Biaxially oriented polyimide film for flexible printed circuit board base material and preparation method of biaxially oriented polyimide film

Abstract

The invention relates to a biaxially oriented polyimide film for flexible printed circuit board base material and a preparation method of the biaxially oriented polyimide film. The method is characterized by mainly comprising the following steps of: (1) polymerizing: preparing a basic solution of polyimide acid according to the following proportions: 1-5% of p-phenylenediamine, 2-8% of biphenyltetracarboxylic dianhydride, 5-10% of diaminodiphenyl ether, 8-15% of pyromellitic dianhydride and 62-84% of dimethylacetylamide; (2) salivating the solution into a film; (3) longitudinally stretching the film according to the stretching ratio of 1:1.02-1.15; (4) transversely stretching the film according to the stretching ratio of 1:1.05-1.2 and carrying out imidization; (5) cutting the edge and rolling up the film; (6) postprocessing the film; and (7) cutting and packaging the film. The special biaxially oriented polyimide film material conforming to the flexible printed circuit board base material can be obtained by using the preparation method provided by the invention.

Description

technical field [0001] The invention relates to a polyimide film and a preparation method thereof, in particular to a biaxially stretched polyimide film for a flexible printed circuit board base material and a preparation method thereof, belonging to the field of organic polymer material preparation. Background technique [0002] At present, most domestic manufacturers of biaxially oriented polyimide films use very primitive technology, using two kinds of raw materials and one solvent, that is, pyromellitic dianhydride (PMDA) and diaminodiphenyl ether. (ODA) is polycondensed and salivated into a film in a very strong solvent dimethylacetamide (DMAC), and then imidized. The yield rate of the films produced is low, and there are very few films used as base materials for flexible printed circuit boards. Most of the films are used on flexible printed circuits, and their service life is very short, or even unusable. The main defects are manifested in: [0003] ①. The thickness ...

AI Technical Summary

Problems solved by technology

[0003] ①. The thickness tolerance is large, and the thickness of the film is uneven, which affects the use on flexible boards

[0004] ②. The tensile strength is low, and the coefficient of linear expansion is quite different from that of flexible copper-clad laminates. When used on flexible boards, the circuit will have some temperature rise during use. Because the tensile strength of the film is not enough, the coefficient of linear expansion is different from that of flexible copper clad laminates. The difference between flexible copper clad laminates is large, so that the copper wires left by etching on the circuit board will be damaged due to the difference in thermal expansion from the film

[0005] ③. The peel strength between the film and the copper clad laminate is not enough, and it cannot be firmly bonded with the flexible copper clad laminate

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