Comparative FEM thermo-mechanical simulations for built-in reliability: Surface mounted technology versus embedded technology for silicon dies

The printed circuit assembly market has been interested in embedded component technology for the last two decades in order to increase both integration density and performance of electronic boards. The objective of this technology is to integrate components, actives and passives, in internal layers of printed circuit boards (PCBs). In addition to the RF performances, the electromagnetic compatibility (EMC) characteristics are improved and the reliability increase. New opportunities in the miniaturization of devices emerge with embedded components technology in a wide range of business areas, as automotive or aeronautics sector. If the embedding of thin film passives in PCBs is now well known, few studies have been performed on active components. The manufacturing process results in stresses on embedded chips due to the assembling method, the temperature and material properties. In the present work, simulations based on Finite Element Method (FEM) have been performed to study the thermo-mechanical behavior of such embedded active components during its operating lifetime. In particular the strain energy density is estimated using a dedicated model for solder joint fatigue based on the Darveaux's methodology. The objective of the present study is to compare the estimated lifetime of solder joints of a surface mounted active component and the same embedded active according to the thermoplastic resin substrate used (for PCB). The influence in operating lifetime of main thermo-mechanical properties, as CTE (Coefficient of thermal expansion) and Young's Modulus, of the resin in embedded package allow to determinate the relevance of use very low CTE resin substrate.