Heavy peeling film>

Comparative Example 2 Except for using the adhesive layer (X1-A4) formed in Manufacturing Example 1-4, an adhesive sheet having the following structure is prepared in the same manner as in Example 1. <Light peeling film>/<Adhesive layer (X1-A4), thickness: 5μm>/<Thermal expansion base layer (Y1), thickness: 100μm>/<Non-thermal expansion base layer (Y2), thickness: 50μm>/<Adhesive layer (X2-A5), thickness: 20μm>/<Heavy peeling film>

[Evaluation of initial adhesion of adhesive layer (X1)] The light peeling film of the adhesive sheets prepared in Examples 1 and 2 and Comparative Examples 1 and 2 was removed, and the adhesive surface of the exposed adhesive layer (X1) was attached to the alkaline lime glass plate of the adherend by a roller weighing 2kg and then left to stand for 20 minutes in an environment of 23℃ and 50%RH (relative humidity) to serve as the test sample. Furthermore, a universal tensile tester (Orientec Co., Ltd., model: Tensilon RTC-1210A) was used to measure the adhesion of the test sample at 23°C in an environment of 23°C and 50% RH (relative humidity) based on JIS Z0237:2000 and using a 180° peeling method at a tensile speed of 300 mm/min. The initial adhesion of the test sample was measured twice, and the average value was calculated. Furthermore, it was confirmed that the adhesive layer (X1-A1, X1-A2, X1-A3, and X1-A4) of any of the adhesive sheets of Examples 1 and 2 and Comparative Examples 1 and 2 was also adhered to the extent that the alkali-lime glass plate of the adhered body would not peel off due to its own weight.

[Evaluation of self-peeling property] Prepare two 30mm×30mm×1.1mm alkali-lime glass plates. Hereinafter, the two alkali-lime glass plates are referred to as "glass plate G1" and "glass plate G2", respectively. The adhesive sheet prepared in Example 1-2 and Comparative Example 1-2 was cut into 30mm×30mm, and the light peeling film was removed from the adhesive layer (X1-A1, X1-A2, X1-A3 and X1-A4) on the side of the thermal expansion base material layer (Y1) of the cut adhesive sheet, and the glass plate G1 was attached. Next, the heavy release film was removed from the adhesive layer (X2-A5) on the non-thermally expansive substrate layer (Y2) side, and after the glass plate G2 was attached, a vacuum laminating machine (Nikko-materials Co., Ltd., product name "V-130") was used to spray at 60°C and 0.2MPa for 30 seconds to prepare a test sample. The test sample was placed on a hot plate and heated for 5 minutes at 100°C, which is above the expansion start temperature of the thermally expansive particles. The test sample was placed on the hot plate so that the glass plate G2 side was in contact with the hot plate and the adhesive sheet side was not in contact with the hot plate. After heating at 100°C for 5 minutes, the peeling state of the self-adhesive sheet of the glass plate G1 was visually confirmed, and the self-peeling property was evaluated according to the following criteria. A: The self-adhesive sheet of the entire glass plate G1 was peeled off. F: The self-adhesive sheet of one part or all of the glass plate G1 was not peeled off.

[Evaluation of Young's modulus of adhesive layer (X1)] (1) Preparation of evaluation samples Adhesive layers (X1-A1), (X1-A2), (X1-A3) and (X1-A4) with a thickness of 400 μm and PET-based release films (manufactured by Lintec Co., Ltd., product name "SP-PET38 1031", thickness: 38 μm) attached to both sides were prepared. (2) Tensile test The prepared evaluation samples were cut into 15 mm × 140 mm pieces, and labels for film stretching were attached to the 20 mm portions at both ends to prepare dumbbell-shaped samples of 15 mm × 100 mm. Furthermore, the tension was performed at a speed of 200 mm/min using Autograph AG-100N XPlus manufactured by Shimadzu Corporation, and the Young's modulus at that time was measured.

The evaluation results are shown in Table 1.

From Table 1, it can be seen that in the adhesive sheets of Examples 1 and 2, the Young's modulus of the adhesive layer (X1) at 23°C is less than 5.0 MPa, and the Young's modulus of the non-thermally expansive base layer (Y2) at 23°C is higher than the Young's modulus of the adhesive layer (X1) at 23°C, so the self-peeling property is good. In contrast, in the adhesive sheets of Comparative Examples 1 and 2, the Young's modulus of the adhesive layer (X1) at 23°C is greater than 5.0 MPa, so the self-peeling property is poor.

1a, 1b, 2a, 2b: Adhesive sheet 10, 10a, 10b: Stripping material 3: Support 4: Laser irradiation device 5: Modified area 6: Grinding machine 7: Thermosetting film 8: Support sheet W: Semiconductor wafer W1: Surface of semiconductor wafer and semiconductor chip W2: Inner surface of semiconductor wafer and semiconductor chip CP: Semiconductor chip

[FIG. 1] is a cross-sectional view showing an example of the structure of the adhesive sheet of the present invention. [FIG. 2] is a cross-sectional view showing another example of the structure of the adhesive sheet of the present invention. [FIG. 3] is a cross-sectional view showing an example of the steps of the method for manufacturing a semiconductor device of the present invention. [FIG. 4] is a cross-sectional view showing an example of the steps of the method for manufacturing a semiconductor device of the present invention. [FIG. 5] is a cross-sectional view showing an example of the steps of the method for manufacturing a semiconductor device of the present invention. [FIG. 6] is a cross-sectional view showing an example of the steps of the method for manufacturing a semiconductor device of the present invention. [FIG. 7] is a cross-sectional view showing an example of the steps of the method for manufacturing a semiconductor device of the present invention. [FIG. 8] is a cross-sectional view showing an example of the steps of the method for manufacturing a semiconductor device of the present invention. [Fig. 9] is a cross-sectional view illustrating an example of the steps of the method for manufacturing the semiconductor device of the present invention.

1a,1b: Adhesive sheet

10: Peeling material

(X1): Adhesive layer

(Y1): Thermal expansion base layer

(Y2): Non-thermal expansion base layer

Claims (15)

An adhesive sheet has a laminated structure in which an adhesive layer (X1), a heat-expandable base layer (Y1) containing heat-expandable particles, and a non-heat-expandable base layer (Y2) are sequentially arranged. The Young's modulus of the adhesive layer (X1) at 23°C is modulus) is 5.0 MPa or less, the Young's modulus of the non-thermally expansive base layer (Y2) at 23°C is higher than the Young's modulus of the adhesive layer (X1) at 23°C, the thermally expansive base layer (Y1) is non-adhesive, the Young's modulus of the thermally expansive base layer (Y1) at 23°C is 100 MPa or more and 600 MPa or less, the Young's modulus of the non-thermally expansive base layer (Y2) at 23°C is 700 MPa or more, and at the expansion start temperature (t) of the thermally expansive particles, the storage modulus E'(t) of the thermally expansive base layer (Y1) is 1.0×10 ³ Pa or more. As in claim 1, the adhesive sheet, wherein the thickness of the adhesive layer (X1) at 23°C is 3-10 μm. The adhesive sheet of claim 1 or 2, wherein the product of the Young's modulus (unit: MPa) of the adhesive layer (X1) at 23°C and the thickness (unit: μm) of the adhesive layer (X1) at 23°C is 0.3 to 50. The adhesive sheet as claimed in claim 1 or 2, wherein the adhesive layer (X1) is a layer formed by an adhesive composition (x-1) comprising an acrylic resin and an isocyanate crosslinking agent. As in claim 4, the adhesive sheet, wherein the aforementioned isocyanate crosslinking agent comprises an isocyanurate type variant having an isocyanurate ring. As in the adhesive sheet of claim 1 or 2, the Young's modulus of the aforementioned non-thermally expansive substrate layer (Y2) at 23°C is 700 MPa or more. As in the adhesive sheet of claim 1 or 2, wherein the aforementioned non-thermally expandable substrate layer (Y2) is a polyethylene terephthalate film. The adhesive sheet of claim 1 or 2, wherein the non-thermally expandable substrate layer (Y2) further has an adhesive layer (X2) on the surface opposite to the laminated surface of the thermally expandable substrate layer (Y1). As in claim 1 or 2, the adhesive sheet, wherein the expansion start temperature (t) of the aforementioned heat-expandable particles is above 50°C and below 125°C. As in claim 8, the adhesive sheet, wherein the expansion start temperature (t) of the aforementioned heat-expandable particles is above 50°C and below 125°C. As in the adhesive sheet of claim 10, the adhesive layer (X2) is an adhesive layer whose adhesive force is reduced by curing by irradiating energy rays. A method for manufacturing a semiconductor device, comprising the steps of attaching an inspection object to an adhesive sheet as in any one of claims 1 to 11, and subjecting the inspection object to one or more of the processing and inspection, and then heating the adhesive sheet to a temperature above the expansion start temperature (t) of the thermally expandable particles in the adhesive sheet. A method for manufacturing a semiconductor device, which uses an adhesive sheet as claimed in claim 10 or 11, and comprises the following steps 1A to 3A, the following first separation step and the following second separation step, step 1A: attaching a processing object to the adhesive layer (X2) of the aforementioned adhesive sheet, and attaching a support to the adhesive layer (X1) of the aforementioned adhesive sheet, step 2A: applying one or more selected from grinding and individualization treatments to the aforementioned processing object Step 3A: a step of attaching a thermosetting film having thermosetting properties to the surface of the object to be processed which is opposite to the adhesive layer (X2), the first separation step: heating the adhesive sheet to a temperature above the expansion start temperature (t) and below 125°C, and separating the adhesive layer (X1) from the support, the second separation step: separating the adhesive layer (X2) from the object to be processed. A method for manufacturing a semiconductor device, which uses an adhesive sheet as claimed in claim 10 or 11, and comprises the following steps 1B to 3B, the following first separation step, and the following second separation step, step 1B: attaching a processing object to the adhesive layer (X1) of the aforementioned adhesive sheet, attaching a support to the adhesive layer (X2) of the aforementioned adhesive sheet, step 2B: subjecting the aforementioned processing object to one or more selected from grinding and individualization treatments Step 3B: a step of attaching a thermosetting film having thermosetting properties to the surface of the object to be processed which is opposite to the adhesive layer (X1), the first separation step: heating the adhesive sheet to a temperature above the expansion start temperature (t) and below 125°C, and separating the adhesive layer (X1) from the object to be processed, the second separation step: a step of separating the adhesive layer (X2) from the support. A method for manufacturing a semiconductor device as claimed in claim 13 or 14, wherein the adhesive sheet as claimed in claim 11 is used, and the second separation step includes a step of hardening the adhesive layer (X2) by irradiating the adhesive layer (X2) with energy rays.

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