PI refers to a type of polyimide resin material, which is widely used in various fields today and is a material with very good performance. Some people call PI a landmark material that promotes the reform of electronic products. We will mainly explain the location and function of the FPC circuit board and PI.

PI is a material with excellent high-temperature resistance, which will be used in aerospace technology. PI has two main positions in the circuit board.

1. As a PCB substrate

This is the material that most circuit boards use, and the substrate mainly plays a role in strengthening and thickening, mainly because the copper foil of the circuit board is very thin, not enough to support the adhesive and covering film separately. In this type of usage, PI mainly has a thickness obtained by laminating multiple layers of PI, and single layer PI is also very thin.

PI is not the only material used as a substrate, and there are also materials such as PET, FR4, ET, etc. However, due to the influence of material shrinkage during the production of flexible circuit boards, PI is mostly used as an insulation material in the production of FPC flexible circuit boards, in order to improve production yield and efficiency, unless the customer requests the use of other materials.

2. As a covering film

Single layer PI is very thin, and PI has multiple properties, not only able to withstand high temperatures, but also excellent in wear resistance and insulation. So, PI is often used as a protective film in the area where the circuit board gold finger is located, mainly because the gold finger needs to be inserted into the connector for an indefinite number of times, and using ordinary covering film for a long time can easily cause damage to the gold finger.