Drying before soldering is mandatory!
Flexible and rigid-flex printed circuit boards with polyimide are hygroscopic, i.e. they absorb moisture from the air even under normal room conditions. A dried polyimide film, for example, will have reached its moisture saturation level again after just a few hours. During the soldering process, the absorbed moisture can evaporate explosively, resulting in damage due to delamination, bubbling, tearing, etc. The original packaging is not moisture-proof.
The drying process must be qualified by the processor, the drying recommendations serve only as an approximate empirical value. Read our detailed drying specification here.
To facilitate and optimize the drying process, you can use our planning sheet for support.
Did you know that your PCB design is of great importance in this context? Learn more about the background and qualification of a suitable drying process.
A detailed Application Note "Physics of humidity & process of drying printed circuit boards" can be found here.
You also have the option to re-watch our webinar "Moisture in Printed Circuit Boards - developing an efficient drying process" or download the associated webinar presentation.
