Transfer sheet

Abstract

To provide a transfer sheet that can create an alignment mark at any position in any step, and is highly versatile.SOLUTION: The transfer sheet of the present invention is used for receiving electronic component. The transfer sheet of the present invention contains a color-changing component that can change color due to external stimulation. The transfer sheet of the present invention has an adhesive layer, and the adhesive layer preferably contains the color-changing component.SELECTED DRAWING: None

Description

[Technical Field]

[0001] This invention relates to a transfer sheet. More specifically, this invention relates to a transfer sheet that can be suitably used for transferring electronic components such as semiconductor chips. [Background technology]

[0002] In the manufacturing process of semiconductor devices, semiconductor wafers are generally diced into individual pieces while temporarily fixed on a dicing tape. The individual semiconductor chips are then pushed from the dicing tape side on the back of the wafer using a pin member, picked up by a suction jig called a collet, and mounted on a mounting substrate such as a circuit board (for example, Patent Document 1).

[0003] However, advances in microfabrication technology have led to the miniaturization and thinning of semiconductor chips, which sometimes resulted in damage to the chips when they were picked up with a collet. Furthermore, the miniaturization and multilayering of semiconductor devices have progressed, requiring dense, multilayer mounting of numerous tiny semiconductor chips on a substrate, making individual mounting with a collet inefficient.

[0004] As a means of solving the above problem, a method has been adopted in which individual semiconductor chips are transferred to a transfer sheet, and the transferred semiconductor chips are mounted all at once onto a mounting substrate such as a circuit board (for example, Patent Document 2). [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2019-9203 [Patent Document 2] Japanese Patent Publication No. 2021-197400 [Overview of the project] [Problems that the invention aims to solve]

[0006] In a transfer sheet used for transferring a semiconductor chip, an alignment mark may be provided for positioning the semiconductor chip at a predetermined position. Such alignment marks need to be provided at different positions for each mounting substrate so that the semiconductor chip is accurately positioned on the circuit on the mounting substrate. Since they are custom-made, there are problems such as low versatility and high cost.

[0007] The present invention has been made in view of the above problems, and an object thereof is to provide a transfer sheet that can create an alignment mark at an arbitrary position in an arbitrary process and has high versatility.

Means for Solving the Problems

[0008] As a result of intensive studies to achieve the above object, the present inventors have found that by including a discoloring component that can change color by an external stimulus in the transfer sheet, an alignment mark can be created at an arbitrary position in an arbitrary process. The present invention has been completed based on these findings.

[0009] That is, a first aspect of the present invention provides a transfer sheet used for receiving an electronic component, the transfer sheet containing a discoloring component that can change color by an external stimulus. In this specification, the transfer sheet of the first aspect of the present invention may be referred to as "the transfer sheet of the present invention".

[0010] The transfer sheet of the present invention is for receiving an electronic component instead of individually picking it up with a collet or the like when mounting a fine and thin electronic component such as a semiconductor chip on a mounting substrate such as a circuit board. By using the transfer sheet of the present invention for mounting an electronic component, it becomes possible to receive a plurality of electronic components separated by dicing in a batch, eliminating the need to pick them up individually. Furthermore, the received electronic components can be mounted by transferring them to a large-area mounting substrate in a batch, thus significantly improving the manufacturing efficiency.

[0011] The position where the transfer sheet receives the electronic component needs to be accurately arranged at a position corresponding to the circuit on the mounting substrate. Therefore, it is common for the transfer sheet to be provided with alignment marks for aligning the electronic component. The alignment marks need to be provided at different positions for each mounting substrate on which the electronic component is mounted, and are made to order, so there are problems of low versatility and high cost.

[0012] The transfer sheet of the present invention contains a discoloring component that can change color by an external stimulus. The configuration in which the transfer sheet of the present invention contains the discoloring component means that by applying the external stimulus to the transfer sheet, the discoloring component at the location where the external stimulus is received changes color, and the discolored location can be used as an alignment mark for aligning the position where the electronic component is received. Since this alignment mark can be created at an arbitrary position on the transfer sheet in an arbitrary process, it has very high versatility, can significantly improve production efficiency, and can greatly reduce costs.

[0013] In the transfer sheet of the present invention, a semiconductor chip can be preferably used as the electronic component. Further, the major axis of the electronic component is preferably 500 μm or less. With the progress of microfabrication technology, miniaturization and thinning of electronic components such as semiconductor chips have advanced. By mounting an electronic component using the transfer sheet of the present invention, it is not necessary to pick up each one individually with a collet, so damage to the electronic component can be prevented.

[0014] One embodiment of the transfer sheet of the present invention preferably has an adhesive layer. The configuration in which the transfer sheet of this embodiment has an adhesive layer is suitable in that it can serve as an adhesive layer for temporarily fixing the transfer sheet to a base substrate (carrier substrate). Alternatively, when the adhesive layer receives the electronic component, it is also suitable in that it can reduce the force applied to the electronic component and suppress damage to the electronic component. Further, when the adhesive layer receives the electronic component without contact, the electronic component is easily caught by the adhesive layer without bouncing off, and can be received with high positional accuracy, which is also suitable.

[0015] In the transfer sheet of the above embodiment, it is preferable that the adhesive layer contains the discoloration component. This configuration is preferable because it makes it easy to prepare a transfer sheet containing the discoloration component and because it makes it easy to adjust the content of the discoloration component.

[0016] In the transfer sheet of the above embodiment, the adhesive constituting the adhesive layer is preferably an acrylic adhesive or a urethane adhesive. This configuration is preferable from the viewpoint that acrylic adhesives and urethane adhesives have high transparency and good visibility of alignment marks.

[0017] Another embodiment of the transfer sheet of the present invention preferably has a laminated structure in which the adhesive layer, a substrate, and another adhesive layer different from the adhesive layer are laminated in this order. In this embodiment, the substrate functions as a support for the transfer sheet of the present invention. Furthermore, the other adhesive layer is preferable in that it forms a double-sided adhesive sheet together with the adhesive layer, with one adhesive layer temporarily fixing to the carrier substrate and the other adhesive layer receiving the electronic component. [Effects of the Invention]

[0018] The transfer sheet of the present invention allows alignment marks to be created at any position on the transfer sheet and in any process by applying an external stimulus, which causes the color-changing component to change color. Therefore, it is applicable to all processing technologies, including the transfer process of electronic components, and is highly versatile, dramatically improving production efficiency and significantly reducing costs. [Brief explanation of the drawing]

[0019] [Figure 1] This is a schematic cross-sectional view showing one embodiment of the transfer sheet of the present invention. [Figure 2] This is a schematic cross-sectional view showing another embodiment of the transfer sheet of the present invention. [Figure 3]Figure 1 is a schematic cross-sectional view illustrating one embodiment of the first step in a method for transferring electronic components using a transfer sheet. [Figure 4] Figure 1 is a schematic cross-sectional view illustrating one embodiment of the second step in a method for transferring electronic components using a transfer sheet. [Figure 5] Figure 4 is a schematic cross-sectional view illustrating one embodiment of a method for mounting electronic components using a transfer sheet on which the electronic components shown have been transferred. [Modes for carrying out the invention]

[0020] [Transfer Sheet] The transfer sheet of the present invention is a transfer sheet used to receive electronic components and contains a color-changing component that can change color in response to external stimuli.

[0021] The transfer sheet of the present invention is used to receive small, thin electronic components, such as semiconductor chips, when mounting them onto a circuit board or other mounting substrate, instead of picking them up individually with a collet or similar tool. By using the transfer sheet of the present invention for mounting electronic components, it becomes possible to receive multiple electronic components that have been separated into individual pieces by dicing all at once, eliminating the need for individual picking. Furthermore, the received electronic components can be mounted by transferring them all at once onto a large-area mounting substrate, thereby dramatically improving manufacturing efficiency.

[0022] [Color-changing components that can change color due to external stimuli] The transfer sheet must be precisely positioned to receive electronic components, corresponding to the circuit on the mounting board. Therefore, it is common for transfer sheets to have alignment marks to guide the placement of electronic components. However, these alignment marks must be placed in different locations for each mounting board, and because they are custom-made, they have low versatility and high costs.

[0023] The transfer sheet of the present invention contains a color-changing component that can change color in response to external stimuli (hereinafter, this may be referred to as "the color-changing component of the present invention" in this specification). The configuration of the transfer sheet of the present invention, which contains the color-changing component of the present invention, allows the color-changing component at the location of the external stimulus to change color when the transfer sheet is subjected to the external stimulus, and the discolored location can be used as an alignment mark for positioning the electronic component to be received. Therefore, since the transfer sheet of the present invention can create alignment marks at any position and in any process, it is applicable to all processing technologies, including the transfer process of electronic components, making it highly versatile, dramatically improving production efficiency, and significantly reducing costs.

[0024] Examples of the aforementioned external stimuli include irradiation with active energy rays such as electron beam irradiation, ultraviolet irradiation, and laser light irradiation, as well as heating. From the viewpoint of easily forming alignment marks at any position on the transfer sheet of the present invention, irradiation with active energy rays is preferred, ultraviolet irradiation is more preferred, and ultraviolet laser light irradiation is even more preferred from the viewpoint of easily forming alignment marks at specific positions.

[0025] The term "discolorable" in response to external stimuli refers to the ability to change color due to external stimuli. From the perspective of using it as an alignment mark, "coloring," which changes from colorless (transparent) to colored, is preferable.

[0026] The color-changing component of the present invention is not particularly limited as long as it can change color in response to the external stimulus, but examples include a combination of a compound that changes color upon reaction with an acid and an acid generator, a combination of a compound that decolorizes upon reaction with a base and a base generator, and photochromic compounds.

[0027] [Compounds that change color upon reaction with acids] The compound that changes color by reacting with an acid constituting the color-changing component of the present invention is preferably a compound that changes from colorless (transparent) to colored by an acid, and examples thereof include leuco dyes. A leuco dye is an organic dye whose color tone changes reversibly with oxidation-reduction. It may be one whose absorption wavelength changes with pH. More specifically, it refers to a reduced-form dye having one or more hydrogen atoms that forms a dye and develops color by adding electrons or removing electrons. Leuco dyes are colorless or have a weak color in a neutral or alkaline medium, but when reacted with an acidic substance or an electron-withdrawing substance, they are dyes that become colored due to the lactone ring being in an open-ring state as shown in the following formula. By selecting a leuco dye that is substantially colorless or has a weak color before electrons are removed, the change in coloring can be made prominent, and the visibility of the alignment mark can be improved.

[0028] [Chemical formula]

[0029] In the above formula, R 6 , 7 , and R 2 may be the same or different and represent a hydrogen atom or a hydrocarbon group. Or, R 1 , and R 2 may form a 5- or 6-membered nitrogen-containing heterocyclic ring together with the nitrogen atom to which they are attached. R 3 , R 4 , R 5 , R 6 , R 7 , R 8 , and R 9 may be the same or different and represent a hydrogen atom, a halogen atom, a hydrocarbon group, or -NR 10 R 11 . R 10 , and R 11 may be the same or different and represent a hydrogen atom or a hydrocarbon group. Or, R 10 , and R 11 may form a 5- or 6-membered nitrogen-containing heterocyclic ring together with the nitrogen atom to which they are attached. Or, R 6 and R 7, R 7 and R 8 , R 8 and R 9 These may combine to form an aromatic hydrocarbon ring, such as a benzene ring, together with the benzene ring to which they are attached.

[0030] Examples of the hydrocarbon group include methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, s-butyl group, t-butyl group, n-pentyl group, isopentyl group, s-pentyl group, t-pentyl group, neopentyl group, etc. 1-6 Alkyl groups; C such as cyclohexyl groups 3-6 Cycloalkyl groups; C such as phenyl groups 6-10 Aryl group; benzyl group, etc. 7-11 Examples include aralkyl groups. Hydrocarbon groups include C 1-6 Alkyl, halo C 1-6 Alkyl alkyl group, halogen atom, C 1-6 Alkoxy group, C 1-6 The compound may have substituents such as alkoxycarbonyl groups and tetrahydrofuryl groups. Examples of 5- or 6-membered nitrogen-containing heterocycles include pyrrolidine, piperidine, and morpholine.

[0031] The leuco dye is colored by the acid generated by irradiating the acid generator with active energy rays or by heating it.

[0032] Furthermore, leuco dyes can be decolorized by reacting them with a base after the lactone ring has opened and colored, causing the lactone ring to close. The base can be generated by irradiating a base generator (described later) with active energy rays or by heating it.

[0033] Examples of leuco dyes include leuco compounds such as phthalide dyes (indolinophthalide type, triphenylmethanephthalide type, etc.), fluorane dyes, triarylmethane dyes, diphenylmethane dyes, phenothiazine dyes, auramine dyes, spiropyran dyes, and rhodamine dyes.

[0034] From the viewpoint of excellent color development, the leuco dye is preferably at least one leuco dye selected from the group consisting of phthalide dyes and fluorane dyes. Leuco dyes may be used individually or in combination of two or more types.

[0035] Specific examples of leuco dyes include the following compounds: 2'-Anilino-6'-(N,N-dipentan-1-ylamino)-3'-methyl-3H-spiro[isobenzofuran-1,9'-xanthene]-3-one, 2-anilino-3-methyl-6-dibutylaminofluorane, 2-anilino-3-methyl-6-dipentylaminofluorane, 2-anilino-3-methyl-6-[ethyl(4-methylphenyl)amino]fluorane, 3,3-bis(p-dimethylaminophenyl)-phthalide, 3,3-bis(p-dimethylaminophenyl)-6-dimethylaminophthalide (also known as crystal violet) Lactone), 3,3-bis(p-dimethylaminophenyl)-6-diethylaminophthalide, 3,3-bis(p-dimethylaminophenyl)-6-chlorphthalide, 3,3-bis(p-dibutylaminophenyl)phthalide, 3-cyclohexylamino-6-chlorofluorane, 3-dimethylamino-5,7-dimethylfluorane, 3-(N-methyl-N-isobutyl)-6-methyl-7-anilinofluorane, 3-(N-ethyl-N-isoamyl)-6-methyl-7-anilinofluorane, 3-diethylamino-7-chlorofluorane, 3-diethylamino-7-chlorofluorane, 3-diethylamino-7-chlorofluorane Tylamino-7-methylfluorane, 3-diethylamino-7,8-benzfluorane, 3-diethylamino-6-methyl-7-chlorfluorane, 3-(Np-tolyl-N-ethylamino)-6-methyl-7-anilinofluorane, 3-pyrrolidino-6-methyl-7-anilinofluorane, 2-{N-(3'-trifluoromethylphenyl)amino}-6-diethylaminofluorane, 2-{3,6-bis(diethylamino)-9-(o-chloranilino)xanthyalbenzoate lactam}3-diethylamino-6-methyl-7-(m-trichloro (N,N-methylanilino)fluorane, 3-diethylamino-7-(o-chloranilino)fluorane, 3-dibutylamino-7-(o-chloranilino)fluorane, 3-(N-methyl-N-amylamino)-6-methyl-7-anilinofluorane, 3-(N-methyl-N-cyclohexylamino)-6-methyl-7-anilinofluorane, 3-diethylamino-6-methyl-7-anilinofluorane, 3-diethylamino-6-methyl-7-(2',4'-dimethylanilino)fluorane, 3-(N,N-diethylamino)-5-methyl-7-(N,N-dibenzylamino)fluorane, benzoylleucomethylene blue, 6'-chloro-8'-methoxy-benzoindlino-spiropyran, 6'-bromo-3'-methoxy-benzoindlino-spiropyran, 3-(2'-hydroxy-4'-dimethylaminophenyl)-3-(2'-methoxy-5'-chlorophenyl)phthalide, 3-(2'-hydroxy-4'-dimethylaminophenyl)-3-(2'-methoxy-5'-nitrophenyl)phthalide, 3 -(2'-hydroxy-4'-diethylaminophenyl)-3-(2'-methoxy-5'-methylphenyl)phthalide, 3-(2'-methoxy-4'-dimethylaminophenyl)-3-(2'-hydroxy-4'-chlor-5'-methylphenyl)phthalide, 3-morpholino-7-(N-propyl-trifluoromethylanilino)fluorane, 3-pyrrolidino-7-trifluoromethylanilinofluorane, 3-diethylamino-5-chloro-7-(N-bendi (Trifluoromethylanilino)fluorane, 3-pyrrolidino-7-(di-p-chlorophenyl)methylaminofluorane, 3-diethylamino-5-chlor-7-(α-phenylethylamino)fluorane, 3-(N-ethyl-p-toluidino)-7-(α-phenylethylamino)fluorane, 3-diethylamino-7-(o-methoxycarbonylphenylamino)fluorane, 3-diethylamino-5-methyl-7-(α-phenylethylamino)fluorane Oran, 3-diethylamino-7-piperidinofluorane, 2-chloro-3-(N-methyltoluidino)-7-(pn-butylanilino)fluorane, 3-(N-methyl-N-isopropylamino)-6-methyl-7-anilinofluorane, 3-dibutylamino-6-methyl-7-anilinofluorane, 3,6-bis(dimethylamino)fluorenspiro(9,3')-6'-dimethylaminophthalide, 3-(N-benzyl-N-cyclohexylamino)-5,6-Benzo-7-α-naphthylamino-4'-bromofluorane, 3-diethylamino-6-chlor-7-anilinofluorane, 3-{N-ethyl-N-(2-ethoxypropyl)amino}-6-methyl-7-anilinofluorane, 3-{N-ethyl-N-tetrahydrofurfurylamino}-6-methyl-7-anilinofluorane, 3-diethylamino-6-methyl-7-mesitidino-4',5'-benzofluorane, 3-(p-dimethylaminophenyl)-3-{1,1-bis(p-dimethylaminophenyl) Nophenyl)ethylene-2-yl}phthalide, 3-(p-dimethylaminophenyl)-3-{1,1-bis(p-dimethylaminophenyl)ethylene-2-yl}-6-dimethylaminophthalide, 3-(p-dimethylaminophenyl)-3-(1-p-dimethylaminophenyl-1-phenylethylene-2-yl)phthalide, 3-(p-dimethylaminophenyl)-3-(1-p-dimethylaminophenyl-1-p-chlorophenylethylene-2-yl)-6-dimethylaminophthalide, 3-(4'- Dimethylamino-2'-methoxy)-3-(1"-p-dimethylaminophenyl-1"-p-chlorophenyl-1",3"-butadien-4"-yl)benzophthalide, 3-(4'-dimethylamino-2'-benzyloxy)-3-(1"-p-dimethylaminophenyl-1"-phenyl-1",3"-butadien-4"-yl)benzophthalide, 3-dimethylamino-6-dimethylamino-fluoren-9-spiro-3'(6'-dimethylamino)phthalide, 6-(diethylamino)-2-[(3 -Trifluoromethyl)anilino]xanthene-9-spiro-3'-phthalide, 3,3-bis{2-(p-dimethylaminophenyl)-2-(p-methoxyphenyl)ethenyl}-4,5,6,7-tetrachlorophthalide, 3-bis{1,1-bis(4-pyrrolidinophenyl)ethylene-2-yl}-5,6-dichloro-4,7-dibromophthalide, bis(p-dimethylaminostyryl)-1-naphthalenesulfonylmethane, bis(p-dimethylaminostyryl)-1-p-tolylsulfonylmethane.

[0036] Compounds that change color upon reaction with acid may be used individually or in mixtures of two or more types. The compound that changes color upon reaction with acid is preferably present in amounts of 0.01 to 30 parts by weight, more preferably 0.1 to 30 parts by weight, even more preferably 0.1 to 20 parts by weight, and still more preferably 1 to 10 parts by weight per 100 parts by weight of the transfer sheet. Within these ranges, alignment marks can be efficiently formed by the color change caused by the compound that changes color upon reaction with acid.

[0037] [Acid Generator] The acid generator constituting the color-changing component of the present invention is a compound that generates acid (cation) when the aforementioned external stimulus is applied. The generated acid causes the compound that changes color through reaction with the acid to change color. When the external stimulus is irradiation with active energy rays, a photoacid generator is used, and when the external stimulus is heating, a thermal acid generator is used. From the viewpoint of easily creating alignment marks at arbitrary positions on the transfer sheet of the present invention by irradiation with active energy rays, a photoacid generator is preferred.

[0038] The photoacid generator is a compound that can generate acid (cations) by irradiation with active energy rays such as alpha rays, beta rays, gamma rays, electron beams, neutron beams, and X-rays, not limited to light such as ultraviolet, visible light, and infrared light. By using the photoacid generator together with a compound that changes color upon reaction with the acid, the transfer sheet of the present invention can be irradiated with active energy rays to cause color change at any location and at any time, thereby forming alignment marks.

[0039] The photoacid generator is not particularly limited as long as it is a compound that can generate acid (cation) by irradiation with active energy rays, and examples include sulfonium salt compounds, iodonium salt compounds, aromatic N-oxyimide sulfonates, sulfonic acid ester compounds, and halomethyl-substituted S-triazine derivatives.

[0040] From the viewpoint of having good compatibility with the adhesive that constitutes the transfer sheet of the present invention (described later), the photoacid generator is preferably at least one compound selected from the group consisting of sulfonium salt compounds, iodonium salt compounds, and aromatic N-oxyimide sulfonates, and sulfonium salt compounds are particularly preferred.

[0041] Specific examples of sulfonium salt compounds include salts composed of cations such as dimethylphenacylsulfonium, dimethylbenzylsulfonium, dimethyl-4-hydroxyphenylsulfonium, dimethyl-4-hydroxynaphthylsulfonium, dimethyl-4,7-dihydroxynaphthylsulfonium, dimethyl-4,8-dihydroxynaphthylsulfonium, triphenylsulfonium, p-tolyldiphenylsulfonium, p-tert-butylphenyldiphenylsulfonium, diphenyl-4-phenylthiophenylsulfonium, and diphenyl-4-phenylthiophenylsulfonium, and anions such as chlorides, bromides, p-toluenesulfonate, trifluoromethanesulfonate, tetrafluoroborate, tetrakispentafluorophenylborate, tetrakispentafluorophenylgallate, hexafluorophosphate, hexafluoroarsenate, hexafluoroantimonate, and nonafluorobutanesulfonate.

[0042] Examples of iodonium salt compounds include salts composed of cations such as diphenyliodonium, bis(p-chlorophenyl)iodonium, ditolyliodonium, bis(p-tert-butylphenyl)iodonium, p-isopropylphenyl-p-methylphenyliodonium, bis(m-nitrophenyl)iodonium, p-tert-butylphenylphenyliodonium, p-methoxyphenylphenyliodonium, bis(p-methoxyphenyl)iodonium, p-octyloxyphenylphenyliodonium, and p-phenoxyphenylphenyliodonium, and anions such as chloride, bromide, p-toluenesulfonate, trifluoromethanesulfonate, tetrafluoroborate, tetrakispentafluorophenylborate, tetrakispentafluorophenylgallate, hexafluorophosphate, hexafluoroarsenate, hexafluoroantimonate, and nonafluorobutanesulfonate.

[0043] Examples of aromatic N-oxyimide sulfonates include N-(trifluoromethylsulfonyloxy)succinimide, N-(trifluoromethylsulfonyloxy)phthalimide, N-(trifluoromethylsulfonyloxy)diphenylmaleimide, N-(trifluoromethylsulfonyloxy)bicyclohepto-5-ene-2,3-dicarboximide, and N-(trifluoromethylsulfonyloxy)naphthylimide.

[0044] Examples of sulfonic acid ester compounds include benzointosylate, α-methylolbenzointosylate, o-nitrobenzyl p-toluenesulfonate, and p-nitrobenzyl-9,10-diethoxyanthracene-2-sulfonate. Specific examples of halomethyl-substituted S-triazine derivatives include 2,4,6-tris(trichloromethyl)-S-triazine, 2-methyl-4,6-bis(trichloromethyl)-S-triazine, 2-phenyl-4,6-bis(trichloromethyl)-S-triazine, and 2-methyl-4,6-bis(tribromomethyl)-S-triazine.

[0045] The thermal acid generator is a compound that can generate acid (cations) when heated. By using the thermal acid generator together with a compound that changes color upon reaction with the acid, the transfer sheet of the present invention can be heated to cause discoloration or coloring at any location and at any time, thereby forming alignment marks.

[0046] Examples of thermal acid generators include aryl sulfonium salts, aryl iodonium salts, allene ion complexes, quaternary ammonium salts, aluminum chelates, and boron trifluoride amine complexes. Examples of anions include those similar to those used in photoacid generators, such as SbF6. - These may be antimony fluoride ions, such as those mentioned above.

[0047] These acid generators can be used individually or in combination of two or more. The acid generator is preferably 0.001 to 30 parts by weight, more preferably 0.01 to 25 parts by weight, even more preferably 0.1 to 30 parts by weight, and still more preferably 0.1 to 20 parts by weight per 100 parts by weight of the transfer sheet of the present invention. Within this range, acid can be efficiently generated by irradiation with active energy rays or heating, and alignment marks can be efficiently formed by discoloration caused by a compound that changes color upon reaction with the acid.

[0048] [Base Generator] The transfer sheet of the present invention may contain a base generator. The base generator is a compound that generates a base when the external stimulus is applied. If the external stimulus is irradiation with active energy rays, a photobase generator is used; if the external stimulus is heating, a thermobase generator is used. A photobase generator is preferred from the viewpoint of efficiently removing alignment marks formed on the transfer sheet of the present invention.

[0049] If the transfer sheet of the present invention contains a photoacid generator, it is preferable to set the combination of the photoacid generator and the thermal base generator such that the base generator does not generate a base at the same time as the photoacid generator generates an acid upon irradiation with active energy rays. Furthermore, if the transfer sheet of the present invention contains a thermal acid generator, it is preferable to set the combination of the thermal acid generator and the photobase generator such that the base generator does not generate a base at the same time as the thermal acid generator generates an acid due to heating.

[0050] A photobase generator is a compound that can generate bases (anions) by irradiation with active energy rays such as alpha rays, beta rays, gamma rays, electron beams, neutron beams, and X-rays, not limited to light such as ultraviolet, visible, and infrared rays. By using a photobase generator together with a compound that changes color upon reaction with the acid, the alignment marks can be removed at any desired timing by irradiating the transfer sheet of the present invention with active energy rays.

[0051] The photobase generator is not particularly limited as long as it is a compound that can generate a base (anion) by irradiation with active energy rays. Examples include transition metal complexes, compounds having a benzylcarbamate structure, compounds having an ortho-substituted nitrobenzene structure, oximes, imidazole derivatives, benzoin compounds, compounds having an N-formylated aromatic amino group, compounds having an N-acylated aromatic amino group, compounds having an alkoxybenzylcarbamate group, compounds having a 1,4-dihydropyridine skeleton, oxime esters, quaternary ammonium salts, and the like.

[0052] A thermal base generator is a compound that can generate a base (anion) upon heating. By using a thermal base generator together with a compound that changes color upon reaction with the acid, the transfer sheet of the present invention can be heated to make the alignment marks disappear at any desired timing.

[0053] The thermal base generator is not particularly limited as long as it is a compound that can generate a base (anion) upon heating. Examples include carbamate derivatives such as 2-(4-biphenyl)-2-propyl carbamate and 1,1-dimethyl-2-cyanoethyl carbamate, urea derivatives such as urea and N,N,N'-trimethylurea, dihydropyridine derivatives such as 1,4-dihydronicotinamide, dicyandiamide, and salts consisting of acids and bases such as organic salts and inorganic salts.

[0054] These base-generating agents can be used individually or in combination of two or more. The amount of base generating agent is preferably 0.001 to 30 parts by weight, more preferably 0.01 to 25 parts by weight, and even more preferably 0.1 to 20 parts by weight per 100 parts by weight of the transfer sheet of the present invention. Within this range, bases can be efficiently generated by active energy ray irradiation or heating, enabling the decolorization of alignment marks.

[0055] [Combination of a compound that decolorizes upon reaction with a base and a base generator] The compound that decolorizes upon reaction with a base constituting the color-changing component of the present invention is preferably a compound that changes from colored to colorless (transparent) upon contact with a base. For example, a compound obtained by the above-mentioned leuco dye changing color (coloring) upon reaction with an acid is an example. Compounds that decolorize upon reaction with a base can also be produced, for example, by the reaction of a leuco dye with an acid generated by heating the above-mentioned thermal acid generator.

[0056] The compound that decolorizes upon reaction with a base may be used individually or as a mixture of two or more types. The amount of the compound that decolorizes upon reaction with a base is the same as that of the compound that changes color upon reaction with an acid.

[0057] Examples of base generators used in combination with compounds that decolorize upon reaction with a base are the same as those mentioned above, and can be used in the same quantities.

[0058] A preferred embodiment of the combination of a compound that decolorizes upon reaction with a base and a base generator is to color the entire surface of a transfer sheet with a compound that decolorizes upon reaction with a base generated by the reaction of a leuco dye with an acid generated by heating the above-mentioned thermal acid generator, and then decolorize the area by applying an external stimulus such as light to a predetermined location, thereby decolorizing the area with a base generated from the base generator, and using the decolorized area as an alignment mark.

[0059] [Photochromic compounds] The photochromic compound constituting the color-changing component of this invention is a compound whose molecular structure reversibly changes upon irradiation with light of a specific wavelength, resulting in a change in color. As an external stimulus, the area that has changed color upon irradiation with light of a specific wavelength can be used as an alignment mark.

[0060] There are no particular restrictions on the photochromic compound; any compound from the conventionally known compounds can be appropriately selected and used. For example, one or more compounds can be used from spiropyran compounds, spirooxazine compounds, fulgide compounds, naphthopyran compounds, bisimidazole compounds, etc., depending on the desired coloration. The amount of the photochromic compound is preferably 0.01 to 30 parts by weight, more preferably 0.1 to 30 parts by weight, even more preferably 0.1 to 20 parts by weight, and even more preferably 1 to 10 parts by weight per 100 parts by weight of the transfer sheet. Within this range, alignment marks can be efficiently formed by the color change caused by the photochromic compound.

[0061] One embodiment of the transfer sheet of the present invention (which may be referred to as "the first embodiment" in this specification) has an adhesive layer, and it is preferable that the adhesive layer contains the color-changing component of the present invention. The configuration of the transfer sheet in the first embodiment, which includes an adhesive layer, is preferable because it can serve as an adhesive layer for temporarily fixing the transfer sheet to a base substrate (carrier substrate). Alternatively, if the adhesive layer receives an electronic component, it is preferable because it can reduce the force applied to the electronic component and suppress damage to the electronic component. Furthermore, if the adhesive layer receives the electronic component without contact, it is preferable because the electronic component is more likely to be caught by the adhesive layer without bouncing, and can be received with high positional accuracy.

[0062] In the first embodiment, the configuration in which the adhesive layer contains the color-changing component is preferable because it facilitates the preparation of a transfer sheet containing the color-changing component of the present invention and facilitates the adjustment of the content of the color-changing component of the present invention.

[0063] Furthermore, other embodiments of the transfer sheet of the present invention (which may be referred to as "second embodiment" in this specification) may also have a laminated structure in which the adhesive layer, the substrate, and another adhesive layer different from the adhesive layer are laminated in this order. In the second embodiment, the substrate functions as a support for the transfer sheet of the present invention. Furthermore, the other adhesive layer is preferable in that it can form a double-sided adhesive sheet together with the adhesive layer, with one adhesive layer temporarily fixing to the carrier substrate and the other adhesive layer receiving the electronic component.

[0064] In the second embodiment, the adhesive layer and the other adhesive layer may be composed of the same adhesive or of different adhesives. Furthermore, in the second embodiment, the discoloration component of the present invention may be contained only in the adhesive layer, or it may be contained in both the adhesive layer and the other adhesive layer.

[0065] In the transfer sheet of the second embodiment, the adhesive layer for receiving electronic components is referred to as the "first adhesive layer," and the adhesive layer for temporarily fixing to the carrier substrate is referred to as the "second adhesive layer."

[0066] In the second embodiment, the first adhesive layer and the second adhesive layer may be composed of the same adhesive or of different adhesives. Furthermore, in the second embodiment, the discoloration component of the present invention may be contained in only one of the first adhesive layer and the second adhesive layer, or it may be contained in both the first adhesive layer and the second adhesive layer.

[0067] In the second embodiment, when the first adhesive layer receives electronic components or after receiving them, if processing using active energy ray irradiation such as laser light irradiation is performed, it is undesirable for the transfer sheet to discolor due to the active energy ray irradiation. Therefore, it is preferable that the first adhesive layer does not contain a discoloration component and the second adhesive layer contains a discoloration component.

[0068] In the first and second embodiments, the compound that changes color upon reaction with an acid is preferably 0.01 to 30 parts by weight, more preferably 0.1 to 30 parts by weight, even more preferably 0.1 to 20 parts by weight, and still more preferably 1 to 10 parts by weight, per 100 parts by weight of the adhesive layer (first adhesive layer or second adhesive layer). Within this range, alignment marks can be efficiently formed by the color change caused by the compound that changes color upon reaction with an acid.

[0069] In the first and second embodiments, the acid generator is preferably 0.001 to 30 parts by weight, more preferably 0.01 to 25 parts by weight, even more preferably 0.1 to 30 parts by weight, and still more preferably 0.1 to 20 parts by weight per 100 parts by weight of the adhesive layer (first adhesive layer or second adhesive layer). Within this range, acid can be efficiently generated by irradiation with active energy rays or heating, and alignment marks can be efficiently formed by discoloration caused by a compound that changes color upon reaction with the acid.

[0070] In the first and second embodiments, the amount of base generator is preferably 0.001 to 30 parts by weight, more preferably 0.01 to 25 parts by weight, and even more preferably 0.1 to 20 parts by weight, per 100 parts by weight of the adhesive layer (first adhesive layer or second adhesive layer). Within this range, bases can be efficiently generated by active energy ray irradiation or heating, enabling the decolorization of alignment marks.

[0071] In the first and second embodiments, the content of the compound that decolorizes upon reaction with a base and the photochromic compound in the adhesive layer is the same as that of the compound that changes color upon reaction with an acid.

[0072] One embodiment of the transfer sheet of the present invention may be described below with reference to the drawings, but the transfer sheet of the present invention is not limited to this embodiment. Figure 1 is a schematic cross-sectional view showing one embodiment (second embodiment) of the transfer sheet of the present invention, where 1 is the transfer sheet, 10 is the substrate, 11 is the first adhesive layer, and 12 is the second adhesive layer.

[0073] As shown in Figure 1, the transfer sheet 1 has a laminated structure in which a first adhesive layer 11, a substrate 10, and a second adhesive layer 12 are stacked in this order. When mounting fine, thin electronic components such as semiconductor chips onto a mounting substrate such as a circuit board, the first adhesive layer 11 receives the electronic components. By using the transfer sheet 1 for mounting electronic components, the first adhesive layer 11 can receive multiple electronic components that have been separated into individual pieces by dicing all at once, eliminating the need to pick them up individually. Furthermore, the electronic components received by the first adhesive layer 11 can be mounted by transferring them all at once onto a large-area mounting substrate, thereby dramatically improving manufacturing efficiency.

[0074] In this embodiment, when the first adhesive layer 11 is processed using active energy ray irradiation, such as laser light irradiation, when receiving or after receiving electronic components, the first adhesive layer does not contain a discoloration component, while the second adhesive layer does (not shown), in order to suppress discoloration of the first adhesive layer 11 due to active energy ray irradiation.

[0075] [First adhesive layer] The first adhesive layer is an adhesive layer for receiving and holding electronic components, and is preferably made of a low-tack adhesive layer. The configuration in which the first adhesive layer is made of a low-tack adhesive layer is preferable because it can reduce the force applied to the electronic component when receiving it, thereby suppressing damage to the electronic component. Furthermore, when the first adhesive layer receives an electronic component without contact, for example, the electronic component is peeled off the dicing tape by pressing it with a pin member and dropped onto the first adhesive layer. However, when the first adhesive layer receives the dropped electronic component, it may bounce and not be received accurately. When this phenomenon occurs, the positional accuracy of the electronic product may decrease and contact failure may occur. The configuration in which the first adhesive layer is made of a low-tack adhesive layer is also preferable because when the first adhesive layer receives an electronic component without contact, the electronic component is more easily caught by the first adhesive layer without bouncing, and can be received with good positional accuracy. Moreover, it is preferable because the electronic component can be easily peeled off the first adhesive layer when the electronic component received by the transfer sheet is mounted on the mounting substrate.

[0076] The first adhesive layer can be made into a low-tack adhesive layer by adjusting the type, composition, and degree of crosslinking of the constituent adhesives, or by forming a Weak Boundary Layer (WBL) by incorporating a light release agent or plasticizer.

[0077] The 180° peel-off adhesive strength of the first adhesive layer to the PET film at 25°C is not particularly limited, but from the viewpoint of ensuring that electronic components are received with good positional accuracy without damage and that there is good transferability to the mounting substrate, it is preferably 100mN / 25mm or less, more preferably 50mN / 25mm or less, and even more preferably 10mN / 25mm or less. Furthermore, from the viewpoint of adhesion of electronic components to the first adhesive layer, the 180° peel-off adhesive strength of the first adhesive layer to the glass plate at 25°C is preferably 0.1mN / 25mm or more, and more preferably 1mN / 25mm or more.

[0078] The thickness of the first adhesive layer is not particularly limited, but is preferably 1 μm or more, and more preferably 3 μm or more. A thickness above a certain level is preferable because it makes it easier for the first adhesive layer to accurately receive electronic components. Furthermore, the upper limit of the thickness of the first adhesive layer is not particularly limited, but is preferably 100 μm or less, and more preferably 75 μm or less. A thickness below a certain level is preferable because it makes it easier to accurately transfer electronic components to the mounting substrate.

[0079] The haze of the first adhesive layer (according to JIS K7136) is not particularly limited, but is preferably 10% or less, and more preferably 5.0% or less. A haze of 10% or less is preferable because it provides excellent transparency, for example, improving the visibility of alignment marks formed by applying external stimuli to the transfer sheet of the second embodiment. The haze can be measured, for example, by forming the first adhesive layer on a release liner, leaving it at normal conditions (23°C, 50%RH) for at least 24 hours, peeling off the release liner, and attaching the sample to a glass slide (for example, one with a total light transmittance of 91.8% and a haze of 0.4%), using a haze meter (manufactured by Murakami Color Technology Laboratory Co., Ltd., product name "HM-150").

[0080] The total light transmittance of the first adhesive layer in the visible light wavelength range (according to JIS K7361-1) is not particularly limited, but is preferably 85% or higher, and more preferably 88% or higher. A total light transmittance of 85% or higher is preferable because it provides excellent transparency, for example, improving the visibility of alignment marks formed by applying external stimuli to the transfer sheet of the second embodiment. The total light transmittance can be measured, for example, by forming the first adhesive layer on a release liner, leaving it at normal conditions (23°C, 50%RH) for at least 24 hours, peeling off the release liner, and attaching the sample to a glass slide (for example, one with a total light transmittance of 91.8% and haze of 0.4%), using a haze meter (manufactured by Murakami Color Technology Laboratory Co., Ltd., product name "HM-150").

[0081] The adhesive constituting the first adhesive layer described above is not particularly limited, but examples include silicone-based adhesives, urethane-based adhesives, acrylic-based adhesives, rubber-based adhesives, polyester-based adhesives, polyamide-based adhesives, epoxy-based adhesives, vinyl alkyl ether-based adhesives, and fluorine-based adhesives. Among these, silicone-based adhesives, urethane-based adhesives, and acrylic-based adhesives are preferred from the viewpoint of being able to receive electronic components with good positional accuracy without damage, having good transferability to the mounting substrate, and having high transparency and good visibility of alignment marks, as are silicone-based adhesives, urethane-based adhesives, and acrylic-based adhesives, which are easier to control to have low tackiness, low tackiness, and transparency. Silicone-based adhesives and urethane-based adhesives are more preferred, and silicone-based adhesives are even more preferred.

[0082] [Silicone-based adhesive] The silicone adhesive is not particularly limited, and known or conventional silicone adhesives can be used, such as addition-type silicone adhesives, peroxide-curing type silicone adhesives, and condensation-type silicone adhesives. The silicone adhesive may be one-component or two-component. The silicone adhesive can be used alone or in combination of two or more types.

[0083] The aforementioned addition-type silicone adhesives are adhesives that produce a silicone polymer by an addition reaction (hydrosilylation reaction) between an organopolysiloxane having an alkenyl group such as a vinyl group on a silicon atom and an organopolysiloxane having a hydrosilyl group, using a platinum compound catalyst such as chloroplatinic acid. Peroxide-curing type silicone adhesives are adhesives that produce a silicone polymer by curing (crosslinking) an organopolysiloxane with a peroxide. Furthermore, condensation-type silicone adhesives are adhesives that produce a silicone polymer by a dehydration or dealcoholization reaction between polyorganosiloxanes having hydrolyzable silyl groups such as silanol groups or alkoxysilyl groups at their ends.

[0084] Examples of silicone-based adhesives include silicone-based adhesive compositions containing silicone rubber and silicone resin, due to their ease of control over low tackiness and adhesiveness.

[0085] The silicone rubber is not particularly limited as long as it is a silicone-based rubber component, but for example, organopolysiloxanes mainly composed of dimethylsiloxane, methylphenylsiloxane, etc. can be used. Depending on the type of reaction, silicone rubber having alkenyl groups bonded to silicon atoms (alkenyl group-containing organopolysiloxane; in the case of addition reaction), silicone rubber having at least methyl groups (in the case of peroxide curing), and silicone rubber having silanol groups or hydrolyzable alkoxysilyl groups at the ends (in the case of condensation) can be used. The weight-average molecular weight of organopolysiloxane in silicone rubber is usually 150,000 or more, but is preferably 280,000 to 1,000,000, and particularly preferably 500,000 to 900,000.

[0086] Furthermore, the silicone resin is not particularly limited as long as it is a silicone-based resin used in silicone-based adhesives, for example, the constituent unit "R3Si 1 / 2 The M unit consists of the constituent unit "SiO2", the Q unit consists of the constituent unit "RSiO2", and the constituent unit "RSiO 3 / 2Examples include silicone resins made of organopolysiloxanes, which are (co)polymers having at least one unit selected from the T units consisting of "" and the D units consisting of the constituent unit "R2SiO". In the constituent unit, R represents a hydrocarbon group or a hydroxyl group. Examples of the hydrocarbon group include aliphatic hydrocarbon groups (alkyl groups such as methyl and ethyl groups), alicyclic hydrocarbon groups (cycloalkyl groups such as cyclohexyl groups), and aromatic hydrocarbon groups (aryl groups such as phenyl and naphthyl groups). The ratio of the M unit to at least one unit selected from the Q, T, and D units is preferably about 0.3 / 1 to 1.5 / 1 (preferably 0.5 / 1 to 1.3 / 1). Various functional groups such as vinyl groups may be introduced into the organopolysiloxane in such silicone resins as needed. The introduced functional groups may be functional groups capable of crosslinking reactions. As the silicone resin, MQ resin consisting of M units and Q units is preferred. The weight-average molecular weight of the organopolysiloxane in the silicone resin is usually 1000 or more, but is preferably 1000 to 20000, and particularly preferably 1500 to 10000.

[0087] While there are no particular restrictions on the mixing ratio of silicone rubber to silicone resin, it is preferable, for example, that the ratio of silicone resin is 100 to 220 parts by weight (particularly 120 to 180 parts by weight) per 100 parts by weight of silicone rubber, as this makes it easier to control low tackiness and low adhesiveness.

[0088] In a silicone-based adhesive composition containing silicone rubber and silicone resin, the silicone rubber and silicone resin may simply be in a mixed state, or they may react with each other to form condensates (especially partial condensates), crosslinked products, addition reaction products, etc.

[0089] Furthermore, silicone-based adhesive compositions containing silicone rubber and silicone resin typically contain a crosslinking agent to create a crosslinked structure, as this makes it easier to control low tackiness and low adhesiveness. While there are no particular limitations on such crosslinking agents, siloxane-based crosslinking agents (silicone-based crosslinking agents) and peroxide-based crosslinking agents are suitably used. The crosslinking agent can be used alone or in combination of two or more types.

[0090] As the siloxane-based crosslinking agent, for example, a polyorganohydrogensiloxane having two or more hydrogen atoms bonded to silicon atoms in the molecule can be suitably used. In such a polyorganohydrogensiloxane, various organic groups other than hydrogen atoms may be bonded to the silicon atoms to which the hydrogen atoms are bonded. Examples of such organic groups include alkyl groups such as methyl groups and ethyl groups; aryl groups such as phenyl groups; and alkyl halides, but from the viewpoint of synthesis and handling, methyl groups are preferred. Furthermore, the skeletal structure of the polyorganohydrogensiloxane may be linear, branched, or cyclic, but a linear structure is preferred.

[0091] Examples of peroxide-based crosslinking agents include diacyl peroxide, alkyl peroxyester, peroxydicarbonate, monoperoxycarbonate, peroxyketal, dialkyl peroxide, hydroperoxide, and ketone peroxide. More specifically, examples include benzoyl peroxide, t-butyl peroxybenzoate, dicumyl peroxide, t-butylcumyl peroxide, di-t-butyl peroxide, 2,5-dimethyl-2,5-di-t-butyl peroxyhexane, 2,4-dichlorobenzoyl peroxide, di-t-butyl peroxydiisopropylbenzene, 1,1-bis(t-butylperoxy)-3,3,5-trimethylcyclohexane, and 2,5-dimethyl-2,5-di-t-butyl peroxyhexyn-3.

[0092] As addition-curing silicone adhesives, for example, the following are commercially available: product names "KR-3700", "KR-3701", "X-40-3237-1", "X-40-3240", "X-40-3291-1", and "X-40-3306" (all manufactured by Shin-Etsu Chemical Co., Ltd.). In addition, as peroxide-curing silicone adhesives, for example, product names "KR-100", "KR-101-10", and "KR-130" (all manufactured by Shin-Etsu Chemical Co., Ltd.) are commercially available.

[0093] The addition-type silicone adhesive composition preferably contains a curing catalyst such as a platinum catalyst. Examples of commercially available platinum catalysts include "CAT-PL-50T" (manufactured by Shin-Etsu Chemical Co., Ltd.), "DOWSIL NC-25 Catalyst," or "DOWSIL SRX212 Catalyst" (all manufactured by Dow Toray Industries, Inc.). From the viewpoint of balancing the ability of the first adhesive layer to accept electronic components, positional accuracy, transferability to the mounting substrate, and tack strength, the curing catalyst content is preferably about 0.1 to 10 parts by weight per 100 parts by weight of the silicone polymer (including silicone rubber, silicone resin, etc.) as the base polymer.

[0094] [Urethane-based adhesive] The urethane adhesive is not particularly limited, and known or conventional urethane adhesives can be used. However, urethane adhesive compositions containing a polyol, a polyfunctional isocyanate compound, and a catalyst are preferred because they are easy to control to have low tackiness and low adhesiveness.

[0095] As the polyol, any suitable polyol having two or more hydroxyl groups can be used. Examples of such polyols include polyols having two hydroxyl groups (diols), polyols having three hydroxyl groups (triols), polyols having four hydroxyl groups (tetraols), polyols having five hydroxyl groups (pentaols), and polyols having six hydroxyl groups (hexaols). The polyol may be just one type or two or more types.

[0096] The polyol preferably contains a polyol with a number-average molecular weight (Mn) of 400 to 20000. The content of the polyol with a number-average molecular weight (Mn) of 400 to 20000 in the total amount of polyol is preferably 50 to 100% by weight, more preferably 70 to 100% by weight, even more preferably 90 to 100% by weight, particularly preferably 95 to 100% by weight, and most preferably substantially 100% by weight. By adjusting the content of the polyol with a number-average molecular weight (Mn) of 400 to 20000 in the polyol within the above range, for example, a urethane-based adhesive with controlled low tackiness can be provided.

[0097] Examples of the polyols include polyester polyols, polyether polyols, polycaprolactone polyols, polycarbonate polyols, and castor oil-based polyols.

[0098] The aforementioned polyester polyol can be obtained, for example, by an esterification reaction between a polyol component and an acid component.

[0099] Examples of the polyol component include ethylene glycol, diethylene glycol, 1,3-butanediol, 1,4-butanediol, neopentyl glycol, 3-methyl-1,5-pentanediol, 2-butyl-2-ethyl-1,3-propanediol, 2,4-diethyl-1,5-pentanediol, 1,2-hexanediol, 1,6-hexanediol, 1,8-octanediol, 1,9-nonanediol, 2-methyl-1,8-octanediol, 1,8-decanediol, octadecanediol, glycerin, trimethylolpropane, pentaerythritol, hexanetriol, and polypropylene glycol.

[0100] Examples of the aforementioned acidic components include succinic acid, methylsuccinic acid, adipic acid, pimelic acid, azelaic acid, sebacic acid, 1,12-dodecanediic acid, 1,14-tetradecanediic acid, dimer acid, 2-methyl-1,4-cyclohexanedicarboxylic acid, 2-ethyl-1,4-cyclohexanedicarboxylic acid, terephthalic acid, isophthalic acid, phthalic acid, isophthalic acid, terephthalic acid, 1,4-naphthalenedicarboxylic acid, 4,4'-biphenyldicarboxylic acid, and their acid anhydrides.

[0101] Examples of the aforementioned polyether polyols include polyether polyols obtained by addition polymerization of alkylene oxides such as ethylene oxide, propylene oxide, and butylene oxide, using water, low molecular weight polyols (propylene glycol, ethylene glycol, glycerin, trimethylolpropane, pentaerythritol, etc.), bisphenols (bisphenol A, etc.), and dihydroxybenzene (catechol, resorcinol, hydroquinone, etc.) as initiators. Specifically, examples include polyethylene glycol, polypropylene glycol, and polytetramethylene glycol.

[0102] Examples of the polycaprolactone polyols include caprolactone-based polyester diols obtained by ring-opening polymerization of cyclic ester monomers such as ε-caprolactone and σ-valerolactone.

[0103] Examples of the polycarbonate polyols include: polycarbonate polyols obtained by polycondensation reaction of the polyol component with phosgene; polycarbonate polyols obtained by transesterification condensation of the polyol component with diesters such as dimethyl carbonate, diethyl carbonate, dipropyl carbonate, diisopropyl carbonate, dibutyl carbonate, ethylbutyl carbonate, ethylene carbonate, propylene carbonate, diphenyl carbonate, and dibenzyl carbonate; copolymerized polycarbonate polyols obtained by using two or more of the polyol components in combination; polycarbonate polyols obtained by esterification reaction of the various polycarbonate polyols with carboxyl group-containing compounds; and various Examples include: polycarbonate polyols obtained by etherification reaction of a polycarbonate polyol with a hydroxyl group-containing compound; polycarbonate polyols obtained by transesterification reaction of the aforementioned polycarbonate polyols with ester compounds; polycarbonate polyols obtained by transesterification reaction of the aforementioned polycarbonate polyols with hydroxyl group-containing compounds; polyester-based polycarbonate polyols obtained by polycondensation reaction of the aforementioned polycarbonate polyols with dicarboxylic acid compounds; copolymerized polyether-based polycarbonate polyols obtained by copolymerization of the aforementioned polycarbonate polyols with alkylene oxides; and the like.

[0104] Examples of the castor oil-based polyols include castor oil-based polyols obtained by reacting castor oil fatty acids with the polyol component. Specifically, examples include castor oil-based polyols obtained by reacting castor oil fatty acids with polypropylene glycol.

[0105] As the polyol, it is preferable to use a polyol (triol) having three hydroxyl groups as an essential component, from the viewpoint of low adhesion, low tackiness, and wettability of the first adhesive layer to electronic components. The polyol (triol) having three hydroxyl groups is preferably present in an amount of 50 to 100% by weight, and more preferably 70 to 100% by weight, relative to the total amount of components constituting the polyol.

[0106] Examples of the aforementioned polyfunctional isocyanate compounds include aliphatic polyisocyanates, alicyclic polyisocyanates, and aromatic polyisocyanate compounds.

[0107] Examples of the aliphatic polyisocyanates include trimethylene diisocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate, pentamethylene diisocyanate, 1,2-propylene diisocyanate, 1,3-butylene diisocyanate, dodecamethylene diisocyanate, and 2,4,4-trimethylhexamethylene diisocyanate.

[0108] Examples of the alicyclic polyisocyanates include 1,3-cyclopentene diisocyanate, 1,3-cyclohexane diisocyanate, 1,4-cyclohexane diisocyanate, isophorone diisocyanate, hydrogenated diphenylmethane diisocyanate, hydrogenated xylylene diisocyanate, hydrogenated tolylene diisocyanate, and hydrogenated tetramethylxylylene diisocyanate.

[0109] Examples of the aromatic polyisocyanates include phenylenediisocyanate, 2,4-tolylenediisosoanate, 2,6-tolylenediisosoanate, 2,2'-diphenylmethanediisocyanate, 4,4'-diphenylmethanediisocyanate, 4,4'-toluidinediisocyanate, 4,4'-diphenyletherdiisocyanate, 4,4'-diphenyldiisocyanate, 1,5-naphthalenediisocyanate, xylylenediisocyanate, and the like.

[0110] Among these, aliphatic polyisocyanates and their modified forms are preferred. Compared to other isocyanate-based crosslinking agents, aliphatic polyisocyanates and their modified forms have a highly flexible crosslinking structure and are easy to control to have low tackiness and low adhesion. Among aliphatic polyisocyanates and their modified forms, hexamethylene diisocyanates and their modified forms are particularly preferred.

[0111] From the viewpoint of low adhesion, low tackiness, and wettability of the first adhesive layer to electronic components, the polyfunctional isocyanate compound and the polyol preferably have an equivalent ratio (NCO / OH) of isocyanate groups of the polyfunctional isocyanate compound and hydroxyl groups of the polyol of 1 to 5, more preferably 1.1 to 3, and even more preferably 1.2 to 2.

[0112] The urethane adhesive composition preferably contains a catalyst such as an iron-based compound and / or a tin-based compound. Specifically, tin-based catalysts such as dibutyltin dilaurate and dioctyltin dilaurate, tris(acetylacetonate) iron, tris(hexane-2,4-dionato) iron, tris(heptane-2,4-dionato) iron, tris(heptane-3,5-dionato) iron, tris(5-methylhexane-2,4-dionato) iron, tris(octane-2,4-dionato) iron, and tris(6-methylheptane-2 ,4-dionato) iron, tris(2,6-dimethylheptane-3,5-dionato) iron, tris(nonane-2,4-dionato) iron, tris(nonane-4,6-dionato) iron, tris(2,2,6,6-tetramethylheptane-3,5-dionato) iron, tris(tridecane-6,8-dionato) iron, tris(1-phenylbutane-1,3-dionato) iron, tris(hexafluoroacetylacetonate Examples of iron-based catalysts include iron, tris(acetate acetate)ferrous iron, tris(acetoacetate-n-propyl)ferrous iron, tris(acetoacetate-isopropyl)ferrous iron, tris(acetoacetate-n-butyl)ferrous iron, tris(acetoacetate-sec-butyl)ferrous iron, tris(acetoacetate-tert-butyl)ferrous iron, tris(propionylacetate-methyl)ferrous iron, tris(propionylacetate-n-propyl)ferrous iron, tris(propionylacetate-isopropyl)ferrous iron, tris(propionylacetate-n-butyl)ferrous iron, tris(propionylacetate-sec-butyl)ferrous iron, tris(propionylacetate-tert-butyl)ferrous iron, tris(acetoacetate benzyl)ferrous iron, tris(malonate dimethyl)ferrous iron, tris(malonate diethyl)ferrous iron, trimethoxyferrous iron, triethoxyferrous iron, triisopropoxyferrous iron, and ferric chloride.

[0113] The amount of catalyst contained in the urethane-based adhesive composition is preferably 0.002 to 0.5 parts by weight, more preferably 0.005 to 0.3 parts by weight, and even more preferably 0.01 to 0.1 parts by weight, per 100 parts by weight of polyol. Within this range, the crosslinking reaction rate is fast when the adhesive layer is formed, and the pot life of the adhesive composition is also extended, resulting in a desirable embodiment.

[0114] Furthermore, as a urethane-based adhesive, a urethane-based adhesive composition containing a urethane prepolymer is also preferred because it is easier to control its low tackiness and low adhesiveness.

[0115] Examples of urethane-based adhesive compositions containing a urethane prepolymer include adhesive compositions containing a polyurethane polyol as the urethane prepolymer and a polyfunctional isocyanate compound. The urethane prepolymer may be one type or two or more types. The polyfunctional isocyanate compound may be one type or two or more types.

[0116] The polyurethane polyol used as a urethane prepolymer is preferably obtained by reacting a polyester polyol and a polyether polyol with an organic polyisocyanate compound in the presence or absence of a catalyst.

[0117] Any suitable polyester polyol can be used as the polyester polyol. Examples of such polyester polyols include those obtained by reacting an acid component with a glycol component. Examples of acid components include terephthalic acid, adipic acid, azelaic acid, sebatic acid, phthalic anhydride, isophthalic acid, and trimellitic acid. Examples of glycol components include ethylene glycol, propylene glycol, diethylene glycol, butylene glycol, 1,6-hexane glycol, 3-methyl-1,5-pentanediol, 3,3'-dimethylolheptane, polyoxyethylene glycol, polyoxypropylene glycol, 1,4-butanediol, neopentyl glycol, and butylethylpentanediol. Examples of polyol components include glycerin, trimethylolpropane, and pentaerythritol. Other examples of polyester polyols include those obtained by ring-opening polymerization of lactones such as polycaprolactone, poly(β-methyl-γ-valerolactone), and polyvalerolactone.

[0118] Polyester polyols can be used with molecular weights ranging from low to high. Preferably, the number average molecular weight of the polyester polyol is 500 to 5000. If the number average molecular weight is less than 500, the reactivity may increase, potentially leading to gelation. If the number average molecular weight exceeds 5000, the reactivity may decrease, and furthermore, the cohesive force of the polyurethane polyol itself may weaken. The amount of polyester polyol used is preferably 10 to 90 mol% of the polyol constituting the polyurethane polyol.

[0119] Any suitable polyether polyol can be used as the polyether polyol. Examples of such polyether polyols include those obtained by polymerizing oxirane compounds such as ethylene oxide, propylene oxide, butylene oxide, and tetrahydrofuran using a low molecular weight polyol such as water, propylene glycol, ethylene glycol, glycerin, or trimethylolpropane as an initiator. Specifically, examples of such polyether polyols include polyether polyols with two or more functional groups, such as polypropylene glycol, polyethylene glycol, and polytetramethylene glycol.

[0120] Polyether polyols can be used with molecular weights ranging from low to high. Preferably, the number average molecular weight of the polyether polyol is between 1000 and 5000. If the number average molecular weight is less than 1000, the reactivity may increase, potentially leading to gelation. If the number average molecular weight exceeds 5000, the reactivity may decrease, and furthermore, the cohesive force of the polyurethane polyol itself may weaken. The amount of polyether polyol used is preferably 20 to 80 mol% of the polyol constituting the polyurethane polyol.

[0121] Polyether polyols can be used in combination with glycols such as ethylene glycol, 1,4-butanediol, neopentyl glycol, butylethylpentanediol, glycerin, trimethylolpropane, and pentaerythritol, or with polyhydric amines such as ethylenediamine, N-aminoethylethanolamine, isophoronediamine, and xylylenediamine, as needed.

[0122] As the polyether polyol, only difunctional polyether polyols may be used, or some or all of a polyether polyol having a number average molecular weight of 1000 to 5000 and at least three hydroxyl groups per molecule may be used. When some or all of a polyether polyol having an average molecular weight of 1000 to 5000 and at least three hydroxyl groups per molecule is used as the polyether polyol, a good balance between adhesiveness and re-peelability can be achieved. In such polyether polyols, if the number average molecular weight is less than 1000, the reactivity may increase, and gelation may become more likely. In such polyether polyols, if the number average molecular weight exceeds 5000, the reactivity may decrease, and furthermore, the cohesive force of the polyurethane polyol itself may decrease. The number average molecular weight of such polyether polyols is more preferably 2500 to 3500.

[0123] Any suitable organic polyisocyanate compound can be used as the organic polyisocyanate compound. Examples of such organic polyisocyanate compounds include aromatic polyisocyanates, aliphatic polyisocyanates, aromatic aliphatic polyisocyanates, and alicyclic polyisocyanates.

[0124] Examples of aromatic polyisocyanates include 1,3-phenylenediisocyanate, 4,4'-diphenyldiisocyanate, 1,4-phenylenediisocyanate, 4,4'-diphenylmethanediisocyanate, 2,4-tolylenediisocyanate, 2,6-tolylenediisocyanate, 4,4'-toluidinediisocyanate, 2,4,6-triisocyanatetoluene, 1,3,5-triisocyanatebenzene, dianisidinediisocyanate, 4,4'-diphenyletherdiisocyanate, and 4,4',4"-triphenylmethanetriisocyanate.

[0125] Examples of aliphatic polyisocyanates include trimethylene diisocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate, pentamethylene diisocyanate, 1,2-propylene diisocyanate, 2,3-butylene diisocyanate, 1,3-butylene diisocyanate, dodecamethylene diisocyanate, and 2,4,4-trimethylhexamethylene diisocyanate.

[0126] Examples of aromatic aliphatic polyisocyanates include ω,ω'-diisocyanate-1,3-dimethylbenzene, ω,ω'-diisocyanate-1,4-dimethylbenzene, ω,ω'-diisocyanate-1,4-diethylbenzene, 1,4-tetramethylxylylenediisocyanate, and 1,3-tetramethylxylylenediisocyanate.

[0127] Examples of alicyclic polyisocyanates include 3-isocyanate methyl-3,5,5-trimethylcyclohexyl isocyanate, 1,3-cyclopentane diisocyanate, 1,3-cyclohexane diisocyanate, 1,4-cyclohexane diisocyanate, methyl-2,4-cyclohexane diisocyanate, methyl-2,6-cyclohexane diisocyanate, 4,4'-methylenebis(cyclohexyl isocyanate), 1,4-bis(isocyanate methyl)cyclohexane, and 1,4-bis(isocyanate methyl)cyclohexane.

[0128] Organic polyisocyanate compounds such as trimethylolpropane adducts, biuret compounds obtained by reaction with water, and trimers having an isocyanurate ring can also be used in combination.

[0129] Any suitable catalyst can be used to obtain polyurethane polyols. Examples of such catalysts include tertiary amine compounds and organometallic compounds.

[0130] Examples of tertiary amine compounds include triethylamine, triethylenediamine, and 1,8-diazabicyclo[5.4.0]-undecene-7(DBU).

[0131] Examples of organometallic compounds include tin compounds and non-tin compounds.

[0132] Examples of tin-based compounds include dibutyltin dichloride, dibutyltin oxide, dibutyltin dibromide, dibutyltin dimaleate, dibutyltin dilaurate (DBTDL), dibutyltin diacetate, dibutyltin sulfide, tributyltin sulfide, tributyltin oxide, tributyltin acetate, triethyltin ethoxide, tributyltin ethoxide, dioctyltin oxide, tributyltin chloride, tributyltin trichloroacetate, and tin 2-ethylhexanoate.

[0133] Examples of non-tin compounds include titanium compounds such as dibutyltitanium dichloride, tetrabutyltitanate, and butoxytitanium trichloride; lead compounds such as lead oleate, lead 2-ethylhexanoate, lead benzoate, and lead naphthenate; iron compounds such as iron 2-ethylhexanoate and iron acetylacetonate; cobalt compounds such as cobalt benzoate and cobalt 2-ethylhexanoate; zinc compounds such as zinc naphthenate and zinc 2-ethylhexanoate; and zirconium compounds such as zirconium naphthenate.

[0134] When using a catalyst to obtain polyurethane polyols, systems containing two types of polyols, polyester polyols and polyether polyols, tend to exhibit problems such as gelation and turbidity of the reaction solution due to their differing reactivity when using a single catalyst. Therefore, using two types of catalysts when obtaining polyurethane polyols makes it easier to control the reaction rate and catalyst selectivity, thereby resolving these issues. Examples of such two-catalyst combinations include tertiary amine / organometallic, tin / non-tin, and tin / tin. Preferably, it is tin / tin, and more preferably a combination of dibutyltin dilaurate and tin 2-ethylhexanoate. The weight ratio of tin 2-ethylhexanoate / dibutyltin dilaurate is preferably less than 1, and more preferably 0.2 to 0.6. A ratio of 1 or more may increase the likelihood of gelation due to the balance of catalytic activity.

[0135] When a catalyst is used to obtain polyurethane polyols, the amount of catalyst used is preferably 0.01 to 1.0% by weight relative to the total amount of polyester polyol, polyether polyol, and organic polyisocyanate compound.

[0136] When a catalyst is used to obtain polyurethane polyols, the reaction temperature is preferably less than 100°C, and more preferably 85°C to 95°C. Above 100°C, it may become difficult to control the reaction rate and crosslinking structure, potentially making it difficult to obtain polyurethane polyols with a predetermined molecular weight.

[0137] A catalyst may not be used to obtain polyurethane polyols. In that case, the reaction temperature is preferably 100°C or higher, and more preferably 110°C or higher. Furthermore, when obtaining polyurethane polyols without a catalyst, it is preferable to allow the reaction to proceed for 3 hours or more.

[0138] Methods for obtaining polyurethane polyols include, for example, 1) a method of charging polyester polyol, polyether polyol, catalyst, and organic polyisocyanate into a volumetric flask, and 2) a method of charging polyester polyol, polyether polyol, and catalyst into a flask and adding organic polyisocyanate dropwise. Method 2) is preferred for controlling the reaction when obtaining polyurethane polyols.

[0139] Any suitable solvent can be used to obtain polyurethane polyols. Examples of such solvents include methyl ethyl ketone, ethyl acetate, toluene, xylene, and acetone. Among these solvents, toluene is preferred.

[0140] As polyfunctional isocyanate compounds, those mentioned above can be used.

[0141] As a method for producing a polyurethane-based composition obtained from a composition containing a urethane prepolymer, any suitable manufacturing method can be adopted, as long as it is a method of producing a polyurethane-based resin composition using a so-called "urethane prepolymer" as a raw material.

[0142] [Acrylic adhesive] The acrylic adhesive is not particularly limited, and known or conventional acrylic adhesives can be used. For example, an acrylic adhesive composition containing an acrylic polymer as a base polymer is recommended because it is easy to control low tackiness and low adhesiveness.

[0143] The above-mentioned acrylic polymer is a polymer that contains structural units derived from acrylic monomers (monomer components having a (meth)acryloyl group in the molecule) as structural units of the polymer. Preferably, the above-mentioned acrylic polymer is a polymer that contains the largest mass percentage of structural units derived from (meth)acrylic acid ester. Note that only one type of acrylic polymer may be used, or two or more types may be used. In this specification, "(meth)acrylic" means "acrylic" and / or "methacrylic" (either one or both of "acrylic" and "methacrylic"), and the same applies to other terms.

[0144] Examples of the above (meth)acrylic acid esters include hydrocarbon group-containing (meth)acrylic acid esters. Examples of hydrocarbon group-containing (meth)acrylic acid esters include (meth)acrylic acid alkyl esters, (meth)acrylic acid cycloalkyl esters, and (meth)acrylic acid aryl esters. Examples of the above (meth)acrylic acid alkyl esters include (meth)acrylic acid 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 (lauryl ester), tridecyl ester, tetradecyl ester, hexadecyl ester, octadecyl ester, and eicosyl ester. Examples of the above (meth)acrylic acid cycloalkyl esters include (meth)acrylic acid cyclopentyl ester and cyclohexyl ester. Examples of the above-mentioned aryl (meth)acrylate esters include phenyl esters and benzyl esters of (meth)acrylic acid.

[0145] The hydrocarbon group-containing (meth)acrylic acid ester described above may be used by one type or by two or more types. To appropriately exhibit the basic properties such as tackiness due to the hydrocarbon group-containing (meth)acrylic acid ester in the first adhesive layer, and to easily control low tackiness and low adhesiveness, the proportion of hydrocarbon group-containing (meth)acrylic acid ester in the total monomer components for forming the acrylic polymer is preferably 40% by mass or more, and more preferably 60% by mass or more.

[0146] The above acrylic polymer may contain constituent units derived from other monomer components copolymerizable with the hydrocarbon group-containing (meth)acrylic acid ester for the purpose of modifying properties such as cohesiveness, heat resistance, tackiness, etc. Examples of the above other monomer components include 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, acrylonitrile and other functional group-containing monomers, vinyl ester monomers, etc. Examples of the above carboxyl group-containing monomers include acrylic acid, methacrylic acid, carboxyethyl (meth)acrylate, carboxypentyl (meth)acrylate, itaconic acid, maleic acid, fumaric acid, crotonic acid, etc. Examples of the above acid anhydride monomers include maleic anhydride, itaconic anhydride, etc. Examples of the above 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 the above glycidyl group-containing monomers include glycidyl (meth)acrylate and methylglycidyl (meth)acrylate. Examples of the above sulfonic acid group-containing monomers include styrene sulfonic acid, allyl sulfonic acid, 2-(meth)acrylamide-2-methylpropanesulfonic acid, (meth)acrylamidepropanesulfonic acid, sulfopropyl (meth)acrylate, and (meth)acryloyloxynaphthalenesulfonic acid. Examples of the above phosphate group-containing monomers include 2-hydroxyethyl acryloyl phosphate. Examples of the vinyl ester monomers mentioned above include vinyl acetate, vinyl propionate, vinyl butyrate, vinyl pivalate, vinyl cyclohexanecarboxylate, and vinyl benzoate. The other monomer components may be used individually or in combination of two or more.To appropriately exhibit basic properties such as tackiness due to hydrocarbon group-containing (meth)acrylic acid esters in the first adhesive layer, and to easily control low tackiness and low adhesiveness, the total proportion of the above-mentioned other monomer components in the total monomer components for forming the acrylic polymer is preferably 60% by mass or less, and more preferably 40% by mass or less.

[0147] The above-mentioned acrylic polymer may contain constituent units derived from polyfunctional monomers copolymerizable with monomer components that form the acrylic polymer, in order to form a crosslinked structure within its polymer backbone. Examples of the above-mentioned polyfunctional monomers include monomers having a (meth)acryloyl group and other reactive functional groups in the molecule, such as 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 (e.g., polyglycidyl(meth)acrylate), polyester(meth)acrylate, and urethane(meth)acrylate. Only one of the above-mentioned polyfunctional monomers may be used, or two or more may be used. To appropriately exhibit basic properties such as tackiness due to hydrocarbon group-containing (meth)acrylic acid esters in the first adhesive layer, and to easily control low tackiness and low adhesiveness, the proportion of the above-mentioned polyfunctional monomer in the total monomer components for forming the acrylic polymer is preferably 40% by mass or less, and more preferably 30% by mass or less.

[0148] Acrylic polymers are obtained by polymerizing one or more monomer components, including acrylic monomers. Polymerization methods include solution polymerization, emulsion polymerization, bulk polymerization, and suspension polymerization.

[0149] The mass-average molecular weight of the acrylic polymer is preferably 100,000 or more, and more preferably 200,000 to 3,000,000. When the mass-average molecular weight is 100,000 or more, there tends to be less low molecular weight material in the adhesive layer, which can further suppress contamination of electronic components and the like.

[0150] The acrylic adhesive composition forming the first adhesive layer may contain a crosslinking agent. For example, the acrylic polymer can be crosslinked to further reduce the amount of low molecular weight substances in the first adhesive layer. Furthermore, the mass-average molecular weight of the acrylic polymer can be increased, allowing for control of low tackiness and low adhesiveness. Examples of the crosslinking agent include polyisocyanate compounds, epoxy compounds, polyol compounds (such as polyphenol compounds), aziridine compounds, and melamine compounds, with isocyanate-based crosslinking agents and / or epoxy-based crosslinking agents being preferred. When using a crosslinking agent, the amount used is preferably about 20 parts by weight or less, and more preferably 0.1 to 15 parts by weight, per 100 parts by weight of the acrylic polymer.

[0151] Examples of isocyanate crosslinking agents include aliphatic isocyanates, alicyclic isocyanates, and aromatic isocyanates. Examples of aliphatic isocyanates include trimethylene diisocyanate, butylene diisocyanate, hexamethylene diisocyanate, and dimer acid diisocyanate. Examples of alicyclic isocyanates include cyclopentylene diisocyanate, cyclohexylene diisocyanate, isophorone diisocyanate, and 1,3-bis(isocyanatomethyl)cyclohexane. Examples of aromatic isocyanates include 2,4-tolylene diisocyanate, 4,4'-diphenylmethane diisocyanate, and xylylene diisocyanate. Other examples of isocyanate-based crosslinking agents include the trimethylolpropane adduct of tolylene diisocyanate (product name "Coronate L", manufactured by Tosoh Corporation) and the isocyanurate derivative of hexamethylene diisocyanate (product name "Coronate HX", manufactured by Tosoh Corporation).

[0152] Examples of epoxy crosslinking agents (polyfunctional epoxy compounds) include N,N,N',N'-tetraglycidyl-m-xylenediamine, diglycidylaniline, 1,3-bis(N,N-diglycidylaminomethyl)cyclohexane, 1,6-hexanediol diglycidyl ether, neopentyl glycol diglycidyl ether, ethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, polypropylene glycol diglycidyl ether, and sorbitol polyglycidyl ether. Examples include diglycidyl ether, glycerol polyglycidyl ether, pentaerythritol polyglycidyl ether, polyglycerol polyglycidyl ether, sorbitan polyglycidyl ether, trimethylolpropane polyglycidyl ether, diglycidyl adipate ester, diglycidyl o-phthalate ester, triglycidyl-tris(2-hydroxyethyl) isocyanurate, resorcinol diglycidyl ether, and bisphenol-S-diglycidyl ether. Epoxy resins having two or more epoxy groups in their molecules are also included. A commercially available epoxy crosslinking agent is, for example, "Tetrad C" manufactured by Mitsubishi Gas Chemical Company, Inc.

[0153] The adhesive composition constituting the first adhesive layer preferably contains a light release agent. By including a light release agent, a Weak Boundary Layer (WBL) is formed on the surface of the first adhesive layer, making it easier to control low tackiness and low adhesiveness.

[0154] The light stripping agent is not particularly limited, and any known light stripping agent can be used without restriction. Examples include silicone-based stripping agents, fluorine-based surfactants, and aliphatic esters, which can be used individually or in combination of two or more.

[0155] The above-mentioned silicone-based release agent is not particularly limited, but examples include thermosetting silicone-based release agents and ionizing radiation-curable silicone-based release agents. Furthermore, the silicone-based release agent may be either a solvent-free type that does not contain a solvent, or a solvent-based type that is dissolved or dispersed in an organic solvent. The silicone-based release agent can be used alone or in combination of two or more types.

[0156] The above-mentioned thermosetting silicone-based release agent is not particularly limited, but it is preferable that it contains an organohydrogenpolysiloxane and an organopolysiloxane having an aliphatic unsaturated group. Furthermore, it is preferable that the above-mentioned silicone-based release agent is a thermoaddition reaction curable silicone-based release agent that hardens by crosslinking due to a thermal addition reaction.

[0157] The above-mentioned heat-curable silicone-based release agent is not particularly limited, but preferably includes a polysiloxane having hydrogen atoms (H) bonded to silicon atoms (Si) in its molecule (Si-H group-containing polysiloxane) and a polysiloxane containing a functional group that is reactive to Si-H bonds (Si-H group-reactive functional group) in its molecule (Si-H group-reactive polysiloxane). This release agent hardens by crosslinking through an addition reaction between the Si-H group and the Si-H group-reactive functional group.

[0158] In the above Si-H group-containing polysiloxane, the Si to which H is bonded may be either Si in the main chain or Si in the side chain. The above Si-H group-containing polysiloxane is preferably a polysiloxane containing two or more Si-H groups in its molecule. Examples of polysiloxanes containing two or more Si-H groups include dimethylhydrogensiloxane polymers such as poly(dimethylsiloxane-methylsiloxane).

[0159] Furthermore, as the Si-H group reactive polysiloxane described above, polysiloxanes in which a Si-H group reactive functional group or a side chain containing such a functional group is bonded to Si (for example, Si at the ends of the main chain, Si inside the main chain) that forms the main chain (backbone) of the siloxane polymer are preferred. Among these, polysiloxanes in which the Si-H group reactive functional group is directly bonded to Si in the main chain are preferred. Moreover, as the Si-H group reactive polysiloxane described above, polysiloxanes containing two or more Si-H group reactive functional groups in the molecule are also preferred.

[0160] Examples of Si-H group reactive functional groups in the above-mentioned Si-H group reactive polysiloxane include vinyl groups, alkenyl groups such as hexenyl groups, and so on. Examples of siloxane polymers that form the main chain portion of the above-mentioned Si-H group reactive polysiloxane include polydialkylsiloxanes such as polydimethylsiloxane, polydiethylsiloxane, and polymethylethylsiloxane (the two alkyl groups may be the same or different); polyalkylarylsiloxanes; poly(dimethylsiloxane-methylsiloxane); polymers obtained by polymerizing multiple Si-containing monomers, and so on. Among these, polydimethylsiloxane is preferred as the siloxane polymer that forms the main chain portion.

[0161] In particular, the above-mentioned thermo-curable silicone-based release agent is preferably a thermo-curable silicone-based release agent that contains a polysiloxane containing two or more Si-H groups in its molecule and a polysiloxane containing two or more Si-H group-reactive functional groups in its molecule.

[0162] Furthermore, while the above-mentioned ionizing radiation-curable silicone-based release agent is not particularly limited, UV-curable silicone-based release agents that undergo a crosslinking reaction and harden upon ultraviolet (UV) irradiation are preferred.

[0163] The above UV-curable silicone-based release agent is a release agent that hardens upon UV irradiation through chemical reactions such as cationic polymerization, radical polymerization, radical addition polymerization, and hydrosilylation. A UV-curable silicone-based release agent that hardens by cationic polymerization is particularly preferred.

[0164] While not particularly limited, a preferred release agent is an epoxy group-containing polysiloxane in which at least two epoxy groups are bonded directly or via divalent groups (alkylene groups such as methylene groups and ethylene groups; alkylene oxygen groups such as ethylene oxygen groups and propylene oxygen groups) to Si forming the main chain (skeleton) of a siloxane polymer (e.g., Si at the ends of the main chain, Si inside the main chain) and / or Si included in the side chains. The manner in which these at least two epoxy groups are bonded to Si may be the same or different. That is, a preferred release agent is an epoxy group-containing polysiloxane containing two or more epoxy group-containing side chains of one or more types. Examples of epoxy group-containing side chains include glycidyl groups, glycidoxy groups (glycidyl oxy groups), 3,4-epoxycyclohexyl groups, and 2,3-epoxycyclopentyl groups. The epoxy group-containing polysiloxane may be linear, branched, or a mixture thereof.

[0165] In particular, in the transfer sheet of the second embodiment, from the viewpoint of easily controlling the first adhesive layer to have low tackiness and low adhesiveness, it is preferable to include a thermosetting silicone-based release agent in the silicone-based adhesive, and more preferably to include a thermoaddition reaction curable silicone-based release agent.

[0166] In the case where the first adhesive layer in the transfer sheet of the second embodiment contains a silicone-based adhesive, the content of the silicone-based release agent is not particularly limited, but is preferably 0.5 parts by weight or more and 100 parts by weight or less per 100 parts by weight of the silicone-based polymer which is the base polymer. When the content is 0.5 parts by weight or more, it is easier to obtain the effect of controlling the first adhesive layer to have low tackiness and low adhesiveness, and is more preferably 1 part by weight or more, and even more preferably 3 parts by weight or more. Furthermore, when the content is 100 parts by weight or less, it is easier to suppress the problem of insufficient adhesiveness being obtained and difficulty in receiving electronic components, and is more preferably 30 parts by weight or less, and even more preferably 25 parts by weight or less.

[0167] By using the aforementioned fluorine-based surfactant as a mild peeling agent, a mild peeling effect can be achieved due to the low surface free energy of the fluorine portion.

[0168] The above-mentioned fluorinated surfactants are not particularly limited, but examples include fluorinated oligomers, perfluorobutanesulfonates, perfluoroalkyl group-containing carboxylates, hexafluoropentane trimer derivative-containing sulfonates, hexafluoropentane trimer derivative-containing carboxylates, hexafluoropentane trimer derivative-containing quaternary ammonium salts, hexafluoropentane trimer derivative-containing betaines, hexafluoropentane trimer derivative-containing polyoxyethylene ethers, and so on, with fluorinated oligomers being preferred. The fluorinated surfactants can be used alone or in combination of two or more types.

[0169] Specific examples of the aforementioned fluorine-based surfactants include, for example, commercially available products with product names such as Megafac F-114, F-410 (both manufactured by DIC Corporation), Surflon S-211, S-221, S-231, S-232, S-233, S-241, S-242, S-243, S-420 (all manufactured by AGC Seimi Chemical Co., Ltd.), and Futergent 100, 100C, 110, 150, 150CH, 300, 310, 320, 400SW, 251, 212M, 215M, 250, 209F, 222F, 245F, 208G, 218GL, 240G, 212P, 220P, 228P, FTX-218, DFX-18 (all manufactured by Neos Corporation). These compounds may be used individually or in combination of two or more.

[0170] The weight-average molecular weight (Mw) of the fluorine-based oligomer is preferably 3500 or more, more preferably 5000 or more, even more preferably 10000 or more, and particularly preferably 20000 or more. When the weight-average molecular weight of the fluorine-based oligomer is 3500 or more, it becomes easier to control low tackiness and low adhesiveness. Furthermore, when the weight-average molecular weight is 20000 or more, foaming during the formulation of the adhesive (composition) can be suppressed, and the appearance after adhesive coating is excellent, which is preferable. In addition, the upper limit of the weight-average molecular weight (Mw) of the fluorine-based oligomer is preferably 200,000 or less, and more preferably 100,000 or less. Setting it to 200,000 or less makes it easier for the fluorine-based oligomer to be unevenly distributed on the surface, which is preferable as it makes it easier to exhibit a light peeling effect.

[0171] Furthermore, as for the fluorine-based oligomers, for example, commercially available products with product names such as Megafack F-251, F-253, F-281, F-410, F-430, F-444, F-477, F-510, F-511, F-551, F-552, F-553, F-554, F-555, F-556, F-557, F-558, F-559, F-560, and F-56 Examples include F-562, F-563, F-565, F-568, F-569, F-570, F-571, F-572 (all manufactured by DIC Corporation), Surflon S-611, S-651, S-386 (all manufactured by AGC Seimi Chemical Co., Ltd.), and Futergent 610FM, 710FL, 710FM, 710FS, 730FL, 730LM (all manufactured by Neos Corporation). These compounds may be used individually or in combination of two or more.

[0172] When the first adhesive layer contains a fluorinated surfactant, the amount of the fluorinated surfactant is not particularly limited, but is preferably 0.01 parts by weight or more and 5 parts by weight or less per 100 parts by weight of the silicone polymer, which is the base polymer. When the amount is 0.01 parts by weight or more, it is easier to control the first adhesive layer to have low tackiness and low adhesiveness, and is more preferably 0.05 parts by weight or more, and even more preferably 0.1 parts by weight or more. Furthermore, when the amount is 5 parts by weight or less, it is easier to suppress the problem of insufficient adhesiveness and difficulty in receiving electronic components, and from the viewpoint of suppressing a decrease in transparency, it is more preferably 3 parts by weight or less, and even more preferably 2 parts by weight or less.

[0173] By including a fatty acid ester in the adhesive composition constituting the first adhesive layer, low tackiness, low adhesion, and wettability of the first adhesive layer to electronic components can be expected.

[0174] Examples of the aforementioned fatty acid esters include polyoxyethylene bisphenol A laurate, butyl stearate, 2-ethylhexyl palmitate, 2-ethylhexyl stearate, monoglyceride behenic acid, cetyl 2-ethylhexanoate, isopropyl myristate, isopropyl palmitate, cholesteryl isostearate, lauryl methacrylate, methyl coconut fatty acid, methyl laurate, methyl oleate, methyl stearate, myristyl myristate, octyldodecyl myristate, pentaerythritol monooleate, pentaerythritol monostearate, pentaerythritol tetrapalmitate, stearyl stearate, isotridecyl stearate, triglyceride 2-ethylhexanoate, butyl laurate, octyl oleate, and tridecyl isononanoate. The fatty acid ester may be one type or two or more types.

[0175] The amount of fatty acid ester contained in the urethane-based adhesive composition is preferably 1 to 50 parts by weight, more preferably 2 to 40 parts by weight, and even more preferably 3 to 30 parts by weight, per 100 parts by weight of polyol, from the viewpoint of low tackiness, low wettability, and staining of the adherend of the first adhesive layer to electronic components.

[0176] If the adhesive composition constituting the first adhesive layer contains a light release agent, the content (total amount) thereof is preferably 0.1 parts by weight or more, more preferably 1 part by weight or more, and even more preferably 3 parts by weight or more, per 100 parts by weight of the base polymer, from the viewpoint of low adhesion, low tack, wettability, and contamination of electronic components of the first adhesive layer. From the viewpoint of preventing discoloration of the first adhesive layer, it is preferably 50 parts by weight or less, more preferably 30 parts by weight or less, and even more preferably 10 parts by weight or less.

[0177] The first adhesive layer may contain an ultraviolet absorber. When the first adhesive layer contains an ultraviolet absorber, discoloration due to irradiation with active energy rays can be suppressed. Therefore, when the first adhesive layer receives electronic components, or when processing using active energy ray irradiation such as laser light irradiation is performed after receiving components, discoloration of the transfer sheet can be prevented.

[0178] The UV absorber is not particularly limited, but examples include triazine-based UV absorbers, benzotriazole-based UV absorbers, benzophenone-based UV absorbers, oxybenzophenone-based UV absorbers, salicylic acid ester-based UV absorbers, and cyanoacrylate-based UV absorbers, and these can be used individually or in combination of two or more. Among these, triazine-based UV absorbers and benzotriazole-based UV absorbers are preferred, and it is preferable that at least one UV absorber is selected from the group consisting of triazine-based UV absorbers having two or fewer hydroxyl groups in one molecule and benzotriazole-based UV absorbers having one benzotriazole skeleton in one molecule, because they have good solubility in monomers used to form acrylic adhesive compositions and have high UV absorption capacity around a wavelength of 380 nm.

[0179] Triazine-based UV absorbers having two or fewer hydroxyl groups in one molecule include, specifically, 2,4-bis-[{4-(4-ethylhexyloxy)-4-hydroxy}-phenyl]-6-(4-methoxyphenyl)-1,3,5-triazine (Tinosorb S, manufactured by BASF), 2,4-bis[2-hydroxy-4-butoxyphenyl]-6-(2,4-dibutoxyphenyl)-1,3,5-triazine (TINUVIN 460, manufactured by BASF), and 2-(4,6-bis(2,4-dimethylphenyl)-1,3,5-triazine-2-yl)-5-hydroxyphenyl and [(C 10 -C 16 (mainly C 12 -C 13Reaction product with alkyloxy)methyl]oxirane (TINUVIN400, BASF), 2-[4,6-bis(2,4-dimethylphenyl)-1,3,5-triazine-2-yl]-5-[3-(dodecyloxy)-2-hydroxypropoxy]phenol), reaction product of 2-(2,4-dihydroxyphenyl)-4,6-bis-(2,4-dimethylphenyl)-1,3,5-triazine and (2-ethylhexyl)-glycidic acid ester (TINUVIN405, BASF), 2-(4,6-diphenyl-1,3,5-triazine-2-yl)-5-[(hexyl)oxy]-phenol (TINUVIN1577, BASF), 2-(4,6-diphenyl-1,3,5-triazine-2-yl)-5-[2-(2-ethylhexanoyloxy)ethoxy]-phenol (ADK STAB Examples include LA46 (manufactured by ADEKA) and 2-(2-hydroxy-4-[1-octyloxycarbonylethoxy]phenyl)-4,6-bis(4-phenylphenyl)-1,3,5-triazine (TINUVIN479, manufactured by BASF).

[0180] Furthermore, examples of benzotriazole-based UV absorbers having one benzotriazole skeleton in one molecule include 2-(2H-benzotriazole-2-yl)-6-(1-methyl-1-phenylethyl)-4-(1,1,3,3-tetramethylbutyl)phenol (TINUVIN 928, manufactured by BASF), 2-(2-hydroxy-5-tert-butylphenyl)-2H-benzotriazole (TINUVIN PS, manufactured by BASF), benzenepropanoic acid, and 3-(2H-benzotriazole-2-yl)-5-(1,1-dimethylethyl)-4-hydroxy(C 7-9Ester compounds of side chains and linear alkyls (TINUVIN384-2, BASF), 2-(2H-benzotriazol-2-yl)-4,6-bis(1-methyl-1-phenylethyl)phenol (TINUVIN900, BASF), 2-(2H-benzotriazol-2-yl)-6-(1-methyl-1-phenylethyl)-4-(1,1,3,3-tetramethylbutyl)phenol (TINUVIN928, BASF), reaction product of methyl-3-(3-(2H-benzotriazol-2-yl)-5-t-butyl-4-hydroxyphenyl)propionate / polyethylene glycol 300 (TINUVIN1130, BASF), 2-(2H-benzotriazol-2-yl)-p-cresol (TINUVIN P (manufactured by BASF), 2(2H-benzotriazol-2-yl)-4-6-bis(1-methyl-1-phenylethyl)phenol (TINUVIN234, manufactured by BASF), 2-[5-chloro(2H)-benzotriazol-2-yl]-4-methyl-6-(tert-butyl)phenol (TINUVIN326, manufactured by BASF), 2-(2H-benzotriazol-2-yl)-4,6-di-tert-pentylphenol (TINUVIN328, manufactured by BASF), 2-(2H-benzotriazol-2-yl)-4-(1,1,3,3-tetramethylbutyl)phenol (TINUVIN234, manufactured by BASF). Examples include N329 (manufactured by BASF), reaction product of methyl 3-(3-(2H-benzotriazol-2-yl)-5-tert-butyl-4-hydroxyphenyl)propionate and polyethylene glycol 300 (TINUVIN 213, manufactured by BASF), 2-(2H-benzotriazol-2-yl)-6-dodecyl-4-methylphenol (TINUVIN 571, manufactured by BASF), and 2-[2-hydroxy-3-(3,4,5,6-tetrahydrophthalimidomethyl)-5-methylphenyl]benzotriazole (Sumisorb 250, manufactured by Sumitomo Chemical Co., Ltd.).

[0181] Furthermore, examples of the benzophenone-based ultraviolet absorbers (benzophenone compounds) and oxybenzophenone-based ultraviolet absorbers (oxybenzophenone compounds) include 2,4-dihydroxybenzophenone, 2-hydroxy-4-methoxybenzophenone, 2-hydroxy-4-methoxybenzophenone-5-sulfonic acid (anhydrous and trihydrate), 2-hydroxy-4-octyloxybenzophenone, 4-dodecyloxy-2-hydroxybenzophenone, 4-benzyloxy-2-hydroxybenzophenone, 2,2',4,4'-tetrahydroxybenzophenone, and 2,2'-dihydroxy-4,4-dimethoxybenzophenone.

[0182] Examples of the salicylic acid ester-based ultraviolet absorbers (salicylic acid ester compounds) include phenyl-2-acryloyloxybenzoate, phenyl-2-acryloyloxy-3-methylbenzoate, phenyl-2-acryloyloxy-4-methylbenzoate, phenyl-2-acryloyloxy-5-methylbenzoate, phenyl-2-acryloyloxy-3-methoxybenzoate, phenyl-2-hydroxybenzoate, phenyl-2-hydroxy-3-methylbenzoate, phenyl-2-hydroxy-4-methylbenzoate, phenyl-2-hydroxy-5-methylbenzoate, phenyl-2-hydroxy-3-methoxybenzoate, and 2,4-di-tert-butylphenyl-3,5-di-tert-butyl-4-hydroxybenzoate (TINUVIN120, manufactured by BASF).

[0183] Examples of the cyanoacrylate-based ultraviolet absorbers (cyanoacrylate compounds) include alkyl-2-cyanoacrylate, cycloalkyl-2-cyanoacrylate, alkoxyalkyl-2-cyanoacrylate, alkenyl-2-cyanoacrylate, and alkynyl-2-cyanoacrylate.

[0184] The maximum absorption wavelength in the absorption spectrum of the UV absorber is preferably in the wavelength region of 300 to 400 nm, and more preferably in the wavelength region of 320 to 380 nm.

[0185] The UV absorber may be used alone or in a mixture of two or more types. From the viewpoint of preventing discoloration due to irradiation with active energy rays, the amount of UV absorber contained in the adhesive composition is preferably 0.01 to 10 parts by weight, more preferably 0.03 to 5 parts by weight, and even more preferably 0.1 to 3 parts by weight per 100 parts by weight of the adhesive composition.

[0186] The first adhesive layer may contain an antioxidant. When the first adhesive layer contains an antioxidant, deterioration such as discoloration during storage of the transfer sheet of the second embodiment can be suppressed.

[0187] Examples of the aforementioned antioxidants include phenolic, phosphorus-based, sulfur-based, and amine-based antioxidants, and at least one selected from these is used. Among these, phenolic antioxidants are preferred, and hindered phenolic antioxidants are particularly preferred.

[0188] Specific examples of phenolic antioxidants include monocyclic phenol compounds such as 2,6-di-t-butyl-p-cresol, 2,6-di-t-butyl-4-ethylphenol, 2,6-dicyclohexyl-4-methylphenol, 2,6-diisopropyl-4-ethylphenol, 2,6-di-t-amyl-4-methylphenol, 2,6-di-t-octyl-4-n-propylphenol, 2,6-dicyclohexyl-4-n-octylphenol, 2-isopropyl-4-methyl-6-t-butylphenol, 2-t-butyl-4-ethyl-6-t-octylphenol, 2-isobutyl-4-ethyl-6-t-hexylphenol, 2-cyclohexyl-4-n-butyl-6-isopropylphenol, styrene-mixed cresol, DL-α-tocopherol, and stearyl β-(3,5-di-t-butyl-4-hydroxyphenyl)propionate, which are bicyclic phenolic compounds. Examples of phenolic compounds include 2,2'-methylenebis(4-methyl-6-t-butylphenol), 4,4'-butylidenebis(3-methyl-6-t-butylphenol), 4,4'-thiobis(3-methyl-6-t-butylphenol), 2,2'-thiobis(4-methyl-6-t-butylphenol), 4,4'-methylenebis(2,6-di-t-butylphenol), and 2,2'-methylenebis[6-(1-methylcyclohexyl )-p-cresol], 2,2'-ethylidenebis(4,6-di-t-butylphenol), 2,2'-butylidenebis(2-t-butyl-4-methylphenol), 3,6-dioxaoctamethylenebis[3-(3-t-butyl-4-hydroxy-5-methylphenyl)propionate], triethylene glycol bis[3-(3-t-butyl-5-methyl-4-hydroxyphenyl)propionate], 1,6-hexanediol Bis[3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate], 2,2'-thiodiethylenebis[3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate], etc., as tri-ring phenol compounds, 1,1,3-tris(2-methyl-4-hydroxy-5-t-butylphenyl)butane, 1,3,5-tris(2,6-dimethyl-3-hydroxy-4-t-butylbenzyl)isocyanurate, 1,3,5-tris[(3,Examples of tetracyclic phenolic compounds include 5-di-t-butyl-4-hydroxyphenyl)propionyloxyethyl isocyanurate, tris(4-t-butyl-2,6-dimethyl-3-hydroxybenzyl)isocyanurate, and 1,3,5-trimethyl-2,4,6-tris(3,5-di-t-butyl-4-hydroxybenzyl)benzene; tetracyclic phenolic compounds include tetrakis[methylene-3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate]methane; and phosphorus-containing phenolic compounds include bis(3,5-di-t-butyl-4-hydroxybenzylphosphonate ethyl)calcium and bis(3,5-di-t-butyl-4-hydroxybenzylphosphonate ethyl)nickel.

[0189] The antioxidant may be used alone or in a mixture of two or more. From the viewpoint of suppressing deterioration such as discoloration during storage and the processability of the transfer sheet, the amount of antioxidant contained in the adhesive composition is preferably 0.01 to 10 parts by weight, more preferably 0.03 to 5 parts by weight, and even more preferably 0.1 to 3 parts by weight per 100 parts by weight of the adhesive composition.

[0190] The adhesive composition constituting the first adhesive layer may contain any other suitable components as long as they do not impair the effects of the present invention. Examples of such other components include tackifiers, inorganic fillers, organic fillers, metal powders, pigments, foils, softeners, plasticizers, conductive agents, surface lubricants, leveling agents, heat stabilizers, polymerization inhibitors, lubricants, solvents, and the like.

[0191] [Second adhesive layer] The second adhesive layer is an adhesive layer for temporary fixing to the carrier substrate, and is preferably made of a release adhesive layer. The configuration in which the second adhesive layer is made of a release adhesive layer is preferable because it allows the second adhesive layer to be peeled off from the carrier substrate without contamination such as adhesive residue, thereby improving reworkability. The second adhesive layer can be made into a release adhesive layer by adjusting its tackiness through the type and composition of the adhesive, the degree of crosslinking, etc., or by reducing its tackiness through physical stimuli such as heat, ultraviolet rays, or other electromagnetic waves.

[0192] The 180° peel-off adhesive strength of the second adhesive layer to the glass plate at 25°C is not particularly limited, but it is preferably 5000mN / 25mm or less, more preferably 3000mN / 25mm or less, and even more preferably 1000mN / 25mm or less, from the viewpoint of being able to peel it off from the carrier substrate without contamination such as adhesive residue, and from the viewpoint of improving reworkability. Furthermore, from the viewpoint of adhesion of the carrier substrate to the second adhesive layer, the 180° peel-off adhesive strength of the second adhesive layer to the glass plate at 25°C is preferably 1mN / 25mm or more, and more preferably 5mN / 25mm or more.

[0193] The 180° peel-off adhesive strength of the second adhesive layer at 25°C can be measured in the same manner as the first adhesive layer. The adhesive strength of the second adhesive layer can be adjusted by adjusting the type, composition, and degree of crosslinking of the constituent adhesives, or by forming a Weak Boundary Layer (WBL) by incorporating a light release agent or plasticizer.

[0194] The thickness of the second adhesive layer is not particularly limited, but is preferably 1 μm or more, and more preferably 3 μm or more. A thickness above a certain level is preferable because it makes it easier for the second adhesive layer to be stably fixed to the carrier substrate. Furthermore, the upper limit of the thickness of the second adhesive layer is not particularly limited, but is preferably 30 μm or less, and more preferably 20 μm or less. A thickness below a certain level makes it easier to peel the second adhesive layer from the carrier substrate, improving reworkability, which is preferable.

[0195] The haze of the second adhesive layer (according to JIS K7136) is not particularly limited, but is preferably 10% or less, and more preferably 5% or less. A haze of 10% or less is preferable because it provides excellent transparency, for example, improving the visibility of alignment marks formed by applying external stimuli to the transfer sheet of the second embodiment. The haze can be measured, for example, by forming the second adhesive layer on a release liner, leaving it at normal conditions (23°C, 50%RH) for at least 24 hours, peeling off the release liner, and attaching the sample to a glass slide (for example, one with a total light transmittance of 91.8% and a haze of 0.4%), using a haze meter (manufactured by Murakami Color Technology Laboratory Co., Ltd., product name "HM-150").

[0196] In the transfer sheet of the second embodiment, the total light transmittance of the second adhesive layer in the visible light wavelength range (according to JIS K7361-1) is not particularly limited, but is preferably 85% or more, and more preferably 88% or more. A total light transmittance of 85% or more provides excellent transparency, and is preferable because, for example, the visibility of alignment marks formed by applying an external stimulus to the transfer sheet of the second embodiment is improved. The total light transmittance can be measured, for example, by forming the second adhesive layer on a release liner, leaving it at normal conditions (23°C, 50%RH) for at least 24 hours, peeling off the release liner, and attaching the sample to a glass slide (for example, one with a total light transmittance of 91.8% and haze of 0.4%), using a haze meter (manufactured by Murakami Color Technology Laboratory Co., Ltd., product name "HM-150").

[0197] The adhesive constituting the second adhesive layer described above is not particularly limited, but examples include silicone-based adhesives, urethane-based adhesives, acrylic-based adhesives, rubber-based adhesives, polyester-based adhesives, polyamide-based adhesives, epoxy-based adhesives, vinyl alkyl ether-based adhesives, and fluorine-based adhesives, which are used in the first adhesive layer described above. Among these, silicone-based adhesives, urethane-based adhesives, and acrylic-based adhesives are preferred from the viewpoint of being able to be peeled off from the carrier substrate without contamination such as adhesive residue, improving reworkability, and having high transparency and good visibility of alignment marks, with urethane-based adhesives and acrylic-based adhesives being more preferred, and acrylic-based adhesives being even more preferred.

[0198] The second adhesive layer may be an adhesive layer whose adhesive strength can be intentionally reduced by external forces during the use of the transfer sheet of the second embodiment (adhesive strength reduction type adhesive layer), or it may be an adhesive layer whose adhesive strength is hardly or not reduced at all by external forces during the use of the transfer sheet (adhesive strength non-reduction type adhesive layer), and can be appropriately selected depending on the method and conditions for transferring electronic components using the transfer sheet of the second embodiment.

[0199] If the second adhesive layer is a type of adhesive layer whose adhesive strength can be reduced, it becomes possible to use the second adhesive layer in a state where it exhibits relatively high adhesive strength and a state where it exhibits relatively low adhesive strength during the manufacturing and use processes of the transfer sheet of the second embodiment. For example, in the process of the first adhesive layer receiving electronic components during the use of the transfer sheet of the second embodiment, it is possible to suppress and prevent the transfer sheet from lifting off the carrier substrate by utilizing the state in which the second adhesive layer exhibits relatively high adhesive strength. On the other hand, in the subsequent process of peeling the transfer sheet of the second embodiment from the carrier substrate, the reworkability can be improved by reducing the adhesive strength of the second adhesive layer.

[0200] Examples of adhesives that form such a tack-reducing adhesive layer include radiation-curable adhesives and heat-foaming adhesives. One type of adhesive may be used to form the tack-reducing adhesive layer, or two or more types of adhesives may be used.

[0201] As the above-mentioned radiation-curable adhesive, for example, an adhesive that hardens upon irradiation with electron beams, ultraviolet rays, alpha rays, beta rays, gamma rays, or X-rays can be used, and an adhesive that hardens upon irradiation with ultraviolet rays (ultraviolet-curable adhesive) can be used in particular preference.

[0202] Examples of the above-mentioned radiation-curable adhesives include additive-type radiation-curable adhesives containing a base polymer such as an acrylic polymer and radiation-polymerizable monomer components or oligomer components having radiation-polymerizable functional groups such as carbon-carbon double bonds.

[0203] As the base polymer, an acrylic polymer similar to that used in the first adhesive layer can be used. To appropriately express the basic properties such as tackiness due to hydrocarbon group-containing (meth)acrylic acid ester in the second adhesive layer, and to easily control tackiness and peelability, the proportion of hydrocarbon group-containing (meth)acrylic acid ester in the total monomer components for forming the acrylic polymer is preferably 40% by mass or more, and more preferably 60% by mass or more.

[0204] The above-mentioned acrylic polymer may contain a hydroxyl group-containing monomer. When the acrylic polymer in the second adhesive layer contains a hydroxyl group-containing monomer, an appropriate cohesive force is easily obtained in the second adhesive layer. From the viewpoint of achieving appropriate adhesion and cohesive force in the second adhesive layer, the proportion of the hydroxyl group-containing monomer in the above-mentioned acrylic polymer is, for example, 0.1 to 30% by mass, and preferably 0.5 to 20% by mass.

[0205] The above-mentioned acrylic polymer may contain a carboxyl group-containing monomer. When the acrylic polymer in the second adhesive layer contains a carboxyl group-containing monomer, it is easier to obtain adequate adhesive reliability in the second adhesive layer. From the viewpoint of achieving adequate adhesive reliability in the second adhesive layer, the proportion of the carboxyl group-containing monomer in the above-mentioned acrylic polymer is, for example, 0.1 to 30% by mass, and preferably 0.5 to 20% by mass.

[0206] The above-mentioned acrylic polymer may also contain a vinyl ester monomer. When the acrylic polymer in the second adhesive layer contains a vinyl ester monomer, an appropriate cohesive force is easily obtained in the second adhesive layer. From the viewpoint of achieving an appropriate cohesive force in the second adhesive layer, the proportion of the vinyl ester monomer in the above-mentioned acrylic polymer is, for example, 0.1 to 60% by mass, and preferably 0.5 to 50% by mass.

[0207] The acrylic adhesive composition forming the second adhesive layer may contain a crosslinking agent. For example, the acrylic polymer can be crosslinked to further reduce the amount of low molecular weight substances in the second adhesive layer. In addition, the mass-average molecular weight of the acrylic polymer can be increased to control low tackiness and release properties. Examples of the crosslinking agent include polyisocyanate compounds, epoxy compounds, polyol compounds (such as polyphenol compounds), aziridine compounds, melamine compounds, etc. When using an isocyanate-based crosslinking agent and / or epoxy-based crosslinking agent, the amount used is preferably about 10 parts by weight or less, and more preferably 0.1 to 10 parts by weight, per 100 parts by weight of the acrylic polymer.

[0208] The acrylic adhesive composition forming the second adhesive layer may contain a crosslinking accelerator. The type of crosslinking accelerator can be appropriately selected depending on the type of crosslinking agent used. In this specification, a crosslinking accelerator refers to a catalyst that increases the rate of the crosslinking reaction by the crosslinking agent. Examples of such crosslinking accelerators include tin (Sn)-containing compounds such as dioctyl tin dilaurate, dibutyl tin dilaurate, dibutyl tin diacetate, dibutyl tin diacetylacetonate, tetra-n-butyl tin, and trimethyl tin hydroxide; amines such as N,N,N',N'-tetramethylhexanediamine and triethylamine; and N-containing compounds such as imidazoles. Among these, Sn-containing compounds are preferred. The use of these crosslinking accelerators is particularly effective when a hydroxyl group-containing monomer is used as the sub-monomer and an isocyanate-based crosslinking agent is used as the crosslinking agent. The amount of crosslinking accelerator contained in the above adhesive composition can be, for example, about 0.001 to 0.5 parts by weight (preferably about 0.001 to 0.1 parts by weight) per 100 parts by weight of the acrylic polymer.

[0209] Examples of the above radiation-polymerizable monomer components include urethane (meth)acrylate, trimethylolpropane tri(meth)acrylate, pentaerythritol tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, dipentaerythritol monohydroxypenta(meth)acrylate, dipentaerythritol hexa(meth)acrylate, and 1,4-butanediol di(meth)acrylate. Examples of the above radiation-polymerizable oligomer components include various oligomers such as urethane-based, polyether-based, polyester-based, polycarbonate-based, and polybutadiene-based oligomers, with a molecular weight of approximately 100 to 30,000 being preferred. The content of the above radiation-curable monomer components and oligomer components in the radiation-curable adhesive forming the second adhesive layer is, for example, 5 to 500 parts by weight, preferably 40 to 150 parts by weight, per 100 parts by weight of the base polymer. Furthermore, as an additive-type radiation-curable adhesive, for example, the one disclosed in Japanese Patent Publication No. 60-196956 may be used.

[0210] The above-mentioned radiation-curable adhesives also include intrinsically charged radiation-curable adhesives containing a base polymer having radiation-polymerizable functional groups such as carbon-carbon double bonds in the polymer side chains, polymer main chain, or polymer main chain ends. Using such intrinsically charged radiation-curable adhesives tends to suppress unintended changes in adhesive properties over time caused by the movement of low molecular weight components within the formed second adhesive layer.

[0211] As the base polymer contained in the above-mentioned intrinsically charged radiation-curable adhesive, an acrylic polymer is preferred. As a method for introducing a radiation-polymerizable carbon-carbon double bond into an acrylic polymer, for example, an acrylic polymer is obtained by polymerizing (copolymerizing) a raw material monomer containing a monomer component having a first functional group, and then a compound having a second functional group that can react with the first functional group and a radiation-polymerizable carbon-carbon double bond is subjected to a condensation or addition reaction with the acrylic polymer while maintaining the radiation polymerizability of the carbon-carbon double bond.

[0212] Examples of combinations of the first functional group and the second functional group include carboxyl group and epoxy group, epoxy group and carboxyl group, carboxyl group and aziridyl group, aziridyl group and carboxyl group, hydroxyl group and isocyanate group, and isocyanate group and hydroxyl group. Among these, from the viewpoint of ease of reaction tracking, combinations of hydroxyl group and isocyanate group, and combinations of isocyanate group and hydroxyl group are preferred. In particular, producing polymers having highly reactive isocyanate groups is technically difficult, while from the viewpoint of ease of production and acquisition of acrylic polymers having hydroxyl groups, a combination in which the first functional group is a hydroxyl group and the second functional group is an isocyanate group is preferred. Examples of compounds having an isocyanate group and a radioactively polymerizable carbon-carbon double bond, i.e., radioactively polymerizable unsaturated functional group-containing isocyanate compounds, include methacryloyl isocyanate, 2-methacryloyloxyethyl isocyanate, and m-isopropenyl-α,α-dimethylbenzyl isocyanate. Furthermore, examples of acrylic polymers having hydroxyl groups include those containing the above-mentioned hydroxyl group-containing monomers, as well as constituent units derived from ether compounds such as 2-hydroxyethyl vinyl ether, 4-hydroxybutyl vinyl ether, and diethylene glycol monovinyl ether.

[0213] The above radiation-curable adhesive preferably contains a photopolymerization initiator. Examples of the above photopolymerization initiator include α-ketol compounds, acetophenone compounds, benzoin ether compounds, ketal compounds, aromatic sulfonyl chloride compounds, photoactive oxime compounds, benzophenone compounds, thioxanthone compounds, camphorquinone, halogenated ketones, acylphosphinoxides, and acylphosphonates. Examples of the above α-ketol compounds include 4-(2-hydroxyethoxy)phenyl(2-hydroxy-2-propyl)ketone, α-hydroxy-α,α'-dimethylacetophenone, 2-methyl-2-hydroxypropiophenone, and 1-hydroxycyclohexylphenyl ketone. Examples of the above acetophenone compounds include methoxyacetophenone, 2,2-dimethoxy-2-phenylacetophenone, 2,2-diethoxyacetophenone, and 2-methyl-1-[4-(methylthio)-phenyl]-2-morpholinopropane-1. Examples of the above benzoin ether compounds include benzoin ethyl ether, benzoin isopropyl ether, and anisoin methyl ether. Examples of the above ketal compounds include benzyldimethyl ketal. Examples of the above aromatic sulfonyl chloride compounds include 2-naphthalenesulfonyl chloride. Examples of the above photoactive oxime compounds include 1-phenyl-1,2-propanedione-2-(O-ethoxycarbonyl)oxime. Examples of the above benzophenone compounds include benzophenone, benzoylbenzoic acid, and 3,3'-dimethyl-4-methoxybenzophenone. Examples of the thioxanthone compounds mentioned above include thioxanthone, 2-chlorothioxanthone, 2-methylthioxanthone, 2,4-dimethylthioxanthone, isopropylthioxanthone, 2,4-dichlorothioxanthone, 2,4-diethylthioxanthone, and 2,4-diisopropylthioxanthone. The content of the photopolymerization initiator in the radiation-curable adhesive is, for example, 0.05 to 20 parts by weight per 100 parts by weight of the base polymer.

[0214] The above-mentioned heat-foaming adhesive is an adhesive containing components (foaming agents, thermally expandable microspheres, etc.) that foam or expand upon heating. Examples of the foaming agents include various inorganic and organic foaming agents. Examples of the inorganic foaming agents include ammonium carbonate, ammonium bicarbonate, sodium bicarbonate, ammonium nitrite, sodium borohydride, and azides. Examples of the above-mentioned organic blowing agents include salt fluoride alkanes such as trichloromonofluoromethane and dichloromonofluoromethane; azo compounds such as azobisisobutyronitrile, azodicarbonamide, and barium azodicarboxylate; hydrazine compounds such as p-toluenesulfonyl hydrazide, diphenylsulfon-3,3'-disulfonyl hydrazide, 4,4'-oxybis(benzenesulfonyl hydrazide), and allylbis(sulfonyl hydrazide); semicarbazide compounds such as p-toluenesulfonyl semicarbazide and 4,4'-oxybis(benzenesulfonyl semicarbazide); triazole compounds such as 5-morpholyl-1,2,3,4-thiatriazole; and N-nitroso compounds such as N,N'-dinitrosopentamethylenetetramine and N,N'-dimethyl-N,N'-dinitrosotelephthalamide. Examples of the above-mentioned thermally expandable microspheres include microspheres in which a substance that readily gasifies and expands upon heating is enclosed within the shell. Examples of substances that readily gasifies and expand upon heating include isobutane, propane, and pentane. Thermally expandable microspheres can be produced by enclosing a substance that readily gasifies and expands upon heating within a shell-forming material using methods such as coacervation or interfacial polymerization. As the shell-forming material, substances that exhibit thermal fusion or substances that can rupture due to the thermal expansion of the enclosed material can be used. Examples of such substances include vinylidene chloride-acrylonitrile copolymer, polyvinyl alcohol, polyvinyl butyral, polymethyl methacrylate, polyacrylonitrile, polyvinylidene chloride, and polysulfone.

[0215] Examples of the non-reducing adhesive layer mentioned above include a pressure-sensitive adhesive layer. The pressure-sensitive adhesive layer includes an adhesive layer formed from the radiation-curable adhesive described above, which is pre-cured by radiation irradiation while maintaining a certain level of adhesion. The adhesive forming the non-reducing adhesive layer may be one type of adhesive or two or more types of adhesives. Furthermore, the entire second adhesive layer may be a non-reducing adhesive layer, or only a portion of it may be a non-reducing adhesive layer. For example, if the second adhesive layer has a single-layer structure, the entire second adhesive layer may be a non-reducing adhesive layer, or a specific portion of the second adhesive layer may be a non-reducing adhesive layer while other portions are adhesive layers with reduced adhesion. Also, if the second adhesive layer has a laminated structure, all adhesive layers in the laminated structure may be non-reducing adhesive layers, or some adhesive layers in the laminated structure may be non-reducing adhesive layers.

[0216] An adhesive layer formed from a radiation-curable adhesive (a radiation-curable adhesive layer that has not been irradiated) and then cured in advance by radiation (a radiation-irradiated radiation-curable adhesive layer) exhibits tackiness due to the polymer components it contains, even if its tackiness is reduced by radiation, and is capable of exhibiting the minimum tackiness required for the transfer sheet of the second embodiment. When using a radiation-irradiated radiation-curable adhesive layer, the entire second adhesive layer may be a radiation-irradiated radiation-curable adhesive layer in the direction of surface expansion of the second adhesive layer, or a part of the second adhesive layer may be a radiation-irradiated radiation-curable adhesive layer and the other part may be an unirradiated radiation-curable adhesive layer. In this specification, "radiation-curable adhesive layer" refers to an adhesive layer formed from a radiation-curable adhesive, and includes both a radiation-curable unirradiated radiation-curable adhesive layer and a radiation-cured radiation-curable adhesive layer after the adhesive layer has been cured by radiation.

[0217] As the adhesive forming the pressure-sensitive adhesive layer described above, known or conventional pressure-sensitive adhesives can be used, and acrylic adhesives with an acrylic polymer as the base polymer are preferably used. When the second adhesive layer contains an acrylic polymer as a pressure-sensitive adhesive, it is preferable that the acrylic polymer is a polymer in which the constituent units derived from (meth)acrylic acid ester are the most abundant by mass. As the acrylic polymer described above, for example, an acrylic polymer that can be included in the additive-type radiation-curable adhesive described above can be used.

[0218] [Base material] In the transfer sheet of the second embodiment, the substrate is an element that functions as a support. Examples of the substrate include a plastic substrate (particularly a plastic film). The substrate may be a single layer or a laminate of the same or different types of substrates.

[0219] Examples of resins constituting the above-mentioned plastic substrates include polyolefin resins such as low-density polyethylene, linear low-density polyethylene, medium-density polyethylene, high-density polyethylene, ultra-low-density polyethylene, random copolymer polypropylene, block copolymer polypropylene, homopolypropylene, polybutene, polymethylpentene, ethylene-vinyl acetate copolymer (EVA), ionomer, ethylene-(meth)acrylic acid copolymer, ethylene-(meth)acrylic acid ester (random, alternating) copolymer, ethylene-butene copolymer, and ethylene-hexene copolymer; polyurethane; polyesters such as polyethylene terephthalate (PET), polyethylene naphthalate, and polybutylene terephthalate (PBT); polycarbonate; polyimide; polyether ether ketone; polyetherimide; polyamides such as aramid and fully aromatic polyamide; polyphenyl sulfide; fluororesin; polyvinyl chloride; polyvinylidene chloride; cellulose resin; silicone resin; and cellulose triacetate (TAC). In the second embodiment, when the transfer sheet receives electronic components and transfers them onto a mounting substrate by thermocompression (for example, at 150°C), the substrate preferably contains a heat-resistant resin such as polyimide (PI), polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polyamide (PA), or polyetheretherketone (PEEK) as its main component, and more preferably contains polyimide as its main component. Furthermore, from the viewpoint of preventing discoloration of the transfer sheet when the transfer sheet of the second embodiment receives electronic components, or when processing is performed using active energy ray irradiation such as laser light irradiation after receiving components, materials that exhibit ultraviolet absorption properties, such as polyimide (PI), polyethylene terephthalate (PET), and cellulose triacetate (TAC), are also preferable. Furthermore, the main component of the base material is defined as the component that accounts for the largest mass proportion among the constituent components. The above resin may be used by one type only, or by two or more types.

[0220] When the base material is a plastic film, the plastic film may be unoriented or oriented in at least one direction (uniaxial direction, biaxial direction, etc.), but unoriented is preferred because it is less likely to exhibit thermal shrinkage.

[0221] The surface of the substrate facing the first adhesive layer and / or the second adhesive layer may be subjected to surface treatments such as physical treatments like corona discharge treatment, plasma treatment, sandblasting, ozone exposure treatment, flame exposure treatment, high-voltage electric shock exposure treatment, and ionization radiation treatment; chemical treatments like chromic acid treatment; coating agents (primers); and easy-adhesion treatments using silicone primers, in order to improve adhesion and retention with the adhesive layer. In addition, to impart antistatic properties, a conductive vapor-deposited layer containing metals, alloys, or oxides thereof may be provided on the substrate surface, or a conductive polymer such as PEDOT-PSS may be coated. It is preferable that the surface treatment to improve adhesion is applied to the entire surface of the substrate facing the adhesive layer.

[0222] From the viewpoint of ensuring sufficient strength for the substrate to function as a support in the transfer sheet of the second embodiment, the thickness of the substrate is preferably 5 μm or more, more preferably 10 μm or more, even more preferably 15 μm or more, and particularly preferably 20 μm or more. Furthermore, from the viewpoint of achieving appropriate flexibility in the transfer sheet of the second embodiment, the thickness of the substrate is preferably 200 μm or less, more preferably 180 μm or less, and even more preferably 150 μm or less.

[0223] In the transfer sheet of the second embodiment, the haze of the substrate (according to JIS K7136) is not particularly limited, but is preferably 10% or less, and more preferably 5.0% or less. When the haze is 10% or less, excellent transparency is obtained, and for example, the visibility of alignment marks formed by applying an external stimulus to the transfer sheet of the second embodiment is improved, which is preferable. The haze can be measured using a haze meter (manufactured by Murakami Color Technology Laboratory Co., Ltd., product name "HM-150").

[0224] In the transfer sheet of the second embodiment, the total light transmittance of the substrate in the visible light wavelength range (according to JIS K7361-1) is not particularly limited, but is preferably 85% or higher, and more preferably 88% or higher. A total light transmittance of 85% or higher is preferable because it provides excellent transparency, for example, improving the visibility of alignment marks formed by applying an external stimulus to the transfer sheet of the second embodiment. The total light transmittance can be measured using a haze meter (manufactured by Murakami Color Technology Laboratory Co., Ltd., product name "HM-150").

[0225] In the transfer sheet of the second embodiment, the substrate may contain the color-changing component of the present invention. That is, the substrate may contain a compound that changes color upon reaction with an acid, an acid generator, and optionally a base generator, and may change color upon external stimuli to form alignment marks. Alternatively, the substrate may contain a compound that decolorizes upon reaction with a base, and a base generator, or a photochromic compound, and may change color upon external stimuli to form alignment marks.

[0226] The compound that changes color upon reaction with acid is preferably in an amount of 0.01 to 30 parts by weight, more preferably 0.1 to 30 parts by weight, even more preferably 0.1 to 20 parts by weight, and still more preferably 1 to 10 parts by weight per 100 parts by weight of the substrate. Within this range, alignment marks can be efficiently formed by the color change caused by the compound that changes color upon reaction with acid.

[0227] The acid generator is preferably in an amount of 0.001 to 30 parts by weight per 100 parts by weight of the base material, more preferably 0.01 to 25 parts by weight, even more preferably 0.1 to 30 parts by weight, and still more preferably 0.1 to 20 parts by weight. Within these ranges, acid can be efficiently generated by irradiation with active energy rays or heating, and alignment marks can be efficiently formed by discoloration caused by a compound that changes color upon reaction with the acid.

[0228] The amount of base generating agent is preferably 0.001 to 30 parts by weight, more preferably 0.01 to 25 parts by weight, and even more preferably 0.1 to 20 parts by weight per 100 parts by weight of the substrate. Within this range, bases can be efficiently generated by active energy ray irradiation or heating, enabling the decolorization of alignment marks.

[0229] The amount of photochromic compounds that decolorize upon reaction with a base in the substrate is the same as that of the compounds that change color upon reaction with an acid.

[0230] [Removable Liner] In the second embodiment, the adhesive layer surface of the transfer sheet (the adhesive surface of the first adhesive layer and / or the second adhesive layer) may be protected by a release liner until use. The release liner is used as a protective material for the adhesive layer and is peeled off when the adhesive sheet is attached to the substrate. Figure 2 is a schematic cross-sectional view showing one embodiment (second embodiment) of the transfer sheet of the present invention, where 1 is the transfer sheet, 10 is the substrate, 11 is the first adhesive layer, 12 is the second adhesive layer, and 110 and 120 are the release liners. Note that the release liner is not necessarily provided.

[0231] As the above-mentioned release liner, conventional release paper can be used. Specifically, for example, in addition to a substrate having a release treatment layer with a release treatment agent on at least one surface, low-adhesion substrates made of fluorine-based polymers (e.g., polytetrafluoroethylene, polychlorotrifluoroethylene, polyvinyl fluoride, polyvinylidene fluoride, tetrafluoroethylene-hexafluoropropylene copolymer, chlorofluoroethylene-vinylidene fluoride copolymer, etc.) or low-adhesion substrates made of non-polar polymers (e.g., polyethylene, polypropylene, and other olefin resins) can be used.

[0232] As the above-mentioned peel-off liner, for example, a peel-off liner having a release treatment layer formed on at least one surface of the peel-off liner substrate can be suitably used. Examples of such peel-off liner substrates include plastic substrate films (synthetic resin films) such as polyester film (polyethylene terephthalate film, etc.), olefin resin film (polyethylene film, polypropylene film, etc.), polyvinyl chloride film, polyimide film, polyamide film (nylon film), and rayon film, as well as paper (high-quality paper, Japanese paper, kraft paper, glassine paper, synthetic paper, topcoat paper, etc.), and composites of these made by laminating or co-extrusion (2-3 layer composites).

[0233] The release agent constituting the above-mentioned release layer is not particularly limited, but for example, silicone-based release agents, fluorine-based release agents, long-chain alkyl-based release agents, etc., can be used. The release agent can be used alone or in combination of two or more types. Furthermore, since the first adhesive layer is composed of a low-tack adhesive layer, it is possible to use a substrate that has not been treated with a release agent as a release liner.

[0234] To prevent adverse effects on electronic components, the above-mentioned peel-off liner may have an antistatic layer formed on at least one surface of the substrate for the peel-off liner. The antistatic layer may be formed on one surface of the peel-off liner (the peel-off surface or the untreated surface), or on both surfaces of the peel-off liner (the peel-off surface and the untreated surface).

[0235] Examples of antistatic agents contained in the antistatic resin forming the antistatic layer include cationic antistatic agents having cationic functional groups such as quaternary ammonium salts, pyridinium salts, and primary, secondary, and tertiary amino groups; anionic antistatic agents having anionic functional groups such as sulfonates, sulfate esters, phosphonates, and phosphate esters; amphoteric antistatic agents such as alkyl betaines and their derivatives, imidazolines and their derivatives, and alanine and its derivatives; nonionic antistatic agents such as amino alcohols and their derivatives, glycerin and its derivatives, and polyethylene glycol and its derivatives; and ion-conductive polymers obtained by polymerizing or copolymerizing monomers having the above-mentioned cationic, anionic, and amphoteric ion-conductive groups. These compounds may be used individually or in combination of two or more.

[0236] The thickness of the release liner is not particularly limited and can be appropriately selected from the range of 5 to 100 μm.

[0237] The method for manufacturing the transfer sheet of the second embodiment varies depending on the composition of the adhesive composition and other factors, and is not particularly limited; known forming methods can be used, but examples include the following methods (1) to (4). (1) A method for manufacturing an adhesive sheet by applying (coating) the above adhesive composition onto a substrate to form a composition layer, and curing the composition layer (for example, by heat curing or curing by irradiation with active energy rays such as ultraviolet light) to form an adhesive layer. (2) A method for producing an adhesive sheet by applying the above adhesive composition onto a release liner to form a composition layer, curing the composition layer (for example, by heat curing or curing by irradiation with active energy rays such as ultraviolet light) to form an adhesive layer, and then transferring the adhesive layer onto a substrate. (3) A method for producing an adhesive sheet by applying the above adhesive composition onto a substrate, drying it to form an adhesive layer. (4) A method for producing an adhesive sheet by applying the above adhesive composition onto a release liner, drying it to form an adhesive layer, and then transferring the adhesive layer onto a substrate.

[0238] Of the curing methods described in (1) to (4) above, a heat curing method is preferred because it offers excellent productivity and allows for the formation of a homogeneous and smooth-surfaced adhesive layer.

[0239] The method for applying (coating) the above adhesive composition onto a predetermined surface can be any known coating method, and is not particularly limited. Examples include roll coating, kiss roll coating, gravure coating, reverse coating, roll brushing, spray coating, dip roll coating, bar coating, knife coating, air knife coating, curtain coating, lip coating, and extrusion coating methods using a die coater.

[0240] The thickness (total thickness) of the transfer sheet in the second embodiment is not particularly limited, but is preferably 10 μm or more, and more preferably 15 μm or more. A thickness above a certain level is preferable because it makes it easier for the first adhesive layer to accurately receive the electronic components. Furthermore, the upper limit of the thickness (total thickness) of the transfer sheet in the second embodiment is not particularly limited, but is preferably 500 μm or less, and more preferably 300 μm or less. A thickness below a certain level is preferable because it makes it easier to accurately transfer the electronic components to the mounting substrate. Note that the thickness of the transfer sheet in the second embodiment does not include the thickness of the release liner.

[0241] The haze of the transfer sheet of the second embodiment (according to JIS K7136) is not particularly limited, but is preferably 10% or less, and more preferably 5.0% or less. A haze of 10% or less is preferable because it provides excellent transparency, for example, improving the visibility of alignment marks formed by applying external stimuli to the transfer sheet of the second embodiment. The haze can be measured, for example, by leaving the transfer sheet at room temperature (23°C, 50%RH) for at least 24 hours, peeling off the release liner if present, and attaching the sample to a glass slide (for example, one with a total light transmittance of 91.8% and a haze of 0.4%), using a haze meter (manufactured by Murakami Color Technology Laboratory Co., Ltd., product name "HM-150").

[0242] The total light transmittance (according to JIS K7361-1) of the transfer sheet in the visible light wavelength range of the second embodiment is not particularly limited, but is preferably 85% or higher, and more preferably 88% or higher. A total light transmittance of 85% or higher is preferable because it provides excellent transparency, for example, improving the visibility of alignment marks formed by applying external stimuli to the transfer sheet of the second embodiment. The total light transmittance can be measured, for example, by leaving the transfer sheet at room temperature (23°C, 50%RH) for at least 24 hours, peeling off the release liner if present, and attaching the sample to a glass slide (for example, one with a total light transmittance of 91.8% and haze of 0.4%), using a haze meter (manufactured by Murakami Color Technology Laboratory Co., Ltd., product name "HM-150").

[0243] The transfer sheet of the present invention is suitably used for receiving (transferring) electronic components. A method for transferring electronic components using the transfer sheet of the present invention preferably includes the following steps. The transfer sheet of the present invention is subjected to an external stimulus to form alignment marks (first step). The second step involves the transfer sheet of the present invention receiving the diced electronic components, using the alignment marks as indicators.

[0244] Figure 3 is a schematic cross-sectional view showing one embodiment of the first step in the method for transferring electronic components using the transfer sheet of the second embodiment. In Figure 3(a), the transfer sheet 1 has a laminated structure in which a first adhesive layer 11, a substrate 10, and a second adhesive layer 12 are laminated in this order. In this embodiment, the second adhesive layer 12 contains the color-changing component of the present invention, while the first adhesive layer 11 does not contain the color-changing component of the present invention. In this embodiment, the color-changing component contained in the second adhesive layer 12 includes a compound that changes color upon reaction with an acid, and a photoacid generator. The second adhesive layer 12 is attached to the carrier substrate 21 by its adhesive surface. The carrier substrate can be a plastic substrate similar to the substrate mentioned above, or a glass substrate, and a glass substrate with high transparency is preferred.

[0245] A photomask 22 is placed on the side of the carrier substrate 21 that is not attached to the second adhesive layer 12. The openings in the photomask 22 correspond to the positions where the electronic components 31, described later, are placed on the second adhesive layer 11.

[0246] In Figure 3(a), the active energy ray U is irradiated onto the photomask 22. The active energy ray U passes through the opening of the photomask 22 and the highly transparent carrier substrate 21, reaching the second adhesive layer 12. The photoacid generator decomposes and generates acid, and the compound that changes color upon reaction with the acid changes color (becomes colored), forming an alignment mark 23 at the position corresponding to the opening of the photomask 22.

[0247] The active energy rays include light such as ultraviolet light, visible light, and infrared light, as well as radiation such as alpha rays, beta rays, gamma rays, electron beams, neutron beams, and X-rays. Electron beams, ultraviolet light, and laser light are preferred, with ultraviolet light being more preferred. Alignment marks 23 may be formed by irradiating a position corresponding to the opening of the photomask 22 with laser light without using the photomask 22.

[0248] Figure 4 is a schematic cross-sectional view showing one embodiment of the second step in the method for transferring electronic components using the transfer sheet of the second embodiment.

[0249] In Figure 4(a), on the upper part of the adhesive surface of the first adhesive layer 11 of the transfer sheet 1, multiple electronic components 31, which have been separated by dicing, are attached to the dicing tape 30, and are positioned spaced apart, facing the adhesive surface of the first adhesive layer 11.

[0250] The electronic components are not particularly limited, but they can be suitably used in fine, thin semiconductor chips and LED chips. The electronic components can be thin and fine, for example, with a major axis of 500 μm or less, or 100 μm or less; and a minor axis of 400 μm or less, or 50 μm or less. The lower limits of the major and minor axes are not particularly limited, but should be 5 μm or more. Furthermore, the thickness of the electronic components is not particularly limited, but may be 100 μm or less, or 50 μm or less. The lower limit of the thickness of the electronic components is also not particularly limited, but it should be 5 μm or more.

[0251] In Figure 4(b), the electronic component 31 is pushed by the pin member 32 from the side of the dicing tape 30 to which the electronic component 31 is not attached, bringing the electronic component 31 close to the adhesive surface of the first adhesive layer 11, which then receives it. The position where the first adhesive layer 11 receives the electronic component 31 is aligned to the corresponding position using the alignment marks 23 as indicators.

[0252] The electronic component 31 may be received by bringing the first adhesive layer 11 into contact with it, or by receiving it without contact. When receiving it without contact, the electronic component 31 is pushed until it peels off from the dicing tape 30 and falls onto the adhesive surface of the electronic component 31. When receiving it in contact, the adhesive surface of the first adhesive layer 11 has low tackiness, so the stress applied when the electronic component 31 is received is weak, thus suppressing damage to the electronic component 31. When receiving it without contact, the adhesive surface of the first adhesive layer 11 has low tackiness, so the fallen electronic component 31 can be caught with good positional accuracy.

[0253] Alternatively, the electronic component 31 may be detached from the dicing tape 30 by irradiating it with radiation such as ultraviolet light or laser light instead of the pin member 32. When the electronic component 31 is detached from the dicing tape 30 by irradiating it with radiation, it is preferable that the first adhesive layer 11 contains an ultraviolet absorber. Because the first adhesive layer 11 contains an ultraviolet absorber, the radiation is absorbed by the first adhesive layer 11, and discoloration of the second adhesive layer 12 can be suppressed.

[0254] The electronic components 31 may be received onto the first adhesive layer 11 individually or in batches. Figure 4(c) is a schematic cross-sectional view showing the configuration in which all the electronic components 31 of the dicing tape 20 have been received onto the adhesive surface of the first adhesive layer 11 of the transfer sheet 1.

[0255] The electronic components 31 transferred onto the first adhesive layer 11 of the transfer sheet 1 are mounted onto the mounting substrate. Figure 5 is a schematic cross-sectional view showing the mounting method of electronic components transferred onto the transfer sheet. In this embodiment, the electronic components 31 are formed in positions such that they can be accurately mounted on each circuit formed on the circuit surface 41 of the mounting substrate 40, using the alignment marks 23 as indicators.

[0256] As shown in Figure 5(a), the electronic components 31 arranged on the adhesive surface of the first adhesive layer 11 of the transfer sheet 1 are placed opposite and spaced apart from the circuit surface 41 (circuit pattern not shown) of the mounting substrate 40. Next, as shown in Figure 5(b), the circuit surface 41 of the mounting substrate 40 and the electronic components 31 arranged on the adhesive surface of the first adhesive layer 11 of the transfer sheet 1 are brought close together so that the electronic components 31 and the circuit surface 41 of the mounting substrate 40 come into contact.

[0257] The transfer of the electronic component 31 to the circuit surface 41 of the mounting substrate 40 may be performed by thermocompression bonding (for example, 150°C for 1 minute). Since the base material 10, the first adhesive layer 11, and / or the second adhesive layer 12 constituting the transfer sheet 1 have excellent heat resistance, they do not expand or contract or change in adhesive strength during thermocompression bonding, so the electronic component 31 can be transferred to the circuit surface 41 of the mounting substrate 40 with high accuracy.

[0258] Next, as shown in Figure 5(c), by separating the transfer sheet 1 and the mounting substrate 40, the electronic component 31 is peeled off from the first adhesive layer 11 and transferred to the circuit surface 41 of the mounting substrate 40. Since the first adhesive layer 11 is composed of a low-tack adhesive layer, the electronic component 31 peels off easily and can be efficiently mounted on the mounting substrate 40 without damaging the electronic component 31.

[0259] The transfer sheet 1 shown in Figure 5(c) after the electronic component 31 has been mounted on the mounting substrate 40 may be peeled off from the carrier substrate 21 (not shown). Since the second adhesive layer 12 is composed of a release adhesive layer, it can be peeled off without leaving any adhesive residue and has excellent reworkability, so the carrier substrate 21 can be easily reused. [Examples]

[0260] Examples are given below to explain the present invention in more detail, but the present invention is not limited in any way by these examples.

[0261] [Production Example 1]: Production of acrylic copolymer (1) Into a four-necked flask equipped with a stirring blade, thermometer, nitrogen gas inlet tube, and cooler, 95 parts by weight of butyl acrylate (manufactured by Nippon Shokubai Co., Ltd.), 5 parts by weight of acrylic acid (manufactured by Toagosei Co., Ltd.), 0.2 parts by weight of 2,2'-azobisisobutyronitrile (manufactured by Wako Pure Chemical Industries, Ltd.) as a polymerization initiator, and 156 parts by weight of ethyl acetate were charged. While gently stirring, nitrogen gas was introduced, and the polymerization reaction was carried out for 10 hours while maintaining the liquid temperature in the flask at around 63°C to prepare a solution of acrylic copolymer (1) with a weight average molecular weight of 700,000 (solid content: 40% by weight).

[0262] [Production Example 2]: Production of acrylic copolymer (2) Into a four-necked flask equipped with a stirring blade, thermometer, nitrogen gas inlet tube, and cooler, 100 parts by weight of 2-ethylhexyl acrylate (2EHA) (manufactured by Nippon Shokubai Co., Ltd.), 4 parts by weight of 2-hydroxyethyl acrylate (HEA) (manufactured by Toagosei Co., Ltd.), 0.02 parts by weight of 2,2'-azobisisobutyronitrile (manufactured by Wako Pure Chemical Industries, Ltd.) as a polymerization initiator, and 180 parts by weight of ethyl acetate were charged. While gently stirring, nitrogen gas was introduced, and the polymerization reaction was carried out for 6 hours while maintaining the liquid temperature in the flask at around 65°C to prepare a solution of acrylic copolymer (2) with a weight average molecular weight of 560,000 (solid content: 35% by weight).

[0263] [Example 1] (Production of transfer sheet) 100 parts by weight of silicone adhesive 1 (addition reaction type silicone adhesive, trade name "X-40-3306", manufactured by Shin-Etsu Chemical Co., Ltd.), 1.4 parts by weight of platinum catalyst 1 (trade name "CAT-PL-50T", manufactured by Shin-Etsu Chemical Co., Ltd.), and 5 parts by weight of silicone release agent 1 (addition reaction type silicone release agent mainly composed of dimethylpolysiloxane, trade name "KS-776A", manufactured by Shin-Etsu Chemical Co., Ltd.) were added, diluted with toluene to a total solid content of 25% by weight, and mixed with a disperser to prepare a silicone adhesive composition (silicone adhesive composition 1). A silicone-based adhesive composition 1 was applied to the silicone-primer-treated side of a base film (1) (a polyester film with one side treated with a silicone primer, 25 μm thick, product name "Diafoil MRF#25", manufactured by Mitsubishi Plastics, Inc.) so that the adhesive thickness after drying was 10 μm. The film was then cured and dried at a drying temperature of 120°C for a drying time of 5 minutes. In this way, a film having a silicone-based adhesive layer (1) on the silicone-primer-treated layer of the base film (1) was obtained. Furthermore, a release liner (1) (untreated polyethylene terephthalate film, 25 μm thick, product name "Lumirror S10#25", manufactured by Toray Industries, Inc.) was laminated onto the adhesive surface of the silicone adhesive film to protect the silicone adhesive layer, thereby obtaining a laminate (1) having a laminated structure of [release liner (1) layer] / [silicone adhesive (1) layer] / [base film (1) layer]. Next, to the solution of the acrylic copolymer (1) obtained in Production Example 1, 6.0 parts by weight of TETRAD-C (manufactured by Mitsubishi Gas Chemical Co., Ltd.) as a crosslinking agent, 2 parts by weight of leuco dye (product name "S-205", manufactured by Yamada Chemical Industry Co., Ltd.), and 7 parts by weight of photoacid generator (product name "CPI-100P", manufactured by Sunapro Co., Ltd.) were added per 100 parts by weight of solids. The solution was diluted with toluene so that the total solids content was 25% by weight, and the acrylic adhesive composition was stirred with a disperser. This acrylic adhesive composition was applied to the release layer side of the release liner (2) (released polyethylene terephthalate film, thickness 38 μm, product name "MRF#38", manufactured by Mitsubishi Chemical Corporation) using a fountain roll so that the thickness after drying was 25 μm. The liner was then cured and dried under conditions of a drying temperature of 130°C and a drying time of 30 seconds. In this way, an acrylic adhesive layer (1) was formed on the release liner (2). Next, the base film (1) side (the side not treated with silicone primer) of the laminate (1) obtained above was bonded to the surface of the acrylic adhesive layer (1) to obtain a transfer sheet having a laminated structure of [release liner (1) layer] / [silicone adhesive (1) layer (first adhesive layer)] / [base film (1) layer] / [acrylic adhesive (1) layer (second adhesive layer)] / [release liner (2) layer].

[0264] [Example 2] A transfer sheet having a laminated structure of [Release Liner (1) layer] / [Silicone-based Adhesive (1) layer (First Adhesive Layer)] / [Base Film (1) layer] / [Acrylic-based Adhesive (2) layer (Second Adhesive Layer)] / [Release Liner (2) layer] was obtained in the same manner as in Example 1, except that 7 parts by weight of a photoacid generator (product name "CPI-110P", manufactured by Sunapro Co., Ltd.) was added instead of the photoacid generator (product name "CPI-100P", manufactured by Sunapro Co., Ltd.).

[0265] [Example 3] A transfer sheet having a laminated structure of [Release Liner (1) layer] / [Silicone-based Adhesive (1) layer (First Adhesive Layer)] / [Base Film (1) layer] / [Acrylic-based Adhesive (3) layer (Second Adhesive Layer)] / [Release Liner (2) layer] was obtained in the same manner as in Example 1, except that 7 parts by weight of a photoacid generator (product name "CPI-310B", manufactured by Sunapro Co., Ltd.) was added instead of a photoacid generator (product name "CPI-100P", manufactured by Sunapro Co., Ltd.).

[0266] [Example 4] Except for replacing the photoacid generator (product name "CPI-100P", manufactured by Sunapro Co., Ltd.) with 7 parts by weight of a photoacid generator (product name "SP-056", manufactured by ADEKA Corporation) and replacing the base film (1) with a base film (2) (polyimide film, thickness 25 μm, product name "Kapton 100H", manufactured by Toray DuPont), a transfer sheet having a laminated structure of [release liner (1) layer] / [silicone-based adhesive (1) layer (first adhesive layer)] / [base film (2) layer] / [acrylic-based adhesive (4) layer (second adhesive layer)] / [release liner (2) layer] was obtained in the same manner as in Example 1.

[0267] [Example 5] Except for using base film (3) (TAC film, 80 μm thick, product name "Fujitac TD80UL", manufactured by Fujifilm Corporation) instead of base film (2), a transfer sheet having a laminated structure of [release liner (1) layer] / [silicone-based adhesive (1) layer (first adhesive layer)] / [base film (3) layer] / [acrylic-based adhesive (4) layer (second adhesive layer)] / [release liner (2) layer] was obtained in the same manner as in Example 4.

[0268] [Example 6] To 100 parts by weight of solids of the acrylic copolymer (2) obtained in Production Example 2, 4.0 parts by weight of Coronate HX (manufactured by Tosoh Corporation) as a crosslinking agent, 0.02 parts by weight of Envirizer OL-1 (manufactured by Tokyo Fine Chemical Co., Ltd.) as a crosslinking catalyst, 2 parts by weight of leuco dye (product name "S-205", manufactured by Yamada Chemical Industry Co., Ltd.), and 7 parts by weight of photoacid generator (product name "SP-056", manufactured by ADEKA Corporation) were added, the mixture was diluted with ethyl acetate so that the total solids content was 25% by weight, stirred with a disperser, and the resulting acrylic adhesive composition was applied to the release liner (2). Except for these steps, a transfer sheet having a laminated structure of [release liner (1) layer] / [silicone adhesive (1) layer (first adhesive layer)] / [base film (1) layer] / [acrylic adhesive (5) layer (second adhesive layer)] / [release liner (2) layer] was obtained in the same manner as in Example 1.

[0269] [Example 7] As a prepolymer-type urethane adhesive composition (1), a solution of Ciabein SH-109 (manufactured by Toyo Chem Co., Ltd.) was prepared by adding 3.0 parts by weight of Coronate HX (manufactured by Tosoh Corporation) as a crosslinking agent, 2 parts by weight of leuco dye (product name "S-205", manufactured by Yamada Chemical Industries, Ltd.), and 7 parts by weight of photoacid generator (product name "SP-056", manufactured by ADEKA Corporation) to 100 parts by weight of solids, diluting with ethyl acetate so that the total solids content was 25% by weight, stirring with a disperser, and applying the resulting urethane adhesive composition to a release liner (2) in the same manner as in Example 1, to obtain a transfer sheet having a laminated structure of [Release liner (1) layer] / [Silicone adhesive (1) layer (first adhesive layer)] / [Base film (1) layer] / [Urethane adhesive (1) layer (second adhesive layer)] / [Release liner (2) layer].

[0270] [Example 8] 100 parts by weight of silicone adhesive 1 (addition reaction type silicone adhesive, trade name "X-40-3306", manufactured by Shin-Etsu Chemical Co., Ltd.), 1.4 parts by weight of platinum catalyst 1 (trade name "CAT-PL-50T", manufactured by Shin-Etsu Chemical Co., Ltd.), 5 parts by weight of silicone release agent 1 (addition reaction type silicone release agent mainly composed of dimethylpolysiloxane, trade name "KS-776A", manufactured by Shin-Etsu Chemical Co., Ltd.), and 5 parts by weight of ultraviolet absorber (trade name "TINUVIN 384-2", manufactured by BASF) were added, diluted with toluene to a total solid content of 25% by weight, and mixed with a disperser to prepare a silicone adhesive composition (silicone adhesive composition 2). A silicone-based adhesive composition 2 was applied to a base film (4) (COP film, 55 μm thick, trade name "ZeonorFilm", manufactured by Zeon Corporation of Japan) so that the adhesive thickness after drying was 10 μm. The film was then cured and dried at a drying temperature of 120°C for a drying time of 5 minutes. In this way, a film having a silicone-based adhesive layer (2) on the base film (4) was obtained. Furthermore, a release liner (1) (untreated polyethylene terephthalate film, 25 μm thick, product name "Lumirror S10#25", manufactured by Toray Industries, Inc.) was laminated onto the adhesive surface of the silicone adhesive film to protect the silicone adhesive layer, thereby obtaining a laminate (2) having a laminated structure of [release liner (1) layer] / [silicone adhesive (2) layer] / [base film (4) layer]. Next, to the solution of the acrylic copolymer (2) obtained in Production Example 2, 4.0 parts by weight of Coronate HX (manufactured by Tosoh Corporation) as a crosslinking agent, 2 parts by weight of leuco dye (product name "S-205", manufactured by Yamada Chemical Industries, Ltd.), and 7 parts by weight of photoacid generator (product name "SP-056", manufactured by ADEKA Corporation) were added per 100 parts by weight of solids. The solution was diluted with toluene so that the total solids content was 25% by weight, and the acrylic adhesive composition was stirred with a disperser. This acrylic adhesive composition was applied to the release layer side of the release liner (2) (release-treated polyethylene terephthalate film, thickness 38 μm, product name "MRF#38", manufactured by Mitsubishi Chemical Corporation) using a fountain roll so that the thickness after drying was 25 μm. The liner was then cured and dried under conditions of a drying temperature of 130°C and a drying time of 30 seconds. In this way, an acrylic adhesive layer (6) was formed on the release liner (2). Next, the base film (4) side of the laminate (2) obtained above was bonded to the surface of the acrylic adhesive layer (6) to obtain a transfer sheet having a laminated structure of [release liner (1) layer] / [silicone adhesive (2) layer (first adhesive layer)] / [base film (4) layer] / [acrylic adhesive (6) layer (second adhesive layer)] / [release liner (2) layer].

[0271] [Comparative Example 1] Except for adding 6.0 parts by weight of TETRAD-C (manufactured by Mitsubishi Gas Chemical Co., Ltd.) as a crosslinking agent, 4.0 parts by weight of Coronate HX (manufactured by Tosoh Corporation) as a crosslinking agent, and 2 parts by weight of leuco dye (product name "S-205", manufactured by Yamada Chemical Industry Co., Ltd.) to 100 parts by weight of solids of the acrylic copolymer (2) obtained in Production Example 2, 4.0 parts by weight of Coronate HX (manufactured by Tosoh Corporation) as a crosslinking agent, and 2 parts by weight of leuco dye (product name "S-205", manufactured by Yamada Chemical Industry Co., Ltd.) to 100 parts by weight of solids, diluting with ethyl acetate so that the total solids content is 25% by weight, stirring with a disperser, and coating the resulting acrylic adhesive composition onto the release liner (2), a transfer sheet having a laminated structure of [release liner (1) layer] / [silicone adhesive (1) layer (first adhesive layer)] / [base film (1) layer] / [acrylic adhesive (7) layer (second adhesive layer)] / [release liner (2) layer] was obtained in the same manner as in Example 1.

[0272] [Comparative Example 2] Based on 100 parts by weight of the solid content of the acrylic copolymer (2) obtained in Production Example 2, 6.0 parts by weight of TETRAD-C (manufactured by Mitsubishi Gas Chemical Company) as a crosslinking agent, 4.0 parts by weight of Coronate HX (manufactured by Tosoh Corporation) in terms of solid content, and 7 parts by weight of a photoacid generator (trade name "SP-056", manufactured by ADEKA) were added. It was diluted with ethyl acetate so that the total solid content was 25% by weight, and stirred with a disper. A transfer sheet having a laminated structure of [release liner (2) layer] / [silicone adhesive (1) layer (first adhesive layer)] / [base film (1) layer] / [acrylic adhesive (8) layer (second adhesive layer)] / [release liner (2) layer] was obtained in the same manner as in Example 1, except that the obtained acrylic adhesive composition was applied to the release liner (2).

[0273] <Evaluation> The following evaluations were performed on the transfer sheets obtained in the examples and comparative examples. The results are shown in Table 1.

[0274] (Total light transmittance change amount) After peeling off the release liners on both sides of the transfer sheet having the laminated structure according to each example, the initial total light transmittance was measured using a haze meter ("HM-150" manufactured by Murakami Color Technology Laboratory) so that the first adhesive layer side was arranged on the light source side. Next, using a UV irradiation device (UV LIGHT SOURCE UL750, manufactured by HOYA) through the release liner (2), an illuminance of 100 mW / cm 2 and an integrated light amount of 1000 mJ / cm 2 of light were irradiated to discolor the second adhesive layer. After peeling off the release liners on both sides, the total light transmittance after discoloration was measured using a haze meter in the same manner as the initial stage, and the absolute value of the difference between the initial and post-discoloration total light transmittances was taken as the change amount of the total light transmittance.

[0275] (Alignment property) A photomask equipped with an alignment mark with a line width of 300 μm was placed on the release liner (2) of the transfer sheet according to each example, and using a UV irradiation device (UV LIGHT SOURCE UL750, manufactured by HOYA) through the photomask, an illuminance of 100 mW / cm 2, cumulative light intensity 1000 mJ / cm 2 Alignment marks were created by irradiating with light. Then, the release liner (2) was peeled off, the second adhesive layer was bonded to alkali-free glass, and the alignment marks were read and evaluated through the glass using the following method. CCD camera: CA-H500C (manufactured by Keyence Corporation) Analysis: ShapeTrax3 (manufactured by Keyence Corporation) Judgment: Items with a correlation value of 90 or higher are marked with ○, and items with a correlation value less than 90 are marked with ×.

[0276] (Discoloration due to exposure to external light from the sheet side) After peeling off the release liner (2) of the transfer sheet for each example, the second adhesive layer was bonded to alkali-free glass to prepare evaluation samples. Then, the release liner (1) was peeled off, and the adhesive sheets of each example and comparative example were left for 240 hours under fluorescent light irradiation from the first adhesive layer side, and the presence or absence of discoloration was visually checked. Samples that did not show discoloration were marked with ○, and those that did show discoloration were marked with ×. Note that comparative examples 1 and 2 do not have alignment properties (discoloration properties), so naturally no discoloration was observed. [Table 1]

[0277] Variations of the present invention are listed below. [Note 1] A transfer sheet used to receive electronic components, A transfer sheet containing a color-changing component that can change color in response to external stimuli. [Note 2] The transfer sheet described in Appendix 1, wherein the aforementioned electronic component is a semiconductor chip. [Note 3] The transfer sheet according to Appendix 1 or 2, wherein the major axis of the electronic component is 500 μm or less. [Note 4] The transfer sheet has an adhesive layer, The transfer sheet according to any one of the appendices 1 to 3, wherein the adhesive layer contains the discoloration component. [Note 5] The transfer sheet as described in Appendix 4, wherein the adhesive constituting the adhesive layer is an acrylic adhesive or a urethane adhesive. [Note 6] The transfer sheet according to Appendix 4 or 5, wherein the transfer sheet has a laminated structure in which the adhesive layer, the substrate, and another adhesive layer different from the adhesive layer are laminated in this order. [Explanation of Symbols]

[0278] 1 Transfer sheet 10 Base material 11 First adhesive layer 12 Second adhesive layer 110,120 Peel-off Liner 21 Carrier substrate 22 Photomasks U-activated energy rays 23. Alignment marks (discolored areas) 30 dicing tapes 31 Electronic Components 32 Pin component 40 Implemented circuit boards 41 Circuit surface

Claims

1. A transfer sheet used to receive electronic components, It contains a color-changing component that can change color in response to external stimuli. A transfer sheet in which the color-changing component is a combination of a compound that changes color upon reaction with an acid and an acid generator, a combination of a compound that decolorizes upon reaction with a base and a base generator, or a photochromic compound.

2. The transfer sheet according to claim 1, wherein the electronic component is a semiconductor chip.

3. The transfer sheet according to claim 1 or 2, wherein the major axis of the electronic component is 500 μm or less.

4. The transfer sheet has an adhesive layer, The transfer sheet according to claim 1 or 2, wherein the adhesive layer contains the discoloration component.

5. The transfer sheet according to claim 4, wherein the adhesive constituting the adhesive layer is an acrylic adhesive or a urethane adhesive.

6. The transfer sheet according to claim 4, wherein the transfer sheet has a laminated structure in which the adhesive layer, the substrate, and another adhesive layer different from the adhesive layer are laminated in this order.

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