JPS62104840A - Production of flexible printed circuit board - Google Patents

Abstract

PURPOSE:To obtain a circuit board having all good heat resistance, electrical characteristic, adhesive property, mechanical characteristic, e.g. flexibility, and dimensional stability, by laminating a metal foil to a thermosetting polyimide film with a specific polyimide film as an adhesive. CONSTITUTION:A polyimide film produced by reacting a symmetric aromatic primary amine group containing a symmetric aromatic meta-substituted primary amine at 100-20% equivalent ratio with an aromatic tetracarboxylic acid anhydride is used as an adhesive in laminating a metal foil to a thermosetting polyimide film. The formed polyimide film is inserted between a film without adhesive property and a metal foil to laminate both film and foil while heating under pressure. The above-mentioned formed film is used as both an adhesive and an insulating layer for lamination.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a method for manufacturing a flexible printed circuit board having excellent heat resistance, electrical properties, zero mechanical properties, and dimensional stability. This invention relates to a method for manufacturing a foil-lined polyimide flexible printed circuit board and a metal foil-backed polyimide flexible printed circuit board that has improved dimensional stability and heat dissipation when one side is covered with copper foil.

[Conventional technology]

A flexible printed circuit board is a board for manufacturing flexible printed circuits, and in recent years,
Their use is increasing as the cases that house printed circuits become more compact. Such flexible printed circuit boards have conventionally been manufactured by laminating a polyimide film to a copper foil using an adhesive. In this substrate, although the polyimide film has sufficiently good heat resistance, electrical properties, and mechanical properties, there is a problem in that the properties of the polyimide film are not fully utilized because the properties of the adhesive are insufficient.

Therefore, methods of manufacturing flexible printed circuit boards from polyimide metal clad plates without using an adhesive layer have been studied, for example, US Pat.
No. 79,684, JP-A-49-129862, and JP-A-58-190091.

JP-A No. 58-190092, etc. However, it is still difficult to obtain a flexible printed circuit board that has sufficient heat resistance, adhesiveness, flexibility, and dimensional stability.

[Problems to be Solved by the Invention] The purpose of the present invention is to provide a single-sided and double-sided metal foil-clad polyimide flexible printed circuit board and a single-sided copper foil-covered polyimide printed circuit board that is excellent in heat resistance, electrical properties, mechanical properties, and dimensional stability. To provide a method for manufacturing a polyimide flexible printed circuit board lined with gold foil, which has further improved dimensional stability and heat dissipation in tension.

[Means for solving problems]

The above object is achieved by the following method for manufacturing a flexible printed circuit board. For single-sided metal foil-covered polyimide flexible printed circuit boards, a symmetrical aromatic primary amine group containing 100 to 20 symmetrical aromatic meta-substituted primary amines in an equivalent proportion and an aromatic tetracarboxylic acid anhydride. A polyimide film produced by reacting with
A manufacturing method characterized in that it is used as an adhesive for laminating metal foil and thermosetting polyimide film.

Moreover, the polyimide film can also be laminated directly onto the metal foil under pressure and heat. For double-sided metal foil-covered polyimide flexible printed circuit boards, the polyimide film can be used as an adhesive and an insulating layer for laminating metal foils. Furthermore, for polyimide flexible printed circuit boards lined with metal foil to further improve dimensional stability and improve heat dissipation, the polyimide film core is replaced with copper foil and metal foil to improve dimensional stability. It can be used as a lamination adhesive and an insulating layer.

The symmetrical aromatic meta-substituted primary amine (hereinafter abbreviated as m-diamine) used in the present invention can be represented by the following general formula.

[In the above general formula, × is 0,802,8. Co.

It is selected from CH2, C(CH3)2, and C(CF3)2, and each x may be the same or different. ]
An example of m-diamine represented by the above general formula is 8.
3'-diaminodiphenyl ether, 8°8'-diaminodiphenyl sulfide, 3. f13'-diaminodiphenylsulfoxide, 8,8'-diaminodiphenylsulfone, 8,8'-diaminobenzophenone, bis I"
4-(8-aminophenoxy)phenylcomethane, 2.
2-bisC4-(8-aminophenoxy)phenyl]propane, 2.2-bis[4-(3-aminophenoxy)
phenyl]-1,1,1,8,8,8-hexafluoropropane, l,8-bis(8-aminophenoxy)benzene 14.4'-bis(3-aminophenoxy)biphenyl, bis[4- (8-aminophenoxy)phenylkoketone, bis[:4-(3-aminophenoxy)phenyl]sulfide, bisC+-(8-aminophenoxy)
phenyl] sulfoxide.

Bis(+-(a-aminophenoxy)phenyl]sulfone, bis(4-(8-aminophenoxy)phenyl)ether, 4.4'-bis(8-aminophenylsulfonyl)diphenyl ether, 4゜47-bis(8 -Amine 100-enoxy) diphenyl sulfone, 1,4-bisC
Examples include 4-(8-aminophenoxy)benzoyl]benzene, which can be used alone or in combination of two or more.

The symmetrical aromatic primary amine group represents m-diamine 100 or a mixture of m-diamine and a symmetrical aromatic rose-substituted primary amine (hereinafter abbreviated as p-diamine). . P-diamine can be represented by the general formula shown below.

HzN-〈;;〉-ゞ-kugokaku〉-riζshi〉-x-
,')o N[1z, [In the above general formula, × is 0,802. S.

It is selected from CO, CH2, C(CH3)2, and C(CF3)2, and each x may be the same or different. ] Examples of p-diamines represented by the above general formula include heather, 4'-diaminodiphenyl ether, 44'-
Diaminodiphenylsulfide, 4.4'-diaminodiphenylsulfoxide, 4.4'-diaminodiphenylsulfone + 4s 4'-diaminobenzopheno/
, bis[4-(4-aminophenoxy)phenyl]meta7.2.2-bis[4-(4-aminophenoxy)phenyl]propane, 2.2-bis(4-(4-aminophenoxy)phenyl) -1,1,1,8,8,8-hexafluoropropane, 1,3-bis(4-aminophenoxy)benzene, 4,4'-bis(4-aminophenoxy)biphenyl, bis[4-( 4-aminophenoxy)phenylkoketone, bis(:4-(4-aminophenoxy)phenyl]sulfide, bisC+-(k-aminophenoxy)phenyl)sulfoxide.

Bis[+-(4-aminophenoxy)phenyl]sulfone, bis[4-(4-aminophenoxy)phenyl]ether, 4.4'-bis(4-aminophenylsulfonyl)diphenyl ether, 4゜4'-bis( 4-Aminethiophenoxy)diphenylsulfones1.4-bis(
Examples include 4-(8-aminophenoxy)benzoyl]benzene, which can be used alone or in combination of two or more.

The aromatic tetracarbo/acid anhydride to be reacted with diamine is pyromellitic dianhydride%8j8',4.4'-
Pe/siphenotetracarboxylic dianhydride, 2.2',
3.3'-be/siphenoic dianhydride m,l 3',4
．． 4'-biphenyltetracarboxylic dianhydride, 2.2
', g, 8'-biphenyltetracarboxylic dianhydride, 2,2-bis(3,4-dicarboxyphenyl)propane dianhydride, 2,2-bis(2,8-dicarboxyphenyl)propane dianhydride Anhydride, bis(3#4-dicarboxyphenyl)ether dianhydride, bis(8,4-dicarboxyphenyl)sulfone dianhydride, 1. t-bis (
2,8-dicarboxyphenyl)ethane dianhydride, bis(2,3-dicarboxyphenyl)methane dianhydride, bis(3゜4-dicarboxyphenyl)methane dianhydride,
2.8,6.7-Naphthalenetetracarboxylic dianhydride, ], ]4.5.8-Naphthalenetetracarboxylic dianhydride 1.2.5°6-Naphthalenetetracarboxylic dianhydride, l.

Z, 8.4-benzenetetracarboxylic dianhydride, 8.
4.9.10-perylenetetracarboxylic dianhydride, 2
．． 3.6.7-anthracenetetracarboxylic dianhydride, 1.2.7.8-7 enanthrenetetracarboxylic dianhydride, etc. are used.

These may be used alone or in a mixture of two or more.

Examples of the organic solvent include N-methyl-2-pyrrolidone, N,N-dimethylacetamide, N,N-dimethylformamide, 1,3-dimethyl-2-imidazolidinone, N,N-diethylacetamide, N, N-dimethylmethoxyacetamide, dimethylsulfoxide, pyridine, dimethylsulfone, hexamethylphosphoramide,
Tetramethylurea, N-methylcaprolactam, ↑trahydrofuran, m-dioxane, p-dioxane, 1,
Examples include z-dimethoxyethano1bis(2-methoxyethyl)ether, 1,2-bis(2-methoxyethoxy)ethane, bis-(:2-(2-methoxyethoxy)ethyl)ether, and the like.

In the present invention, when producing polyamic acid, m-diamine and p-diamine are placed in an organic solvent, and the equivalent ratio of m-diamine and p-diamine is adjusted in advance to 100 to 100.
20:θ~80, preferably 100~30:0~70,
Particularly preferably after mixing at a ratio of 100 to 50:0 to 50,
It is important to react with aromatic tetracarboxylic acid anhydride.

When the equivalent ratio of p-diamine among diamines is 80 or more, the properties of the produced polyimide as an adhesive are low, and the circuit of the flexible printed circuit easily peels off from the polyimide film, making it impossible to put it to practical use. There is a drawback.

In addition, when producing polyamic acid, 1,8-bis(8-aminophenoxy)benzene, 8-bis(8-aminophenoxy)benzene,
．． 8'-diaminobenzophenone, 4,4'-bis(8
-aminophenoxy)biphenyl alone or in combination, and 1,8-bis(4-aminophexy)benzene as p-diamine.

4.4'-diaminodiphenyl ether, 4.4'-bis(4-aminophenoxy)biphenyl are used alone or in combination, and the aromatic tetracarboxylic acid anhydride is pyromellitic dianhydride, 8.8', It is particularly preferable to use 4'-benzophenonetetracarboxylic dianhydride alone or in combination, and it is a flexible material with excellent mechanical properties such as heat resistance, 1-air properties, adhesiveness, and flexibility, and dimensional stability. Printed circuit boards can be manufactured.

When producing a polyimide fill from a polyamic acid solution, first, a sheet of steel or the like is coated with the polyamic acid solution to a certain thickness. When coating a sheet with such a polyamic acid solution, it is preferable that the solution contains 5 to 40 weight percent of polyamic acid, and the logarithmic viscosity is 0.5 to 6 (1//
g (85'O1 concentrated g O, 5g/m1% N
, N-dimethylacetamide), especially 0.
7 to 4 is preferred.

The operation of coating the sheet with the polyamic acid solution is preferably carried out by casting, and specifically, the following method is used. A polyamic acid solution is discharged onto the sheet from a film-forming slit to form a uniform film layer (the thickness is generally adjusted to be 80 to 800 μm). As a coating method,
Roll coater, knife coater, dofter blade,
It is also possible to use other known means such as a flow coater.

The polyamic acid coating layer prepared as described above is then heated to perform solvent removal and dehydration condensation reactions. This operation can be carried out under any conditions such as normal pressure, reduced pressure, or increased pressure.

Generally, the required time is 80~200°0. Preferably 1
Heat to 0-150"0 to remove most of the solvent.

If the temperature is below 80°C, the removal of the solvent is slow and uneconomical, and if the temperature is above 0°C, the removal of the solvent is too fast, which may adversely affect the film shape due to film formation, bubble generation, etc. As the partial dehydration and condensation reactions begin, adhesion to the sheet also begins, making it difficult for the film to be released from the sheet, which is undesirable.

After most of the solvent is removed and a polyamic acid film is formed, it is peeled off from the sheet and passed through a pin tenter to completely remove the solvent and undergo dehydration and condensation reactions to imidize and form a polyimide film. Complete surface removal of the solvent, de4hydration, and condensation reaction are carried out by heating to 150 to 850°C, preferably 200 to 800°C. At temperatures below 150°C, the removal of the solvent or the condensation reaction is sufficient and strong;
In the lamination process when manufacturing flexible printed circuit boards,
Voids occur within the polyimide film, resulting in insulating properties.

Adhesion, etc. becomes insufficient. In addition, temperatures above 350°C are not preferred because the polyimide deteriorates, the polyimide undergoes a glass transition, and the point becomes high, making it difficult to lamination due to the need to increase the bonding temperature in the lamination process.

Metal foils such as copper foil, aluminum foil, and nickel foil are generally used as the metal foil conductor used when a flexible printed circuit board is developed using the inside of the polyimide film produced as described above. Furthermore, metals such as stainless steel foil, aluminum foil, nickel foil, and copper foil are used as the substrate lining metal foil to improve the dimensional stability of the substrate.

Control of heating temperature and pressure is essential in laminating polyimide film with metal foil and forming it into a substrate.

The temperature for forming the substrate must be higher than the glass transition point of the polyimide film to be used, preferably 15 to 100000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000 000 form. is 1-5
00kII/cII, preferably 5 to 100kJ/d is suitable. In addition, the heating and pressurizing time is 1 to 200
minutes, preferably 5 to 60 minutes. If the metal foil surface is exposed to a temperature higher than the oxidation temperature during the process of forming the metal foil onto the substrate, oxidation of the metal foil surface will occur, resulting in a decrease in the mechanical properties, electrical properties, and adhesion of the metal foil. When molding is carried out at a temperature higher than that at which the surface of the metal foil is oxidized, it is particularly preferable to carry out the molding in an inert gas. In this case, being in an inert gas atmosphere means that the surface of the metal foil is in a gas atmosphere that does not substantially undergo oxidation reactions that adversely affect electrical properties, mechanical properties, adhesive strength, etc. when heated for a predetermined period of time. Although it depends on the heating temperature and time, in many cases the oxygen concentration is 2 x 10 mol/I! It means a gas atmosphere that is as follows, and can be carried out by the following methods, etc. The materials to be laminated are placed in a bag made of heat-resistant film, and the air inside the bag is first removed using a vacuum pump. Then pressurize with inert gas.

It is molded using a so-called vacuum press (manufactured by Vacuum Press, Inc., USA, etc.) that uses heating. In addition, when directly laminating metal foil on only one side of the polyimide film, insert the polyimide film (2) between the metal foil and the film, which has no adhesive properties, and laminate it under pressure and heat. This can be done by -. Polyimide film is a film that does not adhere under pressure or heat.
Teflon (fluororesin manufactured by DuPont), Ubilex S
(polyimide manufactured by Ube Industries, Ltd.).

A flexible printed circuit board made of a polyimide metal-clad sheet manufactured by the present invention represented by the method described above does not contain an adhesive layer, and the polyimide film that serves as an adhesive and insulating layer is substantially Because it is a polyimide with excellent properties that does not contain a solvent and has undergone a condensation reaction, it has excellent heat resistance, electrical properties 1 mechanical properties, and dimensional stability.

〔Example〕

Next, the present invention and its effects will be specifically explained with reference to Examples and Comparative Examples.

The logarithmic viscosity in the examples is 85°O10.5g/100m
/ .

The value was measured with N,N-dimethylacetamide, and the rotational viscosity was measured at 25°C using the high viscosity rotor of an E-type viscometer.
The value measured in stone. Various performances as a printed circuit board were measured by the methods shown below.

+1+ Foil peeling strength It was carried out according to the method of IPC-FC-241A.

已）Surface resistance It was conducted according to JIS C-6481.

■ Solder resistance Samples were tested in accordance with JIS C-6481.
After 60 seconds of immersion in the o'o solder bath, "blister" and "deformation of the polyimide film" were observed.

(4) Bending strength According to JIS P-8115, the radius of curvature of the bending surface is 0.
．． The measurement was performed with 8 fl and a static load of 500 g. In the case of a double-sided metal foil-clad substrate, the metal foil on one side was removed by etching the entire surface, and then measurements were performed.

(5) Dimensional stability It was measured by the method of IPC-FC-241A and expressed as shrinkage percentage.

Example 1 In a container equipped with a stirrer, a reflux condenser and a nitrogen inlet tube,
4'-bis(3-aminophenoxy)biphenyl73.
7 g (0.2 mol) was dissolved in 250 m/m of N,N-dimethylacetamide, cooled to around 0°0, and 48.6 g of pyromellitic dianhydride was dissolved in a nitrogen atmosphere.
(0.2 mol) was added and stirred at around 0°C for 2 hours.

Next, the solution was returned to room temperature and stirred for about 20 hours under a nitrogen atmosphere. The logarithmic viscosity of the polyamic acid solution thus obtained was 1.9L and 47g. This polyamic acid solution was diluted to 12ts with N,N-dimethylacetamide, and the viscosity was adjusted to 80.000CP and 8ticy4.

The solution was uniformly coated onto a flat glass plate using a doctor blade. This coated glass plate was heated at 185°C for 1 hour to obtain a polyamic acid film.

This film was peeled off from the glass plate, placed on a pin tenter, and reheated. Heating at that time was carried out gradually from 100'O to 280'0 over 2 hours.
After being kept at 80°0 for 1 hour, it was cooled to room temperature to obtain a polyimide film. The film thickness is 15μ and the amount of residual solvent is 0.1
=1 or less. This polyimide film was laminated by inserting it between rolled copper foil (85μ thick) and Kapton film (polyimide film manufactured by DuPont, thickness 25μ), and heated to 800° with nitrogen using a vacuum press (manufactured by Vacuum Press, USA). Molding was performed for 80 minutes at 0.20 kj/d to obtain a Kapton-based single-sided copper-clad flexible printed circuit board. The characteristics of this substrate were as shown in Table-1.

Example 2 A polyimide film with a thickness of 25μ (residual solvent amount is 0.1 or less) prepared in the same manner as in Example 1 was inserted between rolled steel foil (thickness 85μ) and Upilex S film (25μ). They were laminated and molded using a vacuum press in nitrogen at 280° and 0.20 kp/d for 40 minutes. After cooling to room temperature, the Ubilex S film was peeled off from the laminated sheet to obtain a single-sided copper-clad flexible printed circuit board without using an adhesive layer. The characteristics of this substrate were as shown in Table-1.

Example 8 4. In a vessel equipped with a stirrer, a reflux condenser and a nitrogen inlet tube.
4'-bis(8-aminophenoxy)biphenyl51.
6 g (0.14 mol) and 1,8-bis(8-aminophenoxy)benzey 1 ? , 5 g (0.06 mol) was dissolved in 250 m/N,N-dimethylacetamide, cooled to around 0"0, and placed in a nitrogen atmosphere at 171C:
l? 7t? cr711J 9)! Yu. □8.6g (0
, 2 mol) and stirred at around 0°0 for 2 hours. Then - bring the solution back to room temperature and under a nitrogen atmosphere about 20:1
Intermittent stirring was performed. The polyamide thus obtained (the logarithmic viscosity of the acid solution was 1.617 g.
．． 1. Ao, acid solution N, N--)) f1 Aya, Ami:
Dilute up to 15 degrees with a viscosity of 25.000C.
Adjusted P8&C. This solution was uniformly coated onto a smooth glass plate using a doctor blade. This coated glass plate was heated at 185°0 for 1 hour to obtain a polyamic acid film. This film was peeled off from the glass plate, placed in a pin tenter, and reheated. Heating #-t at that time was gradually carried out from 100°C to 250°C over 2 hours. Thereafter, the mixture was kept at 2i50°0 for 1 hour, and then cooled to room temperature to obtain a polyamic acid lume. Film thickness is 2
5μ, and no residual solvent amount was detected. This polyimide was inserted between two sheets of electrolytic copper foil (thickness 18μ) and laminated.
Molding was performed for minutes to obtain a double-sided copper-clad flexible printed circuit board in which polyamide serves as both an adhesive layer and an insulating layer. The characteristics of this substrate were as shown in Table 1.

Example 4 In a container equipped with a stirrer, a reflux condenser, and a nitrogen inlet tube, 1.
8-bis(8-aminophenoxy)benzene 14.6g
(0.05 mol) and 10.0 g (0.05 mol) of 4,4'-diaminodiphenyl ether were dissolved in 200 ml of N,N-dimethylacetamide, and 3.3 '.

4.4'-benzophenone tetracarbo/acid dianhydride 8
Add 2.2 g (0.1 mol) of i, and add about 2.2 g (0.1 mol) of i
Stirring was continued for 2 hours. The polyamic acid solution thus obtained was dried in the same manner as in Example 8 (final drying temperature 250°0
) to prepare a polyimide film. The thickness of this polyimide film was 25μ, and the residual solvent was 0.2%. This film was inserted between an electrolytic copper foil (85μ) and an Upilex S film (25μ) to laminate it, and using a vacuum press, it was heated to 280° and 0.20° with nitrogen.
9. Perform molding for 30 minutes at /a11. After cooling to room temperature, the Ubilex S film was peeled off from the laminated sheet to obtain a single-sided steel-clad flexible printed circuit board without using an adhesive layer. The characteristics of this substrate were as shown in Table-1.

Example 5 1. In a container equipped with a stirrer, a reflux condenser and a nitrogen inlet tube.
29.2 g of 3-bis(3-aminophenoxy)benzene (
0.1 mol) to N,N-dimethylacetamide 200
8,8' at room temperature under nitrogen atmosphere.
, 82.2 g (0.1 mol) of 4.4'-benzophenone tetracarboxylic dianhydride was added, and the mixture was stirred for about 20 hours under a nitrogen atmosphere.

The logarithmic viscosity of the polyamic acid solution obtained in this way is 1.7
It was 2 az/g. This polyamic acid solution was
- diluted with dimethylacetamide to 14 ml and reduced viscosity to 31 ml.
．． Adjusted to 000CP8. This solution was uniformly coated onto a smooth glass plate using a doctor blade. This coated glass plate was heated at 185°C for 1 hour to obtain a polyamic acid film. This film was peeled off from the glass plate, placed in a pin tenter, and reheated. At that time, heating was gradually carried out from 100'O to 240'O over 90 minutes. Thereafter, the temperature was kept at 2200 for 1 hour, and then cooled to room temperature to obtain a polyimide film. The film thickness was 25μ, and no residual solvent amount was detected. This polyimide film was coated with electrolytic steel foil (85μ) and aluminum foil (50μ).
), laminated and pressed at 280°○ with a hot press.
40 #, /! Molding was carried out for 80 minutes to obtain a single-sided copper-clad flexible printed circuit board with aluminum foil as a backing material to improve dimensional stability. The characteristics of this board are as shown in Table-1.

Comparative Example 1 4. In a container equipped with a stirrer, a reflux condenser, and a nitrogen introduction tube.
47-diamitsiphenyl ether 20.0g (0,1
mol) in 200 ml of N,N-dimethylacetamide, 21.8 g (0.1 mol) of pyromellitic dianhydride was added at 5°C under nitrogen atmosphere, and the mixture was stirred for about 2 hours, then cooled to room temperature. The mixture was returned to the original temperature and further stirred for about 20 hours. The logarithmic viscosity of the polyamic acid solution thus obtained was 1.64.
//g. This polyamic acid solution was diluted to 15% with N,N-dimethylacetamide, and the viscosity was adjusted to 28.0O
Adjusted to OCP8. 228 g of this solution was taken and mixed well with 88 g of the diluted solution obtained in Example 5 under a nitrogen atmosphere to obtain a polyamic acid solution with m-diamine: p-diamine = 0.2:0.8 (equivalent ratio). Ta. A polyimide film was prepared using this solution in the same manner as in Example 1 (final drying temperature 280 O). The thickness of this polyimide film is 2
5 μm, and the amount of residual solvent was 0.1 μm. Using this film, a single-sided steel-clad flexible printed circuit board was obtained in the same manner as in Example 2. The characteristics of this substrate were as shown in Table-1.

Comparative Example 2 In Example 2, a normal hot press was used instead of the vacuum press, and molding was carried out at 280" 0.40 yu/d for 40 minutes. After cooling to room temperature, Ubilex S film was laminated. The sheet was peeled off to obtain a single-sided steel-clad flexible printed circuit board without an adhesive layer.The characteristics of this board were as shown in Table 1.

〔Effect of the invention〕

According to the present invention, as described in the above embodiment, by using a polyimide film with excellent insulating properties and adhesive ability, it is possible to directly laminate the polyimide film on the metal foil, and the heat resistance and electrical properties and adhesion;
It has become possible to manufacture polyimide flexible printed circuit boards with metal foil cladding on one and both sides that have good mechanical properties such as flexibility and dimensional stability.

Claims (1)

[Claims] 1. A symmetrical aromatic primary amine group containing 100 to 20% of a symmetrical aromatic meta-substituted primary amine in an equivalent proportion is reacted with an aromatic tetracarboxylic acid anhydride. A method for manufacturing a flexible printed circuit board, characterized in that the produced polyimide film is used as an adhesive for laminating a metal foil and a thermosetting polyimide film. 2. The produced polyimide film is laminated by inserting the produced polyimide film between a non-adhesive film and metal foil, and the produced polyimide film is directly laminated on the metal foil under pressure and heat. A method according to claim 1. 3. Claim 1 in which the produced polyimide film is used as a laminating adhesive and insulating layer between metal foils
The method described in section. 4. The method according to claim 1, in which the produced polyimide film is used as an adhesive and insulating layer for laminating copper foil and metal foil. 5. The method according to any one of claims 1 to 4, wherein the lamination step is carried out by heating and pressurizing in an inert gas.