A drilled microvia needs a prepared dielectric surface and a clean connection to its target copper before subsequent metallization and filling.
What to consider
The treatment must be compatible with the resin, glass and copper system. Inadequate preparation can weaken the electrical interface even when the finished board passes a simple continuity test. Designers should not prescribe a chemistry from a generic article; they should request a qualified process and acceptance evidence for the selected construction.
A practical review example
When changing laminate grade, ask whether drilling and desmear parameters and via qualification need to change. A material substitution can affect more than impedance.
Checks before release
- Confirm the process is qualified for the material system.
- Request appropriate interconnect inspection.
- Review changes that alter the target interface.
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.