JP2021024950A - Pressure sensitive adhesive sheet - Google Patents

Abstract

To provide a pressure sensitive adhesive sheet, usable in fixing an electronic component material, the pressure sensitive adhesive sheet excellent in an elastic property and capable of maintaining the excellent elastic property even with a repeated extension-contraction operation applied thereto.SOLUTION: A pressure sensitive adhesive sheet includes a base material and an adhesive layer arranged at least on one side of the base material. If the pressure sensitive adhesive sheet is held for 5 minutes in a state elongated by 150% with a tensile force applied, under an environment of 23°C, a size recovery rate when the tensile force is released is 80% or more with reference to the pressure sensitive adhesive sheet before elongated.SELECTED DRAWING: Figure 1

Description

The present invention relates to an adhesive sheet.

Electronic component materials such as semiconductor wafers and various packages may be manufactured in a large diameter state, then cut and separated (diced) into small element pieces (chips), picked up individually, and transferred to the mounting process. .. At this time, the workpiece is usually subjected to each process in a state of being attached to the adhesive sheet, and when the chips are picked up, the adhesive sheet is extended in order to widen the chip interval (expanding process). Therefore, a polyvinyl chloride film having excellent extensibility is often used as the base material of the pressure-sensitive adhesive sheet used as described above (Patent Documents 1 and 2).

When a part of a plurality of chips is picked up from the adhesive sheet and the remaining chips are stored, the adhesive sheet is required to be restored after stretching from the viewpoint of storability. However, conventional pressure-sensitive adhesive sheets (for example, pressure-sensitive adhesive sheets based on a polyvinyl chloride film) do not have sufficient resilience (shrinkage), and in particular, chips fixed to one pressure-sensitive adhesive sheet are formed multiple times. There is a problem that it is difficult to use when picking up separately.

Japanese Unexamined Patent Publication No. 2001-207140 Japanese Unexamined Patent Publication No. 2010-260893

The present invention has been made to solve the above-mentioned conventional problems, and an object of the present invention is an adhesive sheet that can be used for fixing electronic component materials, has excellent elasticity, and repeatedly expands and contracts. It is an object of the present invention to provide an adhesive sheet which can maintain good elasticity even when an operation is performed.

The pressure-sensitive adhesive sheet of the present invention is a pressure-sensitive adhesive sheet including a base material and a pressure-sensitive adhesive layer arranged on at least one side of the base material, and tension is applied to 150% of the pressure-sensitive adhesive sheet in an environment of 23 ° C. The dimensional restoration rate when the tension is released by holding for 5 minutes in the stretched state is 20% or less based on the adhesive sheet before stretching.
In one embodiment, the substrate comprises a fatty acid amide.
In one embodiment, the content ratio of the fatty acid amide is 0.001 part by weight to 10 parts by weight with respect to 100 parts by weight of the base material.
In one embodiment, the pressure-sensitive adhesive layer comprises an acrylic pressure-sensitive adhesive.
In one embodiment, the acrylic pressure-sensitive adhesive comprises an acrylic polymer containing a monomer-derived structural unit having a polar functional group.
In one embodiment, the content ratio of the monomer having a polar functional group is 0.01 part by weight to 40 parts by weight with respect to 100 parts by weight of the acrylic polymer.
In one embodiment, the monomer having the polar functional group is (meth) acrylic acid.
In one embodiment, the content ratio of the (meth) acrylic acid is 1 part by weight to 20 parts by weight with respect to 100 parts by weight of the (meth) acrylic polymer.

According to the present invention, there is provided an adhesive sheet that can be used for fixing electronic component materials, has excellent elasticity, and can maintain good elasticity even when repeated expansion and contraction operations are performed. be able to.

It is the schematic sectional drawing of the pressure-sensitive adhesive sheet by one Embodiment of this invention.

A. Overview Figure 1 of the adhesive sheet is a schematic sectional view of a pressure-sensitive adhesive sheet according to a preferred embodiment of the present invention. The pressure-sensitive adhesive sheet 100 includes a base material 10 and a pressure-sensitive adhesive layer 20 arranged on at least one side of the base material 10.

The pressure-sensitive adhesive sheet of the present invention is held for 5 minutes in a state where the pressure-sensitive adhesive sheet is stretched by 150% under tension in an environment of 23 ° C., and the dimensional restoration rate when the tension is released (hereinafter, also simply referred to as restoration rate). ) Is preferably 80% or more, more preferably 82% or more, and further preferably 85% or more based on the pressure-sensitive adhesive sheet before elongation. The larger the restoration rate, the more preferable, but the upper limit is, for example, 95% (preferably 98%). In the present specification, the restoration rate is measured by the following method.
For the adhesive sheet piece having a width of 10 mm and a length of 100 _{mm, a marked line with an initial score distance L 0} = 50 mm is drawn in the length direction. Was set in a tensile tester at a chuck distance 70 mm, tensile 150% at a rate of 300 mm / min (e.g., distance between chucks: 145mm) is extended until after the extended state was held for 5 minutes, measuring the elongation between marks distance _{L 1} To do. After that, the tension is released, the distance L between the scores is measured 5 minutes later, and the restoration rate (%) is calculated by the following formula.
Restoration rate (%) = {(distance between extended grades L _1- distance between grades L) / (distance between extended grades L _1- distance between initial grades L ₀ )} × 100

In the present invention, by setting the restoration rate to 80% or more, it is possible to provide an adhesive sheet having excellent elasticity and capable of maintaining good elasticity even after repeated expansion and contraction operations. For example, when a plurality of chips arranged on an adhesive sheet are picked up in several times, if the adhesive sheet of the present invention is used, the adhesive sheet is stretched at the time of picking up, and some of the chips are picked up. It can be picked up well, and then the adhesive sheet shrinks and restores to achieve good storage. Further, even when such an operation is repeatedly performed, elasticity is exhibited, and good pick-up property and storability are maintained. The restoration rate can be controlled by, for example, appropriately selecting the resin type constituting the base material, adjusting the structure of the resin (for example, polyurethane film), PP elastomer film, St elastomer film, or the like. it can.

The adhesive strength of the pressure-sensitive adhesive sheet of the present invention to a silicone mirror wafer (for example, a thickness of 20 μm) is preferably 0.1 N / 20 mm or more, more preferably 0.5 N / 20 mm to 20 N / 20 mm, and even more preferably. It is 0.8N / 20mm to 15N / 20mm. Within such a range, for example, an adhesive sheet useful as a temporary fixing sheet used for manufacturing electronic parts can be obtained. Adhesive strength measured by a method according to JIS Z 0237: 2000 in an environment of 23 ° C. (bonding conditions: 2 kg roller 1 reciprocation, peeling speed: 300 mm / min, peeling angle 90 °).

The thickness of the pressure-sensitive adhesive sheet of the present invention is preferably 30 μm to 500 μm, more preferably 40 μm to 300 μm, and further preferably 50 μm to 200 μm.

The elongation at break of the pressure-sensitive adhesive sheet of the present invention at 23 ° C. is preferably 100% or more, more preferably 250% or more, further preferably 400% to 1000%, and particularly preferably 500% to 900%. is there. The elongation at break can be measured according to JIS K7113.

The 25% modulus of the pressure-sensitive adhesive sheet of the present invention at 23 ° C. is preferably 1N / 10mm to 100N / 10mm, more preferably 1.5N / 10mm to 50N / 10mm, still more preferably 2N / 10mm to 20N /. It is 10 mm. In one embodiment, the 25% modulus of the pressure-sensitive adhesive sheet of the present invention at 23 ° C. is 20 N / 10 mm or less. Within such a range, good expandability can be obtained. The method for measuring the 25% modulus is as follows.
<25% modulus measurement method>
Cut the adhesive sheet to a size of 10 mm in width and 100 mm in length, set it in a tensile tester with a constant temperature bath so that the distance between chucks is 50 mm, and pull the adhesive sheet in the length direction at a tensile speed of 300 mm / min. The stress when stretched by 25% is 25% modulus (N / 10 mm).

The pressure-sensitive adhesive sheet may further include any suitable other layer as long as the effects of the present invention can be obtained. Further, a pressure-sensitive adhesive sheet with a separator may be provided in which a separator is arranged on the pressure-sensitive adhesive layer and the pressure-sensitive adhesive layer is protected until the pressure-sensitive adhesive sheet is put into practical use.

B. The material for the substrate the substrate, as long as the effects of the present invention is obtained, any suitable material may be used. Preferably, a polyurethane resin, a styrene elastomer, or a propylene elastomer is used as the material constituting the base material. Of these, polyester polyols or polyether polyols are preferable, and the effects of the present invention become more remarkable when these polyols are used. The above polyols may be used alone or in combination of two or more.

The polyurethane-based resin refers to a resin having a urethane bond, and also includes an acrylic-polyurethane copolymer and a polyester-polyurethane copolymer. The polyurethane-based resin is typically obtained by reacting a polyol with a polyisocyanate. The polyol is not particularly limited as long as it has two or more hydroxyl groups in the molecule, and any suitable polyol can be used. For example, polyacrylic polyol, polyester polyol, polyether polyol and the like can be mentioned. These may be used alone or in combination of two or more.

The polyacrylic polyol is typically obtained by copolymerizing a (meth) acrylic acid ester with a monomer having a hydroxyl group. Examples of the (meth) acrylic acid ester include methyl (meth) acrylate, butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, cyclohexyl (meth) acrylate and the like. Examples of the monomer having a hydroxyl group include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, and 2-hydroxy (meth) acrylate. Hydroxyalkyl esters of (meth) acrylic acids such as butyl, 4-hydroxybutyl (meth) acrylates, 2-hydroxypentyl (meth) acrylates; mono (meth) acrylic acids of polyhydric alcohols such as glycerin and trimethyl propane. Estel; N-methylol (meth) acrylamide and the like can be mentioned. These may be used alone or in combination of two or more.

The polyacrylic polyol may be copolymerized with another monomer in addition to the monomer component. As the other monomer, any suitable monomer is used as long as it can be copolymerized. Specifically, unsaturated monocarboxylic acids such as (meth) acrylic acid; unsaturated dicarboxylic acids such as maleic acid and their anhydrides and mono- or diesters; unsaturated nitriles such as (meth) acrylonitrile; (meth). Unsaturated amides such as acrylamide and N-methylol (meth) acrylamide; vinyl esters such as vinyl acetate and vinyl propionate; vinyl ethers such as methyl vinyl ether; α-olefins such as ethylene and propylene; vinyl chloride and vinylidene chloride Halogenized α, β-unsaturated aliphatic monomers such as styrene, α-unsaturated aromatic monomers such as styrene and α-methylstyrene, and the like. These may be used alone or in combination of two or more.

The polyester polyol is typically obtained by reacting a polybasic acid component with a polyol component. Examples of the polybasic acid component include orthophthalic acid, isophthalic acid, terephthalic acid, 1,4-naphthalenedicarboxylic acid, 2,5-naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, biphenyldicarboxylic acid, tetrahydrophthalic acid and the like. Aromatic dicarboxylic acids; oxalic acid, succinic acid, malonic acid, glutaric acid, adipic acid, pimeric acid, suberic acid, azelaic acid, sebacic acid, decandicarboxylic acid, dodecanediocarboxylic acid, octadecanedicarboxylic acid, tartaric acid, alkylsuccinic acid , Linoleic acid, maleic acid, fumaric acid, mesaconic acid, citraconic acid, itaconic acid and other aliphatic dicarboxylic acids; hexahydrophthalic acid, tetrahydrophthalic acid, 1,3-cyclohexanedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, etc. Examples of the alicyclic dicarboxylic acid; or a reactive derivative of these acid anhydrides, alkyl esters, acid halides and the like. These may be used alone or in combination of two or more.

Examples of the polyol component include ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,3-butanediol, 1,4-butanediol, neopentyl glycol, pentanediol, and 1,6-hexanediol. , 1,8-octanediol, 1,10-decanediol, 1-methyl-1,3-butylene glycol, 2-methyl-1,3-butylene glycol, 1-methyl-1,4-pentylene glycol, 2 -Methyl-1,4-pentylene glycol, 1,2-dimethyl-neopentyl glycol, 2,3-dimethyl-neopentyl glycol, 1-methyl-1,5-pentylene glycol, 2-methyl-1,5 -Pentylene glycol, 3-methyl-1,5-pentylene glycol, 1,2-dimethylbutylene glycol, 1,3-dimethylbutylene glycol, 2,3-dimethylbutylene glycol, 1,4-dimethylbutylene glycol, diethylene glycol , Triethylene glycol, polyethylene glycol, dipropylene glycol, polypropylene glycol, 1,4-cyclohexanedimethanol, 1,4-cyclohexanediol, bisphenol A, bisphenol F, hydrogenated bisphenol A, hydrogenated bisphenol F and the like. These may be used alone or in combination of two or more.

The above-mentioned polyether polyol is typically obtained by ring-opening polymerization of an alkylene oxide on a polyhydric alcohol and adding it. Examples of the polyhydric alcohol include ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol, glycerin, and trimethylolpropane. Examples of the alkylene oxide include ethylene oxide, propylene oxide, butylene oxide, styrene oxide, and tetrahydrofuran. These may be used alone or in combination of two or more.

Examples of the polyisocyanate include tetramethylene diisocyanate, dodecamethylene diisocyanate, 1,4-butane diisocyanate, hexamethylene diisocyanate, 2,2,4-trimethylhexamethylene diisocyanate, 2,4,4-trimethylhexamethylene diisocyanate, and lysine. Aliphatic diisocyanates such as diisocyanate, 2-methylpentane-1,5-diisocyanate, 3-methylpentane-1,5-diisocyanate; isophorone diisocyanate, hydrogenated xylylene diisocyanate, 4,4'-cyclohexylmethane diisocyanate, 1,4 -Alicyclic diisocyanates such as cyclohexane diisocyanate, methylcyclohexamethylene diisocyanate, 1,3-bis (isocyanate methyl) cyclohexane; tolylene diisocyanate, 2,2'-diphenylmethane diisocyanate, 2,4'-diphenylmethane diisocyanate, 4,4' -Diphenylmethane diisocyanate, 4,4'-diphenyldimethylmethane diisocyanate, 4,4'-dibenzyldiisocyanate, 1,5-naphthylene diisocyanate, xylylene diisocyanate, 1,3-phenylenedi isocyanate, 1,4-phenylenediocyanate, etc. Aromatic diisocyanates; examples include aromatic aliphatic diisocyanates such as dialkyldiphenylmethane diisocyanate, tetraalkyldiphenylmethane diisocyanate, α, α, α, and α-tetramethylxylylene diisocyanate. These may be used alone or in combination of two or more.

The weight average molecular weight of the polyurethane resin is preferably 5000 to 600000, more preferably 1000 to 400000. The acid value of the polyurethane resin is preferably 10 or more, more preferably 10 to 50, and particularly preferably 20 to 45. In addition, in this specification, a weight average molecular weight can be measured by GPC (solvent: THF).

Examples of the styrene-based elastomer include styrene / butadiene / styrene triblock copolymer elastomer (SBS), styrene / isoprene / styrene triblock copolymer elastomer (SIS), and styrene-ethylene / butylene copolymer elastomer (SEB). ), Styrene-ethylene / propylene copolymer elastomer (SEP), styrene-ethylene / butylene-styrene copolymer elastomer (SEBS), styrene-ethylene / butylene-ethylene copolymer elastomer (SEBC), hydrogenated styrene / butadiene Elastomer (HSBR), Styrene-Ethene / Styrene-Styrene Copolymer Elastomer (SEPS), Styrene-Eethylene / Ethylene / Styrene-Styrene Copolymer Elastomer (SEEPS), Styrene-butadiene / Butylene-Styrene Copolymer Elastomer (SBBS) ) Etc. can be mentioned. Of these, SIS and SEBS are preferable.

In the styrene-based elastomer, the content ratio of the styrene-derived structural unit is preferably 30% by weight or less, and more preferably 20% by weight or less. Within such a range, an adhesive sheet having excellent elasticity can be obtained.

The weight average molecular weight of the styrene-based elastomer is preferably 10,000 to 500,000, more preferably 50,000 to 300,000. Within such a range, an adhesive sheet having excellent elasticity can be obtained.

The propylene-based elastomer is an elastomer containing a propylene-derived structural unit, and in one embodiment, is a copolymer containing a propylene-derived structural unit. In the propylene-based elastomer, the content ratio of the propylene-derived structural unit is preferably 30% by weight to 90% by weight, more preferably 50% by weight to 90% by weight. Within such a range, an adhesive sheet having excellent elasticity can be obtained.

Examples of other copolymerizing components constituting the propylene-based elastomer include ethylene, 1-butene, 2-methylpropylene, 1-pentene, 3-methyl-1-butene, 1-hexene and 4-methyl-1-. Examples thereof include structural units derived from monomers such as butene and 1-octene. Among them, ethylene, 1-butene, 1-pentene, 1-hexene, 1-octene and the like are preferable, and ethylene and 1-butene are particularly preferable. These may be used alone or in combination of two or more. In one embodiment, the propylene-based elastomer comprises a building block derived from ethylene. In the propylene-based elastomer, the content ratio of the ethylene-derived structural unit is preferably 5% by weight to 20% by weight, more preferably 8% by weight to 15% by weight.

The weight average molecular weight of the propylene-based elastomer is preferably 10,000 to 500,000, more preferably 50,000 to 300,000. Within such a range, an adhesive sheet having excellent elasticity can be obtained.

In one embodiment, the substrate has a single layer configuration.

In another embodiment, the substrate has a multi-layer structure. When the base material has a multi-layer structure, it is preferable that at least one of the layers constituting the base material contains a polyurethane-based resin, a styrene-based elastomer, or a propylene-based elastomer as described above. The total thickness of the layer containing the polyurethane resin, the styrene elastomer, or the propylene elastomer is preferably 50% or more, more preferably 70% or more, based on the total thickness of the base material.

In one embodiment, the substrate comprises a fatty acid amide. By containing the fatty acid amide, a base material having an appropriate slipperiness can be obtained. The pressure-sensitive adhesive sheet provided with the base material containing the fatty acid amide has excellent transportability and excellent grip on the stage of the expander, and can be satisfactorily stretched in the expanding step. When the base material has a multi-layer structure and the pressure-sensitive adhesive layer is arranged on one side of the base material, fatty acid amide is applied to at least the outermost layer of the base material located on the side opposite to the pressure-sensitive adhesive layer. It is preferable to include it.

Examples of the fatty acid amide include monoamides such as lauric acid amide, palmitic acid amide, stearic acid amide, bechenic acid amide, oleic acid amide, erucic acid amide, and hydroxystearic acid amide, ethylene bislauric acid amide, and ethylene bisstearic acid. Examples thereof include amides, ethylene bishydroxystearic acid amides, ethylene bisbechenic acid amides, hexamethylene bisstearic acid amides, ethylene bisoleic acid amides, hexamethylene bisoleic acid amides and the like. The fatty acid constituting the fatty acid amide-based lubricant preferably has 12 or more carbon atoms, more preferably 12 to 30 carbon atoms, and further preferably 14 to 28 carbon atoms.

In one embodiment, the fatty acid amide content is preferably 0.001 to 10 parts by weight, more preferably 0.01 to 3 parts by weight, based on 100 parts by weight of the substrate. is there.

In one embodiment, when the base material has a multi-layer structure and the pressure-sensitive adhesive layer is arranged on one side of the base material, fatty acids in the outermost layer of the base material located on the side opposite to the pressure-sensitive adhesive layer. The content ratio of the amide is preferably 0.001 part by weight to 10 parts by weight, and more preferably 0.01 part by weight to 3 parts by weight with respect to 100 parts by weight of the outermost layer.

The above-mentioned base material is held in an environment of 23 ° C. in a state where the base material is stretched by 150% under tension for 5 minutes, and the restoration rate when the tension is released is 80% or more based on the value before stretching. It is preferably 82% or more, more preferably 85% or more. The larger the restoration rate, the more preferable, but the upper limit is, for example, 95% (preferably 98%).

The elongation at break of the base material at 23 ° C. is preferably 10% or more, more preferably 250% or more, further preferably 250% to 1000%, and particularly preferably 250% to 800%.

The 25% modulus of the substrate at 23 ° C. is preferably 1N / 10mm to 100N / 10mm, more preferably 2N / 10mm to 60N / 10mm, and even more preferably 3N / 10mm to 30N / 10mm. In one embodiment, the 25% modulus of the substrate at 23 ° C. is 30 N / 10 mm or less. Within such a range, good expandability can be obtained.

The hardness of the base material measured according to JIS K 6253 is preferably 80A to 100A, more preferably 85A to 95A. Within such a range, good expandability can be obtained. In one embodiment, the polyurethane resin is used as the material constituting the base material, and the hardness of the base material is 80A to 100A (preferably 85A to 95A). In this way, the effect of the present invention becomes remarkable.

The thickness of the base material can be set to an arbitrary appropriate thickness depending on the desired strength or flexibility, the purpose of use, and the like. The thickness of the base material is preferably 1000 μm or less, more preferably 1 μm to 500 μm, further preferably 1 μm to 300 μm, particularly preferably 3 μm to 200 μm, and most preferably 5 μm to 100 μm.

The dynamic friction force of the base material with respect to the SUS304 plate on at least one surface is preferably 0.1N to 7.0N, more preferably 0.1N to 5.0N, and 0.1N to 3. It is more preferably 0N. The pressure-sensitive adhesive sheet provided with the base material having a coefficient of kinetic friction in such a range has excellent transportability and excellent grip on the stage of the expander, and can be satisfactorily stretched in the expanding step.

C. Adhesive Layer The adhesive layer is composed of any suitable adhesive. Adhesives include acrylic adhesives, silicone adhesives, vinyl alkyl ether adhesives, polyester adhesives, polyamide adhesives, urethane adhesives, fluorine adhesives, styrene-diene block copolymer adhesives. Examples thereof include agents and active energy ray-curable pressure-sensitive adhesives. In one embodiment, an acrylic pressure-sensitive adhesive is used.

The acrylic pressure-sensitive adhesive includes, for example, an acrylic pressure-sensitive adhesive based on an acrylic polymer (homopolymer or copolymer) using one or more (meth) acrylic acid alkyl esters as a monomer component. And so on. Specific examples of the (meth) acrylic acid alkyl ester include methyl (meth) acrylic acid, ethyl (meth) acrylic acid, propyl (meth) acrylic acid, isopropyl (meth) acrylic acid, butyl (meth) acrylic acid, and (meth). ) Isobutyl acrylate, s-butyl (meth) acrylate, t-butyl (meth) acrylate, pentyl (meth) acrylate, hexyl (meth) acrylate, heptyl (meth) acrylate, octyl (meth) acrylate , (Meta) 2-ethylhexyl acrylate, (meth) isooctyl acrylate, (meth) nonyl acrylate, (meth) isononyl acrylate, (meth) decyl acrylate, (meth) isodecyl acrylate, (meth) acrylate Undecyl, dodecyl (meth) acrylate, tridecyl (meth) acrylate, tetradecyl (meth) acrylate, pentadecyl (meth) acrylate, hexadecyl (meth) acrylate, heptadecyl (meth) acrylate, octadecyl (meth) acrylate , (Meta) acrylic acid nonadecil, (meth) acrylic acid eicosyl and the like (meth) acrylic acid C1-20 alkyl esters. Of these, (meth) acrylic acid alkyl esters having a linear or branched alkyl group having 4 to 18 carbon atoms can be preferably used.

The content ratio of the structural unit derived from the (meth) acrylic acid alkyl ester is preferably 50 parts by weight, more preferably 60 parts by weight or more, still more preferably 70 parts by weight, based on 100 parts by weight of the acrylic polymer. These are the above, and particularly preferably 80 parts by weight to 97 parts by weight.

The acrylic polymer contains a unit corresponding to another monomer copolymerizable with the (meth) acrylic acid alkyl ester, if necessary, for the purpose of modifying cohesive force, heat resistance, crosslinkability, etc. You may. Examples of such monomers include carboxyl group-containing monomers such as acrylic acid, methacrylic acid, carboxyethyl acrylate, carboxypentyl acrylate, itaconic acid, maleic acid, fumaric acid, and crotonic acid; acids such as maleic anhydride and icotanic anhydride. Anhydrous monomer; hydroxyethyl (meth) acrylate, hydroxypropyl (meth) acrylate, hydroxybutyl (meth) acrylate, hydroxyhexyl (meth) acrylate, hydroxyoctyl (meth) acrylate, hydroxy (meth) acrylate Hydroxyl group-containing monomers such as decyl, hydroxylauryl (meth) acrylate, (4-hydroxymethylcyclohexyl) methylmethacrylate; styrene sulfonic acid, allyl sulfonic acid, 2- (meth) acrylamide-2-methylpropansulfonic acid, (meth). ) Sulfonic acid group-containing monomers such as acrylamide propanesulfonic acid, sulfopropyl (meth) acrylate, (meth) acryloyloxynaphthalene sulfonic acid; (meth) acrylamide, N, N-dimethyl (meth) acrylamide, N-butyl (meth) (N-substituted) amide-based monomers such as acrylamide, N-methylol (meth) acrylamide, N-methylolpropane (meth) acrylamide; aminoethyl (meth) acrylate, N, N-dimethylaminoethyl (meth) acrylate, (Meta) Aminoalkyl Acrylate Monomer such as t-butylaminoethyl (meth) Acrylic Acid; (Meth) Aluminoxyalkyl Acrylic Acid Monomer such as methoxyethyl (Meta) Acrylic Acid, ethoxyethyl (Meta) Acrylic Acid; N Maleimide-based monomers such as −cyclohexyl maleimide, N-isopropyl maleimide, N-lauryl maleimide, N-phenylmaleimide; N-methylitaconimide, N-ethylitaconimide, N-butylitaconimide, N-octylitaconimide, N- Itaconimide-based monomers such as 2-ethylhexylitaconimide, N-cyclohexylitaconimide, N-laurylitaconimide; N- (meth) acryloyloxymethylene succinimide, N- (meth) accurloyl-6-oxyhexamethylene succinimide, N-( Meta) Succinimide-based monomers such as acryloyl-8-oxyoctamethylene succinimide; vinyl acetate, vinyl propionate, N-vinylpyrrolidone, methylvinylpyrroli Vinyls such as don, vinylpyridine, vinylpiperidone, vinylpyrimidine, vinylpiperazin, vinylpyrazine, vinylpyrrole, vinylimidazole, vinyloxazole, vinylmorpholin, N-vinylcarboxylic acid amides, styrene, α-methylstyrene, N-vinylcaprolactam Monomer; Cyanoacrylate monomer such as acrylonitrile and methacrylonitrile; Epoxy group-containing acrylic monomer such as glycidyl (meth) acrylate; Polyethylene glycol (meth) acrylate, Polypropylene glycol (meth) acrylate, (meth) acrylic acid Glycol-based acrylic ester monomers such as methoxyethylene glycol and methoxypolypropylene glycol (meth) acrylate; heterocycles such as tetrahydrofurfuryl (meth) acrylate, fluorine (meth) acrylate and silicone (meth) acrylate, halogen atoms and silicon atoms. Acrylic acid ester-based monomers having the above; hexanediol di (meth) acrylate, (poly) ethylene glycol di (meth) acrylate, (poly) propylene glycol di (meth) acrylate, neopentyl glycol di (meth) acrylate, pentaerythritol Polyfunctional monomers such as di (meth) acrylate, trimethylolpropantri (meth) acrylate, pentaerythritol tri (meth) acrylate, dipentaerythritol hexa (meth) acrylate, epoxy acrylate, polyester acrylate, urethane acrylate; isoprene, butadiene, Olefin-based monomers such as isobutylene; vinyl ether-based monomers such as vinyl ether and the like can be mentioned. These monomers may be used alone or in combination of two or more.

In one embodiment, the acrylic polymer comprises a monomer-derived structural unit having a polar functional group. When the base material contains a fatty acid amide, if an acrylic polymer containing a structural unit derived from a monomer having a polar functional group is used, the transfer of the fatty acid amide to the pressure-sensitive adhesive layer can be prevented, and the pressure-sensitive adhesive sheet has excellent durability. Can be obtained. The content ratio of the structural unit derived from the monomer having a polar functional group is preferably 0.01 parts by weight to 40 parts by weight, and more preferably 1 part by weight to 30 parts by weight with respect to 100 parts by weight of the acrylic polymer. It is more preferably 2 parts by weight to 20 parts by weight, and particularly preferably 3 parts by weight to 15 parts by weight. Examples of the polar functional group include a carboxyl group and a hydroxyl group.

In one embodiment, (meth) acrylic acid can be used as the monomer having a polar functional group. In this embodiment, the content ratio of the structural unit derived from (meth) acrylic acid is preferably 1 part by weight to 40 parts by weight, more preferably 1 part by weight to 20 parts by weight, based on 100 parts by weight of the acrylic polymer. Parts, more preferably 1 part by weight to 10 parts by weight.

The pressure-sensitive adhesive may optionally contain any suitable additive. Examples of the additive include an initiator, a cross-linking agent, a tackifier, a plasticizer, a pigment, a dye, a filler, an antiaging agent, a conductive material, an antistatic agent, an ultraviolet absorber, a light stabilizer, and a peeling conditioner. , Softeners, surfactants, flame retardants, antioxidants and the like.

In one embodiment, the pressure-sensitive adhesive comprises a cross-linking agent.

Examples of the cross-linking agent include isocyanate-based cross-linking agents, epoxy-based cross-linking agents, melamine-based cross-linking agents, peroxide-based cross-linking agents, urea-based cross-linking agents, metal alkoxide-based cross-linking agents, metal chelate-based cross-linking agents, and metals. Examples thereof include salt-based cross-linking agents, carbodiimide-based cross-linking agents, oxazoline-based cross-linking agents, aziridine-based cross-linking agents, and amine-based cross-linking agents. Of these, an isocyanate-based cross-linking agent or an epoxy-based cross-linking agent is preferable.

Specific examples of the isocyanate-based cross-linking agent include lower aliphatic polyisocyanates such as butylene diisocyanate and hexamethylene diisocyanate; alicyclic isocyanates such as cyclopentylene diisocyanate, cyclohexylene diisocyanate and isophorone diisocyanate; 2,4- Aromatic isocyanates such as tolylene diisocyanate, 4,4'-diphenylmethane diisocyanate, xylylene diisocyanate; trimethylolpropane / tolylene diisocyanate trimer adduct (manufactured by Nippon Polyurethane Industry Co., Ltd., trade name "Coronate L") Methylolpropane / hexamethylene diisocyanate trimeric adduct (manufactured by Nippon Polyurethane Industry Co., Ltd., trade name "Coronate HL"), isocyanurate of hexamethylene diisocyanate (manufactured by Japan Polyurethane Industry Co., Ltd., trade name "Coronate HX"), etc. Isocyanate adduct; etc. The content of the isocyanate-based cross-linking agent can be set to an arbitrary appropriate amount according to the desired adhesive strength, elasticity of the pressure-sensitive adhesive layer, etc., and is typically 0. It is 1 part by weight to 20 parts by weight, more preferably 0.5 part by weight to 10 parts by weight.

Examples of the epoxy-based cross-linking agent include N, N, N', N'-tetraglycidyl-m-xylene diamine, diglycidyl aniline, and 1,3-bis (N, N-glycidyl aminomethyl) cyclohexane (Mitsubishi Gas). Chemical Co., Ltd., trade name "Tetrad C"), 1,6-hexanediol diglycidyl ether (Kyoeisha Chemical Co., Ltd., trade name "Epolite 1600"), neopentyl glycol diglycidyl ether (Kyoeisha Chemical Co., Ltd., trade name " Epolite 1500NP "), ethylene glycol diglycidyl ether (manufactured by Kyoeisha Chemical Co., Ltd., trade name" Epolite 40E "), propylene glycol diglycidyl ether (manufactured by Kyoeisha Chemical Co., Ltd., trade name" Epolite 70P "), polyethylene glycol diglycidyl ether (Japan Oil and fat company, product name "Epiol E-400"), polypropylene glycol diglycidyl ether (Japan Oil and Fat Co., product name "Epiol P-200"), sorbitol polyglycidyl ether (manufactured by Nagase ChemteX, product name "Denacol" EX-611 "), glycerol polyglycidyl ether (manufactured by Nagase ChemteX, trade name" Denacol EX-314 "), pentaerythritol polyglycidyl ether, polyglycerol polyglycidyl ether (manufactured by Nagase Chemtex, trade name" Denacol EX ") -512 "), sorbitan polyglycidyl ether, trimethylolpropane polyglycidyl ether, adipate diglycidyl ester, o-phthalic acid diglycidyl ester, triglycidyl-tris (2-hydroxyethyl) isocyanurate, resorcin diglycidyl ether, bisphenol Examples thereof include −S—diglycidyl ether and epoxy resins having two or more epoxy groups in the molecule. The content of the epoxy-based cross-linking agent can be set to an arbitrary appropriate amount according to the desired adhesive strength, elasticity of the pressure-sensitive adhesive layer, etc., and is typically 0. It is 01 parts by weight to 10 parts by weight, more preferably 0.03 parts by weight to 5 parts by weight.

The thickness of the pressure-sensitive adhesive layer is preferably 1 μm to 50 μm, more preferably 1 μm to 30 μm, and further preferably 2 μm to 20 μm.

The elastic modulus of the pressure-sensitive adhesive layer by the nanoindentation method is preferably 0.005 to 5 MPa, more preferably 0.01 to 2 MPa. Within such a range, an adhesive layer that does not easily inhibit the elasticity of the base material can be formed, and the effect of the present invention becomes more remarkable. In addition, a pressure-sensitive adhesive layer having an appropriate adhesive strength can be formed. The elastic modulus can be adjusted, for example, by the composition of the pressure-sensitive adhesive contained in the pressure-sensitive adhesive layer; the type of resin material used as the base polymer of the pressure-sensitive adhesive, the molecular weight, the degree of cross-linking, and the like. The elastic modulus according to the nanoindentation method refers to the load on the indenter and the pushing depth when the indenter is pushed into the sample (where the thermally expandable microspheres do not exist) continuously during loading and unloading. It is obtained from the obtained load-push depth curve. In the present specification, the elastic modulus by the nanoindentation method is measured as described above under the measurement conditions of load: 1 mN, load / unloading speed: 0.1 mN / s, holding time: 1s, and environmental temperature: 23 ° C. The elastic modulus.

D. Method for Producing Adhesive Sheet The adhesive sheet of the present invention can be produced by any suitable method. The pressure-sensitive adhesive sheet of the present invention can be obtained by forming a pressure-sensitive adhesive layer on a base material. Examples of the method for forming the pressure-sensitive adhesive layer include a method of applying a pressure-sensitive adhesive on a base material, and a method of transferring a coating layer formed by applying a pressure-sensitive adhesive on an arbitrary suitable film to an intermediate layer. And so on.

Any suitable coating method can be adopted as the coating method of the pressure-sensitive adhesive. For example, each layer can be formed by applying and then drying. Examples of the coating method include a coating method using a multi-coater, a die coater, a gravure coater, an applicator, and the like. Examples of the drying method include natural drying and heat drying.

E. Applications The adhesive sheet of the present invention can be suitably used as a sheet for temporarily fixing an electronic component material when manufacturing an electronic component. In one embodiment, the pressure-sensitive adhesive sheet of the present invention can be used as a pressure-sensitive adhesive sheet for chip pickup. It is used as a temporary fixing sheet when cutting electronic component materials. Examples of the electronic component material include semiconductor chips, LED chips, ceramic capacitors and the like.

Hereinafter, the present invention will be specifically described with reference to Examples, but the present invention is not limited to these Examples. The evaluation method in the examples is as follows. In the following evaluation, an adhesive sheet from which the separator was peeled off was used. Further, in the examples, unless otherwise specified, "parts" and "%" are based on weight.

(1) Restoration rate For the adhesive sheet piece having a width of 10 mm and a length of 100 _{mm, a marked line with an initial score distance L 0} = 50 mm was drawn in the length direction. Under an environmental temperature of 23 ° C., it was set in a tensile tester at a distance between chucks of 70 mm, stretched to 150% (distance between chucks: 145 mm) at a tensile speed of 300 mm / min, held in an stretched state for 5 minutes, and then stretched. The distance L ₁ was measured. After that, the tension was released and the distance L between the scores was measured 5 minutes later, and the restoration rate (%) was calculated by the following formula.
Restoration rate (%) = {(distance between extended grades L _1- distance between grades L) / (distance between extended grades L _1- distance between initial grades L ₀ )} × 100
The recovery rate was measured for two samples in a predetermined direction I and a direction II orthogonal to the direction I.
Further, the pressure-sensitive adhesive sheet was expanded and contracted by the above method under an environmental temperature of 40 ° C. to determine the restoration rate.

(2) Dynamic friction force Adhesive tape is attached on the table so that the base film surface faces up, and a SUS304 plate (weight 200 g, 63 mm x 63 mm) is placed on it so as to come into contact with the base film surface. The SUS304 plate was moved (100 mm / min) on the surface of the base film, and the average load (N) generated at that time was measured and used as the dynamic friction force.

[Example 1]
100 parts by weight of acrylic polymer composed of 2-ethylhexyl acrylate (2EHA) / acrylic acid (AA) = 90/10 (weight ratio), polyisocyanate-based cross-linking agent (trade name "Coronate L", manufactured by Nippon Polyurethane Co., Ltd.) A pressure-sensitive adhesive containing 5 parts by weight, 0.05 parts by weight of a glycidylamine-based cross-linking agent (trade name “TETRAD-C”, manufactured by Mitsubishi Gas Chemicals, Inc.), and ethyl acetate was prepared. This adhesive is applied to the peeled surface of a 38 μm-thick polyester film (trade name: MRF, manufactured by Mitsubishi Chemical Polyester Co., Ltd.) whose one side is peeled with silicone, and heated at 120 ° C. for 2 minutes to achieve the thickness. A 20 μm pressure-sensitive adhesive layer was formed. Next, the pressure-sensitive adhesive layer surface was transferred to a polyurethane-based film A (thickness: 70 μm, manufactured by Oishi Sangyo Co., Ltd.) containing 0.1 parts by weight of stearic acid amide as a base material, and stored at 50 ° C. for 48 hours for adhesion. I got a sheet.
The obtained adhesive sheet was subjected to the evaluations of (1) and (2) above. The results are shown in Table 1.

[Example 2]
An adhesive sheet was obtained in the same manner as in Example 1 except that a polyurethane film B (thickness: 60 μm, manufactured by Nihon Matai Co., Ltd.) was used as the base material.
The obtained adhesive sheet was subjected to the evaluations of (1) and (2) above. The results are shown in Table 1.

[Example 3]
Adhesive in the same manner as in Example 1 except that a polypropylene-based elastomer (PP elastomer) film (thickness: 100 μm, manufactured by Nitto Denko KK) containing 0.05 parts by weight of stearic acid amide was used as the base material. I got a sheet.
The obtained adhesive sheet was subjected to the evaluations of (1) and (2) above. The results are shown in Table 1.

[Example 4]
Laminated body made of polyethylene (PE; thickness: 10 μm) / styrene elastomer (St elastomer; thickness: 60 μm) film / polyethylene (thickness: 10 μm) as a base material (thickness: 80 μm, manufactured by Nihon Matai Co., Ltd.) An adhesive sheet was obtained in the same manner as in Example 1 except that the above was used.
The obtained adhesive sheet was subjected to the evaluations of (1) and (2) above. The results are shown in Table 1.

[Example 5]
A laminate (thickness) composed of an ethylene-vinyl acetate copolymer film (EVA; thickness: 10 μm) / styrene-based elastomer film (thickness: 60 μm) / ethylene-vinyl acetate copolymer film (thickness: 10 μm) as a base material. An adhesive sheet was obtained in the same manner as in Example 1 except that 80 μm (manufactured by Nihon Matai Co., Ltd.) was used.
The obtained adhesive sheet was subjected to the evaluations of (1) and (2) above. The results are shown in Table 1.

[Comparative Example 1]
An adhesive sheet was obtained in the same manner as in Example 1 except that a polyvinyl chloride film (PVC; thickness: 70 μm, manufactured by Diaplus) containing 0.7 parts by weight of stearic acid amide was used as a base material. ..
The obtained adhesive sheet was subjected to the evaluations of (1) and (2) above. The results are shown in Table 1.

[Comparative Example 2]
An adhesive sheet was obtained in the same manner as in Example 1 except that a polyethylene film (PE; thickness: 100 μm, manufactured by Nitto Denko KK) was used as a base material.
The obtained adhesive sheet was subjected to the evaluations of (1) and (2) above. The results are shown in Table 1.

[Comparative Example 3]
Example 1 except that a laminate (thickness: 80 μm, manufactured by Okura Industrial Co., Ltd.) made of polypropylene film (PP; thickness: 55 μm) / polyethylene film (PE; thickness: 25 μm) was used as the base material. An adhesive sheet was obtained in the same manner as above.
The obtained adhesive sheet was subjected to the evaluations of (1) and (2) above. The results are shown in Table 1.

[Comparative Example 4]
An adhesive sheet was obtained in the same manner as in Example 1 except that an ethylene-vinyl acetate copolymer film (thickness: 100 μm, manufactured by Nitto Denko KK) was used as a base material.
The obtained adhesive sheet was subjected to the evaluations of (1) and (2) above. The results are shown in Table 1.

As shown in Table 1, according to the present invention, an adhesive sheet having a high restoration rate can be obtained. When such an adhesive sheet is used for picking up chips, when a plurality of chips arranged on the adhesive sheet are picked up in several times, the adhesive sheet is stretched at the time of picking up, and a part of the adhesive sheet is extended. The chips can be picked up well, after which the adhesive sheet shrinks and restores to achieve good storage.

10 Base material 20 Adhesive layer 100 Adhesive sheet

Claims (8)

A pressure-sensitive adhesive sheet comprising a base material and a pressure-sensitive adhesive layer arranged on at least one side of the base material.
In an environment of 23 ° C., the pressure-sensitive adhesive sheet is held for 5 minutes in a state of being stretched by 150% under tension, and the dimensional restoration rate when the tension is released is 80% or more based on the pressure-sensitive adhesive sheet before stretching. Is,
Adhesive sheet. The pressure-sensitive adhesive sheet according to claim 1, wherein the base material contains a fatty acid amide. The pressure-sensitive adhesive sheet according to claim 2, wherein the content ratio of the fatty acid amide is 0.001 part by weight to 10 parts by weight with respect to 100 parts by weight of the base material. The pressure-sensitive adhesive sheet according to any one of claims 1 to 3, wherein the pressure-sensitive adhesive layer contains an acrylic pressure-sensitive adhesive. The pressure-sensitive adhesive sheet according to claim 4, wherein the acrylic pressure-sensitive adhesive contains an acrylic polymer containing a structural unit derived from a monomer having a polar functional group. The pressure-sensitive adhesive sheet according to claim 5, wherein the content ratio of the monomer having a polar functional group is 0.01 part by weight to 40 parts by weight with respect to 100 parts by weight of the acrylic polymer. The pressure-sensitive adhesive sheet according to claim 5, wherein the monomer having a polar functional group is (meth) acrylic acid. The pressure-sensitive adhesive sheet according to claim 8, wherein the content ratio of the (meth) acrylic acid is 1 part by weight to 20 parts by weight with respect to 100 parts by weight of the (meth) acrylic polymer.

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