A skip microvia bypasses an intermediate layer. Its greater dielectric depth and target access must be supported by a specifically qualified process.
What to consider
Do not substitute a skip via for two adjacent microvias simply to reduce layout work. Drillability, taper, aspect ratio, metallization and interaction with the skipped copper layer all change. Obtain the fabricator’s approved structure and verify that the intermediate layer opening is compatible with routing and reference planes.
A practical review example
Compare an L1–L3 skip feature with separate L1–L2 and L2–L3 transitions. The best option depends on geometry, routing space and the process window, not only the number of visible via symbols.
Checks before release
- Confirm the skipped layer clearance.
- Review total dielectric depth.
- Use only the factory-approved span and dimensions.
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.