Polyimide film with low thermal expansion coefficient and preparation method thereof

Abstract

The invention discloses a polyimide film with a low thermal expansion coefficient and a preparation method thereof. The invention belongs to the technical field of macromolecular polymer material filmpreparation. The key points of the technical scheme comprise that the preparation method comprises the steps: completely dissolving metered 4,4-diaminodiphenyl ether into N,N-dimethylformamide; adding metered pyromellitic dianhydride at one time; adding a small amount of amine catalyst after pyromellitic dianhydride is completely dissolved; then adding metered p-phenylene diisocyanate in batchesuntil no CO2 gas releases, obtaining a homogeneous and transparent polyamic acid solution in which p-phenyleneimine is introduced; and carrying out vacuum defoaming, extrusion casting, two-way stretching and heating imidization to obtain the polyimide film with the lowest thermal expansion coefficient of 15 ppm / DEG C. The polyimide film has the advantages that universality is high, the industrialization degree is high, the defect that the chemical imidization technology is high in difficulty is overcome, and the strict environmental protection requirement can be met.

Description

technical field [0001] The invention relates to the technical field of polymer film preparation, in particular to a preparation method of a low thermal expansion coefficient polyimide film. Background technique [0002] With the rapid development of modern electronic products, the requirements for high-density connected flexible printed circuit boards (FPC) are getting higher and higher. Usually, FPC is coated with adhesive on the substrate polyimide film and then laminated with copper foil. It is made of polyimide film copper clad laminate (FCCL), and then formed into a copper winding circuit product. Therefore, FCCL as the raw material of FPC must have better dimensional stability, and starting from the current FCCL preparation process, the polyimide film characteristics of its substrate have become the main factor that has a great impact on the change of FCCL. Therefore, the polyimide film has a high modulus, and it is even more critical that the coefficient of thermal e...

AI Technical Summary

Problems solved by technology

[0003] At present, although there are three types of commercial polyimide films used on FPC by DuPont Company of the United States, Ube Industries of Japan and Zhongyuan Company of Japan, according to relevant reports, the typical preparation method of the film is through chemical imidization. To achieve, the technical difficulty is extremely high, resulting in expensive products

At present, the research and development of chemical imidization of polyimide film has been carried out in China, but it is still in its infancy, and there is no batch product coming out. With the increasingly stringent environmental protection requirements, its technical difficulty is higher

However, the domestic polyimide film is limited by the conventional thermal imidization preparation technology, and its CTE is still difficult to approach 18ppm / ℃ of copper foil, which cannot meet the requirements for the manufacture and use of high-functional FPC, and the reaction by-products are highly polluting. , cannot meet the increasingly stringent environmental protection requirements

[0004] Professor Kuangjun Hasegawa, Department of Chemistry, Faculty of Science, Toho University, Japan, in "Membrane Forming Method and Physical Properties of Polyimide", introduced the reaction of s-BPDA and PDA first, and then added the remaining diaminobenzidine diimide to polymerize The polyamic acid with imine group is formed, and the polyimide film with low CTE is obtained after thermal imidization, but the preparation of diaminodiimine monomer is cumbersome, and it is generally made by the laboratory, which is difficult to produce on a large scale , so there is no commercially available product for diaminodiimide monomers, and now there is a need for a polyimide film manufacturing method with strong versatility, high industrialization degree and low technical difficulty

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