Advances in vapor pressure modeling for electronic packaging

Two advanced techniques have been developed for modeling vapor pressure within the plastic IC packages during solder reflow. The first involves the extension of the "wetness" technique to delamination along multimaterial interface and during dynamic solder reflow. Despite its simplicity, this technique is capable of offering reliable and accurate prediction for packages with high flexural rigidity. For packages with low flexural rigidity, the new "decoupling" technique that integrates thermodynamics, moisture diffusion, and structural analysis into a unified procedure has been shown to be more useful. The rigorous technique has been validated on both leadframe-based as well as laminate-based packages. With high accuracy and computational efficiency, these dynamic modeling tools will be valuable for optimization of package construction, materials, and solder reflow profile against popcorn cracking for both SnPb and Pb-free solders.