FPC flexible circuit board etching is that the etching solution is evenly sprayed on the surface of the copper foil through the nozzle under a certain temperature condition (45+5), and the oxidation-reduction reaction occurs with the copper that is not protected by the etching resist, and the unwanted copper After reaction, the substrate is exposed and the circuit is formed after stripping.

The main components of the etching solution: copper chloride, hydrogen peroxide, hydrochloric acid, soft water (the solubility is strictly required) quality requirements and control points:

1. The dry film on the circuit solder joints shall not be separated or broken by scouring.

2. The etching speed should be appropriate, and the thinning of the line caused by excessive etching is not allowed. The line width and total pitch at the time should be the focus of the management and control of this site.

3. It should be ensured that the chemical solution is evenly distributed at all times to avoid uneven etching on the front and back sides or different parts of the same side.

4. There should be no residual copper, especially double-sided FPC boards.

5. There should be no residual glue, otherwise it will cause exposed copper or poor adhesion of the coating.

6. The FPC sheet after the film is always stripped is not allowed to have bad quality such as oil stains, impurities, and copper peeling.

7. When putting FPC board, pay attention to avoid card FPC board to prevent oxidation.

Process control parameters: stripping liquid temperature: 55+/-5℃ safe use temperature of etching machine ≦55℃ etching liquid temperature: 45+/-5℃ hydrogen peroxide solubility: 1.95~2.05mol/L copper chloride solution specific gravity ：1.2~1.3g/cm3 PCB board angle, guide PCB board, switch status of upper and lower nozzles Hydrochloric acid solubility: 1.9~2.05mol/L Drying temperature: 75+/-5℃

Front and rear FPC board spacing: 5~10cm Quality confirmation: Line width: The etching standard line is .2mm&0.25mm, and it must be within +/-0.02mm after etching.

Non-deformable and non-oxidized water droplets of the line shall be inspected by light transmission without residual copper.

Surface quality: no wrinkles, scratches, etc.