A blind via connects an outer copper layer to an internal layer without extending through the full board. Its process depends on depth, diameter and the construction sequence.
What to consider
Laser drilling is common for short HDI blind interconnects, while some blind structures use mechanical drilling. Specify the span and method rather than treating all blind holes as microvias. A smaller surface land can help escape routing, but the connection must still reach a usable routing layer or plane.
A practical review example
In an eight-layer board, an L1–L2 blind microvia is a different feature from an L1–L4 mechanically drilled blind via. The aspect ratio, drilling sequence, plating access and quote may differ substantially.
Checks before release
- Define start and stop layers.
- State drilled and finished-hole conventions.
- Check how the blind transition joins the rest of the net.
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.