Optimizing Flex for High Speed
The design of flex and rigid-flex interconnect assemblies is an exacting science, made more so when management of high-speed digital signals is an added requirement. This is because material choices that support highspeed signal integrity and impedance matching can significantly affect the flexibility, weight, size and packaging of a flex circuit assembly. Flex and rigid-flex design is successfully accomplished by following a recipe of best practices—executed via design rules in the layout software and other tools—to balance and manage the many trade-offs between conflicting layout and functional goals. To follow the recipe, successful flex and rigid-flex PCB designers depend on a clear understanding of the intended application, particularly how rigid and flexible sections will be packaged within the enclosure, or stressed during use. This initial step in the design process will largely determine the tradeoffs between signal integrity and mechanical properties.