Why Is It Still Difficult to Make Accurate Prediction of the Warpage after Advanced Molding Processes?

With advanced computational mechanics techniques and computing hardware, one can simulate almost any kind of electronic packages. Thermo-mechanical properties required for numerical predictions, including the coefficient of thermal expansion (CTE), the glass transition temperature (Tg), the temperature and time-dependent viscoelastic properties, are routinely measured by commercial tools such as thermomechanical analyzer (TMA), dynamic mechanical analyzer (DMA) and universal testing apparatus. In addition, temperature-dependent warpage can be measured readily using commercial shadow Moiré and digital image correlation (DIC) tools. In spite of the considerable effort devoted for warpage prediction, accurate prediction of warpage is still a challenging task. This paper addresses three main reasons why the prediction is still difficult, and discusses what should be done to bring the prediction capability to a desired level.