On the prediction of optimal baking schedules in plastic SMD microelectronic devices

Moisture concentration at the critical material interface is the key parameter as far as moisture sensitivity of a plastic package is concerned. Using a simple 1-D moisture diffusion model, this parameter allowed us to predict the optimal baking time at 125°C for P-DSO14 and MQFP80: 4–16 and 6–24, hours, respectively, depending on the considered material interface. The theoretical predictions agree well with the experimental results. On the other hand, the standard IPC/JEDED J-STD-033C recommends a distinctly longer baking time of 43 hours.