The role of copper foils in printed circuit boards

When Forbes magazine recently addressed the topic of 3D printing, it argued that while technology has advanced for “making plastic and metal parts, for other applications, such as printed circuit board manufacturing, [3D printing] it’s only in the early stages of proving its viability.” In the meantime, however, printed circuit boards work perfectly fine with their current way of doing things—that is, using copper foil in their design.

For those unfamiliar with the term, Wikipedia defines Printed Circuit Boards or PCBs as a means of mechanically supporting and electrically connecting electronic components. And while they may not be part of the everyday vocabulary of the average individual, one finds them everywhere in the 21st century world. This is because “they are used in all but the simplest of electronics.”

So what does this component include that is so integral to so many of today’s electronic devices? Printed circuit boards wouldn’t even exist, let alone perform such a vital function, were it not for the incorporation of copper foil into their design.

More specifically, as Wikipedia notes, they use “conductive traces, pads, and other features etched onto sheets of copper laminated onto a non-conductive substrate.” Boards come in one of three variations, single-sided, double-sided, or multi-layered. The differentiation between the three types has to do with the number of layers of copper foils that are involved (ie, one layer for a single face, two layers for a double face, and multiple sheets for multiple layers).

The following is a step-by-step procedure of how a typical printed circuit board is made:

1. With today’s electronics demanding that their circuit boards be as small as possible, small, light, and flexible are the orders of the day. While the boards themselves accommodate these requests, the cables that connect to them must be dense enough to handle all of the electronic interaction that takes place within the devices. As a result, most growing today starts with a flexible substrate. This flexibility not only allows the board to be reshaped to fit in and around miniature crevices where required, but also allows for three-dimensional cabling.
2. The polymer from which today’s printed circuit boards are constructed is then laminated to the top surface of a sheet of copper, typically 110 or ED copper.
3. The copper foil is then etched with the pattern of the circuit that the wiring will follow.
4. A second layer of polymer is applied to the copper foil to insulate the circuit board. This coating also prevents the copper foil from corroding.
5. Finally, all the electronic components of the device are connected to each other.

The end result, especially on circuit boards that have multiple layers of copper foil, precipitates the complex interconnected wiring that makes modern electronics so sophisticated. Furthermore, it achieves this goal at a cost affordable to the manufacturer. A copper foil and foil primary converter and distributor facilitates this process.