Reliable microvias require a qualified construction, controlled processing and test evidence that represents the finished board’s thermal exposure.
What to consider
A room-temperature continuity test can miss a weak connection that opens under heat. Geometry, target preparation, copper fill quality and stacked interfaces should be reviewed together. The IPC’s historical warning on microvia reliability is a reason to ask about appropriate qualification, not a statement that every microvia or every stacked design fails.
A practical review example
Ask whether the coupon represents the production via sequence, materials and copper interfaces, and whether electrical monitoring covers the relevant thermal stress. A photograph of an unrelated cross-section is not equivalent evidence.
Checks before release
- Define assembly reflow and possible rework cycles.
- Agree the applicable acceptance plan.
- Keep qualification data tied to the production construction.
Connect this decision to fabrication
Use the design checklist 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.
- Record depth and diameter using the same units and measurement convention.
- Check capture lands, target lands and registration together.
- Match the test coupon to the actual interconnect construction.
Technical references
Fabrication design guidelinesHistorical IPC microvia reliability warning (2019)References checked 2 October 2026. Manufacturer data describes its stated construction and is not an HDIPCB.org manufacturing commitment.