Placement sets route corridors, return-path continuity and assembly access. Increasing HDI complexity is an expensive way to compensate for avoidable placement congestion.
What to consider
Position critical interfaces so they can reach appropriate routing layers with minimal transition complexity. Reserve space for decoupling, test points, tooling and component keepouts. Review connectors and tall parts early because enclosure constraints often prevent later movement.
A practical review example
Before approving a second build-up, try rotating or repositioning the device that creates the blocked route corridor. Compare the impact on timing, power delivery and assembly rather than routing density alone.
Checks before release
- Keep critical interface paths short and direct.
- Preserve access for power and ground connections.
- Coordinate placement with assembly and mechanical teams.
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.
- Use rules confirmed for the chosen factory and construction.
- Inspect return paths through every critical breakout.
- Release consistent artwork, drills, stackup and drawing revisions.
Technical references
HDI design and manufacturing overviewFabrication design guidelinesReferences checked 2 October 2026. Manufacturer data describes its stated construction and is not an HDIPCB.org manufacturing commitment.