Package Design Through Reliable Predictive Modeling and Its Validation

Abstract

The outer packing of electronic products plays a significant role in keeping inner electronics’ functionality. The different designs and materials of outer packing would decrease or isolate the impact energy that further damage the interconnection or chip (such as solder-joint failure, chip-cracking, and pad cratering), which could let the product survive in some extreme working conditions. A specific outer packing was designed for the special inner electronics which need to survive at high-speed impact, 30 mph, and the outer packing should also be moisture resistant. The simulation software, ANSYS/LS-DYNA, was used in this work. Two configurations of outer packing were investigated, one is sphere structure, another is hockey puck structure. Several other parameters were also investigated, like the single layer vs double layer (soft outside hard/stiff inside vs hard/stiff outside soft outside), pimple design (plain vs inner pinball vs extruded pinball), and material of outer packing. For the material of outer packing, foam material, as a well-known shock-absorbing material, was selected for this work. Due to the moisture resistance requirement, there are several closed-cell foams were selected, such as ethylene propylene diene monomer (EPDM), polyethylene, polyvinyl chloride (PVC), polychloroprene (Neoprene_1(smaller density), and Neoprene_2(larger density)). The compression experiments and simulations were performed for each selected foam to validate the finite element model of each foam. And because the strain rate of foam material always changes during the entire impact event, the predicted simulations were performed to obtain the correct material property of foam by using the validated FE foam model. The final design was decided by the predicted material properties of each foam.