Synthesis Process and Applications of PI Film

PI film, also known as polyimide film, is a versatile and high-performance material used in various industries. Known for its exceptional thermal stability, mechanical strength, and electrical insulation properties, PI film is widely used for applications that require resistance to extreme temperatures, chemicals, and abrasion.

In the electronics industry, PI film is commonly used as an insulation material for flexible circuit boards, thanks to its ability to withstand high temperatures during soldering processes. Its excellent dielectric strength also makes it a preferred choice for insulation in electric motors and transformers.

Furthermore, PI film finds extensive use in the aerospace industry due to its lightweight and durable nature. It is employed as a protective covering for sensitive components and as an insulation material for wires and cables in aircraft. Its resistance to radiation and excellent dimensional stability make it ideal for space applications as well.

In addition to its mechanical and thermal properties, PI film offers exceptional barrier properties against moisture, gases, and chemicals. This makes it a preferred choice for packaging materials in the food and pharmaceutical industries, ensuring product integrity and extending shelf life.

Overall, the unique combination of high temperature resistance, mechanical strength, electrical insulation, and barrier properties has made PI film an indispensable material in various specialized applications, ranging from electronics and automotive to aerospace and packaging industries. Its versatility and reliability have cemented its position as a key material for demanding applications worldwide.

Whether as a structural material or a functional material, polyimide has been recognized as one of the most promising engineering plastics of the 21st century by various countries. Polyimide films processed from polyimide resin are particularly suitable for use as flexible printed circuit board substrates and various high-temperature electrical insulating materials due to their excellent insulating and mechanical properties, earning them the nickname "golden films".

Main synthesis processes of polyimide films

There are two main synthesis methods for polyimide films (hereinafter referred to as PIF): one is the thermal imidization method, suitable for the production of PIF below the electronic grade; the other is the chemical imidization method, suitable for the production of PIF above the electronic grade. Compared with the thermal imidization process, PIF produced by the chemical imidization method exhibits better performance and stronger market competitiveness. Dimethylformamide (DMF), an important solvent for the preparation of high-end PIF using the chemical imidization method, has stricter requirements, particularly for controlling water content within 100 ppm. Currently, 90% of domestic manufacturers use the thermal imidization process, while foreign countries have mostly completed the replacement of the thermal imidization process with the chemical imidization method.

Polyimide film belongs to a high-tech barrier industry. Currently, there are 40 to 50 polyimide film manufacturers in different sizes in China, most of which have achieved self-sufficiency in PIF below the electronic grade. However, about 85% of high-end polyimide films rely on imports. The main market is dominated by companies such as DuPont, Toray, SKC, and Ube. Only three domestic factories use the chemical imidization process, which started relatively late. However, with the high growth rate of flexible copper-clad laminate (FCCL) market and the increasing demand for flexible films driven by the rapid popularization of OLEDs, the high-end electronic-grade polyimide film market will be in a phase of rapid expansion, stimulating domestic PIF manufacturers to upgrade and expand their technologies.

Main applications of polyimide films

Electronic-grade PIF is mainly used for flexible electronic substrates. With the development of the times, high-end electronic products require lightweight and thin substrates with large information transmission and recording capacities. This requires good heat dissipation of printed circuit boards (PCBs), which can be bent, folded, rolled, and freely moved and stretched in a three-dimensional space, necessitating the use of flexible printed circuit boards. Flexible printed circuit boards are made by laminating copper foils onto electronic-grade polyimide film as copper-clad laminates (FCCL).