Soldering electronics assemblies can generate many problems, including solder or flux residue buildup in unwanted locations on a printed circuit board. Solder mask is a thin protective layer applied to printed circuit boards intended to control this accidental buildup and prevent unwanted solder connections. On occasion, solder mask will need to be removed from a printed circuit board in situations such as board manufacturing defects or circuit design changes. This mask can be removed with one or a combination of these techniques: scraping and sanding, machining, chemical stripping or abrasion.
Instructions
Scraping and Sanding the Solder Mask
1 Scrape the solder mask layer away from the PCB carefully with the razor blade. Always wear safety glasses to avoid injury during this process.
2 Sand the PCB solder mask away with the mechanical eraser. This process requires a high level of skill to avoid damage to other areas of the PCB.
3 Inspect the PCB for accidental damage to the board itself or any electrical component traces.
Machining
4 Set the carbide tipped mill's tip to ensure that only the PCB solder mask will be affected by the machine's cutting tip. This is an exacting measurement that could require the use of a microscope attachment.
5 Cut the PCB solder mask away with the carbide tipped mill, avoiding damage to other electrical traces or areas of solder mask.
6 Inspect the PCB for accidental damage to the board itself or any electrical component traces.
Chemical Stripping
7 Protect the areas to be unaffected with the masking tape.
8 Apply the commercial solder mask chemical remover with the brush only to the unmasked areas. Always wear latex gloves for safety.
9 Clean the commercial solder mask chemical remover from the PCB with paper towels. The remover works quickly and must be removed before it damages unwanted areas.
10 Inspect the PCB for accidental damage to the board itself or any electrical component traces.
Abrasion
11 Protect any areas not to be affected by abrasion with masking tape.
12 Blast the solder mask away with the electronics microblaster. Be aware of static electricity buildup during this process to avoid electrostatic discharge damage to any components.
13 Inspect the PCB for accidental damage to the board itself or any electrical component traces.
