A majority of our day-to-day lives are intertwined with a wide range of electronic devices, including cell phones, medical devices, wearables, computers, servers and many more, regardless of their sizes, shapes, and uses. While most devices are flexible, efficient, and lightweight, they also have another thing in common — each includes at least one flexible printed circuit board. There are several advantages of using flexible circuit boards over the usual rigid types. These are listed below in order of their importance:
As the name suggests, the most prominent benefit flex circuit boards offer is flexibility. The elastic nature of flexible circuits allows them to be packaged, folded, and positioned around folds and edges. These are especially helpful in electronic devices that require connections in all the three axes. This also implies that flex circuits can almost replace all wiring, eliminating failure of wired connections, thereby increasing the reliability of the device.
Typically, flex circuit boards take up only 10% of the weight and space of wires within a device. Being thin and lightweight, use of flex circuits allow a substantial decrease in the dimensions and weight of devices—to the extent of 60% compared to that used up by rigid PCBs or wire harnesses.
Flexible circuit boards are made with polyimide as the standard base material, capable of as many as 200,000 bending cycles. This eliminates connectors and wiring harness failures in equipment with moving parts, such as printers, medical devices, and advanced cell phones.
Being flexible and lightweight, flex circuits can absorb and reduce the effects of shock and vibration to itself and related solder joint connections. This helps improve the performance and reliability of the device.
Flex circuits can dissipate heat at much better rates than do other dielectric materials typically used for rigid PCBs, while still offering the benefits of flexibility.
Apart from polyimide, flex circuits can be made from materials with properties such as water resistant, moisture resistant, shock resistant, high-temperature resistant, and oil and corrosion resistant. That enables the use of flex circuits in harsh operating environments—offering excellent UV exposure and radiation resistance.
Materials used for flexible circuits show exceptional thermal stability. Medical and military equipment makes substantial use of this feature in applications requiring high reliability.
Designers can reduce the packaging and material costs of the finished assembly, because the thin and flexible polyimide film requires a far smaller area. This also is reflected in the final assembled product, as it lower costs for the PCB assembly. For instance, flex circuits eliminate wire routing errors, which offers benefits such as reduction of test and rework times, and rejects.
Depending on the application, designers use four varieties of flex circuits, as specified by IPC 6013:
All of these offer the benefits of reliable 3-D circuitry applications along with providing a stable platform for components, stiffeners, flex PCB pins, heat streaks, and more. Designers prefer to use flex circuits because they offer improvements in impedance control, noise reduction, signal integrity, and reliability.
Flex circuits offer designers improvements in design freedom, as they reduce the device weight and mechanical space. For instance, the rigid-flex PCB, with HDI micro-vias, offers an inexpensive alternative to multilayer flexible printed circuit boards.