Adhesive sheet for fixing electronic components

Abstract

An adhesive sheet for fixing an electronic member, the adhesive sheet having a substrate film and an adhesive layer which is formed on one surface of the substrate film, and furthermore having an antistatic layer which includes an antistatic material on one or both surfaces of the substrate film, wherein the adhesive sheet for fixing an electronic member has, as the antistatic layer, an outside antistatic layer including an antistatic material, and an outside protective layer in this order on the other surface of the substrate film.

Description

[Technical Field]

[0001] The present invention relates to a pressure-sensitive adhesive sheet for fixing electronic components, which is used in a method for producing electronic components. [Background technology]

[0002] After forming circuits on electronic components such as semiconductor wafers or package substrates (hereinafter sometimes simply referred to as "electronic components"), they are transferred to various processes, such as laminating them to an adhesive sheet for fixing electronic components, cutting them into small element pieces (dicing), stretching the adhesive sheet (expanding), and peeling the element pieces from the adhesive sheet (picking up).The adhesive sheet (dicing tape) used in these processes is desired to have sufficient adhesive strength to adhere to the cut element pieces (chips) during dicing, and to have reduced adhesive strength to the extent that no adhesive residue is left behind during pickup.

[0003] In recent years, as electronic components have become smaller and thinner, chip sizes have become smaller. This has led to chip skipping and chip chipping during the dicing process of semiconductor wafers or substrates, which is one of the factors that reduces yield. Furthermore, during the pickup process, needle pin thrusts can cause cracks in the adhesive layer of the adhesive sheet. When cracks occur in the adhesive layer, the cracked adhesive layer adheres to the chip (leaving adhesive residue), causing contamination and defects in the mounting process.

[0004] In order to solve the above-mentioned problems, various adhesive tapes have been developed that are improved in suppressing chipping and chip flying during the dicing process (see, for example, Patent Document 1 below). [Prior art documents] [Patent documents]

[0005] [Patent Document 1] International Publication No. WO2017 / 18270 Summary of the Invention [Problem to be solved by the invention]

[0006] One of the performance requirements for adhesive sheets for fixing electronic components is excellent antistatic properties. If an adhesive sheet for fixing electronic components becomes electrostatically charged, not only will it have a negative effect on electronic components such as semiconductor wafers, but the adhesive sheet will also attract dust particles present in the vicinity and cutting powder generated during dicing, thereby contaminating the electronic components. Therefore, in order to suppress the effects of static electricity on electronic components, adhesive sheets for fixing electronic components are subjected to various treatments. Examples of such treatments include electrostatic treatment of the base film of the adhesive sheet to reduce the surface resistance of the sheet surface, and the addition of an antistatic layer containing an antistatic material.

[0007] However, when an antistatic layer is provided on a base film, part of the antistatic layer may be damaged due to various factors such as vibrations or changes in the shape of the sheet during dicing, expanding, or picking up. If the antistatic layer is damaged, the desired effect of reducing the surface resistance value may not be achieved, and the pieces of the antistatic layer that fall off may become waste and cause contamination.

[0008] In particular, if the antistatic layer comes into contact with other members or the like during handling of the pressure-sensitive adhesive sheet and is damaged, it is estimated that the antistatic layer is more likely to fall off during handling or dicing.

[0009] In order to solve the above-mentioned problems, an object of the present invention is to provide a pressure-sensitive adhesive sheet for fixing electronic components, which causes less contamination of electronic components and has an excellent effect of reducing surface resistance value. [Means for solving the problem]

[0010] In order to solve the above problems, the present invention employs the following means. <1> A pressure-sensitive adhesive sheet for fixing electronic components, comprising a base film and a pressure-sensitive adhesive layer formed on one side of the base film, and further comprising an antistatic layer containing an antistatic material on one or both sides of the base film, The pressure-sensitive adhesive sheet for fixing electronic components has, on the other surface of the base film, an outer antistatic layer and an outer protective layer in this order as the antistatic layer. <2> The surface resistance of at least one surface is 1×10 7 The above-mentioned is Ω / □ or less <1> The pressure-sensitive adhesive sheet for fixing electronic components according to claim 1. <3> The antistatic material contained in the outer antistatic layer is at least one of carbon nanotubes, metal oxides, polythiophenes, polyanilines, and polypyrroles. <1> or <2> The pressure-sensitive adhesive sheet for fixing electronic components according to claim 1. <4> Furthermore, the antistatic layer may be an inner antistatic layer between the base film and the pressure-sensitive adhesive layer. <1> ~The above <3> 10. The pressure-sensitive adhesive sheet for fixing an electronic member according to claim 1, wherein <5> The antistatic material contained in the inner antistatic layer is at least one of carbon nanotubes, metal oxides, polythiophenes, polyanilines, and polypyrroles. <4> The pressure-sensitive adhesive sheet for fixing electronic components according to claim 1. <6> Furthermore, the above-mentioned adhesive sheet has an inner protective layer between the pressure-sensitive adhesive layer and the inner antistatic layer. <4> or <5> The pressure-sensitive adhesive sheet for fixing electronic components according to claim 1. <7> The substrate film comprises at least one selected from the group consisting of polyolefin resins, polyester resins, and copolymers thereof. <1> ~The above <6> The pressure-sensitive adhesive sheet for fixing an electronic member according to any one of claims 1 to 4. <8> The adhesive layer contains an acrylic adhesive. <1> ~The above <7> 10. The pressure-sensitive adhesive sheet for fixing an electronic member according to claim 1, wherein <9> The adhesive layer contains an ultraviolet curable resin composition. <1> ~The above <8> 10. The pressure-sensitive adhesive sheet for fixing an electronic member according to claim 1, wherein [Effects of the Invention]

[0011] According to the present invention, it is possible to provide a pressure-sensitive adhesive sheet for fixing electronic components that causes less contamination of electronic components and has an excellent effect of reducing the surface resistance value. [Brief explanation of the drawings]

[0012] [Figure 1] 1 is a cross-sectional view showing an example of the configuration of a pressure-sensitive adhesive sheet according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0013] A preferred embodiment for carrying out the present invention will be described below. Note that the embodiment described below is an example of a typical embodiment of the present invention, and the scope of the present invention should not be construed as being narrow.

[0014] Adhesive sheet for fixing electronic components The pressure-sensitive adhesive sheet for fixing electronic components (hereinafter sometimes simply referred to as "pressure-sensitive adhesive sheet") of this embodiment has a base film and a pressure-sensitive adhesive layer formed on one side of the base film (hereinafter sometimes referred to as the "adhesive side"). It also has an antistatic layer containing an antistatic material on one or both sides of the base film, and on the other side of the base film (hereinafter sometimes referred to as the "outside") it has an outer antistatic layer and an outer protective layer, in this order, as the antistatic layers. In this embodiment, as described below, layers (e.g., protective layer, antistatic layer) provided between the base film and the pressure-sensitive adhesive layer on one side (adhesive side) of the base film are referred to as the "inner protective layer" and the "inner antistatic layer," respectively. In the following description, the outer antistatic layer and the inner antistatic layer may be collectively referred to simply as "antistatic layer." Similarly, the outer protective layer and the inner protective layer may be collectively referred to simply as "protective layer."

[0015] <Configuration> The layer structure of the pressure-sensitive adhesive sheet of this embodiment will be described with reference to Fig. 1. Fig. 1 is a cross-sectional view showing an example of the structure of the pressure-sensitive adhesive sheet of this embodiment. Common members in each structure will be described using common numbers.

[0016] As described above, the pressure-sensitive adhesive sheet of this embodiment has at least a pressure-sensitive adhesive layer on the adhesive surface of the base film, and at least an outer antistatic layer and an outer protective layer, in this order, on the other surface (outside) of the base film. That is, as shown in Fig. 1(A), a pressure-sensitive adhesive sheet 100 includes a base film 20, and has a pressure-sensitive adhesive layer 30 provided on one surface (adhesive surface: upward in the drawing), and an outer antistatic layer 40 and an outer protective layer 50 provided on the other surface (outside: downward in the drawing). According to the pressure-sensitive adhesive sheet of this embodiment, since the outer antistatic layer is provided on the base film, the surface resistance value of the pressure-sensitive adhesive sheet surface, particularly the outermost surface, can be reduced.

[0017] On the other hand, the outer antistatic layer is prone to cracking and other defects due to contact during handling of the base film or adhesive sheet, physical impact due to vibration during the dicing process, and force due to deformation of the sheet during substrate picking. Cracks are particularly likely to occur in the antistatic layer when the antistatic material contains carbon nanotubes, metal oxides, or the like. Furthermore, if the antistatic layer comes into contact with other components or the like during handling of the base film or adhesive sheet and is damaged, the likelihood of the antistatic layer being damaged increases. If defects occur in the antistatic layer, the desired surface resistance reduction effect may not be achieved, or pieces of the antistatic layer that fall off may become debris and cause contamination.

[0018] In contrast, the outer antistatic layer of the pressure-sensitive adhesive sheet of this embodiment is an outer protective layer provided on the outside of the base film, and therefore the pressure-sensitive adhesive sheet of this embodiment can prevent the antistatic layer from being damaged by contact with other members when handling the base film, etc., and can also prevent the antistatic layer from falling off even if cracks or the like occur in the antistatic layer due to vibrations or changes in the shape of the sheet during dicing, expanding, or picking up.

[0019] The pressure-sensitive adhesive sheet of this embodiment may have an inner antistatic layer containing an antistatic material between the base film and the pressure-sensitive adhesive layer. In this case, as shown in Fig. 1(B), the pressure-sensitive adhesive sheet 200 includes a base film 20, and has an inner antistatic layer 42 and a pressure-sensitive adhesive layer 30 provided in this order on one surface (the adhesive surface: the upper side of the drawing), and an outer antistatic layer 40 and an outer protective layer 50 provided on the other surface (the outside: the lower side of the drawing).

[0020] For example, it is believed that the surface resistance value [Ω / □] of the adhesive surface is one of the factors that cause chipping and flying during the dicing process. If the surface resistance value of the pressure-sensitive adhesive layer surface is high, the pressure-sensitive adhesive layer may not be able to exert the desired adhesive strength, which may cause chipping and flying. However, if an inner antistatic layer is provided between the base film and the pressure-sensitive adhesive layer, the surface resistance value of the adhesive surface of the pressure-sensitive adhesive sheet can be effectively reduced in addition to the outermost surface, thereby suppressing chipping and flying during the dicing process. Furthermore, by reducing the surface resistance of the adhesive surface of the adhesive sheet, the effect of suppressing charging (peeling charging) when the chip is peeled off is improved compared to conventional adhesives and adhesive sheets that have been given antistatic properties, and an adhesive sheet can be produced that has excellent stabilization of adhesive strength and causes less contamination of electronic components (adhesive transfer when electronic components are attached and then peeled off).

[0021] Furthermore, although not particularly limited, a substrate film with antistatic layers already provided on both sides can be used when producing a pressure-sensitive adhesive sheet having an inner antistatic layer, such as pressure-sensitive adhesive sheet 200. In this case, from the viewpoint 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. For example, when preparing adhesive sheet 200 using a substrate film having an antistatic layer and a protective layer on both sides, adhesive sheet 200 can be prepared by removing only one side of the protective layer from the substrate film and providing an adhesive layer on the removed surface.

[0022] On the other hand, when a pressure-sensitive adhesive sheet is produced using a substrate film having an antistatic layer and a protective layer on both sides, the protective layer on the side (inner side) on which the pressure-sensitive adhesive layer is to be provided may not be removed and the pressure-sensitive adhesive layer may be provided thereon, from the viewpoint of improving production efficiency, etc. That is, the pressure-sensitive adhesive sheet of the present embodiment may have, in addition to the inner antistatic layer, an inner protective layer between the pressure-sensitive adhesive layer and the inner antistatic layer. In this case, as shown in FIG. 1(C), the adhesive sheet 300 comprises a base film 20, and on one side (adhesive side: upward in the drawing) there are provided an inner antistatic layer 42, an inner protective layer 52, and an adhesive layer 30, in that order, and on the other side (outside: downward in the drawing) there are provided an outer antistatic layer 40 and an outer protective layer 50.

[0023] Although not shown, each pressure-sensitive adhesive sheet may have a peelable protective film or the like to protect the adhesive surface of the pressure-sensitive adhesive layer during handling. Furthermore, although the above-described layer structures are described as examples in which the antistatic layer and the protective layer are formed separately, the boundary between the antistatic layer and the protective layer does not necessarily have to be clearly defined. For example, the antistatic layer and the protective layer may be formed integrally. In this case, a layer having the functions of both an antistatic layer and a protective layer can be formed by adjusting the distribution concentration of the antistatic material in the thickness direction of the layer to enrich the content of the antistatic material on the substrate side and to reduce the content of the antistatic material near the outer surface (preferably to 0). The materials constituting each layer will be described below.

[0024] <Base film> The substrate film is not particularly limited, but sheets made of various synthetic resins used in the manufacture of electronic components can be used. The material of the substrate film is not particularly limited, but at least one selected from polyolefin resins, polyester resins, and copolymers thereof can be used. Specific examples include polyvinyl chloride, polyethylene terephthalate, ethylene-vinyl acetate copolymer, ethylene-acrylic acid-acrylate 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 copolymers or ethylene-(meth)acrylic acid-(meth)acrylic acid ester copolymers. The substrate film may also be a mixture or copolymer of these resins.

[0025] As the ionomer resin, from the viewpoint of suppressing cutting waste during dicing, a copolymer having ethylene units, (meth)methacrylic acid units, and (meth)acrylic acid alkyl ester units, and Na + , K. + , Zn 2+ Ionomer resins to which metal ions such as those mentioned above are bonded can be suitably used.

[0026] The method for forming the substrate film is not particularly limited, and examples thereof include calendaring, T-die extrusion, inflation, and casting.

[0027] The substrate film may be a single-layer or multi-layer film or sheet containing the above-mentioned materials, or may be a laminate of films made of different materials. The thickness of the substrate film is preferably 50 to 200 μm, more preferably 70 to 150 μm.

[0028] The substrate film may be subjected to an antistatic treatment, such as a treatment in which an antistatic material is blended into the substrate film or a treatment using corona discharge.

[0029] <Adhesive layer> The adhesive layer is a layer to which electronic components such as a conductor wafer or a package substrate are attached during a dicing process or the like, and serves to fix the electronic components. The adhesive contained in the adhesive layer is not particularly limited, but examples thereof include rubber-based adhesives, acrylic adhesives, urethane-based adhesives, and silicone-based adhesives. In this embodiment, a UV-curable adhesive layer is preferred, and therefore, an acrylic adhesive is preferably used. A UV-curable adhesive layer is cured by irradiation with UV light. When the adhesive layer is cured, its elastic modulus increases, reducing its adhesive strength and causing the adhesive layer itself to change shape (shrink). Therefore, irradiating the adhesive layer with UV light after dicing facilitates chip peeling due to the reduced adhesive strength. Examples of UV-curable resin compositions using acrylic adhesives include those containing a (meth)acrylic acid ester copolymer, a photopolymerizable compound, a curing agent, and a photopolymerization initiator.

[0030] -Acrylic adhesive- The acrylic adhesive is not particularly limited, and examples thereof include acrylic acid ester polymers. Herein, in this specification, a compound containing (meth), such as (meth)acrylic acid, is a general term for compounds having "meth" in their names and compounds not having "meth."

[0031] Examples of (meth)acrylic acid ester copolymers include polymers obtained by polymerizing a monomer having a carboxyl group such as (meth)acrylic acid and an ester monomer thereof, and copolymers obtained by copolymerizing these monomers with unsaturated monomers copolymerizable with them (for example, vinyl acetate, styrene, acrylonitrile).

[0032] Examples of monomers having a carboxyl group include methacrylic acid, crotonic acid, maleic acid, itaconic acid, fumaric acid, acrylamido-N-glycolic acid, and cinnamic acid, with methacrylic acid being preferred. Acrylic acid is particularly preferred because the adhesive strength can be more precisely adjusted by adding a curing agent. Examples of ester monomers for (meth)acrylic 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, and benzyl (meth)acrylate.

[0033] The weight average molecular weight of the (meth)acrylic acid ester polymer is preferably 200,000 to 2,000,000 from the viewpoint of preventing the elastic modulus from excessively decreasing or increasing, and thus preventing chipping during dicing.

[0034] (Photopolymerizable compound) The photopolymerizable compound is not particularly limited, but for example, a urethane acrylate oligomer can be used. The urethane acrylate oligomer can be obtained by reacting a polyvalent isocyanate having an acryloyloxy group or a methacryloyloxy group with a (meth)acrylate having a hydroxy group.

[0035] Examples of polyisocyanate compounds that can be used include 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, 1,3-xylene diisocyanate, 1,4-xylene diisocyanate, diphenylmethane 4,4-diisocyanate, trimethylhexamethylene diisocyanate, hexamethylene diisocyanate, and isophorone diisocyanate.

[0036] Examples of (meth)acrylates having a hydroxy group include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, polyethylene glycol (meth)acrylate, pentaerythritol triacrylate, glycidol di(meth)acrylate, and dipentaerythritol monohydroxypentaacrylate.

[0037] The content of the photopolymerizable compound in the adhesive layer is not particularly limited, but from the viewpoint of avoiding poor semiconductor chip pickup due to a decrease in the peelability of the adhesive sheet after light irradiation, or an excessively high elastic modulus of the adhesive during the light irradiation process, which can cause glue cracking during the pickup process, the content is preferably 20 to 150 parts by mass, and more preferably 50 to 120 parts by mass, per 100 parts by mass of the (meth)acrylic acid ester copolymer.

[0038] The photopolymerizable compound is not particularly limited, but from the viewpoints of preventing adhesive residue on the chip due to the adhesive being scraped up during dicing and curing of the adhesive after irradiation with ultraviolet rays, etc., it is preferable that the photopolymerizable compound has a weight average molecular weight of 500 to 100,000 and has at least one acryloyl group or one methacryloyl group, and a total of 4 to 10 groups.

[0039] (hardening agent) Examples of the curing agent include a polyfunctional isocyanate curing agent, a polyfunctional epoxy curing agent, an azirine compound, and a melamine compound. Examples of polyfunctional isocyanate curing agents include aromatic polyisocyanate curing agents, aliphatic polyisocyanate curing agents, and alicyclic polyisocyanate curing agents, and are generally used as adducts in the form of dimers or higher.

[0040] The aromatic polyisocyanate is not particularly limited, and examples thereof include 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, dianisine diisocyanate, 2,4,6-triisocyanate toluene, 1,3,5-triisocyanate benzene, dianisine diisocyanate, 2,4,6-triisocyanate toluene, 2,4,6-triisocyanate toluene, 2,4,6-triisocyanate toluene, dianisine diisocyanate ... Examples of the isocyanate include dimethylbenzene, 4,4'-diphenyl ether diisocyanate, 4,4',4'-triphenylmethane triisocyanate, ω,ω'-diisocyanate-1,3-dimethylbenzene, ω,ω'-diisocyanate-1,4-dimethylbenzene, ω,ω'-diisocyanate-1,4-diethylbenzene, 1,4-tetramethylxylylene diisocyanate, and 1,3-tetramethylxylylene diisocyanate.

[0041] The aliphatic polyisocyanate is not particularly limited, and examples thereof 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.

[0042] The alicyclic polyisocyanate is not particularly limited, and examples thereof include 3-isocyanatomethyl-3,5,5-trimethylcyclohexyl isocyanate, 1,3-cyclopentane diisocyanate, 1,3-cyclohexane diisocyanate, 1,4-cyclohexane diisocyanate, methyl-2,4-cyclohexane diisocyanate, methyl-2,6-cyclohexane diisocyanate, 4,4'-methylenebis(cyclohexyl isocyanate), 1,4-bis(isocyanatomethyl)cyclohexane, and 1,4-bis(isocyanatomethyl)cyclohexane.

[0043] Of the 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 preferably used.

[0044] Multifunctional epoxy curing agents are primarily compounds that have two or more epoxy groups and one or more tertiary nitrogen atoms, and examples include N·N-glycidylaniline, N·N-glycidyltoluidine, mN·N-glycidylaminophenyl glycidyl ether, pN·N-glycidylaminophenyl glycidyl ether, triglycidyl isocyanurate, N·N·N'·N'-tetraglycidyldiaminodiphenylmethane, N·N·N'·N'-tetraglycidyl-m-xylylenediamine, and N·N·N'·N'·N''-pentaglycidyldiethylenetriamine.

[0045] The content of the curing agent in the adhesive layer is preferably 1 to 20 parts by mass, more preferably 1.5 to 15 parts by mass, per 100 parts by mass of the (meth)acrylic acid ester copolymer, from the viewpoint of suppressing the occurrence of adhesive residue and insufficient adhesive strength.

[0046] (Photopolymerization initiator) As the photopolymerization initiator, benzoin, benzoin alkyl ethers, acetophenones, anthraquinones, thioxanthones, ketals, benzophenones, xanthones, etc. may be used. Examples of benzoin include benzoin, benzoin methyl ether, benzoin ethyl ether, and benzoin propyl ether. Examples of acetophenones include benzoin alkyl ethers, acetophenone, 2,2-dimethoxy-2-acetophenone, 2,2-diethoxy-2-acetophenone, and 1,1-dichloroacetophenone. Examples of anthraquinones include 2-methylanthraquinone, 2-ethylanthraquinone, 2-tert-butylanthraquinone, and 1-chloroanthraquinone. Examples of thioxanthones include 2,4-dimethylthioxanthone, 2,4-diisopropylthioxanthone, 2-chlorothioxanthone, and 2,4-diisopropylthioxanthone.

[0047] Examples of ketals include acetophenone dimethyl ketal, benzyl dimethyl methal, benzyl diphenyl sulfide, tetramethylthiuram monosulfide, azobisisobutyronitrile, dibenzyl, diacetyl, β-chloroanthraquinone, and the like.

[0048] The content of the photopolymerization initiator in the adhesive layer is 1 to 15 parts by mass, and more preferably 1.5 to 10 parts by mass, per 100 parts by mass of the (meth)acrylic acid ester polymer, from the viewpoints of improving peelability from the adhesive sheet after light irradiation and suppressing bleed-out of the photopolymerization initiator onto the surface of the adhesive layer.

[0049] The photopolymerization initiator may be used in combination with one or more conventionally known photopolymerization accelerators, if necessary. Examples of the photopolymerization accelerator include benzoic acid accelerators and tertiary amines. Examples of tertiary amines include triethylamine, tetraethylpentamine, and dimethylaminoether.

[0050] A terpene phenol resin obtained by completely or partially hydrogenating a terpene phenol resin may be added to the adhesive layer as a tackifier resin. Furthermore, various additives such as a softener, an antioxidant, a filler, a conductive agent, an ultraviolet absorber, and a light stabilizer may be added to the pressure-sensitive adhesive layer as needed.

[0051] The thickness of the adhesive layer is not particularly limited, but from the viewpoint of ensuring chip retention during dicing by ensuring adhesive strength and preventing chipping due to the thickness of the adhesive layer, it is preferably 1 to 50 μm, and more preferably 5 to 30 μm. The adhesive strength between the pressure-sensitive adhesive layer and the underlying member, for example, the adhesive strength between the pressure-sensitive adhesive layer and the base film, between the pressure-sensitive adhesive layer and the inner antistatic layer, or between the pressure-sensitive adhesive layer and the inner protective layer (anchoring strength [unit: N / 20 mm]) is not particularly limited, but from the viewpoint of adhesive residue after tape peeling, it is preferably 1 N / 20 mm or more, and more preferably 6 N / 20 mm or more. The anchoring strength can be measured by the method described in the Examples.

[0052] <Antistatic layer> The antistatic layer is a layer containing an antistatic material. In this embodiment, as described above, an inner antistatic layer can be formed in addition to the outer antistatic layer. The antistatic material is not particularly limited, but at least one of carbon nanotubes, metal oxides, polythiophenes, polyanilines, and polypyrroles is preferred. The carbon nanotubes, metal oxides, polythiophenes, polyanilines, and polypyrroles are not particularly limited as long as they are used as antistatic materials (conductive materials), and known materials can be appropriately selected and used. Furthermore, from the viewpoint of antistatic effect, carbon nanotubes are particularly preferred as these antistatic materials. The outer antistatic layer and the inner antistatic layer can be made of the same antistatic material, and both layers may be made of the same material or different materials.

[0053] Carbon nanotubes (hereinafter sometimes simply referred to as "CNTs") may be either single-walled carbon nanotubes (SWCNTs) or multi-walled carbon nanotubes (MWCNTs).

[0054] MWCNTs are composed of multiple cylindrical carbon-walled tubes of different diameters stacked around a central axis, with the carbon walls forming multiple layers in a hexagonal carbon network structure or spiral pattern. MWCNTs preferably have 2 to 30 carbon wall layers stacked, and more preferably have 2 to 15 carbon wall layers stacked. The carbon nanotubes may be dispersed individually or in bundles in the antistatic layer.

[0055] The antistatic layer may use a binder together with an antistatic material such as carbon nanotubes. The binder is not particularly limited, but examples thereof include (meth)acrylic acid ester polymers, acrylic polymers, urethane polymers, polyester polymers, epoxy polymers, polyvinyl chloride polymers, melanin polymers, polyimide polymers, and silicone polymers, among which (meth)acrylic acid ester polymers are preferred. Examples of the (meth)acrylic acid ester polymers include the same (meth)acrylic acid ester polymers as those used in the pressure-sensitive adhesive layer described above.

[0056] When a binder is used, the content of carbon nanotubes and the like in the antistatic layer is not particularly limited. However, from the viewpoint of the strength of the antistatic layer (e.g., crack resistance, etc.), adhesion to the base film, and exhibiting a sufficient antistatic effect, the content of carbon nanotubes in the antistatic layer after drying is, for example, 5 to 20 mg / m 2 Approximately, preferably 7 to 11 mg / m 2 It can be said that:

[0057] The antistatic layer may contain a known antistatic material (e.g., dimethylaminoethyl (meth)acrylate quaternary chloride, diethylaminoethyl (meth)acrylate quaternary chloride, methylethylaminoethyl (meth)acrylate quaternary chloride, p-dimethylaminostyrene quaternary chloride, p-diethylaminostyrene quaternary chloride, etc.) within the range that does not impair the effects of the present invention. If necessary, various additives such as a hardener, a plasticizer, an antioxidant, a filler, etc. may be added to the antistatic layer as appropriate within the range that does not impair the effects of the present invention.

[0058] The method for forming the antistatic layer is not particularly limited, and examples thereof include a method of directly applying the antistatic layer onto a substrate film using a coater such as a gravure coater, a bar coater, a knife coater, or a roll coater, and a printing method such as relief printing, intaglio printing, lithographic printing, flexographic printing, offset printing, or screen printing.

[0059] The thickness of the outer antistatic layer is not particularly limited, but from the viewpoints of the strength of the antistatic layer (e.g., crack resistance, etc.), adhesion to the base film, and exerting a sufficient antistatic effect, it is preferably 0.01 to 1 μm, and more preferably 0.02 to 0.2 μm. The thickness of the inner antistatic layer is not particularly limited, but from the viewpoints of the strength of the antistatic layer (e.g., crack resistance, etc.), adhesion to the base film, and exerting a sufficient antistatic effect, it is preferably 0.01 to 1 μm, and more preferably 0.02 to 0.2 μm.

[0060] <Protective layer> The protective layer is a layer provided to protect the antistatic material. In this embodiment, as described above, an inner protective layer can be formed in addition to the outer protective layer. The outer protective layer is a layer whose main purpose is to prevent the antistatic layer from falling off during the dicing process. Furthermore, both the inner layer and the outer protective layer can suppress damage such as physical impact upon contact when handling the base film, and can also prevent the antistatic layer from falling off. Furthermore, a pressure-sensitive adhesive sheet for electronic components having an inner protective layer has excellent adhesive strength retention of the pressure-sensitive adhesive layer even when stored for a certain period of time under relatively high temperature conditions. The protective layer preferably has no tackiness. Here, "no tackiness" means that the probe tack (based on ASTM D 2979) is 0.1 N / 20 mm 2 It is preferable that: The outer protective layer and the inner protective layer may be layers formed of the same material, or may be layers formed of different materials. When the inner protective layer and the outer protective layer are formed of different materials, it is preferable that at least the outer protective layer does not have tackiness.

[0061] The material (binder) constituting the outer protective layer is not particularly limited, and examples thereof include (meth)acrylic acid ester polymers, acrylic polymers, urethane polymers, polyester polymers, epoxy polymers, polyvinyl chloride polymers, melanin polymers, polyimide polymers, and silicone polymers, among which (meth)acrylic acid ester polymers are preferred. As the (meth)acrylic acid ester polymer, the (meth)acrylic acid ester polymer used in the above-mentioned pressure-sensitive adhesive layer can be used.

[0062] The material (binder) constituting the inner protective layer is not particularly limited, but considering the adhesion to the adhesive layer formed of a UV-curable resin containing an acrylic adhesive, it is preferable to use a water-based olefin resin or an acrylic polymer. The reason why the use of these resins in the inner protective layer improves adhesion to the adhesive layer is not clear, but it is thought 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 the chemical bonding between the isocyanate groups contained in the adhesive and the hydroxyl groups or carboxylic acid groups.

[0063] The acrylic polymer is not particularly limited, but examples thereof include polymethacrylic acid ester, polyacrylic acid ester, sodium polyacrylate, polyacrylonitrile, and polyacrylamide, and specifically, polymethyl methacrylate is preferred.

[0064] Furthermore, a friction reducer can be used in the protective layer (particularly the outer protective layer). The use of a friction reducer can reduce the coefficient of friction between the pressure-sensitive adhesive sheet and the expanding device. Examples of friction reducers include silicone compounds such as silicone resins and (modified) silicone oils, fluororesins, hexagonal boron nitride, carbon black, and molybdenum disulfide. Silicone graft copolymers are preferred from the viewpoint of good compatibility with the antistatic layer and a balance between antistatic properties and expandability.

[0065] Examples of silicone graft copolymers include vinyl polymers obtained by polymerizing a monomer having a vinyl group such as a (meth)acryloyl group or a styryl group at the end of the silicone molecular chain (hereinafter referred to as a "silicone monomer") with a (meth)acrylic monomer, a monomer having a vinyl group such as styrene, etc. (see, for example, JP 2000-080135 A).

[0066] The amount of friction reducer 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 preferably 0.005 to 10 parts by mass per 100 parts by mass of the binder.

[0067] If necessary, various additives such as a hardener, a plasticizer, an antioxidant, a filler, etc. may be added to the protective layer as appropriate within the range that does not impair the effects of the present invention.

[0068] The method for forming the protective layer is not particularly limited, and examples thereof include a method of directly applying the protective layer onto the substrate film using a coater such as a gravure coater, a bar coater, a knife coater, or a roll coater, and a printing method such as relief printing, intaglio printing, lithographic 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.

[0069] The thickness of the outer protective layer is not particularly limited, but from the viewpoint of the strength of the protective layer and the antistatic effect, it is preferably 0.1 to 5 μm, more preferably 0.5 to 2 μm. The thickness of the inner protective layer is not particularly limited, but is preferably 0.1 to 5 μm, more preferably 0.5 to 2 μm, from the viewpoint of the strength of the protective layer and the antistatic effect.

[0070] The outer protective layer is preferably the outermost layer on the outside of the pressure-sensitive adhesive sheet. The surface of the outermost layer of the pressure-sensitive adhesive sheet may be embossed. By embossing, it is possible to make the surface of the outer protective layer an embossed surface having an average surface roughness (Ra) of, for example, 0.3 to 1.5 μm. When the outermost layer surface of the pressure-sensitive adhesive sheet is embossed, the embossed surface of the pressure-sensitive adhesive sheet can be placed on the machine table side of the expanding device, thereby making it possible to easily expand the base film in the expanding step after dicing.

[0071] <Surface resistance value> The surface resistance of the pressure-sensitive adhesive sheet of this embodiment can be measured using an electrometer or the like in accordance with JIS-K6911. The pressure-sensitive adhesive sheet of this embodiment has a surface resistance of 1×10 7 It is preferably Ω / □ or less. Specifically, the surface resistance value of the outermost surface of the adhesive sheet is not particularly limited, but from the viewpoint of suppressing the peeling electrification of the tape, it is set to 1×10 7 Ω / □ or less is preferable. The surface resistance of the adhesive surface (adhesive layer) of the adhesive sheet is not particularly limited, but from the viewpoint of suppressing the peeling charge of the tape, it is set to 1×10 10 Ω / □ or less is preferable.

[0072] <<Method for manufacturing adhesive sheets>> The method for producing the pressure-sensitive adhesive sheet of this embodiment is not particularly limited, and each layer can be produced on a substrate film using the method described above. For example, in the case of the pressure-sensitive adhesive sheet 100 shown in Fig. 1(A), the sheet can be produced by forming an antistatic layer and a protective layer in this order on only one side of a substrate film, and providing a pressure-sensitive adhesive layer on the other side. Furthermore, when using such a base film, the adhesive sheet 200 in FIG. 1(B) can be produced by forming an inner antistatic layer before providing an adhesive layer, and then providing an adhesive layer thereon. Alternatively, the adhesive sheet 200 can be produced by using a substrate film having an antistatic layer and a protective layer on both sides, removing the protective layer from only one side, and providing an adhesive layer on the removed surface. Furthermore, by using a substrate film having an antistatic layer and a protective layer on both sides and providing an adhesive layer on one of the protective layers, adhesive sheet 300 in FIG. 1(C) can be produced.

[0073] As described above, the pressure-sensitive adhesive sheet of this embodiment may have a peelable protective film on the pressure-sensitive adhesive layer. Furthermore, the pressure-sensitive adhesive sheet of this embodiment may have other layers between the layers as long as the effects of the present invention are not impaired. However, from the viewpoint of adhesion between the layers, pressure-sensitive adhesive sheets shown in Figures 1(A) to 1(C) are preferably laminated so that the layers are in direct contact with each other.

[0074] <<Method for manufacturing electronic components>> The method for producing an electronic component using the pressure-sensitive adhesive sheet of this embodiment is not particularly limited, but examples thereof include a production method including the following steps.

[0075] (1) Pasting process In the attachment process, the pressure-sensitive adhesive sheet is attached to an electronic component such as a semiconductor wafer or a package substrate and 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.

[0076] (2) Dicing process In the dicing process, electronic components such as silicon wafers are diced into semiconductor chips or semiconductor components.

[0077] (3) Light irradiation process In the light irradiation step, the photocurable pressure-sensitive adhesive layer is irradiated with active light such as ultraviolet light from the substrate film side. Examples of light sources that can be used for the ultraviolet light include low-pressure mercury lamps, high-pressure mercury lamps, ultra-high-pressure mercury lamps, metal halide lamps, and black lights. Instead of ultraviolet light, electron beams can be used, and α-rays, β-rays, and γ-rays can be used as the source of the electron beams. When irradiated with light, the adhesive layer is hardened through a three-dimensional network structure, and the adhesive strength of the adhesive layer is reduced.

[0078] (4) Expand and pick-up process In the expand pick-up process, the adhesive sheet is stretched to widen the gap between the semiconductor chips, and the chips or components are pushed up with a needle pin, etc. The chips or components are then picked up by adsorbing them with a vacuum collet or air tweezers, etc., and peeling them off from the adhesive layer of the adhesive sheet. [Example]

[0079] The present invention will be explained in more detail below with reference to examples, but the present invention is not limited to these examples in any way.

[0080] <<Production of adhesive sheets for fixing electronic components>> The pressure-sensitive adhesive sheets for fixing electronic members in the examples and comparative examples were produced according to the following formulations. Specifically, a solution of the following acrylic UV adhesive diluted with a solvent (toluene) was applied to a release film (product name: E7002 (manufactured by Toyobo Co., Ltd.)), the solvent was dried in a drying oven, and then the adhesive sheet for fixing electronic components of the example was produced by laminating the film to the following substrate film having the following antistatic layer and protective layer provided in that order on both sides. In the comparative example, a substrate film without a protective layer was used. Moreover, the pressure-sensitive adhesive sheets for fixing electronic members in the examples and comparative examples were subjected to various measurements.

[0081] [Table 1]

[0082] The formulations and measurement methods for each layer in the table are as follows:

[0083] (Adhesive layer) Adhesive layer A (dry film thickness 10 μm): 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)) Adhesive layer B (dry film thickness 10 μm): Acrylic UV adhesive B (main component: dimethylacrylamide (other components include 2-hydroxyethyl methacrylate (2-HEMA), ethyl acrylate (EA), butyl acrylate (BA), 2-ethylhexyl acrylate (2-EHA), glycidyl methacrylate (GMA), pentaerythritol tri- and tetraacrylate (PETA))

[0084] (Base film) Substrate A (film thickness 150 μm): Ionomer film (product name: Himilan (registered trademark) (manufactured by DuPont-Mitsui Polychemicals Co., Ltd.)) Substrate B (film thickness 150 μm): PO-based film (three-layer structure film of polypropylene (10 μm) / polyethylene (130 μm) / polypropylene (10 μm))

[0085] (protective layer) Dry film thickness of both inner and outer protective layers: 1 μm (prepared by gravure coating) Protective layer A: Polyester + Wax Protective layer B: Solvent-based acrylic Protective layer C: Water-based acrylic Protective layer D: Water-based olefin Protective layer E: Acrylic polymer (polymethyl methacrylate resin)

[0086] (antistatic layer) Dry film thickness of both inner and outer antistatic layers: less than 1 μm Antistatic layer A: Carbon nanotubes (content in dry film thickness: 8-10 g / m 2 ): Single-walled carbon nanotubes tube Binder: Polymethyl methacrylate resin Antistatic layer B: Quaternary ammonium (antistatic material) Binder: Polymethyl methacrylate resin Antistatic layer C PEDOT: Poly(3,4-ethylenedioxythiophene)

[0087] (Measurement of surface resistance) The surface resistance of the adhesive layer surface and outer protective layer surface of each adhesive sheet was measured using a microcurrent meter (product name: 5451 (manufactured by ADC Corporation), measurement method: double ring method, applied voltage: 10 V, measurement environment: 23°C, humidity 50%). Specifically, an electrode (probe) was pressed against the surface of the adhesive sheet for fixing electronic components, and a voltage of 10 V was applied to detect the current flowing through the surface. In this case, the measurement surface was set to the upper side, and a guard electrode was placed on the lower side of the adhesive sheet for fixing electronic components, so that the current that had flowed in the thickness direction of the sample was directed to ground, and only the current flowing through the measurement surface was measured. The results are shown in the table.

[0088] (Benefit of having an inner protective layer: Maintains adhesive strength) After the pressure-sensitive adhesive sheet underwent an accelerated heating test (60°C x 12 days), the adhesive strength (X1 [unit: N / 10 mm]; in accordance with JIS Z 0237) of the pressure-sensitive adhesive sheet was measured, and the variation (|(X0-X1) ÷ X0|) x 100 [unit: %] relative to the initial value (before the accelerated heating test: X0 [unit: N / 10 mm]) was evaluated. The results are shown in the table. A: 0% to less than 5% B: 5% or more but less than 10% C: 10% or more

[0089] (Probe tack on outer protective layer) The probe tack of the outer protective layer was measured using a probe tack tester TA500 manufactured by UBM Co., Ltd. in a room with a room temperature of 23±2°C and a humidity of 50±2%. The measurement conditions were a pressing time of 1 second and a load of 400 gf / cm. 2 The probe peeling speed was 10 mm / sec. The results are shown in the table.

[0090] (Effect of having an outer protective layer: Missing the outermost surface layer) A 2 kg roller was rolled back and forth once on the opposite side (outside) of the adhesive sheet from the tape adhesive side, and the roller surface was then visually inspected. The degree of damage to the outermost layer of the adhesive sheet was evaluated according to the following criteria based on whether the roller surface had turned black due to the removal of the antistatic material or protective layer. The results are shown in the table. A: No discoloration B: The roller is partially discolored. C: The entire roller is discolored

[0091] (anchoring) A slit was made in the thickness direction in the adhesive layer of the adhesive sheet for fixing electronic components. A strong adhesive tape was attached to the slit adhesive layer, and ultraviolet light was irradiated (irradiation source: high-pressure mercury lamp, irradiation dose: 250 mJ / cm). 2 ) to cure the adhesive layer. Thereafter, a load was applied in a direction parallel to the sheet surface using a Tensilon universal material testing machine ("RTC-1210" manufactured by Orientec Co., Ltd.) so that the adhesive layer would peel from the cut at the interface with the inner antistatic layer or inner protective layer (tensile speed 300 mm / min, room temperature 23±2°C), and the strength when the adhesive layer was completely peeled off or the strength when peeling occurred between the strong adhesive tape and the adhesive was measured, and the anchoring strength between the adhesive layer and the inner protective layer (or inner antistatic layer or base film) was evaluated.

[0092] As a result of the above evaluation, the anchoring properties of the adhesive layer / inner protective layer of the adhesive sheets for fixing electronic components of Examples 4 and 5 were evaluated to be equal to or better than the anchoring properties between the adhesive layer / inner antistatic layer or base film of the sheets of the comparative example which did not have an inner protective layer.

[0093] The disclosure of Japanese Patent Application No. 2019-225682, filed on December 13, 2019, is incorporated herein by reference in its entirety. In addition, all publications, patent applications, and technical standards mentioned in the specification are herein incorporated by reference to the same extent as if each individual publication, patent application, and technical standard was specifically and individually indicated to be incorporated by reference. [Explanation of symbols]

[0094] 100, 200, 300... adhesive sheet, 20... base film, 30... adhesive layer, 40... outer antistatic layer, 42... inner antistatic layer, 50... outer protective layer, 52... inner protective layer

Claims

1. A pressure-sensitive adhesive sheet for fixing electronic components, comprising a base film and a pressure-sensitive adhesive layer formed on one side of the base film, and further comprising an antistatic layer containing an antistatic material on one or both sides of the base film, The antistatic layer includes an outer antistatic layer and an outer protective layer in this order on the other surface of the base film, an inner antistatic layer is provided between the base film and the pressure-sensitive adhesive layer, an inner protective layer between the pressure-sensitive adhesive layer and the inner antistatic layer; the inner protective layer comprises one selected from polyester, solvent-based acrylic, water-based acrylic, water-based olefin, and acrylic polymer; The surface resistance of the pressure-sensitive adhesive layer surface is 1.5×10 １０ Ω / □ or less, the antistatic material contained in at least one of the outer antistatic layer and the inner antistatic layer is carbon nanotubes; Adhesive sheet for fixing electronic components.

2. The surface resistance of at least one surface is 1×10 ７ The pressure-sensitive adhesive sheet for fixing electronic components according to claim 1, having a resistance of Ω / □ or less.

3. 3. The pressure-sensitive adhesive sheet for fixing electronic components according to claim 1, wherein the antistatic material contained in the outer antistatic layer is at least one of carbon nanotubes, metal oxides, polythiophenes, polyanilines, and polypyrroles.

4. 3. The pressure-sensitive adhesive sheet for fixing electronic components according to claim 1, wherein the antistatic material contained in the inner antistatic layer is at least one of carbon nanotubes, metal oxides, polythiophenes, polyanilines, and polypyrroles.

5. The pressure-sensitive adhesive sheet for fixing electronic members according to any one of claims 1 to 4, wherein the base film contains at least one selected from polyolefin-based resins, polyester-based resins, and copolymers thereof.

6. The pressure-sensitive adhesive sheet for fixing electronic members according to any one of claims 1 to 5, wherein the pressure-sensitive adhesive layer contains an acrylic pressure-sensitive adhesive.

7. The pressure-sensitive adhesive sheet for fixing electronic members according to any one of claims 1 to 6, wherein the pressure-sensitive adhesive layer contains an ultraviolet-curable resin composition.

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