Starting with the construction of your flexible circuit boards you first need to choose the appropriate techniques and right materials. In our company we prefer the use of polyimid material. We also use polyester, but it should be wisely chosen for fields like shielding foils or other subordinated functions.
The thinner the final product is, the better the bending features are and also the amount of life time bending cycles.
Before soldering the plated-through polyimid-FPCs, you need to anneal these for 3h at 140°C degrees, otherwise the circuit boards can be damaged.
In case of onesided flexible circuits you can forego this process, but we also recommend predrying with these articles.