Compact controls may need dense processor escape while also handling noisy power, connectors and a demanding environment. Plan those functions together.
What to consider
Do not apply fine HDI clearances to circuits that require greater spacing for their voltage or environment. Separate the dense low-voltage escape problem from insulation, current and thermal requirements. Ground strategy and connector return paths need attention where fast digital circuitry meets long external cables.
A practical review example
A control board can use local HDI near the processor while retaining larger copper and spacing around power and interface regions. Define those regions explicitly in the design rules.
Checks before release
- Use the applicable product spacing requirements.
- Review noise coupling and cable interfaces.
- Keep high-current and fine-pitch constraints separate.
Connect this decision to fabrication
Use the material selector 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.
- Start with enclosure, interface and assembly constraints.
- Budget space for test access and rework.
- Qualify the final product for its actual use environment.
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.