Thin dielectrics, asymmetric copper and repeated thermal processing can make dimensional control a significant HDI concern.
What to consider
Review the finished board and assembly panel requirements together. Material balance, local copper distribution, support and assembly profiles can all matter. Define flatness requirements using an agreed method and conditions; a number without a measurement context is difficult to interpret.
A practical review example
If a dense BGA area sits on a locally unbalanced construction, review its copper distribution with the factory and assembler. Check both manufacturing flatness and behavior during the assembly process.
Checks before release
- Specify the measurement method and conditions.
- Review copper and material balance.
- Coordinate handling and assembly support.
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.
- Specify acceptance and thermal exposure before requesting a quotation.
- Match coupon structure and process history to production.
- Review deviations and failure evidence with the responsible engineer.
Technical references
Historical IPC microvia reliability warning (2019)Fabrication design guidelinesReferences checked 2 October 2026. Manufacturer data describes its stated construction and is not an HDIPCB.org manufacturing commitment.