CN108307635B - Adhesive tape for processing workpiece - Google Patents

Abstract

The adhesive tape for processing workpieces comprises a base material and an adhesive layer provided on one surface side of the base material, wherein the adhesive layer comprises a urethane resin (A) and an energy ray-curable compound (B) which does not react with the urethane resin (A), has a photopolymerizable unsaturated bond, and has a molecular weight of 35,000 or less.

Description

Adhesive tape for processing workpiece

Technical Field

The present invention relates to an adhesive tape for processing a work, and more particularly to an adhesive tape for protecting a surface of a semiconductor wafer with bumps, which is used for protecting the surface of the semiconductor wafer with bumps.

Background

In the rapid progress of the reduction in thickness, size, and multi-functionalization of information terminal devices, semiconductor devices mounted therein are also required to be reduced in thickness and increased in density, and reduction in thickness of semiconductor wafers is also desired. In order to meet this demand, grinding of the back surface of a semiconductor wafer to reduce the thickness thereof has been studied. In recent years, bumps made of solder or the like having a height of about 30 to 100 μm are sometimes formed on the surface of a semiconductor wafer. When such a bumped semiconductor wafer is subjected to back grinding, a surface protective sheet may be attached to the surface of the wafer on which the bumps are formed in order to protect the bump portions.

Conventionally, as a surface protection sheet, a surface protection sheet including a resin layer having storage moduli adjusted to specific ranges at 25 ℃ and 60 ℃ is known (for example, see patent document 1). The surface protection sheet is provided with a resin layer having a difference between the storage modulus at room temperature (25 ℃) and the storage modulus at high temperature (60 ℃), and thus, by being stuck to the surface of a wafer having concave-convex portions at high temperature, the resin layer is softened, and the concave-convex portions on the surface of the wafer are absorbed, thereby reducing the height difference on the surface of the wafer.

Further, as a surface protection sheet, there is known a surface protection sheet in which 2 resin layers having a predetermined tensile elastic modulus are provided on a substrate in order to improve adhesion and peelability, and of the 2 resin layers, the resin layer on the adhesion surface side is formed of a thermoplastic elastomer such as a polystyrene elastomer, a polyolefin elastomer, a polyurethane elastomer, or a polyester elastomer (see patent document 2).

As a surface protective sheet, an adhesive tape having an intermediate layer and an adhesive layer on one surface of a substrate is known. In this adhesive tape, in order to improve the uneven absorption, the storage modulus at 25 ℃ of the intermediate layer is set to about 30 to 1000kPa, and the adhesive layer is formed by an energy ray-curable adhesive (for example, see patent document 3). When an energy ray-curable pressure-sensitive adhesive is used for the surface protective sheet as in patent document 3, the adhesiveness to and peelability from a semiconductor wafer are easily improved. Conventionally, an acrylic pressure-sensitive adhesive has been mainly used as an energy ray-curable pressure-sensitive adhesive used for a surface protective sheet in order to easily adjust adhesiveness and easily ensure embedding of bumps.

Documents of the prior art

Patent document

Patent document 1: japanese patent No. 4603578

Patent document 2: japanese patent No. 4918181

Patent document 3: japanese patent No. 4367769

Disclosure of Invention

Problems to be solved by the invention

However, in recent years, with further densification and miniaturization of semiconductor devices, the bump height tends to increase, and studies have been made on bumps having a height of 200 μm or more. However, in the case of a semiconductor wafer in which the height difference is increased by increasing the height of the bumps, if the acrylic surface protective sheet described in patent document 3 is used, a large amount of adhesive residue (residual paste) may be generated on the bumps when the sheet is peeled off. This is because the acrylic energy ray-curable adhesive has a low cohesive force and mechanical strength.

On the other hand, for example, in patent documents 1 and 2, it has been studied to use a material other than an acrylic pressure-sensitive adhesive such as a urethane elastomer on the sticking surface of the surface protective sheet. However, in patent documents 1 and 2, application of these materials to an energy ray-curable adhesive is not examined, and further improvement is required to ensure adhesiveness, peelability, and embedding of bumps.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a pressure-sensitive adhesive tape for processing a workpiece, which not only has good adhesion to a workpiece such as a semiconductor wafer, peelability, and following ability of a pressure-sensitive adhesive layer to a surface shape of the workpiece (represented by embeddability of bumps), but also has little residual paste on the surface of the workpiece even if the surface shape of the workpiece to be bonded is uneven.

Means for solving the problems

As a result of intensive studies, the present inventors have found that the above problems can be solved by using a urethane-based binder as a binder and setting the composition to a specific composition, and have completed the following invention. The present invention provides the following (1) to (16) pressure-sensitive adhesive tapes for workpiece processing.

(1) An adhesive tape for processing a workpiece, comprising a base material and an adhesive layer provided on one surface side of the base material,

the adhesive layer contains a urethane resin (A) and an energy ray-curable compound (B) which does not react with the urethane resin (A), has a photopolymerizable unsaturated bond, and has a molecular weight of 35,000 or less.

(2) The adhesive tape for processing a workpiece described in the above (1), wherein the energy ray-curable compound (B) is at least 1 selected from a (meth) acrylate monomer (B1) and a urethane (meth) acrylate (B2).

(3) The adhesive tape for processing a workpiece described in (2), wherein the energy ray-curable compound (B) contains at least a (meth) acrylate monomer (B1), and the (meth) acrylate monomer (B1) is a polyfunctional (meth) acrylate which is a complete esterified product of a polyol and a (meth) acrylic acid.

(4) The adhesive tape for processing a workpiece according to any one of (1) to (3), wherein the energy ray-curable compound (B) has 2 or more (meth) acryloyl groups in 1 molecule.

(5) The adhesive tape for processing a workpiece according to any one of (1) to (4), wherein the urethane resin (a) has a photopolymerizable unsaturated bond.

(6) The adhesive tape for processing a workpiece according to any one of (1) to (5) above, wherein the adhesive layer is formed from an adhesive composition containing at least a urethane polymer (A'), the energy ray-curable compound (B), and a crosslinking agent (C),

the urethane resin (A) is obtained by crosslinking a urethane polymer (A') with the crosslinking agent (C).

(7) The adhesive tape for processing a workpiece described in (6) above, wherein the crosslinking agent (C) comprises a crosslinking agent (C1) containing a photopolymerizable unsaturated bond.

(8) The adhesive tape for processing a workpiece described in (6) or (7), wherein the urethane polymer (a') and the crosslinking agent (C) are bonded via a urethane bond.

(9) The adhesive tape for processing a workpiece according to any one of (6) to (8), wherein the adhesive composition further contains a compound (D) having a photopolymerizable unsaturated bond and a reactive functional group capable of reacting with the crosslinking agent (C).

(10) The adhesive tape for processing a workpiece described in (9), wherein the compound (D) is a polyfunctional (meth) acrylate which is a partially esterified product of a polyol and (meth) acrylic acid.

(11) The adhesive tape for processing a workpiece according to any one of (1) to (10) above, wherein the adhesive layer has a breaking stress of 2.5MPa or more after irradiation with an energy ray.

(12) The adhesive tape for processing a workpiece according to any one of (1) to (11), wherein an intermediate layer is provided between the substrate and the adhesive layer.

(13) The adhesive tape for processing a workpiece described in (12) above, wherein the thickness of the intermediate layer is 10 to 600 μm.

(14) The adhesive tape for processing a workpiece described in (12) or (13), wherein the intermediate layer has a loss tangent at 50 ℃ of 1.0 or more as measured at a frequency of 1 Hz.

(15) The pressure-sensitive adhesive tape for processing a workpiece described in any one of (1) to (14) above, which has an adhesive force after irradiation with an energy ray of 2000mN/25mm or less.

(16) The adhesive tape for processing a workpiece according to any one of (1) to (15) above, which is an adhesive tape for protecting a surface of a semiconductor wafer.

ADVANTAGEOUS EFFECTS OF INVENTION

The invention can provide an adhesive tape for processing a workpiece, which has good adhesiveness, releasability and following property of an adhesive layer to the surface shape of the workpiece, and has less residual paste on the surface of the workpiece.

Detailed Description

In the following description, "weight average molecular weight (Mw)" is a value in terms of polystyrene measured by a Gel Permeation Chromatography (GPC) method, specifically, a value measured by the method described in examples.

In the description of the present specification, for example, "(meth) acrylate" is used as a term indicating both "acrylate" and "methacrylate", and other similar terms are treated in the same manner.

The present invention will be described below with reference to embodiments.

The pressure-sensitive adhesive tape for processing a workpiece (hereinafter, also simply referred to as "pressure-sensitive adhesive tape") of the present invention includes a base material and a pressure-sensitive adhesive layer provided on one surface side of the base material. In addition, the adhesive tape may have an intermediate layer between the substrate and the adhesive layer. The adhesive tape may be composed of 2 or 3 layers as described above, and other layers may be provided. For example, a release material may be further provided on the adhesive layer.

Hereinafter, each member constituting the adhesive tape will be described in detail.

< substrate >

The substrate used for the adhesive tape is not particularly limited, and is preferably a resin film. The resin film is preferable because it is suitable for a processing member of an electronic component and is easily available, because it generates less dust as compared with paper or nonwoven fabric. The substrate may be a single-layer film formed of one resin film or a multilayer film formed by laminating a plurality of resin films.

As the resin film used as the substrate, for example: polyolefin film, vinyl halide polymer film, acrylic resin film, rubber film, cellulose film, polyester film, polycarbonate film, polystyrene film, polyphenylene sulfide film, cycloolefin polymer film, and the like.

Among these, a polyester-based film is preferable from the viewpoint of stably holding the wafer even when the wafer is ground to be extremely thin and from the viewpoint of being a film having high thickness accuracy, and a polyethylene terephthalate film is preferable among the polyester-based films from the viewpoint of being easily available and having high thickness accuracy.

The thickness of the base material is not particularly limited, but is preferably 10 to 200. mu.m, and more preferably 25 to 150. mu.m.

In order to improve the adhesion of the substrate to the adhesive layer or the intermediate layer, a substrate in which an easy-adhesion layer or an adhesive layer is further laminated on the surface of the resin film may be used. The base material used in the present invention may further contain a filler, a colorant, an antistatic agent, an antioxidant, an organic lubricant, a catalyst, and the like, as long as the effects of the present invention are not impaired. The substrate may be transparent or colored as desired, and is preferably a substrate that transmits energy rays to a sufficient extent to cure the pressure-sensitive adhesive layer.

< intermediate layer >

The adhesive tape of the present invention may be provided with an intermediate layer on one side of the substrate. By providing the adhesive tape of the present invention with the intermediate layer, even when the difference in level of the unevenness of the surface of the workpiece such as a bump is large, the protruding portion can be embedded in the adhesive layer and the intermediate layer, and thus the surface of the adhesive tape opposite to the surface to be bonded to the workpiece can be easily kept flat. The loss tangent (tan δ) (hereinafter, also simply referred to as "loss tangent") at 50 ℃ of the intermediate layer used in the present invention, measured at a frequency of 1Hz, is preferably 1.0 or more.

If the loss tangent of the intermediate layer has such a value, the intermediate layer can be sufficiently deformed and can easily follow irregularities when the adhesive tape for workpiece processing is attached to a workpiece having irregularities, such as a bumped wafer. The loss tangent of the intermediate layer is more preferably 1.5 or more, more preferably 1.65 or more, and even more preferably 1.8 or more, from the viewpoint of sufficiently absorbing unevenness of bumps or the like in the intermediate layer, for example, obtaining a good bonding state to the surface of the bumped wafer.

From the viewpoint of adjusting the fluidity of the intermediate layer during heating to an appropriate range, the loss tangent of the intermediate layer is preferably 5.0 or less, and more preferably 4.0 or less.

More specifically, the loss tangent of the intermediate layer is a value measured by a method described in examples described later.

The thickness of the intermediate layer can be appropriately adjusted depending on the state of the surface to be bonded to which the adhesive tape is bonded, and is preferably 10 to 600 μm, more preferably 25 to 550 μm, and still more preferably 35 to 500 μm, from the viewpoint of absorbing a bump having a high height.

The intermediate layer is formed using the resin composition for an intermediate layer. The resin composition for the intermediate layer preferably contains urethane (meth) acrylate.

(urethane (meth) acrylate (X))

The urethane (meth) acrylate (X) is a compound having at least a (meth) acryloyl group and a urethane bond, and has a property of being polymerized by irradiation with an energy ray. The energy ray is a ray having an energy quantum (energy quanta) in an electromagnetic wave or a charged particle beam, and is active light such as ultraviolet ray, an electron ray, or the like.

The number of (meth) acryloyl groups in the urethane (meth) acrylate (X) may be monofunctional, 2-functional or 3-functional or more, and the resin composition for the intermediate layer preferably contains a monofunctional urethane (meth) acrylate in order to easily achieve a loss tangent of 1.0 or more. This is because the monofunctional urethane (meth) acrylate does not contribute to formation of a three-dimensional network structure in the polymer structure, and it is difficult to form a three-dimensional network structure in the intermediate layer, and thus the loss tangent is easily increased.

The urethane (meth) acrylate (X) used as the resin composition for the intermediate layer can be obtained, for example, by reacting a compound having a (meth) acryloyl group with a terminal isocyanate urethane prepolymer obtained by reacting a polyol compound with a polyisocyanate compound. The urethane (meth) acrylate (X) may be used in 1 kind, or 2 or more kinds may be used in combination.

[ polyol compound ]

The polyol compound is not particularly limited as long as it is a compound having 2 or more hydroxyl groups.

Specific examples of the polyol compound include: alkylene glycol, polyether polyol, polyester polyol, polycarbonate polyol and the like.

Among them, polyether polyols are preferred.

The polyol compound may be any of a 2-functional diol, a 3-functional triol, and a 4-or higher-functional polyol, and from the viewpoint of availability, versatility, reactivity, and the like, a 2-functional diol is preferred, and a polyether diol is more preferred.

The polyether diol is preferably a compound represented by the following formula (1).

[ chemical formula 1]

In the formula (1), R is a 2-valent hydrocarbon group, preferably an alkylene group, and more preferably an alkylene group having 1 to 6 carbon atoms. Among alkylene groups having 1 to 6 carbon atoms, ethylene, propylene and tetramethylene groups are preferable, and propylene and tetramethylene groups are more preferable.

In addition, n is the number of repeating units of alkylene oxide, preferably 10 to 250, more preferably 25 to 205, and further preferably 40 to 185. When n is in the above range, the urethane bond concentration of the obtained urethane (meth) acrylate can be made appropriate, the intermediate layer can be easily produced, and the loss tangent can satisfy the above requirements.

Among the compounds represented by the above formula (1), polyethylene glycol, polypropylene glycol and polytetramethylene glycol are preferable, and polypropylene glycol and polytetramethylene glycol are more preferable.

By the reaction of the polyether diol with the polyisocyanate compound, a terminal isocyanate urethane prepolymer having an ether bond portion (— R-O-) n-) introduced thereinto is produced. By using such polyether diol, urethane (meth) acrylate contains a structural unit derived from the polyether diol.

The polyester polyol is obtained by polycondensation of a polyol component and a polybasic acid component. As the polyol component, there can be mentioned: and known various glycols such as ethylene glycol, diethylene glycol, triethylene glycol, 1, 2-propanediol, 1, 3-butanediol, 1, 4-butanediol, neopentyl glycol, pentanediol, 3-methyl-1, 5-pentanediol, 2, 4-trimethyl-1, 3-pentanediol, hexanediol, octanediol, 2-diethyl-1, 3-propanediol, 2-ethyl-2-butyl-1, 3-propanediol, 1, 4-cyclohexanedimethanol, and ethylene glycol or propylene glycol adducts of bisphenol a.

As the polybasic acid component used for the production of the polyester polyol, a compound generally known as a polybasic acid component of a polyester can be used.

Specific examples of the polybasic acid component include: dibasic acids such as adipic acid, maleic acid, succinic acid, oxalic acid, fumaric acid, malonic acid, glutaric acid, pimelic acid, azelaic acid, sebacic acid, suberic acid, and the like; dibasic acids such as phthalic acid, isophthalic acid, terephthalic acid, and 2, 6-naphthalenedicarboxylic acid, aromatic polybasic acids such as trimellitic acid and pyromellitic acid, anhydrides corresponding to these acids, derivatives thereof, dimer acid, and hydrogenated dimer acid. Among them, aromatic polybasic acids are preferable from the viewpoint of forming a coating film having an appropriate hardness. In the esterification reaction for producing the polyester polyol, various known catalysts may be used as necessary.

The polycarbonate-type polyol is not particularly limited, and examples thereof include a reaction product of the above-mentioned diol and an alkylene carbonate.

The number average molecular weight calculated from the hydroxyl value of the polyol compound is preferably 1,000 to 10,000, more preferably 2,000 to 9,000, and still more preferably 3,000 to 7,000. When the number average molecular weight is 1,000 or more, it is preferable to avoid the case where it is difficult to control the viscoelastic properties of the intermediate layer due to the formation of an excessive urethane bond. On the other hand, when the number average molecular weight is 10,000 or less, the intermediate layer obtained can be prevented from being excessively softened, and therefore, it is preferable.

The number average molecular weight calculated from the hydroxyl value of the polyol compound is a value calculated from [ the number of polyol functional groups ] x 56.11 x 1000/[ the hydroxyl value (unit: mgKOH/g) ].

[ polyisocyanate Compound ]

As the polyisocyanate compound, for example: aliphatic polyisocyanates such as tetramethylene diisocyanate, hexamethylene diisocyanate, and trimethylhexamethylene diisocyanate; alicyclic diisocyanates such as isophorone diisocyanate, norbornane diisocyanate, dicyclohexylmethane-4, 4 ' -diisocyanate, dicyclohexylmethane-2, 4 ' -diisocyanate, and ω, ω ' -diisocyanate dimethylcyclohexane; aromatic diisocyanates such as 4, 4' -diphenylmethane diisocyanate, tolylene diisocyanate, xylylene diisocyanate, tolidine diisocyanate, tetramethylene xylene diisocyanate, and naphthalene-1, 5-diisocyanate.

Among them, isophorone diisocyanate, hexamethylene diisocyanate, and xylylene diisocyanate are preferable from the viewpoint of handling properties.

{ Compound having a (meth) acryloyl group }

Examples of the compound having a (meth) acryloyl group include a (meth) acrylate having a hydroxyl group. The (meth) acrylate having a hydroxyl group is not particularly limited as long as it is a compound having a hydroxyl group and a (meth) acryloyl group in at least 1 molecule.

Specific examples of the (meth) acrylate having a hydroxyl group include: hydroxyalkyl (meth) acrylates such as 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, 4-hydroxycyclohexyl (meth) acrylate, 5-hydroxycyclooctyl (meth) acrylate, 2-hydroxy-3-phenoxypropyl (meth) acrylate, pentaerythritol tri (meth) acrylate, polyethylene glycol mono (meth) acrylate, and polypropylene glycol mono (meth) acrylate; hydroxyl group-containing (meth) acrylamides such as N-methylol (meth) acrylamide; and a reaction product obtained by reacting (meth) acrylic acid with vinyl alcohol, vinylphenol, and diglycidyl ester of bisphenol a.

Of these, hydroxyalkyl (meth) acrylates are preferred, and 2-hydroxyethyl (meth) acrylate is more preferred.

The urethane (meth) acrylate (X) used in the resin composition for the intermediate layer thus obtained preferably has a weight average molecular weight of 1,000 to 100,000, more preferably 3,000 to 80,000, and still more preferably 5,000 to 65,000. When the weight average molecular weight is 1,000 or more, it is preferable that the intermediate layer is provided with appropriate hardness due to intermolecular force between structures derived from urethane (meth) acrylate in a polymer formed from urethane (meth) acrylate and a polymerizable monomer described later.

The amount of the urethane (meth) acrylate (X) in the resin composition for the intermediate layer is preferably 20 to 70% by mass, more preferably 25 to 60% by mass, even more preferably 30 to 50% by mass, and even more preferably 33 to 47% by mass, based on the total amount of the composition. When the amount of the urethane (meth) acrylate is in this range, an intermediate layer having a high loss tangent is easily formed.

The resin composition for the intermediate layer contains, for example, a thiol group-containing compound (Y) or a polymerizable monomer (Z) in addition to the urethane (meth) acrylate (X), and preferably contains both.

(Compound (Y) containing thiol group)

The thiol group-containing compound (Y) is not particularly limited as long as it has at least 1 thiol group in the molecule, and is preferably a polyfunctional thiol group-containing compound, and more preferably a 4-functional thiol group-containing compound, from the viewpoint of easy improvement of the loss tangent.

Specific examples of the thiol group-containing compound (Y) include: nonanethiol, 1-dodecylmercaptan, 1, 2-ethanedithiol, 1, 3-propanedithiol, triazine thiol, triazine dithiol, triazine trithiol, 1,2, 3-propanetrithiol, tetraethylene glycol bis (3-mercaptopropionate), trimethylolpropane tris (3-mercaptopropionate), pentaerythritol tetrakis (3-mercaptopropionate), pentaerythritol tetramercaptoacetate, dipentaerythritol hexa (3-mercaptopropionate), tris [ (3-mercaptoacyloxy) ethyl ] isocyanurate, 1, 4-bis (3-mercaptobutyryloxy) butane, pentaerythritol tetrakis (3-mercaptobutyrate), 1,3, 5-tris (3-mercaptobutoxyethyl) -1,3, 5-triazine-2, 4,6- (1H,3H,5H) -triones, and the like.

These thiol group-containing compounds (Y) may be used in 1 kind, or in combination of 2 or more kinds.

The thiol group-containing compound (Y) preferably has a molecular weight of 200 to 3,000, more preferably 300 to 2,000. When the molecular weight is within the above range, the compatibility with the urethane (meth) acrylate (X) is good, and the film-forming property can be made good.

The amount of the thiol group-containing compound (Y) is preferably 1.0 to 4.9 parts by mass, and more preferably 1.5 to 4.8 parts by mass, based on 100 parts by mass of the total of the urethane (meth) acrylate (X) and the polymerizable monomer (Z) described later.

When the amount is 1.0 part by mass or more, an intermediate layer having a high loss tangent is easily formed, and the bump absorption can be improved. On the other hand, when the amount is 4.9 parts by mass or less, bleeding of the intermediate layer and the like can be suppressed when the film is wound in a roll form.

(polymerizable monomer (Z))

The resin composition for an intermediate layer used in the present invention preferably further contains a polymerizable monomer (Z) from the viewpoint of improving film formability. The polymerizable monomer (Z) is a polymerizable compound other than the urethane (meth) acrylate (X), and is a compound capable of polymerizing with other components by irradiation with an energy ray. The polymerizable monomer (Z) is a substance other than the resin component. The polymerizable monomer (Z) is preferably a compound having at least 1 (meth) acryloyl group.

In the present specification, the term "resin component" refers to an oligomer or polymer having a repeating structure in its structure, and is a compound having a weight average molecular weight of 1,000 or more.

Examples of the polymerizable monomer (Z) include: alkyl (meth) acrylates having an alkyl group having 1 to 30 carbon atoms, functional groups such as a hydroxyl group, an amide group, an amino group, and an epoxy group, (meth) acrylates having an alicyclic structure, (meth) acrylates having an aromatic structure, (meth) acrylates having a heterocyclic structure, vinyl compounds such as styrene, hydroxyethyl vinyl ether, hydroxybutyl vinyl ether, N-vinyl formamide, N-vinyl pyrrolidone, N-vinyl caprolactam, and allyl glycidyl ether, and the like.

Examples of the alkyl (meth) acrylate having an alkyl group having 1 to 30 carbon atoms include: methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, isopropyl (meth) acrylate, n-butyl (meth) acrylate, isobutyl (meth) acrylate, t-butyl (meth) acrylate, n-pentyl (meth) acrylate, n-hexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, n-octyl (meth) acrylate, nonyl (meth) acrylate, decyl (meth) acrylate, undecyl (meth) acrylate, dodecyl (meth) acrylate, tridecyl (meth) acrylate, tetradecyl (meth) acrylate, hexadecyl (meth) acrylate, octadecyl (meth) acrylate, eicosyl (meth) acrylate, and the like.

Examples of the (meth) acrylate having a functional group include: hydroxyl group-containing (meth) acrylates such as hydroxyethyl (meth) acrylate, hydroxypropyl (meth) acrylate, and hydroxybutyl (meth) acrylate; amide group-containing compounds such as (meth) acrylamide, N-dimethyl (meth) acrylamide, N-butyl (meth) acrylamide, N-methylol (meth) acrylamide, N-methylolpropane (meth) acrylamide, N-methoxymethyl (meth) acrylamide, and N-butoxymethyl (meth) acrylamide; amino group-containing (meth) acrylates such as primary amino group-containing (meth) acrylates, secondary amino group-containing (meth) acrylates, and tertiary amino group-containing (meth) acrylates; epoxy group-containing (meth) acrylates such as glycidyl (meth) acrylate and methyl glycidyl (meth) acrylate, and the like.

Examples of the (meth) acrylate having an alicyclic structure include: isobornyl (meth) acrylate, dicyclopentenyl (meth) acrylate, dicyclopentanyl (meth) acrylate, dicyclopentenyloxy (meth) acrylate, cyclohexyl (meth) acrylate, adamantyl (meth) acrylate, and the like.

Examples of the (meth) acrylate having an aromatic structure include: phenylhydroxypropyl (meth) acrylate, benzyl (meth) acrylate, 2-hydroxy-3-phenoxypropyl (meth) acrylate, and the like.

Examples of the (meth) acrylate having a heterocyclic structure include: tetrahydrofurfuryl (meth) acrylate, morpholinyl (meth) acrylate, and the like.

Among these, from the viewpoint of compatibility with the urethane (meth) acrylate (X), a group having a large volume is preferable, more specifically, (meth) acrylate having an alicyclic structure, (meth) acrylate having an aromatic structure, and (meth) acrylate having a heterocyclic structure are preferable, and (meth) acrylate having an alicyclic structure is more preferable. From the viewpoint of facilitating the loss tangent of 1.0 or more, the polymerizable monomer preferably contains a (meth) acrylate having a functional group and a (meth) acrylate having an alicyclic structure, and more preferably contains a hydroxyl group-containing (meth) acrylate and isobornyl (meth) acrylate.

From the above viewpoint, the amount of the (meth) acrylate having an alicyclic structure blended in the resin composition for an intermediate layer is preferably 32 to 53% by mass, more preferably 35 to 51% by mass, still more preferably 37 to 48% by mass, and yet more preferably 40 to 47% by mass, based on the total amount of the composition.

From the above viewpoint, the amount of the (meth) acrylate having an alicyclic structure blended is preferably 52 to 87 mass%, more preferably 55 to 85 mass%, even more preferably 60 to 80 mass%, and even more preferably 65 to 77 mass% with respect to the total amount of the polymerizable monomer (Z) contained in the resin composition for an intermediate layer. When the amount of the (meth) acrylate having an alicyclic structure is in this range, the loss tangent can be easily adjusted to 1.0 or more.

The amount of the polymerizable monomer (Z) blended in the resin composition for an intermediate layer is preferably 30 to 80% by mass, more preferably 40 to 75% by mass, even more preferably 50 to 70% by mass, and even more preferably 53 to 67% by mass. When the amount of the polymerizable monomer (Z) is in this range, the mobility of the portion of the intermediate layer where the polymerizable monomer (Z) is polymerized is high, and therefore the intermediate layer tends to be soft, and an intermediate layer satisfying the above requirements can be more easily formed.

From the same viewpoint, the mass ratio of the urethane (meth) acrylate (X) to the polymerizable monomer (Z) [ urethane (meth) acrylate/polymerizable monomer ] in the resin composition for an intermediate layer is preferably 20/80 to 60/40, more preferably 30/70 to 50/50, and still more preferably 35/65 to 45/55.

(energy ray polymerization initiator (R))

The resin composition for the intermediate layer preferably further contains an energy ray polymerization initiator (R). By containing the energy ray polymerization initiator (R), the resin composition for an intermediate layer can be more easily cured by energy rays such as ultraviolet rays. The energy ray polymerization initiator (R) is also generally referred to as "photopolymerization initiator", and therefore, in the present specification, it is also referred to as "photopolymerization initiator" hereinafter.

Examples of the photopolymerization initiator include: a photopolymerization initiator such as a benzoin compound, an acetophenone compound, an acylphosphine oxide compound, a titanocene compound, a thioxanthone compound, or a peroxide compound, and a photosensitizer such as an amine or a quinone, and more specifically, for example: 1-hydroxycyclohexyl phenyl ketone, 2-hydroxy-2-methyl-1-phenylpropan-1-one, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, 2-dimethoxy-1, 2-diphenylethan-1-one, and the like.

These photopolymerization initiators may be used in 1 kind, or in combination of 2 or more kinds.

The amount of the photopolymerization initiator is preferably 0.05 to 15 parts by mass, more preferably 0.1 to 10 parts by mass, and still more preferably 0.3 to 5 parts by mass, based on 100 parts by mass of the total of the urethane (meth) acrylate and the polymerizable monomer.

(other additives)

The resin composition for an intermediate layer may contain other additives within a range not impairing the effects of the present invention. As other additives, for example: crosslinking agents, antioxidants, softeners (plasticizers), fillers, rust inhibitors, pigments, dyes, and the like. When these additives are blended, the blending amount of the other additives is preferably 0.01 to 6 parts by mass, and more preferably 0.1 to 3 parts by mass, based on 100 parts by mass of the total of the urethane (meth) acrylate and the polymerizable monomer.

The resin composition for an intermediate layer may contain a resin component other than urethane (meth) acrylate in addition to urethane (meth) acrylate within a range not impairing the effects of the present invention, but preferably contains only urethane (meth) acrylate as the resin component.

The content of the resin component other than the urethane (meth) acrylate contained in the resin composition for the intermediate layer is preferably 5% by mass or less, more preferably 1% by mass or less, still more preferably 0.1% by mass or less, and still more preferably 0% by mass.

The intermediate layer may be formed of an intermediate layer resin composition containing another resin component instead of the urethane (meth) acrylate (X). For example, the intermediate layer may be formed using a curable composition containing a non-reactive urethane polymer or oligomer and a polymerizable monomer, or a composition containing an ethylene- α -olefin copolymer. Known non-reactive urethane polymers or oligomers can be used, and the same monomers as described above can be used as the polymerizable monomers. Such a curable composition may contain the above-mentioned energy ray polymerization initiator.

The ethylene-alpha-olefin copolymer is obtained by polymerizing ethylene and an alpha-olefin monomer. As the α -olefin monomer, there can be mentioned: ethylene, 1-butene, 2-methyl-1-pentene, 1-hexene, 2-dimethyl-1-butene, 2-methyl-1-hexene, 4-methyl-1-pentene, 1-heptene, 3-methyl-1-hexene, 2-dimethyl-1-pentene, 3-dimethyl-1-pentene, 2, 3-dimethyl-1-pentene, 3-ethyl-1-pentene, 2, 3-trimethyl-1-butene, 1-octene, 2, 4-trimethyl-1-octene, and the like. These α -olefin monomers may be used alone or in combination of 2 or more.

In addition, the ethylene- α -olefin copolymer may be a copolymer obtained by polymerizing ethylene, an α -olefin monomer, and other monomers. Examples of the other monomer components include: vinyl compounds such as vinyl acetate, styrene, acrylonitrile, methacrylonitrile, and vinyl ketone; unsaturated carboxylic acids such as acrylic acid and methacrylic acid; unsaturated carboxylic acid esters such as methyl acrylate, ethyl acrylate, n-propyl acrylate, methyl methacrylate, ethyl methacrylate, and n-propyl methacrylate; unsaturated carboxylic acid amides such as acrylamide and methacrylamide, and the like. These monomers may be used alone, or in combination of 2 or more.

< adhesive layer >

The pressure-sensitive adhesive layer is provided on the substrate, and if an intermediate layer is provided, on the intermediate layer. The adhesive layer of the present invention contains at least a urethane resin (a) and an energy ray-curable compound (B) which does not react with the urethane resin (a) and has a molecular weight of 35,000 or less.

In the present invention, since the adhesive layer contains the urethane resin (a), the cohesive force and mechanical strength of the adhesive layer are improved, and therefore, when the adhesive tape is peeled from a workpiece after energy ray curing, residual paste is less likely to be generated on the surface of the workpiece such as a bump. Further, by containing at least the energy ray-curable compound (B), the adhesive layer can be made to have energy ray-curable properties. Therefore, the peeling performance when the adhesive tape is peeled from the work can be improved. Further, by making the energy ray-curable compound (B) non-reactive, the storage modulus of the pressure-sensitive adhesive layer can be reduced as described later, and the following property to the surface roughness of the workpiece can be easily secured.

The pressure-sensitive adhesive layer preferably has a breaking stress after irradiation with an energy ray of 2.5MPa or more. When the breaking stress is 2.5MPa or more, the mechanical strength is a sufficient value, and the above residual paste is liable to be reduced. The breaking stress is preferably 2.8 to 30MPa, and more preferably 3.0 to 25MPa, from the viewpoint of suppressing residual paste and easily improving embeddability of the protrusions, adhesiveness of the pressure-sensitive adhesive layer, and peelability. The breaking stress was measured according to the method described in the examples described below.

The breaking stress can be adjusted by changing the type of the urethane resin (a). Further, the amount of the photopolymerizable unsaturated bond may be adjusted as described later, and when the amount of the photopolymerizable unsaturated bond contained in the pressure-sensitive adhesive layer is increased, the breaking stress tends to be increased, and when the amount of the photopolymerizable unsaturated bond contained in the pressure-sensitive adhesive layer is decreased, the breaking stress tends to be decreased. Similarly, the amount of the crosslinking agent component described later can be used to adjust the amount, and the fracture stress tends to increase when the amount of the crosslinking agent component is increased and decrease when the amount of the crosslinking agent component is decreased.

Since the adhesive layer is energy ray-curable, it can have a soft texture before irradiation with energy rays, and the adhesive layer can easily follow the irregularities formed on the surface of the workpiece. In addition, the adhesive tape can be easily peeled from the work by being cured by irradiation with an energy ray to reduce the adhesive force.

The adhesive force of the adhesive tape after energy ray irradiation is preferably 2000mN/25mm or less from the viewpoint of suppressing residual paste at the time of peeling of the adhesive tape. In particular, when the adhesive tape of the present invention having an intermediate layer is attached to a workpiece having large protrusions (for example, a height of 200 μm or more) such as bumps on the surface thereof, the protrusions are usually absorbed by the intermediate layer of the adhesive tape attached to the surface of the workpiece. Therefore, although the adhesive tape is likely to have residual paste when peeled therefrom, the adhesive force is set to 2000mN/25mm or less, whereby the occurrence of such residual paste can be easily prevented. The adhesive force of the adhesive tape after the irradiation of the energy ray is preferably 50 to 1750mN/25mm, and more preferably 100 to 1500nN/25 mm.

The adhesive force of the adhesive tape before the energy ray irradiation is, for example, more than 2000mN/25mm, preferably 3000 to 30000mN/25mm, and more preferably 3500 to 9000 mN/m. When the adhesive force before the energy ray irradiation is within this range, the adhesiveness to the surface of the workpiece is good and the protective performance of the workpiece is good.

The adhesive force of the adhesive tape was measured when the adhesive layer of the adhesive tape was attached to a silicon mirror wafer and peeled at a peel angle of 180 ° and a peel speed of 300 mm/min under an environment of 23 ℃, specifically, according to the method described in the examples described below.

The adhesive strength can be adjusted by changing the types of the urethane resin (a) and the energy ray-curable compound (B). The adhesive force after the energy ray irradiation can be adjusted by the amount of the photopolymerizable unsaturated bond described later, and when the amount of the photopolymerizable unsaturated bond contained in the pressure-sensitive adhesive composition is increased, the adhesive force tends to be decreased, and when the amount of the photopolymerizable unsaturated bond contained in the pressure-sensitive adhesive composition is decreased, the adhesive force tends to be increased. The adhesive force after the energy ray irradiation can be easily reduced by adding a crosslinking agent (C1) containing a photopolymerizable unsaturated bond and the compound (D) as described later.

(urethane resin (A))

The urethane resin (a) is a polymer containing at least one of a urethane bond and a urea bond. The adhesive layer of the present invention is formed from a urethane adhesive composition (hereinafter, also simply referred to as "adhesive composition") containing at least a urethane polymer (a ') and an energy ray-curable compound (B), and the urethane resin (a) is composed of at least the urethane polymer (a') as a main agent. The urethane adhesive composition may further contain a crosslinking agent (C), a compound (D), and the like, as necessary.

The urethane resin (a) may be a resin crosslinked with a crosslinking agent (C). As described above, the urethane adhesive composition may contain, in addition to the crosslinking agent (C), a compound that is directly or indirectly bonded to the urethane polymer (a') as in the case of the compound (D) or the like and that constitutes the urethane resin (a) integrally in the adhesive layer.

The compound directly or indirectly bonded to the urethane polymer (a ') like the crosslinking agent (C) and the compound (D) and constituting the urethane resin (a) integrally in the pressure-sensitive adhesive layer together with the urethane polymer (a') is collectively referred to as a "main agent-reactive compound".

In the present invention, in order to ensure the adhesiveness of the pressure-sensitive adhesive layer and to blend the components (B) to (E) described later in an appropriate amount, the blend amount of the urethane polymer (a') is preferably 30 to 85 mass%, more preferably 35 to 80 mass%, and still more preferably 37 to 77 mass% with respect to the total amount of the pressure-sensitive adhesive composition. The total amount of the main agent-reactive compound and the urethane polymer (a') is preferably 40 to 95% by mass, more preferably 45 to 94% by mass, and still more preferably 50 to 93% by mass, based on the total amount of the adhesive composition.

The urethane resin (a) preferably has a photopolymerizable unsaturated bond. When the urethane resin (a) has a photopolymerizable unsaturated bond, both the urethane resin (a) and the energy ray-curable compound (B) have a photopolymerizable unsaturated bond in the adhesive layer of the adhesive tape for workpiece processing. Therefore, by irradiating the adhesive layer with energy rays, the urethane resin (a) and the energy ray-curable compound (B) are bonded by a polymerization reaction, and the adhesive force of the adhesive tape after the irradiation with energy rays is more easily reduced, so that the peelability of the adhesive tape when peeled from the work becomes good. Further, the residual paste generated when the adhesive tape is peeled from the work can be further reduced. In addition, compared to the case where the pressure-sensitive adhesive layer is cured by irradiation with energy rays only with the energy ray-curable compound (B), the strength of the pressure-sensitive adhesive layer after irradiation with energy rays tends to be higher, and the occurrence of residual paste is more easily suppressed.

The method for introducing the photopolymerizable unsaturated bond into the urethane resin (a) is not particularly limited. For example, in the case where the urethane polymer (a') before introduction of the photopolymerizable unsaturated bond has a hydroxyl group, a compound having a functional group capable of reacting with the hydroxyl group and a functional group containing a photopolymerizable unsaturated bond such as a (meth) acryloyl group may be reacted with the hydroxyl group to introduce the photopolymerizable unsaturated bond. Examples of the compound having a functional group capable of reacting with a hydroxyl group and a functional group containing a photopolymerizable unsaturated bond include: methacryloyloxyethyl isocyanate, and the like. Such a compound may be previously reacted with the urethane polymer (a '), or may be previously contained in the adhesive layer and reacted with the urethane polymer (a') at the time of forming the adhesive layer.

As described later, the urethane polymer (a') is crosslinked with a crosslinking agent (C1) having a photopolymerizable unsaturated bond as the crosslinking agent (C), whereby the photopolymerizable unsaturated bond can be introduced into the urethane resin (a). Further, a photopolymerizable unsaturated bond may be introduced into the urethane resin (a) by the compound (D) described later.

< urethane Polymer (A') >

The urethane polymer (a') may be a polymer containing at least one of a urethane bond and a urea bond, and specifically may be a polyurethane polyol having a hydroxyl group at the end obtained by reacting a polyol and a polyisocyanate compound. As the urethane polymer (a'), isocyanate-terminated urethane polymers obtained by reacting a polyol and a polyisocyanate compound can be used.

Examples of the polyol used for the urethane polymer (a') include polyester polyol and polyether polyol.

As the polyester polyol, a known polyester polyol can be used. The polyester polyol is an ester of an acid component and at least one of a diol component and a polyol component, and examples of the acid component include: terephthalic acid, adipic acid, azelaic acid, sebacic acid, phthalic anhydride, isophthalic acid, trimellitic acid, and the like. Further, as the diol component, there may be mentioned: ethylene glycol, propylene glycol, diethylene glycol, butanediol, 1, 6-hexanediol, 3-methyl-1, 5-pentanediol, 3' -dimethylolheptane, polyoxyethylene glycol, polyoxypropylene glycol, 1, 4-butanediol, neopentyl glycol, butylethylpentanediol, and as the polyol component, there can be mentioned: glycerin, trimethylolpropane, pentaerythritol, and the like.

Further, polyester polyols obtained by ring-opening polymerization of lactones such as polycaprolactone, poly (. beta. -methyl-. gamma. -valerolactone) and polygluvalactone may be used.

As the polyether polyol, a known polyether polyol can be used. For example, a polyether polyol obtained by polymerizing an epoxy compound such as ethylene oxide, propylene oxide, butylene oxide, or tetrahydrofuran using water, a low molecular weight polyol such as propylene glycol, ethylene glycol, glycerin, or trimethylolpropane, as an initiator, and specifically, a polyether polyol having a functional group of 2 or more such as polypropylene glycol, polyethylene glycol, or polytetramethylene glycol can be used.

As the polyisocyanate compound, there can be mentioned: known examples of the polyisocyanate include aromatic polyisocyanates, aliphatic polyisocyanates, araliphatic polyisocyanates, and alicyclic polyisocyanates. As the aromatic polyisocyanate, there may be mentioned: 1, 3-phenylene diisocyanate, 4 ' -biphenyl diisocyanate, 1, 4-phenylene diisocyanate, 4 ' -diphenylmethane diisocyanate, 2, 4-tolylene diisocyanate, 2, 6-tolylene diisocyanate, 4 ' -toluidine diisocyanate, 2,4, 6-triisocyanatotoluene, 1,3, 5-triisocyanatobenzene, dianisidine diisocyanate, 4 ' -diphenyl ether diisocyanate, 4 ', 4 ″ -triphenylmethane triisocyanate, and the like.

As the aliphatic polyisocyanate, there may be mentioned: trimethylene diisocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate, pentamethylene diisocyanate, 1, 2-propylene diisocyanate, 2, 3-butylene diisocyanate, 1, 3-butylene diisocyanate, dodecamethylene diisocyanate, 2,4, 4-trimethylhexamethylene diisocyanate, and the like.

As the araliphatic polyisocyanate, there may be mentioned: omega, omega '-diisocyanate-1, 3-dimethylbenzene, omega' -diisocyanate-1, 4-diethylbenzene, tetramethylxylylene-1, 4-diisocyanate, tetramethylxylylene-1, 3-diisocyanate, and the like.

As the alicyclic polyisocyanate, there can be mentioned: 3-isocyanatomethyl-3, 5, 5-trimethylcyclohexyl isocyanate, 1, 3-cyclopentane diisocyanate, 1, 3-cyclohexane diisocyanate, 1, 4-cyclohexane diisocyanate, methyl-2, 6-cyclohexane diisocyanate, 4' -methylenebis (cyclohexyl isocyanate), 1, 4-bis (isocyanatomethyl) cyclohexane, and the like.

The polyisocyanate compound may be used in combination with a trimethylolpropane adduct of the polyisocyanate compound, a biuret product obtained by reaction with water, or an isocyanurate ring-containing 3-mer.

As the polyisocyanate compound, 4' -diphenylmethane diisocyanate, hexamethylene diisocyanate, 3-isocyanatomethyl-3, 5, 5-trimethylcyclohexyl isocyanate (isophorone diisocyanate), and the like are preferable.

The polyurethane polyol may be a polyurethane polyol obtained by reacting a polyol with a polyfunctional isocyanate, and a diamine such as ethylenediamine, N-aminoethylethanolamine, isophoronediamine, or xylylenediamine. In addition, as the polyol, ethylene glycol, 1, 4-butanediol, neopentyl glycol, butylethylpentanediol, glycerin, trimethylolpropane, pentaerythritol, and the like can be used in addition to the polyester polyol and the polyether polyol described above.

The reaction of the polyol and the polyisocyanate compound is usually carried out in the presence of a catalyst such as a tertiary amine compound or an organic metal compound.

The urethane polymer (a') is not limited to the above examples, and may be a michael addition urethane polymer, for example.

Examples of the michael addition type urethane polymer include the following polymers (1) and (2).

(1) A polymer obtained by reacting an amino compound obtained by reacting a polyamine and an unsaturated compound with a urethane prepolymer having an isocyanate group (-NCO) at a terminal obtained by reacting the above polyol and a polyisocyanate compound.

(2) A polymer obtained by reacting a polyurethane urea having a primary amino group or a secondary amino group at the terminal, which is obtained by reacting the above-mentioned polyol, polyisocyanate compound and polyamine, with an unsaturated compound by Michael addition reaction.

As the polyamine used in the michael addition type urethane polymer, known polyamines can be used, and specific examples thereof include: aliphatic polyamines such as ethylenediamine, propylenediamine, trimethylenediamine, tetramethylenediamine, pentamethylenediamine, hexamethylenediamine, triethylenetetramine, diethylenetriamine, triaminopropane, 2, 4-trimethylhexamethylenediamine, tolylenediamine, hydrazine, and piperazine, alicyclic polyamines such as isophoronediamine and dicyclohexylmethane-4, 4' -diamine, and aromatic polyamines such as phenylenediamine and xylylenediamine. Further, diamines having a hydroxyl group in the molecule, such as 2-hydroxyethylethylenediamine, N- (2-hydroxyethyl) propylenediamine, (2-hydroxyethylpropylene) diamine, (di-2-hydroxyethylethylene) diamine, (di-2-hydroxyethylpropylene) diamine, (2-hydroxypropylethylene) diamine, and (di-2-hydroxypropylethylene) diamine, and dimer diamines in which the carboxyl group of a dimer acid is converted into an amino group, polyoxyalkylene glycol diamines having propoxyamines at both ends and represented by the following general formula (2), and the like can be used.

H₂-NCH₂-CH₂-CH₂-O(C_nH_2n-O)_m-CH₂-CH₂-CH₂-NH₂ (2)

(in the formula (2), n represents an arbitrary integer of 2 to 4, and m represents an arbitrary integer of 2 to 50.)

In addition, as the polyamine, a dendritic polymer (dendrimer) having a primary amino group or a secondary amino group at the terminal can also be used.

Among the polyamines mentioned above, isophoronediamine, 2, 4-trimethylhexamethylenediamine and hexamethylenediamine are preferable from the viewpoint of easy control of the reaction.

In addition, unsaturated compounds used in michael addition type urethane polymers may be used for modification of the urethane polymers. Therefore, the kind of the unsaturated compound to be used may be arbitrarily selected depending on the purpose of modification. Examples of the unsaturated compound include: (meth) acrylic unsaturated compounds, amide unsaturated compounds, fatty acid vinyl ester unsaturated compounds, vinyl ether unsaturated compounds, α -olefin unsaturated compounds, allyl acetate unsaturated compounds, vinyl cyanide unsaturated compounds, styrene or vinyl benzene unsaturated compounds, and the like.

The kind of the unsaturated compound to be used may be arbitrarily selected depending on the purpose of modification, but is preferably selected with attention paid to the functional group of the unsaturated compound. Examples of the functional group of the unsaturated compound include a nitrogen-containing group such as an alkyl group, a polyalkylene glycol group, an alkoxy group, a phenoxy group, a hydroxyl group, a carboxyl group, a perfluoroalkyl group, an alkoxysilyl group, an epoxy group, an amide group, a dialkylamino group, or a quaternary ammonium salt group, and the like.

As specific examples of the unsaturated compounds, those described in, for example, Japanese patent application laid-open No. 2002-121256 (European patent application laid-open No. EP1146061A1) can be used.

The weight average molecular weight of the urethane polymer (A') used in the present invention is preferably 10,000 to 300,000, more preferably 30,000 to 150,000. When the weight average molecular weight is 10,000 or more, the cohesive force of the pressure-sensitive adhesive layer can be increased, and a higher effect of suppressing residual paste can be obtained. In addition, by making the weight average molecular weight 300,000 or less, there are the following advantages: when the adhesive layer is formed from the adhesive composition, the adhesive layer is diluted with a solvent or melted by heating, and thus the viscosity is not likely to increase to such an extent that the process adaptability is affected.

(energy ray-curable Compound (B))

The energy ray-curable compound (B) used in the present invention does not react with the urethane resin (a) and has a photopolymerizable unsaturated bond.

The term "non-reactive" as used herein means that the compound (B) does not contain a functional group reactive with the urethane polymer (a') other than the "photopolymerizable unsaturated bond" and a functional group reactive with the main agent reactive compound, and the compound (B) does not react with the urethane resin (a) in the pressure-sensitive adhesive layer.

That is, the energy ray-curable compound (B) is a compound which does not react with the components (a '), (C) and (D) when the urethane polymer (a'), the crosslinking agent (C) and, if necessary, other components (for example, the component (D)) are reacted to form the pressure-sensitive adhesive layer.

Thus, the energy ray-curable compound (B) is present as a component not constituting the urethane resin (a) in the pressure-sensitive adhesive layer. The urethane polymer generally has a high cohesive force and a high storage modulus, and is difficult to embed into a protrusion such as a bump on the surface of a work when used alone.

In the present invention, the photopolymerizable unsaturated bond means an unsaturated bond that is reacted by irradiation with an energy ray, and is usually an olefinic double bond, and is preferably a carbon-carbon double bond contained in a (meth) acryloyl group.

The molecular weight of the energy ray-curable compound (B) is 35,000 or less. When the molecular weight is more than 35,000, it is difficult to reduce the storage modulus of the adhesive layer and to secure the embeddability into the bump. In addition, there is a possibility that the compatibility with the urethane resin (a) is deteriorated. The molecular weight of the energy ray-curable compound (B) is preferably 150 to 35,000, more preferably 200 to 34,000. The molecular weight means the formula weight when the formula weight can be determined, and means the weight average molecular weight when the formula weight cannot be determined.

The amount of the energy ray-curable compound (B) to be blended varies depending on the compound to be used, and is usually 1 to 120 parts by mass, preferably 2 to 100 parts by mass, and more preferably 4 to 90 parts by mass, based on 100 parts by mass of the urethane resin (a) (that is, 100 parts by mass of the total of the urethane polymer (a') and the main agent-reactive compound, the same applies hereinafter). When the amount of the energy ray-curable compound (B) is in such a range, an adhesive layer having both of the following property to the surface of the workpiece and the residual paste suppression can be easily obtained.

Specific examples of the energy ray-curable compound (B) include compounds having a (meth) acryloyl group. The number of (meth) acryloyl (photopolymerizable unsaturated bond) functional groups in one molecule of the energy ray-curable compound (B) may be 1 or more, preferably 2 or more, and more preferably 2 to 12.

Specific examples of the energy ray-curable compound (B) used in the present invention include at least 1 selected from a (meth) acrylate monomer (B1) and a urethane (meth) acrylate (B2).

The (meth) acrylate monomer (B1) is a compound having a (meth) acryloyl group in the molecule, and the number of (meth) acryloyl groups is preferably 2 or more, and more preferably 3 to 6. In particular, when the urethane resin (a) does not have a photopolymerizable unsaturated bond, the adhesive layer preferably contains a (meth) acrylate monomer (B1) having a number of (meth) acryloyl groups of 4 or more, so that the adhesive force of the adhesive tape is easily reduced after the energy ray irradiation to the adhesive layer.

Examples of the (meth) acrylate monomer (B1) include a fully esterified polyfunctional (meth) acrylate obtained by forming an ester of all hydroxyl groups of a polyol with (meth) acrylic acid. Here, the number of carbon atoms of the polyol is preferably 4 to 10. The molecular weight of the (meth) acrylate monomer (B1) is preferably 150 to 1000, more preferably 200 to 800.

Specific examples of the polyfunctional (meth) acrylate include: trimethylolpropane tri (meth) acrylate, pentaerythritol tetra (meth) acrylate, dipentaerythritol hexa (meth) acrylate, 1, 4-butanediol di (meth) acrylate, 1, 6-hexanediol di (meth) acrylate, and the like, and among them, pentaerythritol tetra (meth) acrylate is preferable.

The (meth) acrylate monomer (B1) can specify the structure, and the molecular weight means the formula weight.

The (meth) acrylate monomer (B1) is preferable because residual paste can be prevented even in a small amount of the monomer, and the adhesive force can be appropriately reduced by energy ray curing.

Specifically, the amount of the (meth) acrylate monomer (B1) is preferably 1 to 20 parts by mass, more preferably 2 to 15 parts by mass, and still more preferably 3 to 10 parts by mass, based on 100 parts by mass of the urethane resin (a). By setting the amount of the energy ray-curable compound (B) to such a blending amount, residual paste of the pressure-sensitive adhesive layer can be appropriately prevented, and the adhesive force of the pressure-sensitive adhesive layer can be appropriately reduced by irradiation with energy rays.

The urethane (meth) acrylate (B2) is a polymer having a urethane bond and a (meth) acryloyl group at a terminal. As the urethane (meth) acrylate (B2), there can be mentioned: a compound obtained by reacting a polyol compound with a polyisocyanate compound to produce a terminal isocyanate urethane polymer and reacting a functional group at the terminal thereof with a compound having a (meth) acryloyl group, and the like. Such urethane (meth) acrylate (B2) has energy ray curability due to the action of a (meth) acryloyl group.

The polyol compound, polyisocyanate compound and compound having a (meth) acryloyl group used for obtaining the urethane (meth) acrylate (B2) may be appropriately selected from the polyol compound, polyisocyanate compound and compound having a (meth) acryloyl group used for the urethane (meth) acrylate (X) in the intermediate layer, and their specific description will be omitted here.

The urethane (meth) acrylate (B2) has a (meth) acryloyl group, and the number of (meth) acryloyl functional groups in 1 molecule thereof is preferably 2 or more, more preferably 2 to 12, and still more preferably 2 to 10. Thus, the adhesive force can be easily reduced by curing with an energy ray by making the resin multifunctional.

The molecular weight of the urethane (meth) acrylate (B2) is 35000 or less, preferably 2000 to 35000, and more preferably 5000 to 34000. The molecular weight of the urethane (meth) acrylate (B2) is a weight average molecular weight. By setting the molecular weight of the urethane (meth) acrylate in such a range, the storage modulus of the pressure-sensitive adhesive layer can be reduced, and the following property to the surface unevenness of the workpiece can be easily secured. In addition, the movement of the urethane (meth) acrylate (B2) in the adhesive layer can be suppressed, and the secular stability of the adhesive tape can be improved.

When the energy ray-curable compound (B) is a urethane (meth) acrylate (B2), the amount of the urethane (meth) acrylate (B2) is preferably 30 to 120 parts by mass, more preferably 40 to 100 parts by mass, and still more preferably 50 to 90 parts by mass, based on 100 parts by mass of the urethane resin (a). By setting the amount of the urethane (meth) acrylate (B2) to be blended as described above, the adhesive performance of the adhesive layer can be maintained well, and the embeddability can be easily ensured. In addition, the adhesive force can be sufficiently reduced by energy ray curing, and further the residual paste is easily reduced.

(crosslinking agent (C))

The adhesive composition of the present invention preferably further contains a crosslinking agent (C). The crosslinking agent (C) is a substance that reacts with the urethane polymer (a ') to crosslink the urethane polymer (a'). When the pressure-sensitive adhesive composition contains the crosslinking agent (C), the crosslinking density can be increased, and a pressure-sensitive adhesive layer having high mechanical strength can be easily formed. Further, it is also easy to prevent residual paste or the like when the adhesive tape is peeled.

When the urethane polymer (a') has a hydroxyl group, the crosslinking agent (C) is preferably a crosslinking agent having 2 or more isocyanate groups so as to react with the hydroxyl group. When the pressure-sensitive adhesive composition contains a crosslinking agent, crosslinking is usually performed by heating after coating.

On the contrary, the urethane polymer (a') may have an isocyanate group and the crosslinking agent (C) may have a hydroxyl group. The urethane polymer (a ') generally has a hydroxyl group or an isocyanate group in terms of the production method thereof, and therefore it is preferable that the urethane polymer (a') and the crosslinking agent (C) are bonded via a urethane bond.

As the crosslinking agent (C) that can be used in the present invention, a crosslinking agent (C1) containing a photopolymerizable unsaturated bond is preferably used.

The crosslinking agent (C1) containing a photopolymerizable unsaturated bond is preferably a compound having 2 or more isocyanate groups and a (meth) acryloyl group, and more preferably a urethane (meth) acrylate having at least 2 isocyanate groups is used.

The urethane (meth) acrylate preferably has a weight average molecular weight of 500 to 2000, more preferably 700 to 1000. In addition, when one molecule of the crosslinking agent (C1) has 2 or more photopolymerizable unsaturated bonds, the photopolymerizable unsaturated bonds in one molecule of the crosslinking agent (C1) tend to be easily polymerized with each other. Therefore, the crosslinking agent (C1) hardly reacts with the photopolymerizable unsaturated bond of other molecules, and the adhesive force of the adhesive tape may be reduced by irradiating the adhesive layer with energy rays. Therefore, the crosslinking agent (C1) preferably has 1 photopolymerizable unsaturated bond in one molecule. Examples of the urethane (meth) acrylate used as the crosslinking agent (C1) include: "EBECRYL 4150" manufactured by DAICEL-ALLNEX, Inc.

In the present embodiment, the urethane resin (a) is provided with a photopolymerizable unsaturated bond in the pressure-sensitive adhesive layer by using a crosslinking agent (C1) having a photopolymerizable unsaturated bond.

Examples of the crosslinking agent containing a hydroxyl group and a photopolymerizable unsaturated bond include: an acrylic polymer having a hydroxyl group and a (meth) acryloyl group in a side chain. In this case, the urethane resin (a) crosslinked with the crosslinking agent (C1) is a so-called acrylic urethane resin, and the urethane resin (a) of the present invention includes such an acrylic urethane resin.

The amount of the crosslinking agent (C1) containing a photopolymerizable unsaturated bond is preferably 5 to 60 parts by mass, more preferably 10 to 50 parts by mass, and still more preferably 15 to 45 parts by mass, based on 100 parts by mass of the urethane resin (a). By setting the amount of the crosslinking agent (C1) to be blended as described above, the crosslinking density of the pressure-sensitive adhesive layer can be improved, and an appropriate amount of photopolymerizable unsaturated bonds can be introduced into the urethane resin (a).

The pressure-sensitive adhesive composition may further contain a crosslinking agent (C2) containing no photopolymerizable unsaturated bond as the crosslinking agent (C). When the urethane polymer (a ') has a hydroxyl group, the crosslinking agent (C2) can be appropriately selected from the polyisocyanate compounds used for synthesizing the urethane polymer (a') described above. When the polymer (a') before crosslinking has an isocyanate group, a known polyol can be used as the crosslinking agent (C2). When the pressure-sensitive adhesive composition contains the crosslinking agent (C2), the crosslinking density of the pressure-sensitive adhesive layer can be sufficiently increased.

The crosslinking agent (C) may be all the crosslinking agent (C1) having a photopolymerizable unsaturated bond, or all the crosslinking agent (C2) not having a photopolymerizable unsaturated bond, preferably contains the crosslinking agent (C1) having a photopolymerizable unsaturated bond, and more preferably contains both the crosslinking agent (C1) and the crosslinking agent (C2).

The amount of the crosslinking agent (C2) not containing a photopolymerizable unsaturated bond is preferably 0.2 to 15 parts by mass, and more preferably 0.5 to 10 parts by mass, based on 100 parts by mass of the urethane resin (a). In addition, as described above, when the crosslinking agent (C1) is used in combination, the amount of the crosslinking agent (C2) containing no photopolymerizable unsaturated bond may be small, and is preferably 0.2 to 5 parts by mass, and more preferably 0.5 to 2 parts by mass, based on 100 parts by mass of the urethane resin (a).

(Compound (D))

When the adhesive composition contains the crosslinking agent (C), it preferably further contains a compound (D) having a photopolymerizable unsaturated bond and a reactive functional group capable of reacting with the crosslinking agent (C). The compound (D) having a reactive functional group reacts with the crosslinking agent (C) when the urethane polymer (a') reacts with the crosslinking agent (C) to form a urethane polymer chain.

When the adhesive composition contains the compound (D), the compound (D) can be used to introduce a photopolymerizable unsaturated bond into the urethane resin (a). Therefore, when the pressure-sensitive adhesive layer is cured by the energy ray, the adhesive force of the pressure-sensitive adhesive layer can be easily reduced, and the residual paste and the like can be easily prevented. In addition, the adhesive tape has an effect of easily stabilizing the performance of the adhesive tape over time.

Examples of the reactive functional group contained in the compound (D) include: isocyanate group, hydroxyl group. In addition, as the compound (D), a (meth) acrylate monomer having a hydroxyl group and a (meth) acryloyl group is exemplified. The number of (meth) acryloyl (i.e., photopolymerizable unsaturated bond) functional groups in 1 molecule of the compound (D) is preferably 2 or more, and more preferably 2 to 5 in 1 molecule.

The molecular weight of the (meth) acrylate monomer used as the component (D) is preferably 150 to 3,000, more preferably 200 to 2,000.

Examples of the (meth) acrylate monomer used as the component (D) include polyfunctional (meth) acrylates obtained by partially esterifying polyols and (meth) acrylic acid. Here, the number of carbon atoms of the polyol is preferably 4 to 10. As specific compounds, there can be exemplified: pentaerythritol tri (meth) acrylate, dipentaerythritol tetra (meth) acrylate, dipentaerythritol penta (meth) acrylate, and the like, and among them, pentaerythritol tri (meth) acrylate is preferable.

The amount of the compound (D) is preferably 1 to 30 parts by mass, more preferably 2 to 20 parts by mass, and still more preferably 3 to 15 parts by mass, based on 100 parts by mass of the urethane resin (a). By blending the compound (D) in such a range, the adhesive property of the adhesive layer is not adversely affected, the adhesive force can be easily reduced by curing with an energy ray, and the residual paste can be easily prevented. When the energy ray-curable compound (B) contains a (meth) acrylate monomer (B1), it is generally preferable to use the compound (D). Thus, when the compound (D) and the (meth) acrylate monomer (B1) are used in combination, the effects of the present invention can be further exhibited.

(energy ray polymerization initiator (E))

The adhesive composition preferably further contains an energy ray polymerization initiator (E). By containing the energy ray polymerization initiator (E) in the adhesive layer, curing by energy ray irradiation can be easily performed. The energy ray polymerization initiator (E) can be suitably selected from the photopolymerization initiators that can be used for the above-mentioned resin compositions for an intermediate layer.

The amount of the energy ray polymerization initiator (E) is preferably 0.05 to 25 parts by mass, more preferably 0.1 to 20 parts by mass, and even more preferably 0.3 to 15 parts by mass, based on 100 parts by mass of the total of the compounds having photopolymerizable unsaturated bonds, such as the urethane polymer (a') having photopolymerizable unsaturated bonds, the crosslinking agent (C1), the energy ray curable compound (B), and the compound (D).

The adhesive composition may contain other additives conventionally used in urethane adhesives, and may contain fillers such as calcium carbonate and titanium oxide, colorants, antioxidants, antifoaming agents, light stabilizers, and the like.

The thickness of the adhesive layer can be adjusted as appropriate depending on the height of the bumps on the wafer surface and the surface state of the surface to be bonded to which the adhesive tape is attached, and is preferably 2 to 150 μm, more preferably 5 to 100 μm, and still more preferably 8 to 50 μm.

< stripping Material >

The release material provided on the pressure-sensitive adhesive layer and the release material used in the step of the production method described later may be a release sheet subjected to a single-sided release treatment, a release sheet subjected to a double-sided release treatment, or the like, and examples thereof include a release material obtained by coating a release agent on a release material substrate.

Examples of the base material for release material include: and plastic films such as polyester resin films including polyethylene terephthalate resins, polybutylene terephthalate resins, and polyethylene naphthalate resins, and polyolefin resin films including polypropylene resins and polyethylene resins.

Examples of the release agent include: rubber elastomers such as silicone resins, olefin resins, isoprene resins, and butadiene resins, long-chain alkyl resins, alkyd resins, and fluorine-containing resins.

The thickness of the release agent is not particularly limited, but is preferably 5 to 200 μm, and more preferably 10 to 120 μm.

[ method for producing adhesive tape ]

The method for producing the adhesive tape of the present invention is not particularly limited, and the adhesive tape can be produced by a known method.

The intermediate layer may be formed, for example, in the following manner: a solution of the resin composition for an intermediate layer is directly applied to one surface of the substrate to form a coating film, and then dried and cured as necessary. In addition, the intermediate layer may be formed by: the method for producing a prepreg includes the steps of coating a solution of a resin composition for an intermediate layer on a release-treated surface of a release material to form a coating film, drying the coating film as needed, and performing a semi-curing treatment to form a semi-cured layer on the release material, and bonding the semi-cured layer to a base material to completely cure the semi-cured layer. At this time, the release material may be appropriately removed before or after the semi-cured layer is completely cured. In the curing of the intermediate layer, the coating film is preferably polymerized and cured by irradiation with an energy ray, and the energy ray is preferably an ultraviolet ray. When the intermediate layer is formed using an olefin-based material, the intermediate layer can be formed by extrusion molding or the like.

The pressure-sensitive adhesive layer is preferably formed by applying a pressure-sensitive adhesive composition, heating and crosslinking the pressure-sensitive adhesive composition, and drying the pressure-sensitive adhesive composition as needed. In this case, the adhesive composition may be directly applied to the intermediate layer or the substrate, or may be applied to the release-treated surface of the release material to form an adhesive layer, and then the adhesive layer is bonded to the intermediate layer or the substrate. The release material disposed on the adhesive layer may be peeled off as necessary.

In forming the intermediate layer and the pressure-sensitive adhesive layer, an organic solvent may be further added to the resin composition for the intermediate layer or the pressure-sensitive adhesive composition to prepare a diluted solution of the resin composition for the intermediate layer or the pressure-sensitive adhesive composition. Examples of the organic solvent to be used include: methyl ethyl ketone, acetone, ethyl acetate, tetrahydrofuran, dimethyl ethyl ketone, dimethyl ethyl acetate, dimethyl ethyl ketone

Alkanes, cyclohexane, n-hexane, toluene, xylene, n-propanol, isopropanol, and the like.

The organic solvent used in the synthesis of each component contained in the resin composition for an intermediate layer or the adhesive composition may be used as it is, or 1 or more kinds of organic solvents other than the organic solvent may be added.

The resin composition or the adhesive composition for the intermediate layer can be coated by a known coating method. Examples of the coating method include: spin coating, spray coating, bar coating, blade coating, roll coating, blade coating, die coating, gravure coating, and the like.

[ method of Using adhesive tape ]

The adhesive tape of the present invention is used when it is attached to various workpieces and used for processing the workpieces, and is preferably used by being attached to a surface of a workpiece having projections and depressions.

Further, the adhesive tape is preferably used as an adhesive tape for protecting the surface of a semiconductor wafer by being adhered to the surface of a semiconductor wafer, particularly, the surface of a wafer on which bumps are formed. Further, it is preferable that the adhesive tape is attached to the front surface of the semiconductor wafer and used as a back-grinding tape for protecting a circuit formed on the front surface of the wafer in the subsequent back-grinding of the wafer. In the case where the adhesive tape of the present invention has an intermediate layer, the embedding property is good even if the wafer surface has a level difference formed by bumps or the like, and therefore the wafer surface has good protective properties. In this case, the temperature of the adhesive tape when the adhesive tape is attached to the surface of the semiconductor wafer is, for example, about 40 to 80 ℃, preferably 50 to 70 ℃.

In the present invention, the adhesive layer is of an energy ray-curable type, and the adhesive tape attached to the surface of a workpiece such as a semiconductor wafer is irradiated with an energy ray to be cured and then peeled from the surface of the workpiece. Therefore, the adhesive tape is peeled off after the adhesive force is reduced, and therefore, the peelability thereof is good. In addition, when the cured adhesive tape is peeled off as described above, residual paste is less likely to occur.

When the adhesive tape is used for semiconductor wafer applications, the adhesive tape is not limited to the back grinding sheet, and may be used for other applications. For example, an adhesive tape may be attached to the back surface of the wafer and used as a dicing sheet for holding the wafer when dicing the wafer. In this case, the wafer may be a workpiece having projections such as bumps or irregularities formed on the back surface of the wafer, such as a workpiece having a through electrode formed thereon.

Examples

The present invention will be described in further detail below with reference to examples, but the present invention is not limited to these examples.

The measurement method and evaluation method in the present invention are as follows.

[ weight average molecular weight (Mw), number average molecular weight (Mn) ]

The measurement was carried out under the following conditions using a gel permeation chromatography apparatus (product name "HLC-8220", manufactured by Tosoh corporation), and the values obtained by the measurement and conversion to standard polystyrene were used.

(measurement conditions)

A chromatographic column: "TSK guard column HXL-H", "TSK gel GMHXL (. times.2)" "TSK gel G2000 HXL" (all manufactured by Tosoh Corp.)

Column temperature: 40 deg.C

Eluting solvent: tetrahydrofuran (THF)

Flow rate: 1.0 mL/min

[ loss tangent (tan. delta) ]

The resin compositions for the intermediate layer used in the examples and comparative examples were applied to a polyethylene terephthalate film-based release film (product name "SP-PET 381031" manufactured by Linekekuki Co., Ltd., thickness: 38 μm) by means of a jet die (fountain die) to form a coating film. Then, ultraviolet rays were irradiated from the coating film side to form a semi-cured layer.

The ultraviolet irradiation device used was a conveyor type ultraviolet irradiation device (product name "ECS-4011 GX" manufactured by Eyegraphics corporation), the ultraviolet irradiation device used was a high pressure mercury lamp (product name "H04-L41" manufactured by Eyegraphics corporation), and the ultraviolet irradiation device used was an irradiation device which irradiated light with an illuminance of 112mW/cm at a wavelength of 365nm²Light quantity 177mJ/cm²Ultraviolet irradiation was performed under the conditions of ultraviolet light measurement using an ultraviolet light meter "UVPF-a 1" manufactured by Eyegraphics.

A polyethylene terephthalate film-based release film (product name "SP-PET 381031" manufactured by Linekeko corporation, thickness 38 μm) was laminated on the formed semi-cured layer, and further subjected to ultraviolet irradiation (using the above-mentioned ultraviolet irradiation apparatus and ultraviolet source, as irradiation conditions, illuminance 271mW/cm²Light quantity 1,200mJ/cm²) The cured product was completely cured to form an intermediate layer having a thickness of 200 μm and having a release film adhered to both surfaces thereof.

5 of the thus-formed intermediate layers were prepared, and a PET-based release film was peeled off, and the peeled surfaces were superposed on each other and sequentially laminated to prepare an intermediate layer laminate (thickness: 1,000 μm).

Then, the obtained intermediate layer laminate was punched out into a circular shape having a diameter of 10mm to obtain a sample for measuring viscoelasticity. The sample was subjected to a strain at a frequency of 1Hz using a viscoelasticity measuring apparatus (product name "ARES" manufactured by TA Instruments), and a storage modulus (G') at-50 to 150 ℃ was measured at a temperature rise rate of 4 ℃/min, and a loss tangent (tan. delta.) at 50 ℃ was obtained.

[ breaking stress ]

An adhesive layer (thickness: 200 μm) having a polyethylene terephthalate release film (product name: SP-PET381031, manufactured by Linekec corporation) attached to both surfaces thereof was prepared. Here, an adhesive layer having a thickness of 40 μm was formed on one release film in the same manner as in examples and comparative examples, and then the other release film was attached to the adhesive layer. 5 pressure-sensitive adhesive layers sandwiched between such release films were prepared, and the surfaces of the pressure-sensitive adhesive layers exposed by peeling off one release film were opposed to each other and laminated. This procedure was repeated to obtain an adhesive layer having a thickness of 200 μm in which 5 adhesive layers were laminated. The adhesive layer laminated body sandwiched between 2 sheets of release films was irradiated with ultraviolet rays under conditions of an illuminance of 220mW/cm and an irradiation speed of 15 mm/sec using a UV irradiation apparatus "RAD-2000 m/12" manufactured by Linekec corporation, and then the cured product of the adhesive layer was cut into pieces of 15 mm. times.150 mm. Then, a label for film stretching was attached to 25mm portions at both ends to prepare a rectangular sample having a measurement target portion of 15mm × 100 mm. The breaking stress was measured at a tensile rate of 200 mm/min using "Autograph AG-IS 500N" manufactured by Shimadzu corporation.

[ adhesive force before energy ray irradiation ]

The adhesive tapes of examples and comparative examples were equally cut into 25mm widths, and the adhesive tapes were temporarily placed on a silicon mirror wafer as an adherend, and a roller weighing 1kg was reciprocated 1 time thereon to apply a load by its own weight to perform adhesion. After the adhesive tape was adhered, the tape was stored at 23 ℃ and 50% relative humidity for 1 hour, and then the adhesive tape was peeled off at a peeling angle of 180 ° and a peeling speed of 300 mm/min using a tensile tester (product name "TENSILON" manufactured by ORIENTEC corporation), and the adhesive force at this time was measured.

[ adhesive force after irradiation with energy ray ]

The adhesive tapes of examples and comparative examples were equally cut into 25mm widths, and the adhesive tapes were temporarily placed on a silicon mirror wafer as an adherend, and a roller weighing 1kg was reciprocated 1 time thereon to apply a load by its own weight to perform adhesion. After the adhesive tape was attached, the tape was stored at 23 ℃ and 50% relative humidity for 1 hour, and then irradiated with ultraviolet light from the tape side at an illumination of 220mW/cm and an irradiation speed of 15 mm/sec by a UV irradiation apparatus "RAD-2000 m/12" manufactured by Lindco, and then left at 23 ℃ and 50% relative humidity for 5 minutes, and then the tape was peeled at a peeling angle of 180 ° and a peeling speed of 300 mm/min by using a tensile tester (product name "TENSILON" manufactured by ORIENTEC corporation), and the adhesive force at this time was measured.

[ evaluation of embeddability ]

The adhesive tapes prepared in examples and comparative examples were bonded to a wafer having spherical bumps with a bump height of 250 μm, a pitch of 500 μm and a diameter of 300 μm in plan view (8-inch wafer, Sn/Ag/Cu bump specification of 96.5/3/0.5 mass%, SiO, which is a material for wafer surfaces) by using a laminator "RAD-3510F/12" manufactured by Leideke corporation₂). In the pasting, the laminating table and the laminating roller of the apparatus were set to 60 ℃. After the lamination, ultraviolet rays were irradiated from the tape side at an illuminance of 220mW/cm and an irradiation speed of 15 mm/sec using a UV irradiation apparatus "RAD-2000 m/12" manufactured by Linekuko. The evaluation wafer to which the adhesive tape thus obtained was attached was measured for the diameter of a circular void generated from the base material side to the periphery of the bump using a digital microscope (product name "VHX-1000" manufactured by KEYENCE corporation), and the embeddability was calculated according to the following equation.

Embeddability is the diameter of the void/diameter of the bump x 100 [% ]

The calculated embeddability was evaluated based on the following evaluation criteria, with the calculated embeddability having a suitable void content of 110% or more and less than 130% being the most suitable.

A: the embeddability is 110% or more and less than 130%

B: the embedding property is 130% or more and less than 140%

C: embedding property of less than 110% or more than 140%

[ evaluation of residual paste on bumps ]

The adhesive tape was peeled from the adhesive tape-attached evaluation wafer produced in the same manner as in the embedding evaluation test at a tensile speed of 120 mm/min under an environment of 23 ℃ and a relative humidity of 50% using a tensile tester (product name "TENSILON" manufactured by ORIENTEC). After the peeling, the wafer was observed for a bump portion using an electron microscope "VE-9800" manufactured by KEYENCE corporation, and the presence or absence of residual paste was confirmed.

[ production of substrate with intermediate layer ]

A resin composition for an intermediate layer was prepared by mixing 40 parts by mass of a monofunctional urethane acrylate, 45 parts by mass of isobornyl acrylate (IBXA), 15 parts by mass of hydroxypropyl acrylate (HPA), 3.5 parts by mass of pentaerythritol tetrakis (3-mercaptobutyrate) (showa electric corporation, product name "Karenz MTPE 1", compound containing 4 secondary thiol groups, solid content concentration 100 parts by mass%), 1.8 parts by mass of a crosslinking agent, and 1.0 part by mass of 2-hydroxy-2-methyl-1-phenylpropan-1-one (product name "DAROCUR 1173", solid content concentration 100 parts by mass%, manufactured by BASF) as a photopolymerization initiator. The resin composition for an intermediate layer was applied to a polyethylene terephthalate film-based release film (product name "SP-PET 381031" manufactured by Linekeko Co., Ltd., thickness 38 μm) by a jet die system to form a coating film.

Then, ultraviolet rays were irradiated from the coating film side to form a semi-cured layer. The ultraviolet irradiation device used was a conveyor type ultraviolet irradiation device (product name "ECS-401 GGX" manufactured by Eyegraphics corporation), the ultraviolet irradiation device used was a high-pressure mercury lamp (product name "H04-L41" manufactured by Eyegraphics corporation), and the ultraviolet irradiation device used was an irradiation device which irradiated light with an illuminance of 112mW/cm at a wavelength of 365nm²Light quantity 177mJ/cm²Ultraviolet irradiation was performed under the condition of the product name "UVPF-A1" manufactured by Eyegraphics.

Polyethylene terephthalate (PET) film (product name "Cosm" manufactured by Toyo chemical Co., Ltd.)o Shine A4100 ″, thickness 50 μm) was laminated on the semi-cured layer formed, and further irradiated with ultraviolet light from the PET film side (using the above-mentioned ultraviolet irradiation apparatus and ultraviolet source, as irradiation conditions, illuminance 271mW/cm²Light quantity 1200mJ/cm²) The resulting mixture was completely cured to form an intermediate layer having a thickness of 300 μm on the PET film of the substrate, thereby obtaining a substrate with an intermediate layer.

The loss tangent (tan. delta.) of the intermediate layer at 50 ℃ measured at a frequency of 1Hz was 1.92.

In the following examples and comparative examples, each part by mass represents a value obtained by diluting a solution with a diluent in terms of a solid content.

[ example 1]

As the urethane polymer (A '), a polyurethane polyol having a urethane skeleton and a plurality of hydroxyl groups (product name "SH-101" and weight average molecular weight: 100,000 ", manufactured by TOYOCHEM Co., Ltd.) was prepared, and 100 parts by mass of the urethane polymer (A') was added with 32 parts by mass of urethane acrylate having a plurality of isocyanate groups (product name" EBECRYL4150 "and weight average molecular weight: 1,040) as a crosslinking agent (C1) (product name" EBECRYL4150 "and weight average molecular weight: 1,040) and a mixture (mass ratio (C: D): 40: 60) of pentaerythritol tetraacrylate as the energy ray-curable compound (B) and pentaerythritol triacrylate (formula: 298) as the compound (D) (product name" A-TMM-3LM-N "manufactured by Nikamurakamura chemical Co., Ltd.) 17 parts by mass, 5 parts by mass of 2, 2-dimethoxy-1, 2-diphenylethan-1-one (product name "Irgacure 651" manufactured by BASF Co.) as the energy ray polymerization initiator (E) and 1 part by mass of a polyisocyanate compound (T-501B "manufactured by TOYOCHEM Co.) as the crosslinking agent (C2) were stirred for 10 minutes and diluted with toluene to prepare an adhesive composition having a solid content concentration of 40 mass%.

Then, the prepared adhesive composition was applied to a polyethylene terephthalate release film (product name "SP-PET 381031" manufactured by Linekeko corporation, thickness 38 μm), and heated at 100 ℃ for 2 minutes to dry, thereby forming an adhesive layer having a thickness of 10 μm on the release film.

Then, the release film on the previously produced intermediate layer-attached substrate was removed, the adhesive layer on the release film was bonded to the exposed intermediate layer, and then unnecessary portions of the ends in the width direction were cut off and removed to obtain an adhesive tape provided with the substrate, the intermediate layer, the adhesive layer, and the release film in this order. The evaluation results of the pressure-sensitive adhesive tape are shown in table 1.

[ example 2]

An adhesive tape was produced in the same manner as in example 1 except that the urethane polymer (a') was changed to "SP-205" (weight average molecular weight: 98,000) manufactured by TOYOCHEM corporation, to prepare an adhesive composition.

[ example 3]

An adhesive tape was produced in the same manner as in example 1 except that 17 parts by mass of "a-TMM-3 LM-N" was changed to 100 parts by mass of urethane acrylate (product name "UN-6200", 2 functional group, weight average molecular weight 6,270, manufactured by wako pure chemical industries, ltd.) as the energy ray curable compound (B) to prepare an adhesive composition.

[ example 4]

An adhesive tape was produced in the same manner as in example 3, except that the urethane polymer (a') was changed to "SP-205" manufactured by TOYOCHEM corporation to prepare an adhesive composition.

[ example 5]

An adhesive tape was produced in the same manner as in example 1 except that 17 parts by mass of "a-TMM-3 LM-N" was changed to 100 parts by mass of urethane acrylate (6-functional, weight average molecular weight 33,000) as the energy ray-curable compound (B).

Comparative example 1

An acrylic copolymer (weight average molecular weight: 900,000, solid content: 35 mass%) to which methacryloyl groups were added was prepared by adding 2-isocyanatoethyl methacrylate (product name "Karenz MOI" manufactured by showa electric corporation) to an acrylic copolymer obtained by polymerizing 94 parts by mass of 2-ethylhexyl acrylate and 6 parts by mass of 2-hydroxyethyl acrylate, and the addition rate of the methacrylic copolymer to hydroxyl groups in the acrylic copolymer was 50% on a molar basis. To 100 parts by mass of this copolymer were added 3 parts by mass of 1-hydroxycyclohexyl phenyl ketone (product name "Irgacure 184" manufactured by BASF) as a photopolymerization initiator and 0.8 part by mass of a polyisocyanate compound (product name "BHS-8515" manufactured by TOYOCHEM) as a crosslinking agent, and the mixture was stirred for 30 minutes to prepare an acrylic pressure-sensitive adhesive composition. The obtained acrylic pressure-sensitive adhesive composition was applied to a polyethylene terephthalate release film (product name "SP-PET 381031" manufactured by Linekekeko Co., Ltd., thickness 38 μm) and dried to form a pressure-sensitive adhesive layer having a thickness of 10 μm.

The release film on the previously produced intermediate layer-attached substrate was removed, the exposed intermediate layer was attached to the adhesive layer on the release film, and then unnecessary portions of the ends in the width direction were cut off to obtain an adhesive tape in which the substrate, the intermediate layer, the adhesive layer, and the release film were sequentially provided. The evaluation results of the pressure-sensitive adhesive tape are shown in table 1.

Comparative example 2

2-isocyanatoethyl methacrylate (product name "Karenz MOI" manufactured by Showa Denko K.K.) was added to an acrylic copolymer obtained by polymerizing 90 parts by mass of 2-ethylhexyl acrylate and 10 parts by mass of 4-hydroxybutyl acrylate so that the addition rate of the resulting mixture to hydroxyl groups in the acrylic copolymer was 65% by mole, thereby obtaining an acrylic copolymer to which methacryloyl groups were added (weight-average molecular weight: 1,000,000, solid content: 25% by mass). To 100 parts by mass of this copolymer were added 3 parts by mass of 1-hydroxycyclohexyl phenyl ketone (product name "Irgacure 184" manufactured by BASF) as a photopolymerization initiator and 1.1 parts by mass of a polyisocyanate compound (product name "BHS-8515" manufactured by TOYOCHEM) as a crosslinking agent, and the mixture was stirred for 30 minutes to prepare an acrylic pressure-sensitive adhesive composition. Except for this, an adhesive tape was produced in the same manner as in comparative example 1.

Comparative example 3

2-isocyanatoethyl methacrylate (product name "Karenz MOI" manufactured by Showa Denko K.K.) was added to an acrylic copolymer obtained by polymerizing 90 parts by mass of 2-ethylhexyl acrylate and 10 parts by mass of 4-hydroxybutyl acrylate so that the molar number of the acrylic copolymer was 75% based on the hydroxyl groups in the acrylic copolymer, thereby obtaining an acrylic copolymer to which methacryloyl groups were added (weight average molecular weight: 1,000,000, solid content: 25% by mass).

To 100 parts by mass of this copolymer were added 5 parts by mass of 1-hydroxycyclohexyl phenyl ketone (product name "Irgacure 184" manufactured by BASF) as a photopolymerization initiator and 1.2 parts by mass of a polyisocyanate compound (product name "BHS-8515" manufactured by TOYOCHEM) as a crosslinking agent, and the mixture was stirred for 30 minutes to prepare an acrylic pressure-sensitive adhesive composition. Except for this, an adhesive tape was produced in the same manner as in comparative example 1.

Comparative example 4

An adhesive tape was produced in the same manner as in example 1, except that "A-TMM-3 LM-N" was not added.

[ Table 1]

In examples 1 to 5 described above, the adhesive composition was a urethane, and the urethane resin (a) contained the unreacted energy ray-curable compound (B), whereby the embedding property of the bump (the following property of the adhesive layer to the surface shape of the work) was improved, the breaking stress was increased, and the residual paste at the time of peeling was prevented. Further, the adhesive strength before curing by energy ray is improved and the adhesive strength after curing can be sufficiently reduced, so that the releasability and the adhesiveness are excellent.

On the other hand, in comparative examples 1 to 3, the adhesive composition was acrylic, and the breaking stress was low, so that residual paste could not be prevented. In comparative example 4, the adhesive layer was poor in flexibility and insufficient in embeddability because the energy ray-curable compound (B) was not contained although it was a urethane.

Claims (14)

1. An adhesive tape for processing a workpiece, comprising a base material and an adhesive layer provided on one surface side of the base material,

the adhesive layer contains a urethane resin (A) and an energy ray-curable compound (B) which does not react with the urethane resin (A), has a photopolymerizable unsaturated bond, and has a molecular weight of 35,000 or less,

the urethane resin (A) has a photopolymerizable unsaturated bond,

the adhesive layer is formed from an adhesive composition containing at least a urethane polymer (A'), the energy ray-curable compound (B) and a crosslinking agent (C),

the urethane resin (A) is obtained by crosslinking a urethane polymer (A') with the crosslinking agent (C),

the weight average molecular weight of the urethane polymer (A') is 10000 to 300000,

the amount of the main-agent-reactive compound and the urethane polymer (A ') is 40 to 95 mass% in total relative to the total amount of the adhesive composition, the main-agent-reactive compound being a compound directly or indirectly bonded to the urethane polymer (A ') and constituting the urethane resin (A) integrally with the urethane polymer (A ') in the adhesive layer,

the non-reaction with the urethane resin (a) means that the urethane resin (a) does not contain a functional group that reacts with the urethane polymer (a') other than the "photopolymerizable unsaturated bond" and does not contain a functional group that reacts with the main agent reactive compound.

2. The adhesive tape for processing workpieces as claimed in claim 1, wherein the energy ray-curable compound (B) is at least 1 selected from a (meth) acrylate monomer (B1) and a urethane (meth) acrylate (B2).

3. The adhesive tape for processing workpieces as claimed in claim 2, wherein the energy ray-curable compound (B) contains at least a (meth) acrylate monomer (B1), and the (meth) acrylate monomer (B1) is a polyfunctional (meth) acrylate which is a complete ester of a polyol and a (meth) acrylic acid.

4. The adhesive tape for processing a workpiece according to any one of claims 1 to 3, wherein the energy ray-curable compound (B) has 2 or more (meth) acryloyl groups in 1 molecule.

5. The adhesive tape for processing workpieces as claimed in any one of claims 1 to 3, wherein the crosslinking agent (C) comprises a crosslinking agent (C1) containing a photopolymerizable unsaturated bond.

6. The adhesive tape for processing a workpiece according to any one of claims 1 to 3, wherein the urethane polymer (A') and the crosslinking agent (C) are bonded to each other via a urethane bond.

7. The adhesive tape for processing workpieces as claimed in any one of claims 1 to 3, wherein the adhesive composition further contains a compound (D) having a photopolymerizable unsaturated bond and a reactive functional group capable of reacting with the crosslinking agent (C).

8. The adhesive tape for processing workpieces as claimed in claim 7, wherein the compound (D) is a polyfunctional (meth) acrylate which is a partially esterified product of a polyol and (meth) acrylic acid.

9. The adhesive tape for processing a workpiece according to any one of claims 1 to 3, wherein the adhesive layer has a breaking stress of 2.5MPa or more after irradiation with an energy ray.

10. The adhesive tape for processing a workpiece according to any one of claims 1 to 3, wherein an intermediate layer is provided between the base material and the adhesive layer.

11. The adhesive tape for processing workpieces as claimed in claim 10, wherein the thickness of the intermediate layer is 10 to 600 μm.

12. The adhesive tape for processing workpieces according to claim 10, wherein the loss tangent of the intermediate layer at 50 ℃ measured at a frequency of 1Hz is 1.0 or more.

13. The adhesive tape for processing a workpiece according to any one of claims 1 to 3, which has an adhesive force of 2000mN/25mm or less after irradiation with an energy ray.

14. The adhesive tape for workpiece processing according to any one of claims 1 to 3, which is an adhesive tape for protecting a surface of a semiconductor wafer.