When the term “PCB” is used, many people think of a rigid PCB (printed circuit board). However, the term PCB can refer to either a rigid PCB or a flexible PCB. Flexible PCBs are more commonly known as flex circuits, but they are also known by other names including flex boards, flexible circuit boards, flexible printed circuit boards and, more officially, flexible electronics. Flex circuits have recently gained huge popularity due to the fact that they can be shaped, bent, twisted, and folded into limitless configurations. In the end, however, rigid PCBs and flexible PCBs serve, in the most basic sense, the same ultimate function, which is connecting various electrical and mechanical components together.
When to Use Rigid and When to Use Flexible
Rigid PCBs typically cost less than flex circuits. I say “typically” because when considering the total cost of ownership there are some applications that, when using flexible PCBs, may be less expensive compared to using rigid PCBs. To get a true and accurate understanding of the total cost of ownership, you first need to appreciate the fact that flex circuits may eliminate the need for components such as connectors, wire harnesses, and other circuit boards. By removing these components from a design, material cost, labor and assembly cost, and scrap cost are all reduced.
Many electronic devices (laptop and desktop computers, audio keyboards, solid-state drives (SSDs), flat-screen TVs and monitors, children’s toys, and various electronic gadgets) employ rigid PCBs instead of flexible PCBs. However, flex circuits may be found in ultra-compact and/or high-performance devices, including GPS units, tablets, smart phones, cameras, and wearables.
Greater sophistication is not the only reason to use flex circuits; low-tech applications (such as under-the-counter LED lights, see figure below) may utilize flex circuit technology, in some cases because it makes installation much easier.