JP2015133480A - Adhesive film for coverlay, coverlay, wiring board and method of manufacturing electronic apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an adhesive film for coverlay exhibiting excellent peel strength retention rate between a substrate and wiring and a protective film even if exposed to high temperature environment repeatedly, while reducing discoloration of the protective film, and to provide a coverlay, a wiring board, and a method of manufacturing an electronic apparatus.SOLUTION: An adhesive film for coverlay is capable of molten molding, and contains a fluorine-containing copolymer (A) having at least one kind of functional group selected from a group consisting of a carbonyl radical-containing group, a hydroxy group, an epoxy group and an isocyanate group.

Description

  The present invention relates to a coverlay adhesive film, a coverlay, a wiring board, and a method for manufacturing an electronic device.

In recent years, a flexible printed wiring board (hereinafter referred to as “FPC”) is used for power supply or electric signal transmission in an in-vehicle electronic device of an automobile, instead of a wire harness composed of a bundle of electric wires conventionally used. (Patent Document 1). Since the FPC is lighter and thinner than a wire harness and can be wired along a structural material, it is possible to reduce the weight and modularity of automobile parts and save space inside the automobile.
In a wiring board such as an FPC, a wiring made of copper or the like formed on a substrate mainly composed of polyimide or the like is covered and protected by a protective film made of various raw materials. The protective film is usually attached to a substrate on which wiring is formed with an adhesive so as to cover the wiring.

However, FPCs used in in-vehicle electronic devices are repeatedly exposed to a high temperature environment of about 150 ° C., so that the adhesive is likely to deteriorate due to long-term use. When the adhesive is deteriorated, the adhesive strength is reduced and the protective film is peeled off from the substrate, so that the wiring protection function by the protective film is lowered.
In addition, devices other than in-vehicle electronic devices, such as notebook personal computers and supercomputers having a CPU capable of performing high-speed processing, are increasingly used for further miniaturization and weight reduction. Since the FPC is repeatedly exposed to a high temperature environment due to the heat generated by the CPU, the wiring protection function by the protective film is reduced as in the case of the in-vehicle electronic device.

Up to now, the adhesive has been improved in order to cope with the decrease in the wiring protection function by the protective film resulting from the deterioration of the adhesive in the FPC.
For example, Patent Document 2 discloses a polyimide resin in which a crosslinked structure is formed by reacting an amino compound having at least two primary amino groups as functional groups with polyimidesiloxane having a predetermined chemical structure, It is disclosed that it is possible to form an adhesive layer that does not reduce the adhesive strength of the adhesive.

JP 2006-5134 A International Publication No. 2011/077917

However, in the long-term heat resistance test at 150 ° C. and 1000 hours in the atmosphere, the peel strength retention rate between the substrate and the wiring and the protective film bonded by the adhesive layer made of the polyimide resin described in Patent Document 2 is It ’s not enough. Further, when repeatedly used in a high temperature environment, the adhesive layer tends to cause discoloration of the protective film.
Therefore, the present invention provides a coverlay adhesive film, a coverlay, and a wiring that are excellent in the peel strength retention ratio between the substrate and the wiring and the protective film and are less subject to discoloration even when repeatedly exposed to a high temperature environment. It is an object of the present invention to provide a method for manufacturing a board and an electronic device.

The present invention is a method for manufacturing a coverlay adhesive film, a coverlay, a wiring board, and an electronic device having the following configurations [1] to [11].
[1] A fluorine-containing copolymer (A) that can be melt-molded and has at least one functional group selected from the group consisting of a carbonyl group-containing group, a hydroxy group, an epoxy group, and an isocyanate group, Adhesive film for coverlay.
[2] The fluorine-containing copolymer (A) is selected from the group consisting of a hydrocarbon group containing a carbonyl group between carbon atoms, a carbonate group, a carboxyl group, a haloformyl group, an alkoxycarbonyl group, and an acid anhydride residue. The coverlay adhesive film according to [1], which has at least one functional group.
[3] The content of the functional group according to [1] or [2], wherein the content of the functional group is 10 to 60000 with respect to 1 × 10 ⁶ main chain carbon atoms of the fluorine-containing copolymer (A). Adhesive film for coverlay.
[4] The coverlay adhesive film according to any one of [1] to [3], wherein the fluorine-containing copolymer (A) has a melting point of 260 to 320 ° C.
[5] A coverlay obtained by laminating the coverlay adhesive film according to any one of [1] to [4] on a protective film.
[6] A coverlay adhesive film and a protective film according to any one of [1] to [4], comprising the substrate, the wiring, and the wiring, the coverlay adhesive film, and the protective film on the substrate. Is a wiring board that is laminated in this order.
[7] When the wiring board is treated in the atmosphere at a temperature of 150 ° C. for 1000 hours, the color difference ΔE (transmission) of the wiring board before and after treatment (where no wiring is present) in accordance with JIS Z8730 is 2 The wiring board according to [6], which is 0.0 or less.
[8] When the wiring board is treated in the atmosphere at a temperature of 150 ° C. for 1000 hours, the color difference ΔE (reflection) of the adhesive film for coverlay of the wiring board before and after the treatment according to JIS Z8730 is 5.0. The wiring board according to [6] or [7], wherein:
[9] The wiring board according to any one of [6] to [8], which is for in-vehicle electronic equipment for in-vehicle powertrain.
[10] The wiring board according to [9], wherein the in-vehicle power train is a headlamp board, a transmission, or an engine.
[11] A method for manufacturing an electronic device comprising the wiring board according to any one of [6] to [10], comprising a step of exposing the wiring board to a high temperature environment of 260 ° C. or higher. , Manufacturing method of electronic equipment.

  According to the present invention, even when repeatedly exposed to a high temperature environment, the adhesive film for coverlay, the coverlay, and the wiring having excellent peel strength retention between the substrate and the wiring and the protective film and less discoloration of the protective film A plate and an electronic device manufacturing method can be provided.

In the present specification, the “structural unit” means a structural unit based on the monomer formed by polymerization of the monomer. The structural unit may be a unit directly formed by a polymerization reaction, or may be a unit in which a part of the unit is converted into another structure by treating the polymer.
The term “monomer” means a compound having a polymerizable unsaturated bond, that is, a polymerization-reactive carbon-carbon double bond. The “fluorine monomer” means a monomer having a fluorine atom in the molecule, and the “non-fluorine-containing monomer” means a monomer having no fluorine atom in the molecule.

<Adhesive film for coverlay>
The coverlay adhesive film of the present invention can be melt-molded and has a fluorine-containing copolymer having at least one functional group selected from the group consisting of a carbonyl group-containing group, a hydroxy group, an epoxy group, and an isocyanate group. Includes coalescence (A).

[Fluorine-containing copolymer (A)]
The fluorine-containing copolymer (A) can be melt-molded. The fluorine-containing copolymer (A) is at least one functional group selected from the group consisting of a carbonyl group-containing group, a hydroxy group, an epoxy group, and an isocyanate group (hereinafter referred to as “functional group (I)”). .)

(Moldable)
The fluorine-containing copolymer (A) can be melt-molded. “Melting is possible” means exhibiting melt fluidity.
In the fluorinated copolymer (A), the melt flow rate (Melt Flow Rate: hereinafter) at a temperature 20 ° C. or higher (usually 372 ° C. is adopted) higher than the melting point of the fluorinated copolymer (A). "MFR") is preferably 0.1 to 1000 g / 10 minutes, more preferably 0.5 to 100 g / 10 minutes, further preferably 1 to 30 g / 10 minutes, and most preferably 5 to 20 g / 10 minutes. .
If the MFR is equal to or greater than the lower limit, the processability of the fluorinated copolymer (A) and the coverlay adhesive film formed using the fluorinated copolymer (A) have surface smoothness. If it is excellent in appearance and not more than the above upper limit value, the coverlay adhesive film containing the fluorine-containing copolymer (A) is excellent in mechanical strength.
The value of MFR also serves as an index of the molecular weight of the fluorinated copolymer (A). When the MFR is fast, the molecular weight is small, and when the MFR is slow, the molecular weight is large. The MFR and molecular weight of the fluorinated copolymer (A) can be adjusted according to the production conditions of the fluorinated copolymer (A). For example, if the polymerization time is shortened during the polymerization of the monomer, the MFR tends to increase.

(Functional group (I))
The fluorine-containing copolymer (A) has a functional group (I).
By having the functional group (I), the adhesion between the coverlay adhesive film and the protective film is improved. This is presumed to be due to the chemical interaction between the functional group (I) and the functional group of the polyimide, such as a carbonyl group.
The functional group (I) possessed by the fluorinated copolymer (A) may be one type or two or more types.
Among the functional groups (I), the fluorine-containing copolymer (A) preferably has a carbonyl group-containing group.

Moreover, the fluorine-containing copolymer (A) may have the functional group (I) at the main chain terminal, may be included in the side chain, or may be included in both of them.
As the functional group (I) as the main chain terminal group, an alkoxycarbonyl group, a carbonate group, a hydroxy group, a carboxyl group, a fluoroformyl group, an acid anhydride residue and the like are preferable. These functional groups can be introduced by appropriately selecting a radical polymerization initiator, a chain transfer agent and the like used in the production of the fluorine-containing copolymer (A).
In the present specification, the main chain is a main carbon chain of the chain compound, and generally indicates a portion corresponding to a trunk having the maximum number of carbon atoms.

The content of the functional group (I) in the fluorinated copolymer (A) is preferably 10 to 60000 with respect to 1 × 10 ⁶ main chain carbon atoms of the fluorinated copolymer (A), and preferably 100 to 50000. Are more preferable, 100-10000 are further more preferable, and 300-5000 are especially preferable.
If the content of the functional group (I) is not less than the above lower limit value, the adhesion between the coverlay adhesive film and the protective film will be more excellent, and if it is not more than the above upper limit value, at a low processing temperature. Adhesion with the protective film can be further enhanced.
The content of the functional group (I) can be measured by methods such as nuclear magnetic resonance (NMR) analysis and infrared absorption spectrum analysis. For example, a structure having a functional group (I) in all the structural units constituting the fluorine-containing copolymer (A) using a method such as infrared absorption spectrum analysis as described in JP-A-2007-314720 The unit ratio (mol%) is obtained, and the content of the functional group (I) can be calculated from the ratio.

Hereinafter, among the functional groups (I), the carbonyl group-containing group will be described in detail.
The carbonyl group-containing group is a group containing a carbonyl group (—C (═O) —) in the structure. For example, a hydrocarbon group containing a carbonyl group between carbon atoms, a carbonate group, a carboxyl group, a haloformyl group, an alkoxy group. A carbonyl group, an acid anhydride residue, etc. are mentioned.
Examples of the hydrocarbon group of the hydrocarbon group containing a carbonyl group between carbon atoms include alkylene groups having 2 to 8 carbon atoms.
Examples of the carbonate group include a peroxycarbonate group (—O—C (═O) —O—O—C (═O) —O—) and the like.
The haloformyl group is represented by —C (═O) —X ⁰ (X ⁰ is a halogen atom). Examples of the halogen atom in the haloformyl group include a fluorine atom and a chlorine atom, and a fluorine atom is preferable. That is, the haloformyl group is preferably a fluoroformyl group (also referred to as a carbonyl fluoride group).
The alkoxy group in the alkoxycarbonyl group is preferably an alkoxy group having 1 to 8 carbon atoms, and particularly preferably a methoxy group or an ethoxy group.
Examples of the acid anhydride residue include a group formed by a monomer having an acid anhydride residue and a polymerizable unsaturated bond (hereinafter referred to as “AM monomer”), and specifically, itaconic anhydride. (Hereinafter referred to as “IAH”), citraconic anhydride (hereinafter referred to as “CAH”), 5-norbornene-2,3-dicarboxylic anhydride (hereinafter referred to as “NAH”), and maleic anhydride. And the like. Among these, a group formed by one or more selected from the group consisting of IAH, CAH and NAH is preferable, and a group formed by IAH or CAH is more preferable.

Specific examples of the fluorine-containing copolymer having a carbonyl group-containing group include a structural unit (a1) based on tetrafluoroethylene (hereinafter referred to as “TFE”), an acid anhydride residue, and a polymerizable unsaturated bond. A copolymer containing a structural unit (a2) based on a cyclic hydrocarbon monomer having a structural unit (a3) based on a fluorine-containing monomer (excluding TFE) (hereinafter referred to as “fluorinated copolymer ( A1) ")).
Here, the acid anhydride residue of the structural unit (a2) corresponds to the functional group (I).
Hereinafter, each structural unit of a fluorine-containing copolymer (A1) is explained in full detail.

(Fluorine-containing copolymer (A1))
Structural unit (a1):
The structural unit (a1) is a structural unit based on TFE.

Structural unit (a2):
Examples of the cyclic hydrocarbon monomer having an acid anhydride residue forming the structural unit (a2) and a polymerizable unsaturated bond include IAH, CAH, NAH, maleic anhydride and the like. These may be used alone or in combination of two or more.
Among the above, at least one selected from the group consisting of IAH, CAH, and NAH is preferable. When at least one selected from the group consisting of IAH, CAH, and NAH is used, the acid can be used without using a special polymerization method (see JP-A-11-19312) required when maleic anhydride is used. The fluorine-containing copolymer (A) containing an anhydride residue can be easily produced.
Among IAH, CAH, and NAH, NAH is preferable because it is more excellent in adhesion to the protective film.

Structural unit (a3):
The fluorine-containing monomer that forms the structural unit (a3) is preferably a fluorine-containing compound having one polymerizable double bond, and examples thereof include vinyl fluoride, vinylidene fluoride (hereinafter referred to as “VdF”), and trifluoro. Fluoroolefins (excluding TFE) such as ethylene, chlorotrifluoroethylene (hereinafter referred to as “CTFE”), hexafluoropropylene (hereinafter referred to as “HFP”), CF ₂ = CFOR ^f1 (where RFE ^f1 is a perfluoroalkyl group having 1 to 10 carbon atoms and may contain an oxygen atom between carbon atoms.), CF ₂ = CFOR ^f2 SO ₂ X ¹ (wherein R ^f2 is an oxygen atom having 1 to 10 carbon atoms and an oxygen atom between carbon atoms) contain atoms which may perfluoroalkylene group, ^{X 1} is a halogen atom or a hydroxyl ^{_{group.), CF 2 = CFOR f3}} CO X ² (provided ^{that, R f3} is also good perfluoroalkylene group contain an oxygen atom between carbon atoms at 1 to 10 carbon atoms, ^{X 2} is a hydrogen atom or an alkyl group having 3 or less carbon _{atoms.), CF 2 = CF (} CF ₂ ) _p OCF = CF ₂ (where p is 1 or 2), CH ₂ = CX ³ (CF ₂ ) _q X ⁴ (where X ³ is a hydrogen atom or a fluorine atom, q is an integer of 2 to 10, X ⁴ is a hydrogen atom or a fluorine atom.) And perfluoro (2-methylene-4-methyl-1,3-dioxolane).
Among these fluorine-containing monomers, at least one selected from the group consisting of VdF, CTFE, HFP, CF ₂ = CFOR ^f1 , and CH ₂ = CX ³ (CF ₂ ) _q X ⁴ is preferable, CF ₂ = CFOR ^f1 , HFP is more preferred.
As CF ₂ = CFOR ^f1 , CF ₂ = CFOCF ₂ CF ₃ , CF ₂ = CFOCF ₂ CF ₂ CF ₃ , CF ₂ = CFOCF ₂ CF ₂ CF ₂ CF ₃ , CF ₂ = CFO (CF ₂ ) ₈ F, etc. CF ₂ = CFOCF ₂ CF ₂ CF ₃ (hereinafter referred to as “PPVE”) is preferable.
As CH ₂ = CX ³ (CF ₂ ) _q X ⁴ , CH ₂ = CH (CF ₂ ) ₂ F, CH ₂ = CH (CF ₂ ) ₃ F, CH ₂ = CH (CF ₂ ) ₄ F, CH ₂ ═CF (CF ₂ ) ₃ H, CH ₂ ═CF (CF ₂ ) ₄ H and the like, and CH ₂ ═CH (CF ₂ ) ₄ F or CH ₂ ═CH (CF ₂ ) ₂ F are preferable.

Content of each structural unit:
In the fluorine-containing copolymer (A), the structural unit (a1) is 50 to 99.89 mol% with respect to the total molar amount of the structural unit (a1), the structural unit (a2), and the structural unit (a3). The structural unit (a2) is preferably 0.01 to 5 mol%, the structural unit (a3) is preferably 0.1 to 49.99 mol%, and the structural unit (a1) is 50 to 99.4 mol%. It is more preferable that the structural unit (a2) is 0.1 to 3 mol%, the structural unit (a3) is 0.5 to 49.9 mol%, and the structural unit (a1) is 50 to 98.9. It is particularly preferable that the structural unit (a2) is 0.1 to 2 mol% and the structural unit (a3) is 1 to 49.9 mol%.
When the content of each structural unit is within the above range, the fluorinated copolymer (A) is excellent in heat resistance and chemical resistance, and the adhesive film for coverlay including this is excellent in elastic modulus at high temperature.
In particular, when the content of the structural unit (a2) is within the above range, the amount of the acid anhydride residue of the fluorine-containing copolymer (A) becomes an appropriate amount, and the adhesion to the protective film is improved. Excellent.
When the content of the structural unit (a3) is within the above range, the fluorinated copolymer (A) is excellent in moldability, and the coverlay adhesive film containing this is excellent in mechanical properties such as stress crack resistance.

The content of each structural unit can be calculated by melting NMR analysis, fluorine content analysis, infrared absorption spectrum analysis, and the like of the fluorine-containing copolymer (A).
When the fluorine-containing copolymer (A) is composed of the structural unit (a1), the structural unit (a2), and the structural unit (a3), the content of the structural unit (a2) is the same as that of the structural unit (a1) and the structural unit. 0.01 mol% with respect to the total molar amount of the unit (a2) and the structural unit (a3) means the structural unit (a1), the structural unit (a2) and the structural unit in the fluorine-containing copolymer (A). The content of the acid anhydride residue in the unit (a3) portion is the number of main chain carbon atoms of the structural unit (a1), the structural unit (a2) and the structural unit (a3) in the fluorine-containing copolymer (A) 1 × This is equivalent to 100 for 10 ⁶ . The content of the structural unit (a2) is 5 mol% with respect to the total molar amount of the structural unit (a1), the structural unit (a2), and the structural unit (a3). This corresponds to the content of the acid anhydride residue in A) being 50,000 with respect to 1 × 10 ⁶ main chain carbon atoms of the fluorine-containing copolymer (A).
In the fluorine-containing copolymer (A) having the structural unit (a2), a cyclic hydrocarbon monomer having an acid anhydride residue and a polymerizable unsaturated bond is partially hydrolyzed, resulting in an acid anhydride residue. A structural unit based on a dicarboxylic acid corresponding to a group (itaconic acid, citraconic acid, 5-norbornene-2,3-dicarboxylic acid, maleic acid, etc.) may be included. When the structural unit based on this dicarboxylic acid is contained, content of this structural unit shall be contained in a structural unit (a2).

Structural unit (a4):
The fluorinated copolymer (A1) is a non-fluorinated monomer (however, a cyclic hydrocarbon monomer having an acid anhydride residue and a polymerizable unsaturated bond) in addition to the structural units (a1) to (a3). The structural unit (a4) based on the above may be included.
As the non-fluorine-containing monomer forming the structural unit (a4) (excluding a cyclic hydrocarbon monomer having an acid anhydride residue and a polymerizable unsaturated bond), a non-fluorinated monomer having one polymerizable double bond is used. Fluorine-containing compounds are preferred, and examples thereof include olefins having 3 or less carbon atoms such as ethylene and propylene, and vinyl esters such as vinyl acetate.
These may be used alone or in combination of two or more.
Among these, ethylene, propylene, and vinyl acetate are preferable, and ethylene is particularly preferable.

  When the fluorine-containing copolymer (A) has the structural unit (a4), the content of the structural unit (a4) is based on the total amount of the structural unit (a1), the structural unit (a2), and the structural unit (a3). 5 to 90 mol% is preferable, 5 to 80 mol% is more preferable, and 10 to 65 mol% is most preferable.

Specific examples of the fluorine-containing copolymer (A1):
Examples of the fluorine-containing copolymer (A1) include TFE / PPVE / NAH copolymer, TFE / PPVE / IAH copolymer, TFE / PPVE / CAH copolymer, TFE / HFP / IAH copolymer, TFE / HFP. / CAH copolymer, TFE / VdF / IAH copolymer, TFE / VdF / CAH copolymer, TFE / CH ₂ ═CH (CF ₂ ) ₄ F / IAH / ethylene copolymer, TFE / CH ₂ ═CH (CF ₂ ) ₄ F / CAH / ethylene copolymer, TFE / CH ₂ ═CH (CF ₂ ) ₂ F / IAH / ethylene copolymer, TFE / CH ₂ ═CH (CF ₂ ) ₂ F / CAH / ethylene A copolymer etc. are mentioned.

(Melting point of fluorine-containing copolymer (A))
The melting point of the fluorinated copolymer (A) is preferably 260 to 320 ° C, more preferably 280 to 320 ° C, further preferably 290 to 315 ° C, and most preferably 295 to 310 ° C. If the melting point of the fluorinated copolymer (A) is not less than the lower limit, the heat resistance is excellent, and if it is not more than the upper limit, the moldability is excellent.
Melting | fusing point of a fluorine-containing copolymer (A) can be adjusted with the kind of the structural unit which comprises the said fluorine-containing copolymer (A), a content rate, molecular weight, etc. For example, the melting point tends to increase as the proportion of the structural unit (a1) described later increases.

[Method for producing coverlay adhesive film]
The coverlay adhesive film can be produced by a conventional method. For example, a fluorine-containing copolymer (A) and, if necessary, an additive are blended and kneaded to obtain a fluorine-containing resin composition, which is produced by molding into a film by a known molding method such as extrusion molding or inflation molding. it can.
Moreover, the surface of the adhesive film for coverlay, for example, the surface in contact with the protective film, may be subjected to a surface treatment in order to improve the adhesion to the protective film. The surface treatment method is not particularly limited, and examples thereof include known surface treatment methods such as corona discharge treatment and plasma treatment.
Moreover, the thickness of the adhesive film for coverlays is not specifically limited, For example, 5-100 micrometers is preferable.

(Fluorine-containing copolymer (A))
The fluorine-containing copolymer (A) can be produced by a conventional method.
As a manufacturing method of the fluorine-containing copolymer (A) which has a functional group (I), for example, when manufacturing a fluorine-containing copolymer (A) by (1) polymerization reaction, it has a functional group (I). A method using a monomer (hereinafter referred to as “method (1)”), (2) a fluorine-containing copolymer (A) by a polymerization reaction using a radical polymerization initiator or a chain transfer agent having a functional group (I). ) (Hereinafter referred to as “method (2)”), (3) the fluorine-containing copolymer having no functional group (I) is heated to partially heat the fluorine-containing copolymer. A method of obtaining a fluorine-containing copolymer (A) having a functional group (I) by generating a reactive functional group (for example, a carbonyl group) by decomposing, and (4) containing no functional group (I). The fluorine-containing copolymer is graft-polymerized with a monomer having a functional group (I) to form the fluorine-containing copolymer. A method in which introducing a functional group (I).
Among these, the method (1) is preferable from the viewpoint of improving the adhesive strength.

  As polymerization methods, bulk polymerization methods, solution polymerization methods using organic solvents such as fluorinated hydrocarbons, chlorinated hydrocarbons, fluorinated chlorohydrocarbons, alcohols, hydrocarbons, aqueous media and appropriate organic solvents as required And suspension polymerization method using an aqueous medium, and emulsion polymerization method using an aqueous medium and an emulsifier. Among these, the solution polymerization method is preferable.

Radical polymerization initiator:
As the radical polymerization initiator, an initiator whose half-life is 10 hours is preferably 0 to 100 ° C, and more preferably an initiator whose temperature is 20 to 90 ° C.
Specific examples include azo compounds such as azobisisobutyronitrile, non-fluorine diacyl peroxides such as isobutyryl peroxide, octanoyl peroxide, benzoyl peroxide and lauroyl peroxide, peroxydicarbonates such as diisopropylperoxydicarbonate, tert - butyl peroxypivalate, tert- butylperoxy isobutyrate, tert- butyl peroxy ester peroxy acetate, _{etc., 2} (where _{(Z (CF 2) r COO} ), Z represents a hydrogen atom, a fluorine atom or a chlorine atom , R is an integer of 1 to 10.) Fluorine-containing diacyl peroxide such as a compound represented by formula (I), inorganic peroxides such as potassium persulfate, sodium persulfate, and ammonium persulfate.

Chain transfer agent:
In the polymerization, it is also preferable to use a chain transfer agent in order to control the melt viscosity of the fluorinated copolymer (A).
Chain transfer agents include alcohols such as methanol and ethanol, chlorofluorohydrocarbons such as 1,3-dichloro-1,1,2,2,3-pentafluoropropane, 1,1-dichloro-1-fluoroethane, Examples thereof include hydrocarbons such as pentane, hexane, and cyclohexane.

One or both of the radical polymerization initiator and the chain transfer agent may be a compound having a functional group (I). Thereby, functional group (I) can be introduce | transduced into the principal chain terminal of the fluorine-containing copolymer (A) manufactured (the above-mentioned method (2)).
Examples of such radical polymerization initiators include di-n-propyl peroxydicarbonate, diisopropyl peroxycarbonate, t-butyl peroxyisopropyl carbonate, bis (4-t-butylcyclohexyl) peroxydicarbonate, di-2-ethylhexyl peroxydi. And carbonate. Examples of such chain transfer agents include acetic acid, acetic anhydride, methyl acetate, ethylene glycol, propylene glycol and the like.

Organic solvent:
As the organic solvent used in the solution polymerization method, perfluorocarbon, hydrofluorocarbon, chlorohydrofluorocarbon, hydrofluoroether, or the like is used. These compounds preferably have 4 to 12 carbon atoms.
Specific examples of the perfluorocarbon include perfluorocyclobutane, perfluoropentane, perfluorohexane, perfluorocyclopentane, and perfluorocyclohexane.
Specific examples of the hydrofluorocarbon include 1-hydroperfluorohexane and the like.
Specific examples of the chlorohydrofluorocarbon include 1,3-dichloro-1,1,2,2,3-pentafluoropropane.
Specific examples of the hydrofluoroether include methyl perfluorobutyl ether and 2,2,2-trifluoroethyl 2,2,1,1-tetrafluoroethyl ether.

Polymerization conditions:
The polymerization conditions are not particularly limited, and the polymerization temperature is preferably 0 to 100 ° C, more preferably 20 to 90 ° C. The polymerization pressure is preferably from 0.1 to 10 MPa, more preferably from 0.5 to 3 MPa. The polymerization time is preferably 1 to 30 hours.
When the fluorine-containing copolymer (A1) having the structural unit (a2) is polymerized, the concentration of the cyclic hydrocarbon monomer having an acid anhydride residue and a polymerizable unsaturated bond during the polymerization is the same as that for all monomers. On the other hand, 0.01-5 mol% is preferable, 0.1-3 mol% is more preferable, and 0.1-2 mol% is the most preferable. If the concentration during polymerization of the cyclic hydrocarbon monomer having an acid anhydride residue and a polymerizable unsaturated bond is not less than the lower limit, the content of the structural unit (a2) in the fluorinated copolymer (A1) Can be sufficiently increased, and adhesion to the substrate, wiring and protective film can be enhanced. On the other hand, if it is below the said upper limit, superposition | polymerization will be easy to be maintained at a suitable speed | rate.
As the cyclic hydrocarbon monomer having an acid anhydride residue and a polymerizable unsaturated bond is consumed during the polymerization, the consumed amount is continuously or intermittently supplied into the polymerization tank, and the monomer is supplied. It is preferable to maintain the concentration within the above range.

(Additive)
The coverlay adhesive film may contain an additive as long as the effects of the present invention are not impaired.
As an additive, an inorganic filler having a low dielectric constant and dielectric loss tangent is preferable. Examples of the inorganic filler include silica, clay, talc, calcium carbonate, mica, diatomaceous earth, alumina, zinc oxide, titanium oxide, calcium oxide, magnesium oxide, iron oxide, tin oxide, antimony oxide, calcium hydroxide, magnesium hydroxide, Aluminum hydroxide, basic magnesium carbonate, magnesium carbonate, zinc carbonate, barium carbonate, dosonite, hydrotalcite, calcium sulfate, barium sulfate, calcium silicate, montmorillonite, bentonite, activated clay, sepiolite, imogolite, sericite, glass fiber, Examples thereof include glass beads, silica-based balloons, carbon black, carbon nanotubes, carbon nanohorns, graphite, carbon fibers, glass balloons, carbon burns, wood powder, zinc borate and the like.
An inorganic filler may be used individually by 1 type, and may use 2 or more types together.

The inorganic filler may be porous or non-porous. A porous material is preferable in that the dielectric constant and dielectric loss tangent are lower.
The inorganic filler may be subjected to a surface treatment with a surface treatment agent such as a silane coupling agent or a titanate coupling agent in order to improve dispersibility in the fluorine-containing copolymer (A).
When the inorganic filler is contained, the content of the inorganic filler in the coverlay adhesive film is preferably 0.1 to 100% by mass, and 0.1 to 60% by mass with respect to the fluorinated copolymer (A). More preferred.

<Coverlay>
The coverlay is formed by laminating the above-mentioned adhesive film for coverlay on a protective film.
Moreover, in order for the coverlay to protect the surface of the coverlay adhesive film side, a separator may be laminated on the coverlay adhesive film side. Examples of the separator include paper and PET film. If a separator is used, a coverlay can be made into a roll shape and it will become easy to convey.

[Protective film]
The material of the protective film is preferably one having insulating properties and flexibility. Examples of such a protective film include a polyimide film, a polyetherimide film, a polyamideimide film, and a polyester film. Among these, a polyimide film is preferable from the viewpoint of heat resistance.
Hereinafter, the polyimide film will be described in detail.

(Polyimide film)
Polyimide:
The polyimide which comprises a polyimide-type film is not specifically limited, The polyimide which does not have thermoplasticity, or a thermoplastic polyimide may be sufficient.
A preferred example of polyimide is aromatic polyimide. Among these, wholly aromatic polyimides produced by condensation polymerization of aromatic polycarboxylic dianhydrides and aromatic diamines are preferred.

A polyimide is generally obtained via a polyamic acid (polyimide precursor) by a reaction (polycondensation) between a polyvalent carboxylic dianhydride (or a derivative thereof) and a diamine.
Polyimide, particularly aromatic polyimide, is insoluble and insoluble in solvents due to its rigid main chain structure. Therefore, first, a polyimide precursor (polyamic acid or polyamic acid) that is soluble in an organic solvent is synthesized by a reaction between a polycarboxylic dianhydride and a diamine, and then molded by various methods at the polyamic acid stage. Processing is performed. Thereafter, the polyamic acid is dehydrated by heating or a chemical method to cyclize (imidize) to obtain polyimide.

Aromatic polycarboxylic dianhydrides:
Specific examples of the aromatic polyvalent carboxylic dianhydride include, for example, pyromellitic dianhydride, 3,3 ′, 4,4′-benzophenone tetracarboxylic dianhydride, 2,2 ′, 3,3 '-Benzophenonetetracarboxylic dianhydride, 3,3', 4,4'-biphenyltetracarboxylic dianhydride, 2,2 ', 3,3'-biphenyltetracarboxylic dianhydride, 2,2- Bis (2,3-dicarboxyphenyl) propane dianhydride, bis (3,4-dicarboxyphenyl) ether dianhydride, bis (3,4-dicarboxyphenyl) sulfone dianhydride, 1,1-bis (2,3-dicarboxyphenyl) ethane dianhydride, bis (2,3-dicarboxyphenyl) methane dianhydride, bis (3,4-dicarboxyphenyl) methane dianhydride, 2,2-bis ( 3,4-dicarboki Ruphenyl) -1,1,1,3,3,3-hexafluoropropane dianhydride, 2,3,6,7-naphthalenetetracarboxylic dianhydride, 1,4,5,8-naphthalenetetracarboxylic acid Dianhydride, 1,2,5,6-naphthalenetetracarboxylic dianhydride, 1,2,3,4-benzenetetracarboxylic dianhydride, 3,4,9,10-perylenetetracarboxylic dianhydride Products, 2,3,6,7-anthracenetetracarboxylic dianhydride, 1,2,7,8-phenanthrenetetracarboxylic dianhydride, and the like.
Further, ethylene tetracarboxylic dianhydride and cyclopentane tetracarboxylic dianhydride, which are non-aromatic polyvalent carboxylic dianhydrides, can be used as well as aromatic ones.
These are used individually or in mixture of 2 or more types.

Aromatic diamine:
Specific examples of the aromatic diamine include, for example, m-phenylenediamine, o-phenylenediamine, p-phenylenediamine, m-aminobenzylamine, p-aminobenzylamine, 4,4′-diaminodiphenyl ether, 3,3 ′. -Diaminodiphenyl ether, 3,4'-diaminodiphenyl ether, bis (3-aminophenyl) sulfide, (3-aminophenyl) (4-aminophenyl) sulfide, bis (4-aminophenyl) sulfide, bis (3-aminophenyl) ) Sulfide, (3-aminophenyl) (4-aminophenyl) sulfoxide, bis (3-aminophenyl) sulfone, (3-aminophenyl) (4-aminophenyl) sulfone, bis (4-aminophenyl) sulfone, 3 , 3'-Diaminobenzophenone, 3,4 '-Diaminobenzophenone, 4,4'-diaminobenzophenone, 3,3'-diaminodiphenylmethane, 3,4'-diaminodiphenylmethane, 4,4'-diaminodiphenylmethane, bis [4- (3-aminophenoxy) phenyl] methane Bis [4- (4-aminophenoxy) phenyl] methane, 1,1-bis [4- (3-aminophenoxy) phenyl] ethane, 1,1-bis [4- (4-aminophenoxy) phenyl]- Ethane, 1,2-bis [4- (3-aminophenoxy) phenyl] ethane, 1,2-bis [4- (4-aminophenoxy) phenyl] ethane, 2,2-bis [4- (3-amino Phenoxy) phenyl] propane, 2,2-bis [4- (4-aminophenoxy) phenyl] propane, 2,2-bis [4- (3-aminophenyl) Noxy) phenyl] butane, 2,2-bis [3- (3-aminophenoxy) phenyl] -1,1,1,3,3,3-hexafluoropropane, 2,2-bis [4- (4- Aminophenoxy) phenyl] -1,1,1,3,3,3-hexafluoropropane, 1,3-bis (3-aminophenoxy) benzene, 1,3-bis (4-aminophenoxy) benzene, 1, 4-bis (3-aminophenoxy) benzene, 1,4-bis (4-aminophenoxy) benzene, 4,4′-bis (3-aminophenoxy) biphenyl, 4,4′-bis (4-aminophenoxy) Biphenyl, bis [4- (3-aminophenoxy) phenyl] ketone, bis [4- (4-aminophenoxy) phenyl] ketone, bis [4- (3-aminophenoxy) phenyl] sulfur Bis [4- (4-aminophenoxy) phenyl] sulfide, bis [4- (3-aminophenoxy) phenyl] sulfoxide, bis [4- (4-aminophenoxy) phenyl] sulfoxide, bis [4- (3 -Aminophenoxy) phenyl] sulfone, bis [4- (4-aminophenoxy) phenyl] sulfone, bis [4- (3-aminophenoxy) phenyl] ether, bis [4- (4-aminophenoxy) phenyl] ether, 1,4-bis [4- (3-aminophenoxy) benzoyl] benzene, 1,3-bis [4- (3-aminophenoxy) benzoyl] benzene, 4,4′-bis [3- (4-aminophenoxy) ) Benzoyl] diphenyl ether, 4,4′-bis [3- (3-aminophenoxy) benzoyl] diphenyl ether 4,4′-bis [4- (4-amino-α, α-dimethylbenzyl) phenoxy] benzophenone, 4,4′-bis [4- (4-amino-α, α-dimethylbenzyl) phenoxy] Diphenylsulfone, bis [4- {4- (4-aminophenoxy) phenoxy} phenyl] sulfone, 1,4-bis [4- (4-aminophenoxy) phenoxy] -α, α-dimethylbenzyl] benzene, 1, Examples include 3-bis [4- (4-aminophenoxy) -α, α-dimethylbenzyl] benzene.
These are used individually or in mixture of 2 or more types.

(Additive)
The protective film may contain an additive as long as the effects of the present invention are not impaired.
As an additive, an inorganic filler having a low dielectric constant and dielectric loss tangent is preferable. As this inorganic filler, the thing similar to what was mentioned by description of the adhesive film for coverlays is mentioned.
An inorganic filler may be used individually by 1 type, and may use 2 or more types together.

The inorganic filler may be porous or non-porous. A porous material is preferable in that the dielectric constant and dielectric loss tangent are lower.
The inorganic filler may be subjected to a surface treatment with a surface treatment agent such as a silane coupling agent or a titanate coupling agent in order to improve dispersibility in polyimide.
When it contains an inorganic filler, 0.1-100 mass% is preferable with respect to a polyimide, and, as for content of the inorganic filler in a protective film, 0.1-60 mass% is more preferable.

(Protective film thickness)
The thickness of a protective film is not specifically limited, For example, 5-100 micrometers is preferable.

[Coverlay manufacturing method]
The coverlay is usually manufactured by sequentially laminating an adhesive film for a coverlay and a protective film on a separator and press-bonding them, but this is not restrictive. For example, in the case of continuous production until the production of a wiring board to be described later, the coverlay is formed by sequentially laminating a coverlay adhesive film and a protective film on the substrate on which the wiring is formed so as to cover the wiring. Can be manufactured.
The coverlay adhesive film, the protective film, the separator, and the like used are the same as those described in the above section “Coverlay adhesive film” and “Coverlay”.
In addition, the surface of the protective film, for example, the surface in contact with the coverlay adhesive film, may be subjected to a surface treatment in order to enhance the adhesion to the Burlay adhesive film. The surface treatment method is not particularly limited, and examples thereof include known surface treatment methods such as corona discharge treatment and plasma treatment.

(Crimping method)
The method for pressure bonding is not particularly limited, but from the viewpoint of improving the adhesion, a method of heat pressure bonding using a hot press apparatus or the like is preferable.
The temperature during thermocompression bonding is preferably 295 to 420 ° C, more preferably 300 to 400 ° C. If temperature is more than the said lower limit, adhesiveness can be improved further, and if it is below the said upper limit, it is excellent in thermal stability.
The pressure is preferably 0.3 to 30 MPa, more preferably 0.5 to 20 MPa, and most preferably 1 to 10 MPa. The crimping time is preferably 3 to 240 minutes, more preferably 5 to 120 minutes, and most preferably 10 to 80 minutes.
Moreover, a hot press can be performed using a press board, a roll, etc. The press plate is preferably a stainless steel plate.

<Wiring board>
As long as the wiring board of this invention is provided with the above-mentioned coverlay, the structure in particular is not restrict | limited. For example, a preferred embodiment of the wiring board of the present invention includes at least a substrate, wiring, the above-described coverlay adhesive film, and a protective film, and the wiring, the coverlay adhesive film, and the protective film on the substrate. Are stacked in this order.
The wiring board may be a single-layer wiring board or a multilayer wiring board.
The wiring is mainly formed from copper.
The material of the substrate is not particularly limited. For example, in the case of FPC, it is preferable to use the same material as the protective film, and a polyimide film is preferable.

When the wiring board of the present invention is processed in the atmosphere at a temperature of 150 ° C. for 1000 hours, the color difference ΔE (transmission) of the wiring board before and after processing (where no wiring is present) conforming to JIS Z8730. Is preferably 2.0 or less, more preferably 1.8 or less, and even more preferably 1.6 or less.
When the wiring board of the present invention is processed in the atmosphere at a temperature of 150 ° C. for 1000 hours, the color difference ΔE (reflection) of the adhesive film for the cover lay of the wiring board before and after the treatment, in accordance with JIS Z8730, It is preferably 5.0 or less, more preferably 4.5 or less, and even more preferably 3.0 or less.

[Method of manufacturing a wiring board]
The method of manufacturing the wiring board is not particularly limited. For example, a metal foil of a metal-clad laminate such as a copper-clad laminate is processed into a predetermined pattern by a method such as chemical etching to form a wiring on the substrate. Then, a method of laminating a cover lay on a necessary portion on the circuit (wiring) and then thermocompression bonding using a hot press apparatus or the like can be mentioned.
Further, as described above, the coverlay adhesive film and the protective film may be sequentially laminated on the substrate on which the wiring is formed, and then may be thermocompression bonded together.
The details of the pressure bonding conditions and the heat press at the time of thermocompression bonding are the same as those in the above-described method for manufacturing the coverlay.

[Application of wiring board]
The use of the wiring board of this invention is not specifically limited, For example, FPC etc. are mentioned. Specifically, in the long-term heat resistance test at 150 ° C. for 1000 hours in the atmosphere, the peel strength retention rate between the substrate and wiring and the protective film is excellent. Can be suitably used. Especially, it is preferable to use it as an in-vehicle electronic device for a headlamp substrate, a transmission or an engine.

<Method for manufacturing electronic device>
Manufacture of an electronic device including the wiring board of the present invention may be performed by a known method for each use of the above-described wiring board.
The method for manufacturing an electronic device may include a step of exposing the wiring board to a high temperature environment of 260 ° C. or higher. Even if it has the process of exposing the wiring board to a high temperature environment of 260 ° C. or higher, since the wiring board has the coverlay adhesive film of the present invention, the coverlay adhesive film, the substrate, the wiring, and the protective film The adhesion and adhesion between the two are not impaired. Therefore, the wiring board of this invention can be used suitably for manufacture of the various electronic devices which require the process of exposing this wiring board to a 260 degreeC or more high temperature environment.

<Operational effects of the present invention>
The adhesive film for coverlay of this invention contains the fluorine-containing copolymer (A) which has functional group (I). Since the fluorine-containing copolymer (A) has the functional group (I), the coverlay adhesive film of the present invention is excellent in adhesiveness to the substrate, wiring and protective film.
In addition, since the coverlay adhesive film of the present invention has excellent flexibility and thermoplasticity, in the wiring board of the present invention, it is possible to fill recesses such as between the wirings (regions where no wiring is formed on the substrate). , The formation of voids in the recess can be suppressed. Therefore, the coverlay adhesive film of the present invention can adhere the substrate, wiring and protective film with high adhesion.
Further, in the method of manufacturing an electronic device, even if the wiring board has a step of exposing it to a high temperature environment of 260 ° C. or higher, the wiring board has the cover lay adhesive film, and therefore the cover lay adhesive film and the substrate The adhesion and adhesion between the wiring and the protective film are not impaired.

As described above, according to the present invention, the adhesive film for coverlay, the coverlay, the wiring board, and the electronic device, which are excellent in the peel strength retention ratio between the substrate and the wiring and the protective film, even when repeatedly exposed to a high temperature environment The manufacturing method of can be provided. Specifically, in a long-term heat resistance test at 150 ° C. for 1000 hours in the atmosphere, the peel strength retention rate between the substrate and wiring and the protective film is excellent.
Moreover, even if it uses repeatedly the adhesive film for coverlays of this invention in a high temperature environment, discoloration of a protective film does not arise easily.

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

<Measurement method>
[Copolymerization composition of fluorine-containing copolymer]
The copolymer composition was determined by melt NMR analysis, fluorine content analysis and infrared absorption spectrum analysis.

[Content of Functional Group (I) in Fluorinated Copolymer]
The proportion of structural units based on the monomer (NAH) having a functional group (I) in the fluorine-containing copolymer was determined by the following infrared absorption spectrum analysis.
The fluorine-containing copolymer was press-molded to obtain a 200 μm film. In the infrared absorption spectrum, any absorption peak in the structural unit based on NAH in the fluorine-containing copolymer appears at 1778 cm ⁻¹ . The absorbance of the absorption peak was measured, and the ratio a (mol%) of the structural unit based on NAH was determined using a molar absorption coefficient of NAH of 20810 L / (mol · cm).
The number of the fluorine-containing copolymer backbone number 1 × 10 ⁶ cells for functional group carbon (I) (acid anhydride group) is obtained by the formula "a × ¹⁰ 6/100" (number).

[Melting point of fluorine-containing copolymer (° C)]
Using a differential scanning calorimeter (DSC apparatus) manufactured by Seiko Electronics Co., Ltd., the melting peak when the fluorine-containing copolymer (A) was heated at a rate of 10 ° C./min was recorded, and the temperature corresponding to the maximum value ( ° C.) was defined as the melting point (Tm).

[MFR of fluorinated copolymer (g / 10 min)]
Fluoropolymer that flows out for 10 minutes (unit time) from a nozzle with a diameter of 2 mm and a length of 8 mm under a load of 372 ° C. and 5 kg under a load of 372 ° C., which is 20 ° C. higher than the melting point, using a melt indexer manufactured by Techno Seven The mass (g) was measured and the value was defined as MFR (g / 10 min).

[Peel strength (N / 10mm)]
In order to measure the peel strength between the substrate and the wiring and the coverlay, the wiring board was cut into a size of 100 mm in length and 10 mm in width to prepare a test film. The copper foil and the coverlay were peeled from one end in the length direction of the test film to a position of 50 mm. Next, the test film is peeled 90 degrees at a tensile speed of 50 mm / min using a tensile tester (Orientec Co., Ltd.) centered at a position 50 mm from one end in the length direction of the test film, and the maximum load is peel strength (N / 10 mm). It shows that the adhesiveness between a board | substrate and wiring, and a coverlay is excellent, so that peeling strength is large.
In the above measurement, when the peel strength was 0.2 N / 10 mm or less, the variation in the measured value was large, and the results of the peel strength in this case were all expressed as 0.2 N / 10 mm or less.

The peel strength (N / 10 mm) was obtained before and after the wiring board was heat-treated in the atmosphere at 150 ° C. for 200 hours or 1000 hours using an oven (manufactured by Tabay Espec).
The ratio of the peel strength after the heat treatment to the peel strength before the heat treatment was defined as “peel strength retention rate (%)”.

[Color difference of wiring board]
About the wiring board before and after the heat treatment performed in the same manner as the heat treatment in the peel strength, the chromaticity (L of the wiring board) is determined by the integrating sphere transmission method, the light source, and the viewing angle of D65 light 10 degrees in accordance with JIS Z8730. ^* Value, a ^* value, b ^* value, Y.I value). For the measurement, a color meter (manufactured by Suga Test Instruments Co., Ltd.) was used. Further, the measurement was performed on an area without wiring.
The color difference ΔE (transmission) of the wiring board was calculated according to the following formula (1). Color difference ΔY. I is Y. after heat treatment. I to Y before heat treatment. Obtained by subtracting I.
ΔE = (Δa ² + Δb ² + ΔL ² ) ^1/2 (1)
Δa, Δb, and ΔL in equation (1) are the a ^* values of the untreated wiring board sample and the wiring board sample after being treated in the atmosphere at a temperature of 150 ° C. for 200 hours or 1000 hours, respectively. , B ^* value, and L ^* value. A smaller ΔE means less discoloration.

[Color difference of adhesive film for coverlay]
The chromaticity of the adhesive film for coverlay before and after the heat treatment was measured using the coverlay peeled off from the wiring board before and after the heat treatment performed in the same manner as the heat treatment in the peel strength. Specifically, from the coverlay adhesive film side of the coverlay peeled off from the wiring board, the integrating sphere type reflection method, light source, and viewing angle in accordance with JIS Z8730 are chromaticity ( L ^* value, a ^* value, b ^* value, Y.I value). For the measurement, a color meter (manufactured by Suga Test Instruments Co., Ltd.) was used.
The color difference ΔE (reflection) of the coverlay adhesive film was calculated according to the above formula (1). Color difference ΔY. I is Y. after heat treatment. I to Y before heat treatment. Obtained by subtracting I.

[Heat resistance test]
The wiring board was placed in an oven controlled at a furnace temperature of 280 ° C. for 1 minute, and then the sample was taken out and visually observed for the presence of swelling (foaming).

<Production Example 1>
TFE (manufactured by Asahi Glass Co., Ltd.) as the monomer that forms the structural unit (a1), NAH (hydromix acid anhydride, manufactured by Hitachi Chemical Co., Ltd.) as the monomer that forms the structural unit (a2), and monomer that forms the structural unit (a3) Fluoropolymer (A1-1) was produced using PPVE (CF ₂ = CFO (CF ₂ ) ₃ F, perfluoropropyl vinyl ether, manufactured by Asahi Glass Co., Ltd.).
First, 369 kg of 1,3-dichloro-1,1,2,2,3-pentafluoropropane (AK225cb, manufactured by Asahi Glass Co., Ltd.) (hereinafter referred to as “AK225cb”) and 30 kg of PPVE are degassed in advance. The polymerization volume with a stirrer having an inner volume of 430 L was charged. Next, the inside of the polymerization tank was ripened and heated to 50 ° C., and further charged with 50 kg of TFE, the pressure in the polymerization tank was increased to 0.89 MPa / G.
Furthermore, a polymerization initiator solution in which (perfluorobutyryl) peroxide was dissolved in AK225cb at a concentration of 0.36% by mass was prepared, and 3 L of the polymerization initiator solution was added to the polymerization tank at a rate of 6.25 mL per minute. Polymerization was carried out while continuously adding. Further, TFE was continuously charged so that the pressure in the polymerization tank during the polymerization reaction was maintained at 0.89 MPa / G. A solution in which NAH was dissolved in AK225cb at a concentration of 0.3% by mass was continuously charged in an amount corresponding to 0.1 mol% with respect to the number of moles of TFE charged during the polymerization.

8 hours after the start of polymerization, when 32 kg of TFE was charged, the temperature in the polymerization tank was lowered to room temperature, and the pressure was purged to normal pressure. The obtained slurry was solid-liquid separated from AK225cb and dried at 150 ° C. for 15 hours to obtain 33 kg of a fluorinated copolymer (A1-1). The specific gravity of the obtained fluorine-containing copolymer (A1-1) was 2.15.
From the results of melt NMR analysis and infrared absorption spectrum analysis, the copolymer composition of this fluorinated copolymer (A1-1) is a structural unit based on TFE (structural unit (a1)) / a structural unit based on NAH (constituent Unit (a2)) / constituent unit based on PPVE (constituent unit (a3)) = 97.9 / 0.1 / 2.0 (mol%). Moreover, melting | fusing point of this fluorine-containing copolymer (A1-1) was 300 degreeC, and MFR was 17.6 g / 10min.

<Production Example 2>
The fluorine-containing copolymer (A1-1) was extruded at a die temperature of 340 ° C. using a 30 mmφ single-screw extruder having a 750 mm wide coat hanger die, and a 25 μm thick adhesive film for coverlay (hereinafter referred to as “cover”). It was referred to as “Lay adhesive film 1”.

<Production Example 3>
Instead of the fluorinated copolymer (A1-1), PFA-1 (TFE / perfluoro (alkyl vinyl ether) copolymer, melting point 305 ° C., MFR 13.6 g / 10 min, manufactured by Asahi Glass Co., Ltd., product name “Fluon PFA 73PT” ) Was used in the same manner as in Production Example 2 to obtain a coverlay adhesive film having a thickness of 25 μm (hereinafter referred to as “coverlay adhesive film 2”).

[Example 1]
Polyimide film as substrate (product name “Kapton” manufactured by Toray DuPont), copper foil for wiring (thickness 18 μm, rolled copper foil), adhesive film 1 for coverlay, and polyimide film (Ube) as protective film Kosan Co., Ltd. product name “UPILEX”, thickness 25 μm) was used.
First, copper foil was laminated | stacked on the board | substrate, the copper wiring was formed by the chemical etching method, and the adhesive film 1 for coverlays and the polyimide-type film were laminated | stacked in this order on it. Next, using a hot press apparatus (manufactured by Kitagawa Seiki Co., Ltd.), hot pressing was performed for 5 minutes under the conditions of a temperature of 360 ° C. and a pressure of 1.5 MPa, thereby producing the wiring board 1.
When visually observed, there was almost no gap between the wiring of the wiring board 1 and the protective film, and the degree of adhesion between the substrate and the wiring and the protective film appeared to be high.
Moreover, the wiring board 1 was heat-processed on condition of 150 degreeC and 1000 hours in air | atmosphere using oven (made by Tabai Espec).
After the heat treatment, the peel strength between the substrate and wiring and the protective film and the color difference of the protective film were determined according to the above procedure.

[Comparative Example 1]
A wiring board 2 was prepared in the same procedure as in Example 1 except that the coverlay adhesive film 2 was used instead of the coverlay adhesive film 1.
When visually observed, voids were observed between the wirings of the wiring board 2 and the degree of adhesion between the substrate and the wirings and the protective film seemed to be low.
About the wiring board 2, similarly to Example 1, the peeling strength between a board | substrate and wiring, and a protective film and the color difference of the protective film were calculated | required.

As a result, the peel strength between the substrate and wiring of Example 1 and the protective film was higher than that of Comparative Example 1.
Further, the color difference of the protective film of Example 1 was smaller than that of Comparative Example 1.

[Example 2]
25 μm polyimide film (made by Toray DuPont, product name “Kapton”) as substrate, copper foil for wiring (thickness 18 μm, rolled copper foil), adhesive film 1 for coverlay, and polyimide film as protective film ( Toray DuPont, product name “Kapton”, thickness 25 μm) was used.
First, copper foil was laminated | stacked on the board | substrate, the copper wiring was formed by the chemical etching method, and the adhesive film 1 for coverlays and the polyimide-type film were laminated | stacked in this order on it. Next, using a hot press apparatus (manufactured by Kitagawa Seiki Co., Ltd.), hot pressing was performed for 5 minutes under the conditions of a temperature of 360 ° C. and a pressure of 1.5 MPa, thereby producing the wiring board 3. In addition, the same thing was produced for the wiring board 3 in order to use for the following tests.

When visually observed, there was almost no gap between the wiring of the wiring board 3 and the protective film, and the degree of adhesion between the substrate and the wiring and the protective film appeared to be high.
As a result of the heat resistance test of the wiring board 3, no swelling (foaming) due to heat was found.
With respect to the wiring board 3 before and after the heat treatment, the chromaticity of the wiring board (where no wiring is present) was measured to obtain the color difference. Moreover, about the wiring board 3 before and behind heat processing, peel strength was measured and the peel strength retention rate was calculated | required. Table 1 shows the evaluation results. In the table, “untreated” indicates the result of chromaticity and peel strength using the wiring board 3 before the heat treatment.

As shown in Table 1, the color difference ΔE (transmission) of the wiring board 3 was as small as 0.25.
Further, the peel strength retention was as high as 95% under the conditions of 150 ° C. and 200 hours in the air and 90% under the conditions of 150 ° C. and 1000 hours in the air.

  Moreover, the chromaticity of the adhesive film 1 for coverlays was measured using the wiring board 3 before and after the heat treatment, and the color difference was obtained. Table 2 shows the evaluation results. In the table, “untreated” indicates the result of chromaticity using the wiring board 3 before the heat treatment.

  As shown in Table 2, the color difference ΔE (reflection) of the coverlay adhesive film 1 was as small as 2.93.

The use of the adhesive film for coverlays of the present invention is not particularly limited, and examples thereof include coverlays such as wiring boards.
The use of the coverlay of this invention is not specifically limited, For example, a wiring board etc. are mentioned.
The use of the wiring board of this invention is not specifically limited, For example, FPC etc. are mentioned. Specifically, in the long-term heat resistance test at 150 ° C. for 1000 hours in the atmosphere, the peel strength retention rate between the substrate and wiring and the protective film is excellent. Can be suitably used. Especially, it is preferable to use it as an in-vehicle electronic device for a headlamp substrate, a transmission or an engine.

Claims (11)

  Coverlay comprising a fluorine-containing copolymer (A) that can be melt-molded and has at least one functional group selected from the group consisting of a carbonyl group-containing group, a hydroxy group, an epoxy group, and an isocyanate group Adhesive film.   The fluorine-containing copolymer (A) is at least selected from the group consisting of a hydrocarbon group containing a carbonyl group between carbon atoms, a carbonate group, a carboxyl group, a haloformyl group, an alkoxycarbonyl group, and an acid anhydride residue. The adhesive film for coverlays of Claim 1 which has 1 type of functional groups. The adhesive film for coverlay according to claim 1 or 2, wherein the content of the functional group is 10 to 60000 with respect to 1 x 10 ⁶ main chain carbon atoms of the fluorine-containing copolymer (A). .   The adhesive film for coverlay according to any one of claims 1 to 3, wherein a melting point of the fluorine-containing copolymer (A) is 260 to 320 ° C.   The coverlay by which the adhesive film for coverlays as described in any one of Claims 1-4 is laminated | stacked on a protective film.   A coverlay adhesive film and a protective film according to any one of claims 1 to 4 are provided, and the wiring, the coverlay adhesive film, and the protective film are arranged in this order on the substrate. A wiring board that is laminated.   When the wiring board is treated in the atmosphere at a temperature of 150 ° C. for 1000 hours, the color difference ΔE (transmission) of the wiring board before and after the treatment (where no wiring is present) conforming to JIS Z8730 is 2.0 or less. The wiring board according to claim 6, wherein:   When the wiring board is treated in the atmosphere at a temperature of 150 ° C. for 1000 hours, the color difference ΔE (reflection) of the adhesive film for the cover lay of the wiring board before and after the treatment according to JIS Z8730 is 5.0 or less. The wiring board according to claim 6 or 7, characterized by the above.   The wiring board as described in any one of Claims 6-8 which is an object for vehicle-mounted electronic devices of a vehicle-mounted power train.   The wiring board according to claim 9, wherein the in-vehicle power train is a headlamp board, a transmission, or an engine. It is a manufacturing method of an electronic device provided with the wiring board as described in any one of Claims 6-10,
A method of manufacturing an electronic device, comprising a step of exposing the wiring board to a high temperature environment of 260 ° C. or higher.