Heavy copper PCBs (thick copper) feature copper thickness ≥2oz/ft² (70μm), designed for high-current, high-power, and thermal management applications, with maximum industrial thickness reaching 30oz/ft² (≈1050μm). Copper thickness is measured in oz/ft² (weight per square foot), with 1oz=35μm (±10% tolerance). Standard PCBs use 0.5oz (17.5μm) for HDI and 1oz (35μm) for general electronics, while heavy copper starts at 2oz and extends to 30oz for extreme power needs.

Common heavy copper thicknesses:

2oz (70μm): Power supplies, motor drivers, 5–10A circuits

3oz (105μm): Industrial controls, LED lighting, 10–20A circuits

4oz (140μm): Automotive electronics, battery management, 20–30A circuits

6oz (210μm): Inverters, solar power, 30–50A circuits

8–10oz (280–350μm): High-power servers, electric vehicles (EV), 50–100A circuits

12–20oz (420–700μm): EV charging stations, industrial machinery, 100–200A circuits

25–30oz (875–1050μm): Extreme power (grid equipment, heavy machinery), maximum commercial thickness

Factors limiting maximum copper thickness:

Manufacturing feasibility: Thicker copper requires longer etching times, increasing line width/spacing tolerances (minimum 6mil/6mil for 10oz+), raising costs and reducing yield.

Thermal stress: Thick copper expands/contracts more with temperature, risking delamination in multilayer PCBs (limited to 10–12oz for standard multilayers; 20oz+ for single/double-sided).

Drilling challenges: Thick copper causes excessive drill wear and burrs, requiring specialized tools and processes.

Design constraints: Thick copper limits fine-line routing, making it unsuitable for high-density circuits.

Applications for maximum thickness (20–30oz):

Electric vehicles (EV): Battery management systems (BMS), motor controllers, and high-voltage distribution units (HVDB) handling 200A+.

Renewable energy: Solar inverters, wind turbine converters, and energy storage systems (ESS) requiring high current and heat dissipation.

Industrial power: Heavy machinery, welding equipment, and high-power motor drives.

Aerospace: High-power avionics and power distribution systems.

In summary, the maximum commercial copper thickness for heavy copper PCBs is 30oz/ft² (≈1050μm), with 20oz being the practical limit for most multilayer applications. Thicker copper enables higher current carrying capacity (up to 500A), improved thermal dissipation, and reduced voltage drop, making it essential for modern high-power electronics.