JP2017214528A - Pressure-sensitive adhesive tape for vacuum process - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pressure-sensitive adhesive tape which produces less out gas leading to deposition generated inside an apparatus (for instance, a decompression piping) in a vacuum process.SOLUTION: A pressure-sensitive adhesive tape for a vacuum process includes a base material and an adhesive layer arranged at least on one side of the base material. The adhesive layer includes an active energy ray-curable adhesive agent including a base polymer and a photoinitiator. A 5% weight loss temperature is 160°C or higher in a TGA (thermogravimetry analysis) of the photoinitiator.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an adhesive tape for vacuum process.

  Conventionally, as a method of attaching an adhesive tape, with the adhesive tape disposed above the adherend, separate airtight spaces are formed above and below the adhesive tape, and both the upper airtight space and the lower airtight space are decompressed. Then, a method is known in which only the upper airtight space is returned to atmospheric pressure, and a pressure-sensitive adhesive tape is attached to the adherend using the differential pressure. For example, in recent years, a sheet-like underfill material may be used to reinforce and protect the bumps of a semiconductor chip during flip-chip mounting. A pasting method may be employed.

  However, when an adhesive tape is used in a vacuum process typified by the above-described method of applying pressure by reduced pressure, there is a problem that precipitates are generated in the reduced pressure piping, and as a result, the degree of vacuum at the time of reduced pressure is lowered.

JP 2014-203964 A JP 2014-236152 A

  The inventors of the present invention have found that the deposit in the decompression pipe is caused by outgas from the adhesive tape. The present invention has been made to solve the above-described conventional problems, and an object of the present invention is to provide an adhesive that generates less outgas which causes precipitates generated in the apparatus (for example, decompression piping) in a vacuum process. To provide a tape.

The pressure-sensitive adhesive tape for vacuum process of the present invention comprises a base material and a pressure-sensitive adhesive layer disposed on at least one side of the base material, and the pressure-sensitive adhesive layer contains a base polymer and a photopolymerization initiator. It is composed of a curable pressure-sensitive adhesive, and the 5% weight loss temperature in TGA (thermogravimetric analysis) of the photopolymerization initiator is 160 ° C. or higher.
In one embodiment, the photopolymerization initiator has a functional group capable of binding to the base polymer.
In one embodiment, the functional group is a hydroxyethoxy group.
In one embodiment, the molecular weight of the said photoinitiator is 150-600.
In one embodiment, the said active energy ray hardening-type adhesive further contains a crosslinking agent, and the content rate of this crosslinking agent is 3 weight part or more with respect to 100 weight part of said base polymers.

  According to the present invention, by providing an adhesive layer composed of an active energy ray-curable adhesive containing a specific photopolymerization initiator, the cause of precipitates generated in the apparatus (for example, decompression piping) in a vacuum process Thus, an adhesive tape with less outgassing can be obtained.

It is a schematic sectional drawing of the adhesive tape for vacuum processes by one Embodiment of this invention.

A. Overview of Vacuum Process Adhesive Tape FIG. 1 is a schematic cross-sectional view of a vacuum process adhesive tape according to one embodiment of the present invention. The vacuum process pressure-sensitive adhesive tape 100 includes a base material 10 and a pressure-sensitive adhesive layer 20 disposed on at least one side of the base material 10. Although not shown, the adhesive tape of the present invention may be provided with a release liner on the outside of the adhesive layer for the purpose of protecting the adhesive surface until it is used. Hereinafter, in the present specification, the vacuum process adhesive tape may be simply referred to as an adhesive tape.

  The pressure-sensitive adhesive layer is composed of an active energy ray-curable pressure-sensitive adhesive containing a base polymer and a photopolymerization initiator. The active energy ray-curable adhesive is an adhesive that is cured by irradiating with an active energy ray such as an ultraviolet ray to reduce the adhesive force, and is an adhesive having a predetermined adhesive force before irradiation with the active energy ray. That means. The photopolymerization initiator contained in the active energy ray-curable pressure-sensitive adhesive has a 5% weight reduction temperature of 160 ° C. or higher in TGA (thermogravimetric analysis). By containing such a photopolymerization initiator, outgas generation under vacuum can be suppressed. When such an adhesive tape is used in a vacuum process, generation of precipitates due to outgas can be prevented in an apparatus used in the process. In one embodiment, if the pressure-sensitive adhesive tape of the present invention is used, the generation of precipitates in the decompression pipe can be suppressed, and the narrowing and blockage of the decompression pipe can be prevented. As a result, the degree of vacuum in the vacuum process can be reduced. It can be maintained well. In addition, a vacuum process means the process performed in the environment decompressed from atmospheric pressure. In one embodiment, the pressure-sensitive adhesive tape can be used in a vacuum process including a heating process (for example, 70 ° C. to 80 ° C.).

  As an example of the vacuum process, there is a process of sticking an adhesive tape as an underfill material to the semiconductor chip in order to reinforce and protect the bumps of the semiconductor chip during flip chip mounting. In the process, with the adhesive tape disposed above the semiconductor chip (bump forming surface), separate airtight spaces are formed above and below the adhesive tape, and both the upper airtight space and the lower airtight space are decompressed, Thereafter, only the upper airtight space is returned to atmospheric pressure, and the pressure-sensitive adhesive tape is attached to the adherend using the differential pressure. A process of reducing the pressure in both the upper airtight space and the lower airtight space corresponds to a vacuum process.

  The adhesive sheet of the present invention has an initial adhesive force at 23 ° C. to a semiconductor mirror wafer (made of silicon) of preferably 0.1 N / 20 mm to 30.0 N / 20 mm, and more preferably 1.0 N / 20 mm to 25.25 mm. 0 N / 20 mm, particularly preferably 2.0 N / 20 mm to 20.0 N / 20 mm. In this specification, “initial adhesive strength” means the adhesive strength before reducing the adhesive strength of the adhesive sheet by irradiation with active energy rays. The adhesive strength is measured by a method according to JIS Z 0237 (2000) (bonding conditions: 2 kg roller 1 reciprocation, peeling speed: 300 mm / min, peeling angle 180 °).

  The pressure-sensitive adhesive sheet of the present invention has an adhesive strength of preferably 2 N / 20 mm or less, more preferably 1 N / 20 mm or less, more preferably 0.4 N / 20 mm by irradiating the adhesive layer with active energy rays. More preferably, The pressure-sensitive adhesive sheet of the present invention is excellent in removability because the adhesive strength is reduced by irradiating active energy rays. More specifically, a photopolymerization initiator that is likely to remain in the pressure-sensitive adhesive layer (that is, a photopolymerization initiator having a 5% weight loss temperature of 160 ° C. or more in TGA (thermogravimetric analysis), a specific functionality as described later. Even when a photopolymerization initiator having a group) is used, adhesive residue at the time of re-peeling can be suppressed.

  The thickness of the pressure-sensitive adhesive sheet is preferably 10 μm to 200 μm, more preferably 30 μm to 100 μm.

B. As described above, the pressure-sensitive adhesive layer is composed of an active energy ray-curable pressure-sensitive adhesive containing a base polymer and a photopolymerization initiator. If an active energy ray-curable adhesive is used, an adhesive sheet that has low elasticity and high flexibility at the time of application and is easy to handle, and that can be peeled off can be reduced by irradiating active energy rays. Can be obtained. Examples of the active energy rays include gamma rays, ultraviolet rays, visible rays, infrared rays (heat rays), radio waves, alpha rays, beta rays, electron beams, plasma flows, ionizing rays, particle rays and the like. In the present specification, unless otherwise specified, the “pressure-sensitive adhesive layer” means a pressure-sensitive adhesive layer before the decrease in adhesive strength (before irradiation with active energy rays).

(Base polymer)
In one embodiment, the active energy ray-curable pressure-sensitive adhesive includes an active energy ray-curable adhesive (base monomer) and an active energy ray-reactive compound (monomer or oligomer) that can be bound to the base polymer. An adhesive (A1) is used. In another embodiment, an active energy ray-curable pressure-sensitive adhesive (A2) containing an active energy ray-reactive polymer as a base polymer is used. Preferably, the base polymer has a functional group capable of reacting with a photopolymerization initiator. Examples of the functional group include a hydroxyl group and a carboxyl group.

  Examples of the base polymer used in the pressure-sensitive adhesive (A1) include natural rubber, polyisobutylene rubber, styrene / butadiene rubber, styrene / isoprene / styrene block copolymer rubber, recycled rubber, butyl rubber, polyisobutylene rubber, and nitrile rubber. Examples thereof include rubber polymers such as (NBR); silicone polymers; acrylic polymers. These polymers may be used alone or in combination of two or more. Of these, acrylic polymers are preferred. If an acrylic polymer is used, a pressure-sensitive adhesive layer having properties suitable for semiconductor processes (for example, adhesive strength, elastic modulus, etc.) can be formed.

  The acrylic polymer is typically an acrylic polymer (homopolymer or copolymer) formed using one or more alkyl (meth) acrylates as monomer components. Specific examples of the alkyl (meth) acrylate include methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, isopropyl (meth) acrylate, n-butyl (meth) acrylate, isobutyl (meth) acrylate, s-butyl (meth) acrylate, pentyl (meth) acrylate, isopentyl (meth) acrylate, hexyl (meth) acrylate, heptyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, octyl (meth) acrylate, isooctyl (meth) Acrylate, nonyl (meth) acrylate, isononyl (meth) acrylate, decyl (meth) acrylate, isodecyl (meth) acrylate, undecyl (meth) acrylate, dodecyl (meth) acrylate Rate, tridecyl (meth) acrylate, tetradecyl (meth) acrylate, pentadecyl (meth) acrylate, hexadecyl (meth) acrylate, heptadecyl (meth) acrylate, octadecyl (meth) acrylate, nonadecyl (meth) acrylate, eicosyl (meth) acrylate, etc. (Meth) acrylic acid C1-20 alkyl ester.

  The acrylic polymer has a configuration corresponding to other monomer components copolymerizable with the alkyl (meth) acrylate as necessary for the purpose of modifying cohesive force, heat resistance, crosslinkability, and the like. Units may be included. Examples of such monomer components include carboxyl group-containing monomers such as acrylic acid and methacrylic acid; acid anhydride monomers such as maleic anhydride and itaconic anhydride; hydroxyethyl (meth) acrylate, and (meth) acrylic acid Hydroxyl group-containing monomers such as hydroxypropyl; sulfonic acid group-containing monomers such as styrene sulfonic acid and allyl sulfonic acid; (N-substituted) amide monomers such as (meth) acrylamide and N, N-dimethyl (meth) acrylamide ; (Meth) acrylic acid aminoalkyl monomers such as (meth) acrylic acid aminoethyl; (meth) acrylic acid alkoxyalkyl monomers such as methoxyethyl (meth) acrylate; N-cyclohexylmaleimide, N-isopropylmaleimide, etc. Maleimide monomer; N-methyl Itaconimide monomers such as itaconimide and N-ethylitaconimide; succinimide monomers; vinyl monomers such as vinyl acetate, vinyl propionate, N-vinylpyrrolidone and methylvinylpyrrolidone; cyanoacrylate monomers such as acrylonitrile and methacrylonitrile; Epoxy group-containing acrylic monomers such as glycidyl acrylate; glycol acrylic ester monomers such as polyethylene glycol (meth) acrylate and polypropylene glycol (meth) acrylate; tetrahydrofurfuryl (meth) acrylate, fluorine (meth) Acrylic acid ester monomers having heterocycles such as acrylate and silicone (meth) acrylate, halogen atoms, silicon atoms, etc .; isoprene, butadiene, isobutylene Olefin monomer and the like; vinyl ether monomers such as vinyl ether. These monomer components may be used alone or in combination of two or more. Among these, a carboxyl group-containing monomer (particularly preferably acrylic acid or methacrylic acid) or a hydroxyl group-containing monomer (particularly preferably hydroxyethyl (meth) acrylate) is more preferable. If such a monomer-derived constitutional unit is introduced, the photopolymerization initiator and the acrylic polymer (base polymer) can be bonded, and the effect of the present invention becomes more remarkable. The content of the structural unit derived from the carboxyl group-containing monomer is preferably 0.5 parts by weight to 20 parts by weight, more preferably 1 part by weight to 10 parts by weight with respect to 100 parts by weight of the acrylic polymer. The content ratio of the structural unit derived from the hydroxyl group-containing monomer is preferably 0.5 to 20 parts by weight, more preferably 1 to 10 parts by weight with respect to 100 parts by weight of the acrylic polymer.

  Examples of the active energy ray-reactive compound that can be used in the pressure-sensitive adhesive (A1) include light having a functional group having a carbon-carbon multiple bond such as acryloyl group, methacryloyl group, vinyl group, allyl group, and acetylene group. Examples include reactive monomers or oligomers. Specific examples of the photoreactive monomer include trimethylolpropane tri (meth) acrylate, tetramethylolmethanetetra (meth) acrylate, pentaerythritol tri (meth) acrylate, pentaerythritol tetra (meth) acrylate, and dipentaerythritol mono. Such as hydroxypenta (meth) acrylate, dipentaerythritol hexa (meth) acrylate, 1,4-butanediol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, polyethylene glycol di (meth) acrylate, etc. Examples include esterified products of (meth) acrylic acid and polyhydric alcohols; polyfunctional urethane (meth) acrylates; epoxy (meth) acrylates; oligoester (meth) acrylates. Specific examples of the photoreactive oligomer include dimers and pentamers of the above monomers.

  Further, as the active energy ray-reactive compound, monomers such as epoxidized butadiene, glycidyl methacrylate, acrylamide, and vinyl siloxane; or oligomers composed of the monomers may be used. The pressure-sensitive adhesive (A1) containing these compounds can be cured by high energy rays such as ultraviolet rays and electron beams.

  Furthermore, as the active energy ray-reactive compound, a mixture of an organic salt such as an onium salt and a compound having a plurality of heterocyclic rings in the molecule may be used. In the mixture, an organic salt is cleaved by irradiation with active energy rays (for example, ultraviolet rays and electron beams) to generate ions, which act as starting species to cause a ring opening reaction of the heterocyclic ring to form a three-dimensional network structure. Can do. Examples of the organic salts include iodonium salts, phosphonium salts, antimonium salts, sulfonium salts, and borate salts. Examples of the heterocyclic ring in the compound having a plurality of heterocyclic rings in the molecule include oxirane, oxetane, oxolane, thiirane, aziridine and the like.

  In the pressure-sensitive adhesive (A1), the content ratio of the active energy ray-reactive compound is preferably 0.1 parts by weight to 500 parts by weight, more preferably 1 part by weight to 300 parts by weight with respect to 100 parts by weight of the base polymer. Parts by weight, more preferably 10 parts by weight to 200 parts by weight.

  Examples of the active energy ray-reactive polymer (base polymer) contained in the pressure-sensitive adhesive (A2) include functional groups having carbon-carbon multiple bonds such as acryloyl group, methacryloyl group, vinyl group, allyl group, and acetylene group. The polymer which has is mentioned. Specific examples of the polymer having an active energy ray-reactive functional group include a polymer composed of a polyfunctional (meth) acrylate; a photocationic polymerization type polymer; a cinnamoyl group-containing polymer such as polyvinyl cinnamate; a diazotized amino novolak Resin; polyacrylamide; and the like.

  The pressure-sensitive adhesive (A2) may further contain the active energy ray-reactive compound (monomer or oligomer).

  The weight average molecular weight of the base polymer constituting the pressure-sensitive adhesive is preferably 300,000 to 2,000,000, more preferably 500,000 to 1,500,000. The weight average molecular weight can be measured by GPC (solvent: THF).

  The glass transition temperature of the base polymer constituting the pressure-sensitive adhesive is preferably -50 ° C to 30 ° C, more preferably -40 ° C to 20 ° C. If it is such a range, it will be excellent in heat resistance and the adhesive sheet which can be used suitably at a heating process can be obtained.

(Photopolymerization initiator)
As described above, the 5% weight loss temperature in TGA (thermogravimetric analysis) of the photopolymerization initiator is 160 ° C. or higher. The 5% weight loss temperature means that when the photopolymerization initiator is placed in a nitrogen atmosphere and the environmental temperature is increased from room temperature (23 ° C.) at a rate of temperature increase of 10 ° C./min, the weight of the photopolymerization initiator is The environmental temperature at the time when the weight is decreased by 5% by weight with respect to the weight before temperature increase (that is, the weight of the photopolymerization initiator becomes 95% by weight with respect to the weight before temperature increase). The 5% weight loss temperature of the photopolymerization initiator is more preferably 170 ° C or higher, and further preferably 170 ° C to 300 ° C. Examples of the photopolymerization initiator having a 5% weight loss temperature within such a range include trade names “Irgacure 651”, “Irgacure 2959”, “Irgacure 369”, “Irgacure 127”, “Irgacure 379” manufactured by BASF. And “Irgacure 819”.

  In one embodiment, the photopolymerization initiator has a functional group capable of binding to the base polymer. In one embodiment, a base polymer containing a hydroxyl group or a carboxyl group is used as the base polymer, and a functional group capable of binding to the base polymer (substantially a hydroxyl group or a carboxyl group) is used as a photopolymerization initiator. A photopolymerization initiator having a group is used. In the present invention, by using a photopolymerization initiator having a functional group capable of binding to the base polymer, an adhesive tape capable of significantly suppressing outgassing under vacuum can be obtained.

  Examples of the functional group that can be bonded to the base polymer of the photopolymerization initiator include a hydroxyl group and a hydroxyethoxy group. Examples of the compound that can be used as a photopolymerization initiator having such a functional group include 1- [4- (2-hydroxyethoxy) -phenyl] -2-hydroxy-2-methyl-1-propane- 1-one (trade name “Irgacure 2959” manufactured by BASF AG, oligo (2-hydroxy-2-methyl-1- [4- (1-methylvinyl) phenyl] propanone) (trade name “Esacure One” manufactured by Lamberti) )), An oligomer polyfunctional alpha-hydroxyketone (manufactured by Lamberti, trade name “Esacure KIP150”) and the like.

  The molecular weight of the compound that can be used as the photopolymerization initiator is preferably 150 to 600, more preferably 200 to 500, and still more preferably 220 to 400. If it is such a range, the effect of this invention will become more remarkable.

  The content of the photopolymerization initiator is preferably 0.1 parts by weight to 20 parts by weight, more preferably 1 part by weight to 15 parts by weight, further preferably 100 parts by weight of the base polymer. 3 to 10 parts by weight. If it is such a range, generation | occurrence | production of outgas is suppressed, hardening by an active energy ray fully progresses, and the adhesive layer from which adhesive force falls appropriately can be formed.

(Other ingredients)
The active energy ray-curable pressure-sensitive adhesive may contain any appropriate additive as required. Examples of the additive include an active energy ray polymerization accelerator, a crosslinking agent, a radical scavenger, a tackifier, a plasticizer (for example, trimellitic acid ester plasticizer, pyromellitic acid ester plasticizer, etc.), pigment, Examples include dyes, fillers, anti-aging agents, conductive materials, antistatic agents, ultraviolet absorbers, light stabilizers, release modifiers, softeners, surfactants, flame retardants, and antioxidants.

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

  Specific examples of the isocyanate-based crosslinking agent include lower aliphatic polyisocyanates such as butylene diisocyanate and hexamethylene diisocyanate; alicyclic isocyanates such as cyclopentylene diisocyanate, cyclohexylene diisocyanate and isophorone diisocyanate; 2,4- Aromatic isocyanates such as tolylene diisocyanate, 4,4′-diphenylmethane diisocyanate, xylylene diisocyanate; trimethylolpropane / tolylene diisocyanate trimer adduct (trade name “Coronate L” manufactured by Nippon Polyurethane Industry Co., Ltd.), tri Methylolpropane / hexamethylene diisocyanate trimer adduct (manufactured by Nippon Polyurethane Industry Co., Ltd., trade name “Coronate HL”), hexamethylene diisocyanate isocyanate Isocyanurate body (Nippon Polyurethane Industry Co., Ltd. under the trade name "Coronate HX") isocyanate adducts of the like; and the like.

  The content of the crosslinking agent is preferably 3 parts by weight or more, more preferably 3 parts by weight to 10 parts by weight with respect to 100 parts by weight of the base polymer. Within such a range, a photopolymerization initiator that is likely to remain in the pressure-sensitive adhesive layer (that is, a photopolymerization initiator having a 5% weight loss temperature of 160 ° C. or more in TGA (thermogravimetric analysis), the above-mentioned specific functional group Even when using a photopolymerization initiator having the above, adhesive residue can be suppressed.

(Characteristics of adhesive layer)
The thickness of the pressure-sensitive adhesive layer is preferably 5 μm to 300 μm, more preferably 10 μm to 250 μm, still more preferably 20 μm to 200 μm, and particularly preferably 50 μm to 150 μm. In one embodiment, the thickness of an adhesive layer is 50 micrometers or more. When the thickness of the pressure-sensitive adhesive layer is in such a range, a pressure-sensitive adhesive tape that has excellent step following ability and can cover an uneven adherend (for example, a semiconductor chip having bumps) without a gap can be obtained.

The initial storage elastic modulus E ′ at 23 ° C. of the pressure-sensitive adhesive layer is preferably 0.5 × 10 ⁶ Pa to 1.0 × 10 ⁸ Pa, more preferably 0.8 × 10 ⁶ Pa to 3.0. × 10 ⁷ Pa. If it is such a range, the adhesive tape which is excellent in level | step difference followable | trackability and can coat | cover the uneven adherend (for example, semiconductor chip which has bump) without a space | gap can be obtained. Moreover, the initial storage elastic modulus E ′ of the pressure-sensitive adhesive layer at 80 ° C. is preferably 0.5 × 10 ⁴ Pa to 1.0 × 10 ⁶ Pa, and more preferably 1.0 × 10 ⁴ Pa to 1. 0.0 × 10 ⁵ Pa. The “initial elastic modulus” means an elastic modulus before the adhesive layer is irradiated with active energy rays to reduce the adhesive strength of the adhesive sheet. The initial storage elastic modulus E ′ can be measured using a dynamic viscoelasticity measuring apparatus (for example, trade name “ARES” manufactured by Rheometrics) under measurement conditions of a frequency of 1 Hz and a heating rate of 10 ° C./min.

C. Substrate The substrate can be composed of any suitable resin. Examples of the resin include polyolefins such as low density polyethylene, linear polyethylene, medium density polyethylene, high density polyethylene, ultra low density polyethylene, random copolymer polypropylene, block copolymer polypropylene, homopolypropylene, polybutene, and polymethylpentene. , Ethylene-vinyl acetate copolymer, ionomer resin, ethylene- (meth) acrylic acid copolymer, ethylene- (meth) acrylic acid ester (random, alternating) copolymer, ethylene-butene copolymer, ethylene-hexene Copolymers, Polyesters such as polyurethane and polyethylene naphthalate, Polyimide, Polyetherketone, Polystyrene, Polyvinyl chloride, Polyvinylidene chloride, Fluororesin, Silicone resin, Cellulosic resin, and cross-linked products thereof And the like.

  The glass transition temperature of the resin constituting the substrate is preferably 60 ° C to 500 ° C, more preferably 100 ° C to 500 ° C. If it is such a range, it will be excellent in heat resistance and the adhesive sheet which can be used suitably at a heating process can be obtained. The “glass transition temperature” is a peak of loss tangent (tan δ) that is confirmed in the DMA method (tensile method) under the conditions of a heating rate of 5 ° C./min, a sample width of 5 mm, a distance between chucks of 20 mm, and a frequency of 10 Hz. Means the temperature.

  The thickness of the substrate is preferably 50 μm to 300 μm, more preferably 80 μm to 250 μm, and still more preferably 100 μm to 200 μm.

  The surface of the base material may be subjected to any surface treatment in order to improve adhesion with adjacent layers, retention, and the like. Examples of the surface treatment include chemical or physical treatment such as chromic acid treatment, ozone exposure, flame exposure, high piezoelectric impact exposure, ionizing radiation treatment, and coating treatment.

D. Manufacturing method of adhesive tape The said adhesive tape may be manufactured by arbitrary appropriate methods. The pressure-sensitive adhesive tape can be obtained, for example, by coating the pressure-sensitive adhesive on a substrate. Coating methods include bar coater coating, air knife coating, gravure coating, gravure reverse coating, reverse roll coating, lip coating, die coating, dip coating, offset printing, flexographic printing, screen printing, etc. Various methods can be employed. In addition, a method in which a pressure-sensitive adhesive layer is separately formed on a release liner and then bonded to a substrate may be employed.

  EXAMPLES Hereinafter, although an Example demonstrates this invention concretely, this invention is not limited by these Examples. In Examples, unless otherwise specified, “parts” and “%” are based on weight.

[Example 1]
Acrylic copolymer as a base polymer (2-ethylhexyl (meth) acrylate, copolymer of methyl acrylate and acrylic acid, 2-ethylhexyl (meth) acrylate constitutional unit: methyl acrylate constitutional unit: acrylic acid constitutional unit = 25: 70: 5 ( (Weight ratio)) 100 parts by weight, polyfunctional oligomer (urethane acrylate, Nippon Synthetic Chemical, trade name “UV-1700TL”) 90 parts by weight and polyfunctional oligomer (urethane acrylate, Nippon Synthetic Chemical, trade name “UV-3000TL”) 90 parts by weight, 3 parts by weight of an isocyanate-based crosslinking agent (trade name “Coronate L” manufactured by Tosoh Corporation), and a photopolymerization initiator (trade name “Irgacure 651” manufactured by BASF Corporation; molecular weight: 256.3) Adhesive A was obtained by mixing 7 parts by weight.
This pressure-sensitive adhesive A was applied to one side of a low-density polyethylene film (thickness: 150 μm) as a base material to obtain a pressure-sensitive adhesive sheet composed of a base material and a pressure-sensitive adhesive layer (thickness: 50 μm).

[Example 2]
Instead of 7 parts by weight of photopolymerization initiator (BASF, trade name “Irgacure 651”), 7 parts by weight of photopolymerization initiator (BASF, trade name “Irgacure 369”; molecular weight: 366.5) is used. A pressure-sensitive adhesive sheet was obtained in the same manner as in Example 1 except that it was.

[Example 3]
Instead of 7 parts by weight of photopolymerization initiator (BASF, trade name “Irgacure 651”), 7 parts by weight of photopolymerization initiator (BASF, trade name “Irgacure 2959”; molecular weight: 224.3) is used. A pressure-sensitive adhesive sheet was obtained in the same manner as in Example 1 except that it was. The photopolymerization initiator “Irgacure 2959” has a structure represented by the following general formula (1).

[Comparative Example 1]
Instead of 7 parts by weight of photopolymerization initiator (BASF, trade name “Irgacure 651”), 7 parts by weight of photopolymerization initiator (BASF, trade name “Irgacure 184”; molecular weight: 204.3) is used. A pressure-sensitive adhesive sheet was obtained in the same manner as in Example 1 except that it was.

[Comparative Example 2]
Instead of 7 parts by weight of photopolymerization initiator (BASF, trade name “Irgacure 651”), 7 parts by weight of photopolymerization initiator (BASF, trade name “Irgacure 1173”; molecular weight: 164.2) is used. A pressure-sensitive adhesive sheet was obtained in the same manner as in Example 1 except that it was.

[Evaluation]
(1) 5% weight reduction temperature of photopolymerization initiator Using a differential thermal analyzer (trade name “TG / DTA220” manufactured by SII Nano Technology Inc.), the pressure-sensitive adhesive sheet was heated at a temperature of 10 ° C./minute, and the atmosphere Below, the flow rate was 200 ml / min, and the temperature at which the weight decreased by 5% was measured.

(2) Outgas amount 1 g of the pressure-sensitive adhesive sheet and the adsorbent (TenaxTA) were allowed to stand in a heated and reduced pressure environment (100 ° C., 1000 Pa) for 1 hour, and out of the pressure-sensitive adhesive sheet adsorbed ass on the adsorbent. Then, the adsorbent is heated with a heat desorption apparatus (Agilent Technologies, trade name “TDS / CIS”) directly connected to a gas chromatograph mass spectrometer (Agilent Technologies, trade name “HP6890pls / HP5973”). (Ie, the outgas) was desorbed. The desorption component due to heat desorption was cold trapped by cooling the inlet portion of the gas chromatograph mass spectrometer with liquid nitrogen. Thereafter, the inlet of the analyzer was rapidly heated to introduce the desorbed component into the column provided in the analyzer, and the amount of desorbed component (that is, the amount of outgas) was measured.
For preparations with a predetermined concentration prepared by diluting toluene pure drug with methanol, measuring the outgas amount in the same manner as the adhesive tape, the preparation concentration (concentration at the time of preparation) and peak concentration (gas chromatographic detection) Value) and a calibration curve was created, and the amount of outgas per 1 g of the pressure-sensitive adhesive sheet was determined in terms of toluene using the calibration curve.

  The pressure-sensitive adhesive tape of the present invention can be suitably used as a pressure-sensitive adhesive tape for a vacuum process (for example, a vacuum process in semiconductor production).

10 Substrate 20 Adhesive layer 100 Adhesive tape

Claims (5)

A substrate and a pressure-sensitive adhesive layer disposed on at least one side of the substrate;
The pressure-sensitive adhesive layer is composed of an active energy ray-curable pressure-sensitive adhesive containing a base polymer and a photopolymerization initiator,
5% weight loss temperature in TGA (thermogravimetric analysis) of the photopolymerization initiator is 160 ° C. or higher.
Adhesive tape for vacuum process.   The pressure-sensitive adhesive tape for vacuum process according to claim 1, wherein the photopolymerization initiator has a functional group capable of binding to the base polymer.   The pressure-sensitive adhesive tape for vacuum process according to claim 2, wherein the functional group is a hydroxyethoxy group.   The pressure-sensitive adhesive tape for vacuum process according to any one of claims 1 to 3, wherein the molecular weight of the photopolymerization initiator is 150 to 600. The active energy ray-curable pressure-sensitive adhesive further contains a crosslinking agent,
The pressure-sensitive adhesive tape for vacuum process according to any one of claims 1 to 4, wherein a content ratio of the crosslinking agent is 3 parts by weight or more with respect to 100 parts by weight of the base polymer.

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