Adhesive sheet for fixing electronic components

Abstract

An adhesive sheet for fixing an electronic member having a base film and an adhesive layer formed on one side of the base film, and further having an antistatic layer containing an antistatic material on one side or both sides of the base film, wherein the antistatic layer has, on the other side of the base film, an outer antistatic layer containing an antistatic material and an outer protective layer in this order.

Description

Technology Field

[0001] The present invention relates to an adhesive sheet for fixing an electronic component used in a method for manufacturing an electronic component. Background Technology

[0002] Electronic components such as semiconductor wafers or package substrates (hereinafter simply referred to as "electronic components") are transferred to various processes such as bonding to an adhesive sheet for fixing electronic components, cutting into small component pieces (dicing), stretching of the adhesive sheet (expanding), and peeling off small component pieces from the adhesive sheet (picking up) after forming a circuit. The adhesive sheet (dicing tape) used in these processes is required to have sufficient adhesive strength against the small component pieces (chips) being cut during dicing, and to have reduced adhesive strength so that no adhesive remains during pickup.

[0003] In recent years, along with the miniaturization and thinning of electronic components, chip sizes have been shrinking. Consequently, chip scattering and chipping (chip loss) are more likely to occur during the dicing process of semiconductor wafers or substrates, becoming one of the factors contributing to yield reduction. Furthermore, during the pickup process, cracks may occur in the adhesive layer of the adhesive sheet due to the pushing motion of the needle pins. If cracks occur in the adhesive layer, the cracked adhesive adheres to the chip (residue), causing contamination or defects in the mounting process.

[0004] In order to solve the problems described above, various adhesive tapes have been developed that improve chip scattering and chipping suppression in the dicing process (e.g., see Patent Document 1 below). Prior art literature

[0005] International Publication WO2017 / 18270 The problem to be solved

[0006] However, excellent antistatic properties are a required performance characteristic of adhesive sheets for fixing electronic components. If static electricity accumulates on the adhesive sheet, it not only adversely affects electronic components such as semiconductor wafers but also contaminates the electronic components by adsorbing surrounding dust or cutting debris generated during dicing. Therefore, various treatments are applied to the adhesive sheet to suppress the impact of static electricity on the electronic components. Such treatments include, for example, applying an antistatic treatment to the substrate film of the adhesive sheet to lower the surface resistance of the sheet, or applying an antistatic layer containing an antistatic agent.

[0007] However, when an antistatic layer is formed on a substrate film, a portion of the layer may be lost due to various factors, such as vibrations or changes in the sheet shape during dicing, expanding, or pickup. If the antistatic layer is lost, the desired surface resistance reduction effect cannot be achieved, or the detached fragments of the layer may become debris and cause contamination.

[0008] In particular, if the antistatic layer comes into contact with other components and is damaged during handling of the adhesive sheet, it is presumed that the likelihood of the antistatic layer detaching during handling or dicing increases.

[0009] To solve the aforementioned problem, the present invention aims to provide an adhesive sheet for fixing electronic components that has low contamination of electronic components and excellent surface resistance reduction effect. means of solving the problem

[0010] To solve the above problem, the present invention employs the following means.

[0011] <1> An adhesive sheet for fixing an electronic member having a base film and an adhesive layer formed on one side of the base film, and further having an antistatic layer comprising an antistatic material on one side or both sides of the base film.

[0012] An adhesive sheet for fixing electronic components having, on the other side of the above-described film, an outer antistatic layer and an outer protective layer in this order as the antistatic layer.

[0013] <2> The surface resistance of at least one surface is 1×10 7 The above, which is Ω / □ or less <1> Adhesive sheet for fixing electronic components as described in

[0014] <3> The antistatic material included in the outer antistatic layer is at least one of carbon nanotubes, metal oxides, polythiophene, polyaniline, and polypyrrole, the <1> or <2> Adhesive sheet for fixing electronic components as described in

[0015] <4> Between the above-mentioned film and the above-mentioned adhesive layer, the above-mentioned inner antistatic layer as the antistatic layer further comprises <1> inside <3> An adhesive sheet for fixing electronic components as described in any of the above.

[0016] <5> The antistatic material included in the inner antistatic layer is at least one of carbon nanotubes, metal oxides, polythiophene, polyaniline, and polypyrrole, the <4> Adhesive sheet for fixing electronic components as described in

[0017] <6> The inner protective layer further having an inner protective layer between the adhesive layer and the inner antistatic layer, the <4> or <5> Adhesive sheet for fixing electronic components as described in

[0018] <7> The above-described film comprises at least one selected from polyolefin resins, polyester resins, and copolymers thereof, the above <1> inside <6> An adhesive sheet for fixing electronic components as described in any one of the following.

[0019] <8> The above adhesive layer comprises an acrylic adhesive, <1> inside <7> An adhesive sheet for fixing electronic components as described in any of the above.

[0020] <9> The above adhesive layer comprises a UV-curing resin composition, <1> inside <8> An adhesive sheet for fixing electronic components as described in any of the above. Effects of the invention

[0021] According to the present invention, an adhesive sheet for fixing electronic components can be provided that has low contamination of the electronic components and excellent surface resistance reduction effect. Brief explanation of the drawing

[0022] FIG. 1 is a cross-sectional view showing an example of the composition of an adhesive sheet of the present embodiment. Specific details for implementing the invention

[0023] Preferred embodiments for carrying out the present invention are described below. Furthermore, the embodiments described below represent examples of representative embodiments of the present invention, and the scope of the present invention should not be interpreted narrowly by such embodiments.

[0024] Adhesive Sheet for Fixing Electronic Components

[0025] The adhesive sheet for fixing electronic components of the present embodiment (hereinafter simply referred to as "adhesive sheet") has a base film and an adhesive layer formed on one side of the base film (hereinafter referred to as "adhesive side"), and further has an antistatic layer containing an antistatic material on one side or both sides of the base film, and on the other side of the base film (hereinafter referred to as "outer side"), has an outer antistatic layer and an outer protective layer in this order as the antistatic layer. In addition, in the present embodiment, as described below, a layer (e.g., protective layer, antistatic layer) formed between the base film and the adhesive layer on one side of the base film (adhesive side) is respectively referred to as an "inner protective layer" and an "inner antistatic layer."

[0026] In addition, the outer antistatic layer and the inner antistatic layer may be collectively referred to simply as the "antistatic layer." Likewise, the outer protective layer and the inner protective layer may be collectively referred to simply as the "protective layer."

[0027] <Composition>

[0028] The layer composition of the adhesive sheet of the present embodiment is described using FIG. 1. FIG. 1 is a cross-sectional view showing an example of the composition of the adhesive sheet of the present embodiment. Common components in each composition are described using common numbers.

[0029] As described above, the adhesive sheet of the present embodiment has at least an adhesive layer on the adhesive side of the base film, and on the other side (outer side) of the base film, at least an outer antistatic layer and an outer protective layer in this order. That is, as shown in (A) of FIG. 1, the adhesive sheet (100) has a base film (20), and an adhesive layer (30) is formed on one side (adhesive side: above the ground), and an outer antistatic layer (40) and an outer protective layer (50) are formed on the other side (outer side: below the ground).

[0030] According to the adhesive sheet of the present embodiment, since an outer antistatic layer is formed on the substrate film, the surface resistance value of the adhesive sheet surface, particularly the outermost surface, can be lowered.

[0031] Meanwhile, the outer antistatic layer is prone to defects, such as cracks, caused by contact during the handling of the substrate film or adhesive sheet, physical impact from vibrations during the dicing process, or forces resulting from changes in the sheet's shape during substrate picking. In particular, cracks in the antistatic layer are more likely to occur when carbon nanotubes or metal oxides are included as antistatic materials. Furthermore, if the antistatic layer comes into contact with other components and is damaged during the handling of the substrate film or adhesive sheet, the likelihood of defects occurring in the antistatic layer increases. If defects occur in the antistatic layer in this manner, the desired surface resistance reduction effect may not be achieved, or fragments of the detached antistatic layer may become debris and cause contamination.

[0032] In contrast, the outer antistatic layer of the adhesive sheet of the present embodiment has an outer protective layer formed on the outer side of the substrate film. Therefore, the adhesive sheet of the present embodiment can prevent the antistatic layer from coming into contact with other members and receiving damage, etc., when handling the substrate film, etc., and additionally, can prevent the antistatic layer from detaching even if cracks, etc. occur in the antistatic layer due to vibration or shape change of the sheet during dicing, expanding, or picking.

[0033] The adhesive sheet of the present embodiment may have an inner antistatic layer containing an antistatic material between the base film and the adhesive layer. In this case, as shown in (B) of FIG. 1, the adhesive sheet (200) has a base film (20), and on one side (adhesive side: above the ground), an inner antistatic layer (42) and an adhesive layer (30) are formed in this order, and on the other side (outer side: below the ground), an outer antistatic layer (40) and an outer protective layer (50) are formed.

[0034] For example, it is presumed that the surface resistance value [Ω / □] of the adhesive surface is also related as a factor in chip scattering or chipping during the dicing process. If the surface resistance value of the adhesive layer increases, the adhesive layer may not be able to exert the desired adhesive force, which can cause chip scattering. However, if an inner antistatic layer is formed between the substrate film and the adhesive layer, the surface resistance value on the adhesive surface of the adhesive sheet can be effectively reduced in addition to the outermost surface, thereby suppressing chip scattering or chipping during the dicing process.

[0035] In addition, by reducing the surface resistance value on the adhesive surface of the adhesive sheet, compared to conventional adhesives and adhesive sheets with antistatic properties, the suppression effect of charge (peel-off charge) during chip peeling is improved and the stabilization of adhesive strength is excellent, so it is possible to produce an adhesive sheet with less contamination of electronic components (transfer of adhesive when peeling off electronic components after attaching them).

[0036] In addition, although not specifically limited, when manufacturing an adhesive sheet having an inner antistatic layer such as an adhesive sheet (200), a substrate film having antistatic layers formed on both sides in advance may be used. In this case, from the perspective of preventing damage to the antistatic layer during handling, it is preferable that a protective layer be formed not only on the outer antistatic layer but also on the antistatic layer corresponding to the inner antistatic layer.

[0037] For example, when producing an adhesive sheet (200) using a base film having an antistatic layer and a protective layer on both sides, the adhesive sheet (200) can be produced by removing only the protective layer on one side from the base film and forming an adhesive layer on the removed surface.

[0038] Meanwhile, when manufacturing an adhesive sheet using a substrate film having an antistatic layer and a protective layer on both sides, the adhesive layer may be formed on the side (inner side) where the adhesive layer is formed without removing the protective layer, for the sake of improving manufacturing efficiency. That is, the adhesive sheet of the present embodiment may additionally have an inner protective layer between the adhesive layer and the inner antistatic layer, in addition to the inner antistatic layer.

[0039] In this case, as shown in (C) of FIG. 1, the adhesive sheet (300) is provided with a substrate film (20), and on one side (adhesive side: above the ground), an inner antistatic layer (42), an inner protective layer (52), and an adhesive layer (30) are formed in this order, and on the other side (outer side: below the ground), an outer antistatic layer (40) and an outer protective layer (50) are formed.

[0040] In addition, each adhesive sheet may have a peelable protective film, etc., to protect the adhesive surface of the adhesive layer during handling, although the illustration is omitted.

[0041] In addition, regarding the layer configuration described above, examples in which the antistatic layer and the protective layer are manufactured separately are explained, but the boundary between the antistatic layer and the protective layer does not necessarily have to be clear. For example, the antistatic layer and the protective layer may be formed integrally. In this case, by adjusting the distribution concentration of the antistatic material in the thickness direction of the layer to increase the content of the antistatic material on the substrate side and decrease (preferably 0) the content of the antistatic layer near the outer surface, a layer having the functions of an antistatic layer and a protective layer can be formed.

[0042] The materials constituting each layer, etc., are described below.

[0043] <Insulated Film>

[0044] As for the base film, there are no particular limitations, but sheets made of various synthetic resins used for manufacturing electronic components may be used. As for the material of the base film, there are no particular limitations, but at least one type selected from polyolefin resins, polyester resins, and copolymers thereof may be used. Specifically, examples include polyvinyl chloride, polyethylene terephthalate, ethylene-vinyl acetate copolymer, ethylene-acrylic acid-acrylic acid ester film, ethylene-ethyl acrylate copolymer, polyethylene, polypropylene, propylene copolymer, ethylene-acrylic acid copolymer, and ionomer resins in which metal ions are bonded to ethylene-(meth)acrylic acid copolymer or ethylene-(meth)acrylic acid-(meth)acrylic acid ester copolymer, etc. The base film may be a mixture or copolymer of these resins.

[0045] As for the above ionomer resin, in terms of suppressing cutting chips during dicing, Na in a copolymer having ethylene units, (meth)methacrylic acid units and (meth)acrylic acid alkyl ester units + , K + , Zn 2+ Ionomer resins bonded with metal ions such as the above can be suitably used.

[0046] The molding method of the base film is not particularly limited and may include, for example, calendering, T-die extrusion, inflation, and casting.

[0047] The base film may be a single-layer or multi-layer film or sheet containing the above-described material, or it may be a laminate of a film containing other materials. The thickness of the base film is preferably 50 to 200 μm, and more preferably 70 to 150 μm.

[0048] The substrate film may be subjected to an antistatic treatment. Examples of antistatic treatments include incorporating an antistatic material into the substrate film or treatment by corona discharge.

[0049] <Adhesive layer>

[0050] The adhesive layer is a layer that serves to fix electronic components, such as semiconductor wafers or package substrates, to which they are bonded during the dicing process. The adhesive included in the adhesive layer is not particularly limited, but examples include rubber-based adhesives, acrylic-based adhesives, urethane-based adhesives, and silicone-based adhesives. In this embodiment, since a UV-curing adhesive layer is preferred, it is preferable to use an acrylic-based adhesive. The UV-curing adhesive layer is cured by UV light irradiation. When the adhesive layer is cured, the elastic modulus of the layer increases, so its adhesive strength decreases, and the adhesive layer itself undergoes a shape change (shrinkage). Therefore, if UV light is irradiated onto the adhesive layer after dicing, the chip can be easily peeled off due to the decrease in adhesive strength. Examples of UV-curing resin compositions using an acrylic adhesive include a (meth)acrylic acid ester copolymer, a photopolymerizable compound, a curing agent, and a photopolymerization initiator.

[0051] -Acrylic adhesive-

[0052] As for acrylic adhesives, there are no particular limitations, but examples include acrylic acid ester polymers. Here, in this specification, compounds containing (meth) such as (meth)acrylic acid are a general term for compounds having "meth" in their names and compounds not having "meth."

[0053] Examples of (meth)acrylic acid ester copolymers include polymers formed by polymerizing monomers having carboxyl groups such as (meth)acrylic acid and their ester monomers, and copolymers formed by copolymerizing unsaturated monomers capable of copolymerizing with these monomers (e.g., vinyl acetate, styrene, acrylonitrile).

[0054] Examples of monomers having a carboxyl group include methacrylic acid, crotonic acid, maleic acid, itaconic acid, fumaric acid, acrylamide N-glycolic acid, and cinnamic acid, and methacrylic acid is preferred. Acrylic acid is particularly preferred because it allows for more precise control of adhesive strength by containing a curing agent.

[0055] Examples of ester monomers for (meth)acrylate polymers include butyl (meth)acrylate, 2-butyl (meth)acrylate, t-butyl (meth)acrylate, pentyl (meth)acrylate, octyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, nonyl (meth)acrylate, decyl (meth)acrylate, lauryl (meth)acrylate, methyl (meth)acrylate, ethyl (meth)acrylate, isopropyl (meth)acrylate, tridecyl (meth)acrylate, myristyl (meth)acrylate, cetyl (meth)acrylate, stearyl (meth)acrylate, cyclohexyl (meth)acrylate, benzyl (meth)acrylate, etc.

[0056] The weight average molecular weight of the (meth)acrylic acid ester polymer is preferably 200,000 to 2,000,000 in order to prevent chipping during dicing by suppressing the excessive decrease and increase in elastic modulus.

[0057] (Photopolymerizable compound)

[0058] As for the photopolymerizable compound, there are no particular limitations, but for example, a urethane acrylate oligomer can be used. The urethane acrylate oligomer is obtained by reacting a polyvalent isocyanate having an acryloyloxy group or a methryloyloxy group with a (meth)acrylate having a hydroxyl group.

[0059] Polyvalent isocyanate compounds used include, for example, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, 1,3-xylene diisocyanate, 1,4-xylene diisocyanate, diphenylmethane 4,4-diisocyanate, trimethylhexamethylene diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, etc.

[0060] In addition, (meth)acrylates having hydroxyl groups are used, for example, 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, polyethylene glycol (meth)acrylate, pentaerythritol triacrylate, glycidol di(meth)acrylate, dipentaerythritol monohydroxypentaacrylate, etc.

[0061] The content of the photopolymerizable compound in the adhesive layer is not particularly limited, but from the perspective of avoiding the occurrence of semiconductor chip pickup failures due to reduced peelability of the adhesive sheet after light irradiation or adhesive cracking during the pickup process caused by an excessive increase in the elastic modulus of the adhesive during the light irradiation process, it is preferable to have 20 to 150 parts by mass and 50 to 120 parts by mass per 100 parts by mass of (meth)acrylic acid ester copolymer.

[0062] The photopolymerizable compound is not particularly limited, but from the perspective of preventing adhesive residue from forming on chips when the adhesive is scraped up during dicing or curing the adhesive after irradiation with ultraviolet rays, it is preferable that the weight average molecular weight be 500 to 100,000, and it is preferable that it have at least one of an acryloyl group and a methryloyl group, and a total of 4 to 10.

[0063] (Hardening agent)

[0064] Examples of curing agents include polyfunctional isocyanate curing agents, polyfunctional epoxy curing agents, azirin compounds, melamine compounds, etc.

[0065] Polyfunctional isocyanate curing agents include, for example, aromatic polyisocyanate curing agents, aliphatic polyisocyanate curing agents, and cycloaliphatic polyisocyanate curing agents, and are generally used as adduct types in the form of dimers or more.

[0066] Aromatic polyisocyanates are not particularly limited and, for example, 1,3-phenylene diisocyanate, 4,4'-diphenyl diisocyanate, 1,4-phenylene diisocyanate, 4,4'-diphenylmethane diisocyanate, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, 4,4'-toluidine diisocyanate, 2,4,6-triisocyanate toluene, 1,3,5-triisocyanate benzene, dianisidine diisocyanate, 4,4'-diphenyl ether diisocyanate, 4,4',4'-triphenylmethane triisocyanate, ω,ω'-diisocyanate-1,3-dimethylbenzene, ω,ω'-diisocyanate-1,4-dimethylbenzene, Examples include ω,ω'-diisocyanate-1,4-diethylbenzene, 1,4-tetramethylxylylene diisocyanate, and 1,3-tetramethylxylylene diisocyanate.

[0067] Aliphatic polyisocyanates are not particularly limited and examples include trimethylene diisocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate, pentamethylene diisocyanate, 1,2-propylene diisocyanate, 2,3-butylene diisocyanate, 1,3-butylene diisocyanate, dodecamethylene diisocyanate, and 2,4,4-trimethylhexamethylene diisocyanate.

[0068] Cyclocyclopolyisocyanates are not particularly limited and include, for example, 3-isocyanatomethyl-3,5,5-trimethylcyclohexylisocyanate, 1,3-cyclopentanediisocyanate, 1,3-cyclohexanediisocyanate, 1,4-cyclohexanediisocyanate, methyl-2,4-cyclohexanediisocyanate, methyl-2,6-cyclohexanediisocyanate, 4,4'-methylenebis(cyclohexylisocyanate), 1,4-bis(isocyanatomethyl)cyclohexane, and 1,4-bis(isocyanatomethyl)cyclohexane.

[0069] Among polyisocyanates, 1,3-phenylene diisocyanate, 4,4'-diphenyl diisocyanate, 1,4-phenylene diisocyanate, 4,4'-diphenylmethane diisocyanate, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, 4,4'-toluidine diisocyanate, and hexamethylene diisocyanate are suitably used.

[0070] Polyfunctional epoxy curing agents are compounds that mainly have two or more epoxy groups and one or more tertiary nitrogen atoms, and examples include N·N-glycidylaniline, N·N-glycidyltoluidine, mN·N-glycidylaminophenylglycidyl ether, pN·N-glycidylaminophenylglycidyl ether, triglycidyl isocyanurate, N·N·N'·N'-tetraglycidyldiaminodiphenylmethane, N·N·N'·N'-tetraglycidyl-m-xylylenediamine, N·N·N'·N'·N"-pentaglycidyldiethylenetriamine, etc.

[0071] The content of the curing agent in the adhesive layer is preferably 1 to 20 parts by mass and more preferably 1.5 to 15 parts by mass per 100 parts by mass of the (meth)acrylic acid ester copolymer, in order to suppress the occurrence of adhesive residue or insufficient adhesive strength.

[0072] (Photopolymerization initiator)

[0073] As photopolymerization initiators, benzoin, benzoin alkyl ethers, acetophenones, anthraquinones, thioxantones, ketals, benzophenones, or xantones are used.

[0074] Examples of benzoin include benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin propyl ether, etc.

[0075] Examples of acetophenones include benzoin alkyl ethers, acetophenone, 2,2-dimethoxy-2-acetophenone, 2,2-diethoxy-2-acetophenone, 1,1-dichloroacetophenone, etc.

[0076] Examples of anthraquinones include 2-methylanthraquinone, 2-ethylanthraquinone, 2-tert-butylanthraquinone, 1-chloroanthraquinone, etc.

[0077] Examples of thioxanthones include 2,4-dimethylthioxanthon, 2,4-diisopropylthioxanthon, 2-chlorothioxanthon, 2,4-diisopropylthioxanthon, etc.

[0078] Examples of ketals include acetophenone dimethyl ketal, benzyl dimethyl methyl, benzyl diphenyl sulfide, tetramethylthiuram monosulfide, azobis isobutyronitrile, dibenzyl, diacetyl, β-chloranthraquinone, etc.

[0079] The content of the photopolymerization initiator in the adhesive layer is 1 to 15 parts by mass per 100 parts by mass of (meth)acrylic acid ester polymer, and 1.5 to 10 parts by mass is more preferable, from the perspective of preventing peelability from the adhesive sheet after light irradiation or bleed-out of the photopolymerization initiator to the surface of the adhesive layer.

[0080] As needed, one or more conventionally known photopolymerization promoters may be used in combination with the photopolymerization initiator. Benzoic acid-based or tertiary amines may be used as photopolymerization promoters. Examples of tertiary amines include triethylamine, tetraethylpentaamine, and dimethylamino ether.

[0081] In the adhesive layer, as a tackifying resin, a terpene phenol resin that is completely or partially hydrogenated may be added.

[0082] In addition, various additives such as softeners, anti-aging agents, fillers, conductive agents, UV absorbers, and light stabilizers may be added to the adhesive layer as needed.

[0083] The thickness of the adhesive layer is not particularly limited, but from the perspective of securing adhesive strength to support chip retention during dicing or preventing chipping caused by the thickness of the adhesive layer, 1 to 50 μm is preferred, and 5 to 30 μm is more preferred.

[0084] In addition, the adhesion force between the adhesive layer and the immediately below member, for example between the adhesive layer and the substrate film, between the adhesive layer and the inner antistatic layer, and between the adhesive layer and the inner protective layer (anchor force [unit: N / 20 mm]), is not particularly limited, but in terms of adhesive residue after tape peeling, it is preferable that it be 1 N / 20 mm or more, and more preferable that it be 6 N / 20 mm or more. The said anchor force can be measured by the method described in the example.

[0085] Anti-Damage Layer

[0086] The antistatic layer is a layer containing an antistatic material. In this embodiment, as described above, an inner antistatic layer may be formed in addition to the outer antistatic layer.

[0087] As for the antistatic material, there are no particular limitations, but at least one of carbon nanotubes, metal oxides, polythiophene, polyaniline, and polypyrrole is preferred. As for the carbon nanotubes, metal oxides, polythiophene, polyaniline, and polypyrrole, any known materials used as antistatic materials (conductive materials) may be appropriately selected and used without particular limitations. Furthermore, among these antistatic materials, carbon nanotubes are particularly preferred from the perspective of antistatic effect.

[0088] The same antistatic material may be used for the outer antistatic layer and the inner antistatic layer, and both layers may be formed of the same material or may be formed using different materials.

[0089] Carbon nanotubes (hereinafter simply referred to as “CNT”) may be either single-layer carbon nanotubes (SWCNT) or multi-layer carbon nanotubes (MWCNT).

[0090] MWCNT is configured such that tubes containing multiple cylindrical carbon walls of different diameters are stacked in multiple layers around a central axis, and the carbon walls are formed in multiple layers in a hexagonal carbon mesh structure or a spiral shape. For MWCNT, it is preferable that the carbon walls are stacked in 2 to 30 layers, and more preferable that they are stacked in 2 to 15 layers.

[0091] In addition, carbon nanotubes may be dispersed individually within the antistatic layer, or may be dispersed in a bundled state.

[0092] In the antistatic layer, a binder may be used together with an antistatic material such as carbon nanotubes.

[0093] The binder is not particularly limited, but examples include (meth)acrylic acid ester-based polymers, acrylic polymers, urethane polymers, polyester polymers, epoxy polymers, polyvinyl chloride polymers, melamine polymers, polyimide polymers, and silicone polymers, and (meth)acrylic acid ester-based polymers are preferred. Examples of (meth)acrylic acid ester-based polymers include those similar to the (meth)acrylic acid ester-based polymer used in the adhesive layer described above.

[0094] When a binder is used, the content of carbon nanotubes, etc. in the antistatic layer is not particularly limited, but from the perspective of the strength of the antistatic layer (e.g., crack resistance), adhesion to the substrate film, and sufficient antistatic effect, the content of carbon nanotubes in the antistatic layer after drying can be, for example, about 5 to 20 mg / m², preferably 7 to 11 mg / m².

[0095] The antistatic layer may include known antistatic materials (e.g., dimethylaminoethyl (meth)acrylate quaternary chloride, diethylaminoethyl (meth)acrylate quaternary chloride, methylethylaminoethyl (meth)acrylate quaternary chloride, p-dimethylaminostyrene quaternary chloride, and p-diethylaminostyrene quaternary chloride, etc.) to the extent that it does not impede the effects of the present invention.

[0096] In addition to the antistatic layer, various additives, such as curing agents, plasticizers, anti-aging agents, fillers, etc., may be appropriately added as needed, to the extent that they do not impede the effects of the present invention.

[0097] The method of forming the antistatic layer is not particularly limited and may include, for example, a method of applying it directly onto a substrate film using a coater such as a gravure coater, bar coater, knife coater, or roll coater, or a method of printing using relief printing, intaglio printing, flatbed printing, flexographic printing, offset printing, or screen printing.

[0098] The thickness of the outer antistatic layer is not particularly limited, but from the perspective of the strength of the antistatic layer (e.g., crack resistance), adhesion to the substrate film, and sufficient antistatic effect, it is preferably 0.01 to 1 μm, and more preferably 0.02 to 0.2 μm.

[0099] In addition, although the thickness of the inner antistatic layer is not particularly limited, from the perspective of the strength of the antistatic layer (e.g., crack resistance), adhesion to the substrate film, and sufficient antistatic effect, it is preferably 0.01 to 1 μm, and more preferably 0.02 to 0.2 μm.

[0100] <Protection Layer>

[0101] The protective layer is a layer formed to protect the antistatic material. In this embodiment, as described above, an inner protective layer may be formed in addition to the outer protective layer. Furthermore, the outer protective layer is a layer primarily intended to prevent the antistatic layer from detaching during the dicing process. In addition, both the inner layer and the outer protective layer can further prevent the detachment of the antistatic layer by suppressing damage, such as physical impact during contact, when handling the substrate film. Furthermore, the adhesive sheet for electronic components equipped with an inner protective layer exhibits excellent adhesion retention of the adhesive layer even when stored for a certain period of time under conditions of relatively high temperature.

[0102] In addition, it is desirable that the protective layer does not have adhesive properties. Here, "not having adhesive properties" means that it is desirable that the probe tack (in accordance with ASTM D 2979) is 0.1 N / 20 mm² or less.

[0103] The outer protective layer and the inner protective layer may be layers formed from the same material, or layers formed using different materials. When the inner protective layer and the outer protective layer are formed from different materials, it is preferable that at least the outer protective layer does not have adhesive properties.

[0104] There are no particular limitations on the material (binder) constituting the outer protective layer, but examples include (meth)acrylic acid ester-based polymers, acrylic-based polymers, urethane-based polymers, polyester-based polymers, epoxy-based polymers, polyvinyl chloride-based polymers, melamine-based polymers, polyimide-based polymers, and silicone-based polymers, and (meth)acrylic acid ester-based polymers are preferred. As for the (meth)acrylic acid ester-based polymer, the (meth)acrylic acid ester-based polymer used in the adhesive layer described above may be used.

[0105] Although there are no specific limitations on the material (binder) constituting the inner protective layer, it is preferable to use water-based olefin resins or acrylic polymers when considering adhesion to the adhesive layer formed by a UV-curing resin containing an acrylic adhesive. Although the reason why the adhesion to the adhesive layer is improved by using these resins in the inner protective layer is not clear, it is presumed to be due to the interaction between the functional groups (hydroxyl groups, carboxylic acid groups, epoxy groups, isocyanate groups, etc.) on the surface of the inner protective layer and the functional groups (hydroxyl groups, carboxylic acid groups) contained in the adhesive, or due to the chemical bonding between the isocyanate groups contained in the adhesive and the hydroxyl or carboxylic acid groups.

[0106] The above acrylic polymer is not particularly limited, but may include polymethic acid ester, polyacrylic acid ester, sodium polyacrylate, polyacrylonitrile, and polyacrylamide, and specifically, methyl polymethicate is preferred.

[0107] In addition, a friction reducing agent may be used in the protective layer (particularly the outer protective layer). Using a friction reducing agent can reduce the friction coefficient between the adhesive sheet and the expand device. Examples of friction reducing agents include silicone compounds such as silicone resin or (modified) silicone oil, fluoropolymer, hexagonal boron nitride, carbon black, and molybdenum disulfide; however, silicone-based graft copolymers are preferred in terms of good compatibility with the antistatic layer and the balance of antistatic and expandability properties.

[0108] Examples of silicone-based graft copolymers include a monomer having a vinyl group, such as a (meth)acryloyl group or a styryl group, at the end of a silicone molecular chain (hereinafter referred to as a "silicone-based monomer") and a vinyl polymer formed by polymerizing a (meth)acrylic monomer, a monomer having a vinyl group such as styrene, etc. (e.g., see Japanese Patent Publication No. 2000-080135, etc.).

[0109] The amount of friction reducing agent in the outer protective layer is not particularly limited, but from the viewpoint of sufficiently expanding the adhesive sheet and not impairing the antistatic effect, it is preferable to have 0.005 to 10 parts by mass per 100 parts by mass of binder.

[0110] In the protective layer, various additives, such as curing agents, plasticizers, anti-aging agents, fillers, etc., may be appropriately added as needed, to the extent that they do not impede the effects of the present invention.

[0111] The method of forming the protective layer is not particularly limited and may include, for example, a method of applying directly onto a substrate film using a coater such as a gravure coater, bar coater, knife coater, or roll coater, or a method of printing using relief printing, intaglio printing, flatbed printing, flexographic printing, offset printing, or screen printing. As a method for forming the protective layer, a method using a gravure coater is particularly preferred.

[0112] The thickness of the outer protective layer is not particularly limited, but from the perspective of the strength of the protective layer and the antistatic effect, 0.1 to 5 μm is preferred, and 0.5 to 2 μm is more preferred.

[0113] In addition, the thickness of the inner protective layer is not particularly limited, but from the perspective of the strength of the protective layer and the antistatic effect, 0.1 to 5 μm is preferred, and 0.5 to 2 μm is more preferred.

[0114] The outer protective layer is preferably the outermost layer on the outside of the adhesive sheet. Embossing may be performed on the surface of the outermost layer of the adhesive sheet. By performing the embossing, it is possible to make the surface of the outer protective layer an embossed surface, for example, with an average surface roughness (Ra) of 0.3 to 1.5 μm. When embossing is performed on the surface of the outermost layer of the adhesive sheet, the embossed surface of the adhesive sheet is positioned on the machine table side of the expand device, thereby allowing the substrate film to be easily expanded during the expand process after dicing.

[0115] Surface Resistance Value

[0116] The surface resistance value of the adhesive sheet of the present embodiment can be measured using an electrometer, for example, in accordance with JIS-K6911. The adhesive sheet of the present embodiment has a surface resistance value of 1×10 on at least one surface. 7 It is desirable that it be Ω / □ or less.

[0117] Specifically, the surface resistance value of the outermost surface of the adhesive sheet is not particularly limited, but from the perspective of suppressing peeling charge of the tape, it is 1×10⁻⁶ 7 It is desirable for Ω / □ or less.

[0118] In addition, the surface resistance value of the adhesive side (adhesive layer) of the adhesive sheet is not particularly limited, but from the perspective of suppressing peeling charge of the tape, it is 1×10⁻⁶ 10 It is desirable for Ω / □ or less.

[0119] Method for manufacturing an adhesive sheet

[0120] The method of manufacturing the adhesive sheet of the present embodiment is not particularly limited, and each layer on the substrate film can be manufactured using the method described above. For example, in the case of the adhesive sheet (100) in (A) of FIG. 1, it can be manufactured by forming an antistatic layer and a protective layer in this order on only one side of the substrate film, and forming an adhesive layer on the opposite side.

[0121] In addition, when using the film described above, an inner antistatic layer is formed before forming the adhesive layer, and an adhesive layer is formed thereon, thereby producing the adhesive sheet (200) of (B) in FIG. 1.

[0122] Additionally, the adhesive sheet (200) can also be manufactured by using a substrate film having an antistatic layer and a protective layer on both sides, removing the protective layer on only one side, and forming an adhesive layer on the removed surface.

[0123] In addition, by using a substrate film having an antistatic layer and a protective layer on both sides and forming an adhesive layer on one of the protective layers, the adhesive sheet (300) of (C) in FIG. 1 can be produced.

[0124] As described above, the adhesive sheet of the present embodiment may have a peelable protective film on the adhesive layer. Additionally, the adhesive sheet of the present embodiment may have other layers between each layer as long as it does not impede the effects of the present invention, but from the perspective of the adhesion of each layer, it is preferable to have each adhesive sheet shown in (A) to (C) of FIG. 1, and an adhesive sheet laminated so that each layer is in direct contact.

[0125] Method for manufacturing electronic components

[0126] The method for manufacturing an electronic component using the adhesive sheet of the present embodiment is not particularly limited, but, for example, a manufacturing method including the following steps may be cited.

[0127] (1) Attachment process

[0128] In the attachment process, an adhesive sheet is attached to an electronic component, such as a semiconductor wafer or a package substrate, and to a ring frame. The semiconductor wafer may be a conventional general-purpose wafer, such as a silicon wafer, a gallium nitride wafer, a silicon carbide wafer, or a sapphire wafer. The package substrate may be a general-purpose substrate, such as a package substrate in which a chip is sealed with resin, an LED package substrate, or a ceramic substrate.

[0129] (2) Dicing process

[0130] In the dicing process, electronic components such as silicon wafers are diced to form semiconductor chips or semiconductor parts.

[0131] (3) Light irradiation process

[0132] In the light irradiation process, active light such as ultraviolet rays is irradiated from the substrate film side onto a photocurable adhesive layer. As a light source for ultraviolet rays, low-pressure mercury lamps, high-pressure mercury lamps, ultra-high-pressure mercury lamps, metal halide lamps, and black lights may be used. In addition, electron beams may be used instead of ultraviolet rays, and as a light source for electron beams, alpha rays, beta rays, and gamma rays may be used.

[0133] When irradiated with light, the adhesive layer becomes a three-dimensional mesh and hardens, and the adhesive strength of the adhesive layer decreases.

[0134] (4) Expand / Pickup Process

[0135] In the expand-pickup process, the adhesive sheet is stretched to widen the gap between semiconductor chips, and the chips or components are pushed up using needle pins or similar tools. Subsequently, the chips or components are adsorbed using vacuum collets or air tweezers, peeled off from the adhesive layer of the adhesive sheet, and picked up.

[0136] Examples

[0137] The present invention will be explained in more detail below using examples, but the present invention is not limited by these examples.

[0138] Manufacture of adhesive sheets for fixing electronic components

[0139] The adhesive sheet for fixing electronic components in the examples and comparative examples was manufactured according to the following formula.

[0140] Specifically, a solution of the acrylic UV adhesive diluted with a solvent (toluene) was applied to a release film (product name: E7002 (manufactured by Toyobo Co., Ltd.)), and after drying the solvent in a drying oven, the adhesive sheet for fixing electronic components of the example was prepared by bonding it to the following substrate film, in which the antistatic layer and protective layer are formed on both sides in this order. In addition, in the comparative example, a substrate film without a protective layer was used.

[0141] In addition, each measurement was performed on the adhesive sheet for fixing electronic components in the examples and comparative examples.

[0142]

[0143] The prescription and measurement methods for each layer in the table are as follows.

[0144] (Adhesive layer)

[0145] · Adhesive layer A (dry film thickness 10㎛): Acrylic UV adhesive A (main components 2-ethylhexyl acrylate (2-EHA), methyl acrylate (MA), 2-hydroxyethyl acrylate (2-HEA), acrylic acid (AA), pentaerythritol triacrylate, isophorone diisocyanate (IPDI), trimethylolpropane (TMP), toluene diisocyanate (TDI))

[0146] · Adhesive layer B (dry film thickness 10㎛): Acrylic UV adhesive B (main component dimethylacrylamide (in addition, including 2-hydroxyethyl methacrylate (2-HEMA), ethyl acrylate (EA), butyl acrylate (BA), 2-ethylhexyl acrylate (2-EHA), glycidyl methacrylate (GMA), pentaerythritol tritetraacrylate (PETA))

[0147] (Insulated film)

[0148] · Substrate A (Film thickness 150㎛): Ionomer film (Product name Hi-Milan (registered trademark) (Manufactured by Mitsui DuPont Polychemicals, Inc.))

[0149] · Substrate B (film thickness 150㎛): PO-based film (three-layer structure film of polypropylene (10㎛) / polyethylene (130㎛) / polypropylene (10㎛))

[0150] (Protection layer)

[0151] Dry film thickness of both inner and outer protective layers: 1㎛ (produced by gravure coating)

[0152] · Protective Layer A: Polyester + Wax

[0153] · Protective Layer B: Solvent-based acrylic

[0154] ·Protective Layer C: Water-based acrylic

[0155] · Protective layer D: Aqueous olefin

[0156] · Protective layer E: Acrylic polymer (polymethyl methacrylate resin)

[0157] (Anti-static layer)

[0158] Dry film thickness of both inner and outer antistatic layers: less than 1㎛

[0159] · Anti-static layer A:

[0160] Carbon nanotubes (content in dry film thickness: 8 to 10 g / m²): Monolayer carbon nanotubes

[0161] Binder: Polymethyl methacrylate resin

[0162] · Anti-static layer B:

[0163] Quaternary ammonium (antistatic agent)

[0164] Binder: Polymethyl methacrylate resin

[0165] · Antistatic layer C

[0166] PEDOT: Poly(3,4-ethylenedioxythiophene)

[0167] (Measurement of surface resistance value)

[0168] Using a micro-ampere (product name: 5451 (manufactured by ADC Co., Ltd.), measurement method: double ring method, applied voltage: 10V, measurement environment: 23℃·humidity 50%), the surface resistance value was measured for the surface of the adhesive layer and the surface of the outer protective layer of each adhesive sheet.

[0169] Specifically, an electrode (probe) was pressed into contact with the surface of an adhesive sheet for fixing electronic components, and the applied voltage was set to 10V to detect the current flowing out of the surface. At this time, by placing the measurement surface upward and a guard electrode on the lower side of the adhesive sheet for fixing electronic components, the current flowing in the thickness direction of the sample was diverted to ground, and only the current flowing purely through the measurement surface was measured. The results are shown in the table.

[0170] (Effect due to the presence of an inner protective layer: retention of adhesive strength)

[0171] After a heat-accelerated test of the adhesive sheet (60°C × 12 days), the adhesive strength of the adhesive sheet (X1 [unit: N / 10 mm]; in accordance with JIS Z 0237) was measured, and the variation (|(X0-X1)÷X0|)×100 [unit: %) with respect to the initial value (before heat-accelerated test: X0 [unit: N / 10 mm]) was evaluated. The results are shown in the table.

[0172] A: 0% or more and less than 5%

[0173] B: 5% or more and less than 10%

[0174] C: 10% or more

[0175] (Probe tag of the outer protective layer)

[0176] The probe tack of the outer protective layer was measured using a probe tack tester TA500 manufactured by UBM Inc. in an indoor environment at a room temperature of 23±2℃ and a humidity of 50±2%. The measurement conditions were a compression time of 1 second, a load of 400gf / ㎠, and a probe peeling speed of 10mm / sec. The results are shown in the table.

[0177] (Effect due to the presence of an outer protective layer: Defect of the outermost surface layer located on the outside)

[0178] For the side opposite to the tape adhesive surface of the adhesive sheet (outer side), the roller surface was observed by visual inspection after one reciprocating motion with a 2 kg roller. Based on whether the roller surface turned black due to the detachment of the antistatic material or protective layer, the degree of defect in the outermost surface layer located on the outer side of the adhesive sheet was evaluated according to the following criteria. The results are shown in the table.

[0179] A: No discoloration

[0180] B: The roller is partially discolored

[0181] C: The entire surface of the roller is discolored

[0182] (Anchor-like)

[0183] A perforation line was formed in the thickness direction on the adhesive layer of an adhesive sheet for fixing electronic components. A strong adhesive tape was bonded to the adhesive layer with the perforation line, and the adhesive layer was cured by irradiating with ultraviolet light (irradiation source: high-pressure mercury lamp, irradiation dose: 250 mJ / ㎠).

[0184] After that, a load was applied in a direction parallel to the sheet surface using a Tensilon universal material testing machine (Orient Tech Co., Ltd. “RTC-1210”) so that the adhesive layer would peel off from the interface of the inner antistatic layer or the inner protective layer at the cut line (tensile speed 300 mm / min, room temperature 23±2℃), and the strength when the adhesive layer was completely peeled off or the strength when peeled off between the strong adhesive tape and the adhesive was measured, and the anchoring strength between the adhesive layer and the inner protective layer (or the inner antistatic layer or the substrate film) was evaluated.

[0185] As a result of the above evaluation, the anchoring performance of the adhesive layer / inner protective layer of the adhesive sheets for fixing electronic components in Examples 4 and 5 was evaluated to be equal to or greater than the anchoring performance between the adhesive layer / inner antistatic layer or the substrate film of the comparative example that does not have an inner protective layer.

[0186] The disclosure of Japanese Patent Application No. 2019-225682, filed on December 13, 2019, is incorporated herein by reference in its entirety.

[0187] In addition, all documents, patent applications, and technical specifications described in the specification are cited by reference in this specification to the same extent as individual documents, patent applications, and technical specifications are cited by reference as they are described individually. Explanation of the symbols

[0188] 100, 200, 300: Adhesive Sheet 20: Substrate film 30: Adhesive layer 40: Outer antistatic layer 42: Inner antistatic layer 50: Outer protective layer 52: Inner protective layer

Claims

Claim 1 An adhesive sheet for fixing an electronic component having a base film and an adhesive layer formed on one side of the base film, and further having an antistatic layer comprising an antistatic material on one side or both sides of the base film; on the other side of the base film, an outer antistatic layer and an outer protective layer are formed in this order as the antistatic layer; between the base film and the adhesive layer, an inner antistatic layer is formed as the antistatic layer; between the adhesive layer and the inner antistatic layer, an inner protective layer is formed; the inner protective layer comprises a polyester or an acrylic polymer; the film thickness of the inner protective layer is 0.1 to 5 μm; and the surface resistance value of the outermost surface of the adhesive sheet is 1 × 10⁻⁶ 7 Ω / □ or less, and the surface resistance value of the surface of the adhesive layer of the adhesive sheet is 1.5×10 10 An adhesive sheet for fixing electronic components, wherein the antistatic material included in at least one of the outer antistatic layer and the inner antistatic layer is carbon nanotubes, and the antistatic material is Ω / □ or less. Claim 2 An adhesive sheet for fixing electronic components according to claim 1, wherein the antistatic material included in the outer antistatic layer is at least one of carbon nanotubes, metal oxides, polythiophene, polyaniline, and polypyrrole. Claim 3 An adhesive sheet for fixing electronic members according to claim 1 or 2, wherein the antistatic material included in the inner antistatic layer is at least one of carbon nanotubes, metal oxides, polythiophene, polyaniline, and polypyrrole. Claim 4 An adhesive sheet for fixing an electronic member according to claim 1 or 2, wherein the film described above comprises at least one selected from a polyolefin resin, a polyester resin, and copolymers thereof. Claim 5 An adhesive sheet for fixing electronic components according to claim 1 or 2, wherein the adhesive layer comprises an acrylic adhesive. Claim 6 An adhesive sheet for fixing electronic members according to claim 1 or 2, wherein the adhesive layer comprises a UV-curing resin composition. Claim 7 delete Claim 8 delete Claim 9 delete

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