PCB Etching Process Overview
The PCB etching process is a crucial step in completing the circuit board manufacturing process. After electroplating, the board undergoes post-processing steps to achieve the desired circuitry. These steps include:
- Film Removal: The dry film used for anti-plating is removed using a special solution. Proper filtration is essential to ensure effective removal and post-washing.
- Line Etching: Involves dissolving copper in the non-conductive areas of the board.
- Stripping Tin and Lead: The etch-resistant tin-lead coating is stripped off, a critical step to avoid defects in the final circuit.
PCB Processing Methods
Currently, the “pattern plating method” is commonly used in PCB fabrication. This method involves pre-plating a resist layer on the copper foil, followed by chemical corrosion. Another approach is the “full board copper plating process,” where the entire board is coated with copper.
Etching Quality Control
During etching, tin or lead-tin is used as the resist layer with ammonia etchant. The etching solution quality and equipment structure play a significant role in achieving precise etching results. Additives can help reduce side etching, and maintaining consistent wire width is crucial.
Challenges in Etching
Issues such as residual glue, incomplete etching, and copper root formation can affect the quality of the etching process. Proper control of etching factors is essential to ensure high-quality PCB production.
