JPH11220248A - Flexible wiring board with bending part and protection paint film material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To protect wiring by covering wiring across on a slit opening part with a protection paint film where an initial elastic rate is set to a specific range, the breaking point strength of the specific range is provided, an expansion rate is set to a specific range, electric insulation property is sufficient, a thermal decomposition start temperature is set to the specific range, and a solder heat resistance property exceeding a specified one is shown. SOLUTION: The one-side surface of a number of wires 5 across a slit-shaped opening part 4 of a bending part 3 of a flexible wiring board 2 is covered with a protection paint film 6. The paint film 6 is formed by a covering composition where an initial elastic rate is set to 1-70 kg/mm<2> as a film, breaking point strength is set to approximately 0.5-20 kg/mm<2> at 25 deg.C, an expansion rate is set to approximately 30-500%, electric insulation property is maintained at a sufficient level, thermal decomposition start temperature is set to approximately 250-500 deg.C, and a solder heat resistance property of 30 seconds or more at 200 deg.C is shown. This sort of protection paint film 6 is provided, thus preventing a number of the wires 5 consisting of metal foil from being broken at the bending part 3 even when the flexible wiring board 2 is bent by, for example, 180 deg.C at the slit opening part 4 of a support film 1.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a support at a bent portion of a "flexible wiring board having a wiring of a conductive material formed on a support film (for example, a flexible wiring member, a wiring member for TAB, etc.)". At least one surface of a large number of wirings crossing the slit-shaped opening of the film is covered with a flexible protective film made of a coating composition, and a large number of wirings crossing the slit-shaped opening of the flexible wiring board are bent. The present invention relates to a flexible wiring board having a bent portion which is not easily broken and a protective coating material thereof.

[0002]

2. Description of the Related Art Conventionally, a flexible wiring board (a flexible wiring member,
The wiring member for TAB, etc.) is such that a portion of the support film is opened in a slit shape and a portion of the wiring board is easily bent along the slit-shaped opening. Is finally required to be mounted in a narrow space inside an electric appliance or the like.

However, such a flexible wiring board with a bent portion has a large number of wirings (bare wires after copper foil is etched) crossing the slit-shaped opening, and has a low mechanical strength. Therefore, if the wiring board is bent as it is along the slit-shaped opening, a large number of wirings crossing the slit-shaped opening may be extremely easily broken and disconnected, and it is necessary to provide some protection for the wiring. there were. Various proposals have been made to solve this problem, but there are still few simple and industrial means capable of effectively protecting the large number of wirings from breaking.

[0004]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a flexible wiring board having a bent portion as described above, which is provided with a bent portion in which "a large number of wires" crossing a slit-shaped opening in the bent portion are effectively protected. It is an object of the present invention to provide a flexible wiring board (for example, a flexible wiring board, a wiring board for TAB, etc.), and further provide a protective coating material thereof.

[0005]

According to the present invention, a flexible wiring board having a conductive film formed on a support film is provided with an insulating protective coating on the main wiring. In the wiring board, the support film has a slit-shaped opening at the bent portion, a large number of wirings are provided across the slit-shaped opening, and at least one of the wirings traversing over the slit opening. On one side surface,
The film has an initial elastic modulus of 1 to 70 kg / mm ² , 2
The strength at break at 5 ° C. is about 0.5 to 20 kg / mm ² , the elongation is about 30 to 500%, the electric insulation is maintained at a sufficient level, and the thermal decomposition onset temperature is about 250 to 500.
The present invention relates to a flexible wiring board with a bent portion, which is coated with a protective coating having a solder heat resistance of at least 30 ° C. and 200 ° C. for 30 seconds. The present invention relates to a protective coating material (comprising a resin and an organic polar solvent) for providing a protective coating for a plate.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, each invention of the present application will be described in detail with reference to the drawings. FIG. 1 shows an example of a flexible wiring board with a bent portion according to the present invention (a part of a main wiring region covered with an insulating protective coating made of a solder resist and a bent portion). 2 is a cross-sectional view of the wiring board of FIG. 1 taken along line AA, and FIG. 3 is a cross-sectional view of the wiring board of FIG. 1 taken along line BB.

FIG. 4 is a sectional view showing a state in which the flexible wiring board with a bent portion of the present invention is bent at the bent portion. FIG.
FIG. 6 partially shows an example of a flexible wiring board provided with an insulating protective coating film used for manufacturing the flexible wiring board with a bent portion of the present invention, and FIG. 6 shows a CC line of the wiring board of FIG. FIG. 7 is a sectional view taken along line DD of the wiring board of FIG.

The wiring board used in the flexible wiring board with a bent portion according to the present invention has a wiring of a conductive material formed on a surface of a supporting film (base material) 1 by an etching process of a metal foil or the like. Flexible wiring board (for example, flexible wiring board, wiring for TAB, etc.) 2 and an insulating protective coating film (also referred to as a solder resist film) on the surface of most (region) of the main wiring. 5), and as shown in FIG. 5, FIG. 6, and FIG. 7, the flexible wiring board 2 has Wiring 5 is provided across the slit-shaped opening 4.
Further, as shown in FIGS. 1, 2 and 3, the flexible wiring board 2 with a bent portion of the present invention has at least a large number of wirings 5 provided across the slit-shaped openings 4 of the support film 1. One surface (only one surface is shown in the drawings) is covered with a flexible protective coating 6 made of a specific coating composition.

Examples of the support film include a heat-resistant polymer film such as an aromatic polyimide film, an aromatic polyamide film, an aromatic polyester film, and an inorganic film.
As the conductive wiring, a fine wiring (line width: 10 to 500) formed by etching or the like from a metal foil (thickness: 10 to 200 μm) such as a copper foil or an aluminum foil.
μm, especially 30 to 300 μm, and line spacing: 10 to 5
00 μm, especially 50 to 400 μm).

In the present invention, the support film is preferably a long heat-resistant film having a pair of sprockets (holes) arranged at both ends, which is used for a wiring board for TAB. .

The above-mentioned insulating protective coating (solder resist film) may be made of a known solder resist which has been widely used in the production of wiring boards.
For example, a protective coating film made of a heat-resistant resin such as an epoxy resin solder resist or a polyimide resin solder resist and having a thickness of 5 to 500 μm can be given.

As shown in FIG. 1, the flexible wiring board 2
The protective coating film 6 covering one surface (or both side surfaces, not shown) of a large number of wirings 5 traversing the slit-shaped opening 4 of the bent portion 3 has an initial elastic modulus of 1 to 1 as a film. 70kg / mm ^2, 25 break strength of at ℃ about 0.5 to 20 / mm ^2, elongation of about 30 to 50
0%, having a sufficient level of electrical insulation, a thermal decomposition onset temperature of about 250 to 500 ° C, and a coating composition exhibiting solder heat resistance at 200 ° C for 30 seconds or more; and The thickness of the protective coating 6 is preferably 0.2 to 5 times the thickness of a large number of wirings 5 traversing the slit-shaped opening 4, and particularly preferably about 0.5 to 200 μm. Is preferred.

In the flexible wiring board with a bent portion according to the present invention, the plurality of wirings 5 traversing the slit-shaped openings 1 of the bent portion 3 have a small initial elastic modulus and are flexible. 6, at least one surface thereof is covered, and as shown in FIG. Even if it is bent to 180 ° at step 4, many wires 5 made of metal foil do not break at the bent portions, and the present invention has the greatest feature in this point.

The above coating composition includes, for example, (A)
Biphenyltetracarboxylic acids such as 2,3,3 ′, 4′- or 3,3 ′, 4,4′-biphenyltetracarboxylic acid or an acid dianhydride or an acid derivative thereof (60) An aromatic tetracarboxylic acid component (containing at least 70% by mole, especially 70 to 100% by mole);
50-90 mol% of diaminopolysiloxane, especially 55-90
85 mol%, and (b) a diamine component consisting of 10 to 50 mol%, especially 15 to 45 mol% of an aromatic diamine,
Preferable examples include a resin composition containing a soluble polyimide siloxane obtained by polymerization and imidization in an organic polar solvent, or an epoxy resin modified product thereof in an amount of 80% by weight or more of the resin component.

In the above aromatic tetracarboxylic acid component, "other aromatic tetracarboxylic acids" which can be used together with biphenyltetracarboxylic acids include:
3,3 ′, 4,4′-benzophenonetetracarboxylic acid, 3,3 ′, 4,4′-biphenylethertetracarboxylic acid, pyromellitic acid or a dianhydride of those acids,
Alternatively, esters of these acids can be mentioned.

The above-mentioned diaminopolysiloxane includes:
The group bonded to the amino group is a “multiple methylene group” having 2 to 6 carbon atoms or a divalent hydrocarbon residue composed of a phenylene group, and the groups bonded to the Si group are each independently a methyl group. It is preferably an alkyl group having 1 to 3 carbon atoms such as an ethyl group or a propyl group, or a phenyl group, and more preferably about 5 to 20 repeating units of —Si—O—.

The aromatic diamine is preferably an aromatic diamine compound having a plurality of benzene rings, for example, 4,4'-diaminodiphenyl ether,
Aromatic diamine compounds having two benzene rings such as 4'-diaminodiphenylmethane, 4,4'-diaminodiphenylsulfone, o-tolidine, o-dianisidine,
1,4-bis (4-aminophenoxy) benzene, 1,
An aromatic diamine compound having three benzene rings such as 4-bis (4-aminophenyl) benzene, and bis [4- (4-aminophenoxy) phenyl] sulfone;
Aromatic diamine compounds having four benzene rings, such as 2,2-bis [4- (4-aminophenoxy) phenyl] propane, are preferred.

As the aromatic diamine, an aromatic diamine compound having one or more benzene rings is used together with an aromatic diamine compound having two or more benzene rings at a ratio of 60 mol% or less based on the total aromatic diamine component. Aromatic diamine compounds having one benzene ring include, for example, paraphenylenediamine, metaphenylenediamine, 2,4-diaminotoluene, 3,5
-Diaminobenzoic acid, 2,6-diaminobenzoic acid, 3,
5-diaminobenzyl acrylate and the like can be mentioned.

In the above polyimide siloxane,
When the content ratio of the `` main chain unit based on diaminopolysiloxane '' with respect to all diamine components is reduced, the solubility of such a polyimidesiloxane may be reduced,
On the other hand, when the content ratio of the "main chain unit based on diaminopolysiloxane" is increased, the heat resistance, mechanical properties, adhesiveness to wiring and the like of the polymer may be considerably lowered, which is not preferable.

The polyimide siloxane has a concentration of 0.
High molecular weight polymer having a logarithmic viscosity (indicating the degree of polymerization of the polymer) measured at a measurement temperature of 30 ° C. with a polymer solution of 5 g / 100 ml (N-methyl-2-pyrrolidone) is about 0.05 to 3 Is preferable, and
The imidation ratio of polyimide siloxane (the ratio of “imide bond” by infrared absorption spectroscopy) is about 9%.
It is preferably 0% to 100%, and the absorption peak of “amide-acid bond” is not substantially found in the IR chart.

The above-mentioned polyimide siloxane is partially modified with an appropriate room temperature or thermosetting resin, for example, an epoxy resin such as a phenol-based epoxy resin, a novolak-type epoxy resin, and a bisphenol-based epoxy resin. A protective coating containing such a modified epoxy resin of polyimide siloxane is preferable because of its excellent chemical resistance and heat resistance (such as solder heat resistance).

The polyimide siloxane is, for example,
(A) an aromatic tetracarboxylic acid component mainly containing 2,3,3 ′, 4′-biphenyltetracarboxylic acids; and (B) a diamine component comprising (a) a diaminopolysiloxane and (b) an aromatic diamine. Can be produced by heating in a substantially equimolar organic polar solvent to a high temperature of 120 ° C. or higher to carry out polymerization and imidization in one step. In addition, the polyimide siloxane, the two components of the acid component and the diamine component, approximately equimolar, in an organic polar solvent, polymerized at a low temperature of 80 ℃ or less to generate a polyamic acid, the polyamic acid suitable It can also be produced by imidization by means (imidization method using a chemical imidizing agent or imidation method using high-temperature heating).

Examples of the organic polar solvent used in the above-mentioned production method include sulfoxide-based solvents, formamide-based solvents, acetamide-based solvents, pyrrolidone-based solvents, glyme-based solvents such as methyldiglyme and methyltridiclime, and hexamethylene phosphone. Luamide, γ-butyrolactone, cyclohexanone and the like, and phenol solvents.

The coating composition constituting the protective coating is a composition containing substantially no volatile components, and further contains wollastonite in addition to the resin component. , Silica, talc or the like, an inorganic filler, a polymer filler, or a pigment or a dye.

When a film comprising the above coating composition is formed, the film has an initial elastic modulus of 1 to 70 kg.
/ Mm ² , which is flexible and has suitable mechanical strength (strength at break at 25 ° C .: about 0.5 to 20 kg / mm ² ,
(Elongation: about 30 to 500%), retains electrical insulation at a sufficient level, and has heat resistance (the thermal decomposition onset temperature is about 250 to 500 ° C, and at 200 ° C for 30 seconds or more,
In particular, solder heat resistance of 1 minute or more is high.

As a method of manufacturing the flexible wiring board with a bent portion of the present invention, for example, the flexible wiring board 2 (after the metal foil etching step) in which wiring of a conductive material is formed on a supporting film is roughly described. The flexible wiring board before mounting components and / or soldering, T
A heat-resistant resin solution is applied on the main wiring area of an AB wiring board, etc. to form an insulating protective coating film 7 (solder resist film, etc.), and then as shown in FIGS. 5, 6, and 7. The “polyimide siloxane or its modified epoxy resin” is contained in “at least one surface of a large number of wirings 5 provided across the slit-shaped opening 4 of the support film 1 in the bent portion 3 of the wiring board 2”. A coating composition solution in which the coating composition is uniformly dissolved or dispersed in an organic polar solvent is applied by a suitable coating means, and the coated film is sufficiently coated at a temperature of 50 to 280 ° C. After drying, as shown in FIGS. 1, 2, 3 and 4, a flexible protective coating 6 from which volatile components have been substantially removed is formed on at least one surface of the wiring 5 traversing the slit opening 4. How to do .

The above-mentioned coating composition solution preferably contains the above-mentioned polyimide siloxane together with other coating components such as a curable resin (epoxy resin) and a filler, and has a boiling point of 10%.
It can be prepared by dissolving or dispersing in an organic polar solvent at 0 ° C. to 250 ° C., and the concentration of polyimidesiloxane is 2 to 60% by weight, particularly about 5 to 50% by weight, and its rotational viscosity ( 25 ° C) is about 500-600
It is preferable that the solution has a solution viscosity of 00 centipoise, particularly 1000 to 50,000 centipoise.

The organic polar solvent used in the coating composition solution is an organic polar solvent having a boiling point of 100 ° C. to 250 ° C., and can easily dissolve the polyimide siloxane. Preferably, the organic polar solvent used in the production of the above-mentioned polyimide siloxane can also be used, and phenol solvents, amide solvents (pyrrolidone solvents, formamide solvents, acetamide solvents, etc.), oxane solvents (Dioxane, trioxane, etc.), glyme solvents (methyl diglyme,
Methyltriglyme, etc.) is particularly preferred, and xylene, ethyl cellosolve and the like may be partially incorporated.

The organic polar solvent includes a boiling point of 120.
A glyme-based solvent having a temperature of ~ 240 ° C is particularly preferred, and a triglyme-based solvent is most preferred.
The coating composition solution prepared by dissolving polyimide siloxane or the like in a triglyme solvent does not increase the viscosity of the coating composition solution due to rapid evaporation of the solvent.
In addition, it has excellent storage stability, and it is easy to prepare (e.g., roll kneading) a coating composition solution (printing ink) for forming the protective coating, and use the printing ink. Thus, there is an advantage that a coating operation such as silk screen printing can be suitably performed without any trouble.

The above coating composition solution is applied to one side surface of the wiring at the bent portion of the flexible wiring board having the bent portion by using a spin coating machine, a dispenser or a silk screen printing machine at room temperature or under heating. Then, the coating film is formed at a temperature of 50 to 280 ° C., preferably 60 to 280 ° C.
It is dried at a temperature of 260 ° C, more preferably at a temperature of 100 to 250 ° C for 0.1 to 10 hours, particularly 0.2 to 5 hours. The above-described insulating protective coating (particularly having a thickness of about 0.5 to 200 μm,
(A dry solidified film having a thickness of about 00 μm) is preferably formed.

The coating composition solution described above is low in inorganic fillers such as wollastonite, silica, talc and the like, polymer fillers, inorganic or organic dyes, curable resins such as epoxy resins, and hardeners. It may be blended in a ratio.

As the above coating composition solution, a polyimidesiloxane polymerization solution obtained by polymerizing and imidizing an aromatic tetracarboxylic acid component and a diamine component in one step in an organic polar solvent can be used as it is. Alternatively, the polymerization solution may be diluted with an organic solvent similar to the polymerization solvent to an appropriate concentration before use. In addition, the coating composition solution is prepared by isolating the polyimide siloxane powder once by precipitating it from the above-described polymerization solution, and uniformly dissolving the isolated polyimide siloxane powder in the organic polar solvent. Can also.

[0033]

The present invention will be described in more detail with reference to the following examples.

Example 1 [Production of polyimide siloxane] 2,3,3 ', 4'-biphenyltetracarboxylic dianhydride (a-BPDA) 14 was placed in a 2-liter glass separable flask.
A-BPDA was charged with 7.2 g (500 mmol) and 1274 g of N-methyl-2-pyrrolidone (NMP).
And, while stirring the solution at room temperature,
Diaminopolysiloxane (DAPS) [X-22-161AS, manufactured by Shin-Etsu Silicon Co., Ltd., a group bonded to an amino group:-(CH ₂ ) _3- , a group bonded to Si:-
CH ₃ , —Si—O— repeating unit = 9] 304.9
g (346.5 mmol) and 530 g of diglyme were added over 30 minutes, and the polymerization and imide were carried out for 3 hours while passing nitrogen gas at a polymerization temperature of 190 ° C. and refluxing methyl diglyme to remove water. Reaction,
Next, the reaction solution was once returned to room temperature and stirred,
2,2-bis [4- (4-aminophenoxy) phenyl] propane (BAPP) 6 was added to the cooled reaction solution.
A solution of 2.19 g (151.5 mmol) and 500 g of NMP was added dropwise over a period of 30 minutes, and a reaction temperature of 20 g was added.
The reaction was carried out at 0 to 210 ° C. for 6 hours to produce a polyimidesiloxane.

After the reaction solution was cooled, it was added to 20 liters of methanol, and 30 ml was added using a disperser.
The polymer powder was isolated by filtration and the polymer powder was isolated, and the polymer powder was subjected to “washing for 10 minutes using a disperser in 10 liters of methanol” twice, and further performed at 60 ° C. for 8 minutes. After vacuum drying for 42 hours, 428.9 g of a polyimidesiloxane powder was obtained.
The polyimide siloxane obtained as described above had a logarithmic viscosity (30 ° C.) of 0.24 and an imidization ratio of substantially 100%.

As for the above-mentioned polyimide siloxane, 0.2 g of the polyimide siloxane powder was added to 0.8 g of methyl diglyme at 20 ° C., and the dissolution state was observed. As a result, the polyimide siloxane was completely dissolved within one hour. did. The polyimidesiloxane has a thermal decomposition onset temperature of about 360 ° C. as measured by a DuPont 951 thermogravimeter.

[Preparation of Coating Composition Solution] 3.5 g of the polyimide siloxane produced as described above was dissolved in 6.5 g of methyl diglyme at room temperature, and the polyimide siloxane was dissolved in methyl diglyme at a polymer concentration of 35 g. weight%
To prepare a coating composition solution uniformly dissolved. The coating composition solution had a solution viscosity (rotational viscosity; 25 ° C.) of 3500 centipoise.

A 200 μm spacer is arranged as a frame on a glass plate, and the coating composition solution is cast on the glass plate to form a thin film.
Heat to 00 ° C, dry and heat treat to a thickness of about 40-
A film having a thickness of 60 μm was formed, and the film was measured for breaking strength, elongation, and initial elastic modulus by a universal tensile tester (manufactured by Orientec, Tensilon UTM-11-20). 0.0kg / m
m ² , elongation: 509%, and initial elasticity: 25 kg /
mm ² . In addition, the said film was left in the furnace of 150 degreeC for 2000 hours,
The tensile strength was 1.6 kg / mm ² , the elongation percentage was 80%, the initial elastic modulus was 23 kg / mm ² , and it had extremely excellent heat resistance and durability.

[Application operation of coating composition solution: formation of protective coating film] As shown in FIG. 5, an aromatic polyimide film having a thickness of 75 μm (UPILE manufactured by Ube Industries, Ltd.)
XS-75) as a base material, using a flexible wiring board 2 (copper foil wiring width: about 300 μm, wiring density: 60%, slit opening size: 8 mm × 20 mm). An epoxy resin-based solder resist (manufactured by Taiyo Ink Co., Ltd., S-22) is applied over the entire main wiring area by a printing method, and the applied film is dried and heat-treated at a temperature of 250 ° C. or more. In the area of the main wiring of the flexible wiring board 2 as shown in FIG.
0 μm), and then the flexible wiring board 2
On one side surface of a large number of wirings 5, a silk screen for screen printing is closely arranged, and a coating film of the coating composition solution is formed using a silk screen printing machine. Apply the above coating film at 80 ° C. for 30 minutes,
After drying and heating (baking) at 150 ° C. for 30 minutes and 180 ° C. for 30 minutes, a protective coating (average film thickness: about 30
μm) to form a flexible wiring board with a bent portion as shown in FIGS. 1, 2 and 3.

The flexible wiring board with the bent portion manufactured as described above was bent at the bent portion ten times or more so as to be in the state shown in FIG. 4 (180 ° bending).
None of the wirings 5 was broken. Further, the flexible wiring board with the bent portion is peeled off by the adhesive tape as a result of the adhesiveness of each protective coating film being measured by an adhesiveness test method according to a grid test method (peeling off with an adhesive tape). There were no parts. The heat resistance of each protective coating in the flexible wiring board with a bent portion is 20
It was immersed in a solder bath at 0 ° C. for 30 seconds, and the change in the state of the protective coating after immersion was observed.

[0041]

The flexible wiring board with a bent portion according to the present invention comprises:
At least one surface of the wiring crossing the slit-shaped opening (bent portion) of the supporting film (substrate) has an initial elastic modulus of 1 to 70 kg / mm ² and a breaking strength at 25 ° C. of about 0.5. ~ 20kg / mm ² , elongation about 3
0 to 500%, electrical insulation is maintained at a sufficient level, and thermal decomposition onset temperature is about 250 to 500 ° C, 200 ° C
Protective coating exhibiting solder heat resistance of 30 seconds or more is provided, so that by bending the bent portion of the wiring board, the wiring crossing the slit-shaped opening is not easily cut off, and has excellent flexibility. A flexible wiring board (for example, a flexible wiring board, a wiring for TAB, etc.) can be obtained.

[Brief description of the drawings]

FIG. 1 is a plan view partially showing an example of a flexible wiring board with a bent portion of the present invention.

FIG. 2 is a cross-sectional view taken along the line AA of the flexible wiring board with a bent portion in FIG.

FIG. 3 is a cross-sectional view taken along the line BB of the flexible wiring board with a bent portion in FIG. 1;

FIG. 4 is a cross-sectional view showing a state in which the flexible wiring board with a bent portion of the present invention is bent at the bent portion of the slit opening.

FIG. 5 is a plan view partially showing an example of a flexible wiring board provided with an insulating protective coating film, which is used for manufacturing the flexible wiring board with a bent portion of the present invention.

6 is a cross-sectional view of the flexible wiring board of FIG. 5 taken along line CC.

FIG. 7 is a cross-sectional view taken along the line DD of the flexible wiring board of FIG. 5;

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 support film 2 flexible wiring board with bent portion 3 bent portion 4 slit-shaped opening 5 wiring (wiring across slit-shaped opening 5) 6 protective coating 7 insulating protective coating

Claims (3)

[Claims] 1. A flexible wiring board in which wiring of a conductive material is formed on a supporting film, an insulating protective coating is applied on main wiring, and the wiring board has the above-described structure at a bent portion. The support film is opened in a slit shape, and a number of wirings are provided across the slit-shaped opening,
Then, at least one surface of the wiring crossing over the slit opening has an initial elastic modulus of 1 to 1 as a film.
70 kg / mm ² , strength at break at 25 ° C. of about 0.5 to
20 kg / mm ² , elongation percentage is about 30-500%, electrical insulation is maintained at a sufficient level, and thermal decomposition onset temperature is about 250-500 ° C, and shows solder heat resistance at 200 ° C for 30 seconds or more. A flexible wiring board with a bent portion, which is covered with a protective coating. 2. The flexible wiring board with a bent portion according to claim 1, which is for TAB. 3. A film having an initial elastic modulus of 1 to 70 as a film which is coated on at least one surface of the wiring of the slit-shaped opening of the flexible wiring board with a bent portion according to claim 1 or 2.
kg / mm ² , strength at break at 25 ° C. of about 0.5 to 20
kg / mm ² , elongation percentage is about 30 to 500%, electrical insulation is maintained at a sufficient level, and thermal decomposition onset temperature is about 250 to 500 ° C, and solder heat resistance is 200 ° C for 30 seconds or more. A protective coating material in which the protective coating provides a protective coating.