Cleaning Method of PCB Substrate Surface (2)

B. Machine Cleaning
During machine cleaning, the machine is typically cleaned by abrasive brushes. Figure 7-2 Use solvent strippers such as corundum, corundum, alumina, and silicon carbide to clean substrates. These greasy hand-cleaning abrasive materials can be diffused into nylon or similar plastic materials, so that the brushes used are in the form of flat flakes or filaments. The copper foil surface is typically cleaned with a 320 mesh SiC filament abrasive brush before the dry film resist is formed. The different types of machine cleaning operations are as follows:
1) Polishing
2) Brush
3) Polished or sanded
4) Deburring or scrubbing
5) Scrub

1. Polishing
The process is to improve the appearance of the metal by smoothing it. Polishing is usually done with a buffing wheel (cotton cloth).

2. Brush
The process is to use a rotating non-metallic wire brush, such as a nylon brush to smooth the metal, the wire brush is usually wet. For very dull metal surfaces, brush with a grade 3F or 4F pumice powder. While this does a good job of removing particulate matter and cleaning heavy oxides or other metal contaminants, it does not completely remove organic contaminants such as oils and greases. In practice, these contaminants remain in the brush, so solvent degreasing is recommended prior to brushing.

3. Polished or Sanded
Polishing refers to the use of a cotton cloth wheel to polish the metal surface, changing from a low-gloss product to a high-gloss product. This method removes a large number of inorganic contaminants and particulate matter, and also helps remove scorch marks around the borehole. Polishing can be done using an electric hand-held vibrator.