JPH05299850A - Multilayered flexible printed wiring board - Google Patents

Abstract

PURPOSE:To provide a heat-resistant, multilayered printed-circuit board of polyisoimide resin with its layers of strong adhesion by laminating layers using adhesive polyimide films coated with a specific polyisoimide solution. CONSTITUTION:A polymer, which is obtained by the polymerization of an aromatic tetracarboxylic dianhydride with an excess of an aromatic diamine, is blocked with dicarboxylic dianhydride or its drivative at both terminals to obtain a polyamic acid, and it is converted into an isoimide. The polyimide solution thus obtained is applied to both surfaces of a polyimide film to provide an adhesive film. Flexible printed-wiring material having circuits on both sides are laminated with such having circuits on both sides are laminated with such adhesive films interposed and then they are hardened integrally to form a flexible printed wiring board. The adhesive film coated with the polyisoimide solution is heat-resistant and offers strong adhesion without a high-temperature treatment.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multilayer flexible printed wiring board, and more particularly to a double-sided flexible printed board having a polyimide film on which polyisoimide having excellent adhesion to copper foil and polyimide film is formed. The present invention relates to a multi-layer board configured by stacking a plurality of wiring boards.

[0002]

2. Description of the Related Art In recent years, with the development of the electronic and electric industries, simplification, miniaturization and high reliability of mounting methods for communication and consumer equipment have been demanded, and use of printed circuit boards has been desired. In particular, the use of a flexible printed circuit board which is light in weight and can be mounted three-dimensionally is advantageous and attracts attention. Furthermore, recently, the use of flexible printed circuit boards having a multilayer structure has been strongly desired. Conventionally, in manufacturing a flexible printed circuit board having a multilayer structure, an epoxy resin, an acrylic resin, or the like has been used as an adhesive layer. However, when these adhesive layers are used, the heat resistance of polyimide cannot be fully utilized. In addition, when polyamic acid is used for the adhesive layer of the multilayer flexible printed circuit board, when the drying conditions are mild, when the copper foils are bonded together, the water generated during imidization causes the copper foil to adhere to the copper foil. However, there is a drawback that blisters and wrinkles occur and, on the contrary, if the drying conditions are too strong, sufficient adhesive force cannot be obtained. Also, some examples using thermoplastic polyimide have been reported, but they are still insufficient in terms of adhesive strength and heat resistance.

[0003]

DISCLOSURE OF THE INVENTION The inventors have conducted research to obtain a multilayer flexible printed circuit board composed of a polyisoimide resin composition having excellent heat resistance and excellent adhesion to copper foil and other polyimide films. As a result, the present invention has been achieved.

[0004]

According to the present invention, an aromatic tetracarboxylic acid dianhydride component and an aromatic diamine component are polymerized in a state in which the diamine component is in excess, and then the both ends are dicarboxylic acid anhydride and / or Adhesive made by applying a polyisoimide solution of polyamic acid isoimidized with the derivative to both sides of a polyimide film and a flexible printed wiring board with circuits formed on both sides are alternately laminated and cured and integrated. It is a multilayer flexible printed wiring board.

[0005]

In the present invention, the reaction for obtaining polyisoimide is usually carried out in an organic polar solvent which does not react with tetracarboxylic dianhydride or diamines. Besides being inert to the reaction system and being a good solvent for the product, this organic polar solvent must be a good solvent for at least one, preferably both, of the reaction components. Typical solvents of this type are tetrahydrofuran, N, N-dimethylformamide, N, N-dimethylacetamide, dimethyl sulfone, dimethyl sulfoxide,
There are N-methyl-2-pyrrolidone and the like, and these solvents are used alone or in combination. In addition to these, nonpolar solvents such as benzene, dioxane, xylene, toluene, and cyclohexane that are used in combination as a solvent are used as a dispersion medium of the raw material, a reaction regulator or a volatilization regulator from the product, and a film smoothing agent. used.

The reaction is generally preferably carried out under anhydrous conditions. This is because the tetracarboxylic acid dianhydride may be ring-opened by water and may be inactivated to stop the reaction. Therefore, it is necessary to remove both the water content in the raw material and the water content in the solvent. But on the other hand, it regulates the progress of the reaction,
Water may be added to control the degree of resin polymerization. Further, the reaction is preferably carried out in an inert gas atmosphere. This is to prevent the oxidation of diamines. Dry nitrogen gas is generally used as the inert gas.

Examples of the acid dianhydride used in the present invention include pyromellitic dianhydride, 3,3 ', 4,4'-benzophenonetetracarboxylic dianhydride, 2,2', 3,3 '-Benzophenone tetracarboxylic dianhydride, 2,3,3', 4'-benzophenone tetracarboxylic dianhydride, naphthalene-2,3,
6,7-Tetracarboxylic acid dianhydride, naphthalene-1,2,5,6-
Tetracarboxylic acid dianhydride, naphthalene-1,2,4,5-tetracarboxylic acid dianhydride, naphthalene-1,4,5,8-tetracarboxylic acid dianhydride, naphthalene-1,2,6,7 -Tetracarboxylic acid dianhydride, 4,8-dimethyl-1,2,3,5,6,7-hexahydronaphthalene-1,2,5,6-tetracarboxylic acid dianhydride, 4,8
-Dimethyl-1,2,3,5,6,7-hexahydronaphthalene-2,3,
6,7-Tetracarboxylic acid dianhydride, 2,6-Dichloronaphthalene-1,4,5,8-tetracarboxylic acid dianhydride, 2,7-Dichloronaphthalene-1,4,5,8-tetracarboxylic acid Acid dianhydride, 2,3,
6,7-Tetrachloronaphthalene-1,4,5,8-tetracarboxylic dianhydride, 1,4,5,8-Tetrachloronaphthalene-2,3,6,7
-Tetracarboxylic dianhydride, 3,3 ', 4,4'-diphenyltetracarboxylic dianhydride, 2,2', 3,3'-diphenyltetracarboxylic dianhydride, 2,3,3 ' , 4'-Diphenyltetracarboxylic dianhydride, 3,3 ", 4,4" -p-terphenyltetracarboxylic dianhydride, 2,2 ", 3,3" -p-terphenyltetracarboxylic acid Dianhydride, 2,3,3 ", 4" -p-terphenyltetracarboxylic dianhydride, 2,2-bis (2,3-dicarboxyphenyl)
-Propane dianhydride, 2,2-bis (3,4-dicarboxyphenyl) -propane dianhydride, bis (2,3-dicarboxyphenyl) ether dianhydride, bis (2,3-dicarboxyphenyl) ) Methane dianhydride, bis (3,4-dicarboxyphenyl)
Methane dianhydride, bis (2,3-dicarboxyphenyl) sulfone dianhydride, bis (3,4-dicarboxyphenyl) sulfone dianhydride, 1,1-bis (2,3-dicarboxyphenyl) ethane Dianhydride, 1,1-bis (3,4-dicarboxyphenyl) ethane dianhydride, perylene-2,3,8,9-tetracarboxylic dianhydride, perylene-3,4,9,10- Tetracarboxylic dianhydride,
Perylene-4,5,10,11-tetracarboxylic dianhydride, perylene-5,6,11,12-tetracarboxylic dianhydride, phenanthrene-1,2,7,8-tetracarboxylic dianhydride , Phenanthrene-1,2,6,7-tetracarboxylic dianhydride, phenanthrene-1,2,9,10-tetracarboxylic dianhydride, cyclopentane-1,2,3,4-tetracarboxylic dianhydride Anhydrous, pyrazine
2,3,5,6-tetracarboxylic dianhydride, pyrrolidine-2,3,
4,5-Tetracarboxylic acid dianhydride, thiophene-2,3,4,5-
Examples thereof include, but are not limited to, tetracarboxylic acid dianhydride and 4,4′-oxydiphthalic acid dianhydride.

Examples of the diamine component used in the present invention include 3,3'-dimethyl-4,4'-diaminobiphenyl, 4,6-dimethyl-m-phenylenediamine and 2,5-dimethyl-p-phenylene. Diamine, 2,4-diaminomesitylene,
4,4'-methylenedi-o-toluidine, 4,4'-methylenedi-2,6-
Xylidine, 4,4'-methylene-2,6-diethylaniline, 2,
4-toluenediamine, m-phenylene-diamine, p-phenylene-diamine, 4,4'-diamino-diphenylpropane, 3,3'-diamino-diphenylpropane, 4,4'-diamino-diphenylethane, 3,3 '-Diamino-diphenylethane, 4,4'-diamino-diphenylmethane, 3,3'-diamino-
Diphenylmethane, 4,4'-diamino-diphenyl sulfide, 3,3'-diamino-diphenyl sulfide, 4,4'-diamino-diphenyl sulfone, 3,3'-diamino-diphenyl sulfone, 4,4'-diamino-diphenyl ether , 3,3'-
Diamino-diphenyl ether, benzidine, 3,3'-diamino-biphenyl, 3,3'-dimethyl-4,4'-diamino-biphenyl, 3,3'-dimethoxy-benzidine, 4,4 "-diamino-
p-terphenyl, 3,3 "-diamino-p-terphenyl, bis
(p-amino-cyclohexyl) methane, bis (p-β-amino-
t-butylphenyl) ether, bis (p-β-methyl-δ-aminopentyl) benzene, p-bis (2-methyl-4-amino-pentyl) benzene, p-bis (1,1-dimethyl-5- Amino-pentyl) benzene, 1,5-diamino-naphthalene, 2,6-diamino-naphthalene, 2,4-bis (β-amino-t-butyl) toluene, 2,4-diamino-toluene, m-xylene- 2,5-diamine, p-xylene-2,5-diamine, m-xylylene-diamine, p-xylylene-diamine, 2,6-diamino-pyridine,
2,5-diamino-pyridine, 2,5-diamino-1,3,4-oxadiazole, 1,4-diamino-cyclohexane, piperazine, methylene-diamine, ethylene-diamine, propylene-diamine, 2,2- Dimethyl-propylene-diamine, tetramethylene-diamine, pentamethylene-diamine, hexamethylene-diamine, 2,5-dimethyl-hexamethylene
-Diamine, 3-methoxy-hexamethylene-diamine, heptamethylene-diamine, 2,5-dimethyl-heptamethylene
-Diamine, 3-methyl-heptamethylene-diamine, 4,4-
Dimethyl-heptamethylene-diamine, octamethylene-
Diamine, nonamethylene-diamine, 5-methyl-nonamethylene-diamine, 2,5-dimethyl-nonamethylene-diamine, decamethylene-diamine, 1,10-diamino-1,10-dimethyl-decane, 2,11-diamino-dodecane, 1,12-diamino
-Octadecane, 2,12-diamino-octadecane, 2,17-diamino-icosane, 1,3'-bis (3-aminophenoxy) benzene and the like can be mentioned.

In particular, the resin composition used in the present invention includes 3,3 ', 4,4'-benzophenonetetracarboxylic dianhydride (hereinafter abbreviated as BTDA) and 3,3', 4,4'-biphenyl. An aromatic tetracarboxylic dianhydride component having a molar ratio (BTDA: BPDA) of 70:30 to 10:90 with tetracarboxylic dianhydride (hereinafter abbreviated as BPDA), and 2,2-bis [4- The molar ratio (BAPP: APB) of (4-aminophenoxy) phenyl] propane (hereinafter abbreviated as BAPP) and 1,3-bis (3-aminophenoxy) benzene (hereinafter abbreviated as APB) is 10:
A polyisoimide obtained by polymerizing an aromatic diamine component of 90 to 90:10 in a state in which the diamine component is in excess and then isoimidating a polyamic acid whose both terminals are blocked with a dicarboxylic acid anhydride and / or its derivative is preferable.

As the dicarboxylic acid anhydride, maleic anhydride, phthalic anhydride, naphthalenedicarboxylic acid anhydride and the like are generally used. The dicarboxylic acid is preferably added after the polyamic acid is formed. This is because the amine at the terminal of the polyamic acid reacted with excess diamine component is eliminated. When the amino group remains at the terminal, an addition reaction of the amino group occurs undesirably when a dehydration ring-closing agent such as N, N′-dicyclohexylcarbodiimide is added.

The reaction of the tetracarboxylic dianhydride component, the diamine component, and the acid anhydride component is carried out by acid dianhydride component / diamine component / acid anhydride component (molar ratio) = 0.9 / 1.0 / 0.1 to 0.9.
It is preferable to carry out at 9 / 1.0 / 0.01. Acid dianhydride component is 0.
If it is lower than 90, the degree of polymerization does not increase and the film properties after curing are poor. If it is greater than 1.00, gas is generated during curing, and a smooth film cannot be obtained.

As the dehydrating agent for isoimidation, N,
N'-dicyclohexylcarbodiimide, acetic anhydride, thionyl chloride and the like are generally used. However, these dehydrating agents require careful selection of the solvent and the like because the production ratio of the isoimide ring and the imide ring varies depending on the solvent and the type of the catalyst. It should be noted that the imide ring and the uncyclized amic acid moiety may remain in the polyisoimide thus obtained as long as the physical properties are not significantly affected.

The coating on both sides of the polyimide film is carried out using a coating device such as a roll coater, a flow coater or a curtain coater. The drying temperature of the resin composition is usually 30 to 150 ° C. , A plurality of double-sided flexible printed wiring boards and adhesives are laminated and laminated, and heated and pressure-cured for 3 to 90 minutes in the range of 100 to 250 ° C, or after pressure and pressure bonding below the above temperature, 180 to A multilayer flexible printed wiring board can be obtained by heating at 250 ° C. for 3 to 90 minutes. Among the double-sided flexible printed boards, the one used for the outermost (back) surface may be the one whose circuit is not processed for the surface exposed on the front (back) side.

[0014]

Example 1 A 4-necked flask equipped with a stirrer, a thermometer and a reflux condenser was charged with APB as a diamine component.
292.4 g (1.0 mol) was added, and further 3000 g of tetrahydrofuran (hereinafter abbreviated as THF) was added and well stirred until the diamine was dissolved. After the diamine component has dissolved, the solution is cooled to below 15 ° C and 279.5 g (0.95 mol) BPDA
Was gradually added so that the temperature in the system did not exceed 15 ° C, and after completion of the addition, stirring was carried out at 15 ° C for 3 hours. Subsequently, in order to seal the terminal amine, 14.8 g (0.1 mol) of phthalic anhydride was used.
l) was added and the reaction was further carried out at 15 ° C. for 3 hours. Next, 412.6 g of N, N'-dicyclohexylcarbodiimide dissolved in 600 g of a THF solution was slowly added dropwise over 8 hours. After completion of dropping, the mixture was stirred at 20 ° C. for 24 hours.
After completion of stirring, the reaction mixture was filtered to remove dicyclohexylurea to obtain a polyisoimide solution.

Example 2 A diamine component was added to a 4-neck flask equipped with a stirrer, a thermometer and a reflux condenser as AP.
292.4 g (1.0 mol) of B was added, 3000 g of NMP was further added, and the mixture was stirred well until the diamine was dissolved. After the diamine component has dissolved, the solution is cooled to below 15 ° C and BPDA
223.6 g (0.76 mol) and BTDA 61.2 g (0.19 mol) were gradually added so that the temperature in the system did not exceed 15 ° C, and after the addition was completed, stirring was carried out at 15 ° C for 3 hours. Subsequently, in order to seal the terminal amine, 14.8 g (0.1 mol) of phthalic anhydride was used.
l) was added and the reaction was further carried out at 15 ° C. for 3 hours. Next, 412.6 g of N, N'-dicyclohexylcarbodiimide dissolved in 600 g of NMP solution was slowly added dropwise over 8 hours. After completion of dropping, the mixture was stirred at 20 ° C. for 24 hours.
After completion of stirring, the reaction mixture was filtered to remove dicyclohexylurea. The resulting solution was precipitated in methanol to give a yellow polyisoimide powder. 50g of this powder
It was dissolved in 200 g of 1,4-dioxane to obtain a polyisoimide solution.

COMPARATIVE EXAMPLE 1 A 4-necked flask equipped with a stirrer, a thermometer and a reflux condenser was charged with AP as a diamine component.
B 146.2 g (0.5 mol) and BAPP 205.3 g (0.5 mol) were added, and further tetrahydrofuran (hereinafter abbreviated as THF)
3000 g was added and stirred well until the diamine was dissolved.
After the diamine component was dissolved, the solution was cooled to 15 ° C or lower, and 223.6 g (0.76 mol) of BPDA and 61.2 g of BTDA.
(0.19 mol) was gradually added so that the temperature in the system did not exceed 15 ° C, and after completion of the addition, stirring was carried out at 15 ° C for 3 hours.

(Production of Multilayer Flexible Printed Wiring Board) The polyisoimide solutions synthesized in Examples 1 and 2 and Comparative Example 1 are commercially available polyimide films (manufactured by Ube Industries, Ltd.).
It is coated on Upilex-R) so that the thickness after drying is 40 μm, dried at 60 ° C. for 1 hour, and tack-free, then the other surface not coated with resin is also dried. Apply resin to a thickness of 40μm, 60 ℃, 1
Heating was performed for 100 hours at 100 ° C. for 1 hour (250 ° C. for 3 hours for completing thermal imidization in Comparative Example 1). The obtained sheet with the polyisoimide adhesive layer was inserted between two flexible printed circuit boards having circuits printed on both sides, and heated at 200 ° C., 40 kg / cm ² , 30 minutes, and pressure-bonded. The values measured for the peel strength of the obtained test pieces are shown in Table 1.

[0018]

[Table 1]

Comparative Example 1 did not undergo the imidization and did not melt at 200 ° C., so almost no adhesive strength was obtained.

[0020]

Industrial Applicability According to the present invention, it is possible to obtain a bonding sheet with a polyisoimide adhesive layer, which has excellent heat resistance and exhibits a strong adhesive force without requiring a high temperature in the adhesive step. This bonding sheet with a polyisoimide adhesive layer can exhibit heat resistance similar to that of a normal polyimide because the isoimide ring is rearranged to the imide ring after heat curing. Further, the present invention is suitable as an industrial method for manufacturing a multilayer flexible printed circuit board because it can be easily applied to a continuous process of a multilayer flexible printed circuit board using a continuous sheet.

Claims (1)

[Claims] 1. A polyamic acid in which an aromatic tetracarboxylic dianhydride component and an aromatic diamine component are polymerized in a state in which the diamine component is in excess, and the both ends are sealed with a dicarboxylic acid anhydride and / or a derivative thereof. A multilayer flexible printed wiring board in which an adhesive material obtained by applying a polyisoimide solution of isimidized on both sides of a polyimide film and a flexible printed wiring board having circuits formed on both sides are alternately laminated and cured to be integrated.