JP2022014994A - Adhesive tape - Google Patents

Abstract

To provide an adhesive tape which suppresses leakage of a filler filling a hole, enables easy peeling without an adhesive residue, and can suppress discoloration of a conductor circuit.SOLUTION: An adhesive tape 10 that is used in a step of filling a hole of a multilayer printed wiring board with a resin has a base material film 12 and an adhesive layer 14 formed on the base material film 12, in which the adhesive layer 14 is composed of an adhesive composition containing a (meth)acrylic copolymer having a carboxy group and an epoxy-based crosslinking agent, an acid value of the (meth)acrylic copolymer having a carboxy group is 4.0 mg/KOH or more and 40 mg/KOH or less, a ratio (b/a) of a molar quantity (b) of an epoxy group of the epoxy-based crosslinking agent to a molar quantity (a) of a carboxy group of the (meth)acrylic copolymer having the carboxy group is 0.3 or more and 1.1 or less, and a peeling force to a copper plate at 23°C of the adhesive layer 14 is 0.3 N/25 mm or more and 20 N/25 mm or less.SELECTED DRAWING: Figure 1

Description

The present invention relates to an adhesive tape, and more particularly to an adhesive tape used in a step of filling holes in a multilayer printed wiring board with a resin.

With the miniaturization and higher functionality of electronic devices, printed wiring boards are required to have smaller patterns, smaller mounting areas, and higher density of component mounting. Therefore, in the printed wiring board, a double-sided circuit board provided with through holes for forming an interlayer connection for electrically connecting different wiring layers, that is, through holes, an insulating layer, and a conductor circuit are sequentially formed on the core material. A multilayer board such as a build-up wiring board that is formed and interconnected with layers such as via holes to form multiple layers is used.

In such a printed wiring board, the recesses between the conductor circuits on the surface and the holes such as through holes and via holes in which the wiring layer is formed on the inner wall surface are filled with a filler such as a thermosetting resin. Is generally done. As the filler of the thermosetting resin, a material containing an epoxy resin as a thermosetting resin component, an epoxy resin curing agent, and an inorganic filler is generally used.

As a method of filling the pores with a thermosetting resin filler, for example, a method of filling by a stencil printing method (Patent Document 1), an excess supply layer made of a thermosetting resin filler is formed on a substrate. After that, there is a method of removing the excess resin (Patent Document 2).

Japanese Unexamined Patent Publication No. 2000-183519 Japanese Patent Application Laid-Open No. 2003-188308

In the method of Patent Document 2, there are many steps of removing excess resin, which tends to be complicated. On the other hand, in such a filling method, when the hole is a through hole such as a through hole or a through hole, an adhesive tape is attached to the back surface side of the substrate, and the through hole formed in the substrate is referred to as a bottomed hole. By doing so, it is possible to prevent the filler from oozing out to the back surface side of the substrate and leaking. Further, when the electronic component elements such as the semiconductor element, the coil, and the heat radiating component arranged in the hole are filled with the filler of the thermosetting resin, the electronic component element can be easily arranged and fixed. Then, by removing the adhesive tape after the curing step of the filler of the thermosetting resin, the filling of the through holes can be easily completed.

However, in the adhesive tape used to fill the through holes of the substrate, the adhesive layer reacts with the thermosetting resin during the curing process of the filler of the thermosetting resin, and the adhesiveness with the surface of the conductor circuit such as copper is poor. There is a risk that it will not be easily peeled off due to rising, or that the conductor circuit such as copper will be discolored.

An object to be solved by the present invention is to provide an adhesive tape that can suppress leakage of a filler that fills a hole, can be easily peeled off without adhesive residue, and can further suppress discoloration of a conductor circuit. It is in.

In order to solve the above problems, the adhesive tape according to the present invention is an adhesive tape used in a step of filling holes in a multilayer printed wiring board with a resin, and is a base film and an adhesive formed on the base film. The pressure-sensitive adhesive layer comprises a layer, and the pressure-sensitive adhesive layer is composed of a pressure-sensitive adhesive composition containing a (meth) acrylic copolymer having a carboxy group and an epoxy-based cross-linking agent, and the (meth) acrylic having the carboxy group. The acid value of the system copolymer is 4.0 mg / KOH or more and 40 mg / KOH or less, and the molar amount (a) of the carboxy group of the (meth) acrylic copolymer having the carboxy group and the epoxy-based cross-linking agent. The ratio (b / a) to the molar amount (b) of the epoxy group is 0.3 or more and 1.1 or less, and the peeling force of the adhesive layer with respect to the copper plate at 23 ° C. is 0.3 N / 25 mm or more. It is 20 N / 25 mm or less.

The storage elastic modulus of the pressure-sensitive adhesive layer at 23 ° C. is preferably 0.8 × 10 ⁴ Pa or more and 40 × 10 ⁴ Pa or less. The base film may contain at least one of polyethylene terephthalate, polyethylene naphthalate, polyimide, polymethyl methacrylate, polycarbonate, polyamide, and polyphenylene sulfide.

According to the adhesive tape according to the present invention, leakage of the filler that fills the holes can be suppressed, peeling can be easily performed without adhesive residue, and discoloration of the conductor circuit can be suppressed.

It is sectional drawing of the adhesive tape which concerns on one Embodiment of this invention. It is a process diagram of the hole filling process in which the hole of a multilayer printed wiring board is filled with a filler of a thermosetting resin by using an adhesive tape.

Hereinafter, the present invention will be described in detail.

FIG. 1 is a cross-sectional view of an adhesive tape according to an embodiment of the present invention. As shown in FIG. 1, the pressure-sensitive adhesive tape 10 according to the embodiment of the present invention has a base film 12 and a pressure-sensitive adhesive layer 14 formed on one surface of the base film 12.

(Base film)
Examples of the base film 12 include a polymer film and a glass film. Examples of the polymer material of the base film 12 include polyesters such as polyethylene terephthalate and polyethylene naphthalate, polycarbonate, poly (meth) acrylate, polystyrene, polyamide, polyimide, polyacrylonitrile, polypropylene, polyethylene, polycycloolefin and cycloolefin copolymer. Examples thereof include cellulose-based resins such as polyolefin, triacetyl cellulose and diacetyl cellulose, polyphenylene sulfide, polyvinyl chloride, polyvinylidene chloride, and polyvinyl alcohol. The polymer material of the base film 12 may be composed of only one of these, or may be composed of a combination of two or more.

Among these, from the viewpoint of mechanical strength and heat resistance, polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polyimide (PI), polymethyl methacrylate (PMMA), polycarbonate (PC), polyamide (PA) , At least one of polyphenylene sulfide (PPS) is preferable. In particular, polyethylene terephthalate (PET), polyethylene naphthalate (PEN), and polyimide (PI) are preferable.

The thickness of the base film 12 suppresses the protrusion of the filler to the adhesive tape 10 side due to the deflection of the adhesive tape 10 when the resin (filler) is filled in the step of filling the holes of the multilayer printed wiring board with the resin. The lower limit is 10 μm or more, more preferably 30 μm or more, still more preferably 50 μm or more. The upper limit is not particularly limited, but is 500 μm or less, preferably 200 μm or less from the viewpoint of handleability and the like. The term "film" generally means a film having a thickness of less than 0.25 mm, but even if the film has a thickness of 0.25 mm or more, the thickness is 0 if it can be rolled into a roll. Even if it is .25 mm or more, it shall be included in the "film".

(Adhesive layer)
The adhesive layer 14 is for attaching the adhesive tape 10 to an adherend such as a multilayer printed wiring board. The pressure-sensitive adhesive layer 14 is composed of a pressure-sensitive adhesive composition containing a (meth) acrylic copolymer having a carboxy group and an epoxy-based cross-linking agent.

((Meta) acrylic copolymer having a carboxy group)
In the (meth) acrylic copolymer having a carboxy group, the carboxy group is a reactive functional group, and therefore, discoloration of the conductor circuit (copper) is suppressed even if it comes into contact with the conductor circuit (copper) of the multilayer printed wiring board. Be done.

Examples of the (meth) acrylic monomer having a carboxy group include (meth) acrylic acid, carboxyethyl (meth) acrylate, carboxypentyl (meth) acrylate, 2- (meth) acryloyloxyethyl succinate, and 2- (meth) acryloyloxy. Examples thereof include a monomer obtained by reacting a (meth) acrylate having a hydroxy group such as ethyl maleate and 2- (meth) acryloyloxyethyl phthalate with an acid anhydride such as maleic anhydride, succinic anhydride and phthalic anhydride. Among these, (meth) acrylic acid is preferable.

The acid value of the (meth) acrylic copolymer having a carboxy group is 4.0 mg / KOH or more and 40 mg / KOH or less. If the acid value is less than 4.0 mg / KOH, the cohesive force of the pressure-sensitive adhesive is lowered, and adhesive residue or contamination occurs when peeling from the multilayer printed wiring board. From this viewpoint, the acid value is preferably 6.0 mg / KOH or more, and more preferably 7.0 mg / KOH or more. On the other hand, when the acid value exceeds 40 mg / KOH, the pressure-sensitive adhesive layer 14 reacts with the thermosetting resin which is a filler that fills the pores and firmly adheres to the adhesive tape 10 from the multilayer printed wiring board. Adhesive residue is generated during peeling. From this viewpoint, the acid value is preferably 30 mg / KOH or less, more preferably 25 mg / KOH or less.

The amount of the carboxy group of the (meth) acrylic copolymer having a carboxy group is preferably 0.5 mmol / 100 g or more and 150 mmol / 100 g or less. When the amount of carboxy groups is 0.5 mmol / 100 g or more, the hardness of the pressure-sensitive adhesive layer 14 is ensured, so that the durability of the pressure-sensitive adhesive layer 14 is improved. From this viewpoint, the amount of carboxy group is more preferably 1 mmol / 100 g or more, further preferably 3 mmol / 100 g or more, and particularly preferably 9 mmol / 100 g or more. On the other hand, when the amount of the carboxy group is 150 mmol / 100 g or less, the pressure-sensitive adhesive layer 14 does not become too hard and the adhesiveness is ensured, so that the pressure-sensitive adhesive layer 14 has excellent adhesion to the adherend. From this viewpoint, the amount of carboxy group is more preferably 100 mmol / 100 g or less, further preferably 70 mmol / 100 g or less, and particularly preferably 45 mmol / 100 g or less.

(Epoxy cross-linking agent)
The epoxy-based cross-linking agent refers to a compound having two or more epoxy groups in one molecule as a reactive group. Only one type of epoxy cross-linking agent may be used alone, or two or more types may be used in combination.

Examples of the epoxy-based cross-linking agent include bisphenol A type epoxy-based resin, ethylene glycidyl ether, N, N, N', N'-tetraglycidyl-m-xylene diamine, diglycidyl aniline, diamine glycidyl amine, 1,3. -Bis (N, N-diglycidylaminomethyl) cyclohexane, 1,6-hexanediol diglycidyl ether, neopentyl glycol diglycidyl ether, ethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, polypropylene Glycoldiglycidyl ether, sorbitol polyglycidyl ether, glycerol polyglycidyl ether, pentaerythritol polyglycidyl ether, glycerin diglycidyl ether, glycerin triglycidyl ether, polyglycerol polyglycidyl ether, sorbitan polyglycidyl ether, trimethylolpropane polyglycidyl ether, adipine Examples thereof include acid diglycidyl ester, o-phthalic acid diglycidyl ester, triglycidyl-tris (2-hydroxyethyl) isocyanurate, resorcin diglycidyl ether, bisphenol-S-diglycidyl ether and the like.

When two or more epoxy-based cross-linking agents are used in combination, at least one of them may be a cross-linking agent that is solid at 23 ° C. Specifically, those having a softening point of 20 ° C. to 150 ° C. are preferably used, those having a softening point of 40 ° C. to 120 ° C. are more preferable, and those having a softening point of 60 ° C. to 100 ° C. are more preferable.

The content of the cross-linking agent which is solid at 23 ° C. is preferably 1 part by mass to 60 parts by mass, more preferably 3 parts by mass or more, based on 100 parts by mass of the (meth) acrylic copolymer having a carboxy group. It is 30 parts by mass, more preferably 5 parts by mass to 10 parts by mass. When those in the above range are used, they can also function as a tackifier and have a good initial peeling force, and the heat resistance of the pressure-sensitive adhesive layer 14 is improved.

The content of the reactive group of the epoxy-based cross-linking agent is preferably 0.5 mmol / g or more, more preferably 1.0 mmol / g or more, still more preferably 1.5 mmol / g or more, and particularly preferably 6.0 mmol / g or more. It is / g or more, preferably 20 mmol / g or less, more preferably 15 mmol / g or less, still more preferably 12 mmol / g or less. When the content of the reactive group of the cross-linking agent is in this range, the cohesive force of the pressure-sensitive adhesive layer 14 is preferable, and adhesive residue and resin leakage can be suppressed.

The content of the epoxy-based cross-linking agent is preferably 0.05 part by mass or more, more preferably 0.1 part by mass or more, and further preferably 0 with respect to 100 parts by mass of the (meth) acrylic copolymer having a carboxy group. .4 parts by mass or more, particularly preferably 0.7 parts by mass or more, preferably 16 parts by mass or less, more preferably 12 parts by mass, still more preferably 10 parts by mass or less, and particularly preferably 4 parts by mass or less. When the content of the epoxy-based cross-linking agent is 0.05 parts by mass or more, sufficient cohesive force is exhibited. When the content of the epoxy-based cross-linking agent is 16 parts by mass or less, sufficient adhesion to the film substrate 12 can be exhibited and transfer of glue can be suppressed.

The ratio (b / a) of the molar amount (a) of the carboxy group of the (meth) acrylic copolymer having a carboxy group to the molar amount (b) of the epoxy group of the epoxy-based cross-linking agent is 0.3 or more and 1 .1 or less. When the molar ratio is less than 0.3, the cohesive force of the pressure-sensitive adhesive layer 14 is insufficient, and the pressure-sensitive adhesive layer 14 is likely to be cohesively broken. From this viewpoint, the molar ratio is preferably 0.5 or more, more preferably 0.7 or more. On the other hand, when the molar ratio exceeds 1.1, the number of carboxy groups remaining in the pressure-sensitive adhesive layer 14 increases, and the reaction with the filler of the thermosetting resin suppresses the adhesive residue when the pressure-sensitive adhesive tape 10 is peeled off. do not have. From this viewpoint, the molar ratio is preferably 1.0 or less, more preferably 0.9 or less.

The pressure-sensitive adhesive composition may contain a (meth) acrylic copolymer having no carboxy group in addition to the (meth) acrylic copolymer having a carboxy group. Further, a polymer other than the (meth) acrylic copolymer may be contained.

(Other polymers)
Examples of the (meth) acrylic copolymer having no carboxy group include a (meth) acrylic copolymer having a hydroxy group, a (meth) acrylic copolymer having a sulfonic acid group, and a phosphoric acid group. (Meta) acrylic copolymer, (meth) acrylic copolymer having an epoxy group, (meth) acrylic copolymer having a linear alkyl group, (meth) acrylic copolymer having a branched alkyl group Polymers, (meth) acrylic copolymers with alicyclic hydrocarbon groups, (meth) acrylic copolymers with aromatic groups, (meth) acrylic copolymers with alkoxy groups, polyalkylenes Examples thereof include a (meth) acrylic copolymer having a glycol structural unit, a (meth) acrylic copolymer having a tertiary amino group, and a (meth) acrylamide polymer. Moreover, as a polymer other than a (meth) acrylic copolymer, a vinyl-based polymer and the like can be mentioned. Examples of the vinyl-based polymer include a vinyl-based polymerization system polymer having a hydroxy group, a vinyl-based polymer having a carboxy group, a vinyl-based polymer containing an epoxy group, a vinyl-based polymer having an aromatic group, and a heterocycle. Vinyl-based polymer, vinyl carboxylate polymer, vinyl-based polymer having a tertiary amino group, vinyl-based polymer having a quaternary ammonium base, vinyl-based polymer having a halogen group, vinylamide-based polymer, α -Examples include olefin-based polymers and diene-based polymers. As the other polymer contained in the pressure-sensitive adhesive composition, a (meth) acrylic copolymer having a hydroxy group is particularly preferable.

Examples of the hydroxy group-containing (meth) acrylic monomer constituting the hydroxy group-containing (meth) acrylic copolymer include 2-hydroxyethyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, and 2-hydroxypropyl. (Meta) acrylate, 4-hydroxybutyl (meth) acrylate, 6-hydroxyhexyl (meth) acrylate, 8-hydroxyoctyl (meth) acrylate, 10-hydroxydecyl (meth) acrylate, 12-hydroxylauryl (meth) acrylate, etc. Hydroxyalkyl (meth) acrylates; hydroxyalkylcycloalkane (meth) acrylates such as (4-hydroxymethylcyclohexyl) methyl (meth) acrylates; caprolactone adducts of hydroxyalkyl (meth) acrylates; and the like. Among these, hydroxyalkyl (meth) acrylates are preferable, and (meth) acrylates having a hydroxyalkyl group having 1 to 5 carbon atoms are more preferable.

Examples of the (meth) acrylic monomer having a sulfonic acid group constituting the (meth) acrylic copolymer having a sulfonic acid group include ethyl sulfonate (meth) acrylate. Examples of the (meth) acrylic monomer having a phosphoric acid group constituting the (meth) acrylic copolymer having a phosphoric acid group include 2- (phosphonooxy) ethyl (meth) acrylic acid. Examples of the (meth) acrylic monomer having an epoxy group constituting the (meth) acrylic copolymer having an epoxy group include glycidyl (meth) acrylate and 3,4-epoxycyclohexylmethyl (meth) acrylate.

Examples of the acrylic monomer having a linear alkyl group constituting the (meth) acrylic copolymer having a linear alkyl group include methyl acrylate, ethyl acrylate, n-propyl acrylate, n-butyl acrylate, and n-hexyl. Examples thereof include (meth) acrylic acid linear alkyl esters such as acrylates, n-octyl acrylates, n-nonyl acrylates, n-decyl acrylates, n-lauryl acrylates and n-stearyl acrylates. The acrylic monomer having a linear alkyl group preferably has 1 to 20 carbon atoms in the linear alkyl group. More preferably, the linear alkyl group has 1 to 10 carbon atoms.

Examples of the (meth) acrylic monomer having a branched alkyl group constituting the (meth) acrylic copolymer having a branched alkyl group include isopropyl (meth) acrylate, isobutyl (meth) acrylate, and sec-butyl ( Examples include (meth) acrylic acid branched chain alkyl esters such as meth) acrylate, tert-butyl (meth) acrylate, isooctyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, isononyl (meth) acrylate, and isodecyl (meth) acrylate. Be done. The (meth) acrylic monomer having a branched-chain alkyl group preferably has 3 to 20 carbon atoms in the branched-chain alkyl group. More preferably, the branched chain alkyl group has 3 to 10 carbon atoms.

Examples of the (meth) acrylic monomer having an alicyclic hydrocarbon group constituting the (meth) acrylic copolymer having an alicyclic hydrocarbon group include a (meth) acrylic monomer having a cyclic alkyl group and a polycyclic type. Examples thereof include (meth) acrylic monomers having a structure. Examples of the cyclic alkyl group include a cyclic alkyl group having a monocyclic structure (for example, a cycloalkyl group), and may have a chain portion. Specific examples of the (meth) acrylic monomer having a cyclic alkyl group having a monocyclic structure include (meth) acrylic acid cyclic alkyl esters such as cyclohexyl (meth) acrylate, methylcyclohexyl (meth) acrylate, and cyclododecyl (meth) acrylate. Can be mentioned. The (meth) acrylic monomer having a cyclic alkyl group preferably has 6 to 12 carbon atoms in the cyclic alkyl group.

Examples of the polycyclic structure include a cyclic alkyl group having a crosslinked ring structure (for example, an adamantyl group, a norbonyl group, an isobornyl group), and may have a chain portion. Specific examples of the (meth) acrylic monomer having a polycyclic structure include bornyl (meth) acrylate, isobornyl (meth) acrylate, 1-adamantyl (meth) acrylate, 2-adamantyl (meth) acrylate, and 2-methyl-2. -Adamantyl (meth) acrylate, 2-ethyl-2-adamantyl (meth) acrylate, norbornyl (meth) acrylate, dicyclopentanyl (meth) acrylate, dicyclopentenyl (meth) acrylate, dicyclopentanyloxyethyl (meth) ) Acrylate, dicyclopentenyloxyethyl (meth) acrylate and the like can be mentioned. The (meth) acrylic monomer having a polycyclic structure preferably has a polycyclic structure having 6 to 12 carbon atoms.

In the (meth) acrylic copolymer having an aromatic group, the aromatic group may be an aryl group or the like, and a chain portion such as an alkylaryl group, an araryl group or an aryloxyalkyl group may be used. You may have. As the (meth) acrylic monomer having an aromatic group constituting the (meth) acrylic copolymer having an aromatic group, a compound in which an aryl group is directly bonded to the (meth) acryloyloxy group, (meth) acryloyloxy Examples thereof include a compound in which an aralkyl group is directly bonded to a group, and a compound in which an alkylaryl group is directly bonded to a (meth) acryloyloxy group. Examples of the (meth) acrylic monomer having an aromatic group include benzyl (meth) acrylate, phenyl (meth) acrylate, and phenoxyethyl (meth) acrylate. The (meth) acrylic monomer having an aromatic group preferably has 6 to 12 carbon atoms in the aromatic group. The carbon number of the aralkyl group is preferably 6 to 12. The alkylaryl group preferably has 6 to 12 carbon atoms.

Examples of the (meth) acrylic monomer having an alkoxy group constituting the (meth) acrylic copolymer having an alkoxy group include (meth) acrylic acid alkoxyalkyl such as methoxyethyl (meth) acrylate and ethoxyethyl (meth) acrylate. Esther can be mentioned.

As the (meth) acrylic monomer having a polyalkylene glycol structural unit constituting the (meth) acrylic copolymer having a polyalkylene glycol structural unit, polyethylene glycol (degree of polymerization = 2 to 10) methyl ether (meth) acrylate , Polyethylene glycol (polymerization degree = 2 to 10) ethyl ether (meth) acrylate, polyethylene glycol (polymerization degree = 2 to 10) propyl ether (meth) acrylate, polyethylene glycol (polymerization degree = 2 to 10) phenyl ether (meth) (Meta) acrylic monomer having polyethylene glycol structural unit such as acrylate; polypropylene glycol (polymerization degree = 2 to 10) methyl ether (meth) acrylate, polypropylene glycol (polymerization degree = 2 to 10) ethyl ether (meth) acrylate, polypropylene Examples thereof include (meth) acrylic monomers having a polypropylene glycol structural unit such as glycol (polymerization degree = 2 to 10) propyl ether (meth) acrylate and polypropylene glycol (polymerization degree = 2 to 10) phenyl ether (meth) acrylate.

Examples of the (meth) acrylic monomer having a tertiary amino group constituting the (meth) acrylic copolymer having a tertiary amino group include 2- (dimethylamino) ethyl (meth) acrylate and N, N-dimethylamino. Examples thereof include propyl (meth) acrylate.

Examples of the (meth) acrylamides constituting the (meth) acrylamide-based copolymer include N, N-dimethyl (meth) acrylamide, N, N-diethyl (meth) acrylamide, N, N-diisopropyl (meth) acrylamide, and the like. (Meta) acrylamide, N-methyl (meth) acrylamide, N-ethyl (meth) acrylamide, N-isopropyl (meth) acrylamide, N-tert-butyl (meth) acrylamide, N-octyl (meth) acrylamide, N-methoxy Methyl (meth) acrylamide, N-ethoxymethyl (meth) acrylamide, N-propoxymethyl (meth) acrylamide, N-butoxymethyl (meth) acrylamide, diacetone acrylamide, N- (meth) acrylmorpholin, etc. Be done. (Meta) acrylamides are (meth) acrylic monomers, but are not included in (meth) acrylate monomers.

Examples of the vinyl monomer having a hydroxy group constituting the vinyl-based polymerization system polymer having a hydroxy group include p-hydroxystyrene and allyl alcohol. Examples of the vinyl monomer having a carboxy group constituting the vinyl polymer having a carboxy group include crotonic acid, maleic acid, itaconic acid, citraconic acid, and cinnamon acid. Examples of the epoxy group-containing vinyl monomer constituting the epoxy group-containing vinyl polymer include 2-allyloxylane, glycidyl vinyl ether, and 3,4-epoxycyclohexylvinyl ether.

Examples of the aromatic vinyl monomer constituting the vinyl polymer having an aromatic group include styrene, α-methylstyrene, 4-methylstyrene, 2-methylstyrene, 3-methylstyrene, 4-methoxystyrene and 2-hydroxy. Examples thereof include methylstyrene and 1-vinylnaphthalene. Examples of the vinyl monomer having a heterocycle constituting the vinyl polymer having a heterocycle include 2-vinylthiophene, N-methyl-2-vinylpyrrole, 2-vinylpyridine, 4-vinylpyridine and the like.

Examples of the vinyl carboxylate constituting the vinyl carboxylate polymer include vinyl acetate, vinyl pivalate, vinyl benzoate and the like. Examples of the vinyl monomer having a tertiary amino group constituting the vinyl polymer having a tertiary amino group include N, N-dimethylallylamine and the like. Examples of the vinyl monomer having a quaternary ammonium base constituting the vinyl polymer having a quaternary ammonium base include N-methacryloylaminoethyl-N, N, N-dimethylbenzylammonium chloride and the like. Examples of the vinyl halide monomer constituting the vinyl polymer having a halogen group include vinyl fluoride, vinylidene fluoride, trifluoroethylene, chlorotrifluoroethylene, tetrafluoroethylene, hexafluoropropylene, tetrafluoropropylene and vinylidene chloride. , Vinyl chloride, 1-chloro-1-fluoroethylene, 1,2-dichloro-1,2-difluoroethylene and the like. Examples of vinyl amides constituting the vinyl amide polymer include N-vinylformamide, N-vinylacetamide, 1-vinyl-2-pyrrolidone, N-vinyl-ε-captolactam and the like. Examples of the α-olefin constituting the α-olefin polymer include 1-hexene, 1-octene, 1-decene and the like. Examples of the diene constituting the diene polymer include butadiene, isoprene, 4-methyl-1,4-hexadiene, 7-methyl-1,6-octadien and the like.

(Other additives)
The pressure-sensitive adhesive composition can be used by blending other additives in addition to the (meth) acrylic copolymer having a carboxy group, the epoxy-based cross-linking agent, and other polymers. Other additives include cross-linking accelerators, cross-linking retarders, silane coupling agents, tackifiers, plasticizers, softeners, release aids, dyes, pigments, dyes, fluorescent whitening agents, and charging. Inhibitors, wetting agents, surfactants, thickeners, fungicides, preservatives, oxygen absorbers, UV absorbers, antioxidants, near-infrared absorbers, water-soluble quenchers, fragrances, metal deactivators, Examples thereof include nucleating agents, alkylating agents, flame retardants, lubricants, processing aids and the like. These are appropriately selected and blended according to the intended use and purpose of use. Further, from the viewpoint of productivity and the like, the pressure-sensitive adhesive composition may be diluted with an organic solvent.

(Silane coupling agent)
The silane coupling agent is not particularly limited, but for example, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, 2 -Epoxy group-containing silane coupling agent such as (3,4 epoxycyclohexyl) ethyltrimethoxysilane; 3-aminopropyltrimethoxysilane, N-2- (aminoethyl) -3-aminopropylmethyldimethoxysilane, 3-tri Amino group-containing silane coupling agents such as ethoxysilyl-N- (1,3-dimethylbutylidene) propylamine, N-phenyl-γ-aminopropyltrimethoxysilane; 3-acryloxypropyltrimethoxysilane, 3-methacry Examples thereof include (meth) acrylic group-containing silane coupling agents such as loxypropyltriethoxysilane; and isocyanate group-containing silane coupling agents such as 3-isocyanuspropyltriethoxysilane.

The content of the silane coupling agent is preferably 1 part by mass or less, more preferably 0.01 part by mass to 1 part by mass, and further preferably 1 part by mass with respect to 100 parts by mass of the (meth) acrylic copolymer having a carboxy group. It is 0.02 part by mass to 0.6 part by mass. By adjusting the content of the silane coupling agent to the above range, it is possible to increase the water resistance at the interface when the pressure-sensitive adhesive layer is applied to a hydrophilic adherend such as glass.

(Adhesive)
The tackifier is not particularly limited, and examples thereof include a rosin-based tackifier resin, a terpene-based tackifier resin, a phenol-based tackifier resin, and a hydrocarbon-based tackifier resin. Examples of the rosin-based tackifier resin include unmodified rosins (raw rosins) such as gum rosin, wood rosin, and tall oil rosin, and modified rosins obtained by polymerizing, disproportionating, or hydrogenating these unmodified rosins. Polymerized rosins, stabilized rosins, disproportionated rosins, fully hydrogenated rosins, partially hydrogenated rosins, other chemically modified rosins, etc.), as well as various rosin derivatives and the like.

As the rosin derivative, for example, a rosin phenol-based resin obtained by adding phenol to rosins (unmodified rosin, modified rosin, various rosin derivatives, etc.) with an acid catalyst and thermally polymerizing the rosin derivative; ester of the unmodified rosin with alcohols. Ester compounds of modified rosin (unmodified rosin ester) and ester compounds of modified rosin in which modified rosin is esterified with alcohols (polymerized rosin ester, stabilized rosin ester, disproportionated rosin ester, fully hydrogenated rosin ester, Resin ester-based resins such as partially hydrogenated rosin esters); unsaturated fatty acid-modified rosin-based resins in which unmodified rosins and modified rosins are modified with unsaturated fatty acids; unsaturated fatty acid modifications in which rosin ester-based resins are modified with unsaturated fatty acids. Rosin ester-based resin; unmodified rosin, modified rosin, unsaturated fatty acid-modified rosin-based resin, unsaturated fatty acid-modified rosin ester-based resin, carboxy group-reduced rosin alcohol-based resin; unmodified rosin, modified rosin, various rosin derivatives Examples thereof include metal salts of rosin-based resins (particularly rosin ester-based resins).

Examples of the terpene-based tackifier resin include terpene-based resins such as α-pinene polymer, β-pinene polymer, and dipentene polymer, and modification of these terpene-based resins (phenol modification, aromatic modification, hydrogenation modification, etc.). Examples thereof include modified terpene-based resins (for example, terpene phenol-based resins, styrene-modified terpene-based resins, aromatic-modified terpene-based resins, hydrogenated terpene-based resins) that have been modified by hydrocarbons and the like.
Examples of the phenol-based tackifier resin include a condensate of various phenols (eg, phenol, m-cresol, 3,5-xylenol, p-alkylphenol, resorcin) and formaldehyde (eg, alkylphenol-based resin, xyleneformaldehyde-based resin). (Resin), resole obtained by addition-reacting the phenols and formaldehyde with an alkali catalyst, novolak obtained by subjecting the phenols and formaldehyde to a condensation reaction with an acid catalyst, and the like.

Examples of the hydrocarbon-based tackifier resin (petroleum-based tackifier resin) include aliphatic hydrocarbon resins [olefins having 4 to 5 carbon atoms and dienes (olefins such as butene-1, isobutylene, and pentene-1; butadiene, Polymers of aliphatic hydrocarbons such as 1,3-pentadiene and diene such as isoprene)], aliphatic cyclic hydrocarbon resins [so-called "C4 petroleum distillate" and "C5 petroleum distillate" are cyclized. Alicyclic hydrocarbon-based resins that have been embodied and then polymerized, polymers of cyclic diene compounds (cyclopentadiene, dicyclopentadiene, etilidennorbornene, dipentene, etc.) or their hydrogenated additives, the following aromatic hydrocarbon resins, and Alicyclic hydrocarbon-based resin obtained by hydrogenating the aromatic ring of an aliphatic / aromatic petroleum resin], aromatic hydrocarbon resin [vinyl group-containing aromatic hydrocarbon having 8 to 10 carbon atoms (styrene) , Vinyl toluene, α-methylstyrene, inden, methylinden, etc.)], aliphatic / aromatic petroleum resins (styrene-olefin copolymers, etc.), aliphatic / alicyclic petroleum resins, Examples thereof include hydrogenated hydrocarbon resins, kumaron-based resins, and kumaron-inden-based resins.

The content of the tackifier is preferably 5 parts by mass to 60 parts by mass with respect to 100 parts by mass of the (meth) acrylic copolymer having a carboxy group. By setting the content of the tackifier within the above range, the adhesion to the multilayer printed wiring board is improved. In addition, the adhesion to the base film 12 is also improved.

The pressure-sensitive adhesive layer 14 has a peeling force against a copper plate at 23 ° C. of 0.3 N / 25 mm or more and 20 N / 25 mm or less. When the peeling force is 0.3 N / 25 mm or more, the adhesion to the multilayer printed wiring board is ensured. From this viewpoint, the peeling force is more preferably 1.0 N / 25 mm or more, still more preferably 2.0 N / 25 mm or more. On the other hand, when the peeling force is 20 or less, the adhesive residue when peeled from the multilayer printed wiring board is suppressed. From this viewpoint, the peeling force is more preferably 16 N / 25 mm or less, still more preferably 10 N / 25 mm or less.

The pressure-sensitive adhesive layer 14 preferably has a storage elastic modulus at 23 ° C. of 0.8 × 10 ⁴ Pa or more and 40 × 10 ⁴ Pa or less. When the storage elastic modulus is 0.8 × 10 ⁴ Pa or more, when the filler of the thermosetting resin is filled, the protrusion of the filler caused by the deformation of the pressure-sensitive adhesive layer 14 due to the pressing pressure of the filler is suppressed. be able to. From this viewpoint, the storage elastic modulus is more preferably 1.0 × 10 ⁴ Pa or more, further preferably 2.0 × 10 ⁴ Pa or more, and particularly preferably 4.0 × 10 ⁴ Pa or more. On the other hand, when the storage elastic modulus is 40 × 10 ⁴ Pa or less, the adhesion to the multilayer printed wiring board is excellent. From this viewpoint, the storage elastic modulus is more preferably 35 × 10 ⁴ Pa or less, further preferably 30 × 10 ⁴ Pa or less, and particularly preferably 25 × 10 ⁴ Pa or less.

The thickness of the pressure-sensitive adhesive layer 14 is preferably 1 μm or more, more preferably 5 μm or more, still more preferably 15 μm or more, and particularly preferably 25 μm or more. When the thickness of the pressure-sensitive adhesive layer 14 is 1 μm or more, the adhesion to the multilayer printed wiring board is improved. Further, it is preferably 100 μm or less, more preferably 50 μm or less, still more preferably 30 μm or less. When the thickness of the pressure-sensitive adhesive layer 14 is 100 μm or less, when a copper or ceramic chip for heat dissipation is arranged in the hole of the multilayer printed wiring board, it is possible to prevent the chip from protruding toward the pressure-sensitive adhesive layer 14.

The pressure-sensitive adhesive layer 14 is formed by directly applying the pressure-sensitive adhesive composition on one surface of the base film 12, and applying the pressure-sensitive adhesive composition on the surface of the release film to form the pressure-sensitive adhesive layer 14. After that, a method of transferring to one surface of the base film 12, the pressure-sensitive adhesive composition is applied on the surface of the first release film to form the pressure-sensitive adhesive layer 14, and then the second release film is attached. Together, it can be formed by a method of peeling off one of the release films and transferring it onto one surface of the base film 12.

For coating the pressure-sensitive adhesive composition, for example, reverse gravure coating method, direct gravure coating method, die coating method, bar coating method, wire bar coating method, roll coating method, spin coating method, dip coating method, spray coating method, It can be performed by using various coating methods such as a knife coating method and a kiss coating method, and various printing methods such as an inkjet method, offset printing, screen printing, and flexographic printing.

The drying and curing steps are not particularly limited as long as the solvent and the like used in the coating liquid can be removed and cured, but the drying and curing steps are preferably performed at a temperature of 60 to 150 ° C. for about 20 seconds to 300 seconds. In particular, the drying temperature is preferably 100 to 130 ° C.

FIG. 2 shows a process diagram of a hole filling process in which a filler of a thermosetting resin is filled in a hole of a multilayer printed wiring board using an adhesive tape 10.

As shown in FIG. 2A, the multilayer printed wiring board 20 is formed with a plurality of through holes 22 such as through holes. A screen 24 for screen printing is arranged on the upper surface of the multilayer printed wiring board 20. An adhesive tape 10 is attached to the lower surface of the multilayer printed wiring board 20 via the adhesive layer 14. As a result, the through hole 22 of the multilayer printed wiring board 20 is a bottomed hole. In this state, as shown in FIG. 2B, the thermosetting resin filler 26 is filled from above the screen 24 using the squeegee 28. At this time, it is preferable to fill under reduced pressure conditions. Next, as shown in FIG. 2C, after removing the screen 24, the temperature is raised to a predetermined temperature to cure the filler 26 of the thermosetting resin. Next, as shown in FIG. 2D, the adhesive tape 10 attached to the lower surface of the multilayer printed wiring board 20 is peeled off. Next, as shown in FIG. 2 (e), the filler 26 protruding from the upper surface of the through hole 22 is polished on the upper surface of the multilayer printed wiring board 20 with a polishing roll 30. As a result, as shown in FIG. 2 (f), the multilayer printed wiring board 20 in which the through hole 22 is filled with the filler 26 is obtained.

According to the adhesive tape 10 having the above configuration, leakage of the filler that fills the holes can be suppressed, peeling can be easily performed without adhesive residue, and discoloration of the conductor circuit can be suppressed.

Although the embodiments of the present invention have been described above, the present invention is not limited to the above embodiments, and various modifications can be made without departing from the spirit of the present invention.

Hereinafter, the present invention will be described in detail with reference to Examples and Comparative Examples.

(Example 1)
<Preparation of adhesive composition>
2.8% by mass of the epoxy-based cross-linking agent <1> with respect to 100 parts by mass of the acrylic-based copolymer <1> (solid content of "TERPLUS 200-007" manufactured by Otsuka Chemical Co., Ltd.), which is a carboxy group-containing acrylic-based copolymer. A pressure-sensitive adhesive composition was prepared by adding 6.8 parts by mass of an epoxy-based cross-linking agent <2> and adding butyl acetate so that the solid content concentration was 25% by mass. The ratio (b / a) of the molar amount (a) of the carboxy group of the carboxy group-containing acrylic copolymer to the molar amount (b) of the epoxy group of the epoxy-based cross-linking agent was 0.9.

<Making adhesive tape>
Using a baker-type film applicator, apply the pressure-sensitive adhesive composition to a thickness of 25 μm on one surface of a polyethylene terephthalate (PET) film (“RM65” manufactured by Toray, thickness 75 μm), and 2 at 120 ° C. After heating for a minute, the release surface of the release film (“HY-S10” manufactured by Higashiyama Film, silicone-based PET release film, thickness 25 μm) was attached to the surface of the pressure-sensitive adhesive composition not covered with the PET film. After that, it was cured at 40 ° C. for 3 days to prepare an adhesive tape.

(Examples 2 to 7, Comparative Examples 1 to 6)
In the preparation of the pressure-sensitive adhesive composition, the blended compositions shown in Table 1 were used, and the prepared pressure-sensitive adhesive compositions were used to prepare adhesive tapes.

The materials used are as follows.
Acrylic copolymer <1>: Acrylic copolymer containing a carboxy group (solid substance of "TERPLUS200-007" manufactured by Otsuka Chemical Co., Ltd.), acid value 23.3 mg / KOH
-Acrylic copolymer <2>: Acrylic copolymer containing a carboxy group (solid substance of "LKG-1202A" manufactured by Fujikura Kasei Co., Ltd.), acid value 7.8 mg / KOH
-Acrylic copolymer <3>: Acrylic copolymer containing a carboxy group (solid substance of "LKG-1201A" manufactured by Fujikura Kasei Co., Ltd.), acid value 58 mg / KOH
-Acrylic copolymer <4>: Acrylic copolymer containing a hydroxyl group (solid substance of "TERPLUS N5505" manufactured by Otsuka Chemical Co., Ltd.), hydroxyl value 19.4 mg / KOH
-Epoxy-based cross-linking agent <1>: "TETRAD-C" manufactured by Mitsubishi Gas Chemical Company (liquid at room temperature)
-Epoxy-based cross-linking agent <2>: "JER1002" manufactured by Mitsubishi Chemical (softening point 78 ° C)
-Isocyanate-based cross-linking agent <1>: Asahi Kasei "Duranate TPA-100" (isocyanurate form of hexamethylene diisocyanate)
-Adhesive-imparting agent <1>: Terpene phenol resin (Yasuhara Chemical's "YS Polystar N125")

The storage elastic modulus, thickness, and peeling force of the adhesive layer of the produced adhesive tape with respect to the copper plate were determined. In addition, each evaluation (discoloration of the copper plate, adhesive residue, resin leakage) was performed using the prepared adhesive tape.

(Storage modulus)
The adhesive layer of the produced adhesive sheet was laminated by laminating using a hand roller, and a laminated body having a thickness of 0.5 mm was used as a measurement sample. Measurement sample using a viscoelasticity measuring device (TA instrument "Discovery HR-2") in an environment of 23 ° C. and 50% RH, shear mode, geometry: φ8 mm parallel plate, frequency: 1 Hz, strain: 1%. The shear storage elastic modulus of was measured.

(thickness)
Adhesive tape is measured by measuring the total thickness of the entire adhesive tape using a thickness measuring machine (manufactured by Tester Sangyo, "TH-104"), and the thickness of the base film and the release film is removed from this total thickness. The thickness of the agent layer was determined.

(Peeling force against copper plate)
After cutting the produced adhesive tape to a size of 25 mm in width and 150 mm in length and peeling off the release film, a hand roller is placed on an oxygen-free copper plate (“C1020P” manufactured by Engineering Test Service, thickness 1.5 mm, 50 mm × 150 mm). Was crimped using. The obtained peeling force test sample was allowed to stand at 23 ° C. for 1 hour, and then the initial peeling force with respect to the copper plate was measured by a 180 ° peeling test. Further, the obtained peeling force test sample was heated in a constant temperature bath at a temperature of 150 ° C. for 1 hour, taken out from the constant temperature bath, allowed to stand at 23 ° C. for 1 hour, and then peeled off after heating to a copper plate by a 180 ° peeling test. The force was measured. The 180 ° peeling test was carried out using a precision universal testing machine (“AUTOGRAPH AGS-1kNX, 50N load cell” manufactured by Shimadzu Corporation) at a tensile speed of 0.3 m / min and a peeling angle of 180 °.

(Discoloration of copper plate)
The surface of the oxygen-free copper plate after the adhesive tape was peeled off was visually observed by measuring the peeling force after heating, and the discoloration of the copper plate was evaluated. The case where there was no difference in the color of the copper plate between the part where the adhesive tape was affixed and the part where the adhesive tape was not affixed was marked with "○", and the case where there was a difference in the color of the copper plate was marked with "x".

(Remaining glue)
The produced adhesive tape was cut to a size of 25 mm in width and 150 mm in length, and after the release film was peeled off, an oxygen-free copper plate (manufactured by Engineering Test Service, "C1020P") with a perforated oval hole of φ5 x 25 mm. It was bonded to the entire surface of one surface (thickness 1.5 mm, 50 mm × 150 mm) to form a bottomed hole, and allowed to stand for 1 hour in an environment of 23 ° C. Next, a thermosetting resin filler (“PHP-900 IR-6P” manufactured by Sanei Chemical Co., Ltd., epoxy resin) was filled in the formed bottomed holes using a squeegee, and then at a temperature of 110 ° C. using a constant temperature bath. The thermosetting resin filler was cured by heating for 1 hour and further heating at a temperature of 150 ° C. for 30 minutes. After cooling the evaluation sample taken out from the constant temperature bath to room temperature, the adhesive tape attached was peeled off, and the surface of the filler to which the adhesive tape was attached and the surface of the copper plate were visually observed to check for adhesive residue. ..
(Remaining resin glue)
The case where there was no adhesive residue on the surface of the filler and the resin and adhesive tape were not damaged was marked with "○", and the case where there was glue residue or the resin and adhesive tape were damaged was marked with "x".
(Remaining glue on copper plate)
"○" indicates that there is no adhesive residue on the surface of the copper plate, "△" indicates that there is adhesive residue on a part of the surface of the copper plate, but there is no problem in practical use, and "△" indicates that there is adhesive residue on the entire surface of the copper plate. It was set as "x".

(Resin leak)
In the above evaluation of adhesive residue, the surface of the copper plate from which the adhesive tape was peeled off was observed at a magnification of 100 times with a microscope (manufactured by KEYENCE, VHX-1000) to evaluate resin leakage. The one in which the resin oozes out on the copper plate is marked with "x", and the one in which the resin does not ooze out on the copper plate is marked with "○".

From Examples 1 to 7 and Comparative Examples 1 to 6, the pressure-sensitive adhesive layer of the pressure-sensitive adhesive tape is composed of a pressure-sensitive adhesive composition containing a (meth) acrylic copolymer having a carboxy group and an epoxy-based cross-linking agent, and is carboxy. The acid value of the (meth) acrylic copolymer having a group is 4.0 mg / KOH or more and 40 mg / KOH or less, and the molar amount of the carboxy group of the (meth) acrylic copolymer having a carboxy group (a). The ratio (b / a) of the adhesive layer to the molar amount (b) of the epoxy group of the epoxy-based cross-linking agent is 0.3 or more and 1.1 or less, and the peeling force of the pressure-sensitive adhesive layer on the copper plate at 23 ° C. is 0. When it is 3N / 25mm or more and 20N / 25mm or less, it is possible to suppress leakage of the filler that fills the holes when the filler of the thermosetting resin is filled with holes, and the adhesive tape can be easily peeled off without adhesive residue. It can be seen that the discoloration of the conductor circuit can be suppressed.

In Comparative Example 1 and Comparative Example 2, since the acid value of the acrylic copolymer exceeded 40 mg / KOH, the pressure-sensitive adhesive layer reacted with the thermosetting resin and adhered firmly, and adhesive residue was generated. Further, in Comparative Example 1, it was difficult to easily peel off from the copper plate because the peeling force after heating was excessively increased. In Comparative Example 3, since the molar ratio (b / a) was less than 0.3, the pressure-sensitive adhesive layer reacted with the thermosetting resin and adhered firmly, and adhesive residue was generated. In Comparative Example 4, since the molar ratio (b / a) exceeded 1.1, the pressure-sensitive adhesive layer reacted with the thermosetting resin and adhered firmly, and adhesive residue was generated. In addition, adhesive residue was generated on the copper plate. In Comparative Example 5, since the adhesive force to the copper plate at 23 ° C. was less than 0.3 N / 25 mm, resin leakage occurred. In Comparative Example 6, since the acrylic copolymer was a hydroxyl group-hydroxyl group-containing acrylic copolymer and the cross-linking agent was an isocyanate-based copolymer, the copper plate was oxidized and discolored. Further, since the adhesive force to the copper plate at 23 ° C. was less than 0.3 N / 25 mm, resin leakage occurred.

10 Adhesive tape 12 Base film 14 Adhesive layer

Claims (3)

An adhesive tape used in the process of filling the holes in a multi-layer printed wiring board with resin.
It has a base film and an adhesive layer formed on the base film.
The pressure-sensitive adhesive layer is composed of a pressure-sensitive adhesive composition containing a (meth) acrylic copolymer having a carboxy group and an epoxy-based cross-linking agent.
The acid value of the (meth) acrylic copolymer having the above-mentioned carboxy group is 4.0 mg / KOH or more and 40 mg / KOH or less.
The ratio (b / a) of the molar amount (a) of the carboxy group of the (meth) acrylic copolymer having a carboxy group to the molar amount (b) of the epoxy group of the epoxy-based cross-linking agent is 0.3. More than 1.1 or less,
An adhesive tape having an adhesive layer having a peeling force against a copper plate at 23 ° C. of 0.3 N / 25 mm or more and 20 N / 25 mm or less. The adhesive tape according to claim 1, wherein the pressure-sensitive adhesive layer has a storage elastic modulus of 0.8 × 10 ⁴ Pa or more and 40 × 10 ⁴ Pa or less at 23 ° C. The adhesive tape according to claim 1 or 2, wherein the base film contains at least one of polyethylene terephthalate, polyethylene naphthalate, polyimide, polymethyl methacrylate, polycarbonate, polyamide, and polyphenylene sulfide.

Images