KR900003810B1 - Flexible printed circuit board and process for its production - Google Patents

Abstract

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Description

[Name of invention]

Flexible printed circuit board and its manufacturing method

Detailed description of the invention

[Technical Field]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flexible printed circuit board made of a polyimide metal sheet having excellent heat resistance, electrical characteristics, and mechanical characteristics, and a method of manufacturing the same.

[Background]

Flexible printed circuit boards are substrates for manufacturing flexible printed circuits, and in recent years, their use has increased due to miniaturization of cases in which printed circuits are included. Such a flexible printed circuit board was conventionally manufactured by bonding a polyimide film to a copper foil using an adhesive. In such a substrate, the polyimide film is sufficiently good in heat resistance, electrical characteristics and mechanical properties, but the characteristics of the polyimide film are not fully utilized because of insufficient adhesive properties.

Thus, a method of manufacturing a flexible printed circuit board made of a polyimide sheet metal sheet without using an adhesive has been conventionally tried. For example, US Pat. No. 3,179,634, Japanese Patent Laid-Open No. 129862/74, 190091/83, -190092/83, and the like. However, flexible printed circuit boards with sufficient heat resistance, adhesion and flexibility could not be obtained.

[Initiation of invention]

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and an object thereof is to provide a flexible printed circuit board made of a polyimide sheet of metal having excellent mechanical properties such as heat resistance, electrical properties, adhesiveness, and flexibility, and a method of manufacturing the same.

The present invention mixes a symmetrical aromatic metasubstituted primary diamine and a symmetrical aromatic parasubstituted primary diamine in an equivalent ratio of 10-60: 90-40, and reacts the mixture with an aromatic tetracarboxylic anhydride to give a polyimide precursor. A method of preparing a flexible printed circuit board which prepares amic acid, directly coats the organic solvent solution of the polyamic acid on metal foil, and dehydrates it by heating, or symmetrical aromatic metasubstituted primary diamine and aromatic tetracarboxylic anhydride. Reaction was carried out to prepare polyamic acid (A), symmetrical aromatic parasubstituted primary diamine and aromatic tetracarboxylic anhydride were reacted to prepare polyamic acid (B), and the organic solvent of the polyamic acid (A) The solution and the organic solvent solution of the polyamic acid (B) were mixed in an equivalent ratio of 10-60: 90-40, and then the solution was directly fixed to the metal foil. Open, and to a manufacturing method for the flexible printed circuit board produced by the method of the flexible printed circuit board of dehydration.

[Optimum embodiment of invention]

In addition, the present inventors have found that the flexible printed circuit board has better characteristics when the heating and dehydration is performed in an inert gas atmosphere.

In addition, the organic solvent solution of polyamic acid is directly coated on a metal foil, dried in a substantially tack-free state, wound in a roll shape, and heated and dehydrated in an inert atmosphere. It has been found that a flexible printed circuit board can be manufactured relatively simply and economically.

The symmetrical aromatic metasubstituted primary diamine (hereinafter abbreviated as m-diamine) used in the present invention is a general formula

(Wherein X is selected from O, SO ₂ , S, CO, CH ₂ , C (CH ₃ ) ₂ and C (CF ₃ ) ₂ , and each X may be the same).

As an example of m-diamine represented by the said general formula, 3, 3'- diamino diphenyl ether, 3, 3- diamino diphenyl sulfide, 3,3'- diamino diphenyl sulfone, 3,3'- Diamino benzophenone, bis [4- (3-aminophenoxy) -phenyl] methane, 2,2-bis [4- (3-aminophenoxy) phenyl] propane, 2,2-bis [4- (3 -Aminophenoxy) phenyl-1,1-1,3,3,3-hexafluoropropane, 1,3-bis (3-aminophenoxy) benzene, 4,4'-bis (3-aminophenoxy ) Biphenyl, bis [4- (3-aminophenoxy) phenyl] ketone, bis [4- (3-aminophenoxy) phenyl] sulfide, bis [4- (3-aminophenoxy) phenyl] sulfone, Bis [4- (3-aminophenoxy) phenyl] ether, 4,4'-bis (3-aminophenylsulfonyl) diphenyl ether, 4,4'-bis (3-aminothiophenoxy) diphenyl Sulfone, 1,4-bis [4- (3-aminophenoxy) benzoyl] benzene, and the like. These m-diamines may be used alone or in combination of two or more thereof.

Symmetric aromatic para-substituted primary diamines (hereinafter abbreviated as P-diamines) are of the general formula

Wherein X is selected from O, SO ₂ , S, CO, CH ₂ , C (CH ₃ ) ₂ and C (CF ₃ ) ₂ and each X may be the same or different.

As an example of P-diamine represented by the said general formula, 4,4'- diamino diphenyl ether, 4,4'- diamino diphenyl sulfide, 4,45 degrees diamino diphenyl sulfone, 4,4'- Diaminobenzophenone, bis [4- (4-aminophenoxy) phenyl] methane, 2,2-bis [4- (4-aminophenoxy) phenyl] propane, 2,2-bis [4- (4- Aminophenoxy) phenyl] -1, 1-1, 3, 3, 3-hexafluoropropane, 1,3-bis (4-aminophenoxy) benzene, 4,4'-bis (4-aminophenoxy ) Biphenyl, bis [4- (4-aminophenoxy) phenyl] ketone, bis [4- (4-aminophenoxy) phenyl] sulfoxide, bis [4- (4-aminophenoxy) phenyl] sulfone, Bis [4- (4-aminophenoxy) phenyl] ether, 4,4'-bis (4-aminophenylsulfonyl) diphenyl ether, 4,4'-bis (4-aminothiophenoxy) diphenyl Sulfone, 1,4-bis [4- (4-aminophenoxy) benzoyl] benzene, and the like, and these P-diamines may be used alone or in combination of two or more thereof.

As aromatic tetracarboxylic anhydride reacted with the diamine mentioned above, pyromellitic dianhydride, 3,3 ', 4,4'- benzophenone tetracarboxylic dianhydride, 2,2', 3,3'- benzo Phenonetetracarboxylic dianhydride, 3,3 ', 4,4'-biphenyltetracarboxylic dianhydride, 2,2', 3,3'-biphenyltetracarboxylic dianhydride, 2,2- Bis (3,4-dicarboxyphenyl) propane dianhydride, 2,2-bis (2,3-dicarboxyphenyl) propane dianhydride, bis (3,4-dicarboxyphenyl) ether dianhydride, bis (3, 4-dicarboxyphenyl) sulfone dianhydride, 1, l-bis (2,3-dicarboxyphenyl) ethane dianhydride, bis (2,3-dicarboxyphenyl) methane dianhydride, bis (3,4-dicarboxy Phenyl) methane dianhydride, 2,3,6,7-naphdalenetetracarboxylic dianhydride, 1,4,5,8-naphdalenetetracarboxylic dianhydride, 1,2,5,6-naphthalenetetra Carboxylic dianhydride, 1,2,3,4-benzene tetracarboxylic dianhydride, 3,4,9,10-perylene tetraca Include acid dianhydride, 2,3,6,7-anthracene Kane trad dianhydride, phenanthrene-1,2,7,8- tetracarboxylic acid dianhydride is used. These can be used individually or in mixture of 2 or more types.

As the organic solvent used for the purpose of polymerization and coating, for example, N-methyl-2-pyrrolidone, N, N-dimethylacetamide, N, N-dimethylformamide, 1,3-dimethyl-2- Imidazolidinone, N, N-diethylacetamide, N, N-dimethylmethoxyacetamide, dimethylsulfoxide, pyridine, dimethylsulfone, hexamethylphosphoamide, tetramethylurea, N-methylcaractam, Tetrahydrofuran, m-dioxane, P-dioxane, 1,2-dimethoxyethane, bis (2-methoxyethyl) ether, 1,2-bis (2-methoxyethoxy) ethane, bis [2 -(2-methoxyethoxy) ether] ether and the like.

In the polyamic acid used in the present invention, m-diamine and P-diamine are used in the organic solvent, and the equivalent ratio of m-diamine and P-diamine is 0.1-0.6: 0.9-0.4, preferably 0.2-0.4: 0.8-0.6 Usually at -20 ° C to 100 ° C, preferably at 0 ° C to 40 ° C, and then at lower temperatures than the boiling point of the aromatic tetracarboxylic anhydride and the solvent used from -20 ° C, preferably 0 It is prepared by reacting for 10 minutes or more at 1 DEG C to 40 DEG C, preferably 1 to 48 hours (Method 1), or at a temperature lower than the boiling point of the solvent used from -20 DEG C to m-diamine and aromatic tetracarboxylic anhydride. At a temperature of 0 ° C. to 40 ° C. for at least 10 minutes, preferably 1 to 48 hours, to prepare a polyamic acid (A), wherein the P-diamine and the aromatic tetracarboxylic anhydride are The polyamic acid (B) was prepared in the same manner as the acid (A) Johann then, (A) and the (B) equivalent ratio of 0.1 to 0.6 in terms of a diamine: prepared by mixing a 0.8 to 0.6 (Method 2): from 0.9 to 0.4, preferably 0.2-0.4. The polyamic acid solution obtained by the above method has a polyamic acid concentration of 5 to 50%. Among these two methods, the method (1) can obtain particularly good results in terms of mechanical properties and the like. If the equivalence ratio of m-diamine is 60% or more, the resulting polyimide will have a strong thermoplasticity, and the printed wiring board will have disadvantages that are difficult to handle. In particular, the tube of such a printed wiring board may be easily damaged by the polyimide film being in direct contact with the soldering iron (300-350 ° C), or may be deformed when the substrate is immersed in a high temperature solder solution bath (280 ° C or higher). If the equivalent ratio of m-diamine is 10% or less, the resulting polyimide film may be inadequate practically because the adhesion to the metal foil is weak, and the printed wiring board is likely to be peeled off from the film.

Of the various combinations of diamines used in the production of polyamic acids, m-diamine is described in claims 11, i.e.

Particularly preferred are compounds represented by (wherein X represents O, SO ₂ , S, CO, CH ₂ , C (CH ₃ ) ₂ , C (CF ₃ ) ₂ or a direct link). On the other hand, P-diamine is particularly preferred 4,4'-diaminophenyl ether. And / or 4,4'-bis (4-aminophenoxy) biphenyl. The aromatic tetracarboxylic anhydride is particularly preferably pyromellitic dianhydride and / or 3,3 ', 4,4'-benzophenonetetracarboxylic dianhydride. The use of these results in a flexible printed circuit board having excellent mechanical properties such as heat resistance, electrical properties, adhesiveness, and flexibility.

In order to coat the polyamic acid solution on the metal foil, the polyamic acid may be used directly or after dilution with the organic solvent described above. From the physical properties of the produced polyimide, the coating properties of the polyamic acid and the economics of the drying process, the polyamic acid is more preferably 5 to 40% by weight, preferably 10 to 30% by weight, and has an algebraic viscosity (35 ° C., concentration 0.59 / It is preferable to use a polyamic acid solution having 100 ml, measured in N, N-dimethylacetamide), preferably 0.1 to 4 dl / g, more preferably 0.5 to 6 dl / g. As a simpler method, the viscosity of the polyamic acid can be roughly measured using a rotational viscometer at the time of application. In this case, the preferred range is 100 to 500,000 cps.

Generally, copper foil or aluminum foil is used for the metal foil coated with polyamic acid. However, other conductive metal foils such as nickel foil can also be used.

The operation of coating the polyamic acid solution on the metal foil is preferably carried out by casting. Specifically, the polyamic acid solution is discharged from the slit for forming a film on the surface of the metal foil to form a coating layer having a uniform thickness. The final polyimide coating layer obtained by adjusting the thickness of the coating layer will have a thickness of 10-1000 μm. If the thickness is 10 mu m or less, the flexible printed circuit board will not have adequate strength, and if it is 1000 mu m or more, the substrate will be weak in flexibility. In order to obtain a polyimide coating layer having a thickness of 10 to 1000 mu m, the polyamic acid solution should generally be applied to a thickness of 30 to 3000 mu m.

It is also possible to use other known coating means such as roll coaters, knife coaters, comma coaters, doctor blades, fIow coaters and the like.

The polyamic acid coating film layer formed as described above is heated to perform desolvent and dehydration condensation reaction. This operation can be performed under arbitrary conditions, such as normal pressure, reduced pressure, and pressurization. As the heating method, hot heating, infrared heating, far infrared heating, or the like may be used, and these heating methods may be mixed and used. Generally, most solvents are removed by heating at 100 to 200 ° C., preferably at 100 to 150 ° C. for 3 to 600 minutes, preferably 4 to 180 minutes, more preferably 5 to 60 minutes. The mixture is then heated at 180 to 350 ° C. for 2 to 600 minutes, preferably 3 to 180 minutes, more preferably 5 to 120 minutes to completely remove the solvent and convert the polyamic acid to a more stable polyimide. If the metal foil coated in the desolvent and dehydration process is exposed to a temperature higher than the temperature at which the metal foil surface is oxidized, the mechanical properties, electrical properties, and adhesion of the metal foil are degraded due to oxidation of the metal foil surface. Therefore, above the temperature at which the metal foil surface is oxidized, it is best to prevent the oxidation of the metal foil surface by performing a desolvent and dehydration process in an inert gas atmosphere such as nitrogen, helium, neon, argon, or the like. The inert gas used herein refers to a gas atmosphere in which the metal foil surface is not subjected to substantial oxidation reaction when the metal foil is heated for a predetermined time, which adversely affects electrical properties or adhesion. This depends on the heating temperature but generally the inert gas atmosphere means a gas atmosphere with an oxygen content of 10% or less, preferably 6% or less, more preferably 4% or less.

The above-described heating and drying step is usually performed while spreading the coated metal foil. However, according to the present invention, after directly fixing the organic solvent solution of polyamic acid on the metal foil, it is dried in a substantially semi-dried state (until the solvent content of the coating layer is 40% by weight or less), and wound into a roll shape. It is also possible to heat this under an inert atmosphere to desolvent and dewater.

The flexible printed circuit board made of the polyimide metal sheet produced by the above-described method of the present invention does not contain an adhesive layer, and is excellent in heat resistance, mechanical properties, and electrical properties because excellent polyimide is used.

Since the flexible printed circuit board of the present invention is manufactured by laminating a polyimide film directly on a metal foil such as copper foil or without the use of an adhesive, heat resistance, electrical properties, adhesiveness, flexibility, etc. Excellent mechanical properties Therefore, it is very useful for the manufacture of electric circuits requiring excellent heat resistance, electrical insulation properties, dielectric properties, adhesion and breakdown strength.

EXAMPLE

The present invention and its effects will be described in detail as examples and comparative examples of the present invention.

The logarithmic viscosity in Examples was measured at 35 ° C., 0.5 g / 100 ml, N, N-dimethylacetamide, and the rotational viscosity was measured at 25 ° C. using a high viscosity rotor of an E-viscosity meter. Various performance characteristics of the printed circuit board were measured by the method described below.

(1) peeling strength

It measured according to the method of IPC-FC-241A.

(2) surface resistance

It measured according to JIS C-6481.

(3) resistance to soldering

Resistance to soldering was measured in accordance with JISC-6481. Specifically, after the sample was deposited for 60 seconds in a solder bath at 280 ° C., swelling and deformation of the polyimide film were observed.

(4) resistance to manual soldering

Using a soldering iron with a curvature radius of 0.5 mm and a taper angle of 30 °, the load to the tip was adjusted to 100 g. The temperature at the tip was adjusted to be 325 ± 25 ° C., and the soldering iron was erected vertically on a film composed of polyimide (thickness 25 μm). When the soldering iron was left in contact for 5 seconds or more, the resistance to the manual solder member was good, and the case of breaking within 5 seconds was evaluated as x.

(5) Folding endurance

According to JIS P-8115, the curvature radius of the curved surface was measured at 0.8 mm and a static load of 500 g.

(6) dielectric constant and dielectric loss rate

It carried out at the frequency of 1 KHz according to JIS C-6481.

Example 1

23.4 g (0.08 mol) of 1,3-bis (3-aminophenoxy) benzene and 24.0 g (0.12 mol) of 4,4'-diaminodiphenyl ether were added to a vessel equipped with a stirrer, a reflux cooler and a nitrogen introduction tube. It was dissolved in 420m1 of N-dimethylacetamide. 64.4 g (0.02 mol) of 3,3 ', 4,4'- benzophenone tetracarboxylic dianhydride are added to this solution under nitrogen atmosphere, and this mixture was stirred at 10 degreeC for 24 hours, and the polyamic-acid solution was carried out. Got. The algebraic viscosity of this solution was 1.5 dl / g. The polyamic acid solution was diluted in N, N-dimethylacetamide to a polyamic acid concentration of 15%, the viscosity was adjusted to 25000 cps, and the diluted solution was uniformly coated on the rolled copper foil (thickness 35 µm) using a doctor blade. . The coated copper foil was heated and dried at 130 ° C. for 60 minutes, and then heated for 60 minutes under a nitrogen atmosphere (oxygen concentration of 4%) at 260 ° C. to obtain a copper foil coated with polyimide. The film thickness was 25 micrometers. Table 1 shows the characteristics of this printed circuit board.

Example 2

In a vessel equipped with a stirrer, a reflux condenser and a nitrogen introduction pipe, 22.1 g (0.06 mol) of 4,4'-bis (3-aminophenoxy) biphenyl and 28.0 g (0.14 mol) of 4,4'-diaminodiphenyl ether ) Was dissolved in 350 ml of N, N-dimethylacetamide. After cooling this solution to about 0 degreeC, 43.6 g (0.20 mol) of pyromellitic dianhydrides were added to it under nitrogen atmosphere, and it stirred at about 0 degreeC for 2 hours. The mixture was then returned to room temperature and stirred for 20 hours under a nitrogen atmosphere. The logarithmic viscosity of the polyamic acid solution thus obtained was 1.7 dl / g. This polyamic acid solution was hydrated in N, N-diketylacetamide to a polyamic acid concentration of 19% to adjust the dilution viscosity to 120000 cps.

The solution was uniformly applied to the rolled copper foil (35 μm in thickness) by casting, heat dried at 130 ° C. for 10 minutes, and further dried at 160 ° C. for 10 minutes, and then under nitrogen atmosphere of 270 ° C. (oxygen concentration 3%). It heated for 10 minutes and obtained the copper foil which coated polyimide. The film thickness was 25 micrometers. Table 1 shows the characteristics of this printed circuit board.

Example 3

The copper foil coated with polyimide was obtained in the same manner as in Example 2 except that the coated copper foil was used at an oxygen concentration of 8% when drying at 270 ° C. Table 1 shows the characteristics of this printed circuit board.

Example 4

In the same manner as in Example 2, except that 51.6 g (0.14 mol) of 4,4 ° bis (4-aminophenoxy) biphenyl was used instead of 28.0 g of 4,4'-diaminodiphenyl ether used in Example 2. To prepare a polyamic acid solution. The logarithmic viscosity of the polyamic acid solution thus prepared was 1.6 dl / g. The polyamic acid solution was diluted to 18% polyamic acid concentration in N, N-dimethylacetamide, and the rotational viscosity was adjusted to 105000 cps.

The solution was uniformly coated on a rolled copper foil (35 μm in thickness) by casting, heated and dried at 130 ° C. for 20 minutes, and then dried by heating at 160 ° C. for 20 minutes, followed by a nitrogen atmosphere of 270 ° C. (oxygen concentration 3%). ) And it heated for 20 minutes, and obtained copper foil which coated polyimide. The film thickness was 25 micrometers. Table 1 shows the characteristics of this printed circuit board.

Example 5

In a vessel equipped with a stirrer, a reflux condenser and a nitrogen introduction tube, 31.7 g (0.08 mol) of bis [4- (3-aminophenoxy) phenyl ketone] and 24.0 g (0.12 mol) of 4,4'-diaminodiphenyl ether were added. It was dissolved in 400 ml of N, N-dimethylacetamide. 43.6 g (0.20 roll) of pyromellitic dianhydride was added to this solution under nitrogen atmosphere, and it stirred for 24 hours. The logarithmic viscosity of the polyamic acid solution thus obtained was 1.8 dl / g. The polyamic acid solution was diluted in N, N-dimethylacetamide to a polyamic acid concentration of 13% to adjust the rotational viscosity to 25000 cps, and the HTE electrolytic copper foil (manufactured by Mitsui Metal Mining Co., Ltd.) using a doctor blade. The diluted solution was uniformly coated on. The resultant was dried by heating at 130 ° C. for 10 minutes, and further dried by heating at l 60 ° C. for 10 minutes, and then heated under a nitrogen atmosphere at 270 ° C. for 10 minutes to obtain a polyimide-coated copper foil. The film thickness was 25 µm. Table 1 shows the characteristics of this printed circuit board.

Example 6

24.0 g (0.06 mol) of bis [4- (3-aminophenoxy) phenylsulfide and 4,4 ',-bis (4-aminophenoxy) biphenyl in a container equipped with a stirrer, a reflux condenser and a nitrogen introduction tube. g (0.14 mol) was dissolved in 420 ml of N, N-dimethylacetamide. 43.6 g (0.20 mol) of pyromellitic dianhydrides were added to this solution under nitrogen atmosphere, and it stirred for 24 hours. The logarithmic viscosity of the polyamic acid solution thus obtained was 2.1 dl / g. The polyamic acid solution was diluted with N, N-dimethylacetamide to a polyamic acid concentration of 12% to adjust the rotational viscosity to 45,000 cps, using a doctor blade to HTE electrolytic copper foil (thickness 35 μm; Mitsui Metal Mining Co.) The lime solution was uniformly coated on. The resultant was dried by heating at 130 ° C. for 10 minutes and further dried by heating at 160 ° C. for 10 minutes, and then heated under a nitrogen atmosphere (oxygen concentration of 3%) at 270 ° C. to obtain a polyimide-coated copper foil. The film thickness was 50 micrometers. Table 1 shows the characteristics of this printed circuit board.

Example 7

25.9 g (0.06 mol) of bis [4- (3-aminophenoxy) phenyl] sulfone was used instead of 24.0 g of bis [4- (3-aminomenoxy) phenyl] sulfide used in Example 6. A polyamic acid solution was prepared in the same manner as in Example 6, and the logarithmic viscosity of the polyamic acid solution was 2.0 dl / g. The solution was diluted with N, N-dimethylacetamide to a polyamic acid concentration of 13% to adjust the rotational viscosity to 40000 cps, after which the procedure of Example 6 was repeated to obtain a polyimide-coated copper foil. Table 1 shows the characteristics of this printed circuit board.

Example 8

2,2-bis [4- (3-aminophenoxy) phenyl] -1,1,1,3, instead of 24.0 g of bis [4- (3-aminomenoxy) phenyl] sulfide used in Example 6 A polyamic acid solution was prepared in the same manner as in Example 6 except that 31.1 g (0.06 mol) of 3,3-hexafluoropropane was used. The algebraic viscosity of the solution thus obtained was 1.2 dl / g. This solution was diluted to 18% polyamic acid concentration in N, N-dimethylacetamide to adjust the rotational viscosity to 45000 cps. Thereafter, the procedure of Example 6 was repeated to obtain a copper foil coated with polyimide. The characteristics of this printed circuit board are shown in Table 1.

Example 9

23.4 g (0.08 mole) of l, 3-bis (3-aminophenoxy) benzene was dissolved in 200 ml of N, N-dimethylacetamide in a vessel equipped with a stirrer, a reflux condenser and a nitrogen introduction tube. 25.7 g (0.08 mol) of 2, anhydrous mol of 3,3 ', 4,4'- benzophenone tetracarboxylic acid was added to this solution under nitrogen atmosphere, and it stirred at room temperature for 24 hours, and obtained the polyamic-acid solution. The algebraic viscosity other than the polyamic acid solution thus obtained was 1.8 dl / g. This solution is labeled as solution A.

On the other hand, 24.0 g (0.12 mol) of 4,4'- diaminophenyl ether was dissolved in 250 ml of N, N-dimethylacetamide. 38.7 g (0.12 mol) of 3,3'-4,4'-benzophenone tetracarboxylic dianhydride was added to this solution under nitrogen atmosphere, and it stirred at room temperature for 24 hours, and obtained the polyamic-acid solution. The algebraic viscosity of the polyamic acid solution thus obtained was 1,6 dl / g. This solution is called solution B.

Next, 59 g of Solution A and 74 g of Solution B were mixed to adjust the equivalence ratio between the polyamic acid of Solution A and the polyamic acid of Solution B to 40:60. The solution was diluted with N, N-dimethylacetamide to 14% of the polyalimic acid concentration to adjust the viscosity to 26000 cps, and the diluted solution was uniformly coated on the rolled copper foil (thickness 35 µm) using a doctor blade. The resultant was dried at 150 ° C. for 60 minutes and heated for 30 minutes under a nitrogen atmosphere (oxygen concentration of 3%) at 260 ° C. to obtain a copper foil coated with polyimide. The film thickness was 25 micrometers. Table 1 shows the characteristics of this printed circuit board.

Example 10

22.lg (0.06 mol) of 4,4'-bis (3-aminophenoxy) biphenyl was dissolved in 150 ml of N, N-dimethylacetamide in a vessel equipped with a stirrer, a reflux condenser and a nitrogen introduction tube. 13.lg (0.06 mol) of pyromellitic dianhydrides were added to this solution under nitrogen atmosphere, and it stirred at room temperature for 24 hours, and obtained the polyamic-acid solution. The logarithmic viscosity of the polyamic acid solution thus obtained was 1.7 dl / g. This solution is called solution C.

On the other hand, 28.0 g (0.14 mol) of 4,4'-diaminodiphenyl ether was dissolved in 240 ml of N, N-dimethylacetamide. 30.5 g (0.14 mol) of pyromellitic dianhydrides were added to this solution under nitrogen atmosphere, and this mixture was stirred at room temperature for 24 hours, and the polyamic-acid solution was obtained. The logarithmic viscosity of the polyamic acid solution thus obtained was 1.6 dl / g. This solution is called solution D.

Next, 44 g of solution C and 71 g of solution D were mixed to adjust the equivalent ratio of polyamic acid of solution C and polyamic acid of solution D to 30:70. The solution was diluted with N, N-dimethylacetamide to a polyamic acid concentration of 15% to adjust the viscosity to 30000 cps. Then, the diluted solution was uniformly coated on the rolled copper foil (thickness 35 mu m) using a doctor blade. After drying this at 150 degreeC for 60 minutes, it heated for 30 minutes in 260 degreeC nitrogen atmosphere (oxygen concentration 3%), and obtained the copper foil which coated polyimide. The film thickness was 25 micrometers. Table 1 shows the characteristics of this printed circuit board.

Comparative Example 1

58.4 g (0.20 mol) of 1,3-bis (3-aminophenoxy) benzene was dissolved in 430 ml of N, N-dimethylacetamide in a vessel equipped with a stirrer, a reflux condenser and a nitrogen introduction tube. 64.4 g (0.20 mol) of 3,3 ', 4,4'- benzophenone tetracarboxylic dianhydride was added to this solution under nitrogen atmosphere, and this mixture was stirred at 10 degreeC for 24 hours, and the polyamic-acid solution was obtained. The algebraic viscosity of the polyamic acid solution thus obtained was 1.4 dl / g. The polyamic acid solution was diluted with N, N-dimethylacetamide to 18% polyamic acid concentration to adjust the rotational viscosity to 27000 cps. Then, the diluted solution was uniformly coated on the rolled copper foil (thickness 35 μm) using a doctor blade. After drying this at 130 degreeC for 60 minutes, it heated for 60 minutes in 240 degreeC nitrogen atmosphere (oxygen concentration 4%), and obtained the copper foil which coated polyimide. The film thickness was 25 micrometers. Table 2 shows the characteristics of this printed circuit board.

Comparative Example 2

In a vessel equipped with a stirrer, a reflux condenser and a nitrogen introduction tube, 73.6 g (0.20 mol) of 4,4'-bis (4-aminophenoxy) biphenyl was dissolved in 400 ml of N, N-dimethylacetamide. After cooling this solution at about 0 degreeC, 43.6 g (0.20 mol) of pyromellitic dianhydrides were added to it under nitrogen atmosphere, and it stirred at about 0 degreeC for 2 hours. The mixture was then returned to room temperature and stirred for about 20 hours under a nitrogen atmosphere. The algebraic viscosity of the polyamic acid solution thus obtained was 1,6 dl / g. The polyamic acid solution was diluted with N, N-dimethylacetamide to a polyamic acid concentration of 18% to adjust the rotational viscosity to 110,000 cps.

This solution was apply | coated uniformly to the rolled copper foil (35 micrometers in thickness) by casting. The resultant was dried by heating at 130 ° C. for 10 minutes and further dried by heating at 160 ° C. for 10 minutes, and then heated under a 270 ° C. nitrogen atmosphere (oxygen concentration of 3%) for 10 minutes to obtain a polyimide-coated copper foil. The film thickness was 25 micrometers. Table 2 shows the characteristics of this printed circuit board.

TABLE 1

TABLE 2

Claims (14)

After symmetrical aromatic metasubstituted primary diamine and symmetrical aromatic parasubstituted primary diamine are mixed in an equivalent ratio of 10-60: 90-40, the polyamide film produced by reacting with aromatic tetracarboxylic anhydride is directly bonded to the metal foil. Flexible printed circuit board, characterized in that. A polyamic acid (A) is prepared by reacting a symmetrical aromatic metasubstituted primary diamine and an aromatic tetracarboxylic anhydride, and a polyamic acid (B is reacted by reacting a symmetrical aromatic parasubstituted primary diamine and tetracarboxylic anhydride. ), And the polyamide acid (A) and the polyamic acid (B) are mixed and mixed in an equivalent ratio of 10-60: 90-40 to react the resulting polyamide film directly with a metal foil. Printed circuit board. The flexible printed circuit board of claim 1, wherein the polyimide layer has a thickness of 10 μm to 1 mm. The flexible printed circuit board of claim 2, wherein the polyimide layer has a thickness of 10 μm to 1 mm. In the method of manufacturing a flexible printed circuit board, a symmetrical aromatic metasubstituted primary diamine and a symmetrical aromatic parasubstituted primary diamine are mixed in an equivalent ratio of 10-60: 90-40, and then reacted with an aromatic tetracarboxylic anhydride. A polyamic acid is prepared as a precursor of a polyimide, the organic solvent solution of the polyamic acid is directly coated on a metal foil, and then the coated metal foil is heated and dehydrated to manufacture a flexible printed circuit board. In the method of manufacturing a flexible printed circuit board, a polyamic acid (A) is prepared by reacting a symmetrical aromatic metasubstituted primary diamine and an aromatic tetracarboxylic anhydride, and a symmetrical aromatic parasubstituted primary diamine and an aromatic carboxyl. The acid anhydride is reacted to produce polyamic acid (B), and the organic solvent solution of the polyamic acid (A) and the organic solvent solution of the polyamic acid (B) are mixed in an equivalent ratio of 10-60: 90-40. And directly coating the mixture on the metal foil, and then heating the dehydrated coated metal foil to produce a flexible printed circuit board. The method of manufacturing a flexible printed circuit board according to claim 5, wherein the heating and dehydration step is performed in an inert gas atmosphere. The method of manufacturing a flexible printed circuit board according to claim 6, wherein the heating and dehydration step is performed in an inert gas atmosphere. 6. The substrate prepared by directly coating the polyamic acid organic solvent solution on a metal foil is dried to a substantially semi-cured dry state and wound in a roll shape, and the roll-shaped substrate is ball-activated. A method for manufacturing a flexible printed circuit board, characterized in that the polyamic acid is converted to polyimide by heating under an atmosphere to remove the solvent. The laminate according to claim 6, wherein the laminate obtained by directly coating the mixed solution of the organic solvent solution of the polyamic acid (A) and the organic solvent solution of the polyamic acid (B) on a metal foil is dried in a semi-cured and dried state. And a roll-shaped laminate is heated in an inert gas atmosphere to remove the solvent to convert the polyamic acid into a polyimide. The method of claim 1, wherein the symmetrical aromatic metasubstituted primary diamine is formula (1)

(Wherein X represents O, SO ₂ , S, CO, CH ₂ , C (CH ₃ ) ₂ , C (CF ₃ ) ₂ or a direct bond). The method of claim 2, wherein the symmetric aromatic metasubstituted primary diamine is represented by Formula (1)

(Wherein X represents O, SO ₂ , S, CO, CH ₂ , C (CH ₃ ) ₂ , C (CF ₃ ) ₂ or a direct bond). Manufacturing method. 4. A method according to claim 3, wherein the symmetric aromatic metasubstituted primary diamine is of formula (1).

(Wherein X represents O, SO ₂ , S, CO, CH ₂ , C (CH ₃ ) ₂ , C (CF ₃ ) ₂ or a direct bond); Manufacturing method. The method of claim 4, wherein the symmetric aromatic metasubstituted primary diamine is represented by Formula (1)

Wherein X represents O, SO ₂ , S, CO, CH ₂ , C (CH ₃ ) ₂ , C (CF ₃ ) ₂ or directly connected) Method for producing a flexible printed circuit board characterized in that the compound is displayed.