Heavy Copper PCB Design Guidelines

Below are some key design considerations for heavy copper PCBs:

Layer Stacking

• Position thick copper layers close to the board center to minimize warpage.

• Do not place outer layers next to each other as it exacerbates registration issues.

• Rotate fiber weave direction 90° between adjacent dielectric layers for stability.

Component Placement

• Ensure sufficient clearance from plane layers for soldermask coverage.

• Account for component shadows falling on inner copper layers.

• Check for exposed copper at drilled holes.

Thermal Management

• Place heat generating components over thick copper layers to act as heat spreaders.

• Provide multiple vias beneath hot components to transfer heat to inner planes.

High Current Traces

• Use copper pouring/polygons for high current lines instead of routing multiple parallel traces.

• Place adjacent to plated thru-hole vias for heat dissipation.

Filled Vias

• Limit use of filled vias as they impair heat transfer compared to hollow vias.

• Countersink filled vias and keep soldermask clear of holes.

Panel and Tooling

• Allow generous tolerances for fabrication and assembly.

• Account for material shrinkage, stretching, and warpage.

• Use fiducials and test coupons on panel for easy tooling.

DFM Analysis

• Seek DFM feedback from fabricator during design phase.

• Check manufacturability, especially around heavy copper tolerance issues.

Early engagement with the PCB manufacturer smooths the design process and avoids issues during prototyping.