FPC overlay is an important component of flexible circuit boards, whose main function is to protect the circuit, prevent oxidation, pollution, and mechanical damage. The choice of covering film directly affects the performance and reliability of FPC. The following is a detailed description of FPC cover film:

1. Material type:

-Polyimide (PI): It has excellent high temperature resistance and chemical stability, and is suitable for electronic products working in high temperature environments.

-Polyester (PET): Low cost, suitable for medium and low temperature environments, but its high temperature resistance is not as good as polyimide.

-Acrylic ester: has good transparency and adhesive properties, suitable for applications that require transparency.

2. Thickness selection:

-The thickness of the covering film is usually between 12.5 μ m and 75 μ m. Thicker covering film has better mechanical strength and protective performance, but it can affect the flexibility of FPC.

-A thinner covering film is more conducive to the bending performance of FPC, but the protective effect is relatively weak.

3. Application method:

-Hot press laminating: The covering film is bonded to the FPC through high temperature and high pressure, suitable for mass production and high-quality requirements.

-Cold pressed film coating: The covering film is bonded to FPC under pressure at room temperature, suitable for small batch production and temperature sensitive materials.

4. Performance requirements:

-The covering film shall have good insulation performance, chemical corrosion resistance and aging resistance.

-It needs to have a certain degree of transparency for subsequent optical testing.