There are three main types of flexible circuits: static, flex-to-install, and dynamic. Static circuits are not meant to flex, flex-to-install circuits are meant to flex only during installation/repair and can withstand limited flexing, and dynamic circuits are designed to withstand repeated flexing of over 1 million cycles. Key considerations in flex circuit design include avoiding stacked traces, using hold-down tabs, and calculating minimum bend radii based on circuit thickness. Common flex circuit materials include polyimide films like Kapton but PCB Solutions recommends Taiflex for most applications.