Pressure-sensitive adhesive

Abstract

To provide a pressure-sensitive adhesive sheet which is used in an electronic component transfer process, exhibits peelability by irradiation with a laser beam having a predetermined wavelength, and can prevent an adhesive from remaining when peeled.SOLUTION: 1. A pressure-sensitive adhesive sheet according to an embodiment of the present invention includes a pressure-sensitive adhesive layer, and the pressure-sensitive adhesive layer has a light transmission of 70% or more at 248nm wavelengths. 2. In the PSA sheet according to 1 above, the PSA layer may have a thickness of 10 μm or less. 3. In the pressure-sensitive adhesive sheet according to the item 1 or 2, the pressure-sensitive adhesive layer may contain an active energy ray-curable pressure-sensitive adhesive.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an adhesive sheet, and more particularly to an adhesive sheet used in an electronic component transfer process. [Background technology]

[0002] Conventionally, when transferring electronic components, i.e., when transferring electronic components arranged on a predetermined component to another component, the electronic components are received with an adhesive sheet and then transferred to the other component. For example, when incorporating LED chips into a device, the LED chips formed on the component are first transferred onto an adhesive sheet supported by a predetermined transport carrier, and then transferred from the adhesive sheet to a predetermined device or component, thereby transferring the LED chips. The adhesive sheets used in such processes are required to exhibit releasability when transferring the electronic components.

[0003] In recent years, laser light irradiation has been used in some cases to develop releasability when electronic components are transferred, and in such cases, the pressure-sensitive adhesive sheet is required to develop releasability according to the wavelength of the laser light. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 5875850 [Patent Document 2] Patent No. 6053756 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 to be used in the electronic component transfer process, which exhibits releasability when irradiated with laser light of a specified wavelength and can prevent adhesive residue when peeled off. [Means for solving the problem]

[0006] 1. A pressure-sensitive adhesive sheet according to an embodiment of the present invention includes a pressure-sensitive adhesive layer, and the pressure-sensitive adhesive layer has a light transmittance of 70% or more at a wavelength of 248 nm. 2. In the pressure-sensitive adhesive sheet described in 1 above, the pressure-sensitive adhesive layer may have a thickness of 10 μm or less. 3. In the pressure-sensitive adhesive sheet according to 1 or 2 above, the pressure-sensitive adhesive layer may contain an active energy ray-curable pressure-sensitive adhesive. 4. In the pressure-sensitive adhesive sheet described in 3 above, the active energy ray-curable pressure-sensitive adhesive may contain a base polymer having an acryloyl group. 5. According to another aspect of the present invention, there is provided a method for transferring electronic components, which method uses the pressure-sensitive adhesive sheet according to any one of 1 to 4 above. 6. The method for transferring electronic components described in 5 above includes a first step of transferring a plurality of electronic components arranged on a substrate onto an adhesive layer of the adhesive sheet; and a second step of transferring the electronic components on the adhesive sheet to another member, and the second step may include irradiating the adhesive sheet with laser light. 7. In the method for transferring electronic components as described in 5 or 6 above, the wavelength of the laser light may be 200 nm to 300 nm. 8. The method for transferring electronic components according to any one of the above items 5 to 7, wherein the amount of irradiation of the laser light is 150 mJ / cm 2 ~500mJ / cm 2 may be. 9. In the method for transferring an electronic component described in any one of items 5 to 8 above, the electronic component may be a mini LED or a micro LED. 10. In the method for transferring electronic components according to any one of the above items 5 to 9, the laser light may be an excimer laser. [Effects of the Invention]

[0007] According to the present invention, it is possible to provide an adhesive sheet used in an electronic component transfer process, which exhibits releasability when irradiated with laser light of a predetermined wavelength and can prevent adhesive residue when peeled off. [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. Pressure-sensitive adhesive sheet 100 according to this embodiment includes a pressure-sensitive adhesive layer 10. FIG. 1(b) is a schematic cross-sectional view of a pressure-sensitive adhesive sheet according to one embodiment of the present invention. Pressure-sensitive adhesive sheet 200 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 layer as long as the effects of the present invention are achieved. In addition, in the present invention, as described below, the generation of strain in the pressure-sensitive adhesive layer enables satisfactory release of the adherend, so it is possible to construct a pressure-sensitive adhesive sheet without providing a layer other than the pressure-sensitive adhesive layer (a so-called separation layer) for separating the adherend from the pressure-sensitive adhesive sheet. The above pressure-sensitive adhesive sheet is used in an electronic component transfer process. For example, the adhesive sheet can be used for receiving electronic components (e.g., receiving electronic components by a laser lift-off process) and transferring electronic components, including subsequent peeling of the electronic components by laser light irradiation. Examples of electronic components include mini LEDs, micro LEDs, and the like.

[0010] In one embodiment, the pressure-sensitive adhesive sheet does not include a substrate. 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). Pressure-sensitive adhesive sheets composed without a substrate are preferred in that they have excellent energy utilization efficiency when peeling an adherend by laser light irradiation. In another embodiment, the pressure-sensitive adhesive sheet of the present invention is composed of a substrate and a pressure-sensitive adhesive layer, as shown in FIG. 1(b), and the pressure-sensitive adhesive layer is disposed directly on the substrate (i.e., without any other layer interposed therebetween).

[0011] In one embodiment, the pressure-sensitive adhesive sheet can be used by transferring a plurality of electronic components (e.g., LED chips) arranged on a substrate (e.g., a hard substrate such as a sapphire substrate) to the pressure-sensitive adhesive sheet by any appropriate method (e.g., laser lift-off), and then transferring the electronic components on the pressure-sensitive adhesive sheet to another member. Transfer from the pressure-sensitive adhesive sheet to another member can be achieved by irradiating with laser light. In the present invention, irradiation with laser light of a predetermined wavelength (e.g., 248 nm) generates strain in the pressure-sensitive adhesive layer, resulting in the development of releasability in the area irradiated with the laser light. In one embodiment, heat generated in the pressure-sensitive adhesive layer by laser light irradiation can cause strain in the pressure-sensitive adhesive layer. According to the present invention, strain can be generated in a small area in the pressure-sensitive adhesive layer as described above, allowing for satisfactory release of small electronic components (e.g., 50 μm square) even when processing the electronic components. Use of such a pressure-sensitive adhesive sheet can eliminate the need for cleaning the electronic components after release. Furthermore, even when a small electronic component that needs to be peeled and a small electronic component that does not need to be peeled are temporarily fixed next to each other, only the small electronic component that needs to be peeled can be peeled off, thereby preventing unnecessary detachment of the small electronic component.

[0012] In one embodiment, the light transmittance of the pressure-sensitive adhesive sheet at a wavelength of 248 nm is 70% or more, preferably 75% or more, more preferably 80% or more, even more preferably 85% or more, and particularly preferably 90% or more. In one embodiment, the light transmittance of the pressure-sensitive adhesive sheet at a wavelength of 248 nm can be less than 100%, 99.5% or less, 99% or less, 98% or less, 97% or less, 96% or less, or 95% or less.

[0013] The visible light transmittance of the pressure-sensitive adhesive sheet is preferably 50% or more, more preferably 60% or more, and even more preferably 70% or more. 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 the adherend is peeled off by laser light irradiation. The higher the visible light transmittance of the pressure-sensitive adhesive sheet, the better, but the upper limit is, for example, 95% (preferably 100%).

[0014] The haze value of the pressure-sensitive adhesive sheet is preferably 70% or less, more preferably 65% ​​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%.

[0015] The initial adhesive strength A at 23°C immediately after the adhesive sheet is applied to the stainless steel plate is preferably 0.1 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 capable of holding an adherend well can be obtained. The adhesive strength is measured in accordance with JIS Z 0237:2000. Specifically, the adhesive sheet is applied to a stainless steel plate (arithmetic mean surface roughness Ra: 50±25 nm) using a 2 kg roller in one stroke, and then left at 23°C for 30 minutes. After this, the adhesive sheet is peeled off at a peel angle of 180° and a peel rate (pulling speed) of 300 mm / min. The adhesive strength of the adhesive layer changes upon irradiation with active energy rays and laser light. In this specification, "initial adhesive strength" refers to the adhesive strength before irradiation with active energy rays and laser light.

[0016] In one embodiment, the pressure-sensitive adhesive sheet is attached to a stainless steel plate, and 460 mJ / cm 2 The adhesive strength B at 23°C after irradiation with ultraviolet light (also referred to as adhesive strength B after curing) is preferably 0.2 N / 20 mm or less, more preferably 0.01 N / 20 mm to 0.2 N / 20 mm, and more preferably 0.02 N / 20 mm to 0.15 N / 20 mm. If the adhesive strength is within this range, an adhesive sheet with little adhesive residue 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"), using ultraviolet light from a high-pressure mercury lamp (characteristic wavelength: 365 nm, cumulative light amount: 460 mJ / cm). 2 ) is irradiated onto the adhesive layer.

[0017] The reduction rate of the post-curing adhesive strength B relative to the initial adhesive strength A is preferably 90% or more, more preferably 95% or more. Within this range, a pressure-sensitive adhesive sheet with excellent releasability can be obtained. The reduction rate (%) can be calculated using the formula: (initial adhesive strength A - post-curing adhesive strength B) / initial adhesive strength A x 100.

[0018] The thickness of the pressure-sensitive adhesive sheet is preferably 1 μm to 300 μm, and more preferably 5 μm to 200 μm.

[0019] B.Adhesive layer The pressure-sensitive adhesive layer has a light transmittance of 70% or more at a wavelength of 248 nm. Within this range, a pressure-sensitive adhesive layer can be formed that is strained by a short wavelength laser beam and exhibits favorable releasability.

[0020] In the present invention, since the optical transmittance of the pressure-sensitive adhesive layer at a wavelength of 248 nm is within the above range, a pressure-sensitive adhesive sheet can be obtained that can prevent adhesive residue on an adherend (e.g., electronic components such as LED chips) during peeling by irradiation with a low-wavelength (e.g., 240 nm to 260 nm) laser beam by simply adjusting process conditions (e.g., laser beam irradiation dose). Use of the pressure-sensitive adhesive sheet makes it possible to omit the cleaning step after the peeling operation, thereby reducing production costs. Furthermore, because the pressure-sensitive adhesive sheet exhibits releasability with a low-power laser beam, use of the pressure-sensitive adhesive sheet can reduce damage to the adherend (electronic components) during peeling, preventing breakage of the electronic components. The optical transmittance of the pressure-sensitive adhesive sheet at a wavelength of 248 nm can be controlled, for example, by the composition of the base polymer and photopolymerization initiator that constitute the pressure-sensitive adhesive layer. For example, the optical transmittance can be controlled by the type and amount of the photopolymerization initiator contained in the pressure-sensitive adhesive layer.

[0021] The pressure-sensitive adhesive layer preferably has a light transmittance of 75% or more at a wavelength of 248 nm, more preferably 80% or more, even more preferably 85% or more, and particularly preferably 90% or more. Within such a range, the above-mentioned effects become significant.

[0022] In one embodiment, the pressure-sensitive adhesive layer has a light transmittance at a wavelength of 248 nm of less than 100%, 99.5% or less, 99% or less, 98% or less, 97% or less, 96% or less, or 95% or less. Within such a range, a pressure-sensitive adhesive layer capable of exhibiting favorable releasability due to distortion caused by a low-wavelength laser beam can be formed.

[0023] The thickness of the pressure-sensitive adhesive layer is preferably 45 μm or less. Within this range, the light transmittance can be suitably adjusted, making it possible to obtain a pressure-sensitive adhesive sheet that is particularly excellent in preventing adhesive transfer. Furthermore, it is possible to further reduce the laser output during peeling, making it possible to obtain a pressure-sensitive adhesive sheet that is excellent in peeling properties. The thickness of the pressure-sensitive adhesive layer is more preferably 20 μm or less, even more preferably 15 μm or less, particularly preferably 10 μm or less, and most preferably 1 μm to 10 μm. Within this range, the above effects become more pronounced.

[0024] The pressure-sensitive adhesive layer includes any appropriate pressure-sensitive adhesive. In one embodiment, the pressure-sensitive adhesive layer includes an active energy ray-curable pressure-sensitive adhesive as the pressure-sensitive adhesive. The pressure-sensitive adhesive includes a base polymer. In one embodiment, the pressure-sensitive adhesive does not include an ultraviolet absorber (e.g., a benzotriazole-based ultraviolet absorber, a benzophenone-based ultraviolet absorber, a triazine-based ultraviolet absorber, a salicylate-based ultraviolet absorber, a cyanoacrylate-based ultraviolet absorber, etc.). By not using an ultraviolet absorber, the light transmittance can be preferably adjusted, and a pressure-sensitive adhesive sheet with particularly excellent adhesive transfer prevention effect can be obtained.

[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, a carboxyl group, and an acryloyl 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, 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.

[0033] 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.

[0034] 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.

[0035] In one embodiment, the base polymer is a base polymer having an acryloyl group. Use of such a base polymer makes it possible to form a pressure-sensitive adhesive layer with a suitably adjusted light transmittance at a wavelength of 248 nm.

[0036] In the base polymer, the content of the structural unit having an acryloyl group is preferably 1 to 1000 parts by weight, more preferably 10 to 300 parts by weight, and even more preferably 100 to 200 parts by weight, relative to 100 parts by weight of the base polymer.Within such a range, the above-mentioned effects become prominent.

[0037] 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 (precursor resin). A method for introducing a radiation-polymerizable carbon-carbon double bond into the acrylic polymer (precursor resin) includes, for example, copolymerizing raw material monomers including a monomer having a predetermined functional group (first functional group) to obtain an acrylic polymer (precursor resin), 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 (hereinafter simply referred to as a compound having a carbon double bond) to a condensation reaction or addition reaction with the acrylic polymer while maintaining the radiation polymerizability of the carbon-carbon double bond.

[0038] The amount of the compound having a carbon double bond introduced is preferably 10 parts by weight or more, more preferably 12 parts by weight or more, and even more preferably 15 parts by weight or more, per 100 parts by weight of the solid content of the acrylic polymer (precursor resin). Within this range, a pressure-sensitive adhesive layer with a favorably adjusted light transmittance at a wavelength of 248 nm can be formed. Furthermore, a low-polarity active energy ray-reactive polymer (base polymer) can be obtained. Use of this base polymer allows favorable adherend peeling by low-energy laser light irradiation, even in a pressure-sensitive adhesive layer with a relatively low elastic modulus after ultraviolet irradiation. The upper limit of the amount of the compound having a carbon double bond introduced is, for example, 80 parts by weight (preferably 60 parts by weight, more preferably 50 parts by weight) per 100 parts by weight of the solid content of the acrylic polymer (precursor resin).

[0039] 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.

[0040] The pressure-sensitive adhesive (A2) may further contain the active energy ray-reactive compound (monomer or oligomer).

[0041] The active energy ray-curable pressure-sensitive adhesive may contain a photopolymerization initiator.

[0042] 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.

[0043] In one embodiment, the photopolymerization initiator used has two or more (preferably 2 to 5) photodegradable groups. Examples of photopolymerization initiators having two or more photodegradable groups include 2-hydroxy-1-[4-[4-(2-hydroxy-2-methyl-propionyl)-benzyl]phenyl]-2-methyl-propan-1-one (trade name Omnirad127, manufactured by BASF Japan), 1-[4-(4-benzoylphenylsulfanyl)phenyl]-2-methyl-2-(4-methylphenylsulfonyl)propan-1-one (trade name ESURE1001M), methyl benzoyl formate (trade name SPEEDCURE MBF, manufactured by LAMBSON), O-ethoxyimino-1-phenylpropan-1-one (trade name SPEEDCURE PDO, manufactured by LAMBSON), and oligo[2-hydroxy-2-methyl-4-(1-methylvinyl)phenyl]propanone (trade name ESCURE KIPI50, manufactured by LAMBERTI).

[0044] The content of the photopolymerization initiator is preferably 1 to 30 parts by weight, more preferably 2 to 20 parts by weight, and even more preferably 3 to 15 parts by weight, relative to 100 parts by weight of the base polymer in the pressure-sensitive adhesive layer. Within such a range, when the adhesive strength of the entire pressure-sensitive adhesive layer is satisfactorily reduced by irradiation with active energy rays, the pressure-sensitive adhesive layer is cured satisfactorily, and the amount of distortion of the pressure-sensitive adhesive layer due to laser light irradiation is large, making it possible to obtain a pressure-sensitive adhesive sheet that exhibits good releasability.

[0045] In one embodiment, the active energy ray-curable pressure-sensitive adhesive may contain a photosensitizer.

[0046] In one embodiment, the photosensitizer can be used in combination with the photopolymerization initiator. The photosensitizer can transfer the energy it obtains by absorbing light to the photopolymerization initiator, thereby generating radicals from the photopolymerization initiator. This allows polymerization to proceed with light on the long wavelength side, where the photopolymerization initiator itself does not have an absorption peak. Therefore, by incorporating a photosensitizer, it is possible to increase the difference between the absorption wavelength of the UV absorber and the wavelength at which radicals can be generated from the photopolymerization initiator. As a result, photopolymerization of the pressure-sensitive adhesive layer and peeling by the UV absorber can be performed without affecting each other. In one embodiment, 2,2-dimethoxy-1,2-diphenylethan-1-one (e.g., BASF, trade name "Irgacure 651") as a photopolymerization initiator and a photosensitizer are used in combination. Examples of such photosensitizers include "UVS-581" (trade name, manufactured by Kawasaki Chemical Industries, Ltd.) and 9,10-diethoxyanthracene (e.g., "UVS1101" (trade name, manufactured by Kawasaki Chemical Industries, Ltd.). Other examples of the photosensitizers include 9,10-dibutoxyanthracene (e.g., "UVS-1331" (trade name, manufactured by Kawasaki Chemical Industries, Ltd.), 2-isopropylthioxanthone, benzophenone, thioxanthone derivatives, 4,4'-bis(dimethylamino)benzophenone, etc. Examples of thioxanthone derivatives include ethoxycarbonylthioxanthone, isopropylthioxanthone, etc.

[0047] The content of the photosensitizer is preferably 0.01 to 2 parts by weight, and more preferably 0.5 to 2 parts by weight, relative to 100 parts by weight of the base polymer.

[0048] 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.

[0049] 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.

[0050] 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.

[0051] 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.

[0052] 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.

[0053] 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.

[0054] In one embodiment, the substrate has a light transmittance at a wavelength of 248 nm of 70% or more, preferably 75% or more, more preferably 80% or more, even more preferably 85% or more, and particularly preferably 90% or more. In one embodiment, the substrate has a light transmittance at a wavelength of 248 nm of less than 100%, 99.5% or less, 99% or less, 98% or less, 97% or less, 96% or less, or 95% or less.

[0055] D. 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 PSA layer can be formed on a separate release liner, which can then be laminated to the substrate.

[0056] E. Electronic component transfer method In one embodiment, a method for transferring electronic components using the pressure-sensitive adhesive sheet is provided. The method includes, for example, a first step of transferring a plurality of electronic components arranged on a substrate onto the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet; and a second step of transferring the electronic components on the pressure-sensitive adhesive sheet to another member. Preferably, the same pressure-sensitive adhesive sheet is used in the first and second steps. That is, the method can transfer the electronic components without including any additional transfer steps.

[0057] In one embodiment, the electronic component is a mini LED or a micro LED.

[0058] In the first step, the electronic component can be transferred from the substrate to the adhesive sheet by, for example, a process including irradiating the substrate / electronic component interface with laser light, i.e., a laser lift-off process. The conditions for the laser lift-off process can be any appropriate conditions. For example, a hard substrate such as a sapphire substrate can be used as the substrate. The adhesive sheet can also be used by being attached to any appropriate carrier. The carrier can be made of, for example, glass, quartz glass, or the like.

[0059] In one embodiment, the second step comprises irradiating the pressure-sensitive adhesive sheet with laser light. Specifically, in one embodiment, the second step comprises irradiating the area where releasability is desired with laser light. This laser light irradiation generates strain in the pressure-sensitive adhesive layer, thereby reducing the adhesive strength. According to this method, electronic components can be peeled off only at the area irradiated with laser light. By using the pressure-sensitive adhesive sheet of the present invention, the adhesive strength can be reduced to the point where the electronic components fall off naturally, making it possible to peel off even very small electronic components (e.g., 50 μm square) individually.

[0060] In one embodiment, the second step comprises irradiating the pressure-sensitive adhesive sheet with active energy rays (e.g., ultraviolet rays) to reduce the adhesive strength of the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet. More specifically, the second step may comprise the following operations: (i) irradiating the pressure-sensitive adhesive sheet with active energy rays (e.g., ultraviolet rays) to reduce the adhesive strength of the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet, and (ii) irradiating the area where peelability is desired to be exhibited with laser light to cause distortion in the pressure-sensitive adhesive layer and further reduce the adhesive strength. In this way, the above-mentioned effect becomes more pronounced.

[0061] The wavelength of the laser light in the second step is preferably 200 nm to 300 nm, more preferably 220 nm to 280 nm, even more preferably 230 nm to 270 nm, still more preferably 240 nm to 260 nm, particularly preferably 245 nm to 250 nm, and most preferably 248 nm. By using the pressure-sensitive adhesive sheet, even when using such laser light, it is possible to achieve peelability with little adhesive residue.

[0062] In one embodiment, the laser light is an excimer laser.

[0063] The irradiation dose of the laser light in the second step is preferably 120 mJ / cm 2 ~800mJ / cm 2 and more preferably 130 mJ / cm 2 ~700mJ / cm 2 and more preferably 140 mJ / cm 2 ~600mJ / cm 2 and particularly preferably 150 mJ / cm 2 ~500mJ / cm 2 Within this range, peelability can be achieved with little adhesive residue.

[0064] The active energy rays in (i) above can be irradiated onto the entire surface of the pressure-sensitive adhesive layer. In one embodiment, the active energy rays have an integrated light dose of 100 mJ / cm. 2The active energy ray (preferably ultraviolet light) is irradiated at a dose of 200 mJ / cm or more. Within this range, the peeling operation can be carried out with good workability. Furthermore, adhesive residue can be prevented after the double-sided PSA sheet is peeled in step C. The irradiation dose of the active energy ray (preferably ultraviolet light) is 200 mJ / cm or more. 2 Higher, 1500mJ / cm 2 may be less than 200 mJ / cm 2 ~1500mJ / cm 2 may be 300 mJ / cm 2 ~800mJ / cm 2 may be. [Example]

[0065] 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.

[0066] [Production Example 1] Preparation of Acrylic Polymer I A monomer composition was prepared by mixing 100 parts by weight of 2-ethylhexyl acrylate, 26 parts by weight of acryloylmorpholine, and 19 parts by weight of 2-hydroxyethyl acrylate. Next, nitrogen was introduced into a reaction vessel equipped with a nitrogen inlet tube, a thermometer, and a stirrer, and under a nitrogen atmosphere, 400 parts by weight of ethyl acetate, 132 parts by weight of the monomer composition, and 0.4 parts by weight of benzoyl peroxide (BPO) were charged and stirred for 4 hours at 60° C. Thereafter, the mixture was cooled to room temperature, and 21 parts by weight of 2-methacryloyloxyethyl isocyanate was added and reacted to add NCO groups to the terminal OH groups of the side chains of the 2-hydroxyethyl acrylate in the copolymer, yielding an acrylic polymer solution I containing an acrylic polymer I having a terminal carbon-carbon double bond.

[0067] [Production Example 2] Preparation of Acrylic Polymer II A monomer composition was prepared by mixing 100 parts by weight of isononyl acrylate and 32 parts by weight of 2-hydroxyethyl acrylate. Next, nitrogen was introduced into a reaction vessel equipped with a nitrogen inlet tube, a thermometer, and a stirrer, and under a nitrogen atmosphere, 280 parts by weight of ethyl acetate, 132 parts by weight of the monomer composition, and 0.3 parts by weight of AIBN were charged and stirred for 4 hours at 60° C. Thereafter, the mixture was cooled to room temperature, and 29 parts by weight of 2-methacryloyloxyethyl isocyanate was added and reacted to add NCO groups to the terminal OH groups of the side chains of the 2-hydroxyethyl acrylate in the copolymer, yielding an acrylic polymer solution II containing an acrylic polymer II having a terminal carbon-carbon double bond.

[0068] [Production Example 3] Preparation of acrylic polymer III A monomer composition was prepared by mixing 65 parts by weight of isononyl acrylate, 25 parts by weight of 2-hydroxyethyl acrylate, and 10 parts by weight of an ultraviolet absorber (manufactured by Otsuka Chemical Co., Ltd., trade name "RUVA-93"). Next, nitrogen was introduced into a reaction vessel equipped with a nitrogen inlet tube, a thermometer, and a stirrer, and under a nitrogen atmosphere, 200 parts by weight of ethyl acetate, 100 parts by weight of the monomer composition, and 0.2 parts by weight of AIBN were charged and stirred for 5 hours at 63° C. Thereafter, the mixture was cooled to room temperature, and 31 parts by weight of 2-methacryloyloxyethyl isocyanate was added and reacted to add NCO groups to the terminal OH groups of the side chains of the 2-hydroxyethyl acrylate in the copolymer, thereby obtaining an acrylic polymer III solution containing an acrylic polymer III having a terminal carbon-carbon double bond and to which an ultraviolet absorber was bound.

[0069] [Example 1] To an acrylic polymer solution I containing 100 parts by weight of acrylic polymer I, 5 parts by weight of a crosslinking agent (manufactured by Nippon Polyurethane Industry Co., Ltd., trade name "Coronate HX") and 7 parts by weight of a photopolymerization initiator (manufactured by BASF, trade name "Omnirad 127D") were added to obtain an active energy ray-curable adhesive (1a). The above-mentioned adhesive (1a) was applied to the silicone-treated surface of a release liner (Diafoil MRF38 (thickness: 38 μm) manufactured by Mitsubishi Chemical Corporation), and then heated at 130°C for 2 minutes to form an adhesive layer with a thickness of 5 μm, and an adhesive sheet consisting of a single adhesive layer was formed on the release liner. (evaluation) The adhesive sheet (adhesive layer) was transferred onto a 4-inch square quartz glass to form a quartz glass / adhesive sheet laminate. An LED chip was placed on the adhesive sheet of the quartz glass / adhesive sheet laminate. The adhesive was photocured from the quartz glass side of the obtained sample using an ultraviolet irradiation device (product name "UM 810", manufactured by Nitto Seiki Co., Ltd.) under a nitrogen atmosphere. The curing conditions were ultraviolet light from a high-pressure mercury lamp, wavelength: 365 nm equivalent, 460 mJ / cm. 2 It was decided. Then, laser light (wavelength: 248 nm) was irradiated only at the target chip position from the quartz glass side, and laser transfer was performed. The laser light irradiation dose was 150 mJ / cm 2 , 300mJ / cm 2 , and 500 mJ / cm 2 The laser light peelability was evaluated as follows. The laser irradiated area was observed from the adhesive layer side using a laser microscope to observe the morphology of the adhesive layer surface. When the adhesive was decomposed by laser irradiation and the shape of the chip electrode to which the adhesive layer was attached could be confirmed, it was marked as ◯, and when it was not possible to confirm it, it was marked as ×. When the chip did not peel off and remained attached to the adhesive, it was not possible to evaluate it because it had not been peeled off. The laser irradiated area was observed from the adhesive layer side using a laser microscope to observe the morphology of the adhesive layer surface. When the adhesive was decomposed by laser irradiation and the chip was not attached, it was marked as ◯, and when it remained attached, it was marked as ×. The transmittance of the pressure-sensitive adhesive layer at a wavelength of 248 nm was also measured using a spectrophotometer (product name "UV-Visible-Near-Infrared Spectrophotometer V-670DS", manufactured by JASCO Corporation). Specifically, the light transmittance over a wavelength range of 190 nm to 800 nm was measured for a pressure-sensitive adhesive sheet attached to the silicone-treated surface of a release liner (Diafoil MRF38 (thickness: 38 μm) manufactured by Mitsubishi Chemical Corporation), and the transmittance at a wavelength of 248 nm was obtained. The evaluation results are shown in Table 1 together with Examples 2 to 4, Comparative Examples 1 to 2, and Reference Examples 1 to 2.

[0070] [Example 2] A pressure-sensitive adhesive sheet was obtained in the same manner as in Example 1, except that the thickness of the pressure-sensitive adhesive layer was set to 10 μm. The pressure-sensitive adhesive sheet was then irradiated with laser light at a dose of 150 mJ / cm 2 2 The same evaluation as in Example 1 was carried out except that only the above-mentioned sample was used.

[0071] [Example 3] To an acrylic polymer solution II containing 100 parts by weight of acrylic polymer II, 0.75 parts by weight of a crosslinker (manufactured by Mitsui Chemicals, Inc., trade name "Takenate D-101A") and 7 parts by weight of a photopolymerization initiator (manufactured by BASF, trade name "Omnirad 127D") were added to obtain an active energy ray-curable adhesive (1b). The above-mentioned adhesive (1b) was applied to the silicone-treated surface of a release liner (Diafoil MRF38 (thickness: 38 μm) manufactured by Mitsubishi Chemical Corporation), and then heated at 130°C for 2 minutes to form an adhesive layer with a thickness of 5 μm, and an adhesive sheet consisting of a single adhesive layer was formed on the release liner. The resulting pressure-sensitive adhesive sheet was evaluated in the same manner as in Example 1.

[0072] [Example 4] A pressure-sensitive adhesive sheet was obtained in the same manner as in Example 3, except that the thickness of the pressure-sensitive adhesive layer was set to 10 μm. The pressure-sensitive adhesive sheet was irradiated with laser light at a dose of 150 mJ / cm 2 2 The same evaluation as in Example 3 was carried out except that only the above-mentioned sample was used.

[0073] [Comparative Example 1] To an acrylic polymer solution III containing 100 parts by weight of acrylic polymer III, 0.75 parts by weight of a crosslinker (manufactured by Mitsui Chemicals, Inc., trade name "Takenate D-101A") and 7 parts by weight of a photopolymerization initiator (manufactured by BASF, trade name "Omnirad 127D") were added to obtain an active energy ray-curable adhesive (1c). The above-mentioned adhesive (1c) was applied to the silicone-treated surface of a release liner (Diafoil MRF38 (thickness: 38 μm) manufactured by Mitsubishi Chemical Corporation), and then heated at 130°C for 2 minutes to form an adhesive layer with a thickness of 5 μm, and an adhesive sheet consisting of a single adhesive layer was formed on the release liner. The obtained adhesive sheet was subjected to laser light irradiation at a dose of 150 mJ / cm 2 The same evaluation as in Example 1 was carried out except that only the above-mentioned sample was used.

[0074] Comparative Example 2 An adhesive sheet was obtained in the same manner as in Example 1, except that the thickness of the adhesive layer was 50 μm. The adhesive sheet was exposed to a laser beam with a dose of 150 mJ / cm 2 The same evaluation as in Example 1 was carried out except that only the above-mentioned sample was used.

[0075] [Reference example 1] In the same manner as in Example 1, a pressure-sensitive adhesive sheet was obtained. Laser light irradiation dose: 100mJ / cm 2 The same evaluation as in Example 1 was carried out except for the above.

[0076] [Reference example 2] In the same manner as in Example 1, a pressure-sensitive adhesive sheet was obtained. Laser light irradiation dose: 1000mJ / cm 2 The same evaluation as in Example 1 was carried out except for the above.

[0077] [Table 1] [Explanation of symbols]

[0078] 10 adhesive layer 20 Base material 100, 200 adhesive sheets

Claims

1. An adhesive layer is provided, The pressure-sensitive adhesive layer has a light transmittance of 70% or more at a wavelength of 248 nm. Adhesive sheet used in the electronic component transfer process.

2. The pressure-sensitive adhesive sheet according to claim 1 , wherein the pressure-sensitive adhesive layer has a thickness of 10 μm or less.

3. The pressure-sensitive adhesive sheet according to claim 1 , wherein the pressure-sensitive adhesive layer comprises an active energy ray-curable pressure-sensitive adhesive.

4. The pressure-sensitive adhesive sheet according to claim 3 , wherein the active energy ray-curable pressure-sensitive adhesive comprises a base polymer having an acryloyl group.

5. A method for transporting electronic components, using the pressure-sensitive adhesive sheet according to claim 1.

6. a first step of transferring a plurality of electronic components arranged on a substrate onto the adhesive layer of the adhesive sheet; and a second step of transferring the electronic components on the pressure-sensitive adhesive sheet to another member; The second step includes irradiating the pressure-sensitive adhesive sheet with laser light. The method for transferring electronic components according to claim 5.

7. 7. The method for transferring electronic components according to claim 6, wherein the wavelength of the laser light is 200 nm to 300 nm.

8. The irradiation amount of the laser light is 150 mJ / cm ２ ~500 mJ / cm ２ 7. The method for transferring electronic components according to claim 6, wherein:

9. The method for transferring electronic components according to claim 5 , wherein the electronic components are mini LEDs or micro LEDs.

10. 7. The method for transferring electronic components according to claim 6, wherein the laser light is an excimer laser.

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