Peelable soldermask is a temporary process aid. Its job is complete only when the required area has been protected and the material has been removed as specified. Put removal and final inspection into the route instead of ending acceptance at a photograph of the applied mask.
Identify what is being protected
Eurocircuits describes peelable mask as protection for selected solder holes and, in some cases, carbon elements or gold-plated contacts during mass soldering. The exact application should be agreed with the supplier rather than extending this description to every exposed feature.
Define the protected area in controlled artwork or an assembly drawing. Mark holes, contacts and nearby openings that must remain free of the temporary material after removal. Use the selected mask manufacturer’s application and removal instructions.
Plan the removal stage
Determine which operations the mask must survive and when access for removal exists. A protection area easily reached on the bare board may become inaccessible after a connector or enclosure is installed.
| Stage | Acceptance question |
|---|---|
| Application | Is the required feature covered without unintended intrusion? |
| Processing | Does the approved mask remain suitable for the actual route? |
| Removal | Can the material be removed by the specified method? |
| Final inspection | Is the protected feature usable and free of excluded remnants? |
Inspect the feature after peeling
Check hole accessibility, contact condition and adjacent crevices as relevant. Inspect the board rather than relying only on the size of the piece that was removed. A detached strip can look complete while a small remnant remains at an edge or in a hole.
For example, a connector lead may not enter a protected hole because material remains inside it. Forcing the lead into place would conceal a removal problem and introduce another assembly variable.
Keep removal tools and any allowed cleaning method defined. An improvised scraping method can change the underlying surface, so obtain a disposition when normal removal does not produce the required condition.
Where several protected areas exist, give them separate inspection identifiers. A single completed-removal checkbox can otherwise hide a missed region on the opposite board side.
Qualify the actual thermal history
Include repeated soldering or rework exposure if it is part of the approved route. A mask removed successfully after one operation has not automatically been qualified after a different accumulated process.
Retain sample images of acceptable and rejected final conditions with the inspection instruction. State whether a protected electrical surface needs additional testing before release.
The carbon-contact test guide addresses one protected surface, and selective flux mapping helps define exposure around an intended soldering region.
Move from reading to a build-ready project
Use the fabrication and assembly checklists to prepare drawings, production files and test requirements.
Open the DFM checklist