Moisture diffusion in Printed Circuit Boards: Measurements and Finite- Element- Simulations

When printed circuit boards (PCBs) are exposed to humid ambient conditions an absorption of moisture will occur. This infects the reliability of the PCB and also delamination can occur during reflow. Copper layers in the PCB act as diffusion barrier and have an influence of the moisture distribution and out of this an influence on the moisture concentration in the PCB. Depending on the location the time to get dry PCB increases. In this paper the measurement of different PCB samples will be compared with concentration distribution out of simulations.