A useful HDI vocabulary connects each term to a drawing feature: build-up, core, microvia, blind via, buried via, target land and capture land.
What to consider
A blind via ends inside the board; a buried via is enclosed after later processing. Microvia describes a small interconnect structure and its geometry, while via-in-pad describes placement. Copper filling and resin filling are distinct processes. A pad location alone does not identify how the via was manufactured or qualified.
A practical review example
Write “copper-filled L1–L2 laser microvia in component pad” when that is the intended structure. It communicates more than a general note such as “HDI via” or “filled via.”
Checks before release
- Use consistent layer names from the stackup.
- Distinguish starting copper from finished copper.
- Define dimensions as nominal values with tolerances.
Connect this decision to fabrication
Use the stackup planner 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.
- Prove the package escape on a small routing study.
- Compare complete constructions using the same reliability requirements.
- Resolve the fabrication process before locking the layout.
Technical references
HDI construction types and definitionsHDI design and manufacturing overviewReferences checked 2 October 2026. Manufacturer data describes its stated construction and is not an HDIPCB.org manufacturing commitment.