Define the project
HDI designs use interconnect approaches such as microvias and sequential build-up to route dense circuitry. The via arrangement, lamination sequence and material system determine the practical manufacturing route. An HDI label alone is not enough to quote a board.
Requirements to include
- Build-up drawing with every via start and stop layer
- Microvia diameter and dielectric depth
- Stacked or staggered via requirements
- Filling, capping and via-in-pad requirements
- Fine-pitch escape geometry and the proposed stackup
Decisions to resolve before release
Ask the engineering review to address the complete via structure and its intended reliability requirements. Changes from staggered to stacked structures, or to a different lamination sequence, may affect cost and qualification. Confirm those decisions before releasing the layout.
Request a project-specific quote
Send the design revision, quantity and required date with the technical requirements above. Identify anything still under review. Feasibility, process details, inspection scope and delivery are confirmed against the actual files; a general service description is not a production approval.
Describe the via architecture, not only the HDI label
High-density interconnect design uses features such as microvias and fine routing to escape dense packages and connect selected layers. Identify the start and stop layers of every via structure, pad geometry, filled or capped requirements and any stacked or staggered relationships. A layer count by itself cannot communicate this architecture.
A notation such as 1+N+1 can describe one build-up layer on each side of an N-layer core construction, but the drawing must define the actual stackup and via spans. Confirm the interpretation with the manufacturer. It is not a universal capability specification or a substitute for a complete construction drawing.
Coordinate reliability, cost and package escape
Review the package pitch, escape strategy, copper balance and feasible via locations before freezing the layout. Sequential lamination, via filling and additional process steps affect the manufacturing proposal. Select the simplest construction that satisfies the electrical and mechanical requirements after review.
For demanding applications, agree material, thermal exposure, inspection, test coupons and relevant qualification evidence. Stacked structures and repeated thermal processing need evaluation for the actual construction. Do not infer reliability or an available process window from the term HDI alone.