The materials of flexible circuit boards mainly include the following:

1. Polyimide (PI):also known as Kapton, is one of the most commonly used flexible circuit board substrates. It has excellent temperature resistance, chemical stability, and electrical insulation performance, suitable for applications in high temperature and harsh environments.

2. Polyester (PET): PET materials have lower costs and good flexibility, and are commonly used in flexible circuit boards with low cost and low temperature requirements.

3. Polyamide ester (PA): Similar to PI, PA also has high temperature and chemical resistance, and is commonly used in flexible circuit boards in high-temperature environments.

4. Polyether ketone (PEEK): PEEK has good mechanical properties and chemical stability, suitable for flexible circuit boards with high temperature and strength requirements.

5. Fluoroplastics (FEP, PFA, etc.): Fluoroplastics have excellent high temperature resistance and chemical stability, and are commonly used in flexible circuit boards in high-temperature environments.

6. Metal foil: Metal foil is commonly used as the conductor layer of flexible circuit boards, and common metals include copper, aluminum, etc.

These materials can be selected and combined according to specific application requirements to meet the performance requirements of flexible circuit boards in different environments and working conditions.