WO2016175112A1

WO2016175112A1 - Adhesive tape for work processing

Info

Publication number: WO2016175112A1
Application number: PCT/JP2016/062581
Authority: WO
Inventors: 雄一朗小升; 泰史藤本
Original assignee: リンテック株式会社
Priority date: 2015-04-30
Filing date: 2016-04-21
Publication date: 2016-11-03
Also published as: KR20170140221A; SG11201708797YA; KR102528633B1; CN108307635B; TWI778939B; TW201710428A; CN108307635A; JP6541775B2; JPWO2016175112A1

Abstract

This adhesive tape for work processing is provided with a base and an adhesive layer that is arranged on one surface of the base. The adhesive layer contains (A) a urethane resin and (B) an energy ray-curable compound that is not reactive with the urethane resin (A), while having a photopolymerizable unsaturated bond and a molecular weight of 35,000 or less.

Description

Adhesive tape for workpiece processing

The present invention relates to a workpiece processing adhesive tape, and more particularly to a semiconductor wafer surface protecting adhesive tape used for protecting the surface of a bumped semiconductor wafer.

As information terminal devices are rapidly becoming thinner, smaller, and multifunctional, semiconductor devices mounted on them are also required to be thinner and denser, and semiconductor wafers are also required to be thinner. ing. Conventionally, in order to meet the demand, the back surface of a semiconductor wafer is ground and thinned. 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 semiconductor wafer with bumps is subjected to back grinding, a surface protective sheet may be attached to the wafer surface on which the bumps are formed in order to protect the bump portions.

Conventionally, as a surface protection sheet, a sheet including a resin layer in which the storage elastic modulus at 25 ° C. and 60 ° C. is adjusted to be in a specific range is known (for example, see Patent Document 1). This surface protective sheet is formed by attaching a resin layer having a drop in storage elastic modulus at room temperature (25 ° C.) and storage elastic modulus at high temperature (60 ° C.) to attach it to a wafer surface having an uneven portion at high temperature. The resin layer is softened, the unevenness of the wafer surface is absorbed, and the height difference of the wafer surface is reduced.

Moreover, as a surface protection sheet, in order to make adhesiveness and peelability favorable, two resin layers which have a predetermined tensile elastic modulus are provided on a base material, and a sticking surface is provided among these two resin layers. It is known that the side resin layer is formed of a thermoplastic elastomer such as a polystyrene-based elastomer, a polyolefin-based elastomer, a polyurethane-based elastomer, and a polyester-based elastomer (see Patent Document 2).

Furthermore, as a surface protective sheet, an adhesive tape in which an intermediate layer and an adhesive layer are provided on one surface of a substrate is also known. In this pressure-sensitive adhesive tape, it is known that the storage elastic modulus at 25 ° C. of the intermediate layer is set to about 30 to 1000 kPa and the pressure-sensitive adhesive layer is formed of an energy ray curable pressure-sensitive adhesive in order to increase unevenness absorbability. (For example, refer to Patent Document 3). When an energy ray curable pressure sensitive adhesive is used for the surface protection sheet as in Patent Document 3, it becomes easy to improve the sticking property to the semiconductor wafer and the peelability. Conventionally, the energy ray-curable pressure-sensitive adhesive used in the surface protective sheet is mainly used in the acrylic type because the adhesiveness is easily adjusted and the embedding property of the bumps is easily secured.

Japanese Patent No. 4603578 Japanese Patent No. 4918181 Japanese Patent No. 4367769

By the way, in recent years, as the density and size of semiconductor devices are further increased, the bump height tends to increase, and those having a height of 200 μm or more are being studied. However, for a semiconductor wafer having a high bump height and a large height difference, if an acrylic surface protection sheet described in Patent Document 3 is used, an adhesive residue (adhesive residue) is left on the bump when the sheet is peeled off. Many may occur. This is because the acrylic energy ray curable pressure-sensitive adhesive has relatively low cohesive force and mechanical strength.
On the other hand, for example, in Patent Documents 1 and 2, the use of materials other than acrylic pressure-sensitive adhesives such as polyurethane-based elastomers on the application surface of the surface protection sheet has been studied. However, in Patent Documents 1 and 2, the application of these materials to an energy ray curable pressure-sensitive adhesive is not considered, and further improvements are required to ensure adhesion, peelability, and bump embedding. is necessary.

The present invention has been made in view of the above circumstances, and an object of the present invention is to a surface shape of a work represented by adhesion to a work such as a semiconductor wafer, releasability, and embedding of bumps. It is to provide a work processing pressure-sensitive adhesive tape with less adhesive residue on the surface of the work, even if the work to be applied has a non-flat surface shape while improving the followability of the pressure-sensitive adhesive layer.

As a result of intensive studies, the present inventors have found that the above-mentioned problems can be solved by using a urethane-based pressure-sensitive adhesive as the pressure-sensitive adhesive and making the composition specific, and have completed the following present invention. The present invention provides the following adhesive tapes for processing workpieces (1) to (16).
(1) A substrate and a pressure-sensitive adhesive layer provided on one surface side of the substrate,
Energy ray-curable compound in which the pressure-sensitive adhesive layer is non-reactive with the urethane resin (A) and the urethane resin (A), has a photopolymerizable unsaturated bond, and has a molecular weight of 35,000 or less. An adhesive tape for work processing comprising (B).
(2) Work processing according to the above (1), wherein the energy ray curable compound (B) is at least one selected from a (meth) acrylate monomer (B1) and a urethane (meth) acrylate (B2). Adhesive tape.
(3) The energy ray curable compound (B) contains at least a (meth) acrylate monomer (B1), and the (meth) acrylate monomer (B1) is a polyhydric alcohol and a complete (meth) acrylic acid. The pressure-sensitive adhesive tape for workpiece processing according to the above (2), which is a polyfunctional (meth) acrylic acid ester which is an ester.
(4) The work processing pressure-sensitive adhesive tape according to any one of (1) to (3), wherein the energy ray-curable compound (B) has two or more (meth) acryloyl groups in one molecule.
(5) The pressure-sensitive adhesive tape for workpiece processing according to any one of the above (1) to (4), wherein the urethane resin (A) has a photopolymerizable unsaturated bond.
(6) The pressure-sensitive adhesive layer is formed from a pressure-sensitive adhesive composition containing at least a urethane polymer (A ′), the energy ray-curable compound (B), and a crosslinking agent (C).
6. The work processing pressure-sensitive adhesive tape according to any one of the above (1) to (5), wherein the urethane resin (A) is obtained by crosslinking the urethane polymer (A ′) with the crosslinking agent (C).
(7) The work processing pressure-sensitive adhesive tape according to (6), wherein the crosslinking agent (C) includes a crosslinking agent (C1) containing a photopolymerizable unsaturated bond.
(8) The work processing pressure-sensitive adhesive tape according to (6) or (7), wherein the urethane polymer (A ′) and the cross-linking agent (C) are bonded by a urethane bond.
(9) The above (6) to (8), wherein the pressure-sensitive adhesive composition further comprises a compound (D) having a photopolymerizable unsaturated bond and a reactive functional group capable of reacting with the crosslinking agent (C). ) The adhesive tape for workpiece processing according to any one of the above.
(10) The work processing pressure-sensitive adhesive tape according to (9), wherein the compound (D) is a polyfunctional (meth) acrylic ester which is a partial ester of polyhydric alcohol and (meth) acrylic acid.
(11) The work processing pressure-sensitive adhesive tape according to any one of (1) to (10), wherein the pressure-sensitive adhesive layer has a breaking stress after irradiation with energy rays of 2.5 MPa or more.
(12) The work processing pressure-sensitive adhesive tape according to any one of (1) to (11), wherein an intermediate layer is provided between the substrate and the pressure-sensitive adhesive layer.
(13) The pressure-sensitive adhesive tape for workpiece processing according to (12), wherein the intermediate layer has a thickness of 10 to 600 μm.
(14) The work processing pressure-sensitive adhesive tape according to (12) or (13), wherein the intermediate layer has a loss tangent at 50 ° C. measured at a frequency of 1 Hz of 1.0 or more.
(15) The pressure-sensitive adhesive tape for workpiece processing according to any one of the above (1) to (14), wherein the adhesive strength after irradiation with energy rays is 2000 mN / 25 mm or less.
(16) The work processing pressure-sensitive adhesive tape according to any one of the above (1) to (15), which is a semiconductor wafer surface protecting pressure-sensitive adhesive tape.

In the present invention, it is possible to provide a pressure-sensitive adhesive tape for work processing with less adhesive residue on the work surface while improving the pressure-sensitive adhesiveness, peelability, and followability of the pressure-sensitive adhesive layer to the surface shape of the work.

In the following description, “weight average molecular weight (Mw)” is a value in terms of polystyrene measured by gel permeation chromatography (GPC), and specifically measured based on the method described in the examples. Value.
In the description of the present specification, for example, “(meth) acrylate” is used as a word indicating both “acrylate” and “methacrylate”, and the same applies to other similar terms.

Hereinafter, the present invention will be described using embodiments.
The pressure-sensitive adhesive tape for workpiece processing of the present invention (hereinafter also simply referred to as “pressure-sensitive adhesive tape”) includes a base material and a pressure-sensitive adhesive layer provided on one surface side of the base material. Moreover, the adhesive tape may have an intermediate | middle layer between this base material and an adhesive layer. The adhesive tape may be composed of two or three layers as described above, and may be further provided with other layers. For example, a release material may be further provided on the pressure-sensitive adhesive layer.
Hereinafter, each member which comprises an adhesive tape is demonstrated in detail.

<Base material>
Although the base material used for an adhesive tape is not specifically limited, It is preferable that it is a resin film. Resin films are preferable because they are less likely to generate dust than paper and non-woven fabrics, are suitable for processed parts of electronic parts, and are easily available. The substrate may be a single layer film made of one resin film or a multilayer film in which a plurality of resin films are laminated.
Examples of the resin film used as the base material include polyolefin film, vinyl halide polymer film, acrylic resin film, rubber film, cellulose film, polyester film, polycarbonate film, polystyrene film, and polyphenylene sulfide. Examples thereof include a system film and a cycloolefin polymer film.
Among these, from the viewpoint that the wafer can be stably held when grinding the wafer to an extremely thin thickness, and from the viewpoint of being a film having a high thickness accuracy, a polyester film is preferable, and among the polyester films, From the viewpoint of easy availability and high thickness accuracy, a polyethylene terephthalate film is preferred.
The thickness of the substrate is not particularly limited, but is preferably 10 to 200 μm, more preferably 25 to 150 μm.

In addition, you may use the base material which laminated | stacked the easily bonding layer or the adhesive layer further on the surface of the resin film from a viewpoint of improving the adhesiveness with respect to the adhesive layer or intermediate | middle layer of a base material. Furthermore, the base material used in the present invention may 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 may be colored as desired, but is preferably one that transmits energy rays to a degree sufficient to cure the pressure-sensitive adhesive layer.

<Intermediate layer>
In the pressure-sensitive adhesive tape of the present invention, an intermediate layer may be provided on one surface of the substrate. The pressure-sensitive adhesive tape of the present invention has an intermediate layer, so that the bumps are provided in the pressure-sensitive adhesive layer and the intermediate layer even when the bumps are provided on the work and the unevenness of the surface of the work is large. Thereby, it becomes easy to keep the surface on the opposite side to the surface affixed to the workpiece | work of an adhesive tape flat. The intermediate layer used in the present invention preferably has a loss tangent (tan δ) (hereinafter also simply referred to as “loss tangent”) at 50 ° C. measured at a frequency of 1 Hz of 1.0 or more.
When the loss tangent of the intermediate layer is such a value, when the work processing pressure-sensitive adhesive tape is attached to an uneven work such as a wafer with bumps, the intermediate layer is sufficiently deformed and can easily follow the unevenness. From the viewpoint of the intermediate layer sufficiently absorbing irregularities such as bumps and obtaining a good sticking state on the surface of the wafer with bumps, for example, the loss tangent of the intermediate layer is more preferably 1.5 or more, and still more preferably 1. 65 or more, more preferably 1.8 or more.
Further, from the viewpoint of adjusting the fluidity during heating of the intermediate layer to an appropriate range, the loss tangent of the intermediate layer is preferably 5.0 or less, more preferably 4.0 or less.
The above-mentioned loss tangent of the intermediate layer is more specifically a value measured based on the method described in Examples described later.

Further, the thickness of the intermediate layer can be appropriately adjusted according to the state of the adherend surface to which the adhesive tape is affixed, but it is preferable from the viewpoint of being able to absorb relatively high bumps. Is 10 to 600 μm, more preferably 25 to 550 μm, still more preferably 35 to 500 μm.

An intermediate | middle layer is formed from the resin composition for intermediate | middle layers. Moreover, it is preferable that the resin composition for intermediate | middle layers contains urethane (meth) acrylate.
(Urethane (meth) acrylate (X))
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 energy rays. In addition, an energy ray has an energy quantum in electromagnetic waves or a charged particle beam, and points out active light, such as an ultraviolet-ray, or an electron beam.
The number of (meth) acryloyl groups in the urethane (meth) acrylate (X) may be monofunctional, bifunctional, or trifunctional or higher, but in order to make the loss tangent 1.0 or higher, the resin composition for the intermediate layer Preferably contains a monofunctional urethane (meth) acrylate. This is because the monofunctional urethane (meth) acrylate does not participate in the formation of the three-dimensional network structure in the polymerization structure, and therefore, the three-dimensional network structure is hardly formed in the intermediate layer, and the loss tangent is easily increased.

As urethane (meth) acrylate (X) used for the resin composition for intermediate layers, for example, a terminal isocyanate urethane prepolymer obtained by reacting a polyol compound and a polyisocyanate compound has a (meth) acryloyl group. It can be obtained by reacting a compound. Urethane (meth) acrylate (X) may be used alone or in combination of two or more.

[Polyol compound]
The polyol compound is not particularly limited as long as it is a compound having two or more hydroxy groups.
Specific examples of the polyol compound include alkylene diol, polyether type polyol, polyester type polyol, and polycarbonate type polyol.
Among these, polyether type polyols are preferable.
The polyol compound may be a bifunctional diol, a trifunctional triol, or a tetrafunctional or higher polyol, but from the viewpoint of availability, versatility, reactivity, etc., a bifunctional diol Are preferred, and polyether type diols are more preferred.

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

In the above formula (1), R is a divalent hydrocarbon group, preferably an alkylene group, more preferably an alkylene group having 1 to 6 carbon atoms. Among the alkylene groups having 1 to 6 carbon atoms, an ethylene group, a propylene group, and a tetramethylene group are preferable, and a propylene group and a tetramethylene group are more preferable.
N is the number of repeating units of alkylene oxide, preferably 10 to 250, more preferably 25 to 205, and still more preferably 40 to 185. If n is the said range, it will become easy to prepare an intermediate | middle layer so that the urethane bond density | concentration of the urethane (meth) acrylate obtained may be moderated, and a loss tangent may satisfy | fill the said requirements.
Among the compounds represented by the formula (1), polyethylene glycol, polypropylene glycol, and polytetramethylene glycol are preferable, and polypropylene glycol and polytetramethylene glycol are more preferable.
By reacting the polyether type diol with the polyisocyanate compound, a terminal isocyanate urethane prepolymer having an ether bond [-(-RO-) n-] introduced therein is produced. By using such a polyether type diol, the urethane (meth) acrylate contains a structural unit derived from the polyether type diol.

The polyester type polyol is obtained by polycondensation of a polyol component and a polybasic acid component. Examples of the polyol component include ethylene glycol, diethylene glycol, triethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,3-butanediol, 1,4-butanediol, neopentyl glycol, pentanediol, 3-methyl-1,5-pentanediol, 2,2,4-trimethyl-1,3-pentanediol, hexanediol, octanediol, 2,2-diethyl-1,3-propanediol, 2-ethyl-2 -Known various glycols such as butyl-1,3-propanediol, 1,4-cyclohexanedimethanol, ethylene glycol or propylene glycol adduct of bisphenol A, and the like.
As the polybasic acid component used for the production of the polyester type polyol, a compound generally known as a polybasic acid component of 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, and suberic acid; Dibasic acids such as phthalic acid, isophthalic acid, terephthalic acid, 2,6-naphthalenedicarboxylic acid, aromatic polybasic acids such as polybasic acids such as trimellitic acid and pyromellitic acid, anhydrides corresponding to these, The derivative | guide_body, dimer acid, hydrogenated dimer acid, etc. are mentioned. Among these, an aromatic polybasic acid is preferable from the viewpoint of forming a coating film having an appropriate hardness. In the esterification reaction for producing the polyester-type 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-described glycols and 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. If the number average molecular weight is 1,000 or more, a situation in which it becomes difficult to control the viscoelastic properties of the intermediate layer due to the generation of an excessive amount of urethane bonds is preferable. On the other hand, if the number average molecular weight is 10,000 or less, it is preferable because the obtained intermediate layer can be prevented from being excessively softened.
The number average molecular weight calculated from the hydroxyl value of the polyol compound is a value calculated from [number of polyol functional groups] × 56.11 × 1000 / [hydroxyl value (unit: mgKOH / g)].

[Polyisocyanate compound]
Examples of the polyisocyanate compound include aliphatic polyisocyanates such as tetramethylene diisocyanate, hexamethylene diisocyanate, trimethylhexamethylene diisocyanate; isophorone diisocyanate, norbornane diisocyanate, dicyclohexylmethane-4,4′-diisocyanate, dicyclohexylmethane-2,4 ′. -Cycloaliphatic diisocyanates such as diisocyanate, ω, ω'-diisocyanate dimethylcyclohexane; 4,4'-diphenylmethane diisocyanate, tolylene diisocyanate, xylylene diisocyanate, tolidine diisocyanate, tetramethylene xylylene diisocyanate, naphthalene-1,5- And aromatic diisocyanates such as diisocyanate.
Among these, isophorone diisocyanate, hexamethylene diisocyanate, and xylylene diisocyanate are preferable from the viewpoint of handleability.

{Compound having (meth) acryloyl group}
Examples of the compound having a (meth) acryloyl group include a (meth) acrylate having a hydroxy group. The (meth) acrylate having a hydroxy group is not particularly limited as long as it is a compound having a hydroxy group and a (meth) acryloyl group in at least one molecule.
Specific examples of the (meth) acrylate having a hydroxy group include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, and 4-hydroxycyclohexyl (meth). Acrylate, 5-hydroxycyclooctyl (meth) acrylate, 2-hydroxy-3-phenyloxypropyl (meth) acrylate, pentaerythritol tri (meth) acrylate, polyethylene glycol mono (meth) acrylate, polypropylene glycol mono (meth) acrylate, etc. Hydroxy-alkyl (meth) acrylates; hydroxy-group-containing (meth) acrylamides such as N-methylol (meth) acrylamide; vinyl alcohol, vinyl phenol, bisphenol The reaction product obtained by the diglycidyl ester of Nord A (meth) acrylic acid is reacted, and the like.
Among these, hydroxyalkyl (meth) acrylate is preferable, and 2-hydroxyethyl (meth) acrylate is more preferable.

The weight average molecular weight of the urethane (meth) acrylate (X) for the intermediate layer resin composition thus obtained is preferably 1,000 to 100,000, more preferably 3,000 to 80,000, Preferably, it is 5,000 to 65,000. If the weight average molecular weight is 1,000 or more, in the polymer of urethane (meth) acrylate and a polymerizable monomer described later, due to the intermolecular force between the structures derived from urethane (meth) acrylate, This is preferable because moderate hardness is imparted to the intermediate layer.
The blending amount of urethane (meth) acrylate (X) in the resin composition for an intermediate layer is preferably 20 to 70% by mass, more preferably 25 to 60% by mass, and further preferably 30 to 50% based on the total amount of the composition. The mass is more preferably 33 to 47% by mass. If the blending amount of urethane (meth) acrylate is within such a range, an intermediate layer having a high loss tangent can be easily formed.

In addition to the urethane (meth) acrylate (X), the intermediate layer resin composition further contains, for example, a thiol group-containing compound (Y) or a polymerizable monomer (Z). It is preferable to do.
(Thiol group-containing compound (Y))
The thiol group-containing compound (Y) is not particularly limited as long as it is a compound having at least one thiol group in the molecule, but from the viewpoint of easily increasing the loss tangent, a polyfunctional thiol group-containing compound is preferable. A tetrafunctional thiol group-containing compound is more preferred.
Specific examples of the thiol group-containing compound (Y) include nonyl mercaptan, 1-dodecanethiol, 1,2-ethanedithiol, 1,3-propanedithiol, triazinethiol, triazinedithiol, triazinetrithiol, 1,2 , 3-propanetrithiol, tetraethylene glycol-bis (3-mercaptopropionate), trimethylolpropane tris (3-mercaptopropionate), pentaerythritol tetrakis (3-mercaptopropionate), pentaerythritol tetrakisthio Glucolate, dipentaerythritol hexakis (3-mercaptopropionate), tris [(3-mercaptopropionyloxy) -ethyl] -isocyanurate, 1,4-bis (3-mercaptobutyryloxy) Butane, pentaerythritol tetrakis (3-mercaptobutyrate), 1,3,5-tris (3-mercaptobutyloxyethyl) -1,3,5-triazine-2,4,6- (1H, 3H, 5H) -Triions and the like.
In addition, you may use these thiol group containing compounds (Y) 1 type or in combination of 2 or more types.

The molecular weight of the thiol group-containing compound (Y) is preferably 200 to 3,000, more preferably 300 to 2,000. If the said molecular weight is the said range, compatibility with urethane (meth) acrylate (X) will become favorable and film forming property can be made favorable.
The amount of the thiol group-containing compound (Y) is preferably 1.0 to 4.9 masses per 100 mass parts in total of the urethane (meth) acrylate (X) and the polymerizable monomer (Z) described later. Parts, more preferably 1.5 to 4.8 parts by mass.
When the blending amount is 1.0 part by mass or more, an intermediate layer having a high loss tangent can be easily formed, and the pump absorbability can be improved. On the other hand, if the said compounding quantity is 4.9 mass parts or less, the seepage of the intermediate | middle layer at the time of winding up in roll shape etc. can be suppressed.

(Polymerizable monomer (Z))
It is preferable that the resin composition for intermediate layers used in the present invention further contains a polymerizable monomer (Z) from the viewpoint of improving the film forming property. The polymerizable monomer (Z) is a polymerizable compound other than the urethane (meth) acrylate (X), and is a compound that can be polymerized with other components by irradiation with energy rays. However, the polymerizable monomer (Z) means one excluding the resin component. The polymerizable monomer (Z) is preferably a compound having at least one (meth) acryloyl group.
In the present specification, the “resin component” refers to an oligomer or high molecular weight body having a repeating structure in the structure, and refers to a compound having a weight average molecular weight of 1,000 or more.

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

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, octa Sil (meth) acrylate, eicosyl (meth) acrylate.

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; (meth) acrylamide, N, N -Dimethyl (meth) acrylamide, N-butyl (meth) acrylamide, N-methylol (meth) acrylamide, N-methylolpropane (meth) acrylamide, N-methoxymethyl (meth) acrylamide, N-butoxymethyl (meth) acrylamide, etc. Amide group-containing compounds: primary amino group-containing (meth) acrylates, secondary amino group-containing (meth) acrylates, tertiary amino group-containing (meth) acrylates and other amino group-containing (meth) acrylates; glycidyl ( Meta) Acrylate, and epoxy groups such as methyl glycidyl (meth) acrylate (meth) acrylate.

Examples of the (meth) acrylate having an alicyclic structure include isobornyl (meth) acrylate, dicyclopentenyl (meth) acrylate, dicyclopentanyl (meth) acrylate, dicyclopentenyloxy (meth) acrylate, and cyclohexyl (meth) ) Acrylate, adamantane (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 and morpholine (meth) acrylate.

Among these, from the viewpoint of compatibility with the urethane (meth) acrylate (X), those having a relatively bulky group are preferable, and more specifically, (meth) acrylate having an alicyclic structure, A (meth) acrylate having an aromatic structure and a (meth) acrylate having a heterocyclic structure are preferable, and a (meth) acrylate having an alicyclic structure is more preferable. In addition, from the viewpoint of easily making the loss tangent 1.0 or more, the polymerizable monomer preferably includes a (meth) acrylate having a functional group and a (meth) acrylate having an alicyclic structure. More preferably, it includes (meth) acrylate and isobornyl (meth) acrylate.

From the above viewpoint, the blending amount of the (meth) acrylate having an alicyclic structure in the intermediate layer resin composition is preferably 32 to 53% by mass, more preferably 35 to 51% by mass, based on the total amount of the composition. More preferably, it is 37 to 48% by mass, and still more preferably 40 to 47% by mass.
Further, the blending amount of the (meth) acrylate having an alicyclic structure with respect to the total amount of the polymerizable monomer (Z) contained in the intermediate layer resin composition is preferably 52 to 87% by mass from the above viewpoint. More preferably, it is 55 to 85% by mass, still more preferably 60 to 80% by mass, and still more preferably 65 to 77% by mass. When the blending amount of the (meth) acrylate having an alicyclic structure is in such a range, the loss tangent is easily set to 1.0 or more.

The blending amount of the polymerizable monomer (Z) in the intermediate layer resin composition is preferably 30 to 80% by mass, more preferably 40 to 75% by mass, still more preferably 50 to 70% by mass, and more. More preferably, it is 53 to 67% by mass. If the blending amount of the polymerizable monomer (Z) is within such a range, the intermediate layer is flexible because the portion formed by polymerization of the polymerizable monomer (Z) in the intermediate layer has high mobility. It becomes easier to form an intermediate layer whose loss tangent satisfies the above requirements.
From the same viewpoint, the mass ratio of urethane (meth) acrylate (X) and polymerizable monomer (Z) in the intermediate layer resin composition [urethane (meth) acrylate / polymerizable monomer] is The ratio is preferably 20/80 to 60/40, more preferably 30/70 to 50/50, and still more preferably 35/65 to 45/55.

(Energy beam polymerization initiator (R))
It is preferable that the resin composition for intermediate | middle layers contains an energy beam polymerization initiator (R) further. By containing the energy ray polymerization initiator (R), the intermediate layer resin composition can be easily cured by energy rays such as ultraviolet rays. Since the energy ray polymerization initiator (R) is generally also referred to as “photopolymerization initiator”, in the present specification, it is also simply referred to as “photopolymerization initiator”.
Examples of the photopolymerization initiator include photopolymerization initiators such as benzoin compounds, acetophenone compounds, acylphosphinoxide compounds, titanocene compounds, thioxanthone compounds, and peroxide compounds, and photosensitizers such as amines and quinones. More specifically, for example, 1-hydroxycyclohexyl phenyl ketone, 2-hydroxy-2-methyl-1-phenyl-propan-1-one, benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, 2 , 2-dimethoxy-1,2-diphenylethane-1-one and the like.
These photopolymerization initiators may be used alone or in combination of two or more.
The blending amount of the photopolymerization initiator is preferably 0.05 to 15 parts by mass, more preferably 0.1 to 10 parts by mass with respect to 100 parts by mass in total of the urethane (meth) acrylate and the polymerizable monomer. More preferably, it is 0.3 to 5 parts by mass.

(Other additives)
The resin composition for intermediate layers may contain other additives as long as the effects of the present invention are not impaired. Examples of other additives include cross-linking agents, antioxidants, softeners (plasticizers), fillers, rust inhibitors, pigments, and dyes. When these additives are blended, the amount of other additives is preferably 0.01 to 6 parts by mass, more preferably 100 parts by mass in total of urethane (meth) acrylate and polymerizable monomer. Is 0.1 to 3 parts by mass.
In addition, in the range which does not impair the effect of this invention, the resin composition for intermediate | middle layers may contain resin components other than urethane (meth) acrylate, but urethane as a resin component It is preferable to contain only (meth) acrylate.
The content of the resin component other than the urethane (meth) acrylate contained in the intermediate layer resin composition is preferably 5% by mass or less, more preferably 1% by mass or less, and still more preferably 0.1% by mass or less. More preferably, it is 0 mass%.

The intermediate layer may be formed of an intermediate layer resin composition containing other resin components instead of 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. . As the non-reactive urethane polymer or oligomer, a known one may be used, and as the polymerizable monomer, the same one as described above can be used. Such a curable composition may contain the energy beam polymerization initiator mentioned above.

The ethylene-α-olefin copolymer is obtained by polymerizing ethylene and an α-olefin monomer. Examples of α-olefin monomers include propylene, 1-butene, 2-methyl-1-butene, 2-methyl-1-pentene, 1-hexene, 2,2-dimethyl-1-butene, and 2-methyl-1-hexene. 4-methyl-1-pentene, 1-heptene, 3-methyl-1-hexene, 2,2-dimethyl-1-pentene, 3,3-dimethyl-1-pentene, 2,3-dimethyl-1-pentene , 3-ethyl-1-pentene, 2,2,3-trimethyl-1-butene, 1-octene, 2,2,4-trimethyl-1-octene, and the like. These α-olefin monomers can be used alone or in combination of two or more.
The ethylene-α-olefin copolymer may be one obtained by polymerizing ethylene, an α-olefin monomer, and another monomer. Examples of 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; methyl acrylate, ethyl acrylate, acrylic acid-n -Unsaturated carboxylic acid esters such as propyl, methyl methacrylate, ethyl methacrylate, methacrylic acid-n-propyl; unsaturated carboxylic acid amides such as acrylamide and methacrylamide. These monomers can be used alone or in combination of two or more.

<Adhesive layer>
An adhesive layer is provided on a base material, and when an intermediate layer is provided, it is provided on the intermediate layer. The pressure-sensitive adhesive layer of the present invention contains at least a urethane resin (A) and an energy ray-curable compound (B) that is non-reactive with the urethane resin (A) and has a molecular weight of 35,000 or less.
In the present invention, since the pressure-sensitive adhesive layer contains the urethane-based resin (A), the cohesive force and mechanical strength of the pressure-sensitive adhesive layer are increased. It is difficult for adhesive residue to occur on the workpiece surface. Moreover, an adhesive layer will have energy-beam sclerosis | hardenability by containing an energy-beam curable compound (B) at least. Therefore, the peeling performance at the time of peeling an adhesive tape from a workpiece | work becomes favorable. Furthermore, since the energy ray curable compound (B) is non-reactive, as will be described later, the storage elastic modulus of the pressure-sensitive adhesive layer becomes low, and it becomes easy to ensure followability to the unevenness of the work surface.

The pressure-sensitive adhesive layer preferably has a breaking stress after irradiation with energy rays of 2.5 MPa or more. When the breaking stress is 2.5 MPa or more, the mechanical strength becomes a sufficient value, and it becomes easy to reduce the above adhesive residue. Further, the breaking stress is preferably 2.8 to 30 MPa, more preferably 3.0 to 25 MPa from the viewpoint of easily improving the embedding property of the protrusion, the adhesiveness of the pressure-sensitive adhesive layer, and the peelability while suppressing adhesive residue. is there. The breaking stress is measured by the method described in Examples described later.
The breaking stress can be adjusted by changing the type of the urethane resin (A). It can also be adjusted by the amount of the photopolymerizable unsaturated bond described later. Increasing the amount of the photopolymerizable unsaturated bond contained in the pressure-sensitive adhesive layer increases the breaking stress, and decreasing it decreases the breaking stress. There is a tendency. Similarly, it can also be adjusted by the amount of the cross-linking agent component described later. When the amount of the cross-linking agent component is increased, the breaking stress tends to increase, and when it is decreased, the breaking stress tends to decrease.

Since the pressure-sensitive adhesive layer is energy ray curable, it can be made relatively soft before energy beam irradiation, and the pressure-sensitive adhesive layer can easily follow the unevenness formed on the workpiece surface. In addition, the adhesive tape is cured by being irradiated with an energy ray, so that the adhesive force is reduced and the adhesive tape is easily peeled off from the workpiece.
From the viewpoint of suppressing the adhesive residue when the adhesive tape is peeled off, the adhesive strength of the adhesive tape after irradiation with energy rays is preferably 2000 mN / 25 mm or less. In particular, when the pressure-sensitive adhesive tape of the present invention having an intermediate layer is applied to a workpiece having bumps or other large protrusions (for example, a height of 200 μm or more) on the surface, the adhesive tape in which the protrusions are usually attached to the surface of the workpiece. This is a state absorbed by the intermediate layer. For this reason, when the adhesive tape is peeled from the adhesive tape, adhesive residue is likely to be generated. However, by setting the adhesive force to 2000 mN / 25 mm or less, it becomes easy to prevent such adhesive residue from occurring. The adhesive strength of the adhesive tape after irradiation with energy rays is preferably 50 to 1750 mN / 25 mm, more preferably 100 to 1500 nN / 25 mm.

Further, the adhesive strength of the adhesive tape before irradiation with energy rays is, for example, greater than 2000 mN / 25 mm, preferably 3000 to 30000 mN / 25 mm, more preferably 3500 to 9000 mN / m. When the adhesive force before energy beam irradiation is in such a range, the adhesion to the workpiece surface is good, and the protection performance of the workpiece is good.
The adhesive strength of the adhesive tape is measured when the adhesive layer surface of the adhesive tape is affixed to a silicon mirror wafer and peeled at a peeling angle of 180 ° and a peeling speed of 300 mm / min in an environment of 23 ° C. Specifically, it is measured by the method described in the examples described later.
The adhesive force can be adjusted by changing the type of the urethane-based resin (A) or the energy beam curable compound (B). In addition, the adhesive strength after irradiation with energy rays can be adjusted by the amount of photopolymerizable unsaturated bonds described later, and decreases when the amount of photopolymerizable unsaturated bonds contained in the adhesive composition is increased. When it is less, it tends to be higher. Furthermore, it becomes easy to make the adhesive force after energy ray irradiation low also by mix | blending the crosslinking agent (C1) and compound (D) containing a photopolymerizable unsaturated bond so that it may mention later.

(Urethane resin (A))
The urethane resin (A) is a polymer containing at least one of a urethane bond and a urea bond. The pressure-sensitive adhesive layer of the present invention is composed of a urethane-based pressure-sensitive adhesive composition (hereinafter also simply referred to as “pressure-sensitive adhesive composition”) containing at least a urethane polymer (A ′) and an energy ray-curable compound (B). The urethane-based resin (A) is formed from at least a urethane polymer (A ′) as a main agent. Moreover, a crosslinking agent (C), a compound (D), etc. are further contained in a urethane type adhesive composition as needed.

The urethane resin (A) may be crosslinked with a crosslinking agent (C). Further, as described above, the urethane-based pressure-sensitive adhesive composition is bonded directly or indirectly to the urethane polymer (A ′), such as the compound (D), in addition to the crosslinking agent (C). The layer may contain a compound constituting the urethane resin (A) as a unit.
In addition, like a crosslinking agent (C) and a compound (D), it couple | bonds directly or indirectly with a urethane polymer (A '), and a urethane type resin (A') is united with a urethane-type resin (A ') integrally with an adhesive layer. The compounds constituting A) are collectively referred to as “main agent reactive compounds”.
In the present invention, the blending amount of the urethane polymer (A ′) is the total amount of the pressure-sensitive adhesive composition in order to blend components (B) to (E) described later in appropriate amounts while ensuring the tackiness of the pressure-sensitive adhesive layer. Is preferably 30 to 85% by mass, more preferably 35 to 80% by mass, and still more preferably 37 to 77% by mass. The total amount of the main component reactive compound and the urethane polymer (A ′) is preferably 40 to 95% by mass, more preferably 45 to 94% by mass, and further preferably 50 to 50% by mass with respect to the total amount of the pressure-sensitive adhesive composition. 93% by mass.

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) are light in the pressure-sensitive adhesive layer of the work processing pressure-sensitive adhesive tape. It will have a polymerizable unsaturated bond. Therefore, by irradiating the adhesive layer with energy rays, a bond is formed between the urethane resin (A) and the energy ray curable compound (B) by the polymerization reaction, and adhesion of the adhesive tape after energy ray irradiation is achieved. It becomes easier to reduce the force, and the peelability when peeling the adhesive tape from the work becomes good. Furthermore, it is possible to further reduce the adhesive residue generated when the adhesive tape is peeled from the workpiece. Moreover, compared with the case where the curing of the pressure-sensitive adhesive layer by the energy beam irradiation is caused only by the energy beam curable compound (B), the strength of the pressure-sensitive adhesive layer after the energy beam irradiation tends to increase, and the adhesive residue It is easier to suppress the occurrence.

The method for introducing a photopolymerizable unsaturated bond into the urethane resin (A) is not particularly limited. For example, when the urethane polymer (A ′) before introduction of the photopolymerizable unsaturated bond has a hydroxyl group, a functional group capable of reacting with the hydroxyl group and a function containing a photopolymerizable unsaturated bond such as a (meth) acryloyl group. It is possible to introduce a photopolymerizable unsaturated bond by reacting a compound having a group with the hydroxyl group. 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. Such a compound may be reacted in advance with the urethane polymer (A ′), or may be contained in the pressure-sensitive adhesive layer and reacted with the urethane polymer (A ′) at the time of forming the pressure-sensitive adhesive layer. .
Further, as will be described later, the urethane resin (A) is crosslinked with the urethane polymer (A ′) by using the crosslinking agent (C1) having a photopolymerizable unsaturated bond as the crosslinking agent (C). A polymerizable unsaturated bond may be introduced. Furthermore, you may introduce | transduce a photopolymerizable unsaturated bond into a urethane type resin (A) with the compound (D) mentioned later.

<Urethane polymer (A ')>
Examples of the urethane polymer (A ′) include those containing at least one of a urethane bond and a urea bond, and specific examples include a polyurethane polyol having a hydroxyl group at the terminal obtained by reacting a polyol and a polyisocyanate compound. . Further, the urethane polymer (A ′) may be obtained by reacting a polyol and a polyisocyanate compound, and a urethane polymer having a terminal isocyanate may be used.

Examples of the polyol used in the urethane polymer (A ′) include polyester polyols and polyether polyols.
A known polyester polyol is used as the polyester polyol. Polyester polyol is an ester of an acid component and at least one of a glycol component and a polyol component. Examples of the acid component include terephthalic acid, adipic acid, azelaic acid, sebacic acid, phthalic anhydride, isophthalic acid, trimellitic acid, and the like. Can be mentioned. Further, as glycol components, ethylene glycol, propylene glycol, diethylene glycol, butylene glycol, 1,6-hexane glycol, 3-methyl-1,5-pentanediol, 3,3′-dimethylol heptane, polyoxyethylene glycol, polyoxy Examples include propylene glycol, 1,4-butanediol, neopentyl glycol, and butylethylpentanediol. Examples of the polyol component include glycerin, trimethylolpropane, and pentaerythritol.
In addition, polyester polyols obtained by ring-opening polymerization of lactones such as polycaprolactone, poly (β-methyl-γ-valerolactone), and polyvalerolactone may be used.

In addition, a known polyether polyol is used as the polyether polyol. For example, polyether polyols obtained by polymerizing oxirane compounds such as ethylene oxide, propylene oxide, butylene oxide, tetrahydrofuran using low molecular weight polyols such as water, propylene glycol, ethylene glycol, glycerin and trimethylolpropane as initiators Specifically, those having 2 or more functional groups such as polypropylene glycol, polyethylene glycol, and polytetramethylene glycol are used.

Examples of the polyisocyanate compound include known aromatic polyisocyanates, aliphatic polyisocyanates, araliphatic polyisocyanates, and alicyclic polyisocyanates. Aromatic polyisocyanates include 1,3-phenylene diisocyanate, 4,4'-diphenyl diisocyanate, 1,4-phenylene diisocyanate, 4,4'-diphenylmethane diisocyanate, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate Isocyanate, 4,4'-toluidine diisocyanate, 2,4,6-triisocyanate toluene, 1,3,5-triisocyanate benzene, dianisidine diisocyanate, 4,4'-diphenyl ether diisocyanate, 4,4 ', 4 "- And triphenylmethane triisocyanate.

Aliphatic polyisocyanates include 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.

Examples of the araliphatic polyisocyanate include ω, ω′-diisocyanate-1,3-dimethylbenzene, ω, ω′-diisocyanate-1,4-dimethylbenzene, ω, ω′-diisocyanate-1,4-diethylbenzene, 1, Examples thereof include 4-tetramethylxylylene diisocyanate and 1,3-tetramethylxylylene diisocyanate.

The alicyclic polyisocyanates include 3-isocyanate methyl-3,5,5-trimethylcyclohexyl isocyanate, 1,3-cyclopentane diisocyanate, 1,3-cyclohexane diisocyanate, 1,4-cyclohexane diisocyanate, methyl-2,4- And cyclohexane diisocyanate, methyl-2,6-cyclohexane diisocyanate, 4,4′-methylenebis (cyclohexyl isocyanate), 1,4-bis (isocyanate methyl) cyclohexane, 1,4-bis (isocyanate methyl) cyclohexane, and the like. .
The polyisocyanate compound can be used in combination with a trimethylolpropane adduct of the polyisocyanate compound, a burette reacted with water, a trimer having an isocyanurate ring, or the like.
As the polyisocyanate compound, 4,4′-diphenylmethane diisocyanate, hexamethylene diisocyanate, 3-isocyanate methyl-3,5,5-trimethylcyclohexyl isocyanate (isophorone diisocyanate) and the like are preferable.

The polyurethane polyol may be obtained by further reacting a diamine such as ethylenediamine, N-aminoethylethanolamine, isophoronediamine, xylylenediamine in addition to the polyol and the polyfunctional isocyanate. Further, as the polyol, in addition to the above-described polyester polyol and polyether polyol, ethylene glycol, 1,4-butanediol, neopentyl glycol, butylethylpentanediol, glycerin, trimethylolpropane, pentaerythritol and the like are used. Also good.
In addition, reaction with a polyol and a polyisocyanate compound is normally performed in presence of catalysts, such as a tertiary amine type compound and an organometallic compound.

The urethane polymer (A ′) is not limited to those described above, and may be, for example, a Michael addition type urethane polymer.
Examples of the Michael addition type urethane polymer include the following (1) and (2).
(1) A urethane prepolymer having an isocyanate group (—NCO) at the terminal obtained by reacting the polyol with a polyisocyanate compound is reacted with an amino compound obtained by Michael addition reaction of a polyamine and an unsaturated compound. What
(2) A product obtained by reacting a polyamine in addition to the above polyol and polyisocyanate compound, and reacting a polyurethane urea having a primary or secondary amino group at the terminal with a Michael addition reaction of an unsaturated compound.

As the polyamine used in the Michael addition type urethane polymer, known ones can be used. Specifically, ethylenediamine, propylenediamine, trimethylenediamine, tetramethylenediamine, pentamethylenediamine, hexamethylenediamine, Aliphatic polyamines such as ethylenetetramine, diethylenetriamine, triaminopropane, 2,2,4-trimethylhexamethylenediamine, tolylenediamine, hydrazine, piperazine, isophoronediamine, dicyclohexylmethane-4,4'-diamine, etc. Examples include polyamines and aromatic polyamines such as phenylenediamine and xylylenediamine. Further, 2-hydroxyethylethylenediamine, N- (2-hydroxyethyl) propylenediamine, (2-hydroxyethylpropylene) diamine, (di-2-hydroxyethylethylene) diamine, (di-2-hydroxyethylpropylene) diamine , (2-hydroxypropylethylene) diamine, (di-2-hydroxypropylethylene) diamine and other diamines having a hydroxyl group in the molecule, dimer amine obtained by converting the carboxyl group of dimer acid to an amino group, and propoxyamine at both ends And polyoxyalkylene glycol diamine represented by the following general formula (2) can also be used.
H ₂ —NCH ₂ —CH ₂ —CH ₂ —O (C _n H _2n —O) _m —CH ₂ —CH ₂ —CH ₂ —NH ₂ (2)
(In formula (2), n represents an arbitrary integer of 2 to 4, and m represents an arbitrary integer of 2 to 50.)
Furthermore, a dendrimer having a primary or secondary amino group at the terminal can also be used as a polyamine.
Among the polyamines described above, isophorone diamine, 2,2,4-trimethylhexamethylene diamine, and hexamethylene diamine are preferable from the viewpoint of easy control of the reaction.

Further, the unsaturated compound used in the Michael addition type urethane polymer is used for the purpose of modifying the urethane polymer. Therefore, the type of unsaturated compound to be used can be arbitrarily selected according to the purpose of modification. Examples of unsaturated compounds include (meth) acrylic unsaturated compounds, amide unsaturated compounds, fatty acid vinyl unsaturated compounds, vinyl ether unsaturated compounds, α-olefin unsaturated compounds, allyl unsaturated compounds, acetic acid Examples include allylic unsaturated compounds, vinyl cyanide unsaturated compounds, styrene or vinylbenzene unsaturated compounds.
Although the kind of unsaturated compound to be used can be arbitrarily selected according to the purpose of modification, it is preferable to select it by paying attention to the functional group of the unsaturated compound. The functional groups possessed by such unsaturated compounds include alkyl groups, polyalkylene glycol groups, alkoxy groups, phenoxy groups, hydroxyl groups, carboxyl groups, perfluoroalkyl groups, alkoxysilyl groups, epoxy groups, as well as amide groups and dialkyls. Nitrogen-containing groups such as amino groups and quaternary ammonium bases can be exemplified, but it is preferable to have a hydroxyl group so that the urethane polymer (A ′) contains a hydroxyl group as described above.
As specific examples of the unsaturated compound, those described in, for example, JP-A No. 2002-121256 (European Publication No. EP1146061A1) are used.

The urethane polymer (A ′) used in the present invention preferably has a weight average molecular weight of 10,000 to 300,000, more preferably 30,000 to 150,000. By being 10,000 or more, the cohesive force of an adhesive layer improves and the effect which suppresses a higher adhesive residue is acquired. Further, by setting the viscosity to 300,000 or less, viscosity increase that affects process suitability even if diluted with a solvent or melted by heating when forming a pressure-sensitive adhesive layer from the pressure-sensitive adhesive composition is caused. There is an advantage that it is difficult.

(Energy ray curable compound (B))
The energy ray-curable compound (B) used in the present invention is non-reactive with the urethane resin (A) and has a photopolymerizable unsaturated bond.
Here, non-reactive means that it contains not only the “photopolymerizable unsaturated bond” but also contains not only the urethane polymer (A ′) but also a functional group that reacts with the main compound reactive compound, and the compound (B) Is a compound which has not reacted with the urethane resin (A) in the pressure-sensitive adhesive layer.
That is, the energy ray curable compound (B) is obtained by reacting the urethane polymer (A ′), the crosslinking agent (C), and other components (for example, the component (D)) used as necessary. It is a compound that does not react with the components (A ′), (C), and (D) when the pressure-sensitive adhesive layer is formed.

Thus, energy-beam curable compound (B) will exist as a component which does not comprise urethane type resin (A) in an adhesive layer. Urethane polymers generally have a high cohesive force and a high storage elastic modulus, so it is difficult to embed protrusions such as bumps on the surface of the work alone, but in the present invention, the energy ray curable compound (B) does not constitute a urethane polymer chain. By blending, the storage elastic modulus of the pressure-sensitive adhesive layer is lowered, and it becomes easy to ensure the embedding property to the bump.
In the present invention, the photopolymerizable unsaturated bond means an unsaturated bond that reacts upon irradiation with energy rays, and is usually an ethylenic double bond, preferably a carbon-carbon contained in a (meth) acryloyl group. It is a double bond.

The molecular weight of the energy ray curable compound (B) is 35,000 or less. When the molecular weight is larger than 35,000, it becomes difficult to lower the storage elastic modulus of the pressure-sensitive adhesive layer, and it becomes difficult to ensure the embedding property to the bump. Moreover, there exists a possibility that compatibility with a urethane type resin (A) may deteriorate. The molecular weight of the energy ray curable compound (B) is preferably 150 to 35,000, and more preferably 200 to 34,000. The molecular weight is the formula weight when the formula weight can be specified, and the weight average molecular weight when the formula weight cannot be specified.
The compounding amount of the energy ray curable compound (B) varies depending on the compound used, but 100 parts by mass of the urethane resin (A) (that is, 100 parts by mass of the urethane polymer (A ′) and the main component reactive compound). In the following, the same is true): usually 1 to 120 parts by mass, preferably 2 to 100 parts by mass, more preferably 4 to 90 parts by mass. By setting the blending amount of the energy ray curable compound (B) in such a range, it is easy to obtain a pressure-sensitive adhesive layer that is compatible with the workpiece surface and suppresses adhesive residue.

Specific examples of the energy ray curable compound (B) include compounds having a (meth) acryloyl group. The (meth) acryloyl group (photopolymerizable unsaturated bond) in one molecule of the energy ray curable compound (B) may be one or more functional groups, preferably two functional groups or more, and 2 to 12 functional groups. Is more preferable.
Moreover, at least 1 sort (s) selected from the (meth) acrylate monomer (B1) and urethane (meth) acrylate (B2) as a specific example of the energy-beam curable compound (B) used by this invention is mentioned. .

The (meth) acrylate monomer (B1) is a compound having a (meth) acryloyl group in the molecule, and the number of the (meth) acryloyl group is preferably bifunctional or more, more preferably 3 to 6. In particular, when the urethane-based resin (A) does not have a photopolymerizable unsaturated bond, a (meth) acryloyl group is used so that the adhesive strength of the adhesive tape can be easily reduced after energy ray irradiation to the adhesive layer. It is preferable that the pressure-sensitive adhesive layer contains a (meth) acrylate monomer (B1) having a number of 4 or more.
Examples of the (meth) acrylate monomer (B1) include polyfunctional (meth) acrylic acid esters in which all the hydroxyl groups of the polyhydric alcohol are complete esters formed with (meth) acrylic acid and esters. Here, the carbon number of the polyhydric alcohol is preferably 4 to 10. The (meth) acrylate monomer (B1) preferably has a molecular weight of 150 to 1000, more preferably 200 to 800.
Specific compounds of the polyfunctional (meth) acrylic acid ester include trimethylolpropane tri (meth) acrylate, pentaerythritol tetra (meth) acrylate, dipentaerythritol hexa (meth) acrylate, 1,4-butylene glycol di ( Examples include meth) acrylate and 1,6-hexanediol di (meth) acrylate. Among these, pentaerythritol tetra (meth) acrylate is preferable.
The structure of the (meth) acrylate monomer (B1) can be specified, and the molecular weight means a formula weight.

The (meth) acrylate monomer (B1) is preferable because even with a small blending amount, adhesive residue can be prevented and the adhesive force can be appropriately reduced by energy ray curing.
Further, the blending amount of the (meth) acrylate monomer (B1) is specifically preferably 1 to 20 parts by weight, more preferably 2 to 15 parts by weight with respect to 100 parts by weight of the urethane resin (A). More preferably, it is 3 to 10 parts by mass. The energy ray-curable compound (B) can appropriately prevent adhesive residue from the pressure-sensitive adhesive layer and reduce the pressure-sensitive adhesive force of the pressure-sensitive adhesive layer appropriately by irradiation with energy rays by setting the blending amount as described above. Is possible.

Urethane (meth) acrylate (B2) is a polymer having a urethane bond and having a (meth) acryloyl group at the terminal. The urethane (meth) acrylate (B2) is obtained by reacting a polyol compound with a polyisocyanate compound to produce a terminal isocyanate urethane polymer and reacting a compound having a (meth) acryloyl group with the terminal functional group. Compound etc. are mentioned. Such urethane (meth) acrylate (B2) has energy ray curability by the action of the (meth) acryloyl group.
The polyol compound, polyisocyanate compound, and compound having a (meth) acryloyl group used to obtain the urethane (meth) acrylate (B2) are added to the urethane (meth) acrylate (X) of the intermediate layer described above. The polyol compound, the polyisocyanate compound, and the compound having a (meth) acryloyl group that are used are appropriately selected and used, and a specific description thereof is omitted.

The urethane (meth) acrylate (B2) has a (meth) acryloyl group, and the (meth) acryloyl group in one molecule is preferably bifunctional or more, more preferably 2 to 12, and even more preferably. 2 to 10 functional. Thus, it becomes easy to reduce adhesive force by energy ray hardening by setting it as polyfunctionality.
The molecular weight of the urethane (meth) acrylate (B2) is 35000 or less, preferably 2000 to 35000, more preferably 5000 to 34000. In addition, the molecular weight of urethane (meth) acrylate (B2) means a weight average molecular weight. By setting the molecular weight of the urethane (meth) acrylate in such a range, the storage elastic modulus of the pressure-sensitive adhesive layer is lowered, and it becomes easy to ensure followability to the unevenness of the workpiece surface. Moreover, the movement of the urethane (meth) acrylate (B2) in the pressure-sensitive adhesive layer is suppressed, and the stability over time of the pressure-sensitive adhesive tape is improved.

When the energy ray curable compound (B) is urethane (meth) acrylate (B2), the blending amount of the urethane (meth) acrylate (B2) is 30 to 120 with respect to 100 parts by mass of the urethane resin (A). Mass parts are preferred, 40 to 100 parts by mass are preferred, and 50 to 90 parts by mass are more preferred. By setting the blending amount of the urethane (meth) acrylate (B2), the pressure-sensitive adhesive performance of the pressure-sensitive adhesive layer is favorably maintained and the embedding property is easily secured. Moreover, it becomes easy to reduce adhesive force sufficiently by energy beam hardening, and also to reduce adhesive residue.

(Crosslinking agent (C))
The pressure-sensitive adhesive composition of the present invention preferably further contains a crosslinking agent (C). The crosslinking agent (C) reacts with the urethane polymer (A ′) to crosslink the urethane polymer (A ′). By containing the crosslinking agent (C), the pressure-sensitive adhesive composition has a high crosslink density and can easily form a pressure-sensitive adhesive layer having high mechanical strength. Moreover, it becomes easy to prevent the adhesive residue etc. at the time of peeling an adhesive tape.
When the urethane polymer (A ′) has a hydroxyl group, the crosslinking agent (C) is preferably a crosslinking agent having two or more isocyanate groups so that it can react with the hydroxyl group. When the pressure-sensitive adhesive composition contains a crosslinking agent, it is usually crosslinked by being applied and then heated.

Conversely, the urethane polymer (A ′) may have an isocyanate group and the crosslinking agent (C) may have a hydroxyl group. Since the urethane polymer (A ′) generally has a hydroxyl group or an isocyanate group because of its production method, the urethane polymer (A ′) and the crosslinking agent (C) are thus bonded by a urethane bond. Bonding is preferred.

As the crosslinking agent (C) usable in the present invention, it is preferable to use a crosslinking agent (C1) containing a photopolymerizable unsaturated bond.
The crosslinking agent (C1) containing a photopolymerizable unsaturated bond is preferably a compound having two or more isocyanate groups and a (meth) acryloyl group, and more preferably a urethane having at least two isocyanate groups. (Meth) acrylate is used.
The urethane (meth) acrylate has a weight average molecular weight of preferably 500 to 2,000, more preferably 700 to 1,000. When one molecule of the crosslinking agent (C1) has two or more photopolymerizable unsaturated bonds, the photopolymerizable unsaturated bonds in the same molecule of the crosslinking agent (C1) are polymerized. It tends to be easy. Therefore, the reaction between the photopolymerizable unsaturated bond of the cross-linking agent (C1) and the photopolymerizable unsaturated bond of other molecules is unlikely to occur, and the adhesive force of the adhesive tape is reduced by the energy ray irradiation to the adhesive layer. May be less effective. Therefore, what has a preferable photopolymerizable unsaturated bond in 1 molecule as a crosslinking agent (C1) is preferable. Examples of the urethane (meth) acrylate used as the cross-linking agent (C1) include “EBECRYL 4150” manufactured by Daicel Ornex.
In this embodiment, by using the crosslinking agent (C1) having a photopolymerizable unsaturated bond, the urethane resin (A) has a photopolymerizable unsaturated bond in the pressure-sensitive adhesive layer.

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 the side chain. In this case, the urethane resin (A) crosslinked with the crosslinking agent (C1) is a so-called acrylic urethane resin, but the urethane resin (A) of the present invention includes such an acrylic urethane resin. Shall.

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 with respect to 100 parts by mass of the urethane resin (A). More preferred is ~ 45 parts by mass. By setting the crosslinking agent (C1) to such a blending amount, it is possible to introduce an appropriate amount of a photopolymerizable unsaturated bond into the urethane resin (A) while improving the crosslinking density of the pressure-sensitive adhesive layer. Is possible.

The pressure-sensitive adhesive composition may contain a crosslinking agent (C2) that does not contain a photopolymerizable unsaturated bond as the crosslinking agent (C). As the crosslinking agent (C2), when the urethane polymer (A ′) has a hydroxyl group, it can be appropriately selected from the polyisocyanate compounds used for synthesizing the urethane polymer (A ′) listed above. It is. When the polymer (A ′) before crosslinking has an isocyanate group, a known polyol can be used as the crosslinking agent (C2). The pressure-sensitive adhesive composition can sufficiently increase the cross-linking density of the pressure-sensitive adhesive layer by containing the cross-linking agent (C2).

All of the crosslinking agents (C) may be crosslinking agents (C1) having a photopolymerizable unsaturated bond, or all may be crosslinking agents (C2) having no photopolymerizable unsaturated bond. However, it is preferable to contain the crosslinking agent (C1) which has a photopolymerizable unsaturated bond, and it is more preferable to contain both a crosslinking agent (C1) and a crosslinking agent (C2).

The blending amount of the crosslinking agent (C2) containing no photopolymerizable unsaturated bond is preferably 0.2 to 15 parts by mass, and 0.5 to 10 parts by mass with respect to 100 parts by mass of the urethane resin (A). More preferred. Further, as described above, when used in combination with the crosslinking agent (C1), the blending amount of the crosslinking agent (C2) containing no photopolymerizable unsaturated bond may be relatively small, and the urethane resin (A ) It is preferably 0.2 to 5 parts by mass, more preferably 0.5 to 2 parts by mass with respect to 100 parts by mass.

(Compound (D))
When the pressure-sensitive adhesive composition contains a crosslinking agent (C), the pressure-sensitive adhesive composition may further contain a compound (D) having a photopolymerizable unsaturated bond and a reactive functional group capable of reacting with the crosslinking agent (C). preferable. 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 pressure-sensitive adhesive composition contains the compound (D), a photopolymerizable unsaturated bond is introduced into the urethane resin (A) by the compound (D). Therefore, when the pressure-sensitive adhesive layer is cured with energy rays, the pressure-sensitive adhesive force of the pressure-sensitive adhesive layer is easily reduced, and adhesive residue and the like are further easily prevented. In addition, there is also an effect that the performance of the adhesive tape is easily stabilized over time.

Examples of the reactive functional group contained in the compound (D) include an isocyanate group and a hydroxyl group. Moreover, as a compound (D), the (meth) acrylate monomer which has a hydroxyl group and a (meth) acryloyl group is mentioned. The number of (meth) acryloyl groups (that is, photopolymerizable unsaturated bonds) in one molecule of compound (D) is preferably 2 or more, more preferably 2 to 5 in one molecule. .
The (meth) acrylate monomer used as component (D) preferably has a molecular weight of 150 to 3,000, more preferably 200 to 2,000.
Examples of the (meth) acrylate monomer used as the component (D) include polyhydric alcohols and polyfunctional (meth) acrylic acid esters that are partial esters of (meth) acrylic acid. Here, the carbon number of the polyhydric alcohol is preferably 4 to 10. Specific examples of the compound include pentaerythritol tri (meth) acrylate, dipentaerythritol tetra (meth) acrylate, and dipentaerythritol penta (meth) acrylate. Among these, pentaerythritol tri (meth) acrylate is exemplified. Is preferred.

The compounding amount of the compound (D) is preferably 1 to 30 parts by mass, more preferably 2 to 20 parts by mass, and further preferably 3 to 15 parts by mass with respect to 100 parts by mass of the urethane resin (A). . By mix | blending a compound (D) in such a range, without having a bad influence on the adhesive performance of an adhesive layer, it becomes easy to reduce adhesive force by hardening of an energy ray, and it becomes easy to prevent adhesive residue. Moreover, it is preferable that a compound (D) is normally used when an energy-beam curable compound (B) contains a (meth) acrylate monomer (B1). Thus, when the compound (D) and the (meth) acrylate monomer (B1) are used in combination, the effects of the present invention are more easily exhibited.

(Energy beam polymerization initiator (E))
The pressure-sensitive adhesive composition preferably further contains an energy ray polymerization initiator (E). The pressure-sensitive adhesive layer can be easily cured by irradiation with energy rays by containing the energy ray polymerization initiator (E). The energy ray polymerization initiator (E) can be appropriately selected from photopolymerization initiators that can be used in the resin compositions for intermediate layers listed above.
The compounding amount of the energy ray polymerization initiator (E) is a urethane polymer (A ′) having a photopolymerizable unsaturated bond, a crosslinking agent (C1), an energy ray curable compound (B), and a compound (D). The total amount of the compounds having a photopolymerizable unsaturated bond such as 100 parts by mass is preferably 0.05 to 25 parts by mass, more preferably 0.1 to 20 parts by mass, still more preferably 0.3 to 15 parts by mass. Part.

The pressure-sensitive adhesive composition may contain other additives conventionally used for urethane-based pressure-sensitive adhesives, such as fillers such as calcium carbonate and titanium oxide, colorants, antioxidants, antifoaming agents, It may contain a light stabilizer or the like.
The thickness of the pressure-sensitive adhesive layer can be appropriately adjusted according to the surface state of the adherend surface to which the pressure-sensitive adhesive tape is applied, such as the bump height on the wafer surface, but is preferably 2 to 150 μm, more preferably 5 to The thickness is 100 μm, more preferably 8 to 50 μm.

<Release material>
The release material provided on the pressure-sensitive adhesive layer and the release material used in the process of the production method described below are a release sheet that has been subjected to a single-sided release process, a release sheet that has been subjected to a double-sided release process, etc. The thing etc. which apply | coated the release agent on the base material of this are mentioned.
Examples of the release material substrate include polyester film such as polyethylene terephthalate resin, polybutylene terephthalate resin, polyethylene naphthalate resin, and plastic film such as polyolefin resin film such as polypropylene resin and polyethylene resin.
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 resins.
The thickness of the release material is not particularly limited, but is preferably 5 to 200 μm, more preferably 10 to 120 μm.

[Production method of adhesive tape]
The production method of the pressure-sensitive adhesive tape of the present invention is not particularly limited, and can be produced by a known method.
The intermediate layer may be formed, for example, by directly applying a solution of the resin composition for the intermediate layer on one surface of the substrate to form a coating film, and then drying and curing treatment as necessary. it can. In addition, the intermediate layer is formed on the release material by applying a solution of the resin composition for the intermediate layer to the release treatment surface of the release material to form a coating film, and then drying and semi-curing as necessary. A semi-cured layer may be formed, this semi-cured layer may be bonded to a substrate, and the semi-cured layer may be completely cured. At this time, the release material may be appropriately removed before or after the semi-cured layer is completely cured. The intermediate layer is preferably cured by polymerizing by irradiating the coating film with energy rays. The energy ray is preferably ultraviolet light. Moreover, when forming an intermediate | middle layer using an olefin type material, you may form an intermediate | middle layer by extrusion molding etc.

The pressure-sensitive adhesive layer is preferably formed by applying the pressure-sensitive adhesive composition, heating and cross-linking the pressure-sensitive adhesive composition, and drying as necessary. At this time, the pressure-sensitive adhesive composition may be applied directly to the intermediate layer or the base material, or may be applied to the release treatment surface of the release material to form a pressure-sensitive adhesive layer, and then the intermediate layer or the base material. You may form by sticking an adhesive layer together. The release material disposed on the pressure-sensitive adhesive layer may be peeled off as necessary.

When forming the intermediate layer or 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, so that the intermediate layer resin composition or the pressure-sensitive adhesive composition may be diluted. Good. Examples of the organic solvent to be used include methyl ethyl ketone, acetone, ethyl acetate, tetrahydrofuran, dioxane, cyclohexane, n-hexane, toluene, xylene, n-propanol, isopropanol and the like.
In addition, as these organic solvents, the organic solvent used at the time of the synthesis | combination of each component contained in the resin composition for intermediate | middle layers or an adhesive composition may be used as it is, and 1 or more types of other organic solvents other than that may be used. May be added.
The intermediate layer resin composition or the pressure-sensitive adhesive composition can be applied by a known application method. Examples of the coating method include spin coating, spray coating, bar coating, knife coating, roll coating, blade coating, die coating, and gravure coating.

[How to use adhesive tape]
The pressure-sensitive adhesive tape of the present invention is used when affixing to various workpieces and processing the workpiece, and is preferably affixed to a workpiece surface having irregularities and protrusions.
Moreover, it is more preferable to affix to the semiconductor wafer surface, especially the wafer surface in which the bump was formed, and to use as a semiconductor wafer surface protection adhesive tape. Further, the adhesive tape is more preferably used as a bag grind tape that is attached to the surface of a semiconductor wafer and protects a circuit formed on the wafer surface during subsequent grinding of the wafer back surface. When the pressure-sensitive adhesive tape of the present invention has an intermediate layer, the embedding property is good even if there is a height difference due to bumps or the like on the wafer surface, so that the protection performance of the wafer surface is good. In this case, the temperature of the adhesive tape when the adhesive tape is applied to the surface of the semiconductor wafer is, for example, about 40 to 80 ° C., and preferably 50 to 70 ° C.

In the present invention, the pressure-sensitive adhesive layer is energy-ray curable, and the pressure-sensitive adhesive tape attached to the work surface of a semiconductor wafer or the like is peeled off from the work surface after being irradiated with energy rays and cured with energy rays. is there. Therefore, since the adhesive tape is peeled after the adhesive force is lowered, the peelability is improved. Further, as described above, the adhesive tape after curing is less likely to have adhesive residue when peeled off.
The adhesive tape is not limited to a back grind sheet when used for a semiconductor wafer, and can be used for other purposes. For example, the adhesive tape may be attached to the back surface of the wafer and used as a dicing sheet that holds the wafer when the wafer is diced. In this case, the wafer may be a wafer in which protrusions such as bumps or irregularities are formed on the back surface of the wafer, such as a wafer in which through electrodes are formed.

Hereinafter, the present invention will be described in more detail based on 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)]
Using a gel permeation chromatograph (product name “HLC-8220”, manufactured by Tosoh Corporation), measurement was performed under the following conditions, and values measured in terms of standard polystyrene were used.
(Measurement condition)
Column: “TSK guard column HXL-H” “TSK gel GMHXL (× 2)” “TSK gel G2000HXL” (both manufactured by Tosoh Corporation)
Column temperature: 40 ° C. Developing solvent: Tetrahydrofuran Flow rate: 1.0 mL / min

[Loss tangent (tan δ)]
The resin composition for the intermediate layer used in each Example and Comparative Example was applied by applying to a polyethylene terephthalate film release film (manufactured by Lintec Corporation, product name “SP-PET 381031”, thickness 38 μm) by a fountain die method. A film was formed. And the ultraviolet-ray was irradiated from the coating-film side, and the semi-hardened layer was formed.
For ultraviolet irradiation, a belt conveyor type ultraviolet irradiation device (product name “ECS-4011GX”) is used as an ultraviolet irradiation device, and a high-pressure mercury lamp (product name “Igraphics”, product name “ H04-L41 "), and the irradiation conditions are as follows: illuminance of 112 mW / cm ^{2 with} a light wavelength of 365 nm, light amount of 177 mJ / cm ² (measured with an ultraviolet light meter“ UVPF-A1 ”manufactured by I-Graphics) went.
On the formed semi-cured layer, a polyethylene terephthalate film-based release film (product name “SP-PET 381031”, thickness 38 μm, manufactured by Lintec Co., Ltd.) is laminated, and further irradiated with ultraviolet rays (using the above-described ultraviolet irradiation device and ultraviolet source). As an irradiation condition, an illuminance of 271 mW / cm ² and a light amount of 1,200 mJ / cm ² ) were performed and cured completely to form an intermediate layer having a thickness of 200 μm with a release film attached to both sides.
Five intermediate layers formed in this way were prepared, and an intermediate layer laminate (thickness: 1,000 μm) was prepared by peeling the PET-based release film and aligning the release surfaces and sequentially laminating them.
Next, the obtained intermediate layer laminate was punched into a circle with a diameter of 10 mm to obtain a sample for measuring viscoelasticity. Using a viscoelasticity measuring device (manufactured by TA Instruments Inc., product name “ARES”), the above sample was strained at a frequency of 1 Hz and stored at −50 to 150 ° C. at a heating rate of 4 ° C./min. The elastic modulus (G ′) was measured, and the loss tangent (tan δ) at 50 ° C. was obtained.

[Breaking stress]
A pressure-sensitive adhesive layer (thickness: 200 μm) having a polyethylene terephthalate release film (product name: “SP-PET381031” manufactured by Lintec Corporation) attached to both surfaces was prepared. Here, in the same manner as in Examples and Comparative Examples, the pressure-sensitive adhesive layer was formed on one release film by changing the thickness to 40 μm, and then the other release film was attached to the pressure-sensitive adhesive layer. Five pressure-sensitive adhesive layers sandwiched between such release films were prepared, and the surfaces of the pressure-sensitive adhesive layers exposed by peeling one release film were opposed to each other and laminated. By repeating this procedure, a pressure-sensitive adhesive layer having a thickness of 200 μm in which five pressure-sensitive adhesive layers were laminated was obtained. The laminate of the pressure-sensitive adhesive layer sandwiched between two release films was irradiated with ultraviolet rays at an illuminance of 220 mW / cm and an irradiation speed of 15 mm / sec using a UV irradiation apparatus “RAD-2000 m / 12” manufactured by Lintec Corporation. Then, the hardened | cured material of the adhesive layer was cut out to 15 mm x 150 mm. Next, labels for film tension were affixed to the 25 mm portions at both ends, and a strip-shaped sample having a measurement target portion of 15 mm × 100 mm was produced. The rupture stress was measured with “Autograph AG-IS500N” manufactured by Shimadzu Corporation at a tensile speed of 200 mm / min.

[Adhesive strength before energy beam irradiation]
The pressure-sensitive adhesive tapes of Examples and Comparative Examples are evenly cut to a width of 25 mm, and the pressure-sensitive adhesive tape is temporarily placed on the silicon mirror wafer that is the adherend, and a 1 kg roll is reciprocated once on the adhesive tape. Affixed by applying a load. After sticking, after storing for 1 hour in an environment of 23 ° C. and 50% relative humidity, using a tensile tester (Orientec, product name “Tensilon”) at a peeling angle of 180 ° and a peeling speed of 300 mm / min. The adhesive strength when the adhesive tape was peeled was measured.
[Adhesive strength after energy beam irradiation]
The pressure-sensitive adhesive tapes of Examples and Comparative Examples are evenly cut to a width of 25 mm, and the pressure-sensitive adhesive tape is temporarily placed on the silicon mirror wafer that is the adherend, and a 1 kg roll is reciprocated once on the adhesive tape. Affixed by applying a load. After sticking, it is stored for 1 hour in an environment of 23 ° C and 50% relative humidity, and UV light is applied from the adhesive tape side with an illumination intensity of 220 mW / cm and an irradiation speed of 15 mm / sec using a UV irradiation device “RAD-2000m / 12” manufactured by Lintec Corporation. After being irradiated for 5 minutes in an environment of 23 ° C. and 50% relative humidity, a tensile tester (product name “Tensilon”, manufactured by Orientec Co., Ltd.) was used. The adhesive strength when the adhesive tape was peeled in minutes was measured.

[Embedment evaluation]
Wafer with spherical bumps having a bump height of 250 μm, a pitch of 500 μm, and a diameter of 300 μm in plan view (manufactured by Waltz, 8-inch wafer, bump specification Sn / Ag / Cu = 96.5 / 3 / 0.5 mass%, wafer surface The adhesive tapes produced in Examples and Comparative Examples were attached to the material SiO ₂ ) using a laminator “RAD-3510F / 12” manufactured by Lintec Corporation. In addition, when sticking, the laminating table and laminating roll of the apparatus were set to 60 degreeC. After the lamination, UV light was irradiated from the adhesive tape side at an illumination intensity of 220 mW / cm and an irradiation speed of 15 mm / sec with a UV irradiation apparatus “RAD-2000 m / 12” manufactured by Lintec Corporation. The evaluation wafer with the adhesive tape obtained in this way was measured for the diameter of the circular void generated around the bump from the base material side using a digital microscope (manufactured by Keyence Corporation, product name “VHX-1000”). The embedding property was calculated by the following formula.
Embeddability = void diameter / bump diameter × 100 [%]
The calculated embedding property was evaluated according to the following evaluation criteria, with the best embedding having an appropriate void of 110% or more and less than 130%.
A: Embedding property = 110% or more and less than 130% B: Embedment property = 130% or more and less than 140% C: Embedment property = 110% or less, or 140% or more

[Evaluation of adhesive residue on bumps]
From an evaluation wafer prepared in the same manner as the above-described embedding evaluation test and attached with an adhesive tape, in a tensile tester (Orientec, product name “Tensilon”) in an environment of 23 ° C. and 50% relative humidity. Then, the adhesive tape was peeled off at a pulling speed of 120 mm / min. After peeling, the wafer was observed with an electron microscope “VE-9800” manufactured by Keyence Co., Ltd., and the bump portion of the wafer was observed to confirm the presence or absence of adhesive residue.

[Production of substrate with intermediate layer]
Monofunctional urethane acrylate 40 parts by mass, isobornyl acrylate (IBXA) 45 parts by mass, hydroxypropyl acrylate (HPA) 15 parts by mass, pentaerythritol tetrakis (3-mercaptobutyrate) (Showa Denko Co., Ltd., product name “Karenz MTPE1” , Secondary tetrafunctional thiol-containing compound, solid content concentration 100 parts by mass) 3.5 parts by mass, crosslinking agent 1.8 parts by mass, and 2-hydroxy-2-methyl-1- as a photopolymerization initiator An intermediate layer resin composition was prepared by blending 1.0 part by weight of phenyl-propan-1-one (manufactured by BASF, product name “Darocur 1173”, solid content concentration: 100 parts by weight). This intermediate layer resin composition was coated on a polyethylene terephthalate film-based release film (manufactured by Lintec Corporation, product name “SP-PET 381031”, thickness 38 μm) by a fountain die method to form a coating film.
And the ultraviolet-ray was irradiated from the coating-film side, and the semi-hardened layer was formed. For ultraviolet irradiation, a belt conveyor type ultraviolet irradiation device (product name “ECS-401GGX”) is used as an ultraviolet irradiation device, and a high-pressure mercury lamp (product name “H04” manufactured by Eye Graphics Co., Ltd.) is used as an ultraviolet ray source. -L41 "), and the irradiation conditions were an illuminance of 112 mW / cm ^{2 with} a light wavelength of 365 nm and a light amount of 177 mJ / cm ² (manufactured by IGraphics, product name“ UVPF-A1 ”). .
On the formed semi-cured layer, a base material made of polyethylene terephthalate (PET) film (product name “Cosmo Shine A4100”, thickness 50 μm, manufactured by Toyobo Co., Ltd.) was laminated, and further irradiated with ultraviolet rays from the PET film side (above) Irradiance of 271 mW / cm ² and light intensity of 1200 mJ / cm ² ) is used, and cured completely to form an intermediate layer having a thickness of 300 μm on the base PET film. Thus, a base material with an intermediate layer was obtained.
The loss tangent (tan δ) of the intermediate layer at 50 ° C. measured at a frequency of 1 Hz was 1.92.
In addition, in the following Examples and Comparative Examples, each mass part is shown in terms of solid content when diluted with a diluent.

[Example 1]
As the urethane polymer (A ′), a polyurethane polyol having a urethane skeleton and having a plurality of hydroxyl groups (product name “SH-101” manufactured by Toyochem Co., Ltd., weight average molecular weight: 100,000) is prepared. (A ′) 32 parts by mass of 100 parts by mass of urethane acrylate having a plurality of isocyanate groups as a crosslinking agent (C1) (manufactured by Daicel Ornex, product name “EBECRYL4150”, weight average molecular weight: 1,040) Mixture of pentaerythritol tetraacrylate (formula weight: 352) as the curable compound (B) and pentaerythritol triacrylate (formula weight: 298) as the compound (D) (mass ratio (C: D) = 40: 60) (Product name “A-TMM-3LM-N” manufactured by Shin-Nakamura Chemical Co., Ltd.) 7 parts by mass, 5 parts by mass of 2,2-dimethoxy-1,2-diphenylethane-1-one (manufactured by BASF, product name “Irgacure 651”) as an energy ray polymerization initiator (E), and crosslinking agent (C2) 1 part by weight of a polyisocyanate compound (“T-501B” manufactured by Toyochem Co., Ltd.) was added, stirred for 10 minutes, diluted with toluene to prepare a pressure-sensitive adhesive composition having a solid content concentration of 40% by weight.
Next, the prepared pressure-sensitive adhesive composition was applied to a polyethylene terephthalate release film (manufactured by Lintec Corporation, product name “SP-PET 381031”, thickness 38 μm), heated at 100 ° C. for 2 minutes, dried and then released onto the release film. An adhesive layer having a thickness of 10 μm was formed.
Then, after removing the release film on the base material with the intermediate layer previously prepared, and pasting the adhesive layer on the release film to the exposed intermediate layer, the unnecessary part at the end in the width direction is cut and removed. And the adhesive tape with which the base material, the intermediate | middle layer, the adhesive layer, and the peeling film were provided in this order was obtained. The evaluation results of this adhesive tape are shown in Table 1.

[Example 2]
The procedure was the same as in Example 1 except that the pressure-sensitive adhesive composition was adjusted by changing the urethane polymer (A ′) to Toyochem Co., Ltd., product name “SP-205”, weight average molecular weight: 98,000). An adhesive tape was prepared.

[Example 3]
17 parts by mass of “A-TMM-3LM-N” was added to urethane acrylate as an energy ray curable compound (B) (manufactured by Negami Kogyo Co., Ltd., product name “UN-6200”, bifunctional, weight average molecular weight 6,270). ) A pressure-sensitive adhesive tape was prepared in the same procedure as in Example 1 except that the pressure-sensitive adhesive composition was adjusted by changing to 100 parts by mass.

[Example 4]
A pressure-sensitive adhesive tape was prepared in the same procedure as in Example 3 except that the pressure-sensitive adhesive composition was prepared by changing the urethane polymer (A ′) to the product name “SP-205” manufactured by Toyochem Co., Ltd.

[Example 5]
Example 1 except that 17 parts by mass of “A-TMM-3LM-N” was changed to 100 parts by mass of urethane acrylate (hexafunctional, weight average molecular weight 33,000) as the energy ray-curable compound (B). An adhesive tape was prepared in the same procedure.

[Comparative Example 1]
To an acrylic copolymer obtained by polymerizing 94 parts by mass of 2-ethylhexyl acrylate and 6 parts by mass of 2-hydroxyethyl acrylate, 2-isocyanate ethyl methacrylate (manufactured by Showa Denko KK, product name “Karenz MOI”) is acrylic. A methacryloyl group-added acrylic copolymer (weight average molecular weight: 900,000, solid content: 35 mass%) added so that the addition ratio to the hydroxyl group in the copolymer was 50% on the basis of the number of moles was prepared. To 100 parts by mass of this copolymer, 3 parts by mass of 1-hydroxylcyclohexyl phenyl ketone (manufactured by BASF, product name “Irgacure 184”) as a photopolymerization initiator, and polyisocyanate compound (manufactured by Toyochem Co., Ltd., product name) as a crosslinking agent 0.8 parts by mass of “BHS-8515”) was added and 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-based release film (manufactured by Lintec Corporation, product name “SP-PET 381031”, thickness 38 μm) and dried to form a pressure-sensitive adhesive layer having a thickness of 10 μm. .
After removing the release film on the intermediate layer-prepared substrate previously prepared and pasting the exposed intermediate layer and the adhesive layer on the release film together, the unnecessary part at the end in the width direction is cut and removed. The adhesive tape in which the base material, the intermediate layer, the adhesive layer, and the release film were provided in this order was obtained. The evaluation results of this adhesive tape are shown in Table 1.

[Comparative Example 2]
To an acrylic copolymer obtained by polymerizing 90 parts by mass of 2-ethylhexyl acrylate and 10 parts by mass of 4-hydroxybutyl acrylate, 2-isocyanate ethyl methacrylate (manufactured by Showa Denko KK, product name “Karenz MOI”) was co-polymerized with acrylic. A methacryloyl group-added acrylic copolymer (weight average molecular weight: 1,000,000, solid content: 25% by mass) was obtained by adding such that the addition ratio to the hydroxyl group in the polymer was 65% on a molar basis. . To 100 parts by mass of this copolymer, 3 parts by mass of 1-hydroxylcyclohexyl phenyl ketone (product name “Irgacure 184”) as a photopolymerization initiator and a polyisocyanate compound (product name, manufactured by Toyochem Co., Ltd.) as a crosslinking agent 1.1 parts by weight of “BHS-8515”) was added and stirred for 30 minutes to prepare an acrylic pressure-sensitive adhesive composition. Otherwise, an adhesive tape was prepared in the same procedure as in Comparative Example 1.

[Comparative Example 3]
Acrylic copolymer obtained by polymerizing 90 parts by mass of 2-ethylhexyl acrylate and 10 parts by mass of 4-hydroxybutyl acrylate was acrylic with 2-isocyanatoethyl methacrylate (manufactured by Showa Denko KK, product name “Karenz MOI”). A methacryloyl group-added acrylic copolymer (weight average molecular weight: 1,000,000, solid content: 25% by mass) is obtained by addition so that the addition ratio to the hydroxyl group in the copolymer is 75% on the basis of the number of moles. It was.
To 100 parts by mass of this copolymer, 5 parts by mass of 1-hydroxylcyclohexyl phenyl ketone (manufactured by BASF, product name “Irgacure 184”) as a photopolymerization initiator, and polyisocyanate compound (product name, manufactured by Toyochem Co., Ltd.) 1.2 parts by mass of product name “BHS-8515”) was added and stirred for 30 minutes to prepare an acrylic pressure-sensitive adhesive composition. Otherwise, an adhesive tape was prepared in the same procedure as in Comparative Example 1.

[Comparative Example 4]
An adhesive tape was prepared in the same procedure as in Example 1 except that “A-TMM-3LM-N” was not added.

In Examples 1 to 5 above, the pressure-sensitive adhesive composition is urethane-based, and the urethane-based resin (A) contains the non-reactive energy ray-curable compound (B), so that the embedding property of the bump ( The followability of the pressure-sensitive adhesive layer to the surface shape of the workpiece was improved, and the breaking stress was high, and adhesive residue at the time of peeling could be prevented. Furthermore, since the adhesive force before energy ray curing was increased and the adhesive force after curing was sufficiently low, the peelability and adhesiveness were excellent.
On the other hand, in Comparative Examples 1 to 3, since the pressure-sensitive adhesive composition was acrylic, the rupture stress was low and adhesive residue could not be prevented. Moreover, although it was urethane type in the comparative example 4, since it did not contain an energy-beam curable compound (B), it was inferior to the softness | flexibility of an adhesive layer and embedding property was not enough.

Claims

A base material, and a pressure-sensitive adhesive layer provided on one surface side of the base material,
Energy ray-curable compound in which the pressure-sensitive adhesive layer is non-reactive with the urethane resin (A) and the urethane resin (A), has a photopolymerizable unsaturated bond, and has a molecular weight of 35,000 or less. An adhesive tape for work processing comprising (B).
The pressure-sensitive adhesive tape for workpiece processing according to claim 1, wherein the energy ray-curable compound (B) is at least one selected from a (meth) acrylate monomer (B1) and a urethane (meth) acrylate (B2).
The energy ray curable compound (B) contains at least a (meth) acrylate monomer (B1), and the (meth) acrylate monomer (B1) is a polyhydric alcohol and a complete ester of (meth) acrylic acid. The pressure-sensitive adhesive tape for workpiece processing according to claim 2, which is a polyfunctional (meth) acrylic ester.
The work processing pressure-sensitive adhesive tape according to any one of claims 1 to 3, wherein the energy ray curable compound (B) has two or more (meth) acryloyl groups in one molecule.
The pressure-sensitive adhesive tape for workpiece processing according to any one of claims 1 to 4, wherein the urethane resin (A) has a photopolymerizable unsaturated bond.
The pressure-sensitive adhesive layer is formed from a pressure-sensitive adhesive composition containing at least a urethane polymer (A ′), the energy ray-curable compound (B), and a crosslinking agent (C).
The pressure-sensitive adhesive tape for workpiece processing according to any one of claims 1 to 5, wherein the urethane resin (A) is obtained by crosslinking the urethane polymer (A ') with the crosslinking agent (C).
The pressure-sensitive adhesive tape for workpiece processing according to claim 6, wherein the crosslinking agent (C) includes a crosslinking agent (C1) containing a photopolymerizable unsaturated bond.
The pressure-sensitive adhesive tape for workpiece processing according to claim 6 or 7, wherein the urethane polymer (A ') and the cross-linking agent (C) are bonded by a urethane bond.
9. The pressure-sensitive adhesive composition further comprises a compound (D) having a photopolymerizable unsaturated bond and a reactive functional group capable of reacting with the crosslinking agent (C). Adhesive tape for workpiece processing as described in 1.
The work processing pressure-sensitive adhesive tape according to claim 9, wherein the compound (D) is a polyfunctional (meth) acrylic ester which is a partial ester of polyhydric alcohol and (meth) acrylic acid.
The pressure-sensitive adhesive tape for workpiece processing according to any one of claims 1 to 10, wherein a breaking stress of the pressure-sensitive adhesive layer after irradiation with energy rays is 2.5 MPa or more.
12. The work processing pressure-sensitive adhesive tape according to claim 1, further comprising an intermediate layer between the base material and the pressure-sensitive adhesive layer.
The work processing pressure-sensitive adhesive tape according to claim 12, wherein the intermediate layer has a thickness of 10 to 600 µm.
The pressure-sensitive adhesive tape for workpiece processing according to claim 12 or 13, wherein the intermediate layer has a loss tangent at 50 ° C measured at a frequency of 1 Hz of 1.0 or more.
The pressure-sensitive adhesive tape for workpiece processing according to any one of claims 1 to 14, wherein the adhesive strength after irradiation with energy rays is 2000 mN / 25 mm or less.
The adhesive tape for workpiece processing according to any one of claims 1 to 15, which is an adhesive tape for protecting a semiconductor wafer surface.