Choose HDI when the additional interconnect freedom resolves a measured limitation. A conventional multilayer PCB can remain the better construction when routing space is sufficient.
What to consider
Through holes reserve a vertical corridor through the board. Blind microvias reserve a shorter corridor, often only between adjacent layers. That difference can free internal routing area, but it adds processing and verification requirements. A fair comparison includes usable routing layers, board outline, reference planes, assembly yield and fabrication cost.
A practical review example
Keep the component placement constant and route a representative quadrant of the hardest BGA in both options. A lower layer count is only a saving if the resulting build-up, material and test costs remain acceptable.
Checks before release
- Compare like-for-like electrical and reliability requirements.
- Include component escape and power connections.
- Do not assume HDI automatically reduces cost or improves reliability.
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.