PWB Vs. PCBby Gina Poirier
If you are a student or professional in electronics manufacturing, you probably face the conundrum that many of your colleagues share: the difference between PWB and PCB and which is the right term to use. The difference between the two is subtle, and there is officially no "correct" term. Two U.S. electronics industry associations and a Japanese engineer provide some insight into the terms' uses.
PWB stands for "printed wiring board." The Surface Mount Technology Association defines the PWB as "The substrate, generally epoxy glass, used to provide component attachment lands and interconnections to form a functioning electronic circuit." PCB stands for "printed circuit board." According to the IPC Association Connecting Electronic Industries, on a PCB "the width, side to side and multi-layer relationship (spacing) of conductor runs has or is designed to have a specific effect on circuit operation other than just a point to point connection. Circuit impedance is a primary issue." The subtle difference between the terms is that PCB emphasizes the completed circuits on a board, while PWB refers more to the board itself.
PCB and PWB are often used interchangeably in the U.S. electronics industry. The IPC "Connections" blog explains that PWB is an older term that was used more frequently for the boards when the electronics industry was in its infancy. Back then, "the issue was only a point to point connection" on the boards. The term eventually evolved to describe the functions of circuit technology. Accordingly, "In approximately 1999 the IPC Technical Activities Executive Committee made a mandate" that now PCB is used only for new document development because "more often than not the printed circuitry design will have an impact on function."
Geography also determines what term is used. Japanese electronics engineer Seiichi Inoue explains that while PCB tends to be the preferred term in the modern U.S. electronics industry, PWB is preferred in modern Japan. Conversely, when the electronics industry was first emerging in Japan in the 20th century, PCB was more common. The term was eventually replaced with PWB because PCB also stands for "polychlorinated biphenyls," or a form of poison.
If you're preparing a document, you have to decide which term to use. The answer is . . . it depends. The modern trend in the U.S. is to use PCB, but both terms appear frequently in documents from different time periods and localities. Consider your expected audience. For example, if the primary readers of your document are older, they may prefer PWB regardless of modern trends. Whatever you use, both terms are generally understood and accepted. According to the IPC's Connections blog, the difference is similar to "tomato, tomahto."