Definition of a Heavy Copper Printed Circuit Board

While there is no industrial standard definition of "heavy copper", PCB International follows the industry accepted definition that 3oz of copper or more on either the internal or external layers of a printed circuit board qualifies as a heavy copper printed circuit board.

PCB International and Heavy Copper Printed Circuit Boards

At PCB International, we strive to provide the best quality printed circuit boards with wide variety of design characteristics to suit all your project needs; we can supply printed circuit boards up to 36 layers, and copper weight up to 20oz. PCB Universe' Instant Online Quote Engine can provide quotes for boards requiring copper weight up to 2oz, and up to 24 layers; printed circuit boards requiring copper weight of 3 - 20oz and/or layer count 25 – 36 layers require custom quoting. You can do so by contacting us with your requirements and/or Gerber files.

Benefits of a Heavy Copper Printed Circuit Board

The primary benefit of heavy copper circuit boards is the capability to survive frequent exposure to excessive current, elevated temperatures and recurring thermal cycling, which can destroy a regular circuit board in seconds. The heavy copper board has a higher tolerance capacity, which makes it compatible with applications in rough situations such as defense and aerospace industry products, power adapters/alternators, thermal regulators, etc.

Additionally, consider using a heavy copper printed circuit board for the following benefits:
  1. Compact product size due to higher copper weights on the same layer of circuitry;
  2. Heavy copper-plated vias pass the elevated current through the board and assist in transferring the heat to an outer heat sink for more efficient heat dissipation;
  3. Capability to accommodate onboard high-power-density planar transformers
Common Usage of a Heavy Copper Printed Circuit Board

A heavy copper printed circuit board boasts an improved copper weight, along with the suitable high-temperature laminate material and thicker through-hole copper plating can change a weak board into a long-lasting and dependable wiring platform. Heavy copper conductors can increase the entire PCB thickness considerably. The copper thickness should always be considered during the circuit design stage. The current-carrying capacity is determined from the width and thickness of the heavy copper.

Heavy copper Printed Circuit Boards are used for multiple purposes such as in planar transformers, heat dissipation, high power distribution, power converters, etc. There is an increased demand for heavy copper-clad boards in computer, automotive, military, and industrial controls. Heavy copper printed circuit boards are also used in:

  • Power supplies, power converters
  • Power distribution
  • Welding equipment
  • Automotive industry
  • Solar panel manufacturers, etc.

Thick copper Printed Circuit Boards have started to see more extensive use in power electronic devices and power supply systems. This unique type of heavy copper PCB features a finished copper weight of more than 4oz (140μm), compared to the 1oz (35μm) or 2oz (70μm) copper weight generally found in standard designs.

Heavy Copper Printed Circuit Board Design Guidelines

Heavy copper printed circuit boards may require a thicker final board thickness due to increased copper weight, particularly if controlled dielectric requirements are also present. PCB International strongly recommends sending us the Board Stackup to so we may confirm your desired board thickness and copper weight requirement can be successfully achieved.

With heavy copper Printed Circuit Boards, minimum trace width and space requirements are increased due to the increased risk of causing unintended short circuits. See below (Table 1) for recommended minimum trace width and space for heavy copper boards up to 8oz. Please keep in mind that we are capable of smaller trace/space per oz than shown in this table. However, the pricing is higher, and requires a custom quote. For all heavy copper Printed Circuit Boards, PCB International strongly recommends that our clients send us their board requirements and Gerber files for review, and to obtain a quote.

Table 1: Recommended Minimum Trace Width and Space for up to 8 oz

Min Trace/Space by Cu Weight (outer layers) Capability
Cu Oz Min Trace (mils) Min Space (mils)
0.5 4 4
1 4 4
1.5 6 6
2 8 8
3 11 11
4 12 12
5 20 20
6 24 24
7 28 28
8 32 32

If you have any questions, please don't hesitate to contact our knowledgeable support team or email us directly at

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