TWI863481B - Method for manufacturing a dicing-die bonding integrated film - Google Patents

Abstract

A method for producing a (meth)acrylic resin having an ethylenically unsaturated group comprises: a step (i) of subjecting a raw material monomer group (M) containing a hydroxyl-containing (meth)acrylic ester (m-1) and an alkyl (meth)acrylic ester (m-2) to reversible addition-fragmentation chain transfer (RAFT) polymerization to obtain a copolymer (A-0); and a step (ii) of adding an ethylenically unsaturated compound (a) containing an isocyanate group to a portion of the side chain hydroxyl groups of the copolymer (A-0) to obtain a (meth)acrylic resin.

Description

Manufacturing method of cutting-die bonding integrated film

The content of this disclosure is about a method for producing a (meth) acrylic resin used in an adhesive composition and a method for producing an adhesive composition.

In the past, various adhesive sheets were used in the semiconductor manufacturing process. Specifically, there are protective sheets (back grinding tapes) used to protect the semiconductor wafer in the back grinding (back grinding) step, and fixing sheets (dicing tapes) used in the dicing step from the semiconductor wafer to the component chips. These adhesive sheets are attached to the semiconductor wafer as the attached body, and are re-peelable adhesive sheets that are peeled off from the attached body after the specific processing step is completed.

As an adhesive composition used for an adhesive layer of a re-peelable adhesive sheet, it is known that a resin having an ethylenically unsaturated group that can be cured by UV (ultraviolet light) is introduced into the side chain of a (meth) acrylic resin. Such an adhesive composition is cured by a crosslinking reaction caused by UV irradiation, and the adhesive force is reduced. For example, Patent Document 1 (Japanese Patent Publication No. 2018-138682) describes an adhesive tape containing a living radical polymerized polymer with a molecular weight distribution (Mw/Mn) of 1.05 to 2.5, and in particular, a (meth) acrylic polymer having a polymerizable group that can be cured by UV light is introduced into the side chain of a polymer obtained by living radical polymerization using an organic tellurium polymerization initiator.

[Prior Art Literature] [Patent Literature]

[Patent Document 1] Japanese Patent Publication No. 2018-138682

In order to shorten the semiconductor manufacturing process, a dicing-die bonding integrated film is used in which the dicing tape of a re-peelable adhesive sheet and the die bonding (adhesive layer) are integrated. The film is used, for example, by attaching the adhesive layer to the back of a semiconductor wafer and attaching the adhesive layer from the dicing tape to a dicing ring. Thereafter, the semiconductor wafer is cut by a dicing knife to obtain singulated semiconductor chips. Therefore, the adhesive layer from the dicing tape is required to have high adhesion to the bonding agent layer and the dicing ring in the dicing step. On the other hand, in the semiconductor chip pickup step, it is required that there is no adhesive residue (residue) on each semiconductor chip, and the semiconductor chip with the attached adhesive sheet can be easily picked up. If the adhesive layer is not sufficiently adhered to the bonding agent layer, the bonding agent layer will peel off due to the high-speed rotation of the dicing blade, and the bonding agent layer will break, causing the cut end of the bonding agent layer to fly (DAF (die attach film) flying). If the adhesive layer does not have sufficient adhesion to the cutting ring, the cutting ring may be peeled off from the adhesive layer by the flow of cutting water (ring peeling).

In recent years, invisible dicing has attracted attention as a dicing method that does not use a dicing blade. In invisible dicing, laser light is focused inside the wafer to form a starting point (modified layer) for dicing, and a releasable adhesive sheet is attached to the back of the wafer. By cooling and expanding the sheet, a single-piece semiconductor chip is obtained. When a dicing-die bonding integrated film is used in invisible dicing, the wafer and the adhesive layer are singulated by cooling and expanding. If the adhesive strength of the adhesive layer is insufficient during the cooling and expansion step, the peripheral portion of the adhesive layer may break due to the impact and stress during expansion, causing the cut end to fly (DAF flying) or the end of the chip to which the adhesive chip is attached to peel off from the adhesive layer (chip edge peeling), which may cause defects in subsequent steps.

As such, the adhesive layer used in the dicing-die bonding integrated film is required to have high adhesion to the adhesive layer, no adhesive residue after UV irradiation, and be easily peeled off from the adhesive layer, which are properties not required in other re-peelable adhesive sheets. Therefore, it is difficult to directly apply the acrylic adhesive used in the conventional re-peelable adhesive sheet to the dicing-die bonding integrated film.

The present disclosure provides a method for producing a (meth)acrylic resin or an adhesive composition containing a (meth)acrylic resin. The resin or composition can provide an adhesive layer with sufficient adhesion, and when an adhesive sheet is peeled off from the adhesive layer after UV irradiation, an excellent peeling property is obtained, and an adhesive layer is not prone to residual adhesive.

The inventors of the present invention have found that a copolymer obtained by reversible addition-fragmentation chain transfer (RAFT) polymerization of a hydroxyl-containing (meth)acrylate and an alkyl (meth)acrylate and modified with an ethylenically unsaturated compound containing an isocyanate group can be used as an adhesive layer for a monolithic film for dicing-die bonding.

That is, the present disclosure includes the following aspects. [1] A method for producing a (meth)acrylic resin, comprising: a step (i) of subjecting a raw material monomer group (M) containing a hydroxyl group-containing (meth)acrylic ester (m-1) and an alkyl (meth)acrylic ester (m-2) to reversible addition-fragmentation chain transfer (RAFT) polymerization to obtain a copolymer (A-0); and a step (ii) of adding an ethylenically unsaturated compound (a) containing an isocyanate group to a portion of the side chain hydroxyl groups of the copolymer (A-0) to obtain a (meth)acrylic resin (A) having an ethylenically unsaturated group. [2] A method for producing a (meth)acrylic resin as described in [1], wherein the raw material monomer group (M) further contains a carboxyl group-containing monomer (m-3). [3] A method for producing a (meth)acrylic resin as described in [1] or [2], wherein the molecular weight distribution (Mw/Mn) of the (meth)acrylic resin (A) having an ethylenically unsaturated group is 2.4 to 10.0. [4] A method for producing an adhesive composition, comprising a step (iii) of mixing the (meth)acrylic resin (A) having an ethylenically unsaturated group obtained by the production method described in any one of [1] to [3], a photopolymerization initiator (B) and a crosslinking agent (C). [5] A method for producing an adhesive composition as described in [4], wherein the crosslinking agent (C) is at least one selected from the group consisting of polyisocyanates and polyepoxides. [6] A method for producing an adhesive layer, comprising the step of forming a cross-linked structure in an adhesive composition obtained by the production method described in [4] or [5]. [7] A method for producing an adhesive sheet, comprising applying the adhesive composition obtained by the production method described in [4] or [5] to a sheet-like substrate to produce an adhesive layer. [8] A method for producing an adhesive sheet, comprising the step of forming a cross-linked structure in an adhesive layer obtained by the production method described in [7]. [9] A method for producing a dicing-die bonding integrated film, comprising bonding an adhesive layer on the adhesive layer having a cross-linked structure obtained by the production method described in [8]. [10] A method for manufacturing a dicing-die bonding integrated thin film, comprising applying an adhesive composition obtained by the manufacturing method described in [4] or [5] to an adhesive layer.

By using the (meth) acrylic resin obtained by the method disclosed herein as an adhesive layer for a dicing-die bonding integral film, an adhesive layer can be provided, which has sufficient adhesion to the adhesive layer and has excellent releasability when the adhesive sheet is peeled off from the adhesive layer after UV irradiation, and is not prone to the generation of adhesive residues.

[Form of implementing the invention]

The following describes the embodiments of the present invention in detail. However, the present invention is not limited to the embodiments described below.

In this manual, when "~" is used for a numerical range, the numerical values at both ends are the upper limit and the lower limit, respectively, and are included in the numerical range.

In the present specification, "(meth)acryl" means methacryl or acrylate, "(meth)acrylate" means acrylate or methacrylate, and "(meth)acryloyloxy" means acryloxy or methacryloyloxy.

In this specification, "weight average molecular weight" and "number average molecular weight" are values obtained by using gel permeation chromatography (GPC) under the following conditions at room temperature (23°C) and using a standard polystyrene calibration curve. Apparatus: Shodex (trademark) GPC-101 (Showa Denko Co., Ltd.) Column: Shodex (trademark) LF-804 (Showa Denko Co., Ltd.) Column temperature: 40°C Sample: 0.2 mass% tetrahydrofuran solution of the sample Flow rate: 1 mL/min Eluent: tetrahydrofuran Detector: Shodex (trademark) RI-71S (Showa Denko Co., Ltd.)

In this specification, "glass transition temperature (Tg)" is the endothermic start temperature of the glass transition observed by measuring the temperature of a 10 mg sample from -100°C to 200°C using a differential scanning calorimeter (DSC) at a heating rate of 10°C/min. When two or more endothermic start temperatures are observed, Tg is the simple average of the two or more endothermic start temperatures.

[Method for producing (meth)acrylic resin (A) having ethylenically unsaturated groups] The method for producing (meth)acrylic resin (A) having ethylenically unsaturated groups (hereinafter referred to as "(meth)acrylic resin (A)") comprises: a step (i) of polymerizing a raw material monomer group (M) containing a hydroxyl group-containing (meth)acrylic ester (m-1) and an alkyl (meth)acrylic ester (m-2) by reversible addition-fragmentation chain transfer (RAFT) to obtain a copolymer (A-0); and a step (ii) of adding an ethylenically unsaturated compound (a) containing an isocyanate group to a part of the side chain hydroxyl groups of the copolymer (A-0) to obtain the (meth)acrylic resin (A). The raw material monomer group (M) may contain a carboxyl group-containing monomer (m-3).

<Step (i)> The copolymer (A-0) is obtained by RAFT polymerization of a raw monomer group (M) containing a hydroxyl-containing (meth)acrylate (m-1), an alkyl (meth)acrylate (m-2) and an arbitrarily selected carboxyl-containing monomer (m-3) in the presence of a reversible addition-fragmentation chain transfer agent (RAFT agent). In the present specification, RAFT polymerization means free radical polymerization in the presence of a RAFT agent. RAFT polymerization is a type of living free radical polymerization. Living free radical polymerization is generally known as a polymerization method that can obtain a polymer with a small molecular weight distribution. Specific examples thereof include atom transfer radical polymerization, organic tellurium-mediated free radical polymerization, RAFT polymerization, etc. Among these, RAFT polymerization does not use halogens and heavy metals, so it has low environmental load and is suitable for semiconductor applications. Without being bound by any theory, the copolymer (A-0) obtained by RAFT polymerization has a molecular weight distribution that is more appropriate than that of (meth)acrylic copolymers obtained by other living free radical polymerizations. Therefore, the adhesive composition produced using the (meth)acrylic resin (A) obtained from the copolymer (A-0) has excellent wettability of the adhesive layer and has high adhesion. This is because the low molecular weight component of the (meth)acrylic resin (A) contributes to the wettability and fluidity of the adhesive composition. When the molecular weight distribution of the (meth)acrylic acid copolymer is too narrow, the fluidity of the resulting adhesive composition and the wettability of the adhesive layer are low, and sufficient adhesion cannot be obtained.

As the polymerization method, solution polymerization, emulsion polymerization, bulk polymerization, suspension polymerization, alternating copolymerization, etc. can be used. Among these polymerization methods, solution polymerization is preferably used in view of the ease of reaction when the addition reaction in step (ii) is taken into consideration.

(Hydroxy-containing (meth)acrylate (m-1)) Hydroxy-containing (meth)acrylate (m-1) is not particularly limited as long as it has a hydroxyl group and a (meth)acryloyloxy group. Specifically, hydroxyalkyl (meth)acrylates such as 2-hydroxyethyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 2,3-dihydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, etc.; (meth)acrylates having an aromatic ring and a hydroxyl group such as hydroxyphenyl (meth)acrylate and 2-hydroxy-3-phenoxypropyl (meth)acrylate, etc. can be cited. Among them, from the perspective of the peelability of the adhesive sheet after UV irradiation, hydroxyalkyl (meth)acrylate is preferred, and hydroxyalkyl (meth)acrylate having 1 to 6 carbon atoms in the hydroxyalkyl group is more preferred, and 2-hydroxyethyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate and 4-hydroxybutyl (meth)acrylate are particularly preferred.

The content of the hydroxyl-containing (meth)acrylate (m-1) is preferably 5 to 50 mol%, more preferably 10 to 40 mol%, and particularly preferably 15 to 35 mol% relative to 100 mol% of the raw monomer group (M). If the content of the hydroxyl-containing (meth)acrylate (m-1) is 5 mol% or more, the (meth)acrylate resin (A) has sufficient hydroxyl groups to ensure the amount of crosslinking with the crosslinking agent (C), thereby obtaining an adhesive layer with sufficient cohesive force. In addition, the reaction sites for introducing ethylenic unsaturated groups can also be ensured, and better releasability can be obtained when the adhesive sheet is peeled off from the attached body after UV irradiation. On the other hand, if the content of the hydroxyl-containing (meth)acrylate (m-1) is 50 mol % or less, the progress of unexpected reactions in the adhesive composition can be suppressed, and the storage stability is good.

((Meth) acrylate alkyl ester (m-2)) (Meth) acrylate alkyl ester (m-2) is not particularly limited as long as it does not have a hydroxyl group and a carboxyl group but has an alkyl group and a (meth) acryloyloxy group. Specifically, alkyl (meth)acrylates such as methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, isopropyl (meth)acrylate, n-butyl (meth)acrylate, tert-butyl (meth)acrylate, pentyl (meth)acrylate, neopentyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, isopentyl (meth)acrylate, and dodecyl (meth)acrylate; and alicyclic alkyl (meth)acrylates such as cyclopentyl (meth)acrylate, cyclohexyl (meth)acrylate, ethylcyclohexyl (meth)acrylate, norbornyl (meth)acrylate, dicyclopentyl (meth)acrylate, isobornyl (meth)acrylate, and adamantyl (meth)acrylate can be mentioned. The alkyl group in the alkyl (meth)acrylate (m-2) can be substituted. As the substituent, for example, alkoxy groups such as methoxy and ethoxy can be mentioned. Among them, from the viewpoint of the peeling property of the adhesive sheet after UV irradiation, alkyl (meth)acrylates and alicyclic alkyl (meth)acrylates having an alkyl group with 1 to 20 carbon atoms are preferred, and one or more selected from methyl (meth)acrylate, ethyl (meth)acrylate, 2-methoxyethyl (meth)acrylate, propyl (meth)acrylate, butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, dodecyl (meth)acrylate, cyclohexyl (meth)acrylate, isoborneol (meth)acrylate and dicyclopentyl (meth)acrylate are more preferred.

The content of the (meth) alkyl ester (m-2) is preferably 10 to 94 mol%, more preferably 30 to 85 mol%, and particularly preferably 50 to 80 mol% relative to 100 mol% of the raw monomer group (M). If the content of the (meth) alkyl ester (m-2) is 10 mol% or more, excellent adhesion can be obtained. If the content of the (meth) alkyl ester (m-2) is 94 mol% or less, the content of the hydroxyl group and the ethylenic unsaturated group of the (meth) acrylic resin (A) can be sufficiently ensured, thereby obtaining an adhesive layer with balanced physical properties from the viewpoint of the cohesive force of the adhesive layer and the releasability of the adhesive sheet after UV irradiation.

(Carboxyl-containing monomer (m-3)) Carboxyl-containing monomer (m-3) is not particularly limited as long as it is a monomer that does not have a hydroxyl group but has a carboxyl group and an ethylenically unsaturated group. For example, unsaturated monobasic acids such as (meth)acrylic acid, crotonic acid, vinylbenzoic acid, α-halogenated, alkoxy, halogen, nitro or cyano substituents of acrylic acid, and unsaturated dibasic acids such as itaconic acid can be cited. Among them, (meth)acrylic acid is preferred from the perspective of ease of manufacturing the adhesive.

When a carboxyl group-containing monomer (m-3) is used, the content of the carboxyl group-containing monomer (m-3) is preferably 0.1 to 10 mol%, more preferably 0.5 to 8.0 mol%, and particularly preferably 1.0 to 5.0 mol, relative to 100 mol% of the raw monomer group (M). If the content of the carboxyl group-containing monomer (m-3) is 0.1 mol% or more, when the crosslinking agent (C) is a polyepoxide, a sufficient amount of crosslinking can be ensured, and sufficient cohesion of the adhesive can be obtained. If the content of the carboxyl group-containing monomer (m-3) is 10 mol% or less, the content of the hydroxyl group and the ethylenically unsaturated group of the (meth)acrylic resin (A) can be sufficiently ensured, so that an adhesive layer having balanced physical properties can be obtained from the viewpoint of the cohesive force of the adhesive layer and the releasability of the adhesive sheet after UV irradiation.

In the raw material monomer group (M), the molar ratio of the hydroxyl-containing (meth)acrylate (m-1), the (meth)acrylate alkyl (m-2) and the carboxyl-containing monomer (m-3) is preferably (m-1): (m-2): (m-3) = 10-70: 30-90: 0-10, and more preferably (m-1): (m-2): (m-3) = 15-35: 65-85: 0-5.

(Other monomers (m-4)) The raw material monomer group (M) may include other monomers (m-4) other than (m-1) to (m-3). Specific examples include dienes such as butadiene and dicyclopentadiene, styrenes, unsaturated dicarboxylic acid diesters, and other vinyl compounds.

Specific examples of styrenes include styrene and α-, o-, m- or p-alkyl derivatives of styrene.

Specific examples of the unsaturated dicarboxylic acid diester include diethyl liconate, diethyl maleate, diethyl fumarate, diethyl itaconate, and the like.

Specific examples of other vinyl compounds include norbornene (bicyclo[2.2.1]hept-2-ene), 5-methylbicyclo[2.2.1]hept-2-ene, 5-ethylbicyclo[2.2.1]hept-2-ene, tetracyclo[4.4.0.1 ^2,5 .1 ^7,10 ]dodec-3-ene, 8-methyltetracyclo[4.4.0.1 ^2,5 .1 ^{7,10 ]dodec-3-ene, 8-ethyltetracyclo[4.4.0.1 2,5 .1 7,10 ] dodec} -3-ene, tricyclo[5.2.1.0 ^2,6 ]dec-8-ene, tricyclo[5.2.1.0 ^2,6 ]dec-3-ene, tricyclo[4.4.0.1 ^2,5 .1 ^7,10 .0 ^1,6 ]dodec-3-ene, tricyclo[4.4.0.1 2,5 ^.1 7,12 ]dodec-3-ene, tricyclo[6.2.1.0 ^1,8 ]undec-9-ene, tricyclo[6.2.1.0 ^1,8 ]undec-4-ene, tetracyclo[4.4.0.1 ^2,5 .1 ^7,10 .0 ^1,6 ]dodec-3-ene, 8-methyltetracyclo[4.4.0.1 ^{2,5 .1 7,10 .0 1,6 ]dodec-3-ene, 8-ethylenetetracyclo[4.4.0.1 2,5} .1 ^7,12 ]dodec-3-ene, 8-ethylenetetracyclo[4.4.0.1 ^2,5 .1 ^7,10 .0 ^1,6 ] dodeca-3-ene, pentacyclo[6.5.1.1 ^3,6 .0 ^2,7 .0 ^9,13 ] pentadeca-4-ene, pentacyclo[7.4.0.1 ^2,5 .1 ^9,12 .0 ^8,13 ] pentadeca-3-ene, (meth)acrylic acid acylaniline, vinylpyridine, ethyl acetate, etc.

(Reversible addition fragmentation chain transfer agent (RAFT agent)) As the RAFT agent, well-known ones can be used without particular limitation. For example, preferably, a sulfur compound (trithiocarbonate, dithioester, dithiocarbonate and dithiocarbamate) represented by the following formula (1), formula (2), formula (3) or formula (4) is used.

≪Trithiocarbonate≫ (In formula (1), R ^1a and R ^1b are the same or different and represent a hydrogen atom, a hydrocarbon group, a carboxyl group or a cyano group; R ^1c represents a cyano group, a saturated or unsaturated aliphatic hydrocarbon group which may be substituted with a cyano group or a carboxyl group, or a substituted phenyl group; R ² represents a saturated or unsaturated aliphatic hydrocarbon group in which a part of the hydrogen atom may be substituted with a carboxyl group, or a substituted benzyl group).

≪Dithioester≫ (In formula (2), R ^3a and R ^3b are the same or different and represent a hydrogen atom, a alkyl group or a cyano group, R ^3c represents a carboxyl group, an acetyloxymethyl group, or a alkyl group which may be substituted by a cyano group or a carboxyl group, and R ⁴ represents a alkyl group).

≪Dithiocarbonate≫ (In formula (3), ^R5a and ^R5b are the same or different and represent a hydrogen atom, a alkyl group, a carboxyl group which may be substituted by a saturated aliphatic alkyl group having 1 to 3 carbon atoms, or a cyano group; ^R5c represents a alkyl group which may be substituted by an alkoxy group; and ^R6 represents a alkyl group).

≪Dithiocarbamate≫ (In formula (4), ^R7a and ^R7b are the same or different and represent a hydrogen atom or a alkyl group, ^R7c represents a cyano group, ^R8 and ^R9 are the same or different and represent a alkyl group, or ^R8 and ^R9 may be bonded to form a saturated aliphatic alkyl group having 1 to 3 carbon atoms or a pyrazole ring which may be substituted by a chlorine atom).

In formula (1), examples of the alkyl group represented by R ^1a and R ^1b include linear, branched or cyclic saturated or unsaturated alkyl groups having 1 to 20 carbon atoms, and preferably linear, branched or cyclic saturated or unsaturated alkyl groups having 1 to 12 carbon atoms. Examples of the alkyl group include linear, branched or cyclic saturated aliphatic alkyl groups having 1 to 20 carbon atoms such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, cyclohexyl, dodecyl, octadecyl, etc.; aryl groups having 6 to 12 carbon atoms such as phenyl; and arylalkyl groups having 7 to 10 carbon atoms such as benzyl and phenethyl. In formula (1), examples of the saturated or unsaturated aliphatic hydrocarbon group represented by R ^1c include linear, branched or cyclic saturated or unsaturated aliphatic hydrocarbon groups having 1 to 20 carbon atoms, and preferably linear, branched or cyclic saturated or unsaturated aliphatic hydrocarbon groups having 1 to 12 carbon atoms. Examples of the aliphatic hydrocarbon group include linear, branched or cyclic saturated aliphatic hydrocarbon groups having 1 to 20 carbon atoms such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, t-butyl, cyclohexyl, dodecyl, octadecyl, and the like. In the formula (1), 1 to 3 hydrogen atoms of the saturated or unsaturated aliphatic hydrocarbon group represented by R ^1c may be substituted by, for example, a carboxyl group or a cyano group, and the carboxyl group may be further substituted by a saturated aliphatic hydrocarbon group having 1 to 3 carbon atoms. In the formula (1), examples of the substituent of the phenyl group represented by R ^1c which may be substituted include a substituted carbamoyl group, an alkoxycarbonyl group having 2 to 5 carbon atoms which may be substituted by a hydroxyl group, and an alkenyloxycarbonyl group having 3 to 5 carbon atoms. Examples of the substituent of the substituted carbamoyl group include a saturated aliphatic hydrocarbon group having 1 to 3 carbon atoms which may be substituted by a hydroxyl group or an acetyloxy group. In the formula (1), the saturated or unsaturated aliphatic hydrocarbon group represented by R ² includes, for example, a linear, branched or cyclic saturated or unsaturated aliphatic hydrocarbon group having 1 to 20 carbon atoms, and preferably an aliphatic hydrocarbon group having 1 to 12 carbon atoms. Examples of the above-mentioned aliphatic hydrocarbon group include a linear, branched or cyclic saturated aliphatic hydrocarbon group having 1 to 20 carbon atoms such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, cyclohexyl, dodecyl, octadecyl, etc. In the formula (1), 1 to 3 hydrogen atoms of the saturated or unsaturated aliphatic hydrocarbon group represented by R ² may be substituted with carboxyl groups. In formula (1), as the substituent of the benzyl group which may be substituted represented by ^R2 , there can be mentioned a substituted carbamoyl group, an alkoxycarbonyl group having 2 to 5 carbon atoms which may be substituted with a hydroxyl group, an alkenyloxycarbonyl group having 3 to 5 carbon atoms, and the like. As the substituent of the substituted carbamoyl group, there can be mentioned a saturated aliphatic hydrocarbon group having 1 to 3 carbon atoms which may be substituted with a hydroxyl group or an acetyloxy group, and the like. R ^1a and R ^1b are the same or different and are hydrogen atoms, alkyl groups having 1 to 4 carbon atoms or carboxyl groups, R ^1c is alkyl groups having 1 to 4 carbon atoms or phenyl groups which may be substituted, R ² is a linear, branched or cyclic saturated or unsaturated aliphatic alkyl group having 1 to 20 carbon atoms, or a benzyl group which may be substituted, and the compound represented by formula (1) is preferred. R ^1a and R ^1b are hydrogen atoms, a combination of methyl or ethyl groups and carboxyl groups, or a hydrogen atom, R ^1c is methyl, ethyl or phenyl groups which may be substituted, and R ² is a linear saturated aliphatic alkyl group having 1 to 20 carbon atoms or a benzyl group which may be substituted, and the compound represented by formula (1) is more preferred.

In formula (2), examples of the alkyl group represented by R ^3a , R ^3b , R ^3c and R ⁴ include linear, branched or cyclic saturated or unsaturated alkyl groups having 1 to 20 carbon atoms, and preferably linear, branched or cyclic saturated or unsaturated alkyl groups having 1 to 12 carbon atoms. Examples of the alkyl group include linear, branched or cyclic saturated aliphatic alkyl groups having 1 to 20 carbon atoms such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, cyclohexyl, dodecyl and octadecyl; aryl groups having 6 to 12 carbon atoms such as phenyl; and arylalkyl groups having 7 to 10 carbon atoms such as benzyl and phenethyl. In formula (2), examples of the alkyl group which may be substituted with a cyano group or a carboxyl group represented by R ^3c include groups in which 1 to 3 hydrogen atoms of the above-mentioned alkyl groups are substituted with a cyano group or a carboxyl group. Among these, the compound represented by formula (2) is preferably one in which R ^3a and R ^3b are the same or different and are a linear saturated alkyl group having 1 to 4 carbon atoms, R ^3c is an aryl group, and R ⁴ is an aryl group or a benzyl group. The compound represented by formula (2) is more preferably one in which R ^3a and R ^3b are the same or different and are a methyl group or an ethyl group, R ^3c is a phenyl group, and R ⁴ is a phenyl group or a benzyl group.

In formula (3), examples of the alkyl group represented by R ^5a , R ^5b , R ^5c and R ⁶ include linear, branched or cyclic saturated or unsaturated alkyl groups having 1 to 20 carbon atoms, and preferably linear, branched or cyclic saturated or unsaturated alkyl groups having 1 to 12 carbon atoms. Examples of the alkyl group include linear, branched or cyclic saturated aliphatic alkyl groups having 1 to 20 carbon atoms such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, cyclohexyl, dodecyl and octadecyl; aryl groups having 6 to 12 carbon atoms such as phenyl; and arylalkyl groups having 7 to 10 carbon atoms such as benzyl and phenethyl. In the formula (3), examples of the alkyl group which may be substituted with an alkoxy group represented by R ^5c include groups in which 1 to 3 hydrogen atoms possessed by the above-mentioned alkyl groups are substituted with an alkoxy group.

In formula (4), examples of the alkyl group represented by ^R7a , ^R7b , ^R8 and ^R9 include linear, branched or cyclic saturated or unsaturated alkyl groups having 1 to 20 carbon atoms, and preferably linear, branched or cyclic saturated or unsaturated alkyl groups having 1 to 12 carbon atoms. Examples of the alkyl group include linear, branched or cyclic saturated aliphatic alkyl groups having 1 to 20 carbon atoms such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, cyclohexyl, dodecyl and octadecyl; aryl groups having 6 to 12 carbon atoms such as phenyl; and arylalkyl groups having 7 to 10 carbon atoms such as benzyl and phenethyl. ^R8 and ^R9 may form a pyrazole ring together with the nitrogen atom in formula (4). The pyrazole ring may be substituted with a saturated aliphatic hydrocarbon group having 1 to 3 carbon atoms or a chlorine atom.

When polymerization is carried out in the presence of a RAFT agent represented by formula (1) to (4), free radical species undergo a chain reaction between the sulfur atom in the RAFT agent and the carbon atom adjacent to the sulfur atom, and polymerization proceeds simultaneously. Among them, the RAFT agents represented by formula (1) and (2) are preferred from the viewpoint of ease of polymerization.

Most RAFT agents are commercially available. Those that are not commercially available can be easily synthesized by well-known or conventional methods.

Specific examples of the RAFT agent include S-cyanomethyl-S-dodecyl trithiocarbonate, 2-[(dodecyl alkylthiocarbonyl) alkyl] propionic acid, 2-{[(2-carboxyethyl) alkylthiocarbonyl] alkyl} propionic acid, bis{4-[ethyl-(2-hydroxyethyl)carbamoyl]benzyl} trithiocarbonate, 4-[(2-carboxyethyl alkylthiocarbonyl) alkyl]-4-cyanopentanoic acid, 4-cyano-4-[(dodecyl alkylthiocarbonyl) alkyl] alkyl] pentanoic acid, S,S-dibenzyl trithiocarbonate, 2-[(dodecyl alkylthiocarbonyl) alkyl] propionic acid, 2-[(2-carboxyethyl) alkylthiocarbonyl] alkyl] propionic acid, bis{4-[ethyl-(2-hydroxyethyl)carbamoyl]benzyl} trithiocarbonate, 4-[(2-carboxyethyl alkylthiocarbonyl) alkyl]-4-cyanopentanoic acid, 4-cyano-4-[(dodecyl alkylthiocarbonyl) alkyl] alkyl] pentanoic acid, S,S-dibenzyl trithiocarbonate, 2-[(dodecyl alkylthiocarbonyl) alkyl] alkyl] propionic acid, 2-[(2-carboxyethyl) alkylthiocarbonyl ... Thiocarbonates, methyl 4-cyano-4-[(dodecylthiocarbonyl)thiocarbonyl]pentanoate, 2-cyano-2-propyldodecyl trithiocarbonate, bis[4-(allyloxycarbonyl)benzyl]trithiocarbonate, bis[4-(2,3-dihydroxypropoxycarbonyl)benzyl]trithiocarbonate, bis{4-[ethyl-(2-acetyloxyethyl)aminoformyl]benzyl}trithiocarbonate, bis[4-(2-hydroxyethoxycarbonyl)benzyl]trithiocarbonate, etc. ; dithioesters of cyanoethyl dithiopropionate, benzyl dithiopropionate, benzyl dithiobenzoate, ethyloxyethyl dithiobenzoate, 2-phenyl-2-propyl dithiobenzoic acid, 2-cyano-2-propyl dithiobenzoic acid, 4-cyano-4-(phenylthiocarbonylthio)pentanoic acid, S-(thiobenzoyl)thioglycolic acid, etc.; ethyl 2-[(ethoxythiocarbonyl)thio]propionate, O-ethyl-S-(2-propoxyethyl) dithiocarbonate, O-ethyl-S-(1- dithiocarboxylates such as cyano-1-methylethyl)dithiocarboxylates; dithiocarboxylates such as 2-cyano-2-propyldiethyldithiocarboxylate, 2'-cyanobutane-2'-yl 4-chloro-3,5-dimethylpyrazole-1-dithiocarboxylate, 2'-cyanobutane-2'-yl 3,5-dimethylpyrazole-1-dithiocarboxylate, cyanomethyl 3,5-dimethylpyrazole-1-dithiocarboxylate, cyanomethyl N-methyl-N-phenyldithiocarboxylate, etc. Among them, from the viewpoint of the ease of polymerization of the (meth)acrylic resin (A), trithiocarbonates and dithioesters are preferred, and 2-[(dodecylalkylthiocarbonyl)alkyl]propionic acid, 2-{[(2-carboxyethyl)alkylthiocarbonyl]alkyl}propionic acid, 2-phenyl-2-propyldithiobenzoic acid, S,S-dibenzyl trithiocarbonate and bis{4-[ethyl-(2-acetyloxyethyl)aminocarbonyl]benzyl}trithiocarbonate are more preferred.

The RAFT agent may be used alone or in combination of two or more.

(Free radical polymerization initiator) RAFT polymerization is preferably carried out in the presence of a free radical polymerization initiator. Examples of the free radical polymerization initiator include conventional organic free radical polymerization initiators, specifically, 2,2'-azobis(isobutyronitrile), 2,2'-azobis(4-methoxy-2,4-dimethylvaleronitrile), 2,2'-azobis(2,4-dimethylvaleronitrile), 2,2'-azobis(2-methylbutyronitrile), 1,1'-azobis(cyclohexane-1-carbonitrile), 2,2'-azobis(2,4,4-triazine), 2,2'-azobis(2,4-dimethylvaleronitrile), 2,2'-azobis(2,4-dimethylvaleronitrile), 2,2'-azobis(2,4-dimethylbutyronitrile), 1,1'-azobis(cyclohexane-1-carbonitrile), 2,2'-azobis(2,4,4-triazine), 2,2'-azobis(2,4,4-triazine), 2,2'-azobis(2,4-dimethylvaleronitrile), 2,2'-azobis(2,4-dimethylvaleronitrile), 2,2'-azobis(2,4-dimethylbutyronitrile ... Azo-based polymerization initiators such as 2-methylpentane), dimethyl-2,2'-azobis(2-methylpropionate); and peroxide-based polymerization initiators such as benzoyl peroxide, tert-butyl hydroperoxide, di-tert-butyl peroxide, tert-butyl peroxybenzoate, isopropyl peroxide, 1,1-bis(tert-butylperoxy)-3,3,5-trimethylcyclohexane, 1,1-bis(tert-butylperoxy)cyclododecane, etc., as well as oil-soluble polymerization initiators.

The radical polymerization initiator may be used alone or in combination of two or more.

The amount of the free radical polymerization initiator used is preferably 0.001 to 5 parts by mass, more preferably 0.005 to 3 parts by mass, and particularly preferably 0.01 to 1 part by mass, relative to 100 parts by mass of the total amount of the raw monomer group (M).

(Solvent) As the solvent used in RAFT polymerization, a general solvent can be used. Examples of the solvent include esters such as ethyl acetate, propyl acetate, and butyl acetate; aromatic hydrocarbons such as toluene, xylene, and benzene; aliphatic hydrocarbons such as hexane and heptane; alicyclic hydrocarbons such as cyclohexane and methylcyclohexane; ketones such as methyl ethyl ketone and methyl isobutyl ketone; glycols such as ethylene glycol, propylene glycol, and dipropylene glycol; glycol ethers such as methyl cellulose, propylene glycol monomethyl ether, and dipropylene glycol monomethyl ether; and glycol esters such as ethylene glycol diacetate and propylene glycol monomethyl ether acetate. The solvent may be used alone or in combination of two or more.

(Reaction conditions) The reaction temperature of RAFT polymerization also depends on the type of free radical polymerization initiator used, but is usually 30℃～130℃, preferably 40℃～120℃, and more preferably 50℃～110℃. If the temperature during RAFT polymerization is above 30℃, a sufficient reaction rate can be obtained. If the temperature during RAFT polymerization is below 130℃, the danger during production is less.

The reaction time of RAFT polymerization also depends on the types of the raw monomer group (M), RAFT agent and free radical polymerization initiator used, but is generally 3 to 30 hours, preferably 4 to 20 hours, and more preferably 5 to 15 hours. If the reaction time is 3 hours or longer, the copolymer (A-0) can be produced from the raw monomer group (M) with an appropriate degree of polymerization, and if the reaction time is 30 hours or shorter, the production can be carried out efficiently.

<Step (ii)> The (meth) acrylic resin (A) is obtained by adding an isocyanate-containing ethylenically unsaturated compound (a) to a portion of the side chain hydroxyl groups of the hydroxyl-containing (meth) acrylic ester (m-1) possessed by the copolymer (A-0). If the isocyanate-containing ethylenically unsaturated compound (a) is added to all the side chain hydroxyl groups of the copolymer (A-0), the reaction site with the crosslinking agent (C) described later disappears, and thus the addition is retained on a portion of the side chain hydroxyl groups. Specifically, taking the side chain hydroxyl groups as 100 mol %, the addition reaction is preferably 5.0 to 99 mol %. There is no particular limitation on the method of adding the isocyanate group-containing ethylenically unsaturated compound (a), and any method known in the art of this specification can be used. Since the (meth)acrylic resin (A) has an ethylenically unsaturated group in the side chain, the length of the molecular chain between the crosslinking points is relatively short compared to the (meth)acrylic copolymer having an ethylenically unsaturated group introduced at the end, and the adhesive force can be greatly reduced after UV irradiation. Therefore, the adhesive sheet using the (meth)acrylic resin (A) has excellent releasability from the attached body. In addition, since the (meth)acrylic resin (A) has an appropriate molecular weight distribution, the adhesive composition produced using the meth)acrylic resin (A) has excellent adhesion to the adhesive layer. Therefore, the adhesive composition made using the (meth) acrylic resin (A) is suitable for the adhesive layer of the monolithic film for dicing-die bonding.

The molecular weight distribution (Mw/Mn) of the (meth)acrylic resin (A) is preferably 2.4 or more, more preferably 2.5 or more, and particularly preferably 3.0 or more. The molecular weight distribution of the (meth)acrylic resin (A) is preferably 10.0 or less, more preferably 6.0 or less, particularly preferably 5.8 or less, and particularly preferably 5.6 or less. The combination of the lower limit and the upper limit may be any combination. The molecular weight distribution of the (meth)acrylic resin (A) is preferably 2.4 to 10.0, more preferably 2.4 to 6.0, particularly preferably 2.5 to 5.8, and particularly preferably 3.0 to 5.6. If the molecular weight distribution is 2.4 or more, the wettability of the adhesive composition containing the (meth)acrylic resin (A) is improved, and the adhesion to the adherend, especially the adhesive layer, is good. If the molecular weight distribution is 10.0 or less, the (meth) acrylic resin (A) in the high molecular weight region is within an appropriate range, so the viscosity of the adhesive composition is easily controlled, and since the (meth) acrylic resin (A) in the low molecular weight region is within an appropriate range, the residual adhesive when the adhesive sheet is peeled off from the adherend is suppressed.

The weight average molecular weight (Mw) of the (meth) acrylic resin (A) is preferably 100,000 or more, more preferably 150,000 or more, particularly preferably 200,000 or more, and particularly preferably 300,000 or more. The weight average molecular weight of the (meth) acrylic resin (A) is preferably 800,000 or less, more preferably 700,000 or less, and particularly preferably 650,000 or less. The combination of the lower limit and the upper limit may be any combination. The weight average molecular weight (Mw) of the (meth) acrylic resin (A) is preferably 100,000 to 800,000, more preferably 150,000 to 700,000, particularly preferably 200,000 to 650,000, and particularly preferably 300,000 to 650,000. If the weight average molecular weight is 100,000 or more, the peeling property after UV irradiation is improved. If the weight average molecular weight is 800,000 or less, the viscosity of the adhesive composition containing the (meth)acrylic resin (A) can be appropriately suppressed, and the workability of the adhesive composition can be improved.

The ethylenic unsaturated group equivalent weight of the (meth)acrylic resin (A) is preferably 100 to 3,000 g/mol, more preferably 300 to 2,500 g/mol, and particularly preferably 500 to 2,000 g/mol. If it is within the above range, the crosslinking amount of the adhesive composition during UV irradiation is sufficient, and excellent peeling properties when the adhesive sheet made using the (meth)acrylic resin (A) is peeled off from the attached body and excellent pickup properties of small-chip components are obtained. In this specification, the ethylenic unsaturated group equivalent weight of the (meth)acrylic resin (A) is the mass of the (meth)acrylic resin (A) per mole of ethylenic unsaturated bonds. The ethylenically unsaturated group equivalent of the (meth)acrylic resin (A) in one embodiment is a calculated value calculated from the feed amount assuming that each raw material used in the production of the (meth)acrylic resin (A) reacts 100%. The ethylenically unsaturated group equivalent of the (meth)acrylic resin (A) can be calculated from the amount of halogen bound to the (meth)acrylic resin (A). The amount of halogen bound to the (meth)acrylic resin (A) can be evaluated in accordance with JIS K 0070:1992.

The glass transition temperature (Tg) of the (meth) acrylic resin (A) is preferably -80°C to 0°C, more preferably -70°C to -10°C, and particularly preferably -60°C to -30°C. If the glass transition temperature (Tg) is -80°C or higher, the cohesive force of the adhesive composition increases, suppressing residual adhesive. If the glass transition temperature (Tg) is 0°C or lower, sufficient fixation and bonding strength are obtained during the processing of the attached object.

When the raw monomer group (M) contains a carboxyl group-containing monomer (m-3), the acid value of the (meth) acrylic resin (A) is preferably 0.5 to 100 mgKOH/g, more preferably 1.0 to 50 mgKOH/g, and particularly preferably 3.0 to 25 mgKOH/g. If the acid value is 0.5 mgKOH/g or more, when a polyepoxide is used as a crosslinking agent (C), a sufficient amount of crosslinking can be ensured, and the cohesive force of the adhesive layer can be fully ensured. If the acid value is 100 mgKOH/g or less, the storage stability of the adhesive composition is good. The acid value in this specification is the value measured in accordance with JIS K 0070:1992.

(Isocyanate-containing ethylenically unsaturated compound (a)) The isocyanate-containing ethylenically unsaturated compound (a) is not particularly limited as long as it is a compound having an isocyanate group and an ethylenically unsaturated group but having no hydroxyl group or carboxyl group. Specifically, (meth)acryloyloxyalkyl isocyanates such as 2-isocyanatoethyl (meth)acrylate, 2-isocyanatopropyl (meth)acrylate, 3-isocyanatopropyl (meth)acrylate, 2-isocyanato-1-methylethyl (meth)acrylate, 2-isocyanato-1,1-dimethylethyl (meth)acrylate, 4-isocyanatocyclohexyl (meth)acrylate, 2-(2-isocyanatoethoxy)ethyl (meth)acrylate, 1,1-(bis(meth)acryloyloxymethyl)ethyl isocyanate, etc. can be cited. Among them, from the viewpoint of the ease of synthesis of the (meth)acrylic resin (A), (meth)acryloyloxyalkyl isocyanate is preferred, and 2-isocyanatoethyl (meth)acrylate is more preferred.

The content of the ethylenically unsaturated compound (a) containing an isocyanate group is preferably 0.25 mol or more, more preferably 0.50 mol or more, and particularly preferably 1.0 mol or more relative to 100 mol of the raw monomer group (M). The content of the ethylenically unsaturated compound (a) containing an isocyanate group is preferably 49 mol or less, more preferably 47 mol or less, and particularly preferably 45 mol or less. The combination of the lower limit and the upper limit may be any combination. The content of the ethylenically unsaturated compound (a) containing an isocyanate group is preferably 0.25 to 49 mol, more preferably 0.50 to 47 mol, and particularly preferably 1.0 to 45 mol relative to 100 mol of the raw monomer group (M). If the content of the isocyanate group-containing ethylenically unsaturated compound (a) is 0.25 mol or more, a sufficient amount of ethylenically unsaturated groups are introduced into the (meth)acrylic resin (A), and a better peeling property can be obtained when the adhesive sheet is peeled off from the attached body after UV irradiation. If the content of the isocyanate group-containing ethylenically unsaturated compound (a) is 49 mol or less, the hydroxyl content of the (meth)acrylic resin (A) can be sufficiently ensured, and excellent cohesion of the adhesive layer can be obtained. In addition, since the amount of unreacted isocyanate group-containing ethylenically unsaturated compound (a) can be reduced, an adhesive sheet with less residual glue can be obtained.

(Catalyst) In the addition reaction of step (ii), a well-known catalyst can be used as needed. As the catalyst, for example, a carbamate catalyst such as dibutyltin dilaurate, titanium diisopropoxybis(ethylacetate), tetrakis(2,4-pentanedione)zirconium, bis(tris(2-ethylhexanoate)) and the like can be used.

When a catalyst is used in step (ii), the amount of the catalyst used is preferably 0.01 to 10 parts by mass, more preferably 0.02 to 5 parts by mass, and particularly preferably 0.03 to 1 part by mass, relative to 100 parts by mass of the total of the copolymer (A-0) and the isocyanate group-containing ethylenically unsaturated compound (a).

(Polymerization inhibitor) In the addition reaction of step (ii), a known polymerization inhibitor may be used as needed. As the polymerization inhibitor, known ones may be used without particular limitation, for example, 4-methoxyphenol, hydroquinone, methoquinone, 2,6-di-tert-butylphenol, 2,2'-methylenebis(4-methyl-6-tert-butylphenol) and phenanthridine. The polymerization inhibitor may be used alone or in combination of two or more.

When a polymerization inhibitor is used in step (ii), the amount of the polymerization inhibitor used is preferably 0.005 to 5 parts by mass, more preferably 0.03 to 3 parts by mass, and particularly preferably 0.05 to 1.5 parts by mass, relative to 100 parts by mass of the total of the copolymer (A-0) and the isocyanate group-containing ethylenically unsaturated compound (a). If the amount of the polymerization inhibitor used is 0.005 parts by mass or more, gelation during the addition reaction can be prevented. On the other hand, if the amount of the polymerization inhibitor used is 5 parts by mass or less, sufficient exposure sensitivity of the (meth)acrylic resin (A) during UV irradiation can be obtained.

(Reaction conditions) The temperature of the addition reaction is preferably 25°C to 130°C, and particularly preferably 40°C to 120°C. If the temperature of the addition reaction is 25°C or higher, a sufficient reaction rate can be obtained. If the temperature of the addition reaction is 130°C or lower, free radical polymerization caused by heat can be prevented from causing crosslinking of double bonds and the formation of gel.

During the addition reaction, a gas having a polymerization inhibiting effect may be introduced into the reaction system. By introducing a gas having a polymerization inhibiting effect into the reaction system, gelation during the addition reaction can be prevented.

As a gas having a polymerization inhibitory effect, there can be cited a gas containing oxygen to a degree that is not within the explosion range of the substances in the system, such as air.

It is more preferable to use a gas having a polymerization inhibitory effect together with a polymerization inhibitor because the amount of the polymerization inhibitor used can be reduced or the polymerization inhibitory effect can be enhanced.

[Method for producing adhesive composition] The adhesive composition can be produced by a method comprising step (iii) of mixing a (meth) acrylic resin (A), a photopolymerization initiator (B), a crosslinking agent (C) and other components as needed. The adhesive composition comprising the (meth) acrylic resin (A) is suitable for re-peelable adhesive sheets, especially dicing-die bonding integrated films.

The method for mixing the components contained in the adhesive composition is not particularly limited. The mixing can be performed using a stirring device equipped with stirring blades such as a homodispersor or a paddle.

<Photopolymerization initiator (B)> Examples of the photopolymerization initiator (B) include benzophenone, diphenylethanedione, benzoin, ω-bromoacetophenone, chloroacetone, acetophenone, 2,2-diethoxyacetophenone, 2,2-dimethoxy-2-phenylacetophenone, p-dimethylaminoacetophenone, p-dimethylaminoacetophenone, 2-chlorobenzophenone, 4,4'-dichlorobenzophenone, 4,4'-bis(diethylaminobenzophenone), Michler's ketone, benzoin methyl ether, benzyl alcohol, Carbonyl photopolymerization initiators such as isobutyl benzoate, n-butyl benzoate, benzyl methyl ketal, 1-hydroxycyclohexyl phenyl ketone, 2-hydroxy-2-methyl-1-phenyl-propane-1-one, 1-(4-isopropylphenyl)-2-hydroxy-2-methylpropane-1-one, methylbenzoylformate, 4'-dimethylaminoacetophenone, 2-methyl-1-[4-(methylthio)phenyl]-2-oxo-propane-1-one, etc.

Examples of the photopolymerization initiator (B) include sulfide-based photopolymerization initiators such as diphenyl disulfide, dibenzyl disulfide, tetraethylthiuram disulfide, and tetramethylammonium monosulfide; acylphosphine oxides such as 2,4,6-trimethylbenzyldiphenylphosphine oxide and 2,4,6-trimethylbenzylphenylethoxyphosphine oxide; quinone-based photopolymerization initiators such as benzoquinone and anthraquinone; sulfonyl chloride-based photopolymerization initiators; and thiothione-based photopolymerization initiators such as thiothione, 2-chlorothiothione, and 2-methylthiothione.

Among the photopolymerization initiators (B), carbonyl-based photopolymerization initiators and acylphosphine oxides are preferred from the viewpoint of solubility in the adhesive composition, and at least one selected from 1-hydroxycyclohexyl phenyl ketone and 2,4,6-trimethylbenzyldiphenylphosphine oxide is more preferred.

The photopolymerization initiator (B) may be used alone or in combination of two or more.

The photopolymerization initiator (B) is preferably in an amount of 0.1 to 5.0 parts by mass, more preferably 0.5 to 2.0 parts by mass, relative to 100 parts by mass of the (meth)acrylic resin (A). If the content of the photopolymerization initiator (B) is 0.1 parts by mass or more relative to 100 parts by mass of the (meth)acrylic resin (A), the adhesive composition can be cured at a sufficiently fast curing speed during UV irradiation, thereby sufficiently reducing the adhesive force of the adhesive layer after UV irradiation. If the content of the photopolymerization initiator (B) is 5.0 parts by mass or less relative to 100 parts by mass of the (meth)acrylic resin (A), the adhesive layer is less likely to remain on the adherend when the adhesive sheet having the adhesive layer containing the adhesive composition is attached to the adherend and then peeled off. Even if the content of the photopolymerization initiator (B) exceeds 5.0 parts by mass relative to 100 parts by mass of the (meth)acrylic resin (A), no effect commensurate with the content of the photopolymerization initiator (B) is observed, so by setting the content to 5.0 parts by mass or less, the adhesive composition can be economically produced.

<Crosslinking agent (C)> By mixing the crosslinking agent (C), an adhesive composition having a good balance between the adhesive force before UV irradiation and the adhesive force after UV irradiation can be obtained. The crosslinking agent (C) is a compound having no ethylenic unsaturated bond and having two or more functional groups that can react with the hydroxyl group contained in the (meth)acrylic resin (A) and/or the carboxyl group of any functional group contained therein.

As a crosslinking agent (C), there is no particular limitation, but preferably a compound having two or more functional groups reactive to a hydroxyl group. When the (meth) acrylic resin (A) has a carboxyl group, a compound having two or more functional groups reactive to a carboxyl group can be used. As a functional group reactive to a hydroxyl group, an isocyanate group, an epoxy group, a carboxyl group, an acid anhydride group, an aziridine group, etc. can be cited, but from the viewpoint of reactivity, an isocyanate group and an epoxy group are preferred, and an isocyanate group is particularly preferred. As a functional group reactive to a carboxyl group, an epoxy group, a hydroxyl group, an aziridine group, etc. can be cited, but from the viewpoint of reactivity, an epoxy group and an aziridine group are preferred.

Examples of the crosslinking agent (C) include 2,4-toluene diisocyanate, 2,6-toluene diisocyanate, hydrogenated toluene diisocyanate, 1,3-xylylenediisocyanate, 1,4-xylylenediisocyanate, diphenylmethane-4,4′-diisocyanate, isophorone diisocyanate, 1,3-bis(isocyanatomethyl)cyclohexane, isocyanurate of hexamethylene diisocyanate, tetramethylxylylenediisocyanate, 1,5-naphthalene diisocyanate, toluene diisocyanate adduct of trihydroxymethylpropane, xylylenediisocyanate adduct of trihydroxymethylpropane, triphenylmethane, and the like. triisocyanate, polyisocyanate of methylenebis(4-phenylmethane)triisocyanate, etc.; 1,3-bis(N,N'-diepoxypropylaminomethyl)cyclohexane, epoxy resin of bisphenol A-epichlorohydrin type, N,N'-[1,3-phenylenebis(methylene)]bis[bis(epoxyethane-2-ylmethyl)amine], ethylene glycol diepoxypropyl ether, polyethylene glycol diepoxypropyl ether, glycerol diepoxypropyl ether, glycerol triepoxypropyl ether, 1,6-hexanediol diepoxypropyl ether, trihydroxymethylpropane triepoxypropyl ether, sorbitol polyepoxypropyl ether, polyglycerol polyepoxypropyl ether, pentaerythritol polyepoxypropyl ether Polyepoxides such as propyl ether and diglycerol polyglycidyl ether; aziridine compounds such as tetrahydroxymethylmethane-tri-β-aziridine propionate, trihydroxymethylpropane-tri-β-aziridine propionate, N,N'-diphenylmethane-4,4'-bis(1-aziridine carboxylamide), N,N'-hexamethylene-1,6-bis(1-aziridine carboxylamide); melamine compounds such as hexamethoxymethyl melamine, hexaethoxymethyl melamine, hexapropoxymethyl melamine, hexabutoxymethyl melamine, hexapentoxymethyl melamine, hexahexyloxymethyl melamine; ethylene glycol-bis(ethylene glycol); -[3-(2-aziridinyl)propionate], trihydroxymethylpropane-tris[3-(2-aziridinyl)propionate], trihydroxymethylpropane-tris[3-(1-aziridinyl)propionate], trihydroxymethylpropane-tris[3-(2-methyl-1-aziridinyl)propionate], tetrahydroxymethylmethane-tris[3-(2-aziridinyl)propionate], pentaerythritol-tris[3-(1-aziridinyl)propionate], N,N'-diphenylmethane-4,4'-bis(1-aziridinylcarboxylic acid amide), N,N'-hexamethylene-1,6-bis(1-aziridinylcarboxylic acid amide), and the like aziridinyl compounds.

Among the crosslinking agents (C), at least one selected from the group consisting of polyisocyanate and polyepoxide is preferably used, and polyisocyanate is more preferably used, because of its good reactivity with the (meth)acrylic resin (A).

The crosslinking agent (C) may be used alone or in combination of two or more.

The amount of the crosslinking agent (C) is preferably 0.1 to 30 parts by mass, more preferably 0.1 to 20 parts by mass, particularly preferably 0.1 to 10 parts by mass, and particularly preferably 0.1 to 5 parts by mass relative to 100 parts by mass of the (meth)acrylic resin (A). If the amount of the crosslinking agent (C) is 0.1 parts by mass or more relative to 100 parts by mass of the (meth)acrylic resin (A), a three-dimensional crosslinked structure is fully formed in the adhesive composition during UV irradiation, thereby sufficiently reducing the adhesion of the adhesive composition after UV irradiation. If the amount of the crosslinking agent (C) is 30 parts by mass or less relative to 100 parts by mass of the (meth)acrylic resin (A), the adhesion of the adhesive composition before UV irradiation is good.

(Other components) In the method for producing the adhesive composition, other components other than the (meth)acrylic resin (A), the photopolymerization initiator (B) and the crosslinking agent (C) may be mixed as needed. Examples of other components include thickeners, solvents and various additives.

(Thickener) As the thickener, known ones can be used without particular limitation. Examples of the thickener include terpene thickener resins, phenol thickener resins, rosin thickener resins, aliphatic petroleum resins, aromatic petroleum resins, copolymerized petroleum resins, alicyclic petroleum resins, xylene resins, epoxy thickener resins, polyamide thickener resins, ketone thickener resins, and elastic system thickener resins. These thickeners can be used alone or in combination of two or more.

When the thickener is mixed, the added amount is preferably 30 parts by mass or less, more preferably 5 to 20 parts by mass, relative to 100 parts by mass of the (meth)acrylic resin (A).

(Solvent) Solvents are used to adjust the viscosity of adhesive compositions and can be used to dilute adhesive compositions. For example, when applying an adhesive composition, a solvent can be used to make the viscosity of the adhesive composition an appropriate viscosity.

Examples of the solvent include organic solvents such as methyl ethyl ketone, methyl isobutyl ketone, acetone, ethyl acetate, propyl acetate, tetrahydrofuran, dioxane, dicyclohexanone, hexane, toluene, xylene, n-propanol, and isopropanol. These solvents may be used alone or in combination of two or more.

(Additives) Examples of additives include plasticizers, surface lubricants, levelers, softeners, antioxidants, anti-aging agents, light stabilizers, ultraviolet absorbers, polymerization inhibitors, benzotriazole-based light stabilizers, phosphate-based and other flame retardants, surfactants, and antistatic agents.

[Adhesive sheet manufacturing method] The adhesive sheet can be manufactured, for example, by the method shown below.

First, an adhesive solution is prepared by dissolving or dispersing the adhesive composition in a solvent. Alternatively, the adhesive composition can be directly used as the adhesive solution.

Next, an adhesive solution is applied to the substrate, and when the adhesive solution contains a solvent, the adhesive solution is dried by heating to remove the solvent and form an adhesive layer. Then, a peeling sheet is attached to the adhesive layer as required. Furthermore, the obtained sheet is aged in an oven for a certain period of time as required to form a cross-linked structure and obtain an adhesive sheet.

The adhesive sheet can also be manufactured by the method shown below. When an adhesive solution containing a solvent is applied to a peeling sheet, the solvent is removed by heating and drying to form an adhesive layer. Thereafter, the peeling sheet with the adhesive layer is placed on a substrate with the adhesive layer side facing the substrate, and the adhesive layer is transferred to the substrate (transfer attachment). Furthermore, by aging the obtained sheet in an oven for a certain period of time as needed to form a cross-linked structure, an adhesive sheet can be obtained.

In the above method, a substrate having an adhesive layer is used as a substrate, and an adhesive composition is coated on the adhesive layer, or the adhesive layer and the adhesive layer are laminated face to face, so that a dicing-die bonding integrated thin film can be obtained.

As a method for applying the adhesive solution on the substrate (or the release sheet), a well-known method can be used. Specifically, there can be cited a method of applying using a conventional coater, such as a gravure roll coater, a reverse roll coater, a kiss roll coater, a dip roll coater, a rod coater, a knife coater, a spray coater, a notch wheel coater, a direct coater, and the like.

The conditions for heat drying the applied adhesive solution are not particularly limited, but are generally performed at 25 to 180°C, preferably 60 to 150°C, and generally performed for 1 to 20 minutes, preferably 1 to 10 minutes. By heat drying within the above range, the solvent contained in the adhesive solution can be removed. The conditions for aging the heat-dried sheet in an oven for a certain period of time are not particularly limited, but are generally performed at 25 to 100°C, preferably 30 to 80°C, and generally performed for 1 to 30 days, preferably 1 to 14 days. By aging under the above conditions, the (meth)acrylic resin (A) can be crosslinked by the crosslinking agent (C), and the gel fraction of the adhesive layer can be adjusted to a desired range.

[Application of adhesive sheets] Adhesive sheets can be used as removable adhesive sheets, for example, in the manufacture of electronic components. Specifically, removable adhesive sheets are used to fix the attached body in each step of the manufacture of electronic components, and after various processing steps, they are irradiated with UV (ultraviolet rays) to be peeled off from the attached body. Therefore, adhesive sheets can be used as back grinding tapes and cutting tapes when processing semiconductor wafers. Adhesive sheets can also be used as support tapes for fragile components such as ultra-thin glass substrates and components that are easily warped such as FPC substrates. In particular, the adhesive sheet is suitable for dicing tape used in manufacturing dicing-die bonding integrated films due to its excellent adhesion to the adhesive layer and excellent releasability after UV irradiation.

Using an adhesive sheet as a dicing tape for the wafer, before the dicing step, an adhesive sheet is attached to the wafer on which multiple parts are formed. Next, the wafer is cut and cut (diced) into individual parts to form component chips (wafers). After that, the adhesive sheet attached to each component chip is irradiated with UV. In this way, UV is irradiated to the adhesive layer through the substrate of the adhesive sheet, and the unsaturated bonds in the adhesive form a three-dimensional cross-linked structure and harden. As a result, the adhesive force of the adhesive layer is reduced. After that, the adhesive sheet is peeled off from each component chip.

Examples of the light source used for UV irradiation include a high-pressure mercury lamp, an ultra-high-pressure mercury lamp, a carbon arc lamp, a xenon lamp, a metal halide lamp, a chemical lamp, and a black light.

The UV irradiation amount irradiated to the adhesive sheet is preferably 50 to 3,000 mJ/cm ² , and more preferably 100 to 600 mJ/cm ^2. If the UV irradiation amount irradiated to the adhesive sheet is 50 mJ/cm ² or more, the adhesive layer can be cured at a sufficiently fast curing speed by UV irradiation, so the adhesion of the adhesive layer after UV irradiation can be sufficiently reduced. Even if the UV irradiation amount irradiated to the adhesive sheet exceeds 3,000 mJ/cm ² , the corresponding effect cannot be obtained. Therefore, by setting the UV irradiation amount irradiated to the adhesive sheet to 3,000 mJ/cm ² or less, the adhesive sheet can be economically peeled off while reducing the influence of UV irradiation on the attached object. [Example]

Hereinafter, the present invention will be described in more detail by way of embodiments and comparative examples, but the present invention is not limited to the following embodiments.

The following shows the raw materials used in the synthesis of (meth)acrylic resins (A) and (cA). (Meth)acrylate containing hydroxyl group (m-1): 2-Hydroxyethyl acrylate, Japan Catalyst Co., Ltd., 2-Hydroxyethyl methacrylate, Japan Catalyst Co., Ltd., 4-Hydroxybutyl acrylate, Osaka Organic Chemical Industry Co., Ltd. (Meth) alkyl ester (m-2): 2-Ethylhexyl acrylate, Osaka Organic Chemical Industry Co., Ltd., n-Butyl acrylate, Osaka Organic Chemical Industry Co., Ltd., Dodecyl acrylate, Osaka Organic Chemical Industry Co., Ltd., 2-Methoxyethyl acrylate, Osaka Organic Chemical Industry Co., Ltd., Ethyl acrylate, Japan Catalyst Co., Ltd., Methyl methacrylate, Japan Catalyst Co., Ltd. Monomer containing carboxyl group (m-3): Acrylic acid, Japan Catalyst Co., Ltd., Methacrylic acid, Japan Catalyst Co., Ltd. Free radical polymerization initiator: 2,2'-azobis(isobutyronitrile), Fuji Film Wako Pure Chemical Co., Ltd. RAFT agent: 2-"(Dodecylthiocarbonyl)ethoxy"propionic acid, Fuji Film Wako Pure Chemical Co., Ltd. Bis{4-[ethyl-(2-hydroxyethyl)aminoformyl]benzyl}trithiocarbonate, Fuji Film Wako Pure Chemical Co., Ltd. S,S-dibenzyl trithiocarbonate, Fuji Film Wako Pure Chemical Co., Ltd. 2-Phenyl-2-propyldithiobenzoic acid, Ouchi Shinko Chemical Co., Ltd. Additive: 2-Methyl-2-n-butyltelluryl-propionic acid ethyl ester, Otsuka Chemical Co., Ltd. Ethylenically unsaturated compound containing isocyanate group (a): Karenz (trademark) MOI, 2-isocyanatoethyl methacrylate, Showa Denko Co., Ltd. AOI-VM (trademark), 2-isocyanatoethyl acrylate, Showa Denko Co., Ltd.

The following is a synthesis example of (meth)acrylic resins (A) and (cA). The weight average molecular weight, molecular weight distribution, acid value and glass transition temperature of (meth)acrylic resins (A) and (cA) were measured and calculated by the above-mentioned method. The ethylenic unsaturated group equivalent of (meth)acrylic resins (A) and (cA) was calculated from the feed amount as mentioned above. The hydroxyl value is the mass (mg) of potassium hydroxide required to neutralize acetic acid bonded to hydroxyl groups when 1 g of the resin is acetylated in accordance with JIS K 0070:1992. Table 1 shows the weight average molecular weight, molecular weight distribution, ethylenic unsaturated group equivalent, hydroxyl value, acid value and glass transition temperature of (meth)acrylic resins (A) and (cA).

[Synthesis Example 1 (Example 1-1)] In a reaction apparatus equipped with a stirrer, a temperature regulator, a reflux cooler, a dropping funnel and a thermometer, 132 parts by mass (71.6 mol) of 2-ethylhexyl acrylate, 33 parts by mass (28.4 mol) of 2-hydroxyethyl acrylate, 0.23 parts by mass of 2-[(dodecylthiocarbonyl)carbonyl]propionic acid, 0.05 parts by mass of 2,2'-azobis(isobutyronitrile) and 471 parts by mass of ethyl acetate as a solvent were added. After heating and reflux were started, the reaction was carried out for 10 hours. Next, the temperature of the reactants was lowered to 60°C, and a mixture of 24.7 parts by mass (15.9 mol) of 2-isocyanatoethyl methacrylate and 0.19 parts by mass of dibutyltin dilaurate as a urethane catalyst was dripped through a dropping funnel. After the dripping was completed, the reaction system was kept at 70°C for 4 hours to eliminate the isocyanate group. Thus, a solution containing 35% by mass of a solid component of a (meth) acrylic resin (A1) with a weight average molecular weight of 300,000, a glass transition temperature of -50°C, and an ethylene unsaturated group equivalent of 1,189 g/mol was obtained.

[Synthesis Examples 2 to 4 (Examples 1-2 to 1-4)] Except for using the composition shown in Table 1, (meth)acrylic resins (A2) to (A4) were obtained in the same manner as in Synthesis Example 1.

[Comparative Synthesis Example 1 (Comparative Example 1-1)] In a reaction apparatus equipped with a stirrer, a temperature regulator, a reflux cooler, a dropping funnel and a thermometer, 132 parts by mass (71.6 mol) of 2-ethylhexyl acrylate, 33 parts by mass (28.4 mol) of 2-hydroxyethyl acrylate, 0.08 parts by mass of 2,2'-azobis(isobutyronitrile) and 471 parts by mass of ethyl acetate as a solvent were added. After heating and reflux were started, the reaction was carried out for 10 hours. Next, the temperature of the reactants was lowered to 60°C, and a mixed solution of 16.5 parts by mass (10.6 mol) of 2-isocyanatoethyl methacrylate and 0.18 parts by mass of dibutyltin dilaurate as a urethane catalyst was dripped through a dropping funnel. After the dripping was completed, the reaction system was kept at 70°C for 4 hours to eliminate the isocyanate groups. Thus, a solution containing 35% by mass of a solid content of a (meth) acrylic resin (cA1) with a weight average molecular weight of 600,000, a glass transition temperature of -45°C, and an ethylene unsaturated group equivalent of 1,707 g/mol was obtained.

[Comparative Synthesis Example 2 (Comparative Example 1-2)] Except that 2-methyl-2-n-butyltelluryl-propionic acid ethyl ester was used instead of 2-[(dodecylphenylthiocarbonyl)phenyl]propionic acid, and the composition shown in Table 1 was used, the (meth)acrylic resin (cA2) was obtained in the same manner as in Synthesis Example 1.

[Comparative Synthesis Example 3 (Comparative Example 1-3)] Except for using the composition shown in Table 1, a (meth)acrylic resin (cA3) was obtained in the same manner as in Synthesis Example 1.

The following shows the raw materials used in the preparation of the adhesive composition. Photopolymerization initiator (B): TPO: 2,4,6-trimethylbenzyldiphenylphosphine oxide (BASF, trade name: L-TPO) Crosslinking agent (C) L-45E: toluene diisocyanate adduct of trihydroxymethylpropane (Tosoh Co., Ltd., trade name: Coronate L-45E), TETRAD-X: N,N’-[1,3-phenylenebis(methylene)]bis[bis(oxiran-2-ylmethyl)amine] (Mitsubishi Gas Chemical Co., Ltd., trade name: TETRAD-X)

[Preparation of adhesive composition] Ethyl acetate was added as a diluent to a solution containing (meth)acrylic resins (A1) to (A4) and (cA1) to (cA3) obtained in Synthesis Examples 1 to 4 and Comparative Synthesis Examples 1 to 3, and the contents of (meth)acrylic resins (A1) to (A4) and (cA1) to (cA3) were adjusted to 30% by mass. Using this solution, an adhesive composition was obtained by the method shown below.

In a room where active lines are blocked, in a plastic container, the (meth)acrylic resin (A) or (cA) shown in Table 2, a photopolymerization initiator (B) and a crosslinking agent (C) are added and stirred in the amounts (parts by mass) shown in Table 2 to obtain adhesive compositions (B1) to (B4) and (cB1) to (cB3). The values of (meth)acrylic resins (A1) to (A4) and (meth)acrylic resins (cA1) to (cA3) in Table 2 are the solid components of the solutions used, i.e., the amounts (parts by mass) of (meth)acrylic resins (A1) to (A4) and (cA1) to (cA3). The value of the photopolymerization initiator (B) is the amount of the photopolymerization initiator (B) used relative to 100 parts by mass of the (meth)acrylic resin (A) or (cA). The value of the crosslinking agent (C) is the amount of the crosslinking agent (C) used relative to 100 parts by mass of the (meth)acrylic resin (A) or (cA).

[Example 2-1] Preparation of adhesive sheet As a separator, a polysilicone-based light-peel PET film (Toyobo Co., Ltd., product name: E7006, thickness 25μm) was prepared. The adhesive composition (B1) was applied to the surface with release treatment using a coater in such a way that the thickness after curing became 20μm, and heated and dried at 100°C for 2 minutes to form an adhesive layer. Next, as a sheet-like substrate, a PO film with a thickness of 90μm was prepared. The PO film was attached to the adhesive layer using a rubber roller in such a way that the corona-treated surface of the PO film was in contact with the exposed surface of the adhesive layer. Cured in an oven at 40°C for 3 days to crosslink and harden the adhesive layer to obtain the adhesive sheet of Example 2-1.

[Examples 2-2 to 2-4 and Comparative Examples 2-1 to 2-3] Preparation of adhesive sheets Except that the adhesive composition listed in Table 2 was used instead of the adhesive composition (B1), the adhesive sheets of Examples 2-2 to 2-4 and Comparative Examples 2-1 to 2-3 were obtained in the same manner as in Example 2-1.

[Preparation of a dicing-die bonding integrated film] The die bonding film (FH-D25T-50, Showa Denko Materials Co., Ltd.) whose adhesive layer is protected by a covering film on both sides is peeled off from one side of the covering film to expose the adhesive layer. The adhesive layer is peeled off and the PET film is lightly peeled off to expose the adhesive layer, and the adhesive layer of the adhesive sheets of Examples 2-1 to 2-4 and Comparative Examples 2-1 to 2-3 is laminated with a rubber roller. The film is placed at room temperature for 1 day to obtain a dicing-die bonding integrated film.

[Evaluation] (1) Determination of adhesion before UV irradiation (30° peel strength) As follows, the adhesion of the adhesive sheet of the embodiment and the comparative example to the die-bonding film was evaluated by measuring the 30° peel strength. A sample with a width of 25 mm and a length of 100 mm was cut out from the dicing-die-bonding integrated film. The cover film on the side of the dicing-die-bonding integrated film to which the adhesive sheet was not attached was peeled off, and the adhesive layer was attached to a polycarbonate plate using a double-sided tape to obtain a sample for adhesion measurement. The peel strength of the adhesive sheet to the die-bonding film was measured using a tensile tester (VPA-H200, Kyowa Interface Sciences Co., Ltd.). The test conditions were set to a peeling angle of 30° and a tensile speed of 600 mm/min. The samples were stored and the peeling strength was measured at a temperature of 23°C and a relative humidity of 40%. The results are shown in Table 2.

(2) Determination of adhesion after UV irradiation (30° peel strength) For the dicing-die bonding integrated film, ultraviolet rays (UV) were irradiated from the substrate side of the adhesive sheet at an irradiation dose of 300mJ/ ^cm2 to obtain a sample for the measurement of adhesion after UV irradiation. During UV irradiation, a conveyor-type UV irradiation device (EYEGRAPHICS Co., Ltd., 2KW lamp, 80W/cm) was used. Thereafter, the peel strength of the adhesive sheet to the die bonding film was measured in the same manner as the measurement of adhesion before UV irradiation (30° peel strength). The results are shown in Table 2.

(3) Processability evaluation (i) Preparation of samples for processability evaluation A protective tape (BG tape) is attached to the surface of a silicon wafer (diameter: 12 inches, thickness: 775 μm). Then, invisible dicing of the silicon wafer is performed. That is, the surface (back side) of the silicon wafer opposite to the side attached with the BG tape is irradiated with laser light under the following conditions to form a modified layer inside the silicon wafer. <Invisible cutting conditions> ・Invisible cutting device: DFL7361 (DISCO Co., Ltd.) ・Laser oscillator type: Q-switched semiconductor excitation solid-state laser ・Wavelength: 1342nm ・Frequency: 90kHz ・Output: 1.7W ・Number of passes: 2 ・Wafer size: 10mm×10mm ・Cutting speed: 700mm/sec

Grind the invisible cut silicon wafer until the thickness reaches 30μm. Use a grinding and polishing device (DGP8761, DISCO Co., Ltd.) for grinding. Under the following conditions, attach a dicing-die bonding integrated film adhesive layer to the ground silicon wafer so that the substrate side of the dicing tape faces the dicing ring. Then, peel off the BG tape from the surface of the silicon wafer. <Attachment conditions> ・Attachment device: DFM2800 (DISCO Co., Ltd.) ・Attachment temperature: 70℃ ・Attachment speed: 10mm/s ・Attachment tension level: Level 6

Next, a die separation machine (DDS2300, DISCO Co., Ltd.) is used to cool and expand under the following conditions. Thereafter, the substrate layer (PO film) of the dicing-die bonding integrated film is thermally shrunk under the following conditions. After these steps, the silicon wafer and the adhesive layer are singulated into a plurality of wafers (size 10mm×10mm) with adhesive chips attached. <Cooling expansion conditions> ・Cooling temperature: -15℃ ・Cooling time: 120 seconds ・Push-up amount: 12mm ・Push-up speed: 200mm/sec ・Holding time after push-up: 3 seconds <Heat shrinkage conditions> ・Heater temperature: 220℃ ・Heater rotation speed: 5°/sec ・Push-up amount: 8mm ・Tape cooling waiting time: 10 seconds

After the silicon wafer and adhesive layer are singulated, the adhesive layer is irradiated with ultraviolet light under the following conditions from the substrate side of the adhesive sheet. This hardens the adhesive layer and reduces the adhesion to the adhesive layer. <Ultraviolet irradiation conditions> ・Ultraviolet irradiation intensity: 100mW/ ^cm2・Ultraviolet irradiation dose: 150mJ/ ^cm2

(ii) Evaluation of processability (DAF scattering) After cooling expansion and heat shrinkage, DAF scattering was evaluated using the following criteria. The results are shown in Table 2. A: DAF scattering did not occur at all. B: DAF scattering did not occur, but peeling or floating was observed at the interface between the adhesive layer and the adhesive layer. C: DAF scattering occurred at least in one place.

(Wafer edge peeling) After cooling expansion and heat shrinkage, the peeling of the adhesive layer and the adhesive layer at the edge of the wafer with the adhesive sheet attached was evaluated using the following criteria. The results are shown in Table 2. A: No peeling was observed at the edge. B: Peeling was observed over a length of 1 mm or more and less than 2 mm from the edge. C: Peeling was observed over a length of 2 mm or more and less than 3 mm from the edge. D: Peeling was observed over a length of 3 mm or more from the edge.

(Separability of adhesive layer) The entire surface of the silicon wafer after cooling expansion and thermal contraction was observed under a microscope, and the separability of the adhesive layer was evaluated using the following criteria. The results are shown in Table 2. A: The adhesive layer was completely separated. D: There was an unseparated portion in at least one place of the adhesive layer.

(Incision width) Using a microscope, measure the interval (incision width) of the wafers attached after singulation. Measure the incision width in the MD/TD direction at two locations on the periphery (up, down, left, and right) of the silicon wafer and one location in the center (a total of 18 points) and find the average value. Evaluate using the following criteria. The results are shown in Table 2. S: The average incision width is 100μm or more and less than 150μm. A: The average incision width is 70μm or more and less than 100μm. B: The average incision width is 50μm or more and less than 70μm.

(Pick-up performance) After the above evaluation, 100 wafers with adhesive were picked up under the following conditions and evaluated using the following criteria. The results are shown in Table 2. <Pick-up conditions> ・Die bonding device: DB-830P (FASFORD TECHNOLOGY Co., Ltd.) ・Ejector needle: EJECTOR NEEDLE SEN2-83-05 (diameter: 0.7mm, tip shape: hemisphere with a radius of 350μm, MICROMECHANICS) ・Ejector height: 250μm ・Ejector speed: 1mm/sec ・Number of ejector pins: 9 <Evaluation criteria> A: The success rate of pick-up is 100%. B: The success rate of pick-up is 80% or more but less than 100%. C: The success rate of pick-up is 60% or more but less than 80%.

The results of the processability evaluation of the dicing-die bonding integrated film made using the adhesive sheets of Examples 2-1 to 2-3 are all good. In particular, the kerf width evaluation of Examples 2-1, 2-2 and 2-4 is "S". From the perspective of achieving excellent pickup performance, the kerf width is considered one of the important items in the invisible dicing process. On the other hand, the kerf width evaluation of the comparison examples is "B". In addition, the comparison examples all experienced chip edge peeling after cooling expansion and thermal contraction, and poor pickup also occurred. Comparative Example 2-2, which uses a (meth) acrylic resin obtained by copolymerization of organic tellurium free radical polymerization, has a D adhesive layer splitting property due to the small amount of low molecular weight components and insufficient propagation of fracture stress. [Possibility of industrial application]

According to the present disclosure, a (meth) acrylic resin suitable for an adhesive composition can be provided. The adhesive layer formed by using the adhesive composition made of the (meth) acrylic resin can be preferably used as a re-peelable adhesive sheet, especially as an adhesive layer of a dicing-die bonding integrated film.

Claims (5)

A method for producing a dicing-die bonding integrated film comprises: a step of producing a (meth) acrylic resin, comprising: a step of subjecting a raw material monomer group (M) containing a hydroxyl group-containing (meth) acrylic ester (m-1) and an alkyl (meth) acrylic ester (m-2) to reversible addition-fragmentation chain transfer (RAFT) polymerization to obtain a copolymer (A-0); and a step of adding an ethylenically unsaturated compound (a) containing an isocyanate group to a portion of the side chain hydroxyl groups of the copolymer (A-0) to obtain a (meth) acrylic resin (A) having an ethylenically unsaturated group (ii) ); the step of manufacturing the adhesive composition: comprising the step of mixing the (meth) acrylic resin (A) having an ethylenically unsaturated group obtained by the aforementioned step of manufacturing the (meth) acrylic resin, a photopolymerization initiator (B) and a crosslinking agent (C) (iii); the step of manufacturing the adhesive sheet: comprising coating the adhesive composition obtained by the aforementioned step of manufacturing the adhesive composition on a sheet-like substrate to prepare an adhesive layer and forming a crosslinking structure in the aforementioned adhesive layer; and coating an adhesive layer on the adhesive layer having a crosslinking structure obtained by the aforementioned step of manufacturing the adhesive sheet. A method for manufacturing a dicing-die bonding integrated film comprises: a step of manufacturing a (meth) acrylic resin, comprising: a step of subjecting a raw material monomer group (M) containing a hydroxyl group-containing (meth) acrylic ester (m-1) and an alkyl (meth) acrylic ester (m-2) to reversible addition-fragmentation chain transfer (RAFT) polymerization to obtain a copolymer (A-0); and a step (i) of adding an ethylenically unsaturated isocyanate group-containing hydroxyl group to a portion of the side chain hydroxyl groups of the copolymer (A-0). Compound (a), step (ii) of obtaining a (meth) acrylic resin (A) having an ethylenically unsaturated group; step (iii) of preparing an adhesive composition, comprising mixing the (meth) acrylic resin (A) having an ethylenically unsaturated group obtained by the aforementioned step of preparing a (meth) acrylic resin, a photopolymerization initiator (B) and a crosslinking agent (C); and applying the adhesive composition obtained by the aforementioned step of preparing an adhesive composition to an adhesive layer. The method for manufacturing a dicing-die bonding integrated film as claimed in claim 1 or 2, wherein the aforementioned raw material monomer group (M) further contains a carboxyl-containing monomer (m-3). The method for manufacturing a dicing-die bonding integrated film as claimed in claim 1 or 2, wherein the molecular weight distribution (Mw/Mn) of the aforementioned (meth) acrylic resin (A) having ethylenically unsaturated groups is 2.4-10.0. The method for manufacturing a dicing-die bonding integrated thin film as claimed in claim 1 or 2, wherein the crosslinking agent (C) is at least one selected from the group consisting of polyisocyanate and polyepoxide.