WO2023286619A1

WO2023286619A1 - Adhesive sheet

Info

Publication number: WO2023286619A1
Application number: PCT/JP2022/026242
Authority: WO
Inventors: 拓三由藤; 和通加藤; 航大中尾
Original assignee: 日東電工株式会社
Priority date: 2021-07-13
Filing date: 2022-06-30
Publication date: 2023-01-19
Also published as: TW202338049A; KR20240032112A; CN117642476A; DE112022002949T5; JPWO2023286619A1

Abstract

The present invention provides an adhesive sheet having a satisfactory balance of reduced adhesive residue when peeling and excellent conformability to the surface shape of an adherend. Provided is an adhesive sheet comprising a base material and an adhesive layer that is disposed on at least one side of the base material. The indentation hardness H1 of the surface of the adhesive layer of the adhesive sheet is 0.10-0.50 MPa, and, in a cross-section of the adhesive sheet, the indentation hardness H2 measured at a position 4 μm from the base material in the direction of the surface of the adhesive layer is 0.001-0.090 MPa.

Description

Adhesive sheet

The present invention relates to an adhesive sheet. This application claims priority based on Japanese Patent Application No. 2021-115926 filed on July 13, 2021, the entire contents of which are incorporated herein by reference.

　In the manufacture of semiconductor parts including semiconductor chips, the semiconductor chips are sometimes sealed with resin in order to prevent damage to the semiconductor chips and expand metal wiring. In the resin encapsulation process, the resin encapsulation of a semiconductor chip may be performed on an adhesive sheet from the viewpoint of workability. For example, a plurality of semiconductor chips are arranged on an adhesive layer of an adhesive sheet as a temporary fixing material, and the semiconductor chips are collectively sealed on the adhesive layer. After that, in a predetermined post-process, the pressure-sensitive adhesive sheet is peeled off from the structure including the sealing resin and the semiconductor chip.

Japanese Patent Application Publication No. 2001-308116 Japanese Patent Application Publication No. 2001-313350

The pressure-sensitive adhesive sheet used in the above process must not leave any adhesive residue (residual pressure-sensitive adhesive) on the structure when the pressure-sensitive adhesive sheet is peeled off from the structure containing the sealing resin and the semiconductor chip. is required. In order to suppress the adhesive residue, the adhesive layer on which the semiconductor chip is arranged in the adhesive sheet is generally made of an adhesive having a very high elastic modulus. However, since there may be steps on the surface of the semiconductor chip due to pre-formed metal wiring or the like, if the adhesive layer has a high elastic modulus, the adhesive does not sufficiently adhere to the steps on the chip surface, resulting in The sealing resin tends to enter the interface between the adhesive and the adhesive.

The present invention was created in view of the above circumstances, and provides a pressure-sensitive adhesive sheet that achieves both suppression of adhesive residue during peeling and good conformability to the surface shape of an adherend in a well-balanced manner. for the purpose.

The adhesive sheet provided by this specification comprises a substrate and an adhesive layer arranged on at least one side of the substrate. The pressure-sensitive adhesive sheet has an indentation hardness H1 of the surface of the pressure-sensitive adhesive layer of 0.10 MPa or more and 0.50 MPa or less in the indentation hardness measurement using a nanoindenter, and from the base material in the cross section of the pressure-sensitive adhesive sheet The pressure-sensitive adhesive layer has an indentation hardness H2 of 0.001 MPa or more and 0.090 MPa or less measured at a position 4 μm away from the surface side of the pressure-sensitive adhesive layer. When the indentation hardness H1 measured with the surface of the pressure-sensitive adhesive layer as the measurement position (hereinafter also referred to as "measurement position A") is 0.10 MPa or more, it is possible to suppress adhesive residue at the time of peeling. Further, the inside of the measurement position A (substrate side), specifically, a position at a distance of 4 μm from the substrate to the surface side of the adhesive layer in the cross section of the adhesive sheet (hereinafter, also referred to as “measurement position B”) ) is 0.090 MPa or less, the conformability to the surface shape of the adherend can be enhanced. Therefore, the pressure-sensitive adhesive sheet having the indentation hardnesses H1 and H2 within the above ranges can achieve both suppression of adhesive residue at the time of peeling and good conformability to the surface shape of the adherend in a well-balanced manner.

In some aspects, the ratio (H2/H1) of the indentation hardness H2 [MPa] to the indentation hardness H1 [MPa] is 0.002 or more and 0.90 or less. According to the pressure-sensitive adhesive sheet in which the indentation hardness H2 at the measurement position B (inside) is 0.90 times or less as large as the indentation hardness H1 at the measurement position A (surface), it is possible to satisfactorily achieve both suppression of adhesive residue and surface conformability. be able to.

In some aspects, in stringiness evaluation using a nanoindenter, the surface stringiness D1 of the pressure-sensitive adhesive layer is 50 nm or more and 500 nm or less. A stringiness D1 of 500 nm or less on the surface (measurement position A) of the pressure-sensitive adhesive layer is advantageous from the viewpoint of suppressing adhesive residue. In the stringiness evaluation, the stringiness D2 measured at a position (measurement position B) at a distance of 4 μm from the substrate to the surface side of the pressure-sensitive adhesive layer in the cross section of the pressure-sensitive adhesive sheet is 150 nm or more and 1000 nm or less. is preferred. A pressure-sensitive adhesive layer having a stringiness D2 within the above range is likely to achieve good surface conformability.

In some embodiments, the ratio (D2/D1) of the stringiness D2 [nm] to the stringiness D1 [nm] is 0.3 or more and 20.0 or less. A pressure-sensitive adhesive sheet having a ratio (D2/D1) within the above range tends to favorably achieve both suppression of adhesive residue and surface conformability.

In some embodiments, the initial thickness T0 [μm] of the adhesive layer and the thickness of the adhesive layer after dropping 4-t-butylphenylglycidyl ether on the surface of the adhesive layer and allowing it to stand for 1 minute The difference from the thickness T1 [μm] (T1−T0; hereinafter also referred to as “thickness variation”) is 20 μm or less. A pressure-sensitive adhesive sheet having a pressure-sensitive adhesive layer with a small amount of thickness change can be used, for example, in a mode of use in which a semiconductor chip is placed on the pressure-sensitive adhesive layer and the semiconductor chip is sealed with a resin. It is preferable because it is less likely to cause a step (standoff) with the resin.

The pressure-sensitive adhesive sheet according to some aspects is measured using a thermomechanical analyzer (TMA) under the conditions of a measurement environment temperature of 23 ° C., an indentation load of 0.01 N, and an indentation load time of 60 minutes. The amount of sinking of the penetrating probe from the surface is 3.50 μm or more and 20.0 μm or less. According to the pressure-sensitive adhesive sheet having the amount of sinking in the above range, for example, in a mode of use in which a semiconductor chip is placed on the pressure-sensitive adhesive layer and the semiconductor chip is sealed with resin, the surface shape of the semiconductor chip is affected. It is possible to achieve both followability and suppression of embedding of the semiconductor chip in the adhesive sheet in a well-balanced manner.

In some aspects of the adhesive sheet disclosed herein, the adhesive layer has a thickness of 5 μm or more and 110 μm or less. According to the pressure-sensitive adhesive layer having the thickness described above, the effect of different characteristics between the measurement position A and the measurement position B can be suitably exhibited.

In some aspects, the substrate is a substrate film made of a resin material having a glass transition temperature (Tg) of 25°C or higher. The pressure-sensitive adhesive sheet having the above-described pressure-sensitive adhesive layer on the base film is used in a mode of use in which, for example, a step of placing a semiconductor chip on the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet and sealing the semiconductor chip with a resin is performed. It is possible to prevent the semiconductor chip from being embedded in the adhesive sheet even if it is heated during the process, and to prevent a step (standoff) between the semiconductor chip and the sealing resin.

The pressure-sensitive adhesive sheet according to some aspects has an adhesive force to polyethylene terephthalate (PET) film of 0.05 N/20 mm or more and 1.00 N/20 mm or less. Within such a range, the adherend (for example, semiconductor chip) can be preferably fixed, and the load applied to the adherend when the pressure-sensitive adhesive sheet is peeled off can be suppressed.

In some aspects, the anchoring force of the pressure-sensitive adhesive layer to the substrate measured at 23°C after heating the pressure-sensitive adhesive sheet at 150°C for 1 hour is 4.00 N/20 mm or more. The pressure-sensitive adhesive sheet exhibiting the above-described anchoring force can be heated during the step of placing a semiconductor chip on the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet and encapsulating the semiconductor chip with a resin, for example. , which is preferable because adhesive residue can be suppressed in the subsequent peeling process.

In some aspects, the pressure-sensitive adhesive that constitutes at least the surface of the pressure-sensitive adhesive layer is an acrylic pressure-sensitive adhesive that uses an acrylic polymer as a base polymer. The technology disclosed herein can be preferably practiced in the form of a pressure-sensitive adhesive sheet having at least a surface (adhesive surface) comprising a pressure-sensitive adhesive layer made of an acrylic pressure-sensitive adhesive.

In some aspects, the acrylic polymer has an SP value of 18.0 to 20.0. By configuring the adhesive surface with an acrylic adhesive whose base polymer is an acrylic polymer having an SP value within the above range, it is easy to achieve the indentation hardness H1 within the above range and, for example, a semiconductor chip can be placed on the adhesive surface. Even in a mode of use in which a step of arranging and sealing the semiconductor chip with resin is carried out, it is easy to suppress an excessive increase in the adhesive force to the sealing resin.

In some aspects of the pressure-sensitive adhesive sheet disclosed herein, the pressure-sensitive adhesive layer includes a layer A constituting the surface of the pressure-sensitive adhesive layer and a layer disposed between the layer A and the base material. and the B layer adjacent to the . The pressure-sensitive adhesive sheet disclosed herein can be preferably implemented in a mode comprising a pressure-sensitive adhesive layer having a structure including layer A (surface layer) and layer B (undercoat layer).

The thickness L1 of the layer A is preferably, for example, 1 μm or more and 10 μm or less. According to the A layer having such a thickness, it is easy to favorably achieve both suppression of adhesive residue and surface conformability.
It is preferable that the thickness L2 of the layer B is, for example, 4 μm or more and 100 μm or less. According to the B layer having such a thickness, it is easy to favorably achieve both suppression of adhesive residue and surface conformability.
The ratio (L2/L1) of the thickness L2 [μm] of the layer B to the thickness L1 [μm] of the layer A is preferably 1.0 to 100.0.

In some aspects, the T2 relaxation time ( _T2s ) of the S component by pulse NMR of the A layer is 45 μsec or less, and the T2 relaxation _time ( _T2s ) of the S component by _pulse NMR of the B layer is 45 μsec. longer. According to the pressure-sensitive adhesive sheet having the pressure-sensitive adhesive layer containing the A layer and the B layer satisfying the above relaxation time (T _2s ), it is possible to achieve both suppression of component migration between the pressure-sensitive adhesive layer and the encapsulating resin and surface conformability. Cheap.

In some aspects, the layer A is crosslinked with an epoxy-based cross-linking agent, and the layer B is cross-linked with an isocyanate-based cross-linking agent. The pressure-sensitive adhesive sheet disclosed herein can be preferably implemented in a mode comprising a pressure-sensitive adhesive layer having such a configuration.

In some aspects of the pressure-sensitive adhesive sheet disclosed herein, the pressure-sensitive adhesive sheet comprises the base material, the pressure-sensitive adhesive layer (first pressure-sensitive adhesive layer) disposed on one side of the base material, and the base material. and a second pressure-sensitive adhesive layer disposed on the opposite side of the pressure-sensitive adhesive layer. The pressure-sensitive adhesive sheet having such a structure can be fixed on an appropriate carrier by using the second pressure-sensitive adhesive layer, for example, and the resin sealing step can be performed on the first pressure-sensitive adhesive layer in that state. Easy to use.

In some aspects, at least the surface of the second adhesive layer is composed of an adhesive containing thermally expandable microspheres. The pressure-sensitive adhesive sheet of this aspect can easily release the bond between the second pressure-sensitive adhesive layer and the adherend by heating the heat-expandable microspheres at appropriate timing as necessary to expand the heat-expandable microspheres. preferable.

Any appropriate combination of the elements described in this specification may also be included in the scope of the invention for which patent protection is sought by this patent application.

1 is a cross-sectional view schematically showing the configuration of a pressure-sensitive adhesive sheet according to one embodiment; FIG. (i) to (iv) are explanatory diagrams showing an example of a semiconductor chip resin encapsulation process performed using the adhesive sheet shown in FIG. FIG. 3 is a cross-sectional view schematically showing the configuration of a pressure-sensitive adhesive sheet according to another embodiment; FIG. 3 is a cross-sectional view schematically showing the configuration of a pressure-sensitive adhesive sheet according to another embodiment; It is a schematic diagram for demonstrating the definition of stringiness.

Preferred embodiments of the present invention are described below. Matters other than those specifically referred to in this specification that are necessary for the implementation of the present invention are applicable based on the teaching of the implementation of the invention described in this specification and the common general knowledge at the time of filing. understandable to traders. The present invention can be implemented based on the contents disclosed in this specification and common general technical knowledge in the field.
In the drawings below, members and portions having the same function may be denoted by the same reference numerals, and redundant description may be omitted or simplified. In addition, the embodiments described in the drawings are schematics for the purpose of clearly explaining the present invention and do not necessarily represent the size or scale of the products actually provided.

In this specification, the "base polymer" of the pressure-sensitive adhesive refers to the main component of the rubber-like polymer contained in the pressure-sensitive adhesive, and is not to be construed as being limited to anything other than this. The term "rubber-like polymer" refers to a polymer that exhibits rubber elasticity in a temperature range around room temperature. In this specification, the term "main component" refers to a component contained in an amount exceeding 50% by weight unless otherwise specified.
In this specification, the term "acrylic polymer" refers to a polymer containing monomer units derived from a monomer having at least one (meth)acryloyl group in one molecule as monomer units constituting the polymer. Hereinafter, a monomer having at least one (meth)acryloyl group in one molecule is also referred to as "acrylic monomer". Accordingly, an acrylic polymer in this specification is defined as a polymer containing monomeric units derived from an acrylic monomer. A typical example of an acrylic polymer is a polymer in which the acrylic monomer accounts for more than 50% by weight (preferably more than 70% by weight, for example more than 90% by weight) of all the monomers used in the synthesis of the acrylic polymer. be done. Hereinafter, a monomer used for synthesizing a polymer is also referred to as a monomer component constituting the polymer.
Moreover, in this specification, "(meth)acryloyl" is meant to comprehensively refer to acryloyl and methacryloyl. Similarly, "(meth)acrylate" is a generic term for acrylate and methacrylate, and "(meth)acrylic" is generic for acrylic and methacrylic. Therefore, the concept of an acrylic monomer as used herein can include both a monomer having an acryloyl group (acrylic monomer) and a monomer having a methacryloyl group (methacrylic monomer).

<Outline of adhesive sheet>
The pressure-sensitive adhesive sheet disclosed herein can be suitably used as a temporary fixing material when resin-sealing a semiconductor chip. More specifically, the pressure-sensitive adhesive sheet of the present invention is obtained by arranging semiconductor chips on the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet, covering the semiconductor chips with a sealing resin (usually an epoxy resin), and curing the sealing resin. By doing so, it can be used as a temporary fixing material for the semiconductor chip when the semiconductor chip is resin-sealed. After the semiconductor chip is resin-encapsulated, in the case of predetermined post-processes (for example, back grinding of the encapsulation resin, pattern formation, bump formation, chip formation (cutting)), the adhesive sheet is used to separate the encapsulation resin and the semiconductor. It can be peeled off from a structure that includes the chip. The epoxy equivalent of the sealing resin is, for example, 50 g/eq to 500 g/eq.

FIG. 1 is a schematic cross-sectional view showing one embodiment of the adhesive sheet disclosed here. The adhesive sheet 100 includes a substrate 10 and an adhesive layer (first adhesive layer) 20 arranged on one side of the substrate 10 . This pressure-sensitive adhesive sheet 100 has an indentation hardness H1 of 0.10 MPa or more at the surface of the pressure-sensitive adhesive layer (first pressure-sensitive adhesive layer) 20, that is, at the measurement position A (arrow A in FIG. 1). The indentation hardness H2 measured at a position (measurement position B indicated by arrow B in FIG. 1) at a distance of 4 μm from the substrate 10 to the surface side of the adhesive layer 20 in the cross section is 0.09 MPa or less.

The adhesive sheet 100 can be used for resin encapsulation of semiconductor chips, for example, as shown in FIG. First, a plurality of semiconductor chips 1 are adhered onto the adhesive layer (first adhesive layer) of the adhesive sheet 100 (step (i)). (Step (ii)), by curing the semi-cured material 2', the semiconductor chip 1 is sealed with the sealing resin 2 (Step (iii)). The semi-cured material 2' can be formed using a composition containing, for example, a naphthalene-type bifunctional epoxy resin (epoxy equivalent: 144). Thereafter, during a predetermined post-process, the adhesive sheet 100 is peeled off from the structure 50 including the semiconductor chip 1 and the sealing resin 2 (process (iv)).

Since the pressure-sensitive adhesive sheet disclosed here has a pressing hardness H1 of 0.10 MPa or more at the measurement position A, it is difficult for adhesive to remain on the structure 50 in step (iv) shown in FIG. In addition, since the indentation hardness H2 at the measurement position B is 0.09 MPa or less inside the adhesive layer, specifically, the adhesive layer has a surface shape of the adherend (for example, the adhesive of the semiconductor chip 1 (steps due to metal wiring, etc. that may exist on the layer side surface) can be satisfactorily followed, and the occurrence of defects (mold flash) in which the sealing resin 2 enters the interface between the adhesive sheet and the semiconductor chip 1 is prevented. can do.

FIG. 3 is a schematic cross-sectional view showing another embodiment of the adhesive sheet disclosed here. In the pressure-sensitive adhesive sheet 200, the pressure-sensitive adhesive layer 20 in the pressure-sensitive adhesive sheet 100 shown in FIG. and a B layer 24 adjacent to the substrate 10 . According to the pressure-sensitive adhesive layer 20 having such a structure, the indentation hardness H1 at the measurement position A and the indentation hardness H2 at the measurement position B can be easily adjusted to appropriate ranges. The pressure-sensitive adhesive sheet disclosed herein can be preferably implemented in such a manner that the pressure-sensitive adhesive layer 20 including the A layer 22 and the B layer 24 is provided on at least one side of the substrate 10 .

FIG. 4 is a schematic cross-sectional view showing another embodiment of the adhesive sheet disclosed here. The adhesive sheet 300 further includes a second adhesive layer 30 on the back side of the base material 10 (the side opposite to the adhesive layer 20). That is, the adhesive sheet 300 includes the adhesive layer 20, the base material 10, and the second adhesive layer 30 in this order. By providing the second adhesive layer 30, the adhesive sheet 300 can be easily fixed to the carrier by attaching the second adhesive layer 30 side to the carrier when resin sealing is performed on the carrier. can be done.

In some embodiments, at least the surface of the second adhesive layer is composed of an adhesive containing heat-expandable microspheres. When the pressure-sensitive adhesive layer containing such heat-expandable microspheres is heated to a predetermined temperature or higher, the heat-expandable microspheres are expanded to cause unevenness on the surface of the pressure-sensitive adhesive layer, thereby reducing the adhesive force. or can be extinguished. By forming at least the surface of the second pressure-sensitive adhesive layer with a pressure-sensitive adhesive containing heat-expandable microspheres, when fixing the pressure-sensitive adhesive sheet (for example, fixing to a carrier) via the second pressure-sensitive adhesive layer, Adhesiveness is developed, and when the adhesive sheet is peeled off (for example, when peeled off from the carrier), the adhesive strength is reduced or lost by heating, thereby exhibiting good peelability. Between the pressure-sensitive adhesive layer containing heat-expandable microspheres and the substrate, an elastic intermediate layer (which may be a pressure-sensitive adhesive layer) containing no or a small amount of heat-expandable microspheres is disposed. good too.

(indentation hardness)
The indentation hardness H1 of the pressure-sensitive adhesive sheet disclosed herein is suitably 0.10 MPa or more (for example, more than 0.10 MPa), preferably 0.12 MPa or more, from the viewpoint of suppressing adhesive residue. In some embodiments, the indentation hardness H1 may be 0.15 MPa or higher, 0.18 MPa or higher, or 0.20 MPa or higher. An adhesive layer with a high indentation hardness H1 is generally used in a mode of use in which a semiconductor chip is placed on the adhesive layer and the semiconductor chip is sealed with a resin. This tends to be advantageous from the viewpoint of suppressing a step (standoff) that may occur at the boundary. Also, the indentation hardness H1 is suitably 0.50 MPa or less, preferably 0.40 MPa or less. In some embodiments, the indentation hardness H1 may be, for example, 0.30 MPa or less, or 0.30 MPa or less, from the viewpoint of facilitating the development of adhesion to the adherend surface and appropriate tackiness on the pressure-sensitive adhesive layer surface. It may be 28 MPa or less, 0.25 MPa or less, 0.23 MPa or less, or 0.21 MPa or less.

The indentation hardness H2 of the pressure-sensitive adhesive sheet disclosed herein is suitably lower than the indentation hardness H1, and is preferably 0.090 MPa or less from the viewpoint of improving the conformability to the surface shape of the adherend. From the viewpoint of obtaining higher conformability, in some embodiments, the indentation hardness H2 may be 0.080 MPa or less, 0.060 MPa or less, or 0.050 MPa or less. The lower limit of the indentation hardness H2 is not particularly limited, and may be, for example, 0.001 MPa or more. From the viewpoint of preventing cohesive failure inside the pressure-sensitive adhesive layer, in some embodiments, the indentation hardness H2 is suitably 0.005 MPa or more, preferably 0.010 MPa or more, and 0.005 MPa or more. It may be 030 MPa or more, 0.040 MPa or more, 0.050 MPa or more, or 0.060 MPa or more.

The ratio (H2/H1) of the indentation hardness H2 [MPa] to the indentation hardness H1 [MPa] is, for example, suitably 0.90 or less, preferably 0.70 or less, and 0 It may be 0.50 or less, 0.40 or less, or 0.30 or less. The ratio (H2/H1) is, for example, suitably 0.002 or more, preferably 0.005 or more, and more preferably 0.01 or more. A pressure-sensitive adhesive sheet in which the ratio (H2/H1) is within such a range tends to achieve both suppression of adhesive residue and surface conformability in a well-balanced manner.

(Stringiness)
In the pressure-sensitive adhesive sheet disclosed herein, the range of the stringiness D1 at the measurement position A is not particularly limited, and may be, for example, 800 nm or less. In some embodiments, the stringiness D1 is suitably 500 nm or less, preferably 300 nm or less, may be 250 nm or less, may be 200 nm or less, and may be 150 nm from the viewpoint of improving the adhesive residue prevention property. It can be below. In addition, from the viewpoint of exhibiting appropriate tackiness on the surface of the pressure-sensitive adhesive layer and, for example, facilitating placement of semiconductor chips on the surface of the pressure-sensitive adhesive layer, the stringiness D1 is suitably 50 nm or more, and 80 nm. 100 nm or more, or 120 nm or more.

In the pressure-sensitive adhesive sheet disclosed herein, the range of the stringiness D2 at the measurement position B is not particularly limited, and may be, for example, 100 nm or more. , and more preferably 200 nm or more. In some embodiments, the stringiness D2 may be 300 nm or greater, 400 nm or greater, or 500 nm or greater. Further, the stringiness D2 may be, for example, 2500 nm or less, preferably 1500 nm or less from the viewpoint of preventing cohesive failure inside the pressure-sensitive adhesive layer, more preferably 1000 nm or less, and may be 800 nm or less. , 600 nm or less.

The ratio (D2/D1) of the stringiness D2 [nm] to the stringiness D1 [nm] may be, for example, 0.3 or more, 0.5 or more, or 1.0 or more. In some embodiments, the ratio (D2/D1) is preferably greater than 1.0 (eg, 1.2 or greater), may be 2.5 or greater, may be 3.5 or greater, or may be 5.0 or greater. It's okay. The ratio (D2/D1) is, for example, suitably 20.0 or less, advantageously 15.0 or less, preferably 10.0 or less, and 8.0 or less. , 7.0 or less, or 6.0 or less. A pressure-sensitive adhesive sheet in which the ratio (D2/D1) is within the range defined by the combination of any of the upper and lower limits described above tends to achieve both suppression of adhesive residue and surface conformability in a well-balanced manner.

The indentation hardnesses H1 and H2 and the stringiness D1 and D2 are measured by using a nanoindenter to vertically indent the indenter to a predetermined depth from the surface of the sample at a predetermined measurement position and then pulling it out. Calculated from the load (indentation) - unload (pull out) curve obtained by plotting the transition of the load (vertical axis) applied to the indenter against the displacement (horizontal axis) of the indenter based on the surface of the above sample. . Here, in the measurement of the indentation hardness H1 and the stringiness D1, the surface of the pressure-sensitive adhesive layer is the measurement position (measurement position A). In the measurement of the indentation hardness H2 and the stringiness D2, the measurement position (measurement position B) is a position at a distance of 4 μm from the base material to the surface side of the pressure-sensitive adhesive layer in the cross section of the pressure-sensitive adhesive sheet.

The indentation hardness [MPa] is obtained by dividing the maximum load (Pmax) [μN] of the load curve when the indenter is pushed in to a predetermined depth by the projected contact area (A) of the indenter. Hardness [MPa]=Pmax/A; The indentation hardness can be controlled within the above range by appropriately selecting the structure of the pressure-sensitive adhesive layer and the composition of the pressure-sensitive adhesive constituting the pressure-sensitive adhesive layer (for example, composition of base polymer, degree of cross-linking, type of cross-linking agent, etc.). can be

The stringiness [nm] is defined as the amount of displacement when the unloading curve becomes zero load on the negative displacement side, as schematically shown in FIG. The stringiness can be set within the above range by appropriately selecting the composition of the adhesive constituting the adhesive layer (for example, the composition of the base polymer, the degree of cross-linking, the type of cross-linking agent, etc.).

Specifically, indentation hardness and stringiness are measured under the following conditions using a nanoindenter manufactured by Hysitron under the product name "Triboindenter TI-950" or its equivalent.
[Measurement condition]
Indenter used: Berkovich (triangular pyramid) type diamond indenter Measurement method: Single indentation measurement Measurement temperature: Room temperature (25°C)
Indentation depth setting: 800 nm at measurement position A,
1000 nm at measurement position B
Pushing speed: 200 nm/sec Pulling speed: 200 nm/sec

(swelling)
In some aspects of the pressure-sensitive adhesive sheet disclosed herein, the pressure-sensitive adhesive layer (first pressure-sensitive adhesive layer) has an initial thickness T0 [μm], and 4-t-butylphenylglycidyl ether is formed on the surface of the pressure-sensitive adhesive layer. The difference (T1-T0) between the thickness T1 [μm] of the pressure-sensitive adhesive layer after dropping (TBPGE) and allowing it to stand for 1 minute, that is, the amount of change in thickness is 20 μm or less. A pressure-sensitive adhesive sheet having a pressure-sensitive adhesive layer with a small amount of thickness change due to swelling with TBPGE, for example, in a mode of use in which a semiconductor chip is resin-sealed on the pressure-sensitive adhesive layer, component migration between the pressure-sensitive adhesive layer and the encapsulating resin tends to be suppressed, thereby suppressing a step (standoff) between the semiconductor chip and the sealing resin. From this point of view, in some aspects, the thickness variation is preferably 15 μm or less, more preferably 10 μm or less. The amount of change in thickness is preferably as close to 0 (zero) μm as possible, and may be 0 μm. In some aspects, from the viewpoint of balance with other properties and practical considerations such as cost, the thickness variation may be, for example, 0.1 μm or more, 0.5 μm or more, or 1 μm or more. 2 μm or more, or 3 μm or more.

In some aspects of the pressure-sensitive adhesive sheet disclosed herein, the thickness change rate of the pressure-sensitive adhesive layer after dropping TBPGE on the surface of the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet and allowing it to stand for 1 minute is preferably 160%. or less, more preferably 150% or less. A pressure-sensitive adhesive sheet provided with a pressure-sensitive adhesive layer whose thickness change rate due to swelling by TBPGE is suppressed is, for example, in a mode of use in which a semiconductor chip is resin-sealed on the pressure-sensitive adhesive layer, between the pressure-sensitive adhesive layer and the sealing resin. Component migration tends to be inhibited, which can reduce standoff. From this point of view, in some embodiments, the thickness change rate may be, for example, 120% or less, 100% or less, 80% or less, or 60% or less. The thickness change rate is preferably as small as possible, and the lower limit thereof is not particularly limited. In some embodiments, the thickness change rate may be, for example, 5% or more, 10% or more, or 20% or more from the viewpoint of balance with other properties and practical considerations such as cost.

The amount of thickness change is obtained by dropping a predetermined amount of TBPGE (0.02 g using a syringe with a diameter of 22 mm) on the surface of the adhesive layer, leaving it for 1 minute in an environment of 23 ° C. and 50% RH. From the thickness T1 of the adhesive layer at the location where TBPGE was dropped after wiping off the TBPGE remaining on the surface and the thickness (initial thickness) T0 of the adhesive layer at that location before TBPGE was dropped, T1 It is obtained by the formula of -T0. The thickness change rate is obtained from the above T0 and T1 by the formula (T1-T0)/T0. The amount of thickness change and the rate of thickness change are determined, for example, by appropriately adjusting the composition and degree of cross-linking of the base polymer (for example, acrylic polymer) of layer A that constitutes at least the surface of the pressure-sensitive adhesive layer, the type of cross-linking agent, etc. The above range can be achieved by selection. For example, 30% by weight or more (more preferably 40% by weight or more) of the monomer component constituting the acrylic polymer is an alkyl group having a large number of carbon atoms (for example, 4 or more, preferably 8 or more) at the ester end ( By using meth)acrylate, it is possible to form a pressure-sensitive adhesive layer with a small thickness change amount and/or thickness change rate.

(TMA subduction amount)
In some aspects of the pressure-sensitive adhesive sheet disclosed herein, the amount of sinking of the pressure-sensitive adhesive sheet in a 23° C. environment using TMA is about 20.0 μm or less (for example, about 1.00 μm or more and 20.0 μm or less). can be Here, the "sinking amount of the pressure-sensitive adhesive sheet in a 23° C. environment using TMA" (hereinafter also referred to as "TMA sinking amount") means, using a thermomechanical analyzer (TMA), It means the amount of sinking after 60 minutes have passed since the probe was brought into contact with the adhesive layer (first adhesive layer). The measurement conditions for the amount of TMA sinking are as follows: Probe: Penetration (cylindrical, tip diameter 1 mmΦ), nitrogen gas flow rate: 50.0 ml/min, indentation load: 0.01N. As a thermomechanical analyzer, a product name "TMA Q400" manufactured by TA Instruments, or an equivalent thereof can be used.

When the pressure-sensitive adhesive sheet has a pressure-sensitive adhesive layer only on one side of the substrate (that is, when it does not have a second pressure-sensitive adhesive layer described later), the pressure-sensitive adhesive layer (first pressure-sensitive adhesive layer) of the substrate is After applying the standard adhesive layer to the opposite side, the above measurements are taken. The standard adhesive layer is an acrylic polymer (ethyl acrylate (EA)/2-ethylhexyl acrylate (2EHA)/methyl methacrylate (MMA)/2-hydroxyethyl acrylate (HEA) = 30/70/5/ 5 (weight ratio) acrylic polymer composed of a monomer component.Weight average molecular weight 450,000) 100 parts by weight, tackifier (manufactured by Yasuhara Chemical Co., Ltd., trade name "Mighty Ace G125") 10 parts by weight, isocyanate 2 parts by weight of a cross-linking agent (manufactured by Tosoh Corporation, trade name "Coronate L"), 30 parts by weight of thermally expandable microspheres (manufactured by Matsumoto Yushi Seiyaku Co., Ltd., trade name "Matsumoto Microsphere F-190D"), and toluene It is an adhesive layer with a thickness of 45 μm formed using an adhesive composition obtained by mixing.

In some aspects, the TMA subsidence amount is preferably 15.0 μm or less, more preferably 10.0 μm or less, may be 9.00 μm or less, or may be 6.00 μm or less. A pressure-sensitive adhesive sheet with a smaller amount of TMA sinking can be used, for example, in a mode of use in which a semiconductor chip is placed on the pressure-sensitive adhesive layer and the step of sealing the semiconductor chip with resin is carried out during resin sealing (for example, FIG. 2 (ii) and (iii) of (1) above) tends to reduce the embedding of the semiconductor chip in the adhesive sheet due to the force applied to the semiconductor chip. By reducing the embedding, it is possible to reduce the step (standoff) between the semiconductor chip and the sealing resin caused by the embedding in the structure including the chip and the sealing resin. Reducing the level difference is also preferable from the viewpoint of improving the ability to prevent adhesive deposits when the pressure-sensitive adhesive sheet is peeled off from the structure.

In some embodiments, the amount of TMA subsidence may be, for example, 1.50 μm or more, from the viewpoint of enhancing conformability to the surface shape of the adherend (for example, steps that may exist on the surface of a semiconductor chip). , is suitably 2.00 μm or more, and may be 2.50 μm or more, 3.00 μm or more, or 3.50 μm or more. In the adhesive sheet exhibiting such a TMA sinking amount, it is possible to satisfactorily achieve both conformability to the surface shape of the semiconductor chip and suppression of embedding of the semiconductor chip in the adhesive sheet.
The amount of TMA sinking depends, for example, on the structure of the pressure-sensitive adhesive layer (thickness, layer composition, etc.), the composition and degree of crosslinking of the base polymer (for example, acrylic polymer) of the pressure-sensitive adhesive layer constituting the pressure-sensitive adhesive layer, and the degree of cross-linking of the cross-linking agent. The above range can be obtained by appropriately selecting the type, the type of base material, and the like.

In some aspects of the pressure-sensitive adhesive sheet disclosed herein, the pressure-sensitive adhesive sheet has a subsidence amount in a 145° C. environment using TMA (hereinafter also referred to as “high-temperature TMA subsidence amount”) of 2.00 μm or more. It is suitable to be 60 μm or less, for example, it may be 3.00 μm or more and 50 μm or less, or 4.00 μm or more and 40 μm or less. A pressure-sensitive adhesive sheet having a high-temperature TMA sinking amount within the above range can favorably suppress embedding of semiconductor chips in the pressure-sensitive adhesive sheet even when subjected to a high-temperature environment (for example, a heat treatment environment during resin sealing). The high-temperature TMA subsidence amount is measured in the same manner as the TMA subsidence amount under the above-described 23°C environment, except that the ambient temperature for measurement is 145°C.

(probe tack value)
In some aspects of the pressure-sensitive adhesive sheet disclosed herein, the probe tack value measured on the surface of the pressure-sensitive adhesive layer (first pressure-sensitive adhesive layer) is preferably 50 N/5 mmφ or more, more preferably 75 N/ It is 5 mmφ or more, more preferably 100 N/5 mmφ or more. It is preferable that the probe tack value is in such a range from the viewpoint of preventing displacement of the adherend (for example, semiconductor chip) placed on the pressure-sensitive adhesive layer. Probe tack value was measured using a commercially available probe tack tester under an environment of 23°C and 50% RH, probe area area and material: 5 mmφ SUS (stainless steel), probe lowering speed: 30 mm/min, adhesion load. : 100 gf, adhesion holding time: 1 second, test speed: 30 mm/min.

(Adhesive strength against PET)
The adhesive strength (adhesive strength to PET) of the adhesive sheet disclosed herein to polyethylene terephthalate film is not particularly limited, and may be, for example, 5.00 N/20 mm or less, 3.00 N/20 mm or less, or 2.00 N. /20 mm or less. In some aspects, from the viewpoint of preventing damage to the adherend due to the load when the adhesive sheet is peeled off, the adhesive strength to PET is preferably 1.00 N/20 mm or less, and 0.05 N/20 mm or less. is more preferable. In some embodiments, the adhesive strength of the adhesive sheet to PET is suitably 0.03 N/20 mm or more from the viewpoint of preferably fixing the adherend (e.g., semiconductor chip), and 0.05 N /20 mm or more, may be 0.10 N/20 mm or more, or may be 0.15 N/20 mm or more.
The adhesive strength to PET was obtained by laminating a PET film (thickness 25 μm) as an adherend to the adhesive layer (first adhesive layer) of an adhesive sheet having a width of 20 mm and a length of 140 mm (lamination conditions: 2 kg roller 1 Reciprocating), and after leaving it for 30 minutes at an environmental temperature of 23° C., a tensile test (peeling angle of 180 degrees, tensile speed of 300 mm/min) and adhesive strength measured.

(tensile modulus)
In some aspects, the tensile modulus at 25° C. of the first pressure-sensitive adhesive layer is preferably less than 100 MPa, more preferably 0.1 MPa to 50 MPa, even more preferably 0.1 MPa to 10 MPa. Within such a range, it is easy to obtain a pressure-sensitive adhesive sheet in which the first pressure-sensitive adhesive layer exhibits appropriate adhesive strength. The tensile modulus can be measured according to JISK7161:2008.

<Adhesive layer (first adhesive layer)>
In the pressure-sensitive adhesive sheet disclosed herein, the pressure-sensitive adhesive constituting the pressure-sensitive adhesive layer (first pressure-sensitive adhesive layer) disposed on at least one side of the substrate may be any suitable pressure-sensitive adhesive as long as the effects of the present invention can be obtained. Adhesives can be used. The adhesive layer includes, for example, acrylic adhesives, rubber adhesives (natural rubber, synthetic rubber, mixtures thereof, etc.), silicone adhesives, polyester adhesives, urethane adhesives, polyether It may contain one or more adhesives selected from various known adhesives such as adhesives, polyamide adhesives, fluorine-based adhesives, and the like. In the pressure-sensitive adhesive layer containing two or more types of pressure-sensitive adhesives, the pressure-sensitive adhesives may be two or more types selected from the same type of pressure-sensitive adhesive (e.g., acrylic pressure-sensitive adhesive), or two or more different types of pressure-sensitive adhesives. (for example, an acrylic pressure-sensitive adhesive and a polyester-based pressure-sensitive adhesive). In the pressure-sensitive adhesive layer containing two or more types of pressure-sensitive adhesives, the pressure-sensitive adhesives may be uniformly mixed, or may be arranged (for example, laminated) at different positions in the thickness direction. They may be arranged (for example, painted separately) with different positions in the direction, or may be arranged in a combination of these, or an intermediate arrangement between them.

The thickness of the first adhesive layer is preferably 5 μm or more. When the thickness of the first pressure-sensitive adhesive layer is 5 μm or more, it is easy to exhibit good conformability to the surface shape of the adherend. The upper limit of the thickness of the first pressure-sensitive adhesive layer is not particularly limited, and may be, for example, 200 μm or less, or 150 μm or less. In some aspects, it is possible to prevent adhesive residue due to cohesive failure of the adhesive layer, and to suppress embedding of the semiconductor chip in the adhesive sheet in the usage mode in which the resin sealing step of the semiconductor chip is performed on the adhesive layer. From a viewpoint, the thickness of the first pressure-sensitive adhesive layer is suitably 110 μm or less, preferably 60 μm or less, and more preferably 20 μm or less.

<A layer>
The pressure-sensitive adhesive layer (first pressure-sensitive adhesive layer) typically includes a layer A that constitutes at least the surface of the pressure-sensitive adhesive layer. In some aspects, the pressure-sensitive adhesive layer may have a single layer structure consisting of the A layer. In this case, the layer A is formed by directly bonding the opposite side of the surface to one surface of the substrate. In some other embodiments, the pressure-sensitive adhesive layer has another pressure-sensitive adhesive layer different from the layer A (e.g., a layer B described later) between the layer A and one side surface of the substrate. It can be configured to In this embodiment, the difference between the pressure-sensitive adhesive constituting the layer A and the pressure-sensitive adhesive constituting the other pressure-sensitive adhesive layer is, for example, the difference in the base polymer (for example, the composition of the monomer component constituting the base polymer). difference, weight average molecular weight, polymer chain structure difference, etc.), cross-linking agent difference (e.g., type and amount used), tackifying resin difference (e.g., presence or absence, content, tackifying resin difference in type, etc.), presence or absence of other additives, difference in content, type, etc., may be one or more.

In some preferred embodiments, the adhesive that constitutes the A layer is an acrylic adhesive that uses an acrylic polymer as a base polymer. By forming at least the surface of the first pressure-sensitive adhesive layer with an acrylic pressure-sensitive adhesive, the effects of the invention disclosed herein can be favorably exhibited.

(acrylic polymer)
The acrylic polymer, which is the base polymer of the acrylic pressure-sensitive adhesive, preferably contains an alkyl (meth)acrylate as a main monomer, and optionally further contains a sub-monomer copolymerizable with the main monomer. It is a polymer. The term "main monomer" as used herein refers to the main component in the monomer component that constitutes the acrylic polymer, that is, the component contained in the monomer component in an amount exceeding 50% by weight.

As the alkyl (meth)acrylate, for example, compounds represented by the following formula (A) can be preferably used.
_CH2 =C( ^R1 ) ^COOR2 (A)
Here, R ¹ in the above formula (A) is a hydrogen atom or a methyl group. R ² is a chain alkyl group having 1 to 20 carbon atoms (hereinafter, such a range of carbon atoms may be referred to as "C _1-20 "). From the viewpoint of ease of adjustment of adhesive properties, etc., alkyl (meth)acrylates in which R ² is a C _1-18 chain alkyl group are preferred, and R ² is a C _1-12 chain alkyl group (alkyl (meth)acrylate). ) acrylates are more preferred.

Specific examples of the alkyl (meth)acrylates include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, isopropyl (meth)acrylate, butyl (meth)acrylate, and (meth)acrylate. isobutyl acrylate, s-butyl (meth)acrylate, t-butyl (meth)acrylate, pentyl (meth)acrylate, hexyl (meth)acrylate, heptyl (meth)acrylate, octyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, isooctyl (meth)acrylate, nonyl (meth)acrylate, isononyl (meth)acrylate, decyl (meth)acrylate, isodecyl (meth)acrylate, undecyl (meth)acrylate , dodecyl (meth)acrylate, tridecyl (meth)acrylate, tetradecyl (meth)acrylate, pentadecyl (meth)acrylate, hexadecyl (meth)acrylate, heptadecyl (meth)acrylate, octadecyl (meth)acrylate, (Meth)acrylic acid C _1-20 alkyl esters such as nonadecyl (meth)acrylate and eicosyl (meth)acrylate. Among them, (meth)acrylic acid alkyl esters having a C _4-20 (more preferably C _6-20 , still more preferably C _8-18 ) linear or branched alkyl group Acid 2-ethylhexyl) is preferably used.

In some aspects, 30% by weight or more of the monomer components constituting the acrylic polymer have 4 or more carbon atoms (preferably 8 or more) in R ² in the formula (A), and preferably 18 or less, such as 12 below) is an alkyl (meth)acrylate having a structure that is a linear or branched alkyl group. By using such an alkyl (meth)acrylate, component migration between the pressure-sensitive adhesive layer and the sealing resin can be preferably suppressed. The content of the alkyl (meth)acrylate in the monomer component used to synthesize the acrylic polymer is preferably 40% by weight or more, and in some embodiments may be 50% by weight or more, and may be 70% by weight or more. . The content of the alkyl (meth)acrylate in the monomer component is suitably 99.5% by weight or less from the viewpoint of facilitating adjustment of the indentation hardness H1 at the measurement position A to a suitable range. % or less, may be 98 wt % or less, or may be 97 wt % or less.

A sub-monomer that is copolymerizable with the main monomer, alkyl (meth)acrylate, can be useful for introducing cross-linking points into the acrylic polymer and increasing the cohesive strength and heat resistance of the acrylic polymer. Secondary monomers can also help adjust the indentation hardness H1. As the submonomer, for example, the following functional group-containing monomers can be used singly or in combination of two or more. For example, the following functional group-containing monomers can be used singly or in combination of two or more.

Carboxy group-containing monomers such as acrylic acid, methacrylic acid, carboxyethyl acrylate, carboxypentyl acrylate, itaconic acid, maleic acid, fumaric acid, crotonic acid;
Acid anhydride monomers such as maleic anhydride and isotanoic anhydride;
Hydroxyethyl (meth)acrylate, hydroxypropyl (meth)acrylate, hydroxybutyl (meth)acrylate, hydroxyhexyl (meth)acrylate, hydroxyoctyl (meth)acrylate, hydroxydecyl (meth)acrylate, (meth)acrylate ) hydroxy group-containing monomers such as hydroxyllauryl acrylate, (4-hydroxymethylcyclohexyl)methyl methacrylate;
(N-substituted) amide monomers such as (meth)acrylamide, N,N-dimethyl(meth)acrylamide, N-butyl(meth)acrylamide, N-methylol(meth)acrylamide, N-methylolpropane(meth)acrylamide;
N-vinyl-2-pyrrolidone, N-methylvinylpyrrolidone, N-vinylpyridine, N-vinylpiperidone, N-vinylpyrimidine, N-vinylpiperazine, N-vinylpyrazine, N-vinylpyrrole, N-vinylimidazole, N- Monomers having a nitrogen atom-containing ring such as vinyloxazole, N-vinylmorpholine, N-vinylcaprolactam, N-(meth)acryloylmorpholine;
amino group-containing monomers such as aminoethyl (meth)acrylate, N,N-dimethylaminoethyl (meth)acrylate, and t-butylaminoethyl (meth)acrylate;
epoxy group-containing acrylic monomers such as glycidyl (meth)acrylate;
Cyano group-containing monomers such as acrylonitrile and methacrylonitrile;
Sulfonic acids such as styrenesulfonic acid, allylsulfonic acid, 2-(meth)acrylamido-2-methylpropanesulfonic acid, (meth)acrylamidopropanesulfonic acid, sulfopropyl (meth)acrylate, (meth)acryloyloxynaphthalenesulfonic acid group-containing monomer;
Maleimide monomers such as N-cyclohexylmaleimide, N-isopropylmaleimide, N-laurylmaleimide, N-phenylmaleimide;
Itaconimide-based monomers such as N-methylitaconimide, N-ethylitaconimide, N-butylitaconimide, N-octylitaconimide, N-2-ethylhexylitaconimide, N-cyclohexylitaconimide, N-laurylitaconimide;
succinimide-based monomers such as N-(meth)acryloyloxymethylenesuccinimide, N-(meth)acryloyl-6-oxyhexamethylenesuccinimide, N-(meth)acryloyl-8-oxyoctamethylenesuccinimide;
3-(meth)acryloxypropyltrimethoxysilane, 3-(meth)acryloxypropyltriethoxysilane, 3-(meth)acryloxypropylmethyldimethoxysilane, 3-(meth)acryloxypropylmethyldiethoxysilane, etc. , an alkoxysilyl group-containing monomer.

The monomer component may contain other copolymerizable monomers other than the above-exemplified functional group-containing monomers as submonomers for the purpose of improving the cohesive strength and the like. Examples of such other copolymerizable monomers include vinyl ester monomers such as vinyl acetate, vinyl propionate, and vinyl laurate; aromatic vinyl compounds such as styrene, substituted styrene (α-methylstyrene, etc.), and vinyl toluene; cycloalkyl (meth)acrylates such as cyclohexyl (meth)acrylate, cyclopentyl (meth)acrylate, isobornyl (meth)acrylate; aryl (meth)acrylates (e.g. phenyl (meth)acrylate), aryloxyalkyl (meth)acrylates (e.g. phenoxy aromatic ring-containing (meth)acrylates such as ethyl (meth)acrylate) and arylalkyl (meth)acrylates (e.g. benzyl (meth)acrylate); olefinic monomers such as ethylene, propylene, isoprene, butadiene and isobutylene; vinyl chloride , chlorine-containing monomers such as vinylidene chloride; isocyanate group-containing monomers such as 2-(meth)acryloyloxyethyl isocyanate; alkoxy group-containing monomers such as methoxyethyl (meth) acrylate and ethoxyethyl (meth) acrylate; methyl vinyl ether, ethyl vinyl ether Vinyl ether-based monomers such as; polyethylene glycol (meth)acrylate, polypropylene glycol (meth)acrylate, methoxyethylene glycol (meth)acrylate, and glycol-based monomers such as methoxypolypropylene glycol (meth)acrylate;
Other examples include heterocyclic ring-containing monomers such as tetrahydrofurfuryl (meth)acrylate, fluorine (meth)acrylates, silicone (meth)acrylates, and the like.

The monomer component may contain, as the other copolymerizable monomer, a polyfunctional monomer for the purpose of cross-linking or the like. Non-limiting examples of such multifunctional monomers include hexanediol di(meth)acrylate, (poly)ethylene glycol di(meth)acrylate, (poly)propylene glycol di(meth)acrylate, neopentyl glycol di(meth)acrylate, (meth)acrylate, pentaerythritol di(meth)acrylate, trimethylolpropane tri(meth)acrylate, pentaerythritol tri(meth)acrylate, dipentaerythritol hexa(meth)acrylate, polyfunctional epoxy acrylate, polyfunctional polyester acrylate, poly multifunctional monomers such as functional urethane acrylates; and the like. A polyfunctional monomer can be used individually by 1 type or in combination of 2 or more types.

In some preferred embodiments, the acrylic polymer is a monomer whose homopolymer has a glass transition temperature (Tg) of -5°C to 150°C (preferably 50°C to 150°C, more preferably 80°C to 120°C). It preferably contains a structural unit a derived from. Including such a structural unit a restricts the molecular motion of the acrylic polymer, and it is possible to realize a layer A in which the T2 relaxation _time of the S component by the pulse NMR is preferably adjusted. Moreover, since at least the surface of the first pressure-sensitive adhesive layer is composed of the layer A, it is possible to obtain a pressure-sensitive adhesive sheet having excellent low-temperature pressure-sensitive adhesiveness. The content of the structural unit a is preferably 0.1% by weight to 20% by weight, more preferably 1% by weight to 10% by weight, and particularly Preferred is 1.5% to 8% by weight, most preferred is 3% to 6% by weight.

Examples of monomers having a homopolymer Tg of -5°C to 150°C include 2-hydroxyethyl acrylate (Tg: -3°C), 2-hydroxyethyl methacrylate (Tg: 77°C), acrylic acid (Tg: 102°C ), cyclohexyl methacrylate (Tg: 83°C), dicyclopentanyl acrylate (Tg: 120°C), dicyclopentanyl methacrylate (Tg: 175°C), isobornyl acrylate (Tg: 94°C), methacrylic acid isobornyl (Tg: 150°C), t-butyl methacrylate (Tg: 118°C), methyl methacrylate (Tg: 105°C), styrene (Tg: 80°C), acrylonitrile (Tg: 97°C), N-acryloyl morpholine (Tg: 145°C), and the like. As the glass transition temperature of homopolymers of monomers other than the above, the values described in publicly known materials such as "Polymer Handbook" (3rd edition, John Wiley & Sons, Inc., 1989) are used. For monomers for which multiple values are listed in the above Polymer Handbook, the highest value is adopted. If the Tg of the homopolymer is not described in known documents, the value obtained by the measurement method described in Japanese Patent Application Publication No. 2007-51271 shall be used.
These monomers can be used singly or in combination of two or more. Among them, methyl methacrylate is preferable for enhancing the visibility of the adherend during processing because it enhances the transparency of the pressure-sensitive adhesive layer. Further, acrylic acid is preferable when strong adhesion is required because it strongly adheres to an adherend due to intermolecular interaction. In addition, 2-hydroxyethyl (meth)acrylate exhibits high reactivity with various cross-linking agents, and is suitable for forming an adhesive having a short T2 relaxation _time , which will be described later.

In some preferred embodiments, the acrylic polymer contains a structural unit derived from a carboxy group-containing monomer. The content of structural units derived from a carboxy group-containing monomer is preferably 0.1% by weight or more, more preferably 1% by weight or more, and still more preferably It is 2% by weight or more, preferably 15% by weight or less, more preferably 10% by weight or less, and still more preferably 7% by weight or less.

In some preferred embodiments, the acrylic polymer contains a structural unit derived from a hydroxy group-containing monomer. The content of structural units derived from a hydroxy group-containing monomer is preferably 0.01% by weight or more, more preferably 0.03% by weight or more, relative to all the structural units constituting the acrylic polymer. It is 0.05% by weight or more, preferably 20% by weight or less, more preferably 10% by weight or less, for example, 7% by weight or less.

(SP value)
In some embodiments, the SP value of the base polymer (preferably acrylic polymer) of the pressure-sensitive adhesive that constitutes layer A is, for example, suitably 10 or more and 30 or less, and preferably 15 or more and 25 or less. , 18 or more and 20 or less. Within such a range, migration of components between the pressure-sensitive adhesive layer and the sealing resin can be preferably prevented. In this specification, the units of numerical values representing SP values are all "(cal/cm ³ ) ^1/2 ".

Here, the SP value is a value calculated from the basic structure of the compound by the method proposed by Fedors. Specifically, the SP value is calculated according to the following formula from the evaporation energy Δe (cal) of each atom or atomic group at 25° C. and the molar volume Δv (cm ³ ) of each atom or atomic group at the same temperature. be.
SP value = (ΣΔe/ΣΔv) ^1/2
(Reference: Hideki Yamamoto, "SP Value Basics/Applications and Calculation Methods", 4th edition, Information Organization Publishing Co., Ltd., published on April 3, 2006, pp. 66-67).

When the polymer is a copolymer, the SP value is obtained by calculating the SP value of each homopolymer of each structural unit that constitutes the copolymer, and adding the moles of each structural unit to each of these SP values. Calculated by summing the products multiplied by the fractions. In the above case, the analysis method of each structural unit (polymer composition analysis) is to collect only the adhesive layer from the adhesive sheet as appropriate and immerse it in an organic solvent such as dimethylformamide (DMF), acetone, methanol, tetrahydrofuran (THF). The resulting solvent-soluble portion can be recovered and determined by analysis methods such as gel filtration permeation chromatography (GPC), nuclear magnetic resonance spectroscopy (NMR), infrared spectroscopy (IR), and mass spectrometry.

(crosslinking agent)
From the viewpoint of easily achieving the preferred indentation hardness H1 described above, the base polymer of the layer A is preferably crosslinked in the adhesive constituting the layer A. For example, by using a pressure-sensitive adhesive composition containing a base polymer and an appropriate cross-linking agent, it is possible to obtain a layer A composed of a pressure-sensitive adhesive in which the base polymer is cross-linked with the cross-linking agent.

The type of cross-linking agent is not particularly limited. Cross-linking agents, metal salt-based cross-linking agents, carbodiimide-based cross-linking agents, oxazoline-based cross-linking agents, aziridine-based cross-linking agents, amine-based cross-linking agents, etc. can be appropriately selected and used. A crosslinking agent can be used individually by 1 type or in combination of 2 or more types. Among them, preferred cross-linking agents include epoxy-based cross-linking agents and isocyanate-based cross-linking agents.

Examples of epoxy-based cross-linking agents include N,N,N',N'-tetraglycidyl-m-xylenediamine, diglycidylaniline, 1,3-bis(N,N-glycidylaminomethyl)cyclohexane (Mitsubishi Gas Chemical company, trade name “Tetrad C”), 1,6-hexanediol diglycidyl ether (manufactured by Kyoeisha Chemical Co., Ltd., trade name “Epolite 1600”), neopentyl glycol diglycidyl ether (manufactured by Kyoeisha Chemical Co., Ltd., trade name “Epolite 1500NP"), ethylene glycol diglycidyl ether (manufactured by Kyoeisha Chemical Co., Ltd., trade name "Epolite 40E"), propylene glycol diglycidyl ether (manufactured by Kyoeisha Chemical Co., Ltd., trade name "Epolite 70P"), polyethylene glycol diglycidyl ether (NOF company, trade name “Epiol E-400”), polypropylene glycol diglycidyl ether (manufactured by NOF Corporation, trade name “Epiol P-200”), sorbitol polyglycidyl ether (manufactured by Nagase ChemteX Corporation, trade name “Denacol EX -611”), glycerol polyglycidyl ether (manufactured by Nagase ChemteX, trade name “Denacol EX-314”), pentaerythritol polyglycidyl ether, polyglycerol polyglycidyl ether (manufactured by Nagase ChemteX, trade name “Denacol EX- 512"), sorbitan polyglycidyl ether, trimethylolpropane polyglycidyl ether, adipate diglycidyl ester, o-phthalate diglycidyl ester, triglycidyl-tris(2-hydroxyethyl) isocyanurate, resorcin diglycidyl ether, bisphenol- Examples include S-diglycidyl ether and epoxy resins having two or more epoxy groups in the molecule. The amount of the epoxy-based cross-linking agent used can be set to any appropriate amount depending on the desired properties. In some embodiments, the amount of the epoxy-based cross-linking agent used relative to 100 parts by weight of the base polymer may be, for example, 0.01 to 50 parts by weight, preferably 0.6 to 15 parts by weight. more preferably 2 parts by weight or more and 13 parts by weight or less, and still more preferably 3 parts by weight or more and 10 parts by weight or less.

Specific examples of isocyanate-based cross-linking agents include lower aliphatic polyisocyanates such as butylene diisocyanate and hexamethylene diisocyanate; alicyclic isocyanates such as cyclopentylene diisocyanate, cyclohexylene diisocyanate and isophorone diisocyanate; Aromatic isocyanates such as diisocyanate, 4,4'-diphenylmethane diisocyanate, and xylylene diisocyanate; trimethylolpropane/tolylene diisocyanate trimer adduct (manufactured by Tosoh Corporation, trade name "Coronate L"), trimethylolpropane/ Isocyanate adducts such as hexamethylene diisocyanate trimer adduct (manufactured by Tosoh Corporation, trade name "Coronate HL"), isocyanurate form of hexamethylene diisocyanate (manufactured by Tosoh Corporation, trade name "Coronate HX"); be done. The amount of the isocyanate-based cross-linking agent used can be set to any appropriate amount depending on the desired adhesive strength. In some aspects, the amount of the isocyanate-based cross-linking agent used relative to 100 parts by weight of the base polymer is typically 0.1 parts by weight or more and 20 parts by weight or less, preferably 1 part by weight or more and 10 parts by weight or less. .

In some aspects, an epoxy-based cross-linking agent can be preferably employed as the cross-linking agent used in the A layer. The A layer having a crosslinked structure in which the base polymer is crosslinked with an epoxy-based crosslinking agent can suitably achieve the preferred indentation hardness H1 disclosed herein. Also, it is possible to obtain a pressure-sensitive adhesive sheet that can preferably reduce the difference in level between the semiconductor chip and the sealing resin. In addition, it is possible to form a pressure-sensitive adhesive layer with high cohesive force, and to more effectively prevent displacement of the adherend.

In some aspects, a cross-linking agent containing a nitrogen (N) atom can be preferably used as the cross-linking agent. A cross-linking agent containing an N atom is advantageous in that the cross-linking reaction (for example, reaction with carboxy groups in the base polymer) is promoted by the catalytic action of the N atom, and the gel fraction of the pressure-sensitive adhesive can be easily increased. Specific examples of N atom-containing cross-linking agents include isocyanate cross-linking agents as described above, as well as N atom-containing epoxy cross-linking agents (for example, N,N,N',N'-tetraglycidyl-m-xylenediamine and 1,3-bis(N,N-glycidylaminomethyl)cyclohexane, epoxy-based cross-linking agents having a glycidylamino group). In some embodiments using a cross-linking agent containing N atoms, the nitrogen gas generation amount described later is 0.06 wt% or more and 1.0 wt% or less (more preferably 0.06 wt% or more and 0.9 wt% or less) It is preferable to set the amount of the cross-linking agent to be used so that By using such amount, it is easy to obtain a pressure-sensitive adhesive sheet that satisfactorily achieves both the prevention of adhesive residue and the conformability to the surface shape.

In some embodiments, a cross-linking agent (preferably a cross-linking agent that forms a cross-linked structure by reacting with a carboxy group, e.g., an epoxy-based cross-linking agent, an isocyanate-based cross-linking agent etc.) is preferably from 0.08 molar equivalent to 2 molar equivalents, more preferably from 0.1 molar equivalent to 1 molar equivalent. With such a usage amount, the preferred indentation hardness H1 disclosed herein can be accurately achieved. In addition, a pressure-sensitive adhesive sheet having a small number of residual carboxy groups in the pressure-sensitive adhesive layer can be obtained by cross-linking the carboxy groups in the base polymer with the above amount of the cross-linking agent.

(Other additives)
The pressure-sensitive adhesive constituting the A layer may contain appropriate additives other than those described above as optional components, if necessary. Such additives include, for example, tackifiers, plasticizers (e.g., trimellitic ester plasticizers, pyromellitic ester plasticizers, etc.), pigments, dyes, fillers, antioxidants, conductive materials, , antistatic agents, ultraviolet absorbers, light stabilizers, release modifiers, softeners, surfactants, flame retardants, antioxidants, and the like.

Any appropriate tackifier can be used as the tackifier. As the tackifier, for example, a tackifier resin is used. Specific examples of the tackifying resin include rosin-based tackifying resins (e.g., unmodified rosin, modified rosin, rosin phenol-based resin, rosin ester-based resin, etc.), terpene-based tackifying resins (e.g., terpene-based resin, terpene phenolic resin, styrene-modified terpene-based resin, aromatic-modified terpene-based resin, hydrogenated terpene-based resin), hydrocarbon-based tackifying resin (e.g., aliphatic hydrocarbon resin, aliphatic cyclic hydrocarbon resin, aromatic Hydrocarbon resins (e.g., styrene resins, xylene resins, etc.), aliphatic/aromatic petroleum resins, aliphatic/alicyclic petroleum resins, hydrogenated hydrocarbon resins, coumarone resins, coumarone-indene resins resins, etc.), phenolic tackifying resins (e.g., alkylphenolic resins, xylene-formaldehyde-based resins, resols, novolacs, etc.), ketone-based tackifying resins, polyamide-based tackifying resins, epoxy-based tackifying resins, elastomer-based tackifying resins etc. Among them, rosin-based tackifying resins, terpene-based tackifying resins, and hydrocarbon-based tackifying resins (styrene-based resins, etc.) are preferred. A tackifier can be used individually by 1 type or in combination of 2 or more types.

In some aspects, a resin with a high softening point or glass transition temperature (Tg) is used as the tackifying resin. If a resin with a high softening point or glass transition temperature (Tg) is used, a pressure-sensitive adhesive layer that can exhibit high adhesiveness even in a high-temperature environment (for example, in a high-temperature environment during processing when sealing semiconductor chips) is formed. can do. The softening point of the tackifier is preferably 100°C to 180°C, more preferably 110°C to 180°C, even more preferably 120°C to 180°C. The glass transition temperature (Tg) of the tackifier is preferably 100°C to 180°C, more preferably 110°C to 180°C, even more preferably 120°C to 180°C.

In some embodiments, a low-polarity tackifying resin is used as the tackifying resin. Using a low-polarity tackifying resin is advantageous from the viewpoint of forming a pressure-sensitive adhesive layer with low affinity for the sealing material. Low-polar tackifying resins include, for example, aliphatic hydrocarbon resins, aliphatic cyclic hydrocarbon resins, aromatic hydrocarbon resins (e.g., styrene resins, xylene resins, etc.), aliphatic/aromatic petroleum resins (sometimes referred to as C5/C9 petroleum resins), aliphatic/alicyclic petroleum resins, and hydrocarbon tackifying resins such as hydrogenated hydrocarbon resins. Of these, aliphatic/aromatic petroleum resins are preferred. Such a tackifying resin has low polarity, is excellent in compatibility with acrylic polymers, does not undergo phase separation in a wide temperature range, and can form a highly stable adhesive layer.

The acid value of the tackifying resin is preferably 40 or less, more preferably 20 or less, and even more preferably 10 or less. Within such a range, it is possible to form a pressure-sensitive adhesive layer having low affinity with the sealing material. The hydroxyl value of the tackifier resin is preferably 60 or less, more preferably 40 or less, still more preferably 20 or less. Within such a range, it is possible to form a pressure-sensitive adhesive layer that has low affinity with the sealing material and is suitable for suppressing migration of components between the pressure-sensitive adhesive layer and the sealing resin.

The amount of the tackifier used may be, for example, 5 parts by weight or more and 100 parts by weight or less, preferably 8 parts by weight or more and 50 parts by weight or less, relative to 100 parts by weight of the base polymer. In some aspects of the pressure-sensitive adhesive sheet disclosed herein, from the viewpoint of easy peelability from the adherend and suppression of adhesive residue, a tackifier is added to 100 parts by weight of the base polymer of the pressure-sensitive adhesive constituting the layer A. It is suitable that the amount is less than 3 parts by weight, less than 1 part by weight, or less than 0.5 parts by weight, and it is preferable not to blend a tackifier (in particular, a tackifier resin) with the adhesive constituting the A layer. .

(T2 relaxation _time )
In some aspects of the pressure-sensitive adhesive sheet disclosed herein, the T ₂ relaxation time (T _2s ) of the S component of the A layer by pulse NMR is preferably 45 μsec or less. According to the pressure-sensitive adhesive sheet in which the _{T2 relaxation time (T 2s} ₎ of the layer A constituting at least the surface of the first pressure-sensitive adhesive layer is 45 μsec or less, for example, a semiconductor chip is resin-sealed on the first pressure-sensitive adhesive layer. WHEREIN: It can suppress the component migration between an adhesive layer and sealing resin, and can suppress the level|step difference between a semiconductor chip and sealing resin suitably.

The relaxation time means the time required for the excited atoms (group) to return to the ground state after irradiation with energy suitable for exciting the atoms to be measured in pulse NMR measurement. The excited state of atoms (groups) can be controlled by the amount and time of energy irradiation. In addition, it is known that there are various energy relaxation mechanisms for the excited atoms (groups) to return to the ground state, and the relaxation time is determined according to the relaxation mechanism (for example, "Chemist Review of the Latest NMR for Physics, Kagaku Dojin (1997)). The present inventors excited the ¹ H atoms of an acrylic pressure-sensitive adhesive (substantially, an acrylic polymer contained in the pressure-sensitive adhesive) under the following conditions, measured the subsequent relaxation behavior, and further analyzed the measured values. As a result, _among them, S The inventors have found that the component (T _2s ) is useful, and have found that the above effect can be obtained by specifying the S component (T _2s ) of the T ₂ relaxation time. A short T _2s indicates a state in which molecular motion related to the degree of cross-linking of the base polymer is restricted, that is, a state in which cross-linking progresses and the degree of freedom of movement of the polymer as a whole is reduced. indicates In such a state of the adhesive, the gaps between the base polymers are small, and the migration of the components of the adhesive layer into the sealing resin and the migration of the low-molecular-weight components contained in the sealing resin into the adhesive layer are suppressed. tend to As a result, when the adhesive sheet is peeled off after the semiconductor chip is resin-sealed on the adhesive sheet, the occurrence of a step between the semiconductor chip and the sealing resin is prevented.

The T ₂ relaxation time (T _2s ) of the S component by pulse NMR of the A layer is preferably 40 μsec or less, and is preferably 35 μsec or less (for example, 30 μsec or less) from the viewpoint of better suppression of component migration from the sealing resin. is more preferable. The lower limit of _T2s of the A layer is not particularly limited, and may be, for example, 5 μsec or more. From the viewpoint of facilitating the development of moderate tackiness on the pressure-sensitive adhesive layer surface, in some embodiments, T _2s of layer A may be 10 μsec or more, 15 μsec or more, or 20 μsec or more. good too. It is preferable that the T _2s of the A layer is not too short from the viewpoint of improving the adhesion between the A layer and a layer adjacent thereto (which may be a base material, an adherend, a B layer described later, etc.).

The T _2s of the A layer is obtained by obtaining a T ₂ relaxation curve measured by a solid echo method using about 100 mg of the adhesive constituting the A layer as a measurement sample, and fitting the T ₂ relaxation curve to the following formula (1). can ask. The T ₂ relaxation time (T _2s ) of the S component by pulse NMR of the B layer, which will be described later, is also measured in the same manner.

M(t)=α・exp(-(1/Wa)(t/ _T2s ) ^Wa )+β・exp(-(1/Wa)(t/ _T2L ) ^Wa ) (1)
M(t): Free induction decay α: Proton ratio (%) of component with short relaxation time (S component)
T _2s : T ₂ relaxation time of S component (msec)
β: Proton ratio (%) of component with long relaxation time (L component)
T _2L : T ₂ relaxation time of L component (msec)
t: observation time (msec)
Wa: Shape factor (=1)

The measurement conditions for the above measurements are as follows.
・90° pulse width: 2.1 μsec
・Repeat time: 1 sec
・Number of accumulated times: 32 times ・Measured temperature: 30°C

(Gel fraction)
The gel fraction of the adhesive constituting layer A is preferably 75% or more, more preferably 85% or more, and still more preferably 90% or more. Within such a range, the molecular motion of the base polymer is preferably restricted by cross-linking, and component transfer between the pressure-sensitive adhesive layer and the sealing resin can be suppressed. From the viewpoint of suppressing migration of components, the higher the gel fraction constituting the A layer, the more advantageous. In addition, considering the balance with other properties (for example, moderate tackiness and adhesiveness on the surface of the pressure-sensitive adhesive layer, conformability to the surface shape of the adherend, etc.), in some embodiments, the A layer is The gel fraction of the constituent adhesive may be, for example, 99.5% or less, or may be 99% or less. The gel fraction is determined by (dry weight of adhesive after immersion/weight of adhesive before immersion)×100 after immersing the adhesive collected from layer A in ethyl acetate for 7 days and then drying.

(Nitrogen gas generation amount)
In the pressure-sensitive adhesive sheet according to some aspects, the amount of nitrogen gas generated when the pressure-sensitive adhesive constituting the layer A is heat-treated is preferably 0, with the weight of the pressure-sensitive adhesive subjected to the heat treatment being 100% by weight. 0.06 wt % to 1.0 wt %, more preferably 0.06 wt % to 0.9 wt %. When the amount of nitrogen gas generated is 0.06% by weight or more, the pressure-sensitive adhesive exhibits sufficient cohesive force and suppresses migration of components between the pressure-sensitive adhesive layer and the sealing resin, thereby sealing the semiconductor chip. There is a tendency that a step is less likely to occur at the interface of the stopper resin. The fact that the amount of nitrogen gas generated is 1.0% by weight or less is advantageous from the viewpoint of suppressing displacement of the adherend placed on the A layer.
The amount of nitrogen gas generated is the amount of nitrogen gas generated by heating a sample obtained by taking 2 mg of the adhesive, putting it in a ceramic board, and weighing it with a microbalance under the conditions of a pyrolysis furnace at 800°C and an oxidation furnace at 900°C. is determined by analyzing with a TN (trace total nitrogen analysis) device. Conditions for measurement can be as follows.
Carrier gas: O ₂ (300 mL/min), Ar (300 mL/min)
・Standard sample: pyridine/toluene solution ・Detector: vacuum chemiluminescence detector ・Range: high concentration

<B layer>
In some aspects of the pressure-sensitive adhesive sheet disclosed herein, the first pressure-sensitive adhesive layer is disposed between a layer A constituting at least the surface of the pressure-sensitive adhesive layer and the layer A and the substrate. and a B layer adjacent to the substrate. That is, the outer surface (surface on the adherend side) of the first pressure-sensitive adhesive layer is formed by the A layer, and the inner surface (surface on the base material side) of the first pressure-sensitive adhesive layer is formed by the B layer. According to the first adhesive layer having such a structure, for example, by selecting the adhesive constituting each of the A layer and B layer, selecting the thickness of each layer, etc., the characteristics at the measurement positions A and B (indentation hardness, thread _pullability , T2 relaxation time of the S component, etc.) and their ratio can be easily adjusted.

Any appropriate adhesive can be used as the adhesive that constitutes the B layer. The layer B is, for example, an acrylic adhesive, a rubber adhesive, a silicone adhesive, a polyester adhesive, a urethane adhesive, a polyether adhesive, a polyamide adhesive, a fluorine adhesive, or the like. 1 or 2 or more adhesives selected from various adhesives.

In some preferred embodiments, the pressure-sensitive adhesive that constitutes the layer B is an acrylic pressure-sensitive adhesive that uses an acrylic polymer as a base polymer. In the aspect in which the layer A is composed of an acrylic pressure-sensitive adhesive, the acrylic pressure-sensitive adhesive may be used as the pressure-sensitive adhesive constituting the layer B from the viewpoint of enhancing the interlayer adhesion of the layers contained in the first pressure-sensitive adhesive layer. Especially preferred.

In the embodiment in which the pressure-sensitive adhesive constituting the B layer is an acrylic pressure-sensitive adhesive, the acrylic polymer that is the base polymer of the acrylic pressure-sensitive adhesive is appropriately selected from those similar to the acrylic polymers described above as the base polymer of the A layer. can choose. The acrylic polymer that is the base polymer of layer A and the acrylic polymer that is the base polymer of layer B may be the same or different. In some embodiments, from the viewpoint of adhesion between the A layer and the B layer, the same acrylic polymer can be used as the base polymer for the A layer and the B layer. In such an embodiment, depending on whether or not to use materials other than the base polymer (crosslinking agent, tackifier, etc.) used to form each layer, the type, amount, etc., the characteristics at the measurement positions A and B and their ratio can be changed. can be adjusted.

The base polymer of the B layer is preferably crosslinked in the adhesive that constitutes the B layer. For example, by using a pressure-sensitive adhesive composition containing a base polymer and an appropriate cross-linking agent, it is possible to obtain a layer B composed of a pressure-sensitive adhesive in which the base polymer is cross-linked with the cross-linking agent. The type of cross-linking agent used in the B layer is not particularly limited, and can be appropriately selected from, for example, those exemplified above as cross-linking agents that can be used in the A layer. The cross-linking agent used for the A layer and the cross-linking agent used for the B layer may be the same type of cross-linking agent (e.g., the same or different isocyanate-based cross-linking agent), or different cross-linking agents (e.g., one of The other may be an epoxy-based cross-linking agent and an isocyanate-based cross-linking agent).

In some preferred embodiments, an epoxy-based cross-linking agent is used for the A layer, and an isocyanate-based cross-linking agent is used for the B layer. In general, an isocyanate-based cross-linking agent tends to form a more flexible cross-linked structure than an epoxy-based cross-linking agent. The agent layer can be suitably realized.

When an isocyanate-based cross-linking agent is used as the cross-linking agent for the B layer, the amount of the isocyanate-based cross-linking agent used relative to 100 parts by weight of the base polymer (for example, an acrylic polymer) of the B layer is not particularly limited, and the desired properties can be obtained. can be adjusted appropriately to In some aspects, the amount of the isocyanate-based cross-linking agent used relative to 100 parts by weight of the base polymer of the layer B is, for example, 0.1 part by weight or more and 20 parts by weight or less, preferably 1 part by weight or more and 10 parts by weight or less. , more preferably from 1 part by weight to 7 parts by weight, may be from 1 part by weight to 5 parts by weight, or may be from 2 parts by weight to 5 parts by weight.

A cross-linking catalyst may be used to promote the cross-linking reaction more effectively. Examples of cross-linking catalysts include metallic cross-linking catalysts such as tetra-n-butyl titanate, tetraisopropyl titanate, Nasem ferric, butyltin oxide, and dioctyltin dilaurate. The amount of cross-linking catalyst used is not particularly limited. In some embodiments, considering the balance between the speed of the crosslinking reaction and the length of the pot life of the pressure-sensitive adhesive composition, the amount of the crosslinking catalyst used relative to 100 parts by weight of the base polymer is, for example, 0.0001 parts by weight or more. It can be set to be no more than parts by weight (preferably 0.001 parts by weight or more and 0.5 parts by weight or less). The above crosslinking catalyst may be used in the A layer or in both the A layer and the B layer.

In some embodiments of the pressure-sensitive adhesive sheet disclosed herein, the T ₂ relaxation time (T _2s ) of the S component by pulse NMR of the B layer constituting the first pressure-sensitive adhesive layer is measured on the A layer of the pressure-sensitive adhesive layer. It is preferably longer than T _2s of the layer A from the viewpoint of improving the conformability to the surface shape of the adherend to be placed. The difference between the T _2s of the A layer and the T _2s of the B layer may be, for example, 5 μsec or more, advantageously 10 μsec or more, more preferably 15 μsec or more, more preferably 20 μsec or more. Preferably, it may be 25 μsec or longer, or 30 μsec or longer. In addition, from the viewpoint of preventing cohesive failure of the adhesive layer due to excessively long T _2s of the B layer, the difference between the T _2s of the A layer and the T _2s of the B layer is, for example, 70 μsec or less. It is preferably 60 μsec or less, more preferably 50 μsec or less, may be 40 μsec or less, or may be 35 μsec or less.

In some embodiments, the T _2s of the B layer is suitably larger than the T _2s of the A layer and 30 μsec or more (for example, 35 μsec or more, 40 μsec or more, or 45 μsec or more), and the surface shape of the adherend From the viewpoint of suitably exhibiting the effect of improving the followability, it is preferably longer than 45 μsec, may be 47 μsec or longer, or may be 50 μsec or longer. From the viewpoint of preventing cohesive failure of the B layer, _T2s of the B layer is suitably 80 μsec or less, preferably 70 μsec or less, may be 65 μsec or less, may be 60 μsec or less, and may be 57 μsec or less. It's okay.

In some aspects of the pressure-sensitive adhesive sheet comprising a pressure-sensitive adhesive layer configured to include an A layer and a B layer, the thickness of the B layer may be, for example, 3 μm or more, suitably 4 μm or more, and the surface From the viewpoint of enhancing the effect of imparting shape followability, the thickness is preferably 5 μm or more, may be 7 μm or more, may be 10 μm or more, or may be 15 μm or more. The upper limit of the thickness of the B layer is not particularly limited, and may be, for example, 300 μm or less, 250 μm or less, 150 μm or less, or 130 μm or less. From the viewpoint of suppressing the embedding of the semiconductor chip in the adhesive sheet in the mode of use in which the semiconductor chip is resin-sealed on the adhesive layer, the thickness of the layer B is suitably 100 μm or less, and 90 μm or less. It is preferably 70 μm or less, 50 μm or less, 30 μm or less, or 20 μm or less.

In a pressure-sensitive adhesive sheet comprising a pressure-sensitive adhesive layer configured to include layers A and B, the thickness of the layer A may be, for example, 1 μm or more and 20 μm or less. In some embodiments, the thickness of the A layer is suitably 15 μm or less, and preferably 10 μm or less, from the viewpoint of suitably exhibiting the effect of improving the surface shape followability due to the contribution of the B layer. Preferably, it may be 8 μm or less, or 6 μm or less. Moreover, from the viewpoint of suitably exhibiting the effect of suppressing component migration between the adhesive layer and the sealing resin due to the contribution of the A layer, in some embodiments, the thickness of the A layer is 2 μm or more. Advantageously, it is preferably greater than or equal to 3 μm, may be greater than or equal to 4 μm, and may be greater than or equal to 5 μm.

In a pressure-sensitive adhesive sheet comprising a pressure-sensitive adhesive layer configured to include an A layer and a B layer, the ratio (L2/L1) of the thickness L2 [μm] of the B layer to the thickness L1 [μm] of the A layer is particularly limited. can be, for example, about 0.5 to 100.0. In some aspects, the ratio (L2/L1) is suitably 0.5 or more, and 0.7, from the viewpoint of facilitating effective performance of each function of the A layer and the B layer. It is preferably 0.8 or more, 0.9 or more, or 1.0 or more. From the same point of view, the ratio (L2/L1) is suitably 50.0 or less, preferably 30.0 or less, may be 20.0 or less, or even 15.0 or less. It may be 10.0 or less, 5.0 or less, 3.0 or less, or 2.0 or less.

<Base material>
Examples of the base material of the pressure-sensitive adhesive sheet disclosed herein include resin sheets, nonwoven fabrics, paper, metal foils, woven fabrics, rubber sheets, foam sheets, laminates thereof (especially laminates containing resin sheets), and the like. obtain. Examples of the resin constituting the resin sheet include polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polybutylene terephthalate (PBT), polyethylene (PE), polypropylene (PP), ethylene-propylene copolymer, ethylene- Vinyl acetate copolymer (EVA), polyamide (nylon), wholly aromatic polyamide (aramid), polyimide (PI), polyvinyl chloride (PVC), polyphenylene sulfide (PPS), fluorine resin, polyether ether ketone (PEEK) ) and the like. Examples of nonwoven fabrics include nonwoven fabrics made of heat-resistant natural fibers such as nonwoven fabrics containing manila hemp; synthetic resin nonwoven fabrics such as polypropylene resin nonwoven fabrics, polyethylene resin nonwoven fabrics and ester resin nonwoven fabrics. Examples of metal foil include copper foil, stainless steel foil, and aluminum foil. Examples of paper include Japanese paper and kraft paper.

In some aspects, a resin sheet composed of a resin having a glass transition temperature (Tg) of 25°C or higher (preferably 40°C or higher, more preferably 50°C or higher) is preferably used as the substrate. By using such a resin sheet, the shape of the base material is maintained even by heating during the sealing process, and the semiconductor chip is prevented from being embedded in the adhesive sheet. The resin constituting such a resin sheet is preferably a polymer having an aromatic ring, and specific examples thereof include polyethylene terephthalate (PET), polyimide, polyethylene naphthalate and the like, but are not limited to these.

The thickness of the base material can be set to any appropriate thickness depending on the desired strength or flexibility, purpose of use, and the like. The thickness of the substrate is preferably 1000 µm or less, more preferably 25 µm or more and 1000 µm or less, still more preferably 40 µm or more and 500 µm or less, particularly preferably 60 µm or more and 300 µm or less, and most preferably 80 µm or more and 250 µm or less. is. In one embodiment, a substrate having a thickness of 25 μm or more is used. A base material having such a thickness is suitable for preventing embedding of a semiconductor chip in an adhesive sheet because the shape of the base material is easily maintained even when pressure is applied during the sealing process.

In one embodiment, the thickness of the substrate is 20% or more and 90% or less (preferably 20% or more and 89% or less, more preferably 20% or more and 88% or less) of the total thickness of the adhesive sheet. . In such a range, embedding of the semiconductor chip in the adhesive sheet can be suitably prevented.

The base material may be surface-treated. Examples of surface treatment include corona treatment, chromic acid treatment, ozone exposure, flame exposure, high voltage shock exposure, ionizing radiation treatment, and coating treatment with a primer.

An organic coating material may be used as the primer. Examples of the organic coating material include materials described in "Plastic Hard Coat Materials II" (published in 2004) by CMC Publishing. Urethane-based polymers are preferably used, more preferably polyacrylurethane, polyesterurethane, or precursors thereof. This is because it is easy to apply and apply to the substrate, and industrially, a wide variety of materials can be selected and are available at low cost. The urethane-based polymer is, for example, a polymer composed of a reaction mixture of an isocyanate monomer and an alcoholic hydroxyl group-containing monomer (for example, a hydroxyl group-containing acrylic compound or a hydroxyl group-containing ester compound). The organic coating material may contain optional additives such as chain extenders such as polyamines, anti-aging agents, oxidation stabilizers, and the like. The thickness of the organic coating layer is not particularly limited.

<Second adhesive layer>
A pressure-sensitive adhesive sheet according to some embodiments includes the base material, the pressure-sensitive adhesive layer disposed on one side of the base material, and a second pressure-sensitive adhesive layer disposed on the opposite side of the base material to the pressure-sensitive adhesive layer. a layer; A pressure-sensitive adhesive sheet having such a configuration (a double-sided pressure-sensitive adhesive sheet with a base material) is, for example, fixed on an appropriate carrier (for example, a SUS plate, a glass plate, etc.) using the second pressure-sensitive adhesive layer, and the first pressure-sensitive adhesive The resin encapsulation process can be performed on the agent layer, so it is convenient to use. The second pressure-sensitive adhesive layer may be a pressure-sensitive adhesive layer composed of any appropriate pressure-sensitive adhesive.

In the pressure-sensitive adhesive sheet according to some aspects, at least the surface of the second pressure-sensitive adhesive layer is composed of a pressure-sensitive adhesive containing thermally expandable microspheres. In the pressure-sensitive adhesive sheet of this aspect, the second pressure-sensitive adhesive layer and the adherend (for example, the carrier) can be easily bonded by heating the heat-expandable microspheres at an appropriate timing as necessary to expand the heat-expandable microspheres. It is preferable because it can be released at any time.

The adhesive containing heat-expandable microspheres may be a curable adhesive (for example, an active energy ray-curable adhesive) or a pressure-sensitive adhesive. Examples of pressure-sensitive adhesives include acrylic adhesives and rubber adhesives. Details of the adhesive contained in the second adhesive layer can be referred to, for example, the description of Japanese Patent Application Publication No. 2018-009050. The publication is incorporated herein by reference in its entirety.

Any appropriate heat-expandable microspheres can be used as the heat-expandable microspheres as long as they are microspheres that can be expanded or foamed by heating. As the heat-expandable microspheres, for example, microspheres in which a substance that easily expands by heating is encapsulated in an elastic shell can be used. Such heat-expandable microspheres can be produced by any appropriate method such as coacervation, interfacial polymerization, and the like.

Substances that easily expand when heated include, for example, propane, propylene, butene, normal butane, isobutane, isopentane, neopentane, normal pentane, normal hexane, isohexane, heptane, octane, petroleum ether, methane halides, and tetraalkylsilanes. low boiling point liquid such as; azodicarbonamide gasified by thermal decomposition; and the like.

Examples of substances constituting the shell include nitrile monomers such as acrylonitrile, methacrylonitrile, α-chloroacrylonitrile, α-ethoxyacrylonitrile, and fumaronitrile; acrylic acid, methacrylic acid, itaconic acid, maleic acid, fumaric acid, Carboxylic acid monomers such as citraconic acid; vinylidene chloride; vinyl acetate; methyl (meth) acrylate, ethyl (meth) acrylate, n-butyl (meth) acrylate, isobutyl (meth) acrylate, t-butyl (meth) acrylate, (Meth)acrylic acid esters such as isobornyl (meth)acrylate, cyclohexyl (meth)acrylate, benzyl (meth)acrylate, β-carboxyethyl acrylate; styrene monomers such as styrene, α-methylstyrene, chlorostyrene; acrylamide, substituted acrylamide , methacrylamide, substituted methacrylamide, and other amide monomers; A polymer composed of these monomers may be a homopolymer or a copolymer. Examples of the copolymer include vinylidene chloride-methyl methacrylate-acrylonitrile copolymer, methyl methacrylate-acrylonitrile-methacrylonitrile copolymer, methyl methacrylate-acrylonitrile copolymer, acrylonitrile-methacrylonitrile-itaconic acid copolymer, A polymer etc. are mentioned.

An inorganic foaming agent or an organic foaming agent may be used as the thermally expandable microspheres. Examples of inorganic foaming agents include ammonium carbonate, ammonium hydrogencarbonate, sodium hydrogencarbonate, ammonium nitrite, sodium borohydride, and various azides. Examples of organic foaming agents include chlorofluoroalkane compounds such as trichloromonofluoromethane and dichloromonofluoromethane; and azo compounds such as azobisisobutyronitrile, azodicarbonamide, and barium azodicarboxylate. hydrazine compounds such as paratoluenesulfonyl hydrazide, diphenylsulfone-3,3′-disulfonyl hydrazide, 4,4′-oxybis(benzenesulfonyl hydrazide), allylbis(sulfonyl hydrazide); p-toluylenesulfonyl semicarbazide, 4, Semicarbazide compounds such as 4'-oxybis(benzenesulfonyl semicarbazide); triazole compounds such as 5-morpholyl-1,2,3,4-thiatriazole; N,N'-dinitrosopentamethylenetetramine, N,N' -dimethyl-N,N'-dinitrosoterephthalamide; and other N-nitroso compounds.

Commercially available products may be used as the thermally expandable microspheres. Specific examples of commercially available heat-expandable microspheres include Matsumoto Yushi Seiyaku's trade name "Matsumoto Microspheres" (grades: F-30, F-30D, F-36D, F-36LV, F-50 , F-50D, F-65, F-65D, FN-100SS, FN-100SSD, FN-180SS, FN-180SSD, F-190D, F-260D, F-2800D), a product name manufactured by Nippon Philite Co., Ltd. " Expancel” (Grade: 053-40, 031-40, 920-40, 909-80, 930-120), Kureha Chemical Industry Co., Ltd. “Daiform” (Grade: H750, H850, H1100, S2320D, S2640D, M330, M430, M520), "Advancel" manufactured by Sekisui Chemical Co., Ltd. (grades: EML101, EMH204, EHM301, EHM302, EHM303, EM304, EHM401, EM403, EM501).

The particle size of the heat-expandable microspheres before heating is preferably 0.5 μm to 80 μm, more preferably 5 μm to 45 μm, even more preferably 10 μm to 20 μm, and particularly preferably 10 μm to 15 μm. . Therefore, the average particle size of the heat-expandable microspheres before heating is preferably 6 μm to 45 μm, more preferably 15 μm to 35 μm. The above particle size and average particle size are values determined by a particle size distribution measurement method in a laser scattering method.

The thickness of the adhesive layer composed of the adhesive containing heat-expandable microspheres is not particularly limited, and can be, for example, 3 μm or more. From the viewpoint of suppressing deterioration in the smoothness of the adhesive surface due to the inclusion of thermally expandable microspheres, the thickness of the adhesive layer is usually 7 μm or more, preferably more than 10 μm. , may be greater than 15 μm, may be greater than 25 μm, may be greater than 35 μm. Although the upper limit of the thickness of the pressure-sensitive adhesive layer is not particularly limited, it is usually suitable to be 300 μm or less, and may be 200 μm or less, 150 μm or less, 100 μm or less, or 70 μm or less. It is advantageous from the viewpoint of avoiding cohesive failure of the adhesive layer due to expansion of the heat-expandable microspheres that the thickness of the adhesive layer is not too large. In some aspects, the thickness of the adhesive layer may be 60 μm or less, 50 μm or less, or 45 μm or less.

The thickness Ta of the pressure-sensitive adhesive layer is preferably larger than the average particle diameter D of the thermally expandable microspheres before heating. That is, Ta/D is preferably greater than 1.0. From the viewpoint of smoothness of the adhesive surface, in some embodiments, Ta/D is preferably 2.0 or more, may be 3.0 or more, or may be 4.0 or more. In addition, from the viewpoint of facilitating the release effect due to the expansion of the heat-expandable microspheres, Ta/D is usually suitably 50 or less, preferably 20 or less, and may be 15 or less. It may be 10 or less.

It is preferable that the thermally expandable microspheres have an appropriate strength such that they do not burst until the volume expansion coefficient is preferably 5 times or more, more preferably 7 times or more, and still more preferably 10 times or more. When such heat-expandable microspheres are used, the adhesive strength can be efficiently reduced by heat treatment.

The content ratio of the heat-expandable microspheres in the pressure-sensitive adhesive containing the heat-expandable microspheres can be appropriately set according to the desired reduction in adhesive force. The content of the heat-expandable microspheres is, for example, 1-150 parts by weight, preferably 10-130 parts by weight, per 100 parts by weight of the base polymer of the pressure-sensitive adhesive containing the heat-expandable microspheres. and more preferably 20 to 100 parts by weight.

When the adhesive constituting the surface of the second adhesive layer contains thermally expandable microspheres, the arithmetic mean roughness of the surface of the second adhesive layer before the thermally expandable microspheres expand (that is, before heating) Ra is preferably 500 nm or less, more preferably 400 nm or less, and even more preferably 300 nm or less. Within such a range, it is possible to obtain a pressure-sensitive adhesive sheet having excellent adhesion to an adherend on the second pressure-sensitive adhesive layer side. The second pressure-sensitive adhesive layer having such excellent surface smoothness can be formed, for example, by setting the thickness of the pressure-sensitive adhesive layer within the above range, applying a pressure-sensitive adhesive composition containing heat-expandable microspheres to a release liner, and drying the composition. It can be obtained by, for example, transferring the pressure-sensitive adhesive layer formed on the substrate directly onto the substrate or onto an intermediate layer (for example, an elastic intermediate layer) provided on the substrate.

When the second pressure-sensitive adhesive layer contains heat-expandable microspheres, the pressure-sensitive adhesive layer is made of a base polymer having a dynamic storage modulus at 80° C. in the range of 5 kPa to 1 MPa (more preferably 10 kPa to 0.8 MPa). It preferably contains a structured adhesive. With such a pressure-sensitive adhesive layer, it is possible to form a pressure-sensitive adhesive sheet that has appropriate adhesiveness before heating and whose adhesive strength is likely to be reduced by heating. The dynamic storage modulus can be measured using a dynamic viscoelasticity measuring device (for example, product name "ARES" manufactured by Rheometrics Co., Ltd.) under measurement conditions of a frequency of 1 Hz and a heating rate of 10 ° C./min. .

<Method for manufacturing adhesive sheet>
The pressure-sensitive adhesive sheet of the invention can be produced by any appropriate method. The pressure-sensitive adhesive sheet of the present invention can be, for example, a pressure-sensitive adhesive layer (a first pressure-sensitive adhesive layer, a layer A or B constituting the first pressure-sensitive adhesive layer, a second pressure-sensitive adhesive layer, etc.)-forming component. A method of forming a pressure-sensitive adhesive layer by applying the agent composition directly to a substrate or to an intermediate layer (e.g., B layer, elastic intermediate layer, etc.) provided on the substrate, and any appropriate release property. A pressure-sensitive adhesive composition is applied onto a process material (for example, a release liner) to form a pressure-sensitive adhesive layer on the releasable process material, and the pressure-sensitive adhesive layer is transferred to a substrate or an intermediate layer on the substrate. methods, combinations thereof, and the like. The pressure-sensitive adhesive composition may be a solvent-based pressure-sensitive adhesive composition containing any suitable solvent.

When forming a pressure-sensitive adhesive layer containing heat-expandable microspheres, the pressure-sensitive adhesive layer is formed by applying a composition containing heat-expandable microspheres, a pressure-sensitive adhesive, and any appropriate solvent to a substrate. be able to. Alternatively, after sprinkling heat-expandable microspheres on the adhesive coating layer, the heat-expandable microspheres are embedded in the adhesive using a laminator or the like to form an adhesive layer containing the heat-expandable microspheres. may be formed.

Any appropriate coating method can be adopted as the coating method for the adhesive and each composition. For example, each layer can be formed by coating and then drying. Examples of the coating method include coating methods using a multi-coater, die coater, gravure coater, applicator, and the like. Drying methods include, for example, natural drying and heat drying. The heating temperature for drying by heating can be set to any suitable temperature depending on the properties of the substance to be dried.

Although some examples of the present invention will be described below, it is not intended to limit the present invention to those shown in such specific examples. In the following description, "parts" and "%" are by weight unless otherwise specified.

<Evaluation method>
1. Indentation hardness Using a nanoindenter manufactured by Hysitron under the product name "Triboindenter TI-950", the indentation hardnesses H1 and H2 were measured by the method described above.

2. Stringiness Using a nanoindenter manufactured by Hysitron under the product name "Triboindenter TI-950", the stringiness D1 and D2 were measured by the method described above.

3. Swelling test Using a syringe (syringe diameter: 22 mm), 0.02 g of 4-t-butylphenylglycidyl ether (TBPGE) was dropped onto the surface of the first adhesive layer, and the temperature was maintained at 23°C and 50% RH for 1 minute. left undisturbed. After removing the TBPGE remaining on the surface of the pressure-sensitive adhesive layer by absorbing it with a waste cloth, the thickness T1 [μm] of the pressure-sensitive adhesive layer at the point where the TBPGE was dropped is measured. From the thickness (initial thickness) T0 [μm] of the adhesive layer at the relevant location before TBPGE is dropped and the thickness T1 [μm], the amount of change in thickness and the rate of change in thickness of the adhesive layer are obtained by the following formula. was calculated.
Thickness change amount [μm] = T1-T0
Thickness change rate [%] = ((T1-T0) / T0) × 100

4. TMA sinking amount Using a thermomechanical analyzer manufactured by TA Instruments, product name "TMA Q400", probe: needle insertion (columnar, tip diameter 1 mmΦ), nitrogen gas flow rate: 50.0 ml / min, indentation load: The amount of sinking from the surface of the first pressure-sensitive adhesive layer was measured under the conditions of 0.01N, measurement atmosphere temperature: 23.0°C, and indentation load time: 60 minutes. The measurement was performed with N=5, and the average value of N=3 obtained by removing the maximum and minimum values from these measured values was taken as the amount of TMA sinking.
In addition, when the pressure-sensitive adhesive sheet has a pressure-sensitive adhesive layer (first pressure-sensitive adhesive layer) only on one side of the substrate and does not have a second pressure-sensitive adhesive layer on the opposite side (back side) of the substrate, the pressure-sensitive adhesive For the sheet, 10 parts of a tackifier is added to 100 parts of the acrylic polymer of the standard adhesive layer (EA/2EHA/MMA/HEA = 30/70/5/5 (weight ratio)) described above on the back side of the base material. parts, 2 parts of an isocyanate cross-linking agent, and 30 parts of thermally expandable microspheres (thickness: 45 μm).

5. Relaxation Time About 100 mg of the adhesive was sampled from the adhesive layer constituting the _A layer by picking, and a T2 relaxation curve was obtained by pulse NMR measurement using this as a measurement sample. Fitting was performed using analysis software (TDNMR-A) using the above equation (1), and the T ₂ relaxation time of the S component was obtained by approximation to one component (α) and analysis. In addition, all Wa was analyzed as 1. The shortest relaxation time calculated by the above analysis method was taken as the T ₂ relaxation time (T _2s ) of the S component by pulse NMR of the A layer. Similarly, the T ₂ relaxation time (T _2s ) of the S component of the B layer was determined by pulse NMR. In addition, the pulse NMR measurement was performed using a time domain NMR device manufactured by Bruker, the device name "TD-NMR the minispec mq20", with a 90 ° pulse width of 2.1 µs, a repetition time of 1 second, and the number of integrations of 32 times. A solid echo method was used at a temperature of 30°C.

6. Adhesion to PET The adhesive sheet is cut into a size of 20 mm in width and 140 mm in length, and the entire surface of the back side (the side opposite to the side where the first adhesive layer is provided) is coated with double-sided adhesive tape (Nitto Denko Co., Ltd. , trade name "No. 531") to a SUS304 plate using a 2-kg hand roller. Regarding the pressure-sensitive adhesive sheet having the second pressure-sensitive adhesive layer on the back side of the base material, the above No. Instead of using the 531 double-sided adhesive tape, the back side of the pressure-sensitive adhesive sheet was adhered to the SUS304 plate via the second pressure-sensitive adhesive layer.
In an environment of 23° C. and 50% RH, a polyethylene terephthalate (PET) film (manufactured by Toray Industries, Inc., product name “Lumirror S-10", thickness 25 μm, width 30 mm) was pasted by reciprocating a 2 kg roller once. After leaving this for 30 minutes in the above environment, a tensile tester was used to measure the load when the PET film was peeled from the adhesive sheet under the conditions of a peeling angle of 180 degrees and a tensile speed of 300 mm / min. The average load at the time was defined as the adhesive strength of the adhesive sheet to PET. As the tensile tester, a trade name "Autograph AG-120kN" manufactured by Shimadzu Corporation was used.

7. Anchor force after heating Cut the adhesive sheet into a size of 20 mm in width and 140 mm in length, and apply double-sided adhesive tape (Nitto Denko Co., Ltd. , trade name "No. 531") to a SUS304 plate using a 2-kg hand roller. Regarding the pressure-sensitive adhesive sheet having the second pressure-sensitive adhesive layer on the back side of the base material, the above No. Instead of using the 531 double-sided adhesive tape, the pressure-sensitive adhesive sheet was adhered to the SUS304 plate via the second pressure-sensitive adhesive layer. After holding this in an environment of 150° C. for 1 hour, it was allowed to stand in an environment of 23° C. and 50% RH for 2 hours. Next, in an environment of 23° C. and 50% RH, a cutter knife is used to cut a depth from the surface of the first adhesive layer to the surface of the substrate, and a commercially available acrylic adhesive tape (Nitto Denko Co., Ltd., trade name: No. 315) was crimped by one reciprocation of a 2 kg roller, and allowed to stand for 30 minutes. After that, using the tensile tester, the load when the acrylic adhesive tape was peeled off was measured under the conditions of a peeling angle of 180 degrees and a tensile speed of 50 mm/min, and the maximum load at that time was recorded as the anchoring force after heating. bottom.

8. Adhesive strength to encapsulating resin Cut the adhesive sheet into a size of 50 mm in width and 140 mm in length, and attach a mold (opening size: 35 mm in width, 90 mm in length, thickness: 564 μm) on the first adhesive layer. Matched. After spraying a granular epoxy resin-based sealing material (Sumitomo Bakelite Co., Ltd., G730) in the mold so that the thickness of the resin after curing is 0.3 mm, cover it with a silicone-treated release liner, Using "hydraulic molding machine NS-VPF-50" manufactured by Najo Press Co., Ltd., temperature 145 ° C., molding time 600 seconds, pressure condition 0.3 MPa (300 mm square stage size), vacuum time 600 seconds, degree of vacuum The sealing resin was heat-molded on the first adhesive layer under the condition of −0.1 MPa. This is heated at 150° C. for 7 hours to cure the sealing resin, and then allowed to stand in an environment of 23° C. and 50% RH for 2 hours, after which the sealing resin and the first adhesive layer are in contact. A sample for evaluation was prepared by cutting the portion into a size of 20 mm in width and 88 mm in length. After leaving this evaluation sample in an environment of 23° C. and 50% RH for 30 minutes, the pressure-sensitive adhesive sheet was peeled off from the sealing resin under the conditions of a peeling angle of 180 degrees and a tensile speed of 300 mm/min using the above tensile tester. The load at the time of pressing was measured, and the average load at that time was defined as the adhesive strength of the adhesive sheet to the encapsulating resin.

9. Adhesive Residue Prevention Property In the measurement of the encapsulating resin adhesive strength, presence or absence of adhesive residue on the encapsulating resin after peeling off the adhesive sheet was visually observed. Based on the results, when adhesive residue is observed, the adhesive residue prevention property is “P” (Poor: Poor adhesive residue prevention property), and when no adhesive residue is observed, the adhesive residue prevention property is rated “G” (Good). : good adhesive residue prevention).

10. Mold flash evaluation On the first adhesive surface of the adhesive sheet, the resin sealing process of the semiconductor chip (Si chip) was performed under the following conditions, and the encapsulation resin entered the interface between the chip and the encapsulation resin (mold flash). ) was evaluated for its ability to prevent
Carrier: SUS carrier (220mmΦ)
Chip: Dummy chip with steps (dummy chip with a copper pad on one side of a 7 mm × 7 mm × 400 μm thick silicon substrate (target pad height: 5.5 μm, mask: GNC-300 mm-G03-A-300S). Global Net Co., Ltd. made)
Bonding device: FC3000W manufactured by Toray Engineering Co., Ltd.
Bonding conditions: crimping time 6 seconds, crimping pressure 10N, crimping temperature: 23°C
Sealing equipment: MS-150HP manufactured by Apic Yamada
Sealing resin: G730 manufactured by Sumitomo Bakelite Co., Ltd.
Preheating conditions: 130°C x 30 seconds Time from preheating to start of sealing: 1 hour Sealing temperature: 145°C
Vacuum time: 5 seconds Sealing time: 600 seconds Clamping force: 3.6 MPa
Encapsulation thickness: 600 μm

The sealing work was carried out according to the following procedure.
1) The back side of the adhesive sheet was attached to a SUS carrier via an adhesive layer containing thermally expandable microspheres (attachment conditions: 23°C atmosphere, attachment cylinder pressure 0.1 MPa, attachment speed 0.5 m/ min).
As the pressure-sensitive adhesive layer containing the heat-expandable microspheres, for a pressure-sensitive adhesive sheet having a structure having a second pressure-sensitive adhesive layer containing heat-expandable microspheres on the back side of the substrate, the second pressure-sensitive adhesive layer is I used it as is. For a pressure-sensitive adhesive sheet that does not have a second pressure-sensitive adhesive layer on the back side of the substrate, the standard pressure-sensitive adhesive layer described above (100 parts of acrylic polymer and thermally expandable microspheres (Matsumoto Yushi Pharmaceutical Co., Ltd., trade name "Matsumoto Microsphere F-190D")) to form an adhesive layer containing 30 parts (thickness 45 μm), and the back side of the adhesive sheet is attached to SUS through the standard adhesive layer. fixed to the carrier.
2) On the first adhesive layer of the adhesive sheet fixed to the SUS carrier, using the bonding apparatus, a total of 25 dummy chips with steps are formed in eight radial straight lines with a central angle of 45 degrees. , so that the intervals gradually widen from the center toward the outer periphery. The direction of the chip was such that the stepped surface (pad forming surface) of the chip faced the first adhesive layer.
3) A SUS carrier having stepped dummy chips disposed on the first adhesive layer of the adhesive sheet was preheated under predetermined conditions.
4) After preheating, the dummy chip was allowed to stand for 1 hour in an environment of 23° C. and 50% RH, and then a predetermined sealing resin was evenly spread over the dummy chip by hand to obtain a predetermined sealing facility and sealing conditions. and sealed.
5) The resulting laminate was heated at 150° C. for 4 hours to cure the sealing resin.
6) After the heat-cured laminate is left in an environment of 23°C and 50% RH for 5 days, the heat in the adhesive layer fixing the adhesive sheet to the SUS carrier is removed by heating on a hot plate. The expandable microspheres were expanded to separate the SUS carrier from the laminate.
7) After separating the SUS carrier, the adhesive sheet was peeled off from the laminate to obtain a structure composed of the sealing resin and the stepped dummy chip.

The surface of the structure that was in contact with the first adhesive surface was observed with a laser confocal microscope (OLS-4000 manufactured by Olympus) to confirm whether or not the sealing resin had penetrated onto the stepped dummy chip. When a residue of the adhesive (adhesive residue) or the like was observed on the surface, the residue was removed with toluene and then observed. As a result, "P" (poor: poor mold flash prevention) was observed when the encapsulation resin entered any of the dummy chips, and no encapsulation resin entered any of the dummy chips. In this case, it was judged as "G" (Good: good mold flash prevention property).

11. Standoff evaluation On the first adhesive surface of the adhesive sheet, a semiconductor chip (Si chip ) was carried out to obtain a structure composed of a sealing resin and a Si mirror chip.
For this structure, the surface that was in contact with the first adhesive surface was observed with a laser confocal microscope (OLS-4000 manufactured by OLYMPUS), and the Si chip and the sealing on the surface were focused on the Si chip placed in the center. The step height (standoff height) at the resin interface was measured. When a residue of the adhesive (adhesive residue) or the like was found on the surface, measurement was performed after removing the residue using toluene. As a result, when the standoff height was less than 3.3 μm, “G” (Good: standoff is well suppressed), and when it was 3.3 μm or more, “P” (Poor: standoff height Insufficient suppression of off).

<Example 1>
In a toluene solution containing 100 parts of polymer P1 (acrylic polymer composed of monomer components of 2-ethylhexyl acrylate (2EHA)/acrylic acid (AA) = 95/5 (weight ratio), SP value 19.3), 5 parts of an epoxy-based cross-linking agent (manufactured by Mitsubishi Gas Chemical Co., Ltd., trade name "Tetrad C") and toluene for dilution (100 parts in total) were added and mixed to prepare an adhesive composition 1a. This pressure-sensitive adhesive composition 1a was applied to a release film R1 (manufactured by Toray Advanced Film Co., Ltd., trade name “Therapeel MDAR”, thickness 38 μm) made of polyethylene terephthalate (PET) and one side of which was subjected to release treatment with a silicone-based release agent. and dried to form an adhesive layer 1A (thickness L1=10 μm) on the release film R1.
A pressure-sensitive adhesive composition 1b was prepared in the same manner as the pressure-sensitive adhesive composition 1a, except that 5 parts of the epoxy-based cross-linking agent was changed to 3 parts of an isocyanate-based cross-linking agent (manufactured by Tosoh Corporation, trade name "Coronate L"). . The pressure-sensitive adhesive composition 1b is applied to one side of a PET film (manufactured by Toray Industries, Inc., trade name “Lumirror S10”, thickness 38 μm) as a substrate and dried to form a pressure-sensitive adhesive layer on one side of the substrate. 1B (thickness L2=10 μm) was formed.
By bonding the adhesive surface of the adhesive layer 1A formed on the release film R1 to the adhesive surface of the adhesive layer 1B, the first adhesive layer composed of the adhesive layer 1B and the adhesive layer 1A is formed as described above. A pressure-sensitive adhesive sheet arranged on one side of the substrate (a pressure-sensitive adhesive sheet having a configuration of substrate/adhesive layer 1B (B layer)/adhesive layer 1A (A layer)) was obtained.

<Example 2>
Base material/adhesive layer 2B (B layer)/adhesive layer 2A (A layer ) was obtained.

<Example 3>
Polymer P2 (n-butyl acrylate (BA) / ethyl acrylate (EA) / AA = 50/50/5 (weight ratio) acrylic polymer composed of monomer components, SP value 19.6) 100 parts To the toluene solution, 5 parts of an epoxy-based cross-linking agent (manufactured by Mitsubishi Gas Chemical Co., Ltd., trade name "Tetrad C") and toluene for dilution (100 parts in total) were added and mixed to form an adhesive composition 3a. was prepared. The pressure-sensitive adhesive composition 3a was applied to the release-treated surface of the release film R1 and dried to form a pressure-sensitive adhesive layer 3A (thickness L1=5 μm) on the release film R1.
A pressure-sensitive adhesive composition 3b was prepared in the same manner as the pressure-sensitive adhesive composition 3a, except that 5 parts of the epoxy-based cross-linking agent was changed to 3 parts of an isocyanate-based cross-linking agent (manufactured by Tosoh Corporation, trade name "Coronate L"). . This adhesive composition 3b is applied to one side of a PET film (manufactured by Toray Industries, Inc., trade name “Lumirror S10”, thickness 38 μm) as a substrate and dried to form an adhesive layer on one side of the substrate. 3B (thickness L2=35 μm) was formed.
By bonding the adhesive surface of the adhesive layer 3A formed on the release film R1 to the adhesive surface of the adhesive layer 3B, the substrate / adhesive layer 3B (B layer) / adhesive layer 3A (A layer) ) was obtained.

<Example 4>
In the same manner as in Example 3 except that the thicknesses of the A layer and the B layer were as shown in Table 1, an adhesive having a structure of substrate / adhesive layer 4B (B layer) / adhesive layer 4A (A layer) got a sheet.

<Example 5>
Acrylic polymer composed of monomer components of polymer P3 (EA/2EHA/methyl methacrylate (MMA)/2-hydroxyethyl acrylate (HEA)=30/70/5/4 (weight ratio) SP value 20. 7) To a toluene solution containing 100 parts, 30 parts of thermally expandable microspheres (manufactured by Matsumoto Yushi Seiyaku Co., Ltd., trade name "Matsumoto Microsphere F-190D") and an isocyanate cross-linking agent (manufactured by Tosoh Corporation, trade name " Coronate L") 1.4 parts, 10 parts of a tackifier (manufactured by Yasuhara Chemical Co., Ltd., trade name "Mighty Ace G125"), and toluene for dilution (total amount of 100 parts) are added and mixed to obtain adhesion. Agent composition 5c was prepared. The pressure-sensitive adhesive composition 5c was applied to the release-treated surface of the release film R1 and dried to form a pressure-sensitive adhesive layer 5C (thickness: 45 µm) on the release film R1.
By bonding the adhesive surface of the adhesive layer 5C formed on the release film R1 to the back surface of the substrate of the adhesive sheet according to Example 4, the adhesive layer 5C (second adhesive layer)/substrate/adhesive A double-sided pressure-sensitive adhesive sheet having a structure of agent layer 4B (layer B)/pressure-sensitive adhesive layer 4A (layer A) was obtained.

<Example 6>
To a toluene solution containing 100 parts of polymer P3, 1.5 parts of an isocyanate cross-linking agent (manufactured by Tosoh Corporation, trade name "Coronate L") and 10 parts of a tackifier (manufactured by Yasuhara Chemical Co., Ltd., trade name "Mighty Ace G125"). and toluene for dilution (total amount of 100 parts) were added and mixed to prepare an adhesive composition 6a. The pressure-sensitive adhesive composition 6c was applied to the release-treated surface of the release film R1 and dried to form a pressure-sensitive adhesive layer 6A (thickness: 30 µm) on the release film R1.
To a toluene solution containing 100 parts of polymer P3, 1 part of an isocyanate-based cross-linking agent (manufactured by Tosoh Corporation, trade name "Coronate L") and toluene for dilution (total amount of 100 parts) are added and mixed to form an adhesive. Agent composition 6b was prepared. The pressure-sensitive adhesive composition 6b is applied to one side of a PET film (manufactured by Toray Industries, Inc., product name “Lumirror S10”, thickness 38 μm) as a substrate and dried to form a pressure-sensitive adhesive layer on one side of the substrate. 6B (thickness L2=20 μm) was formed.
By bonding the adhesive surface of the adhesive layer 6A formed on the release film R1 to the adhesive surface of the adhesive layer 6B, the substrate/adhesive layer 6B (B layer)/adhesive layer 6A (A layer) ) was obtained.

<Example 7>
Polymer P4 (2EHA/acryloylmorpholine (ACMO)/HEA = 75/25/22 (molar ratio) acrylic polymer composed of monomer components, 11 mol of 2-isocyanatoethyl methacrylate per 22 mol of HEA To a toluene solution containing 100 parts of an acrylic polymer obtained by modifying Karenz MOI (manufactured by Showa Denko), 5 parts of an isocyanate cross-linking agent (manufactured by Tosoh Corporation, trade name "Coronate L") and UV curing 10 parts of a reactive oligomer (manufactured by Toagosei Co., Ltd., trade name "Aronix M321"), 3 parts of a photoinitiator (manufactured by IGM Resins, trade name "Omnirad 651"), and ethyl acetate for dilution are added and mixed, An adhesive composition 7a was prepared. The pressure-sensitive adhesive composition 7a was applied to the release-treated surface of the release film R1 and dried to form a pressure-sensitive adhesive layer 7A (thickness L1=5 μm) on the release film R1.
To a toluene solution containing 100 parts of polymer P2, 1 part of an isocyanate cross-linking agent (manufactured by Tosoh Corporation, trade name "Coronate L") and 10 parts of UV curable oligomer (manufactured by Toagosei Co., Ltd., trade name "Aronix M321") , 3 parts of a photoinitiator (manufactured by IGM Resins, trade name "Omnirad 651") and ethyl acetate for dilution were added and mixed to prepare an adhesive composition 7b. This adhesive composition 7b is applied to one side of a PET film (manufactured by Toray Industries, Inc., product name “Lumirror S10”, thickness 38 μm) as a substrate and dried to form an adhesive layer on one side of the substrate. 7B (thickness L2=150 μm) was formed.
By bonding the adhesive surface of the adhesive layer 7A formed on the release film R1 to the adhesive surface of the adhesive layer 7B, the substrate/adhesive layer 7B (B layer)/adhesive layer 7A (A layer) ) was obtained.

The obtained adhesive sheet was evaluated by the method described above. Table 1 shows the results. In addition, in the measurement of the anchoring force after heating, peeling progressed at the interface between the acrylic adhesive tape and the adhesive surface of the measurement target, and anchoring failure between the substrate (PET film) was not observed. .

As shown in Table 1, the pressure-sensitive adhesive sheets of Examples 1 to 5 having an indentation hardness H1 of 0.10 MPa or more and 0.50 MPa or less and an indentation hardness H2 of 0.001 MPa or more and 0.090 MPa or less were molded. The flash prevention property was good, and the adhesive residue prevention property was also good.

Specific examples of the present invention have been described in detail above, but these are merely examples and do not limit the scope of the claims. The technology described in the claims includes various modifications and changes of the specific examples illustrated above.

1: Semiconductor chip 2: Sealing resin 10: Base material (base film)
20: Adhesive layer (first adhesive layer)
22: A layer 24: B layer 30: Second

adhesive layer

100, 200, 300: Adhesive sheet A: Measurement position A
B: Measurement position B

Claims

A pressure-sensitive adhesive sheet comprising a base material and a pressure-sensitive adhesive layer disposed on at least one side of the base material,
In indentation hardness measurement with a nanoindenter, the indentation hardness H1 of the surface of the adhesive layer is 0.10 MPa or more and 0.50 MPa or less, and the surface of the adhesive layer from the base material in the cross section of the adhesive sheet A pressure-sensitive adhesive sheet having an indentation hardness H2 of 0.001 MPa or more and 0.090 MPa or less measured at a position with a distance of 4 μm on the side.
The pressure-sensitive adhesive sheet according to claim 1, wherein the ratio (H2/H1) of the indentation hardness H2 [MPa] to the indentation hardness H1 [MPa] is 0.002 or more and 0.90 or less.
In evaluation of stringiness by a nanoindenter, the stringiness D1 of the surface of the pressure-sensitive adhesive layer is 50 nm or more and 500 nm or less, and the distance from the substrate to the surface side of the pressure-sensitive adhesive layer in the cross section of the pressure-sensitive adhesive sheet is 4 μm. The pressure-sensitive adhesive sheet according to claim 1 or 2, wherein the stringiness D2 measured at the position of is 150 nm or more and 1000 nm or less.
The pressure-sensitive adhesive sheet according to claim 3, wherein the ratio (D2/D1) of the stringiness D2 [nm] to the stringiness D1 [nm] is 0.3 or more and 20.0 or less.
The thickness T1 [μm] of the adhesive layer after 4-t-butylphenyl glycidyl ether is dropped on the surface of the adhesive layer and allowed to stand for 1 minute, and the initial thickness T0 [μm] of the adhesive layer The pressure-sensitive adhesive sheet according to any one of claims 1 to 4, wherein the difference between (T1-T0) is 20 µm or less.
The sinking amount of the penetrating probe from the pressure-sensitive adhesive layer surface measured using a thermomechanical analyzer under the conditions of a measurement environment temperature of 23° C., an indentation load of 0.01 N, and an indentation load time of 60 minutes is 3.50 μm or more 20 The pressure-sensitive adhesive sheet according to any one of claims 1 to 5, which has a thickness of 0.0 μm or less.
The pressure-sensitive adhesive sheet according to any one of claims 1 to 6, wherein the pressure-sensitive adhesive layer has a thickness of 5 µm or more and 110 µm or less.
The pressure-sensitive adhesive sheet according to any one of claims 1 to 7, wherein the base material is a base film made of a resin material having a glass transition temperature of 25°C or higher.
The pressure-sensitive adhesive sheet according to any one of claims 1 to 8, which has an adhesive strength to a polyethylene terephthalate film of 0.05 N/20 mm or more and 1.00 N/20 mm or less.
Any one of claims 1 to 9, wherein the anchoring force of the adhesive layer to the substrate measured at 23 ° C. after heating the adhesive sheet at 150 ° C. for 1 hour is 4.00 N / 20 mm or more. Adhesive sheet described.
The pressure-sensitive adhesive sheet according to any one of claims 1 to 10, wherein the pressure-sensitive adhesive constituting at least the surface of the pressure-sensitive adhesive layer is an acrylic pressure-sensitive adhesive having an acrylic polymer as a base polymer.
The adhesive sheet according to claim 11, wherein the acrylic polymer has an SP value of 18.0 to 20.0.
Claims 1 to 12, wherein the pressure-sensitive adhesive layer comprises a layer A constituting the surface of the pressure-sensitive adhesive layer, and a layer B disposed between the layer A and the substrate and adjacent to the substrate. The pressure-sensitive adhesive sheet according to any one of .
The pressure-sensitive adhesive sheet according to claim 13, wherein the thickness L1 of the layer A is 1 µm or more and 10 µm or less.
The pressure-sensitive adhesive sheet according to claim 13 or 14, wherein the thickness L2 of the layer B is 4 µm or more and 100 µm or less.
The ratio (L2/L1) of the thickness L2 [μm] of the B layer to the thickness L1 [μm] of the A layer is 1.0 to 100.0, according to any one of claims 13 to 15 Adhesive sheet described.
14. The T2 relaxation time ( T2s ) of the S component by pulse NMR of the A layer is 45 μsec or less, and the T2 relaxation time ( T2s ) of the S component by pulse NMR of the B layer is longer than 45 μsec. 17. The pressure-sensitive adhesive sheet according to any one of 16.
The pressure-sensitive adhesive sheet according to any one of claims 13 to 17, wherein the A layer is crosslinked with an epoxy-based crosslinking agent, and the B-layer is crosslinked with an isocyanate-based crosslinking agent.
The substrate, the adhesive layer arranged on one side of the substrate, and a second adhesive layer arranged on the opposite side of the substrate to the adhesive layer,
The pressure-sensitive adhesive sheet according to any one of claims 1 to 18, wherein at least the surface of the second pressure-sensitive adhesive layer is composed of a pressure-sensitive adhesive containing heat-expandable microspheres.