Solder-mask openings and remaining dams must fit the package land pattern and the factory’s registration capability. Mask color is not a substitute for a process specification.
What to consider
Small pads can leave little space for a mask dam. The fabricator and assembler should agree the opening geometry, mask definition and allowable registration. Do not enlarge or merge openings without checking solder bridging, pad exposure and assembly yield.
A practical review example
Overlay the worst-case mask registration on the BGA lands and inspect whether copper remains correctly exposed. Coordinate the result with the stencil and paste-volume plan.
Checks before release
- Use the package assembly guidance for land definition.
- Obtain mask registration and minimum-dam capability.
- Review vias and filled pads in the same region.
Connect this decision to fabrication
Use the lamination guide to organize the initial discussion. Keep proposed values separate from the approved drawing and document the effect of any change on the rest of the construction.
- Ask the fabricator to confirm the complete construction in writing.
- Resolve manufacturing exceptions before tooling.
- Retain the approved drawing, stackup and inspection plan with the release.
Technical references
Fabrication design guidelinesConstruction-specific HDI capabilities and FAQReferences checked 2 October 2026. Manufacturer data describes its stated construction and is not an HDIPCB.org manufacturing commitment.