JPH0888460A - Method for manufacturing wiring board with flexed part - Google Patents

Abstract

PURPOSE: To easily manufacture a wiring board with a flexed part with improved heat resistance adhesion property between a flexible base film layer and copper foil corresponding to a flexed part. CONSTITUTION: When forming a copper-clad substrate, polyimidesiloxane solution composition is applied to 'a reverse side 5 (a slit-shaped opening 3) of copper foil' where copper foil is exposed in the slit-shaped opening 3 of base film made of aromatic polyimide and is dried, a flexible base film layer made of polyimidesiloxane is formed on the reverse side of copper foil and a copper-clad substrate is manufactured, and the copper-clad substrate is used to manufacture the wiring board with flexed part by etching operation and the operation for forming a covering layer.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention generally relates to (A) a base film made of an aromatic polyimide partially opening like a slit and the back surface of a copper foil, and the back surface of the copper foil corresponds to a bent portion. Form a copper-clad substrate that is entirely bonded except exposed in the slit-shaped openings, and then (B) polyimide siloxane solution on the back surface of the copper foil that is exposed in slits in the copper-clad substrate. The composition is applied and dried to form a flexible base film layer made of polyimide siloxane, and a copper clad substrate having the flexible base film layer and the aromatic polyimide base film layer continuously and integrally formed is prepared. Then, (C) using the copper-clad substrate, performing a copper etching operation from the surface side of the copper foil, to form a copper wiring pattern including the bent portion wiring formed in the flexible base film layer portion. , (D) Later, protected with a coating layer (overcoating layer), relates to a method of copper wiring patterns to produce a bent portion with a wiring board is protected with a coating layer (an overcoat layer).

[0002]

2. Description of the Related Art Conventionally, as a method of manufacturing a printed wiring board having a bent portion, the bent portion and the circuit surface have been proposed, including the method proposed in JP-A-4-364795 or JP-A-4-364796. Various means such as a film cover lay method of fusing and adhering a film to the film, an ink cover coating method of coating a liquid coating agent, etc. have been proposed, but in the method of manufacturing a wiring board with a bent portion, the bent portion wiring is easily formed. In addition, no suitable industrial method has been proposed as a manufacturing method capable of providing sufficient electrical protection.

In the above-mentioned known method for manufacturing a wiring board with a bent portion, the manufacturing process is extremely complicated, and the bending property of the obtained bent wiring board itself and the insulation of the wiring at the bent portion are high. However, it was difficult to maintain high adhesion between the wiring and the protective layer, and it was difficult to obtain a stable and high-quality wiring board with a bent portion.

That is, in the above-mentioned film coverlay method, it is extremely difficult to accurately position the bent portion wiring and other wiring portions so that the films are superposed and joined, and a gap is formed between the film and the wiring. It was difficult to obtain a wiring board on which a protective film layer having sufficient insulation and adhesion was formed easily. In addition, in the above-mentioned ink cover coating method, since the polymer varnish used as the ink often has curability, there is a problem in its storage stability, and at the same time, the wiring of the bent portion formed by the ink is protected. The film is rigid (a property lacking in flexibility), which has been a problem in terms of chemical resistance, insulation, and flexibility.

[0005]

As a result of intensive studies to overcome the above-mentioned various problems, as a result, the back surface of the copper foil of the wiring board (the portion corresponding to the bent portion, the slit shape of the base film made of aromatic polyimide) (Aperture) is coated with a polyimidesiloxane solution composition and dried to create a wiring board having a base film layer formed of polyimidesiloxane on the back surface of the copper foil in the portion corresponding to the bent portion of the wiring board, and then, If a wiring board is manufactured by a copper etching operation using the wiring board, it is possible to easily industrially manufacture a wiring board with a bent portion having high flexibility and bending resistance. Thus, the present invention has been completed.

[0006]

Means for Solving the Problems The present invention provides (A) an aromatic polyimide base film partially opening in a slit shape and a back surface of a copper foil, wherein the back surface of the copper foil is the slit opening. A copper clad substrate that is bonded to the entire surface except that exposed in the above is formed, and (B) the polyimide siloxane solution composition is applied to the back surface of the copper foil exposed in a slit shape in the copper clad substrate and dried. Then, a copper-clad substrate in which a flexible base film layer made of polyimide siloxane is continuously formed integrally with an aromatic polyimide base film on the back surface of the copper foil exposed in a slit shape, (C ) In the copper clad substrate manufactured as described above, an etching resist is pattern-printed on the surface of the copper foil to form a resist pattern, and then a copper etching operation is performed using an etching agent. Te surface to remove copper foil of the exposed portion to form a copper wiring pattern including the formed flexible base film layer portions bent section lines, (D)
Finally, it relates to a method for producing a wiring board with a bent portion, which comprises removing the etching resist layer if necessary and then forming a flexible coating layer on the copper wiring pattern.

In the present invention, the polyimidesiloxane in the polyimidesiloxane solution composition used in the step (B) is composed of the aromatic tetracarboxylic acid component and the general formula (1).

[0008]

Embedded image

(In the formula, R ₁ represents a divalent hydrocarbon residue, R ₂ independently represents an alkyl group having 1 to 3 carbon atoms or a phenyl group, and n represents an integer of 3 to 30. Of the diaminopolysiloxane represented by the formula (1), and a diamine component containing an aromatic diamine having 2 to 4 benzene rings at a ratio of about 10 to 60 mol%. The above-mentioned method for producing a wiring board with a bent portion, which is a soluble polyimide siloxane obtained by equimolar polymerization and imidization of both components, is particularly preferable.

Hereinafter, the manufacturing method of the present invention will be described in detail with reference to the drawings. FIG. 1 shows the manufacturing method of the present invention.
(A) A plan view showing an example of the copper clad substrate 4 formed in the step, a cross-sectional view taken along the line AA '(horizontal), and a line BB' (vertical).
FIG. FIG. 2 is a (longitudinal) cross-sectional view showing an example of a copper-clad substrate 41 having a flexible base film layer 7 formed by using the copper-clad substrate 4 shown in FIG. 1 in the step (B) of the manufacturing method of the present invention. Is.

FIG. 3 shows a wiring board 42 in which an etching resist pattern 8 is formed using the copper clad board 41 shown in FIG. 2 in the step (C) of the manufacturing method of the present invention [cross-sectional view.
(b)], Intermediate wiring board 43 [cross-sectional view after etching]
(c)] and a resist-removed wiring board 44 [cross-sectional view (d)] from which the resist has been removed, and a flexible coating on the wiring using the resist-removed wiring board 44 in the step (D). A wiring board and each wiring board are illustrated in order to sequentially explain each step for forming a layer and manufacturing the final target wiring board 45 with a bent portion [cross-sectional view (e)] ( (Longitudinal) sectional views (b) to (e).

FIG. 4 shows that in the step (B) of the manufacturing method of the present invention, the copper-clad substrate 41 shown in FIG. 1 is used to form an imidazole adhesion layer on the back surface (slit-shaped opening) of the copper foil [FIG. 4 (f)], and the polyimide siloxane solution composition is applied onto the imidazole adhesion layer on the back surface of the copper foil and dried to form a flexible coating layer on the back surface of the copper foil 47. It is a (longitudinal) sectional view showing an example of [see sectional view (g)].

In the present invention, firstly, (A) the aromatic polyimide base film 1 and the back surface of the copper foil 2 which are partially opened in a slit shape (except the slit-shaped opening 3) The back surface 5 of the foil 2 is exposed), and the copper-clad substrate 4 as shown in FIG. 1 that is integrally bonded is formed, and then (B) the slit-shaped opening 3 of the copper-clad substrate 4 is exposed. The polyimide siloxane solution composition is applied to the entire back surface 5 of the copper foil 2 and dried, and as a result, the flexible base film layer 7 made of polyimide siloxane is formed on the back surface 5 of the copper foil 2 in the slit-shaped openings 3. To form a copper clad substrate 41 as shown in FIG. 2 (a), which is continuously formed integrally with the aromatic polyimide base film layer 1.

As shown in FIG. 1, the wiring board manufactured in the step (A) of the present invention has an aromatic polyimide base film 1 (thickness: about 5 to 200 μm; Aromatic polyimide film base film having a heat-resistant adhesive layer between the copper foil 2 (thickness: 10 to 150 μm) and the back surface of the copper foil 2 (thickness: about 5 to 100 μm, particularly 10 to 50 μm) or without an adhesive. Except for the slit-shaped opening 3, the wiring board 4 may be integrally joined as a whole.

The shape and size of the slit-shaped opening are not particularly limited, but the shape and size are appropriately selected depending on the size and shape of the bent portion in the finally obtained wiring board with a bent portion. I can decide. The slit-shaped opening is, for example,
Width: 0.5 to 30 mm, particularly about 1 to 20 mm, and length: 10 to 500 mm, especially about 20 to 200 mm, like the slit-shaped opening (rectangular opening) 3 shown in FIG. Is preferred.

In the present invention, as the slit-shaped opening, both sides of the slit-shaped opening 3 shown in the (transverse) vertical cross section along the line AA 'in the wiring board 4 as shown in FIG. Without the base film 1 of 1, that is, the base film 1 made of aromatic polyimide
It also includes those that are completely divided into two regions at regular intervals.

In the method of the present invention, the aromatic polyimide base film has a thickness of about 5 to 200 μm, more preferably 10 to 150 μm, and has sufficient flexibility and high strength (tensile strength of about 10 to 10 μm). 50 kg / mm ² ,
Particularly, about 15 to 48 kg / mm ² , and more preferably 20 to 4
A base film having a heat resistance of 6 kg / mm ² ) and formed of a heat-resistant aromatic polyimide used as a base film for flexible printed wiring boards, TAB, etc. is preferable.

Examples of the aromatic polyimide forming the heat resistant base film include, for example, 2,3,3 ', 4'-biphenyltetracarboxylic acid and 3,3', 4,4'-biphenyltetracarboxylic acid. An aromatic tetracarboxylic acid component containing a carboxylic acid, or an acid dianhydride thereof, or a biphenyltetracarboxylic acid such as an acid esterified compound as a main component (50 to 100 mol%), and 4,4′-diphenyl ether diamine,
Aromatic diamine having 1 to 4 (particularly 1 to 2) benzene rings such as 3,4'-diphenyl ether diamine, p-, o- or m-phenylenediamine, and 4,4'-biphenyldiamine as a main component (50-100 mol%, especially 70-1
The aromatic polyimide obtained by polymerizing and imidizing the aromatic diamine component contained therein (00 mol%) in approximately equimolar amounts of the acid component and the diamine component is most suitable.

As the aromatic polyimide, an aromatic tetracarboxylic acid component containing pyromellitic acid as a main component (50 to 100 mol%), and 1 to 4 (particularly 1 to 2) benzene rings described above. An aromatic polyimide obtained by polymerizing and imidizing an aromatic diamine component containing an aromatic diamine as a main component in approximately equimolar amounts can also be suitably mentioned. Further, as the aromatic polyimide, in addition to the above-mentioned biphenyltetracarboxylic acid-based aromatic polyimide, pyromellitic acid-based aromatic polyimide, as an aromatic tetracarboxylic acid component, benzophenonetetracarboxylic acids, diphenylmethanetetracarboxylic acid It is also possible to use an aromatic polyimide obtained by using as a main component or a sub-component.

In the step (B) of the production method of the present invention, the polyimide siloxane solution composition should be used as a method for forming a flexible base film layer on the back surface (slit-like opening) of the copper foil. The polyimide siloxane solution composition is applied to the back surface (slit-shaped opening) of the copper foil at room temperature or under heating to a uniform thickness by a coating method using a spin coater, a dispenser, a printer, or the like, and the solution composition A flexible base film layer (thickness: consisting of polyimide siloxane) is formed by forming a coating film layer made of a material and then drying the coating film layer at a temperature of about 110 ° C. or higher, particularly about 120 to 180 ° C. About 0.1-500
μm, particularly about 0.2 to 100 μm).

The polyimidesiloxane containing as a main component the polyimidesiloxane solution composition applied to the back surface of the above-mentioned slit-shaped copper foil has an aromatic tetracarboxylic acid component and a diamino represented by the general formula 1. Siloxane (content of all diamine components is about 40 to 90 mol%, particularly 45 to 85 mol%) and aromatic diamine having 2 to 4 benzene rings (content of all diamine components is about 10 to 10). 60 mol%, especially 15-55 mol%) and a diamine component consisting of approximately equimolar polymerization and imidization, and sufficiently soluble in an organic solvent to form a thin film or film. In this case, any polyimide siloxane may be used as an extremely flexible film.

The polyimidesiloxane used in the present invention has a solubility in a diglyme solvent of about 10% by weight or more, particularly about 15 to 50% by weight, and an imidization ratio of about 90%.
As described above, it is particularly preferably 95 to 100%, and the logarithmic viscosity (measured concentration: 0.5
g / 100 ml, solvent: N-methyl-2-pyrrolidone, measurement temperature: 30 ° C.) is 0.05 to 3, preferably about 0.1 to 2.

Examples of the aromatic tetracarboxylic acid component used for producing the above-mentioned polyimide siloxane include:
Biphenyltetracarboxylic acids such as 3,3 ', 4,4'-biphenyltetracarboxylic acid and 2,3,3', 4'-biphenyltetracarboxylic acid, 3,3 ', 4,4'-benzophenonetetracarboxylic acid ,
Benzophenone tetracarboxylic acids such as 2,3,3 ', 4'-benzophenone tetracarboxylic acid, 3,3', 4,4'-biphenyl ether tetracarboxylic acid, bis (3,4-dicarboxyphenyl) methane, 2 , 2-bis (3,4-dicarboxyphenyl)
Propane, pyromellitic acid, or their dianhydrides or ester compounds are mainly (80 mol% or more,
Particularly, an aromatic tetracarboxylic acid component containing 85 to 100 mol%) is preferable, and an aromatic tetracarboxylic acid component containing 2,3,3 ′, 4′-biphenyltetracarboxylic acid as a main component is particularly preferable. 2,3,3 ', 4'-biphenyltetracarboxylic acid, or a biphenyltetracarboxylic acid of an acid dianhydride or an esterified product of a lower alcohol of the acid as a main component (80 mol% or more, particularly 85 to 100%)
Aromatic tetracarboxylic acid component containing (mol%) is preferable, and further, among them, aromatic tetracarboxylic acid component containing 90 to 100% of 2,3,3 ′, 4′-biphenyltetracarboxylic dianhydride is particularly preferable. The carboxylic acid component is optimal because it is excellent in the solubility of the obtained polyimide siloxane in an organic polar solvent and the compatibility with an epoxy compound.

As the diaminopolysiloxane represented by the general formula 1 used in the production of the above-mentioned soluble polyimidesiloxane, R _{1 in} the formula represents a divalent hydrocarbon group and has 2 to 6 carbon atoms, preferably It is composed of a plurality of methylene groups of 3 to 5 or a phenylene group, and R ₂ independently has 1 carbon atom.
To 3 represent an alkyl group such as a methyl group, an ethyl group, a propyl group or a phenyl group, and n is 3 to 30, preferably 4
Those showing an integer of -20 are preferable. The above-mentioned diaminopolysiloxane has too many carbon atoms in R ₁ and R ₂ , or n
If the number of is too large, the reactivity with the aromatic tetracarboxylic acid component will decrease, the molecular weight of the resulting polyimidesiloxane will be low, the solubility in organic solvents will be low, and other polyimides Since the compatibility deteriorates, those within the above range are suitable.

Specific examples of the diaminopolysiloxane include ω, ω'-bis (2-aminoethyl) polydimethylsiloxane, ω, ω'-bis (3-aminopropyl) polydimethylsiloxane, ω, ω '. -Bis (4-aminophenyl) polydimethylsiloxane, ω, ω'-bis (4-amino)
-3-Methylphenyl) polydimethylsiloxane, ω,
ω'-bis (3-aminopropyl) polydiphenylsiloxane and the like can be mentioned.

Examples of the aromatic diamine having 2 to 4 benzene rings used in the production of the aforementioned soluble polyimide siloxane include, for example, 4,4'-diaminodiphenyl ether, 3,4'-diaminodiphenyl ether and 3,3 '. −
Diaminodiphenyl ether such as diaminodiphenyl ether, diaminobiphenyl such as 4,4′-diaminobiphenyl, 3,4′-diaminobiphenyl, bis (4-aminophenyl) methane, bis (4-aminophenyl) sulfone, o-tolidine, o -Aromatic diamine having two benzene rings such as dianisidine, 1,4-bis (4-aminophenoxy) benzene, aromatic diamine having three benzene rings such as 1,4-bis (4-aminophenyl) benzene , Screw [4-
(4-Aminophenoxy) phenyl] sulfone, 2,2-
[4- (4-Aminophenoxy) phenyl] Aromatic diamines (having 2 to 4 benzene rings) such as aromatic diamines having 4 benzene rings such as propane are preferable.

Examples of the polyimide siloxane used in the step (B) of the production method of the present invention include, for example, JP-A-1
As described in JP-A-121325, "an aromatic tetracarboxylic acid component containing a biphenyltetracarboxylic acid as a main component (80 mol% or more, particularly 85 to 100 mol% based on the total amount of the acid component); Diaminopolysilocisan represented by the general formula 1 (20 to 90 mol%, especially 40 to 85 mol%, and further 45 to
80 mol%) and an aromatic diamine (10 to 80 mol%, especially 15 to 60 mol%, and further 20 to 55 mol% based on the total amount of the diamine component), about equimolar, polymerization and imidization Is preferred.

As the method for producing the above-mentioned polyimide siloxane, for example, (1) an aromatic tetracarboxylic acid component and a diamine component composed of diaminopolysiloxane and aromatic diamine are polymerized and imidized at a high temperature in an organic polar solvent. Method (2) Polymerization of excess amount of aromatic tetracarboxylic acid component and diaminopolysiloxane in organic polar solvent at high temperature
Imidization is carried out to prepare an imide siloxane oligomer having a low degree of polymerization of about 1 to 10 and having an acid or acid anhydride group at the terminal, and an aromatic tetracarboxylic acid component and an excess amount of aromatic diamine are separately added as organic polar compounds. Polymerization / imidization is performed in a solvent at a high temperature to prepare an imide oligomer having a low degree of polymerization of about 1 to 10 and having an amino group at a terminal, and then the acid component and the diamine component of both are substantially equimolar. So that they are mixed and reacted at around normal temperature, and further 130-250
A method of obtaining a block type polyimide siloxane by raising the temperature to ° C and (3) polymerizing an aromatic tetracarboxylic acid component and a diamine component composed of diaminopolysiloxane and aromatic diamine in an organic polar solvent at low temperature Examples thereof include a method of obtaining a polyamic acid, heating the polyamic acid to a high temperature and imidizing the polyamic acid to obtain a polyimidesiloxane.

The polyimidesiloxane used in the production method of the present invention contains (a) 2,3,3 ', 4'-biphenyltetracarboxylic acid as a main component described in JP-A-4-36321. An aromatic tetracarboxylic acid component to
Diaminopolysiloxane represented by the general formula 1 (content in all diamine components: 45 to 85 mol%, particularly 45 to 80 mol%), diaminobenzoic acid (in all diamine components: 0.5
˜40 mol%, especially 1 to 35 mol%) and the balance is an aromatic diamine having 2 to 4 benzene rings (in all diamine components: 2 to 60 mol%, special 5 to 50 mol%). 100 parts by weight of a soluble polyimide siloxane obtained by polymerizing and imidizing
It is preferably used as a polyimidesiloxane composition containing 50 parts by weight or a solution composition thereof. Examples of the diaminobenzoic acid include 3,5-diaminobenzoic acid and 2,6-diaminobenzoic acid.

Examples of the organic polar solvent used in preparing the above-mentioned polyimide siloxane solution composition include amide solvents; N, N-dimethylacetamide, N, N-diethylacetamide, N, N-dimethylformamide. , N, N-
Solvents containing sulfur atom such as diethylformamide, N-methyl-2-pyrrolidone, etc .; dimethyl sulfoxide, diethyl sulfoxide, dimethyl sulfone, diethyl sulfone, hexamethyl sulfolamide, etc. phenolic solvents; cresol, phenol, xylenol, etc., ethylene Glycol dimethyl ether-based solvent: Solvent having oxygen atom in the molecule such as ethylene glycol dimethyl ether, diethylene glycol dimethyl ether (diglyme), triethylene glycol dimethyl ether (triglyme); acetone, methanol, ethanol,
Other examples include ethylene glycol, dioxane, tetrahydrofuran, and the like, pyridine, tetramethylurea, and the like. In addition, if necessary, aromatic hydrocarbon solvents such as benzene, toluene, xylene, solvent naphtha,
You may use together other organic solvents, such as benzonitrile.

The above-mentioned polyimide siloxane is the above-mentioned polyimide siloxane.
(1) ~ (3) obtained by any method may be used, as high molecular weight as possible, high imidization rate,
It is dissolved in an organic polar solvent at a high concentration of at least 5% by weight, particularly 10% by weight or more, and the obtained polyimidesiloxane solution composition has a solution viscosity (E type rotational viscometer) of 25 ° C. About 0.01 to 10,000 poise, especially 0.1 to 1,000 poise,
It is appropriate from the viewpoint of workability such as coating operation and overcoat layer forming operation, solution physical properties, and other physical properties.

The epoxy resin used in the above-mentioned polyimide siloxane composition has an epoxy equivalent of 10
It is about 0 to 1000, and the molecular weight is 400 to 5000.
Liquid or powdered epoxy resin, which is of a degree, is preferable,
For example, a bisphenol A type or bisphenol F type epoxy resin (Epicote 80 manufactured by Yuka Shell Epoxy Co., Ltd.)
7, Epicoat 1001, etc.), novolac type epoxy resin (Yukaka Shell Epoxy Co .: Epicoat 157S-
70, Epicoat 152, Epicoat 154, etc.), glycidylamine-type polyfunctional epoxy resin (Yukaka Shell Epoxy Co .: Epicoat 604, etc.), and the like. From the viewpoint of heat resistance, novolac type epoxy resin is most preferable.

The epoxy resin is used in an amount of 1 to 50 parts by weight, based on 100 parts by weight of polyimidesiloxane.
It is preferably 5 to 40 parts by weight. If the amount of the epoxy resin used is too large or too small, the composition may gel and the heat resistance and the chemical resistance after curing may decrease, so the above range is preferable. The polyimide siloxane solution composition may contain an inorganic filler such as Wallacenite, silica or talc, or an inorganic or organic dye or pigment together with the epoxy resin.

The above-mentioned polyimide siloxane solution composition can be easily prepared by uniformly stirring and mixing the polyimide siloxane and the epoxy resin in the presence or absence of the organic polar solvent. When the polyimide siloxane and the epoxy resin are mixed, they can be mixed in a suitable organic polar solvent to obtain a solution composition of polyimide siloxane, and after the mixing, the polyimide siloxane solution composition is dissolved in an organic polar solvent. You can make things. The polyimidesiloxane solution composition may be prepared by using the polymerization solution of polyimidesiloxane as it is, or may be prepared by diluting the polymerization solution with an appropriate organic solvent.

Examples of the organic polar solvent used in the polyimidesiloxane solution composition include organic polar solvents that can be used for obtaining the polyimidesiloxane, and those having a boiling point of 140 ° C. or higher, for example, a boiling point of 18
When an organic solvent having a temperature of 0 ° C or higher, particularly 200 ° C or higher is used, the dissipation due to the evaporation of the solvent is significantly reduced, so that the storage stability is improved and the printing ink is used. This is optimal because screen printing can be suitably performed without any problems. The flexible base film layer made of a polyimide siloxane formed from the above-mentioned solution composition of polyimide siloxane has excellent mechanical strength and electrical insulation, and also has high heat resistance.

In step (B) of the production method of the present invention,
Before applying the polyimidesiloxane solution composition to the back surface 5 of the copper foil 2 exposed in the slit shape of the copper-clad substrate 4 obtained in the step (A), as shown in (f) of FIG. After adhering the imidazole compound to the back surface 5 of the copper foil, the polyimidesiloxane solution composition is further applied onto the imidazole compound adhering layer 10 and dried to form slits as shown in FIG. 4 (g). Backside 5 of exposed copper foil 2
Flexible base film layer 7 made of polyimide siloxane
Is suitable for improving the adhesion between the back surface of the copper foil and the flexible base film layer.

The imidazole compound adhesion layer 10 formed on the wiring board 46 shown in FIG. 4 (f) is then coated with the polyimidesiloxane solution composition and dried. When the flexible coating layer made of polyimide siloxane is finally formed by melting in the coating layer and dissolving in the polyimide siloxane, as shown in the wiring board 47 of FIG. 4 (g). Although the adhesion layer 10 disappears from the back surface of the copper foil, the imidazole compound is substantially contained in the flexible coating layer 7.

Examples of the above-mentioned imidazole compound include imidazole, 2-methylimidazole, 2-ethyl-
4-methylimidazole, 2-undecylimidazole, 2-
"2-alkyl imidazoles optionally having substituents" such as heptadecyl imidazole, 1-benzyl-2-methyl imidazole, 1-cyanoethyl-2-methyl imidazole, 2-phenyl imidazole, 1-cyanoethyl-2 Preferable examples thereof include "2-phenylimidazoles which may have a substituent" such as phenylimidazole.

As a method of attaching the imidazole compound to the back surface of the copper foil, for example, (A) in a solution in which the imidazole compound is dissolved in a polar solvent (for example, an aqueous solution of the imidazole compound, an alcohol solution, etc.) The copper clad substrate obtained in the step is heated to about 5 to 60 ° C., especially 10 to 5 ° C.
At a temperature of 0 ° C. for about 0.1 to 30 minutes, especially 0.2 to 10
Minute, further 0.2 to 3 minutes, so as to coat and adhere the imidazole compound solution to the back surface (slit-shaped opening) of the copper foil, and then to coat the coating layer with the coating layer for about 30 minutes.
0.1 ° C or higher, especially at a temperature of 40 to 150 ° C.
A method of forming an imidazole compound adhesion layer by drying for 30 minutes, or a polar solvent solution of the above imidazole compound at room temperature on the back surface (slit-shaped opening) of the copper foil of the copper clad substrate obtained in step (A). Alternatively, under heating, apply by a coating method using a spin coater, a dispenser or a printing machine,
The method of forming the imidazole compound adhesion layer by drying under the above-mentioned drying conditions can be preferably mentioned.

In the above-mentioned adhesion (or coating layer) of the imidazole compound solution layer, the polar solvent such as water may be completely removed from the imidazole compound adhesion layer, but it is not always necessary to completely remove the polar solvent. A part of the polar solvent (0.01 to
20% by weight, particularly about 0.02 to 10% by weight) may remain, and the imidazole compound-attached layer may be swollen with a solvent such as water. The imidazole compound adhesion layer has a thickness of about 0.01 to 20 μm, and particularly 0.05.
It is preferably about 10 to 10 μm, and more preferably about 0.1 to 5 μm.

In the production method of the present invention, (A) and (B)
After the copper-clad substrate 41 in which the aromatic polyimide base film 1 and the flexible base film 7 (slit-shaped opening) and the back surface of the copper foil 2 are bonded to each other by the steps, (b) of FIG. As shown in (e), in the step (C), an etching resist is printed in an appropriate wiring pattern shape (circuit pattern shape) on the surface 6 of the copper foil 2 on the copper clad substrate 42 to form a wiring pattern. After forming the "etching resist wiring pattern 8" that protects the surface 6 of the copper foil 2 in the exposed portion [see (b) of FIG. 3], the copper in the portion where the wiring is not formed by using an appropriate etching reagent The foil is removed by etching and the flexible base film 7
The whole of the other wiring 22 is formed together with the upper bent portion wiring 21. [Refer to (c) of FIG. 3]

In the manufacturing method of the present invention, finally, (C)
In the step (D) following the step, if necessary, the etching resist 8 on the formed wirings 21 and 22 is removed [see (d) of FIG. 3], and the side where the patterns of the wirings 21 and 22 are formed. By forming a flexible coating layer (overcoat layer) 9 on the entire surface of the (see (e) of FIG. 3),
Wiring board 4 with bends such as flexible printed wiring boards
5 can be manufactured suitably.

In the present invention, the above-mentioned step (C) and
In the step (D), a conventionally known copper etching method or overcoat coating method that is generally used in various wiring board manufacturing methods can be adopted. In the manufacturing method of the present invention, the method of forming the flexible coating layer on the upper surface of the wiring pattern of the wiring board is, for example, applying the above-mentioned polyimidesiloxane solution composition to the upper surface of the wiring pattern of the wiring board, and drying the coating layer. Then, a method of forming a flexible coating layer (overcoat layer) made of polyimide siloxane is preferable.

Before forming a flexible coating layer on the wiring pattern of the wiring board in the step (D) of the production method of the present invention, an imidazole compound is attached to the wiring pattern to form an imidazole compound-attached layer, and The polyimide siloxane solution composition is applied thereon and dried to form a flexible coating layer made of polyimide siloxane.
It is preferable to manufacture the wiring board 45 with a bent portion as shown in (e) in order to improve the adhesion between the wirings 21 and 22 and the coating layer 9. The formation of the above imidazole compound adhesion layer is performed by the same method as described in the method of forming the oxazole compound adhesion layer on the back surface of the copper foil of the copper clad substrate [see (f) and (g) of FIG. 4]. You can

[0045]

EXAMPLES The present invention will be described below with reference to Examples and Comparative Examples. In the Reference Examples and Examples, the heat-resistant adhesiveness between the flexible base film of the wiring board and the copper foil, the logarithmic viscosity of the aromatic polyimide or polyimidesiloxane, etc. were measured by the following methods.

As a measure of the molecular weight of aromatic polyimide and polyimidesiloxane, the logarithmic viscosity is 0.5 g / concentration.
Use a solution in which polyimidesiloxane is uniformly dissolved in N-methyl-2-pyrrolidone to make a 100 ml solution, and use a Canon-Fenske viscometer to measure 30
It was measured at ° C. The imidization ratio (%) of aromatic polyimide and polyimidesiloxane was measured by an infrared absorption spectrum analysis method.

[Heat Resistant Adhesion (Plating Resistance): Amount of Tin Plating Liquid Migrated] A polyimidesiloxane solution composition was applied by the method of Example 1 below to the back surface of a copper foil of a wiring board or the wiring pattern of a wiring board. The resulting flexible base sheet layer or coating layer made of polyimidesiloxane was formed. These were immersed in an electroless tin plating solution. If the tin plating solution penetrates (curves) from the boundary between the flexible base sheet and the back surface of the copper foil or the boundary between the flexible coating layer and the wiring, an overcoat layer is formed. At the spot where the tin plating was entangled, the surface was observed under a microscope of 100 times to observe the discolored and white appearance, and the length of the discolored portion was measured to determine the amount of entanglement.

Reference Example 1 [Production of Polyimide Siloxane] In a glass flask having a capacity of 500 ml, 2, 3,
3 ', 4'-biphenyltetracarboxylic dianhydride (a-BP
DA) 14.71 g (50 mmol) and N-methyl-2-pyrrolidone (NMP) 100 g were charged, and while the solution was stirred at room temperature to dissolve a-BPDA, ω, ω′-bis (3 -Aminopropyl) polydimethylsiloxane (DAPS) (manufactured by Shin-Etsu Silicon, X-22
-161AS, n = 9) 30.80 g (35 mmol)
And 100 g of diglyme were added and uniformly dissolved, and the mixture was heated at 190 ° C. under a nitrogen atmosphere to reflux the diglyme to remove water and polymerize at this temperature for 4 hours. Then
The reaction solution was returned to room temperature and stirred with 2,2-bis [4- (4-aminophenoxy) phenyl] propane (BAPP) 3.08
g (7.5 mmol) and 3,5-diaminobenzoic acid (DABA)
After adding 1.41 g (7.5 mmol) and 47.9 g of NMP, the reaction temperature was raised to 200 to 210 ° C and further 3
A reaction was carried out for a time to prepare a polyimidesiloxane solution.

The reaction solution was returned to room temperature and added to methanol to precipitate polyimide siloxane for 30 minutes using a disperser, followed by filtration and 10 minutes in methanol.
Washing for 2 minutes, vacuum drying at 60 ° C for 8 hours,
43.87 g (yield 92%) of powdery polyimide siloxane was obtained. As a measure of the molecular weight, the logarithmic viscosity was 0.18 and the imidization ratio was substantially 100%.

Reference Example 2 [Preparation of Polyimide Siloxane Solution Composition] 30 g of the polyimide siloxane of Reference Example 1 was mixed with a novolac type epoxy resin (Epicote 1 manufactured by Yuka Shell Epoxy Co., Ltd.).
57S-70) 5.40 g was uniformly dissolved in 40 g of diglyme at room temperature to obtain a polyimide siloxane solution composition (concentration 39.8%, solution viscosity 100 poise at 20 ° C.). This solution composition retained the solution viscosity in a uniform solution state even when left at room temperature for 1 week.

Example 1 A 75 μm thick aromatic polyimide film (base film) having slit-shaped openings (size: 8 mm × 20 mm) [manufactured by Ube Industries, Ltd., trade name (registered trademark):
Upilex-S, 35 mm × 70 mm)], an adhesive layer and a copper foil having a thickness of 35 μm are integrally laminated and bonded together except for the slit-shaped openings, and a copper clad substrate as shown in FIG. (The back surface of the copper foil is exposed at the slit-shaped opening).

Next, the polyimidesiloxane solution composition obtained in Reference Example 2 was thinly applied to the back surface (slit-shaped opening) of the copper foil of the copper clad substrate shown in FIG. 1 manufactured as described above. , A flexible base film layer made of polyimidesiloxane (average thickness: 30) after drying at a temperature of about 200 ° C.
μm) is continuously and integrally formed with an aromatic polyimide base film to form a copper-clad substrate 4 as shown in FIG. 2 (a).
1 was produced.

Then, an etching resist (manufactured by Yamagishi Chemical Co., Ltd .: SER-42) is formed on the surface of the copper foil of the copper clad substrate.
0) was printed in a circuit pattern shape by screen printing and cured at 120 ° C. for 30 minutes to produce a wiring board 42 [(b) of FIG. 3] having a circuit pattern etching layer. The copper clad substrate 42 on which this etching resist is printed is treated with an aqueous ferric chloride solution (etching solution, 60 ° C.) at 50 ° C.
The wiring board 43 [(c) of FIG. 3] on which the bent wiring and other wiring corresponding to the slit opening are formed all at once by etching in copper for 10 to 15 minutes to partially remove copper After manufacturing, the etching resist remaining on the wiring board is removed by immersing in a 2% sodium hydroxide aqueous solution to manufacture a printed wiring board 44 with a bent portion as shown in FIG. 3 (d). did.

Finally, a 1% by weight aqueous solution of imidazole was applied onto the copper circuit pattern of the printed wiring board with a bent portion 44 obtained as described above, and dried at 50 ° C. for 10 minutes to adhere the imidazole compound. Layer (thickness: about 1 μm)
Then, the polyimide siloxane solution composition prepared in Reference Example 2 was applied on the imidazole compound-attached layer and dried to form a flexible polyimide siloxane solution as shown in FIG. 3 (e). Wiring board 4 with a bent portion on which a coating layer (overcoat layer, thickness: 30 μm) is formed
5 was produced.

A part of the printed wiring board 45 with a bent portion manufactured as described above is immersed in an electroless tin plating solution (Teineposit LT-34, manufactured by Shiplane Co., Ltd.) for 10 minutes in a tin plating solution at 75 ° C. Soaked in and processed. At that time, since tin plating solution soaked (penetration) from the boundary between the copper circuit of the wiring board and the coating layer, the portion was discolored and appeared white when observed from the surface side of the overcoat layer. The length of the discolored portion was measured, and the amount of tin crawling showing heat-resistant adhesion (plating resistance) was measured. The result was that the length of the discolored portion was about 5 μm. The printed wiring board with a bent portion manufactured as described above could be flexibly bent at the bent portion and was excellent in bending resistance.

[0056]

The manufacturing method of the present invention uses a copper-clad substrate in which a tough aromatic polyimide film base film having a slit-shaped opening and the back surface of a copper foil are joined together except for the slit-shaped opening. , A polyimide siloxane solution composition is applied to the back surface of the copper foil exposed in the slit-shaped openings in the copper-clad substrate and dried to form an aromatic polyimide base film and a polyimide siloxane flexible base film (slit-shaped). A copper-clad substrate having an opening portion: a bent portion) on the back surface of a copper foil is manufactured, a wiring board is formed by an etching operation using the copper-clad substrate, and a coating layer is further applied to thereby bend the substrate. It is a new manufacturing method that can industrially manufacture a printed wiring board with a bent portion that has high performance with excellent insulation and adhesion. .

[Brief description of drawings]

FIG. 1 is a copper clad substrate 4 obtained in step (A) of the manufacturing method of the present invention.
The top view which shows an example, AA 'line (transverse) sectional drawing, and B
It is a -B 'line (longitudinal) sectional view.

FIG. 2 is a (longitudinal) sectional view of a copper clad substrate 41 obtained in the step (B).

FIG. 3 is (longitudinal) cross-sectional views (b) to (e) illustrating a wiring board 42 and wiring lines 43, 44 and 45 formed in steps (C) to (D) of the manufacturing method of the present invention.

FIG. 4 is a (longitudinal) cross-sectional view (FIG. 4 (f)) showing a state of the wiring board 46 when the imidazole adhesion layer is formed in the step (B) of the manufacturing method of the present invention, and the back surface of the copper foil. A (longitudinal) sectional view showing a copper clad substrate 47 having a flexible coating layer formed thereon (see FIG. 4).
(g)].

[Explanation of symbols]

 1: Base film 2: Copper foil 3: Slit-shaped opening (bent portion) 4: Wiring substrate 5: Back surface of copper foil 6: Front surface of copper foil 7: Flexible base film layer 8: Etching layer (wiring pattern shape) 9: Coating layer 21: Wiring (bending portion) 22: Wiring 45: Wiring board with bending portion

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yukio Shimizu 6 1978 Kobugushi, Ube City Ube Chemical Co., Ltd. Ube Chemical Factory

Claims (4)

[Claims] 1. A whole surface of (A) a base film made of an aromatic polyimide partially opening in a slit shape and the back surface of the copper foil except that the back surface of the copper foil is exposed in the slit opening. To form a copper-clad substrate that is bonded to each other, and (B) apply a polyimidesiloxane solution composition to the back surface of the copper foil that is exposed in a slit shape in the copper-clad substrate, dry it, and expose it in a slit shape. A copper-clad substrate in which a flexible base film layer made of polyimide siloxane is continuously and integrally formed with an aromatic polyimide base film on the back surface of the copper foil is prepared (C) and manufactured as described above. In the copper-clad substrate, a portion where the surface is exposed by pattern-printing an etching resist on the surface of the copper foil to form a resist pattern and then performing a copper etching operation using an etching agent. By removing the copper foil, to form a copper wiring pattern including a bent portion wiring formed in the flexible base film layer portion, (D) Finally, if necessary, after removing the etching resist layer, the copper A method of manufacturing a wiring board with a bent portion, which comprises forming a flexible coating layer on a wiring pattern. 2. The polyimidesiloxane in the polyimidesiloxane solution composition used in step (B) comprises an aromatic tetracarboxylic acid component and a compound represented by the general formula (1): (However, R ₁ in the formula represents a divalent hydrocarbon residue,
₂ independently represents an alkyl group having 1 to 3 carbon atoms or a phenyl group, and n represents an integer of 3 to 30. And a diamine component containing an aromatic diamine having 2 to 4 benzene rings at a ratio of about 10 to 60 mol% and a diaminopolysiloxane represented by the formula (1) to about 40 to 90 mol%. The method for producing a wiring board with a bent portion according to claim 1, which is a soluble polyimide siloxane obtained by polymerizing and imidizing with a mole. 3. In the step (B), before applying the polyimidesiloxane solution composition to the back surface of the copper foil exposed in the slit shape of the copper clad substrate, after applying the imidazole compound to the back surface of the copper foil, Furthermore, the polyimide siloxane solution composition is apply | coated on it, it dries and the flexible base film layer made from polyimide siloxane is formed in the back surface of the copper foil exposed in slit form, The bending part of Claim 1. Method of manufacturing wiring board with. 4. Before forming a flexible coating layer on the wiring pattern in the step (D), an imidazole compound is attached to the wiring pattern, and a polyimidesiloxane solution composition is applied on the compound and dried. The method for producing a wiring board with a bent portion according to claim 1, wherein a flexible coating layer made of polyimidesiloxane is formed.