In the PCB industry, copper thickness is typically measured in ounces (oz). 1oz of copper evenly distributed across 1 square foot of surface area results in a thickness of 1.37mils. Please refer to the table below.

Copper Weight (oz/sq ft) Copper Thickness (mil)
0.5 0.685
1.0 1.37
2.0 2.74
3.0 4.11
4.0 5.48
Copper Weight (oz/sq ft) Copper Thickness (mil)
5.0 6.85
6.0 8.22
7.0 9.59
8.0 10.96
9.0 12.33

Most printed circuit boards are manufactured using a copper thickness with 1 to 3 oz. A heavy copper PCB has a copper thickness that is equal or greater to 3 per sq. ft in its outer and inner layers.

Heavy Copper PCB Capabilities

  • Max outer layer copper: 20oz
  • Multi layer’s max inner layer copper: 10oz
  • Max number of layers: 50 layers


For a custom quote please email your Gerber files to or request a Custom Quote
Phone number: (800) 348-9250

Advantages of Heavy Copper Printed Circuit Boards

Heavy copper PCBs provide better current conductivity and withstand exposure to excessive current loads. The current carrying capacity of a copper trace can be improved by increasing it width, thicker copper traces have higher current carrying capacity.

Improve thermal performance. Increase heat dissipation. Endure the reoccurring thermal cycles that occur during the fabrication and assembly processes.

Provide high mechanical strength at connector sites and in plated through holes.

Reduce board size due to copper layers.

Disadvantages of Heavy Copper Printed Circuit Boards

Heavy copper PCBs have a higher manufacturing cost than standard PCBs. They require more specialized equipment and greater expertise.

They are more difficult to work with. They can heavier and bulkier than other PCBs.

Manufacturing Heavy Copper Printed Circuit Boards

Heavy copper PCBs cannot be fabricated using the same copper etching and plating process used to fabricate regular printed circuit boards. Using the same process will result in over-etched margins and uneven trace sidewalls.

Heavy copper PCBs require specialized etching and plating techniques to achieve straight edges. It also requires electroplating to add thickness to the walls of the plated through holes.

Heavy Copper Printed Circuit Board Design Considerations

A PCB designer must take into consideration several factors when designing heavy copper PCBs to minimize board failure:

  • Current Carrying Capacity: The PCB designer must first determine the amount of current required and then calculate the copper weight, trace width and the maximum temperature rise that the PCB can withstand.
Copper Weight (oz/sq ft) Minimum Trace (mil) Minimum Space (mil)
0.5 0.030 0.030
1.0 0.035 0.035
2.0 0.008 0.008
3.0 0.010 0.010
4.0 0.012 0.012
  • Thermal considerations: The substrate material of choice must have a low TCE (thermal coefficient of expansion) to avoid cracks and layer separation, a high CTI, CAF resistance, and a high Tg (glass transition temperature) to withstand the high mechanical stress delivered to the plated holes.

Heavy Copper Printed Circuit Board Applications

Heavy copper PCBs are becoming increasingly popular due to their wide range of applications in the following fields:

  • Automotive: electric vehicle charging, electric motors control.
  • Power distribution: excitation systems for power regulators, power grid switching systems, high power rectifiers, and overload relays.
  • Transportation: power converters for railway systems, power line monitors, traction converters.
  • Industrial controls: safety and signal systems, welding equipment, protection relays, surge protectors.
  • Military: weapons control, radar, and monitoring systems.
  • Renewable Systems: power converters, energy storage, power grid back-up, hydroelectric power plants control panels.