JP2000244083A - Flexible circuit board - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To achieve high-density patterning and alignment at the time of semiconductor mounting, the insulating film has heat resistance, dimensional stability,
Provided is a flexible circuit board having good workability, a circuit formed thereon, and a coat layer having good insulation. SOLUTION: It is made of a polyimide containing biphenyltetracarboxylic acids and phenylenediamine as main components, has a thickness of 5-150 μm, an elongation of 45-90%, a tensile modulus of 550-1300 kg / mm 2, and a tear propagation resistance (Elmendorf). ) Is 350-1500 g / mm, an electric conductor is laminated on at least one surface of an aromatic polyimide film to form a circuit, a coating material is applied and dried, the warpage is 25 mm or more, and erosion by tin plating is performed. Is 2
A flexible circuit board provided with a coat layer of 50 mm or less.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to the use of a solution of a polyimide precursor (for example, aromatic polyamic acid) containing biphenyltetracarboxylic dianhydride or a derivative thereof and phenylenediamine as main units,
A conductor is provided by laminating a copper foil on an aromatic polyimide film obtained by film casting by a solution casting method, and then a circuit is formed, and a coating material is applied thereon and dried. Flexible circuit board with a coat layer with good insulation properties, especially aromatic, which has good heat resistance, dimensional stability and workability, enabling high-density patterning and alignment during semiconductor mounting. The present invention relates to a flexible circuit board using a polyimide film.

[0002]

2. Description of the Related Art Conventionally, a flexible circuit board is provided with a metal foil layer such as a copper foil directly or through an adhesive on one or both sides of an aromatic polyimide film, and thereafter a circuit is formed by etching, and a coat is formed thereon. It is common to provide a layer. Aromatic polyimide film used in this application is required to have various properties such as heat resistance, cold resistance, electrical insulation, and mechanical strength. Therefore, a polyimide film composed of a biphenyltetracarboxylic acid component and a phenylenediamine component Is used, for example,
-42817.

However, in the field where the polyimide film is used, high precision and high productivity are required more and more, and the running of a laminate in which a metal foil (for example, a copper foil) and a polyimide film are laminated with an adhesive is performed. It has been pointed out that there are problems of stability, curling of the laminate, and alignment due to lead distortion. For example, in TAB applications, which require particularly high precision, in the case of TAB applications, a sprocket hole is drilled in a tape shape of 35 mm width, 70 mm width, etc.
Depending on the polyimide film as the base film, the running stability of the laminate during processing is poor, and in the worst case, there is a problem in workability that the laminate comes off the sprocket, or curl occurs in the laminate and high density occurs. It has been pointed out that it is difficult to form a pattern, or it is difficult to perform the above-described alignment during semiconductor mounting.

For this reason, various improvements have been made focusing on the dimensional stability and expansion coefficient of the polyimide film. For example, JP-A-61-264027 discloses a method for producing a dimensionally stable polyimide film by reheating a polyimide film obtained from biphenyltetracarboxylic dianhydride and p-phenylenediamine under low tension. Have been. In addition, Japanese Patent Publication No. 4-6213 describes a polyimide film having a linear expansion coefficient ratio (feed direction / perpendicular direction) and a linear expansion coefficient in the feed direction within a specific range and having excellent dimensional stability. In these known techniques, although the dimensional accuracy of the polyimide film itself is high, the dimensional accuracy in the manufacturing process of the application field is also high, and the alignment when mounting other articles is good, and various demands for high density are required. It is difficult to obtain a polyimide film that satisfies the requirements of a flexible circuit board in a well-balanced manner, and it is difficult to satisfy the needs of flexible circuit boards such as high precision, high productivity, uniform quality and low cost. is there.

[0005] Epoxy resin, aromatic polyimide or the like is used as a coating material provided after the circuit formation of the flexible circuit board. However, in general, it is necessary to use an epoxy resin for a coating material in combination, and there are various problems such as storage stability related to the curing agent, workability for preparing a two-package, and heat resistance. Also, when used as the above-mentioned coating material, the insulating film formed by thermosetting is rigid, lacks flexibility, and is inferior in bending property. There is a problem that the alignment is difficult, or stress is applied after connecting to a liquid crystal or the like, and the film eventually peels off and does not function.

When an aromatic polyimide is used as a coating material, it is difficult to dissolve the aromatic polyimide in an organic solvent, so that it is used as a solution of a precursor (aromatic polyamic acid) of the aromatic polyimide. It is necessary to form a coating film and then heat and dry and imidize at a high temperature for a long time to form an aromatic polyimide coat layer, and the flexible circuit board itself to be protected is thermally degraded. There was a problem.

On the other hand, an aromatic polyimide soluble in an organic solvent is prepared by polymerizing and imidizing a biphenyltetracarboxylic acid component and a diamine compound in an organic polar solvent as described in, for example, Japanese Patent Publication No. 57-41491. Aromatic polyimides are known, but the polyimides do not have sufficient adhesion (adhesion) with flexible substrates, so the substrates need to be pre-treated with an adhesion promoter or dissolved in an organic polar solvent. However, since the solubility in these solvents is usually as low as about 10 to 20% by weight, there is a problem that the electric insulation is insufficient when used as it is. Further, when an aromatic polyimide soluble in a known organic solvent is used as a coating material, the aromatic is considerably rigid, has insufficient flexibility and is inferior in flexibility, so that the warp becomes large. There is a problem that it is difficult to position the flexible circuit board manufactured by mounting at the time of mounting, or stress is applied after connecting to a liquid crystal or the like, and eventually, the flexible circuit board is not functional. In addition, when polyimide is used, there is a problem that the adhesion becomes insufficient, the erosion by the tin plating solution is large, and the insulating property is deteriorated.

For this reason, the combination of a conventionally known polyimide film and a coating material satisfies the demands of a flexible circuit board such as high density, high productivity, uniform quality and low cost. It is difficult.

[0009]

SUMMARY OF THE INVENTION An object of the present invention is to provide a flexible circuit board, particularly for TAB applications.
An object of the present invention is to provide a flexible circuit board in which problems in running stability during processing, high-density patterning, alignment during semiconductor mounting, and insulation of a coat layer are improved.

[0010]

According to the present invention, there is provided a polyimide comprising biphenyltetracarboxylic dianhydride or a derivative thereof and phenylenediamine as main components, a thickness of 5-150 μm, and a tensile modulus of elasticity. But,
750-13 when the thickness is 5 μm or more and less than 50 μm
650-1100 kg / mm 2 when the thickness is 50 μm or more and less than 100 μm, and 550 when the thickness is more than 100 μm and 150 μm or less.
-1100 kg / mm 2, elongation of 45-90% and tear propagation resistance (Elmendorf) of 350-1500 when the thickness is 5 μm or more and less than 50 μm.
g / mm, and when the thickness is 50 μm or more and 150 μm or less, a circuit is formed after providing a conductor directly or via an adhesive layer on at least one surface of an aromatic polyimide film having a thickness of 550-1500 g / mm. Then, an insulating coating material is applied thereon and heated and dried to a thickness of 5 to 50 μm.
And a warp (radius of curvature) of 25 m
m or more, erosion by tin plating solution (tin digging) is 250
mm or less.

[0011] Further, the present invention is characterized in that the thickness is 5 to 150 μm.
The tensile modulus is 750-1300 kg / mm 2 when the thickness is 5 μm or more and less than 50 μm, and 650-110 when the thickness is 50 μm or more and less than 100 μm.
0 kg / mm2, thickness greater than 100 μm and 150
When the thickness is 5 μm or less, the elongation is 45-90%, and the tear propagation resistance (Elmendorf) is 350-1500 g / mm when the thickness is 5 μm or more and less than 50 μm. Is 50μ
550 to 1500 g / m
mm and the coefficient of linear expansion is 5-25 × 10 −6 cm / cm.
/ C and a conductor is provided directly or via an adhesive layer on at least one surface of an aromatic polyimide film having a heat shrinkage of 0.002-0.4%, and then a circuit is formed. A coating layer having a thickness of 5 to 50 μm is formed by applying an insulating coating material on the substrate and drying by heating. The warpage (radius of curvature) is 25 mm or more, and the erosion (tin digging) by the tin plating solution is prevented. The present invention relates to a flexible circuit board having a length of 250 mm or less.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be listed below. 1) The coefficient of linear expansion of the aromatic polyimide film is 5-25
× 10 −6 cm / cm / ° C. with a heat shrinkage of 0.00
The flexible circuit board described above, which is 2-0.4%. 2) The specific tear resistance of the aromatic polyimide film is 14-
The above flexible circuit board having a weight of 25 kg / 20 mm / 10 μm. 3) The above flexible circuit board, wherein the aromatic polyimide film contains 0.1-5% by weight of an inorganic filler. 4) The flexible circuit board as described above, wherein the adhesive is a polyimide-based thermoplastic adhesive or a polyimide-based thermosetting adhesive. 5) The flexible circuit board as described above, wherein the coating layer has an erosion (tin digging) by a tin plating solution of 150 mm or less.

In the present invention, the biphenyltetracarboxylic acid component includes 2,3,3 ′, 4′-biphenyltetracarboxylic acid, 3,3 ′, 4,4′-biphenyltetracarboxylic acid, halides thereof, Their dianhydrides or their esters can be used, and among them, 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride is preferably used. Examples of the aromatic tetracarboxylic acid component that can be used in combination with the biphenyltetracarboxylic acid component include pyromellitic dianhydride. When pyromellitic dianhydride is used in combination, the content is preferably 50 mol% or less in the tetracarboxylic acid component.

Other aromatic tetracarboxylic acid components may be used as long as the effects of the present invention are not impaired. Such aromatic tetracarboxylic acid components include 3,3 ′,
4,4′-benzophenonetetracarboxylic dianhydride,
2,2 ', 3,3'-benzophenonetetracarboxylic dianhydride, 2,2-bis (3,4-dicarboxyphenyl) propane dianhydride, 2,2-bis (2,3-dicarboxyphenyl ) Propane dianhydride, bis (3,4-dicarboxyphenyl) ether dianhydride, bis (2,3
-Dicarboxyphenyl) ether dianhydride, 2,3
6,7-naphthalenetetracarboxylic dianhydride, 1,
4,5,8-naphthalenetetracarboxylic dianhydride,
2,2-bis (3,4-dicarboxyphenyl) -1,
1,1,3,3,3-hexafluoropropane dianhydride, 2,2-bis (2,3-dicarboxyphenyl)
Examples thereof include 1,1,1,3,3,3-hexafluoropropane dianhydride.

The phenylenediamine used in the present invention may be any of o-phenylenediamine, m-phenylenediamine and p-phenylenediamine. Other aromatic diamines may be used as long as the effects of the present invention are not impaired. Such aromatic diamine components include diaminodiphenyl ether, 4,4′-
Diaminodiphenylpropane, 4,4′-diaminodiphenylethane, 4,4′-diaminodiphenylmethane,
Bis [4- (4-aminophenoxy) phenyl] propane, 2,2′-bis [4- (aminophenoxy) phenyl] 1,1,1,3,3,3-hexafluoropropane, bis [4- ( 4-aminophenoxy) phenyl] ether and the like.

In the present invention, the aromatic polyimide film has a thickness of 5-150 μm, preferably 5-150 μm.
It is 100 μm, particularly preferably 10-75 μm. When the thickness of the aromatic polyimide film is smaller than the lower limit, the self-supporting property is low. When the thickness is larger than the upper limit, a large cost is required for production. If the values of the tensile modulus, elongation, and tear propagation resistance (Elmendorf) of the aromatic polyimide film are out of the above ranges, the object of the present invention cannot be achieved. Further, when the linear expansion coefficient and the heat shrinkage ratio of the aromatic polyimide film, and the specific edge resistance are within the above ranges, the dimensional stability and handling under various environments are good, and the conductor ( For example, a problem is less likely to occur when bonding with a copper foil).

The aromatic polyimide film according to the present invention can be manufactured, for example, as follows.
Preferably, first, the biphenyltetracarboxylic acid and phenylenediamine, preferably paraphenylenediamine, are dissolved in an organic polar solvent usually used for producing a polyimide such as N, N-dimethylacetamide or N-methyl-2-pyrrolidone. Polymerization is preferably carried out at 10-80 ° C for 1-30 hours, and the logarithmic viscosity of the polymer (measuring temperature: 30 ° C, concentration: 0.5 g / 100 ml solvent, solvent: N-methyl-2)
-Pyrrolidone) 0.1-5, polymer concentration 15-2
5% by weight, and the rotational viscosity (30 ° C.) is 500-450.
A polyamic acid (imidation ratio: 5% or less) solution having 0 poise is obtained.

Then, for example, 1,2-dimethylimidazole is preferably added to the polyamic acid solution obtained as described above, in particular, in an amount of 0.005-2 times equivalent to the amic acid unit of the polyamic acid. , Preferably 0.005-
0.8 equivalent, especially about 0.02-0.8 equivalent is contained. A part of 1,2-dimethylimidazole is converted to imidazole, benzimidazole, N-methylimidazole, N-benzyl-2-methylimidazole, 2-methylimidazole, 2-ethyl -4-methylimidazo-
, 5-methylbenzimidazole, isoquinoline,
It may be replaced with 3,5-dimethylpyridine, 3,4-dimethylpyridine, 2,5-dimethylpyridine, 2,4-dimethylpyridine, 4-n-propylpyridine or the like.

In the above-mentioned polyamic acid solution, a phosphorus compound is added preferably in an amount of 0.01-5 parts by weight, particularly 0.01-3 parts by weight, especially 0.01-1 part by weight, per 100 parts by weight of the polyamic acid. An organic phosphorus compound, preferably a (poly) phosphate ester, an amine salt of a phosphate ester or an inorganic phosphorus compound is added in a ratio of parts by weight, and more preferably an inorganic filler, particularly 100 parts by weight of polyamic acid, is added. 0.1-3 parts by weight of colloidal silica, silicon nitride, talc, titanium oxide, calcium phosphate (preferably having an average particle size of 0.005-5 μm, particularly 0.005-2 μm
m) is added to obtain a polyimide precursor solution composition.

This polyimide precursor solution composition is continuously cast on a glass or metal support having a smooth surface to form a thin film of the solution, and when the thin film is dried, the drying conditions To adjust the temperature: 100-200
C., time: 1 to 30 minutes after drying, the solidified film has a volatile content of about 30 to 50% by weight and an imidization rate of about 5 to 80% in the solidified film. A solidified film is formed, and the solidified film is peeled from the support surface. The solidified film is further dried under controlled drying conditions to obtain a temperature of room temperature (25 ° C.)-250.
C., Time: A drying step of drying for about 0.5 to 30 minutes may be added. By holding both edges in the width direction of the solidified film and maintaining the stretched state in at least a part of these drying steps, the width direction (TD) and both directions (MD, T
You may stretch a little to D).

Next, after applying or spraying a surface treatment liquid containing a known surface treatment agent such as an aminosilane type, an epoxysilane type or a titanate type on both surfaces of the solidified film, the film can be further dried. As surface treatment agents, γ-aminopropyl-triethoxysilane, N-
β- (aminoethyl) -γ-aminopropyl-triethoxysilane, N- (aminocarbonyl) -γ-aminopropyl-triethoxysilane, N- [β- (phenylamino) -ethyl] -γ-aminopropyl- Aminosilanes such as triethoxysilane, N-phenyl-γ-aminopropyl-triethoxysilane, γ-phenylaminopropyltrimethoxysilane, β- (3,4-epoxycyclohexyl) -ethyl-trimethoxysilane, γ
-Epoxy silanes such as glycidoxypropyl-trimethoxysilane, isopropyl-tricumylphenyl-titanate, dicumylphenyl-oxyacetate-
A heat-resistant surface treating agent such as titanate such as titanate can be used. The surface treatment liquid is 0.5 parts of the above surface treatment agent.
It can be used as a solution of an organic polar solvent such as a lower alcohol or amide solvent containing -50% by weight. The surface treatment liquid is preferably applied uniformly using a gravure coating method, a silk screen, a dipping method or the like to form a thin layer.

The aromatic polyimide film of the present invention can be obtained by heating the solidified film to a high temperature, preferably in a curing furnace, to complete the drying and imidization. That is, the solidified film obtained as described above is further dried, if necessary, and in a state where both edges in the width direction of the dried film are gripped, the maximum heating temperature in a curing furnace: about 400 to 500 ° C. Especially 47
The dried film is heated and dried and imidized under the condition that a temperature of about 5 to 500 ° C. is 0.5 to 30 minutes,
A long aromatic polyimide film can be suitably produced by completing imidization at a residual volatile matter amount of about 0.4% by weight or less. After the curing step, one or both surfaces of the aromatic polyimide film are subjected to alkali treatment (for example, after immersion in an aqueous alkali solution such as sodium hydroxide, acid washing, water washing, and drying), and then the surface treatment liquid is applied and heated. The surface of the film can be similarly surface-treated by drying. The aromatic polyimide film obtained as described above is heated under a low tension or no tension at a temperature of about 200 to 400 ° C., subjected to a stress relaxation treatment, and wound up.

The above-mentioned aromatic polyimide film is obtained by using a polyimide precursor solution obtained by adding 1,2-dimethylimidazole or the like to the above-mentioned polyamic acid and forming a long film by a solution casting method. , Tensile modulus, elongation and tear propagation resistance (Elmendorf) can be set to the values specified in the present invention. When the thickness of the aromatic polyimide film is larger than 125 μm, preferably after laminating two or more polyimide precursor solutions by co-extrusion, the aromatic polyimide film having a large thickness is similarly dried and imidized. Can be manufactured.

A heat-fusible polyimide (preferably, the glass transition temperature (Tg) of the polyimide is 180-26) on one or both sides of the aromatic polyimide film.
0 ° C. The self-supporting film is a heat-fusible polyimide precursor solution which is a solution of an organic polar solvent containing a polyamic acid to give the above (optionally, 1,2-dimethylimidazole or the like may be added). Or heat-fusible thin-layer polyimide by laminating it by coextrusion for a thin layer, and then drying and imidizing it (preferably at a maximum heating temperature of about 300 to 450 ° C.). (Preferably 0.1-10 μm, especially 0.2-
(Preferably 5 μm in thickness)).

As such a heat-fusible polyimide,
Low modulus [preferably 1-250 kg / mm 2 (25
C))] is a combination of an aromatic tetracarboxylic acid component giving a polyimide and an aromatic diamine having three or more benzene rings, and a polyimide giving the above glass transition temperature is preferable. For example, 2,3,3 ', A preferred example is a combination of 4'-biphenyltetracarboxylic dianhydride and 1,3-bis (4-aminophenoxy) benzene (TPER). The heat-fusible polyimide of this thin layer has a thickness of 0.1-0.1 mm of the aromatic polyimide film of the present invention.
It is preferably about 25%, especially about 0.5-10%.

Alternatively, an aluminum compound (for example,
Aluminum hydroxide compounds such as aluminum hydroxide and aluminum triacetyl acetate), tin compounds (for example, dibutyltin acetate, bis (tributyltin) oxide, tetrabutyltin, etc.), bismuth compounds or antimony compounds. A solution dissolved in a solvent (for example, an aliphatic or aromatic hydrocarbon, an alcohol solvent, a ketone solvent, an ether solvent, an amide solvent, etc.) may be applied. In this case, metal components such as aluminum are contained in the film in an amount of 1 to 10000 ppm, particularly 1 to 1 ppm.
It is preferably contained at a rate of -1000 ppm.

In the present invention, the aromatic polyimide film is preferably treated as it is or with a surface treating agent. If necessary, corona discharge treatment, low-temperature (ie, vacuum) or normal-pressure plasma discharge treatment, ultraviolet irradiation treatment, After performing the surface treatment by flame treatment, an adhesive layer can be provided by applying an adhesive or laminating a film of the adhesive.

For example, a metal foil such as a copper foil is applied to the aromatic polyimide film of the present invention via a thermosetting adhesive, preferably a thermosetting polyimide-based adhesive or a thermoplastic adhesive such as a thermoplastic polyimide resin. And laminated.
Alternatively, a conductor layer may be directly laminated on the aromatic polyimide film. For example, the conductor layer can be directly laminated by a vapor deposition method, a sputtering method, or a plating method.

The conductor in the present invention is preferably a copper foil. The copper foil is an electrolytic copper foil or a rolled copper foil, and a copper foil having a tensile strength of 17 kg / mm 2 or more is preferable. The thickness of the copper foil is preferably 8-50 μm.

In the present invention, a circuit is formed after a conductor is provided directly on the aromatic polyimide film or by laminating a conductor via an adhesive. Further, in the present invention, a precursor solution of the thermoplastic polyimide is cast and dried on a conductor such as the copper foil, and a polyimide precursor solution composition that gives the aromatic polyimide film thereon is cast. A circuit may be formed after a conductor is provided on the aromatic polyimide film via the thermoplastic polyimide by drying and heating treatment.

A circuit is formed on a conductor by preparing a conductive substrate by providing a conductor directly on an aromatic polyimide film or via an adhesive, and then, for example, etching a resist on the surface of the conductor with a circuit pattern. After forming a wiring pattern of an etching resist which protects the surface of the conductor at the portion where the wiring pattern is formed by printing on the wiring pattern, an etching solution is used by a method known per se. Then, the conductor at the portion where the wiring is not formed is removed by etching, and preferably, the etching resist is removed.

In the present invention, a circuit is formed as described above, and an insulating coating material is applied on the upper surface of a circuit pattern (wiring pattern) of the circuit board (wiring board), and is heated and dried. And a warp formed by forming a coat layer having a thickness of 5 to 50 μm is not less than 25 mm, preferably not less than 100 mm, and erosion by a tin plating solution is not more than 250 μm, especially not more than 150 μm. The above-described flexible wiring board is manufactured.

The above-mentioned insulating coating layer is formed by directly coating the upper surface of the circuit pattern or by treating it with a surface treating agent such as a silane coupling agent, and then spin-coating a coating material (liquid material). It is applied to a uniform thickness, preferably 1 to 100 μm, by a coating method using a machine, a dispenser or a printing machine, and dried by heating (preferably at 50 to 180 ° C., about 1 to 100 μm).
(Under normal pressure or reduced pressure for 150 minutes).

As the insulating coating material in the present invention, for example, the following polyimidesiloxane-based coating material solution composition can be preferably mentioned. The above-mentioned polyimide siloxane-based coating material is preferably prepared by adding (a) 45-90 mol% of diaminopolysiloxane in aromatic tetracarboxylic dianhydride and diamine and the remainder of aromatic diamine (particularly, In an aromatic diamine, part or all thereof, preferably 0.5
An organic polar solvent-soluble polyimide siloxane 100 obtained by polymerizing and imidizing -40 mol% of an aromatic diamine having a reactive group with an epoxy group on a benzene ring.
(B) 1-250 parts by weight of epoxy resin, (c) 2-150 parts by weight of inorganic fine particles (particularly, talc, barium sulfate or mica), and if necessary, a pigment (for example, phthalocyanine resin). And a polyimide siloxane composition containing an antifoaming agent.

Examples of the aromatic tetracarboxylic dianhydride include 2,3,3 ', 4'-biphenyltetracarboxylic dianhydride and 3,3', 4,4'-biphenyltetracarboxylic dianhydride. And 3,3 ′, 4,4′-diphenylethertetracarboxylic dianhydride.

The diaminopolysiloxane has the formula H2NR-[-Si (R1R1) O] n-Si (R1R1)
-R-NH2 (where R represents a divalent hydrocarbon or phenyl group, R1 independently represents an alkyl group having 1 to 3 carbon atoms or a phenyl group, and n represents a number of 3 to 30). It is the diamine shown.

The aromatic diamine is selected from 3,
3'-dihydroxy-4,4'-diaminobiphenyl, bis (3-carboxy, 4-aminophenyl) methane (hereinafter sometimes abbreviated as MBAA), bis (3-hydroxy, 4-aminophenyl) methane,
3,5-diaminobenzoic acid (hereinafter sometimes abbreviated as DABA), 2,2-bis [4- (4-aminophenoxy) phenyl] propane (hereinafter sometimes abbreviated as BAPP), 1,4- (4-aminophenoxy)
Benzene and the like can be mentioned.

The epoxy resin has an epoxy equivalent of about 100-1000 and a molecular weight of 40
A liquid or solid epoxy resin of about 0-5000 is preferred. For example, bisphenol A type epoxy resin, bisphenol F type epoxy resin (specifically, Epicoat 806, Epicoat 825, etc., manufactured by Yuka Shell Co., Ltd.), phenol novolak type epoxy resin, glycidyl ether Examples thereof include a tell-type epoxy resin, a glycidyl ester-type epoxy resin, and a glycidylamine-type epoxy resin. These may be used alone or in combination. Further, an epoxy resin curing catalyst such as hydrazines, imidazoles and phthalic anhydride may be used together with the epoxy resin.

In the above polyimide siloxane composition, N, N-dimethylacetamide, N, N-diethylacetamide, N, N-dimethylformamide, N-methyl-2-pyrrolidone, 2-methoxyethyl ether Organic solvents having a boiling point of 140 ° C. or higher, particularly 180 ° C. or higher, such as ter (diglyme) and tri (ethylene glycol) dimethyl ether (triglyme), are used. Polyimide siloxane has a logarithmic viscosity (measured concentration: 0). 0.5 g / 100 ml, solvent: N-methyl-2-pyrrolidone, measurement temperature: 30 ° C.) is preferably 0.1-2. Further, the solid content concentration in the polyimide siloxane composition is preferably 10 to 60% by weight. Silicon-based thickening components such as Aerosil manufactured by Nippon Aerosil Co., Ltd.
It is preferable to add 1 to 50 parts by weight to 1 part by weight.

[0040]

Embodiments of the present invention will be described below. In each of the following examples, the physical properties of the polyimide film were measured by the following methods. The following measured values are measured at 25 ° C. unless otherwise specified.

Elongation: Measured according to ASTM D882-83 (MD) Tensile Modulus: Measured according to ASTM D882-83 (MD) Tear Propagation Resistance (Elmendorf): ASTM D19
Measured according to 22-67 (MD) Tensile strength: Measured according to ASTM D882-83 (M
D) Heat shrinkage: measured according to JIS C2318 (200
℃) Dielectric breakdown voltage: Measured according to JIS C2318

The crack resistance (or specific crack resistance) is J
It means the average value of the tear resistance (or the specific tear resistance) of the samples (5 pieces) measured according to IS C2318.
Specifically, the upper thickness of the constant speed tension type tensile tester is 1.00.
The center line of the V-shaped notch plate test fixture of ± 0.05 mm is aligned with the center line of the upper grip, and the handle is attached so that the gap between the cut top and the lower grip is about 30 mm. A test piece of about 20 mm in width and about 200 mm in length is passed through the hole of the metal fittings, folded into two parts, clamped by the lower grip of the tester, and pulled at a speed of about 200 mm per minute,
The force at the time of tearing is called end tear resistance. Five test pieces were taken from the longitudinal direction and the transverse direction over the entire width, respectively, and the average value of the end crack resistance was determined, which is shown as the end crack resistance value. The specific edge tear resistance indicates an edge tear resistance per film thickness (10 μm conversion).

Measurement of linear expansion coefficient (50-200 ° C.): 30
A sample that was heated at 0 ° C. for 30 minutes to relax the stress was applied to a TMA device (tensile mode, 2 g load, sample length 10 mm, 20 ° C.).
/ Min) Tear strength: 5 cm using a razor blade on one side of a film cut into a square of 7.5 cm × 7.5 cm.
A notch of length was made. The load at the time of pulling at both sides of the cut with a tensile tester at a speed of 200 mm / min was measured, and the load at which tearing occurred was defined as tear strength (g). Bending resistance (MIT): Measured in accordance with ASTM D2176 (MD) Punching property: Good when there is no problem such as buckling, deformation or cutting when punching into a rectangular shape by punching, and with some problems Somewhat defective, those with problems were regarded as defective.

Adhesive strength: The 180 ° peel strength of the copper clad board was measured at a tensile speed of 50 mm / min. Solder heat resistance (Solder resistance test): 50μm thick polyimide spacer on glossy surface of 35μm thick electrolytic copper foil
Is placed, and a coating material (polyimide siloxane composition) is cast, and dried by heating at 80 ° C. for 30 minutes and at 160 ° C. for 60 minutes to form a polyimide siloxane coating material layer. 3 × 3c copper foil with polyimide siloxane coat material layer
m, and a rosin-based flux (SUNFLUX SF-270, manufactured by Sanwa Chemical Industry Co., Ltd.) was applied on the coating material layer. Then, the coating material layer was placed in a molten solder bath at 240 ° C. and 260 ° C. for 30 seconds. The surfaces were brought into contact, and after cooling, the presence or absence of blisters on the coating material layer surface was observed. The temperature without any blistering is shown as the solder heat resistance temperature.

Warpage (radius of curvature): The radius of curvature of the circuit board from which the conductor was removed was measured in accordance with JIS-C-6481. Erosion by tin plating solution (submersion in tin plating solution): After immersing the flexible circuit board in the plating solution, the degree of penetration of the plating solution at the interface between the coating material and the conductor was measured. The plating solution used was an electroless tin plating solution (trade name: Tileposit LT-34) manufactured by Sibre Fast East Co., Ltd.
It is indicated by the dipping amount (mm) of the tin plating solution when immersed under the specified conditions.

Example 1 To 100 parts by weight of N, N-dimethylacetamide, 5.897 parts by weight of p-phenylenediamine and 3,3 ',
4,4'-biphenyltetracarboxylic dianhydride
After adding 019 parts by weight, the mixture was stirred at 40 ° C. for 3 hours under a nitrogen stream to cause a polymerization reaction, whereby the polymer concentration was 18% by weight and the logarithmic viscosity of the polymer (measuring temperature: 30 ° C., concentration: 0.5 g / 1)
00 ml solvent, solvent: N, N-dimethylacetamide)
Was 1.3, and a polyamic acid solution having a solution viscosity of 1800 poise (30 ° C., rotational viscometer) was obtained. In this polyamic acid solution, monostearyl phosphate triethanolamine salt in a ratio of 0.1 part by weight to 100 parts by weight of the polyamic acid and a ratio of 0.5 part by weight (based on solid content)
Was added and colloidal silica having an average particle size of 0.08 μm was added and uniformly mixed to obtain a polyamic acid solution composition. Further, to this polyamic acid solution composition, 2.39 parts by weight of 1,2-dimethylimidazole (0.1 equivalent equivalent to the polyamic acid unit) was added to 100 parts by weight of the polyamic acid, and the mixture was added at 40 ° C. For 2 hours to obtain a polyimide precursor solution composition.

The polyimide precursor solution composition was continuously extruded from a slit of a T-die to form a thin film on a smooth metal support. After heating this thin film at 140 ° C. for 20 minutes, it was peeled from the support to form a long solidified film. The film was continuously passed through a heating furnace with both ends of the film restrained. At this time, the residence time in the heating furnace is set to 1
The maximum heating temperature in the heating furnace was set to 480 ° C. for 3 minutes. Thus, a long aromatic polyimide film having a thickness of 50 μm was obtained.

Preparation of Polyimide Siloxane Solution Composition as Coating Material In a glass flask, 1,808 parts by weight of 2,3,3 ′, 4′-biphenyltetracarboxylic dianhydride and 4000 parts by weight of triglyme were charged. After dissolving with stirring, α, ω-bis (3-aminopropyl) polydimethylsiloxane (X-22-161A manufactured by Shin-Etsu Silicon Co., Ltd.)
(S, n = 9) (Diaminopolysiloxane) 4692 parts by weight and triglyme 1600 parts by weight were added and uniformly dissolved, kept under a nitrogen atmosphere, and further added with MBAA.
After adding 62.20 parts by weight and 8000 parts by weight of triglyme, the reaction temperature was raised to 180 ° C., and the mixture was further reacted for 10 hours to prepare a polyimidesiloxane solution. This polyimide siloxane solution has a polyimide siloxane concentration of 5
1.0 wt%, solution viscosity was 25 poise. Also,
The polyimide siloxane in this polyimide siloxane solution has a diaminopolysiloxane ratio of 8 in the diamine.
5 mol%, the ratio of MBAA was 15 mol%, the logarithmic viscosity was 0.18, and the imidation ratio was substantially 100%. Solution 1 in which triglyme was added to this polyimide siloxane solution to adjust the polymer solids concentration to 50% by weight
6 parts by weight of epoxy resin (Epicoat 157-70, manufactured by Yuka Shell Co., Ltd.), 1 part by weight of phthalocyanine line as a pigment, and 0.18 parts of 2-ethyl, 4-methylimidazole as a catalyst. Parts by weight and phthalic anhydride.
06 parts by weight, Aerosil (average particle size: 0.01 μm)
9.0 parts by weight, barium sulfate (average particle size: 0.3 μm)
22.4 parts by weight, talc (average particle size 1.8 μm) 5.6
Parts by weight, 5.6 parts by weight of mica (average particle size: 2.6 μm), and 2.8 parts by weight of a silicone-based defoamer were charged at room temperature (2 parts by weight).
(5 ° C.), stirred for 2 hours, and uniformly mixed polyimidesiloxane solution composition part (solution viscosity: 600 poise)
I got

Production of Polyimidesiloxane-Epoxy Resin Adhesive In the production of the above-mentioned polyimidesiloxane solution, bis (3-carboxy, 4-aminophenyl) methane (MB
Using AA) and BAPP, changing the proportion of diamine, the proportion of diaminopolysiloxane
Mol%, the proportion of BAPP is 45 mol%, the proportion of MBAA is 5 mol%, the logarithmic viscosity is 0.41, the imidization ratio is substantially 100%, and the elastic modulus of the film is 7%.
A polyimide siloxane solution of 5 kg / mm 2 was obtained and poured into methanol to obtain a polyimide siloxane powder. Solvent: 500 parts by weight of tetrahydrofuran (THF), 100 parts by weight of the above-mentioned polyimide siloxane, 43 parts by weight of an epoxy resin (EP807 manufactured by Yuka Shell Co., Ltd.), phenol-
33 parts by weight of a lunovolak resin (manufactured by Meiwa Kasei Co., Ltd.) and 0.2 parts by weight of a curing catalyst (2-phenylimidazole) were mixed to obtain an adhesive composition. This adhesive composition was treated with polyethylene terephthalate (PE).
T) It was applied on a film (thickness: 25 μm), dried, and covered with a PET film on the adhesive side. The thickness of the adhesive is 12 μm. The obtained adhesive sheet was slit to obtain a polyimidesiloxane-epoxy resin adhesive tape having a width of 26 mm.

Production of Flexible Circuit Board The above polyimide film was slit to form a 35 mm wide tape, and a 26 mm wide polyimide siloxane-epoxy resin adhesive tape (20 μm thick) was formed on one side.
m, thermosetting type), and the laminate was laminated at 120 ° C. at the center of the polyimide tape to produce a polyimide tape with an adhesive. A sprocket hole and a device hole are punched in the polyimide tape with the adhesive, and an electrolytic copper foil (35 μm, tensile strength 40 kg / mm) is formed.
2) was bonded at 130 ° C., and the adhesive was heated at 100 ° C. for 2 hours, at 120 ° C. for 1 hour, and at 180 ° C. for 6 hours to cure the adhesive. Subsequently, patterning was performed on the copper-clad board according to a conventional method, followed by etching, washing and drying steps, and then applying the above-mentioned polyimide siloxane composition as a coating material. By heating and drying at 80 ° C. for 30 minutes and at 160 ° C. for 60 minutes, a flexible coat layer (thickness: 30 μm) made of polyimide siloxane was formed to produce a flexible circuit board. The evaluation results are shown below.

1) About film Film thickness: 50 μm Tensile modulus: 780 kg / mm 2 Elongation: 60% Tear propagation resistance (Elmendorf): 830 g / mm Tensile strength: 54 kg / mm 2 Heat shrinkage: 0.05% Dielectric breakdown voltage: 9.5 kv Tear resistance value: 82 kg / 20 mm Specific end resistance value: 16.4 kg / 20 mm / 10 μm Linear expansion coefficient: 1.7 × 10 −5 cm / cm / ° C. Tear strength: 26 g Number of times of bending resistance (× 10 4 Times):> 10 Punching property: good

2) Regarding the circuit board Adhesive strength: 1.4 kg / cm Solder heat resistance (260 ° C.): good Warpage (radius of curvature: mm): 130 mm Erosion of tin plating (mm): 95 mm Overall evaluation: good

Example 2 A long aromatic polyimide having a thickness of 50 μm was obtained in the same manner as in Example 1 except that the heating time on the support was 13 minutes and the residence time in the heating furnace was 8.6 minutes. A film and then a flexible circuit board were obtained. The evaluation results are shown below.

1) Film Film thickness: 50 μm Tensile modulus: 790 kg / mm 2 Elongation: 56% Tear propagation resistance (Elmendorf): 820 g / mm Tensile strength: 48 kg / mm 2 Heat shrinkage: 0.05% Dielectric breakdown voltage: 9.4 kv Tear resistance value: 82 kg / 20 mm Specific end resistance value: 16.4 kg / 20 mm / 10 μm Linear expansion coefficient: 1.7 × 10 −5 cm / cm / ° C. Tear strength: 28 g Number of times of bending resistance (× 10 4 Times):> 10 Punching property: good

2) Regarding the circuit board Adhesive strength: 1.4 kg / cm Solder heat resistance (260 ° C.): good Sledding (radius of curvature mm): 150 mm Erosion of tin plating (mm): 100 mm Overall evaluation: good

Example 3 A long aromatic polyimide having a thickness of 50 μm was obtained in the same manner as in Example 1 except that the heating time on the support was 10 minutes and the residence time in the heating furnace was 6.5 minutes. A film and then a flexible circuit board were obtained. The evaluation results are shown below.

1) About film Film thickness: 50 μm Tensile modulus: 810 kg / mm 2 Elongation: 54% Tear propagation resistance (Elmendorf): 760 g / mm Tensile strength: 49 kg / mm 2 Heat shrinkage: 0.06% Dielectric breakdown voltage: 9.5 kv Tear resistance value: 83 kg / 20 mm Specific end resistance value: 16.6 kg / 20 mm / 10 μm Linear expansion coefficient: 1.6 × 10 −5 cm / cm / ° C. Tear strength: 25 g Number of flexing resistance (× 10 4 Times):> 10 Punching property: good

2) Regarding the circuit board Adhesive strength: 1.3 kg / cm Solder heat resistance (260 ° C.): good Warpage (radius of curvature: mm): 135 mm Erosion of tin plating (mm): 103 mm Overall evaluation: good

[0059]

Since the present invention is configured as described above, it has the following effects. In the flexible circuit board of the present invention, the substrate film has heat resistance,
Good dimensional stability and processability, good operability and running stability during processing, enabling high-density patterning, easy positioning during semiconductor mounting, insulation of coat layer The properties are good.

 ──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Seiji Ishikawa 8-1 Goi-minamikaigan, Ichihara-shi, Chiba Ube Industries, Ltd. Polymer Research Laboratory (72) Inventor Hiroshi Anno 8th Goi-minamikaigan, Ichihara-shi, Chiba F1 term in Ube Industries Co., Ltd. Polymer Research Laboratory 4F071 AA60 AE17 AF20 AF61 AF62 AH13 BB06 BC01 BC12 4J043 PA02 PA04 QB15 QB26 RA35 SA06 SB01 SB03 TA22 TB01 TB03 UA121 UA131 UA132 UA151 UA262 UB01 UB121 UB121 UB121 UB131 UB141 UB152 VA021 VA031 VA041 XA16 XA19 YA06 ZA32 ZA46 ZB11 ZB50 5G305 AA06 AB01 AB17 AB34 AB36 AB40 BA12 BA18 BA26 CA21 CA25 CC02 CC04 CC11 CD01

Claims (6)

[Claims] 1. A polyimide comprising biphenyltetracarboxylic dianhydride or a derivative thereof and phenylenediamine as main components, having a thickness of 5 to 150 μm and a tensile modulus of 5 to 50 μm. Is 750-1300 kg / mm2 and the thickness is 5
650-1100 when 0 μm or more and less than 100 μm
kg / mm2, thickness greater than 100μm and 150μ
m, the elongation is 45-90%, and the tear propagation resistance (Elmendorf) is 350-1500 g / mm when the thickness is 5 μm or more and less than 50 μm. Is 50μ
550 to 1500 g / m
After providing a conductor directly or via an adhesive layer on at least one side of an aromatic polyimide film having a thickness of 1 mm, a circuit is formed, an insulating coating material is applied thereon, and the film is dried by heating and drying. A flexible circuit board having a coating layer of 5 to 50 μm, having a warpage (radius of curvature) of 25 mm or more and an erosion (tin digging) by a tin plating solution of 250 mm or less. 2. The flexible circuit board according to claim 1, wherein the aromatic polyimide film has a coefficient of linear expansion of 5-25.times.10@-6 cm / cm / DEG C. and a heat shrinkage of 0.002-0.4%. . 3. The flexible circuit board according to claim 1, wherein the aromatic polyimide film contains 0.1 to 5% by weight of an inorganic filler. 4. The flexible circuit board according to claim 1, wherein the adhesive is a polyimide-based thermoplastic adhesive or a polyimide-based thermosetting adhesive. 5. The flexible circuit board according to claim 1, wherein the coating layer has an erosion by tin plating solution (tin digging) of 150 mm or less. 6. A film having a thickness of 5 to 150 μm and a tensile modulus of elasticity of 750 when the thickness is 5 μm or more and less than 50 μm.
-1300kg / mm2, thickness 50μm or more and 100
In the case of less than μm, it is 650-1100 kg / mm 2,
When the thickness is more than 100 μm and 150 μm or less, it is 550-1100 kg / mm 2 and the elongation is 45-9.
0% and tear propagation resistance (Elmendorf)
However, when the thickness is 5 μm or more and less than 50 μm, 350-
When the thickness is 1500 g / mm and the thickness is 50 μm or more and 150 μm or less, it is 550-1500 g / mm, the coefficient of linear expansion is 5-25 × 10 −6 cm / cm / ° C., and the heat shrinkage is 0.002-0. A conductor is provided directly or through an adhesive layer on at least one side of an aromatic polyimide film of 0.4%, a circuit is formed, an insulating coating material is applied thereon, and then heated and dried. A coat layer having a thickness of 5 to 50 μm is formed, and a warp (radius of curvature) is 25 mm.
Above, erosion by tin plating solution (tin digging) is 250m
m or less.