Adhesive sheet for workpiece processing, method for manufacturing same, and method for manufacturing electronic device

Abstract

The present invention relates to an adhesive sheet for workpiece processing, a method for manufacturing the same, and a method for manufacturing an electronic device using the adhesive sheet for workpiece processing, the adhesive sheet for workpiece processing having a buffer layer, a substrate, and an adhesive layer, and having the adhesive layer on one surface, the buffer layer is a layer containing a cured product of a thermosetting resin composition, and the thermosetting resin composition contains an antistatic agent.

Description

TECHNICAL FIELD

[0001] The present application relates to an adhesive sheet for workpiece processing and a manufacturing method thereof, and a manufacturing method of an electronic device. BACKGROUND

[0002] In the process of rapid development of thinness, miniaturization, and multifunctionality of information terminal devices, electronic device such as semiconductor devices mounted on these devices are also required to be thin and high-density.

[0003] As a method of thinning electronic device, a method of grinding the back surface of a workpiece such as a semiconductor wafer used in the electronic device has been performed. The back surface grinding of the workpiece is performed in a state where an adhesive sheet for workpiece processing (hereinafter, also referred to as "back grinding sheet") for grinding the back surface is attached to the surface of the workpiece and protects the surface of the workpiece. The back grinding sheet can be peeled off and removed from the surface of the workpiece after the back surface grinding.

[0004] In recent years, as a method of thinning while suppressing damage to the workpiece, a pre-dicing method, a stealth dicing method, and the like have been put into practical use. The pre-dicing method is a method of forming a groove of a given depth on the surface of the workpiece using a dicing blade or the like, and then grinding the workpiece from the back surface side to reach the groove, thereby singulating the workpiece into a workpiece singulation. In addition, the stealth dicing method is a method of forming a modified region inside the workpiece by irradiation of laser light, and then grinding the workpiece from the back surface side, and cutting it at the modified region as a division starting point, thereby singulating the workpiece into a semiconductor chip. In these methods, a back grinding sheet for protecting the surface of the workpiece is also used.

[0005] For the adhesive sheet for workpiece processing, it is required to stably hold the workpiece and suppress good grinding properties such as cracking of the workpiece when processing the workpiece.

[0006] As the adhesive sheet for workpiece processing, for example, an adhesive tape for semiconductor processing is proposed, which has a base material, a buffer layer provided on at least one side of the base material, and an adhesive layer provided on the other side of the base material, the Young's modulus of the buffer layer at 23°C is 10 to 400 MPa, and the breaking energy is 1 to 9 MJ / m 3 The Young's modulus of the base material at 23°C is greater than the Young's modulus of the buffer layer (see Patent Literature 1).

[0007] Prior Art Documents

[0008] Patent Literature

[0009] Patent Literature 1: International Publication No. 2020 / 003920 SUMMARY

[0010] Problem to be solved by the invention

[0011] In the adhesive tape for semiconductor processing of Patent Document 1, the buffer layer is provided to absorb vibration generated at the time of grinding of the workpiece, and to moderate unevenness caused by foreign matter, and to stably maintain the workpiece flat.

[0012] However, in the adhesive sheet for workpiece processing, at the time of manufacture, storage, or use, sometimes an unpleasant odor caused by the constituent components of the adhesive sheet is generated. With the increase in awareness of the working environment in recent years, low odor property is also required for the adhesive sheet for workpiece processing, but it is difficult to obtain excellent low odor property while maintaining good grinding property of the workpiece.

[0013] In addition, at the time of peeling the adhesive sheet for workpiece processing from the workpiece after processing, sometimes peeling static electricity is generated. If the peeling static electricity voltage is too large, it can cause failure of a circuit or the like formed on the workpiece, and thus it is desirable to suppress the peeling static electricity voltage.

[0014] The present invention was completed in view of the above-described actual circumstances, and aims to provide an adhesive sheet for workpiece processing in which the peeling static electricity voltage is suppressed, and which has excellent low odor property and grinding property, a method for manufacturing the same, and a method for manufacturing an electronic device using the same.

[0015] Method for solving the problem

[0016] The present inventors and others have conducted intensive studies, and as a result, have found that by providing a buffer layer containing a cured product of a thermosetting resin composition containing a specific component in an adhesive sheet for workpiece processing, the above-described problems can be solved, and thus have completed the following invention.

[0017] That is, the present invention relates to the following [1] to

[13] .

[0018] [1] An adhesive sheet for workpiece processing, having a buffer layer, a base material, and an adhesive layer,

[0019] The above-described adhesive sheet for workpiece processing has the above-described adhesive layer on one surface,

[0020] The above-described buffer layer is a layer containing a cured product of a thermosetting resin composition,

[0021] The above-described thermosetting resin composition contains an antistatic agent.

[0022] [2] The adhesive sheet for workpiece processing according to the above-described [1], wherein,

[0023] The above-described antistatic agent is an ionic material.

[0024] [3] The adhesive sheet for workpiece processing according to the above-described [1] or [2], wherein,

[0025] The surface resistivity of the above-mentioned buffer layer is 1.0 x 10 12 Ω / sq. or less.

[0026] [4] The adhesive sheet for workpiece processing according to any one of the above-mentioned [1] to [3], wherein

[0027] The thickness of the above-mentioned buffer layer is 2 to 100 μm.

[0028] [5] The adhesive sheet for workpiece processing according to any one of the above-mentioned [1] to [4], wherein

[0029] The above-mentioned thermosetting resin composition contains a polyester-based resin.

[0030] [6] The adhesive sheet for workpiece processing according to the above-mentioned [5], wherein

[0031] The above-mentioned polyester-based resin is a polyester urethane resin.

[0032] [7] The adhesive sheet for workpiece processing according to the above-mentioned [5], wherein

[0033] The above-mentioned polyester-based resin is a polyester-based resin having two or more hydroxyl groups, and the above-mentioned thermosetting resin composition further contains a polyisocyanate compound.

[0034] [8] The adhesive sheet for workpiece processing according to any one of the above-mentioned [1] to [7], wherein

[0035] The above-mentioned buffer layer is provided on one side of the above-mentioned substrate, and the above-mentioned adhesive layer is provided on the other side of the above-mentioned substrate.

[0036] [9] The adhesive sheet for workpiece processing according to any one of the above-mentioned [1] to [8], which is used for grinding a workpiece.

[0037]

[10] The adhesive sheet for workpiece processing according to any one of the above-mentioned [1] to [9], which is used for singulating a workpiece into a plurality of workpiece singulation products in such a manner that

[0038] The above-mentioned workpiece has a groove on a surface or a modified region inside,

[0039] A back surface of the above-mentioned workpiece is ground in a state where the above-mentioned adhesive sheet for workpiece processing, which is attached to the surface of the above-mentioned workpiece, is fixed, whereby the above-mentioned workpiece is singulated into a plurality of workpiece singulation products with the above-mentioned groove or the above-mentioned modified region as a starting point.

[0040]

[11] A method for manufacturing an adhesive sheet for workpiece processing, which is a method for manufacturing the adhesive sheet for workpiece processing according to any one of the above-mentioned [1] to

[10] , the method having:

[0041] a process of curing the thermosetting resin composition by heating.

[0042]

[12] A method for manufacturing an electronic device, the method comprising:

[0043] a process of adhering the workpiece processing adhesive sheet of any one of the above-mentioned [1] to

[10] to the surface of the workpiece with the adhesive layer as the adhering surface; and

[0044] a process of grinding the back surface of the workpiece in a state where the workpiece processing adhesive sheet adhered to the workpiece is fixed.

[0045]

[13] A method for manufacturing an electronic device, the method comprising:

[0046] a predetermined division line forming process, which is a process a of forming a groove on the surface of the workpiece, or a process b of forming a modified region inside the workpiece from the surface or the back surface of the workpiece;

[0047] a sheet adhering process of adhering the workpiece processing adhesive sheet of any one of the above-mentioned [1] to

[10] to the surface of the workpiece with the adhesive layer as the adhering surface, after the process a, or before or after the process b; and

[0048] a grinding and singulation process of grinding the back surface of the workpiece in a state where the workpiece processing adhesive sheet adhered to the workpiece is fixed, and singulating the workpiece into a plurality of workpiece singulation products with the groove or the modified region as the starting point.

[0049] Effects of the Invention

[0050] According to the present application, it is possible to provide a workpiece processing adhesive sheet in which the peeling static voltage is suppressed, which is low in odor, and which is excellent in grindability, and a method for manufacturing an electronic device using the same. DETAILED DESCRIPTION

[0051] In the present specification, with respect to the preferable numerical range, the lower limit value and the upper limit value described hierarchically can be combined independently of each other. For example, according to the description "preferably 10 to 90, more preferably 30 to 60", it is also possible to combine the "preferably lower limit value (10)" and the "more preferably upper limit value (60)" to obtain "10 to 60".

[0052] In the present specification, the "effective ingredient" means an ingredient other than a dilution solvent among the ingredients contained in the composition that is the object.

[0053] In the present specification, the number average molecular weight (Mn) and the weight average molecular weight (Mw) are values converted to a standard polystyrene, and specifically, are values determined based on the method described in the examples.

[0054] In the present specification, for example, "(meth)acrylic acid" indicates both "acrylic acid" and "methacrylic acid", and the like.

[0055] In the present specification, "energy ray" indicates a ray having an energy quantum in an electromagnetic wave or a charged particle beam, and as examples thereof, ultraviolet rays, radioactive rays, electron beams, and the like can be given. For example, an electrodeless lamp, a high-pressure mercury lamp, a metal halide lamp, a UV-LED, and the like can be used as an ultraviolet light source to irradiate ultraviolet rays. In the case of an electron beam, an electron beam generated by an electron beam accelerator or the like can be irradiated.

[0056] In the present specification, "energy ray polymerizability" indicates a property of undergoing polymerization by irradiation of an energy ray. In addition, "energy ray curability" indicates a property of undergoing curing by irradiation of an energy ray, and "non-energy ray curability" indicates a property of not having energy ray curability.

[0057] In the present specification, "workpiece" indicates a plate-shaped body obtained by adhering the workpiece processing adhesive sheet of the present embodiment and then performing processing.

[0058] As the workpiece, for example, a wafer, a panel level package, a strip (long strip-shaped substrate) on which a molded resin seal is implemented, and the like can be given, and among them, from the viewpoint of easily obtaining the effect of the present application, a wafer is preferred.

[0059] As the wafer, for example, a semiconductor wafer such as a silicon wafer, a gallium arsenide wafer, a silicon carbide wafer, a gallium nitride wafer, an indium phosphorus wafer, and the like, and an insulator wafer such as a glass wafer, a lithium tantalate wafer, a lithium niobate wafer, and the like can be given. In addition, a reconstituted wafer formed of a resin and a semiconductor for the production of fan-out packaging and the like can also be given. Among them, from the viewpoint of easily obtaining the effect of the present application, as the wafer, a semiconductor wafer, an insulator wafer, and more preferably a semiconductor wafer, and further preferably a silicon wafer are preferred.

[0060] On the surface of the semiconductor wafer, a circuit such as a wiring, a capacitor, a diode, a transistor, and the like is generally formed. These circuits can be formed by, for example, an etching method, a Lift-Off method, and the like, which are conventionally known.

[0061] The thickness of the workpiece before processing is not particularly limited, and is generally 500 to 1000 μm.

[0062] In the present specification, a "workpiece singulated product" refers to an object after a workpiece is singulated. For example, in the case where the workpiece is a semiconductor wafer, the workpiece singulated product is a semiconductor chip, and in the case where the workpiece is a tape (long strip-shaped substrate) on which panel-level packaging or molding resin sealing is performed, the workpiece singulated product is a semiconductor package.

[0063] In the present specification, an "electronic device" can include, for example, a workpiece, a workpiece singulated product, an electronic component including the workpiece singulated product, an electronic device provided with the electronic component, and the like.

[0064] In the present specification, a "surface" of a workpiece refers to a surface on which a circuit is formed, and a "back surface" refers to a surface on which no circuit is formed.

[0065] The mechanism described in the present specification is a presumption, and does not limit the mechanism of the effect of the adhesive sheet for workpiece processing of the present application.

[0066] [Adhesive sheet for workpiece processing]

[0067] The adhesive sheet for workpiece processing of the present embodiment (hereinafter also referred to as "adhesive sheet") has a cushion layer, a substrate, and an adhesive layer,

[0068] The adhesive sheet for workpiece processing described above has the adhesive layer described above on one surface,

[0069] The cushion layer described above is a layer containing a cured product of a thermosetting resin composition,

[0070] The thermosetting resin composition described above contains an antistatic agent.

[0071] The adhesive sheet of the present embodiment is attached to a surface of a workpiece, and is used for performing a given processing on the workpiece while protecting the surface. After the given processing is performed on the workpiece, the adhesive sheet of the present embodiment is peeled off and removed from the workpiece.

[0072] The laminated structure of the adhesive sheet of the present embodiment is not particularly limited as long as it has an adhesive layer on one surface, and the adhesive layer can be attached to a workpiece, and for example, can have a cushion layer on one side of a substrate, can have an adhesive layer on the other side of the substrate, or can have a substrate, a cushion layer, and an adhesive layer in this order. Among them, from the viewpoint of easily obtaining a better grinding property, it is preferable that the cushion layer be on one side of the substrate and the adhesive layer be on the other side of the substrate.

[0073] The adhesive sheet of the present embodiment can have a layer other than the cushion layer, the substrate, and the adhesive layer, or can not have a layer other than the cushion layer, the substrate, and the adhesive layer.

[0074] As the layer other than the cushion layer, the base material, and the adhesive layer, for example, an intermediate layer provided between the base material and the adhesive layer, a release sheet provided on the surface of the adhesive sheet, and the like can be cited.

[0075] Next, each member constituting the adhesive sheet of the present embodiment will be described in order.

[0076] <Buffer Layer>

[0077] The adhesive sheet of the present embodiment has a cushion layer, whereby it is possible to absorb vibrations, impacts, and the like generated when a workpiece is subjected to grinding or the like, and prevent cracks from occurring in the workpiece. Further, by providing the cushion layer, it is also possible to absorb irregularities such as foreign matter present on the table of the support device, and improve the holding property of the support device with respect to the adhesive sheet.

[0078] The cushion layer possessed by the adhesive sheet of the present embodiment is a layer containing a cured product of a thermosetting resin composition, and the thermosetting resin composition contains an antistatic agent. By forming the cushion layer from a thermosetting resin composition containing an antistatic agent, the adhesive sheet of the present embodiment suppresses the peeling static voltage. In addition, since the cushion layer contains an antistatic agent, the adhesive sheet of the present embodiment is able to suppress the decrease in adhesive force caused by the antistatic agent and the contamination of the workpiece caused by the antistatic agent, which can occur when the adhesive layer contains an antistatic agent.

[0079] In addition, it can be considered that the raw material constituting the thermosetting resin composition forms a crosslinked structure by heating, at which time the raw material that becomes the cause of the bad odor is not easily left, and thus the bad odor of the cushion layer is suppressed, and excellent low odor property can be obtained. Furthermore, it can be considered that, by the good form retention property brought about by the crosslinked structure of the cured product of the thermosetting resin composition, the workpiece can be well retained during grinding of the workpiece, and excellent grinding property can be obtained.

[0080] The cushion layer possessed by the adhesive sheet of the present embodiment can be any layer containing a cured product of a thermosetting resin composition, and from the viewpoints of low odor property and grinding property, it is preferable that the cured product of the thermosetting resin composition be formed into a layer.

[0081] Next, the above-described thermosetting resin composition will be described in detail.

[0082] (Thermosetting Resin Composition)

[0083] The thermosetting resin composition can be any resin composition having thermosetting property, and is not particularly limited.

[0084] The thermosetting resin contained in the thermosetting resin composition can be a resin that exhibits thermosetting property alone, or a resin that exhibits thermosetting property by being used in combination with one or more selected from a crosslinking agent and a catalyst.

[0085] [Thermosetting resin]

[0086] As the thermosetting resin, for example, an epoxy resin, a phenol resin, a silicone resin, a melamine resin, an acrylic resin, a polyester resin, and the like can be exemplified. Among them, from the viewpoints of low odor property and grinding property, a polyester resin is preferable.

[0087] The thermosetting resin can be used singly or in combination of two or more kinds.

[0088] As the polyester resin, for example, a polymer obtained by condensation polymerization of an alcohol component such as ethylene glycol, propylene glycol, 1,3-butanediol, 1,4-butanediol, diethylene glycol, triethylene glycol, 1,5-pentanediol, 1,6-hexanediol, neopentyl glycol, cyclohexane-1,4-dimethanol, hydrogenated bisphenol A, an ethylene oxide or propylene oxide adduct of bisphenol A, and the like, and a carboxylic acid component such as terephthalic acid, isophthalic acid, naphthalene dicarboxylic acid, cyclohexane-1,4-dicarboxylic acid, adipic acid, azelaic acid, maleic acid, fumaric acid, itaconic acid, an acid anhydride thereof, and the like can be exemplified.

[0089] The alcohol component and the carboxylic acid component can each be used singly or in combination of two or more kinds.

[0090] The polyester resin can be a resin in which a polyester is modified. From the viewpoints of low odor property and grinding property, a polyester urethane resin obtained by urethane-modifying a polyester is preferable. Note that, in the present specification, the polyester urethane resin is included in the concept of the polyester resin, and the preferable mode of the polyester resin can be replaced by the preferable mode of the polyester urethane resin.

[0091] As the polyester urethane resin, a resin obtained by reacting a polyester polyol having a hydroxyl group at a terminal, which is obtained by condensation polymerization of the above alcohol component and the above carboxylic acid component, and a polyisocyanate compound can be exemplified.

[0092] The polyisocyanate compound, which is a raw material component of the polyester urethane resin, can be any one of an aromatic polyisocyanate compound, an aliphatic polyisocyanate compound, and a cycloaliphatic polyisocyanate compound. As specific examples of the polyisocyanate compound, a diisocyanate compound such as diphenylmethane diisocyanate, toluene diisocyanate, 1,3-xylylene diisocyanate, isophorone diisocyanate, 1,6-hexane diisocyanate, and the like can be exemplified.

[0093] The polyester polyol and the polyisocyanate compound, which are raw material components of the polyester urethane resin, can each be used singly or in combination of two or more kinds.

[0094] The polyester-based resin has a reactive functional group for thermal curing, and from the viewpoint of making the thermosetting good, it is preferable to have two or more hydroxyl groups, and more preferably to have two or more hydroxyl groups at the molecular terminal. Note that, for the "molecular terminal" of the polyester-based resin, in the case of a straight chain, it refers to both terminals, and in the case of a branched chain, it also includes the terminal of the branch. Among them, the polyester-based resin is preferably a straight chain, and has a hydroxyl group at both terminals.

[0095] The glass transition temperature (Tg) of the polyester-based resin is not particularly limited, and is preferably 50 to 140°C, more preferably 60 to 120°C, further preferably 70 to 110°C, and more further preferably 75 to 100°C.

[0096] When the glass transition temperature (Tg) of the polyester-based resin is the above lower limit value or more, there is a tendency to be able to suppress excessive deformation of the cushion layer when processing the workpiece. In addition, when the glass transition temperature (Tg) of the polyester-based resin is the above upper limit value or less, there is a tendency to improve the effect of absorbing vibrations, impacts, and the like generated at the time of grinding of the workpiece, and the retention of the adhesive sheet.

[0097] The glass transition temperature (Tg) of the polyester-based resin can be measured according to JIS K 7121:2012.

[0098] The number average molecular weight (Mn) of the polyester-based resin is not particularly limited, and is preferably 5000 to 100000, more preferably 10000 to 70000, further preferably 15000 to 50000, and more further preferably 30000 to 48000.

[0099] When the number average molecular weight (Mn) of the polyester-based resin is the above lower limit value or more, there is a tendency to be able to suppress excessive deformation of the cushion layer when processing the workpiece. In addition, when the number average molecular weight (Mn) of the polyester-based resin is the above upper limit value or less, there is a tendency to improve the effect of absorbing vibrations, impacts, and the like generated at the time of grinding of the workpiece, and the retention of the adhesive sheet.

[0100] The hydroxyl value of the polyester-based resin is not particularly limited, and is preferably 0.5 to 30 KOH mg / g, more preferably 1 to 20 KOH mg / g, further preferably 2 to 10 KOH mg / g, and more further preferably 2 to 5 KOH mg / g.

[0101] When the hydroxyl value of the polyester-based resin is the above lower limit value or more, there is a tendency to make the thermosetting good, to improve the low odor property, and to be able to suppress excessive deformation of the cushion layer when processing the workpiece. In addition, when the hydroxyl value of the polyester-based resin is the above upper limit value or less, there is a tendency to improve the effect of absorbing vibrations, impacts, and the like generated at the time of grinding of the workpiece, and the retention of the adhesive sheet.

[0102] The hydroxyl value of the polyester-based resin can be determined according to JIS K 0070:1992.

[0103] In the case where the thermosetting resin composition contains the polyester-based resin, the content of the polyester-based resin in the thermosetting resin composition is not particularly limited, and is preferably 30 to 98 mass%, more preferably 50 to 98 mass%, and further preferably 70 to 98 mass%, relative to the total amount of solid components (100 mass%) of the thermosetting resin composition.

[0104] When the content of the polyester-based resin is in the above range, there is a tendency that the low odor property and the ease of polishing property further become good.

[0105] Note that, in the present specification, the "total amount of solid components of the thermosetting resin composition" refers to components other than a solvent contained in the thermosetting resin composition, and the components other than the solvent are regarded as solid components even if they are in a liquid state at room temperature (23°C).

[0106] Note that, as a molding method of the polyester-based resin, processing based on extrusion molding is generally performed, and the extrusion molding requires heating the polyester-based resin to a high temperature, and thus the equipment and energy load are large, and it is difficult to obtain good productivity. In addition, since problems peculiar to extrusion molding such as generation of a mass called a fish eye occurs, it is also difficult to obtain excellent quality stability. In contrast, in the adhesive sheet of the present embodiment, since the polyester-based resin is used as a raw material of the thermosetting resin composition, it is possible to form a buffer layer of uniform quality under relatively mild heating conditions. Therefore, the adhesive sheet of the present embodiment is excellent in productivity and excellent in quality stability.

[0107] [Antistatic agent]

[0108] The thermosetting resin composition contains an antistatic agent.

[0109] The antistatic agent is not particularly limited, and examples include ionic materials, nonionic materials, amphoteric materials, metal salts, carbon nanotubes, and the like. Among them, from the viewpoint of more effectively suppressing the peeling static voltage, ionic materials are preferred.

[0110] The antistatic agent can be used alone or in combination with two or more kinds.

[0111] The ionic material can be an ion pair compound composed of a cation and an anion.

[0112] As the cation constituting the ionic material, examples include ammonium-based cations, imidazolium -based cations, -based cations, pyridinium -based cations, and pyrrolidinium Cationic, pyrroline Cationic and triazole Cationic, etc. These cations can be used singly or in combination of two or more.

[0113] Among them, from the viewpoint of having excellent antistatic properties, the cation constituting the ionic material is preferably selected from the group consisting of ammonium cationic, imidazole Cationic and pyridine Cationic, etc. These cations can be used singly or in combination of two or more.

[0114] As the above-mentioned ammonium cation, for example, cations derived from alkyl alcohol amine salt reaction products (alkyl alcohol amine cations), butyl trimethyl ammonium cations, triethyl propyl ammonium cations, 2-hydroxyethyl triethyl ammonium cations, methyl trioctyl ammonium cations, tetrabutyl ammonium cations, tetraethyl ammonium cations, tetraheptyl ammonium cations, tributyl methyl ammonium cations, triethyl methyl ammonium cations, tri(2-hydroxy)methyl ammonium cations, ammonium cations, etc. can be given. The ammonium cation can be used singly or in combination of two or more.

[0115] As the above-mentioned imidazole Cationic, for example, 1-allyl-3-methyl imidazole Cationic, 1-benzyl-3-methyl imidazole Cationic, 1,3-bis(cyanomethyl) imidazole Cationic, 1,3-bis(cyanopropyl) imidazole Cationic, 1-butyl-2,3-dimethyl imidazole Cationic, etc. The imidazole Cationic can be used singly or in combination of two or more.

[0116] As the above-mentioned pyridine Cationic, for example, 1-butyl pyridine Cationic, 1-hexyl pyridine Cationic, 1-butyl-3-methyl pyridine Cationic, 1-butyl-4-methyl pyridine Cationic, 1-octyl-4-methyl pyridine Cationic, etc. The pyridine Cationic can be used singly or in combination of two or more.

[0117] As the anion constituting the ionic material, for example, sulfonate anions, carboxylate anions, carbonate anions, amide anions, phosphate anions, thiocyanate anions, nitrate anions, borate anions, etc. can be given. These anions can be used singly or in combination of two or more.

[0118] Among them, from the viewpoint of excellent antistatic properties, the anion constituting the ionic material is more preferably at least one selected from the group consisting of sulfonate anions, borate anions, and phosphate anions.

[0119] As the above sulfonate anion, for example, an anion derived from a reaction product of a glycol ether sulfate (glycol ether sulfate anion), an anion derived from a reaction product of an alkylbenzenesulfonic acid (alkylbenzenesulfonic acid anion), a butyl sulfonate anion, a methyl sulfonate anion, an ethyl sulfonate anion, a hydrogen sulfonate anion, an octyl sulfonate anion, an alkyl sulfonate anion, a dialkyl succinate sulfonic acid anion, and the like can be given. The sulfonate anion can be used alone or in combination with two or more.

[0120] As the above borate anion, for example, a borate anion represented by the following formula (1) in which four groups are bonded to a boron atom can be given.

[0121] (R 1 )(R 2 )B-(R 3 )(R 4 )(1)

[0122] In the above formula (1), at least one group of R 1 and R 2 , and R 3 and R 4 is bonded to each other to form a monocyclic ring, or is bonded to each other to form a fused ring, or is not bonded to each other, R 1 , R 2 , R 3 , and R 4 are each independently a saturated or unsaturated organic group of 1 to 20 carbon atoms not containing a hetero atom, or a saturated or unsaturated organic group of 1 to 20 carbon atoms containing a hetero atom.

[0123] R 1 , R 2 , R 3 , and R 4 each independently represent an organic group selected from any of an alkyl group, a cycloalkyl group, an aryl group, an aralkyl group, an alkenyl group, an alkynyl group, and a heterocyclic group, and is an optionally hetero atom-containing group. As the hetero atom, at least one of a nitrogen atom, an oxygen atom, and a sulfur atom can be given.

[0124] The above borate anion represented by formula (1) can be a complex anion.

[0125] The borate anion can be used alone or in combination with two or more.

[0126] As the above-mentioned phosphoric acid ester anion, for example, an alkyl phosphoric acid ester anion such as an ethyl phosphoric acid ester anion, a dimethyl phosphoric acid ester anion, and the like can be given. The phosphoric acid ester anion can be used singly or in combination of two or more.

[0127] As the ionic material, a product prepared using a cation and an anion selected from the above-mentioned examples can be used, and a commercially available product can also be used. As the commercially available product of the ionic material, for example, "AMINO ION AS400" manufactured by Japan Emulsifier Co., Ltd., "CIL-H11" manufactured by Japan Carlit Co., Ltd., "CIL-317" manufactured by Japan Carlit Co., Ltd., and the like can be given.

[0128] The content of the antistatic agent in the thermosetting resin composition is not particularly limited, and is preferably 0.1 to 50 parts by mass, more preferably 0.5 to 40 parts by mass, further preferably 1 to 30 parts by mass, and more further preferably 2 to 25 parts by mass, relative to 100 parts by mass of the thermosetting resin.

[0129] In addition, the content of the antistatic agent in the thermosetting resin composition is not particularly limited, and is preferably 0.1 to 45 mass%, more preferably 0.4 to 35 mass%, further preferably 0.8 to 25 mass%, and more further preferably 1.5 to 20 mass%, relative to the total amount of the solid components (100 mass%) of the thermosetting resin composition.

[0130] When the content of the antistatic agent is equal to or greater than the above-mentioned lower limit value, there is a tendency that the peeling electrostatic voltage can be more effectively suppressed. In addition, when the content of the antistatic agent is equal to or less than the above-mentioned upper limit value, there is a tendency that the dispersibility of the antistatic agent in the thermosetting resin composition easily becomes further good.

[0131] [Crosslinking agent]

[0132] The thermosetting resin composition can contain a crosslinking agent for crosslinking the thermosetting resin as needed. The crosslinking agent can be used singly or in combination of two or more.

[0133] The crosslinking agent can be applied with a publicly known compound according to the kind of the reactive group possessed by the thermosetting resin as the crosslinking object, and for example, an isocyanate-based crosslinking agent, an epoxy-based crosslinking agent, an amine-based crosslinking agent, a melamine-based crosslinking agent, an aziridine-based crosslinking agent, a hydrazine-based crosslinking agent, an aldehyde-based crosslinking agent, an oxazoline-based crosslinking agent, a metal alkoxide-based crosslinking agent, a metal chelate-based crosslinking agent, a metal salt-based crosslinking agent, an ammonium salt-based crosslinking agent, and the like can be given.

[0134] Among the cross-linking agents described above, in the case where the thermosetting resin composition contains a polyester resin having 2 or more hydroxyl groups, the cross-linking agent is preferably an isocyanate-based cross-linking agent from the viewpoint of good thermosetting. The isocyanate-based cross-linking agent is preferably a polyisocyanate compound. The polyisocyanate compound is capable of bonding the polyester resin having a hydroxyl group to form a cross-linked structure because it has reactivity with a hydroxyl group.

[0135] The number of isocyanate groups possessed by the polyisocyanate compound can be, for example, 2 or 3, or more than 3, depending on the kind of the thermosetting resin to be cross-linked.

[0136] As the polyisocyanate compound, there can be mentioned, for example, aromatic isocyanates such as toluene diisocyanate, diphenylmethane diisocyanate, xylylene diisocyanate, 1,3,5-triisocyanatobenzene, 1,3,5-triisocyanatomesitylene, 2,4,6-triisocyanatotoluene, triphenylmethane-4,4',4"-triisocyanate; alicyclic isocyanate compounds such as dicyclohexylmethane-4,4'-diisocyanate, bicycloheptane triisocyanate, cyclopentylene diisocyanate, cyclohexylene diisocyanate, methylcyclohexylene diisocyanate, hydrogenated xylylene diisocyanate; aliphatic isocyanates such as hexamethylene diisocyanate, trimethylhexamethylene diisocyanate, lysine diisocyanate; and the like.

[0137] In addition, the polyisocyanate compound can be a modified body such as a biuret or isocyanurate of the above-mentioned exemplified compounds, an adduct of a reaction product of these compounds with a non-aromatic low-molecular active hydrogen-containing compound such as ethylene glycol, trimethylolpropane, castor oil, and the like.

[0138] Among these, the adduct of trimethylolpropane is preferred from the viewpoint of easy availability of good reactivity.

[0139] In the case where the thermosetting resin composition contains a polyester resin having 2 or more hydroxyl groups and a polyisocyanate compound, the content of the polyisocyanate compound in the thermosetting resin composition is not particularly limited, and is preferably 1 to 15 parts by mass relative to 100 parts by mass of the polyester resin having 2 or more hydroxyl groups.

[0140] When the content of the polyisocyanate compound is within the above-mentioned range, there is a tendency that the low odor property and the grindability of the adhesive sheet are further easily made good.

[0141] [Curing Catalyst]

[0142] The thermosetting resin composition can contain, as needed, a curing catalyst for promoting the thermosetting reaction of the thermosetting resin. The curing catalyst can be used singly or in combination of two or more kinds.

[0143] As the curing catalyst, for example, an organometallic compound, a tertiary amine compound, or the like can be mentioned. Among them, from the viewpoint of reactivity, an organometallic compound is preferred.

[0144] As the organometallic compound, a tin-based organometallic compound is preferred, and for example, dibutyl tin diacetate, dibutyl tin dioctoate, dibutyl tin dilaurate, dibutyl tin bis(2-ethylhexanoate), dibutyl tin bis(neodecanoate), dioctyl tin diacetate, dioctyl tin dioctoate, dioctyl tin dilaurate, dioctyl tin bis(2-ethylhexanoate), dioctyl tin bis(neodecanoate), or the like can be mentioned. Among them, from the viewpoint of reactivity, dioctyl tin dilaurate is preferred. As other organometallic compounds, for example, metal acylates (e.g., octoate compounds, naphthenate compounds, stearate compounds, or the like) of bismuth, titanium, zirconium, zinc, iron, or the like, metal chelates, metal alkoxides, or the like can be mentioned. These can be used singly or in combination of two or more.

[0145] In the case where the thermosetting resin composition contains a curing catalyst, the content of the curing catalyst in the thermosetting resin composition is not particularly limited, and relative to 100 parts by mass of the thermosetting resin, 0.01 to 10 parts by mass, more preferably 0.05 to 5 parts by mass, and further preferably 0.1 to 1 part by mass is preferred.

[0146] When the content of the curing catalyst is within the above range, the thermosetting reaction can be uniformly and sufficiently performed.

[0147] [Other Components]

[0148] The thermosetting resin composition can contain other components within a range not impairing the effects of the present application. As the other components, for example, resin components other than the above-described resin, other additives such as antioxidants, softening agents, fillers, rust-preventive agents, pigments, dyes, or the like, and the like can be mentioned.

[0149] (Thickness of the Buffer Layer)

[0150] The thickness of the buffer layer is not particularly limited, and 2 to 100 μm is preferred, 5 to 80 μm is more preferred, 10 to 70 μm is further preferred, and 20 to 60 μm is still further preferred.

[0151] When the thickness of the buffer layer is equal to or greater than the above lower limit value, there is a tendency that the effect of absorbing vibrations, impacts, or the like generated at the time of grinding of the workpiece and the adhesion of the workpiece are improved. In addition, when the thickness of the buffer layer is equal to or smaller than the above upper limit value, there is a tendency that the economic efficiency is excellent while the excessive deformation of the buffer layer at the time of processing the workpiece is suppressed.

[0152] (Surface Resistivity of the Buffer Layer)

[0153] The surface resistivity of the buffer layer of the adhesive sheet of the present embodiment is preferably 1.0 x 10 12 Ω / sq. or less, more preferably 5.0 x 10 11 Ω / sq. or less, more preferably 5.0 x 10 11 Ω / sq. or less, more preferably 5.0 x 10 10 Ω / sq. or less.

[0154] When the surface resistivity of the buffer layer is the above upper limit value or less, there is a tendency that the peeling static voltage can be more sufficiently suppressed.

[0155] The surface resistivity of the buffer layer is more preferably lower, and can be 1.0 x 10 7 Ω / sq. or more, 1.0 x 10 8 Ω / sq. or more, 1.0 x 10 9 Ω / sq. or more.

[0156] The surface resistivity of the buffer layer can be measured by the method described in the examples.

[0157] <Adhesive layer>

[0158] The adhesive layer is not particularly limited, and is preferably a layer formed of an energy ray-curable adhesive. By forming the adhesive layer of an energy ray-curable adhesive, it is possible to protect the workpiece surface well with sufficient adhesiveness before energy ray curing, and it is possible to reduce the peeling force after energy ray curing, thereby achieving easy peeling from the workpiece.

[0159] As the energy ray-curable adhesive, for example, the following can be cited: an adhesive composition of Type X, an adhesive composition of Type Y, an adhesive composition of Type XY, and the like.

[0160] Adhesive composition of Type X: an energy ray-curable adhesive composition containing an adhesion resin that is not energy ray-curable (hereinafter, also referred to as "adhesion resin I"), and an energy ray-curable compound other than the adhesion resin

[0161] Adhesive composition of Type Y: an energy ray-curable adhesive composition containing an adhesion resin that is energy ray-curable in which an unsaturated group is introduced into the side chain of an adhesion resin that is not energy ray-curable (hereinafter, also referred to as "adhesion resin II"), and not containing an energy ray-curable compound other than the adhesion resin

[0162] Adhesive composition of Type XY: an energy ray-curable adhesive composition containing the above adhesion resin II that is energy ray-curable, and an energy ray-curable compound other than the adhesion resin

[0163] Among them, the energy ray-curable adhesive is preferably an adhesive composition of the XY type. By using an adhesive composition of the XY type, there is a tendency to have sufficient adhesiveness before curing and, on the other hand, to be able to sufficiently reduce the peeling force with respect to the work after curing.

[0164] The adhesive layer can also be a layer formed of an adhesive that is not energy ray-curable, i.e., does not undergo curing even when energy rays are irradiated. As an adhesive that is not energy ray-curable, for example, an adhesive containing the adhesive resin I but not containing the adhesive resin II and the energy ray-curable compound can be cited.

[0165] Next, each component constituting the adhesive layer will be described in more detail.

[0166] In the following description, the term "adhesive resin" is used as a term having the meaning of one or both of the adhesive resin I and the adhesive resin II. In addition, in the following description, in the case of being simply described as "adhesive composition", it is considered to include the concept of the adhesive composition of the X type, the adhesive composition of the Y type, the adhesive composition of the XY type, and an adhesive composition other than these.

[0167] As the adhesive resin, for example, an acrylic resin, a urethane resin, a rubber-based resin, a silicone-based resin, or the like can be cited. Among them, an acrylic resin is preferred.

[0168] (acrylic resin)

[0169] The acrylic resin preferably contains a structural unit derived from an alkyl (meth)acrylate.

[0170] As the alkyl (meth)acrylate, for example, an alkyl (meth)acrylate in which the number of carbon atoms of the alkyl group is 1 to 20 can be cited.

[0171] The alkyl group possessed by the alkyl (meth)acrylate can be linear or branched.

[0172] From the viewpoint of further improving the adhesive force of the adhesive layer, the acrylic resin preferably contains a structural unit derived from an alkyl (meth)acrylate in which the number of carbon atoms of the alkyl group is 4 or more.

[0173] The structural unit derived from an alkyl (meth)acrylate in which the number of carbon atoms of the alkyl group is 4 or more contained in the acrylic resin can be a single one or two or more.

[0174] The number of carbon atoms of the alkyl group possessed by the alkyl (meth)acrylate in which the number of carbon atoms of the alkyl group is 4 or more is preferably 4 to 12, more preferably 4 to 8, and further preferably 4 to 6.

[0175] As the (meth)acrylic acid alkyl ester having 4 or more carbon atoms in the alkyl group, for example, (meth)acrylic acid butyl ester, (meth)acrylic acid 2-ethylhexyl ester, (meth)acrylic acid n-octyl ester, (meth)acrylic acid iso-octyl ester, (meth)acrylic acid nonyl ester, (meth)acrylic acid decyl ester, (meth)acrylic acid undecyl ester, (meth)acrylic acid dodecyl ester, and the like can be exemplified. Among them, (meth)acrylic acid butyl ester is preferred, and acrylic acid butyl ester is more preferred.

[0176] In the case where the acrylic resin contains a structural unit derived from the (meth)acrylic acid alkyl ester having 4 or more carbon atoms in the alkyl group, the content thereof in the acrylic resin is preferably 30 to 90% by mass, more preferably 40 to 80% by mass, and further preferably 45 to 60% by mass, from the viewpoint of further improving the adhesion of the adhesive layer.

[0177] From the viewpoint of making the storage modulus G' and the adhesion properties of the adhesive layer good, the acrylic resin preferably contains a structural unit derived from the (meth)acrylic acid alkyl ester having 1 to 3 carbon atoms in the alkyl group, in addition to the structural unit derived from the (meth)acrylic acid alkyl ester having 4 or more carbon atoms in the alkyl group.

[0178] The structural unit derived from the (meth)acrylic acid alkyl ester having 1 to 3 carbon atoms in the alkyl group contained in the acrylic resin can be one alone or two or more.

[0179] As the (meth)acrylic acid alkyl ester having 1 to 3 carbon atoms in the alkyl group, for example, (meth)acrylic acid methyl ester, (meth)acrylic acid ethyl ester, (meth)acrylic acid iso-propyl ester, (meth)acrylic acid n-propyl ester, and the like can be exemplified. Among them, (meth)acrylic acid methyl ester, (meth)acrylic acid ethyl ester are preferred, and (meth)acrylic acid methyl ester is more preferred, and methyl (meth)acrylic acid methyl ester is further preferred.

[0180] In the case where the acrylic resin contains a structural unit derived from the (meth)acrylic acid alkyl ester having 1 to 3 carbon atoms in the alkyl group, the content thereof in the acrylic resin is preferably 1 to 35% by mass, more preferably 5 to 30% by mass, and further preferably 15 to 25% by mass.

[0181] The acrylic resin preferably further contains a structural unit derived from a functional group-containing monomer.

[0182] By making the acrylic resin contain a structural unit derived from a functional group-containing monomer, a functional group that is a crosslinking starting point for reaction with a crosslinking agent, or a functional group that can react with a compound containing an unsaturated group to introduce an unsaturated group to the side chain of the acrylic resin can be introduced.

[0183] The structural unit derived from a functional group-containing monomer contained in the acrylic resin can be one alone or two or more.

[0184] As the functional group-containing monomer, for example, a hydroxyl group-containing monomer, a carboxyl group-containing monomer, an amino group-containing monomer, an epoxy group-containing monomer, and the like can be exemplified. Among them, a hydroxyl group-containing monomer, a carboxyl group-containing monomer are preferred, and a hydroxyl group-containing monomer is more preferred.

[0185] As the hydroxyl group-containing monomer, for example, a (meth)acrylic acid hydroxyalkyl ester such as 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 3-hydroxybutyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, and the like; an unsaturated alcohol such as vinyl alcohol, allyl alcohol, and the like can be exemplified.

[0186] As the carboxyl group-containing monomer, for example, an ethylenically unsaturated monocarboxylic acid such as (meth)acrylic acid, crotonic acid, and the like; an ethylenically unsaturated dicarboxylic acid such as fumaric acid, itaconic acid, maleic acid, citraconic acid, and the like, and an anhydride thereof; 2-carboxyethyl methacrylate; and the like can be exemplified.

[0187] In the case where the acrylic resin contains a structural unit derived from the functional group-containing monomer, the content thereof is not particularly limited, and it is preferably 5 to 45 mass%, and more preferably 15 to 40 mass% in the acrylic resin.

[0188] The acrylic resin can contain, in addition to the above-described structural unit, a structural unit derived from another monomer copolymerizable with the acrylic monomer.

[0189] The structural unit derived from the other monomer contained in the acrylic resin can be one alone or two or more.

[0190] As the other monomer, for example, styrene, α-methylstyrene, vinyltoluene, vinyl formate, vinyl acetate, acrylonitrile, acrylamide, and the like can be exemplified.

[0191] In the acrylic resin, an unsaturated group having an energy ray polymerizability can also be further introduced in order to impart an energy ray curability.

[0192] The unsaturated group can be introduced, for example, by reacting a functional group of the acrylic resin containing a structural unit derived from the functional group-containing monomer, and a reactive substituent of a compound having a reactive substituent having a reactivity with the functional group and an unsaturated group (hereinafter, also referred to as "unsaturated group-containing compound"). The unsaturated group-containing compound can be used alone or two or more can be used in combination.

[0193] As the unsaturated group possessed by the unsaturated group-containing compound, for example, a (meth)acryloyl group, a vinyl group, an allyl group, and the like can be exemplified. Among them, a (meth)acryloyl group is preferred.

[0194] As the reactive substituent group possessed by the compound containing an unsaturated group, there can be mentioned, for example, isocyanate group, glycidyl group, and the like.

[0195] As the compound containing an unsaturated group, there can be mentioned, for example, (meth)acryloyloxyethyl isocyanate, (meth)acryloyl isocyanate, glycidyl (meth)acrylate, and the like.

[0196] In the case where the acrylic resin containing a structural unit derived from a functional group-containing monomer is reacted with the compound containing an unsaturated group, the ratio of the functional groups reacted with the compound containing an unsaturated group in the total number of the functional groups in the acrylic resin is not particularly limited, and is preferably 60 to 98 mol%, more preferably 70 to 95 mol%, and further preferably 80 to 93 mol%.

[0197] When the ratio of the functional groups reacted with the compound containing an unsaturated group is within the above range, the acrylic resin can be imparted with sufficient energy ray curability, and the functional groups not reacted with the compound containing an unsaturated group can be reacted with the crosslinking agent to crosslink the acrylic resin.

[0198] The weight average molecular weight (Mw) of the acrylic resin is not particularly limited, and is preferably 300,000 to 1,500,000, more preferably 350,000 to 1,000,000, and further preferably 400,000 to 600,000. When the weight average molecular weight (Mw) of the acrylic resin is within the above range, there is a tendency that the adhesion and cohesion of the adhesive layer become more favorable.

[0199] (Energy ray curable compound)

[0200] As the energy ray curable compound contained in the adhesive composition of the X type or XY type, there is preferably a monomer or oligomer having an unsaturated group in the molecule and capable of being cured by irradiation of energy rays.

[0201] As the energy ray curable compound, there can be mentioned, for example, polyvalent (meth)acrylate monomers such as trimethylolpropane tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, dipentaerythritol hexa(meth)acrylate, 1,4-butanediol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, and the like; oligomers such as urethane (meth)acrylate, polyester (meth)acrylate, polyether (meth)acrylate, epoxy (meth)acrylate, and the like; and the like. Among them, from the viewpoint that the molecular weight is high and the elastic modulus of the adhesive layer is less likely to decrease, there is preferably a urethane (meth)acrylate oligomer.

[0202] The molecular weight of the energy ray-curable compound is not particularly limited, and is preferably from 100 to 12,000, more preferably from 200 to 10,000, further preferably from 400 to 8,000, and more further preferably from 600 to 6,000. Note that in the case where the energy ray-curable compound is an oligomer, the above-mentioned molecular weight indicates the weight average molecular weight (Mw).

[0203] The content of the energy ray-curable compound in the adhesive composition of the XY type is not particularly limited, and is preferably from 1 to 30 parts by mass, more preferably from 2 to 20 parts by mass, and further preferably from 3 to 15 parts by mass, relative to 100 parts by mass of the adhesive resin.

[0204] When the content of the energy ray-curable compound in the adhesive composition of the XY type is within the above-mentioned range, there is a tendency for the balance between the adhesion before energy ray irradiation and the peelability after energy ray irradiation to become good. Note that in the adhesive composition of the XY type, since the adhesive resin is energy ray-curable, there is a tendency for the peel force to be sufficiently reduced after irradiation of energy rays even if the content of the energy ray-curable compound is small.

[0205] (Cross-linking agent)

[0206] The adhesive composition preferably further contains a cross-linking agent.

[0207] The cross-linking agent is, for example, a component that cross-links the adhesive resins to each other by reacting with the functional groups derived from the functional group-containing monomers possessed by the adhesive resins.

[0208] The cross-linking agent can be used singly or in combination of two or more.

[0209] As the cross-linking agent, there can be mentioned, for example, isocyanate-based cross-linking agents such as toluene diisocyanate, hexamethylene diisocyanate, and adducts thereof; epoxy-based cross-linking agents such as ethylene glycol glycidyl ether; aziridine-based cross-linking agents such as hexakis[l-(2-methyl)-aziridinyl]triazine; chelate-based cross-linking agents such as aluminum chelate; and the like. Among these, from the viewpoints of improving the cohesiveness to further improve the adhesion and easiness of obtaining, an isocyanate-based cross-linking agent is preferred.

[0210] In the case where the adhesive composition contains a cross-linking agent, the content thereof is not particularly limited, and is preferably from 0.01 to 10 parts by mass, more preferably from 0.03 to 7 parts by mass, and further preferably from 0.05 to 4 parts by mass, relative to 100 parts by mass of the adhesive resin, from the viewpoint of allowing the cross-linking reaction to proceed moderately.

[0211] (Photo-polymerization initiator)

[0212] In the case where the adhesive is an energy ray-curable adhesive, the adhesive composition preferably further contains a photopolymerization initiator. By causing the energy ray-curable adhesive to contain a photopolymerization initiator, there is a tendency that the curing reaction of the energy ray-curable adhesive can be sufficiently performed even with a lower energy of energy rays such as ultraviolet rays.

[0213] The photopolymerization initiator can be used alone or in combination of two or more.

[0214] As the photopolymerization initiator, there can be mentioned, for example, benzoin compounds, phenylacetone compounds, acyloxyphosphine compounds, titanocene compounds, thioxanthone compounds, peroxide compounds, and photosensitizers such as amines, quinones, and the like, and more specifically, there can be mentioned, for example, 1-hydroxycyclohexyl phenyl ketone, 2-hydroxy-2-methyl-l-phenyl-propane-l-one, benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzyl phenyl sulfide, tetramethylthiuram monosulfide, azobisisobutyronitrile, benzpinacol, butanedione, 8-chloroanthraquinone, phenyl bis(2,4,6-trimethylbenzoyl)phosphine oxide, and the like.

[0215] In the case where the adhesive composition contains a photopolymerization initiator, the content thereof is not particularly limited, and from the viewpoint of causing the energy ray-curing reaction to proceed uniformly and sufficiently, it is preferably 0.01 to 10 parts by mass, more preferably 0.03 to 7 parts by mass, and further preferably 0.05 to 5 parts by mass, relative to 100 parts by mass of the adhesive resin.

[0216] (Other additives)

[0217] The adhesive composition can also contain other additives within a range not impairing the effects of the present application. As the other additives, there can be mentioned, for example, antistatic agents, antioxidants, softening agents, fillers, rust-preventive agents, pigments, dyes, and the like.

[0218] (Organic solvent)

[0219] From the viewpoint of further improving the coatability onto a substrate, a release sheet, or the like, the adhesive composition can be diluted with an organic solvent to be in the form of a solution. The organic solvent can be the same as the organic solvent that can be contained in the thermosetting resin composition described later. The organic solvent can be directly used as the organic solvent used at the time of synthesis of the adhesive resin, or one or more kinds of organic solvents other than the organic solvent used at the time of synthesis can be added.

[0220] The thickness of the adhesive layer is not particularly limited, and is preferably 5 to 100 μm, more preferably 10 to 80 μm, and further preferably 15 to 60 μm.

[0221] When the thickness of the adhesive layer is equal to or greater than the above lower limit value, there is a tendency that excellent adhesion can be obtained and the surface of the workpiece can be more favorably protected during processing. In addition, when the thickness of the adhesive layer is equal to or smaller than the above upper limit value, there is a tendency that the generation of chips at the time of cutting the adhesive sheet can be suppressed and the breakage of the workpiece can be more favorably prevented.

[0222] <Substrate>

[0223] As the substrate, various resin films, for example, can be given. As the resin constituting the resin film, polyethylene such as low-density polyethylene (LDPE), linear low-density polyethylene (LLDPE), high-density polyethylene (HDPE), polypropylene, polybutylene, polybutadiene, polymethylpentene, ethylene-norbornene copolymer, norbornene resin, and the like; polyolefin such as ethylene-vinyl acetate copolymer, ethylene-(meth)acrylic acid copolymer, ethylene-(meth)acrylic ester copolymer, and the like; polyvinyl chloride such as polyvinyl chloride, vinyl chloride copolymer, and the like; polyester such as polyethylene terephthalate, polyethylene naphthalate, polybutylene terephthalate, wholly aromatic polyester, and the like; polyurethane, polyimide, polyamide, polycarbonate, fluororesin, polyacetal, modified polyphenylene ether, polyphenylene sulfide, polysulfone, polyether ketone, acrylic polymer, and the like can be given.

[0224] The substrate can be a single layer film of a resin film formed of one or two or more kinds of resins selected from among these resins, or can be a laminated film in which two or more of these resin films are laminated. In addition, it can also be a modified film such as a crosslinked film of the above-mentioned resins, an ionomer film, and the like.

[0225] Among these resin films, the substrate is preferably one or more kinds selected from among a polyester film, a polyamide film, a polyimide film, and a biaxially-stretched polypropylene film, more preferably a polyester film, and further preferably a polyethylene terephthalate film.

[0226] The Young's modulus of the substrate is not particularly limited, and is preferably 1000 MPa or greater, more preferably 1800 to 30000 MPa, and further preferably 2500 to 6000 MPa.

[0227] Note that the Young's modulus of the substrate can be measured based on JIS K 7127:1999, under the condition of a test speed of 200 mm / min.

[0228] The thickness of the substrate is not particularly limited, and is preferably 10 to 200 μm, more preferably 25 to 100 μm, and further preferably 30 to 70 μm.

[0229] When the thickness of the base material is equal to or greater than the lower limit value described above, there is a tendency that sufficient strength for functioning as a support of an adhesive sheet can be obtained. In addition, when the thickness of the base material is equal to or smaller than the upper limit value described above, there is a tendency that moderate flexibility and improved handling are obtained.

[0230] Note that the "thickness of the base material" refers to the thickness of the entire base material, and in the case where the base material is a base material composed of multiple layers, refers to the total thickness of all the layers constituting the base material.

[0231] The base material can contain a plasticizer, a lubricant, an infrared absorber, an ultraviolet absorber, a filler, a colorant, an antistatic agent, an antioxidant, a catalyst, and the like, within a range that does not impair the effects of the present application.

[0232] The base material can be transparent or non-transparent, and can be colored or vapor-deposited as desired.

[0233] From the viewpoint of improving the adhesion to other layers, at least one surface of the base material can be subjected to surface treatment such as corona treatment, and a coating layer for the purpose of improving adhesion can be provided.

[0234] <Release sheet>

[0235] The release sheet protects the surface of the adhesive sheet before use by being attached to the surface in a releasable manner, and is peeled off and removed when the adhesive sheet is used.

[0236] The release sheet can be a release sheet subjected to single-sided release treatment, or a release sheet subjected to double-sided release treatment.

[0237] As the release sheet, a release sheet in which a release agent such as a polysiloxane-based resin is applied to a release sheet base material can be preferably selected. As the release sheet base material, the same base materials exemplified as the base material possessed by the adhesive sheet of the present embodiment can be listed.

[0238] <Total thickness of adhesive sheet>

[0239] The total thickness of the adhesive sheet of the present embodiment is not particularly limited, and is preferably 30 to 300 μm, more preferably 40 to 220 μm, and further preferably 45 to 180 μm.

[0240] When the total thickness of the adhesive sheet is equal to or greater than the lower limit value described above, there is a tendency that the adhesion of the adhesive layer, the impact absorption of the cushion layer, and the like are appropriately maintained, and the function as an adhesive sheet for workpiece processing can be sufficiently exerted. In addition, when the total thickness of the adhesive sheet is equal to or smaller than the upper limit value described above, there is a tendency that the peeling force at the time of peeling the workpiece from the adhesive sheet can be reduced.

[0241] Note that in the case where the adhesive sheet of the present embodiment is provided with a release sheet, the thickness of the release sheet is not included in the "total thickness of the adhesive sheet".

[0242] [Method for manufacturing adhesive sheet]

[0243] The method for manufacturing the adhesive sheet of the present embodiment is a method having a step of curing the thermosetting resin composition by heating (hereinafter also referred to as "heat curing step"). By the heat curing step, the cushion layer possessed by the adhesive sheet of the present embodiment can be formed.

[0244] The heat curing step is preferably a step of curing the coating film formed by applying the thermosetting resin composition by heating.

[0245] When the thermosetting resin composition is applied, the thermosetting resin composition is preferably in the form of a solution diluted with an organic solvent. By dilution with an organic solvent, the application operation becomes easy, and the thickness of the cushion layer can be easily adjusted, and even a thin cushion layer can be formed with excellent thickness precision.

[0246] As the organic solvent, for example, methyl ethyl ketone, acetone, ethyl acetate, tetrahydrofuran, dioxane, cyclohexane, n-hexane, toluene, xylene, n-propanol, isopropanol, and the like can be exemplified. The organic solvent can be used alone or in combination of two or more.

[0247] The content of the organic solvent in the thermosetting resin composition diluted with an organic solvent is not particularly limited, and is preferably 40 to 90% by mass, more preferably 50 to 85% by mass, and further preferably 60 to 80% by mass.

[0248] The thermosetting resin composition can be applied to a release sheet, or can be directly applied to the surface of a substrate or an adhesive layer.

[0249] As the method for applying the thermosetting resin composition, for example, spin coating, spray coating, bar coating, doctor blade coating, roll coating, roll-knife coating, blade coating, die coating, gravure coating, and the like can be exemplified.

[0250] From the viewpoint of productivity of the adhesive sheet and sufficient curing of the thermosetting resin composition, the heating temperature of the thermosetting resin composition is preferably 80 to 150°C, more preferably 90 to 140°C, and further preferably 100 to 130°C.

[0251] In addition, from the viewpoint of productivity of the adhesive sheet and sufficient curing of the thermosetting resin composition, the heating time of the thermosetting resin composition is preferably 0.1 to 60 minutes, more preferably 0.3 to 30 minutes, and further preferably 0.5 to 5 minutes.

[0252] ​In the case where the thermosetting resin composition is applied to the release sheet to obtain a release sheet with a cushion layer, subsequently, it is only necessary to adhere the cushion layer of the release sheet with the cushion layer to the surface of the substrate or the adhesive layer.

[0253] In the method for manufacturing the adhesive sheet of the present embodiment, the method for forming the adhesive layer is not particularly limited, and a method in which drying is performed after the above-mentioned adhesive composition is applied, for example, can be exemplified.

[0254] The adhesive composition can be applied to the release sheet, or can be directly applied to the surface of the substrate or the cushion layer. In the case where the adhesive composition is applied to the release sheet to obtain a release sheet with an adhesive layer, subsequently, it is only necessary to adhere the adhesive layer of the release sheet with the adhesive layer to the surface of the substrate or the cushion layer. The method for applying the adhesive composition is described in the same manner as the method for applying the above-mentioned thermosetting resin composition.

[0255] <Use of the adhesive sheet>

[0256] As the processing of the workpiece performed in a state where the adhesive sheet of the present embodiment is adhered, a back-grinding process in which the other face is ground in a state where the adhesive sheet is adhered to one face of the workpiece, a cutting process in which the workpiece is singulated in a state where the adhesive sheet is adhered to one face of the workpiece, the conveyance of the workpiece, the picking up of the workpiece singulation, and the like can be exemplified.

[0257] Among them, the adhesive sheet of the present embodiment is suitable for the grinding of the workpiece, is more suitable for the back-grinding process of the workpiece, and is further suitable for the back-grinding process in which the back face of the workpiece is ground in a state where the adhesive sheet of the present embodiment is adhered to the circuit formation face of the workpiece.

[0258] In particular, the adhesive sheet of the present embodiment has an effect of suppressing the generation of cracks when the workpiece is thinned, and is thus suitable for a process such as a first-cutting method, a phantom first-cutting method, and the like, and specifically, is preferably used in a manner in which the workpiece has a groove on the surface or has a modified region inside, and the back face of the workpiece is ground in a state where the above-mentioned workpiece processing adhesive sheet adhered to the surface of the workpiece is fixed, whereby the workpiece is singulated into a plurality of workpiece singulations with the above-mentioned groove or the above-mentioned modified region as a starting point.

[0259] [Method for manufacturing electronic device]

[0260] The method for manufacturing the electronic device of the present embodiment includes:

[0261] a step of adhering the workpiece processing adhesive sheet of the present embodiment to the surface of the workpiece with the above-mentioned adhesive layer as an adhering face; and

[0262] a step of grinding the back face of the workpiece in a state where the above-mentioned workpiece processing adhesive sheet adhered to the workpiece is fixed.

[0263] Further, the manufacturing method of the electronic device apparatus of the present embodiment preferably includes:

[0264] a predetermined division line forming step of forming a groove on the surface of the workpiece or a modification region inside the workpiece from the surface or the back surface of the workpiece;

[0265] a sheet adhering step of adhering the workpiece processing adhesive sheet of the present embodiment to the surface of the workpiece with the adhesive layer as the adhering surface after the step a or before or after the step b; and

[0266] a grinding and singulation step of grinding the back surface of the workpiece in a state where the workpiece processing adhesive sheet adhered to the workpiece is fixed, and singulating the workpiece into a plurality of workpiece singulation products using the groove or the modification region as a starting point.

[0267] Further, the manufacturing method of the electronic device apparatus of the present embodiment can also include a peeling step of peeling the workpiece processing adhesive sheet of the present embodiment from the plurality of workpiece singulation products after the grinding and singulation step.

[0268] Note that the manufacturing method of the electronic device apparatus having the step a is a process equivalent to a pre-dicing method, and the manufacturing method of the electronic device apparatus having the step b is a process equivalent to a stealth dicing method.

[0269] Hereinafter, each step of the manufacturing method of the electronic device apparatus of the present embodiment will be described in detail.

[0270] <Pre-determined division line forming step>

[0271] The predetermined division line forming step is a step a of forming a groove on the surface of the workpiece or a step b of forming a modification region inside the workpiece from the surface or the back surface of the workpiece.

[0272] The step a is a step of forming a groove on the surface of the workpiece, and is performed before adhering the adhesive sheet to the surface of the workpiece.

[0273] The groove formed on the surface of the workpiece in the step a is a groove having a depth shallower than the thickness of the workpiece. After the step a, the workpiece is ground from the back surface to reach the position of the groove formed in the step a, and is thereby divided into a plurality of workpiece singulation products. Therefore, in the step a, the groove is formed along the division line at which the workpiece is divided and singulated.

[0274] The formation of the groove can be performed by cutting using a wafer cutting device or the like that is publicly known.

[0275] The process b is a process of forming a modified region inside the workpiece from the surface or the back surface of the workpiece, and can be performed before or after the adhesive sheet is attached to the surface of the workpiece.

[0276] In the process b, the modified region is formed inside the workpiece by irradiation of laser light having a focal point focused on the inside of the workpiece. The modified region is a portion in which embrittlement occurs in the workpiece, and is a region that is thinned by back surface grinding or is destroyed due to application of force based on grinding, thereby becoming a starting point of singulation of the workpiece. Therefore, the modified region is formed along a division line when the workpiece is divided and singulated.

[0277] The irradiation of laser light can be performed from the surface side of the workpiece or from the back surface side. In the case where the process b is performed after the sheet attaching process, the workpiece can be irradiated with laser light through the adhesive sheet.

[0278] <Sheet attaching process>

[0279] The sheet attaching process is a process of attaching an adhesive sheet to the surface of the workpiece with an adhesive layer as an attachment surface after the process a or before or after the process b.

[0280] The method of attaching the adhesive sheet is not particularly limited, and a publicly known method using a laminator or the like can be employed.

[0281] <Grinding and singulation process>

[0282] The grinding and singulation process is a process of grinding the back surface of the workpiece in a state where the workpiece processing adhesive sheet attached to the workpiece is fixed by a support device, and singulating the workpiece into a plurality of workpiece singulation products from the above-described groove or the above-described modified region as a starting point.

[0283] For the workpiece to which the adhesive sheet is attached and in which the groove or the modified region is formed, the adhesive sheet side is fixed by the support device. The support device is not particularly limited, and is preferably a device such as a chuck table that holds a fixed object by suction.

[0284] Next, the back surface of the fixed workpiece is ground, and the workpiece is singulated into a plurality of workpiece singulation products.

[0285] In the case where the groove is formed in the workpiece by the process a, at least the workpiece is ground to a position where the ground surface reaches the bottom of the groove in the back surface grinding. By the back surface grinding, the groove becomes a notch that penetrates the workpiece, and the workpiece is divided and singulated into individual workpiece singulation products through the notch.

[0286] On the other hand, in the case where the modified region is formed in the work by the process b, the ground surface can reach the modified region, but can also not strictly reach the modified region. That is, it is only necessary to grind to a position close to the modified region so that the work is broken and singulated with the modified region as a starting point. For example, after grinding to a position close to the modified region without singulating the work, a pickup tape can be attached to the work, and the semiconductor chips can be singulated by stretching the pickup tape.

[0287] The shape of the work singulation after the singulation can be a square shape, or an elongated shape such as a rectangular shape.

[0288] The thickness of the work singulation after the singulation is not particularly limited, and is preferably 5 to 100 μm, more preferably 7 to 70 μm, and further preferably 10 to 45 μm.

[0289] The size of the work singulation after the singulation is not particularly limited, and is preferably less than 50 mm 2 , more preferably less than 30 mm 2 , and further preferably less than 10 mm 2 .

[0290] <Peeling Process>

[0291] The peeling process is a process of peeling the adhesive sheet from the plurality of work singulations after the grinding and singulation processes.

[0292] In the case where the adhesive layer of the adhesive sheet is formed of an energy ray-curable adhesive, the adhesive sheet is peeled after the adhesive is cured by irradiation of an energy ray to reduce the peeling force of the adhesive layer.

[0293] Note that, at the time of peeling the adhesive sheet, a pickup tape can also be used. The pickup tape can be composed of, for example, an adhesive sheet having a base material and an adhesive layer provided on one surface of the base material.

[0294] In the case of using the pickup tape, the pickup tape is first attached to the back surface side of the work singulation after the singulation, and position and direction alignment is performed so that pickup is possible. At this time, it is preferable to fit a ring-shaped frame arranged on the outer peripheral side of the work singulation to the pickup tape, and to fix the outer peripheral edge portion of the pickup tape to the ring-shaped frame. Subsequently, the adhesive sheet is peeled from the plurality of work singulations fixed on the pickup tape.

[0295] Then, the plurality of work singulations on the pickup tape can be picked up and fixed on a substrate or the like, thereby manufacturing an electronic device.

[0296] Example

[0297] The present application will be described in more detail based on examples below, but the present application is not limited by these examples.

[0298] Note that the compounding amount of each component and the like in the following description represents the compounding amount of the effective component.

[0299] The measurement method and evaluation method of various physical properties are described below.

[0300] Weight average molecular weight (Mw) and number average molecular weight (Mn)

[0301] The weight average molecular weight (Mw) and the number average molecular weight (Mn) were measured using a gel permeation chromatography device (manufactured by Tosoh Corporation, trade name "HLC-8220") under the following conditions, and were calculated by converting to standard polystyrene.

[0302] (Measurement conditions)

[0303] • Column: "TSK guard column HXL-H" "TSK gel GMHXL (x2)", "TSK gel G2000HXL" (all manufactured by Tosoh Corporation)

[0304] • Column temperature: 40°C

[0305] • Elution solvent: Tetrahydrofuran

[0306] • Flow rate: 1.0 mL / min

[0307] [Thickness measurement of adhesive sheet for workpiece processing]

[0308] The total thickness of the adhesive sheet for workpiece processing, the thickness of each layer, and the thickness of the test piece made therefrom were measured using a constant pressure thickness gauge (manufactured by TECLOCK Co., Ltd., trade name "PG-02"). At this time, 10 points were measured at random, and the average value was calculated.

[0309] Note that the total thickness of the adhesive sheet for workpiece processing is a value obtained by measuring the thickness of the adhesive sheet for workpiece processing with a release sheet, and subtracting the thickness of the release sheet from the thickness thereof.

[0310] In addition, the thickness of the buffer layer is a value obtained by subtracting the thickness of the substrate from the thickness of the substrate with a buffer layer.

[0311] In addition, the thickness of the adhesive layer is a value obtained by subtracting the thickness of the buffer layer and the substrate from the total thickness of the adhesive sheet for workpiece processing.

[0312] [Low odor evaluation]

[0313] The release tab was peeled off from the adhesive sheet for workpiece processing manufactured in the examples and comparative examples, and a sensory evaluation of unpleasant odor was conducted at room temperature (23°C). The low odor of the adhesive sheet for workpiece processing was evaluated based on the following criteria.

[0314] A: No unpleasant odor

[0315] C: Has an unpleasant odor

[0316] [Measurement of the surface resistivity of the buffer layer]

[0317] (1) Fabrication of substrate with buffer layer

[0318] (1-1) Method for manufacturing a substrate with a buffer layer using a thermosetting buffer layer forming composition

[0319] As a substrate, a polyethylene terephthalate (PET) film with a thickness of 50 μm was prepared. A thermosetting resin composition, prepared as a buffer layer forming composition in Examples 1-8 and Comparative Examples 1-3, was coated onto one side of the substrate, resulting in a dried thickness of 30 μm, thus forming a coated film. Next, the coated film was heated at 110°C for 2 minutes to dry the organic solvent and to perform a thermosetting resin composition thermosetting reaction, resulting in a substrate with a buffer layer having a thickness of 30 μm formed on one side of the substrate.

[0320] (1-2) Method for manufacturing a substrate with a buffer layer using an energy-curable buffer layer forming composition

[0321] Using the same method as described in Comparative Example 4 below, a substrate with a buffer layer having a thickness of 28 μm formed on one side of the substrate was obtained.

[0322] (2) Measurement of surface resistivity

[0323] The substrate with the buffer layer obtained above was cut into 10cm × 10cm pieces, and the surface resistivity of the buffer layer was measured according to JIS K 6911:1995 using the double-ring electrode method (two-terminal method). The measuring apparatus used was an ADC R8252 digital electrometer and an Advantest TR42 sample chamber. It should be noted that the measurements were performed at 23°C and 50% RH, and the surface resistivity was calculated based on the current value when a 100V voltage was applied for 1 minute. Four measurements were performed for each substrate with the buffer layer, and the arithmetic mean of the four measurements was taken as the surface resistivity of the buffer layer.

[0324] [Determination of stripping electrostatic voltage]

[0325] The release sheet was peeled off from the workpiece processing adhesive sheet produced in the examples and comparative examples under an environment of 23°C, 50% RH (relative humidity), and the workpiece processing adhesive sheet was attached to the surface of a silicon wafer (mirror surface, 8 inches in diameter) using a backgrinding tape laminator (Lindberg Co., Ltd., trade name "RAD-3510", stage temperature: 23°C). The workpiece processing adhesive sheet was left to stand for 30 minutes under the same environment. The workpiece processing adhesive sheet was peeled off from the silicon wafer using a wafer taping machine (Lindberg Co., Ltd., product name "RAD-2700F / 12") under conditions of a peeling speed of 600 mm / min and a stage temperature of 40°C, and the voltage (maximum voltage at the time of peeling) was measured at a position 10 mm vertically apart from the surface of the silicon wafer using a peeling static voltage tester (Prostat Co., product name "PFM-711A"). Note that, in the measurement of the peeling static voltage, no static electricity removing device such as an ion generator was used. The arithmetic mean of the five measured values was taken as the peeling static voltage for each workpiece processing adhesive sheet. A sample having a peeling static voltage of 500 V or less was judged to be good.

[0326] [Grinding Evaluation: Backgrinding Processing]

[0327] The workpiece processing adhesive sheet produced in the examples and comparative examples was attached to a silicon wafer of 12 inches in diameter and 775 μm in thickness using a backgrinding tape laminator (Lindberg Co., Ltd., trade name "RAD3510F / 12") with the adhesive layer as the attachment surface. Subsequently, the silicon wafer was ground (including dry polishing) to a thickness of 30 μm using a backgrinding device (DISCO Corporation, trade name "DGP8761") in a state where the workpiece processing adhesive sheet was fixed. The appearance of the ground silicon wafer was observed with the naked eye, and the grindability in backgrinding processing was evaluated based on the following criteria.

[0328] A: No breakage of the silicon wafer was confirmed.

[0329] C: Breakage of the silicon wafer was confirmed.

[0330] [Grinding Evaluation: Stealth Dicing Processing]

[0331] The workpiece processing adhesive sheet produced in the examples and comparative examples was attached to a silicon wafer of 12 inches in diameter and 775 μm in thickness using a backgrinding tape laminator (Lindberg Co., Ltd., trade name "RAD3510F / 12") with the adhesive layer as the attachment surface. Subsequently, a lattice-shaped modified region was formed inside the silicon wafer using a laser saw (DISCO Corporation, trade name "DFL7361"). Note that the lattice size was set to 10 mm x 10 mm.

[0332] Next, the silicon wafer was ground (including dry polishing) using a backside grinding device (DISCO Corporation, trade name "DGP8761") until the thickness reached 30 μm, and the silicon wafer was singulated into a plurality of chips from the modified region described above as a starting point. Then, the workpiece processing adhesive sheet was subjected to energy ray (ultraviolet) irradiation. Next, a dicing tape (Lindberg Corporation, trade name "Adwill D-175D") was attached to the side of the plurality of chips opposite the adhesive surface of the workpiece processing adhesive sheet, and the workpiece processing adhesive sheet was peeled from the plurality of chips.

[0333] The plurality of chips after peeling of the workpiece processing adhesive sheet were observed with a digital microscope, and classified according to the size of each crack according to the following criteria, and the number of chips with cracks was counted, and the grinding properties in the stealth dicing process were evaluated based on the following criteria. Note that, for the size of the crack (μm), the length of the crack along the longitudinal direction of the chip (μm) was compared with the length of the crack along the lateral direction of the chip (μm), and the length with the larger value was set.

[0334] (Classification of cracks based on crack size)

[0335] Large crack: crack size greater than 20 μm

[0336] Medium crack: crack size 10 μm or more and less than 20 μm

[0337] Small crack: crack size less than 10 μm

[0338] (Evaluation criteria)

[0339] A: 0 large cracks, 7 or fewer medium cracks, and 15 or fewer small cracks

[0340] B: 0 large cracks, 8 or more and 10 or fewer medium cracks, and 15 or fewer small cracks, or 0 large cracks, 7 or fewer medium cracks, and 16 or more and 20 or fewer small cracks

[0341] C: 1 or more large cracks, or 11 or more medium cracks, or 21 or more small cracks

[0342] [Manufacture of adhesive composition]

[0343] Production Example 1

[0344] An acrylic polymer obtained by copolymerizing n-butyl acrylate (BA) 50 parts by mass, methyl methacrylate (MMA) 20 parts by mass, and 2-hydroxyethyl acrylate (2HEA) 30 parts by mass was reacted with 2-methacryloyloxyethyl isocyanate (MOI) in a manner that 80 mole% of the hydroxyl groups in the acrylic polymer were added to the hydroxyl groups. This resulted in an energy ray-curable acrylic polymer (Mw: 500,000). To 100 parts by mass of this energy ray-curable acrylic polymer, 10 parts by mass of a multifunctional urethane acrylate ultraviolet-curable compound (manufactured by Mitsubishi Chemical Corporation, product name "Rayglow UT-4332") as an energy ray-curable compound, 0.38 parts by mass of an isocyanate crosslinking agent (manufactured by Mitsui Chemicals, Inc., product name "TAKENATE D-101E") as a solid content, and 1 part by mass of bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide as a photopolymerization initiator were added, and the mixture was diluted with methyl ethyl ketone. This resulted in a coating agent for an adhesive composition having a solid content concentration of 34% by mass. The adhesive composition obtained in Production Example 1 is referred to as "Composition 1" in Table 1.

[0345] Production Example 2

[0346] An acrylic polymer obtained by copolymerizing 2-ethylhexyl acrylate (2EHA) 80 parts by mass and 2-hydroxyethyl acrylate (2HEA) 20 parts by mass was reacted with 2-methacryloyloxyethyl isocyanate (MOI) in a manner that 80 mole% of the hydroxyl groups in the acrylic polymer were added to the hydroxyl groups. This resulted in an energy ray-curable acrylic polymer (Mw: 500,000). To 100 parts by mass of this energy ray-curable acrylic polymer, 0.38 parts by mass of an isocyanate crosslinking agent (manufactured by Mitsui Chemicals, Inc., product name "TAKENATE D-101E") as a solid content, and 1 part by mass of bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide as a photopolymerization initiator were added, and the mixture was diluted with methyl ethyl ketone. This resulted in a coating agent for an adhesive composition having a solid content concentration of 30% by mass. The adhesive composition obtained in Production Example 2 is referred to as "Composition 2" in Table 1.

[0347] [Manufacture of adhesive sheet for workpiece processing]

[0348] Examples 1 to 8

[0349] (1) Production of substrate with buffer layer

[0350] As raw materials for the composition for forming a buffer layer, the raw materials shown below were prepared.

[0351] [Thermosetting resin]

[0352] Polyester urethane resin having 2 or more hydroxyl groups (manufactured by Toyobo Co., Ltd., trade name "UR-1400", glass transition temperature 83°C, number average molecular weight (Mn) 40,000, hydroxyl value 2 to 3 KOH mg / g, solvent (in which the content of methyl ethyl ketone is 50 mass%, and the content of toluene is 50 mass%) diluted product, solid content concentration 30 mass%)

[0353] <crosslinking agent>

[0354] Isocyanate-based crosslinking agent (manufactured by DKS Co., Ltd., trade name "CORONATE HL", acetic acid ethyl ester diluted product, solid content concentration 74 to 76 mass%)

[0355] <curing catalyst>

[0356] Dibutyltin dilaurate (manufactured by TOYO-CHEM Co., Ltd., trade name "BXX3778G")

[0357] <antistatic agent>

[0358] Ionic material 1: reaction product of alkanolamine and dialkyl succinate sulfonic acid, manufactured by Japan Emulsifier Co., Ltd., product name "AMINO ION AS400"

[0359] Ionic material 2: manufactured by Japan Carlit Co., Ltd., trade name "CIL-H11"

[0360] A thermosetting resin composition as a composition for forming a buffer layer was prepared by compounding 100 parts by mass of the above-described thermosetting resin, 7.5 parts by mass of the crosslinking agent, 0.5 parts by mass of the curing catalyst, and the antistatic agent of the kind and amount shown in Table 1.

[0361] Next, as a substrate, a polyethylene terephthalate (PET) film having a thickness shown in Table 1 was prepared, and the above-described obtained thermosetting resin composition was applied to one side of the substrate to form an applied film. Note that the thermosetting resin composition was adjusted in the amount of application so that the thickness of the buffer layer to be formed became the thickness described in Table 1. Next, the applied film was heated at 110°C for 2 minutes, whereby the organic solvent was dried, and a thermosetting reaction of the thermosetting resin composition was performed, and a substrate with a buffer layer in which a buffer layer having a thickness described in Table 1 was formed on one side of the substrate was obtained.

[0362] (2) Formation of adhesive layer

[0363] Next, the adhesive composition of the kind shown in Table 1 was applied to the release-treated surface of a release sheet (manufactured by Lindberg Corporation, trade name "SP-PET381031") so that the thickness after drying would be the thickness shown in Table 1, and then, heat drying was performed, to produce an adhesive layer-equipped release sheet.

[0364] Next, the adhesive layer of the adhesive layer-equipped release sheet was attached to the surface of the substrate opposite the buffer layer of the above-described buffer layer-equipped substrate, to obtain an adhesive sheet for workpiece processing with a release sheet, which successively has a buffer layer, a substrate, an adhesive layer, and a release sheet.

[0365] Comparative Example 1

[0366] In Example 1, an antistatic agent was not compounded in the buffer layer-forming composition, but otherwise, Example 1 likewise produced an adhesive sheet for workpiece processing with a release sheet.

[0367] Comparative Example 2

[0368] In Example 7, an antistatic agent was not compounded in the buffer layer-forming composition, but otherwise, Example 7 likewise produced an adhesive sheet for workpiece processing with a release sheet.

[0369] Comparative Example 3

[0370] In Example 8, an antistatic agent was not compounded in the buffer layer-forming composition, but otherwise, Example 8 likewise produced an adhesive sheet for workpiece processing with a release sheet.

[0371] Comparative Example 4

[0372] (1) Preparation of Buffer Layer-Forming Composition

[0373] An energy ray-curable resin composition as the buffer layer-forming composition was prepared by compounding 50 parts by mass of a urethane acrylate oligomer (manufactured by SARTOMER Co., trade name "CN8881") as an energy ray-curable compound, 50 parts by mass of polyethylene glycol (400) diacrylate, and 2.0 parts by mass of 2-hydroxy-2-methyl-l-phenylpropane-l-one (manufactured by IGM Resins Co., trade name "Omnirad 1173") as a photopolymerization initiator.

[0374] (2) Preparation of Adhesive Sheet

[0375] A coating film was formed by coating the energy ray-curable resin composition obtained above on a release-treated surface of a release sheet (manufactured by Lindberg Corporation, trade name "SP-PET381031"). Next, the energy ray-curable resin composition was semi-cured by irradiating the coating film with ultraviolet rays, and a layer of the energy ray-curable resin composition semi-cured to a thickness of 28 μm was formed on the release sheet.

[0376] Note that the ultraviolet irradiation described above was performed using a conveyer belt type ultraviolet irradiation device (manufactured by Eye Graphics, trade name "ECS-401GX") and a high-pressure mercury lamp (manufactured by Eye Graphics, trade name "H04-L41") under irradiation conditions of a lamp height of 260 mm, an output power of 80 W / cm, an illuminance of 70 mW / cm 2 , and an irradiation amount of 30 mW / cm 2 .

[0377] Next, the surface of the layer of the energy ray-curable resin composition semi-cured on the release sheet was attached to one side of a PET film (manufactured by Mitsubishi Resin, trade name "PET50 T910 WM19", thickness 50 μm) as a substrate. Next, the energy ray-curable resin composition was completely cured by irradiating the release sheet side with ultraviolet rays, and a substrate with a buffer layer having a buffer layer of 28 μm in thickness formed on one side of the substrate was obtained.

[0378] Note that the ultraviolet irradiation described above was performed using the ultraviolet irradiation device and the high-pressure mercury lamp under irradiation conditions of a lamp height of 210 mm, a lamp output power of 120 W / cm, an illuminance of 155 mW / cm 2 , and an irradiation amount of 600 mW / cm 2 .

[0379] Next, the adhesive layer of the release sheet with an adhesive layer prepared in the same manner as in Example 1 was attached to the side of the substrate of the substrate with a buffer layer opposite to the buffer layer, and a release sheet-equipped workpiece processing adhesive sheet sequentially having a buffer layer, a substrate, an adhesive layer, and a release sheet was obtained.

[0380] The evaluation results of the workpiece processing adhesive sheets obtained in each of the examples and comparative examples are shown in Table 1.

[0381]

[0382] As is apparent from Table 1, the adhesive sheets for workpiece processing of Examples 1 to 8 of the present embodiment sufficiently suppressed the peeling static voltage, and were excellent in odorlessness and grindability. On the other hand, the adhesive sheets for workpiece processing of Comparative Examples 1 to 3 in which the cushion layer did not contain an antistatic agent failed to sufficiently suppress the peeling static voltage. In addition, the adhesive sheet for workpiece processing of Comparative Example 4 in which the cushion layer was formed using an energy ray-curable resin composition was poor in odorlessness.

Claims

1. An adhesive sheet for workpiece processing, having a cushion layer, a base material, and an adhesive layer, the adhesive sheet for workpiece processing has the adhesive layer on one side of a surface, the cushion layer is a layer containing a cured product of a thermosetting resin composition, the thermosetting resin composition contains an antistatic agent.

2. The adhesive sheet for workpiece processing according to claim 1, wherein the antistatic agent is an ionic material.

3. The adhesive sheet for workpiece processing according to claim 1 or 2, wherein The surface resistivity of the buffer layer is 1.0 x 10 12 Ω / sq. or less.

4. The adhesive sheet for workpiece processing according to claim 1 or 2, wherein the thickness of the cushion layer is 2 to 100 μm.

5. The adhesive sheet for workpiece processing according to claim 1 or 2, wherein the thermosetting resin composition contains a polyester-based resin.

6. The adhesive sheet for workpiece processing according to claim 5, wherein the polyester-based resin is a polyester urethane resin.

7. The adhesive sheet for workpiece processing according to claim 5, wherein the polyester-based resin is a polyester-based resin having two or more hydroxyl groups, and the thermosetting resin composition further contains a polyisocyanate compound.

8. The adhesive sheet for workpiece processing according to claim 1 or 2, wherein the cushion layer is on one side of the base material, and the adhesive layer is on the other side of the base material.

9. The adhesive sheet for workpiece processing according to claim 1 or 2, which is used for grinding a workpiece.

10. The adhesive sheet for workpiece processing according to claim 1 or 2, which is used for singulating a workpiece into a plurality of workpiece singulates as follows, the workpiece has a groove on a surface, or has a modified region inside, a back surface of the workpiece is ground in a state where the adhesive sheet for workpiece processing attached to the surface of the workpiece is fixed, whereby the workpiece is singulated into a plurality of workpiece singulates with the groove or the modified region as a starting point.

11. A method for manufacturing an adhesive sheet for workpiece processing, which is a method for manufacturing the adhesive sheet for workpiece processing according to claim 1 or 2, the method having: a step of curing the thermosetting resin composition by heating.

12. A method for manufacturing an electronic device, the method comprising: a step of attaching the adhesive sheet for workpiece processing according to claim 1 or 2 to a surface of a workpiece with the adhesive layer as an attachment surface; and a step of grinding a back surface of the workpiece in a state where the adhesive sheet for workpiece processing attached to the workpiece is fixed.

13. A method for manufacturing an electronic device, the method comprising: a predetermined division line forming step, which is a step a of forming a groove on a surface of a workpiece, or a step b of forming a modified region inside the workpiece from a surface or a back surface of the workpiece; a sheet attaching step of attaching the adhesive sheet for workpiece processing according to claim 1 or 2 to the surface of the workpiece with the adhesive layer as an attachment surface after the step a, or before or after the step b; and A grinding and singulation process in which the back surface of the workpiece is ground in a state in which the adhesive sheet for workpiece processing, which is attached to the workpiece, is fixed, and the workpiece is singulated into a plurality of workpiece singulation products starting from the groove or the modified region. A grinding and singulation process in which the back surface of the workpiece is ground in a state in which the adhesive sheet for workpiece processing, which is attached to the workpiece, is fixed, and the workpiece is singulated into a plurality of workpiece singulation products starting from the groove or the modified region.

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