A pre-production checklist for HDI microvia designs: via diameter, capture pad, aspect ratio, stacking and impedance — catch issues before they cost a respin.
Quick answer
Before releasing an HDI design, verify microvia diameter (≥75 µm), capture pad sizing, microvia aspect ratio (≤0.75:1 typical), stacked-via copper fill requirements, and impedance across transitions. Catching these in DFM avoids costly respins.
The checklist
- Laser via diameter — minimum 75 µm; smaller requires special review
- Capture pad — adequate annular ring for registration
- Microvia aspect ratio — keep depth-to-diameter reasonable for reliable plating
- Stacked vias — require copper-filled, planarized process
- Impedance — maintain reference-plane continuity across microvia transitions
- Material — confirm laminate supports your build-up and signal needs
Our engineers run this review on every HDI order before production.
FAQ
A microvia depth-to-diameter aspect ratio around 0.75:1 or lower is reliably plated and filled. Higher ratios are reviewed case by case.
Related capability: Any-Layer HDI PCB