Masking in the PCB manufacturing process is an important step involving the application of a protective layer to various electronic components on a printed circuit board (PCB).
The main purpose of masking a PCB is to prepare it for the application of a conformal coating. This coating creates a protective layer against external factors, but requires careful masking so that the circuitry and functional components are not compromised.
Manufacturers use a variety of PCB masking methods, each with its own application, material, and cost. The two main categories are masking shields and masking tapes.
Reusable masking screens:
- Common options include masking boots, plugs, and vinyl. - Customized masking boots are economical and easy to apply, but may require constant cleaning. - Vinyl plugs are a bit more reusable because they adhere to the components. - Customized masking plugs are used to fill large interlayer and through holes. - Masking tapes
Disposable masking tapes:
- Low ESD polyimide tapes provide safer removal. - Standard polyimide tapes withstand high temperatures and leave no residue. - Crepe masking tapes are less expensive, easy to work with, and leave no silicone residue. - Each masking method has its own advantages and limitations, which influences the choice depending on specific PCB requirements and manufacturing considerations.