Adhesive sheet for temporarily fixing electronic components and method for treating electronic components

Abstract

To provide a pressure sensitive adhesive sheet used for temporarily fixing an electronic component to a support, in which a laser beam irradiation causes detachability from the support, and can reduce a residue on the support after detachment.SOLUTION: A pressure sensitive adhesive sheet for temporarily fixing an electronic component of the invention includes a photothermal conversion layer and a thermal decomposition layer directly disposed on the photothermal conversion layer. A temperature of 5% weight loss of the thermal decomposition layer is lower than a temperature of 5% weight loss of the photothermal conversion layer. In an embodiment, the temperature of 5% weight loss of the photothermal conversion layer is 300-600°C.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a pressure-sensitive adhesive sheet for temporarily fixing electronic components and a method for treating electronic components. [Background technology]

[0002] Demand for smaller and thinner electronic components is growing year by year. For example, the trend toward thinner semiconductor wafers, particularly in areas such as power devices, is accelerating in order to improve the characteristics of semiconductor devices. In applications involving the processing and handling of thin and fragile semiconductor substrates (e.g., silicon wafers), a method is widely used in which a liquid adhesive is used to temporarily fix the substrate to a light-transmitting, rigid substrate (support) such as glass to reduce the risk of cracking during the processing and handling process (e.g., Patent Document 1). This temporary fixation method involves multiple film-forming processes to form a photothermal conversion layer and a bonding layer on the light-transmitting substrate. During processing, the workpiece is firmly fixed. During peeling, a laser beam of a specified wavelength is irradiated onto the photothermal conversion layer, which absorbs the light, converts it into heat, and thermally decomposes, thereby easily separating the workpiece from the light-transmitting substrate. However, when the photothermal conversion layer thermally decomposes, the decomposed material burns onto the hard substrate (support), leaving a residue that is difficult to clean. Therefore, hard substrates (supports) are used as disposable substrates, and even if they are recovered and reused, a large amount of cleaning work is required, which is one of the factors that increases the manufacturing costs of semiconductor devices. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 4565804 Summary of the Invention [Problem to be solved by the invention]

[0004] The present invention has been made to solve the above-mentioned problems, and its object is to provide an adhesive sheet used for temporarily fixing electronic components to a support, which exhibits releasability from the support when irradiated with laser light and can reduce residue on the support after removal. [Means for solving the problem]

[0005] The pressure-sensitive adhesive sheet for temporarily fixing electronic components of the present invention comprises a photothermal conversion layer and a thermal decomposition layer disposed directly on the photothermal conversion layer, and the 5% weight loss temperature of the thermal decomposition layer is lower than the 5% weight loss temperature of the photothermal conversion layer. In one embodiment, the photothermal conversion layer has a 5% weight loss temperature of 300°C to 600°C. In one embodiment, the 5% weight loss temperature of the pyrolysis layer is 250°C to 400°C. In one embodiment, the light-to-heat conversion layer has a transmittance of 50% or less for light with a wavelength of 355 nm. In one embodiment, the light-to-heat conversion layer is a resin film made of a polyimide resin. In one embodiment, the thermal decomposition layer has a transmittance of 80% or more for light with a wavelength of 355 nm. In one embodiment, the light-to-heat conversion layer has a transmittance of 50% or less for light with a wavelength of 1032 nm. In one embodiment, the light-to-heat conversion layer is a colored film. In one embodiment, the thermal decomposition layer has a transmittance of 80% or more for light with a wavelength of 1032 nm. In one embodiment, the thermal decomposition layer has a gel fraction of 70% or more. In one embodiment, the photothermal conversion layer has a tensile modulus at 200° C. of 5 MPa to 2 GPa. In one embodiment, the pressure-sensitive adhesive sheet for temporarily fixing electronic components further includes a pressure-sensitive adhesive layer, and the pressure-sensitive adhesive layer, the photothermal conversion layer, and the thermal decomposition layer are laminated in this order. According to another aspect of the present invention, there is provided a method for treating electronic components, which comprises placing an electronic component on the pressure-sensitive adhesive sheet and then subjecting the electronic component to a predetermined treatment. In one embodiment, the treatment is grinding, dicing, die bonding, wire bonding, etching, deposition, molding, rewiring, through-hole formation, or device surface protection. [Effects of the Invention]

[0006] According to the present invention, it is possible to provide an adhesive sheet that is used for temporarily fixing electronic components to a support, which exhibits releasability from the support upon irradiation with laser light and can reduce residue on the support after peeling. [Brief explanation of the drawings]

[0007] [Figure 1] 1 is a schematic cross-sectional view of a pressure-sensitive adhesive sheet according to one embodiment of the present invention. [Figure 2] FIG. 2 is a diagram illustrating a method of using the pressure-sensitive adhesive sheet according to one embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0008] A. Overview of adhesive sheets for temporary fixing of electronic components FIG. 1 is a schematic cross-sectional view of a pressure-sensitive adhesive sheet for temporary fixing of electronic components according to one embodiment of the present invention. The pressure-sensitive adhesive sheet 100 for temporary fixing of electronic components comprises a photothermal conversion layer 10 and a pyrolysis layer 20 disposed directly on the photothermal conversion layer. The photothermal conversion layer absorbs light of a predetermined wavelength and converts the light into heat. Heat generation from the photothermal conversion layer raises the temperature of the pyrolysis layer, resulting in decomposition of the pyrolysis layer. As a result, the pressure-sensitive adhesive sheet for temporary fixing of electronic components (hereinafter also simply referred to as a pressure-sensitive adhesive sheet) exhibits releasability. In one embodiment, heat is generated in the photothermal conversion layer by irradiation with laser light. In this specification, "thermal decomposition" means that heating to 250°C or higher can result in a weight loss of 5% or more. Furthermore, "directly disposed" means that the photothermal conversion layer and the pyrolysis layer are in contact with each other, with no other layer disposed between them. On the other hand, as long as the effects of the present invention are obtained, the pressure-sensitive adhesive sheet may further comprise other layers. 1, any suitable pressure-sensitive adhesive layer 30 may be disposed on the side of the photothermal conversion layer 10 opposite the pyrolysis layer 20. That is, in one embodiment, a pressure-sensitive adhesive sheet 100 may be provided in which the pressure-sensitive adhesive layer 30, the photothermal conversion layer 10, and the pyrolysis layer 20 are laminated in this order.

[0009] In the pressure-sensitive adhesive sheet, the 5% weight loss temperature of the thermal decomposition layer is lower than the 5% weight loss temperature of the photothermal conversion layer. The 5% weight loss temperature refers to the temperature at which the weight of the sample to be evaluated, when heated, decreases by 5% by weight relative to the weight before heating. The 5% weight loss temperature is measured using a differential thermal analyzer under the following conditions: a heating rate of 10°C / min, an air atmosphere, and a flow rate of 25 ml / min.

[0010] In one embodiment, the pressure-sensitive adhesive sheet is used by adhering the thermal decomposition layer as an adhesive layer to a support, and placing an electronic component (e.g., a semiconductor component such as a semiconductor wafer) on the photothermal conversion layer side. In the present invention, by providing a photothermal conversion layer and a thermal decomposition layer, i.e., by providing a layer that absorbs laser light and generates heat (photothermal conversion layer) and a layer that is more easily thermally decomposed than the photothermal conversion layer and contributes to peeling (thermal decomposition layer) as separate layers, it is possible to easily separate the electronic component from the support and prevent residue from being left on the support. More specifically, the pressure-sensitive adhesive sheet of the present invention can behave as shown in Figure 2 and below, and can achieve the effects described above. (1) The adhesive sheet 100 is placed on the support 200 with the pyrolysis layer side facing the support 200, and the electronic component 300, which is the workpiece, is placed on the side of the adhesive sheet 100 opposite the support 200 (Figure 2(a)). (2) When the adhesive sheet 100 placed on the support 200 is irradiated with laser light, the photothermal conversion layer 10 generates heat, and the generated heat propagates to the adjacent pyrolysis layer 20, causing the pyrolysis layer 20 to decompose at the interface with the photothermal conversion layer 10 (FIG. 2(b)). In one embodiment, the decomposition of the pyrolysis layer occurs locally. (3) As a result, the thermal decomposition layer 20 changes shape at the interface with the photothermal conversion layer 10, losing its adhesiveness, and the photothermal conversion layer 10 can be peeled off from the support 200 (FIG. 2(c)). As a result, the electronic component can be separated from the support. (4) Next, the pyrolysis layer 20 on the support 200 is removed, whereby the residue is suppressed and a clean support 200 can be recovered (FIG. 2(d)). In the present invention, by providing a photothermal conversion layer and a pyrolysis layer, the pressure-sensitive adhesive sheet can be peeled off by the above-mentioned operation, and the electronic component can be separated from the support with less damage to the electronic component. Furthermore, by setting the 5% weight loss temperature of the pyrolysis layer lower than the 5% weight loss temperature of the photothermal conversion layer, peeling at the pyrolysis layer / photothermal conversion layer interface is promoted, and the above-mentioned effect becomes more pronounced. Furthermore, in the past, when laser light irradiation for generating heat in the photothermal conversion layer unnecessarily heated the pyrolysis layer, the pyrolysis product of the pyrolysis layer could be burned onto the support, making it difficult to recover a clean support. In the present invention, in step (4) above, the pyrolysis layer is immersed in an organic solvent (e.g., toluene) to remove it, thereby removing most of the pyrolysis layer from the support at once, and the support can be easily recovered. This effect becomes even more pronounced by optimizing the gel fraction of the pyrolysis layer (details will be described later).

[0011] The support may be made of any suitable material. Examples of suitable supports include glass, such as borosilicate glass and quartz glass; sapphire; and acrylic resins, such as PMMA (polymethyl methacrylate) and PC (polycarbonate). In one embodiment, a support without an organic layer on its surface is used. The arithmetic surface roughness Ra of the support is, for example, 0.3 nm to 100 nm, and more preferably 0.4 nm to 50 nm. The arithmetic surface roughness Ra can be measured in accordance with JIS B 0601. Generally, a smaller surface roughness of the support is preferable from the viewpoint of preventing residues. Furthermore, the support is preferably optically transparent in the ultraviolet to infrared range. In particular, the support is preferably optically transparent to laser light of any selected wavelength. The transmittance of the support at the wavelength of laser light is, for example, 50% or more, and more preferably 60% or more. The water contact angle of the support surface is, for example, 0° to 150°, and more preferably 3° to 120°. The support preferably has solvent resistance. The present invention is advantageous in that it enables favorable peeling even when a support that has conventionally been difficult to achieve good peeling (for example, because residues are generated) is used, i.e., it broadens the range of support options.

[0012] The initial adhesive strength at 23°C when the pyrolytic layer is attached to a glass plate is preferably 0.3 N / 20 mm to 20 N / 20 mm, more preferably 0.5 N / 20 mm to 15 N / 20 mm. Within this range, a pressure-sensitive adhesive sheet suitable for temporary fixing applications can be obtained without misalignment on the support. The adhesive strength is measured in accordance with JIS Z 0237:2000. Specifically, the pyrolytic layer is attached to a glass plate (arithmetic mean surface roughness Ra: 10±8 nm) using a 2 kg roller in one stroke, and then the adhesive sheet is peeled off at a peel angle of 180° and a peel rate (pulling rate) of 300 mm / min. The adhesive strength of the pyrolytic layer can change upon irradiation with laser light; however, in this specification, "initial adhesive strength" refers to the adhesive strength before irradiation with laser light.

[0013] The thickness of the pressure-sensitive adhesive sheet is preferably 10 μm to 500 μm, and more preferably 20 μm to 400 μm.

[0014] In one embodiment, the pressure-sensitive adhesive sheet has a transmittance of 0% to 50%, more preferably 0% to 40%, and even more preferably 0% to 35% for light with a wavelength of 355 nm, and in another embodiment, a transmittance of 0% to 50%, more preferably 0% to 40%, and even more preferably 0% to 35% for light with a wavelength of 1032 nm.

[0015] B. Light-to-heat conversion layer The 5% weight loss temperature of the photothermal conversion layer is preferably 300° C. to 600° C., and more preferably 315° C. to 590° C. If the temperature is within this range, the effects of the present invention become significant.

[0016] As described above, the 5% weight loss temperature of the pyrolysis layer is lower than the 5% weight loss temperature of the photothermal conversion layer. The difference between the 5% weight loss temperature of the pyrolysis layer and the 5% weight loss temperature of the photothermal conversion layer is preferably 5°C to 300°C, and more preferably 8°C to 280°C. Within this range, the effects of the present invention become more pronounced.

[0017] The thickness of the light-heat conversion layer is preferably 5 μm to 200 μm, and more preferably 10 μm to 150 μm.

[0018] In one embodiment, the light-to-heat conversion layer has a transmittance of 50% or less, more preferably 40% or less, even more preferably 35% or less, and most preferably 0% for light with a wavelength of 355 nm.Within such a range, a light-to-heat conversion layer that favorably absorbs UV laser light and easily generates heat can be formed.

[0019] In one embodiment, the light-to-heat conversion layer has a transmittance of 50% or less, more preferably 40% or less, even more preferably 35% or less, and most preferably 0% for light with a wavelength of 1032 nm. Within such a range, a light-to-heat conversion layer that favorably absorbs IR laser light and easily generates heat can be formed.

[0020] The tensile modulus of the photothermal conversion layer at 200°C is preferably 5 MPa to 2 GPa, more preferably 10 MPa to 1.8 GPa. Within this range, decomposition gas generated in the pyrolysis layer is prevented from migrating to the opposite side of the photothermal conversion layer. The decomposition gas can be retained near the interface between the photothermal conversion layer and the pyrolysis layer, thereby improving the separation of the electronic component from the support. For example, when a pressure-sensitive adhesive layer is disposed on the opposite side of the photothermal conversion layer from the pyrolysis layer, the decomposition gas is prevented from flowing into the interface between the pressure-sensitive adhesive layer and the electronic component. The electronic component can be separated from the support while being protected by the photothermal conversion layer. The tensile modulus can be measured using a dynamic viscoelasticity measuring device. Specific measurement methods will be described later. Even when the photothermal conversion layer is a multilayer structure, the tensile modulus is measured for the entire photothermal conversion layer. In one embodiment, the tensile modulus of the photothermal conversion layer at 200°C is 1 GPa or more, more preferably 1.4 GPa or more. Within this range, the photothermal conversion layer can also function as a substrate. Examples of light-to-heat conversion layers having such properties include resin films described below, and preferably, resin films made of polyimide resins can be used.

[0021] B-1. Photothermal conversion layer capable of absorbing UV light In one embodiment, a photothermal conversion layer capable of absorbing UV light (hereinafter also referred to as a UV-absorbing photothermal conversion layer) is formed. A pressure-sensitive adhesive sheet having a UV-absorbing photothermal conversion layer can be peeled off using UV laser light. The UV-absorbing photothermal conversion layer has a transmittance of 50% or less, more preferably 40% or less, even more preferably 35% or less, and most preferably 0% for light with a wavelength of 355 nm. In one embodiment, the transmittance of the photothermal conversion layer can be calculated using the formula (total light - absorptance).

[0022] In one embodiment, the UV absorption light-to-heat conversion layer is a resin film. The resin film may be made of any appropriate resin as long as it can absorb UV light. Examples of resins that can be used for the resin film include polyimide resins, polyether ether ketone resins, polyethylene naphthalate resins, acrylic resins, and epoxy resins. Of these, polyimide resins are preferred.

[0023] The resin film may be a colored film that is colored to absorb a predetermined amount of UV light. The colored film may be a film having a colored printed layer, or may be a resin film containing a pigment and / or dye. The printed layer may be formed by a method such as gravure printing or screen printing. The thickness of the printed layer is, for example, preferably more than 0 μm and not more than 15 μm, more preferably 0.3 μm to 10 μm, and even more preferably 0.5 μm to 8 μm. Furthermore, a thickness of 0.6 μm to 5 μm is even more preferable, and a thickness of 0.8 μm to 3 μm is particularly preferable. A colored metal film may also be used as the UV absorbing light-to-heat conversion layer.

[0024] In another embodiment, the UV-absorbing photothermal conversion layer may be a resin layer formed by applying a photothermal conversion layer-forming composition. The resin layer may contain, for example, an ultraviolet absorber. The resin layer may also be an adhesive layer containing an adhesive. Examples of adhesives include pressure-sensitive adhesives and active energy ray-curable adhesives.

[0025] (ultraviolet absorber) Any suitable ultraviolet absorber can be used as long as it is a compound that absorbs ultraviolet light (for example, a wavelength of 355 nm). Examples of ultraviolet absorbers include benzotriazole-based ultraviolet absorbers, benzophenone-based ultraviolet absorbers, triazine-based ultraviolet absorbers, salicylate-based ultraviolet absorbers, and cyanoacrylate-based ultraviolet absorbers. Among these, triazine-based ultraviolet absorbers or benzotriazole-based ultraviolet absorbers are preferred, and triazine-based ultraviolet absorbers are particularly preferred.

[0026] Examples of hydroxyphenyltriazine-based ultraviolet absorbers include a reaction product of 2-(4,6-bis(2,4-dimethylphenyl)-1,3,5-triazin-2-yl)-5-hydroxyphenyl with [(C10-C16 (mainly C12-C13) alkyloxy)methyl]oxirane (trade name "TINUVIN 400", manufactured by BASF), 2-[4,6-bis(2,4-dimethylphenyl)-1,3,5-triazin-2-yl]-5-[3-(dodecyloxy)-2-hydroxypropoxy]phenol), a reaction product of 2-(2,4-dihydroxyphenyl)-4,6-bis-(2,4-dimethylphenyl)-1,3,5-triazine with (2-ethylhexyl)-glycidic acid ester (trade name "TINUVIN 405, manufactured by BASF), 2,4-bis(2-hydroxy-4-butoxyphenyl)-6-(2,4-dibutoxyphenyl)-1,3,5-triazine (trade name "TINUVIN 460", manufactured by BASF), 2-(4,6-diphenyl-1,3,5-triazin-2-yl)-5-[(hexyl)oxy]-phenol (trade name "TINUVIN 1577", manufactured by BASF), 2-(4,6-diphenyl-1,3,5-triazin-2-yl)-5-[2-(2-ethylhexanoyloxy)ethoxy]-phenol (trade name "ADEKA STAB LA-46", manufactured by ADEKA Corporation), 2-(2-hydroxy-4-[1-octyloxycarbonylethoxy]phenyl)-4,6-bis(4-phenylphenyl)-1,3,5-triazine (trade name "TINUVIN 479" manufactured by BASF), and TINUVIN 477 manufactured by BASF.

[0027] Examples of benzotriazole-based ultraviolet absorbers (benzotriazole-based compounds) include 2-(2-hydroxy-5-tert-butylphenyl)-2H-benzotriazole (trade name "TINUVIN PS", manufactured by BASF), an ester compound of benzenepropanoic acid and 3-(2H-benzotriazol-2-yl)-5-(1,1-dimethylethyl)-4-hydroxy (C7-9 side chain and linear alkyl) (trade name "TINUVIN 384-2", manufactured by BASF), a mixture of octyl 3-[3-tert-butyl-4-hydroxy-5-(5-chloro-2H-benzotriazol-2-yl)phenyl]propionate and 2-ethylhexyl-3-[3-tert-butyl-4-hydroxy-5-(5-chloro-2H-benzotriazol-2-yl)phenyl]propionate (trade name "TINUVIN 109, manufactured by BASF), 2-(2H-benzotriazol-2-yl)-4,6-bis(1-methyl-1-phenylethyl)phenol (trade name "TINUVIN 900", manufactured by BASF), 2-(2H-benzotriazol-2-yl)-6-(1-methyl-1-phenylethyl)-4-(1,1,3,3-tetramethylbutyl)phenol (trade name "TINUVIN 928", manufactured by BASF), reaction products of methyl 3-(3-(2H-benzotriazol-2-yl)-5-tert-butyl-4-hydroxyphenyl)propionate / polyethylene glycol 300 (trade name "TINUVIN 1130", manufactured by BASF), 2-(2H-benzotriazol-2-yl)-p-cresol (trade name "TINUVIN P", manufactured by BASF), 2-(2H-benzotriazol-2-yl)-4,6-bis(1-methyl-1-phenylethyl)phenol (trade name "TINUVIN 234", manufactured by BASF), 2-[5-chloro-2H-benzotriazol-2-yl]-4-methyl-6-(tert-butyl)phenol (trade name "TINUVIN 326", manufactured by BASF), 2-(2H-benzotriazol-2-yl)-4,6-di-tert-pentylphenol (trade name "TINUVIN 328", manufactured by BASF), 2-(2H-benzotriazol-2-yl)-4-(1,1,3,3-tetramethylbutyl)phenol (trade name "TINUVIN 329", manufactured by BASF), 2,2'-methylenebis[6-(2H-benzotriazol-2-yl)-4-(1,1,3,3-tetramethylbutyl)phenol] (trade name "TINUVIN 360", manufactured by BASF), reaction products of methyl 3-(3-(2H-benzotriazol-2-yl)-5-tert-butyl-4-hydroxyphenyl)propionate with polyethylene glycol 300 (trade name "TINUVIN 213", manufactured by BASF), 2-(2H-benzotriazol-2-yl)-6-dodecyl-4-methylphenol (trade name "TINUVIN 571", manufactured by BASF), 2-[2-hydroxy-3-(3,4,5,6-tetrahydrophthalimido-methyl)-5-methylphenyl]benzotriazole (trade name "Sumisorb 250" manufactured by Sumitomo Chemical Co., Ltd.), 2-(3-tert-butyl-2-hydroxy-5-methylphenyl)-5-chloro-2H-benzotriazole (trade name "SEESORB 703" manufactured by Shipro Chemical Co., Ltd.), 2-(2H-benzotriazol-2-yl)-4-methyl-6-(3,4,5,6-tetrahydrophthalimidylmethyl)phenol (trade name "SEESORB 706" manufactured by Shipro Chemical Co., Ltd.), 2-(4-benzoyloxy-2-hydroxyphenyl)-5-chloro-2H-benzotriazole (trade name "SEESORB 7012BA" manufactured by Shipro Chemical Co., Ltd.), 2-tert-butyl-6-(5-chloro-2H-benzotriazol-2-yl)-4-methylphenol (trade name "KEMISORB 73" manufactured by Chemipro Chemical Co., Ltd.), 2,2'-methylenebis[6-(2H-benzotriazol-2-yl)-4-tert-octylphenol] (trade name "ADK STAB LA-31" manufactured by ADEKA Corporation), 2-(2H-benzotriazol-2-yl)-p-cellulose (trade name "ADK STAB LA-32" manufactured by ADEKA Corporation), 2-(5-chloro-2H-benzotriazol-2-yl)-6-tert-butyl-4-methylphenol (trade name "ADK STAB LA-36" manufactured by ADEKA Corporation), etc.

[0028] The ultraviolet absorber may be a dye or a pigment. Examples of pigments include azo-based, phthalocyanine-based, anthraquinone-based, lake-based, perylene-based, perinone-based, quinacridone-based, thioindigo-based, dioxandine-based, isoindolinone-based, and quinophthalone-based pigments. Examples of dyes include azo-based, phthalocyanine-based, anthraquinone-based, carbonyl-based, indigo-based, quinoneimine-based, methine-based, quinoline-based, and nitro-based dyes.

[0029] The molecular weight of the compound constituting the ultraviolet absorber is preferably 100-1,500, more preferably 200-1,200, and even more preferably 200-1,000.

[0030] The maximum absorption wavelength of the ultraviolet absorber is preferably 300 nm to 450 nm, more preferably 320 nm to 400 nm, and even more preferably 330 nm to 380 nm. The difference between the maximum absorption wavelength of the ultraviolet absorber and the maximum absorption wavelength of the photopolymerization initiator is preferably 10 nm or more, more preferably 25 nm or more.

[0031] The content of the ultraviolet absorber is preferably 1 to 50 parts by weight, and more preferably 5 to 20 parts by weight, relative to 100 parts by weight of the base polymer in the UV absorption light-to-heat conversion layer.

[0032] (pressure-sensitive adhesive) Examples of the pressure-sensitive adhesive include acrylic adhesives, rubber adhesives, vinyl alkyl ether adhesives, silicone adhesives, polyester adhesives, polyamide adhesives, urethane adhesives, and styrene-diene block copolymer adhesives. Among these, acrylic adhesives or rubber adhesives are preferred, and acrylic adhesives are more preferred. The adhesives may be used alone or in combination of two or more.

[0033] Examples of the acrylic adhesive include those based on an acrylic polymer (homopolymer or copolymer) containing one or more (meth)acrylic acid alkyl esters as a monomer component. Examples of the acrylic polymer include homopolymers or copolymers of hydrocarbon group-containing (meth)acrylic acid esters such as (meth)acrylic acid alkyl esters, (meth)acrylic acid cycloalkyl esters, and (meth)acrylic acid aryl esters; and copolymers of the hydrocarbon group-containing (meth)acrylic acid esters with other copolymerizable monomers. Specific examples of (meth)acrylic acid alkyl esters include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, isopropyl (meth)acrylate, butyl (meth)acrylate, isobutyl (meth)acrylate, s-butyl (meth)acrylate, t-butyl (meth)acrylate, pentyl (meth)acrylate, hexyl (meth)acrylate, heptyl (meth)acrylate, octyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, isooctyl (meth)acrylate, and butyl (meth)acrylate. Examples of (meth)acrylic acid C1-20 alkyl esters include nonyl acrylate, isononyl (meth)acrylate, decyl (meth)acrylate, isodecyl (meth)acrylate, undecyl (meth)acrylate, dodecyl (meth)acrylate, tridecyl (meth)acrylate, tetradecyl (meth)acrylate, pentadecyl (meth)acrylate, hexadecyl (meth)acrylate, heptadecyl (meth)acrylate, octadecyl (meth)acrylate, nonadecyl (meth)acrylate, and eicosyl (meth)acrylate. Among these, (meth)acrylic acid alkyl esters having a linear or branched alkyl group having 4 to 18 carbon atoms can be preferably used.

[0034] Examples of the other copolymerizable monomers include functional group-containing monomers such as carboxyl group-containing monomers, acid anhydride monomers, hydroxyl group-containing monomers, glycidyl group-containing monomers, sulfonic acid group-containing monomers, phosphate group-containing monomers, acrylamide, and acrylonitrile. Examples of the carboxyl group-containing monomers include acrylic acid, methacrylic acid, carboxyethyl (meth)acrylate, carboxypentyl (meth)acrylate, itaconic acid, maleic acid, fumaric acid, and crotonic acid. Examples of the acid anhydride monomers include maleic anhydride and itaconic anhydride. Examples of the hydroxyl group-containing monomers include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate, 8-hydroxyoctyl (meth)acrylate, 10-hydroxydecyl (meth)acrylate, 12-hydroxylauryl (meth)acrylate, and (4-hydroxymethylcyclohexyl)methyl (meth)acrylate. Examples of glycidyl group-containing monomers include glycidyl (meth)acrylate and methylglycidyl (meth)acrylate. Examples of sulfonic acid group-containing monomers include styrenesulfonic acid, allylsulfonic acid, 2-(meth)acrylamido-2-methylpropanesulfonic acid, (meth)acrylamidopropanesulfonic acid, sulfopropyl (meth)acrylate, and (meth)acryloyloxynaphthalenesulfonic acid. Examples of phosphate group-containing monomers include 2-hydroxyethyl acryloyl phosphate. Examples of acrylamides include N-acryloylmorpholine. These may be used alone or in combination of two or more. The content of the structural units derived from the copolymerizable monomers is preferably 60 parts by weight or less, more preferably 40 parts by weight or less, per 100 parts by weight of the base polymer.

[0035] Examples of the rubber-based pressure-sensitive adhesive include rubber-based pressure-sensitive adhesives whose base polymer is natural rubber; polyisoprene rubber, styrene-butadiene (SB) rubber, styrene-isoprene (SI) rubber, styrene-isoprene-styrene block copolymer (SIS) rubber, styrene-butadiene-styrene block copolymer (SBS) rubber, styrene-ethylene-butylene-styrene block copolymer (SEBS) rubber, styrene-ethylene-propylene-styrene block copolymer (SEPS) rubber, styrene-ethylene-propylene block copolymer (SEP) rubber, reclaimed rubber, butyl rubber, polyisobutylene, and synthetic rubbers such as modified versions of these.

[0036] The pressure-sensitive adhesive may contain any suitable additives as needed, such as crosslinkers, tackifiers (e.g., rosin-based tackifiers, terpene-based tackifiers, hydrocarbon-based tackifiers, etc.), plasticizers (e.g., trimellitic ester-based plasticizers, pyromellitic ester-based plasticizers), pigments, dyes, antioxidants, conductive materials, antistatic agents, light stabilizers, release modifiers, softeners, surfactants, flame retardants, antioxidants, etc.

[0037] (Active energy ray curable adhesive) In one embodiment, the active energy ray-curable adhesive (A1) is used as the active energy ray-curable adhesive, which comprises a base polymer as a matrix and an active energy ray-reactive compound (monomer or oligomer). In another embodiment, an active energy ray-curable adhesive (A2) is used, which comprises an active energy ray-reactive polymer as the base polymer. In one embodiment, the base polymer has a functional group that can be cleaved by a photopolymerization initiator. Examples of the functional group include functional groups having a carbon-carbon double bond. Examples of active energy rays include gamma rays, ultraviolet rays, visible light, infrared rays (heat rays), radio waves, alpha rays, beta rays, electron beams, plasma flow, ionizing rays, and particle beams. Ultraviolet rays are preferred.

[0038] Examples of base polymers used in the PSA (A1) include rubber-based polymers such as natural rubber, polyisobutylene rubber, styrene-butadiene rubber, styrene-isoprene-styrene block copolymer rubber, reclaimed rubber, butyl rubber, polyisobutylene rubber, and nitrile rubber (NBR); silicone-based polymers; and acrylic-based polymers. These polymers may be used alone or in combination of two or more. Among these, acrylic polymers are preferred.

[0039] Examples of acrylic polymers include homopolymers or copolymers of hydrocarbon group-containing (meth)acrylic acid esters such as (meth)acrylic acid alkyl esters, (meth)acrylic acid cycloalkyl esters, and (meth)acrylic acid aryl esters; copolymers of such hydrocarbon group-containing (meth)acrylic acid esters with other copolymerizable monomers, etc. Specific examples of (meth)acrylic acid alkyl esters include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, isopropyl (meth)acrylate, butyl (meth)acrylate, isobutyl (meth)acrylate, s-butyl (meth)acrylate, t-butyl (meth)acrylate, pentyl (meth)acrylate, hexyl (meth)acrylate, heptyl (meth)acrylate, octyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, isooctyl (meth)acrylate, and (meth)acrylate. Examples of (meth)acrylic acid C1-20 alkyl esters include nonyl acrylate, isononyl (meth)acrylate, decyl (meth)acrylate, isodecyl (meth)acrylate, undecyl (meth)acrylate, dodecyl (meth)acrylate, tridecyl (meth)acrylate, tetradecyl (meth)acrylate, pentadecyl (meth)acrylate, hexadecyl (meth)acrylate, heptadecyl (meth)acrylate, octadecyl (meth)acrylate, nonadecyl (meth)acrylate, and eicosyl (meth)acrylate. Among these, (meth)acrylic acid alkyl esters having a linear or branched alkyl group having 4 to 18 carbon atoms can be preferably used.

[0040] Examples of the other copolymerizable monomers include functional group-containing monomers such as carboxyl group-containing monomers, acid anhydride monomers, hydroxyl group-containing monomers, glycidyl group-containing monomers, sulfonic acid group-containing monomers, phosphate group-containing monomers, acrylamide, and acrylonitrile. Examples of the carboxyl group-containing monomers include acrylic acid, methacrylic acid, carboxyethyl (meth)acrylate, carboxypentyl (meth)acrylate, itaconic acid, maleic acid, fumaric acid, and crotonic acid. Examples of the acid anhydride monomers include maleic anhydride and itaconic anhydride. Examples of the hydroxyl group-containing monomers include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate, 8-hydroxyoctyl (meth)acrylate, 10-hydroxydecyl (meth)acrylate, 12-hydroxylauryl (meth)acrylate, and (4-hydroxymethylcyclohexyl)methyl (meth)acrylate. Examples of glycidyl group-containing monomers include glycidyl (meth)acrylate and methylglycidyl (meth)acrylate. Examples of sulfonic acid group-containing monomers include styrenesulfonic acid, allylsulfonic acid, 2-(meth)acrylamido-2-methylpropanesulfonic acid, (meth)acrylamidopropanesulfonic acid, sulfopropyl (meth)acrylate, and (meth)acryloyloxynaphthalenesulfonic acid. Examples of phosphate group-containing monomers include 2-hydroxyethyl acryloyl phosphate. Examples of acrylamides include N-acryloylmorpholine. These may be used alone or in combination of two or more. The content of the structural units derived from the copolymerizable monomers is preferably 60 parts by weight or less, more preferably 40 parts by weight or less, per 100 parts by weight of the base polymer.

[0041] The acrylic polymer may contain a structural unit derived from a polyfunctional monomer. Examples of the polyfunctional monomer include hexanediol di(meth)acrylate, (poly)ethylene glycol di(meth)acrylate, (poly)propylene glycol di(meth)acrylate, neopentyl glycol di(meth)acrylate, pentaerythritol di(meth)acrylate, trimethylolpropane tri(meth)acrylate, pentaerythritol tri(meth)acrylate, dipentaerythritol hexa(meth)acrylate, epoxy (meth)acrylate (i.e., polyglycidyl (meth)acrylate), polyester (meth)acrylate, and urethane (meth)acrylate. These may be used alone or in combination of two or more. The content of the structural unit derived from the polyfunctional monomer is preferably 40 parts by weight or less, more preferably 30 parts by weight or less, per 100 parts by weight of the base polymer.

[0042] The weight-average molecular weight of the acrylic polymer is preferably 100,000 to 3,000,000, and more preferably 200,000 to 2,000,000. The weight-average molecular weight can be measured by GPC (solvent: THF).

[0043] Examples of the active energy ray reactive compound that can be used in the pressure-sensitive adhesive (A1) include photoreactive monomers or oligomers having a functional group with a polymerizable carbon-carbon multiple bond, such as an acryloyl group, a methacryloyl group, a vinyl group, an allyl group, or an acetylene group. Specific examples of the photoreactive monomer include esters of (meth)acrylic acid and polyhydric alcohols such as trimethylolpropane tri(meth)acrylate, tetramethylolmethane tetra(meth)acrylate, pentaerythritol tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, dipentaerythritol monohydroxypenta(meth)acrylate, dipentaerythritol hexa(meth)acrylate, 1,4-butanediol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, and polyethylene glycol di(meth)acrylate; polyfunctional urethane (meth)acrylate; epoxy (meth)acrylate; oligoester (meth)acrylate; etc. Also usable are monomers such as methacryloisocyanate, 2-methacryloyloxyethyl isocyanate (2-isocyanatoethyl methacrylate), and m-isopropenyl-α,α-dimethylbenzyl isocyanate. Specific examples of the photoreactive oligomer include dimers to pentamers of the above-mentioned monomers. The molecular weight of the photoreactive oligomer is preferably 100 to 3,000.

[0044] Furthermore, as the active energy ray reactive compound, a monomer such as epoxidized butadiene, glycidyl methacrylate, acrylamide, vinyl siloxane, or the like, or an oligomer composed of such a monomer may be used.

[0045] In the pressure-sensitive adhesive (A1), the content of the active energy ray-reactive compound is preferably 0.1 to 500 parts by weight, more preferably 5 to 300 parts by weight, and even more preferably 40 to 150 parts by weight, relative to 100 parts by weight of the base polymer.

[0046] Examples of the active energy ray-reactive polymer (base polymer) contained in the pressure-sensitive adhesive (A2) include polymers having functional groups with carbon-carbon multiple bonds such as acryloyl groups, methacryloyl groups, vinyl groups, allyl groups, acetylene groups, etc. Specific examples of the active energy ray-reactive polymer include polymers composed of multifunctional (meth)acrylates, photocationic polymerizable polymers, cinnamoyl group-containing polymers such as polyvinyl cinnamate, diazotized amino novolac resins, polyacrylamides, etc.

[0047] In one embodiment, an active energy ray-reactive polymer is used, which is constructed by introducing an active energy ray-polymerizable carbon-carbon multiple bond into the side chain, main chain, and / or main chain terminal of the acrylic polymer. A method for introducing a radiation-polymerizable carbon-carbon double bond into an acrylic polymer includes, for example, copolymerizing raw material monomers including a monomer having a predetermined functional group (first functional group) to obtain an acrylic polymer, and then subjecting a compound having a radiation-polymerizable carbon-carbon double bond and a predetermined functional group (second functional group) capable of reacting with and bonding to the first functional group to a condensation reaction or addition reaction with the acrylic polymer while maintaining the radiation polymerizability of the carbon-carbon double bond.

[0048] Examples of combinations of the first functional group and the second functional group include a carboxyl group and an epoxy group, an epoxy group and a carboxyl group, a carboxyl group and an aziridyl group, an aziridyl group and a carboxyl group, a hydroxyl group and an isocyanate group, and an isocyanate group and a hydroxyl group. Among these combinations, a hydroxyl group and an isocyanate group, or an isocyanate group and a hydroxyl group, is preferred from the viewpoint of ease of reaction tracking. Furthermore, while producing a polymer having a highly reactive isocyanate group is technically difficult, from the viewpoint of ease of production or availability of the acrylic polymer, it is more preferred that the first functional group on the acrylic polymer be a hydroxyl group and the second functional group be an isocyanate group. In this case, examples of isocyanate compounds having both a radiation-polymerizable carbon-carbon double bond and an isocyanate group as the second functional group include methacryloyl isocyanate, 2-methacryloyloxyethyl isocyanate, and m-isopropenyl-α,α-dimethylbenzyl isocyanate. Furthermore, the acrylic polymer having a first functional group is preferably one that contains a structural unit derived from the above-mentioned hydroxy group-containing monomer, and is also preferably one that contains a structural unit derived from an ether compound such as 2-hydroxyethyl vinyl ether, 4-hydroxybutyl vinyl ether, or diethylene glycol monovinyl ether.

[0049] The pressure-sensitive adhesive (A2) may further contain the active energy ray-reactive compound (monomer or oligomer).

[0050] The active energy ray-curable pressure-sensitive adhesive may contain a photopolymerization initiator.

[0051] Any suitable initiator can be used as the photopolymerization initiator. Examples of the photopolymerization initiator include α-ketol compounds such as 4-(2-hydroxyethoxy)phenyl(2-hydroxy-2-propyl)ketone, α-hydroxy-α,α'-dimethylacetophenone, 2-methyl-2-hydroxypropiophenone, and 1-hydroxycyclohexylphenyl ketone; acetophenone compounds such as methoxyacetophenone, 2,2-dimethoxy-2-phenylacetophenone, 2,2-diethoxyacetophenone, and 2-methyl-1-[4-(methylthio)-phenyl]-2-morpholinopropane-1; benzoin ether compounds such as benzoin ethyl ether, benzoin isopropyl ether, and anisoin methyl ether; and ketal compounds such as benzyl dimethyl ketal. Examples of suitable photopolymerization initiators include aromatic sulfonyl chloride compounds such as 2-naphthalenesulfonyl chloride, photoactive oxime compounds such as 1-phenone-1,1-propanedione-2-(o-ethoxycarbonyl)oxime, benzophenone compounds such as benzophenone, benzoylbenzoic acid, and 3,3'-dimethyl-4-methoxybenzophenone, thioxanthone compounds such as thioxanthone, 2-chlorothioxanthone, 2-methylthioxanthone, 2,4-dimethylthioxanthone, isopropylthioxanthone, 2,4-dichlorothioxanthone, 2,4-diethylthioxanthone, and 2,4-diisopropylthioxanthone, camphorquinone, halogenated ketones, acylphosphinoxides, and acylphosphonates. The amount of the photopolymerization initiator used can be set to any appropriate amount.

[0052] In one embodiment, the active energy ray-curable pressure-sensitive adhesive may contain a photosensitizer.

[0053] Preferably, the active energy ray-curable pressure-sensitive adhesive contains a crosslinking agent, such as an isocyanate-based crosslinking agent, an epoxy-based crosslinking agent, an oxazoline-based crosslinking agent, an aziridine-based crosslinking agent, a melamine-based crosslinking agent, a peroxide-based crosslinking agent, a urea-based crosslinking agent, a metal alkoxide-based crosslinking agent, a metal chelate-based crosslinking agent, a metal salt-based crosslinking agent, a carbodiimide-based crosslinking agent, or an amine-based crosslinking agent.

[0054] The content of the crosslinking agent is preferably 0.01 to 20 parts by weight relative to 100 parts by weight of the base polymer of the pressure-sensitive adhesive.

[0055] In one embodiment, an epoxy-based crosslinking agent is preferably used. Examples of the epoxy-based crosslinking agent include N,N,N',N'-tetraglycidyl-m-xylenediamine, diglycidylaniline, 1,3-bis(N,N-glycidylaminomethyl)cyclohexane (manufactured by Mitsubishi Gas Chemical Company, Inc., trade name "Tetrad C"), 1,6-hexanediol diglycidyl ether (manufactured by Kyoeisha Chemical Co., Ltd., trade name "Epolite 1600"), neopentyl glycol diglycidyl ether (manufactured by Kyoeisha Chemical Co., Ltd., trade name "Epolite 1500NP"), ethylene glycol diglycidyl ether (manufactured by Kyoeisha Chemical Co., Ltd., trade name "Epolite 1500NP"), and the like. Licor diglycidyl ether (manufactured by Kyoeisha Chemical Co., Ltd., trade name "Epolight 40E"), propylene glycol diglycidyl ether (manufactured by Kyoeisha Chemical Co., Ltd., trade name "Epolight 70P"), polyethylene glycol diglycidyl ether (manufactured by NOF Corporation, trade name "Epiol E-400"), polypropylene glycol diglycidyl ether (manufactured by NOF Corporation, trade name "Epiol P-200"), sorbitol polyglycidyl ether (manufactured by Nagase ChemteX Corporation, trade name "Denacol") Examples of suitable epoxy crosslinking agents include glycerol polyglycidyl ether (manufactured by Nagase ChemteX Corporation under the trade name "Denacol EX-611"), glycerol polyglycidyl ether (manufactured by Nagase ChemteX Corporation under the trade name "Denacol EX-314"), pentaerythritol polyglycidyl ether, polyglycerol polyglycidyl ether (manufactured by Nagase ChemteX Corporation under the trade name "Denacol EX-512"), sorbitan polyglycidyl ether, trimethylolpropane polyglycidyl ether, adipic acid diglycidyl ester, o-phthalic acid diglycidyl ester, triglycidyl tris(2-hydroxyethyl)isocyanurate, resorcinol diglycidyl ether, bisphenol-S-diglycidyl ether, and epoxy resins having two or more epoxy groups in the molecule. The content of the epoxy crosslinking agent can be set to any appropriate amount depending on the desired properties, and is typically 0.01 to 10 parts by weight, and more preferably 0.05 to 7 parts by weight, per 100 parts by weight of the base polymer.

[0056] In one embodiment, an isocyanate-based crosslinking agent is preferably used. Specific examples of the isocyanate-based crosslinking agent include lower aliphatic polyisocyanates such as butylene diisocyanate and hexamethylene diisocyanate; alicyclic isocyanates such as cyclopentylene diisocyanate, cyclohexylene diisocyanate and isophorone diisocyanate; aromatic isocyanates such as 2,4-tolylene diisocyanate, 4,4'-diphenylmethane diisocyanate and xylylene diisocyanate; and isocyanate adducts such as trimethylolpropane / tolylene diisocyanate trimer adduct (manufactured by Nippon Polyurethane Industry Co., Ltd., trade name "Coronate L"), trimethylolpropane / hexamethylene diisocyanate trimer adduct (manufactured by Nippon Polyurethane Industry Co., Ltd., trade name "Coronate HL"), and isocyanurate of hexamethylene diisocyanate (manufactured by Nippon Polyurethane Industry Co., Ltd., trade name "Coronate HX"). Preferably, a crosslinking agent having three or more isocyanate groups is used. The content of the isocyanate crosslinking agent can be set to any appropriate amount depending on the desired properties, and is typically 0.1 to 20 parts by weight, more preferably 0.5 to 10 parts by weight, per 100 parts by weight of the base polymer.

[0057] The active energy ray-curable pressure-sensitive adhesive may further contain any appropriate additives as necessary, such as an active energy ray polymerization accelerator, a radical scavenger, a tackifier, a plasticizer (e.g., a trimellitic acid ester-based plasticizer, a pyromellitic acid ester-based plasticizer, etc.), a pigment, a dye, a filler, an antioxidant, a conductive material, an antistatic agent, an ultraviolet absorber, a light stabilizer, a release adjuster, a softener, a surfactant, a flame retardant, and an antioxidant.

[0058] B-2. Photothermal conversion layer capable of absorbing IR light In one embodiment, a photothermal conversion layer capable of absorbing IR light (hereinafter also referred to as an IR-absorbing photothermal conversion layer) is formed. In one embodiment, a pressure-sensitive adhesive sheet having an IR-absorbing photothermal conversion layer can be peeled off using IR laser light. The IR-absorbing photothermal conversion layer has a transmittance of 50% or less, more preferably 40% or less, even more preferably 35% or less, and most preferably 0% for light with a wavelength of 1032 nm. The IR-absorbing photothermal conversion layer may also be a layer capable of absorbing ultraviolet light, in which case the peeling can be performed using not only IR laser light but also UV laser light.

[0059] In one embodiment, the IR absorbing light-to-heat conversion layer is composed of a resin film. In one embodiment, the resin film may be a colored film containing a predetermined coloring matter (pigment or dye) to absorb IR light of a predetermined wavelength. The colored film serving as the IR absorbing light-to-heat conversion layer may be a film (e.g., a single-layer film) in which the coloring matter is contained in the resin, or a film consisting of a layer (e.g., a printed layer) containing the predetermined coloring matter and a resin layer. When a layer containing the coloring matter is formed, it is preferable that the layer containing the coloring matter and the thermal decomposition layer are adjacent to each other. Any suitable coloring matter may be used in any suitable amount as long as it can impart IR light absorption. Examples of such coloring matter include carbon black, cesium tungsten oxide, lanthanum hexaboride, tin-doped indium oxide, antimony-doped tin oxide, cyanine compounds, phthalocyanine compounds, dithiol metal complexes, naphthoquinone compounds, diimmonium compounds, and azo compounds. Examples of resins that can be used to form the resin film include polyimide resins, polyethylene terephthalate resins, polyamide resins, polyether ether ketone resins, polyethylene naphthalate resins, acrylic resins, and epoxy resins. Among these, polyimide resins and polyethylene terephthalate resins are preferred. Furthermore, a colored metal film (e.g., a metal film having a colored printed layer) may be used as the IR absorption light-to-heat conversion layer. The method for forming the printed layer is as described above.

[0060] C. Pyrolysis layer The 5% weight loss temperature of the pyrolysis layer is preferably 250°C to 400°C, and more preferably 280°C to 370°C. Within this range, the effects of the present invention are more pronounced. The 5% weight loss temperature of the pyrolysis layer can be adjusted, for example, by the type and structure of the resin (base polymer of the adhesive) constituting the pyrolysis layer, the presence or absence and type of additives, etc. If the 5% weight loss temperature is too low, i.e., if the heat resistance is too low, excessive decomposition may occur throughout the pyrolysis layer when irradiated with laser light, which may hinder separation of the electronic component from the support.

[0061] The gel fraction of the pyrolysis layer is preferably 70% or more, more preferably 80% to 99%, and even more preferably 85% to 97%. Within this range, removal of the pyrolysis layer as residue on the support after separating the electronic component from the support becomes significantly easier. More specifically, if laser light irradiation for generating heat in the photothermal conversion layer unnecessarily heats the pyrolysis layer, the pyrolysis product of the pyrolysis layer may be baked onto the support. Conventionally, recovery of a clean support has been laborious. However, by setting the gel fraction of the pyrolysis layer within the above range, removal of the pyrolysis layer becomes significantly easier. An organic solvent such as toluene can be used to remove the pyrolysis layer. The gel fraction of the pyrolysis layer can be controlled by adjusting the composition of the base polymer constituting the pyrolysis layer, the type and content of the crosslinking agent added to the pyrolysis layer, the type and content of the tackifier, etc. The gel fraction can be measured as follows. Approximately 0.5 g of the pyrolysis layer was sampled and weighed accurately (sample weight). The sample was wrapped in a mesh sheet (trade name "NTF-1122", manufactured by Nitto Denko Corporation) and then immersed in 50 ml of toluene at room temperature (25°C) for one week. Thereafter, the solvent-insoluble matter (contents of the mesh sheet) was removed from the toluene and dried at 130°C for approximately two hours. The dried solvent-insoluble matter was weighed (weight after immersion and drying), and the gel fraction (wt%) was calculated using the following formula (a): Gel fraction (wt%) = [(weight after immersion and drying) / (weight of sample)] × 100 (a)

[0062] The tensile modulus of the pyrolysis layer at 25°C is preferably 0.05 MPa to 1 GPa, more preferably 0.1 MPa to 300 MPa. Within this range, the pyrolysis layer can be easily removed as a residue on the support after the electronic component is separated from the support. For example, the pyrolysis layer can be swelled, and most of the pyrolysis layer as a residue can be removed all at once.

[0063] The thickness of the pyrolysis layer is preferably 10 μm to 200 μm, more preferably 20 μm to 150 μm, and even more preferably 30 μm to 100 μm.

[0064] In one embodiment, the thermal decomposition layer has a transmittance of 80% or more to light with a wavelength of 355 nm, more preferably 82% to 98%, and even more preferably 85% to 97%. Within this range, when peeling is performed by irradiation with UV laser light, the laser light can be made to preferably reach the photothermal conversion layer, and peeling of the photothermal conversion layer at the interface between the thermal decomposition layer and the photothermal conversion layer is promoted.

[0065] In one embodiment, the thermal decomposition layer has a transmittance of 80% or more, more preferably 85% to 98%, and even more preferably 90% to 96% for light with a wavelength of 1032 nm. Within this range, when peeling is performed by irradiating an IR laser beam, the laser beam can be made to preferably reach the photothermal conversion layer, and peeling of the photothermal conversion layer at the interface between the thermal decomposition layer and the photothermal conversion layer is promoted.

[0066] In one embodiment, the thermal decomposition layer includes a pressure-sensitive adhesive, such as the pressure-sensitive adhesives described in section B above.

[0067] D. Adhesive layer (other layers) As described above, in one embodiment, an adhesive layer may be disposed on the surface of the photothermal conversion layer opposite the thermal decomposition layer. The adhesive layer may contain any appropriate adhesive, such as the pressure-sensitive adhesive described above. In one embodiment, a heat-resistant adhesive is used as the adhesive contained in the adhesive layer. By providing an adhesive layer made of a heat-resistant adhesive, it is possible to prevent scorching (adhesive residue) on the workpiece (device) when irradiated with laser light. In this specification, a heat-resistant adhesive refers to an adhesive that has a predetermined adhesive strength in an environment of 260°C. It is preferable that the heat-resistant adhesive can be used in an environment of 260°C without leaving any adhesive residue. Preferably, the heat-resistant adhesive contains an acrylic resin, a silicone resin, or the like as a base polymer.

[0068] E. Manufacturing method of adhesive sheet The pressure-sensitive adhesive sheet of the present invention can be produced by any appropriate method. The pressure-sensitive adhesive sheet of the present invention can be formed, for example, by coating a resin film that will serve as the photothermal conversion layer with a thermal decomposition layer-forming composition (e.g., a pressure-sensitive adhesive). Alternatively, the pressure-sensitive adhesive sheet can be obtained by laminating a thermal decomposition layer formed on a separate substrate to the photothermal conversion layer. Alternatively, the pressure-sensitive adhesive sheet can be formed by laminating a photothermal conversion layer formed on a predetermined substrate by coating the photothermal conversion layer-forming composition with a thermal decomposition layer formed on another substrate by coating the thermal decomposition layer-forming composition. Various coating methods can be used, including bar coater coating, air knife coating, gravure coating, gravure reverse coating, reverse roll coating, lip coating, die coating, dip coating, offset printing, flexographic printing, and screen printing. When the photothermal conversion layer-forming composition contains an active energy ray-reactive compound, the coating layer of the photothermal conversion layer-forming composition may be irradiated with active energy rays such as ultraviolet light. The irradiation conditions can be any appropriate conditions depending on the composition of the photothermal conversion layer-forming composition.

[0069] F. Use of adhesive sheets for temporary fixing of electronic components In one embodiment, as described above, the adhesive sheet 100 is placed on the support 200 with the pyrolysis layer side facing the support 200, and an electronic component 300, which is the workpiece, is placed on the side of the adhesive sheet 100 opposite the support 200 (Figure 2(a)). Laser light is irradiated onto the adhesive sheet 100 placed on the support 200, causing the photothermal conversion layer 10 to generate heat. The generated heat propagates to the adjacent pyrolysis layer 20, causing the pyrolysis layer 20 to begin to decompose, for example locally, at the interface with the photothermal conversion layer 10 (Figure 2(b)). As a result, the interface between the pyrolysis layer 20 and the photothermal conversion layer 10 changes shape and loses its adhesiveness, allowing the photothermal conversion layer 10 to be peeled off from the support 200 (Figure 2(c)). Next, the pyrolysis layer 20 on the support 200 is removed (for example, by immersion in toluene), thereby reducing residue and allowing the recovery of a clean support 200 (Figure 2(d)).

[0070] Examples of the electronic component that is the workpiece include a semiconductor wafer, a semiconductor package, a semiconductor chip, an insulating material for a circuit board, a die attach film, a ceramic material, etc. A plurality of the electronic components may be arranged, or one electronic component may be arranged.

[0071] The electronic component can be attached to the pressure-sensitive adhesive sheet via, for example, a pressure-sensitive adhesive layer disposed on the side of the light-to-heat conversion layer opposite the thermal decomposition layer.

[0072] After placing the electronic component on the pressure-sensitive adhesive sheet (i.e., the state shown in FIG. 2(a)), the electronic component may be subjected to a predetermined process, such as grinding, dicing, die bonding, wire bonding, etching, vapor deposition, molding, rewiring, through-hole formation, or device surface protection.

[0073] The laser light used may have any suitable wavelength depending on the configuration of the pressure-sensitive adhesive sheet. The conditions for laser light irradiation may also be any suitable conditions depending on the configuration of the pressure-sensitive adhesive sheet. In one embodiment, UV laser light is used as the laser light. The wavelength of the UV laser light is preferably 150 nm to 380 nm, more preferably 240 nm to 360 nm. The output of the UV laser light is, for example, 0.1 W to 2.0 W. In another embodiment, IR laser light is used as the laser light. The wavelength of the IR laser light is preferably 800 nm to 10600 nm, more preferably 900 nm to 1200 nm. The output of the IR laser light is, for example, 0.01 W to 10 W. [Example]

[0074] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples. Evaluation methods in the examples are as follows. In the examples, "parts" and "%" are by weight unless otherwise specified.

[0075] [evaluation] (1) Tensile modulus of the light-to-heat conversion layer at 200°C The photothermal conversion layers obtained in the examples and comparative examples were used as samples to measure the tensile modulus at 200°C under the following conditions using a dynamic viscoelasticity measuring device (manufactured by TA Instrument, product name "RSA-3"). Measurement frequency: 1Hz Distortion: 0.05% Chuck distance: 20mm Sample width: 10mm Heating rate from 0℃ to 250℃ at 5℃ / min (2) Tensile modulus of the pyrolysis layer at 25°C The thermal decomposition layers obtained in the examples and comparative examples were used as samples to measure the tensile modulus at 25°C under the same conditions as in (1) above using a dynamic viscoelasticity measuring device (manufactured by TA Instrument, product name "RSA-3"). (3) 5% weight loss temperature of the photothermal conversion layer and the thermal decomposition layer The photothermal conversion layers and thermal decomposition layers obtained in the examples and comparative examples were used as evaluation samples. Using a differential thermal analyzer (manufactured by TA Instruments, trade name "Discovery TGA"), the temperature at which the weight decreased by 5% was measured at a temperature increase rate of 10°C / min in a N2 atmosphere with a flow rate of 25 ml / min. Specifically, about 0.01 g of the evaluation sample was placed in the analyzer, heated from 20°C to 110°C at the above heating rate, and cooled from 110°C to 20°C at a rate of 10°C / min to remove the effect of contained moisture, and then heated again at the above heating rate from 20°C to 500°C while measuring the weight loss of the evaluation sample. From the obtained data, the temperature at which the weight loss was 5% was extracted. (4) Light transmittance of the photothermal conversion layer, thermal decomposition layer, and adhesive sheet The photothermal conversion layer, the thermal decomposition layer and the adhesive sheet obtained in the examples and comparative examples were used as evaluation samples. The samples were set in a spectrophotometer (product name "UV-VIS ultraviolet-visible spectrophotometer SolidSpec3700", manufactured by Shimadzu Corporation) so that incident light was perpendicular to each sample, and the light transmittance in the wavelength range of 300 nm to 2500 nm was measured. The transmittance at wavelengths of 355 nm and 1032 nm was extracted from the obtained transmission spectrum. (5) Adhesive strength of adhesive layer The thermal decomposition layer side of the adhesive sheet was attached and fixed to a stainless steel plate, and the adhesive layer was attached to a polyethylene terephthalate film (manufactured by Toray Industries, Inc., trade name "Lumirror S10", thickness: 25 μm), and the adhesive strength of the pressure-sensitive adhesive layer side to PET#25 was measured using a method in accordance with JIS Z 0237:2000 (lamination conditions: 1 round trip with a 2 kg roller, tensile speed: 300 mm / min, peel angle: 180°, measurement temperature: 23°C). (6) Initial adhesive strength to glass (thermal decomposition layer side) The thermal decomposition layer side of the adhesive sheet was attached to glass, and the initial adhesive strength of the thermal decomposition layer side of the adhesive sheet to glass was measured using a method in accordance with JIS Z 0237:2000 (lamination conditions: one round trip with a 2 kg roller, tensile speed: 300 mm / min, peel angle: 180°, measurement temperature: 23°C). The glass used in the above and evaluation (7) below was the non-tin side of a Matsunami Glass slide glass, product number S200423 (water-polished edge, 65 mm x 165 mm x 1.3 mmT). The non-tin side was considered to be the side that did not develop color when exposed to UV light using a UV lamp. (7) Laser debonding evaluation The adhesive layer side of the adhesive sheet obtained in the examples and comparative examples was attached with a hand roller to a thin glass plate (Matsunami Glass Co., Ltd., rectangular cover glass No. 1, product name "C050701") measuring 50 mm in width, 70 mm in length, and 0.12 mm in thickness, simulating a workpiece such as a semiconductor wafer. The adhesive sheet was then cut to the size of the thin glass plate. The pyrolysis layer side was then laminated with a hand roller to a support (a thick glass plate (Matsunami Glass Co., Ltd., large slide glass, standard large, white-edged polished No. 2, product name "S9112") measuring 52 mm in width, 76 mm in length, and 1.0 mm in thickness, simulating a light-transmitting support substrate). The laminate was then placed in an autoclave and heated to degass (40°C, 5 kgf, 10 minutes) to remove any air bubbles trapped in the laminate, producing a laminate sample. The prepared laminate sample was irradiated with laser light from the support side to evaluate laser debonding. Specifically, for IR laser debonding evaluation, a laser with a wavelength of 1032 nm and a beam diameter of approximately 80 μm was used, and pulse scanning was performed at an output of 7.7 W and a frequency of 25 kHz to achieve a pitch of approximately 80 μm vertically and horizontally. Alternatively, for UV laser debonding evaluation, a laser with a wavelength of 355 nm, a beam width of approximately 10 μm, a beam length of approximately 1.5 mm, and an energy density of 0.5 J / cm was used. 2Using a line laser, pulse scanning was performed at 0.75 W output and a frequency of 10 kHz so that the spacing between the line centers was approximately 10 μm in the width direction and an overlap of at least 0.2 mm in the length direction. After irradiating the laminate sample with lasers of various corresponding wavelengths, we checked whether the thin glass (workpiece) and the support could be debonded and the areas to be debonded. Table 1 shows which laser light was used. The evaluation of laser debonding workability was carried out in the debonding work of thin glass and thick glass, with the debonding workability being rated as ◯ if the laminate sample could be easily debonded by lifting one point on the outer periphery with the cutter blade, △ if the entire outer periphery had to be lifted with the cutter blade to finally debond, and × if the thin glass (workpiece) could not be debonded even when the cutter blade was inserted into the outer periphery and the thin glass (workpiece) broke. (8) Evaluation of the recyclability of the support (7) For samples that could be debonded from thin glass and thick glass in the laser debondability evaluation, the re-recoverability of the support was evaluated. Specifically, the state of contamination on the support after laser debonding was visually observed, and samples that did not leave any irremovable or visible residue after immersion in toluene at 25°C for 2 hours were rated as ◯, and samples that left any residue were rated as ×. (9) Gel fraction of the pyrolysis layer The pyrolysis layer obtained in the examples and comparative examples was used as an evaluation sample. Approximately 0.5 g of the pyrolysis layer was weighed out and used as a sample (weight W1). The sample was wrapped in a porous polytetrafluoroethylene membrane (manufactured by Nitto Denko Corporation, product name "Nitoflon NTF1122", average pore size: 0.2 μm, porosity 75%, thickness 85 μm, weight W2) in a purse shape, and the opening was tied with string (weight W3). The package was immersed in 50 mL of toluene and kept at room temperature (25 ° C) for 7 days to elute only the sol component in the adhesive layer out of the membrane. After that, the package was removed and the toluene adhering to the outer surface was wiped off. The package was dried at 130 ° C for 2 hours, and the weight of the package (W4) was measured. The gel fraction was then calculated by substituting each value into the following formula. Gel fraction (%) = [(W4 - W2 - W3) / W1] x 100

[0076] [Production Example 1] Production of acrylic polymer A 50 parts by weight of butyl acrylate, 50 parts by weight of ethyl acrylate, 5 parts by weight of acrylic acid, 0.1 parts by weight of 2-hydroxyethyl acrylate, 0.3 parts by weight of trimethylolpropane triacrylate, and 0.1 parts by weight of benzoyl peroxide as a polymerization initiator were added to toluene, and the mixture was heated to 70°C to obtain a toluene solution of an acrylic polymer (polymer A).

[0077] [Production Example 2] Production of Acrylic Polymer B 95 parts by weight of 2-ethylhexyl acrylate, 5 parts by weight of acrylic acid, and 0.15 parts by weight of benzoyl peroxide as a polymerization initiator were added to ethyl acetate, and the mixture was heated to 70°C to obtain an ethyl acetate solution of an acrylic polymer (polymer B).

[0078] [Production Example 3] Production of Acrylic Polymer C 30 parts by weight of 2-ethylhexyl acrylate, 70 parts by weight of methyl acrylate, 10 parts by weight of acrylic acid, and 0.2 parts by weight of benzoyl peroxide as a polymerization initiator were added to ethyl acetate, and the mixture was heated to 70°C to obtain an ethyl acetate solution of an acrylic polymer (polymer C).

[0079] [Production Example 4] Production of Acrylic Polymer D 88.8 parts by weight of 2-ethylhexyl acrylate, 11.2 parts by weight of 2-hydroxyethyl acrylate, 0.2 parts by weight of a polymerization initiator (manufactured by NOF Corporation, trade name "Niper BW"), and toluene were mixed together. The resulting mixture was polymerized at 60°C under a nitrogen gas stream to obtain an acrylic copolymer with a weight-average molecular weight (Mw) of approximately 600,000. To a toluene solution containing 100 parts by weight of an acrylic copolymer, 12 parts by weight of methacryloyloxyethyl isocyanate (MOI) and 0.06 parts by weight of butyltin dilaurate were added, and the MOI was subjected to an addition reaction to prepare acrylic polymer D having a carbon-carbon double bond.

[0080] [Production Example 5] Preparation of pressure-sensitive adhesive An adhesive was prepared by mixing an ethyl acetate solution of polymer B (polymer B: 100 parts by weight) with 2 parts by weight of an epoxy-based crosslinking agent (manufactured by Mitsubishi Gas Chemical Company, Inc., trade name "TETRAD-C"). The composition of the adhesive is shown in Table 1.

[0081] [Production Example 6] Preparation of pyrolysis layer-forming composition I (adhesive I) A toluene solution of polymer A (polymer A: 100 parts by weight) and 1 part by weight of an epoxy-based crosslinking agent (manufactured by Mitsubishi Gas Chemical Company, Inc., trade name "TETRAD-C") were mixed to prepare a composition I for forming a pyrolysis layer.

[0082] [Production Example 7] Preparation of pyrolysis layer-forming composition II (adhesive II) A pyrolysis layer-forming composition II was prepared by mixing an ethyl acetate solution of polymer C (polymer A: 100 parts by weight) with 1 part by weight of an epoxy-based crosslinking agent (manufactured by Mitsubishi Gas Chemical Company, Inc., trade name "TETRAD-C").

[0083] [Production Example 8] Preparation of pyrolysis layer-forming composition III (adhesive III) A toluene solution of polymer A (polymer A: 100 parts by weight), 1 part by weight of an epoxy-based crosslinking agent (manufactured by Mitsubishi Gas Chemical Company, Inc., trade name "TETRAD-C"), 70 parts by weight of a UV oligomer (manufactured by Mitsubishi Chemical Corporation, trade name "Shikou UV-1700B"), 30 parts by weight of a UV oligomer (manufactured by Mitsubishi Chemical Corporation, trade name "Shikou UV-3000B"), and 0.5 parts by weight of a photopolymerization initiator (manufactured by BASF, trade name "Omnirad127D") were mixed to prepare a composition III for forming a pyrolysis layer.

[0084] [Production Example 9] Photothermal conversion layer forming composition I A toluene solution of polymer A (polymer A: 100 parts by weight), 1 part by weight of an epoxy-based crosslinking agent (manufactured by Mitsubishi Gas Chemical Company, Inc., trade name "TETRAD-C"), 70 parts by weight of a UV oligomer (manufactured by Mitsubishi Chemical Corporation, trade name "Shikou UV-1700B"), 30 parts by weight of a UV oligomer (manufactured by Mitsubishi Chemical Corporation, trade name "Shikou UV-3000B"), 0.5 parts by weight of a photopolymerization initiator (manufactured by BASF, trade name "Omnirad127D"), and 20 parts by weight of an ultraviolet absorber (a reaction product of 2-(4,6-bis(2,4-dimethylphenyl)-1,3,5-triazin-2-yl)-5-hydroxyphenyl) and [(C10-C16 (mainly C12-C13) alkyloxy)methyl]oxirane, trade name "TINUVIN 400", manufactured by BASF) were mixed to prepare a composition for forming a photothermal conversion layer I.

[0085] [Example 1] The pressure-sensitive adhesive obtained in Production Example 5 was applied to one side of a polyimide film (manufactured by Toray DuPont, trade name "Kapton 100H", thickness: 25 μm) serving as a light-to-heat conversion layer so that the thickness after solvent evaporation (drying) would be 10 μm. The film was then dried to form a pressure-sensitive adhesive layer on the polyimide film, and a polyethylene terephthalate film (manufactured by Toray, trade name "Cerapeel", thickness: 38 μm) with a silicone release agent-treated surface was laminated between rolls to bond the layer together. Next, the composition for forming the thermal decomposition layer I obtained in Production Example 6 was applied to a polyethylene terephthalate film (thickness: 75 μm) with a silicone release agent-treated surface so that the thickness after solvent evaporation (drying) would be 50 μm, and then dried and laminated between rolls to the side opposite the pressure-sensitive adhesive layer of the polyimide film. In this way, an adhesive sheet (adhesive layer (pressure-sensitive adhesive layer) / light-to-heat conversion layer (polyimide film) / thermal decomposition layer) sandwiched between polyethylene terephthalate films with silicone release agent-treated surfaces was obtained. The resulting pressure-sensitive adhesive sheet was subjected to the above evaluations, and the results are shown in Table 1.

[0086] [Example 2] A pressure-sensitive adhesive sheet was obtained in the same manner as in Example 1, except that the resin film (light-to-heat conversion layer) and the composition for forming the thermal decomposition layer shown in Table 1 were used and the thickness of each layer was as shown in Table 1. The pressure-sensitive adhesive sheet obtained was subjected to the above-mentioned evaluations. The results are shown in Table 1. The resin film "black printed PET (1)" used as the light-to-heat conversion layer is a polyethylene terephthalate film with a printed layer, and is a resin film with a transmittance of 0% for light with a wavelength of 1032 nm.

[0087] [Comparative Example 1] The pressure-sensitive adhesive obtained in Production Example 5 was applied to one side of a polyethylene terephthalate film (manufactured by Toray Industries, Inc., trade name "Lumirror S10", thickness: 25 μm) so that the thickness after solvent evaporation (drying) would be 10 μm, and then dried to form an adhesive layer on the polyester terephthalate film. A polyethylene terephthalate film with a silicone release agent-treated surface (manufactured by Toray Industries, Inc., trade name "Cerapeel", thickness: 38 μm) was laminated between rolls to bond the layer together. Next, the composition for forming a photothermal conversion layer I obtained in Production Example 6 was applied to a polyethylene terephthalate film (thickness: 75 μm) with a surface treated with a silicone release agent so that the thickness after solvent evaporation (drying) would be 50 μm, and then dried. The film was then laminated between rolls to the side opposite the pressure-sensitive adhesive layer of the polyester terephthalate film, and an irradiation dose of 1380 mJ / cm 2 UV irradiation was carried out under the following conditions. In this way, an adhesive sheet (adhesive layer (pressure-sensitive adhesive layer) / base layer / photothermal conversion layer) sandwiched between polyethylene terephthalate films with silicone release agent-treated surfaces was obtained. The adhesive sheet in this experimental example does not have a thermal decomposition layer, and exhibits peelability due to decomposition of the photothermal conversion layer by irradiation with laser light. In other words, the photothermal conversion layer also functions as a thermal decomposition layer. The resulting pressure-sensitive adhesive sheet was subjected to the above evaluations, and the results are shown in Table 1.

[0088] Comparative Example 2 (Preparation of photothermal conversion layer forming composition II) A toluene solution of acrylic polymer D obtained in Production Example 4 (polymer D: 100 parts by weight), 0.2 parts by weight of an isocyanate-based crosslinking agent (manufactured by Tosoh Corporation, product name "Coronate L"), 3 parts by weight of a photopolymerization initiator (manufactured by BASF, product name "Omnirad127D"), and 12.5 parts by weight of an ultraviolet absorber (manufactured by BASF, product name "TINUVIN 400") was mixed to prepare a composition II for forming a photothermal conversion layer. (Manufacturing adhesive sheets) The pressure-sensitive adhesive obtained in Production Example 5 was applied to one side of a polyethylene terephthalate film (manufactured by Toray Industries, Inc., trade name "Lumirror S10", thickness: 25 μm) so that the thickness after solvent evaporation (drying) would be 10 μm, and then dried to form an adhesive layer on the polyester terephthalate film. A polyethylene terephthalate film with a silicone release agent-treated surface (manufactured by Toray Industries, Inc., trade name "Cerapeel", thickness: 38 μm) was laminated between rolls to bond the layer together. Next, the composition II for forming a photothermal conversion layer was applied to a polyethylene terephthalate film (thickness: 75 μm) with a silicone release agent-treated surface so that the thickness after solvent evaporation (drying) would be 50 μm, and then dried and laminated between rolls to the side opposite the adhesive layer of the polyester terephthalate film. In this way, an adhesive sheet (adhesive layer (pressure-sensitive adhesive layer) / base layer / photothermal conversion layer) sandwiched between polyethylene terephthalate films with silicone release agent-treated surfaces was obtained. The adhesive sheet in this experimental example does not have a thermal decomposition layer, and exhibits peelability due to decomposition of the photothermal conversion layer by irradiation with laser light. In other words, the photothermal conversion layer also functions as a thermal decomposition layer. The resulting pressure-sensitive adhesive sheet was subjected to the above evaluations, and the results are shown in Table 1.

[0089] Comparative Example 3 The pressure-sensitive adhesive obtained in Production Example 5 was applied to a polyethylene terephthalate film (thickness: 75 μm) with a silicone release agent-treated surface so that the thickness after solvent evaporation (drying) would be 10 μm, and then dried to form an adhesive layer on the polyethylene terephthalate film. The photothermal conversion layer forming composition II obtained in Comparative Example 2 was applied to a polyethylene terephthalate film with a silicone release agent-treated surface (manufactured by Toray Industries, Inc., product name "Cerapeel", thickness: 38 μm) so that the thickness after solvent evaporation (drying) would be 30 μm, and then dried to form a photothermal conversion precursor layer on the polyethylene terephthalate film. Next, the pressure-sensitive adhesive layer and the photothermal conversion precursor layer were laminated together between rolls, and 500 mJ / cm 2 was applied from the photothermal conversion precursor layer side. 2 The laminate was then irradiated with UV light under the conditions of (a) to (b) to obtain a laminate (adhesive layer / light-to-heat conversion layer) sandwiched between polyethylene terephthalate films with surfaces treated with a silicone release agent. The composition III for forming a pyrolysis layer obtained in Production Example 8 was applied to a polyethylene terephthalate film with a silicone release agent-treated surface (manufactured by Toray Industries, Inc., product name "Cerapeel", thickness: 38 μm) so that the thickness after solvent evaporation (drying) would be 50 μm, and then dried to form a pyrolysis layer on the polyethylene terephthalate film. After peeling off the polyethylene terephthalate film with a silicone release agent-treated surface on the photothermal conversion layer side of the laminate, the photothermal conversion layer and the thermal decomposition layer were laminated together between rolls to obtain an adhesive sheet (adhesive layer (pressure-sensitive adhesive layer) / photothermal conversion layer / thermal decomposition layer) sandwiched between polyethylene terephthalate films with silicone release agent-treated surfaces. The resulting pressure-sensitive adhesive sheet was subjected to the above evaluations, and the results are shown in Table 1.

[0090] [Table 1]

[0091] As is clear from Table 1, the pressure-sensitive adhesive sheet for temporarily fixing electronic components of the present invention can satisfactorily separate a temporarily fixed electronic component from a support, and also makes it easy to remove the pyrolysis layer residue on the support. In all examples, separation of the electronic component was achieved by interfacial peeling between the pyrolysis layer and the photothermal conversion layer, and it is believed that this resulted in the above-mentioned excellent effects. On the other hand, in all comparative examples, cohesive failure occurred in the photothermal conversion layer, and the effects of the present invention could not be confirmed. [Explanation of symbols]

[0092] 10. Light-to-heat conversion layer 20 Pyrolysis layer 30 adhesive layer 100 Adhesive sheet for temporary fixing of electronic components 200 Support 300 Electronic Components

Claims

1. a photothermal conversion layer and a thermal decomposition layer disposed on one side of the photothermal conversion layer; the thermal decomposition layer is disposed directly on the light-to-heat conversion layer; the thermally decomposable layer is a layer that has adhesiveness and is thermally decomposable, the 5% weight loss temperature of the thermal decomposition layer is lower than the 5% weight loss temperature of the light-to-heat conversion layer; Adhesive sheet for temporarily fixing electronic components.

2. 2. The pressure-sensitive adhesive sheet for temporarily fixing electronic components according to claim 1, wherein the 5% weight loss temperature of the photothermal conversion layer is 300°C to 600°C.

3. 3. The pressure-sensitive adhesive sheet for temporary fixing of electronic components according to claim 1, wherein the 5% weight loss temperature of the thermal decomposition layer is 250°C to 400°C.

4. 4. The pressure-sensitive adhesive sheet for temporarily fixing electronic components according to claim 1, wherein the light-to-heat conversion layer has a transmittance of 50% or less for light having a wavelength of 355 nm.

5. 5. The pressure-sensitive adhesive sheet for temporarily fixing electronic parts according to claim 1, wherein the light-to-heat conversion layer is a resin film made of a polyimide resin.

6. The pressure-sensitive adhesive sheet for temporarily fixing electronic components according to claim 1 , wherein the thermal decomposition layer has a transmittance of 80% or more for light having a wavelength of 355 nm.

7. The pressure-sensitive adhesive sheet for temporarily fixing electronic components according to claim 1 , wherein the light-to-heat conversion layer has a transmittance of 50% or less for light having a wavelength of 1032 nm.

8. The pressure-sensitive adhesive sheet for temporarily fixing electronic parts according to claim 1 , wherein the light-to-heat conversion layer is a colored film.

9. 9. The pressure-sensitive adhesive sheet for temporary fixing of electronic components according to claim 1, wherein the thermal decomposition layer has a transmittance of 80% or more for light having a wavelength of 1032 nm.

10. The pressure-sensitive adhesive sheet for temporary fixing of electronic components according to claim 1 , wherein the thermal decomposition layer has a gel fraction of 70% or more.

11. The pressure-sensitive adhesive sheet for temporarily fixing electronic components according to claim 1, wherein the photothermal conversion layer has a tensile modulus of elasticity at 200°C of 5 MPa to 2 GPa.

12. Further provided with an adhesive layer, the pressure-sensitive adhesive layer, the photothermal conversion layer, and the thermal decomposition layer are laminated in this order; The pressure-sensitive adhesive sheet for temporarily fixing electronic components according to claim 1 .

13. A method for treating electronic components, comprising placing electronic components on the pressure-sensitive adhesive sheet according to claim 1 and then subjecting the electronic components to a predetermined treatment.

14. The method for processing an electronic component according to claim 13, wherein the processing is grinding, dicing, die bonding, wire bonding, etching, vapor deposition, molding, rewiring formation, through-hole formation, or device surface protection.

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