Adhesive sheet

Abstract

Provided is an adhesive sheet that temporarily fixes small electronic components (e.g., chips having a size of 50 μm or less) with good adhesion, and that can be peeled off with good adhesion. The adhesive sheet of the present invention has an adhesive layer containing a curable energy ray 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 initial adhesion at 23°C when the above-described adhesive sheet is attached to a stainless steel plate is 0.3 N / 20 mm to 15 N / 20 mm. In one embodiment, the adhesion at 23°C after the above-described adhesive sheet is attached to a stainless steel plate and 460 mJ / cm 2 of ultraviolet rays is irradiated is 0.01 N / 20 mm to 2.4 N / 20 mm.

Description

Technical Field

[0001] This invention relates to adhesive sheets. Background Technology

[0002] Conventionally, when processing or transferring electronic components, the following operations are sometimes performed: the electronic components are temporarily fixed to an adhesive sheet during processing or transfer, and then peeled off from the adhesive sheet after processing or transfer. As for the adhesive sheet used in this operation, sometimes a sheet with a specified adhesive force is used during processing and transfer (when receiving the electronic components), and sometimes an adhesive sheet with reduced adhesive force is used after processing and transfer (when transferring the electronic components). As one type of adhesive sheet, an adhesive sheet containing thermally expandable microspheres in the adhesive layer has been proposed (for example, Patent Document 1). The adhesive sheet containing thermally expandable microspheres has the following characteristics: it has a specified adhesive force, and by heating, the thermally expandable microspheres expand, thereby forming unevenness on the adhesive surface and reducing the contact area, thus reducing or eliminating the adhesive force. This type of adhesive sheet has the advantage of easily peeling off the adhered object without external stress.

[0003] However, in recent years, with the trend towards lightweighting and increasing the number of components in various devices, the miniaturization of electronic components has led to the necessity of temporarily fixing electronic components that are miniaturized to the same size as the aforementioned thermally expandable microspheres. When temporarily fixing (receiving) miniaturized electronic components and subsequently peeling them off (transferring them), higher adhesive strength is required during temporary fixing than for electronic components of typical size, and peelability needs to be selectively exhibited within a narrower range during peeling. However, in conventional adhesive sheets, increasing the adhesive strength leads to a deterioration in peelability, while decreasing the adhesive strength leads to a deterioration in temporary fixing. Furthermore, when temporarily fixing miniaturized electronic components and subsequently peeling them off (transferring them), the influence of areas with large thermally expandable microspheres due to particle size fluctuations, and areas where thermally expandable microspheres are absent, becomes more significant, sometimes making proper peeling impossible in these areas.

[0004] Existing technical documents

[0005] Patent documents

[0006] Patent Document 1: Japanese Patent Application Publication No. 2001-131507 Summary of the Invention

[0007] The problem the invention aims to solve

[0008] The present invention was made to solve the above-mentioned problems, and its object is to provide an adhesive sheet that can effectively and temporarily fix small electronic components (e.g., chips with a size of 50 μm or less) and can be easily peeled off.

[0009] Solution for solving the problem

[0010] The adhesive sheet of the present invention is an adhesive sheet having an adhesive layer comprising an active energy ray curable adhesive, with a transmittance of 0% to 35% at a wavelength of 360 nm and a transmittance of 10% to 100% at a wavelength of 380 nm.

[0011] In one embodiment, the initial adhesive force at 23°C when the adhesive layer of the adhesive sheet is attached to the stainless steel plate is 0.3 N / 20 mm to 15 N / 20 mm.

[0012] In one embodiment, the adhesive layer of the adhesive sheet is attached to a stainless steel plate and irradiated with 460 mJ / cm². 2 The adhesion strength at 23°C after UV exposure is 0.01N / 20mm~2.4N / 20mm.

[0013] In one embodiment, the adhesive layer of the adhesive sheet is attached to a stainless steel plate and irradiated with 460 mJ / cm². 2 The adhesive strength at 23°C after exposure to ultraviolet light is less than 50% of the initial adhesive strength.

[0014] In one embodiment, the transmittance of the adhesive sheet at a wavelength of 500 nm is 70% to 100%.

[0015] In one embodiment, the haze value of the adhesive sheet is 50% or less.

[0016] In one embodiment, the adhesive layer comprises an ultraviolet absorber having a maximum absorption wavelength of 350 nm or less.

[0017] In one embodiment, the ultraviolet absorber is a compound having a triazine structure with three benzene rings bonded to it, and the total number of highly electronegative atoms directly bonded to the three benzene rings is less than six.

[0018] In one embodiment, the adhesive layer comprises a photopolymerization initiator with an absorption coefficient of 10 ml / g·cm to 10000 ml / g·cm at a wavelength of 365 nm.

[0019] In one embodiment, the adhesive layer comprises a photopolymerization initiator having an absorption coefficient of less than 10 ml / g·cm at a wavelength of 405 nm.

[0020] In one embodiment, the adhesive layer is cured by irradiation with ultraviolet light at a wavelength of 350 nm or higher and 380 nm or lower.

[0021] In one embodiment, the thickness of the adhesive layer is 0.1 μm to 50 μm.

[0022] In one embodiment, the surface of the adhesive sheet is deformed by laser irradiation.

[0023] In one embodiment, the surface of the adhesive sheet is deformed into a convex shape by laser irradiation.

[0024] In one embodiment, the surface of the adhesive sheet is deformed into a concave shape by laser irradiation.

[0025] According to another aspect of the present invention, a method for processing an electronic component is provided. The method includes the following steps: attaching an electronic component to a substrate and fixing it to the adhesive substrate; processing the electronic component; irradiating the adhesive layer of the adhesive substrate entirely with active energy rays to reduce the adhesive force of the adhesive substrate; and then irradiating the area where peelability is desired with a laser to peel off the electronic component.

[0026] In one embodiment, the electronic components are selectively stripped from their locations.

[0027] In one embodiment, the above-mentioned processing is grinding, cutting, chip bonding, wire bonding, etching, vapor deposition, molding, circuit formation, inspection, product inspection, cleaning, transfer, alignment, repair, or protection of device surface.

[0028] In one embodiment, the above processing method includes the following steps: after peeling the electronic component from the adhesive sheet, the electronic component is disposed on another sheet.

[0029] The effects of the invention

[0030] According to the present invention, an adhesive sheet can be provided that can temporarily fix a small electronic component (e.g., a chip with a size of 50 μm or less) in a good manner, and has a gas generating layer that can generate gas by laser irradiation so as to be able to peel off the small electronic component in a good manner. Attached Figure Description

[0031] Figure 1 (a) is a simplified cross-sectional view of an adhesive sheet according to one embodiment of the present invention. Figure 1 (b) is a simplified cross-sectional view of the adhesive sheet according to another embodiment of the present invention. Detailed Implementation

[0032] A. Overview of Adhesive Sheets

[0033] Figure 1 (a) is a simplified cross-sectional view of an adhesive sheet according to one embodiment of the present invention. The adhesive sheet 100 of this embodiment includes an adhesive layer 10. The adhesive layer 10 comprises an active energy radiation-curable adhesive. Figure 1(b) is a simplified cross-sectional view of an adhesive sheet according to one embodiment of the present invention. The adhesive sheet 100' of this embodiment further includes a substrate 20, on which an adhesive layer 10 is disposed at least on one side. Not shown, but for the adhesive sheet of the present invention, a release liner may be provided on the outer side of the adhesive layer to protect the adhesive surface until use. Furthermore, the adhesive sheet may also include any suitable other layers as long as the effects of the present invention are achieved. In one embodiment, such as... Figure 1 As shown in (a), the adhesive sheet of the present invention consists of only one adhesive layer. In another embodiment, as... Figure 1 As shown in (b), the adhesive sheet of the present invention comprises a substrate and an adhesive layer, the adhesive layer being disposed directly (i.e., without the aid of other layers) on the substrate. In the present invention, as described later, in order to effectively peel off the adhered objects by reducing the adhesive force and deforming the adhesive layer, the adhesive sheet can be constructed without providing a layer other than the adhesive layer for separating the adhered objects from the adhesive sheet (a so-called separation layer). Furthermore, although not illustrated, the aforementioned adhesive layer can be disposed on one side of the substrate, and other adhesive layers can be disposed on the other side of the substrate. The form of the other adhesive layers is not limited; they can be curable adhesive layers or pressure-sensitive adhesive layers.

[0034] The transmittance of the adhesive sheet at a wavelength of 360 nm is 0% to 35%, preferably 0% to 30%, more preferably 0.01% to 20%, and even more preferably 0.02% to 10%. Furthermore, the transmittance of the adhesive sheet at a wavelength of 380 nm is 10% to 100%, preferably 20% to 90%, more preferably 30% to 85%, and even more preferably 45% to 80%. It should be noted that the transmittance of the adhesive sheet refers to the transmittance in the thickness direction of the adhesive sheet, and is the transmittance measured with all constituent layers of the adhesive sheet as the object. For example, by containing a specified ultraviolet absorber in the adhesive layer, it is possible to form an adhesive sheet with such adjusted transmittance.

[0035] In this invention, the adhesive layer contains an active energy ray-curable adhesive (i.e., forming an active energy ray-curable adhesive layer), and the transmittance of ultraviolet light (ultraviolet light with a wavelength of 360 nm and ultraviolet light with a wavelength of 380 nm) is within the aforementioned range, thereby enabling the peeling of adhered objects based on laser irradiation within a very small area. More specifically, by irradiating the adhesive layer with a laser, the gas generated by the decomposition of the ultraviolet absorber and / or the gas generated by the decomposition of the adhesive layer due to the heating of the ultraviolet absorber deforms on the surface of the adhesive sheet (e.g., the surface of the adhesive layer), resulting in peelability at the laser-irradiated portion. According to the invention, as described above, deformation can occur within a very small range, thus enabling the good peeling of even extremely fine small adhered objects. Furthermore, when small adhered objects to be peeled are temporarily fixed adjacent to small adhered objects that do not need to be peeled, peeling can be achieved at the peeling target area while not peeling at the non-peeling target area, that is, only the small adhered objects to be peeled can be peeled, and unwanted detachment of small adhered objects can be prevented. The adhesive sheet of the present invention improves adhesion before peeling, partly due to its excellent peelability. As a result, it provides excellent fixation when the adhered object needs to be secured, allowing for the handling of small objects without defects. Furthermore, the adhesive sheet exhibits excellent peeling directionality, enabling peeling only at the desired location, which is advantageous in preventing breakage and minimizing adhesive residue. It should be noted that peeling directionality refers to the positional accuracy when peeling small electronic components or other adhered objects from the adhesive sheet, indicating the accuracy of aiming at a specific distance. Excellent directionality prevents the adhered object from scattering in unexpected directions during peeling.

[0036] Deformation of the adhesive sheet refers to the displacement of the adhesive sheet surface (e.g., the adhesive layer surface) in the normal direction (thickness direction) and the horizontal direction (orthogonal to the thickness direction). Deformation of the adhesive sheet can be generated, for example, by using a wavelength of 355 nm and a beam diameter of approximately... A UV laser, pulsed at 0.80mW power and 40kHz frequency, generates gas from the gas-generating layer. The deformed shape is observed, for example, at any point after the pulse scan, measured one minute after laser irradiation using a confocal laser microscope or a non-contact interferometer (WYKO). Its shape can be bubbly (convex), porous (concave-convex), or pitted (concave), and its deformation produces a peelable structure. For efficient peeling of electronic components in the normal direction, a large change in displacement in the normal direction before and after laser irradiation is preferred, particularly suitable for forming bubbly shapes.

[0037] Furthermore, the adhesive sheet of the present invention, whose adhesive layer contains an active energy ray-curable adhesive, exhibits reduced overall adhesive strength by irradiation with active energy rays. By irradiating the entire adhesive layer of the adhesive sheet to which the adhered object is attached with active energy rays, the adhesive strength is reduced, and as described above, excellent peelability is achieved, preventing residue after peeling. Additionally, by forming an adhesive layer containing an active energy ray-curable adhesive, the laser power during peeling can be reduced. The adhesive sheet of the present invention exhibits peelability under low-power laser light; therefore, using this adhesive sheet reduces damage to the adhered object during peeling and prevents breakage of the adhered object. Examples of active energy rays include gamma rays, ultraviolet rays, visible light, infrared rays (thermal rays), radio waves, alpha rays, beta rays, electron beams, plasma streams, ionizing rays, and particle beams. Ultraviolet rays are preferred.

[0038] The transmittance of the adhesive sheet at a wavelength of 500 nm is preferably 70% to 100%, more preferably 75% to 98%, and even more preferably 80% to 95%. If it is within this range, when the adhered objects are peeled off by laser irradiation, an adhesive sheet can be obtained in which the adhered objects to be peeled can be clearly identified through the adhesive sheet.

[0039] The haze value of the adhesive sheet of the present invention is preferably 70% or less, more preferably 65% ​​or less, and even more preferably 50% or less. If it is within this range, when the adhered objects are peeled off by laser irradiation, an adhesive sheet can be obtained in which the adhered objects to be peeled can be clearly identified through the adhesive sheet. The lower the haze value of the adhesive sheet, the more preferred, and the lower limit is, for example, 0.1% (preferably 0%).

[0040] When the adhesive layer of the adhesive sheet of the present invention is attached to a stainless steel plate, the initial adhesive force at 23°C is preferably 0.3 N / 20 mm to 15 N / 20 mm, more preferably 0.5 N / 20 mm to 10 N / 20 mm. Within this range, an adhesive sheet that can well retain the adhered object can be obtained. Furthermore, peelability can be improved by low-energy laser irradiation, resulting in an adhesive sheet with less adhesive residue and excellent directional peeling. In this specification, the adhesive force is measured according to JIS Z 0237:2000. Specifically, the adhesive sheet is attached to an object (e.g., a stainless steel plate (arithmetic mean surface roughness Ra: 40 ± 25 nm)) by reciprocating once with a 2 kg roller, and after being placed at 23°C for 30 minutes, the adhesive sheet is peeled off and measured under conditions of a peel angle of 180° and a peeling speed (stretching speed) of 300 mm / min. The adhesive force of the adhesive layer changes upon irradiation with active energy rays and laser irradiation, but in this specification, "initial adhesive force" refers to the adhesive force before irradiation with active energy rays and laser.

[0041] In one embodiment, the adhesive layer of the adhesive sheet is attached to a stainless steel plate and irradiated with 460 mJ / cm². 2 The adhesive strength at 23°C after UV irradiation 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 this range, an adhesive sheet with good peelability can be obtained. The UV irradiation is performed as follows: using a UV irradiation device (manufactured by Nitto Seiki Co., Ltd., trade name "UM-810"), the adhesive layer is irradiated with ultraviolet light from a high-pressure mercury lamp (characteristic wavelength: 365 nm, cumulative light intensity: 460 mJ / cm²). 2 Irradiation energy: 70W / cm 2 Irradiation time: 6.6 seconds.

[0042] The adhesive layer of the adhesive sheet is attached to a stainless steel plate and irradiated with 460 mJ / cm. 2 The adhesive strength at 23°C after exposure to ultraviolet light is preferably 50% or less, more preferably 40% or less, particularly preferably 30% or less, and most preferably 20% or less relative to the initial adhesive strength. If it is within this range, an adhesive sheet with particularly excellent peelability and little adhesive residue after peeling can be obtained.

[0043] The thickness of the adhesive sheet is preferably 1μm to 300μm, more preferably 5μm to 200μm.

[0044] In one embodiment, the adhesive sheet can be used as a carrier sheet for the adhered object (e.g., an electrical component). For example, the adhesive sheet can be used in the following manner: (1) transferring and receiving a plurality of miniature components disposed on other fixing materials onto the adhesive sheet; (2) irradiating the 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 to cure the entire gas-generating layer) and reduce the adhesive force; (3) thereafter irradiating with a UV laser (e.g., a UV laser with a wavelength of 355 nm) to selectively peel off the miniature components located at the desired location.

[0045] As described above, the adhesive sheet of the present invention exhibits good peelability through laser irradiation. Here, good peelability means: (1) peeling with low energy, (2) minimal adhesive residue, and (3) excellent directional properties during peeling. If peeling can be performed with low energy, deterioration of the laser-irradiated area can be prevented. If there is minimal adhesive residue, defects in subsequent processes can be prevented. If the directional properties during peeling are excellent, unwanted chips can be prevented from scattering.

[0046] B. Adhesive layer

[0047] The thickness of the adhesive layer is preferably 0.1 μm to 500 μm, more preferably 3 μm to 100 μm, further 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 thinning the adhesive layer within this range, the laser power during peeling can be further reduced, resulting in an adhesive sheet with excellent peel performance. By making the adhesive layer thickness 15 μm or more, it becomes easier to obtain an adhesive sheet with a convex shape. By making the adhesive layer thickness less than 15 μm, it becomes easier to obtain an adhesive sheet with a concave shape.

[0048] As described above, the adhesive layer comprises an active energy radiation-curable adhesive. In one embodiment, the adhesive layer further comprises an ultraviolet absorber.

[0049] In one embodiment, the adhesive layer is cured by irradiation with ultraviolet light at a wavelength of 350 nm or more and 380 nm or less (preferably 360 nm or more and 370 nm or less). Whether curing has occurred can be determined by the decrease in adhesive strength at 23°C. For example, if the adhesive layer cures, the adhesive strength at 23°C can be reduced by 50% to 90%.

[0050] (Active energy radiation curing adhesive)

[0051] In one embodiment, an active energy radiation-curable adhesive (A1) can be used as an active energy radiation-curable adhesive, comprising a base polymer as a masterbatch and an active energy radiation-reactive compound (monomer or oligomer) that can bind to the base polymer. In another embodiment, an active energy radiation-curable adhesive (A2) can be used, comprising an active energy radiation-reactive polymer as the base polymer. Preferably, the base polymer has a functional group that can react with a photopolymerization initiator. Examples of such functional groups include thiol groups and carboxyl groups.

[0052] Examples of base polymers used in the aforementioned adhesive (A1) include natural rubber, polyisobutylene rubber, styrene / butadiene rubber, styrene / isoprene / styrene block copolymer rubber, reclaimed rubber, butyl rubber, polyisobutylene rubber, nitrile rubber (NBR), and other rubber-based polymers; silicone-based polymers; and acrylic polymers. These polymers can be used alone or in combination of two or more. Among them, acrylic polymers are preferred.

[0053] Examples of acrylic polymers include homopolymers or copolymers of hydrocarbon-containing (meth)acrylates such as alkyl (meth)acrylates, cycloalkyl (meth)acrylates, and aryl (meth)acrylates; and copolymers of these hydrocarbon-containing (meth)acrylates with other comonomers. Examples of alkyl (meth)acrylates include methyl esters, ethyl esters, propyl esters, isopropyl esters, butyl esters, isobutyl esters, sec-butyl esters, tert-butyl esters, pentyl esters, isopentyl esters, hexyl esters, heptyl esters, octyl esters, 2-ethylhexyl esters, isooctyl esters, nonyl esters, decyl esters, isodecanyl esters, undecyl esters, dodecyl esters (i.e., lauryl esters), tridecyl esters, tetradecyl esters, hexadecyl esters, octadecyl esters, and eicosyl esters. Examples of cycloalkyl (meth)acrylates include cyclopentyl esters and cyclohexyl esters of (meth)acrylate. Examples of aryl (meth)acrylates include phenyl (meth)acrylate and benzyl (meth)acrylate. The proportion of the structural unit derived from the hydrocarbon (meth)acrylate relative to 100 parts by weight of the base polymer is preferably 40 parts by weight or more, more preferably 60 parts by weight or more.

[0054] Examples of other copolymerizable monomers include, for example, carboxyl-containing monomers, acid anhydride monomers, hydroxyl-containing monomers, glycidyl-containing monomers, sulfonic acid monomers, phosphate-containing monomers, acrylamide, and acrylonitrile, which contain functional groups. Examples of carboxyl-containing monomers include, for example, acrylic acid, methacrylic acid, carboxyethyl methacrylate, carboxypentyl methacrylate, itaconic acid, maleic acid, fumaric acid, and crotonic acid. Examples of acid anhydride monomers include, for example, maleic anhydride and itaconic anhydride. Examples of hydroxyl-containing monomers include, for example, 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, 4-hydroxybutyl methacrylate, 6-hydroxyhexyl methacrylate, 8-hydroxyoctyl methacrylate, 10-hydroxydecyl methacrylate, 12-hydroxylauryl methacrylate, and methyl methacrylate (4-hydroxymethylcyclohexyl) Examples of monomers containing glycidyl groups include glycidyl (meth)acrylate and methyl glycidyl (meth)acrylate. Examples of monomers containing sulfonic acid groups include styrene sulfonic acid, allyl sulfonic acid, 2-(meth)acrylamide-2-methylpropanesulfonic acid, (meth)acrylamide propanesulfonic acid, sulfopropyl (meth)acrylate, and (meth)acryloyloxynaphthalene sulfonic acid. Examples of monomers containing phosphate groups include 2-hydroxyethylacryloyl phosphate. Examples of acrylamides include N-acryloylmorpholine. These monomers can be used individually or in combination of two or more. The proportion of the structural units derived from the above-mentioned copolymeric monomers relative to 100 parts by weight of the base polymer is preferably 60 parts by weight or less, more preferably 40 parts by weight or less.

[0055] Acrylic polymers may contain structural units derived from multifunctional monomers to form a crosslinked structure in their polymer backbone. Examples of multifunctional monomers include hexanediol di(meth)acrylate, polyethylene glycol di(meth)acrylate, polypropylene 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. They may be used individually or in combination of two or more. The proportion of the structural units derived from the aforementioned multifunctional monomers relative to 100 parts by weight of the base polymer is preferably 40 parts by weight or less, more preferably 30 parts by weight or less.

[0056] The weight-average molecular weight of the above-mentioned acrylic polymers is preferably 100,000 to 3,000,000, more preferably 200,000 to 2,000,000. The weight-average molecular weight can be determined by GPC (solvent: THF).

[0057] Examples of photoreactive compounds that can be used in the aforementioned adhesive (A1) include: monomers or oligomers possessing photoreactive functional groups such as acryloyl, methacryl, vinyl, allyl, and ethynyl groups, which have polymerizable carbon-carbon multiple bonds. Specific examples of such photoreactive monomers include esters of (meth)acrylic acid and polyols 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)acrylates; epoxy (meth)acrylates; and low-polyester (meth)acrylates. Alternatively, monomers such as isocyanates, 2-methacryloyloxyethyl isocyanate (2-isocyanate ethyl methacrylate), and m-isopropenyl-α,α-dimethylbenzyl isocyanate can also be used. Specific examples of photoreactive oligomers include 2- to 5-mers of the above monomers. The molecular weight of the photoreactive oligomer is preferably between 100 and 3000.

[0058] In addition, monomers such as epoxide butadiene, glycidyl methacrylate, acrylamide, and vinylsiloxane, or oligomers composed of such monomers, can be used as the above-mentioned reactive energy radiation compounds.

[0059] Furthermore, as the aforementioned reactive compounds for active energy rays, mixtures of organic salts such as onium salts and compounds having multiple heterocycles within the molecule can be used. This mixture is irradiated with active energy rays (e.g., ultraviolet light, electron beams) to cause the organic salts to decompose and generate ions, which act as initiators, inducing ring-opening reactions of the heterocycles and forming a three-dimensional network structure. Examples of the aforementioned organic salts include iodonium salts, phosphonium salts, antimony salts, sulfonium salts, and borates. Examples of heterocycles in the aforementioned compounds having multiple heterocycles within the molecule include ethylene oxide, oxetane, oxopentane, thiohexacyclopropane, and aziridine.

[0060] In the above-mentioned adhesive (A1), the proportion of the active energy ray reactive compound relative to 100 parts by weight of the base polymer is preferably 0.1 parts by weight to 500 parts by weight, more preferably 5 parts by weight to 300 parts by weight, and even more preferably 40 parts by weight to 150 parts by weight.

[0061] Examples of active energy-reactive polymers (basic polymers) contained in the aforementioned adhesive (A2) include polymers possessing functional groups with carbon-carbon multiple bonds, such as acryloyl, methacryloyl, vinyl, allyl, and ethynyl groups. Specific examples of active energy-reactive polymers include polymers composed of polyfunctional (meth)acrylates; photocationic polymers; cinnamoyl-containing polymers such as polyvinyl cinnamate; diazotized aminophenolic varnish resins; polyacrylamide; and so on.

[0062] In one embodiment, an active energy-ray reactive polymer is used, which is formed by introducing active energy-ray polymerizable carbon-carbon multiple bonds into the side chains, main chains, and / or main chain ends of the aforementioned acrylic polymer. As a method for introducing radiopolymerizable carbon-carbon double bonds into the acrylic polymer, an example method is as follows: After copolymerizing a raw material monomer containing a monomer having a predetermined functional group (first functional group) to obtain an acrylic polymer, while maintaining the radiopolymerizability of the carbon-carbon double bonds, a compound having a predetermined functional group (second functional group) and radiopolymerizable carbon-carbon double bonds that can react and combine with the first functional group is subjected to a condensation reaction or addition reaction with the acrylic polymer.

[0063] Examples of combinations of the first and second functional groups include carboxyl and epoxy groups, epoxy and carboxyl groups, carboxyl and glycidyl groups, glycidyl and carboxyl groups, hydroxyl and isocyanate groups, and isocyanate and hydroxyl groups. Among these combinations, from the viewpoint of ease of reaction tracking, combinations of hydroxyl and isocyanate groups and combinations of isocyanate and hydroxyl groups are preferred. Furthermore, the production of polymers with highly reactive isocyanate groups is technically difficult; therefore, from the viewpoint of ease of production or acquisition of acrylic polymers, the case where the first functional group on the acrylic polymer side is a hydroxyl group and the second functional group is an isocyanate group is more preferred. In this case, examples of isocyanate compounds possessing both a radially polymerizable carbon-carbon double bond and an isocyanate group belonging to the second functional group include methacryloyl isocyanate, 2-methacryloyloxyethyl isocyanate, and m-isopropenyl-α,α-dimethylbenzyl isocyanate. Furthermore, as an acrylic polymer having a first functional group, it is preferable to include structural units derived from the above-mentioned hydroxyl-containing monomers, and it is also preferable to include structural units derived from ether compounds such as 2-hydroxyethyl vinyl ether, 4-hydroxybutyl vinyl ether, and diethylene glycol monovinyl ether.

[0064] The adhesive (A2) described above may further contain the aforementioned reactive energy ray compound (monomer or oligomer).

[0065] The aforementioned active energy ray-cured adhesives may contain photopolymerization initiators.

[0066] Any suitable initiator can be used as a photopolymerization initiator. Examples of photopolymerization initiators include α-keto alcohol compounds such as 4-(2-hydroxyethoxy)phenyl(2-hydroxy-2-propyl)one, α-hydroxy-α,α'-dimethylacetophenone, 2-methyl-2-hydroxyphenylacetone, and 1-hydroxycyclohexylphenylone; acetophenone compounds such as methoxyacetophenone, 2,2-dimethoxy-2-phenylacetophenone, 2,2-diethoxyacetophenone, and 2-methyl-1-[4-(methylthio)-phenyl]-2-morpholino-1-propane; benzoin ether compounds such as benzoin ethyl ether, benzoin isopropyl ether, and anisole methyl ether; and benzoin dimethyl ether. Ketal compounds such as ketal acetals; aromatic sulfonyl chloride compounds such as 2-naphthalenesulfonyl chloride; photoactive oxime compounds such as 1-benzophenone-1,1-propanedione-2-(o-ethoxycarbonyl)oxime; benzophenone compounds such as benzoylbenzoic acid and 3,3'-dimethyl-4-methoxybenzophenone; thioxanthone compounds such as 2-chlorothioxanthone, 2-methylthioxanthone, 2,4-dimethylthioxanthone, isopropylthioxanthone, 2,4-dichlorothioxanthone, 2,4-diethylthioxanthone, and 2,4-diisopropylthioxanthone; camphorquinone; haloketones; acylphosphine oxides; acyl phosphates, etc. The amount of photopolymerization initiator can be set to any appropriate amount.

[0067] In one embodiment, a photopolymerization initiator with an absorptivity of 10 ml / g·cm to 10000 ml / g·cm (preferably 80 ml / g·cm to 8000 ml / g·cm, more preferably 100 ml / g·cm to 5000 ml / g·cm) at a wavelength of 365 nm is used. In this invention, the adhesive layer is constructed such that the transmittance of the adhesive sheet at a wavelength of 360 nm is 0% to 35%, thereby allowing the use of a photopolymerization initiator with high reactivity in the mid-wavelength (e.g., 360 nm to 380 nm) region. Adhesive layers containing such photopolymerization initiators are advantageous in that their properties are less likely to change when they should not cure, such as during storage or use under a UV cut lamp. It should be noted that in this specification, the absorptivity refers to the absorptivity in methanol. The method for measuring the absorptivity is described below.

[0068] In one embodiment, the absorption coefficient of the photopolymerization initiator at a wavelength of 405 nm is 10 ml / g·cm or less, more preferably 5 ml / g·cm or less.

[0069] Commercially available products can also be used as photopolymerization initiators. For example, photopolymerization initiators with the above-mentioned absorption coefficient characteristics include those manufactured by BASF under the trade names "IRGACURE 651", "IRGACURE 184", "IRGACURE 1173", "IRGACURE 500", "IRGACURE 2959", "IRGACURE 127", "IRGACURE 754", "IRGACURE MBF", and "IRGACURE 907".

[0070] The proportion of the above-mentioned photopolymerization initiator relative to 100 parts by weight of the base polymer of the adhesive is preferably 0.5 parts by weight to 10 parts by weight, more preferably 1 part by weight to 8 parts by weight.

[0071] Preferably, the above-mentioned active energy radiation-curable adhesive includes a crosslinking agent. Examples of crosslinking agents include isocyanate-based crosslinking agents, epoxy-based crosslinking agents, oxazoline-based crosslinking agents, aziridine-based crosslinking agents, melamine-based crosslinking agents, peroxide-based crosslinking agents, urea-based crosslinking agents, metal alkoxide-based crosslinking agents, metal chelate-based crosslinking agents, metal salt-based crosslinking agents, carbodiimide-based crosslinking agents, and amine-based crosslinking agents.

[0072] The crosslinking agent is preferably 0.5 to 10 parts by weight, more preferably 1 to 8 parts by weight, relative to 100 parts by weight of the base polymer of the adhesive.

[0073] In one embodiment, an isocyanate-based crosslinking agent is preferred. Isocyanate-based crosslinking agents are preferred in that they can react with a variety of functional groups. Specific examples of the aforementioned isocyanate-based crosslinking agents include lower aliphatic polyisocyanates such as butylene diisocyanate and hexamethylene diisocyanate; alicyclic isocyanates such as cyclopentylene diisocyanate, cyclohexylene diisocyanate, and isophorone diisocyanate; aromatic isocyanates such as 2,4-toluene diisocyanate, 4,4'-diphenylmethane diisocyanate, and xylene diisocyanate; isocyanate adducts such as trimethylolpropane / toluene 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 derivatives of hexamethylene diisocyanate (manufactured by Nippon Polyurethane Industry Co., Ltd., trade name "CORONATE HX"); etc. Crosslinking agents with three or more isocyanate groups are preferred.

[0074] Active energy radiation-cured adhesives may further include any suitable additives as needed. Examples of additives include, for instance, active energy radiation polymerization accelerators, free radical scavengers, tackifiers, plasticizers (e.g., trimellitate plasticizers, pyromellitic ester plasticizers, etc.), pigments, dyes, fillers, antioxidants, conductive materials, antistatic agents, UV absorbers, light stabilizers, peel modifiers, softeners, surfactants, flame retardants, antioxidants, etc.

[0075] (UV absorber)

[0076] As a UV absorber, any suitable UV absorber can be used as long as it is a compound that absorbs ultraviolet light (e.g., wavelengths below 355 nm). Examples of UV absorbers include benzotriazole-based UV absorbers, benzophenone-based UV absorbers, triazine-based UV absorbers, salicylate-based UV absorbers, and cyanoacrylate-based UV absorbers. Among these, triazine-based or benzotriazole-based UV absorbers are preferred, and triazine-based UV absorbers are particularly preferred. When using an acrylic adhesive as adhesive A, triazine-based UV absorbers are particularly preferred from the perspective of high compatibility between the acrylic adhesive and the base polymer. Triazine-based UV absorbers are more preferably composed of compounds having hydroxyl groups, and UV absorbers composed of hydroxyphenyltriazine compounds (hydroxyphenyltriazine-based UV absorbers) are particularly preferred.

[0077] Examples of hydroxyphenyl triazine-based ultraviolet absorbers include, for instance, the reaction product of 2-(4,6-bis(2,4-dimethylphenyl)-1,3,5-triazin-2-yl)-5-hydroxyphenyl with [(C10-C16 (mainly C12-C13)alkoxy)methyl]ethylene oxide (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 the reaction product of 2-(2,4-dihydroxyphenyl)-4,6-bis-(2,4-dimethylphenyl)-1,3,5-triazine with (2-ethylhexyl)-glycidyl 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 "Adekastab LA-46", manufactured by ADEKA Corporation), 2-(2-hydroxy-4-[1-octoxycarbonylethoxy]phenyl)-4,6-bis(4-phenylphenyl)-1,3,5-triazine (trade name "TINUVIN") 479”, manufactured by BASF, and the BASF-manufactured product name “TINUVIN 477”, etc.

[0078] Examples of benzotriazole-based ultraviolet absorbers (benzotriazole compounds) include 2-(2-hydroxy-5-tert-butylphenyl)-2H-benzotriazole (trade name "TINUVIN PS", manufactured by BASF), phenylpropionic acid and esters of 3-(2H-benzotriazole-2-yl)-5-(1,1-dimethylethyl)-4-hydroxy (C7-9 side chain and straight-chain alkyl) (trade name "TINUVIN 384-2", manufactured by BASF), and mixtures of octyl 3-[3-tert-butyl-4-hydroxy-5-(5-chloro-2H-benzotriazole-2-yl)phenyl]propionate and 2-ethylhexyl-3-[3-tert-butyl-4-hydroxy-5-(5-chloro-2H-benzotriazole-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), methyl 3-(3-(2H-benzotriazol-2-yl)-5-tert-butyl-4-hydroxyphenyl)propionate / polyethylene glycol 300 reaction product (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”, 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-(1,1,3,3-tetramethylbutyl)phenol (trade name “TINUVIN 328”, manufactured by BASF), 2-(2H-benzotriazol-2-yl)-4-(1,1,3,3-tetramethylbutyl)phenol (trade name “TINUVIN 326”, 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-(1,1,3,3-tetramethylbutyl)phenol (trade name “TINUVIN 326”, manufactured by BASF), 2-[2H-benzotriazol-2-yl]- 329” (BASF), 2,2'-methylenebis[6-(2H-benzotriazol-2-yl)-4-(1,1,3,3-tetramethylbutyl)phenol] (trade name "TINUVIN 360", BASF), methyl 3-(3-(2H-benzotriazol-2-yl)-5-tert-butyl-4-hydroxyphenyl)propionate reacting with polyethylene glycol 300 (trade name "TINUVIN 213", BASF), 2-(2H-benzotriazol-2-yl)-6-dodecyl-4-methylphenol (trade name "TINUVIN 571", BASF), 2-[2-hydroxy-3-(3,[4,5,6-Tetrahydrophthalimide-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 KASEI KAISHA,LTD.), 2-(2H-benzotriazole-2-yl)-4-methyl-6-(3,4,5,6-tetrahydrophthalimide-methyl)phenol (trade name "SEESORB 706", manufactured by SHIPRO KASEI KAISHA,LTD.), 2-(4-benzoyloxy-2-hydroxyphenyl)-5-chloro-2H-benzotriazole (trade name "SEESORB" manufactured by SHIPRO KASEI KAISHA,LTD.) 7012BA”), 2-tert-butyl-6-(5-chloro-2H-benzotriazol-2-yl)-4-methylphenol (trade name “KEMISORB 73”, manufactured by Chemipro Kasei Co., Ltd.), 2,2'-methylenebis[6-(2H-benzotriazol-2-yl)-4-tert-octylphenol] (trade name “Adekastab LA-31”, manufactured by ADEKA Co., Ltd.), 2-(2H-benzotriazol-2-yl)-p-cellulose (trade name “Adekastab LA-32”, manufactured by ADEKA Co., Ltd.), 2-(5-chloro-2H-benzotriazol-2-yl)-6-tert-butyl-4-methylphenol (trade name “Adekastab LA-36”, manufactured by ADEKA Co., Ltd.), etc.

[0079] In one embodiment, the ultraviolet absorber described above uses a compound having a triazine structure with three benzene rings bonded to it, and the total number of highly electronegative atoms directly bonded to these three benzene rings is less than six. By using this compound, an adhesive sheet exhibiting excellent peelability can be obtained after laser irradiation following a wide range of ultraviolet (e.g., ultraviolet light with wavelengths of 350 nm to 380 nm) irradiation. 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. This compound is less likely to shield the wavelength of ultraviolet light used in curing, making it suitable as an ultraviolet absorber used in this invention. For example, BASF's trade name "TINUVIN 400" can be cited as an example of such a compound.

[0080] The aforementioned ultraviolet absorbers can be dyes or pigments. Examples of pigments include azo, phthalocyanine, anthraquinone, lake, pyrene, violet ketone, quinacridone, thioindigo, dioxazine, isoindolineone, and quinophthalone pigments. Examples of dyes include azo, phthalocyanine, anthraquinone, carbonyl, indigo, quinone imine, methynyl, quinoline, and nitro dyes.

[0081] The molecular weight of the compound constituting the aforementioned ultraviolet absorber is preferably 100–1500, more preferably 200–1200, and even more preferably 200–1000. If it is within this range, an adhesive sheet capable of forming a better deformable portion can be obtained by laser irradiation.

[0082] In one embodiment, the maximum absorption wavelength of the aforementioned ultraviolet absorber is preferably 350 nm or less, more preferably 340 nm or less. Using such an ultraviolet absorber, which absorbs ultraviolet light, results in an adhesive sheet exhibiting good peelability and excellent stability under normal conditions.

[0083] The proportion of the aforementioned ultraviolet absorber relative to 100 parts by weight of the base polymer in the adhesive layer is preferably 1 to 50 parts by weight, more preferably 5 to 20 parts by weight. If it is within this range, the overall adhesive strength of the adhesive layer is well reduced by irradiation with active energy rays, the curing of the adhesive layer is well promoted, and an adhesive sheet exhibiting good peelability can be obtained by laser irradiation.

[0084] C. Substrate

[0085] The aforementioned substrate can be composed of any suitable resin. Examples of such resins include polyethylene-based resins, polypropylene-based resins, polybutene-based resins, polymethylpentene-based resins, polyolefin-based resins, polyurethane-based resins, polyester-based resins, polyimide-based resins, polyetherketone-based resins, polystyrene-based resins, polyvinyl chloride-based resins, polyvinylidene chloride-based resins, fluorine-based resins, silicone-based resins, cellulose-based resins, and ionomer resins. Among these, polyolefin-based resins are preferred.

[0086] The thickness of the above-mentioned substrate is preferably 2μm to 300μm, more preferably 2μm to 100μm, and even more preferably 2μm to 50μm.

[0087] The transmittance of the substrate at a wavelength of 355 nm is preferably 70% or more, more preferably 80% or more, further preferably 90% or more, and particularly preferably 95% or more. The upper limit of the transmittance of the substrate at 355 nm is, for example, 98% (preferably 99%).

[0088] D. Other adhesive layers

[0089] As the adhesive constituting the other adhesive layers described above, any suitable adhesive can be used as long as the effects of the present invention are achieved. Examples of such adhesives include acrylic adhesives, silicone adhesives, vinyl alkyl ether adhesives, polyester adhesives, polyamide adhesives, urethane adhesives, fluorinated adhesives, styrene-diene block copolymer adhesives, and active energy radiation-cured adhesives. Among these, acrylic adhesives, rubber adhesives, or silicone adhesives are preferred, and acrylic adhesives are more preferred.

[0090] When the other adhesive layers of the above-mentioned adhesive sheet are attached to the polyethylene terephthalate film, the adhesion at 23°C is preferably 0.01N / 20mm to 15N / 20mm, more preferably 0.05N / 20mm to 10N / 20mm.

[0091] The transmittance of the other adhesive layers at a wavelength of 355 nm is preferably 70% or more, more preferably 80% or more, further preferably 90% or more, and particularly preferably 95% or more. The upper limit of the transmittance of the other adhesive layers at a wavelength of 355 nm is, for example, 98% (preferably 99%).

[0092] E. Method for manufacturing adhesive sheets

[0093] The aforementioned adhesive sheet can be manufactured by any suitable method. For example, the adhesive sheet can be obtained by coating the adhesive onto a substrate or release liner. Various coating methods can be employed, such as bar coating, air knife coating, gravure coating, reverse gravure coating, reverse roller coating, lip coating, die coating, dip coating, offset printing, flexographic printing, and screen printing. Alternatively, a method can be used where an adhesive layer is formed on the release liner and then bonded to the substrate.

[0094] F. Instructions for using adhesive pads (methods for handling electronic components)

[0095] The adhesive sheet of the present invention can be used for processing any suitable workpiece (e.g., electronic component) and for temporarily fixing the workpiece. Taking the processing method of an electronic component as an example, the method of using the adhesive sheet of the present invention will be described. The aforementioned processing method of the electronic component can be exemplified by using a method in the following manner: (i) attaching and fixing the electronic component to the adhesive layer of the adhesive sheet, (ii) processing the electronic component, (iii) irradiating the entire adhesive layer of the adhesive sheet with active energy rays (e.g., ultraviolet light) to reduce the adhesive force of the adhesive sheet, and (iv) irradiating the area where peelability is desired with a laser to peel off the electronic component. According to this method, the electronic component can be peeled off by allowing it to fall naturally. Furthermore, in the case of temporarily fixing multiple electronic components, only a portion can be peeled off. Using the adhesive sheet of the present invention, the adhesive force can be reduced to the point of falling naturally, allowing even very small electronic components (e.g., 50 μm square) to be peeled off individually and independently.

[0096] The removal of the aforementioned electronic components can be performed selectively at different locations. Specifically, multiple electronic components are attached to and secured to an adhesive sheet, and a portion of the electronic components can be removed while keeping the other electronic components secured.

[0097] In one embodiment, the method for processing the electronic component of the present invention includes the following operations: after attaching the electronic component to the adhesive sheet and before peeling the electronic component off the adhesive sheet, performing a prescribed treatment on the electronic component. The above treatment is not particularly limited, and examples include grinding, cutting, chip bonding, wire bonding, etching, vapor deposition, molding, circuit forming, inspection, product inspection, cleaning, transfer printing, alignment, repair, and protection of device surfaces.

[0098] The dimensions (area of ​​the attachment surface) of the aforementioned electronic components are, for example, 1 μm. 2 ~250000μm 2 In one embodiment, the size (area of ​​the attachment surface) of the electronic component is 1 μm. 2 ~6400μm 2 The electronic components can be processed. In another embodiment, the size (area of ​​the attachment surface) of the electronic component is 1 μm. 2 ~2500μm 2 The electronic components can be processed.

[0099] In one embodiment, as described above, multiple electronic components can be arranged on the adhesive sheet. The spacing between the electronic components is, for example, 1 μm to 500 μm. In this invention, reducing the spacing and temporarily fixing the workpiece is advantageous.

[0100] As a laser, for example, a UV laser can be used. The irradiation power of the laser is, for example, 1 μJ to 1000 μJ. The wavelength of the UV laser is, for example, 240 nm to 380 nm.

[0101] In one embodiment, the method for processing the electronic component includes the following steps: after peeling off the electronic component, the electronic component is placed on other sheets (e.g., adhesive sheets, substrates, etc.).

[0102] Example

[0103] The present invention will now be specifically described with reference to embodiments, but the present invention is not limited to these embodiments. The testing and evaluation methods in the embodiments are as described below. In addition, unless otherwise specified, "parts" and "%" are based on weight.

[0104] (1) Initial adhesion (adhesive layer), adhesion of other adhesive layers

[0105] The adhesive layer of the adhesive sheet was attached to SUS430, and the initial adhesive force of the adhesive sheet was measured according to the method of JIS Z 0237:2000 (bonding conditions: 2 kg roller reciprocating once, tensile speed: 300 mm / min, peel angle 180°, test temperature: 23°C). It should be noted that when the initial adhesive force is 2 N / 20 mm or more, the receptivity (transferability) during the transfer of the adhered object is significantly excellent (〇 in the table); when it is 0.5 N / 20 mm or more but less than 2 N / 20 mm, the receptivity (transferability) during the transfer of the adhered object is good (△ in the table); when it is less than 0.5 N / 20 mm, the receptivity (transferability) during the transfer of the adhered object is evaluated as insufficient (× in the table).

[0106] In addition, the adhesive layer of the adhesive sheet was adhered to and fixed to a support such as a stainless steel plate, and other adhesive layers were attached to a polyethylene terephthalate film (manufactured by Toray Industries, Inc., trade name "Lumirror S10", thickness: 25μm). The adhesion strength of the other adhesive layers was measured according to the method of JIS Z 0237:2000 (bonding conditions: 2kg roller reciprocating once, stretching speed: 300mm / min, peel angle 180°, measurement temperature: 23℃).

[0107] (2) Adhesive strength after ultraviolet irradiation

[0108] The adhesive layer of the adhesive sheet is attached to SUS430. The entire surface of this adhesive layer is then irradiated with ultraviolet light from a high-pressure mercury lamp using an ultraviolet irradiation device (Nitto Seiki, trade name "UM-810"). (Specific wavelength: 365nm, cumulative light intensity: 460mJ / cm²) 2It should be noted that when the adhesive strength after UV irradiation is below 0.5 N / 20 mm, the peelability is significantly excellent (〇 in the table); when it is above 0.5 N / 20 mm but below 2 N / 20 mm, the transferability is good (△ in the table); when it is above 2 N / 20 mm, the peelability is not adequate (× in the table).

[0109] (3) Light transmittance

[0110] The adhesive sheet was mounted on a spectrophotometer (trade name "UV-VIS Ultraviolet-Vis Spectrophotometer SolidSpec3700", manufactured by Shimadzu Corporation). Transmittance in the wavelength range of 300 nm to 800 nm was measured by perpendicularly illuminating the adhesive layer side of the sample. The transmittance at wavelengths of 360 nm, 380 nm, and 500 nm was extracted from the obtained transmission spectrum.

[0111] (4) Surface shape changes of adhesive sheets

[0112] For the entire adhesive layer of the adhesive sheet, a high-pressure mercury lamp was used to irradiate the entire adhesive layer with ultraviolet light (specific wavelength: 365nm, cumulative light intensity: 460mJ / cm²) using an ultraviolet irradiation device (Nitto Seiki, trade name "UM-810"). 2 The sample is then placed on the entire surface. Next, a glass plate (Matsunami Glass Co., Ltd., large glass slide S9112 (standard large white edge grinder No. 2)) is bonded to the adhesive layer to obtain the measurement sample. A wavelength of 355 nm and a beam diameter of approximately [missing information] are used. A UV laser was used to pulse and scan the glass plate side of the sample at a power of 0.80 mW and a frequency of 40 kHz, generating gas from the adhesive layer. The shape changes on the surface of the adhesive sheet produced by this operation were observed.

[0113] (5) Haze value

[0114] The haze value of the adhesive sheet was measured using a haze meter (trade name "HAZE METER HM-150", manufactured by Murakami Color Technology Research Institute).

[0115] (6) 10% temperature of weight loss

[0116] For ultraviolet absorbers, the 10% weight loss temperature is measured.

[0117] Using a differential thermal analysis apparatus (TA Instruments, trade name "Discovery TGA"), for the adhesive sheet, the temperature was measured at a heating rate of 10°C / min, under a N2 atmosphere, a flow rate of 25 ml / min, and a 10% weight reduction.

[0118] [Manufacturing Example 1] Manufacturing of Acrylic Polymer I

[0119] In toluene, 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. The polymerization reaction was carried out under a nitrogen atmosphere at 60°C. Then, 13.5 parts by weight of methacryloxyethyl isocyanate were added to the mixture for an addition reaction, thereby obtaining a toluene solution of an acrylic copolymer (acrylic polymer I) with carbon-carbon double bonds.

[0120] [Manufacturing Example 2] Manufacturing of Acrylic Polymer II

[0121] In toluene, 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, and the mixture was heated to 70°C to obtain a toluene solution of acrylic copolymer (acrylic polymer II).

[0122] [Manufacturing Example 3] Manufacturing of acrylic polymer a

[0123] In ethyl acetate, 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, and the mixture was heated to 70°C to obtain an ethyl acetate solution of an acrylic copolymer (acrylic polymer a).

[0124] [Manufacturing Example 4] Manufacturing of acrylic polymer b

[0125] In toluene, 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, and the mixture was heated to 70°C to obtain a toluene solution of an acrylic copolymer (acrylic polymer b).

[0126] [Example 1]

[0127] (Preparation of adhesive (1))

[0128] In an acrylic polymer solution I containing 100 parts by weight of acrylic polymer I, 0.2 parts by weight of a crosslinking agent (manufactured by Nippon Polyurethane Kogyo Co., Ltd., trade name "CORONATE L") and an α-hydroxyketone photopolymerization initiator (manufactured by BASF JAPAN, trade name "IRGACURE 127", molecular weight: 340.4, absorbance coefficient at 365 nm: 1.07 × 10⁻⁶) were added. 23 parts by weight of hydroxyphenyl triazine ultraviolet absorber (manufactured by BASF JAPAN, trade name "Tinuvin 400", molecular weight: 647.8, 10% loss temperature: 391.7℃, maximum absorption wavelength: 336nm) were added to obtain adhesive (1).

[0129] (Preparation of adhesive (2))

[0130] In an ethyl acetate solution containing 100 parts by weight of acrylic polymer a, 2 parts by weight of a crosslinking agent (manufactured by Mitsubishi Gas Chemical Co., Ltd., trade name "TETRAD C") were added to obtain an adhesive (2).

[0131] (Adhesive sheet)

[0132] On one side of a polyethylene terephthalate film (thickness: 50 μm), an adhesive (1) is applied so that the thickness after solvent evaporation (drying) is 10 μm, forming an adhesive layer. On the other side, an adhesive (2) is applied so that the thickness after solvent evaporation (drying) is 10 μm, forming other adhesive layers, resulting in an adhesive sheet.

[0133] The resulting adhesive sheets were used for the evaluations described above (1) to (6). The results are shown in Table 1.

[0134] [Examples 2-13, Comparative Examples 1-7]

[0135] The types of acrylic polymers, the amount of crosslinking agents, the types / amounts of photopolymerization initiators, the types / amounts of ultraviolet absorbers, and the thickness of the adhesive layer were as described in Tables 1 and 2, except that adhesive sheets were obtained in the same manner as in Example 1. The obtained adhesive sheets were subjected to the above evaluations (1) to (6). The results are shown in Table 1 or Table 2. It should be noted that in Comparative Example 1, 20 parts by weight of a surfactant (manufactured by Kao Corporation, trade name "Exepearl IPP") were also added to the adhesive. In Example 13, the adhesive (curing type adhesive) was applied only to one side. In Comparative Example 4, 10 parts by weight of a terpene phenolic tackifying resin (manufactured by Yasuhara Chemical Co., Ltd., trade name "YS Polystar S145") were also added to the adhesive.

[0136] The contents of the materials recorded in Table 1 are as follows.

[0137] "Irg651": Manufactured by BASF JAPAN Co., Ltd., trade name "Irgacure 651", molecular weight: 256.3, absorbance coefficient at 365nm: 3.613×10 2 ml / g·cm

[0138] "Tinuvin477": Manufactured by BASF JAPAN, trade name "Tinuvin 477", molecular weight: 958.2, 10% weight loss temperature: 352.8℃, maximum absorption wavelength: 356nm

[0139] [Table 1]

[0140]

[0141] [Table 2]

[0142]

[0143] Explanation of reference numerals in the attached figures

[0144] 10 Adhesive Layer

[0145] 20 Substrate

[0146] 100, 100' adhesive sheet

Claims

1. An adhesive sheet comprising: an adhesive layer containing a curable adhesive by active energy rays, the adhesive sheet has a light transmittance of 0 to 35% at a wavelength of 360 nm, the adhesive sheet has a light transmittance of 10 to 100% at a wavelength of 380 nm, the adhesive layer contains an ultraviolet absorber, the ultraviolet absorber is a triazine-based ultraviolet absorber or a benzotriazole-based ultraviolet absorber, and the ultraviolet absorber has a maximum absorption wavelength of 350 nm or less, the ultraviolet absorber generates gas upon irradiation of laser light at a wavelength of 355 nm.

2. The adhesive sheet according to claim 1, wherein the initial adhesive force at 23°C when the adhesive layer of the adhesive sheet is attached to a stainless steel plate is 0.3 N / 20 mm to 15 N / 20 mm.

3. The adhesive sheet according to claim 1 or 2, wherein The adhesive layer of the adhesive sheet was attached to a stainless steel plate, and the adhesion at 23°C after irradiation of 460 mJ / cm2of ultraviolet rays was 0.01 N / 20 mm to 2.4 N / 20 mm. 2 The adhesion at 23°C after irradiation of 460 mJ / cm2of ultraviolet rays was 0.01 N / 20 mm to 2.4 N / 20 mm.

4. The adhesive sheet according to claim 1 or 2, wherein The adhesive layer of the adhesive sheet is attached to a stainless steel plate and irradiated with 460 mJ / cm. 2 The adhesive strength at 23°C after exposure to ultraviolet light is less than 50% of the initial adhesive strength.

5. The adhesive sheet according to claim 1 or 2, which has a light transmittance of 70 to 100% at a wavelength of 500 nm.

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

7. The adhesive sheet according to claim 1 or 2, wherein the triazine-based ultraviolet absorber is a compound having a structure in which three benzene rings are bonded in a triazine structure, and the total number of high-electronegativity atoms directly bonded to the three benzene rings is less than 6.

8. The adhesive sheet according to claim 1 or 2, wherein the adhesive layer contains a photopolymerization initiator, the photopolymerization initiator has an absorbance coefficient of 10 ml / g-cm to 10,000 ml / g-cm at a wavelength of 365 nm.

9. The adhesive sheet according to claim 1 or 2, wherein the adhesive layer contains a photopolymerization initiator, the photopolymerization initiator has an absorbance coefficient of 10 ml / g-cm or less at a wavelength of 405 nm.

10. The adhesive sheet according to claim 1 or 2, wherein the adhesive layer is cured by irradiation of ultraviolet light having a wavelength of 350 nm or more and 380 nm or less.

11. The adhesive sheet according to claim 1 or 2, wherein the thickness of the adhesive layer is 0.1 μm to 50 μm.

12. The adhesive sheet according to claim 1 or 2, wherein the surface of the adhesive sheet is deformed by laser irradiation.

13. The adhesive sheet according to claim 12, wherein the surface of the adhesive sheet is deformed into a convex shape by laser irradiation.

14. The adhesive sheet according to claim 12, wherein the surface of the adhesive sheet is deformed into a concave shape by laser irradiation.

15. A processing method of an electronic component, comprising the steps of: attaching an electronic component on an adherend and fixing it to the adhesive sheet according to any one of claims 1 to 14, processing the electronic component, irradiating active energy rays to the entire adhesive layer of the adhesive sheet to reduce the adhesive force of the adhesive sheet, and then irradiating laser light to a site where peeling is desired to be performed to peel the electronic component.

16. The electronic parts processing method according to claim 15, wherein the peeling of the electronic component is performed position-selectively.

17. The electronic component processing method according to claim 15 or 16, wherein the processing is polishing, cutting, die bonding, wire bonding, etching, vapor deposition, molding, circuit formation, inspection, product inspection, cleaning, transfer, arrangement, repair, or protection of a device surface.

18. The processing method of an electronic component according to claim 17, comprising the step of arranging the electronic component on another sheet after peeling the electronic component from the adhesive sheet.

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