Flex circuitry is ideal for many of today’s electronics needs. It is light, compact, and, if properly designed,extremely robust. Because it bends, however, a flex circuit has some very specific requirements that aredifferent from those of traditional rigid circuits. Materials, circuit architecture, placement of features, and thenumber of layers in the circuit must all be considered in the design process. So must the degree to which thecircuit will be bent, how tight the bend will be, how the bend will be formed, and how frequently the circuit will be flexed. By carefully defining the application and design priorities and recognizing the unique demandsmade upon flex circuits, the designer can work within these requirements to realize the technology’s fullpotential.
The most frequently asked question we receive regarding flex circuits is “how much can I bend a flex?” The standard IPC answer is 10 times the thickness of the material. There is a section in IPC-2223 that offers reasonable information on bend radius calculations. But there are other factors that need consideration when designing a flex circuit for high reliability.
Because the IPC standards are conservatively written to take into account many factors that can affect circuitresilience, it is possible to safely achieve lower-than-standard bend ratios. However, due to the number offactors that can affect performance at smaller-than-recommended bend ratios, it is highly advisable thatdesigners work with an experienced flex circuit manufacturer in developing such designs.