Adhesive sheet and method for manufacturing semiconductor device

Abstract

The present invention provides an adhesive sheet and a method for producing a semiconductor device using the adhesive sheet, wherein the adhesive sheet has a laminated structure including an adhesive layer (X1) and a substrate layer (Y), at least one of the adhesive layer (X1) and the substrate layer (Y) is a heat-expandable layer containing heat-expandable particles, and a surface (S) of the adhesive layer (X1) is X1 ) has an arithmetic mean waviness (Wa) of 0.090 μm or less, and the surface (S X1 ) is a surface on the opposite side to the surface facing the substrate layer (Y).

Description

Technical Field

[0001] The present invention relates to an adhesive sheet and a method for manufacturing a semiconductor device using the adhesive sheet. Background Art

[0002] Adhesive sheets are not only used for semi-permanently fixing components, but are also sometimes used as temporary fixing sheets to temporarily fix components (hereinafter also referred to as "adherends") that are being processed or inspected during the processing or inspection of building materials, interior materials, electronic components, etc. For example, temporary fixing sheets are used when processing semiconductor wafers during the manufacturing process of semiconductor devices.

[0003] In the manufacturing process of semiconductor devices, semiconductor wafers are processed into semiconductor chips through a grinding process in which the thickness is reduced by grinding, a singulation process in which the semiconductor wafer is cut and separated, and singulation is carried out. At this time, the semiconductor wafer is subjected to a given processing while being temporarily fixed to a temporary fixing sheet. For the semiconductor chip obtained by implementing the given processing, after being separated from the temporary fixing sheet, a sheet expansion process in which the intervals between the semiconductor chips are expanded, a rearrangement process in which a plurality of semiconductor chips with expanded intervals are arranged, a flipping process in which the front and back sides of the semiconductor chip are flipped, etc. are appropriately implemented as needed, and then the semiconductor chip is installed on the substrate. In each of the above-mentioned steps, a temporary fixing sheet suitable for each purpose can also be used. As such a temporary fixing sheet, a single-sided adhesive sheet or a double-sided adhesive sheet can be used. In the case of a double-sided adhesive sheet, a given processing is sometimes carried out in a state in which the object to be processed is affixed to one side and the other side is affixed to a support.

[0004] Patent Document 1 discloses a heat-peelable adhesive sheet for temporarily fixing electronic components when they are cut, wherein a heat-expandable adhesive layer containing heat-expandable microspheres is provided on at least one side of a substrate. The document describes the following: The heat-peelable adhesive sheet ensures a predetermined contact area with the adherend when the electronic component is cut, thereby exhibiting adhesion properties that prevent poor adhesion, such as chip scattering. Furthermore, after use, the heat-expandable microspheres are expanded by heating to reduce the contact area with the adherend, thereby facilitating peeling.

[0005] Prior art literature

[0006] Patent Literature

[0007] Patent Document 1: Japanese Patent No. 3594853 Summary of the Invention

[0008] Problems to be solved by the invention

[0009] When a temporary fixing sheet is used to perform a predetermined process on an object with the object attached to one side and a support attached to the other side, a hard material may be attached to both sides of the temporary fixing sheet. In this case, for example, when attaching a hard support to a temporary fixing sheet attached to a hard object, the temporary fixing sheet and the support must be attached with the attachment surfaces substantially parallel to each other.

[0010] Compared with the method that temporarily fixing is pasted with sheet bending limit, the method that temporarily fixing is pasted with sheet and adherend under the state of keeping substantially parallel easily produces air stagnation at the bonding interface of temporary fixing sheet and adherend.And the air stagnation at the bonding interface can become the reason of vibration, misalignment etc. of adherend, when processing object is processed, can become the reason that causes processing accuracy to decline etc. such as rupture, defect generation.On the other hand, when adherend is pasted on temporary fixing sheet, from the viewpoint of productivity and suppression of the breakage and deterioration of the adherend caused by pressurization and heating, should avoid being set to harsh in order to improve adhesiveness, preferably paste under gentle condition as far as possible.Therefore, although excellent adhesiveness is required for temporary fixing sheet itself, the heat peelable adhesive sheet of patent documentation 1 is not an adhesive sheet that fully satisfies this requirement.

[0011] The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to provide an adhesive sheet having excellent adhesiveness and a method for manufacturing a semiconductor device using the adhesive sheet.

[0012] Solutions to the Problem

[0013] The present inventors focused on the arithmetic mean waviness (Wa) of the surface of a PSA sheet and found that the above-mentioned problems can be solved by adjusting the arithmetic mean waviness (Wa) to a specific range, thereby completing the present invention.

[0014] That is, the present invention relates to the following [1] to

[13] .

[0015] [1] A pressure-sensitive adhesive sheet having a laminate structure comprising a pressure-sensitive adhesive layer (X1) and a substrate layer (Y),

[0016] At least one of the adhesive layer (X1) and the base layer (Y) is a heat-expandable layer containing heat-expandable particles.

[0017] The surface (S) of the adhesive layer (X1) X1 ) has an arithmetic mean waviness (Wa) of 0.090 μm or less, and the surface (S X1 ) is a surface on the opposite side to the surface facing the above-mentioned base material layer (Y).

[0018] [2] The adhesive sheet according to [1], wherein the thickness of the heat-expandable layer before thermal expansion is 30 to 300 μm.

[0019] [3] The pressure-sensitive adhesive sheet according to [1] or [2], wherein the content of the heat-expandable particles in the heat-expandable layer is 1 to 25% by mass relative to the total mass (100% by mass) of the heat-expandable layer.

[0020] [4] The pressure-sensitive adhesive sheet according to any one of [1] to [3], wherein the expansion starting temperature (t) of the heat-expandable particles is 50°C or higher and lower than 125°C.

[0021] [5] The adhesive sheet according to any one of [1] to [4] above, wherein the substrate layer (Y) is a substrate laminate formed by laminating a heat-expandable substrate layer (Y1) containing heat-expandable particles and a non-heat-expandable substrate layer (Y2), and the adhesive sheet has a laminated structure in which the adhesive layer (X1), the heat-expandable substrate layer (Y1) and the non-heat-expandable substrate layer (Y2) are arranged in this order.

[0022] [6] The adhesive sheet according to any one of [1] to [5], further comprising an adhesive layer (X2), wherein the adhesive sheet has a laminated structure in which the adhesive layer (X1), the substrate layer (Y), and the adhesive layer (X2) are arranged in this order.

[0023] [7] The adhesive sheet according to [6], wherein the adhesive layer (X2) is an energy-ray-curable adhesive layer that is cured by irradiation with energy rays, thereby causing a decrease in adhesive strength.

[0024] [8] A method for manufacturing a semiconductor device using the adhesive sheet described in [6] or [7], comprising the following steps 1A, 2A, a first separation step, and a second separation step.

[0025] Step 1A: a step of attaching an object to the adhesive layer (X2) of the adhesive sheet and attaching a support to the adhesive layer (X1) of the adhesive sheet

[0026] Step 2A: A step of performing one or more treatments selected from grinding and singulation on the object to be processed.

[0027] First separation step: a step of heating the adhesive sheet to a temperature higher than the expansion starting temperature (t) of the heat-expandable particles to separate the adhesive layer (X1) from the support

[0028] Second separation step: a step of separating the adhesive layer (X2) from the object to be processed

[0029] [9] The method for manufacturing a semiconductor device according to [8] above, wherein the expansion starting temperature (t) of the thermally expandable particles is 50°C or higher and lower than 125°C,

[0030] After the above step 2A, a step 3A of attaching a thermosetting film to the surface of the object subjected to the above treatment, which is opposite to the adhesive layer (X2), is included.

[0031] The first separation step is a step of heating the adhesive sheet to a temperature not lower than the expansion starting temperature (t) and lower than 125° C. to separate the adhesive layer ( X1 ) from the support.

[0032]

[10] The method for manufacturing a semiconductor device according to [8] or [9], wherein the step of attaching the support to the adhesive layer (X1) of the adhesive sheet in the step 1A is performed by making the surface (S) of the adhesive layer (X1) X1 ) and the surface (S) of the support to be bonded with the adhesive sheet s ) keep the surface of the support body (S s ) is attached to the surface (S) of the adhesive layer (X1) X1 ) process.

[0033]

[11] A method for manufacturing a semiconductor device, using the adhesive sheet described in [6] or [7] above, comprising the following steps 1B, 2B, a first separation step, and a second separation step.

[0034] Step 1B: a step of attaching an object to the adhesive layer (X1) of the adhesive sheet and attaching a support to the adhesive layer (X2) of the adhesive sheet

[0035] Step 2B: A step of performing one or more treatments selected from grinding and singulation on the object to be processed.

[0036] First separation step: a step of heating the adhesive sheet to a temperature higher than the expansion starting temperature (t) of the heat-expandable particles to separate the adhesive layer (X1) from the object to be processed

[0037] Second separation step: a step of separating the adhesive layer (X2) from the support

[0038]

[12] The method for manufacturing a semiconductor device according to

[11] , wherein the expansion starting temperature (t) of the heat-expandable particles is 50°C or higher and lower than 125°C,

[0039] After the above step 2B, a step 3B of attaching a thermosetting film to the surface of the object subjected to the above treatment, which is opposite to the adhesive layer (X1), is included.

[0040] The first separation step is a step of heating the adhesive sheet to a temperature not lower than the expansion starting temperature (t) and lower than 125° C. to separate the adhesive layer ( X1 ) from the object.

[0041]

[13] The method for manufacturing a semiconductor device described in

[11] or

[12] , wherein the step of attaching the object to be processed to the adhesive layer (X1) of the adhesive sheet in the step 1B is performed by making the surface (S) of the adhesive layer (X1) X1 ) and the surface (S) of the object to be processed to be pasted with the adhesive sheet w ) keep the surface of the object to be processed (S w ) is attached to the surface (S) of the adhesive layer (X1) X1 ) process.

[0042] Effects of the Invention

[0043] According to the present invention, there can be provided an adhesive sheet having excellent adhesive properties and a method for producing a semiconductor device using the adhesive sheet. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Figure 1 This is a cross-sectional view showing an example of the structure of the pressure-sensitive adhesive sheet of the present invention.

[0045] Figure 2 This is a cross-sectional view showing another example of the structure of the pressure-sensitive adhesive sheet of the present invention.

[0046] Figure 3 This is a cross-sectional view illustrating an example of the steps of the method for manufacturing a semiconductor device according to the present invention.

[0047] Figure 4 This is a cross-sectional view illustrating an example of the steps of the method for manufacturing a semiconductor device according to the present invention.

[0048] Figure 5 This is a cross-sectional view illustrating an example of the steps of the method for manufacturing a semiconductor device according to the present invention.

[0049] Figure 6 This is a cross-sectional view illustrating an example of the steps of the method for manufacturing a semiconductor device according to the present invention.

[0050] Figure 7 This is a cross-sectional view illustrating an example of the steps of the method for manufacturing a semiconductor device according to the present invention.

[0051] Figure 8This is a cross-sectional view illustrating an example of the steps of the method for manufacturing a semiconductor device according to the present invention.

[0052] Figure 9 This is a cross-sectional view illustrating an example of the steps of the method for manufacturing a semiconductor device according to the present invention.

[0053] Figure 10 This is an image of the three-dimensional surface shape of the PSA sheet produced in Example 1.

[0054] Figure 11 This is an image of the three-dimensional surface shape of the PSA sheet produced in Comparative Example 9.

[0055] Figure 12 This is an example of a photograph of the appearance of a test sample corresponding to Evaluation A in the adhesiveness evaluation.

[0056] Figure 13 This is an example of a photograph of the appearance of a test sample corresponding to evaluation F in the adhesiveness evaluation.

[0057] Explanation of symbols

[0058] 1a, 1b, 2a, 2b adhesive sheets

[0059] 10, 10a, 10b Stripping material

[0060] 3 Support

[0061] 4 Laser irradiation device

[0062] 5 Modified area

[0063] 6 grinders

[0064] 7 Thermosetting film

[0065] 8 Support plate

[0066] W semiconductor wafer

[0067] W1 Circuit surface of semiconductor chip

[0068] W2 Backside of semiconductor wafer

[0069] CP semiconductor chips

[0070] (X1) Adhesive layer (X1)

[0071] (X2) Adhesive layer (X2)

[0072] (Y) Base material layer (Y)

[0073] (S x1 ) The surface (S) of the adhesive layer (X1) x1 )

[0074] (S s ) The surface of the support to which the adhesive sheet is to be attached (S s ) DETAILED DESCRIPTION

[0075] In this specification, the "active ingredient" refers to the components contained in the target composition excluding the diluent solvent.

[0076] In this specification, the weight average molecular weight (Mw) is a value measured by gel permeation chromatography (GPC) in terms of standard polystyrene, and specifically, is a value measured according to the method described in Examples.

[0077] In this specification, for example, "(meth)acrylic acid" means both "acrylic acid" and "methacrylic acid", and the same applies to other similar terms.

[0078] In this specification, regarding preferred numerical ranges (e.g., content ranges), the lower and upper limits described in a hierarchical manner can be independently combined. For example, in the description "preferably 10 to 90, more preferably 30 to 60," the "preferable lower limit (10)" and the "more preferably upper limit (60)" can be combined to obtain "10 to 60."

[0079] In this specification, "energy radiation" refers to radiation containing energy particles such as electromagnetic waves or charged particle beams. Examples include ultraviolet rays, radiation, and electron beams. For example, ultraviolet radiation can be emitted using electrodeless lamps, high-pressure mercury lamps, metal halide lamps, and UV-LEDs. Electron beams can be emitted using electron beams generated by, for example, electron beam accelerators.

[0080] In this specification, "energy ray polymerizable" means a property of being polymerized by irradiation with energy rays. Also, "energy ray curable" means a property of being cured by irradiation with energy rays.

[0081] In this specification, whether a “layer” is a “non-thermally expandable layer” or a “thermally expandable layer” is determined as follows.

[0082] If the layer being evaluated contains heat-expandable particles, heat the layer for 3 minutes at the expansion starting temperature (t) of the heat-expandable particles. If the volume change rate calculated using the following formula is less than 5%, the layer is considered a "non-heat-expandable layer." If it is 5% or greater, the layer is considered a "heat-expandable layer."

[0083] ■ Volume change rate (%) = {(volume of the above layer after heat treatment - volume of the above layer before heat treatment) / volume of the above layer before heat treatment} × 100

[0084] In addition, the layer which does not contain heat-expandable particles is regarded as a "non-heat-expandable layer."

[0085] In this specification, the "front surface" of a semiconductor wafer or semiconductor chip refers to the surface on which a circuit is formed (hereinafter also referred to as the "circuit surface"), and the "back surface" of a semiconductor wafer or semiconductor chip refers to the surface on which no circuit is formed.

[0086] In this specification, the thickness of each layer is the thickness at 23° C. and represents a value measured by the method described in Examples.

[0087] In this specification, the adhesive strength of each layer refers to the adhesive strength to the mirror surface of the silicon mirror wafer, and refers to the adhesive strength measured at 23°C, 50% RH (relative humidity) in an environment using a 180° peel method at a tensile speed of 300 mm / min in accordance with JIS Z0237:2000.

[0088] [Adhesive sheet]

[0089] The pressure-sensitive adhesive sheet according to one embodiment of the present invention has a laminated structure including a pressure-sensitive adhesive layer (X1) and a base material layer (Y).

[0090] At least one of the adhesive layer (X1) and the base layer (Y) is a heat-expandable layer containing heat-expandable particles.

[0091] The surface (S) of the adhesive layer (X1) X1 ) has an arithmetic mean waviness (Wa) of 0.090 μm or less, and the surface (S X1 ) is a surface on the opposite side to the surface facing the above-mentioned base material layer (Y).

[0092] In one embodiment of the adhesive sheet of the present invention, the heat-expandable particles contained in the heat-expandable layer of at least one of the adhesive layer (X1) and the base layer (Y) are heated to a temperature above the expansion starting temperature (t) to expand, thereby forming irregularities on the adhesive surface of the adhesive layer (X1). This significantly reduces the contact area between an adherend attached to the adhesive surface of the adhesive layer (X1) and the adhesive surface. This significantly reduces the adhesion between the adhesive surface of the adhesive layer (X1) and the adherend, making it easier to separate the adhesive sheet from the adherend.

[0093] In the pressure-sensitive adhesive sheet of one embodiment of the present invention, the surface (S) opposite to the surface facing the substrate layer (Y) of the pressure-sensitive adhesive layer (X1) is formed. X1 ) has an arithmetic mean waviness (Wa) of 0.090 μm or less, resulting in a PSA sheet with excellent adhesiveness.

[0094] It should be noted that, as a factor affecting the adhesion of the adhesive sheet, the arithmetic mean roughness (Ra) of the adhesive surface is sometimes of concern. However, the present inventors have found that, for an adhesive sheet containing heat-expandable particles, particularly in the case where the adhesive surfaces are kept substantially parallel to each other, sufficient adhesion may not be obtained simply by suppressing the arithmetic mean roughness (Ra) to a smaller value. This is considered to be due to the fact that although local adhesion is improved by improving the microscopic smoothness characterized by the arithmetic mean roughness (Ra), the adhesive sheet containing heat-expandable particles may be due to the presence of heat-expandable particles or the presence of some undulations on the adhesive surface, resulting in air entrapment at the bonding interface. On the other hand, the adhesive sheet of one aspect of the present invention can suppress the occurrence of air entrapment by adjusting the arithmetic mean waviness (Wa) representing a more microscopic surface shape to a specific range of less than 0.090 μm, thereby achieving excellent adhesion.

[0095] <Composition of Adhesive Sheet>

[0096] In the pressure-sensitive adhesive sheet of one embodiment of the present invention, at least one of the pressure-sensitive adhesive layer (X1) and the base material layer (Y) may be a heat-expandable layer containing heat-expandable particles.

[0097] Examples of adhesive sheets in which the substrate layer (Y) is a heat-expandable layer containing heat-expandable particles include an adhesive sheet in which the substrate layer (Y) is a substrate laminate in which a heat-expandable substrate layer (Y1) containing heat-expandable particles and a non-heat-expandable substrate layer (Y2) are laminated, and the adhesive sheet has a laminate structure in which the adhesive layer (X1), the heat-expandable substrate layer (Y1), and the non-heat-expandable substrate layer (Y2) are arranged in this order. Hereinafter, an adhesive sheet having this structure may be referred to as a "first embodiment adhesive sheet."

[0098] In one embodiment of the adhesive sheet of the present invention, when the adhesive layer (X1) is a heat-expandable layer containing heat-expandable particles, an adhesive sheet having a laminated structure comprising an adhesive layer (X1) as a heat-expandable layer and a substrate layer (Y) can be used. Hereinafter, an adhesive sheet having this structure may be referred to as a "second embodiment of the adhesive sheet."

[0099] The pressure-sensitive adhesive sheet of one embodiment of the present invention may have any structure as long as it has a laminated structure including the pressure-sensitive adhesive layer (X1) and the base layer (Y), and may have layers other than the pressure-sensitive adhesive layer (X1) and the base layer (Y) depending on the application.

[0100] For example, in the case where the adhesive sheet of one embodiment of the present invention is used for the processing of the object to be processed, from the viewpoint of improving the processability of the object to be processed, the adhesive sheet of one embodiment of the present invention preferably has the following structure: further having an adhesive layer (X2), and having a laminated structure (i.e., a double-sided adhesive sheet) in which an adhesive layer (X1), a substrate layer (Y) and an adhesive layer (X2) are sequentially arranged. By having this structure, the object to be processed can be attached to any one of the adhesive layers in the adhesive layer (X1) or the adhesive layer (X2) and the support can be attached to any other adhesive layer. By fixing the object to be processed to the support via the adhesive sheet, it is possible to suppress the vibration, dislocation, and breakage of the fragile object to be processed when the object to be processed is processed, thereby improving processing accuracy and processing speed.

[0101] In the following description, unless otherwise specified, a "double-sided PSA sheet" refers to a PSA sheet having a laminate structure in which a PSA layer (X1), a substrate layer (Y), and a PSA layer (X2) are sequentially arranged.

[0102] The adhesive sheet of one embodiment of the present invention may also have a release material on the adhesive surface of the adhesive layer (X1). In addition, when the adhesive sheet of one embodiment of the present invention has the structure of a double-sided adhesive sheet, it may have a release material on the adhesive surface of at least one of the adhesive layer (X1) and the adhesive layer (X2).

[0103] Hereinafter, the structure of the pressure-sensitive adhesive sheet according to one embodiment of the present invention will be described in more detail with reference to the drawings.

[0104] Examples of the pressure-sensitive adhesive sheet of one embodiment of the present invention include Figure 1 (a) shows an adhesive sheet 1a having an adhesive layer (X1) on a substrate layer (Y). The adhesive sheet 1a has a surface (S) with an arithmetic mean waviness (Wa) of 0.090 μm or less on the side opposite to the surface of the adhesive layer (X1) facing the substrate layer (Y). X1 ).

[0105] It should be noted that the adhesive sheet of one embodiment of the present invention may also be Figure 1 Like the PSA sheet 1b shown in (b), the PSA layer (X1) is further provided with a release material 10 on the adhesive surface.

[0106] As another embodiment of the PSA sheet of the present invention, there can be mentioned a PSA sheet having the structure of the above-mentioned double-sided PSA sheet.

[0107] Examples of the PSA sheet having such a structure include: Figure 2(a) A double-sided adhesive sheet 2a having a structure in which a substrate layer (Y) is sandwiched between an adhesive layer (X1) and an adhesive layer (X2). The double-sided adhesive sheet 2a has a surface (S) having an arithmetic mean waviness (Wa) of 0.090 μm or less on the side opposite to the surface of the adhesive layer (X1) facing the substrate layer (Y). X1 ).

[0108] In addition, you can also Figure 2 Like the double-sided PSA sheet 2b shown in (b), the PSA layer (X1) further has a release material 10a on the PSA surface, and the PSA layer (X2) further has a release material 10b on the PSA surface.

[0109] It should be noted that in Figure 2 In the double-sided adhesive sheet 2b shown in (b), if the peeling force when peeling the release material 10a from the adhesive layer (X1) and the peeling force when peeling the release material 10b from the adhesive layer (X2) are equal, when the release materials on both sides are pulled outward to peel, the adhesive layer may be cut and fall off along with the release materials on both sides. To prevent this phenomenon, it is preferable to use two release materials designed to have different peeling forces from the adhesive layers adhered to each other as the release materials 10a and 10b on both sides.

[0110] As other types of adhesive sheets, Figure 2 The double-sided adhesive sheet 2a shown in (a) may also be a double-sided adhesive sheet having the following structure, wherein a release material with release treatment applied on both sides is laminated on the adhesive surface of one of the adhesive layer (X1) and the adhesive layer (X2) and then rolled into a roll.

[0111] The adhesive sheet of one embodiment of the present invention may or may not have another layer between the substrate layer (Y) and the adhesive layer (X1). In addition, when the adhesive sheet of one embodiment of the present invention is the above-mentioned double-sided adhesive sheet, in addition to the above, another layer may or may not be present between the substrate layer (Y) and the adhesive layer (X2).

[0112] It should be noted that, for the first embodiment of the adhesive sheet, from the viewpoint of suppressing expansion on that surface, it is preferred that a non-thermally expandable substrate layer (Y2) be directly laminated on the surface of the heat-expandable substrate layer (Y1) opposite to the adhesive layer (X1). Furthermore, for the second embodiment of the adhesive sheet, it is preferred that a layer capable of suppressing expansion on the surface of the adhesive layer (X1) be directly laminated on the surface opposite to the adhesive surface, and it is more preferred that the substrate layer (Y) be directly laminated.

[0113] <Arithmetic mean waviness (Wa)>

[0114] In the pressure-sensitive adhesive sheet of one embodiment of the present invention, the surface (S) opposite to the surface facing the substrate layer (Y) of the pressure-sensitive adhesive layer (X1) X1 )’s arithmetic mean waviness (Wa) is less than 0.090 μm.

[0115] By making the surface (S X1 ) has an arithmetic mean waviness (Wa) of 0.090 μm or less, and excellent adhesiveness can be obtained.

[0116] On the other hand, when the surface (S X1 When the arithmetic mean waviness (Wa) of the adhesive exceeds 0.090 μm, sufficient adhesiveness may not be obtained.

[0117] In this specification, the arithmetic mean waviness (Wa) is measured based on JIS B0601:2013, and more specifically, it can be measured by the method described in the examples below.

[0118] Furthermore, from the viewpoint of improving the adhesiveness of the adhesive sheet, the surface (S X1 ) is preferably 0.089 μm or less, more preferably 0.088 μm or less, further preferably 0.087 μm or less, and further preferably 0.086 μm or less. X1 ) has no particular restriction on the lower limit of the arithmetic mean waviness (Wa) and may be 0 μm, but from the viewpoint of maintaining a good balance with the peelability of the adhesive layer (X1), it is preferably 0.010 μm or more, more preferably 0.020 μm or more, further preferably 0.030 μm or more, and even more preferably 0.040 μm or more.

[0119] For the surface (S) of the adhesive layer (X1) X1 ) can be adjusted to the above range according to, for example, the thickness of the adhesive layer (X1) and the substrate layer (Y), the content of heat-expandable particles in the heat-expandable layer, the manufacturing conditions of the adhesive composition (x-1) as the forming material of the adhesive layer (X1) described later, and the resin composition (y-1) as the forming material of the substrate layer (Y).

[0120] <Thermal Expandable Particles>

[0121] The heat-expandable particles used in the PSA sheet of one embodiment of the present invention may be particles that expand when heated, and the expansion starting temperature (t) may be appropriately selected depending on the application of the PSA sheet.

[0122] On the other hand, in recent years, when mounting a semiconductor chip on a substrate, a process of attaching the semiconductor chip to the substrate via a thermosetting film adhesive called die attach film (hereinafter also referred to as "DAF") has been adopted.

[0123] DAF is pasted on one side of a semiconductor wafer or a plurality of semiconductor chips after singulation, and is divided into the same shape as the semiconductor chip at the same time as the singulation of the semiconductor wafer or after being pasted on the semiconductor chip. The semiconductor chip with DAF obtained by singulation is pasted (chip bonding) to the substrate from the DAF side, and then the semiconductor chip and the substrate are bonded by thermally curing the DAF. At this time, the DAF needs to maintain the property of being adhered by pressure or heat until it is pasted to the substrate. However, in the case where the semiconductor chip with DAF is the adherend of a heat-peelable adhesive sheet, sometimes the heat caused by the expansion of the heat-expandable microspheres causes the DAF to be cured before the chip is attached, thereby reducing the adhesion of the DAF to the substrate. The reduction in the adhesion of the DAF will cause a reduction in the bonding reliability between the semiconductor chip and the substrate, and therefore needs to be suppressed. That is, when performing heat peeling, it is desirable to suppress the thermal changes of the adherend.

[0124] From this viewpoint, in the pressure-sensitive adhesive sheet of one embodiment of the present invention, the expansion starting temperature (t) of the heat-expandable particles is preferably lower than 125°C, more preferably 120°C or lower, even more preferably 115°C or lower, even more preferably 110°C or lower, and even more preferably 105°C or lower.

[0125] Furthermore, when using particles with a low expansion onset temperature as heat-expandable particles in heat-peelable adhesive sheets, the heat-expandable particles may expand due to temperature increases during, for example, grinding of the adherend. Such unexpected expansion of the heat-expandable particles can cause unexpected separation or displacement of the adherend, and therefore, it is desirable to suppress this.

[0126] From this viewpoint, in the pressure-sensitive adhesive sheet of one embodiment of the present invention, the expansion starting temperature (t) of the heat-expandable particles is preferably 50°C or higher, more preferably 55°C or higher, further preferably 60°C or higher, and even more preferably 70°C or higher.

[0127] In addition, in this specification, the expansion starting temperature (t) of heat-expandable particles represents a value measured by the following method.

[0128] (Method for measuring expansion starting temperature (t) of heat-expandable particles)

[0129] A sample was prepared by placing 0.5 mg of thermally expandable particles to be measured in an aluminum cup having a diameter of 6.0 mm (inner diameter of 5.65 mm) and a depth of 4.8 mm, and covering the cup with an aluminum lid (diameter of 5.6 mm, thickness of 0.1 mm).

[0130] Using a dynamic viscoelasticity measuring instrument, the height of the sample was measured while an indenter applied a force of 0.01 N from the upper surface of the aluminum cap. The sample was then heated from 20°C to 300°C at a rate of 10°C / min while the indenter applied a force of 0.01 N. The vertical displacement of the indenter was measured, and the temperature at which the displacement in the positive direction began was defined as the expansion onset temperature (t).

[0131] The heat-expandable particles are preferably microencapsulated foaming agents comprising an outer shell formed of a thermoplastic resin and an inner component encapsulated by the outer shell and vaporized when heated to a predetermined temperature.

[0132] Examples of the thermoplastic resin constituting the shell of the microencapsulated foaming agent include polyvinyl alcohol, polyvinyl butyral, polymethyl methacrylate, polyacrylonitrile, polyvinylidene chloride, polysulfone, and copolymers obtained by polymerizing two or more monomers forming structural units contained in these thermoplastic resins.

[0133] Examples of the component encapsulated by the shell of the microencapsulated foaming agent, i.e., the inner component, include low-boiling-point liquids such as propane, propylene, butylene, n-butane, isobutane, isopentane, neopentane, n-pentane, n-hexane, isohexane, n-heptane, n-octane, cyclopropane, cyclobutane, and petroleum ether.

[0134] Among these components, from the viewpoint of suppressing thermal changes in the adherend during heat peeling and suppressing unexpected expansion of the heat-expandable particles caused by temperature increases when the adherend is ground, etc., when the expansion starting temperature (t) of the heat-expandable particles is set to 50°C or higher and lower than 125°C, the inner component is preferably propane, isobutane, n-pentane, and cyclopropane.

[0135] These internal components may be used alone or in combination of two or more.

[0136] The expansion starting temperature (t) of the heat-expandable particles can be adjusted by appropriately selecting the type of the contained components.

[0137] The average particle size of the heat-expandable particles used in one embodiment of the present invention before expansion at 23° C. is preferably 3 to 100 μm, more preferably 4 to 70 μm, even more preferably 6 to 60 μm, and even more preferably 10 to 50 μm.

[0138] It should be noted that the average particle size of the heat-expandable particles before expansion refers to the volume median particle size (D 50 ), in the particle distribution of the heat-expandable particles before expansion measured using a laser diffraction particle size distribution measuring apparatus (e.g., manufactured by Malvern, product name "Mastersizer 3000"), the particle size at which the cumulative volume frequency calculated starting from the particles with the smallest particle size among the heat-expandable particles before expansion is equivalent to 50%.

[0139] As the 90% particle size (D ) of the heat-expandable particles before expansion at 23°C used in one embodiment of the present invention, 90 ), preferably 10 to 150 μm, more preferably 15 to 100 μm, further preferably 20 to 90 μm, and further preferably 25 to 80 μm.

[0140] It should be noted that the 90% particle size (D 90 ) refers to the particle size corresponding to 90% of the cumulative volume frequency calculated from the particles with the smallest particle size among the heat-expandable particles before expansion, in the particle distribution of the heat-expandable particles before expansion, measured using a laser diffraction particle size distribution analyzer (e.g., manufactured by Malvern, product name "Mastersizer 3000").

[0141] The heat-expandable particles used in one embodiment of the present invention preferably have a maximum volume expansion ratio of 1.5 to 200 times, more preferably 2 to 150 times, further preferably 2.5 to 120 times, and even more preferably 3 to 100 times when heated to a temperature not lower than the expansion starting temperature (t).

[0142] The content of the heat-expandable particles in the heat-expandable layer is preferably 1% by mass or more, more preferably 2% by mass or more, even more preferably 3% by mass or more, and even more preferably 4% by mass or more, relative to the total mass (100% by mass) of the heat-expandable layer. Furthermore, the content of the heat-expandable particles in the heat-expandable layer is preferably 25% by mass or less, more preferably 23% by mass or less, even more preferably 22% by mass or less, and even more preferably 21% by mass or less, relative to the total mass (100% by mass) of the heat-expandable layer.

[0143] When the content of the heat-expandable particles is 1% by mass or more, there is a tendency that the peeling property during heat peeling is improved. In addition, when the content of the heat-expandable particles is 25% by mass or less, the generation of unevenness caused by the heat-expandable particles before thermal expansion is suppressed, and the surface area (S) of the adhesive layer (X1) can be further reduced. x1 ) and the tendency of improving the arithmetic mean waviness (Wa) and adhesion.

[0144] <Thickness of Thermally Expandable Layer>

[0145] In one embodiment of the present invention, the thickness of the heat-expandable layer before thermal expansion is preferably 30 to 300 μm, more preferably 40 to 270 μm, further preferably 50 to 240 μm, and even more preferably 55 to 220 μm.

[0146] When the thickness of the heat-expandable layer before heat expansion is 30 μm or more, the generation of irregularities due to the heat-expandable particles before heat expansion is suppressed, and the surface area (S) of the adhesive layer (X1) can be further reduced. x1 ) and the adhesiveness tend to be improved. In addition, when the thickness of the heat-expandable layer before thermal expansion is 300 μm or less, there is a tendency for the pressure-sensitive adhesive sheet to be easily handled.

[0147] Next, preferred aspects of each layer included in the pressure-sensitive adhesive sheet according to one embodiment of the present invention will be described.

[0148] Hereinafter, preferred embodiments of the first embodiment and the second embodiment of the PSA sheet will be described, but the present invention is not limited to these embodiments.

[0149] [Adhesive Sheet of the First Aspect]

[0150] The first embodiment of the PSA sheet has a laminated structure in which a PSA layer (X1), a heat-expandable base layer (Y1), and a non-heat-expandable base layer (Y2) are arranged in this order.

[0151] In the first embodiment of the adhesive sheet, since the heat-expandable particles are contained in the base layer (Y), the irregularities caused by the heat-expandable particles are less likely to form on the surface (S) of the adhesive layer (X1). x1 Furthermore, the adhesive layer (X1) does not need to contain heat-expandable particles, so there is a high degree of freedom in designing thickness, resin composition, etc., and the arithmetic mean waviness (Wa) can be further reduced, thereby tending to improve adhesiveness.

[0152] <Adhesive Layer (X1)>

[0153] The pressure-sensitive adhesive layer (X1) included in the pressure-sensitive adhesive sheet of the first embodiment may be a heat-expandable layer or a non-heat-expandable layer, but is preferably a non-heat-expandable layer.

[0154] When the adhesive layer (X1) is a non-thermally expandable layer, the volume change rate (%) of the adhesive layer (X1) calculated by the above formula is less than 5%, preferably less than 2%, more preferably less than 1%, further preferably less than 0.1%, and further preferably less than 0.01%.

[0155] The adhesive layer (X1) in the adhesive sheet of the first embodiment preferably does not contain heat-expandable particles, but may contain heat-expandable particles within a range that does not violate the purpose of the present invention. When the adhesive layer (X1) contains heat-expandable particles, the smaller the content, the better. It is preferably less than 3% by mass, more preferably less than 1% by mass, further preferably less than 0.1% by mass, further preferably less than 0.01% by mass, and further preferably less than 0.001% by mass relative to the total mass (100% by mass) of the adhesive layer (X1).

[0156] The adhesive layer (X1) included in the adhesive sheet of the first embodiment can be formed from an adhesive composition (x-1) containing an adhesive resin.

[0157] Hereinafter, each component contained in the adhesive composition (x-1) will be described.

[0158] (Adhesive resin)

[0159] Examples of the adhesive resin include polymers which have adhesive properties alone and have a weight average molecular weight (Mw) of 10,000 or more.

[0160] From the viewpoint of improving the adhesive strength of the adhesive layer (X1), the weight average molecular weight (Mw) of the adhesive resin is preferably 10,000 to 2,000,000, more preferably 20,000 to 1,500,000, and even more preferably 30,000 to 1,000,000.

[0161] Specific examples of the adhesive resin include rubber-based resins such as acrylic resins, urethane resins, and polyisobutylene resins, polyester resins, olefin resins, silicone resins, and polyvinyl ether resins.

[0162] These adhesive resins may be used alone or in combination of two or more.

[0163] When these adhesive resins are copolymers having two or more structural units, the form of the copolymer is not particularly limited and may be any of a block copolymer, a random copolymer, and a graft copolymer.

[0164] Here, in one embodiment of the present invention, from the viewpoint of allowing the pressure-sensitive adhesive layer (X1) to exhibit excellent adhesive strength, the pressure-sensitive adhesive resin preferably contains an acrylic resin.

[0165] The content of the acrylic resin in the adhesive resin is preferably 30 to 100% by mass, more preferably 50 to 100% by mass, further preferably 70 to 100% by mass, and even more preferably 85 to 100% by mass, relative to the total amount (100% by mass) of the adhesive resin contained in the adhesive composition (x-1) or the adhesive layer (X1).

[0166] In one embodiment of the present invention, examples of acrylic resins that can be used as adhesive resins include polymers containing a structural unit derived from an alkyl (meth)acrylate having a linear or branched alkyl group, and polymers containing a structural unit derived from a (meth)acrylate having a cyclic structure.

[0167] The weight average molecular weight (Mw) of the acrylic resin is preferably 100,000 to 1.5 million, more preferably 200,000 to 1.3 million, even more preferably 350,000 to 1.2 million, and even more preferably 500,000 to 1.1 million.

[0168] As the acrylic resin used in one embodiment of the present invention, an acrylic copolymer (A1) having a structural unit (a1) derived from an alkyl (meth)acrylate (a1') (hereinafter also referred to as "monomer (a1')") and a structural unit (a2) derived from a functional group-containing monomer (a2') (hereinafter also referred to as "monomer (a2')") is more preferred.

[0169] The number of carbon atoms of the alkyl group of the monomer (a1′) is preferably 1 to 24, more preferably 1 to 12, further preferably 2 to 10, and even more preferably 4 to 8, from the viewpoint of achieving excellent adhesive strength in the pressure-sensitive adhesive layer (X1).

[0170] It should be noted that the alkyl group contained in the monomer (a1′) may be a linear alkyl group or a branched alkyl group.

[0171] Examples of the monomer (a1′) include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, n-butyl (meth)acrylate, sec-butyl (meth)acrylate, isobutyl (meth)acrylate, tert-butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, lauryl (meth)acrylate, tridecyl (meth)acrylate, and stearyl (meth)acrylate.

[0172] These monomers (a1') may be used alone or in combination of two or more.

[0173] As the monomer (a1′), n-butyl acrylate and 2-ethylhexyl acrylate are preferred.

[0174] The content of the structural unit (a1) relative to all structural units (100% by mass) of the acrylic copolymer (A1) is preferably 50 to 99.9% by mass, more preferably 60 to 99.0% by mass, further preferably 70 to 97.0% by mass, and even more preferably 80 to 95.0% by mass.

[0175] Examples of the functional group possessed by the monomer (a2′) include a hydroxyl group, a carboxyl group, an amino group, and an epoxy group.

[0176] That is, examples of the monomer (a2′) include a hydroxyl group-containing monomer, a carboxyl group-containing monomer, an amino group-containing monomer, and an epoxy group-containing monomer.

[0177] These monomers (a2') may be used alone or in combination of two or more.

[0178] Among these monomers, the monomer (a2′) is preferably a hydroxyl group-containing monomer and a carboxyl group-containing monomer, and more preferably a hydroxyl group-containing monomer.

[0179] Examples of the hydroxyl group-containing monomer include hydroxyalkyl (meth)acrylates such as 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 3-hydroxybutyl (meth)acrylate, and 4-hydroxybutyl (meth)acrylate; and hydroxyl group-containing compounds such as unsaturated alcohols such as vinyl alcohol and allyl alcohol.

[0180] Examples of the carboxyl group-containing monomer include ethylenically unsaturated monocarboxylic acids such as (meth)acrylic acid and crotonic acid; ethylenically unsaturated dicarboxylic acids such as fumaric acid, itaconic acid, maleic acid, and citraconic acid, and their anhydrides; 2-(acryloyloxy)ethyl succinate; and 2-carboxyethyl (meth)acrylate.

[0181] The content of the structural unit (a2) relative to the total structural units (100% by mass) of the acrylic copolymer (A1) is preferably 0.1 to 30% by mass, more preferably 0.5 to 20% by mass, further preferably 1.0 to 15% by mass, and even more preferably 3.0 to 10% by mass.

[0182] The acrylic copolymer (A1) may further have a structural unit (a3) derived from another monomer (a3') other than the monomers (a1') and (a2').

[0183] In the acrylic copolymer (A1), the total content of the structural units (a1) and (a2) relative to all the structural units (100% by mass) of the acrylic copolymer (A1) is preferably 70 to 100% by mass, more preferably 80 to 100% by mass, even more preferably 90 to 100% by mass, and even more preferably 95 to 100% by mass.

[0184] Examples of the monomer (a3') include olefins such as ethylene, propylene, and isobutylene; halogenated olefins such as vinyl chloride and vinylidene chloride; diene monomers such as butadiene, isoprene, and chloroprene; (meth)acrylates having a cyclic structure such as cyclohexyl (meth)acrylate, benzyl (meth)acrylate, isobornyl (meth)acrylate, dicyclopentyl (meth)acrylate, dicyclopentenyl (meth)acrylate, dicyclopentenyloxyethyl (meth)acrylate, and imide (meth)acrylate; styrene, α-methylstyrene, vinyltoluene, vinyl formate, vinyl acetate, acrylonitrile, (meth)acrylamide, (meth)acrylonitrile, (meth)acryloylmorpholine, and N-vinylpyrrolidone.

[0185] The content of the adhesive resin in the adhesive composition (x-1) is preferably 35 to 100 mass %, more preferably 50 to 100 mass %, further preferably 60 to 100 mass %, and further preferably 70 to 99.5 mass %, relative to the total amount (100 mass %) of the active ingredients of the adhesive composition (x-1).

[0186] (cross-linking agent)

[0187] In one embodiment of the present invention, when the pressure-sensitive adhesive composition (x-1) contains a pressure-sensitive adhesive resin having a functional group like the acrylic copolymer (A1), it is preferred that the pressure-sensitive adhesive composition (x-1) further contain a cross-linking agent.

[0188] The crosslinking agent is a component that reacts with the adhesive resin having a functional group to crosslink the adhesive resins with the functional group serving as a crosslinking starting point.

[0189] Examples of the cross-linking agent include isocyanate-based cross-linking agents, epoxy-based cross-linking agents, aziridine-based cross-linking agents, and metal chelate-based cross-linking agents.

[0190] These cross-linking agents may be used alone or in combination of two or more.

[0191] Among these cross-linking agents, isocyanate cross-linking agents are preferred from the viewpoints of improving cohesive strength and thus adhesive strength, and from the viewpoints of easy availability.

[0192] Examples of the isocyanate crosslinking agent include aromatic polyisocyanates such as tolylene diisocyanate, diphenylmethane diisocyanate, and xylylene diisocyanate; alicyclic polyisocyanates such as dicyclohexylmethane-4,4'-diisocyanate, bicycloheptane triisocyanate, cyclopentylene diisocyanate, cyclohexylene diisocyanate, methylcyclohexylene diisocyanate, methylenebis(cyclohexyl isocyanate), 3-isocyanatomethyl-3,5,5-trimethylcyclohexyl isocyanate, and hydrogenated xylylene diisocyanate; non-cyclic aliphatic polyisocyanates such as hexamethylene diisocyanate, trimethylhexamethylene diisocyanate, and lysine diisocyanate; and other polyisocyanate compounds.

[0193] Examples of the isocyanate crosslinking agent include trimethylolpropane adduct-type modified products of the polyvalent isocyanate compound, biuret-type modified products formed by reaction with water, and isocyanurate-type modified products containing an isocyanurate ring.

[0194] Among these isocyanate cross-linking agents, from the viewpoint of suppressing a decrease in the elastic modulus of the adhesive layer (X1) during heating and suppressing adhesion of residues from the adhesive layer (X1) to the adherend, it is preferred to use a trimethylolpropane adduct-type modified product of a polyisocyanate compound, more preferably a trimethylolpropane adduct-type modified product of an aromatic polyisocyanate compound, and still more preferably a trimethylolpropane adduct-type modified product of toluene diisocyanate.

[0195] The content of the crosslinking agent can be appropriately adjusted depending on the number of functional groups in the adhesive resin, but is preferably 0.01 to 10 parts by mass, more preferably 0.03 to 7 parts by mass, and even more preferably 0.05 to 5 parts by mass per 100 parts by mass of the adhesive resin having functional groups.

[0196] (Thickener)

[0197] In one embodiment of the present invention, the adhesive composition (x-1) may further contain a tackifier from the viewpoint of further improving adhesive strength.

[0198] In this specification, the "tackifier" refers to a component having a weight average molecular weight (Mw) of less than 10,000 among components that auxiliary improve the adhesive strength of the adhesive resin, and is a component different from the above-mentioned adhesive resin.

[0199] The weight average molecular weight (Mw) of the tackifier is less than 10,000, preferably 400 to 9,000, more preferably 500 to 8,000, and even more preferably 800 to 5,000.

[0200] Examples of the tackifier include rosin-based resins, terpene-based resins, styrene-based resins, C5 petroleum resins obtained by copolymerizing C5 fractions such as pentene, isoprene, piperine, and 1,3-pentadiene produced by thermal decomposition of naphtha, C9 petroleum resins obtained by copolymerizing C9 fractions such as indene and vinyltoluene produced by thermal decomposition of naphtha, and hydrogenated resins obtained by hydrogenating these resins.

[0201] The softening point of the tackifier is preferably 60 to 170°C, more preferably 65 to 160°C, and even more preferably 70 to 150°C.

[0202] In addition, in this specification, the "softening point" of a tackifier means the value measured based on JIS K 2531.

[0203] The tackifier may be used alone or in combination of two or more tackifiers having different softening points, structures, etc. When two or more tackifiers are used, the weighted average of the softening points of these tackifiers preferably falls within the above range.

[0204] The content of the tackifier is preferably 0.01 to 65 mass %, more preferably 0.1 to 50 mass %, further preferably 1 to 40 mass %, and even more preferably 2 to 30 mass % relative to the total amount (100 mass %) of the active ingredients of the adhesive composition (x-1).

[0205] (Additives for adhesives)

[0206] In one embodiment of the present invention, the adhesive composition (x-1) may contain, in addition to the above-mentioned additives, adhesive additives commonly used in adhesives within a range that does not impair the effects of the present invention.

[0207] Examples of such adhesive additives include antioxidants, softeners (plasticizers), rust preventives, pigments, dyes, retarders, reaction accelerators (catalysts), ultraviolet absorbers, energy-ray curable compounds described below, and photopolymerization initiators.

[0208] In addition, these adhesive additives may be used individually or in combination of two or more kinds.

[0209] When these adhesive additives are contained, the content of each adhesive additive is independently preferably 0.0001 to 20 parts by mass, more preferably 0.001 to 10 parts by mass, based on 100 parts by mass of the adhesive resin.

[0210] (Adhesive Strength of the Adhesive Layer (X1) Before Thermal Expansion of the Heat-Expandable Base Material Layer (Y1))

[0211] The adhesive strength of the adhesive layer (X1) before thermal expansion of the heat-expandable substrate layer (Y1) is preferably 0.1 to 12.0 N / 25 mm, more preferably 0.5 to 9.0 N / 25 mm, further preferably 1.0 to 8.0 N / 25 mm, and even more preferably 1.2 to 7.5 N / 25 mm.

[0212] When the adhesive strength of the adhesive layer (X1) before thermal expansion of the heat-expandable base layer (Y1) is 0.1 N / 25 mm or more, unexpected peeling from the adherend during temporary fixing, displacement of the adherend, etc. can be more effectively suppressed. On the other hand, when the adhesive strength is 12.0 N / 25 mm or less, the peelability during thermal peeling can be further improved.

[0213] In addition, the adhesive strength of the adhesive layer (X1) at 23° C. before thermal expansion can be measured by the above-mentioned method.

[0214] (Adhesive Strength of the Adhesive Layer (X1) at 23°C After Thermal Expansion of the Heat-Expandable Base Layer (Y1))

[0215] The adhesive strength of the adhesive layer (X1) at 23°C after thermal expansion of the heat-expandable substrate layer (Y1) is preferably 1.5 N / 25 mm or less, more preferably 0.05 N / 25 mm or less, even more preferably 0.01 N / 25 mm or less, and even more preferably 0 N / 25 mm. It should be noted that an adhesive strength of 0 N / 25 mm means an adhesive strength below the measurement limit in the method for measuring adhesive strength after thermal expansion described below, and also includes cases where unexpected peeling occurs due to excessively low adhesive strength when the adhesive sheet is fixed for measurement.

[0216] The adhesive strength of the pressure-sensitive adhesive layer (X1) at 23°C after thermal expansion of the heat-expandable base layer (Y1) can be measured by the above-mentioned method using a pressure-sensitive adhesive sheet heated at the expansion starting temperature of the heat-expandable particles contained in the heat-expandable base layer (Y1) + 22°C for 1 minute.

[0217] (Thickness of Adhesive Layer (X1))

[0218] The thickness of the adhesive layer (X1) of the adhesive sheet of the first embodiment is preferably 3 to 10 μm, more preferably 3 to 8 μm, and even more preferably 3 to 7 μm at 23° C., from the viewpoint of exhibiting good adhesive strength and forming good irregularities on the adhesive surface of the adhesive layer (X1) when the heat-expandable particles are expanded by heating.

[0219] By adjusting the thickness of the adhesive layer (X1) to the above range, the adhesive layer (X1) can be easily formed, and the unevenness can be easily and satisfactorily formed on the adhesive surface of the adhesive layer (X1).

[0220] <Thermal Expandable Base Material Layer (Y1)>

[0221] The heat-expandable substrate layer (Y1) included in the first embodiment of the adhesive sheet is a heat-expandable layer containing heat-expandable particles in a resin material, and is provided between the adhesive layer (X1) and the non-heat-expandable substrate layer (Y2).

[0222] The heat-expandable base material layer (Y1) is preferably a non-adhesive base material.

[0223] The probe tack value of the surface of the heat-expandable base material layer (Y1) is usually less than 50 mN / 5 mmφ, preferably less than 30 mN / 5 mmφ, more preferably less than 10 mN / 5 mmφ, and further preferably less than 5 mN / 5 mmφ.

[0224] In addition, in this specification, the probe viscosity value of the substrate surface means the value measured by the following method.

[0225] <Probe stickiness value>

[0226] The substrate to be measured was cut into 10 mm squares and allowed to stand for 24 hours in an environment at 23°C and 50% RH (relative humidity). The resulting material was used as a test sample. The probe tack value of the test sample surface was measured in an environment at 23°C and 50% RH (relative humidity) using a tack tester (manufactured by Japan Tokushu Test Instruments Co., Ltd., product name "NTS-4800") in accordance with JIS Z0237:1991. Specifically, a 5 mm diameter stainless steel probe was subjected to a contact load of 0.98 N / cm for 1 second. 2 After contacting the surface of the test sample, the force required to move the probe away from the surface of the test sample at a speed of 10 mm / second is measured, and the obtained value can be used as the probe adhesion value of the test sample.

[0227] From the viewpoint of improving interlayer adhesion between the heat-expandable base layer (Y1) and other layers to be laminated, the surface of the heat-expandable base layer (Y1) may be subjected to surface treatment such as oxidation or embossing, adhesion-facilitating treatment, or primer treatment.

[0228] Examples of the oxidation method include corona discharge treatment, plasma discharge treatment, chromic acid treatment (wet method), hot air treatment, ozone treatment, and ultraviolet irradiation treatment. Examples of the roughening method include sandblasting and solvent treatment.

[0229] The heat-expandable base material layer (Y1) is preferably formed from a resin composition (y-1) containing a resin and heat-expandable particles.

[0230] Hereinafter, preferred embodiments of the resin composition (y-1) will be described. In addition, preferred embodiments of the thermally expandable particles are as described above.

[0231] (resin)

[0232] The resin contained in the resin composition (y-1) may be a non-adhesive resin or an adhesive resin.

[0233] That is, even if the resin contained in the resin composition (y-1) is an adhesive resin, as long as the adhesive resin undergoes a polymerization reaction with the polymerizable compound during the process of forming the heat-expandable substrate layer (Y1) from the resin composition (y-1), the resulting resin becomes a non-adhesive resin, and the heat-expandable substrate layer (Y1) containing the resin becomes non-adhesive.

[0234] The weight average molecular weight (Mw) of the resin contained in the resin composition (y-1) is preferably 1,000 to 1,000,000, more preferably 1,000 to 700,000, and even more preferably 1,000 to 500,000.

[0235] When the resin is a copolymer having two or more structural units, the form of the copolymer is not particularly limited and may be any of a block copolymer, a random copolymer, and a graft copolymer.

[0236] The content of the resin relative to the total amount (100% by mass) of the active ingredients of the resin composition (y-1) is preferably 50 to 99% by mass, more preferably 60 to 95% by mass, further preferably 65 to 90% by mass, and even more preferably 70 to 85% by mass.

[0237] The resin contained in the resin composition (y-1) preferably contains one or more selected from acrylic urethane resins and olefin resins from the viewpoint of facilitating the formation of irregularities on the adhesive surface of the adhesive layer (X1) and from the viewpoint of ensuring good sheet shape retention after thermal expansion. In other words, the thermally expandable substrate layer (Y1) preferably contains one or more selected from acrylic urethane resins and olefin resins.

[0238] Moreover, as said acrylic urethane resin, the following resin (U1) is preferable.

[0239] ■ An acrylic urethane resin (U1) obtained by polymerizing a urethane prepolymer (UP) and a vinyl compound containing a (meth)acrylate.

[0240] In addition, in this specification, a prepolymer refers to a compound which is formed by polymerizing a monomer and can constitute a polymer simply by further polymerization.

[0241] [Acrylic urethane resin (U1)]

[0242] As the urethane prepolymer (UP) forming the main chain of the acrylic urethane resin (U1), a reaction product of a polyol and a polyisocyanate can be mentioned.

[0243] In addition, the urethane prepolymer (UP) is preferably a prepolymer obtained by further subjecting the prepolymer to a chain extension reaction using a chain extender.

[0244] Examples of the polyol used as a raw material for the urethane prepolymer (UP) include alkylene polyols, ether polyols, ester polyols, ester amide polyols, ester-ether polyols, and carbonate polyols.

[0245] These polyols may be used alone or in combination of two or more.

[0246] As the polyol used in one embodiment of the present invention, a diol is preferred, an ester diol, an alkylene diol, and a carbonate diol are more preferred, and an ester diol and a carbonate diol are still more preferred.

[0247] Examples of the ester diol include condensation products of one or more diols selected from the following diols, such as 1,3-propylene glycol, 1,4-butanediol, 1,5-pentanediol, neopentyl glycol, and 1,6-hexanediol, and alkylene glycols such as ethylene glycol, propylene glycol, diethylene glycol, and dipropylene glycol, and one or more dicarboxylic acids and their anhydrides; and dicarboxylic acids such as phthalic acid, isophthalic acid, terephthalic acid, naphthalene dicarboxylic acid, 4,4-diphenyldicarboxylic acid, diphenylmethane-4,4'-dicarboxylic acid, succinic acid, adipic acid, azelaic acid, sebacic acid, chlorobridgeic acid, maleic acid, fumaric acid, itaconic acid, cyclohexane-1,3-dicarboxylic acid, cyclohexane-1,4-dicarboxylic acid, hexahydrophthalic acid, hexahydroisophthalic acid, hexahydroterephthalic acid, and methylhexahydrophthalic acid.

[0248] Specific examples include polyethylene adipate diol, polybutylene adipate diol, poly-1,6-hexanediol adipate diol, poly-1,6-hexanediol isophthalate diol, poly-neopentyl adipate diol, polyethylene propylene adipate diol, polyethylene butylene adipate diol, poly-1,6-hexanediol adipate diol, polyethylene diethylene adipate diol, poly(polytetramethylene ether) adipate diol, poly(3-methylpentane adipate) diol, polyethylene azelaic acid diol, polyethylene sebacate diol, polybutylene azelaic acid diol, polybutylene sebacate diol, and poly-neopentyl terephthalate diol.

[0249] Examples of the alkylene glycol include alkane diols such as 1,3-propylene glycol, 1,4-butanediol, 1,5-pentanediol, neopentyl glycol, and 1,6-hexanediol; alkylene glycols such as ethylene glycol, propylene glycol, diethylene glycol, and dipropylene glycol; polyalkylene glycols such as polyethylene glycol, polypropylene glycol, and polybutylene glycol; and polyoxyalkylene glycols such as polytetramethylene glycol.

[0250] Examples of the carbonate diol include 1,4-tetramethylene carbonate diol, 1,5-pentamethylene carbonate diol, 1,6-hexamethylene carbonate diol, 1,2-propylene carbonate diol, 1,3-propylene carbonate diol, 2,2-dimethylpropylene carbonate diol, 1,7-heptamethylene carbonate diol, 1,8-octamethylene carbonate diol, and 1,4-cyclohexane carbonate diol.

[0251] Examples of the polyisocyanate serving as a raw material for the urethane prepolymer (UP) include aromatic polyisocyanates, aliphatic polyisocyanates, and alicyclic polyisocyanates.

[0252] These polyvalent isocyanates may be used alone or in combination of two or more.

[0253] Furthermore, these polyvalent isocyanates may be trimethylolpropane adduct-type modified products, biuret-type modified products formed by reaction with water, or isocyanurate-type modified products containing an isocyanurate ring.

[0254] Among these, the polyisocyanate used in one embodiment of the present invention is preferably a diisocyanate, and more preferably one or more selected from 4,4′-diphenylmethane diisocyanate (MDI), 2,4-toluene diisocyanate (2,4-TDI), 2,6-toluene diisocyanate (2,6-TDI), hexamethylene diisocyanate (HMDI), and alicyclic diisocyanates.

[0255] Examples of the alicyclic diisocyanate include 3-isocyanate methyl-3,5,5-trimethylcyclohexyl isocyanate (isophorone diisocyanate, IPDI), 1,3-cyclopentane diisocyanate, 1,3-cyclohexane diisocyanate, 1,4-cyclohexane diisocyanate, methyl-2,4-cyclohexane diisocyanate, and methyl-2,6-cyclohexane diisocyanate. Isocyanate (IPDI) is preferred.

[0256] In one embodiment of the present invention, the urethane prepolymer (UP) forming the main chain of the acrylic urethane resin (U1) is preferably a linear urethane prepolymer which is a reaction product of a diol and a diisocyanate and has ethylenically unsaturated groups at both ends.

[0257] Examples of a method for introducing ethylenically unsaturated groups into both terminals of the linear urethane prepolymer include a method of reacting a terminal NCO group of a linear urethane prepolymer obtained by reacting a diol and a diisocyanate compound with a hydroxyalkyl (meth)acrylate.

[0258] Examples of the hydroxyalkyl (meth)acrylate include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 3-hydroxybutyl (meth)acrylate, and 4-hydroxybutyl (meth)acrylate.

[0259] The vinyl compound forming the side chain of the acrylic urethane resin (U1) contains at least (meth)acrylate.

[0260] As the (meth)acrylate, at least one selected from alkyl (meth)acrylates and hydroxyalkyl (meth)acrylates is preferred, and a combination of an alkyl (meth)acrylate and a hydroxyalkyl (meth)acrylate is more preferred.

[0261] When an alkyl (meth)acrylate and a hydroxyalkyl (meth)acrylate are used in combination, the mixing ratio of the hydroxyalkyl (meth)acrylate to 100 parts by mass of the alkyl (meth)acrylate is preferably 0.1 to 100 parts by mass, more preferably 0.5 to 30 parts by mass, even more preferably 1.0 to 20 parts by mass, and even more preferably 1.5 to 10 parts by mass.

[0262] The number of carbon atoms of the alkyl group of the alkyl (meth)acrylate is preferably 1 to 24, more preferably 1 to 12, even more preferably 1 to 8, and even more preferably 1 to 3.

[0263] Examples of the hydroxyalkyl (meth)acrylate include the same hydroxyalkyl (meth)acrylates as those used for introducing ethylenically unsaturated groups into both terminals of the linear urethane prepolymer.

[0264] Examples of vinyl compounds other than (meth)acrylates include aromatic hydrocarbon vinyl compounds such as styrene, α-methylstyrene, and vinyltoluene; vinyl ethers such as methyl vinyl ether and ethyl vinyl ether; polar group-containing monomers such as vinyl acetate, vinyl propionate, (meth)acrylonitrile, N-vinyl pyrrolidone, (meth)acrylic acid, maleic acid, fumaric acid, itaconic acid, and (meth)acrylamide; and the like.

[0265] These compounds may be used alone or in combination of two or more.

[0266] The content of the (meth)acrylate in the vinyl compound is preferably 40 to 100 mass %, more preferably 65 to 100 mass %, further preferably 80 to 100 mass %, and even more preferably 90 to 100 mass %, based on the total amount of the vinyl compound (100 mass %).

[0267] The total content of the alkyl (meth)acrylate and the hydroxyalkyl (meth)acrylate in the vinyl compound is preferably 40 to 100 mass %, more preferably 65 to 100 mass %, further preferably 80 to 100 mass %, and even more preferably 90 to 100 mass %, based on the total amount (100 mass %) of the vinyl compound.

[0268] The acrylic urethane resin (U1) used in one embodiment of the present invention can be obtained by mixing a urethane prepolymer (UP) and a vinyl compound containing a (meth)acrylate and polymerizing the mixture.

[0269] In this polymerization, it is preferred to further add a radical initiator.

[0270] In the acrylic urethane resin (U1) used in one embodiment of the present invention, the content ratio of the structural unit (u11) derived from the urethane prepolymer (UP) to the structural unit (u12) derived from the vinyl compound [(u11) / (u12)] is preferably 10 / 90 to 80 / 20, more preferably 20 / 80 to 70 / 30, further preferably 30 / 70 to 60 / 40, and even more preferably 35 / 65 to 55 / 45 in terms of mass ratio.

[0271] [Olefin resin]

[0272] The olefin-based resin preferably used as the resin contained in the resin composition (y-1) is a polymer having at least a structural unit derived from an olefin monomer.

[0273] The olefin monomer is preferably an α-olefin having 2 to 8 carbon atoms, and specific examples thereof include ethylene, propylene, butene, isobutylene, and 1-hexene.

[0274] Among these, ethylene and propylene are preferred.

[0275] Specific examples of olefin resins include ultra-low density polyethylene (VLDPE, density: 880 kg / m 3 Above and below 910kg / m 3 ), low-density polyethylene (LDPE, density: 910kg / m 3 Above and below 915kg / m 3 ), medium density polyethylene (MDPE, density: 915kg / m 3 Above and below 942kg / m 3 ), high-density polyethylene (HDPE, density: 942kg / m 3 above), linear low-density polyethylene and other polyethylene resins; polypropylene resin (PP); polybutene resin (PB); ethylene-propylene copolymer; olefin elastomer (TPO); poly (4-methyl-1-pentene) (PMP); ethylene-vinyl acetate copolymer (EVA); ethylene-vinyl alcohol copolymer (EVOH); olefin terpolymers such as ethylene-propylene-(5-ethylidene-2-norbornene); and the like.

[0276] In one embodiment of the present invention, the olefinic resin may be a modified olefinic resin further subjected to one or more modifications selected from the group consisting of acid modification, hydroxy modification, and acrylic modification.

[0277] For example, examples of the acid-modified olefin resin obtained by acid-modifying an olefin resin include modified polymers obtained by graft-polymerizing an unsaturated carboxylic acid or an anhydride thereof to the above-mentioned unmodified olefin resin.

[0278] Examples of the unsaturated carboxylic acid or anhydride thereof include maleic acid, fumaric acid, itaconic acid, citraconic acid, glutaconic acid, tetrahydrophthalic acid, aconitic acid, (meth)acrylic acid, maleic anhydride, itaconic anhydride, glutaconic anhydride, citraconic anhydride, aconitic anhydride, norbornene dicarboxylic anhydride, and tetrahydrophthalic anhydride.

[0279] In addition, the unsaturated carboxylic acid or its anhydride may be used alone or in combination of two or more.

[0280] Examples of acrylic-modified olefinic resins obtained by subjecting an olefinic resin to acrylic acid modification include modified polymers obtained by graft-polymerizing an alkyl (meth)acrylate as a side chain to the above-mentioned unmodified olefinic resin as a main chain.

[0281] The number of carbon atoms of the alkyl group of the alkyl (meth)acrylate is preferably 1 to 20, more preferably 1 to 16, and even more preferably 1 to 12.

[0282] Examples of the alkyl (meth)acrylate include the same compounds as those which can be selected as the monomer (a1′) described above.

[0283] Examples of the hydroxy-modified olefinic resin obtained by modifying an olefinic resin with a hydroxy group include modified polymers obtained by graft-polymerizing a hydroxyl-containing compound onto the above-mentioned unmodified olefinic resin as a main chain.

[0284] Examples of the hydroxyl group-containing compound include the same compounds as those described above.

[0285] [Resins other than acrylic urethane resins and olefin resins]

[0286] In one embodiment of the present invention, the resin composition (y-1) may contain resins other than the acrylic urethane resin and the olefin resin within a range that does not impair the effects of the present invention.

[0287] Examples of such resins include vinyl resins such as polyvinyl chloride, polyvinylidene chloride, and polyvinyl alcohol; polyester resins such as polyethylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate; polystyrene; acrylonitrile-butadiene-styrene copolymer; cellulose triacetate; polycarbonate; polyurethanes that are not acrylic urethane resins; polysulfone; polyetheretherketone; polyethersulfone; polyphenylene sulfide; polyimide resins such as polyetherimide and polyimide; polyamide resins; acrylic resins; fluororesins, etc.

[0288] Among them, from the viewpoint of easily forming irregularities on the adhesive surface of the adhesive layer (X1) and of achieving good sheet shape retention after thermal expansion, it is preferred that the content of resins other than the acrylic urethane resin and the olefin resin in the resin composition (y-1) is small.

[0289] The content of resins other than acrylic urethane resins and olefin resins is preferably less than 30 parts by mass, more preferably less than 20 parts by mass, further preferably less than 10 parts by mass, further preferably less than 5 parts by mass, and further preferably less than 1 part by mass, relative to 100 parts by mass of the total amount of resins contained in the resin composition (y-1).

[0290] (Additives for base materials)

[0291] The resin composition (y-1) may contain a substrate additive as needed within a range not impairing the effects of the present invention.

[0292] Examples of the additive for the substrate include ultraviolet absorbers, light stabilizers, antioxidants, antistatic agents, slip agents, antiblocking agents, and colorants.

[0293] In addition, these additives for substrates may be used alone or in combination of two or more.

[0294] When these additives for base materials are contained, the content of each additive for base materials is independently preferably 0.0001 to 20 parts by mass, more preferably 0.001 to 10 parts by mass, relative to 100 parts by mass of the resin.

[0295] (Solvent-free resin composition (y-1a))

[0296] As one embodiment of the resin composition (y-1) used in one embodiment of the present invention, there can be mentioned a solvent-free resin composition (y-1a) which is prepared by blending an oligomer having an ethylenically unsaturated group and a weight average molecular weight (Mw) of 50,000 or less, an energy beam polymerizable monomer, and the above-mentioned thermally expandable particles, and does not contain a solvent.

[0297] Although no solvent is blended in the solvent-free resin composition (y-1a), the energy-ray polymerizable monomer contributes to improvement in the plasticity of the oligomer.

[0298] By irradiating the solvent-free resin composition (y-1a) with energy rays, oligomers having an ethylenically unsaturated group, energy-ray polymerizable monomers, and the like are polymerized to form the heat-expandable base material layer (Y1).

[0299] The weight average molecular weight (Mw) of the oligomer contained in the solvent-free resin composition (y-1a) is 50,000 or less, preferably 1,000 to 50,000, more preferably 2,000 to 40,000, further preferably 3,000 to 35,000, and even more preferably 4,000 to 30,000.

[0300] The oligomer may be any resin having an ethylenically unsaturated group and a weight average molecular weight of 50,000 or less among the resins contained in the resin composition (y-1). The oligomer is preferably the urethane prepolymer (UP), and more preferably a linear urethane prepolymer having ethylenically unsaturated groups at both ends.

[0301] In addition, as this oligomer, a modified olefin resin having an ethylenically unsaturated group may also be used.

[0302] The total content of the above-mentioned oligomers and energy-ray polymerizable monomers in the solvent-free resin composition (y-1a) is preferably 50 to 99 mass %, more preferably 60 to 95 mass %, further preferably 65 to 90 mass %, and even more preferably 70 to 85 mass %, relative to the total amount (100 mass %) of the solvent-free resin composition (y-1a).

[0303] Examples of energy-ray polymerizable monomers include alicyclic polymerizable compounds such as isobornyl (meth)acrylate, dicyclopentenyl (meth)acrylate, dicyclopentanyl (meth)acrylate, dicyclopentenyloxy (meth)acrylate, cyclohexyl (meth)acrylate, adamantyl (meth)acrylate, and tricyclodecyl acrylate; aromatic polymerizable compounds such as phenylhydroxypropyl acrylate, benzyl acrylate, and phenol ethylene oxide-modified acrylate; and heterocyclic polymerizable compounds such as tetrahydrofurfuryl (meth)acrylate, morpholine acrylate, N-vinyl pyrrolidone, and N-vinylcaprolactam. Among these, isobornyl (meth)acrylate and phenylhydroxypropyl acrylate are preferred.

[0304] These energy-ray polymerizable monomers may be used alone or in combination of two or more.

[0305] The content ratio of the oligomer to the energy-beam-polymerizable monomer in the solvent-free resin composition (y-1a) [oligomer / energy-beam-polymerizable monomer] is preferably 20 / 80 to 90 / 10, more preferably 30 / 70 to 85 / 15, and even more preferably 35 / 65 to 80 / 20 by mass.

[0306] In one embodiment of the present invention, it is preferred that the solvent-free resin composition (y-1a) further contain a photopolymerization initiator.

[0307] By containing a photopolymerization initiator, the curing reaction can be sufficiently advanced by irradiation with energy rays having relatively low energy.

[0308] Examples of the photopolymerization initiator include 1-hydroxycyclohexyl phenyl ketone, benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin propyl ether, benzylphenyl sulfide, tetramethylthiuram monosulfide, azobisisobutyronitrile, bibenzyl, diacetyl, β-chloroanthraquinone, and phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide.

[0309] These photopolymerization initiators may be used alone or in combination of two or more.

[0310] The amount of the photopolymerization initiator to be added is preferably 0.01 to 5 parts by mass, more preferably 0.01 to 4 parts by mass, and even more preferably 0.02 to 3 parts by mass, relative to the total amount (100 parts by mass) of the oligomer and energy-ray-polymerizable monomer.

[0311] The resin composition (y-1) can be produced by mixing the above-mentioned components.

[0312] The method for mixing the components is not particularly limited, and may be appropriately selected from known mixing methods depending on the types of components used, the viscosity of the resin composition, and the like.

[0313] The resin composition (y-1) is a composition containing heat-expandable particles, and therefore, a dispersion treatment for improving the dispersibility of the heat-expandable particles may be performed. By improving the dispersibility of the heat-expandable particles in the resin composition (y-1), the surface of the heat-expandable substrate layer (Y1) becomes smoother, thereby further reducing the surface area (S) of the adhesive layer (X1) formed on the heat-expandable substrate layer (Y1). x1 ) is the arithmetic mean waviness (Wa).

[0314] Examples of methods for dispersing the heat-expandable particles include: stirring using a high-speed mixer such as a homomixer, homogenizer, planetary mixer, or ball mill to impart shear; ultrasonic treatment; and filtration to remove aggregates using a filter. Among these dispersion methods, it is preferred to appropriately determine a method and conditions that can improve dispersibility while maintaining the functionality of the heat-expandable particles.

[0315] The dispersion treatment of the heat-expandable particles may be performed after the heat-expandable particles are mixed with other components, or may be performed in a dispersion medium before the heat-expandable particles are mixed with other components.

[0316] (Thickness of the Heat-Expandable Base Material Layer (Y1))

[0317] In one embodiment of the present invention, the thickness of the heat-expandable base layer (Y1) before thermal expansion is preferably 30 to 300 μm, more preferably 40 to 270 μm, further preferably 50 to 240 μm, and even more preferably 55 to 220 μm.

[0318] When the thickness of the heat-expandable base material layer (Y1) before heat expansion is 30 μm or more, the occurrence of irregularities due to the heat-expandable particles before heat expansion is suppressed, and the surface area (S) of the adhesive layer (X1) can be further reduced. x1 ) and the adhesiveness tend to be improved. In addition, when the thickness of the heat-expandable base layer (Y1) before thermal expansion is 300 μm or less, the handling of the adhesive sheet tends to be easier.

[0319] <Non-thermal expansion base material layer (Y2)>

[0320] The non-heat-expandable base layer (Y2) included in the pressure-sensitive adhesive sheet of the first embodiment is provided on the surface of the heat-expandable base layer (Y1) opposite to the surface on which the pressure-sensitive adhesive layer (X1) is laminated.

[0321] The non-heat-expandable substrate layer (Y2) is preferably a non-adhesive substrate. The probe tack value of the surface of the non-heat-expandable substrate layer (Y2) is usually less than 50 mN / 5 mmφ, preferably less than 30 mN / 5 mmφ, more preferably less than 10 mN / 5 mmφ, and further preferably less than 5 mN / 5 mmφ.

[0322] Examples of the material for forming the non-thermally expandable base material layer (Y2) include resins, metals, and paper materials, and the material can be appropriately selected depending on the application of the pressure-sensitive adhesive sheet.

[0323] Examples of the resin include polyolefin resins such as polyethylene and polypropylene; vinyl resins such as polyvinyl chloride, polyvinylidene chloride, polyvinyl alcohol, ethylene-vinyl acetate copolymer, and ethylene-vinyl alcohol copolymer; polyester resins such as polyethylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate; polystyrene; acrylonitrile-butadiene-styrene copolymer; cellulose triacetate; polycarbonate; polyurethane resins such as polyurethane and acrylic modified polyurethane; polymethylpentene; polysulfone; polyetheretherketone; polyethersulfone; polyphenylene sulfide; polyimide resins such as polyetherimide and polyimide; polyamide resins; acrylic resins; fluororesins, etc.

[0324] Examples of the metal include aluminum, tin, chromium, and titanium.

[0325] Examples of the paper material include thin paper, medium-quality paper, high-quality paper, impregnated paper, coated paper, art paper, stencil paper, and glassine paper.

[0326] Among these, polyester resins such as polyethylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate are preferred.

[0327] These forming materials may be composed of one kind or two or more kinds may be used in combination.

[0328] Examples of the non-thermally expandable base material layer (Y2) formed by combining two or more materials include a material obtained by laminating a paper material with a thermoplastic resin such as polyethylene, and a material obtained by forming a metal film on the surface of a resin film or sheet containing a resin.

[0329] Examples of the method for forming the metal layer include a method of depositing the metal by PVD methods such as vacuum deposition, sputtering, and ion plating, and a method of attaching a metal foil made of the metal using a conventional adhesive.

[0330] It should be noted that, from the viewpoint of improving the interlayer adhesion between the non-heat-expandable base layer (Y2) and other laminated layers, when the non-heat-expandable base layer (Y2) contains a resin, the surface of the non-heat-expandable base layer (Y2) can also be subjected to surface treatment based on oxidation method, embossing method, etc., adhesion-facilitating treatment, or primer treatment in the same manner as the above-mentioned heat-expandable base layer (Y1).

[0331] Furthermore, when the non-thermally expandable base material layer (Y2) contains a resin, it may contain the above-mentioned base material additives that may be contained in the resin composition (y-1) together with the resin.

[0332] The non-heat-expandable base material layer (Y2) is a non-heat-expandable layer determined by the above-mentioned method.

[0333] Therefore, the volume change rate (%) of the non-heat-expandable base material layer (Y2) which can be calculated by the above formula is less than 5%, preferably less than 2%, more preferably less than 1%, further preferably less than 0.1%, and further preferably less than 0.01%.

[0334] Furthermore, the non-thermally expandable base layer (Y2) may contain thermally expandable particles as long as the volume change rate is within the above range. For example, by selecting the resin contained in the non-thermally expandable base layer (Y2), the volume change rate can be adjusted to the above range even if thermally expandable particles are contained.

[0335] In addition, the smaller the content of the heat-expandable particles in the non-heat-expandable base material layer (Y2), the more preferable it is.

[0336] Specifically, the content of the heat-expandable particles is generally less than 3% by mass, preferably less than 1% by mass, more preferably less than 0.1% by mass, further preferably less than 0.01% by mass, and even more preferably less than 0.001% by mass relative to the total mass (100% by mass) of the non-heat-expandable base material layer (Y2). It is further preferred that no heat-expandable particles are contained.

[0337] (Storage modulus E'(23) of the non-heat-expandable base material layer (Y2) at 23°C)

[0338] The storage modulus E'(23) of the non-heat-expandable base material layer (Y2) at 23°C is preferably 5.0×10 7 ~5.0×10 9 Pa, more preferably 5.0×108 ~4.5×10 9 Pa, more preferably 1.0×10 9 ~4.0×10 9 Pa.

[0339] The storage modulus E'(23) of the non-heat-expandable base material layer (Y2) is 5.0×10 7 When the value of Pa is greater than 1.5, the deformation resistance of the adhesive sheet can be improved. On the other hand, the storage modulus E'(23) of the non-heat-expandable substrate layer (Y2) is 5.0×10 9 When the viscosity is not more than Pa, the handleability of the pressure-sensitive adhesive sheet can be easily improved.

[0340] In addition, in this specification, the storage modulus E'(23) of the non-thermally expandable base material layer (Y2) represents a value measured by the method described in the Examples.

[0341] (Thickness of the non-thermally expandable base material layer (Y2))

[0342] The thickness of the non-thermally expandable substrate layer (Y2) is preferably 5 to 500 μm, more preferably 15 to 300 μm, and even more preferably 20 to 200 μm. When the thickness of the non-thermally expandable substrate layer (Y2) is 5 μm or greater, the deformation resistance of the adhesive sheet is easily improved. On the other hand, when the thickness of the non-thermally expandable substrate layer (Y2) is 500 μm or less, the handleability of the adhesive sheet is easily improved.

[0343] <Adhesive Layer (X2)>

[0344] The adhesive sheet of the first embodiment may also have an adhesive layer (X2) on the surface of the non-heat-expandable substrate layer (Y2) opposite to the laminated surface of the heat-expandable substrate layer (Y1). That is, the adhesive sheet of the first embodiment may be an adhesive sheet having a laminated structure in which the adhesive layer (X1), the heat-expandable substrate layer (Y1), the non-heat-expandable substrate layer (Y2), and the adhesive layer (X2) are arranged in this order.

[0345] The adhesive layer (X2) is preferably a non-thermally expandable layer.

[0346] When the adhesive layer (X2) is a non-thermally expandable layer, the volume change rate (%) of the adhesive layer (X2) calculated by the above formula is less than 5%, preferably less than 2%, more preferably less than 1%, further preferably less than 0.1%, and further preferably less than 0.01%.

[0347] The pressure-sensitive adhesive layer (X2) preferably does not contain heat-expandable particles, but may contain heat-expandable particles within a range that does not hinder the purpose of the present invention.

[0348] When the adhesive layer (X2) contains thermally expandable particles, the lower the content, the better. It is preferably less than 3 mass%, more preferably less than 1 mass%, further preferably less than 0.1 mass%, further preferably less than 0.01 mass%, and further preferably less than 0.001 mass%, relative to the total mass (100 mass%) of the adhesive layer (X2).

[0349] The adhesive layer (X2) is preferably an energy-ray-curable adhesive layer that is cured by irradiation with energy rays, thereby reducing the adhesive force. By making the adhesive layer (X2) an energy-ray-curable adhesive layer, the adhesive surface of the adhesive layer (X1) can be made in a form in which the adhesive force is reduced by heating, and the adhesive surface of the adhesive layer (X2) can be made in a form in which the adhesive force is reduced by irradiation with energy rays, thereby making the mechanism of action of the adhesive layers of each other that reduces the adhesive force different. Thus, when performing a process to reduce the adhesive force of any one adhesive layer, it is possible to avoid the situation in which the adhesive force of the other adhesive layer is also reduced unintentionally.

[0350] The adhesive layer (X2) is preferably formed from an adhesive composition (x-2) containing an adhesive resin. Hereinafter, each component contained in the adhesive composition (x-2) will be described.

[0351] The adhesive composition (x-2) is a composition containing an adhesive resin and may contain, as necessary, a crosslinking agent, a tackifier, a polymerizable compound, a polymerization initiator, and adhesive additives generally used in adhesives in addition to the above components.

[0352] (Adhesive resin)

[0353] The adhesive resin may be any polymer as long as it has adhesiveness as a single resin and has a weight average molecular weight (Mw) of 10,000 or more.

[0354] From the viewpoint of further improving the adhesive strength of the adhesive layer (X2), the weight average molecular weight (Mw) of the adhesive resin is preferably 10,000 to 2,000,000, more preferably 20,000 to 1,500,000, and even more preferably 30,000 to 1,000,000.

[0355] As the adhesive resin, there can be mentioned the same ones as the adhesive resin contained in the adhesive composition (x-1).

[0356] These adhesive resins may be used alone or in combination of two or more.

[0357] When these adhesive resins are copolymers having two or more structural units, the copolymer may be in the form of a block copolymer, a random copolymer, or a graft copolymer.

[0358] From the viewpoint of making the obtained adhesive layer (X2) a layer whose adhesive strength is reduced by curing upon irradiation with energy rays, the adhesive resin contained in the adhesive composition (x-2) is preferably an adhesive resin having an energy ray polymerizable functional group in its side chain.

[0359] Examples of the energy beam polymerizable functional group include functional groups having a carbon-carbon double bond, such as a (meth)acryloyl group, a vinyl group, and an allyl group.

[0360] From the viewpoint of exhibiting excellent adhesive strength, the adhesive resin preferably contains an acrylic resin.

[0361] The content of the acrylic resin in the adhesive composition (x-2) is preferably 30 to 100 mass %, more preferably 50 to 100 mass %, further preferably 70 to 100 mass %, and even more preferably 85 to 100 mass %, relative to the total amount (100 mass %) of the adhesive resin contained in the adhesive composition (x-2).

[0362] Relative to the total amount (100 mass%) of the active ingredients of the adhesive composition (x-2), the content of the adhesive resin in the adhesive composition (x-2) is preferably 35 to 100 mass%, more preferably 50 to 100 mass%, further preferably 60 to 98 mass%, and further preferably 70 to 95 mass%.

[0363] (Energy ray curable compound)

[0364] The adhesive composition (x-2) may contain, in addition to the adhesive resin, a monomer or oligomer that can be polymerized and cured by irradiation with energy rays as an energy-ray-curable compound.

[0365] Examples of such energy-ray-curable compounds include poly(meth)acrylate monomers such as trimethylolpropane tri(meth)acrylate, pentaerythritol (meth)acrylate, pentaerythritol tetra(meth)acrylate, dipentaerythritol hexa(meth)acrylate, 1,4-butanediol di(meth)acrylate, and 1,6-hexanediol (meth)acrylate; and oligomers such as polyfunctional urethane (meth)acrylate, polyfunctional polyester (meth)acrylate, polyfunctional polyether (meth)acrylate, and polyfunctional epoxy (meth)acrylate.

[0366] Among these, polyfunctional urethane (meth)acrylate oligomers are preferred because they have a relatively high molecular weight and are less likely to cause a decrease in the elastic modulus of the pressure-sensitive adhesive layer (X2).

[0367] The molecular weight (weight average molecular weight (Mw) in the case of an oligomer) of the energy ray curable compound is preferably 100 to 12,000, more preferably 200 to 10,000, further preferably 400 to 8,000, and still further preferably 600 to 6,000.

[0368] (Photopolymerization initiator)

[0369] The adhesive composition (x-2) preferably further contains a photopolymerization initiator.

[0370] By containing a photopolymerization initiator, polymerization of the energy-ray polymerizable component can be more efficiently carried out.

[0371] Examples of the photopolymerization initiator include the same ones as those exemplified in the description of the solvent-free resin composition (y-1a). Among them, 1-hydroxycyclohexyl phenyl ketone is preferred.

[0372] The content of the photopolymerization initiator is preferably 0.01 to 10 parts by mass, more preferably 0.03 to 5 parts by mass, and even more preferably 0.05 to 2 parts by mass, based on 100 parts by mass of the total amount of the adhesive resin having an energy ray polymerizable functional group.

[0373] (cross-linking agent)

[0374] In one embodiment of the present invention, when the adhesive composition (x-2) contains an adhesive resin having a functional group, it is preferred that the adhesive composition (x-2) further contain a crosslinking agent.

[0375] The crosslinking agent is a component that reacts with the adhesive resin having a functional group to crosslink the adhesive resins with the functional group serving as a crosslinking starting point.

[0376] As the cross-linking agent optionally contained in the adhesive composition (x-2), those that are the same as or equivalent to the cross-linking agent optionally contained in the adhesive composition (x-1) can be listed, but from the perspective of improving cohesive force and thus improving adhesive force, and from the perspective of easy availability, isocyanate cross-linking agents are preferred.

[0377] The content of the crosslinking agent can be appropriately adjusted depending on the number of functional groups in the adhesive resin, but is preferably 0.01 to 10 parts by mass, more preferably 0.03 to 7 parts by mass, and even more preferably 0.05 to 5 parts by mass per 100 parts by mass of the adhesive resin having functional groups.

[0378] (Thickener)

[0379] In one embodiment of the present invention, the adhesive composition (x-2) may further contain a tackifier from the viewpoint of further improving adhesive strength.

[0380] As the tackifier optionally contained in the adhesive composition (x-2), those that are the same as or equivalent to those optionally contained in the adhesive composition (x-1) can be used.

[0381] (Additives for adhesives)

[0382] Examples of the adhesive additive include the same ones as those optionally contained in the adhesive composition (x-1).

[0383] The adhesive composition (x-2) can be produced by mixing an adhesive resin and, if necessary, a cross-linking agent, a tackifier, an adhesive additive, and the like.

[0384] (Adhesive Strength of Adhesive Layer (X2) Before Energy Ray Irradiation)

[0385] The adhesive strength of the adhesive layer (X2) before energy ray irradiation is preferably 1.1 to 30.0 N / 25 mm, more preferably 3.0 to 25.0 N / 25 mm, further preferably 5.0 to 20.0 N / 25 mm.

[0386] When the adhesive strength of the adhesive layer (X2) before energy ray irradiation is 1.1 N / 25 mm or more, unexpected peeling from the adherend, displacement of the adherend, etc. can be more effectively suppressed. On the other hand, when the adhesive strength is 30.0 N / 25 mm or less, the releasability after energy ray irradiation can be further improved.

[0387] In addition, the adhesive strength of the adhesive layer (X2) before energy ray irradiation can be measured by the above-mentioned method.

[0388] (Adhesive Strength of Adhesive Layer (X2) after Energy Ray Irradiation)

[0389] The adhesive strength of the adhesive layer (X2) after energy ray irradiation is preferably 1.0 N / 25 mm or less, more preferably 0.9 N / 25 mm or less, further preferably 0.8 N / 25 mm or less, and even more preferably 0.7 N / 25 mm or less. The lower limit of the adhesive strength of the adhesive layer (X2) after energy ray irradiation is not particularly limited and may be 0 N / 25 mm or more.

[0390] When the adhesive strength of the pressure-sensitive adhesive layer (X2) after energy ray irradiation is 1.0 N / 25 mm or less, the pressure-sensitive adhesive layer (X2) will have further excellent releasability from an adherend.

[0391] It should be noted that the adhesive strength of the adhesive layer (X2) after energy ray irradiation can be measured by irradiating the adhesive layer (X2) with an illuminance of 230 mW / cm 2 , light intensity 90mJ / cm 2The measurement was performed by the above-mentioned method on a pressure-sensitive adhesive sheet obtained by irradiating the adhesive sheet with ultraviolet rays.

[0392] (Thickness of adhesive layer (X2))

[0393] The thickness of the adhesive layer (X2) of the adhesive sheet of the first embodiment is preferably 5 to 150 μm, more preferably 8 to 100 μm, further preferably 12 to 70 μm, and even more preferably 15 to 50 μm.

[0394] When the thickness of the adhesive layer (X2) is 5 μm or more, sufficient adhesive strength is easily obtained, and unexpected peeling from the adherend during temporary fixing, displacement of the adherend, etc. tend to be suppressed. On the other hand, when the thickness of the adhesive layer (X2) is 150 μm or less, there is a tendency for the adhesive sheet to be easily handled.

[0395] <Method for Manufacturing PSA Sheet of First Aspect>

[0396] The method for producing the PSA sheet of the first embodiment is not particularly limited, and examples thereof include a method for producing a PSA sheet comprising the following steps (1a) to (3a).

[0397] ■Step (1a): A step of applying the adhesive composition (x-1) on the release-treated surface of the release material to form the adhesive layer (X1).

[0398] ■Step (2a): A step of applying the resin composition (y-1) on one side of the non-heat-expandable base layer (Y2) to form a base layer laminate comprising the non-heat-expandable base layer (Y2) and the heat-expandable base layer (Y1).

[0399] ■ Step (3a): A step of laminating the adhesive surface of the adhesive layer (X1) formed in step (1a) and the surface of the substrate laminate formed in step (2a) on the side of the heat-expandable substrate layer (Y1) to obtain an adhesive sheet.

[0400] In addition, when the adhesive sheet of the first embodiment has a laminated structure in which an adhesive layer (X1), a base layer (Y) and an adhesive layer (X2) are arranged in this order, the adhesive sheet can be manufactured by a method further including the following steps (4a) and (5a).

[0401] ■Step (4a): A step of applying the adhesive composition (x-2) onto the release-treated surface of the release material to form the adhesive layer (X2).

[0402] ■ Step (5a): A step of laminating the adhesive surface of the adhesive layer (X2) formed in step (4a) to the surface of the adhesive sheet formed in step (3a) on the non-heat-expandable base material layer (Y2) side.

[0403] In the above-mentioned method for producing an adhesive sheet, the resin composition (y-1), the adhesive composition (x-1), and the adhesive composition (x-2) may be further mixed with a dilution solvent to form a solution.

[0404] Examples of the coating method include spin coating, spray coating, wire bar coating, knife coating, roll coating, blade coating, die coating, and gravure coating.

[0405] In addition, the step of drying the coating film formed from the resin composition (y-1), the adhesive composition (x-1) and the adhesive composition (x-2) is preferably carried out under conditions where the drying temperature is lower than the expansion starting temperature (t) of the thermally expandable particles from the viewpoint of suppressing the expansion of the thermally expandable particles.

[0406] [Second Embodiment of Pressure-Sensitive Adhesive Sheet]

[0407] The second embodiment of the PSA sheet has a laminated structure including a substrate layer (Y) and a PSA layer (X1) serving as a thermally expandable layer.

[0408] The second embodiment of the adhesive sheet may also include an adhesive layer (X2) on the surface of the substrate layer (Y) opposite to the laminated surface of the adhesive layer (X1). In other words, the second embodiment of the adhesive sheet may also include a laminated structure in which the adhesive layer (X1) as a heat-expandable layer, the substrate layer (Y), and the adhesive layer (X2) are sequentially arranged.

[0409] The description of the substrate layer (Y) of the second embodiment of the adhesive sheet is the same as the description of the non-heat-expandable substrate layer (Y2) in the first embodiment of the adhesive sheet. In addition, the description of the adhesive layer (X2) optionally included in the second embodiment of the adhesive sheet is the same as the description of the adhesive layer (X2) optionally included in the first embodiment of the adhesive sheet.

[0410] <Adhesive Layer (X1)>

[0411] The pressure-sensitive adhesive layer (X1) of the second embodiment is a heat-expandable layer containing heat-expandable particles, and preferably contains a polymer of an energy-beam-polymerizable component and heat-expandable particles.

[0412] Among the above-mentioned polymers, the energy-ray polymerizable component is a polymer obtained by irradiating a polymerizable composition (hereinafter also referred to as "polymerizable composition (x-1')") containing a monomer (b1) having an energy-ray polymerizable functional group (hereinafter also referred to as "(b1) component") and a prepolymer (b2) having an energy-ray polymerizable functional group (hereinafter also referred to as "(b2) component") with energy rays.

[0413] In addition, in this specification, a prepolymer means a compound which is formed by polymerizing a monomer and can constitute a polymer by further polymerization.

[0414] The energy-ray polymerizable component contained in the polymerizable composition (x-1′) is a component that polymerizes upon irradiation with energy rays, and has an energy-ray polymerizable functional group.

[0415] Examples of energy-ray-polymerizable functional groups include functional groups having a carbon-carbon double bond, such as a (meth)acryloyl group, a vinyl group, and an allyl group. It should be noted that in the following description, functional groups partially containing a vinyl group or a substituted vinyl group, such as a (meth)acryloyl group and an allyl group, and the vinyl group or the substituted vinyl group themselves may be collectively referred to as "vinyl-containing groups."

[0416] Hereinafter, each component contained in the polymerizable composition (x-1) will be described.

[0417] (Monomer (b1) having an energy-ray polymerizable functional group)

[0418] The monomer (b1) having an energy-ray polymerizable functional group may be any monomer as long as it has an energy-ray polymerizable functional group, and may have a hydrocarbon group or a functional group other than the energy-ray polymerizable functional group in addition to the energy-ray polymerizable functional group.

[0419] Examples of the hydrocarbon group contained in the component (b1) include an aliphatic hydrocarbon group, an aromatic hydrocarbon group, and a group composed of a combination of these hydrocarbon groups.

[0420] The aliphatic hydrocarbon group may be a linear or branched aliphatic hydrocarbon group, or may be an alicyclic hydrocarbon group.

[0421] Examples of the linear or branched aliphatic hydrocarbon group include aliphatic hydrocarbon groups having 1 to 20 carbon atoms, such as methyl, ethyl, n-propyl, isopropyl, n-butyl, tert-butyl, sec-butyl, n-pentyl, n-hexyl, 2-ethylhexyl, n-octyl, isooctyl, n-decyl, n-dodecyl, n-myristyl, n-palmityl, and n-stearyl.

[0422] Examples of the alicyclic hydrocarbon group include alicyclic hydrocarbon groups having 3 to 20 carbon atoms, such as a cyclopentyl group, a cyclohexyl group, and an isobornyl group.

[0423] Examples of the aromatic hydrocarbon group include a phenyl group.

[0424] Examples of the group formed by combining an aliphatic hydrocarbon group and an aromatic hydrocarbon group include a phenoxyethyl group and a benzyl group.

[0425] Among these hydrocarbon groups, from the viewpoint of further improving the adhesive strength of the adhesive layer (X1), the (b1) component preferably contains a monomer (b1-1) having an energy-ray polymerizable functional group and a linear or branched aliphatic hydrocarbon group (hereinafter also referred to as "(b1-1) component"), a monomer (b1-2) having an energy-ray polymerizable functional group and an alicyclic hydrocarbon group (hereinafter also referred to as "(b1-2) component"), etc.

[0426] When the component (b1) contains the component (b1-1), the content thereof is preferably 20 to 80 mass %, more preferably 40 to 70 mass %, and even more preferably 50 to 60 mass % relative to the total amount (100 mass %) of the component (b1).

[0427] When the component (b1) contains the component (b1-2), the content thereof is preferably 5 to 60 mass%, more preferably 10 to 40 mass%, and even more preferably 20 to 30 mass%, relative to the total amount (100 mass%) of the component (b1).

[0428] Examples of monomers having an energy-ray polymerizable functional group and a functional group other than the energy-ray polymerizable functional group include monomers having a hydroxyl group, a carboxyl group, a thiol group, a primary amino group, or a secondary amino group as a functional group other than the energy-ray polymerizable functional group. Among these functional groups, from the viewpoint of further improving the formability of the adhesive layer (X1), it is preferred that the component (b1) contain a monomer (b1-3) having an energy-ray polymerizable functional group and a hydroxyl group (hereinafter also referred to as "component (b1-3)").

[0429] When the component (b1) contains the component (b1-3), the content thereof is preferably 1 to 60 mass %, more preferably 5 to 30 mass %, and even more preferably 10 to 20 mass % relative to the total amount (100 mass %) of the component (b1).

[0430] The number of energy-ray polymerizable functional groups possessed by the component (b1) may be 1 or 2 or more. In addition, from the viewpoint of further improving the releasability of the adhesive layer (X1), it is preferred that the component (b1) contain a monomer (b1-4) having 3 or more energy-ray polymerizable functional groups (hereinafter also referred to as "component (b1-4)").

[0431] When the component (b1) contains the component (b1-4), the content thereof is preferably 1 to 20 mass %, more preferably 2 to 15 mass %, and even more preferably 3 to 10 mass % relative to the total amount (100 mass %) of the component (b1).

[0432] As the monomer having one energy-ray polymerizable functional group, a monomer having one vinyl group (hereinafter also referred to as a "polymerizable vinyl monomer") is preferred.

[0433] The monomer having two or more energy-ray-polymerizable functional groups is preferably a monomer having two or more (meth)acryloyl groups (hereinafter also referred to as a "multifunctional (meth)acrylate monomer"). By including the above-mentioned compounds in the component (b1), the cohesive strength of the adhesive obtained by polymerization thereof is improved, and it is possible to form an adhesive layer (X1) that is less contaminated by the adherend after peeling.

[0434] [Polymerizable vinyl monomer]

[0435] The polymerizable vinyl monomer is not particularly limited as long as it is a monomer having a vinyl group, and conventionally known ones can be appropriately used.

[0436] The polymerizable vinyl monomers may be used alone or in combination of two or more.

[0437] Examples of polymerizable vinyl monomers include compounds corresponding to the above-mentioned component (b1-1), such as methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, butyl (meth)acrylate, pentyl (meth)acrylate, hexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, isooctyl (meth)acrylate, decyl (meth)acrylate, dodecyl (meth)acrylate, myristyl (meth)acrylate, palmityl (meth)acrylate, and stearyl (meth)acrylate; compounds corresponding to the above-mentioned component (b1-2), such as cyclohexyl (meth)acrylate and isobornyl (meth)acrylate; and (meth)acrylates having no functional groups other than vinyl groups in the molecule, such as phenoxyethyl (meth)acrylate, benzyl (meth)acrylate, and polyoxyalkylene-modified (meth)acrylate. Among these, 2-ethylhexyl acrylate and isobornyl acrylate are preferred.

[0438] The polymerizable vinyl monomer may also be a monomer having a functional group other than a vinyl group in the molecule. Examples of such functional groups include hydroxyl, carboxyl, thiol, primary or secondary amino groups. Of these functional groups, polymerizable vinyl monomers having a hydroxyl group, such as those in component (b1-3) above, are preferred.

[0439] Examples of polymerizable vinyl monomers having a hydroxyl group include hydroxyalkyl (meth)acrylates such as 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 3-hydroxybutyl (meth)acrylate, and 4-hydroxybutyl (meth)acrylate; and hydroxyl-containing acrylamides such as N-methylol acrylamide and N-methylol methacrylamide. Examples of polymerizable vinyl monomers having a carboxyl group include ethylenically unsaturated carboxylic acids such as acrylic acid, methacrylic acid, crotonic acid, maleic acid, itaconic acid, and citraconic acid. Among these monomers, 2-hydroxyethyl acrylate and 4-hydroxybutyl acrylate are preferred.

[0440] In addition, other polymerizable vinyl monomers include, for example: vinyl esters such as vinyl acetate and vinyl propionate; olefins such as ethylene, propylene, and isobutylene; halogenated olefins such as vinyl chloride and vinylidene chloride; styrene monomers such as styrene and α-methylstyrene; diene monomers such as butadiene, isoprene, and chloroprene; nitrile monomers such as acrylonitrile and methacrylonitrile; amide monomers such as acrylamide, methacrylamide, N-methylacrylamide, N-methylmethacrylamide, N,N-dimethyl(meth)acrylamide, N,N-diethyl(meth)acrylamide, and N-vinylpyrrolidone; tertiary amino group-containing monomers such as N,N-diethylaminoethyl(meth)acrylate and N-(meth)acryloylmorpholine, etc.

[0441] [Multifunctional (meth)acrylate monomer]

[0442] The polyfunctional (meth)acrylate monomer is not particularly limited as long as it has two or more (meth)acryloyl groups in one molecule, and conventionally known ones can be appropriately used.

[0443] The polyfunctional (meth)acrylate monomers may be used alone or in combination of two or more.

[0444] Examples of the multifunctional (meth)acrylate monomer include: 1,4-butanediol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, neopentyl glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate, neopentyl glycol adipate di(meth)acrylate, hydroxypivalate neopentyl glycol di(meth)acrylate, dicyclopentanyl di(meth)acrylate, caprolactone-modified dicyclopentanyl di(meth)acrylate, ethylene oxide-modified phosphoric acid di(meth)acrylate, di(acryloyloxyethyl)isocyanurate, allylated cyclohexyl di(meth)acrylate, isocyanuric acid ethylene oxide-modified diacrylate, and bifunctional (meth)acrylate monomers such as trimethylolpropane tri(meth)acrylate, dipentylethylene glycol di(meth)acrylate, and diisocyanuric acid ethylene oxide-modified diacrylate. Polyfunctional (meth)acrylate monomers corresponding to the above-mentioned component (b1-4) such as tetraol tri(meth)acrylate, propionic acid-modified dipentaerythritol tri(meth)acrylate, pentaerythritol tri(meth)acrylate, propylene oxide-modified trimethylolpropane tri(meth)acrylate, tris(acryloyloxyethyl)isocyanurate, bis(acryloyloxyethyl)hydroxyethyl isocyanurate, isocyanuric acid ethylene oxide-modified triacrylate, ε-caprolactone-modified tri(acryloyloxyethyl)isocyanurate, diglycerol tetra(meth)acrylate, pentaerythritol tetra(meth)acrylate, propionic acid-modified dipentaerythritol penta(meth)acrylate, dipentaerythritol hexa(meth)acrylate, and caprolactone-modified dipentaerythritol hexa(meth)acrylate.

[0445] Content of ingredient (b1)

[0446] The total content of the polymerizable vinyl monomers in the polymerizable composition (x-1') is preferably 10 to 80 mass%, more preferably 30 to 75 mass%, and even more preferably 50 to 70 mass%, relative to the total amount (100 mass%) of the active ingredients in the polymerizable composition (x-1').

[0447] The total content of the polyfunctional (meth)acrylate monomers in the polymerizable composition (x-1') is preferably 0.5 to 15 mass %, more preferably 1 to 10 mass %, and even more preferably 2 to 5 mass %, relative to the total amount (100 mass %) of the active ingredients in the polymerizable composition (x-1').

[0448] The total content of the components (b1) in the polymerizable composition (x-1') is preferably 15 to 90 mass%, more preferably 35 to 80 mass%, and even more preferably 55 to 75 mass%, relative to the total amount (100 mass%) of the active ingredients in the polymerizable composition (x-1').

[0449] (Prepolymer (b2) having an energy-ray-polymerizable functional group)

[0450] Examples of the prepolymer (b2) having an energy-ray polymerizable functional group include a prepolymer having one energy-ray polymerizable functional group, a prepolymer having two or more energy-ray polymerizable functional groups, etc. Among these prepolymers, from the viewpoint of forming an adhesive layer having excellent releasability and little contamination of the adherend after peeling, the component (b2) preferably contains a prepolymer having two or more energy-ray polymerizable functional groups, more preferably contains a prepolymer having two energy-ray polymerizable functional groups, and even more preferably contains a prepolymer having two energy-ray polymerizable functional groups and having the energy-ray polymerizable functional groups at both ends.

[0451] The component (b2) preferably contains a prepolymer having two or more (meth)acryloyl groups as energy-ray polymerizable functional groups (hereinafter also referred to as a "multifunctional (meth)acrylate prepolymer"). By including such a compound in the component (b2), the cohesive strength of the adhesive obtained by polymerization thereof is improved, and a pressure-sensitive adhesive layer (X1) having excellent releasability and minimal contamination by adherends after peeling can be formed.

[0452] [Multifunctional (meth)acrylate prepolymer]

[0453] The polyfunctional (meth)acrylate prepolymer is not particularly limited as long as it has two or more (meth)acryloyl groups in one molecule, and conventionally known ones can be appropriately used.

[0454] The multifunctional (meth)acrylate prepolymer may be used alone or in combination of two or more.

[0455] Examples of the polyfunctional (meth)acrylate prepolymer include urethane acrylate prepolymers, polyester acrylate prepolymers, epoxy acrylate prepolymers, polyether acrylate prepolymers, polybutadiene acrylate prepolymers, silicone acrylate prepolymers, and polyacryloyl acrylate prepolymers.

[0456] Urethane acrylate prepolymers can be obtained by esterifying a polyurethane prepolymer obtained, for example, by reacting a polyisocyanate with a compound such as a polyalkylene polyol, a polyether polyol, a polyester polyol, hydroxyl-terminated hydrogenated isoprene, or hydroxyl-terminated hydrogenated butadiene using (meth)acrylic acid or a (meth)acrylic acid derivative.

[0457] Examples of polyalkylene polyols that can be used in the production of urethane acrylate prepolymers include polypropylene glycol, polyethylene glycol, polybutylene glycol, and polyethylene glycol. Among these, polypropylene glycol is preferred. It should be noted that, to obtain a urethane acrylate prepolymer having three or more functional groups, an appropriate combination of glycerol, trimethylolpropane, triethanolamine, pentaerythritol, ethylenediamine, diethylenetriamine, sorbitol, and sucrose may be used.

[0458] Examples of polyisocyanates that can be used in the production of urethane acrylate prepolymers include aliphatic diisocyanates such as hexamethylene diisocyanate and trimethylene diisocyanate; aromatic diisocyanates such as toluene diisocyanate, xylene diisocyanate, and diphenyl diisocyanate; and alicyclic diisocyanates such as dicyclohexylmethane diisocyanate and isophorone diisocyanate. Of these polyisocyanates, aliphatic diisocyanates are preferred, with hexamethylene diisocyanate being more preferred. It should be noted that polyisocyanates are not limited to difunctional ones; trifunctional or higher-functional polyisocyanates may also be used.

[0459] Examples of (meth)acrylic acid derivatives that can be used in the production of urethane acrylate prepolymers include hydroxyalkyl (meth)acrylates such as 2-hydroxyethyl acrylate and 4-hydroxybutyl acrylate; 2-isocyanoethyl acrylate, 2-isocyanoethyl methacrylate, and 1,1-bis(acryloyloxymethyl)ethyl isocyanate. Among these (meth)acrylic acid derivatives, 2-isocyanoethyl acrylate is preferred.

[0460] Other methods for producing urethane acrylate prepolymers include reacting hydroxyl groups of compounds such as polyalkylene polyols, polyether polyols, polyester polyols, hydroxyl-terminated hydrogenated isoprene, and hydroxyl-terminated hydrogenated butadiene with the -N=C=O moiety of an isocyanoalkyl (meth)acrylate. In this case, examples of the isocyanoalkyl (meth)acrylate include the aforementioned 2-isocyanoethyl acrylate, 2-isocyanoethyl methacrylate, and 1,1-bis(acryloyloxymethyl)ethyl isocyanate.

[0461] Polyester acrylate prepolymers can be obtained, for example, by esterifying the hydroxyl groups of a polyester prepolymer having hydroxyl groups at both ends, obtained by condensing a polycarboxylic acid and a polyol, with (meth)acrylic acid. Alternatively, they can be obtained by esterifying the terminal hydroxyl groups of a prepolymer obtained by adding an alkylene oxide to a polycarboxylic acid with (meth)acrylic acid.

[0462] Epoxy acrylate prepolymers can be obtained, for example, by reacting the epoxy rings of relatively low molecular weight bisphenol epoxy resins, novolac epoxy resins, etc. with (meth)acrylic acid for esterification. Alternatively, carboxyl-modified epoxy acrylate prepolymers, which are obtained by partially modifying the epoxy acrylate prepolymer with a dicarboxylic acid anhydride, can also be used.

[0463] The polyether acrylate-based prepolymer can be obtained, for example, by esterifying the hydroxyl group of polyether polyol with (meth)acrylic acid.

[0464] Polyacryloyl acrylate prepolymers may have acryloyl groups in their side chains, or at both or one of their terminals. Polyacryloyl acrylate prepolymers having acryloyl groups in their side chains can be obtained, for example, by adding glycidyl methacrylate to the carboxyl groups of polyacrylic acid. Furthermore, polyacryloyl acrylate prepolymers having acryloyl groups at both terminals can be obtained, for example, by introducing acryloyl groups into a long-terminal structure by polymerizing a polyacrylate prepolymer synthesized by ATRP (Atom Transfer Radical Polymerization).

[0465] The weight average molecular weight (Mw) of the component (b2) is preferably 10,000 to 350,000, more preferably 15,000 to 200,000, and even more preferably 20,000 to 50,000.

[0466] Content of ingredient (b2)

[0467] The total content of the polyfunctional (meth)acrylate prepolymer in the polymerizable composition (x-1') is preferably 10 to 60 mass%, more preferably 15 to 55 mass%, and even more preferably 20 to 30 mass%, relative to the total amount (100 mass%) of the active ingredients in the polymerizable composition (x-1').

[0468] The total content of the components (b2) in the polymerizable composition (x-1') is preferably 10 to 60 mass%, more preferably 15 to 55 mass%, and even more preferably 20 to 30 mass%, relative to the total amount (100 mass%) of the active ingredients in the polymerizable composition (x-1').

[0469] The content ratio of the components (b2) and (b1) in the polymerizable composition (x-1') [(b2) / (b1)] is preferably 10 / 90 to 70 / 30, more preferably 20 / 80 to 50 / 50, and even more preferably 25 / 75 to 40 / 60.

[0470] Among the energy-ray polymerizable components, the polymerizable composition (x-1′) preferably contains a polymerizable vinyl monomer, a polyfunctional (meth)acrylate monomer, and a polyfunctional (meth)acrylate prepolymer.

[0471] The total content of the polymerizable vinyl monomer, the polyfunctional (meth)acrylate monomer, and the polyfunctional (meth)acrylate prepolymer in the energy-ray polymerizable components contained in the polymerizable composition (x-1′) is preferably 80% by mass or more, more preferably 90% by mass or more, further preferably 95% by mass or more, even more preferably 99% by mass or more, and may also be 100% by mass, relative to the total amount (100% by mass) of the energy-ray polymerizable components.

[0472] The total content of the energy-ray polymerizable components in the polymerizable composition (x-1') is preferably 70 to 98 mass%, more preferably 75 to 97 mass%, further preferably 80 to 96 mass%, and even more preferably 82 to 95 mass%, relative to the total amount (100 mass%) of the active ingredients in the polymerizable composition (x-1').

[0473] (Other ingredients)

[0474] The polymerizable composition (x-1′) may contain other components in addition to the energy beam polymerizable component and the thermally expandable particles.

[0475] Examples of the other components include photopolymerization initiators, tackifiers, and adhesive additives generally used for adhesives other than the above-mentioned components.

[0476] Examples of these components include the same ones as described in the pressure-sensitive adhesive sheet of the first embodiment.

[0477] The polymerizable composition (x-1') may contain a solvent such as a diluent within the scope of the present invention, but preferably contains no solvent. In other words, the polymerizable composition (x-1') is preferably a solvent-free polymerizable composition.

[0478] By using a solvent-free polymerizable composition (x-1′), heat drying of the solvent can be omitted when forming the adhesive layer (X1), thereby suppressing expansion of the heat-expandable particles during heat drying.

[0479] When the polymerizable composition (x-1′) contains a solvent, the smaller the content, the better. It is preferably 10% by mass or less, more preferably 1% by mass or less, further preferably 0.1% by mass or less, and even more preferably 0.01% by mass or less, relative to the total amount (100% by mass) of the active ingredients in the polymerizable composition (x-1).

[0480] The polymerizable composition (x-1′) can be produced by mixing an energy-beam polymerizable component, thermally expandable particles, and other components as needed.

[0481] The method for mixing the components is not particularly limited, and may be appropriately selected from known mixing methods depending on the types of components used, the viscosity of the resin composition, and the like.

[0482] Since the polymerizable composition (X-1') contains heat-expandable particles, a dispersion treatment may be performed to improve the dispersibility of the heat-expandable particles in the polymerizable composition (X-1'). By improving the dispersibility of the heat-expandable particles, the surface of the adhesive layer (X1) becomes smoother, thereby further reducing the surface area (S) of the adhesive layer (X1). x1 ) is the arithmetic mean waviness (Wa).

[0483] Examples of the method for dispersing the heat-expandable particles include the same methods as those mentioned in the description of the "resin composition (y-1)" in the "pressure-sensitive adhesive sheet of the first embodiment."

[0484] Since the polymerizable composition (x-1') subsequently undergoes energy-beam polymerization and thus has a high molecular weight, a low-molecular-weight energy-beam-polymerizable component can be used to adjust the viscosity to an appropriate level during layer formation. Therefore, the polymerizable composition (x-1') can be used directly as a coating solution for forming the adhesive layer (X1) without the addition of a solvent such as a diluent.

[0485] It should be noted that the adhesive layer (X1) formed by irradiating the polymerizable composition (X-1') with energy rays contains a variety of polymers polymerized from energy-ray-polymerizable components and thermally expandable particles dispersed in the polymers. However, in some cases, it is impossible or almost impractical to directly define them based on their structure and physical properties.

[0486] (Adhesive Strength of Adhesive Layer (X1))

[0487] The description of the adhesive strength of the adhesive layer (X1) before thermal expansion and the adhesive strength after thermal expansion in the second embodiment of the adhesive sheet is the same as the description of the adhesive strength of the adhesive layer (X1) before thermal expansion of the heat-expandable substrate layer (Y1) and the adhesive strength of the adhesive layer (X1) after thermal expansion of the heat-expandable substrate layer (Y1) in the description of the first embodiment of the adhesive sheet.

[0488] (Thickness of Adhesive Layer (X1))

[0489] The thickness of the adhesive layer (X1) before thermal expansion of the adhesive sheet of the second embodiment is preferably 20 to 270 μm, more preferably 30 to 240 μm, further preferably 40 to 220 μm, and even more preferably 50 to 200 μm.

[0490] When the thickness of the adhesive layer (X1) before thermal expansion is 20 μm or more, the occurrence of irregularities due to the thermally expandable particles before thermal expansion is suppressed, and the surface area (S) of the adhesive layer (X1) can be further reduced. x1 ) and the adhesiveness tend to be improved. In addition, when the thickness of the adhesive layer (X1) before thermal expansion is 270 μm or less, the handling of the adhesive sheet tends to be easier.

[0491] <Method for Manufacturing the Second PSA Sheet>

[0492] The second embodiment of the method for producing a pressure-sensitive adhesive sheet is preferably a method for producing a pressure-sensitive adhesive sheet in which the method for forming the pressure-sensitive adhesive layer (X1) includes irradiating a polymerizable composition (x-1′) containing the above-mentioned energy-ray polymerizable component and the above-mentioned heat-expandable particles with energy rays to form a polymer of the above-mentioned energy-ray polymerizable component. Specifically, the method is more preferably a method for producing a pressure-sensitive adhesive sheet including the following steps (1b) and (2b).

[0493] Step (1b): a step of forming a polymerizable composition layer composed of a polymerizable composition (x-1′) on one side of a substrate (Y)

[0494] Step (2b): a step of irradiating the polymerizable composition layer with energy rays to form a polymer of the energy ray polymerizable component, thereby forming an adhesive layer (X1) containing the polymer and the heat-expandable particles, thereby obtaining an adhesive sheet.

[0495] In addition, when the adhesive sheet of the second embodiment has a laminated structure in which the adhesive layer (X1), the base layer (Y) and the adhesive layer (X2) are arranged in this order, the adhesive sheet can be produced by a method further including the following step (3b).

[0496] Step (3b): a step of forming an adhesive layer (X2) on the surface of the substrate layer (Y) of the adhesive sheet formed in step (2b) opposite to the surface on which the adhesive layer (X1) is laminated.

[0497] As step (1b), for example, the following method can be mentioned: a polymerizable composition (x-1') is applied to the release-treated surface of the release material to form a polymerizable composition layer, the polymerizable composition layer is irradiated with a first energy ray to prepolymerize the energy ray-polymerizable component in the polymerizable composition layer, and then a substrate (Y) is attached to the prepolymerized polymerizable composition layer.

[0498] It should be noted that the polymerizable composition (x-1') is preferably a solvent-free polymerizable composition as described above. When the polymerizable composition (x-1') is a solvent-free polymerizable composition, the heat drying step of the solvent does not need to be performed in this step, and the expansion of the thermally expandable particles can be suppressed.

[0499] Step (2b) is a step of irradiating the polymerizable composition layer formed in step (1b) with energy rays to form a polymer of the energy-ray polymerizable component, thereby forming a pressure-sensitive adhesive layer (X1) containing the polymer and thermally expandable particles.

[0500] Here, when the first energy ray irradiation is performed in step (1b), the energy ray irradiation in step (2b) becomes the second energy ray irradiation performed on the prepolymerized polymerizable composition layer.

[0501] The energy ray irradiation in step (2b) is different from the first energy ray irradiation and is preferably performed until polymerization of the energy ray-polymerizable component substantially stops even after further energy ray irradiation. The energy ray irradiation in step (2b) allows polymerization of the energy ray-polymerizable component to proceed, thereby forming a polymer of the energy ray-polymerizable component constituting the adhesive layer (X1).

[0502] As step (3b), there can be mentioned a method of applying the adhesive composition (x-2) on one side of the release material to form an adhesive layer (X2), and attaching the adhesive layer (X2) to the other side of the substrate (Y).

[0503] From the viewpoint of suppressing the expansion of the heat-expandable particles, it is preferred that none of the above steps include a step of heating the polymerizable composition.

[0504] It should be noted that the "heating" here refers to heating performed intentionally, for example, during drying or lamination, and does not include temperature increases caused by heat imparted to the polymerizable composition by energy ray irradiation or polymerization heat generated by polymerization of the energy ray polymerizable composition.

[0505] <Peeling Material>

[0506] As a release material optionally included in the pressure-sensitive adhesive sheet of one embodiment of the present invention, a double-sided release sheet, a single-sided release sheet, or the like can be used. Examples of the release material include a release material having a base material coated with a release agent.

[0507] Examples of the base material for the release material include plastic films and paper. Examples of plastic films include polyester resin films such as polyethylene terephthalate resin, polybutylene terephthalate resin, and polyethylene naphthalate resin; and olefin resin films such as polypropylene resin and polyethylene resin. Examples of paper include high-quality paper, glassine paper, and kraft paper.

[0508] Examples of release agents include rubber elastomers such as silicone resins, olefin resins, isoprene resins, and butadiene resins; long-chain alkyl resins, alkyd resins, and fluorine resins. These release agents may be used alone or in combination.

[0509] The thickness of the release material is preferably 10 to 200 μm, more preferably 20 to 150 μm, and even more preferably 35 to 80 μm.

[0510] [Applications and usage of adhesive sheets]

[0511] The adhesive sheet of one embodiment of the present invention can easily release a temporarily fixed adherend by heating, and is therefore suitable for a variety of applications. Specifically, it is suitable for use as a dicing sheet used when dicing adherends such as semiconductor wafers; a back grinding sheet used in grinding adherends; a sheet expansion tape used to increase the distance between adherends such as semiconductor chips separated by dicing; a transfer tape used to reverse the front and back sides of adherends such as semiconductor chips; and a temporary fixing sheet used to temporarily secure and inspect an object.

[0512] The adherend of the pressure-sensitive adhesive sheet according to one embodiment of the present invention is not particularly limited, and examples thereof include semiconductor chips, semiconductor wafers, compound semiconductors, semiconductor packages, electronic components, sapphire substrates, displays, and panel substrates.

[0513] In the pressure-sensitive adhesive sheet of one embodiment of the present invention, when the expansion starting temperature (t) of the heat-expandable particles is set to less than 125°C, thermal peeling at low temperatures is possible, making the sheet suitable for temporarily fixing adherends that are susceptible to thermal changes, such as semiconductor chips with DAF.

[0514] Furthermore, in one embodiment of the adhesive sheet of the present invention, when the expansion starting temperature (t) of the heat-expandable particles is set to 50°C or higher, unexpected expansion of the heat-expandable particles caused by a temperature rise during, for example, grinding of an adherend can be suppressed. Therefore, the adhesive sheet is suitable for use as a back grinding sheet used in a grinding process of an adherend.

[0515] The heating temperature for thermally peeling the PSA sheet of one embodiment of the present invention from an adherend is equal to or higher than the expansion starting temperature (t) of the heat-expandable particles, preferably a temperature higher than the expansion starting temperature (t), more preferably equal to or higher than the expansion starting temperature (t) + 2°C, even more preferably equal to or higher than the expansion starting temperature (t) + 4°C, and even more preferably equal to or higher than the expansion starting temperature (t) + 5°C. Furthermore, from the perspectives of energy conservation and suppressing thermal changes in the adherend during thermal peeling, the temperature is preferably equal to or lower than the expansion starting temperature (t) + 50°C, more preferably equal to or lower than the expansion starting temperature (t) + 40°C, and even more preferably equal to or lower than the expansion starting temperature (t) + 20°C.

[0516] In addition, from the viewpoint of suppressing thermal changes in the adherend, the heating temperature during heat peeling is within a range above the expansion starting temperature (t), preferably below 125°C, more preferably below 120°C, further preferably below 115°C, further preferably below 110°C, and further preferably below 105°C.

[0517] The heating method is not particularly limited as long as it can heat the heat to a temperature above the temperature at which the heat-expandable particles expand. Suitable examples include electric heaters; induction heating; magnetic heating; and heating using electromagnetic waves such as near-infrared, mid-infrared, and far-infrared rays. The heating method may include any of contact heating methods such as heated rollers and heated presses, and non-contact heating methods such as atmosphere heating devices and infrared irradiation.

[0518] [Method for Manufacturing Semiconductor Device]

[0519] The present invention also provides a method for manufacturing a semiconductor device using the adhesive sheet according to one embodiment of the present invention.

[0520] One embodiment of the method for manufacturing a semiconductor device of the present invention includes a method in which the adhesive sheet of one embodiment of the present invention is used as a temporary fixing sheet for at least either processing or inspection of an adherend (hereinafter also referred to as "the first embodiment of the method for manufacturing a semiconductor device").

[0521] It should be noted that, in this specification, the term "semiconductor device" refers to any device capable of functioning by utilizing semiconductor characteristics. Examples include wafers equipped with integrated circuits, thinned wafers equipped with integrated circuits, chips equipped with integrated circuits, thinned chips equipped with integrated circuits, electronic components including these chips, and electronic devices equipped with these electronic components.

[0522] <Method for Manufacturing Semiconductor Device According to First Aspect>

[0523] As a more specific method of manufacturing a semiconductor device of the first embodiment, there can be cited a method of manufacturing a semiconductor device including the following steps: adhering a processing and inspection object to an adhesive sheet of one embodiment of the present invention, and after performing one or more selected from processing and inspection on the processing and inspection object, heating the above-mentioned adhesive sheet to above the above-mentioned expansion starting temperature (t).

[0524] Examples of the object to be processed and inspected include semiconductor chips, semiconductor wafers, compound semiconductors, semiconductor packages, electronic components, LED elements, sapphire substrates, displays, and panel substrates.

[0525] The processing performed on the inspection object is not particularly limited, and examples thereof include grinding processing and singulation processing.

[0526] The inspection of the object to be inspected is not particularly limited, and examples thereof include optical microscopy, defect inspection using a laser (eg, dust inspection, surface scratch inspection, wiring pattern inspection, etc.), and visual surface inspection.

[0527] In the semiconductor device manufacturing method of the first embodiment, the adhesive layer of the adhesive sheet to which the object to be inspected is attached may be the adhesive layer (X1), or may be the adhesive layer (X2) if the adhesive sheet is a double-sided adhesive sheet.

[0528] In the case where the adhesive sheet is a double-sided adhesive sheet, it is preferred that the object to be inspected is adhered to the adhesive layer on one side and the support is adhered to the adhesive layer on the other side. By fixing the object to be inspected to the support via the adhesive sheet, vibration, dislocation, breakage of the fragile object to be inspected can be suppressed during processing, thereby improving processing accuracy and processing speed. Furthermore, the adhesive sheet of one embodiment of the present invention has excellent adhesiveness, and therefore, can more effectively suppress vibration, dislocation, breakage of the object to be inspected caused by air entrapment at the bonding interface between the adhesive sheet and the adherend. At this time, the support can be adhered to the adhesive layer (X1) and the object to be inspected is adhered to the adhesive layer (X2), or the object to be inspected is adhered to the adhesive layer (X1) and the support is adhered to the adhesive layer (X2).

[0529] In the case where the support is attached to the adhesive layer (X1) and the object to be inspected is attached to the adhesive layer (X2), by attaching the support to the adhesive layer (X1) having excellent releasability after heat treatment, even if the support is made of a hard material, thermal peeling can be performed without causing the adhesive sheet and the support to bend. In addition, the composition of the adhesive layer (X2) can be appropriately selected according to the type of the object to be inspected. For example, when the adhesive layer (X2) is an adhesive layer whose adhesive strength is reduced by irradiation with energy rays, peeling can be performed without contaminating the object to be inspected due to residues from thermally expandable particles.

[0530] On the other hand, in the case where the object to be inspected is adhered to the adhesive layer (X1) and the support is adhered to the adhesive layer (X2), by adhering the object to be inspected to the adhesive layer (X1) having excellent releasability after heat treatment, the object to be inspected can be easily peeled off from the adhesive sheet after processing, thereby reducing damage to the object to be inspected.

[0531] <Method for Manufacturing Semiconductor Device According to Second Aspect>

[0532] The second method for manufacturing a semiconductor device can be listed as follows: a manufacturing method (hereinafter also referred to as "manufacturing method A") using an adhesive sheet having a stacked structure in which an adhesive layer (X1), a base material layer (Y) and an adhesive layer (X2) are arranged in sequence as an adhesive sheet of one mode of the present invention, and including the following steps 1A, 2A, a first separation step, and a second separation step.

[0533] Step 1A: a step of attaching an object to the adhesive layer (X2) of the adhesive sheet and attaching a support to the adhesive layer (X1) of the adhesive sheet

[0534] Step 2A: A step of performing one or more treatments selected from grinding and singulation on the object to be processed.

[0535] First separation step: a step of heating the adhesive sheet to a temperature higher than the expansion starting temperature (t) of the heat-expandable particles to separate the adhesive layer (X1) from the support

[0536] Second separation step: a step of separating the adhesive layer (X2) from the object to be processed

[0537] The following describes manufacturing method A with reference to the accompanying drawings. It should be noted that while the following description primarily uses a semiconductor wafer as the object to be processed, the same description applies to other objects to be processed. Examples of other objects to be processed include those listed above as the objects to be processed and inspected.

[0538] (Process 1A)

[0539] Step 1A is a step of attaching an object to the adhesive layer (X2) of the adhesive sheet and attaching a support to the adhesive layer (X1).

[0540] Figure 3 (a) and (b) show the process of attaching the semiconductor wafer W to the adhesive layer (X2) of the adhesive sheet 2a and the surface (S) of the support 3. s ) is attached to the surface (S) of the adhesive layer (X1) x1 ) process is explained in a cross-sectional view.

[0541] The semiconductor wafer W is attached so that the surface W1 serving as the circuit surface faces the adhesive layer ( X2 ).

[0542] The semiconductor wafer W may be a silicon wafer, or a wafer made of gallium arsenide, silicon carbide, sapphire, lithium tantalate, lithium niobate, gallium nitride, indium phosphide, or a glass wafer.

[0543] The thickness of the semiconductor wafer W before grinding is usually 500 to 1000 μm.

[0544] The circuit on the surface W1 of the semiconductor wafer W can be formed by a conventional method such as etching or lift-off.

[0545] The material of the support 3 may be appropriately selected according to the type of the object to be processed, the content of processing, etc., taking into consideration required properties such as mechanical strength and heat resistance.

[0546] The material of the support body 3 includes, for example: metal materials such as SUS; non-metallic inorganic materials such as glass and silicon wafers; resin materials such as epoxy resin, ABS resin, acrylic resin, engineering plastics, special engineering plastics, polyimide resin, polyamide-imide resin; composite materials such as glass epoxy resin, etc. Among these materials, SUS, glass, and silicon wafers are preferred.

[0547] Examples of the engineering plastics include nylon, polycarbonate (PC), and polyethylene terephthalate (PET).

[0548] Examples of the special engineering plastics include polyphenylene sulfide (PPS), polyethersulfone (PES), and polyetheretherketone (PEEK).

[0549] The support 3 is preferably attached to the entire adhesive surface of the adhesive layer (X1). Therefore, the surface area of the support 3 attached to the adhesive surface of the adhesive layer (X1) is preferably greater than the area of the adhesive surface of the adhesive layer (X1). In addition, the surface of the support 3 attached to the adhesive surface of the adhesive layer (X1) is preferably flat.

[0550] The shape of the support 3 is not particularly limited, but is preferably a plate shape.

[0551] The thickness of the support 3 may be appropriately selected in consideration of required properties, and is preferably 20 μm or more and 50 mm or less, and more preferably 60 μm or more and 20 mm or less.

[0552] The step of attaching the support 3 to the adhesive layer (X1) of the adhesive sheet 2a in step 1A is preferably performed after the surface (S) of the adhesive layer (X1) is attached. X1 ) and the surface (S) of the support 3 to which the adhesive sheet 2a is to be attached s ) keep the surface of the support 3 (S s ) is attached to the surface (S) of the adhesive layer (X1) X1 ) process (hereinafter also referred to as "face pasting process A").

[0553] Since the PSA sheet of one embodiment of the present invention has excellent adhesiveness, even when the surface laminating step A is performed, air entrapment can be suppressed at the bonding interface between the PSA sheet 2 a and the support 3 .

[0554] As the surface laminating step A, for example, the following step can be mentioned: after laminating the object to be processed to the adhesive layer (X2) of the adhesive sheet 2a, the surface (S1) of the adhesive layer (X1) of the adhesive sheet 2a laminating to the object to be processed is laminated. X1 ) and the surface (S) of the support 3 to which the adhesive sheet 2a is to be attached s ) is kept substantially parallel to the surface (Ss) of the support 3 and the surface (S) of the adhesive layer (X1). X1 ) process.

[0555] It should be noted that, in this specification, “substantially parallel” means a state of 0 degrees ± less than 10 degrees relative to a parallel direction, preferably within 0 degrees ± 5 degrees, and more preferably within 0 degrees ± 1 degree.

[0556] The bonding in step 1A may be performed while performing pressing, heating, pressure reduction, etc., as necessary.

[0557] As for the lamination pressure, from the viewpoint of adhesiveness and productivity, it is preferably 0.12 to 1.0 MPa, more preferably 0.15 to 0.7 MPa, and even more preferably 0.17 to 0.5 MPa. When the lamination pressure is 0.12 MPa or more, there is a tendency to obtain better adhesiveness. In addition, when the lamination pressure is 1.0 MPa or less, there is a tendency to obtain better productivity. It should be noted that lamination can be a method of applying pressure on a flat surface or a method of applying linear pressure using a roller. It should be noted that the lamination pressure here refers to the pressure applied to the object to be pasted. For example, when both the pressure of the pressurizing mechanism of the device and the atmospheric pressure are applied to the object to be pasted, the total pressure of the pressure of the pressurizing mechanism of the device and the atmospheric pressure is the lamination pressure.

[0558] From the perspective of adhesiveness and productivity, the heating temperature is preferably 40 to 88°C, more preferably 45 to 80°C, and even more preferably 50 to 70°C. A heating temperature of 40°C or higher tends to provide better adhesiveness. A heating temperature of 88°C or lower tends to provide better productivity.

[0559] From the perspective of adhesiveness and productivity, the pressing or heating time is preferably 5 to 120 seconds, more preferably 10 to 60 seconds, and even more preferably 20 to 40 seconds. A pressing time of 5 seconds or longer tends to yield superior adhesiveness. A pressing time of 120 seconds or less tends to yield superior productivity.

[0560] The atmospheric pressure when decompressing during lamination is preferably 50 hPa or less, more preferably 10 hPa or less, and even more preferably 5 hPa or less from the viewpoint of lamination properties and productivity. The lower limit of the atmospheric pressure is not particularly limited and may be 0 hPa.

[0561] (Process 2A)

[0562] Step 2A is a step of performing one or more processes selected from a grinding process and a singulation process on the object to be processed.

[0563] As one or more treatments selected from grinding treatment and singulation treatment, for example, there can be listed: grinding treatment using a grinder, etc.; singulation treatment based on a blade cutting method, a laser cutting method, or a Stealth Dicing (registered trademark) method; grinding treatment and singulation treatment based on a blade first cutting method or a stealth first cutting method; and the like.

[0564] Among these, preferred are singulation processing based on the Stealth Dicing method, grinding processing and singulation processing based on the blade-first cutting method, and grinding processing and singulation processing based on the stealth-first cutting method. More preferred are grinding processing and singulation processing based on the blade-first cutting method, and grinding processing and singulation processing based on the stealth-first cutting method.

[0565] Stealth Dicing is a method that uses laser irradiation to create a modified region within a semiconductor wafer, and then singulates the semiconductor wafer using this modified region as the starting point for dicing. The modified region formed in the semiconductor wafer is a portion that has become brittle due to multiphoton absorption. During wafer expansion, stress is applied to the semiconductor wafer in a direction parallel to the wafer surface and in the direction of wafer expansion. This causes cracks to extend from this modified region toward the surface and back of the semiconductor wafer, thus singulating the wafer into semiconductor chips. In other words, the modified region is formed along the dicing lines used during dicing.

[0566] The modified region is formed within the semiconductor wafer by irradiating it with a laser beam focused within the semiconductor wafer. The laser beam can be incident on either the front or back surface of the semiconductor wafer. Alternatively, the laser beam can be incident on the surface to which the adhesive sheet is attached. In this case, the laser beam is irradiated onto the semiconductor wafer through the adhesive sheet.

[0567] The blade-first dicing method is also called the DBG method (Dicing Before Grinding). The blade-first dicing method is a method in which a groove is formed in advance on the semiconductor wafer with a depth shallower than its thickness along the predetermined dividing line, and then the semiconductor wafer is back-ground so that the grinding surface reaches at least the groove to thin it and singulate it at the same time. The groove reached by the grinding surface becomes a cut that passes through the semiconductor wafer, and the semiconductor wafer is divided by the cut and singulated into semiconductor chips. The pre-formed groove is usually provided on the surface (circuit surface) of the semiconductor wafer and can be formed by, for example, cutting using a conventionally known wafer cutting device equipped with a dicing blade.

[0568] The stealth dicing method is also known as the SDBG method (Stealth Dicing Before Grinding). Like the Stealth Dicing method, the Stealth Dicing method is a method of singulating the semiconductor wafer by forming a modified region inside the semiconductor wafer by irradiating it with a laser and using the modified region as the starting point for division. However, it differs from the Stealth Dicing method in that the semiconductor wafer is singulated into semiconductor chips while being thinned by grinding. Specifically, the semiconductor wafer having the modified region is thinned by back grinding, and the pressure applied to the semiconductor wafer at this time is used to cause cracks to extend from the modified region as the starting point toward the adhesive layer attached to the semiconductor wafer, thereby singulating the semiconductor wafer into semiconductor chips.

[0569] It should be noted that the grinding thickness after forming the modified region may be the thickness reaching the modified region, but even if it does not exactly reach the modified region, it can be cut by grinding to a position near the modified region using processing pressure such as a grinding stone.

[0570] When the semiconductor wafer W is singulated by the blade-first dicing method, it is preferable to form grooves in advance on the surface W1 of the semiconductor wafer W to be bonded to the adhesive layer ( X2 ) in step 1A.

[0571] On the other hand, when the semiconductor chip W is singulated using the stealth pre-cutting method, the semiconductor chip W to be attached to the adhesive layer (X2) in process 1A can be irradiated with laser to form a modified area in advance, or the semiconductor chip W already attached to the adhesive layer (X2) can be irradiated with laser to form a modified area.

[0572] Figure 4 A cross-sectional view illustrating a step of forming a plurality of reformed regions 5 using a laser irradiation device 4 on a semiconductor wafer W bonded to an adhesive layer ( X2 ) is shown.

[0573] The semiconductor wafer W is irradiated with laser light from the back surface W2 side, thereby forming a plurality of reformed regions 5 inside the semiconductor wafer W at substantially equal intervals.

[0574] Figure 5 (a) and (b) are cross-sectional views illustrating a process of thinning a semiconductor wafer W and singulating it into a plurality of semiconductor chips CP.

[0575] like Figure 5 As shown in (a), the back surface W2 of the semiconductor wafer W having the reformed region 5 formed thereon is ground by a grinder 6. At this time, the pressure applied to the semiconductor wafer W causes the cutting to occur starting from the reformed region 5. Figure 5 As shown in (b), a plurality of semiconductor chips CP can be obtained by thinning and singulating the semiconductor wafer W.

[0576] The back surface W2 of the semiconductor wafer W having the reformed region 5 formed thereon is ground, for example, with the support 3 supporting the semiconductor wafer W fixed to a fixing table such as a chuck table.

[0577] The thickness of the ground semiconductor chip CP is preferably 5 to 100 μm, more preferably 10 to 45 μm. In addition, when the grinding and singulation are performed by stealth dicing, it is easy to reduce the thickness of the ground semiconductor chip CP to 50 μm or less, more preferably 10 to 45 μm.

[0578] The size of the semiconductor chip CP after grinding in a plan view is preferably less than 600 mm. 2 , more preferably less than 400mm 2 , further preferably less than 300mm 2 It should be noted that the top view refers to observation along the thickness direction.

[0579] The shape of the semiconductor chip CP after singulation in a plan view may be a square or an elongated shape such as a rectangle.

[0580] (Process 3A)

[0581] The production method A preferably further includes the following step 3A.

[0582] Step 3A: A step of attaching a thermosetting film to the surface of the object to be processed that has been subjected to the above treatment, which is opposite to the adhesive layer (X2)

[0583] In addition, in the manufacturing method A, step 3A is an optional step, and a form not including step 3A is also possible.

[0584] When performing step 3A, the expansion starting temperature (t) of the heat-expandable particles contained in the adhesive sheet used in production method A is preferably 50° C. or higher and lower than 125° C. This can prevent the thermosetting film from unexpectedly curing during the first separation step described below.

[0585] Figure 6 The cross-sectional view for explaining the step of attaching the thermosetting film 7 including the support sheet 8 to the surface opposite to the adhesive layer ( X2 ) of the plurality of semiconductor chips CP obtained by the above-mentioned process.

[0586] Thermosetting film 7 is a thermosetting film obtained by forming a resin composition containing at least a thermosetting resin into a film, and is used as an adhesive when mounting the semiconductor chip CP on a substrate. Thermosetting film 7 may also contain a curing agent for the thermosetting resin, a thermoplastic resin, an inorganic filler, a curing accelerator, etc. as needed.

[0587] As the thermosetting film 7 , a thermosetting film generally used as, for example, a die bonding film, a die attach film, or the like can be used.

[0588] The thickness of the thermosetting film 7 is not particularly limited, but is usually 1 to 200 μm, preferably 3 to 100 μm, and more preferably 5 to 50 μm.

[0589] The support sheet 8 may be made of any material as long as it supports the thermosetting film 7 , and examples thereof include resins, metals, and paper materials listed as the non-thermally expandable base material layer ( Y2 ) included in the pressure-sensitive adhesive sheet of one embodiment of the present invention.

[0590] As a method of attaching the thermosetting film 7 to the plurality of semiconductor chips CP, for example, a method based on lamination can be cited.

[0591] Lamination can be performed with or without heating. When lamination is performed with heating, from the perspective of suppressing the expansion of the heat-expandable particles and suppressing thermal changes in the adherend, the heating temperature is preferably "a temperature lower than the expansion starting temperature (t)", more preferably "the expansion starting temperature (t) - 5°C" or lower, further preferably "the expansion starting temperature (t) - 10°C" or lower, and even more preferably "the expansion starting temperature (t) - 15°C" or lower.

[0592] (First Separation Step)

[0593] The first separation step is a step of heating the pressure-sensitive adhesive sheet to a temperature not lower than the expansion starting temperature (t) of the heat-expandable particles to separate the pressure-sensitive adhesive layer (X1) from the support.

[0594] Figure 7 A cross-sectional view illustrating the step of heating the pressure-sensitive adhesive sheet 2a to separate the pressure-sensitive adhesive layer (X1) from the support 3 is shown.

[0595] The heating temperature in the first separation step is equal to or higher than the expansion starting temperature (t) of the heat-expandable particles, preferably a temperature higher than the expansion starting temperature (t), more preferably equal to or higher than the expansion starting temperature (t) + 2°C, even more preferably equal to or higher than the expansion starting temperature (t) + 4°C, and even more preferably equal to or higher than the expansion starting temperature (t) + 5°C. Furthermore, from the perspectives of energy conservation and suppression of thermal changes in the adherend during heat peeling, the heating temperature in the first separation step is preferably equal to or lower than the expansion starting temperature (t) + 50°C, more preferably equal to or lower than the expansion starting temperature (t) + 40°C, and even more preferably equal to or lower than the expansion starting temperature (t) + 20°C, within a range of 125°C or lower.

[0596] From the perspective of suppressing thermal changes in the adherend, the heating temperature in the first separation step is preferably below 125°C, more preferably below 120°C, even more preferably below 115°C, even more preferably below 110°C, and even more preferably below 105°C, within a range not lower than the expansion starting temperature (t). In particular, when the heating temperature in the first separation step is below 125°C, unintended curing of the thermosetting film can be suppressed during the aforementioned step 3A.

[0597] (Second Separation Step)

[0598] The second separation step is a step of separating the adhesive layer (X2) and the object to be processed.

[0599] Figure 8 A cross-sectional view illustrating a step of separating the adhesive layer ( X2 ) and the plurality of semiconductor chips CP is shown.

[0600] The method for separating the adhesive layer (X2) and the plurality of semiconductor chips CP can be appropriately selected depending on the type of the adhesive layer (X2). For example, if the adhesive layer (X2) is an adhesive layer whose adhesive strength is reduced by irradiation with energy rays, separation can be performed after irradiating the adhesive layer (X2) with energy rays to reduce the adhesive strength.

[0601] Through the above steps, a plurality of semiconductor chips CP bonded to the thermosetting film 7 can be obtained.

[0602] Next, the thermosetting film 7 with the plurality of semiconductor chips CP bonded thereto is preferably divided into the same shape as the semiconductor chips CP to obtain semiconductor chips CP with thermosetting film 7. Thermosetting film 7 can be divided by, for example, laser cutting, sheet expansion, or fusing.

[0603] Figure 9 The semiconductor chip CP with the thermosetting film 7 is shown divided into the same shape as the semiconductor chip CP.

[0604] The semiconductor chip CP with the thermosetting film 7 is further subjected to a chip expansion step for increasing the intervals between the semiconductor chips CP, a rearrangement step for arranging the plurality of semiconductor chips CP after the intervals have been increased, and a flipping step for flipping the front and back surfaces of the plurality of semiconductor chips CP, as appropriate as needed. The chip is then attached (die-attached) to the substrate from the side of the thermosetting film 7. The thermosetting film is then thermally cured, thereby bonding the semiconductor chip and the substrate.

[0605] The second method for manufacturing a semiconductor device may be as follows: using an adhesive sheet having a stacked structure in which an adhesive layer (X1), a substrate layer (Y) and an adhesive layer (X2) are arranged in sequence as an adhesive sheet of one embodiment of the present invention, and a manufacturing method (hereinafter also referred to as "manufacturing method B") including the following steps 1B to 2B, the following first separation step and the following second separation step.

[0606] Step 1B: a step of attaching an object to the adhesive layer (X1) of the adhesive sheet and attaching a support to the adhesive layer (X2) of the adhesive sheet

[0607] Step 2B: A step of performing one or more treatments selected from grinding and singulation on the object to be processed.

[0608] First separation step: a step of heating the adhesive sheet to a temperature higher than the expansion starting temperature (t) of the heat-expandable particles to separate the adhesive layer (X1) from the object to be processed

[0609] Second separation step: a step of separating the adhesive layer (X2) from the support

[0610] The production method B preferably further includes the following step 3B.

[0611] Step 3B: A step of attaching a thermosetting film to the surface of the object subjected to the above treatment, which is opposite to the adhesive layer (X1)

[0612] In addition, in the manufacturing method B, step 3B is an optional step, and a form not including step 3B is also possible.

[0613] When performing step 3B, the expansion starting temperature (t) of the heat-expandable particles contained in the adhesive sheet used in manufacturing method B is preferably 50° C. or higher and lower than 125° C. This can prevent the thermosetting film from unexpectedly curing during the first separation step described below.

[0614] The step of attaching the object to be processed to the adhesive layer (X1) of the adhesive sheet 2a in step 1B is preferably performed by attaching the surface (S) of the adhesive layer (X1) to the adhesive layer 2a.X1 ) and the surface (S w ) keep the surface of the object to be processed (S w ) is attached to the surface (S) of the adhesive layer (X1) X1 ) process (hereinafter also referred to as "face pasting process B").

[0615] As the surface laminating step B, for example, the following step can be mentioned: after laminating the support 3 to the adhesive layer (X2) of the adhesive sheet 2a, the surface (S1) of the adhesive layer (X1) of the adhesive sheet 2a laminating to the support 3 is laminated. X1 ) and the surface (S w ) keep the surface of the object to be processed (S w ) is attached to the surface (S) of the adhesive layer (X1) X1 ) process.

[0616] Since the pressure-sensitive adhesive sheet of one embodiment of the present invention has excellent adhesiveness, even when the surface laminating step B is performed, air entrapment can be suppressed at the bonding interface between the pressure-sensitive adhesive sheet 2 a and the object to be processed.

[0617] The lamination in step 1B may be carried out while applying pressure, heating, reducing pressure, etc. as necessary, and the preferred conditions are the same as those described in step 1A above.

[0618] Steps 1B to 3B can be described by replacing the adhesive layer (X1) with the adhesive layer (X2) and replacing the adhesive layer (X2) with the adhesive layer (X1) in the description of steps 1A to 3A.

[0619] The first separation step is a step of heating the adhesive sheet to a temperature not lower than the expansion starting temperature (t) to separate the adhesive layer (X1) from the object.

[0620] The heating conditions such as the heating temperature of the adhesive sheet in the first separation step are the same as those described in the manufacturing method A. In particular, when step 3B is performed, the first separation step is preferably a step of heating the adhesive sheet to a temperature not lower than the expansion starting temperature (t) and lower than 125° C. to separate the adhesive layer (X1) from the object to be processed.

[0621] In the first separation step, a plurality of semiconductor chips bonded to the thermosetting film can be obtained. Thereafter, similarly to the case of the above-mentioned manufacturing method A, the thermosetting film can be divided to obtain semiconductor chips with thermosetting films.

[0622] The second separation step is a step of separating the adhesive layer (X2) and the support.

[0623] The method for separating the adhesive layer (X2) and the support may be appropriately selected depending on the type of the adhesive layer (X2). For example, if the adhesive layer (X2) has adhesive strength that is reduced by irradiation with energy rays, the adhesive layer (X2) may be irradiated with energy rays to reduce the adhesive strength before separation.

[0624] It should be noted that the production method B may also include a second separation step.

[0625] <Other Methods of Manufacturing Semiconductor Devices>

[0626] The method for manufacturing a semiconductor device of the present invention is not limited to the methods for manufacturing a semiconductor device of the first and second aspects described above, and may be a method for manufacturing a semiconductor device of another aspect different from the first and second aspects.

[0627] As another example of a method for manufacturing a semiconductor device of another embodiment, there is a method of separating an object to be processed, which has been adhered to another sheet, from the other sheet using the adhesive sheet of one embodiment of the present invention.

[0628] For example, multiple semiconductor chips, spaced apart on a wafer tape, are attached to the adhesive surface of the wafer tape. However, picking up these chips one by one is very cumbersome. However, a method for manufacturing a semiconductor device according to one embodiment of the present invention allows multiple semiconductor chips to be separated from the wafer tape at once by attaching an adhesive layer (X1) of an adhesive sheet according to one embodiment of the present invention to the exposed surfaces of the multiple semiconductor chips attached to the wafer tape and then peeling the wafer tape from the multiple semiconductor chips.

[0629] After the above steps, a plurality of semiconductor chips bonded to the adhesive sheet of one embodiment of the present invention can be obtained. These semiconductor chips can be easily separated by subsequently heating the adhesive layer (X1) to a temperature not lower than the expansion starting temperature (t) of the heat-expandable particles.

[0630] The plurality of separated semiconductor chips may be transferred to another adhesive sheet, or may be subjected to a rearrangement step of aligning the plurality of semiconductor chips after being temporarily separated.

[0631] Example

[0632] The present invention will be described in detail with reference to the following examples, but the present invention is not limited to the following examples. It should be noted that the physical property values in each example are values measured by the following methods.

[0633] [Weight average molecular weight (Mw)]

[0634] The values were measured using a gel permeation chromatography apparatus (manufactured by Tosoh Corporation, product name "HLC-8020") under the following conditions and converted to standard polystyrene.

[0635] (Measurement conditions)

[0636] ■Chromatographic column: A column made by sequentially connecting "TSK guard column HXL-L", "TSK gel G2500HXL", "TSK gel G2000HXL", and "TSK gel G1000HXL" (all manufactured by Tosoh Corporation)

[0637] Column temperature: 40°C

[0638] ■Developing solvent: tetrahydrofuran

[0639] ■Flow rate 1.0mL / min

[0640] [Thickness of each layer]

[0641] The measurement was performed at 23° C. using a constant pressure thickness gauge manufactured by TECLOCK Co., Ltd. (model: “PG-02J”, standard: in accordance with JIS K6783, Z1702, and Z1709).

[0642] [Average particle size of thermally expandable particles (D 50 ), 90% particle size (D 90 )]

[0643] The particle size distribution of the heat-expandable particles before expansion at 23° C. is measured using a laser diffraction particle size distribution analyzer (for example, manufactured by Malvern, product name “Mastersizer 3000”).

[0644] Furthermore, the particle sizes corresponding to the 50% and 90% cumulative volume frequencies of the particles with the smallest particle size in the particle distribution are respectively defined as the "average particle size of the thermally expandable particles (D 50 )" and "90% particle size of thermally expandable particles (D 90 )”.

[0645] [Method for measuring arithmetic mean waviness (Wa)]

[0646] The arithmetic mean waviness (Wa) was measured based on JIS B0601:2013 using a scanning white light interference microscope (manufactured by Hitachi Hi-Tech Co., Ltd., product name "VS-1550"). The surface (S) of the adhesive layer (X1) was measured under the conditions of the measurement mode PSI and the objective lens 10 times. X1) observations were performed, and a total of 100 images (with a 10% overlap ratio with adjacent images) were acquired in a 10-vertical x 10-horizontal grid format. Each image was then combined with its adjacent image to create a composite image. The height data from the resulting composite image was processed using a Gaussian filter with a cutoff value of 100 μm and a vibration transmissibility of 50%, yielding the arithmetic mean waviness (Wa) value.

[0647] In the following examples, details of materials used to form each layer are as follows.

[0648] <Adhesive Resin>

[0649] ■Acrylic copolymer (A1): A solution comprising an acrylic copolymer having a Mw of 600,000, a diluent of ethyl acetate, and a solid content of 40% by mass, wherein the acrylic copolymer has structural units derived from raw material monomers consisting of n-butyl acrylate (BA) / methyl methacrylate (MMA) / acrylic acid (AA) / 2-hydroxyethyl acrylate (HEA) in a mass ratio of 86 / 8 / 1 / 5.

[0650] <Crosslinking Agent>

[0651] ■Isocyanate crosslinking agent (i): a solution containing trimethylolpropane-modified toluene diisocyanate (product name "Coronate L") manufactured by Tosoh Corporation, solid content concentration: 75% by mass

[0652] <Photopolymerization Initiator>

[0653] ■Photopolymerization initiator (i): 1-hydroxycyclohexyl phenyl ketone

[0654] <Additives>

[0655] ■Phthalocyanine pigments

[0656] <Thermal Expandable Particles>

[0657] ■ Heat-expandable particles: manufactured by Nouryon, product name "Expancel (registered trademark) 031-40" (DU type), expansion starting temperature (t) = 88°C, average particle size (D 50 )=12.6μm, 90% particle size (D 90 )=26.2μm

[0658] <Peeling Material>

[0659] Heavy release film: Lintec Co., Ltd., product name "SP-PET382150," a polyethylene terephthalate (PET) film with a release agent layer formed of a silicone release agent on one side. Thickness: 38 μm

[0660] Examples 1 to 10 and Comparative Examples 1 to 10: Formation of Adhesive Sheets

[0661] (1) Formation of adhesive layer (X1)

[0662] 1.38 parts by mass of an isocyanate crosslinking agent (i) was added to 100 parts by mass of the solid content of the acrylic copolymer (A1) (solid content ratio), diluted with toluene, and stirred uniformly to prepare an adhesive composition (x-1) having a solid content concentration (active ingredient concentration) of 25% by mass.

[0663] Then, the prepared adhesive composition (x-1) was applied to the release surface of the heavy release film to form a coating film, and the coating film was dried at 100° C. for 60 seconds to form an adhesive layer (X1) having a thickness of 5 μm.

[0664] (2) Preparation of solvent-free resin composition (y-1a)

[0665] 2-Hydroxyethyl acrylate was reacted with an isocyanate-terminated urethane prepolymer obtained by reacting an ester diol with isophorone diisocyanate (IPDI) to obtain an oligomer having a weight average molecular weight (Mw) of 5,000, which is a linear urethane prepolymer having ethylenically unsaturated groups at both ends.

[0666] Then, 40 parts by mass (solid content ratio) of isobornyl acrylate (IBXA) and 20 parts by mass (solid content ratio) of phenylhydroxypropyl acrylate (HPPA) as energy-ray polymerizable monomers were added to 40 parts by mass (solid content ratio) of the above-synthesized urethane prepolymer, and 2.0 parts by mass (solid content ratio) of a photopolymerization initiator (i) and 0.2 parts by mass (solid content ratio) of a phthalocyanine pigment and 20 parts by mass of cyclohexyl acrylate (CHA) as additives were further added to the total amount (100 parts by mass) of the urethane prepolymer and the energy-ray polymerizable monomer to prepare an energy-ray curable composition.

[0667] Next, heat-expandable particles were blended into the energy-ray curable composition so that the content of the heat-expandable particles relative to the total mass (100% by mass) of the resulting heat-expandable base layer (Y1) reached the content listed in Table 1. Then, any of the dispersion treatments listed in Table 1 was performed to prepare a solvent-free, solvent-free resin composition (y-1a). The details of the dispersion treatments listed in Table 1 are as follows.

[0668] (Distributed Processing)

[0669] Stirring treatment: The mixture was stirred at 200 rpm for 5 minutes using a cylindrical stirring rod (manufactured by Engineering Test Service Co., Ltd., product name "PE05", 30 mmΦ×300 mm).

[0670] Filtration: Filtration was performed using Tetoron Mesh (#200).

[0671] High-speed stirring treatment: Using a stirring device (manufactured by Primix Co., Ltd., product name "LABOLUTION") equipped with a stirring blade (manufactured by Primix Co., Ltd., product name "Homomixer MARKII"), stirring was performed at 10,000 rpm for 20 minutes while cooling with 10°C water.

[0672] (3) Formation of a substrate laminate comprising a thermally expandable substrate layer (Y1) and a non-thermally expandable substrate layer (Y2)

[0673] As the non-thermally expandable base material layer (Y2), a PET film (manufactured by Toyobo Co., Ltd., product name: "COSMOSHINE A4300", thickness: 50 μm) was prepared.

[0674] Next, a solvent-free resin composition (y-1a) was applied to one surface of the PET film so that the thickness of the formed heat-expandable base material layer (Y1) would be the thickness described in Table 1, thereby forming a coating film.

[0675] Then, an ultraviolet irradiation device (manufactured by Eye Graphics Co., Ltd., product name "ECS-401GX") and a high-pressure mercury lamp (manufactured by Eye Graphics Co., Ltd., product name "H04-L41") were used at an illumination of 160 mW / cm 2 , light intensity 500mJ / cm 2 The coating film was cured by irradiating with ultraviolet rays under the conditions of , to obtain a substrate laminate in which a heat-expandable substrate layer (Y1) having the thickness described in Table 1 was formed on a PET film as a non-heat-expandable substrate layer (Y2). It should be noted that the illuminance and light quantity during ultraviolet irradiation are values measured using an illuminance / light quantity meter (manufactured by EIT Corporation, product name "UV Power Puck II").

[0676] (4) Formation of adhesive sheet

[0677] The adhesive surface of the adhesive layer (X1) formed in (1) was bonded to the surface of the heat-expandable substrate layer (Y1) of the substrate laminate formed in (2) to produce an adhesive sheet having the following structure.

[0678] <Heavy release film> / <Adhesive layer (X1), thickness: 5 μm> / <Thermal expandable substrate layer (Y1), thickness: thickness described in Table 1> / <Non-thermal expandable substrate layer (Y2), thickness: 50 μm>

[0679] Figure 10 The surface (S) obtained for calculating the arithmetic mean waviness (Wa) of the adhesive sheet of Example 1 is shown. X1 ), Figure 11 The surface (S) obtained for calculating the arithmetic mean waviness (Wa) of the adhesive sheet of Comparative Example 9 is shown. X1 )’s three-dimensional surface shape image. Figure 10 and Figure 11 The scale in the x-axis direction is about 16 mm, the scale in the y-axis direction is about 12 mm, and the scale in the z-axis direction is about Figure 10 and Figure 11 are the same.

[0680] according to Figure 10 and Figure 11 It can be seen that compared with Example 1 ( Figure 10 ) of the adhesive sheet (S X1 ), the arithmetic mean waviness (Wa) of Comparative Example 9 is large ( Figure 11 ) of the adhesive sheet (S X1 ) have greater fluctuations.

[0681] [Storage modulus E'(23) of the non-heat-expandable substrate layer (Y2) at 23°C]

[0682] The non-heat-expandable base material layer (Y2) cut into a size of 30 mm in length and 5 mm in width was used as a test sample. The storage modulus E' at 23°C was measured using a dynamic viscoelasticity measuring apparatus (manufactured by TA INSTRUMENTS, product name "DMAQ800") under the conditions of a test start temperature of 0°C, a test end temperature of 200°C, a heating rate of 3°C / min, a frequency of 1 Hz, and an amplitude of 20 μm. As a result, the storage modulus E'(23) of the PET film serving as the non-heat-expandable base material layer (Y2) at 23°C was 2.27×10 9 Pa.

[0683] [Evaluation of adhesiveness]

[0684] The adhesive sheet obtained in each example was cut into a diameter of 300 mm, and the heavy release film was removed so that the surface (S x1 ) is placed on a flat surface with the surface facing upward. A silicon mirror wafer with a diameter of 300 mm is placed on it so that the mirror surface is aligned with the surface (S x1) contact side, on the side (S x1 ) was placed substantially parallel to the mirror surface. A vacuum laminator (Nikko Materials Co., Ltd., product name "V-130") was used to reduce the atmospheric pressure to below 2 hPa. Pressing was performed for 30 seconds at a lamination temperature of 60°C and a pressure setting of 0.2 MPa on the pressurizing mechanism of the device to produce a test sample. It should be noted that in the vacuum laminator, the total pressure of 0.3 MPa, a combination of the 0.2 MPa pressure applied by the pressurizing mechanism and the atmospheric pressure of 0.1 MPa, constituted the lamination pressure.

[0685] The test samples obtained in each example were visually observed from the non-heat-expandable base material layer (Y2) side. The case where no air entrapment was observed at the bonding interface between the adhesive layer (X1) and the silicon mirror wafer was evaluated as "A," and the case where air entrapment was observed was evaluated as "F." It should be noted that since translucent materials were used as the heat-expandable base material layer (Y1) and the non-heat-expandable base material layer (Y2), the state of the bonding interface between the silicon mirror wafer and the adhesive layer (X1) could be visually observed from the non-heat-expandable base material layer (Y2) side.

[0686] The evaluation results of each example are shown in Table 1. In addition, an example of a photograph of the appearance of a test sample corresponding to the evaluation "A" is shown in Table 1. Figure 12 (a) and (b) show an example of the appearance photograph of the test sample corresponding to the evaluation "F". Figure 13 (a) and (b).

[0687] exist Figure 12 and 13 In the figure (b), the area enclosed by the black dotted line in the figure (a) is enlarged. Figure 12 No air entrapment was confirmed in Figure 13 There are multiple islands of air stagnation (relatively brighter areas).

[0688] [Table 1]

[0689]

[0690] ※“-” in the table means that the treatment was not implemented

[0691] As shown in Table 1, the surface (S X1 ) is 0.090 μm or less, indicating excellent adhesiveness. In contrast, the surface (S X1) exceeded 0.090 μm, indicating poor adhesion.

Claims

1. A pressure-sensitive adhesive sheet having a laminate structure comprising a pressure-sensitive adhesive layer (X1) and a substrate layer (Y), At least one of the adhesive layer (X1) and the base layer (Y) is a heat-expandable layer containing heat-expandable particles. The surface (S) of the adhesive layer (X1) X1 ) has an arithmetic mean waviness (Wa) of 0.090 μm or less, and the surface (S X1 ) is a surface on the opposite side to the surface facing the base material layer (Y), The arithmetic mean waviness (Wa) is measured based on JIS B0601:2013 under the conditions of a cutoff value of 100 μm and a vibration transmissibility of 50%.

2. The adhesive sheet according to claim 1, wherein The thickness of the heat-expandable layer before heat expansion is 30 to 300 μm.

3. The adhesive sheet according to claim 1 or 2, wherein The content of the heat-expandable particles in the heat-expandable layer is 1 to 25% by mass relative to the total mass (100% by mass) of the heat-expandable layer.

4. The adhesive sheet according to claim 1 or 2, wherein The expansion starting temperature (t) of the heat-expandable particles is 50°C or higher and lower than 125°C.

5. The adhesive sheet according to claim 1 or 2, wherein The substrate layer (Y) is a substrate laminate formed by laminating a heat-expandable substrate layer (Y1) containing heat-expandable particles and a non-heat-expandable substrate layer (Y2), and the adhesive sheet has a laminated structure in which the adhesive layer (X1), the heat-expandable substrate layer (Y1) and the non-heat-expandable substrate layer (Y2) are arranged in this order. The adhesive sheet according to claim 1 or 2, further comprising an adhesive layer (X2), wherein the adhesive sheet has a laminated structure in which the adhesive layer (X1), the base layer (Y), and the adhesive layer (X2) are arranged in this order.

7. The adhesive sheet according to claim 6, wherein The adhesive layer (X2) is an energy-ray-curable adhesive layer that is cured by irradiation with energy rays and has reduced adhesive strength.

8. A method for manufacturing a semiconductor device, using the adhesive sheet according to claim 6 or 7, comprising the following steps 1A, 2A, a first separation step, and a second separation step. Step 1A: a step of attaching an object to the adhesive layer (X2) of the adhesive sheet and attaching a support to the adhesive layer (X1) of the adhesive sheet; Step 2A: performing one or more treatments selected from grinding and singulation on the object to be processed; A first separation step: heating the adhesive sheet to a temperature not lower than the expansion starting temperature (t) of the heat-expandable particles to separate the adhesive layer (X1) from the support; Second separation step: a step of separating the adhesive layer (X2) from the object to be processed.

9. The method for manufacturing a semiconductor device according to claim 8, wherein: The expansion starting temperature (t) of the heat-expandable particles is 50° C. or higher and lower than 125° C., After the step 2A, the method further includes a step 3A of attaching a thermosetting film to the surface of the object subjected to the treatment, which is opposite to the adhesive layer (X2), The first separation step is a step of heating the adhesive sheet to a temperature not lower than the expansion starting temperature (t) and lower than 125° C. to separate the adhesive layer ( X1 ) from the support.

10. The method for manufacturing a semiconductor device according to claim 8 or 9, wherein: The step of attaching the support to the adhesive layer (X1) of the adhesive sheet in step 1A is to make the surface (S X1 ) and the surface (S) of the support to which the adhesive sheet is to be attached s ) keep the surface of the support body (S s ) is attached to the surface (S) of the adhesive layer (X1) X1 ) process.

11. A method for manufacturing a semiconductor device, using the adhesive sheet according to claim 6 or 7, comprising the following steps 1B, 2B, a first separation step, and a second separation step. Step 1B: a step of attaching an object to the adhesive layer (X1) of the adhesive sheet and attaching a support to the adhesive layer (X2) of the adhesive sheet; Step 2B: performing one or more treatments selected from grinding and singulation on the object to be processed; A first separation step: heating the adhesive sheet to a temperature not lower than the expansion starting temperature (t) of the heat-expandable particles to separate the adhesive layer (X1) from the object to be processed; Second separation step: a step of separating the adhesive layer (X2) from the support.

12. The method for manufacturing a semiconductor device according to claim 11, wherein: The expansion starting temperature (t) of the heat-expandable particles is 50° C. or higher and lower than 125° C., After the step 2B, the method further includes a step 3B of attaching a thermosetting film to the surface of the object subjected to the treatment, which is opposite to the adhesive layer (X1), The first separation step is a step of heating the adhesive sheet to a temperature not lower than the expansion starting temperature (t) and lower than 125° C. to separate the adhesive layer ( X1 ) from the object to be processed.

13. The method for manufacturing a semiconductor device according to claim 11 or 12, wherein: The step of attaching the object to be processed to the adhesive layer (X1) of the adhesive sheet in the step 1B is to make the surface (S X1 ) and the surface (S) of the object to be processed to which the adhesive sheet is to be attached w ) is kept substantially parallel to the surface of the object to be processed (S w ) is attached to the surface (S) of the adhesive layer (X1) X1 ) process.

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