JPH04256394A - Manufacture of flexible wiring board - Google Patents

Abstract

PURPOSE:To effectively obtain a flexible circuit board made of polyimide having excellent curling properties and adhesive strength and a metal foil by directly coating the foil with special polyamic acid varnish, then removing solvent by drying, and forming imide. CONSTITUTION:After a metal foil is coated directly with polyamic acid varnish obtained by polymerizing tetracarboxylic acid dianhydride component containing 20mol% to less than 50mol% of 3,3',4,4'-biphenyltetracarboxylic acid bianhydride (A) and pyromellitic acid bianhydride (B), and 10-40mol% of 3,3',4,4'- benzphenonetetracarboxylic acid bianhydride (C) in such a manner that total of the bianhydride (A) and the bianhydride (B) is 60-90mol%, and diamine component containing 80mol% or more of p-phenylenediamine and 4,4'- diaminodiphenylether (100:0-40:60 of a range of molar ratio), solvent is removed by drying, and imide is formed.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a flexible wiring board made of polyimide and metal foil and having excellent heat resistance, electrical properties, chemical resistance and mechanical properties.

0002

2. Description of the Related Art Conventionally, flexible wiring boards have been manufactured by laminating a polyimide film and metal foil together with an adhesive. The various properties of such flexible wiring boards are determined by the performance of the adhesive layer, which is inferior to polyimide, despite the use of polyimide films that have excellent heat resistance, electrical properties, chemical resistance, and mechanical properties. For example, although the heat resistance of polyimide is 350°C or higher, the solder heat resistance of flexible wiring boards is usually 300°C or lower.

[0003] As a method to solve such problems,
A method of directly forming a polyimide layer on metal foil without using an adhesive is being considered. A representative example of this is obtained by polymerizing a tetracarboxylic dianhydride component such as pyromellitic dianhydride shown in US Pat. No. 3,179,634 and a diamine component consisting of an aromatic primary diamine. This is a method in which a polyamic acid varnish is applied directly to a metal foil, and then the solvent is removed by drying and imidization is performed. This method causes problems such as curling due to curing shrinkage after imidization. In order to solve this problem, in Special Publication No. 64-6556, 3,3', 4,4'
- A method for curing a polyamic acid varnish obtained by polymerizing a biphenyltetracarboxylic dianhydride component and a symmetrical aromatic diamine component having no substituents on a metal foil, in JP-A No. 60-210894. 4,4'-
A polyamic obtained by polymerizing a diamine component having a molar ratio of diaminodiphenyl ether and p-phenylenediamine of 50:50 to 10:90 and a tetracarboxylic dianhydride component containing 50 mol% or more of pyromellitic dianhydride. A method of curing acid varnish on metal foil, Japanese Patent Publication No. 63-30143 describes a polyamic acid varnish whose main components are 3,3',4,4'-biphenyltetracarboxylic dianhydride and p-phenylenediamine. There are methods such as curing on metal foil. However, even with these methods, there are problems such as weak adhesion between the copper foil and polyimide for materials with small curls, and large curls for materials with strong adhesive strength, making it difficult to achieve both adhesion and curl. It is.

0004

[Problems to be Solved by the Invention] As a result of studying ways to improve the drawbacks of the prior art, the present inventors have found that both curling and adhesive strength can be achieved by controlling the composition of the tetracarboxylic dianhydride component and the diamine component. This is what we discovered and arrived at the present invention.

[0005]

[Means for Solving the Problems] The objects of the present invention are achieved by the following configuration.

3,3',4,4'-biphenyltetracarboxylic dianhydride from 20 mol% to less than 50 mol%, pyromellitic dianhydride from 20 mol% to less than 50 mol%, 3,3' , 4,4'-benzophenonetetracarboxylic dianhydride in a range of 10 mol% or more and 40 mol% or less, and 3,3',4,4'-biphenyltetracarboxylic dianhydride and pyromellitic dianhydride. A tetracarboxylic dianhydride component containing a total of 60 mol% or more and 90 mol% or less of anhydrides, p-phenylenediamine and 4,4'-diaminodiphenyl ether (molar ratio range 100:0 to 4)
A flexible wiring characterized in that a polyamic acid varnish obtained by polymerizing a diamine component containing 80 mol% or more of 0:60) is applied directly to a metal foil, and then the solvent is dried and removed and imidized. Substrate manufacturing method.

That is, the polyamic acid varnish in the present invention is obtained by polymerizing a tetracarboxylic dianhydride component and a diamine component.

[0008] As the tetracarboxylic dianhydride component, 3
, 3',4,4'-biphenyltetracarboxylic dianhydride from 20 mol% to less than 50 mol%, preferably from 30 mol% to 45 mol%, and pyromellitic dianhydride from 2 to 50 mol%.
0 mol% or more and less than 50 mol%, preferably 30 mol% or more and 45 mol% or less, 3,3',4,4'-benzophenonetetracarboxylic dianhydride 10 mol% or more and 40 mol%
The following is preferably included in the range of 10 mol% or more and 30 mol% or less, and the total of 3,3',4,4'-biphenyltetracarboxylic dianhydride and pyromellitic dianhydride is 60
mol% or more and 90 mol% or less, preferably 70 mol% or more9
It must be contained in a range of 0 mol% or less. In addition, a small amount of a tetracarboxylic dianhydride component such as 3,3',4,4'-diphenyl ether tetracarboxylic dianhydride may be added as long as the properties are not deteriorated.

The diamine component may contain 80 mol% or more of p-phenylene diamine and 4,4'-diaminodiphenyl ether (molar ratio range 100:0 to 40:60); Diaminodiphenylthioether, m-phenylenediamine, 3,3'-diaminodiphenylsulfone, 9,9'-bis(4-aminophenyl)fluorene, 1,3-bis(3-aminophenoxy)benzene, 1,4-bis (4-aminophenoxy)benzene, 4,4'-bis(4-aminophenoxy)biphenyl, 2,2'-[4-(4-aminophenoxy)phenyl]propane, 1,5-diaminonaphthalene, 4,4 '-Diaminodiphenylmethane, benzidine, 2,7-diaminodiphenylfluorene, 3,3'-
It may also contain aromatic diamines such as dimethylbenzidine and 3,3'-dimethythoxybenzidine, or diaminosiloxanes such as bis(3-aminopropyl)tetramethyldisiloxane.

[0010] As the polymerization method, a known method may be used, for example, a method in which the diamine component is dissolved in a polymerization solvent, and then the tetracarboxylic dianhydride component is added and polymerized.

The polymerization solvent for the polyamic acid may be any aprotic solvent in which the tetracarboxylic dianhydride component, the diamine component, and the polyamic acid product are soluble. Such solvents include N
, N-dimethylacetamide, N-methyl-2-pyrrolidone, N,N-dimethylformamide, and N,N-diethylformamide are particularly preferred, and other preferred examples include dimethyl sulfoxide, butyllactone, sulfolane, and methylsulfolane. These solvents may be used alone or in combination of two or more, and benzene, toluene, hexane, cyclohexanone, tetrahydrofuran, dioxane, methyl ethyl ketone, etc. may also be added as long as the polyamic acid does not precipitate.

The concentration of the polyamic acid varnish is preferably 5 to 60% by weight, particularly preferably 10 to 30% by weight.

[0013] The reaction temperature is preferably -10 to 100°C,
Particularly preferred is 0 to 80°C. In order to increase the degree of polymerization, a low temperature is preferable, but in terms of reaction rate or solubility of raw materials, a high temperature is better as long as imidization does not proceed, and the above temperatures are preferable.

Copper foil is generally used as the metal foil to which the polyamic acid varnish is applied, but conductive metal foils such as aluminum foil, nickel foil, and iron foil may also be used. The thickness is preferably 10 to 100 microns, and the surface in contact with the polyamic acid varnish is preferably roughened.

[0015] General coating means such as a slit die and a roll coater are used for coating the polyamic acid varnish.

[0016] Dry removal of the solvent is usually carried out at a temperature below 170°C, and imidization is carried out at a temperature in the range of 170 to 400°C. These steps may be performed separately or consecutively. Further, it may be carried out in air or in an inert gas such as nitrogen, but in order to avoid oxidation of the metal foil, an inert gas is preferred. Furthermore, during imidization, a dehydrating agent consisting of an amine, acetic anhydride, or the like may be used.

Furthermore, the polyamic acid varnish may contain a small amount of a coating improver, an adhesion improver, a filler, etc., if necessary.

[0018]

[Examples] The present invention will be explained in detail below based on Examples, but the present invention is not limited thereto. The measurements of curl and adhesion during the experiment were carried out using the following methods.

[Measurement of Curl] After cutting the imidized sample into 10 cm square pieces, the copper-clad film was placed on a flat plate, and the average length of the four corners was measured. If the curl was too large to measure the length of lift, the number of turns curled was displayed. Moreover, the direction of curl is shown as negative when the copper foil is placed inside, and positive when it is placed outside.

[Measurement of Adhesive Strength] According to JISC-6471, 90 degree peeling of a sample with a width of 5 mm was measured using a Tensilon at a tensile speed of 50 mm/min.

Example 1 The reaction was carried out under a nitrogen stream. N,N-
After dissolving in 207.80 g of dimethylacetamide,
8.72 g (0.04 mol) of pyromellitic dianhydride and 11.77 g (0.04 mol) of 3,3',4,4'-biphenyltetracarboxylic dianhydride, 3,3',4, 4
´-benzophenone tetracarboxylic anhydride 6.44g
(0.02 mol) was added and reacted by stirring at 50°C for 3 hours to obtain a polyamic acid varnish with a viscosity of 105ps (25°C).

[0022] This varnish was applied onto a copper foil of 18 microns, heated at 80°C for 30 minutes, heated from 80°C to 150°C for 30 minutes, heated at 150°C for 30 minutes, and heated from 150°C to 350°C for 30 minutes. The solvent was removed by drying and imidization was performed at 350° C. for 30 minutes. Table 1 shows the curl and adhesive strength evaluation results.

[0023]

[Table 1]

Example 2 7.57 g (0.07 mol) of p-phenylenediamine,
4,4'-diaminodiphenyl ether 6.01g (0
．． 03 mol), pyromellitic dianhydride 8.72 g (0
．． 04 mol), 3,3',4,4'-biphenyltetracarboxylic dianhydride 11.77 g (0.04 mol), 3
, 6.44 g (0.02 mol) of 3',4,4'-benzophenonetetracarboxylic acid anhydride was reacted in the same manner as in Example 1 in 184.5 g of N,N-dimethylacetamide, and evaluated in the same manner. The results are shown in Table 1.

Example 3 5.41 g (0.05 mol) of p-phenylenediamine,
4,4'-diaminodiphenyl ether 6.01g (0
．． 05 mol), pyromellitic dianhydride 9.81 g (0
．． 045 mol), 17.65 g (0.045 mol) of 3,3',4,4'-biphenyltetracarboxylic dianhydride
, 3.22 g (0.01 mol) of 3,3',4,4'-benzophenonetetracarboxylic acid anhydride was reacted in the same manner as in Example 1 in 159.52 g of N,N-dimethylacetamide, and evaluated in the same manner. The results are shown in Table 1.

Example 4 4,4'-diaminodiphenyl ether 4.04g (0
．． 02 mol), p-phenylenediamine 8.65 g (0
．． 08 mol) to 161.0 mol of N,N-dimethylacetamide.
After dissolving in 16g, pyromellitic dianhydride 7.6
3 g (0.035 mol) and 10.30 g (0.03 mol) of 3,3',4,4'-biphenyltetracarboxylic dianhydride.
5 mol), 3,3',4,4'-benzophenonetetracarboxylic anhydride (9.67 g (0.03 mol)) and reacted in the same manner as in Example 1. The results are shown in Table 1. Indicated.

Comparative Example 1 7.57 g (0.07 mol) of p-phenylenediamine,
4,4'-diaminodiphenyl ether 6.01g (0
．． 03 mol), pyromellitic dianhydride 15.27 g (
0.07 mol), 8.83 g (0.03 mol) of 3,3',4,4'-biphenyltetracarboxylic dianhydride was
, N-dimethylacetamide in 150.72 g in the same manner as in Example 1 and evaluated in the same manner. The results are shown in Table 1.

Comparative Example 2 2.76 g (0.0255 mol) of p-phenylenediamine, 11.91 g of 4,4'-diaminodiphenyl ether
g (0.0595 mol), 3,3',4,4'-biphenyltetracarboxylic dianhydride 25.00 g (0.08
50 mol) to N,N-dimethylacetamide 158.6
The reaction was carried out in the same manner as in Example 1 in 8 g and evaluated in the same manner. The results are shown in Table 1.

Comparative Example 3 7.57 g (0.07 mol) of p-phenylenediamine,
4,4'-diaminodiphenyl ether 6.01g (0
．． 03 mol), pyromellitic dianhydride 6.54 g (0
．． 03 mol) 20.59 g (0.07 mol) of 3,3',4,4'-biphenyltetracarboxylic dianhydride with N,
50 for 3 hours in 162.8 g of N-dimethylacetamide
Polyamic acid varnish was obtained by polymerization at ℃. Evaluations were made in the same manner as in Example 1, and the results are shown in Table 1.

Comparative Example 4 8.65 g (0.08 mol) of p-phenylenediamine,
4,4'-diaminodiphenyl ether 4.00g (0
．． 02 mol), pyromellitic dianhydride 8.72 g (0
．． 04 mol) 3,3',4,4'-benzophenonetetracarboxylic dianhydride (19.33 g (0.06 mol)) was polymerized in 162.8 g of N,N-dimethylacetamide at 50°C for 3 hours to form a polyamic acid. Acid varnish was obtained. Evaluations were made in the same manner as in Example 1, and the results are shown in Table 1.

From the curling and adhesive strength results of the copper-clad polyimide films of Examples and Comparative Examples summarized in Table 1, it can be seen that curling and adhesive strength are both compatible when the composition of the present invention is satisfied.

[0032]

[Effects of the Invention] Since the present invention is constructed as described above, it is possible to reliably obtain a flexible wiring board made of polyimide and metal foil that has excellent curling properties and adhesive properties.

Claims (1)

[Claims] Claim 1: 20 mol% or more and less than 50 mol% of 3,3',4,4'-biphenyltetracarboxylic dianhydride, 20 mol% or more and less than 50 mol% of pyromellitic dianhydride, 3, Contains 3',4,4'-benzophenonetetracarboxylic dianhydride in a range of 10 mol% or more and 40 mol% or less, and 3,3',4,4'-biphenyltetracarboxylic dianhydride and pyromellit A tetracarboxylic dianhydride component containing a total of acid dianhydrides of 60 mol% or more and 90 mol% or less, p-phenylenediamine and 4,4'-diaminodiphenyl ether (molar ratio range 100:0 to 4)
A flexible wiring characterized in that a polyamic acid varnish obtained by polymerizing a diamine component containing 80 mol% or more of 0:60) is applied directly to a metal foil, and then the solvent is dried and removed and imidized. Substrate manufacturing method.