Can Flexible PCBs Be Repaired?

Flexible circuit boards, including keyboards, can be repaired. Let’s explore how to repair a keyboard FPC flexible circuit board:

1. Understanding the Flexible Circuit Board

The keyboard’s flexible circuit board (FPC) is made of polyester film (PET) with three layers. The upper and lower layers are printed with silver paste or foil, while the middle layer acts as insulation to prevent short circuits. When a key is pressed, the upper hole allows for instant short-circuiting between the printed layers, inputting the corresponding character or command.

2. Troubleshooting the Failed Keys

If only a few keys fail, it indicates that the main control board is functioning correctly. By using a multimeter’s diode buzzer function, trace the FPC line to the connection pin on the main control board. If there is an open circuit due to damage, consider repairing it.

3. Repairing the Flexible Circuit Board

Unlike standard PCBs, repairing a flexible PCB with soldering is impractical. Instead, use conductive silver paint to fix open circuits effectively. This paint is suitable for various plastic circuit boards found in keyboards, offering low resistance and excellent conductivity.

4. Applying Conductive Silver Paint

Conductive silver paint is a reliable solution for repairing broken circuits. It dries quickly, adheres well to plastics, and can be applied with a brush or syringe. Ensure thorough mixing before application and seal it after drying. While it may be slightly expensive, the effectiveness outweighs the cost.

If you encounter any PCB repair issues or have manufacturing needs, feel free to contact us.