JP2006232985A - Non-halogen adhesive composition, and coverlay film and adhesive sheet obtained using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a non-halogen adhesive composition giving a cured product excellent in flame retardancy, migration property, glass transition temperature, soldering heat resistance and processability, and a coverlay film and an adhesive sheet each having an adhesive layer comprised of the composition. <P>SOLUTION: The adhesive composition comprises (A) a phenoxy resin having a molecular weight of at least 10,000, a glass transition temperature of 40°C or higher and bearing epoxy groups on the both ends of the molecular chain, (B) a non-halogen epoxy resin, (C) a carboxy group-containing acrylic resin, (D) a curing agent, (E) an inorganic filler, and (F) a phosphorus-containing flame retardant, where the ratio of the component (C) to the total of the components (A)-(D) is 10-60 mass%; the ratio of the components having a glass transition temperature of 30°C or higher in the components (A)-(D) is 40-90 mass%; and the phosphorus content in the whole organic solid component is at least 2.5 mass%. The adhesive sheet and the coverlay film are obtained using the composition. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a non-halogen adhesive composition that is a cured product excellent in flame retardancy, glass transition point, migration property, solder heat resistance and processability, and a coverlay film having an adhesive layer made of the composition And an adhesive sheet.

  In recent years, the electronics field has been remarkably developed, and in particular, electronic devices for communication and consumer use have been reduced in size, weight, density, etc., and demands for these performances have become increasingly sophisticated. In response to such requirements, flexible printed wiring boards are flexible and can withstand repeated bending, so they can be mounted three-dimensionally and densely in a narrow space. As a composite part with a connector function and the like, its application is expanding.

  As the flexible printed wiring board, a coverlay film is used in which a semi-cured adhesive is applied to one side of an electrically insulating base film and a release material is bonded together. This cover lay film is for the purpose of circuit protection and flexibility improvement of a flexible printed wiring board, and, for example, characteristics such as storage stability, adhesion, heat resistance, electrical characteristics, and workability are required.

  In addition, when manufacturing a multilayer flexible printed wiring board by bonding a flexible printed wiring board and a flexible printed wiring board, or when bonding a flexible printed wiring board and a reinforcing plate, an adhesive sheet is used as an adhesive material. Is done. This adhesive sheet is obtained by applying a semi-cured adhesive on one side of the release material, or by applying a semi-cured adhesive on one side of the release material, and further bonding the release material. Properties such as storability, adhesion, heat resistance, electrical properties, and workability are required.

  In recent years, the opportunity to use flexible printed wiring boards at high temperatures and the opportunity to mount components by wire bonding has increased, and this has led to a high glass transition point for adhesives used for flexible printed wiring boards. Is becoming necessary. In addition, with the background of environmental problems, there is a tendency to ban the use of halogen compounds for components mounted on electronic equipment, and bromine compounds that have been used to make flame-retardant substrate materials for flexible printed wiring. The use of has become difficult.

  Therefore, regarding flexible printed wiring boards, materials using an adhesive having a high glass transition point, materials obtained by bonding a metal foil and a heat-resistant resin without using an adhesive, and the like have been proposed. In addition, flame retardant without using a halogen has been made by adding a phosphorus flame retardant instead of a bromine compound as a flame retardant to an adhesive to make it flame retardant. On the other hand, as for the coverlay film and the adhesive sheet, those using an adhesive having a high glass transition point and a phosphorus flame retardant have been proposed from the viewpoints of processability and storage stability.

  Specific examples thereof include, for example, an adhesive composition composed of a thermoplastic resin, a phosphorus-containing phenoxy resin, a phosphorus-containing epoxy resin and a curing agent (Patent Document 1), an epoxy resin, a curing agent, a phenoxy resin, a rubber component, and a curing accelerator. Resin composition comprising an agent (Patent Document 2), resin composition comprising a phenoxy resin, an epoxy resin and a curing agent (Patent Document 3), an adhesive composition comprising an acrylic rubber, a phenoxy resin and a curing agent (Patent Document 4) , Phosphorus-containing phenoxy resin, epoxy resin, carboxyl group-containing butadiene rubber, curing agent, curing accelerator, adhesive composition comprising metal hydroxide and inorganic filler (Patent Document 5), epoxy resin, polyfunctional aralkylphenol, Curing accelerators, elastomers such as carboxyl group-containing acrylonitrile butadiene rubber, phosphazene compounds And adhesive compositions comprising an inorganic filler (Patent Document 6) have been proposed.

  However, in any of the adhesive compositions, the cured product has excellent glass transition point, migration property, solder heat resistance and workability at the same time, and does not contain halogen and is not excellent in flame retardancy.

JP 2003-176470 A JP 2003-286391 A JP 11-279260 A JP 2004136663 A JP 2003-292927 A Japanese Patent Application Laid-Open No. 2004-075748

  Accordingly, the present invention provides a non-halogen adhesive composition that is a cured product excellent in flame retardancy, migration, glass transition point, solder heat resistance and processability, and a cover having an adhesive layer made of the composition. An object is to provide a lay film and an adhesive sheet.

In order to solve the above problems, the present invention provides:
(A) a phenoxy resin having an epoxy group at both ends of a molecular chain, having a weight average molecular weight of 10,000 or more and a glass transition point of 40 ° C. or more;
(B) a non-halogen epoxy resin other than the component (A),
(C) carboxyl group-containing acrylic resin,
(D) a curing agent,
(E) An inorganic filler, and (F) a non-halogen adhesive composition comprising a phosphorus-based flame retardant having a melting point of 80 ° C. or higher, and the total of the components (A) to (D) The proportion of the component (C) is 10 to 60% by mass, the proportion of the component having a glass transition point of 30 ° C. or higher among the components (A) to (D) is 40 to 90% by mass, and the total organic The above composition, wherein the phosphorus content in the solid component is 2.5% by mass or more,
I will provide a.

  Secondly, the present invention provides an adhesive sheet having an adhesive layer made of the adhesive composition and a release material layer covering the adhesive layer.

  Thirdly, the present invention provides a coverlay film having an electrically insulating film layer and an adhesive layer made of the adhesive composition provided on the film layer.

  The non-halogen adhesive composition of the present invention forms a cured product or an adhesive layer excellent in flame retardancy, migration property, glass transition point, solder heat resistance and processability. Furthermore, the composition is environmentally friendly because it does not contain halogen. Therefore, since the coverlay film and adhesive sheet having this adhesive layer also have excellent characteristics, they can be suitably used and applied particularly in the field of flexible printed wiring boards and the like.

  Hereinafter, the present invention will be described in detail.

  In addition, in this specification, the glass transition point (Tg) of (A)-(F) component and the component contained depending on the case is based on DSC method, The glass transition point of the hardened | cured material of adhesive composition is This is based on the DMA method.

<Adhesive composition>
The adhesive composition of the present invention is a thermosetting adhesive composition, and is used, for example, for the production of coverlay films and adhesive sheets.

  The adhesive composition of the present invention comprises the components (A) to (F). In the present specification, the “organic solid component” is a non-volatile organic component constituting the adhesive composition of the present invention.

  Hereinafter, each component contained in the composition will be described in detail.

[(A) Phenoxy resin]
The phenoxy resin as component (A) has an epoxy group at both ends of the molecular chain, a weight average molecular weight of 10,000 or more, and a glass transition point of 40 ° C. or more.

  The weight average molecular weight is preferably 20,000 to 100,000, more preferably 30,000 to 80,000. When the molecular weight is less than 10,000, the cured product may be inferior in heat resistance and flexibility, and in the case of exceeding 100,000, the cured product may be inferior in stability. In particular, the solubility of this component in a solvent may be reduced. In addition, this molecular weight is a polystyrene conversion value by GPC.

  The glass transition point is preferably 50 to 200 ° C, more preferably 60 to 160 ° C. When the glass transition point is less than 40 ° C., the glass transition point of the cured product may be low, and when it exceeds 200 ° C., the peel strength of the cured product may be inferior.

  Further, when the phenoxy resin does not have an epoxy group at both ends of the molecular chain, the solvent resistance of the cured product, the solder heat resistance, particularly the solder heat resistance during moisture absorption is lowered.

  Examples of the phenoxy resin of this component include bisphenol A type phenoxy resin, bisphenol F type phenoxy resin, copolymerized phenoxy resin of bisphenol A type and bisphenol F type, and the like. As the commercially available product, for example, Epicoat 4256, Epicoat 4275, Epicoat 1256 (manufactured by Japan Epoxy Resin Co., Ltd.) and the like are listed under the trade name.

  (A) The phenoxy resin of a component may be used individually by 1 type, or may use 2 or more types together.

[(B) Non-halogen epoxy resin]
The non-halogen epoxy resin as the component (B) does not contain halogen in the molecular skeleton and has two or more epoxy groups in one molecule, and is other than the component (A). Specifically, it is usually a non-halogen epoxy resin having a weight average molecular weight of less than 10,000, and may be modified with, for example, silicone, urethane, polyimide, polyamide, etc. A sulfur atom, a nitrogen atom, etc. may be included.

  This non-halogen epoxy resin preferably has 2 to 15 epoxy groups in one molecule, and more preferably 2 to 10 epoxy groups. In particular, an epoxy resin having two epoxy groups in one molecule is more excellent in flexibility and peel strength of a cured product, and an epoxy resin having three or more epoxy groups in one molecule is a cured product. The heat resistance and glass transition point of the glass are more excellent.

  Examples of the epoxy resin having two epoxy groups in one molecule include bisphenol A type epoxy resin, bisphenol F type epoxy resin, stilbene type epoxy resin, biphenyl type epoxy resin, and alicyclic epoxy resin. . As the commercial item, for example, Epicoat 828, 871, 1001 (manufactured by Japan Epoxy Resin), Sumiepoxy ELA115, 127 (manufactured by Sumitomo Chemical Co., Ltd.) and the like are listed as trade names.

  Examples of the epoxy resin having three or more epoxy groups in one molecule include phenol novolac type epoxy resin, cresol novolac type epoxy resin, glycidylamine type epoxy resin, polyphenylmethane type epoxy resin and the like. Examples of such commercially available products include Epicoat 604 (manufactured by Japan Epoxy Resin), Sumiepoxy ESCN195X, ELM120 (manufactured by Sumitomo Chemical Co., Ltd.), EOCN103S, EPPN502H (manufactured by Nippon Kayaku Co., Ltd.), and the like.

  (B) The compounding quantity of a component is 20-200 mass parts normally with respect to 100 mass parts of said (A) component, Preferably it is 30-180 mass parts, More preferably, it is 40-150 mass parts. When this blending amount satisfies such a range, the cured product has better solvent resistance, solder heat resistance, heat resistance, glass transition point, flame retardancy, and peel strength, and further facilitates flow control.

  The non-halogen epoxy resin of this component may be used alone or in combination of two or more.

[(C) Carboxyl group-containing (meth) acrylic resin]
The (C) component carboxyl group-containing (meth) acrylic resin has a carboxyl group in the molecular skeleton of the (meth) acrylic resin. Further, the carboxyl group-containing (meth) acrylic resin of this component is a polymer compound having a glass transition point (Tg) of usually less than room temperature (25 ° C.).

  There are usually 50 or more, preferably 100 or more carboxyl groups in one molecule, and may be present at either the molecular chain non-terminal or the molecular chain terminal.

  The carboxyl group content in this component is usually 0.005 to 5% by mass, preferably 0.001 to 1% by mass. When the carboxyl group content satisfies such a range, the reactivity of the composition is improved, so that the cured product has better solvent resistance, solder heat resistance, adhesiveness, and electrical properties.

  As for the weight average molecular weight of the carboxyl group-containing (meth) acrylic resin of this component, the measured value by gel permeation chromatography (GPC, standard polystyrene conversion) is preferably 100,000 to 1,000,000, and 200,000 to 700,000. More preferably.

  Examples of the carboxyl group-containing (meth) acrylic resin include (C-1) (meth) acrylic acid ester, (C-2) (meth) acrylonitrile, and (C-3) polymerizable unsaturated double bond. Examples thereof include an acrylic polymer and a methacrylic polymer obtained by copolymerizing three components of the carboxylic acid monomer. The copolymerization of these three components may be a conventional polymerization method, and may be any of ordinary solution polymerization, emulsion polymerization, suspension polymerization, and bulk polymerization.

  Monomer (C-1) (meth) acrylic acid ester imparts flexibility to the cured product. Examples of (meth) acrylic acid esters include acrylic acid esters and methacrylic acid esters. Specific examples of the acrylate ester include methyl acrylate, ethyl acrylate, -n-butyl acrylate, isobutyl acrylate, isopentyl acrylate, and the like. Specific examples of the methacrylic acid ester include methyl methacrylate, ethyl methacrylate, -n-butyl methacrylate, isobutyl methacrylate, isopentyl methacrylate and the like. Among these, acrylic acid alkyl esters and methacrylic acid alkyl esters having an alkyl group with 1 to 12, particularly 1 to 4 carbon atoms are preferred.

  Although the compounding quantity of a monomer (C-1) is not specifically limited, It is 50-80 mass% normally with respect to the sum total of a monomer (C-1)-(C-3), Preferably it is 55-75 mass. %.

  A monomer (C-1) may be used individually by 1 type, or may use 2 or more types together.

  Monomer (C-2) (meth) acrylonitrile imparts heat resistance, adhesion and chemical resistance to the cured product. (Meth) acrylonitrile includes acrylonitrile and methacrylonitrile.

  Although the compounding quantity of a monomer (C-2) is not specifically limited, It is 15-45 mass% normally with respect to the sum total of monomer (C-1)-(C-3), Preferably 20-40 mass %.

  A monomer (C-2) may be used individually by 1 type, or may use 2 types together.

  The carboxylic acid monomer having a polymerizable unsaturated double bond of the monomer (C-3) imparts adhesiveness to the cured product and at the same time serves as a crosslinking point when the composition is heated. The carboxylic acid monomer having a polymerizable unsaturated double bond may be any carboxylic acid having a copolymerizable aliphatic unsaturated bond, and specific examples thereof include acrylic acid, methacrylic acid, crotonic acid, maleic acid, Examples thereof include fumaric acid and itaconic acid.

  Although the compounding quantity of a monomer (C-3) is not specifically limited, It is 2-10 mass% normally with respect to the sum total of monomer (C-1)-(C-3), Preferably it is 4-8 mass %.

  A monomer (C-3) may be used individually by 1 type, or may use 2 types together.

  The acrylic polymer and the methacrylic polymer may be a copolymer composed only of the monomers (C-1) to (C-3), or may contain other monomers having a polymerizable unsaturated double bond. It may be a polymer.

  (C) The compounding quantity of a component needs to be the quantity used as 10-60 mass% with respect to the sum total of (A)-(D) component, Preferably the quantity used as 20-50 mass%, The amount is more preferably 25 to 50% by mass. When the blending amount is less than 10% by mass, the adhesive layer (cured product) is likely to be broken or chipped when processing the coverlay film and the adhesive sheet, resulting in 60% by mass. When the amount is exceeded, the glass transition point of the cured product may be lowered.

  In a preferred embodiment, since the peel strength, flexibility, heat resistance, flame retardancy, and glass transition point of the cured product become better, the blending amount of the component (C) is in addition to the above range, ( Preferably it is 20-200 mass parts with respect to 100 mass parts of component A), More preferably, it is 30-150 mass parts, More preferably, it is 40-120 mass parts.

  The (C) component carboxyl group-containing (meth) acrylic resin may be used alone or in combination of two or more.

[(D) Curing agent]
(D) The hardening | curing agent which is a component may be a well-known thing used as a hardening | curing agent of an epoxy resin. Examples of the curing agent include aliphatic amine curing agents such as diethylenetriamine, tetraethylenetetramine, and tetraethylenepentamine; alicyclic amine curing agents such as isophoronediamine; and aromatics such as diaminodiphenylmethane, diaminodiphenylsulfone, and phenylenediamine. Group amine curing agents; acid anhydride curing agents such as phthalic anhydride, pyromellitic anhydride, trimellitic anhydride, hexahydrophthalic anhydride; 2-methylimidazole, 2-ethyl-4-methylimidazole, 1-cyanoethyl-2 -Imidazole compounds such as ethyl-4-methylimidazole; Dicyandiamide; Octylates such as tin octylate and zinc octylate, and the like, preferably aliphatic amine curing agents, aromatic amine curing agents, imidazole compounds , Dicyandiamide Fine octylate, particularly preferably, the aromatic amine curing agent, imidazole compounds and octyl acid salt.

  The blending amount of the component (D) is determined in consideration of the epoxy equivalent of the components (A) and (B), the cured state of the adhesive, the balance of the properties of the cured product, and the like. On the other hand, it is 0.1-50 mass parts normally, Preferably it is 0.5-30 mass parts, More preferably, it is 1-20 mass parts. When this blending amount satisfies such a range, the cured product has better solder heat resistance, solvent resistance, glass transition point, and electrical characteristics.

  (D) The hardening | curing agent of a component may be used individually by 1 type, or may use 2 or more types together.

[(E) inorganic filler]
The inorganic filler as component (E) is a component blended for the purpose of assisting the flame retardancy of the cured product, improving the stability of the peeled state (cohesive peeling of the adhesive), stabilizing the moisture absorption resistance, and the like. . The inorganic filler is not particularly limited as long as it is conventionally used for a coverlay film or an adhesive sheet. Examples of the inorganic filler include metal hydroxides such as aluminum hydroxide and magnesium hydroxide; metal oxides such as aluminum oxide, silicon oxide and molybdenum oxide; boric acid compounds such as zinc borate and magnesium borate. Preferred are metal hydroxides such as aluminum hydroxide and magnesium hydroxide, and boric acid compounds such as zinc borate and magnesium borate, and particularly preferred are aluminum hydroxide, magnesium hydroxide and zinc borate. It is. In order to improve the adhesion and water resistance of these inorganic fillers to the resin matrix, and to improve the heat resistance, moisture absorption resistance, etc. of the cured product, the surface of the inorganic filler is a silane coupling agent or titanate cup. It is preferably hydrophobized with a ring agent or the like.

  The amount of component (E) is usually 5 to 40% by mass, preferably 10 to 35% by mass, more preferably the total of components (A) to (D). The amount is 15 to 30% by mass. When this blending amount satisfies such a range, the cured product has better flame retardancy, peel strength, solder heat resistance, and moisture absorption resistance.

  (E) The inorganic filler of a component may be used individually by 1 type, or may use 2 or more types together.

[(F) Phosphorus flame retardant]
The phosphorus-based flame retardant as component (F) is a flame retardant containing phosphorus in the molecule and has a melting point of 80 ° C. or higher, preferably 100 to 500 ° C. A phosphorus flame retardant having a phosphorus content of preferably 8% by mass or more, more preferably 10 to 30% by mass is used in order to keep the phosphorus content in the total organic solid component within the range described below.

  Specific examples of the phosphorus-based flame retardant include phosphate ester, triphenylphosphine (TPP), red phosphorus, phosphazene compound, phosphate ester amide, and the like, since the cured product has excellent migration properties. Phosphoric ester amide is preferred, and phosphoric ester amide is more preferred.

The phosphazene compound is not particularly limited as long as it does not contain a halogen atom and has a phosphazene structure in the molecule. Here, the phosphazene structure means a structure represented by the formula: —P (R ₂ ) ═N— [wherein R is an organic group]. As such a phosphazene compound, for example, a cyclophosphazene oligomer is preferable from the viewpoint of heat resistance, moisture resistance, flame retardancy, and chemical resistance.

  This cyclophosphazene oligomer has the following general formula:

［式中、Ｘは同一または異なり、水素原子またはハロゲン原子を含まない有機基であり、ｎは３〜10の整数である］
で表されるものであり、その融点は、好ましくは90〜150℃、より好ましくは100〜150℃である。上記一般式中、ｎは好ましくは３〜９、より好ましくは３〜６の整数である。上記一般式中、Ｘで表されるハロゲン原子を含まない有機基としては、例えば、アルコキシ基、フェノキシ基、アミノ基、アリル基等が挙げられる。上記一般式で示されるホスファゼン化合物としては、例えば、商品名で、ＳＰＥ−１００、ＳＰＢ−１００（大塚化学製、シクロホスファゼン系化合物）等が挙げられる。

[Wherein X is the same or different and is an organic group containing no hydrogen atom or halogen atom, and n is an integer of 3 to 10]
The melting point thereof is preferably 90 to 150 ° C, more preferably 100 to 150 ° C. In the above general formula, n is preferably an integer of 3 to 9, more preferably 3 to 6. In the above general formula, examples of the organic group containing no halogen atom represented by X include an alkoxy group, a phenoxy group, an amino group, and an allyl group. Examples of the phosphazene compound represented by the above general formula include SPE-100 and SPB-100 (manufactured by Otsuka Chemical Co., Ltd., cyclophosphazene compounds) under the trade names.

  The phosphoric ester amide is not particularly limited, but an aromatic phosphoric ester amide is preferable since the heat resistance of the cured product is good.

  (F) The compounding quantity of a component is normally 20-50 mass% with respect to all the organic solid components.

  The phosphorus-based flame retardant component (F) may be used alone or in combination of two or more.

[Other conditions]
-Ratio of components having a glass transition point of 30 ° C or higher With respect to the sum of components (A) to (D), the proportion of components having a glass transition point of 30 ° C or higher among the components (A) to (D) is 40. It is necessary to be -90 mass%, Preferably it is 50-80 mass%, More preferably, it is 60-80 mass%. When this ratio is less than 40% by mass, the glass transition point of the cured product may be lowered. When it exceeds 90% by mass, the adhesive layer is used when processing the coverlay film and the adhesive sheet. The (cured product) is likely to be broken or chipped.

-Phosphorus content Furthermore, the phosphorous content rate in all the organic solid components needs to be 2.5 mass% or more, Preferably it is 3.0-6.0 mass%, More preferably, it is 3.5-5.0 mass%. When the phosphorus content is less than 2.5% by mass, the flame retardancy of the cured product may be insufficient. When it exceeds 6.0% by mass, the blending amount of the component (F) is mainly This increases the solder heat resistance and heat resistance of the cured product.

[Other ingredients]
In addition to the components (A) to (F), the following components can be blended as necessary. Each of these other components may be used alone or in combination of two or more.

  Examples of other components include non-halogen flame retardants such as non-bromine flame retardants, coupling agents, antioxidants, and ion adsorbents.

Organic solvent The above components (A) to (F) and components added as necessary may be used in the production of adhesive sheets and coverlay films without solvent, but are dissolved or dispersed in an organic solvent, The composition may be prepared and used as a solution or dispersion (hereinafter simply referred to as “solution”). Examples of the organic solvent include toluene, methanol, ethanol, isopropanol, acetone, dioxolane, methyl ethyl ketone (hereinafter referred to as “MEK”), and preferably toluene, dioxolane, and methyl ethyl ketone.

  The adhesive solution obtained here preferably has a concentration of all organic solid components of 20 to 45% by mass, more preferably 25 to 40% by mass, and particularly preferably 25 to 35% by mass. . When this density | concentration satisfy | fills the range of 20-45 mass%, an adhesive composition will become the thing excellent in coating property, without producing a nonuniformity at the time of coating.

  In the case of mixing the above components, the order is not particularly limited, but can be determined as appropriate in consideration of the solubility of the added components and the viscosity of the resulting adhesive solution. A pot mill, a ball mill, a homogenizer, a super mill, etc. can be used for mixing.

<Coverlay film>
-Structure As a structure of the coverlay film which has an adhesive bond layer which consists of an adhesive composition of this invention, it has an electrically insulating film layer and the adhesive bond layer provided on this film layer. Specifically, for example, a three-layer structure having an electrically insulating film layer, an adhesive layer, and a release material layer can be given. The thickness of the adhesive layer can be selected according to the purpose of use, but is usually 10 to 50 μm, preferably 15 to 35 μm, particularly preferably 15 to 25 μm in a dry state.

  Examples of the electrically insulating film constituting the electrically insulating film layer include polyimide film, PET (polyethylene terephthalate) film, polyester film, polyparabanic acid film, polyether ether ketone film, polyphenylene sulfide film, aramid film; glass fiber, Based on aramid fiber, polyester fiber, etc., epoxy resin as a matrix, polyester resin, diallyl phthalate resin impregnated in this, film or sheet and pasted with copper foil, etc. From the viewpoints of heat resistance, dimensional stability, mechanical properties (elastic modulus, elongation, etc.), a polyimide film, a polyparabanic acid film, and a polyphenylene sulfide film are preferable, and a polyimide film is particularly preferable.

  The thickness of the electrically insulating film layer may be arbitrarily selected depending on the purpose of use, but is usually 12.5 to 75 μm, preferably 12.5 to 50 μm, particularly preferably 12.5 to 25 μm. In addition, in order to improve adhesion to the adhesive layer, clean the film surface, improve dimensional stability, etc., surface treatment such as low-temperature plasma treatment, corona discharge treatment, sandblast treatment, etc. is performed on one or both sides of this film. May be.

  Examples of the release material constituting the release material layer include polyethylene (PE) film, polypropylene (PP) film, polymethylpentene (TPX) film; PE film and PP film with silicone release material; PE resin-coated paper, PP resin Examples thereof include coated paper and TPX resin coated paper. The thickness of the release material may be an appropriate thickness as required, but is preferably 13 to 75 μm for a film and 50 to 200 μm for paper.

-Manufacturing method Next, the case where the organic solvent which is preferable embodiment is used is demonstrated as an example about the manufacturing method of the coverlay film of this invention.

  First, an adhesive solution containing an organic solvent prepared in advance is applied to one side of an electrically insulating film using a reverse roll coater, a comma coater or the like. The adhesive composition is semi-cured by removing the organic solvent in the adhesive composition by heating the film coated with this adhesive composition through an in-line dryer at 40-160 ° C for 2-20 minutes. State. Next, the application surface of the adhesive composition of the film and the release material are pressure-bonded by a heating roll under the conditions of a linear pressure of 0.2 to 20 kg / cm and a temperature of 40 to 120 ° C. to obtain a coverlay film. The release material is peeled off during use. The “semi-cured state” means a state in which the composition is dried or a state in which the curing reaction proceeds in a part thereof.

<Adhesive sheet>
-Structure As a structure of the adhesive sheet which has an adhesive bond layer which consists of an adhesive composition of this invention, it has an adhesive bond layer and the mold release material layer which coat | covers this adhesive bond layer. Specific examples include a two-layer structure having a release material layer and an adhesive layer, or a three-layer structure having a release material layer, an adhesive layer, and a release material layer. The two-layer structure and three-layer structure of the adhesive sheet may be appropriately selected depending on the processing method at the time of manufacturing the flexible printed wiring board. The thickness of the adhesive layer can be selected according to the purpose of use, but is usually 10 to 50 μm, preferably 15 to 35 μm, particularly preferably 15 to 25 μm in a dry state.

  The release material constituting the release material layer is as described in the section of the coverlay film.

〔Production method〕
Next, the case where the organic solvent which is preferable embodiment is used is demonstrated as an example about the manufacturing method of the adhesive sheet of this invention.

  First, an adhesive solution containing an organic solvent prepared in advance is applied to one side of a release material using a reverse roll coater, a comma coater, or the like. The release agent coated with the adhesive composition is passed through an in-line dryer and heat-treated at 40 to 160 ° C. for 2 to 20 minutes to remove the organic solvent in the adhesive composition. It is set as a hardening state and it is set as the adhesive sheet of 2 layer structure. Further, another release material is pressure-bonded to the application surface of the adhesive composition of the adhesive sheet with a heating roll under the conditions of a linear pressure of 0.2 to 20 kg / cm and a temperature of 40 to 120 ° C. To do. The release material is peeled off during use.

  EXAMPLES Hereinafter, although this invention is demonstrated concretely using an Example, this invention is not limited to these Examples. In addition, specifically, the following were used as said (A)-(F) component and another component.

<Adhesive composition components>
(A) Phenoxy resin / Epicoat 4275 (trade name) (made by Japan Epoxy Resin, weight average molecular weight: about 60,000, Tg: about 68 ° C.)
Epicoat 1256 (trade name) (made by Japan Epoxy Resin, weight average molecular weight: about 53,000, Tg: about 95 ° C.)
(B) Non-halogen epoxy resin / Epicoat 604 (trade name) (product of Japan Epoxy Resin, weight average molecular weight: about 500, Tg: less than 30 ° C., 4 epoxy groups in one molecule)
Epicoat 828 (trade name) (made by Japan Epoxy Resin, weight average molecular weight: about 300, Tg: less than 30 ° C., 2 epoxy groups in one molecule)
Epicoat 1001 (trade name) (made by Japan Epoxy Resin, weight average molecular weight: about 1,000, Tg: about 70 ° C., two epoxy groups in one molecule)
(C) Carboxyl group-containing (meth) acrylic resin (meth) acrylic resin A: The mass ratio of butyl acrylate / acrylonitrile / methacrylic acid is 65/32/3, the weight average molecular weight is about 400,000, and the glass transition point Acrylic resin (meth) acrylic resin B having a carboxyl group content of about 0.03% by mass and a mass ratio of butyl acrylate / ethyl acrylate / acrylonitrile / methacrylic acid is 35/30/28/7 An acrylic resin having a weight average molecular weight of about 450,000, a glass transition point of about 14 ° C., and a carboxyl group content of about 0.07% by mass.
(Meth) acrylic resin C: The mass ratio of butyl acrylate / ethyl acrylate / acrylonitrile / methacrylic acid is 30/30/35/5, the weight average molecular weight is about 600,000, and the glass transition point is about 20 ° C. An acrylic resin having a carboxyl group content of about 0.05% by mass.
(D) a curing agent,
・ DDS (4,4′-diaminodiphenylsulfone, Tg: 30 ° C. or higher)
・ Dicyandiamide (Tg: about 200 ℃)
・ 2E4MZ-CN (trade name) (Shikoku Chemicals, Tg: less than 30 ° C)
(E) Inorganic filler H43STE (trade name) (Showa Denko, aluminum hydroxide)
・ Kisuma 5A (trade name) (manufactured by Kyowa Chemical, magnesium hydroxide)
(F) Phosphorus flame retardant SPE100 (trade name) (manufactured by Otsuka Chemical, phosphazene compound, melting point: about 110 ° C., phosphorus content: about 13% by mass)
・ SP703 (trade name) (manufactured by Shikoku Chemicals, melting point: about 180 ° C, phosphorus content: about 10% by mass)
PX200 (trade name) (manufactured by Daihachi Chemical, melting point: about 92 ° C., phosphorus content: about 9% by mass)
(Other)
Nipol 1072B (trade name) (manufactured by Nippon Zeon, carboxyl group-containing acrylonitrile-butadiene rubber, acrylonitrile content: about 27.0 mass%, carboxyl group content: about 0.075 mass%)

<Materials used>
・ Kapton 100H (trade name) (Toray DuPont, polyimide film, thickness: 25μm)
・ Y7TF (trade name) (Made by Lintec, release paper, thickness: approx. 130 μm)
・ PET38X (trade name) (Made by Lintec, release film, thickness: approx. 38μm)
・ HTE (trade name) (Mitsui Metals, electrolytic copper foil)
RAS22S47 (trade name) (manufactured by Shin-Etsu Chemical, flexible printed wiring board, Kapton 50H / adhesive layer thickness: 13 μm / rolled copper foil 1/2 oz)
・ E33 (trade name) (manufactured by Shin-Etsu Chemical, adhesive sheet, adhesive layer thickness: 25 μm)

<Examples 1-8, Comparative Examples 1-4>
For each component of the adhesive composition, the types shown in Table 1 were used in the blending amounts (parts by mass) shown in the same table. First, the component (A), the component (B), and the component (D) were dissolved in MEK, stirred, and mixed to obtain a solution 1 having an organic solid component concentration of 30% by mass. Next, separately (C) component (in Comparative Example 4, instead acrylonitrile-butadiene rubber) was dissolved in a MEK / toluene mixed solution (MEK: toluene = 80: 20 (mass ratio)) to be a 15 mass% solution. After adding component (E) and component (F) to this solution, component (E) was sufficiently dispersed using a ball mill to obtain solution 2. Thereafter, the solution 1 and the solution 2 were mixed and sufficiently stirred to obtain an adhesive solution.

  Next, this adhesive solution was applied on a polyimide film (trade name: Kapton 100H) using a reverse roll coater so that the thickness of the adhesive layer after drying was 25 μm. Thereafter, MEK and toluene were removed under heating and drying conditions at 140 ° C. for 10 minutes, so that the adhesive composition was in a semi-cured state. A release paper (trade name: Y7TF) is pressure-bonded to the adhesive surface of the film with the semi-cured adhesive composition using a roll laminator at a temperature of 70 ° C. and a linear pressure of 2 kg / cm. A film was prepared.

  Moreover, the adhesive sheet was produced by the process similar to preparation of a coverlay film except having changed the polyimide film into the release film (brand name: PET38X).

  About these coverlay films and adhesive sheets, physical properties were evaluated and measured according to the following evaluation and measurement methods. The results are shown in Table 1.

<Evaluation and measurement method>
(Configuration of evaluation sample)
The following sample, which was pressure-bonded while being heated at 160 ° C., 3.0 MPa for 50 minutes, was used as a sample for evaluating peel strength, solder heat resistance, and glass transition point. The release material was peeled off and used for sample preparation.
Sample 1: Adhesive layer of coverlay film prepared in Example and electrolytic copper foil (trade name: HTE) 1 oz. Glossy surface Sample 2: Two sheets of both sides of adhesive sheet prepared in Example Sample of flexible printed wiring board (trade name: RAS22S47) covered with film surface Sample 3: Both surfaces of the adhesive sheet prepared in the example were covered with 2 oz. Glossy surface of electrolytic copper foil (trade name: HTE) thing

(Physical property evaluation / measurement method)
1. Peel strength / Peel strength A: Sample 1 was cut to a width of 10 mm to produce test piece 1, and electrolytic copper foil (trade name: HTE) was placed in the direction of 90 degrees under the condition of 25 ° C. The minimum value of the load when peeling 50 mm continuously at a speed of 50 mm / min was measured and taken as the peel strength.
-Peel strength B: Sample 2 was cut to a width of 10 mm to produce test piece 2, and a flexible printed wiring board (trade name: RAS22S47) was oriented at 90 degrees under the condition of 25 ° C. The minimum value of the load when peeling 50 mm continuously at a speed of 50 mm / min was measured and taken as the peel strength.

2. Solder heat resistance / solder heat resistance A: Sample 1 was cut into 25 mm square to prepare test piece 3, which was dried at 80 ° C. for 10 minutes and then floated on a solder bath for 30 seconds. Then, the external appearance of this test piece 3 was confirmed visually, and the presence or absence of a swelling, peeling, etc. was investigated. This operation was repeated while changing the temperature of the solder bath, and the maximum temperature at which the sample did not swell or peel off was measured.
Solder heat resistance B: Sample 1 was cut into a 25 mm square to prepare test piece 4, which was left at 40 ° C. and 90% RH for 1 hour, and then floated on a solder bath for 30 seconds. Thereafter, the maximum temperature was measured in the same manner as the solder heat resistance A.
Solder heat resistance C: The maximum temperature was measured in the same manner as the solder heat resistance A, except that the test piece 5 was prepared by cutting the sample 2 into 25 mm square.

3. Glass transition point (Tg)
The electrolytic copper foil (trade name: HTE) of Sample 3 was removed with a ferric chloride aqueous solution to prepare an adhesive sheet, and this adhesive sheet was cut to prepare a test piece 6 (10 mm × 50 mm). Using the test piece 6, the Tg of the adhesive was measured using a viscoelasticity measuring device (trade name: RSAIII, manufactured by Rheometric Co., Ltd.) with the temperature raising condition set to 5 ° C./min. Tg was a peak (maximum value) of tan δ.

4). Workability After removing the release material from the adhesive sheet produced in the example, the operation of folding the adhesive sheet in the 180 degree direction and opening it was repeated five times, and the adhesive layer was confirmed to be broken or chipped visually. When the adhesive layer is not broken or chipped, the processability is evaluated as good and shown as A, and when the adhesive layer is broken or chipped, the processability is evaluated as poor. B.

5). 1 is a plan view of a comb circuit for evaluation of migration formed by etching a copper foil portion of a flexible printed wiring board (trade name: RAS22S47, copper foil / adhesive layer / polyimide film laminate). It is. The comb circuit on the substrate includes a conductor 1 made of parallel copper foil and voltage application electrodes 2 provided at both ends thereof. Further, the adhesive layer 3 is exposed on the substrate by copper foil etching. In addition, the width | variety of the conductor (copper foil) 1 is 250 micrometers, and the distance between adjacent conductors (between lines) is 60 micrometers.
First, a flexible printed wiring board (trade name: RAS22S47) was cut into 120 mm × 120 mm to obtain a square flexible printed wiring board. The copper foil portion of the obtained flexible printed wiring board was etched by a conventional method to form a comb circuit for evaluating migration properties shown in FIG. Next, this circuit was cut into a shape (60 mm × 20 mm) shown in FIG.
The coverlay film prepared in the previous embodiment (with release paper peeled off) is pressed against the entire structure excluding the voltage application electrode 2 of this comb circuit while heating at 160 ° C., 3.0 MPa for 50 minutes. Then, a coated body was prepared by coating. A 2 mm thick glass epoxy board is heated and bonded to both sides of this covering body under conditions of 160 ° C., 3.0 MPa, 50 minutes via an adhesive sheet (trade name: E33) to obtain a substrate for evaluating migration properties. It was. A voltage of 50 V was applied to this substrate under the conditions of 85 ° C. and 85% RH over 240 hours, and the subsequent electric resistance value was measured. This measured value (MΩ) was evaluated as an index of migration.

6). Halogen Content The halogen content of the adhesive part of the adhesive sheet produced in the example was measured according to the method described in JPCA-ES-001 (JPCA standard, Japan Printed Circuit Industry Association). A case where the halogen content was 0.09% by mass or less was evaluated as being halogen-free and indicated as A, and a case where the halogen content was over 0.09% by mass was evaluated as being non-halogen-free and indicated as B.

7). Flame retardancy The coverlay film produced in the example was cut into 50 mm × 200 mm to produce a flame retardant evaluation sample. The sample was evaluated for flame retardancy according to the UL94VTM-0 standard. When the flame retardancy satisfied the VTM-0 standard, it was evaluated as good and indicated as A, and when it did not meet the VTM-0 standard, it was evaluated as defective and indicated as B.

It is a top view of the comb circuit for migration property evaluation formed by etching the copper foil part of the board | substrate for flexible printed wirings (brand name: RAS22S47).

Explanation of symbols

1 Conductor (copper foil)
2 Electrode for voltage application 3 Adhesive layer

Claims (4)

(A) a phenoxy resin having an epoxy group at both ends of a molecular chain, having a weight average molecular weight of 10,000 or more and a glass transition point of 40 ° C. or more;
(B) a non-halogen epoxy resin other than the component (A),
(C) carboxyl group-containing acrylic resin,
(D) a curing agent,
(E) An inorganic filler, and (F) a non-halogen adhesive composition comprising a phosphorus-based flame retardant having a melting point of 80 ° C. or higher, and the total of the components (A) to (D) The proportion of the component (C) is 10 to 60% by mass, the proportion of the component having a glass transition point of 30 ° C. or higher among the components (A) to (D) is 40 to 90% by mass, and the total organic The above composition, wherein the phosphorus content in the solid component is 2.5% by mass or more.   The component (B) is 20 to 200 parts by mass with respect to 100 parts by mass of the component (A), the component (C) is 20 to 200 parts by mass, and the component (D) is 0.1 to 50 parts by mass. And the proportion of the component (E) is 5 to 40% by mass with respect to the total of the components (A) to (D), and the proportion of the component (F) is based on the total organic solid components. The composition according to claim 1, which is 20 to 50% by mass.   The adhesive sheet which has an adhesive bond layer which consists of an adhesive composition of Claim 1 or 2, and a mold release material layer which coat | covers this adhesive bond layer.   The coverlay film which has an electrically insulating film layer and the adhesive bond layer which consists of an adhesive composition of Claim 1 or 2 provided on this film layer.

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