Enhanced Design of Airborne Radiation Sensor for Improved Survivability During Deployment Impact

Abstract

By employing optimized outer packaging designs and materials, the impact energy can be effectively absorbed or dissipated, thereby preventing potential damage to interconnections and chips. This includes mitigating solder-joint fractures, chip cracks, pad cratering or lifting, and other mechanical stresses that commonly result from impact forces. To ensure that the internal ionic sensor remains resilient to moisture intrusion and can endure impact velocities of up to 30 mph, advanced packaging solutions have been developed. In this study, the ANSYS/LS-DYNA finite element analysis (FEAs) tool was utilized to evaluate the performance of various packaging designs in minimizing the shock energy transferred to the printed circuit board (PCB). Modifications were made to the external foam packaging to increase the effective thickness and stiffness of the PCB, thus limiting its deformation under impact. These adjustments involved testing several configurations, including a two-layer foam system, a single-layer foam, and variations in the foam material’s stress-strain characteristics. The results demonstrated a significant reduction in PCB deformation—by 86.9%—with the final design achieving a deformation of just $52~\mu $ m, compared to $398.7~\mu $ m in the initial design. Furthermore, the simulations of the final design were conducted for different drop orientations to ensure that out-of-plane deformations remained within the same order of magnitude, regardless of the drop direction.