JP2005244135A - Flexible printed-wiring board - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a flexible printed-wiring board having various kinds of improved performance. <P>SOLUTION: In the flexible printed-wiring board with a base film layer, a conductive layer, an adhesive layer, and a cover film layer as essential components, a polyester polyurethane resin that is crosslinked to an adhesive layer by an epoxy resin is provided. The base film layer is preferably a polyamideimide resin, and the cover film layer is preferably a polyimide resin. The flexible printed-wiring board capable of achieving high quality even if a fine pattern circuit is formed is provided by specifying an adhesive and adopting a specified layer configuration. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a flexible printed wiring board (hereinafter also referred to as “FPC”). The flexible printed circuit board is sometimes called a flexible printed circuit board, a flexible printed circuit board, or the like.

  The present invention relates to a flexible printed wiring board having excellent migration properties, heat resistance, dimensional stability, adhesiveness, and the like. More specifically, the polyamideimide resin solution is continuously applied to a metal foil and dried, and is excellent in heat resistance, dimensional stability, adhesiveness, and the like. The present invention relates to a flexible printed wiring board with little deterioration in migration.

  In the present specification and claims, the “flexible printed circuit board” is a laminate formed of a metal foil and a resin layer. A flexible printed wiring board is conventionally manufactured by a conventionally known method such as a subtractive method using a flexible metal-clad laminate, for example, and a conductor circuit is partially or entirely covered by a coverlay film. And so-called flexible circuit boards (FPC), flat cables, circuit boards for tape automated bonding (TAB), etc. coated with screen printing ink or the like.

  Conventionally, FPC using a flexible metal-clad laminate in which a metal foil is laminated on a polymer film is known. For example, Patent Document 1 (JP-A-2-131933), Patent Document 2 (JP-A-8-250860), Patent Document 3 (JP-A 2000-273430), and Patent Document 4 (International Publication WO03 / No. 072639) describes a metal-clad laminate in which a metal foil is laminated on a polymer film.

  A conventional flexible printed wiring board is obtained by bonding a polyimide film and a metal foil with a thermosetting adhesive such as an epoxy resin or an acrylic resin. The flexible printed circuit board formed from the flexible metal-clad laminate bonded with this thermosetting adhesive has a high thermal expansion coefficient of the base material (resin film layer) due to the adhesive, so that the thermal dimension is stable. Inferior in heat resistance and inferior in moisture resistance, there is a problem that insulation and solder heat resistance are lowered after humidification. Furthermore, because it is inferior in thermal dimensional stability, the flexible metal-clad laminate and the flexible printed circuit board obtained by processing the circuit in various heating processes are curled or inferior in moisture resistance. During the wet process, curling, twisting, and the like are generated on the substrate, and as a result, there is a problem that the yield is deteriorated in the circuit forming process and the mounting process on the flexible printed circuit board.

  In order to solve these problems, a technique for forming a metal foil directly on an insulating substrate without an adhesive has been studied (a so-called two-layer flexible metal-clad laminate). For example, Patent Document 5 (Japanese Patent Laid-Open No. 02-98994) discloses a polyimide film by a sputtering method, Patent Document 6 (Japanese Patent Laid-Open No. 62-181488) uses a vapor deposition method, and Patent Document 7 (Japanese Patent Laid-Open No. 57-157). No. 18357) proposes a technique in which a thin metal layer (seed layer) is formed by an ion plating method and then a conductor layer is formed by plating. However, both methods have the disadvantage of high production costs, and there are problems such as pinholes when forming the seed layer and insufficient adhesion between the polyimide film and the conductor. .

  In order to provide a high-performance flexible printed circuit board without an adhesive layer at a lower cost, in Patent Document 8 (Japanese Patent Laid-Open No. 57-50670) and the like, a polyamic acid-based solution which is a polyimide resin precursor is used as a metal foil. A method has been proposed in which a flexible metal-clad laminate is formed by directly applying to a metal foil and dehydrating / polyimidizing on a metal foil. However, the flexible metal-clad laminate obtained by such a method has a poor insulation performance after the humidification treatment due to a high moisture absorption rate of the resin and the like (for example, a high voltage is applied) The flexible printed circuit board used for display peripheral parts) has a problem of poor reliability (migration resistance). In addition, solder heat resistance is also reduced after humidification, so application to lead-free solder (Ag—Sn—Bi, Ag—Sn—Cu, etc.) is restricted, or wet process and high humidity atmosphere There is a problem in that the yield in the circuit forming process and the mounting process deteriorates because the substrate is curled or twisted. In addition, in the case of a polyamic acid that is a precursor, if a varnish in which a resin is dissolved is stored, hydrolysis proceeds, causing problems such as a decrease in molecular weight or solidification in a gel form.

  As described above, in the prior art, polyamideimide resin has excellent varnish stability, excellent dimensional stability and heat resistance, and there is no decrease in solder heat resistance or insulation even under humidification. Actually, there is no flexible metal-clad laminate for use in a two-layer type flexible printed circuit board that is free from warping and twisting even under a moderate atmosphere (under humidification or heating).

  Moreover, as an insulating film for FPC, a polyimide resin or the like has been conventionally used. For example, Patent Document 9 (Japanese Patent Laid-Open No. 7-41588) and Patent Document 10 (Japanese Patent Laid-Open No. 11-156936) describe a polyimide film used as an insulating film for FPC.

  However, these insulating films have a drawback in that the adhesiveness with the adhesive is not good. In addition, in FPC obtained by combining an insulating film, metal foil and adhesive, the properties and performance of the insulating film, the properties and performance of the metal foil, and the properties and performance of the adhesive, respectively. It is extremely difficult to predict the performance as an FPC. In the development of an FPC, it is not possible to predict whether or not the required performance as an FPC will be satisfied unless the combination of various materials is actually evaluated. There was a situation.

  For this reason, it has been extremely difficult for those skilled in the art to predict whether a general-purpose conventional adhesive can be used for FPC. For example, in the case of an FPC composed of four layers of a base film layer, a metal foil layer, an adhesive layer, and an insulating film layer, it was necessary to satisfy the performance of the FPC as the entire four layers. And when the adhesive force between the base film layer and the adhesive layer is not sufficient, the performance as the FPC cannot be satisfied, and the adhesive force between the metal foil layer and the adhesive layer is not sufficient In addition, the performance as the FPC cannot be satisfied, and the performance as the FPC cannot be satisfied even when the adhesive force between the insulating film layer and the adhesive layer is not sufficient. In addition, even if each of the four layer materials is a material having good performance, if there is a variation in physical properties between one of the four layers and the other layer, FPC Serious defects may occur.

  Therefore, in order to satisfy the required performance required for FPC, each of the four layers (or five layers when an adhesive layer is provided between the base material layer and the metal foil layer) has excellent performance. It is not enough to select the material, and the interaction between the material of the first layer and the material of the other layer, the interaction between the material of the second layer and the material of the other layer, the material of the third layer and the other material The interaction between the material of the layer and the interaction between the material of the fourth layer and the material of the other layer, and in the case of the five layers, all the interaction between the material of the fifth layer and the material of the other layer It is necessary to consider and designing an appropriate layer structure has been extremely difficult for those skilled in the art.

  For example, in Patent Document 11 (Japanese Patent Application Laid-Open No. 11-116930), a polyester / polyuretan type adhesive is described, but whether or not such an adhesive can be used as an insulating film for FPC. It wasn't something that a trader could easily predict.

For this reason, for example, an NBR adhesive as described in Patent Document 3 (Japanese Patent Laid-Open No. 2000-273430) is used as an adhesive for FPC. In this type of adhesive, In an FPC having a circuit on which a fine pattern is formed, it has been difficult to ensure sufficient performance for various required qualities as the FPC.
JP-A-2-131933 JP-A-8-250860 JP 2000-273430 A International Publication WO03 / 072639 JP-A-2-98994 JP-A-62-181488 JP-A-57-18357 JP-A-57-50670 JP 7-41558 A JP-A-11-156936 JP-A-11-116930

  This invention makes it a subject to solve said subject. That is, an object of the present invention is to provide an FPC excellent in various performances. Specifically, an object of the present invention is to provide an FPC having excellent flexibility. An object of the present invention is to provide an FPC excellent in balance of various performances.

  In particular, the present invention provides a flexible printed wiring board that can be used for a circuit board that requires high quality such as a plasma display or a cellular phone that requires high reliability even in a circuit in which a fine pattern is formed. It is to provide.

  As a result of diligent research to achieve the above object, the present inventors have succeeded in developing an FPC having excellent flexibility, which has not been conventionally available. That is, according to the present invention, the following FPC is provided.

[1] A flexible printed wiring board including a base film layer, a conductor layer, an adhesive layer, and a cover film layer,
A flexible printed wiring board, wherein the adhesive contains a polyester polyurethane resin crosslinked with an epoxy resin, and the number average molecular weight of the polyester polyurethane resin is 8000 to 100,000.

  [2] The flexible printed wiring board according to [1], which includes a pattern having a circuit pitch of 150 μm or less and a circuit line width of 100 μm or less.

  [3] The flexible printed wiring board according to [1] or [2], wherein the cover film layer is a polyimide resin film or a polyamideimide resin film.

  [4] The flexible printed wiring board according to [3], wherein the cover film layer is a polyimide resin film.

  [5] The flexible printed wiring board according to [4], wherein 5 to 70 mol% of the diamine component of the polyimide resin is p-phenylenediamine.

  [6] The flexible printed wiring board according to any one of [1] to [5], wherein the base film layer is a polyimide resin film or a polyamideimide resin film.

  [7] The flexible printed wiring board according to [6], wherein the base film layer is a polyamideimide resin film.

[8] The flexible printed wiring board according to [7], wherein 70 to 90 mol% trimellitic anhydride, 5 to 25 mol% 3, of the acid component of the polyamide-imide resin 3 ′, 4,4′-benzophenone tetracarboxylic dianhydride, and 5-25 mol% 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride,
A flexible printed wiring board comprising 3,3′-dimethyl-4,4′-biphenyldiamine as a diamine component of the polyamideimide resin.

  [9] The flexible printed wiring board according to [1], wherein the conductor layer is directly laminated on the base film layer without using an adhesive.

  According to the present invention, an FPC excellent in various performances is provided. Specifically, the FPC of the present invention is particularly excellent in flexibility.

  Hereinafter, embodiments of the flexible printed circuit board (FPC) of the present invention will be described.

(Laminated structure)
The FPC of the present invention can have any laminated structure that can be employed as an FPC. For example, it can be set as FPC comprised from 4 layers, a base film layer, a metal foil layer, an adhesive bond layer, and a cover film layer. For example, it can be set as FPC comprised from five layers, a base film layer, an adhesive bond layer, a metal foil layer, an adhesive bond layer, and a cover film layer.

  Furthermore, if necessary, a configuration in which two or three or more of the above FPCs are stacked may be used.

  For example, a plurality of the four-layer type FPC or the five-layer type FPC may be stacked, and the FPC and the FPC may be bonded with an adhesive as necessary. More specifically, for example, a first FPC base film layer, a first FPC metal foil layer, a first FPC adhesive layer, a first FPC cover film layer, and a first FPC An adhesive layer for adhering to the second FPC, a base film layer for the second FPC, a metal foil layer for the second FPC, an adhesive layer for the second FPC, and a cover film layer for the second FPC A total of nine layers may be sequentially stacked.

Further, for example, the four-layer type FPC or the five-layer type FPC may be bonded back to back by bonding the bottoms of two base film layers with an adhesive layer. In this case, for example, if the above four-layer type FPC is used,
First FPC cover film layer,
First FPC adhesive layer;
A metal foil layer of the first FPC;
A first FPC base film layer;
An adhesive layer for adhering the base films of the first FPC and the second FPC,
A second FPC substrate film layer,
A second FPC metal foil layer;
A total of nine layers of the second FPC adhesive layer and the second FPC cover film layer may be laminated in order.

For example, if the above-mentioned 5-layer type FPC is used,
First FPC cover film layer,
An adhesive layer on the cover film side of the first FPC;
A metal foil layer of the first FPC;
An adhesive layer on the base film side of the first FPC;
A first FPC base film layer;
An adhesive layer for adhering the base films of the first FPC and the second FPC,
A second FPC substrate film layer,
An adhesive layer on the base film side of the second FPC;
A second FPC metal foil layer;
A total of 11 layers of the adhesive layer on the cover film side of the second FPC and the cover film layer of the second FPC may be laminated in order.

  Further, a laminated structure of a total of 10 layers in which the adhesive layer on the base film side of the first FPC or the adhesive layer on the base film side of the second FPC is omitted, that is, the above-described four-layer type FPC and 5 A layer type FPC may be bonded back to back.

(Base film)
In the FPC of the present invention, any resin film conventionally used as an FPC base material can be used as the base film.

  As the resin for the base film, a resin containing halogen may be used, or a resin not containing halogen may be used. From the viewpoint of environmental problems, a resin containing no halogen is preferable. However, from the viewpoint of flame retardancy, a resin containing halogen can also be used.

  The base film is preferably a polyimide film or a polyamideimide film. More preferably, it is a polyamideimide film.

  A polyimide film has a polyimide resin as a main component as its resin component. Of the resin components, 90% by weight or more is preferably polyimide, more preferably 95% by weight or more is polyimide, more preferably 98% by weight or more is polyimide, and 99% by weight or more is polyimide. It is particularly preferred. Any conventionally known resin can be used as the polyimide resin. The polyimide resin is a resin having an imide bond in a repeating unit, and is synthesized, for example, by reacting an anhydride of tetracarboxylic acid (for example, pyromellitic acid anhydride) and a diamine (for example, diaminodiphenyl ether).

  The molecular weight of the polyimide resin (when the polyimide resin is insoluble in N-methyl-2-pyrrolidone, the precursor polyamic acid) is 30 in N-methyl-2-pyrrolidone (polymer concentration 0.5 g / dl), 30 Those having a molecular weight corresponding to 0.3 to 2.5 dl / g in terms of logarithmic viscosity at ° C. are preferred, more preferably those having a molecular weight corresponding to 0.8 to 2.0 dl / g. If the logarithmic viscosity is too low, the mechanical properties may be insufficient when formed into a molded product such as a film, and if it is too high, the solution viscosity will be high, making molding difficult. There is.

  The polyamide-imide film has a polyamide-imide resin as a main component as its resin component. Of the resin components, 90% by weight or more is preferably polyamideimide, more preferably 95% by weight or more is polyamideimide, more preferably 98% by weight or more is polyamideimide, and 99% by weight or more. Is particularly preferably polyamideimide.

  The polyamideimide resin is a resin having an imide bond and an amide bond in the repeating unit of the main chain. Any conventionally known resin can be used as the polyamideimide resin. As a method for synthesizing a polyamideimide resin, typically, an isocyanate method in which trimellitic anhydride and diisocyanate are reacted and an acid chloride method in which trimellitic anhydride chloride and diamine are reacted are known. Polyamideimide resin produced by any method can be used in the present invention. Hereinafter, particularly preferred polyamideimide resins in the present invention will be described.

  A preferred polyamideimide resin can be dissolved in an amide solvent at a concentration of 10%, and the change rate of the solution viscosity when the varnish is stored at 5 ° C. for 1 month ((solution viscosity after 1 month−initial solution viscosity) / The absolute value of the initial solution viscosity is 3.0 or less, and the moisture absorption rate of the resin (25 ° C., 90% RH, 24 hours) is 2.0% or less. A non-halogen type is more preferable.

  In the present specification, soluble in an amide solvent means N-methyl-2-pyrrolidone, N, N-dimethylformamide, N, N-dimethylacetamide, 1,3-dimethyl-2-imidazolidinone. It means that 10% by weight or more is dissolved in any one of the single solvents or the mixed organic solvent containing 20% by weight or more of at least one of them. Preferably it is 15 weight% or more, More preferably, it is 20 weight%.

  In addition, when the resin is in a solid state, whether or not it has been dissolved is determined by adding a specified weight of resin powder passing through 80 mesh into a 200 ml beaker and gently stirring the solution for 24 hours at 25 ° C. Judge visually. In addition, when it is already a solvent solution, the solution diluted to a specific concentration is allowed to stand at 25 ° C. for 24 hours, and the solution without any gelation, non-uniformity, white turbidity, or precipitation is dissolved. judge.

  The varnish in which the polyamideimide resin is dissolved has an absolute value of the change rate of the solution viscosity ((solution viscosity after one month−initial solution viscosity) / initial solution viscosity) when stored at 5 ° C. for one month is 3.0 or less. Things are desirable. The solution viscosity change rate was determined by measuring the solution viscosity immediately after dissolution of the varnish dissolved at 10% by weight in the above amide solvent at 25 ° C. with a B-type viscometer, storing the varnish at 5 ° C. for 1 month, The solution viscosity at 25 ° C. is measured using a mold viscometer. The rate of change in solution viscosity is determined from the measured value. The absolute value of the rate of change is more preferably 2.0 or less, further preferably 1.0 or less, and most preferably 0.20 or less. The change rate of the solution viscosity exceeds 3.0 means that the storage stability of the varnish is not good, so it must be applied to the metal foil immediately after the production of the varnish. It becomes difficult to manufacture.

The moisture absorption rate (25 ° C., 90% RH, 24 hours) of the polyamideimide resin is preferably 2.0% or less, more preferably 1.8% or less, and further preferably 1.5% or less. . Here, the moisture absorption rate is a value measured by the following method using a resin film having a length and a width of 50 ± 1 mm. Five samples are used for the measurement.
(1) The sample is allowed to stand for 24 hours in a thermostat kept at 50 ± 2 ° C.
(2) Place the sample in a weighing bottle so that the samples do not contact each other, and leave it for 24 hours at 25 ° C. and 90% RH with the lid of the weighing bottle (hereinafter simply referred to as the lid) open (sample surface). The dust is removed with a feather or brush.
(3) The weighing bottle is quickly sealed with a lid and left in a desiccator at room temperature for 1 hour.
(4) The total weight of the weighing bottle and the sample is measured (W1), and then the sample is quickly taken out and the weight (W0) of only the weighing bottle is measured.
(5) Put the sample in the weighing bottle again and dry it for 1 hour in a thermostat kept at 100 ± 5 ° C. with the lid open.
(6) The weighing bottle is quickly sealed with a lid and left in a desiccator at room temperature for 1 hour.
(7) The total weight of the weighing bottle and the sample is measured (referred to as W3), and then the sample is quickly taken out therefrom and the weight (W4) of only the weighing bottle is measured.
(8) The moisture absorption rate WA (%) is calculated by the following formula.

WA = [{(W1-W0)-(W3-W4)} / (W1-W0)] × 100
When the moisture absorption rate exceeds 1.5% by weight, the curl of the flexible metal-clad laminate increases under humidification, and the flexible printed circuit board processed using the same also increases curl under humidification, and fine soldering Dimensional accuracy when processing such as the above may be deteriorated. Furthermore, solder heat resistance and insulation (humidity stability of line insulation resistance, stability of line breakdown voltage over time) after the humidification process may be lowered.

  Polyamideimide resin with good solution stability, non-halogen and low moisture absorption rate, for example, a plurality of polyimide skeletons and polyamides in which the repeating unit of the polymer chain is insoluble in organic solvents or poorly soluble in organic solvents It can be produced by a method in which an imide skeleton is formed and each repeating unit is copolymerized within a range compatible with each other.

  One embodiment includes the following general formula (1), general formula (2), and general formula (3) as structural units, and the general formula (1), general formula (2), and general formula (3) ) Is a formula (1) / formula (2) = 1/99 to 99/1 molar ratio, preferably formula (1) / formula (2) = 30/70 to 70/30. Molar ratio and {formula (1) + formula (2)} / formula (3) = 30/70 to 1/99 molar ratio, preferably {formula (1) + formula (2)} / formula ( 3) = copolymerized polyamideimide satisfying 20/80 to 5/95 molar ratio. When the molar ratio of the formula (1) and the formula (2) is compared, the moisture absorption rate tends to increase when the component of the formula (1) is small, and when the component of the formula (1) is large, There is a case where the compatibility of the resin is deteriorated, and the mechanical properties and thermal dimensional stability (thermal expansion coefficient) tend to be deteriorated. Further, when {Formula (1) + Formula (2)} and Formula (3) are compared, if {Formula (1) + Formula (2)} exceeds 30 mole ratio, the solvent solubility is poor and 1 mole% If it is less than 1, the moisture absorption property may deteriorate in addition to the solvent solubility.

  General formula (1);

（式中、Ｒ^１およびＲ^２は同じであっても異なっていてもよく、それぞれ水素もしくは炭素数１〜４のアルキル基、又は、アルコキシ基を示す。又、Ｙは直結（ビフェニル結合）、或いは、エーテル結合（−Ｏ−）を示す。）
一般式（２）；

(Wherein R ¹ and R ² may be the same or different and each represents hydrogen, an alkyl group having 1 to 4 carbon atoms, or an alkoxy group. Y is a direct bond (biphenyl bond); Or an ether bond (-O-) is shown.)
General formula (2);

（式中、Ｒ^３およびＲ^４は同じであっても異なっていてもよく、それぞれ水素もしくは炭素数１〜４のアルキル基、又は、アルコキシ基を示す。）
一般式（３）；

(In the formula, R ³ and R ⁴ may be the same or different, and each represents hydrogen, an alkyl group having 1 to 4 carbon atoms, or an alkoxy group.)
General formula (3);

（式中、Ｒ^５およびＲ^６は同じであっても異なっていてもよく、それぞれ水素もしくは炭素数１〜４のアルキル基、又は、アルコキシ基を示す。）
好ましい例としてはポリアミドイミド樹脂の酸成分１００モル％のうちに、酸成分としてトリメリット酸無水物７０〜９０モル％と、３，３’，４，４’−ベンゾフェノンテトラカルボン酸二無水物５〜２５モル％と、３，３’，４，４’−ビフェニルテトラカルボン酸二無水物５〜２５モル％とを含み、ジアミン成分として３，３’−ジメチル−４，４’−ビフェニルジイソシアネートを含むポリアミドイミド樹脂である。

(In the formula, R ⁵ and R ⁶ may be the same or different and each represents hydrogen, an alkyl group having 1 to 4 carbon atoms, or an alkoxy group.)
As a preferable example, 70 to 90 mol% of trimellitic anhydride as an acid component in 100 mol% of the acid component of polyamideimide resin, 3,3 ', 4,4'-benzophenone tetracarboxylic dianhydride 5 -25 mol% and 3,3 ', 4,4'-biphenyltetracarboxylic dianhydride 5-25 mol%, and 3,3'-dimethyl-4,4'-biphenyl diisocyanate as a diamine component It is a polyamidoimide resin.

  Moreover, trimellitic anhydride 70-90 mol%, 3,3 ', 4,4'-benzophenone tetracarboxylic dianhydride 5-25 mol%, 3,3', 4,4 'as an acid component Polyamideimide resin containing 5 to 25 mol% of diphenyl ether tetracarboxylic dianhydride and containing 3,3′-dimethyl-4,4′-biphenyl diisocyanate as a diamine component is also preferable.

  One embodiment includes the following general formula (4), general formula (5), and general formula (6) as structural units, and the general formula (4), general formula (5), and general formula (6) ) Is a formula (4) / formula (5) = 1/99 to 99/1 molar ratio, preferably formula (4) / formula (5) = 30/70 to 70/30. Molar ratio and {formula (4) + formula (5)} / formula (6) = 50/50 to 1/99 molar ratio, preferably {formula (4) + formula (5)} / formula ( 6) = copolymerized polyamideimide satisfying 30/70 to 5/95 molar ratio. When the molar ratio of the formula (4) and the formula (5) is compared, when the amount of the component of the formula (4) is small, the moisture absorption rate tends to be high, and when the amount of the component of the formula (4) is large, the film is formed. There is a case where the compatibility of the resin is deteriorated, and the mechanical properties and thermal dimensional stability (thermal expansion coefficient) tend to be deteriorated. In addition, when the molar ratio of {Formula (4) + Formula (5)} and Formula (6) is compared, if the amount of {Formula (4) + Formula (5)} is large, the thermal expansion coefficient increases. Solvent solubility tends to decrease, and if the amount of {formula (4) + formula (5)} is small, solvent solubility and moisture absorption characteristics may be deteriorated.

  General formula (4);

（式中、Ｒ^１およびＲ^２は同じであっても異なっていてもよく、それぞれ水素もしくは炭素数１〜４のアルキル基、又は、アルコキシ基を示す。又、Ｚは、−ＯＣ（Ｏ）−Ｒ’−ＣＯＯ−を示す。但し、Ｒ’は二価のアルキレン基、或いは、芳香族残基を示す。）
一般式（５）；

(In the formula, R ¹ and R ² may be the same or different and each represents hydrogen, an alkyl group having 1 to 4 carbon atoms, or an alkoxy group. Z represents —OC (O). -R'-COO-, wherein R 'represents a divalent alkylene group or an aromatic residue.)
General formula (5);

（式中、Ｒ^３およびＲ^４は同じであっても異なっていてもよく、それぞれ水素もしくは炭素数１〜４のアルキル基、又は、アルコキシ基を示す。）

(In the formula, R ³ and R ⁴ may be the same or different, and each represents hydrogen, an alkyl group having 1 to 4 carbon atoms, or an alkoxy group.)

一般式（６）；
（式中、Ｒ^５およびＲ^６は同じであっても異なっていてもよく、それぞれ水素もしくは炭素数１〜４のアルキル基、又は、アルコキシ基を示す。）
好ましい実施態様としてはポリアミドイミド樹脂の酸成分１００モル％のうちに、酸成分としてトリメリット酸無水物７０〜９０モル％と、３，３’，４，４’−ベンゾフェノンテトラカルボン酸二無水物５〜２５モル％と、エチレングリコールビス（アンヒドロトリメリテート）５〜２５モル％とを含み、ジアミン成分として３，３’−ジメチル−４，４’−ビフェニルジイソシアネートを含むポリアミドイミド樹脂である。

General formula (6);
(In the formula, R ⁵ and R ⁶ may be the same or different and each represents hydrogen, an alkyl group having 1 to 4 carbon atoms, or an alkoxy group.)
As a preferable embodiment, 70 to 90 mol% of trimellitic anhydride as an acid component in 100 mol% of the acid component of polyamideimide resin, and 3,3 ′, 4,4′-benzophenone tetracarboxylic dianhydride A polyamide-imide resin containing 5 to 25 mol% and 5 to 25 mol% ethylene glycol bis (anhydrotrimellitate) and containing 3,3′-dimethyl-4,4′-biphenyl diisocyanate as a diamine component. .

  Further, trimellitic anhydride 70 to 90 mol%, 3,3 ', 4,4'-benzophenonetetracarboxylic dianhydride 5 to 25 mol%, propylene glycol bis (anhydrotrimellitate) as an acid component A polyamideimide resin containing 5 to 25 mol% and containing 3,3′-dimethyl-4,4′-biphenyl diisocyanate as a diamine component is also preferable.

  Further, trimellitic anhydride 70-90 mol%, 3,3 ′, 4,4′-benzophenone tetracarboxylic dianhydride 5-25 mol%, 2,2-bis (4-hydroxy) as acid components Phenyl) propanedibenzoate-3,3 ′, 4,4′-tetracarboxylic dianhydride, 5 to 25 mol%, and 3,3′-dimethyl-4,4′-biphenyl diisocyanate as the diamine component Polyamideimide resin is also good.

  Manufacture of a polyamideimide resin can be synthesize | combined by a conventionally well-known normal procedure. For example, an isocyanate method, an acid chloride method, a low temperature solution polymerization method, a room temperature solution polymerization method, and the like. From the viewpoint of reducing production costs and unreacted functional groups (carboxyl groups), a particularly preferable production method is decarboxylation. This is an isocyanate method in which a polymer is obtained by reaction.

  The raw materials (acid component and diamine component) used for introducing the polyimide skeleton represented by the general formulas (1), (2), (4), and (5) into the polymer are as follows. There are many things.

  Examples of the acid component include benzophenone-3,3 ′, 4,4′-tetracarboxylic acid, biphenyl-3,3 ′, 4,4′-tetracarboxylic acid, diphenylether-3,3 ′, 4,4′-tetra Carboxylic acid or monoanhydrides such as alkylene glycol bis (trimellitate) and bisphenol bis (trimellitate) as shown by the following general formula (7), dianhydrides, esterified products, etc. alone or in combination of two or more It can be used as a mixture.

  General formula (7);

（式中、Ｒ’はアルキレン基、或いは、二価の芳香族残基を示す。）
また、ジアミン成分としては、３，３’−ジメチル−４，４’−ジアミノビフェニル、３，３’−ジエチル−４，４’−ジアミノビフェニル、２，２’−ジメチル−４，４’−ジアミノビフェニル、２，２’−ジエチル−４，４’−ジアミノビフェニル、３，３’−ジメトキシ−４，４’−ジアミノビフェニル、３，３’−ジエトキシ−４，４’−ジアミノビフェニル、或いは、これらに対応するジイソシアネートなどの単独、或いは２種以上の混合物を用いることができる。

(In the formula, R ′ represents an alkylene group or a divalent aromatic residue.)
As the diamine component, 3,3′-dimethyl-4,4′-diaminobiphenyl, 3,3′-diethyl-4,4′-diaminobiphenyl, 2,2′-dimethyl-4,4′-diamino Biphenyl, 2,2′-diethyl-4,4′-diaminobiphenyl, 3,3′-dimethoxy-4,4′-diaminobiphenyl, 3,3′-diethoxy-4,4′-diaminobiphenyl, or these A single diisocyanate or a mixture of two or more of them can be used.

  In addition to the above, it is also possible to copolymerize an acid component and a diamine component as shown below as long as the object of the present invention is not impaired.

  Examples of the acid component include pyromellitic acid, 3,3 ′, 4,4′-diphenylsulfonetetracarboxylic acid, naphthalene-2,3,6,7-tetracarboxylic acid, naphthalene-1,2,4,5-tetra Monoanhydrides such as carboxylic acid and naphthalene-1,4,5,8-tetracarboxylic acid, dianhydrides, esterified products and the like can be used alone or as a mixture of two or more.

  Examples of the diamine component include p-phenylenediamine, m-phenylenediamine, 3,4'-diaminodiphenyl ether, 4,4'-diaminodiphenyl ether, 4,4'-diaminodiphenyl sulfone, 3,3'-diaminodiphenyl sulfone, 3, 4'-diaminobiphenyl, 3,3'-diaminobiphenyl, 3,3'-diaminobenzanilide, 4,4'-diaminobenzanilide, 4,4'-diaminobenzophenone, 3,3'-diaminobenzophenone, 3, 4'-diaminobenzophenone, 2,6-tolylenediamine, 2,4-tolylenediamine, 4,4'-diaminodiphenyl sulfide, 3,3'-diaminodiphenyl sulfide, 4,4'-diaminodiphenylpropane, 3 , 3′-Diaminodiphenylpropane, 3,3 ′ Diaminodiphenylmethane, 4,4′-diaminodiphenylmethane, p-xylenediamine, m-xylenediamine, 1,4-naphthalenediamine, 1,5-naphthalenediamine, 2,6-naphthalenediamine, 2,7-naphthalenediamine, 2 , 2′-bis (4-aminophenyl) propane, 1,3-bis (3-aminophenoxy) benzene, 1,3-bis (4-aminophenoxy) benzene, 1,4-bis (4-aminophenoxy) Benzene, 2,2-bis [4- (4-aminophenoxy) phenyl] propane, bis [4- (4-aminophenoxy) phenyl] sulfone, bis [4- (3-aminophenoxy) phenyl] sulfone, bis [ 4- (3-Aminophenoxy) phenyl] propane, 4,4′-bis (4-aminophenoxy) Phenyl, 4,4'-bis (3-aminophenoxy) biphenyl, or may be used singly or in combination of two or more of such diisocyanates corresponding to these.

  Examples of raw materials (acid component and diamine component) used for introducing the polyamideimide skeleton represented by the general formulas (3) and (6) into the polymer include the following.

  As the acid component, trimellitic acid, or its monoanhydride, esterified product, etc., alone or as a mixture, and as the diamine component, the same diamine as the polyimide skeleton, or the corresponding diisocyanate alone, Or a mixture is mention | raise | lifted.

  In addition to the above, it is also possible to copolymerize an acid component and a diamine component as shown below as long as the object of the present invention is not impaired.

  Examples of the acid component include diphenyl ether-3,3 ′, 4′-tricarboxylic acid, diphenylsulfone-3,3 ′, 4′-tricarboxylic acid, benzophenone-3,3 ′, 4′-tricarboxylic acid, and naphthalene-1,2. Monoanhydrides such as tricarboxylic acids such as 1,4-tricarboxylic acid, esterified compounds, etc., alone or as a mixture of two or more, and as the diamine component, the same diamine as the polyimide skeleton, or corresponding The diisocyanate may be used alone or as a mixture of two or more.

  In the above preferred resin, one feature is that the polymer chain does not contain a halogen compound. For example, 3,3′-dichloro-4,4′-diaminobiphenyl, 3,3 This means that a halogen element-containing monomer such as' -dibromo-4,4'-diaminobiphenyl is not used. Of course, even if a monomer containing a halogen element is used, the object of the present invention, such as solvent solubilization and low thermal expansion, may be achieved, but in this case, applications that can be used are limited due to environmental problems. Therefore, it is not preferable.

  The molecular weight of the polyamide-imide resin has a molecular weight corresponding to 0.3 to 2.5 dl / g in N-methyl-2-pyrrolidone (polymer concentration 0.5 g / dl) and a logarithmic viscosity at 30 ° C. Preferably, it has a molecular weight corresponding to 0.8 to 2.0 dl / g. If the logarithmic viscosity is too low, the mechanical properties may be insufficient when formed into a molded product such as a film, and if it is too high, the solution viscosity will be high, making molding difficult. There is.

  Further, when the polyamideimide resin is produced, adipic acid, as an acid component, in a range that does not impair the object of the present invention, such as moisture absorption characteristics, heat resistance, insulation, dimensional stability (thermal expansion coefficient), solvent solubility, etc. Azelaic acid, sebacic acid, cyclohexane-4,4'-dicarboxylic acid, butane-1,2,4-tricarboxylic acid, butane-1,2,3,4-tetracarboxylic acid, cyclopentane-1,2,3 Aliphatic and alicyclic dicarboxylic acids such as 4-tetracarboxylic acid, polycarboxylic acids, and their monoanhydrides, dianhydrides, and esterified products may be used, and tetramethylenediamine may be used as the diamine component. , Hexamethylenediamine, isophoronediamine, 4,4'-dicyclohexylmethanediamine, cyclohexane-1,4-diamine, diaminosiloxane Group and alicyclic diamines, or may be used diisocyanates corresponding to these alone or in combination of two or more. Further, a resin separately polymerized by a combination of these acid component and diamine component can be mixed and used.

  For the polyamide-imide resin, a terminal-capping monomer for blocking the terminal may be used. For example, monocarboxylic acids such as phthalic anhydride and benzoic acid, monoanhydrides, monoamines such as aniline and phenyl isocyanate, monoisocyanates, and the like can be used.

  As the molar balance of the acid component and the diamine component, the acid / amine ratio is preferably in the range of 1.1 to 0.9 molar ratio, and more preferably, the acid component is slightly excessive, 1.00 to 1.05. A range of molar ratios. The purity of the anhydride in the acid component is preferably 95%, preferably 99% or more.

The absorbance ratio of the imide bond of the polyamide-imide resin to the benzene nucleus is preferably 0.9 or more. More preferably, it is 1.0 or more. The upper limit is not particularly limited, but is preferably less than 5.0 from the viewpoint of solvent solubility. If the absorbance of the imide bond is less than 0.9, the hygroscopic property of the resin is lowered, and the dielectric breakdown voltage of the flexible printed circuit board, the temporal stability of the insulation resistance of the line, and the solder heat resistance after the humidification process are reduced. It tends to get worse. The absorbance ratio here is determined by the following measurement method. A 270-3 type infrared spectrophotometer manufactured by Hitachi, Ltd. is used, and a powdery sample obtained by scraping the surface of the resin film (surface not in contact with the metal foil) is used as a sample, and measurement is performed by the KBr method. Base minus International Publication WO03 / 072,639 discloses the absorbance of the absorption of an imide absorbance 1380 cm ^-1 as shown in FIG. 2 (a) and 1500cm absorbance of absorption of the benzene nucleus of ^-1 (b) between the peak-bottom Obtained as the height from the line, the absorbance ratio (b / a) is calculated. In the measurement, the absolute value of the absorbance of benzene nucleus absorption is in the range of 0.5 to 0.7, and the height from the baseline is 0.2 or more in absorbance. Concentration adjustment and grinding.

  It is preferable that the ionic impurity in resin (for example, polyamideimide resin) of the base film is 2 mg / kg or less. More preferably, it is 1.5 mg / kg or less, More preferably, it is 1 mg / kg or less. The lower limit is not particularly limited, but is preferably as close to 0 mg / kg as possible. If the ionic impurity exceeds 2 mg / kg, solder heat resistance / insulation after humidification described later may be deteriorated. For ionic impurities, after cutting the substrate film into 1 cm x 1 cm, 5 g is put in a quartz beaker, 50 ml of ultrapure water is added, and heat treatment is performed in an autoclave at 120 ° C for 20 hours, and the resulting sample (extracted pure water) For Na, K, and Li, elemental quantification is performed by atomic absorption.

  It is preferable that the acid value of resin (for example, polyamide imide resin) of the base film is 150 μeq / g or less. More preferably, it is 130 microeq / g or less, More preferably, it is 120 microeq / g or less. If the acid value exceeds 150 μeq / g, the hygroscopic properties of the resin will deteriorate, and the dielectric breakdown voltage of the flexible printed circuit board, the stability over time of the insulation resistance between lines, and the solder heat resistance after humidification will tend to deteriorate. It is in. The lower limit of the acid value is not particularly from the viewpoint of the dielectric breakdown voltage of the flexible printed circuit board, the temporal stability of the insulation resistance between the lines, or the solder heat resistance after the humidification treatment, but if it is too low, the adhesive strength is lowered. Tend to. This lower limit value varies depending on the value of the insolubility rate of the heat-resistant resin film layer described later, and is particularly preferably 5 μeq / g or more when the insolubility rate is high. This is presumably because the higher the insolubility, the higher the degree of crosslinking of the resin film layer, and as a result, the mechanical properties such as the elastic modulus tend to change, which affects the adhesiveness.

  In the base film resin (for example, polyamide-imide resin), the acid value and the absorbance of the imide bond can be controlled by the polymerization conditions such as the polymerization temperature and the polymerization time, but generally the molar balance of the acid component and the diamine component. It can be controlled by the use of an end-capping agent or the amount of anhydride groups in the acid component (control of monomer purity and moisture).

  The glass transition temperature of the base film resin (for example, polyamideimide resin) is preferably 250 ° C. or higher. More preferably, it is 280 degreeC or more, More preferably, it is 300 degreeC or more. Although an upper limit is not specifically limited, It is preferable that it is less than 450 degreeC at the point of varnish stability. If the glass transition temperature is too low, solder heat resistance may be reduced. The glass transition temperature is measured by a tensile load method of thermomechanical analysis using a resin film as a sample (load: 1 g, sample size: 4 (width) × 20 (length) mm, temperature increase rate: 10 ° C./min, atmosphere: nitrogen ) The film is measured for a film that is once heated to an inflection point in nitrogen and then cooled to room temperature at a heating rate of 10 ° C./min.

(Polyamideimide resin solution)
As a solvent for producing a solution of polyamideimide resin, an organic solvent not containing a halogen element, that is, a non-halogen organic solvent is preferable in consideration of the environment. Typical examples of such organic solvents include, for example, N-methyl-2-pyrrolidone, N, N-dimethylformamide, N, N-dimethylacetamide, 1,3-dimethyl-2-imidazolidinone, tetramethylurea, sulfolane. Dimethyl sulfoxide, γ-butyrolactone, cyclohexanone, cyclopentanone, etc., preferably N-methyl-2-pyrrolidone. When these solvents are used as polymerization solvents, they can be used as they are as solutions for producing flexible metal-clad laminates described later.

  Some of these can be replaced with hydrocarbon organic solvents such as toluene and xylene, ether organic solvents such as diglyme, triglyme and tetrahydrofuran, and ketone organic solvents such as methyl ethyl ketone and methyl isobutyl ketone.

  If necessary, the heat-resistant resin of the present invention is used for the purpose of improving various properties of the flexible metal-clad laminate or flexible printed circuit board, such as mechanical properties, electrical properties, slipperiness, and flame retardancy. Other resins, organic compounds, and inorganic compounds may be mixed or reacted with the solution. For example, lubricant (silica, talc, silicone, etc.), adhesion promoter, flame retardant (phosphorus, triazine, aluminum hydroxide, etc.), stabilizer (antioxidant, UV absorber, polymerization inhibitor, etc.), plating activity Agents, organic and inorganic fillers (talc, titanium oxide, fluoropolymer fine particles, pigments, dyes, calcium carbide, etc.), silicone compounds, fluorine compounds, isocyanate compounds, blocked isocyanate compounds, acrylic resins, urethane resins, Resins such as polyester resin, polyamide resin, epoxy resin, phenol resin and organic compounds, or these curing agents, inorganic compounds such as silicon oxide, titanium oxide, calcium carbonate, iron oxide, etc. are within the range not hindering the object of the present invention. Can be used together.

  The concentration of the polyamideimide resin in the polyamideimide resin solution (varnish) thus obtained can be selected from a wide range, but is generally about 5 to 40% by weight, and particularly preferably about 8 to 20% by weight. When the concentration is out of the above range, the coatability tends to be lowered.

  The hygroscopic dimensional change rate of the base film resin (for example, polyamideimide resin) is preferably 15 ppm /% RH or less. More preferably, it is 12 ppm /% RH or less, More preferably, it is 10 ppm /% RH or less. The lower limit is not particularly limited and is preferably closer to 0 ppm /% RH, but is preferably 0.1 ppm /% RH or more and more preferably 1 ppm /% RH or more from the viewpoint of ease of production. Preferably, it is 5 ppm /% RH or more. If the hygroscopic dimensional change rate exceeds 15 ppm /% RH, the curl of the flexible metal-clad laminate or the flexible printed wiring board during humidification may increase, or the yield during circuit processing may decrease. The moisture absorption dimensional change rate is measured by the following method.

  (1) A hole is made in a certain position of the metal-clad laminate according to IPC-FC 241 (IPC-TM-650, 2.2.4 (c)), and humidity is adjusted at 25 ° C. and 65% for 4 hours. Measure the distance between holes.

  (2) The front surface of the metal layer of the metal-clad laminate was removed with ferric chloride (etching), and the resulting resin film was subjected to 25% relative humidity in an atmosphere of 20%, 40%, 65%, and 90%. Condition at 24 ° C for 24 hours.

  (3) According to IPC-FC 241 (IPC-TM-650, 2.2.4 (c)), the distance between holes in the resin film is measured, and the distance between holes in the metal foil laminate in (1). The dimensional change rate is obtained based on the above.

  (4) The dimensional change rate of (3) is plotted against each relative humidity, and the slope with respect to the humidity is defined as the hygroscopic dimensional change rate.

  The thermal expansion coefficient of the base film is preferably 30 ppm / ° C. or less. More preferably, it is 25 ppm / ° C. or less, and further preferably 20 ppm / ° C. or less. The lower limit is not particularly limited, but it is preferably 5 ppm / ° C. or more because there is a tendency for strain to accumulate in the laminate when the deviation from the thermal expansion coefficient of the metal foil increases. Here, the thermal expansion coefficient was measured using a resin film layer obtained by etching and removing the metal foil of the flexible metal-clad laminate by TMA (Thermomechanical Analysis / Rigaku Corporation) tensile load method (load: 1 g, sample size: 4 ( Width) × 20 (length) mm, temperature increase rate: 10 ° C./min, atmosphere: nitrogen, measurement temperature range: 100 ° C. to 200 ° C.). In addition, the film shall be measured with respect to a film which is once heated to an inflection point in nitrogen at a heating rate of 10 ° C./min and then cooled to room temperature.

  If the coefficient of thermal expansion is too large, the dimensional stability will be reduced, and thereby curling of the flexible metal laminate (especially normal state or flexible metal laminate). When the body is heated (when moisture is released), the curl may become large, and as a result, the flexible printed wiring board on which the body is processed tends to become large in normal state or when heated.

  As polyamideimide resin, acid component is 100 mol%, trimellitic anhydride 70-90 mol% as acid component, 3,3 ′, 4,4′-benzophenone tetracarboxylic dianhydride 5-25 Mol% and 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride 5 to 25 mol%, and 3,3′-dimethyl-4,4′-biphenyl diisocyanate (or 3) as a diamine component , 3′-dimethyl-4,4′-biphenyldiamine), or trimellitic anhydride 70 to 90 mol% as an acid component and 3,3 ′, 4,4′-benzophenonetetracarboxylic dianhydride 5 to 25 mol% of 3,3 ', 4,4'-diphenyl ether tetracarboxylic dianhydride, and 3,3'-dimethyl as a diamine component Resin containing 4,4′-biphenyl diisocyanate (or 3,3′-dimethyl-4,4′-biphenyldiamine) is excellent in heat resistance, dimensional stability, adhesiveness, etc., and has insulation and solder even under humidification This is most preferable in that a flexible metal-clad laminate for flexible printed circuit boards with reduced heat resistance, curling, and dimensional change can be produced at low cost.

  A base film can contain arbitrary additives other than a resin component as needed. As such an additive, any additive conventionally used for an FPC substrate (for example, a flame retardant) can be used.

  The thickness of the base film layer is not particularly limited as long as it does not hinder the performance of the FPC. Preferably, the thickness after absolute drying is preferably 5 μm or more, more preferably 10 μm or more, and further preferably 20 μm or more. Moreover, it is preferably 200 μm or less, more preferably 150 μm or less, and still more preferably 100 μm or less. If the thickness is too thin, mechanical properties such as film strength and handling properties may be inferior. On the other hand, if the thickness is too thick, characteristics such as flexibility and workability (drying properties, coating properties) ), Etc. may decrease.

(Adhesive on the base film side of FPC)
In the FPC of the present invention, an adhesive on the base film side, that is, an adhesive between the base film and the conductor layer may be used, and an adhesive between the base film and the conductor layer may be used. You may laminate | stack a conductor layer directly on a base film, without using. When an adhesive is used between the base film and the conductor layer, the performance of the FPC may be deteriorated due to the adhesive. However, when the adhesiveness between the base film and the conductor layer is not sufficient, it is preferable to use an adhesive.

  When an adhesive layer is used between the base film and the conductor layer, a conventionally known adhesive can be used as an adhesive for FPC. For example, acrylonitrile butadiene rubber (NBR) adhesive, polyamide adhesive, polyester adhesive, polyacrylic adhesive, polyester polyurethane adhesive, and the like can be used.

Among them, a polyester polyurethane adhesive can be preferably used. More preferably, it is an adhesive described as an adhesive on the cover film side described later. Specifically, a preferred resin for the adhesive is, for example, a polyester polyurethane resin crosslinked with an epoxy resin. Here, Preferably, the total amount of terephthalic acid and isophthalic acid is 70 mol%-100 mol% among 100 mol% of the acid component of a polyester component. Preferably, the isocyanate component in the polyester polyurethane resin contains hexamethylene diisocyanate. Also preferably, the acid value of the polyester polyurethane resin is 100 to 1000 equivalents / 10 ⁶ g. Preferably, the number average molecular weight of the polyester polyurethane resin is 8000 to 100,000. Preferably, the epoxy resin is a mixture of a novolac type epoxy resin and a bisphenol A type epoxy resin.

  In a preferred embodiment, the adhesive described later as the adhesive on the cover film side can be used as the adhesive on the base film side.

  In one embodiment, the same adhesive as the adhesive on the cover film described later can be used as the adhesive on the base film side.

  When an adhesive is used between the base film and the conductor layer, the thickness of the adhesive layer is not particularly limited as long as it does not hinder the performance of the FPC. The thickness after absolutely dry is preferably 1 μm or more, more preferably 5 μm or more, and further preferably 10 μm or more. Moreover, it is preferably 150 μm or less, more preferably 100 μm or less, and further preferably 50 μm or less. If the thickness is too thin, it may be difficult to obtain sufficient adhesiveness. On the other hand, if the thickness is too thick, processability (drying property, coating property) and the like may be deteriorated.

(Conductor layer)
As the conductor layer used in the present invention, any conductive material usable for a circuit board can be used. For example, a metal foil can be used. Any conventionally known metal foil can be used. As the material, for example, copper foil, aluminum foil, steel foil, nickel foil and the like can be used, and composite metal foil obtained by combining these and metal foil treated with other metals such as zinc and chromium compounds are also used. be able to. Preferably, it is a copper foil.

  Although there is no limitation in particular about the thickness of metal foil, Preferably it is 1 micrometer or more, More preferably, it is 3 micrometers or more, More preferably, it is 10 micrometers or more. Moreover, it is preferably 50 μm or less, more preferably 30 μm or less, and still more preferably 20 μm or less. If the thickness is too thin, it may be difficult to obtain sufficient electrical performance of the circuit. On the other hand, if the thickness is too thick, the processing efficiency at the time of circuit fabrication may be reduced.

  The metal foil is usually provided in the form of a ribbon. The form of the metal foil used when manufacturing the FPC of the present invention is not particularly limited, and the length of the metal foil is not particularly limited when a ribbon-like metal foil is used. Also, the width of the ribbon-like metal foil is not particularly limited, but is generally about 25 to 300 cm, particularly about 50 to 150 cm.

(Adhesive layer on the cover film side of FPC)
The adhesive layer of the FPC of the present invention contains a polyester polyurethane resin crosslinked with an epoxy resin. Here, the polyester polyurethane resin has a number average molecular weight of 8000 to 100,000 before being crosslinked by the epoxy resin.

(Dibasic acid component of polyester polyol)
For the production of the polyester polyurethane resin used in the present invention, a polyester polyol is used. Any dibasic acid can be used as the dibasic acid component of the polyester polyol. For example, the following dibasic acids can be used:
Terephthalic acid, isophthalic acid, orthophthalic acid, 1,5-naphthalic acid, 2,6-naphthalic acid, 4,4′-diphenyldicarboxylic acid, 2,2′-diphenyldicarboxylic acid, 4,4′-diphenyletherdicarboxylic acid, etc. Aromatic dibasic acid, adipic acid, azelaic acid, sebacic acid, 1,4-cyclohexanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, 1,2-cyclohexanedicarboxylic acid, 4-methyl-1,2-cyclohexanedicarboxylic acid Aliphatic and alicyclic dibasic acids such as acids and dimer acids.

  Aromatic dibasic acids are preferred from the viewpoint of heat resistance. Moreover, in order to balance adhesiveness and heat resistance, it is also preferable to use an aliphatic dibasic acid in combination. In particular, terephthalic acid, isophthalic acid, orthophthalic acid, 2,6-naphthalic acid, and adipic acid are desirable.

  Aromatic dibasic acids are preferred from the viewpoint of heat resistance. Moreover, in order to balance adhesiveness and heat resistance, it is also preferable to use an aliphatic dibasic acid in combination. In particular, terephthalic acid, isophthalic acid, orthophthalic acid, 2,6-naphthalic acid, and adipic acid are desirable.

  It is preferable that 30 mol% or more of the dibasic acid component used for the polyester polyol is an aromatic dibasic acid.

(Glycol component)
Any glycol can be used as the glycol component of the polyester polyol. For example, the following glycols can be used:
Ethylene glycol, propylene glycol, 1,3-propanediol, 2-methyl-1,3-propanediol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol 1,5-pentanediol, 1,6-hexanediol, 3-methyl-1,5-pentanediol, neopentyl glycol, diethylene glycol, dipropylene glycol, 2,2,4 -Trimethyl-1,3-pentanediol, cyclohexanedimethanol, neopentylhydroxypivalate, bisphenol A ethylene oxide adduct and propylene oxide adduct, hydrogenated bisphenol A ethylene oxide adduct And propylene oxide adduct, 1,9-nonanediol, 2-methyloctanediol 1,10-dodecane diol, 2-butyl-2-ethyl-1,3-propanediol, tricyclodecanedimethanol.

  Of the above glycols, ethylene glycol, propylene glycol, 2-methyl-1,3-propanediol, diethylene glycol, neopentyl glycol, and cyclohexane dimethanol are preferred.

  It is also preferable to use polyether polyol as glycol. Specific examples include polyethers such as polyethylene glycol, polypropylene glycol, and polytetramethylene glycol.

(Isocyanate)
As the organic diisocyanate component used in the polyester polyurethane resin, any conventionally known diisocyanate can be used. Specifically, for example, the following diisocyanates can be used.
2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, p-phenylene diisocyanate, diphenylmethane diisocyanate, m-phenylene diisocyanate, hexamethylene diisocyanate, tetramethylene diisocyanate, 3,3′-dimethoxy-4,4′-biphenylene Diisocyanate, 1,5-naphthalene diisocyanate, 2,6-naphthalene diisocyanate, 3,3′-dimethyl-4,4′-diisocyanate, 4,4′-diisocyanate diphenyl ether, 1,5-xylylene diisocyanate, 1,3- Diisocyanate methylcyclohexane, 1,4-diisocyanate methylcyclohexane, 4,4′-diisocyanatecyclohexane, 4,4′-diisocyanatecyclohexylmethane, Isophorone diisocyanate.

(Acid value)
The acid value of the polyester polyurethane resin is not particularly limited. The acid value is preferably 0.5 equivalent / 10 ⁶ g or more, more preferably 2 equivalent / 10 ⁶ g or more, and further preferably 4 equivalent / 10 ⁶ g or more. Moreover, Preferably it is 1000 equivalent / 10 < ⁶ > g or less, In one embodiment, it is less than 100 equivalent / 10 < ⁶ > g. When the acid value is too large, the storage stability of the semi-finished product is likely to be lowered, and the water resistance and alkali resistance of the resin are likely to be lowered. If the acid value is too small, the heat resistance tends to decrease.

(Number average molecular weight)
The number average molecular weight of the polyester polyurethane resin is 8000 to 100,000. Preferably it is 10,000 or more, More preferably, it is 12000 or more, More preferably, it is 14000 or more. Moreover, it is preferably 80000 or less, more preferably 600000 or less, further preferably 40000 or less, and particularly preferably 20000 or less. When the number average molecular weight is too large, it is difficult to synthesize the resin, and the viscosity increases and the handleability of the resin tends to be lowered. When the number average molecular weight is too small, the bending resistance is liable to be lowered and the adhesiveness is also liable to be lowered.

  In the molecular weight distribution of the polyester polyurethane resin, the ratio of the molecular weight of 5,000 or less is preferably 20% by weight or less. If the proportion of the molecular weight is 5,000 or less, the heat resistance after curing tends to decrease.

  The number average molecular weight of the polyester polyol used as a raw material for the polyester polyurethane resin is preferably 1000 or more, more preferably 3000 or more, further preferably 7000 or more, and particularly preferably 10,000 or more. preferable. Moreover, it is preferable that it is 80000 or less, and it is more preferable that it is 50000 or less.

  In the polyester polyurethane resin, the proportion of the polyester component, that is, the polyester polyol is preferably 20% by weight or more, more preferably 40% by weight or more, and further preferably 60% by weight or more, 70 More preferably, it is at least% by weight. It is particularly preferably 75% by weight or more. Moreover, it is preferable that it is 95 weight% or less, and it is more preferable that it is 90 weight% or less. If the amount of polyester polyol is too small, the flexibility tends to decrease, and conversely if too large, the heat resistance tends to decrease.

  Therefore, regarding the ratio between the number average molecular weight of the polyester polyurethane resin and the number average molecular weight of the polyester polyol, it is preferable that the number average molecular weight of the polyester polyurethane resin is 100% and the number average molecular weight of the polyester polyol is 20% or more. More preferably, it is 40% or more, more preferably 60% or more, and even more preferably 70% or more. It is particularly preferably 75% or more. Moreover, it is preferable that it is 95% or less, and it is more preferable that it is 90% or less.

(Epoxy resin)
In the above adhesive, the polyester polyurethane resin is cross-linked using an epoxy resin. Here, any epoxy resin can be used as the epoxy resin. Novolac type epoxy resins and bisphenol A type epoxy resins are preferred. A novolac type epoxy resin is more preferable.

  Specific examples of the epoxy resin include glycidyl ether types such as bisphenol A diglycidyl ether, bisphenol S diglycidyl ether, novolac glycidyl ether, brominated bisphenol A diglycidyl ether, hexahydrophthalic acid glycidyl ester, and dimer acid glycidyl ester. Examples include glycidyl ester types such as triglycidyl isocyanurate, glycidyl amines such as tetraglycidyl diaminodiphenylmethane, and alicyclic or aliphatic epoxides such as 3,4-epoxycyclohexylmethylcarboxylate, epoxidized polybutadiene, and epoxidized soybean oil. It is done.

  About the compounding quantity of an epoxy resin, it is preferable to mix | blend so that the equivalent ratio of the sum total of the carboxyl group in a polyurethane and the glycidyl group in all the epoxy resins may be 1: 0.5-1: 5, More preferably One to one to one to three. When the amount of epoxy resin is too small, the degree of crosslinking tends to be low, so that the heat resistance may be lowered. When the amount is too large, the amount of unreacted epoxy resin remaining in the final product of FPC tends to increase, and the remaining unreacted epoxy resin may reduce performance such as heat resistance.

  The epoxy equivalent of the epoxy resin is preferably 100 or more, more preferably 150 or more. Moreover, Preferably it is 1000 or less, More preferably, it is 700 or less.

(Curing agent)
Any conventionally known curing agent for epoxy resins can be used as the curing agent that catalyzes the curing reaction of the epoxy resin.
Diaminodiphenylmethane, diaminodiphenyl sulfide, diaminobenzophenone, diaminodiphenylsulfone, amine compounds such as diethyltriamine, triethylamine, benzyldimethylamine, basic compounds such as triphenylphosphine, 2-alkyl-4-methylimidazole, 2-phenyl- Imidazole derivatives such as 4-alkylimidazole, phthalic anhydride, tetrahydrophthalic anhydride, trimellitic anhydride, 3,4,3 ′, 4′-benzophenone tetracarboxylic acid, ethylene glycol bis (anhydrotrimellitate), etc. Examples thereof include acid anhydrides, boron trifluoride amine complexes such as boron trifluoride triethylamine complex, and dicyandiamide. You may use these individually or in mixture of 2 or more types. An acid anhydride is preferable, and tetrahydrophthalic anhydride and ethylene glycol bis (anhydrotrimellitate) are more preferable.

  When an acid anhydride is used, the blending amount thereof is preferably 1 part by weight or more, more preferably 3 parts by weight or more, and still more preferably with respect to 100 parts by weight of the solid content of the polyester polyurethane resin. 5 parts by weight or more. Moreover, Preferably it is 20 weight part or less, More preferably, it is 15 weight part or less, More preferably, it is 10 weight part or less.

  In the case of using an acid anhydride, the acid anhydride reacts with the epoxy to generate a part of carboxyl group, so that the acid value of the resin can be adjusted by using the acid anhydride. That is, the acid anhydride can serve not only as a curing agent but also as a function of adjusting the acid value.

  When an imidazole derivative is used as the curing catalyst, the blending amount is preferably 0.01 parts by weight or more, more preferably 0.1 parts by weight or more with respect to 100 parts by weight of the solid content of the polyester polyurethane resin. is there. Moreover, Preferably it is 5 weight part or less, More preferably, it is 3 weight part or less, More preferably, it is 1 weight part or less. If the amount used is too small, the epoxy resin may not be sufficiently cured. If it is too high, the curing agent remaining in the final product may adversely affect the performance of the product. If necessary, an adhesion improver such as an acrylic phosphorus-containing monomer may be further blended.

(Glass-transition temperature)
Although the glass transition temperature (Tg) of the polyester polyurethane resin used for an adhesive agent is not specifically limited, Preferably it is -20 degreeC or more, More preferably, it is -10 degreeC or more, More preferably, it is 0 degreeC or more. Further, it is preferably 50 ° C. or lower, more preferably 40 ° C. or lower, still more preferably 35 ° C. or lower, and particularly preferably 30 ° C. or lower. When the glass transition temperature is too low, it is difficult to obtain sufficient heat resistance. When the glass transition temperature is too high, it is difficult to obtain sufficient adhesion.

(Inorganic filler)
An inorganic filler may be added to the adhesive as necessary. Inorganic fillers that can be used include metal hydroxides such as aluminum hydroxide, magnesium hydroxide, calcium aluminate hydrate, silica, alumina, zinc oxide, antimony trioxide, antimony pentoxide, magnesium oxide, oxidation Examples thereof include metal oxides such as titanium, inorganic salts such as calcium carbonate, and carbon black. These inorganic fillers may be used alone or in combination of two or more. For example, if aluminum hydroxide is used, flame retardancy can be improved.

  The inorganic filler may be surface-treated as necessary. Examples of the surface treatment agent include silane coupling agents such as 3-aminopropyltriethoxysilane and 3-glycidoxypropyltrimethoxysilane, and silane compounds such as hexamethyldisilazane and chlorosilane.

  The amount of the inorganic filler added is preferably 1 part by weight or more, more preferably 10 parts by weight or more, still more preferably 30 parts by weight or more, and particularly preferably 50 parts by weight or more with respect to 100 parts by weight of the solid content of the resin component. 500 parts by weight or less is preferable, 300 parts by weight or more is more preferable, 200 parts by weight or less is more preferable, and 150 parts by weight or more is particularly preferable. When the amount is too small, it is difficult to obtain the effect of adding the filler. When the amount is too large, the viscosity of the adhesive may increase and workability may decrease.

  The particle size of the inorganic filler is preferably 20 μm or less, more preferably 10 μm or less, and even more preferably 5 μm or less. Moreover, it is preferably 0.01 μm or more, more preferably 0.1 μm or more, and further preferably 0.5 μm or more. If the particle size is too large, the wiring pattern may be adversely affected, and those having a very small particle size may be difficult to obtain.

  Any additive conventionally known to be used for an FPC adhesive can be added to the adhesive as necessary. For example, an antioxidant or an ion scavenger can be added.

  The thickness of the adhesive layer between the cover film and the conductor layer is not particularly limited as long as it does not hinder the performance of the FPC. Preferably it is 1 micrometer or more, More preferably, it is 5 micrometers or more, More preferably, it is 10 micrometers or more. Moreover, it is preferably 100 μm or less, more preferably 50 μm or less. If the thickness is too thin, it may be difficult to obtain sufficient adhesiveness. On the other hand, if the thickness is too thick, processability (drying property, coating property) and the like may be deteriorated.

  Moreover, about the part from which the conductor layer was removed by the etching etc., an adhesive agent adhere | attaches between a cover film and a base film (or base film side adhesive). The thickness of the adhesive in this portion is a thickness obtained by adding the thickness of the conductor layer to the thickness of the adhesive layer between the cover film and the conductor layer described above.

(Cover film)
As the cover film, any conventionally known insulating film can be used as an insulating film for FPC. For example, films produced from various polymers such as polyimide, polyester, polyphenylene sulfide, polyethersulfone, polyetheretherketone, aramid, polycarbonate, polyarylate, polyimide, and polyamideimide can be used. More preferably, it is a polyimide film or a polyamidoimide film, More preferably, it is a polyimide film.

  As the resin for the cover film, a resin containing halogen may be used, or a resin not containing halogen may be used. From the viewpoint of environmental problems, a resin containing no halogen is preferable. However, from the viewpoint of flame retardancy, a resin containing halogen can also be used.

  A polyimide film has a polyimide resin as a main component as its resin component. Of the resin components, 90% by weight or more is preferably polyimide, more preferably 95% by weight or more is polyimide, more preferably 98% by weight or more is polyimide, and 99% by weight or more is polyimide. It is particularly preferred. Any conventionally known resin can be used as the polyimide resin.

  Specifically, the polyimide film preferably has the following repeating unit.

Ｒ^７、Ｒ^８は二価の有機残基である。

R ⁷ and R ⁸ are divalent organic residues.

  Polyimide can be polymerized by a conventionally known method such as a low temperature solution polymerization method for synthesizing a precursor polyamic acid. When the polyimide is soluble in an organic solvent, it can also be produced by an isocyanate method or a solution polymerization method in which polyamic acid is chemically or thermally dehydrated in solution.

  Examples of the solvent for producing the polyimide resin solution used in the present invention include N-methyl-2-pyrrolidone, N, N-dimethylformamide, N, N-dimethylacetamide, and 1,3-dimethyl-2-imidazo. Examples include lydinone, tetramethylurea, sulfolane, dimethylsulfoxide, γ-butyrolactone, cyclohexanone, cyclopentanone, and preferably dimethylacetamide. If the polyamic acid produced is soluble, hydrocarbon organic solvents such as toluene and xylene, ether organic solvents such as diglyme, diethylene glycol diethyl ether, triglyme, and tetrahydrofuran, cyclohexanone, cyclopentanone, methyl ethyl ketone, methyl isobutyl Ketone organic solvents such as ketones can also be used, and diglyme is particularly preferred. These solvents can be used in a mixed system of two or more.

  The monomers used are as follows.

  As the acid component, 3,3 ′, 4,4′-benzophenone tetracarboxylic acid, 3,3 ′, 4,4′-biphenyltetracarboxylic acid, 3,3 ′, 4,4′-diphenyl ether tetracarboxylic acid, Alkylene glycol bis (anhydrotrimellitate), 2,2-bis (4-hydroxyphenyl) propanedibenzoate-3,3 ′, 4,4′-tetracarboxylic dianhydride, pyromellitic acid, 3,3 '-Diphenylsulfonetetracarboxylic acid, naphthalene-2,3,6,7-tetracarboxylic acid, naphthalene-1,2,4,5-tetracarboxylic acid, naphthalene-1,4,5,8-tetracarboxylic acid, etc. Monoanhydride, dianhydride, esterified product, etc. can be used alone or as a mixture of two or more.

  A preferred embodiment of the acid component is a polyimide having pyromellitic acid in an amount of 50 to 100 mol%, more preferably 70 to 100 mol%, and still more preferably 80 to 100 mol%. Good FPC such as flexibility and curl (warp) can be manufactured.

  Examples of the amine component include 3,3′-dimethyl-4,4′-diaminobiphenyl, 3,3′-diethyl-4,4′-diaminobiphenyl, 2,2′-dimethyl-4,4′-diamino. Biphenyl, 2,2′-diethyl-4,4′-diaminobiphenyl, 3,3′-dimethoxy-4,4′-diaminobiphenyl, 3,3′-diethoxy-4,4′-diaminobiphenyl, p-phenylene Diamine, m-phenylenediamine, 3,4'-diaminodiphenyl ether, 4,4'-diaminodiphenyl ether, 4,4'-diaminodiphenyl sulfone, 3,3'-diaminodiphenyl sulfone, 3,4'-diaminobiphenyl, 3 , 3′-diaminobiphenyl, 3,3′-diaminobenzanilide, 4,4′-diaminobenzanilide, 4,4 ′ Diaminobenzophenone, 3,3′-diaminobenzophenone, 3,4′-diaminobenzophenone, 2,6-tolylenediamine, 2,4-tolylenediamine, 4,4′-diaminodiphenyl sulfide, 3,3′-diamino Diphenyl sulfide, 4,4′-diaminodiphenylpropane, 3,3′-diaminodiphenylpropane, 3,3′-diaminodiphenylmethane, 4,4′-diaminodiphenylmethane, p-xylenediamine, m-xylenediamine, 1,4 -Naphthalenediamine, 1,5-naphthalenediamine, 2,6-naphthalenediamine, 2,7-naphthalenediamine, 2,2'-bis (4-aminophenyl) propane, 1,3-bis (3-aminophenoxy) Benzene, 1,3-bis (4-aminophenoxy) benzene 1,4-bis (4-aminophenoxy) benzene, 2,2-bis [4- (4-aminophenoxy) phenyl] propane, bis [4- (4-aminophenoxy) phenyl] sulfone, bis [4- ( 3-aminophenoxy) phenyl] sulfone, bis [4- (3-aminophenoxy) phenyl] propane, 4,4′-bis (4-aminophenoxy) biphenyl, 4,4′-bis (3-aminophenoxy) biphenyl Or the diisocyanate etc. corresponding to these can be used individually or in mixture of 2 or more types.

  Among the diamine components of the polyimide resin, a preferred embodiment is a polyimide in which 5-70 mol%, more preferably 10-50 mol%, still more preferably 15-40 mol% is p-phenylenediamine, and this range. By doing so, it is possible to manufacture an FPC having good dimensional stability, curling (warping), moisture absorption characteristics (insulation when humidifying, curling, etc.) and the like. If p-phenylenediamine is 5 mol% or less, the effect of these characteristics may be reduced, and if it exceeds 70 mol%, the bending characteristics may be deteriorated.

  The resin solution obtained as described above can be heated as it is, or a dehydrating agent (aliphatic acid anhydride; acetic anhydride, aromatic acid anhydride, etc.) with a stoichiometric amount or more and a catalytic amount of a tertiary amine. (Triethylamine, pyridine, quinoline, etc.) are mixed and chemically and / or thermally imidized to form polyimide. The solution is cast on a carrier such as an endless belt or a film, and after removing the solvent at a temperature of about 50 ° C. to 150 ° C., a self-supporting film is peeled off, and then peeled off in a heating furnace such as a pin tenter system. Or it can be set as a polyimide film by heat-processing at the temperature of 50 to 600 degreeC, extending | stretching to a TD direction.

  The molecular weight of the polyimide resin (when the polyimide resin is insoluble in N-methyl-2-pyrrolidone, the precursor polyamic acid) is 30 in N-methyl-2-pyrrolidone (polymer concentration 0.5 g / dl), 30 Those having a molecular weight corresponding to 0.3 to 2.5 dl / g in terms of logarithmic viscosity at ° C. are preferred, more preferably those having a molecular weight corresponding to 0.8 to 2.0 dl / g. If the logarithmic viscosity is too low, the mechanical properties may be insufficient when formed into a molded product such as a film, and if it is too high, the solution viscosity will be high, making molding difficult. There is.

  The polyamide-imide film has a polyamide-imide resin as a main component as its resin component. Of the resin components, 90% by weight or more is preferably polyamideimide, more preferably 95% by weight or more is polyamideimide, more preferably 98% by weight or more is polyamideimide, and 99% by weight or more. Is particularly preferably polyamideimide.

  Specifically, any conventionally known resin film can be used as the polyamideimide film. In particular, the film described for the base film can be preferably used. Specifically, for example, in 100 mol% of the acid component of the polyamideimide resin, 70 to 90 mol% of trimellitic anhydride as an acid component, and 3,3 ′, 4,4′-benzophenone tetracarboxylic acid dicarboxylic acid are used. Containing 5 to 25 mol% of anhydride and 5 to 25 mol% of 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride, and 3,3′-dimethyl-4,4′-biphenyl as a diamine component Polyamideimide resin containing diisocyanate is preferred.

  Moreover, trimellitic anhydride 70-90 mol%, 3,3 ', 4,4'-benzophenone tetracarboxylic dianhydride 5-25 mol%, 3,3', 4,4 'as an acid component Polyamideimide resin containing 5 to 25 mol% of diphenyl ether tetracarboxylic dianhydride and containing 3,3′-dimethyl-4,4′-biphenyl diisocyanate as a diamine component is also preferable.

  The molecular weight of the polyamide-imide resin has a molecular weight corresponding to 0.3 to 2.5 dl / g in N-methyl-2-pyrrolidone (polymer concentration 0.5 g / dl) and a logarithmic viscosity at 30 ° C. Preferably, it has a molecular weight corresponding to 0.8 to 2.0 dl / g. If the logarithmic viscosity is too low, the mechanical properties may be insufficient when formed into a molded product such as a film, and if it is too high, the solution viscosity will be high, making molding difficult. There is.

  The absorbance ratio of the imide bond of the polyamide-imide resin to the benzene nucleus is preferably 0.9 or more. More preferably, it is 1.0 or more. The upper limit is not particularly limited, but is preferably less than 5.0 from the viewpoint of solvent solubility. If the absorbance of the imide bond is less than 0.9, the hygroscopic property of the resin is lowered, and the dielectric breakdown voltage of the flexible printed circuit board, the temporal stability of the insulation resistance of the line, and the solder heat resistance after the humidification process are reduced. It tends to get worse. The absorbance ratio is measured by the method described above.

  It is preferable that the ionic impurity in resin (for example, polyimide resin) of a cover film is 2 mg / kg or less. More preferably, it is 1.5 mg / kg or less, More preferably, it is 1 mg / kg or less. The lower limit is not particularly limited, but is preferably as close to 0 mg / kg as possible. If the ionic impurity exceeds 2 mg / kg, solder heat resistance / insulation after humidification described later may be deteriorated. Ionic impurities are measured by the method described above.

  The acid value of the cover film resin (for example, polyimide resin) is preferably 150 μeq / g or less. More preferably, it is 130 microeq / g or less, More preferably, it is 120 microeq / g or less. If the acid value exceeds 150 μeq / g, the hygroscopic properties of the resin will deteriorate, and the dielectric breakdown voltage of the flexible printed circuit board, the stability over time of the insulation resistance between lines, and the solder heat resistance after humidification will tend to deteriorate. It is in. The lower limit of the acid value is not particularly from the viewpoint of the dielectric breakdown voltage of the flexible printed circuit board, the temporal stability of the insulation resistance between the lines, or the solder heat resistance after the humidification treatment, but if it is too low, the adhesive strength is lowered. Tend to. This lower limit value varies depending on the value of the insolubility rate of the heat-resistant resin film layer described later, and is particularly preferably 5 μeq / g or more when the insolubility rate is high. This is presumably because the higher the insolubility, the higher the degree of crosslinking of the resin film layer, and as a result, the mechanical properties such as the elastic modulus tend to change, which affects the adhesiveness.

  In the resin of the cover film (for example, polyimide resin), the acid value and the absorbance of the imide bond can be controlled by the polymerization conditions such as the polymerization temperature and the polymerization time. It can be controlled by the use of a sealant or the amount of anhydride groups in the acid component (control of monomer purity and moisture).

  The glass transition temperature of the cover film resin (eg, polyimide resin) is preferably 250 ° C. or higher. More preferably, it is 280 degreeC or more, More preferably, it is 300 degreeC or more. Although an upper limit is not specifically limited, It is preferable that it is less than 450 degreeC at the point of varnish stability. If the glass transition temperature is too low, solder heat resistance may be reduced. The glass transition temperature is measured by a tensile load method of thermomechanical analysis using a resin film as a sample (load: 1 g, sample size: 4 (width) × 20 (length) mm, temperature increase rate: 10 ° C./min, atmosphere: nitrogen ) The film is measured for a film that is once heated to an inflection point in nitrogen and then cooled to room temperature at a heating rate of 10 ° C./min.

  The hygroscopic dimensional change rate of the cover film resin (for example, polyimide resin) is preferably 15 ppm /% RH or less. More preferably, it is 12 ppm /% RH or less, More preferably, it is 10 ppm /% RH or less. The lower limit is not particularly limited and is preferably closer to 0 ppm /% RH, but is preferably 0.1 ppm /% RH or more and more preferably 1 ppm /% RH or more from the viewpoint of ease of production. Preferably, it is 5 ppm /% RH or more. If the hygroscopic dimensional change rate exceeds 15 ppm /% RH, the curl of the flexible metal-clad laminate or the flexible printed wiring board during humidification may increase, or the yield during circuit processing may decrease. The measuring method of the moisture absorption dimensional change rate is as described above.

  The cover film preferably has a thermal expansion coefficient of 30 ppm / ° C. or less. More preferably, it is 25 ppm / ° C. or less, and further preferably 20 ppm / ° C. or less. The lower limit is not particularly limited, but it is preferably 5 ppm / ° C. or more because there is a tendency for strain to accumulate in the laminate when the deviation from the thermal expansion coefficient of the metal foil increases.

  If the coefficient of thermal expansion is too large, the dimensional stability will be reduced, and thereby curling of the flexible metal laminate (especially normal state or flexible metal laminate). When the body is heated (when moisture is released), the curl may become large, and as a result, the flexible printed wiring board on which the body is processed tends to become large in normal state or when heated.

  The glass transition temperature of the cover film resin (eg, polyamideimide resin) is preferably 250 ° C. or higher. More preferably, it is 280 degreeC or more, More preferably, it is 300 degreeC or more. The upper limit is not particularly limited, but is preferably less than 450 ° C. in terms of varnish stability. If the glass transition temperature is too low, solder heat resistance may be reduced.

  A cover film can contain arbitrary additives as needed other than a resin component. As such an additive, any additive conventionally used for an FPC substrate (for example, a flame retardant) can be used.

  The thickness of the cover film layer is not particularly limited as long as it does not hinder the performance of the FPC. The thickness after absolutely dry is preferably 5 μm or more, more preferably 10 μm or more, and further preferably 20 μm or more. Moreover, it is preferably 200 μm or less, more preferably 150 μm or less, and still more preferably 100 μm or less. If the thickness is too thin, mechanical properties such as film strength and handling properties may be inferior. On the other hand, if the thickness is too thick, characteristics such as flexibility and workability (drying properties, coating properties) ), Etc. may decrease.

  In addition, you may surface-treat to a cover film as needed. For example, surface treatment such as hydrolysis, corona discharge, low temperature plasma, physical roughening, and easy adhesion coating treatment can be performed.

(FPC manufacturing method)
The FPC of the present invention can be manufactured using any conventionally known process except that the material of each layer described above is used.

  In a preferred embodiment, a semi-finished product in which an adhesive layer is laminated on a cover film layer (hereinafter referred to as “cover film-side semi-finished product”) is produced. On the other hand, an adhesive layer is laminated on a semi-finished product (hereinafter referred to as “base film side two-layer semi-product”) or a base film layer in which a desired circuit pattern is formed by laminating a metal foil layer on the base film layer. And a semi-finished product (hereinafter referred to as “base film side three-layer semi-product”) having a desired circuit pattern formed by laminating a metal foil layer thereon (hereinafter referred to as base film side two-layer semi-product) The base film side three-layer semi-finished product is collectively referred to as “base film side semi-finished product”). A four-layer or five-layer FPC can be obtained by laminating the cover film-side semi-finished product and the base film-side semi-finished product thus obtained.

(Manufacturing method of base film side semi-finished product)
The base film side semi-finished product is, for example,
(A) Step of applying a polyamide-imide resin solution to the metal foil and initial drying of the coating film (B) Step of heat-treating and drying the laminate of the metal foil obtained in (A) and the initial drying coating film (Hereafter referred to as “heat treatment / solvent removal process”)
It is obtained by the manufacturing method containing.

  The temperature and time conditions during the heat treatment / solvent removal step are preferably performed so that the insoluble rate of the applied resin layer is 1% or more after the heat treatment / solvent removal step. If the insolubility is less than 1%, depending on the composition of the heat-resistant resin, the solder heat resistance and insulation of the flexible metal-clad laminate and the flexible printed circuit board on which the circuit is processed, in particular, the solder heat resistance after humidification treatment, Insulation (line breakdown voltage, stability over time of line insulation resistance) may be insufficient.

In particular, in the present invention, in addition to the characteristics of the heat resistant resin to be used, it is one point that the heat resistant resin film layer maintains a certain degree of cross-linked structure. By setting it as% or more, it is possible to obtain a flexible metal-clad laminate that is excellent in solder heat resistance and insulation after moisture treatment (insulation resistance between lines, temporal stability of insulation resistance between lines). this is,
・ Reduced functional groups such as carboxyl groups that adversely affect moisture absorption properties due to cross-linking reactions,
-The physical heat resistance of the resin film layer is improved by the crosslinking reaction,
This is considered to be an effect of the above.

  The insoluble rate indicates the insoluble content of the resin layer after dissolving only the resin layer excluding the metal foil with a 0.5 wt% concentration solution in N-methyl-2-pyrrolidone at 100 ° C. for 2 hours. Is shown by the following formula.

Insolubility (%) = [Mi / Mf] × 100
(In the formula, Mi represents the weight (g) of insoluble matter, and Mf represents the weight (g) of the resin film.)
The upper limit of the insoluble rate varies depending on the acid value of the polyamideimide resin to be used, but is usually 99% or less, preferably 85% or less. In particular, when the acid value of the resin used is low, the adhesive strength tends to decrease at an insoluble rate of 99% or more.

  In addition, when the formed heat resistant resin film layer is soluble in a solvent, the acid value of the part soluble in the solvent is 5 to 150 μeq / g. If it is 5 μeq / g or less, the adhesive strength tends to be low, and if it is 150 μeq / g or more, the temporal stability of the line breakdown voltage and the line insulation resistance tends to be poor.

  The specific heat treatment temperature is desirably (Tg + 50) ° C. or lower. In view of productivity, the lower limit of the heat treatment / solvent removal temperature is preferably (Tg−250) ° C. Here, Tg represents the glass transition point of the polyamideimide resin expressed in Celsius.

(Circuit formation)
A conventionally known method can be used to form a circuit in the metal foil layer. An active method may be used and a subtractive method may be used. The subtractive method is preferable.

  The circuit wiring pattern can be any pattern. In particular, since the FPC of the present invention exhibits a high level of performance even in a circuit including a fine wiring pattern, the FPC of the present invention is particularly advantageous in a circuit including a fine wiring pattern.

  Specifically, in the fine wiring pattern portion, the wiring thickness of the circuit can be 300 μm or less, the wiring thickness can be 150 μm or less, and the wiring thickness can be reduced. The thickness of the wiring can be set to 70 μm or less, and preferably 50 μm or less. The thickness of the wiring is preferably 1 μm or more, more preferably 10 μm or more, further preferably 20 μm or more, and particularly preferably 30 μm or more from the viewpoint of the electrical performance of the wiring.

  In a fine wiring pattern portion, the wiring interval can be 300 μm or less, can be 150 μm or less, can be 100 μm or less, and can be 70 μm or less. Yes, preferably 50 μm or less. The distance between the wirings is preferably 1 μm or more, more preferably 10 μm or more, further preferably 20 μm or more, and particularly preferably 30 μm or more from the viewpoint of the electrical performance of the wiring.

  In the fine wiring pattern portion, the sum of the wiring thickness and the wiring interval (circuit pitch) can be 600 μm or less, can be 300 μm or less, and can be 200 μm or less. Yes, it can be 150 μm or less. The circuit pitch is preferably 2 μm or more, more preferably 20 μm or more, still more preferably 60 μm or more, and particularly preferably 100 μm or more from the viewpoint of the electrical performance of the wiring.

  The obtained base film side semi-finished product may be used as it is for pasting with the cover film side semi-finished product. May be used.

  The obtained base film-side semi-finished product is excellent in thermal dimensional stability, so that it is a semi-finished product that hardly causes curling. For example, a semi-finished product having a curl radius of curvature of 70 mm or more after humidification (40 ° C., 90% RH, 24 hours) can be obtained, and the curl radius of curvature after heating (100 ° C., 1 hour) A semi-finished product that is 70 mm or more can be obtained.

(Manufacturing method for semi-finished products on the cover film side)
The cover film side semi-finished product is manufactured, for example, by applying an adhesive to the cover film. If necessary, a crosslinking reaction in the applied adhesive can be performed. In a preferred embodiment, the adhesive layer is semi-cured.

  The obtained cover film-side semi-finished product may be used as it is for pasting with the base-side semi-finished product, or after being laminated and stored with the release film for pasting with the base-film-side semi-finished product. May be used.

(Lamination of base film side semi-finished product and cover film side semi-finished product)
The base film-side semi-finished product and the cover film-side semi-finished product are each stored, for example, in the form of a roll and then bonded to produce an FPC. Arbitrary methods can be used as a method of bonding, for example, it can bond using a press or a roll. Moreover, both can also be bonded together, heating by the method of using a heating press or a heating roll apparatus.

  For example, if the adhesive layer in the semi-finished product is in an uncured or semi-cured state, it can be cured by proceeding with the crosslinking reaction of the adhesive layer by heating at the time of bonding. A final product in which the agent layer is completely cured can be easily obtained.

  The obtained final product is excellent in thermal dimensional stability, and thus is a product that is less likely to curl. For example, a product having a curl radius of curvature of 70 mm or more after humidification (40 ° C., 90% RH, 24 hours) can be obtained, and a curl radius of curvature after heating (100 ° C., 1 hour) is 70 mm. The product which is the above can be obtained.

(Use)
The FPC of the present invention can be used for various products for which FPC has conventionally been used. In particular, it can be suitably used for applications that require thin wiring and applications that require a narrow interval between wirings. For example, it is suitable for products whose wiring thickness is 100 μm or less. Further, for example, it is suitable for a product having a wiring interval of 300 μm or less, more suitable for a product having a wiring interval of 150 μm or less, and further suitable for a product having a wiring interval of 100 μm or less. Therefore, it can be suitably used for applications in which the sum (circuit pitch) of the wiring thickness and the wiring interval is narrow. It is suitable for products having a circuit pitch of 600 μm or less, more suitable for products having a circuit pitch of 300 μm or less, further suitable for products having a circuit pitch of 200 μm or less, and particularly suitable for products having a circuit pitch of 150 μm or less.

  Further, the FPC of the present invention can be suitably used for applications where a high voltage is applied. For example, it can be used for applications where a voltage of 100 V or higher is applied, can be used for applications where a voltage of 150 V or higher is applied, and can be used for applications where a voltage of 200 V or higher is applied.

  Further, the FPC of the present invention can be suitably used for applications that require a high level of bending performance. For example, it can be suitably used for an application in which bending and stretching at a very high frequency is repeated, such as a bent portion of a mobile phone.

  Specific examples of the final product in which the FPC of the present invention is used include, for example, a plasma display and a mobile phone.

Usually, a flexible printed wiring board used for applications where a high voltage is applied, for example, a flexible printed wiring board used in the periphery of a display such as a plasma display, has a line insulation resistance of 1.0 even under humidification. It is necessary to maintain insulation reliability with × 10 ¹⁰ Ω or more and a dielectric breakdown voltage between lines of 1.0 KV or more, and the conventional flexible printed wiring board has insufficient insulation reliability, but the flexible printed wiring board of the present invention Exhibits excellent reliability even in such applications. In addition, the time-dependent stability of the insulation breakdown voltage between lines and the insulation resistance between lines is the normal state of each value after heating and humidification treatment with a voltage of 100 V or more applied to the conductor circuit of the flexible printed circuit board. This is a comparison value for the value at.

  In the following, non-limiting examples of the invention are described.

  Each measurement evaluation item of polyester resin and polyester polyurethane resin followed the following method. In addition, each measurement evaluation item of polyester polyurethane resin measured each solid according to the following method by removing the solvent by drying the solution obtained by the following synthesis example at 120 degreeC for 1 hour.

(1) Resin composition: ¹ H-NMR analysis was performed using a nuclear magnetic resonance analyzer (NMR) Gemini-200 manufactured by Varian in a deuterated chloroform solvent, and the integral ratio was determined.

  (2) Number average molecular weight: Calculated from the results of GPC measurement at a column temperature of 35 ° C. and a flow rate of 1 ml / min using Waters Gel Permeation Chromatography (GPC) 150c with tetrahydrofuran as an eluent, A measurement value in terms of polystyrene was obtained. However, Showa Denko Co., Ltd. shodex KF-802, 804, 806 was used for the column.

  (3) Glass transition temperature: 5 mg of sample was put in an aluminum sample pan and sealed, and the differential scanning calorimetry (DSC) DSC-220 manufactured by Seiko Instruments Inc. was used to increase the temperature up to 200 ° C. and the heating rate was 20 ° C. Measured at / min. The glass transition temperature was determined by the temperature at the intersection of the extended line of the baseline and the tangent showing the maximum slope at the transition.

(4) Measurement of acid value: 0.2 g of sample was dissolved in 20 cm ³ of chloroform and titrated with 0.1 N potassium hydroxide ethanol solution to obtain the equivalent (eq / 10 ⁶ g) per 10 ⁶ g of resin. It was. Phenolphthalein was used as the indicator.

(Example of polyester synthesis)
In a reaction vessel equipped with a thermometer, stirrer, reflux condenser and distillation tube, 49.8 parts of terephthalic acid, 49.8 parts of isophthalic acid, 58.4 parts of adipic acid, 74.4 parts of ethylene glycol, neopentyl glycol 83.2 parts and 0.07 part of tetrabutyl titanate were added, the temperature was gradually raised to 230 ° C. over 4 hours, and the esterification reaction was carried out while removing distilled water out of the system. Subsequently, this was subjected to reduced pressure initial polymerization up to 10 mmHg over 20 minutes and the temperature was raised to 240 ° C., and further late polymerization was performed at 1 mmHg or less for 30 minutes to obtain a polyester. The characteristic values of the polyester thus obtained were as follows.

Resin composition Acid component: Terephthalic acid 30 mol%
Isophthalic acid 30 mol%
Adipic acid 40 mol%
Glycol component: Ethylene glycol 49 mol%
Neopentyl glycol 51 mol%
Number average molecular weight: 1500
Glass transition temperature: 12 ° C
Acid value: 13 equivalent / t
(Synthesis example of polyester polyurethane)
A reaction vessel equipped with a thermometer, a stirrer and a distillation tube was charged with 100 parts of the polyester obtained by the polyester synthesis example and 100 parts of toluene, and the resin was dissolved at 100 ° C. Thereafter, the temperature was raised to 130 ° C., 60.3 parts of toluene was distilled, and the reaction system was dehydrated by azeotropic distillation of toluene and water. Thereafter, the system was cooled to 60 ° C., 39.7 parts of methyl ethyl ketone and 3 parts of neopentyl glycol were charged, and the mixture was stirred at 60 ° C. for 30 minutes. Thereafter, 16 parts of 1,6-hexamethylene diisocyanate was charged and stirred at 60 ° C. for 30 minutes. Subsequently, 0.2 part of dibutyltin dilaurate was added, the temperature was raised to 80 ° C., the reaction was performed, and after completion of the reaction, 99.1 parts of methyl ethyl ketone was added to adjust the solid content concentration to 40% to obtain the desired polyester polyurethane. . The characteristic values of the polyester polyurethane thus obtained were as follows.

Number average molecular weight: 18000
Glass transition temperature: 15 ° C
Acid value: 10 equivalent / t
(Manufacturing example of adhesive)
In a reaction vessel equipped with a thermometer, a stirrer, and a reflux condenser, 250 parts of the polyester polyurethane solution obtained in the synthesis example of polyester polyurethane, 120 parts of methyl ethyl ketone, and BREN-S (Nippon Kayaku Co., Ltd.) as a curing agent 40 parts brominated phenol novolac type epoxy resin), 5 parts 3,3 ′, 4,4′-benzophenonetetracarboxylic dianhydride, Ricacid TMTA-C (glycerol manufactured by Shin Nippon Rika Co., Ltd.) 3 parts of anhydrotrimellitate) are charged, dissolved at 50 ° C., and 1.6 parts of 2PHZ-CN (imidazole compound manufactured by Shikoku Chemicals Co., Ltd.) as a curing catalyst, C11Z-A (Shikoku Chemicals). 0.4 part of 2,4-diamino-6- (2′-undecylimidazolyl) -ethyl-s-triazine) manufactured by Co., Ltd. as a flame retardant Charged aluminum oxide 30 parts, and thoroughly stirred to obtain an adhesive solution for the purpose.

(Comparative synthesis example of polyether polyurethane)
A reaction vessel equipped with a thermometer, a stirrer, and a distillation tube was charged with 100 parts of polypropylene glycol having a number average molecular weight of 1000 and 100 parts of toluene, and the resin was dissolved at 100 ° C. Thereafter, the temperature was raised to 130 ° C., 55 parts of toluene was distilled, and the reaction system was dehydrated by azeotropic distillation of toluene and water. Thereafter, the system was cooled to 60 ° C., 45 parts of methyl ethyl ketone and 3 parts of neopentyl glycol were added, and the mixture was stirred at 60 ° C. for 30 minutes. Thereafter, 32 parts of 4,4′-diphenylmethane diisocyanate was charged and stirred at 60 ° C. for 30 minutes. Subsequently, 0.2 part of dibutyltin dilaurate was added, the temperature was raised to 80 ° C. for reaction, and after completion of the reaction, 112.5 parts of methyl ethyl ketone was added to adjust the solid content concentration to 40% to obtain a polyether polyurethane. The characteristic values of the polyether polyurethane thus obtained were as follows.

Number average molecular weight: 12000
Glass transition temperature: -30 ° C
Acid value: 3 equivalent / t
(Comparative synthesis example of adhesive)
In a reaction vessel equipped with a thermometer, a stirrer, and a reflux condenser, 250 parts of the polyether polyurethane solution obtained in the synthesis example of polyether polyurethane, 73.5 parts of methyl ethyl ketone, and BREN-S (Nipponization) as an epoxy resin 20 parts of brominated phenol novolac type epoxy resin manufactured by Yakuhin Co., Ltd., 15 parts of YDB400 (brominated bisphenol A type epoxy resin manufactured by Toto Kasei Co., Ltd.), 3,3 ′, 4,4 as curing agent Charge 5 parts of '-benzophenonetetracarboxylic dianhydride and 3 parts of Ricacid TMTA-C (glycerol tris anhydrotrimellitate manufactured by Shin Nippon Rika Co., Ltd.), dissolve at 50 ° C, and then use 2PHZ as a curing catalyst. -CN (Shikoku Chemicals Co., Ltd. imidazole compound) 0.6 parts, C11Z-A (Shikoku Chemicals Co., Ltd. 2 0.4 part of 4-diamino-6- (2′-undecylimidazolyl) -ethyl-s-triazine) and 5 parts of antimony trioxide as a flame retardant aid were added and sufficiently stirred to obtain an adhesive solution. .

(Manufacture of copper-clad laminate)
a) Synthesis of base polyamideimide resin In the reaction vessel, 153.7 g (80 mol%) trimellitic anhydride, 38.7 g (12 mol%) 3,3 ', 4,4'-benzophenonetetracarboxylic anhydride, 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride (purity 99%) 23.5 g (8 mol%), 3,3′-dimethyl-4,4′-biphenyl diisocyanate 264.3 g (100 Mol%), 1.5 g of 1,8-diazabicyclo- [5.4.0] -undecene-7 and 2230 g of N-methyl-2-pyrrolidone (purity 99.9%) are added to a temperature of 100 ° C. under a nitrogen stream. The temperature was raised and reacted at 100 ° C. for 2 hours. Next, after reacting at 150 ° C. for 1 hour, 1307 g of N-methyl-2-pyrrolidone (polymer concentration 10% by weight) was added, and the mixture was cooled to room temperature.

b) Production of copper-clad laminate The polyamideimide resin solution obtained above was removed using a knife coater on an electrolytic copper foil (trade name “USLP-R2”, manufactured by Nippon Electrolytic Co., Ltd.) having a thickness of 18 μm. Coating was performed so that the subsequent thickness was 25 μm. Subsequently, it dried for 3 minutes at the temperature of 120 degreeC, and the flexible metal-clad laminate which was initially dried was obtained.

Next, the above initially dried laminate was wound on an aluminum can with an outer diameter of 16 inches so that the coated surface was on the outside, and 200 ° C. × 24 hrs in a vacuum dryer (the degree of vacuum was 10 to 100 Pa depending on the volatilization of the solvent. The mixture was dried and further heated in an inert oven under nitrogen (flow rate: 20 L / min); 280 ° C. × 3 hr. (The solvent in the coating was completely removed.)
(Manufacture of insulation film)
a) Synthesis of Polyimide Resin for Insulating Film In a container equipped with a stirrer, a reflux condenser, and a nitrogen introduction can, 170 g (0.85 mol) of 4,4′-diaminodiphenyl ether and 16 g of p-phenylenediamine (0 .15) The mole was dissolved in 1600 g of N, N-dimethylacetamide, cooled to around 5 ° C. and stirred until it was completely dissolved. Next, 218 g (0.1 mol) of pyromellitic dianhydride was gradually added and stirred for about 10 hours under a nitrogen atmosphere. Then, it stirred until it became room temperature, and the solution of the polyamic acid was obtained.

b) Manufacture of polyimide resin film Add 30 g of acetic anhydride and triethylamine to the above polyamic acid solution, apply it on a glass plate with an applicator, dry at 100 ° C for 10 minutes, peel off the coating, and support the coating It fixed to the frame and heated at 200 degreeC for 3 minutes, 300 degreeC for 1 minute, and 450 degreeC for 1 minute, and obtained the 25-micrometer-thick insulating film.

c) Production of insulating film The adhesives of the above synthesis examples and comparative synthesis examples were coated on the polyimide resin film with a comma coater so that the thickness after drying was 25 μm, and 3 minutes at 80 ° C. and 3 minutes at 150 ° C. Partial drying was performed to obtain an insulating film.

(Example 1)
A photosensitive resist was laminated on the copper foil surface of the flexible metal-clad laminate, exposed and baked with a mask film, developed, and a necessary pattern (evaluation pattern described in JIS C 5016) was transferred. Next, the copper foil was etched away using a 35% cupric chloride solution at 40 ° C., and the resist used for circuit formation was removed with an alkali to perform circuit processing.

Next, the insulating film obtained by punching and punching a part necessary for electrical connection in advance with a mold is overlaid so that the adhesive layer is in contact with the circuit surface, and press lamination (160 ° C. × 4 minutes, The pressure was 20 kgf / cm ² (196.133 N / cm ² )) and after-curing (100 ° C. × 16 hr) to obtain a flexible printed wiring board.

(Comparative Example 1)
A flexible printed wiring board was obtained by the same method as in Example 1. However, what used the adhesive agent obtained by the comparative synthesis example as an insulating film was used.

  Evaluation of the flexible printed wiring board was performed as follows.

a) Evaluation of bending resistance Measured according to JIS-C-5016 at a bending diameter of 0.38 mm and 1.0 mm.

b) Evaluation results The evaluation results are shown in the following table.

以上のように、本発明の好ましい実施形態を用いて本発明を例示してきたが、本発明は、この実施形態に限定して解釈されるべきものではない。本発明は、特許請求の範囲によってのみその範囲が解釈されるべきであることが理解される。当業者は、本発明の具体的な好ましい実施形態の記載から、本発明の記載および技術常識に基づいて等価な範囲を実施することができることが理解される。本明細書において引用した特許、特許出願および文献は、その内容自体が具体的に本明細書に記載されているのと同様にその内容が本明細書に対する参考として援用されるべきであることが理解される。

As mentioned above, although this invention has been illustrated using preferable embodiment of this invention, this invention should not be limited and limited to this embodiment. It is understood that the scope of the present invention should be construed only by the claims. It is understood that those skilled in the art can implement an equivalent range based on the description of the present invention and the common general technical knowledge from the description of specific preferred embodiments of the present invention. Patents, patent applications, and documents cited herein should be incorporated by reference in their entirety, as if the contents themselves were specifically described herein. Understood.

  As described above, according to the present invention, an FPC excellent in various performances is provided. Therefore, the present invention is extremely useful in industries related to products that require FPC.

Claims (9)

A flexible printed wiring board including a base film layer, a conductor layer, an adhesive layer, a cover film layer,
A flexible printed wiring board, wherein the adhesive contains a polyester polyurethane resin crosslinked with an epoxy resin, and the number average molecular weight of the polyester polyurethane resin is 8000 to 100,000.   The flexible printed wiring board according to claim 1, comprising a pattern having a circuit pitch of 150 μm or less and a circuit line width of 100 μm or less.   The flexible printed wiring board according to claim 1, wherein the cover film layer is a polyimide resin film or a polyamideimide resin film.   The flexible printed wiring board in any one of Claims 1-3 whose said cover film layer is a polyimide resin.   The flexible printed wiring board of Claim 4 whose 5-70 mol% is p-phenylenediamine among the diamine components of the said polyimide resin.   The flexible printed wiring board in any one of Claims 1-5 whose said base film layer is a polyimide resin film or a polyamide-imide resin film.   The flexible printed wiring board according to claim 6, wherein the base film layer is a polyamideimide resin film. It is a flexible printed wiring board of Claim 7, Comprising: 70-90 mol% trimellitic anhydride, 5-25 mol% 3,3 'in 100 mol% of acid components of the said polyamideimide resin , 4,4′-benzophenone tetracarboxylic dianhydride, and 5-25 mol% 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride,
A flexible printed wiring board comprising 3,3′-dimethyl-4,4′-biphenyldiamine as a diamine component of the polyamideimide resin.   The flexible printed wiring board according to claim 1, wherein the conductor layer is directly laminated on the base film layer without using an adhesive.