A kind of polyimide film with low thermal expansion coefficient and preparation method thereof

Abstract

The invention belongs to the field of high polymer materials and particularly relates to a polyimide film with a low thermal expansion coefficient and a preparation method of the polyimide film. The polyimide film has the following structural formula shown in the specification, wherein R1 and R3 are residues of two different tetracarboxylic acid dianhydride monomers, and R2 and R4 are residues of two different di-primary amine monomers. The preparation method is a multi-step polymerization method, firstly, two polyimide acid solutions with different structure units are obtained through polymerization respectively, then the solutions are mixed and then polymerized, finally, heating drying is carried out, and the polyimide film with the low thermal expansion coefficient is obtained. Compared with the prior art, the polyimide film with the low thermal expansion coefficient introduces ester bonds / amide, imidazole / oxazole and other structure units into molecular structure design at the same time, the interaction force among molecules is improved, the thermal expansion coefficient of the polyimide film is effectively reduced, meanwhile, the thermal expansion coefficient of the polyimide film can be adjusted and controlled by adopting different formulas, and the matching problem among different substrate materials is solved.

Description

technical field [0001] The invention belongs to the field of polymer materials, and in particular relates to a polyimide film with low thermal expansion coefficient and a preparation method thereof. Background technique [0002] Polyimide is the most important variety of aromatic heterocyclic polymers developed in the past half century, and it is also a type of polymer material with the highest service temperature. It has high mechanical strength, high temperature resistance, chemical stability, and creep resistance. With excellent comprehensive performance, it has been widely used in aviation, aerospace, electrical, mechanical, microelectronics, chemical industry and other fields. [0003] However, polyimide has a large thermal expansion coefficient (40-80×10 -6 / K), which greatly limits its application range, especially in the microelectronics industry, as in the above-mentioned packaging circuit, there is a large difference in thermal expansion coefficient between polyim...

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Problems solved by technology

[0003] However, polyimide has a large thermal expansion coefficient (40-80×10 -6 / K), which greatly limits its application range, especially in the microelectronics industry, as in the above-mentioned packaging circuit, there is a large difference in thermal expansion coefficient between polyimide and conductive material or substrate (such as The coefficient of thermal expansion of Cu is 16-18×10 -6 / K, SiO 2 The coefficient of thermal expansion is 14×10 -6 / K, Si thermal expansion coefficient is 3-6×10 -6 / K), serious thermal expansion coefficient mismatch will lead to delamination or cracking of the packaging material during the heat treatment of the packaging process or during the use of the packaged circuit, and even lead to the failure of the material or device

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