JP3637934B2 - Method for manufacturing flexible printed circuit board - Google Patents

Description

【００４２】
実施例１
厚み３５μｍの電解銅箔の粗面に参考例１で得られたポリマ−溶液を、ポリマ−層が５０μｍとなるように塗布し、８０℃で６０分間乾燥させた。
次いで、同様の電解銅箔の粗面を重ね、１０ｋｇ／ｃｍ² 、１６０℃で３０分間あるいは２００℃で３０分間加熱圧着して厚み１２０μｍの積層体を得た。
得られた積層体であるフレキシブルプリント基板は、従来公知のフレキシブルプリント基板と比較して格段に柔軟（小さく折り曲げ可能）であった。
これらの積層体の９０°ピ−ル剥離強度を表２に示す。
半田耐熱性は３分以上良好であった。
【００４３】
実施例２〜４
ポリマ−溶液の種類を参考例１で得られたポリマ−溶液から参考例２〜４で得られたポリマ−溶液に変えた他は実施例１と同様に実施した。
結果を纏めて表２に示す。
半田耐熱性はいずれも３分以上良好であった。
【００４４】
実施例５〜８
加熱圧着条件を変えて、１０ｋｇ／ｍｍ² 、１６０℃で３分間加熱圧着した後、無荷重で１６０℃で６０分間加熱して積層体を得た。
得られた積層体であるフレキシブルプリント基板は、従来公知のフレキシブルプリント基板と比較して格段に柔軟（折り曲げ可能）であった。
これらの積層体の９０°ピ−ル剥離強度を表３に示す。
半田耐熱性はいずれも３分以上良好であった。
【００４５】
比較例１
市販のポリイミド系２層基板（新日鉄化学株式会社製、エスパネックス）について同様に評価した。
９０°ピ−ル剥離強度は１．１３Ｋｇ／ｃｍであり、ポリマ−層は引張強度が１６ｋｇ／ｍｍ² 、伸びが７３％、初期弾性率が１５６ｋｇ／ｍｍ² であった。
反発力が大きなフレキシブルプリント基板である。
【００４６】
【表２】

【００４７】
【表３】

【００４８】
【発明の効果】
この発明は前述のような構成からなるので、以下に示すような効果を奏するのである。
【００４９】
この発明の方法によれば、従来のフレキシブルプリント基板の製造におけるような加熱圧着時の高温、高圧の圧着条件を必要とせず、金属箔に悪影響を及ぼさないゆるやかな条件でフレキシブルプリント基板を製造することができる。
【００５０】
また、この発明のフレキシブルプリント基板は、柔軟でかつ耐熱性が高く、ポリマ−層がある程度の強度を有しているため、コンパクトの要求される分野でも使用することができる。[0001]
  That is, the present invention relates to a method for producing a flexible printed circuit board. Specifically, a flexible printed circuit board is produced by directly applying a polymer solution mainly composed of polyimide siloxane onto a conductor which is a metal foil.On the wayIt is related.
[0002]
According to the method of the present invention, there is no need for high-temperature and high-pressure pressure bonding conditions during thermocompression bonding in the production of conventional flexible printed circuit boards, and the obtained laminate has both flexibility and heat resistance. ing.
[0003]
[Prior art]
Conventionally, a flexible printed circuit board has been manufactured by bonding a polyimide resin onto a conductor using an adhesive such as an epoxy resin, and the polyimide film itself has excellent heat resistance, but the heat resistance of the epoxy resin. There was a problem that swelling and peeling occurred when heated to a high temperature in the mounting stage.
[0004]
Therefore, as a means to solve this problem, polyimide resin is directly bonded to metal foil as a conductor, but conventionally used polyimide resin is a polyimide precursor when applied to metal foil Therefore, since heat treatment at 350 to 450 ° C. is necessary, there is a problem of thermal deterioration of the copper foil.
[0005]
Furthermore, a flexible printed circuit board in which a polyimide film and a copper foil are laminated using thermoplastic polyimide instead of an epoxy resin has also been proposed, but because the film is rigid, the flexible printed circuit board is due to the repulsive force of the film. Was difficult to load onto a compact substrate.
[0006]
[Problems to be solved by the invention]
An object of the present invention is to provide a method for producing a flexible printed circuit board which can be cured at a low temperature and has a small repulsive force by using a specific polymer in order to solve the problems of the conventional flexible printed circuit board. That is.
[0007]
[Means for Solving the Problems]
  That is, the present invention relates to a roughened surface of a metal foil, wherein the polymer component is an aromatic tetracarboxylic dianhydride or a derivative thereof, an aromatic diamine, an aromatic diamine having an OH group or a COOH group in the benzene ring, and Polyimide siloxane obtained by polymerizing and imidizing diamine composed of diaminopolysiloxaneFrom 50 parts by weight or less of epoxy resin to 100 parts by weightAfter directly applying the polymer solution, the organic solvent is removed by heating and drying, and the polymer layer is overlaid with a roughened surface of another metal foil, and at the same time or at a temperature and pressure of 140 ° C. or higher and 250 ° C. or lower. The present invention relates to a method for producing a flexible printed board characterized in that the polymer is cured separately.
[0008]
This inventionAccording to the flexibilityAnd 90 ° peel strength of the laminate is 0.6 kg / cm or more, and has heat resistance that does not cause blistering even if held in a 300 ° C solder bath for 3 minutes. The initial elastic modulus of the polymer layer is 10 to 130 kg / mm²Flexible printed circuit boardCan be obtained.
[0009]
The polyimide siloxane mainly constituting the polymer component in the present invention is, for example, an aromatic tetracarboxylic dianhydride or derivative thereof (ester, etc.) and an aromatic diamine, and an aromatic diamine having an OH group or a COOH group in the benzene ring. And a diamine comprising diaminopolysiloxane are preferably obtained by polymerization in an organic solvent and then imidization by a thermal imidization method or a chemical imidization method.
[0010]
Examples of the aromatic tetracarboxylic dianhydride or derivatives thereof include 2,3,3 ′, 4′-biphenyltetracarboxylic acid, 3,3 ′, 4,4′-biphenyltetracarboxylic acid, and 3,3. ', 4,4'-diphenyl ether tetracarboxylic acid, 3,3', 4,4'-diphenylsulfone tetracarboxylic acid, 3,3 ', 4,4'-benzophenone tetracarboxylic 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) Aromatic tetracarboxylic acids containing 80 mol% or more of) phenyl] propane, or their anhydrides or esterified products of lower alcohols are used.
Among these, in particular, 2,3,3 ′, 4′-biphenyltetracarboxylic dianhydride, 3,3 ′, 4,4′-diphenyl ether tetracarboxylic dianhydride, 2,2-bis Since [4- (3,4-phenoxydicarboxylic acid) phenyl] propane, their anhydrides, lower alcohols or derivatives thereof have a flexible structure, the repulsive force of the laminate is small, and the polyimidesiloxane It is suitable because of its excellent solubility in organic solvents.
In this case, 50 mol% or less thereof may be replaced with the other aromatic tetracarboxylic dianhydride or derivative thereof.
In this invention, 2,3,3 ', 4'-biphenyltetracarboxylic dianhydride is particularly suitable.
[0011]
Examples of the aromatic diamine include one benzene such as 1,4-diaminobenzene, 1,3-diaminobenzene, 2,4-diaminotoluene, 1,4-diamino, and 2,5-dihalogenobenzene. Diamines, 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-tolidine, toldi Diamines containing two benzenes such as sulfonic acids, 1,4-bis (4-aminophenoxy) benzene, 1,4-bis (3-aminophenoxy) benzene, 1,4-bis (4-aminophenyl) benzene 1,4-bis (3-aminophenyl) benzene, α, α′-bis (4-aminophenyl) -1,4-diisopropylbenzene, α, α′-bis (4-aminophenyl) -1,3 -Diamines containing three benzenes such as 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-bis (4-a And diamines containing 4 or more benzenes such as minophenyl) fluorene and 5,10-bis (4-aminophenyl) anthracene.
In particular, 2,2-bis [4- (4-aminophenoxy) phenyl] propane is preferred as the aromatic diamine because of its availability and the thermal stability of the resulting polyimidesiloxane.
[0012]
Examples of the aromatic diamine compound having an OH group or a COOH group 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′-tetra Hydroxybiphenyl compounds such as hydroxybiphenyl, 3,3′-diamino, 4,4′-dihydroxydiphenylmethane, 4,4′-diamino, 3,3′-dihydroxydiphenylmethane, 4,4′-diamino, 2, 2'-dihydroxydiphenylmethane, 2,2-bis [3-amino, 4-hydroxyphenyl] propane, 2,2-bis 4-amino, 3-hydroxyphenyl] propane, 2,2-bis [3-amino, 4-hydroxyphenyl] hexafluoropropane, 4,4′-diamino, 2,2 ′, 5,5′-tetrahydroxydiphenylmethane Hydroxydiphenylalkane compounds such as 3,3′-diamino, 4,4′-dihydroxydiphenyl ether, 4,4′-diamino, 3,3′-dihydroxydiphenyl ether, 4,4 ′ Hydroxydiphenyl ether compounds such as diamino, 2,2′-dihydroxydiphenyl ether, 4,4′-diamino, 2,2 ′, 5,5′-tetrahydroxydiphenyl ether, 3, 3'-diamino, 4,4'-dihydroxydiphenylsulfone, 4,4'-diamino, 3,3'-dihydroxydi Hydroxydiphenylsulfone compounds such as phenylsulfone, 4,4′-diamino, 2,2′-dihydroxydiphenylsulfone, 4,4′-diamino, 2,2 ′, 5,5′-tetrahydroxydiphenylsulfone, 2 , 2-bis [4- (4-amino, 3-hydroxyphenoxy) phenyl] propane and other bis (hydroxyphenoxyphenyl) alkane compounds, 4,4′-bis (4-amino, 3-hydroxyphenoxy) biphenyl Bis (hydroxyphenoxy) biphenyl compounds such as bis (hydroxyphenoxyphenyl) sulfone compounds such as 2,2-bis [4- (4-amino, 3-hydroxyphenoxy) phenyl] sulfone, 3,5-diamino Cite diaminobenzoic acid such as benzoic acid Can do.
[0013]
As said diamino polysiloxane, the number of siloxane bonds is 5-30, Especially the thing of 5-20 is preferable. Since diaminopolysiloxane is usually produced as a mixture of compounds having a number of siloxane bonds of 3 to 100, the number of siloxane bonds is an average value. Specific examples of 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) ) Examples include polydimethylsiloxane.
[0014]
In the polyimide siloxane in this invention, the ratio of each component in the diamine component consisting of aromatic diamine, aromatic diamine having OH group or COOH group and diaminopolysiloxane is 0-50 mol%, especially 5 -50 mol%, aromatic diamine having an OH group or COOH group is 1 to 40 mol%, particularly 2 to 40 mol%, among which 5 to 35 mol%, especially diaminopolysiloxane is 30 to 80 mol% (total of 100 Mol%), particularly 40 to 80 mol%, and particularly preferably 45 to 75 mol%.
[0015]
The polyimidesiloxane in this invention is obtained by the following method, for example.
A method for obtaining polyimidesiloxane by polymerizing and imidizing continuously at 15 to 250 ° C. in an organic polar solvent, using approximately equimolar amounts of an aromatic tetracarboxylic acid component, a diaminopolysiloxane and an aromatic diamine diamine component .
[0016]
Alternatively, the diamine component is divided, and first, an excess amount of the aromatic tetracarboxylic acid component and diaminopolysiloxane are polymerized and imidized in an organic polar solvent at 15 to 250 ° C., and the terminal has an average degree of polymerization of about 1 to 10. An imide siloxane oligomer having an acid or acid anhydride group is prepared, and an aromatic tetracarboxylic acid component and an excess amount of aromatic diamine are separately polymerized and imidized in an organic polar solvent at 15 to 250 ° C. An imide oligomer having an amino group at the terminal with a degree of polymerization of about 1 to 10 is prepared, and then both are mixed so that the acid component and the diamine component are approximately equimolar and reacted at 15 to 60 ° C., A method of further increasing the temperature to 130 to 250 ° C. to obtain a block type polyimidesiloxane.
[0017]
Alternatively, the aromatic tetracarboxylic acid component and the diaminopolysiloxane and the diamine component of the aromatic diamine are used in approximately equimolar amounts, and after first polymerizing at 20 to 80 ° C. in an organic polar solvent to obtain a polyamic acid once, There is a method of obtaining polyimide siloxane by imidization.
[0018]
Examples of the organic polar solvent used in obtaining the polyimidesiloxane include nitrogen-containing solvents such as N, N-dimethylacetamide, N, N-diethylacetamide, N, N-dimethylformamide, N, N-diethylformamide, N-methyl-2-pyrrolidone, 1,3-dimethyl-2-imidazolidinone, N-methylcaprolactam and other solvents containing sulfur atoms, such as dimethyl sulfoxide, diethyl sulfoxide, dimethyl sulfone, diethyl sulfone, hexamethylsulfol Amides, phenolic solvents such as cresol, phenol, xylenol, diglyme solvents such as diethylene glycol dimethyl ether (diglyme), triethylene glycol dimethyl ether (triglyme), tetraglyme, oxygen The solvent having a child in the molecule, such as acetone, methanol, ethanol, ethylene glycol, dioxane, tetrahydrofuran, and 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.
[0019]
In the present invention, the polyimide siloxane obtained by any of the above methods may be used. However, the polyimide siloxane is as high in molecular weight as possible, has a high imidization ratio, and is at least 3% by weight, preferably 5% in the organic polar solvent. It can be dissolved at a high concentration of ˜60% by weight, especially 5˜50% by weight, and the solution viscosity at 25 ° C. (E-type rotational viscometer) is 1 to 10000 poise, especially 10 to 2000 poise. Is preferred.
[0020]
The imidation ratio of polyimidesiloxane is preferably 90% or more, particularly preferably 95% or more. Logarithmic viscosity (measurement concentration: 0.5 g / 100 ml, solvent: N-methyl-2-pyrrolidone, measurement temperature) : 30 ° C.) is 0.16 or more, preferably 0.17 or more, particularly 0.17 to 2 in terms of storage stability (viscosity change coefficient) of the composition and solder heat resistance of the laminate. preferable.
[0021]
In the present invention, the above-mentioned polymer containing polyimide siloxane as a main component is used, but an epoxy resin may be used in a small amount.
In this case, the epoxy resin to be used (hereinafter sometimes simply referred to as epoxy) is preferably a liquid or solid epoxy resin having an epoxy equivalent of about 100 to 1000 and a molecular weight of about 300 to 5000. . For example, bisphenol A type or bisphenol F type epoxy resin (Oilized Shell: Epicoat 806, Epicoat 825, etc.), trifunctional or higher epoxy resin (Oilized Shell: Epicoat 152, Epicoat 154, Epicoat 180 series, Epicoat 157 series, Epicoat 1032 series, Ciba-Geigy: MT0163 and the like.
[0022]
In this invention, the usage-amount of an epoxy resin is an amount below 50 weight part with respect to 100 weight part of polyimide siloxane, Preferably it is 1-50 weight part, Most preferably, it is 5-40 weight part. If the amount used is too large or too small, the composition will gel, and the heat resistance and chemical resistance will deteriorate after curing, so the above range is preferred.
[0023]
You may use the additive component which accelerates | stimulates hardening of epoxy resins, such as hydrazides and imidazoles, with an epoxy resin.
[0024]
In this invention, an inorganic filler may be used together with the polymer.
As such an inorganic filler, it is preferable to use at least one kind of talc, mica or barium sulfate. The mica and barium sulfate may be of any size and form, but have an average particle diameter. Of 0.1 to 25 μm, for example, HiMod450 (average particle size: 17 μm), C-4000 (average particle size: 22 μm) manufactured by Shiroishi Kogyo Co., Ltd. or MK-100 (average particle size) manufactured by Co-op Chemical Co., Ltd. : 2.6 μm) is preferable. In barium sulfate, for example, B-30 and B-54 manufactured by Sakai Kogyo Co., Ltd. are preferable. Use of a material outside this range is not preferable because a crack is generated when the resulting polymer layer is bent or the bent portion is whitened.
[0025]
In this invention, the usage-amount of an inorganic filler is 0-150 weight part in total with respect to 100 weight part of polyimide siloxane, Preferably it is 2-150 weight part, Most preferably, it is 10-80 weight part. If the amount used is too much or too little, the above range is preferred because cracks occur due to bending of the laminate or the heat resistance of the solder deteriorates.
[0026]
Further, it is preferable to add a silica-based thickening component such as Aerosil (fine powdered silica) manufactured by Nippon Aerosil, preferably 1 to 50 parts by weight, particularly 5 to 40 parts by weight with respect to 100 parts by weight of polyimidesiloxane.
[0027]
In this invention, the polymer composition can be easily obtained by uniformly stirring and mixing a predetermined amount of polyimide siloxane in an organic solvent, and preferably an epoxy resin, and optionally mica or barium sulfate and silicon. it can. At the time of mixing, it can be mixed in a suitable organic solvent to form a polymer solution composition. In preparing a solution composition dissolved in an organic solvent, it may be performed after mixing. The polyimide siloxane may be a polyimide siloxane polymerization solution as it is or a solution obtained by diluting the polymerization solution with a suitable organic solvent. Examples of the organic solvent include organic polar solvents that can be used for obtaining the polyimidesiloxane, and those having a boiling point of 140 ° C. or higher are preferable, for example, organic solvents having a boiling point of 180 ° C. or higher, particularly 200 ° C. or higher (for example, methyl When triglyme is used, the dissipation due to the evaporation of the solvent is extremely reduced, so that the application can be carried out without any trouble and is optimal.
[0028]
The polymer concentration of the polymer solution composition is 5 to 60% by weight, preferably 5 to 50% by weight, and particularly 10 to 45% by weight. The solution viscosity is 1 to 10000 centipoise. It is preferably 10 to 2000 centipoise (25 ° C., E-type rotational viscometer) in view of workability, physical properties of the solution, and characteristics of the laminate.
[0029]
In the present invention, a polymer solution mainly composed of the above polyimidesiloxane is usually applied to the roughened surface of a metal foil such as an electrolytic copper foil, a roughened copper alloy foil, or a roughened aluminum having a thickness of about 18 to 35 μm. Preferably, after coating directly so that the thickness of the polymer layer (adhesive layer) after curing is 12.5 to 125 μm, it is preferably dried by heating at a temperature of 80 to 100 ° C. to remove the organic solvent, The polymer layer is overlaid with a roughened surface of another metal foil of the same or different type as the metal foil, and a temperature and pressure of 140 to 250 ° C., particularly 140 to 200 ° C. (preferably 5 to 30 kg / cm).²) At the same time or separately to cure the polymer (preferably for 20 to 60 minutes) to produce a flexible printed circuit board.
When pressurization and heating are applied separately, it is appropriate to hold at the temperature and pressure for about 10 seconds to 5 minutes and then to heat at the temperature for about 20 to 120 minutes.
[0030]
Further, according to the present invention, in the laminate comprising at least two metal foils, preferably an electrolytic copper foil, a roughened copper alloy foil, an aluminum foil and a polymer layer, the laminate is flexible and heat resistant. The polymer layer is mainly composed of polyimide siloxane, and the 90 ° peel strength of the laminate is 0.6 kg / cm or more, preferably 1.2 to 2.5 kg / cm, 300 ° C. solder. Has heat resistance that does not cause blistering even when held in a bath for 3 minutes, and the initial elastic modulus of the polymer layer is 10 to 130 kg / mm², Preferably 20-80 kg / mm²Thus, a double-sided flexible printed circuit board and a multilayer flexible printed circuit board are obtained.
[0031]
In this invention, the polymer layer mainly composed of polyimidesiloxane has a certain tensile strength, preferably 0.7 to 10 kg / mm.², Especially 1-10kg / mm²Since it has both the tensile strength, flexibility and heat resistance, it can be used as a flexible printed circuit board.
In the present invention, it is considered that good solder heat resistance is achieved because the benzene ring in the polyimidesiloxane molecule preferably has an OH group or COOH group.
[0032]
The flexible printed circuit board of the present invention is based on the structure of metal foil / polymer layer / metal foil, but of course, other structures such as metal foil / polymer layer / polyimide film / polymer layer may be used depending on the application. A structure of / metal foil, metal foil / polymer layer / metal foil / polymer layer / metal foil is also possible as an application of the present invention.
[0033]
When producing a printed wiring board from the flexible printed circuit board of this invention, it can carry out by the method of providing a photoresist layer by a conventional method and providing a circuit by a conventional method, for example.
[0034]
Since the flexible printed circuit board obtained by the present invention has a certain degree of strength, flexibility and heat resistance, it can be suitably used as a material for making electronic components more and more demanded in the future.
[0035]
【Example】
Hereinafter, the present invention will be described with reference to Examples and Comparative Examples. In each example, measurement and evaluation were performed by the following methods.
[0036]
Tensile strength of base polymer: Tensilon UTM-2-20 from Orientec
It was measured by.
The elongation rate of the base polymer, the initial elastic modulus (tensile) of the base polymer, and the 90 ° peel strength (g / cm) of the laminate were also measured at a measurement temperature of 25 ° C. using the same apparatus.
[0037]
[Measurement of logarithmic viscosity (ηinh)]
The logarithmic viscosity (ηinh) of the polyimidesiloxane reaction solution can be expressed by the following equation.
ηinh = ln (t / t₀) / C
Where t is the passage time (in seconds) between the marked lines in the Canon Fenceke viscometer of the measurement solution, t₀Is the passage time (in seconds) between marked lines in the Canon Fenceke viscometer of pure solvent, and c is the concentration of polyimide siloxane solid (g / 100 ml solvent).
The viscosity was measured at 30 ° C. using an N-methyl-2-pyrrolidone solvent at a polyimidesiloxane solid concentration of 0.5 g / 100 ml.
[0038]
[Measurement method of solder (solder) heat resistance]
The laminate is cut to 3 × 3 cm, and after applying a rosin flux (SUNFLUX SF-270, manufactured by Sanwa Chemical Industries) on the laminate, the laminate is immersed in a 300 ° C. molten solder bath for 3 minutes, cooled, and then laminated. It was observed and evaluated whether or not blistering occurred.
[0039]
[Production of polyimide siloxane]
Reference example 1
A glass flask having a capacity of 500 ml was charged with 2,3,3 ′, 4′-biphenyltetracarboxylic dianhydride (100 mmol, the same in the following molar ratio) and 50 g of triglyme, and heated and stirred at 180 ° C. in a nitrogen atmosphere. . α, ω-bis (3-aminopropyl) polydimethylsiloxane (amino equivalent 480, n = 10.6) (70 mmol) and 50 g of triglyme were added, and the mixture was heated and stirred at 180 ° C. for 60 minutes. Further, 3,5-diaminobenzoic acid (15 mmol), 2,2-bis [4- (4-aminophenoxy) phenyl] propane (15 mmol) and 50 g of triglyme were added to this reaction solution, and the mixture was heated at 180 ° C. for 6 hours. After heating and stirring, filtration was performed. The obtained polyimidesiloxane reaction solution had a polymer solid content concentration of 41 wt%, ηinh 0.17, and a solution viscosity of 50 centipoise. The imidization rate was substantially 100%. 18 parts by weight of an epoxy resin (157S70 manufactured by Yuka Shell) and 18 parts by weight of Aerosil 200 with respect to 100 parts by weight of polyimidesiloxane were added to the polyimidesiloxane solution to obtain a polymer solution.
A film was formed from this polymer solution, and the physical properties of the base polymer were measured. The results are shown in Table 1.
[0040]
Reference Examples 2-4
A polymer solution shown in Table 1 was obtained in the same manner as in Reference Example 1 except that the ratio of diaminopolysiloxane was changed to the ratio shown in Table 1.
A film was formed from this polymer solution, and the physical properties of the base polymer were measured. The results are shown in Table 1.
[0041]
[Table 1]

[0042]
Example 1
The polymer solution obtained in Reference Example 1 was applied to the rough surface of an electrolytic copper foil having a thickness of 35 μm so that the polymer layer had a thickness of 50 μm and dried at 80 ° C. for 60 minutes.
Next, the rough surface of the same electrolytic copper foil is overlaid and 10 kg / cm²The laminate was 120 μm thick by thermocompression bonding at 160 ° C. for 30 minutes or 200 ° C. for 30 minutes.
The obtained flexible printed circuit board, which is a laminate, was much more flexible (can be folded smaller) than a conventionally known flexible printed circuit board.
Table 2 shows the 90 ° peel peel strength of these laminates.
The solder heat resistance was good for 3 minutes or more.
[0043]
Examples 2-4
The same procedure as in Example 1 was conducted except that the polymer solution was changed from the polymer solution obtained in Reference Example 1 to the polymer solution obtained in Reference Examples 2 to 4.
The results are summarized in Table 2.
The solder heat resistance was good for 3 minutes or more.
[0044]
Examples 5-8
10kg / mm by changing the thermocompression bonding conditions²After heating and pressure bonding at 160 ° C. for 3 minutes, the laminate was obtained by heating at 160 ° C. for 60 minutes with no load.
The obtained flexible printed circuit board, which is a laminate, was much more flexible (can be bent) than a conventionally known flexible printed circuit board.
Table 3 shows the 90 ° peel strength of these laminates.
The solder heat resistance was good for 3 minutes or more.
[0045]
Comparative Example 1
A commercially available polyimide-based two-layer substrate (manufactured by Nippon Steel Chemical Co., Ltd., Espanex) was similarly evaluated.
The 90 ° peel strength is 1.13 Kg / cm, and the polymer layer has a tensile strength of 16 kg / mm.²Elongation is 73%, initial elastic modulus is 156kg / mm²Met.
It is a flexible printed circuit board with a large repulsive force.
[0046]
[Table 2]

[0047]
[Table 3]

[0048]
【The invention's effect】
Since the present invention is configured as described above, the following effects can be obtained.
[0049]
According to the method of the present invention, the flexible printed circuit board is manufactured under the mild conditions that do not adversely affect the metal foil without requiring the high temperature and high pressure bonding conditions at the time of thermocompression bonding in the conventional flexible printed circuit board manufacturing. be able to.
[0050]
In addition, the flexible printed circuit board of the present invention is flexible and has high heat resistance, and the polymer layer has a certain level of strength, so that it can be used in fields where compactness is required.

Claims (4)

On the roughened surface of the metal foil, the polymer component is an aromatic tetracarboxylic dianhydride or derivative thereof, an aromatic diamine, an diamine having an OH group or a COOH group in the benzene ring, and a diamine comprising diaminopolysiloxane. A polymer solution composed of an epoxy resin in an amount of 50 parts by weight or less is directly applied to 100 parts by weight of polyimidesiloxane obtained by polymerizing and imidizing and then drying by heating to remove the organic solvent, and the polymer. A method for producing a flexible printed circuit board, comprising: laminating a roughened surface of another metal foil on a layer and applying a temperature and pressure of 140 ° C. or more and 250 ° C. or less simultaneously or separately to cure the polymer. After application of the polymer solution, the organic solvent is removed by heating and drying at a temperature of 80 to 120 ° C., another metal foil is layered on the polymer layer, and a temperature of 140 to 250 ° C. and a pressure of 5 to 30 kg / cm ² are simultaneously applied. Alternatively, the method for producing a flexible printed circuit board according to claim 1, wherein the polymer is cured separately. The polymer component is an aromatic tetracarboxylic dianhydride having a flexible structure of 50 mol% or more or a derivative thereof, an aromatic diamine, an aromatic diamine having an OH group or a COOH group in the benzene ring, and 30 to 80 in the diamine. The method for producing a flexible printed circuit board according to claim 1, wherein 1 to 50 parts by weight of an epoxy resin is mixed with 100 parts by weight of polyimidesiloxane obtained by polymerizing and imidizing a diamine composed of mol% of diaminopolysiloxane. . The polyimide siloxane is obtained by using 2,3,3 ′, 4′-biphenyltetracarboxylic dianhydride or a derivative thereof as a flexible structure aromatic tetracarboxylic dianhydride or a derivative thereof. Item 4. A method for producing a flexible printed circuit board according to Item 3.