Heavy Copper PCB
Power Without Compromise

Technology Overview

Why Heavy Copper PCB?

Standard PCBs use 1oz (35µm) copper — fine for signals, but insufficient for power electronics where currents reach tens or hundreds of amps. Heavy copper PCBs use copper thicknesses from 4oz (140µm) to 12oz (420µm) on outer layers, dramatically increasing current-carrying capacity and thermal dissipation.

The challenge isn't just plating thicker copper — it's etching fine features in thick foil, applying solder mask that won't crack over tall copper steps, and managing thermal expansion mismatches. Our heavy copper process addresses all three, with double-coat solder mask for copper weights above 4oz and controlled etch compensation for trace geometry integrity.

• Outer layers: 4oz, 6oz, 8oz, 10oz, 12oz (140-420µm)
• Inner layers: up to 6oz; mixed weights (signal 1oz + power 6oz)
• Bus bar: laminated copper to 40oz for 200A+ distribution
• Thermal management: integrated copper-core or aluminum-clad options

Manufacturing Process

Etching & Masking
for Thick Copper

Heavy copper processing requires specialized etch techniques. Standard alkaline etch that works for 1oz copper would undercut 12oz traces by 6-8 mil per side. We use optimized etch compensation — the phototool has wider traces to account for lateral etching — and step-plating where copper is built up in multiple plating cycles for uniform thickness control.

• Etch compensation: phototool traces widened by 0.5-1.0× copper thickness per side
• Step plating: multiple DC plating cycles for uniform 12oz thickness ±10%
• Double-coat solder mask: first coat fills copper steps; second coat provides uniform surface
• Thermal stress test: every lot undergoes 288°C / 10s solder float — zero delamination
• Microsection: cross-section verification of copper thickness and etch profile on coupon