Standard printed circuit boards, whether double-sided or multilayer, are manufactured using a combination of copper etching and plating processes. Circuit layers start as thin sheets of copper foil that are etched to remove unwanted copper, and plated to add copper thickness to planes, traces, pads and plated-through-holes. All of the circuit layers are laminated into a complete package using an epoxy-based substrate, such as FR4 or polyimide.

Boards incorporating heavy copper circuits are produced in exactly the same way, albeit with specialized etching and plating techniques, such as high-speed/step plating and differential etching. Historically, heavy copper features were formed entirely by etching thick copper clad laminated board material, causing uneven trace sidewalls and unacceptable undercutting. Advances in plating technology have allowed heavy copper features to be formed with a combination of plating and etching, resulting in straight sidewalls and negligible undercut.

Plating of a heavy copper circuit enables the board fabricator to increase the amount of copper thickness in plated holes and via sidewalls. It’s now possible to mix heavy copper with standard features on a single board, also known as PowerLink. Advantages include reduced layer count, low impedance power distribution, smaller footprints and potential cost savings. Normally, high-current/high-power circuits and their control circuits were produced separately on separate boards. Heavy copper plating makes it possible to integrate high-current circuits and control circuits to realize a highly dense yet simple board structure.

The heavy copper features can be seamlessly connected to standard circuits. Heavy copper and standard features can be placed with minimal restriction provided the designer and fabricator discuss manufacturing tolerances and abilities prior to final design