adhesive sheet

Abstract

Provided is a pressure-sensitive adhesive sheet with which small-sized electronic components (e.g., chips having a size of 50 μm□ or less) can be temporarily fixed satisfactorily and removed satisfactorily.　This pressure-sensitive adhesive sheet includes a pressure-sensitive adhesive layer comprising an actinic-ray-curable pressure-sensitive adhesive, and has a transmittance for light having a wavelength of 360 nm of 0-35% and a transmittance for light having a wavelength of 380 nm of 10-100%. One embodiment of the pressure-sensitive adhesive sheet, which has been applied to a stainless-steel sheet, has an initial adhesive force at 23°C of 0.3-15 N / 20 mm. Another embodiment of the pressure-sensitive adhesive sheet, which has been applied to a stainless-steel sheet and then irradiated with ultraviolet light in an amount of 460 mJ / cm2, has an initial adhesive force at 23°C of 0.01-2.4 N / 20 mm.

Description

[Technical Field]

[0001] The present invention relates to a pressure-sensitive adhesive sheet. [Background technology]

[0002] Conventionally, when processing, transporting, etc., electronic components, a procedure has been performed in which the electronic components are temporarily fixed to a pressure-sensitive adhesive sheet during processing, transport, etc., and then peeled off from the pressure-sensitive adhesive sheet after processing and transport. Pressure-sensitive adhesive sheets used in such operations may have a predetermined adhesive strength during processing and transport (when the electronic components are received) and a decrease in adhesive strength after processing and transport (when the electronic components are delivered). One such pressure-sensitive adhesive sheet has been proposed, which is one in which heat-expandable microspheres are incorporated into the adhesive layer (see, for example, Patent Document 1). Pressure-sensitive adhesive sheets containing heat-expandable microspheres have a predetermined adhesive strength, but when heated, the heat-expandable microspheres expand, forming irregularities on the adhesive surface and reducing the contact area, thereby decreasing or eliminating the adhesive strength. Such pressure-sensitive adhesive sheets have the advantage of being easily peeled off from the adherend without external stress.

[0003] However, in recent years, with the trend toward lighter weight and increased number of devices mounted on them, electronic components have become increasingly miniaturized, creating a need for temporary fixation of electronic components that are as small as the heat-expandable microspheres described above. When temporarily fixing (receiving) and then peeling (delivering) miniaturized electronic components, a higher adhesive strength is required for temporary fixation than for standard-sized electronic components, and selective releasability over a narrower range is required for peeling. However, conventional pressure-sensitive adhesive sheets have the problem that increasing adhesive strength deteriorates releasability, while decreasing adhesive strength deteriorates temporary fixation. Furthermore, when temporarily fixing and then peeling (delivering) miniaturized electronic components, particle size variation can significantly affect the presence of heat-expandable microspheres in areas with large particle sizes and areas without heat-expandable microspheres, which can prevent satisfactory peeling in those areas. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2001-131507 Summary of the Invention [Problem to be solved by the invention]

[0005] The present invention has been made to solve the above-mentioned conventional problems, and its object is to provide an adhesive sheet that can effectively temporarily fix and also easily release small electronic components (e.g., chips measuring 50 μm square or less). [Means for solving the problem]

[0006] The pressure-sensitive adhesive sheet of the present invention is an adhesive sheet comprising an adhesive layer containing an active energy ray-curable adhesive, and has a light transmittance of 0% to 35% at a wavelength of 360 nm and a light transmittance of 10% to 100% at a wavelength of 380 nm. In one embodiment, the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet has an initial adhesive strength at 23° C. of 0.3 N / 20 mm to 15 N / 20 mm when attached to a stainless steel plate. In one embodiment, the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet is attached to a stainless steel plate, and a pressure-sensitive adhesive layer of 460 mJ / cm 2 The adhesive strength at 23°C after irradiation with ultraviolet light is 0.01N / 20mm to 2.4N / 20mm. In one embodiment, the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet is attached to a stainless steel plate, and a pressure-sensitive adhesive layer of 460 mJ / cm 2 The adhesive strength at 23°C after irradiation with ultraviolet light is 50% or less of the initial adhesive strength. In one embodiment, the pressure-sensitive adhesive sheet has a light transmittance of 70% to 100% at a wavelength of 500 nm. In one embodiment, the pressure-sensitive adhesive sheet has a haze value of 50% or less. In one embodiment, the pressure-sensitive adhesive layer contains an ultraviolet absorber, and the ultraviolet absorber has a maximum absorption wavelength of 350 nm or less. In one embodiment, the ultraviolet absorber is a compound having a structure in which three benzene rings are bonded to a triazine structure, and in which the total number of highly electronegative atoms directly bonded to the three benzene rings is less than six. In one embodiment, the pressure-sensitive adhesive layer contains a photopolymerization initiator, and the photopolymerization initiator has an absorption coefficient at a wavelength of 365 nm of 10 ml / g·cm to 10,000 ml / g·cm. In one embodiment, the pressure-sensitive adhesive layer contains a photopolymerization initiator, and the photopolymerization initiator has an absorption coefficient at a wavelength of 405 nm of 10 ml / g·cm or less. In one embodiment, the pressure-sensitive adhesive layer is cured by irradiation with ultraviolet light having a wavelength of 350 nm or more and 380 nm or less. In one embodiment, the pressure-sensitive adhesive layer has a thickness of 0.1 μm to 50 μm. In one embodiment, the surface of the pressure-sensitive adhesive sheet is deformed by irradiation with laser light. In one embodiment, the surface of the pressure-sensitive adhesive sheet is deformed into a convex shape by irradiation with laser light. In one embodiment, the surface of the pressure-sensitive adhesive sheet is deformed into a concave shape by irradiation with laser light. According to another aspect of the present invention, there is provided a method for treating an electronic component, which comprises attaching and fixing an electronic component to a substrate sheet of the above-mentioned pressure-sensitive adhesive sheet, treating the electronic component, irradiating the entire pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet with active energy rays to reduce the adhesive strength of the pressure-sensitive adhesive sheet, and then irradiating the area where releasability is desired to be exhibited with laser light to peel the electronic component. In one embodiment, the electronic component is peeled off in a position-selective manner. In one embodiment, the treatment is grinding, dicing, die bonding, wire bonding, etching, deposition, molding, circuit formation, inspection, testing, cleaning, transfer, alignment, repair, or protection of a device surface. In one embodiment, the treatment method includes peeling the electronic component from the pressure-sensitive adhesive sheet and then placing the electronic component on another sheet. [Effects of the Invention]

[0007] According to the present invention, an adhesive sheet can be provided that can effectively temporarily fix small electronic components (e.g., chips of 50 μm square or less), and that can effectively peel off the small electronic components by having a gas generating layer that can generate gas when irradiated with laser light. [Brief explanation of the drawings]

[0008] [Figure 1] 1(a) is a schematic cross-sectional view of a pressure-sensitive adhesive sheet according to one embodiment of the present invention, and FIG. 1(b) is a schematic cross-sectional view of a pressure-sensitive adhesive sheet according to another embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0009] A. Overview of adhesive sheets FIG. 1(a) is a schematic cross-sectional view of a pressure-sensitive adhesive sheet according to one embodiment of the present invention. A pressure-sensitive adhesive sheet 100 according to this embodiment includes a pressure-sensitive adhesive layer 10. The pressure-sensitive adhesive layer 10 contains an active energy ray-curable pressure-sensitive adhesive. FIG. 1(b) is a schematic cross-sectional view of a pressure-sensitive adhesive sheet according to one embodiment of the present invention. A pressure-sensitive adhesive sheet 100' according to this embodiment further includes a substrate 20, with the pressure-sensitive adhesive layer 10 disposed on at least one side of the substrate 20. Although not shown, the pressure-sensitive adhesive sheet of the present invention may be provided with a release liner on the outside of the pressure-sensitive adhesive layer to protect the adhesive surface until use. The pressure-sensitive adhesive sheet may also include any other appropriate layers as long as the effects of the present invention are achieved. In one embodiment, the pressure-sensitive adhesive sheet of the present invention is composed of only one pressure-sensitive adhesive layer, as shown in FIG. 1(a). In another embodiment, the pressure-sensitive adhesive sheet of the present invention includes a substrate and a pressure-sensitive adhesive layer, with the pressure-sensitive adhesive layer being disposed directly on the substrate (i.e., without any other layers interposed therebetween), as shown in FIG. 1(b). In the present invention, as described below, the adhesive strength of the adhesive layer is reduced and the adhesive layer is deformed, allowing the adherend to be easily peeled off. Therefore, it is possible to construct an adhesive sheet without providing a layer other than the adhesive layer (a so-called separation layer) for separating the adherend from the adhesive sheet. Furthermore, although not shown, the adhesive layer may be disposed on one side of the substrate, and another adhesive layer may be disposed on the other side of the substrate. The form of the other adhesive layer is not limited, and may be a curing type adhesive layer or a pressure-sensitive type adhesive layer.

[0010] The pressure-sensitive adhesive sheet of the present invention has a light transmittance at a wavelength of 360 nm of 0% to 35%, preferably 0% to 30%, more preferably 0.01% to 20%, and even more preferably 0.02% to 10%. The pressure-sensitive adhesive sheet has a light transmittance at a wavelength of 380 nm of 10% to 100%, preferably 20% to 90%, more preferably 30% to 85%, and even more preferably 45% to 80%. The light transmittance of the pressure-sensitive adhesive sheet refers to the light transmittance in the thickness direction of the pressure-sensitive adhesive sheet, and is measured for all of the constituent layers of the pressure-sensitive adhesive sheet. For example, a pressure-sensitive adhesive sheet with such an adjusted light transmittance can be formed by incorporating a predetermined ultraviolet absorber into the pressure-sensitive adhesive layer.

[0011] In the present invention, by incorporating an active energy ray-curable adhesive into the adhesive layer (i.e., forming an active energy ray-curable adhesive layer) and setting the transmittance of ultraviolet light (ultraviolet light with a wavelength of 360 nm and ultraviolet light with a wavelength of 380 nm) within the above range, adherends can be peeled off within a small area by irradiating them with laser light. More specifically, by irradiating the adhesive layer with laser light, gases generated by decomposition of the ultraviolet absorber and / or gases generated by decomposition of the adhesive layer due to heat generated by the ultraviolet absorber cause deformation of the adhesive sheet surface (e.g., the adhesive layer surface), resulting in releasability in the area irradiated with laser light. According to the present invention, deformation can be generated within a small area as described above, and therefore adherends can be successfully peeled off even when extremely small adherends are processed. Furthermore, even when a small adherend requiring separation and a small adherend not requiring separation are temporarily fixed next to each other, separation occurs at the location to be separated and not at the location not requiring separation. In other words, only the small adherend requiring separation can be separated, preventing unnecessary detachment of the small adherend. The pressure-sensitive adhesive sheet of the present invention can enhance its adhesiveness before separation, in part due to its excellent releasability. As a result, when adherend fixation is required, excellent fixation can be achieved, and even if the adherend is small, processing can be performed without any problems. Furthermore, the pressure-sensitive adhesive sheet has excellent directionality during separation, allowing separation only at the desired location, preventing damage and leaving little adhesive residue, which is also advantageous. Note that directionality during separation is an index that represents the positional accuracy when an adherend such as a small electronic component is peeled from the pressure-sensitive adhesive sheet and ejected at a location a certain distance away. Excellent directionality prevents the adherend from flying in an unexpected direction during peeling.

[0012] Deformation of a pressure-sensitive adhesive sheet refers to displacement occurring in the normal direction (thickness direction) and horizontal direction (direction perpendicular to the thickness direction) of the pressure-sensitive adhesive sheet surface (e.g., the pressure-sensitive adhesive layer surface). Deformation of a pressure-sensitive adhesive sheet occurs, for example, by pulse scanning a UV laser beam with a wavelength of 355 nm and a beam diameter of approximately 20 μmφ at an output of 0.80 mW and a frequency of 40 kHz to generate gas from the gas-generating layer. The shape of the deformed sheet is observed, for example, by measuring an arbitrary pulse-scanned spot with a confocal laser microscope or a non-contact interference microscope (WYKO) one minute after laser beam irradiation. The shape may be a bubble (convex), a through-hole (concave), or a depression (concave), and these deformations may result in peelability. To efficiently peel electronic components in the normal direction, a large change in normal displacement before and after laser beam irradiation is preferable, and a bubble-like shape is particularly suitable.

[0013] Furthermore, in the pressure-sensitive adhesive sheet of the present invention, the adhesive layer of which contains an active energy ray-curable adhesive, the adhesive strength of the entire adhesive layer is reduced by irradiation with active energy rays. By irradiating the entire adhesive layer of a pressure-sensitive adhesive sheet to which an adherend has been attached with active energy rays to reduce the adhesive strength, and then irradiating with laser light as described above, excellent releasability is exhibited and adhesive residue after peeling can be prevented. Furthermore, by forming a pressure-sensitive adhesive layer containing an active energy ray-curable adhesive, the laser output required for peeling can be reduced. Because the pressure-sensitive adhesive sheet of the present invention exhibits releasability with low-output laser light, use of this pressure-sensitive adhesive sheet can reduce damage to the adherend during peeling and prevent breakage of the adherend. 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.

[0014] The pressure-sensitive adhesive sheet of the present invention preferably has a light transmittance of 70% to 100%, more preferably 75% to 98%, and even more preferably 80% to 95% at a wavelength of 500 nm. Within such a range, a pressure-sensitive adhesive sheet can be obtained that allows the adherend to be clearly visible through the pressure-sensitive adhesive sheet when the adherend is peeled off by laser light irradiation.

[0015] The haze value of the pressure-sensitive adhesive sheet of the present invention is preferably 70% or less, more preferably 65% ​​or less, and even more preferably 50% or less. Within this range, a pressure-sensitive adhesive sheet can be obtained that allows the adherend to be easily visible through the pressure-sensitive adhesive sheet when peeled off by laser light irradiation. The lower the haze value of the pressure-sensitive adhesive sheet, the better, and the lower limit is, for example, 0.1% (preferably 0%).

[0016] The initial adhesive strength at 23°C when the adhesive layer of the pressure-sensitive adhesive sheet of the present invention is adhered to a stainless steel plate is preferably 0.3 N / 20 mm to 15 N / 20 mm, and more preferably 0.5 N / 20 mm to 10 N / 20 mm. Within this range, a pressure-sensitive adhesive sheet capable of holding an adherend well can be obtained. Furthermore, releasability can be achieved by irradiation with low-energy laser light, resulting in a pressure-sensitive adhesive sheet that leaves little adhesive residue and has excellent directionality upon peeling. In this specification, adhesive strength is measured in accordance with JIS Z 0237:2000. Specifically, the pressure-sensitive adhesive sheet is adhered to an adherend (e.g., a stainless steel plate (arithmetic mean surface roughness Ra: 40±25 nm)) using a 2 kg roller in one reciprocating motion, and the sheet is left to stand at 23°C for 30 minutes. The adhesive strength is then measured by peeling the sheet off at a peel angle of 180° and a peel speed (pulling speed) of 300 mm / min. The adhesive strength of the adhesive layer changes upon irradiation with active energy rays and laser light, and in this specification, "initial adhesive strength" means the adhesive strength before irradiation with active energy rays and laser light.

[0017] In one embodiment, the adhesive layer of the adhesive sheet is attached to a stainless steel plate, and 460 mJ / cm 2The adhesive strength at 23°C after irradiation with ultraviolet light is preferably 0.005 N / 20 mm to 2.4 N / 20 mm, more preferably 0.01 N / 20 mm to 1.5 N / 20 mm, and even more preferably 0.02 N / 20 mm to 1 N / 20 mm. Within these ranges, an adhesive sheet with good releasability can be obtained. The ultraviolet light irradiation can be carried out, for example, using an ultraviolet light irradiation device (manufactured by Nitto Seiki Co., Ltd., product name "UM-810"), irradiating the adhesive with ultraviolet light from a high-pressure mercury lamp (characteristic wavelength: 365 nm, cumulative light amount: 460 mJ / cm). 2 , Irradiation energy: 70W / cm 2 The adhesive layer is irradiated with light (irradiation time: 6.6 seconds).

[0018] The adhesive layer of the adhesive sheet was attached to a stainless steel plate, and 460 mJ / cm 2 The adhesive strength at 23°C after irradiation with ultraviolet light is preferably 50% or less, more preferably 40% or less, particularly preferably 30% or less, and most preferably 20% or less of the initial adhesive strength. Within such a range, a pressure-sensitive adhesive sheet with particularly excellent releasability and little adhesive residue after peeling can be obtained.

[0019] The thickness of the pressure-sensitive adhesive sheet is preferably 1 μm to 300 μm, and more preferably 5 μm to 200 μm.

[0020] In one embodiment, the pressure-sensitive adhesive sheet is used as a carrier sheet for adherends (e.g., electrical components). For example, the pressure-sensitive adhesive sheet can be used in the following manner: (1) transferring a plurality of micro-components arranged on another fixing material onto the pressure-sensitive adhesive sheet, (2) irradiating the pressure-sensitive adhesive sheet with ultraviolet light (e.g., ultraviolet light with a wavelength of 350 nm to 380 nm) to cure the gas-generating layer (preferably, curing the entire gas-generating layer) to reduce adhesive strength, and (3) thereafter irradiating the pressure-sensitive adhesive sheet with UV laser light (e.g., UV laser light with a wavelength of 355 nm) to selectively peel off the micro-components in desired locations.

[0021] As described above, the pressure-sensitive adhesive sheet of the present invention exhibits good releasability when irradiated with laser light. Here, good releasability means (1) releasability with low energy, (2) little adhesive residue, and (3) excellent directionality during peeling. If releasability with low energy is possible, deterioration of the area irradiated with laser light can be prevented. If there is little adhesive residue, problems in subsequent processes can be prevented. If the directionality during peeling is excellent, unnecessary chipping can be prevented.

[0022] B.Adhesive layer The thickness of the pressure-sensitive adhesive layer is preferably 0.1 μm to 500 μm, more preferably 3 μm to 100 μm, even more preferably 5 μm to 80 μm, even more preferably 5 μm to 50 μm, particularly preferably 5 μm to 30 μm, and most preferably 5 μm to 20 μm. By reducing the thickness of the pressure-sensitive adhesive layer within this range, it is possible to further reduce the laser output during peeling, and a pressure-sensitive adhesive sheet with excellent peeling properties can be obtained. By making the thickness of the pressure-sensitive adhesive layer 15 μm or more, a pressure-sensitive adhesive sheet with a convex shape can be easily obtained. By making the thickness of the pressure-sensitive adhesive layer less than 15 μm, a pressure-sensitive adhesive sheet with a concave shape can be easily obtained.

[0023] As described above, the pressure-sensitive adhesive layer contains an active energy ray-curable pressure-sensitive adhesive. In one embodiment, the pressure-sensitive adhesive layer further contains an ultraviolet absorber.

[0024] In one embodiment, the pressure-sensitive adhesive layer is cured by irradiation with ultraviolet light of 350 nm or more and 380 nm or less (preferably 360 nm or more and 370 nm or less). Whether or not the pressure-sensitive adhesive layer has cured can be determined by a decrease in adhesive strength at 23°C. For example, the adhesive strength of the pressure-sensitive adhesive layer at 23°C can decrease by 50% to 90% upon curing.

[0025] (Active energy ray curable adhesive) In one embodiment, an 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) capable of bonding to the base polymer. In another embodiment, an active energy ray-curable adhesive (A2) is used, which comprises an active energy ray-reactive polymer as the base polymer. Preferably, the base polymer has a functional group capable of reacting with a photopolymerization initiator. Examples of such functional groups include a hydroxyl group and a carboxyl group.

[0026] 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.

[0027] 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; and copolymers of such hydrocarbon group-containing (meth)acrylic acid esters with other copolymerizable monomers. Examples of (meth)acrylic acid alkyl esters include the methyl ester, ethyl ester, propyl ester, isopropyl ester, butyl ester, isobutyl ester, s-butyl ester, t-butyl ester, pentyl ester, isopentyl ester, hexyl ester, heptyl ester, octyl ester, 2-ethylhexyl ester, isooctyl ester, nonyl ester, decyl ester, isodecyl ester, undecyl ester, dodecyl ester (i.e., lauryl ester), tridecyl ester, tetradecyl ester, hexadecyl ester, octadecyl ester, and eicosyl ester of (meth)acrylic acid. Examples of (meth)acrylic acid cycloalkyl esters include the cyclopentyl ester and cyclohexyl ester of (meth)acrylic acid. Examples of (meth)acrylic acid aryl esters include phenyl (meth)acrylate and benzyl (meth)acrylate. The content of the structural unit derived from the hydrocarbon group-containing (meth)acrylic acid ester is preferably 40 parts by weight or more, more preferably 60 parts by weight or more, per 100 parts by weight of the base polymer.

[0028] 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.

[0029] The acrylic polymer may contain structural units derived from polyfunctional monomers to form crosslinked structures in the polymer backbone. Examples of polyfunctional monomers 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 units 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.

[0030] 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).

[0031] 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.

[0032] 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.

[0033] Furthermore, the active energy ray-reactive compound may be a mixture of an organic salt such as an onium salt and a compound having multiple heterocycles in the molecule. When the mixture is irradiated with active energy rays (e.g., ultraviolet light or an electron beam), the organic salt is cleaved to generate ions, which act as initiating species to cause a ring-opening reaction of the heterocycles, forming a three-dimensional network structure. Examples of the organic salt include iodonium salts, phosphonium salts, antimonium salts, sulfonium salts, and borate salts. Examples of the heterocycle in the compound having multiple heterocycles in the molecule include oxirane, oxetane, oxolane, thiirane, and aziridine.

[0034] 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.

[0035] 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.

[0036] 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.

[0037] 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.

[0038] The pressure-sensitive adhesive (A2) may further contain the active energy ray-reactive compound (monomer or oligomer).

[0039] The active energy ray-curable pressure-sensitive adhesive may contain a photopolymerization initiator.

[0040] 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.

[0041] In one embodiment, a photopolymerization initiator having an absorption coefficient at a wavelength of 365 nm of 10 ml / g·cm to 10,000 ml / g·cm (preferably 80 ml / g·cm to 8,000 ml / g·cm, more preferably 100 ml / g·cm to 5,000 ml / g·cm) is used. In the present invention, the pressure-sensitive adhesive layer is configured so that the light transmittance at a wavelength of 360 nm of the pressure-sensitive adhesive sheet is 0% to 35%, thereby making it possible to use a photopolymerization initiator that is highly reactive in the medium wavelength range (e.g., 360 nm to 380 nm). A pressure-sensitive adhesive layer containing such a photopolymerization initiator is advantageous in that its properties are less likely to change in situations where curing should not occur, such as during storage or use under a UV-blocking lamp. In this specification, the absorption coefficient refers to the absorption coefficient in methanol. A method for measuring the absorption coefficient will be described later.

[0042] In one embodiment, the photopolymerization initiator has an absorption coefficient at a wavelength of 405 nm of 10 ml / g·cm or less, more preferably 5 ml / g·cm or less.

[0043] The photopolymerization initiator may be a commercially available product. For example, photopolymerization initiators having the above-described absorption coefficient characteristics include those available from BASF under the trade names "Irgacure 651," "Irgacure 184," "Irgacure 1173," "Irgacure 500," "Irgacure 2959," "Irgacure 127," "Irgacure 754," "Irgacure MBF," and "Irgacure 907."

[0044] The content of the photopolymerization initiator is preferably 0.5 to 10 parts by weight, and more preferably 1 to 8 parts by weight, relative to 100 parts by weight of the base polymer of the pressure-sensitive adhesive.

[0045] 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.

[0046] The content of the crosslinking agent is preferably 0.5 to 10 parts by weight, and more preferably 1 to 8 parts by weight, relative to 100 parts by weight of the base polymer of the pressure-sensitive adhesive.

[0047] In one embodiment, an isocyanate-based crosslinking agent is preferably used, which is preferred because it can react with a variety of functional groups. 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.

[0048] 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.

[0049] (ultraviolet absorber) Any appropriate ultraviolet absorber can be used as the ultraviolet absorber, as long as it is a compound that absorbs ultraviolet light (for example, wavelengths of 355 nm or less). 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. In particular, when an acrylic adhesive is used as the adhesive A, triazine-based ultraviolet absorbers can be preferably used because of their high compatibility with the base polymer of the acrylic adhesive. The triazine-based ultraviolet absorber is more preferably composed of a compound having a hydroxyl group, and is particularly preferably an ultraviolet absorber composed of a hydroxyphenyltriazine-based compound (hydroxyphenyltriazine-based ultraviolet absorber).

[0050] 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, and 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 BASF's trade name "TINUVIN 477" and the like.

[0051] 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.

[0052] In one embodiment, the ultraviolet absorber is a compound having a triazine structure to which three benzene rings are bonded, and in which the total number of highly electronegative atoms directly bonded to the three benzene rings is less than six. By using such a compound, a pressure-sensitive adhesive sheet can be obtained that exhibits excellent releasability when irradiated with laser light after widespread (preferably full-surface) irradiation with ultraviolet light (e.g., ultraviolet light with a wavelength of 350 nm to 380 nm). More specifically, as described above, by reducing the number of highly electronegative atoms bonded to the conjugated double bonds (conjugated electron system) related to the benzene rings, the expansion of the conjugated electron system is suppressed, resulting in a compound with a short maximum absorption wavelength. Such a compound is unlikely to block the wavelength of ultraviolet light used for curing, and is therefore suitable as an ultraviolet absorber for use in the present invention. An example of such a compound is BASF's product name "TINUVIN 400."

[0053] 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.

[0054] The molecular weight of the compound constituting the ultraviolet absorber is preferably 100 to 1500, more preferably 200 to 1200, and even more preferably 200 to 1000. Within such a range, a pressure-sensitive adhesive sheet capable of forming a better deformed portion upon irradiation with laser light can be obtained.

[0055] In one embodiment, the maximum absorption wavelength of the ultraviolet absorber is preferably 350 nm or less, more preferably 340 nm or less. Use of such an ultraviolet absorber makes it possible to obtain a pressure-sensitive adhesive sheet that absorbs ultraviolet light favorably, exhibits good releasability, and has excellent property stability under normal conditions.

[0056] The content of the ultraviolet absorber is preferably 1 to 50 parts by weight, more preferably 5 to 20 parts by weight, relative to 100 parts by weight of the base polymer in the pressure-sensitive adhesive layer. Within this range, when the adhesive strength of the entire pressure-sensitive adhesive layer is favorably reduced by irradiation with active energy rays, the pressure-sensitive adhesive layer is favorably cured, and a pressure-sensitive adhesive sheet that exhibits favorable releasability by irradiation with laser light can be obtained.

[0057] C. Base material The substrate may be made of any suitable resin. Examples of the resin include polyolefin resins such as polyethylene resins, polypropylene resins, polybutene resins, and polymethylpentene resins, polyurethane resins, polyester resins, polyimide resins, polyether ketone resins, polystyrene resins, polyvinyl chloride resins, polyvinylidene chloride resins, fluorine resins, silicone resins, cellulose resins, and ionomer resins. Among these, polyolefin resins are preferred.

[0058] The thickness of the substrate is preferably 2 μm to 300 μm, more preferably 2 μm to 100 μm, and even more preferably 2 μm to 50 μm.

[0059] The substrate has a light transmittance of preferably 70% or more, more preferably 80% or more, even more preferably 90% or more, and particularly preferably 95% or more at a wavelength of 355 nm. The upper limit of the substrate's light transmittance at 355 nm is, for example, 98% (preferably 99%).

[0060] D. Another adhesive layer Any suitable adhesive can be used as the adhesive constituting the separate adhesive layer as long as the effects of the present invention can be obtained. Examples of the adhesive include acrylic adhesives, silicone adhesives, vinyl alkyl ether adhesives, polyester adhesives, polyamide adhesives, urethane adhesives, fluorine-based adhesives, styrene-diene block copolymer adhesives, and active energy ray-curable adhesives. Among these, acrylic adhesives, rubber adhesives, and silicone adhesives are preferred, and acrylic adhesives are more preferred.

[0061] The adhesive strength at 23° C. when the other adhesive layer of the pressure-sensitive adhesive sheet is attached to a polyethylene terephthalate film is preferably 0.01 N / 20 mm to 15 N / 20 mm, more preferably 0.05 N / 20 mm to 10 N / 20 mm.

[0062] The transmittance of the other pressure-sensitive adhesive layer at a wavelength of 355 nm is preferably 70% or more, more preferably 80% or more, even more preferably 90% or more, and particularly preferably 95% or more. The upper limit of the transmittance of the other pressure-sensitive adhesive layer at a wavelength of 355 nm is, for example, 98% (preferably 99%).

[0063] E. Manufacturing method of adhesive sheet The PSA sheet can be produced by any appropriate method. The PSA sheet can be obtained, for example, by coating the PSA on a substrate or a release liner. 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. Alternatively, a method can be used in which a PSA layer is separately formed on a release liner and then the liner is laminated to the substrate.

[0064] F. How to use adhesive sheets (how to dispose of electronic components) The pressure-sensitive adhesive sheet of the present invention can be used to temporarily fix any suitable workpiece (e.g., electronic components) when processing the workpiece. A method for using the pressure-sensitive adhesive sheet of the present invention will be described using a method for processing electronic components as an example. Examples of methods for processing electronic components include (i) adhering and fixing an electronic component to the pressure-sensitive adhesive layer of a substrate sheet, (ii) processing the electronic component, (iii) irradiating the entire pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet with active energy rays (e.g., ultraviolet rays) to reduce the adhesive strength of the pressure-sensitive adhesive sheet, and (iv) irradiating the desired area for release with laser light to release the electronic component. This method allows electronic components to be released by natural drop. Furthermore, when multiple electronic components are temporarily fixed, it is also possible to release only a portion of them. By using the pressure-sensitive adhesive sheet of the present invention, the adhesive strength can be reduced to the point where the electronic components naturally drop, making it possible to release even very small electronic components (e.g., 50 μm square) individually.

[0065] The electronic components can be peeled off selectively at their positions. Specifically, a plurality of electronic components are attached and fixed to the pressure-sensitive adhesive sheet, and then some of the electronic components are peeled off while the remaining electronic components remain fixed.

[0066] In one embodiment, the method for treating an electronic component of the present invention comprises applying a predetermined treatment to the electronic component after the electronic component is attached to the pressure-sensitive adhesive sheet and before the electronic component is peeled from the pressure-sensitive adhesive sheet. The treatment is not particularly limited, and examples thereof include grinding, dicing, die bonding, wire bonding, etching, vapor deposition, molding, circuit formation, inspection, testing, cleaning, transfer, alignment, repair, and device surface protection.

[0067] The size of the electronic component (area of ​​the attachment surface) is, for example, 1 μm 2 ~250,000μm 2 In one embodiment, the size of the electronic component (area of ​​the attachment surface) is 1 μm 2 ~6400μm 2In another embodiment, an electronic component having a size (area of ​​the attachment surface) of 1 μm can be subjected to the treatment. 2 ~2500μm 2 of electronic components can be subjected to processing.

[0068] In one embodiment, as described above, a plurality of electronic components can be arranged on the adhesive sheet. The intervals between the electronic components are, for example, 1 μm to 500 μm. The present invention is advantageous in that the intervals can be narrowed to temporarily fix the object to be treated.

[0069] The laser light may be, for example, a UV laser light. The irradiation output of the laser light is, for example, 1 μJ to 1000 μJ. The wavelength of the UV laser light is, for example, 240 nm to 380 nm.

[0070] In one embodiment, the method for treating an electronic component includes, after peeling the electronic component, placing the electronic component on another sheet (for example, an adhesive sheet, a substrate, or the like). [Example]

[0071] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples. Test and evaluation methods in the examples are as follows. Unless otherwise specified, "parts" and "%" are by weight.

[0072] (1) Initial adhesive strength (adhesive layer), adhesive strength of another adhesive layer The adhesive layer of the pressure-sensitive adhesive sheet was attached to SUS430, and the initial adhesive strength of the pressure-sensitive adhesive sheet was measured according to 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). Note that an initial adhesive strength of 2 N / 20 mm or more was evaluated as significantly excellent receptivity (transferability) when the adherend was transferred (◯ in the table); an initial adhesive strength of 0.5 N / 20 mm or more but less than 2 N / 20 mm was evaluated as good receptivity (transferability) when the adherend was transferred (△ in the table); and an initial adhesive strength of less than 0.5 N / 20 mm was evaluated as insufficient receptivity (transferability) when the adherend was transferred (× in the table). In addition, an adhesive layer of the adhesive sheet was attached and fixed to a support such as a stainless steel plate, and another 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 other adhesive layer 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).

[0073] (2) Adhesive strength after UV irradiation The adhesive layer of the adhesive sheet was attached to SUS430, and the entire surface of the adhesive layer was irradiated with ultraviolet light from a high-pressure mercury lamp (specific wavelength: 365 nm, cumulative light intensity: 460 mJ / cm ) using an ultraviolet irradiation device (manufactured by Nitto Seiki, product name "UM-810"). 2 The entire surface was irradiated with ultraviolet light. When the adhesive strength after ultraviolet light irradiation was 0.5 N / 20 mm or less, the peelability was evaluated as being extremely excellent (◯ in the table); when it was 0.5 N / 20 mm or more but less than 2 N / 20 mm, the transferability was evaluated as being good (△ in the table); and when it was 2 N / 20 mm or more, the peelability was evaluated as being insufficient (× in the table).

[0074] (3) Light transmittance The pressure-sensitive adhesive sheet was placed in a spectrophotometer (product name "UV-VIS Ultraviolet-Visible Spectrophotometer SolidSpec3700" manufactured by Shimadzu Corporation) and the light transmittance was measured in the wavelength range of 300 nm to 800 nm with incident light perpendicular to the pressure-sensitive adhesive layer side of the sample. The transmittances at wavelengths of 360 nm, 380 nm, and 500 nm were extracted from the obtained transmission spectrum.

[0075] (4) Changes in the surface shape of the adhesive sheet The entire adhesive layer of the adhesive sheet was exposed to ultraviolet light from a high-pressure mercury lamp (specific wavelength: 365 nm, cumulative light intensity: 460 mJ / cm) using an ultraviolet light irradiation device (manufactured by Nitto Seiki, product name "UM-810"). 2 ) was irradiated onto the entire surface. A glass plate (large slide glass S9112 (standard large white edge polished No. 2) manufactured by Matsunami Glass Co., Ltd.) was then attached to the adhesive layer to obtain a measurement sample. A UV laser beam with a wavelength of 355 nm and a beam diameter of approximately 20 μmφ was used from the glass plate side of the measurement sample, and pulse scanning was performed at an output of 0.80 mW and a frequency of 40 kHz to generate gas from the adhesive layer. The change in the shape of the adhesive sheet surface caused by this operation was observed.

[0076] (5) Haze value The haze value of the pressure-sensitive adhesive sheet was measured using a haze meter (trade name "HAZE METER HM-150", manufactured by Murakami Color Research Laboratory).

[0077] (6)10% weight loss temperature The 10% weight loss temperature of the ultraviolet absorber was measured. Using a differential thermal analyzer (manufactured by TA Instruments, trade name "Discovery TGA"), the adhesive sheet was heated at a temperature of 10°C / min in a N2 atmosphere at a flow rate of 25 ml / min, and the temperature at which the weight lost 10% was measured.

[0078] [Production Example 1] Production of Acrylic Polymer I 100 parts by weight of 2-ethylhexyl acrylate, 12.6 parts by weight of 2-hydroxyethyl acrylate, and 0.25 parts by weight of benzoyl peroxide as a polymerization initiator were added to toluene, and a polymerization reaction was carried out at 60°C under a nitrogen gas stream. 13.5 parts of methacryloyloxyethyl isocyanate was then added to the mixture to carry out an addition reaction, thereby obtaining a toluene solution of an acrylic copolymer having a carbon-carbon double bond (acrylic polymer I).

[0079] [Production Example 2] Production of Acrylic Polymer II 30 parts by weight of 2-ethylhexyl acrylate, 70 parts by weight of ethyl acrylate, 4 parts by weight of 2-hydroxyethyl acrylate, 5 parts by weight of methyl methacrylate, and 0.2 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 copolymer (acrylic polymer II).

[0080] [Production Example 3] Production of acrylic polymer a 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 copolymer (acrylic polymer a).

[0081] [Production Example 4] Production of acrylic polymer b 30 parts by weight of 2-ethylhexyl acrylate, 70 parts by weight of ethyl acrylate, 4 parts by weight of 2-hydroxyethyl acrylate, 5 parts by weight of methyl methacrylate, and 0.2 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 copolymer (acrylic polymer b).

[0082] [Example 1] (Preparation of Adhesive (1)) Acrylic polymer solution I containing 100 parts by weight of acrylic polymer I was mixed with 0.2 parts by weight of a crosslinking agent (manufactured by Nippon Polyurethane Industry Co., Ltd., trade name "Coronate L") and 0.2 parts by weight of an α-hydroxyketone-based photopolymerization initiator (manufactured by BASF Japan, trade name "Irgacure 127", molecular weight: 340.4, extinction coefficient at a wavelength of 365 nm: 1.07 × 10 2 3 parts by weight of hydroxyphenyltriazine-based ultraviolet absorber (manufactured by BASF Japan, trade name "Tinuvin 400", molecular weight: 647.8, 10% weight loss temperature: 391.7°C, maximum absorption wavelength: 336 nm) were added to obtain adhesive (1). (Preparation of Adhesive (2)) To an ethyl acetate solution of acrylic polymer a containing 100 parts by weight of acrylic polymer a, 2 parts by weight of a crosslinking agent (manufactured by Mitsubishi Gas Chemical Company, Inc., trade name "Tetrad C") was added to obtain adhesive (2). (adhesive sheet) Adhesive (1) was applied to one side of a polyethylene terephthalate film (thickness: 50 μm) so that the thickness after solvent evaporation (drying) would be 10 μm to form an adhesive layer, and adhesive (2) was applied to the other side so that the thickness after solvent evaporation (drying) would be 10 μm to form another adhesive layer, and an adhesive sheet was obtained. The obtained pressure-sensitive adhesive sheet was subjected to the above evaluations (1) to (6). The results are shown in Table 1.

[0083] [Examples 2 to 13, Comparative Examples 1 to 7] An adhesive sheet was obtained in the same manner as in Example 1, except that the type of acrylic polymer, the amount of crosslinking agent, the type and amount of photopolymerization initiator, the type and amount of UV absorber, and the thickness of the adhesive layer were as shown in Tables 1 and 2. The obtained adhesive sheet was subjected to the above-mentioned evaluations (1) to (6). The results are shown in Tables 1 and 2. In Comparative Example 1, 20 parts by weight of a surfactant (manufactured by Kao Corporation, trade name "Exsepal IPP") was also added to the adhesive. In Example 13, the adhesive (curable adhesive) was applied to only one side. In Comparative Example 4, 10 parts by weight of a terpene phenol-based tackifying resin (manufactured by Yasuhara Chemical Co., Ltd., trade name "YS Polystar S145") was also added to the adhesive. The materials listed in Table 1 are as follows: "Irg651": BASF Japan, trade name "Irgacure 651", molecular weight: 256.3, absorption coefficient at 365 nm: 3.613 x 10 2 ml / g cm "Tinuvin 477": BASF Japan, product name "Tinuvin 477", molecular weight: 958.2, 10% weight loss temperature: 352.8°C, maximum absorption wavelength: 356nm

[0084] [Table 1]

[0085] [Table 2] [Explanation of symbols]

[0086] 10 adhesive layer 20 Base material 100, 100' adhesive sheet

Claims

1. A pressure-sensitive adhesive sheet having a pressure-sensitive adhesive layer containing an active energy ray-curable pressure-sensitive adhesive, the pressure-sensitive adhesive sheet has a light transmittance of 0% to 35% at a wavelength of 360 nm; the pressure-sensitive adhesive sheet has a light transmittance of 10% to 100% at a wavelength of 380 nm; the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet has an initial adhesive strength of 0.5 N / 20 mm to 15 N / 20 mm at 23°C when attached to a stainless steel plate; the adhesive layer of the pressure-sensitive adhesive sheet is attached to a stainless steel plate, and after irradiation with ultraviolet light of 460 mJ / cm 2 , the adhesive strength at 23°C is 0.01 N / 20 mm to 1.5 N / 20 mm; The adhesive layer of the adhesive sheet was attached to a stainless steel plate, and 460 mJ / cm ２ the adhesive strength at 23°C after irradiation with ultraviolet light is 50% or less of the initial adhesive strength, the pressure-sensitive adhesive layer contains an ultraviolet absorber, The maximum absorption wavelength of the ultraviolet absorber is 350 nm or less. Adhesive sheet.

2. The pressure-sensitive adhesive sheet according to claim 1, wherein the light transmittance at a wavelength of 500 nm is 70% to 100%.

3. The pressure-sensitive adhesive sheet according to claim 1 or 2, which has a haze value of 50% or less.

4. 4. The pressure-sensitive adhesive sheet according to claim 1, wherein the ultraviolet absorber is a compound having a structure in which three benzene rings are bonded to a triazine structure, and in which the total number of highly electronegative atoms directly bonded to the three benzene rings is less than six.

5. the pressure-sensitive adhesive layer contains a photopolymerization initiator, the photopolymerization initiator has an absorption coefficient at a wavelength of 365 nm of 10 ml / g cm to 10,000 ml / g cm; The pressure-sensitive adhesive sheet according to claim 1 .

6. the pressure-sensitive adhesive layer contains a photopolymerization initiator, the photopolymerization initiator has an absorption coefficient at a wavelength of 405 nm of 10 ml / g cm or less; The pressure-sensitive adhesive sheet according to any one of claims 1 to 5.

7. The pressure-sensitive adhesive sheet according to claim 1 , wherein the pressure-sensitive adhesive layer is cured by irradiation with ultraviolet light having a wavelength of 350 nm or more and 380 nm or less.

8. The pressure-sensitive adhesive sheet according to any one of claims 1 to 7, wherein the pressure-sensitive adhesive layer has a thickness of 0.1 µm to 50 µm.

9. The pressure-sensitive adhesive sheet according to claim 1 , wherein the surface of the pressure-sensitive adhesive sheet is deformed by irradiation with laser light.

10. The pressure-sensitive adhesive sheet according to claim 9 , wherein the surface of the pressure-sensitive adhesive sheet is deformed into a convex shape by irradiation with laser light.

11. The pressure-sensitive adhesive sheet according to claim 9 , wherein the surface of the pressure-sensitive adhesive sheet is deformed into a concave shape by irradiation with laser light.

12. An electronic component is attached to and fixed to a receiving sheet of the pressure-sensitive adhesive sheet according to any one of claims 1 to 11, Treating the electronic component; The entire pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet is irradiated with active energy rays to reduce the adhesive strength of the pressure-sensitive adhesive sheet, and then irradiating a laser beam onto a portion where peelability is desired to be exhibited, thereby peeling off the electronic component; How to process electronic components.

13. The method for processing an electronic component according to claim 12, wherein the peeling of the electronic component is performed selectively at a position.

14. The method for processing electronic components according to claim 12 or 13, wherein the processing is grinding, dicing, die bonding, wire bonding, etching, vapor deposition, molding, circuit formation, inspection, testing, cleaning, transfer, alignment, repair, or device surface protection.

15. The method for treating an electronic component according to claim 12 , further comprising the step of: peeling the electronic component from the adhesive sheet, and then placing the electronic component on another sheet.

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