Polyimide (PI) film is a thin-film insulating material made of pyromellitic dianhydride and diaminodiphenyl ether in a strong polar solvent, polycondensed and cast into a film, and then imidized. PI film has become the best flexible substrate material currently due to its excellent high temperature resistance, mechanical properties and chemical stability.
The PI film is yellow and transparent, and the relative density is between 1.39 ~ 1.45. It has excellent high and low temperature resistance, electrical insulation, adhesion, radiation resistance, dielectric resistance, etc., and can be used at -269°C to 280°C It has been used for a long time in the temperature range and is widely used in high-tech fields such as aviation, aerospace, machinery, electrical, atomic energy, microelectronics, liquid crystal display, etc., and has become one of the indispensable materials in the world's rocket, aerospace and other cutting-edge technology fields.
Flexible substrate materials For folding mobile phones, traditional glass materials are hard and fragile, and the replacement of traditional rigid glass substrates by flexible substrate materials is one of the key elements to achieve product flexibility. PI film has excellent high temperature resistance, mechanical properties and chemical resistance. Stability is currently the best flexible substrate material.
For example, it is proposed in "Made in China 2025" that by 2020, flexible displays should reach 300PPI resolution. Small and medium-sized flexible AMOLED displays with a bendable diameter of <1cm; in 2025, a 100-inch, rollable 8K4K flexible display, small and medium-sized Foldable display.
PI is one of the organic polymer materials that can withstand high temperatures above 400 degrees Celsius. The long-term use temperature is between 200 and 300 degrees Celsius. It has no obvious melting point. It has high insulation properties and has excellent performance in diaphragm materials. It has excellent high and low temperature resistance, electrical insulation, adhesion, radiation resistance and other special properties, so it can replace traditional ITO glass and is widely used in substrates, covers and touch materials in foldable mobile phones. Among them, yellow PI is mainly used for substrate materials and auxiliary materials in flexible OLEDs, and CPI (transparent PI) is mainly used for cover materials and touch materials.
Monopoly and leading situation: The PI industry chain includes the production of upstream PI resin and base film, as well as precision coating and subsequent processing procedures. Among them, the production of resin and base film is the link with the highest barriers in the world. It is worth mentioning that the world Leading companies include global giants such as Ube of Japan and Cologne of South Korea. There are about 50 PI film manufacturers in China. Especially with the explosion of flexible screen mobile phones and the large number of application functions of other consumer electronic products, PI is expected to become the "upstart" among new materials.