JP2012138455A - Mounting method of flexible wiring board and polyimide siloxane resin composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a mounting method of a flexible wiring board in which gold plating is performed after forming a protective film, and a polyimide siloxane resin composition having improved gold-plating resistance is used suitably.SOLUTION: In the mounting method of a flexible wiring board including a step for gold-plating a wiring pattern not covered with a protective film but exposed, a polyimide siloxane resin composition is composed to contain at least (A) a polyimide siloxane resin having a substituent group (carboxyl group and/or hydroxyl group) and (B) a hardener containing an epoxy resin as an essential component. The ratio of the epoxy group in the hardener (B) to the substituent group in the polyimide siloxane resin (A) ([quantity of the epoxy group]/[quantity of the substituent group]) is 1.5 or less.

Description

  The present invention relates to a flexible wiring board mounting method and a polyimidesiloxane resin composition suitably used in the mounting method. In particular, the present invention relates to a mounting method of a flexible wiring board that is mounted including a step of gold plating, and a polyimidesiloxane resin composition with improved gold plating resistance that is preferably used in the mounting method.

  A flexible wiring board on which an electronic component such as a semiconductor element is mounted is manufactured by various mounting methods. For example, the flexible wiring board is preferably manufactured by the following mounting method. That is, a step of preparing a substrate on which a conductive metal wiring pattern is formed on the surface of an insulating film, a curable resin composition on a wiring pattern surface of a region where a wiring pattern excluding at least connection terminal portions of the substrate is formed Next, a step of forming a protective film (insulating protective film) that is cured by heat treatment, a step of gold-plating the wiring pattern including the connection terminal portion that is exposed without being covered with the protective film, and a connection of the wiring pattern It is preferably manufactured by a mounting method including a step of mounting an electronic component such as a semiconductor element using a gold bump or the like on the terminal portion, and then a step of protecting and fixing the electronic component using, for example, an underfill material.

  By the way, in this method, during the gold plating process, the gold plating solution may permeate into the gap between the protective film and the conductive metal, causing discoloration, peeling or corrosion, and the reliability of the flexible wiring board is lowered. There was a problem that could be. For this reason, the curable resin composition used in this method has been required to be improved in gold plating resistance.

On the other hand, a polyimide siloxane resin composition comprising a polyimide siloxane resin having a carboxyl group and / or a hydroxyl group as a substituent and an epoxy resin and / or a polyvalent isocyanate compound is used for a protective film of a flexible wiring board. Is already known. Patent Document 1 discloses a polyimidesiloxane resin composition that can suppress discoloration of the copper foil on the protective film side even when immersed in a tin plating bath. Further, Patent Document 2 discloses a mounting in which a protective film is formed after performing a tin plating process in advance in order to avoid intrusion of tin into the gap between the protective film and the copper foil during tin plating (tin diving). It is explained that the method is adopted, and a polyimide siloxane resin composition that can be suitably used in such a mounting method is disclosed.
However, there has been no description of a polyimidesiloxane solution composition that can be suitably used in a mounting method in which gold plating is performed after forming a protective film.

JP 7-304950 A JP 2004-211064 A

  An object of the present invention is to propose a mounting method using a polyimide siloxane resin composition with improved gold plating resistance in a flexible wiring board mounting method in which gold plating is performed after forming a protective film. Another object of the present invention is to propose a polyimidesiloxane resin composition with improved gold plating resistance, which can be suitably used in a flexible wiring board mounting method in which gold plating is performed after forming a protective film.

The present invention relates to the following items.
1. The step of preparing a substrate on which a conductive metal wiring pattern is formed on the film surface, applying a polyimide siloxane resin composition to the region where the wiring pattern excluding at least the connection terminal portion is formed, and then heat-treating A method for mounting a flexible wiring board, including a step of forming a protective film, a step of gold-plating an exposed wiring pattern that is not covered with a protective film, and a step of mounting an electronic component on a connection terminal portion as necessary. And
The polyimide siloxane resin composition comprises at least a polyimide siloxane resin (A) having a substituent (carboxyl group and / or hydroxyl group) and a curing agent (B) having an epoxy resin as an essential component. The method of mounting a flexible wiring board, wherein the ratio of the epoxy group of the curing agent (B) to the substituent of (A) ([quantity of epoxy groups] / [quantity of substituents]) is 1.5 or less .

2. Item 2. The method for mounting a flexible wiring board according to Item 1, wherein the curing agent (B) contains an epoxy resin.

3. Item 3. The method for mounting a flexible wiring board according to Item 1 or 2, wherein the polyimide siloxane resin (A) has a substituent equivalent weight of 2000 to 5000.

4). It comprises at least a polyimidesiloxane resin (A) having a substituent (carboxyl group and / or hydroxyl group) and a curing agent (B) having an epoxy resin as an essential component, with respect to the substituent of the polyimidesiloxane resin (A). The ratio of the epoxy group of the curing agent (B) ([quantity of epoxy group] / [quantity of substituent]) is 1.5 or less, and the flexible wiring board is mounted including the step of gold plating the wiring pattern A polyimide siloxane resin composition, which is used for a protective film.

5). Item 5. The polyimide siloxane resin composition according to item 4, wherein the curing agent (B) contains an epoxy resin and a polyvalent isocyanate compound.

6). Item 6. The polyimidesiloxane resin composition according to item 4 or 5, wherein the substituent equivalent of the polyimidesiloxane resin (A) is 2000 to 5000.

  According to the present invention, it is possible to propose a mounting method suitably using a polyimide siloxane resin composition having improved gold plating resistance in a mounting method of a flexible wiring board in which gold plating is performed after forming a protective film. Further, it is possible to propose a polyimidesiloxane resin composition with improved gold plating resistance that can be suitably used in a flexible wiring board mounting method in which gold plating is performed after forming a protective film.

  In the present invention, a step of preparing a substrate having a conductive metal wiring pattern formed on the film surface, at least applying a polyimide siloxane resin composition to a region where a wiring pattern excluding connection terminal portions is formed, A flexible wiring board including a step of forming a protective film by heat treatment, a step of gold-plating the exposed wiring pattern without being covered with the protective film, and a step of mounting electronic components on the connection terminal portion as necessary In the mounting method, the polyimidesiloxane resin composition includes at least a polyimidesiloxane resin (A) having a substituent (carboxyl group and / or hydroxyl group) and a curing agent (B) having an epoxy resin as an essential component. The ratio of the epoxy group of the curing agent (B) to the substituent of the polyimidesiloxane resin (A) ([quantity of epoxy groups] / [setting Implementation method of a flexible wiring board Quantity groups]) is equal to or more than 1.5.

  In the present invention, the film is preferably an electrically insulating heat-resistant film having flexibility, and usually a polyimide film having a thickness of 5 to 80 μm is preferably used. The wiring pattern is formed by using a laminate in which a conductive metal foil such as copper foil or aluminum foil is laminated on the film surface with or without an adhesive, and the conductive metal foil is made of a photosensitive resin. It can be suitably performed by a conventionally known method such as a method of forming a circuit by an etching method or a method of forming a circuit by screen printing a conductive metal paste on the film surface. The copper foil may be a rolled copper foil or an electrolytic copper foil. A wiring pattern having a thickness of about 2 to 80 μm and a wiring pattern having a line width of about 5 to 500 μm is preferably used.

  A substrate having a conductive metal wiring pattern formed on the film surface is coated with a polyimide siloxane resin composition, which is a feature of the present invention, at least in a region where a wiring pattern excluding connection terminal portions is formed. A protective film is formed by heat treatment. Note that the connection terminal part of the wiring pattern is an inner lead for connecting electronic components such as semiconductor elements, an outer lead for connecting the substrate to other units of the device, etc. A protective film is formed at least on the connection terminal part Not.

  After the protective film is formed, the exposed wiring pattern that is not covered with the protective film is subjected to a gold plating process. As the gold plating treatment, a conventionally known method can be suitably adopted, and electrolytic gold plating or electroless gold plating may be used. Further, other plating processes such as a nickel plating process may be performed before the gold plating process.

  The flexible wiring board mounting method of the present invention is not necessarily essential after the gold plating process is performed, but electronic components such as semiconductor elements are used by using gold bumps or the like in the connection terminal portions of the wiring pattern as necessary. After mounting, the electronic component is then protected and fixed by, for example, an epoxy resin-based underfill material or sealing material. Epoxy resin-based underfill materials and sealing materials are usually cured by heat treatment at a temperature of about 60 to 200 ° C.

  The polyimidesiloxane resin composition that is a feature of the present invention includes at least a polyimidesiloxane resin (A) having a substituent (carboxyl group and / or hydroxyl group) and a curing agent (B) containing an epoxy resin as an essential component. The ratio of the epoxy group of the curing agent (B) to the substituent of the polyimidesiloxane resin (A) ([quantity of epoxy groups] / [quantity of substituents]) is 1.5 or less. .

  The polyimide siloxane resin (A) having a substituent (carboxyl group and / or hydroxyl group) is a polyimide siloxane resin having a carboxyl group and / or a hydroxyl group in the molecule, and the carboxyl group and / or the substituent in the molecule. Or it can obtain suitably by introduce | transducing the unit which has a hydroxyl group. Without limitation, for example, in a solvent, a tetracarboxylic acid component, (a) diaminopolysiloxane, (b) a diamine having a carboxyl group and / or a hydroxyl group as a substituent, and (c) said It can be easily obtained by polymerizing and imidizing with a diamine component composed of other diamines.

  The solvent used in this reaction is not limited as long as it provides a solvent environment for suitably polymerizing and imidizing a tetracarboxylic acid component and a diamine component to obtain polyimide siloxane, but an organic polar solvent having excellent solubility is preferable. . Examples of the organic polar solvent include nitrogen-containing solvents such as N, N-dimethylacetamide, N, N-diethylacetamide, N, N-dimethylformamide, N, N-diethylformamide, N-methyl-2-pyrrolidone, 1, Solvents containing sulfur atoms such as 3-dimethyl-2-imidazolidinone, N-methylcaprolactam, such as dimethyl sulfoxide, diethyl sulfoxide, dimethyl sulfone, diethyl sulfone, hexamethylsulfuramide, phenolic solvents such as cresol, Phenol, xylenol, etc., diglyme solvents such as diethylene glycol dimethyl ether (diglyme), triethylene glycol dimethyl ether (triglyme), tetraglyme, etc., solvents having oxygen atoms in the molecule, such as acetone, Methanol, ethanol, ethylene glycol, dioxane, isophorone, and tetrahydrofuran, lactone solvents such as γ- butyrolactone, etc. γ- valerolactone, other pyridine, and the like tetramethylurea. Moreover, you may use together other organic solvents, such as aromatic hydrocarbon type solvents, such as benzene, toluene, and xylene, solvent naphtha, and benzonitrile, as needed.

  Examples of the tetracarboxylic acid component include 2,3,3 ′, 4′-biphenyltetracarboxylic acid, 3,3 ′, 4,4′-biphenyltetracarboxylic acid, and 2,2 ′, 3,3′-biphenyltetracarboxylic acid. Carboxylic acid, 3,3 ′, 4,4′-diphenyl ether tetracarboxylic acid, 3,3 ′, 4,4′-diphenylsulfone tetracarboxylic acid, 3,3 ′, 4,4′-benzophenone tetracarboxylic acid Acid, 2,2-bis (3,4-benzenedicarboxylic acid) hexafluoropropane, pyromellitic acid, 1,4-bis (3,4-benzenedicarboxylic acid) benzene, 2,2-bis [4- (3 , 4-phenoxydicarboxylic acid) phenyl] propane, 2,3,6,7-naphthalenetetracarboxylic acid, 1,2,5,6-naphthalenetetracarboxylic acid, 1,2,4,5-naphthalene Aromatic tetracarboxylic acids such as tetracarboxylic acid, 1,4,5,8-naphthalenetetracarboxylic acid, 1,1-bis (2,3-dicarboxyphenyl) ethane, or their acid dianhydrides or lower Alcohol esterified products and fats such as cyclopentanetetracarboxylic acid, 1,2,4,5-cyclohexanetetracarboxylic acid, 3-methyl-4-cyclohexene-1,2,4,5-tetracarboxylic acid Preferable examples include cyclic tetracarboxylic acids, or acid dianhydrides and esterified products of lower alcohols. The tetracarboxylic acid component is preferably a tetracarboxylic dianhydride that can be easily reacted with a diamine.

  The diamine component is composed of (a) diaminopolysiloxane, (b) a diamine having a carboxyl group and / or a hydroxyl group as a substituent, and (c) other diamine other than the above, if necessary.

  (A) The diaminopolysiloxane is not particularly limited as long as it is a diamine compound having a silylene skeleton in the molecule, but is preferably a diamine compound represented by the following chemical formula (1).

化学式（１）において、Ｒ_１は２価の脂肪族又は芳香族炭化水素基を示し、Ｒ_２は独立に１価の脂肪族又は芳香族炭素水素基を示し、ｎ１は２〜５０の整数を示す。但し、化学式（１）中、Ｒ_１は炭素数１〜６のアルキレン基又はフェニレン基、特にプロピレン基が好ましく、Ｒ_２は独立に炭素数１〜５のアルキル基又はフェニル基が好ましく、ｎ１は３〜５０、特に３〜２０が好ましい。ジアミノシロキサンのアミノ基は保護基で保護されていてもよい。尚、ジアミノポリシロキサンが２種以上の混合物からなる場合は、ｎ１はアミノ当量から計算される。

In the chemical formula (1), R ₁ represents a divalent aliphatic or aromatic hydrocarbon group, R ₂ independently represents a monovalent aliphatic or aromatic hydrocarbon group, and n1 represents an integer of 2 to 50. Show. However, in chemical formula (1), R ₁ is preferably an alkylene group having 1 to 6 carbon atoms or a phenylene group, particularly preferably a propylene group, R ₂ is independently preferably an alkyl group having 1 to 5 carbon atoms or a phenyl group, and n1 is 3-50, especially 3-20 are preferred. The amino group of diaminosiloxane may be protected with a protecting group. In addition, when diaminopolysiloxane consists of 2 or more types of mixtures, n1 is calculated from an amino equivalent.

  Examples of (a) diaminopolysiloxane include α, ω-bis (2-aminoethyl) polydimethylsiloxane, α, ω-bis (3-aminopropyl) polydimethylsiloxane, α, ω-bis (4-amino). Phenyl) polydimethylsiloxane, α, ω-bis (4-amino-3-methylphenyl) polydimethylsiloxane, α, ω-bis (3-aminopropyl) polydiphenylsiloxane, α, ω-bis (4-aminobutyl) ) Polydimethylsiloxane and the like.

(B) The diamine having a carboxyl group and / or a hydroxyl group as a substituent may be a diamine having a carboxyl group and / or a hydroxyl group in the molecule. The purpose of introducing such a diamine into polyimide siloxane is to cause a curing reaction by reaction with an epoxy group or an isocyanate group.
Although it does not limit, the aromatic diamine which has a carboxyl group and / or a hydroxyl group in a molecule | numerator is suitable, Preferably it is an aromatic diamine represented by following Chemical formula (2).

化学式（２）において、Ｘ及びＹは、それぞれ独立に、直接結合、ＣＨ_２、Ｃ（ＣＨ_３）_２、Ｃ（ＣＦ_３）_２、Ｏ、ベンゼン環、ＳＯ_２を示し、ｒ１はＣＯＯＨ又はＯＨを示し、ｎ２は１又は２であり、ｎ３、ｎ４はそれぞれ独立に０、１又は２、好ましくは０又は１であり、ｎ３及びｎ４の少なくとも一方は１又は２である。

In the chemical formula (2), X and Y each independently represent a direct bond, CH ₂ , C (CH ₃ ) ₂ , C (CF ₃ ) ₂ , O, a benzene ring, or SO ₂ , and r1 is COOH or OH N2 is 1 or 2, n3 and n4 are each independently 0, 1 or 2, preferably 0 or 1, and at least one of n3 and n4 is 1 or 2.

  Examples of the diamine represented by the chemical formula (2) include diaminophenol compounds such as 2,4-diaminophenol, 3,3′-diamino-4,4′-dihydroxybiphenyl, 4,4 ′. -Diamino-3,3'-dihydroxybiphenyl, 4,4'-diamino-2,2'-dihydroxybiphenyl, 4,4'-diamino-2,2 ', 5,5'-tetrahydroxybiphenyl, etc. Hydroxybiphenyl compounds, 3,3′-diamino-4,4′-dihydroxydiphenylmethane, 4,4′-diamino-3,3′-dihydroxydiphenylmethane, 4,4′-diamino-2,2′-di Hydroxydiphenylmethane, 2,2-bis [3-amino-4-hydroxyphenyl] propane, 2,2-bis [4-amino-3-hydroxy Hydroxydiphenylalkane compounds such as benzyl] propane, 2,2-bis [3-amino-4-hydroxyphenyl] hexafluoropropane, 4,4′-diamino-2,2 ′, 5,5′-tetrahydroxydiphenylmethane 3,3′-diamino-4,4′-dihydroxydiphenyl ether, 4,4′-diamino-3,3′-dihydroxydiphenyl ether, 4,4′-diamino-2,2 ′ Hydroxydiphenyl ether compounds such as dihydroxydiphenyl ether, 4,4′-diamino-2,2 ′, 5,5′-tetrahydroxydiphenyl ether, 3,3′-diamino-4, 4'-dihydroxydiphenyl sulfone, 4,4'-diamino-3,3'-dihydroxydiphenyl sulfone, 4,4'-di Hydroxydiphenylsulfone compounds such as mino-2,2′-dihydroxydiphenylsulfone, 4,4′-diamino-2,2 ′, 5,5′-tetrahydroxydiphenylsulfone, 2,2-bis [4- ( Bis (hydroxyphenoxy) biphenyl compounds such as bis (hydroxyphenoxyphenyl) alkane compounds such as 4-amino-3-hydroxyphenoxy) phenyl] propane and 4,4′-bis (4-amino-3-hydroxyphenoxy) biphenyl And diamine compounds having an OH group such as bis (hydroxyphenoxyphenyl) sulfone compounds such as 2,2-bis [4- (4-amino-3-hydroxyphenoxy) phenyl] sulfone.

  Furthermore, examples of the diamine represented by the chemical formula (2) include benzene carboxylic acids such as 3,5-diaminobenzoic acid and 2,4-diaminobenzoic acid, 3,3′-diamino-4,4′-dicarboxy Biphenyl, 4,4′-diamino-3,3′-dicarboxybiphenyl, 4,4′-diamino-2,2′-dicarboxybiphenyl, 4,4′-diamino-2,2 ′, 5,5 ′ Carboxyphenyl compounds such as tetracarboxybiphenyl, 3,3′-diamino-4,4′-dicarboxydiphenylmethane, 4,4′-diamino-3,3′-dicarboxydiphenylmethane, 4,4′-diamino- 2,2′-dicarboxydiphenylmethane, 2,2-bis [3-amino-4-carboxyphenyl] propane, 2,2-bis [4-amino-3-carboxy Carboxydiphenylalkane compounds such as boxyphenyl] propane, 2,2-bis [3-amino-4-carboxyphenyl] hexafluoropropane, 4,4′-diamino-2,2 ′, 5,5′-tetracarboxybiphenyl 3,3′-diamino-4,4′-dicarboxydiphenyl ether, 4,4′-diamino-3,3′-dicarboxydiphenyl ether, 4,4′-diamino-2,2 ′ -Carboxydiphenyl ether compounds such as dicarboxydiphenyl ether, 4,4'-diamino-2,2 ', 5,5'-tetracarboxydiphenyl ether, 3,3'-diamino-4, 4'-dicarboxydiphenyl sulfone, 4,4'-diamino-3,3'-dicarboxydiphenyl sulfone, 4,4'-diamino-2,2 , 5,5'-tetracarboxydiphenylsulfone and other carboxydiphenylsulfone compounds, and bis (carboxyphenoxyphenyl) alkane compounds such as 2,2-bis [4- (4-amino-3-carboxyphenoxy) phenyl] propane Bis (carboxyphenoxy) biphenyl compounds such as 4,4′-bis (4-amino-3-carboxyphenoxy) biphenyl, 2,2-bis [4- (4-amino-3-carboxyphenoxy) phenyl] sulfone Examples thereof include diamine compounds having a COOH group such as bis (carboxyphenoxyphenyl) sulfone compounds.

  (C) Other diamines are used as necessary. (C) Other diamines are not particularly limited as long as they are diamines other than (a) diaminopolysiloxane and (b) a diamine having a carboxyl group and / or a hydroxyl group as a substituent. Aromatic diamines comprising a plurality of benzene rings represented by

化学式（３）において、Ｘ及びＹは、それぞれ独立に、直接結合、ＣＨ_２、Ｃ（ＣＨ_３）_２、Ｃ（ＣＦ_３）_２、Ｏ、ベンゼン環、ＳＯ_２を示し、ｎ５は１又は２である。

In the chemical formula (3), X and Y each independently represent a direct bond, CH ₂ , C (CH ₃ ) ₂ , C (CF ₃ ) ₂ , O, a benzene ring, SO ₂ , and n5 is 1 or 2 It is.

Examples of the aromatic diamine represented by the chemical formula (3) include 1,4-diaminobenzene, 1,3-diaminobenzene, 2,4-diaminotoluene, 1,4-diamino-2,5-dihalogenobenzene and the like. Diamines containing one benzene, bis (4-aminophenyl) ether, bis (3-aminophenyl) ether, bis (4-aminophenyl) sulfone, bis (3-aminophenyl) sulfone, bis (4-aminophenyl) methane, bis (3-aminophenyl) methane, bis (4-aminophenyl) sulfide, bis (3-aminophenyl) sulfide, 2,2-bis (4-aminophenyl) propane, 2, 2-bis (3-aminophenyl) propane, 2,2-bis (4-aminophenyl) hexafluoropropane, o-dianisidine, o-to Diamines containing two benzenes such as gin and tolidine sulfonic acids, 1,4-bis (4-aminophenoxy) benzene, 1,4-bis (3-aminophenoxy) benzene, 1,4-bis (4-amino) Phenyl) benzene, 1,4-bis (3-aminophenyl) benzene, α, α′-bis (4-aminophenyl) -1,4-diisopropylbenzene, α, α′-bis (4-aminophenyl)- Diamines containing three benzenes such as 1,3-diisopropylbenzene, 2,2-bis [4- (4-aminophenoxy) phenyl] propane, 2,2-bis [4- (4-aminophenoxy) phenyl] Hexafluoropropane, 2,2-bis [4- (4-aminophenoxy) phenyl] sulfone, 4,4 ′-(4-aminophenoxy) biphenyl, 9,9-bi Examples thereof include diamine compounds such as diamines containing 4 or more benzenes such as su (4-aminophenyl) fluorene and 5,10-bis (4-aminophenyl) anthracene.
In addition, aliphatic diamine compounds such as hexamethylene diamine and diaminododecane can be used together with the diamine.

  The ratio of the tetracarboxylic acid component and the diamine component used is approximately equimolar, preferably 0.95 to 1.2, more preferably 1.0 to 1.1, with respect to 1 mol of the diamine component. The molar ratio.

  Further, the diamine component is not particularly limited, but in 100 mol% of the diamine component, preferably 20 to 95 mol%, more preferably 40 to 90 mol% of (a) diaminopolysiloxane, preferably 5 to 80 mol%, More preferably, a diamine having a carboxyl group and / or a hydroxyl group can be used as a substituent of 10 to 60 mol% (b). If necessary, 0 to 75 mol%, more preferably 0 to 40 mol% of (c) other diamines other than those described above can be used.

  The “polymerization / imidization” reaction between the tetracarboxylic acid component and the diamine component means that the tetracarboxylic acid component reacts with the diamine component to form an imide ring while forming a polyimide skeleton. Therefore, a conventionally known polymerization / imidization method can be suitably used. For example, the tetracarboxylic acid component and the diamine component can be heated at a temperature of about 100 to 250 ° C. in a solvent to be polymerized and imidized in one step. Further, a tetracarboxylic acid component and a diamine component are reacted in a solvent at a temperature of about 100 ° C. or less to obtain a polyimide precursor (polyamic acid), and then heated to about 100 to 250 ° C. for imidization or dehydration. It can also be imidized by a chemical imidizing agent such as acetic anhydride / pyridine system or dicyclohexylcarbodiimide as a cyclizing reagent. In the imidization reaction, an azeotropic agent such as toluene or xylene may be added and reacted to remove the generated water from the system.

  The polyimidesiloxane resin can be dissolved in an organic solvent at a high concentration of at least 3% by weight, preferably about 5 to 60% by weight, and the solution viscosity at 25 ° C. (E-type rotational viscometer) is 1 to 10,000. A poise, particularly 1 to 100 poise is preferred. The polyimide siloxane resin preferably has a high imidization rate. The logarithmic viscosity (measurement concentration: 0.5 g / 100 ml, solvent: N-methyl-2-pyrrolidone, measurement temperature: 30 ° C.) as a measure of molecular weight is 0.15 or more, particularly 0.16 to 2 This is preferable from the viewpoint of mechanical properties such as strength and elongation of the cured product. Further, the imidation ratio obtained from the infrared absorption spectrum is preferably 90% or more, particularly 95% or more, and substantially 100%.

The curing agent (B) of the polyimidesiloxane resin composition of the present invention contains an epoxy resin as an essential component. Therefore, the curing agent (B) may be an epoxy resin alone, but those containing an epoxy resin and a polyvalent isocyanate compound can be suitably used.
,

  The epoxy resin is not particularly limited as long as it is a compound having an epoxy group, but a liquid or solid resin having an epoxy equivalent of about 100 to 4000 and a molecular weight of about 300 to 10,000 is preferable. For example, bisphenol A type or bisphenol F type epoxy resin (manufactured by Japan Epoxy Resin Co., Ltd .: Epicoat 806, Epicoat 825, Epicoat 828, Epicoat 1001, Epicoat 1002, Epicoat 1003, Epicoat 1004, Epicoat 1055, Epicoat 1004AF, Epicoat 1007, Epicoat 1009, Epicoat 1010, etc.) Trifunctional or higher functional epoxy resin (Japan Epoxy Resins Co., Ltd .: Epicoat 152, Epicoat 154, Epicoat 180 Series, Epicoat 157 Series, Epicoat 1032 Series, Ciba-Geigy: MT0163, etc. ), Hibe ETBN 1300 × 40 manufactured by Ube Industries, Ltd., Denarex R-45EPT manufactured by Nagase ChemteX Corporation, bifunctional bifeni Type epoxy resin (Japan Epoxy Resins Co., Ltd.: YX4000 series), epoxy-modified polysiloxane (Shin-Etsu Chemical Co., Ltd., etc. KF105) and the like.

The polyvalent isocyanate blended with the epoxy resin may be any one having two or more isocyanate groups in one molecule. Examples of such polyvalent isocyanate compounds include aliphatic, alicyclic or aromatic diisocyanates, such as 1,4-tetramethylene diisocyanate and 1,5-pentamethylene diisocyanate. Net, 1,6-hexamethylene diisocyanate, 2,2,4-trimethyl-1,6-hexamethylene diisocyanate, lysine diisocyanate, 3-isocyanate methyl 3,5,5-trimethylcyclohexyl isocyanate (isophorone diisocyanate), 1,3-bis (isocyanatomethyl) -cyclohexane, 4,4'-dicyclohexylmethane diisocyanate, tolylene diisocyanate Neat, 4,4'-diphenylmethane diisocyanate, 1,5-naphthalene diisocyanate, tolidine diisocyanate, xylylene diene Soshiane - door, and the like can be given.
Further, as the polyvalent isocyanate compound, those derived from aliphatic, alicyclic or aromatic polyvalent isocyanates such as isocyanurate-modified polyisocyanate, burette-modified polyisocyanate, It may be a urethane-modified polyvalent isocyanate.
As the polyvalent isocyanate compound, a block polyvalent isocyanate in which the isocyanate group of the polyvalent isocyanate is blocked with a blocking agent is preferably used.
Examples of the block polyvalent isocyanate include Burnock D-500 (tolylene diisocyanate blocked) and D-550 (1,6-hexamethylene diisocyanate blocked) manufactured by Dainippon Ink and Chemicals, Inc. ), Takenate Takenate B-830 (tolylene diisocyanate blocked), B-815N (4,4′-methylenebis (cyclohexyl isocyanate) blocked), B-842N (made by Mitsui Takeda Chemical Co., Ltd.) 1,3-bis (isocyanatemethyl) cyclohexane blocked), B-846N (1,3-bis (isocyanatemethyl) cyclohexane blocked), B-874N (isophorone diisocyanate blocked), first Elastolone BN-P17 (4,4'-diphenylmethane manufactured by Kogyo Seiyaku Co., Ltd. Isocyanate block), Elastron BN-04, Elastron BN-08, Elastron BN-44, Elastron BN-45 (above, 3 to 5 functional groups per molecule of urethane-modified polyisocyanate block, all water emulsion (It can be used after being dried and isolated with a product).

In the polyimidesiloxane resin composition of the present invention, the substituent (carboxyl group and / or hydroxyl group) of the polyimidesiloxane resin (A) has a role as a crosslinking group. In the present invention, the ratio of the substituent (carboxyl group and / or hydroxyl group) of the polyimidesiloxane resin (A) to the epoxy group of the curing agent (B) ([quantity of epoxy groups] / [quantity of substituents]). Is 1.5 or less, preferably 1.3 or less, more preferably 1.2 or less. Moreover, Preferably it is 0.2 or more, More preferably, it is 0.3 or more.
If this ratio ([epoxy group quantity] / [substituent quantity]) exceeds 1.5, it is not preferable because the gold plating resistance may deteriorate. On the other hand, if it is less than 0.2, characteristics such as solvent resistance are not obtained. Is unfavorable because it decreases.

  Although it does not specifically limit, the usage-amount of an epoxy resin is about 0.1-30 mass parts normally with respect to 100 mass parts of polyimide siloxane resins. Moreover, the usage-amount of a polyvalent isocyanate compound is about 0-40 mass parts normally with respect to 100 mass parts of polyimidesiloxane resins.

In the polyimidesiloxane resin composition of the present invention, the polyimidesiloxane resin (A) having a substituent (carboxyl group and / or hydroxyl group) preferably has a substituent equivalent of 2000 to 5000, particularly 3000 to 4000. The substituent equivalent is the mass of polyimide siloxane per substituent (carboxyl group and / or hydroxyl group).
When the substituent equivalent is less than 2,000, the resulting cured product has a high crosslinking density and may be less flexible. When it exceeds 5,000, the polyimide siloxane resin (A) has a substituent (carboxyl group and / or hydroxyl group). When the ratio of the epoxy groups in the curing agent (B) ([quantity of epoxy groups] / [quantity of substituents]) is 1.5 or less, the resulting cured product has a low crosslink density and solvent resistance. The characteristics such as are likely to deteriorate.

  The polyimide siloxane resin composition of the present invention comprises a polyimide siloxane resin (A) having a substituent (carboxyl group and / or hydroxyl group), and a curing agent (B) having an epoxy resin as an essential component, and a solvent as an essential component. It is suitably used as a solution composition. As the solvent, a solvent that can be used when producing a polyimidesiloxane resin can be suitably used.

  The polyimidesiloxane resin composition of the present invention is dissolved in a solvent at a solid content concentration of at least 3% by mass, preferably 5 to 60% by mass, more preferably 20 to 60% by mass, and still more preferably 30 to 60% by mass. It is preferable that The higher the concentration of the solution composition, the more likely the problem of viscosity stability occurs. For this reason, when it exceeds 60 mass%, a viscosity will become high and handling will be difficult normally and workability | operativity will be bad. The viscosity of the polyimidesiloxane resin composition is preferably a solution viscosity (E-type rotational viscosity) at 25 ° C. of 0.1 to 1000 Pa · s, more preferably 0.1 to 100 Pa · s.

The polyimide siloxane resin composition of the present invention further comprises a resin such as a phenol resin, an organic or inorganic filler, a coloring pigment such as a curing catalyst such as an imidazole or a tertiary amine, such as a polysiloxane, a fluorine-modified resin. For resin compositions for protective films such as flame retardants and antioxidants such as antifoaming agents such as polysiloxane, polyacrylic and polyvinyl, such as hindered phenolic compounds, phosphorus compounds and hindered amine compounds The conventionally well-known component used can be used suitably.
In addition, when a phenol resin forms a protective film in this invention, since the reactivity with the carboxyl group and / or hydroxyl group of a polyimidesiloxane resin (A) is low, there is no substantial participation in a curing reaction. Conceivable.

  As the organic or inorganic filler, known ones can be suitably used. For example, inorganic fine particles such as silica, alumina, titanium oxide, barium sulfate, talc, calcium carbonate, glass powder, quartz powder, epoxy resin powder, melamine resin powder, urea resin powder, guanamine resin powder, polyester resin powder, polyamide resin Organic fine particles such as powder, polyimide resin powder, rubber particles, and silicone powder can be suitably used. The particle diameter (average particle diameter) is preferably 0.001 to 2 μm. In the case of forming a pattern by screen printing, it is preferable to add thixotropic properties by adding a filler such as silica in order to suppress bleeding. The compounding amount of the organic or inorganic filler is generally 1 to 200 parts by mass, preferably 5 to 100 parts by mass with respect to 100 parts by mass of the polyimidesiloxane resin (A).

As the coloring pigment, known pigments such as a blue pigment, a green pigment, and a yellow pigment can be suitably used singly or in combination. Among these, it is preferable to use a pigment that does not contain a chlorine atom and a bromine atom in the molecular structure, and use a single pigment or a plurality of pigments so as to give blue or green color. When a compound containing a chlorine atom and a bromine atom in the molecular structure is contained in the composition, a harmful substance may be generated when a product using the compound is incinerated.
The blending amount of the color pigment is not limited as long as the target color can be colored, but is usually preferably about 0.01 to 5 parts by mass, more preferably 0.05 to 1 part by mass with respect to 100 parts by mass of the polyimidesiloxane resin. .

  The polyimidesiloxane resin composition of the present invention is applied to the surface of the wiring pattern excluding at least the connection terminal portion of the flexible wiring board so that the thickness of the protective film is about 3 to 60 μm, for example, by screen printing. The coating film is formed, the solvent is removed at a low temperature, and then the polyimidesiloxane resin (A) and the curing agent (B) undergo a curing reaction by heat treatment, for example, 60 to 200 ° C., preferably 80 to Protective film by heat treatment at 150 ° C., more preferably 100 to 130 ° C., for 5 minutes to 5 hours, preferably 10 minutes to 3 hours, more preferably 15 minutes to 2 hours, with hot air, infrared rays or far infrared rays Can be suitably obtained.

In the curing reaction of the polyimidesiloxane resin composition of the present invention, the crosslinking group (carboxyl group and / or hydroxyl group) of the relatively high molecular weight polyimidesiloxane resin reacts with the reactive group of the epoxy resin or polyvalent isocyanate compound. For this reason, since the cross-linking group and the reactive group are not uniformly dispersed in the reaction field, it is considered that the theoretical stoichiometric reaction is not performed. Therefore, in the protective film obtained by the heat treatment in the present invention, a certain amount of cross-linked structure is formed, and a considerable amount of the cross-linking group of the polyimidesiloxane resin (A) and the reactive group of the curing agent (B) is not reacted. It seems that it remains in the state.
The feature of the present invention is that the gold plating resistance of the protective film obtained as a result of the special reaction as described above of the polyimidesiloxane resin composition is a combination of an epoxy resin and a polyvalent isocyanate compound as a curing agent (B). Even if it exists, the ratio ([quantity of epoxy group] / [quantity of substituent]) of the curing agent (B) to the substituent (carboxyl group and / or hydroxyl group) of the polyimidesiloxane resin (A) is controlled. It has been achieved by The gold plating resistance of the protective film is not directly related to the amount of use even when the curing agent (B) contains a polyvalent isocyanate compound.

  In the flexible wiring board mounting method of the present invention, after the step of forming such a protective film, when the exposed wiring pattern that is not covered with the protective film is gold-plated, the gold plating treatment liquid is electrically conductive with the protective film. It is possible to manufacture a flexible wiring board with higher reliability by suppressing the occurrence of problems such as discoloration, peeling, and corrosion by penetrating into the gap with the conductive metal.

In the flexible wiring board mounting method of the present invention, it is not always necessary after the gold plating treatment for the exposed wiring pattern that is not covered with the protective film, but if necessary, the connecting terminal portion of the wiring pattern may be coated with gold. A flexible wiring board can be suitably manufactured by mounting electronic components such as semiconductor elements using bumps and the like, and further protecting and fixing the electronic components using, for example, an underfill material or a sealing material.
The mounting method of the flexible wiring board of the present invention can be particularly preferably employed in the so-called COF method or FPC method.

  Hereinafter, the present invention will be described in more detail with reference to examples. In addition, this invention is not limited to the following examples.

The evaluation methods used in the following examples are as follows.
[Measurement method of solid content]
The sample solution composition was heat-treated while being heated in the order of 120 ° C. for 10 minutes and then 250 ° C. for 60 minutes. From the sample weight (w1) before the heat treatment and the weight (w2) after the heat treatment, the solid content concentration was calculated by the following formula.
Solid content concentration (%) = [w2 / w1] × 100

[Measurement method of solution viscosity]
The solution viscosity at 10 rpm at 25 ° C. was measured using an E-type rotational viscometer.

[Evaluation method of gold plating resistance]
Dry and cure the polyimide siloxane composition blended as in the above example on a flexible wiring board (using copper-clad laminates using Upicel N Cu foil thickness / PI film thickness = 9 μm / 25 μm manufactured by Ube Industries) It apply | coated by screen printing so that the film thickness after that might be set to 15-20 micrometers. The film was dried at 80 ° C. for 30 minutes and then cured at 150 ° C. for 60 minutes to form a protective film. Next, the exposed wiring pattern not covered with the protective film is subjected to electrolytic gold / nickel plating (Au layer thickness / Ni layer thickness = 0.3 μm / 0.5 μm), and the end of the protective film of the obtained flexible wiring board The amount of gold plating in the part (distance from the end) was observed to evaluate the resistance to gold plating.
The depth of penetration was less than 50 μm, and the above was rated as x.

[Method for measuring substituent equivalent]
The sample was precisely weighed in a pear-shaped three-necked flask and completely dissolved using 40 mL of THF. The inside of the flask was replaced with nitrogen gas, and an appropriate amount of a phenolphthalein solution was added. Next, a micro burette (KOH) was set and the titer (t1) was determined under stirring. Moreover, the titer (t2) of the blank test was measured in the same manner. The COOH group equivalent was calculated by the following formula.
Substituent equivalent (g / eq) =
1 / [{(t1-t2) × 0.01 × F / (S × solid content concentration)} / 1000]
t1: 0.01 mol / L KOH-ethanol solution titration of sample solution (mL)
t2: 0.01 mol / L KOH-ethanol solution titration of empty sample (mL)
F: Factor of 0.01 mol / L KOH-ethanol solution
S: Sample (g)

The raw materials used in the following examples are as follows.
Curing agent (epoxy resin)
Epicoat 157S70: Epoxy equivalent 200 manufactured by Mitsubishi Chemical Corporation
YX4000HK: Epoxy equivalent 190 manufactured by Mitsubishi Chemical Corporation
(Isocyanate)
Burnock D-550: manufactured by DIC (1,6-hexamethylene diisocyanate blocked: NCO concentration 6.9%)
Curing accelerator JEFFCAT DMDEE: manufactured by Huntsman (bis [(2-morpholino) ethyl] ether)
2E4MZ: Shikoku Kasei Kogyo Co., Ltd. (2-ethyl-4methylimidazole)
Filler SG-95: average particle size 2.5 μm manufactured by Nippon Talc
Aerosil # 50: Nippon Aerosil Co., Ltd. average particle size 30 nm

[Reference Example 1]
Manufacture of polyimidesiloxane resin A glass flask with a capacity of 500 ml was charged with 61.79 g (0.21 mol) of 2,3,3 ′, 4′-biphenyltetracarboxylic dianhydride and 100 g of solvent triglyme under a nitrogen atmosphere. The mixture was heated and stirred at 80 ° C. 122.24 g (0.145 mol) of α, ω-bis (3-aminopropyl) polydimethylsiloxane (amine equivalent 422) and 40 g of triglyme were added, and the mixture was heated and stirred at 175 ° C. for 60 minutes. Furthermore, 13.29 g (0.033 mol) of 2,2-bis [4- (4-aminophenoxy) phenyl] propane and 8.29 g (0 of bis (3-carboxy-4-aminophenyl) methane were added to this reaction solution. 0.029 mol) and 50 g of triglyme were added, and the mixture was heated and stirred at 175 ° C. for 20 hours and then filtered. The resulting polyimidesiloxane reaction solution was a solution having a polymer solid content concentration of 52% by weight and ηinh of 0.20. The imidization rate was substantially 100%.

[Reference Example 2]
A glass flask with a capacity of 500 ml is charged with 60.02 g (0.21 mol) of 2,3,3 ′, 4′-biphenyltetracarboxylic dianhydride and 100 g of solvent triglyme and heated at 80 ° C. in a nitrogen atmosphere. Stir. α, ω-bis (3-aminopropyl) polydimethylsiloxane (amine equivalent 422) 118.16 g (0.14 mol) and triglyme 40 g were added, and the mixture was heated and stirred at 175 ° C. for 60 minutes. Further, this reaction solution was charged with 12.32 g (0.03 mol) of 2,2-bis [4- (4-aminophenoxy) phenyl] propane, 4.56 g (0.03 mol) of 3,5-diaminobenzoic acid, and Triglyme (50 g) was added, and the mixture was heated and stirred at 175 ° C. for 20 hours, followed by filtration. The resulting polyimidesiloxane reaction solution was a solution having a polymer solid content concentration of 52% by weight and ηinh of 0.20. The imidization rate was substantially 100%.

[Example 1]
In the polyimidesiloxane resin solution of Reference Example 1, 1.2 parts by mass of epoxy resin Epicoat 157S70, 1.2 parts by mass of epoxy resin YX4000HK, and 10 parts of Aerosil 50 of finely divided silica are added to 100 parts by mass of polyimidesiloxane resin. 0.08 parts by mass, 80.0 parts by mass of talc SG-95, and 1.68 parts by weight of silane coupling agent KBE-402 were added and stirred to obtain a uniformly mixed polyimidesiloxane resin composition. .
In addition to 100 parts by mass of the total amount of polyimidesiloxane resin and epoxy resin in the polyimidesiloxane resin composition, 0.8 parts by mass of bis [(2-morpholino) ethyl] ether and 2E4MZ0.2 mass as a curing accelerator. Was dissolved in 27 g of a mixed solvent of cyclohexanone and diglyme (cyclohexanone: diglyme = 1: 6) to obtain a polyimidesiloxane resin composition.
This resin composition was screen-printed on the copper wiring pattern surface of the flexible wiring board and heat-treated at 80 ° C. for 30 minutes and 150 ° C. for 60 minutes to form a protective film. Next, the exposed wiring pattern not covered with the protective film was subjected to gold plating treatment, and the gold plating resistance at the end of the protective film of the obtained flexible wiring board was observed. Table 1 shows the evaluation results of the polyimidesiloxane resin composition and gold plating resistance.

[Examples 2 to 4]
Except having changed the kind and addition amount of a hardening | curing agent (B) as shown in Table 1, it carried out similarly to Example 1 and obtained the polyimidesiloxane resin composition.
Using this resin composition, the gold plating resistance at the end of the protective film was observed in the same manner as in Example 1. Table 1 shows the evaluation results of the polyimidesiloxane resin composition and gold plating resistance.

[Comparative Examples 1-2]
A polyimide siloxane resin composition was obtained in the same manner as in Example 1 except that the types and addition amounts of the polyimide siloxane resin (A) and the curing agent (B) were changed as shown in Table 1.
Using this resin composition, the gold plating resistance at the end of the protective film was observed in the same manner as in Example 1. Table 1 shows the evaluation results of the polyimidesiloxane resin composition and gold plating resistance.

  According to the present invention, it is possible to propose a mounting method suitably using a polyimide siloxane resin composition having improved gold plating resistance in a mounting method of a flexible wiring board in which gold plating is performed after forming a protective film. Further, it is possible to propose a polyimidesiloxane resin composition with improved gold plating resistance that can be suitably used in a flexible wiring board mounting method in which gold plating is performed after forming a protective film.

Claims (6)

The step of preparing a substrate on which a conductive metal wiring pattern is formed on the film surface, applying a polyimide siloxane resin composition to the region where the wiring pattern excluding at least the connection terminal portion is formed, and then heat-treating A method for mounting a flexible wiring board, including a step of forming a protective film, a step of gold-plating an exposed wiring pattern that is not covered with a protective film, and a step of mounting an electronic component on a connection terminal portion as necessary. And
The polyimide siloxane resin composition comprises at least a polyimide siloxane resin (A) having a substituent (carboxyl group and / or hydroxyl group) and a curing agent (B) having an epoxy resin as an essential component. The method of mounting a flexible wiring board, wherein the ratio of the epoxy group of the curing agent (B) to the substituent of (A) ([quantity of epoxy groups] / [quantity of substituents]) is 1.5 or less .   The method for mounting a flexible wiring board according to claim 1, wherein the curing agent (B) contains an epoxy resin and a polyvalent isocyanate compound.   The mounting method of the flexible wiring board according to claim 1 or 2, wherein the substituent equivalent of the polyimidesiloxane resin (A) is 2000 to 5000.   It comprises at least a polyimidesiloxane resin (A) having a substituent (carboxyl group and / or hydroxyl group) and a curing agent (B) having an epoxy resin as an essential component, with respect to the substituent of the polyimidesiloxane resin (A). The ratio of the epoxy group of the curing agent (B) ([quantity of epoxy group] / [quantity of substituent]) is 1.5 or less, and the flexible wiring board is mounted including the step of gold plating the wiring pattern A polyimide siloxane resin composition, which is used for a protective film.   The polyimide siloxane resin composition according to claim 4, wherein the curing agent (B) contains an epoxy resin and a polyvalent isocyanate compound.   The polyimide siloxane resin composition according to claim 4 or 5, wherein the substituent equivalent of the polyimide siloxane resin (A) is 2000 to 5000.