JP2007070471A - Plastic film having adhesive layer, flexible printed circuit board having cover film and method for producing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a cover film having an adhesive layer, having high adhesive strength between a plastic film and a conductive circuit, good soldering heat-resistance and excellent storage stability and keeping a pattern-embedding property for a long period. <P>SOLUTION: An adhesive layer (II) formed of an adhesive composition (I) containing (A) a polyurethane polyurea resin having an acid value of 3-25 mgKOH/g and produced by reacting a polyamino compound (e) with a urethane prepolymer (d) having an isocyanate group and obtained by reacting a polyol compound (a), an organic diisocyanate (b) and a diol compound (c) having carboxyl group is sandwiched between a plastic film free from releasing treatment and a protection film to obtain the plastic film having an adhesive layer. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention particularly relates to a plastic film with an adhesive layer (a cover film with an adhesive layer or a cover layer) for protecting a conductive circuit of a flexible printed wiring board made of a polyimide film on which a semiconductor integrated circuit (IC) or the like is mounted. And a flexible printed wiring board with a cover film and a method for producing the same.

In the process of producing a wiring board, various adhesives having excellent reliability, peel strength, heat resistance and the like are used. A flexible printed wiring board, which has been used in an increasing amount as a wiring board, has a conductive film provided on a base film by various methods. In order to protect the conductive circuit, prevent oxidation, and improve the flexibility of the conductive circuit, a protective / coating plastic film is generally coated via an adhesive layer.
The flexible printed wiring board is coated with a cover film, and then the entire wiring board including the solder portion formed by printing or coating is heated to about 230 to 280 ° C by infrared reflow or the like in order to mount electronic components. Then, the solder part is melted (solder reflow), and the electronic component is joined to the wiring board. There is also a process of attaching a cover film so that a part of the conductive circuit of the flexible printed wiring board is exposed, and bringing the exposed conductive circuit part into contact with the molten solder. Films are also exposed to high heat.
Accordingly, the adhesive layer for the cover film needs to have heat resistance that does not cause foaming / peeling due to solder reflow, and further, it does not cause foaming / peeling even when it comes into contact with molten solder. Heat resistance is required.

  Printed wiring boards are key components in the electronics field, where the market is growing rapidly, and their manufacturing and processing bases are scattered throughout the country. Therefore, printed wiring boards and materials for producing them are desired to have excellent storage stability with little property change even after transport and storage processes under various conditions. Therefore, the cover film with an adhesive layer in which an adhesive layer to be called a precursor of the adhesive layer after curing is provided on the plastic film is desired to have a pot life of about 3 months at room temperature.

  For the adhesive used for such applications, for example, a mixture of an epoxy resin and a curing agent of an epoxy resin is used as a curing component to improve the peel strength and to give flexibility, such as acrylonitrile butadiene rubber. An epoxy resin composition containing a flexible component is widely used (see, for example, Patent Document 1). Such an epoxy resin-based composition has high heat resistance and good substrate adhesion, but most of the composition is occupied by the epoxy resin and its curing agent, and the epoxy resin is in a semi-cured state (B stage) ) In many cases. Therefore, it needs to be stored at a low temperature, and has a problem of poor storage stability.

  Moreover, the acrylic resin type composition which mix | blended the epoxy resin as a hardening component using the acrylic resin for a base polymer is proposed (for example, refer patent document 2, patent document 3). These contain functional groups that can be cross-linked with epoxy resin in the acrylic resin, and since substantially no epoxy resin curing agent is used, a composition that has good storage stability and adheres well to metal materials is obtained. However, there is a problem that the adhesion to the polyimide film is not yet sufficient.

  Further, a method has been proposed in which a saturated polyester resin is used in combination and the curing component is relatively reduced to improve storage stability and the degree of curing is adjusted, but there is a problem that solder heat resistance is reduced (Patent Document 4). 5).

  In addition, an adhesive composition containing an epoxy adhesive as the main component and a urethane prepolymer composed of a diol and diisocyanate and a diamine curing agent has excellent copper foil / polyimide adhesive strength and good solder heat resistance. It has been proposed to have In this adhesive composition, the diamine compound, which is a curing agent, reacts with both the epoxy resin and the urethane prepolymer to obtain good heat resistance, but the isocyanate group which is a functional group of the urethane prepolymer and the diamine curing agent It is highly reactive and it is difficult to achieve both storage stability and solder heat resistance (see Patent Document 6).

Furthermore, Patent Document 7 discloses an adhesive composition containing a resin containing a urethane bond and / or a urea bond in the main chain and a thermosetting resin. However, a resin containing a urethane bond and / or a urea bond in the main chain disclosed in Patent Document 7 does not have a carboxyl group. Therefore, even if an epoxy resin is used as the thermosetting resin, no reaction occurs between the two resins, so that the solder heat resistance is poor. In particular, the solder heat resistance after humidification is significantly reduced.
JP-A-4-370996 JP-A-9-316398 JP 2002-12841 A JP-A-6-330014 Japanese Unexamined Patent Publication No. 2000-273430 JP-A-8-32230 Japanese Patent Laid-Open No. 10-178066

  The present invention solves the problems of conventional adhesive compositions for flexible copper-clad boards and adhesive compositions for flexible printed wiring boards, and the adhesive strength between a plastic film such as a polyimide film and a conductive circuit. Adhesive for flexible printed wiring board coating, which has excellent solder heat resistance compared to the case where it is not stored even when stored as a cover film with an adhesive layer before bonding. It aims at providing the plastic film with an agent layer.

The present invention has an isocyanate group obtained by reacting a polyol compound (a), an organic diisocyanate (b), and a diol compound (c) having a carboxyl group, between a plastic film that has not been peeled off and a protective film. An adhesive containing a polyurethane polyurea resin (A) obtained by reacting a urethane prepolymer (d) and a polyamino compound (e) and having an acid value of 3 to 25 mg KOH / g, and an epoxy resin (B) The present invention relates to a plastic film with an adhesive layer formed by sandwiching an adhesive layer (II) formed from the composition (I).
In addition, the plastic film with an adhesive layer of this invention is for coat | covering the surface by the side of the conductive circuit of the flexible printed wiring board which has a conductive circuit on the surface mentioned later. Therefore, the plastic film that is not peeled and used in the present invention is sometimes referred to as a cover film.

  Moreover, this invention makes the surface of the conductive circuit side of the flexible printed wiring board which has a conductive circuit on the surface react with the diol compound (c) which has a polyol compound (a), organic diisocyanate (b), and a carboxyl group. Polyurethane polyurea resin (A) having an acid value of 3 to 25 mg KOH / g obtained by reacting the urethane prepolymer (d) having an isocyanate group and the polyamino compound (e), and an epoxy resin (B A flexible print with a cover film, which is coated with an unpeeled plastic film through a cured adhesive layer (III) formed from an adhesive composition (I) containing It relates to a wiring board.

  Furthermore, the present invention provides a surface on the conductive circuit side of a flexible printed wiring board having a conductive circuit on the surface by peeling off the protective film from the plastic film with the adhesive layer described in the above invention and exposing the exposed adhesive layer (II). It is related with the manufacturing method of the flexible printed wiring board with a cover film characterized by heating, after making it contact and / or after making it contact.

  The present invention also provides a urethane prepolymer (d) having an isocyanate group obtained by reacting a polyol compound (a), an organic diisocyanate (b) and a diol compound (c) having a carboxyl group, and a polyamino compound (e). A plastic that has not been subjected to a release treatment with an adhesive composition (I) containing a polyurethane polyurea resin (A) having an acid value of 3 to 25 mg KOH / g and an epoxy resin (B). Apply on one side of the film to form the adhesive layer (II), and then contact the adhesive layer (II) with the conductive circuit side surface of the flexible printed wiring board having the conductive circuit on the surface. It is related with the manufacturing method of the flexible printed wiring board with a cover film characterized by heating after making it contact and / or contact.

  The present invention also provides a urethane prepolymer (d) having an isocyanate group obtained by reacting a polyol compound (a), an organic diisocyanate (b) and a diol compound (c) having a carboxyl group, and a polyamino compound (e). And an adhesive composition (I) containing a polyurethane polyurea resin (A) having an acid value of 3 to 25 mg KOH / g and an epoxy resin (B), and a conductive circuit on the surface. Applying to the surface of the flexible printed wiring board having the conductive circuit side, forming an adhesive layer (II), and then contacting the adhesive layer (II) with an unpeeled plastic film and / or It is related with the manufacturing method of the flexible printed wiring board with a cover film characterized by heating after making it contact.

  According to the present invention, it is possible to obtain a cover film with an adhesive layer that has high adhesive strength between a plastic film and a conductive circuit, has good solder heat resistance, and excellent storage stability, so that pattern embedding can be maintained for a long period of time. It is possible to provide an excellent flexible printed wiring board with a cover film.

First, the adhesive composition (I) used for the plastic film with an adhesive layer and the flexible printed wiring board with a cover film of the present invention will be described.
The polyurethane polyurea resin (A) contained in the adhesive composition (I) is a urethane having an isocyanate group obtained by reacting a polyol compound (a), an organic diisocyanate (b) and a diol compound (c) having a carboxyl group. It is obtained by reacting the prepolymer (d), the polyamino compound (e), and a reaction terminator as necessary.

  The polyol compound (a) is a polyol component other than the diol compound (c) having a carboxyl group to be described later, and is generally known as a polyol component constituting a polyurethane resin. Various polyether polyols, polyester polyols, Polycarbonate polyols, polybutadiene glycols, or a mixture thereof can be used.

  Examples of polyether polyols include polymers or copolymers such as ethylene oxide, propylene oxide, and tetrahydrofuran.

  Polyester polyols include ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,3-butanediol, 1,4-butanediol, neopentyl glycol, pentanediol, 3-methyl-1, Saturated and unsaturated low molecular weight diols such as 5-pentanediol, hexanediol, octanediol, 1,4-butylenediol, diethylene glycol, triethylene glycol, dipropylene glycol, dimer diol, and adipic acid, phthalic acid, isophthalic acid , Terephthalic acid, maleic acid, fumaric acid, succinic acid, oxalic acid, malonic acid, glutaric acid, pimelic acid, suberic acid, azelaic acid, sebacic acid and other dicarboxylic acids or their anhydrides. Polyester polio N-butyl glycidyl ether, alkyl glycidyl ethers of 2-ethylhexyl glycidyl ether, carboxylic acid glycidyl esters such as versatic acid glycidyl esters and anhydrides of the above dicarboxylic acids and hydroxyl groups such as alcohols Examples include polyester polyols obtained by reacting in the presence of the containing compound and polyester polyols obtained by ring-opening polymerization of a cyclic ester compound.

Examples of the polycarbonate polyol include 1) a reaction product of diol or bisphenol and a carbonate ester, and 2) a reaction product obtained by reacting diol or bisphenol with phosgene in the presence of an alkali.
Examples of the carbonic acid ester used in the case of 1) include dimethyl carbonate, diethyl carbonate, diphenyl carbonate, ethylene carbonate, propylene carbonate, and the like.
As the diol used in the above 1) and 2), ethylene glycol, propylene glycol, dipropylene glycol, diethylene glycol, triethylene glycol, butylene glycol, 3-methyl-1,5-pentanediol, 2-methyl-1 , 8-octanediol, 3,3′-dimethylolheptane, polyoxyethylene glycol, polyoxypropylene glycol, propanediol, 1,3-butanediol, 1,4-butanediol, 1,5-pentanediol, 1 , 6-hexanediol, 1,9-nonanediol, neopentyl glycol, octanediol, butylethylpentanediol, 2-ethyl-1,3-hexanediol, cyclohexanediol, 3,9-bis (1,1-dimethyl) -2-Hyd Roxyethyl, 2,2,8,10-tetraoxospiro [5.5] undecane and the like can be mentioned.
Examples of the bisphenol used in the cases 1) and 2) include bisphenol A, bisphenol F, and bisphenols obtained by adding alkylene oxides such as ethylene oxide and propylene oxide to bisphenols.

The number average molecular weight (Mn) of the polyol compound (a) is appropriately determined in consideration of the heat resistance, adhesive strength, solubility and the like of the resulting polyurethane polyurea resin (A), but is usually in the range of 500 to 8000. Is more preferable, and 1000 to 5000 is more preferable. When Mn is less than 500, the number of urethane bonds in the polyurethane polyurea resin (A) increases too much, the flexibility of the polymer skeleton tends to decrease and the adhesion to the polyimide film / copper foil tends to decrease. When it exceeds 8000, the molecular weight between cross-linking points tends to increase, and the solder heat resistance tends to decrease.
The polyol compound (a) may be used alone or in combination of two or more. Furthermore, within the range in which the performance of the polyurethane polyurea resin (A) is not lost, various low-molecular diols used as a part of the polyol compound (a), for example, a molecular weight of about 400 or less used for the production of the polyol compound. Molecular diols can be used instead.

  As the organic diisocyanate compound (b), aromatic diisocyanate, aliphatic diisocyanate, alicyclic isocyanate, or a mixture thereof can be used, and isophorone diisocyanate is particularly preferable.

  Aromatic diisocyanates include 1,5-naphthylene diisocyanate, 4,4′-diphenylmethane diisocyanate, 4,4′-diphenyldimethylmethane diisocyanate, 4,4′-benzyl isocyanate, dialkyldiphenylmethane diisocyanate, tetraalkyldiphenylmethane diisocyanate, 1 , 3-phenylene diisocyanate, 1,4-phenylene diisocyanate, tolylene diisocyanate, xylylene diisocyanate and the like.

  Examples of the aliphatic diisocyanate include butane-1,4-diisocyanate, hexamethylene diisocyanate, 2,2,4-trimethylhexamethylene diisocyanate, and lysine diisocyanate.

  Examples of the alicyclic diisocyanate include cyclohexane-1,4-diisocyanate, isophorone diisocyanate, norbornane diisocyanate methyl, bis (4-isocyanatocyclohexyl) methane, 1,3-bis (isocyanatemethyl) cyclohexane, methylcyclohexane diisocyanate, and the like. It is done.

  Examples of the diol compound (c) having a carboxyl group include dimethylol alkanoic acid such as dimethylolacetic acid, dimethylolpropionic acid, dimethylolbutanoic acid and dimethylolpentanoic acid, dihydroxysuccinic acid, and dihydroxybenzoic acid. In particular, dimethylolpropionic acid and dimethylolbutanoic acid are preferable from the viewpoint of reactivity and solubility.

The conditions for obtaining the urethane prepolymer (d) having an isocyanate group by reacting the polyol compound (a), the organic diisocyanate (b), and the diol compound (c) having a carboxyl group include an isocyanate group in excess. The equivalent ratio of isocyanate group / hydroxyl group is preferably in the range of 1.05 / 1 to 3/1. More preferably, it is 1.2 / 1 to 2/1. The reaction is usually carried out at a temperature between normal temperature and 150 ° C., and is preferably carried out between 60 ° C. and 120 ° C. from the viewpoints of production time and side reaction control.
The range of 1000-100000 is preferable and, as for the weight average molecular weight (Mw) of the urethane prepolymer (d) which has an isocyanate group obtained, it is more preferable that it is the range of 2000-80000. When Mw is less than 1000, the heat resistance of the formed flexible printed wiring board with cover film is inferior, and when it exceeds 100,000, the viscosity of the adhesive composition is high, and the handling property is decreased. Absent.

The polyurethane polyurea resin (A) is obtained by reacting a urethane prepolymer (d) having an isocyanate group with a polyamino compound (e).
The polyamino compound (e) functions as a chain extender, and includes ethylenediamine, propylenediamine, hexamethylenediamine, diethylenetriamine, triethylenetetramine, isophoronediamine, dicyclohexylmethane-4,4'-diamine, norbornanediamine, 2 -(2-Aminoethylamino) ethanol, 2-hydroxyethylethylenediamine, 2-hydroxyethylpropylenediamine, di-2-hydroxyethylethylenediamine, di-2-hydroxypropylethylenediamine and other amines having a hydroxyl group may also be used. it can. Of these, isophoronediamine is preferably used.

  In order to adjust the molecular weight of the resulting polyurethane polyurea resin (A) when reacting the urethane prepolymer (d) having an isocyanate group with the polyamino compound (e) to synthesize the polyurethane polyurea resin (A), a reaction terminator is used. Can be used in combination. As the reaction terminator, dialkylamines such as di-n-butylamine, dialkanolamines such as diethanolamine, and alcohols such as ethanol and isopropyl alcohol can be used.

The conditions for reacting the urethane prepolymer (d) having an isocyanate group, the polyamino compound (e), and the reaction terminator are not particularly limited, but 1 equivalent of a free isocyanate group at both ends of the urethane prepolymer. The total equivalent of amino groups in the polyamino compound (e) and the reaction terminator is preferably in the range of 0.5 to 1.3, and 50 to 100% of the total equivalents of amino groups is polyamino It is preferably derived from the compound (e). Furthermore, the total equivalent of amino groups is preferably in the range of 0.8 to 1.1, of which 70 to 100% is preferably derived from the polyamino compound (e).
When the total equivalent of amino groups is less than 0.5, the molecular weight of the polyurethane polyurea resin (A) cannot be sufficiently increased, so that the solder heat resistance is not sufficient. When the amount exceeds 1.3, the polyamino compound (e) and the reaction terminator remain in a large amount unreacted and react directly with the epoxy resin in the adhesive composition, or exhibit catalytic activity and exhibit an adhesive composition. Reduces storage stability.
The weight average molecular weight of the polyurethane polyurea resin (A) is preferably in the range of 5,000 to 500,000. When the molecular weight is less than 5,000, the solder heat resistance is inferior, and when it exceeds 500,000, the viscosity of the adhesive composition is high and the handling property is lowered, which is not preferable.

  Further, the acid value of the polyurethane polyurea resin (A) needs to be 3 to 25 mg KOH / g, and preferably 7 to 20 mg KOH / g. In addition, an acid value is an acid value by a carboxyl group, and is with respect to solid content of a polyurethane polyurea resin (A). When the acid value of the polyurethane polyurea resin (A) is smaller than 3 mg KOH / g, the crosslinking with the epoxy resin contained in the adhesive composition becomes insufficient, the heat resistance is lowered, and the solder heat resistance is not exhibited. Moreover, when an acid value is larger than 25 mgKOH / g, it crosslinks excessively with the epoxy resin contained in an adhesive composition, and the adhesive strength to the polyimide film and copper foil etc. which are adherends falls.

When synthesizing the polyurethane polyurea resin (A), an ester solvent, a ketone solvent, a glycol ether solvent, an aliphatic solvent, an aromatic solvent, an alcohol solvent, a carbonate solvent, water or the like alone , Or two or more types can be used in combination.
Examples of ester solvents include ethyl acetate, isopropyl acetate, n-butyl acetate, isobutyl acetate, amyl acetate, and ethyl lactate.
Examples of the ketone solvent include acetone, methyl ethyl ketone, methyl isobutyl ketone benzene, diisobutyl ketone, diacetone alcohol, isophorone, and cyclohexanone.

  Examples of glycol ether solvents include ethylene glycol monoethyl ether, ethylene glycol monoisopropyl ether, ethylene glycol monobutyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, propylene glycol monomethyl ether, propylene glycol monoethyl ether, and these monoethers. Examples thereof include acetates and diethers such as diethylene glycol dimethyl ether and diethylene glycol diethyl ether.

Examples of the aliphatic solvent include n-heptane, n-hexane, cyclohexane, methylcyclohexane, and ethylcyclohexane.
Examples of the aromatic solvent include toluene and xylene.
Examples of the alcohol solvent include methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, and cyclohexanol.
Examples of the carbonate solvent include dimethyl carbonate, ethyl methyl carbonate, di-n-butyl carbonate and the like.

  Of the various solvents described above, those having a hydroxyl group cannot be used for obtaining a urethane prepolymer (d) having an isocyanate group. However, when the urethane prepolymer (d) having an isocyanate group is reacted with the polyamino compound (e), a solvent having a hydroxyl group can be appropriately used. This is because the reaction between the amino group and the isocyanate group is much faster than the reaction between the hydroxyl group and the isocyanate group. When a urea bond is formed, a hydrogen bond is generated, and the viscosity of the reaction solution is extremely rapidly increased due to the hydrogen bond. When a solvent having a hydroxyl group is used in the urea formation, the influence of the hydrogen bond can be alleviated.

In addition, the epoxy resin (B) contained in the adhesive composition (I) used in the present invention is a compound having an epoxy group, which may be liquid or solid and is particularly limited. Although it is not a thing, what has an average of two or more epoxy groups in 1 molecule is used.
As the epoxy resin (B), an epoxy resin such as a glycidyl ether type epoxy resin, a glycidyl amine type epoxy resin, a glycidyl ester type epoxy resin, or a cyclic aliphatic (alicyclic type) epoxy resin can be used.

Examples of the glycidyl ether type epoxy resin include bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol S type epoxy resin, bisphenol AD type epoxy resin, cresol novolac type epoxy resin, phenol novolac type epoxy resin, α-naphthol novolak type epoxy resin. Resin, bisphenol A type novolak type epoxy resin, dicyclopentadiene type epoxy resin, tetrabromobisphenol A type epoxy resin, brominated phenol novolac type epoxy resin, tris (glycidyloxyphenyl) methane, tetrakis (glycidyloxyphenyl) ethane, etc. Can be mentioned.
Examples of the glycidylamine type epoxy resin include tetraglycidyldiaminodiphenylmethane, triglycidylparaaminophenol, triglycidylmetaaminophenol, and tetraglycidylmetaxylylenediamine.

Examples of the glycidyl ester type epoxy resin include diglycidyl phthalate, diglycidyl hexahydrophthalate, and diglycidyl tetrahydrophthalate.
Examples of the cycloaliphatic (alicyclic) epoxy resin include epoxycyclohexylmethyl-epoxycyclohexanecarboxylate, bis (epoxycyclohexyl) adipate, and the like.
An epoxy resin can be used individually by 1 type or in combination of 2 or more types.
As the epoxy resin (B), bisphenol A type epoxy resin, cresol novolac type epoxy resin, phenol novolac type epoxy resin, tris (glycidyloxyphenyl) methane, tetrakis (glycidyloxyphenyl) from the viewpoint of high adhesion and heat resistance It is preferable to use ethane.

  The adhesive composition (I) used in the present invention preferably contains 3 to 200 parts by weight of the epoxy resin (B) with respect to 100 parts by weight of the polyurethane polyurea resin (A), and contains 5 to 100 parts by weight. More preferably. When the amount of the epoxy resin (B) is less than 3 parts by weight, the solder heat resistance is hardly exhibited. When there are more epoxy resins (B) than 200 weight part, there exists a tendency for the adhesiveness with respect to a polyimide film and copper foil to fall.

  The adhesive composition (I) used in the present invention includes a curing accelerator and a curing agent for the purpose of promoting the reaction between the polyurethane polyurea resin (A) and the epoxy resin (B) and the reaction between the epoxy resins (B). Can be contained. As the curing accelerator for the epoxy resin (B), tertiary amine compounds, phosphine compounds, imidazole compounds and the like can be used, and as the curing agent, dicyandiamide, carboxylic acid hydrazide, acid anhydrides and the like can be used.

  Examples of the tertiary accelerator include triethylamine, benzyldimethylamine, 1,8-diazabicyclo (5.4.0) undecene-7, 1,5-diazabicyclo (4.3.0) nonene-5, and the like as the curing accelerator. It is done. Examples of the phosphine compound include triphenylphosphine and tributylphosphine. Examples of imidazole compounds include 2-methylimidazole, 2-ethyl-4-methylimidazole, 2-phenyl-4-methylimidazole, 2,4-dimethylimidazole, 2-phenylimidazole, and the like. A latent curing accelerator having improved storage stability such as a type in which an epoxy resin is reacted to insolubilize in a solvent or a type in which an imidazole compound is encapsulated in a microcapsule can be mentioned. Among these, a latent curing accelerator is preferable.

As the curing agent, examples of the carboxylic acid hydrazide include succinic acid hydrazide and adipic acid hydrazide. Examples of the acid anhydride include hexahydrophthalic anhydride and trimellitic anhydride.
Two or more kinds of these curing accelerators and curing agents may be used in combination, and the addition amount is preferably in the range of 0.1 to 30 parts by weight with respect to 100 parts by weight of the epoxy resin (B).

In the adhesive composition (I) used in the present invention, a filler (C) can be added for the purposes of soldering heat resistance, improving thermal conductivity, and controlling the fluidity of the adhesive.
Examples of the filler (C) include silica, alumina, aluminum hydroxide, magnesium hydroxide, barium sulfate, calcium carbonate, titanium oxide, zinc oxide, antimony trioxide, magnesium oxide, talc, montmorillonite, kaolin and bentonite. Examples include inorganic fillers, metal fillers such as aluminum, gold, silver, copper, and nickel. Among these, silica, alumina, and aluminum hydroxide are preferable from the viewpoint of dispersibility. In particular, hydrophobic silica obtained by modifying a silanol group on the silica surface with a halogenated silane can reduce the water absorption rate and is suitably used in the adhesive composition of the present invention.
The blending amount of the filler (C) is preferably 0.1 to 100 parts by weight and more preferably 0.2 to 50 parts by weight with respect to 100 parts by weight of the polyurethane polyurea resin (A).

The adhesive composition (I) used in the present invention includes a silane coupling agent, a heat stabilizer, a pigment, a dye, and a tackifying resin as long as the adhesiveness to a plastic film and a conductive circuit and solder heat resistance are not deteriorated. , Plasticizers, ultraviolet absorbers, antifoaming agents, leveling regulators and the like can be blended.
By using the heat stabilizer in combination, more excellent solder heat resistance can be imparted. As the heat-resistant stabilizer, hindered phenol-based, phosphorus (phosphite) -based, lactone-based, hydroxylamine-based, sulfur-based, and the like can be used. In particular, a hindered phenol-based heat stabilizer is effective.

Next, the plastic film with an adhesive layer of the present invention will be described.
The plastic film with an adhesive layer of the present invention is formed by sandwiching an adhesive layer (II) formed from the above adhesive composition (I) between an unpeeled plastic film and a protective film. Is.
The plastic film with an adhesive layer of the present invention is obtained by applying the adhesive composition (I) to a plastic film or a protective film that has not been subjected to release treatment by various methods, and drying the adhesive composition (I). It can be obtained by forming and superposing a protective film or a plastic film not subjected to release treatment on the adhesive layer (II).

  As a coating method of the adhesive composition (I), a conventionally known method, for example, comma coating, knife coating, die coating, lip coating, roll coating, curtain coating, bar coating, gravure printing, flexographic printing, dip coating, spraying. After applying the adhesive composition (I) by coating, spin coating or the like, the adhesive layer (II) can be obtained usually by drying at 40 to 150 ° C.

  The plastic film which has not been peeled is used to cover the conductive circuit of the flexible printed wiring board, and is also called a cover film. Examples of the plastic film that has not been subjected to release treatment include plastic films such as polyester, polyolefin, polyimide, and polyamide that are not coated with a release agent containing silicone or a fluorine compound, and polyimide films are preferred.

  A protective film here is for protecting the adhesive bond layer of a plastic film with an adhesive bond layer. As long as the protective film can be peeled off from the plastic film with the adhesive layer when covering the conductive circuit of the flexible printed wiring board, the protective film may be one that is not specially peeled off, and various types are used. Can do. For example, a film obtained by coating a plastic film such as polyester, polyolefin, polyimide, polyamide or the like with a release agent containing silicone or a fluorine compound can be used.

Next, the flexible printed wiring board with a cover film of this invention and its manufacturing method are demonstrated.
A flexible printed wiring board is obtained by providing a conductive circuit on a base film such as a polyimide film by various methods.
As a method for providing a conductive circuit, for example, a photosensitive etching resist layer is formed on a copper foil of a flexible copper-clad plate in which a copper foil is provided on a base film with or without an adhesive layer. Expose the conductive circuit from the copper foil by exposing it through a mask film with a pattern, curing only the exposed area, then removing the unexposed area of the copper foil by etching, and then peeling off the remaining resist layer. Can be formed. Alternatively, only a necessary circuit may be provided on the base film by means such as sputtering or plating.
Examples of the flexible printed wiring board used in the present invention include those having a conductive circuit on one surface, those having a conductive circuit on both surfaces, and those having a conductive circuit inside thereof.

Suitable as the base film is a plastic film having insulating properties, flexibility and heat resistance, such as polyimide, polyethylene terephthalate (PET), polyphenylene sulfide, polyethersulfone, polyetheretherketone, aramid, polycarbonate, polyarylate. And liquid crystal polymers represented by wholly aromatic polyamides and wholly aromatic polyesters.
As the copper foil, electrolytic copper foil or rolled copper foil can be used.

The flexible printed wiring board with a cover film of the present invention is a cured adhesive layer formed from the adhesive composition (I) on the surface of the flexible printed wiring board having a conductive circuit on the surface thereof on the conductive circuit side ( It is formed by coating with a plastic film not subjected to release treatment via III).
The flexible printed wiring board with a cover film of the present invention can be obtained by various production methods.
For example, the protective film is peeled off from the plastic film with the adhesive layer, and the exposed adhesive layer (II) is heated while contacting the surface of the flexible printed wiring board having the conductive circuit on the surface thereof on the conductive circuit side, The adhesive layer (II) can be cured by heating after the contact to obtain the flexible printed wiring board with a cover film of the present invention.
Further, the adhesive composition (I) is applied on a plastic film that has not been subjected to a release treatment and dried to form an adhesive layer (II), and then the adhesive layer (II) is formed on a flexible printed wiring board. It is possible to obtain a flexible printed wiring board with a cover film according to the present invention by heating while contacting the surface of the conductive circuit side, or heating after contacting, and curing the adhesive layer (II). it can.
Alternatively, the adhesive composition (I) is applied to the surface of the flexible printed wiring board on the conductive circuit side and dried to form the adhesive layer (II), and then the adhesive layer (II) is peeled off. It is possible to obtain a flexible printed wiring board with a cover film according to the present invention by heating while making contact with an untreated plastic film, or by heating after making contact and curing the adhesive layer (II). .
In addition, the application method of adhesive composition (I) can illustrate similarly the method described in the case of the plastic film with an adhesive layer.

In either case, pressure can be applied when and / or after bonding the adhesive layer (II) and the surface on the conductive circuit side. More specifically, a laminate composed of a plastic film / adhesive layer (II) / flexible printed wiring board that has not been peeled is passed between two heated rolls, or the laminate is hot pressed. By this, a cover film can be more firmly affixed on a flexible printed wiring board.
Moreover, after a cover film is affixed on a flexible printed wiring board, it can further heat and hardening of adhesive bond layer (II) can also be advanced.
For example, this adhesive layer (II) can be made into a cured adhesive layer (III) by heating, for example, heating at 100 to 200 ° C. for about 30 minutes to 24 hours. The film thickness of the adhesive layer (III) is preferably 5 μm to 100 μm, more preferably 10 μm to 50 μm.
Thus, the flexible printed wiring board with a cover film obtained as mentioned above will be in the state by which the cover film and the conductive circuit side of the flexible printed wiring board were bonded together through the hardened | cured adhesive bond layer (III).

Next, the present invention will be described in more detail with reference to examples, but the present invention is not limited thereto. In the examples, parts and% mean parts by weight and% by weight, Mn means number average molecular weight, and Mw means weight average molecular weight, respectively.
[Synthesis Example 1]
Polyester polyol (made by Kuraray Co., Ltd.) obtained from terephthalic acid, adipic acid and 3-methyl-1,5-pentanediol in a reaction vessel equipped with a stirrer, a thermometer, a reflux condenser, a dropping device, and a nitrogen introduction tube. Kuraray polyol P-2011 ", Mn = 2040) 195.2 parts, 6.67 parts dimethylolbutanoic acid, 40.7 parts isophorone diisocyanate, 70.0 parts toluene, and reacted at 90 ° C for 4 hours in a nitrogen atmosphere. To this was added 250 parts of toluene to obtain a urethane prepolymer solution having an isocyanate group with Mw = 21,000.
Next, the urethane prepolymer solution 506.3 having the above isocyanate group in a mixture of 6.08 parts of isophoronediamine, 0.59 parts of di-n-butylamine, 112.5 parts of 2-propanol, and 184.5 parts of toluene. A polyurethane polyurea resin solution A-1 having Mw = 110,000, acid value = 10.1 mg KOH / g, and solid content of about 25% was obtained.

[Synthesis Example 2]
In a reaction vessel similar to Synthesis Example 1, 195.0 parts of polyoxytetramethylene glycol (“PTG-2000SN”, Mn = 2029, manufactured by Hodogaya Chemical Co., Ltd.), 6.70 parts of dimethylolbutanoic acid, 40 of isophorone diisocyanate 8 parts and 70.0 parts of toluene were reacted in a nitrogen atmosphere at 90 ° C. for 4 hours, and 250 parts of toluene was added thereto to obtain a urethane prepolymer solution having an isocyanate group with Mw = 22,000.
Next, a urethane prepolymer solution 506 containing the above isocyanate group in a mixture of 6.11 parts of isophoronediamine, 0.59 parts of di-n-butylamine part, 112.5 parts of 2-propanol, and 184.5 parts of toluene. .3 parts were added and reacted at 85 ° C. for 4 hours to obtain a polyurethane polyurea resin solution A-2 having Mw = 105,000, acid value = 10.2 mgKOH / g, and solid content of about 25%.

[Synthesis Example 3]
In a reaction vessel similar to that in Synthesis Example 1, 193.6 parts of polyhexamethylene carbonate diol ("Placcel CD220" manufactured by Daicel Chemical Industries, Ltd., Mn = 1965), 6.87 parts of dimethylolbutanoic acid, 41. 9 parts and 70.0 parts of toluene were charged and reacted at 90 ° C. for 4 hours under a nitrogen atmosphere, and 250 parts of toluene was added thereto to obtain a urethane prepolymer solution containing Mw = 20,000 and containing an isocyanate group.
Next, a urethane prepolymer solution 506.1 containing the above isocyanate in a mixture of 6.26 parts of isophoronediamine, 0.61 part of di-n-butylamine, 112.5 parts of 2-propanol, and 184.5 parts of toluene. A polyurethane polyurea resin solution A-3 having Mw = 88,000, acid value = 10.4 mgKOH / g, and solid content of about 25% was obtained.

[Synthesis Example 4]
In the same reaction vessel as in Synthesis Example 1, polyester polyol obtained from terephthalic acid, adipic acid and 3-methyl-1,5-pentanediol (“Kuraray Polyol P-2011”, Mn = 2040) 209 manufactured by Kuraray Co., Ltd. .4 parts, 1.69 parts of dimethylolbutanoic acid, 32.9 parts of isophorone diisocyanate, and 70.0 parts of toluene were reacted in a nitrogen atmosphere at 90 ° C. for 4 hours. To this, 250 parts of toluene was added, and Mw = 23. 1,000, urethane prepolymer solution having an isocyanate group was obtained.
Next, a urethane prepolymer solution having the above isocyanate group in a mixture of 4.93 parts of isophoronediamine, 0.48 parts of di-n-butylamine, 112.5 parts of 2-propanol, and 184.5 parts of toluene 6 parts were added and reacted at 85 ° C. for 4 hours to obtain a polyurethane polyurea resin solution A-4 having Mw = 120,000, acid value = 2.6 mgKOH / g, and solid content of about 25%.

[Synthesis Example 5]
In a reaction vessel similar to Synthesis Example 1, polyester polyol obtained from terephthalic acid, adipic acid and 3-methyl-1,5-pentanediol ("Kuraray Polyol P-2011" manufactured by Kuraray Co., Ltd., Mn = 2040) 155 0.0 part, 20.9 parts of dimethylolbutanoic acid, 62.7 parts of isophorone diisocyanate, and 70.0 parts of toluene were reacted in a nitrogen atmosphere at 90 ° C. for 4 hours, 250 parts of toluene was added thereto, and Mw = 19 1,000, urethane prepolymer solution having an isocyanate group was obtained.
Next, in a mixture of 9.38 parts of isophoronediamine, 0.91 part of di-n-butylamine, 112.5 parts of 2-propanol, and 184.5 parts of toluene, the urethane prepolymer solution having the above isocyanate group 502. 7 parts were added and reacted at 85 ° C. for 4 hours to obtain a polyurethane polyurea resin solution A-5 having Mw = 94,000, acid value = 31.7 mgKOH / g, and solid content of about 25%.

[Synthesis Example 6]
In the same reaction vessel as in Synthesis Example 1, polyester polyol obtained from terephthalic acid, adipic acid and 3-methyl-1,5-pentanediol (“Kuraray Polyol P-2011” manufactured by Kuraray Co., Ltd., Mn = 2040) 482 9 parts, 16.5 parts of dimethylolbutanoic acid, 100.6 parts of isophorone diisocyanate, and 70.0 parts of toluene were reacted in a nitrogen atmosphere at 90 ° C. for 4 hours, 330 parts of toluene was added thereto, and Mw = 21 1,000, urethane prepolymer solution having an isocyanate group was obtained.

In addition, the weight average molecular weight of polyurethane polyurea resin is the weight average molecular weight of polystyrene conversion calculated | required by GPC measurement, and GPC measurement conditions are as follows.
Apparatus: Shodex GPC System-21 (manufactured by Showa Denko KK)
Column: A total of 3 columns, Shodex KF-802, KF-803L, KF-805L (manufactured by Showa Denko Co., Ltd.), are connected and used.
Solvent: Tetrahydrofuran Flow rate: 1.0 ml / min
Temperature: 40 ° C
Sample concentration: 0.2% by weight
Sample injection volume: 100 μl

[Example 1]
Tetrakis (glycidyloxyphenyl) ethane (“Epicoat 1031S” manufactured by Japan Epoxy Resin Co., Ltd., epoxy equivalent = 180 to 220 g / eq) with respect to 400 parts of the polyurethane polyurea resin solution A-1 obtained in Synthesis Example 1 10 parts and 20 parts of hydrophobic silica filler (“Nippil SS-50F” manufactured by Tosoh Silica Co., Ltd.) were mixed to obtain an adhesive composition.
This adhesive composition is applied to a 25 μm-thick polyimide film (manufactured by Toray Industries, Inc., Kapton 100H) so that the dry film thickness is 25 μm, dried at 80 ° C. for 2 minutes, and a protective film (silicone) is applied to the adhesive surface. And a cover film with an adhesive layer was prepared.

[Examples 2-5 and Comparative Examples 1-2]
Adhesive composition and adhesion in exactly the same manner as in Example 1 except that the type and amount of polyurethane polyurea resin (A) solution, epoxy resin (B), and filler (C) shown in Table 1 were used. A cover film with an agent layer was produced.

Abbreviations in Table 1 are shown below.
EP828: Bisphenol A type epoxy resin (“Epicoat 828” manufactured by Japan Epoxy Resin Co., Ltd., epoxy equivalent = 189 g / eq)
EP152: Phenol novolac type epoxy resin (“Epicoat 152” manufactured by Japan Epoxy Resin Co., Ltd., epoxy equivalent = 172 to 178 g / eq)
1031S: Tetrakis (glycidyloxyphenyl) ethane (“Epicoat 1031S” manufactured by Japan Epoxy Resin Co., Ltd., epoxy equivalent = 180 to 220 g / eq)
SS-50F: Hydrophobic silica filler (“Nippil SS-50F” manufactured by Tosoh Silica Co., Ltd.)
R972: Hydrophobic silica filler (“AEROSIL R972” manufactured by Nippon Aerosil Co., Ltd.)

[Comparative Example 3]
Carboxyl group-containing nitrile butadiene rubber (“Nipol 1072J” manufactured by Nippon Zeon Co., Ltd., bound acrylonitrile amount 27.0%, Mooney viscosity 48) 100 parts, bisphenol A type epoxy resin “Epicoat 828” 200 parts, anhydrous silica filler “Aerosil” 2 parts of 300 ", 14 parts of finely pulverized dicyandiamide" Epicure DICY7 "and 2 parts of imidazole curing accelerator" Amicure PN-40 "were dissolved in toluene so that the solid content was 30%, and the adhesive composition A product was made.
A cover film with an adhesive layer was prepared in exactly the same manner as in Example 1 using the obtained adhesive composition.

[Comparative Example 4]
In a reactor similar to Synthesis Example 1, 95.0 parts of butyl acrylate, 5.0 parts of acrylic acid, 163.0 parts of ethyl acetate, 0.06 part of 2,2′-azobisisobutyronitrile were charged. After the air in the reaction vessel was replaced with nitrogen gas, the reaction solution was heated to 80 ° C. and reacted for 9 hours in a nitrogen atmosphere with stirring. After completion of the reaction, 57 parts of toluene was added to obtain an acrylic resin solution having a solid content of 30.0%.
In 133 parts of this acrylic resin solution, 10 parts of bisphenol A type epoxy resin “Epicoat 828”, 0.1 part of silica filler “Aerosil 300”, 0.7 part of finely pulverized dicyandiamide “Epicure DICY7”, and imidazole curing accelerator 0.1 part of “Amicure PN-40” was blended to obtain an adhesive composition.
A cover film with an adhesive layer was prepared in exactly the same manner as in Example 1 using the obtained adhesive composition.

[Comparative Example 5]
For 167 parts of the urethane prepolymer resin obtained in Synthesis Example 6, 20 parts of bisphenol A type epoxy resin (“Epicoat 1001” manufactured by Japan Epoxy Resin Co., Ltd., epoxy equivalent = 450 to 500 g / eq) and diaminodiphenyl 8 parts of sulfone (“Seika Cure-S” manufactured by Wakayama Seika Kogyo Co., Ltd.) and 30 parts of hydrophobic silica filler (“Nipsil SS-50F” manufactured by Tosoh Silica Co., Ltd.) were mixed to prepare an adhesive composition.
A cover film with an adhesive layer was prepared in exactly the same manner as in Example 1 using the obtained adhesive composition.

For the cover films with adhesive layers obtained in Examples and Comparative Examples, the adhesive strength, solder heat resistance after humidification, pattern embedding after storage stability test, and change in insulation resistance value were evaluated by the following methods. . The results are shown in Table 2.
(1) Adhesive strength The protective film of the cover film with an adhesive layer is peeled off and bonded to the matte surface of an electrolytic copper foil having a thickness of 35 μm using a thermal laminator with a roll temperature of 100 ° C., and then 150 ° C. and 1.0 MPa. It heat-pressed on conditions for 2 minutes, and also it heated for 180 minutes with 150 degreeC electric oven, and produced the electrolytic copper foil with a cover film.
The electrolytic copper foil with the cover film is cut to a width of 10 mm, and a 180 ° peel peel test is performed between the cover film and the electrolytic copper foil at a tensile rate of 50 mm / min in an atmosphere of 23 ° C. and a relative humidity of 50%. The adhesive strength (N / cm) was determined.

(2) Solder heat resistance after humidification The above-mentioned electrolytic copper foil with a cover film is cut to a width of 10 mm and immersed in purified water at 85 ° C. for 3 hours, and immediately the cover film side is melted at 260 ° C. for 1 minute. , Contact. The appearance was visually observed, and the presence or absence of adhesion abnormality such as foaming, floating, and peeling of the adhesive layer was observed.
○: No adhesion abnormality.
Δ: Some adhesion abnormality is observed.
X: Adhesion abnormality occurred.

(3) Pattern embedding after storage stability test A flexible copper-clad laminate in which a protective film is peeled off from a cover film with an adhesive layer left in a constant temperature bath at 40 ° C. for 30 days, and a comb-shaped conductor pattern is formed by a subtractive method (Line / space 0.1 mm), using a thermal laminator with a roll temperature of 100 ° C., then heat-pressed under the conditions of 150 ° C., 1.0 MPa, 2 min, and heated in an electric oven at 150 ° C. for 180 min. Thus, a flexible copper-clad laminate having a comb-shaped conductor pattern with a cover film was obtained. The filling property of the cover film adhesive layer into the comb-shaped conductor pattern portion was visually observed to check for the presence of voids.
○: No void.
Δ: Slight voids are observed.
X: Many voids are observed.
(4) Change in insulation resistance The protective film was peeled off from the cover film with an adhesive layer, and a flexible copper-clad laminate (line / space 0.3 mm) having a comb-shaped conductor pattern formed by a subtractive method, with a roll temperature of 100 ° C. After laminating using a thermal laminator, heat press under conditions of 150 ° C., 1.0 MPa, 2 min, heat for 180 min in an electric oven at 150 ° C., and flexible copper-clad with comb conductor pattern with cover film A laminate was obtained. This flexible copper-clad laminate having a comb-shaped conductor pattern with a cover film was applied with a voltage of 24 V and 1000 Hrs between the comb-shaped conductors in an atmosphere of 85 ° C. and 85% RH (relative humidity). The resistance values between the comb-shaped conductors before and after voltage application in a humidified atmosphere were compared.
○: The absolute value of the rate of change of the resistance value is less than 20%.
Δ: The absolute value of the change rate of the resistance value is 20% or more.

Schematic sectional view of a flexible printed wiring board covered with a cover film with an adhesive layer

Explanation of symbols

1: Flexible printed wiring board 2: Conductive circuit 3: Cured adhesive layer (III)
4: Plastic film

Claims (5)

Urethane prepolymer having an isocyanate group obtained by reacting a polyol compound (a), an organic diisocyanate (b) and a diol compound having a carboxyl group (c) between a plastic film not subjected to a release treatment and a protective film ( An adhesive composition (I) obtained by reacting d) with a polyamino compound (e) and containing a polyurethane polyurea resin (A) having an acid value of 3 to 25 mg KOH / g and an epoxy resin (B) A plastic film with an adhesive layer formed by sandwiching an adhesive layer (II) formed from An isocyanate group obtained by reacting a polyol compound (a), an organic diisocyanate (b), and a diol compound (c) having a carboxyl group on the surface of the flexible printed wiring board having a conductive circuit on the surface thereof. A polyurethane polyurea resin (A) obtained by reacting a urethane prepolymer (d) having a polyamino compound (e) with an acid value of 3 to 25 mg KOH / g, and an epoxy resin (B) A flexible printed wiring board with a cover film, which is covered with a plastic film not subjected to a release treatment via a cured adhesive layer (III) formed from the agent composition (I). While peeling the protective film from the plastic film with an adhesive layer according to claim 1 and exposing the exposed adhesive layer (II) to the surface of the flexible printed wiring board having the conductive circuit on the surface, And after making it contact, the manufacturing method of the flexible printed wiring board with a cover film characterized by heating. Obtained by reacting a urethane prepolymer (d) having an isocyanate group obtained by reacting a polyol compound (a), an organic diisocyanate (b) and a diol compound (c) having a carboxyl group with a polyamino compound (e). An adhesive composition (I) containing a polyurethane polyurea resin (A) having an acid value of 3 to 25 mg KOH / g and an epoxy resin (B) is applied to one side of a plastic film that has not been subjected to a release treatment. Apply and form an adhesive layer (II), and then contact the adhesive layer (II) with the conductive circuit side surface of the flexible printed wiring board having a conductive circuit on the surface and / or contact A method for producing a flexible printed wiring board with a cover film, which is heated after being heated. Obtained by reacting a urethane prepolymer (d) having an isocyanate group obtained by reacting a polyol compound (a), an organic diisocyanate (b) and a diol compound (c) having a carboxyl group with a polyamino compound (e). An adhesive composition (I) containing a polyurethane polyurea resin (A) having an acid value of 3 to 25 mg KOH / g and an epoxy resin (B) is formed on a surface of a flexible printed wiring board having a conductive circuit. Applying to the surface of the conductive circuit side, forming the adhesive layer (II), and then heating the adhesive layer (II) while contacting and / or contacting the unpeeled plastic film A method for producing a flexible printed wiring board with a cover film, comprising:

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