Drying flexible and flex-rigid circuit boards
Drying before soldering is a must!
Flexible and rigid-flex circuit boards with polyimide are hygroscopic, i.e. they absorb moisture from the air even under normal room conditions. A dried polyimide laminate e.g. reaches its moisture saturation point after only a few hours of exposure. During the soldering process, the absorbed moisture can vaporise explosively, resulting in damage such as delaminating, formation of bubbles, cracks, etc. The original packaging is not fire protected.