Potted electronics are becoming more common in precision-guided artillery due to demands for increased structural-robustness. In field artillery applications, the potted electronics are inactive for most of their lifetime. Projectiles may be stored in a bunker without environmental (temperature and humidity) controls for up to 20 years. In contrast, the electronics for most commercial applications tend to be active for most of their lifetime and the operating environment is more predictable. This difference makes the thermal management task for the artillery application challenging. The ability to accurately analyze these designs requires the use of fully coupled thermal-stress transient-analysis with accurate material properties over the full temperature range. To highlight the thermal-stress transient effects, the potted configuration of a typical electronics assembly is analyzed. The thermal analysis indicates that significant stresses can develop in critical locations as a result of temperature cycles. The structural dynamic responses of unpotted and potted assemblies, subjected to gun-launch environments, are also compared. The results indicate that for the potted design, the dynamic response of the processor board is attenuated by the potting material.

Miniaturized electronics and components are becoming more common in precision-guided artillery-launched munitions and missiles. Due to the highly dynamic nature of projectile launch, and the demands for increased structural robustness, many miniaturized smart munitions resort to a potted design in order to achieve functionality and reliability requirements. In most of these applications, the potted electronics are inactive for most of their lifetime and may be stored without environmental (temperature and humidity) controls for up to 20 years. The uncontrolled environment for smart munitions however makes the thermal management task especially difficult due to the coefficient of thermal expansion (CTE) mismatch between the potting material and the electronic components. It has been previously observed that modeling a potted device, in support of its development through finite-element simulations, is a complex task due to the numerical-convergence issues, material properties and meshes, during simulations as well as resource limitations. In this paper, we will present a modeling/simulation methodology which can be used in the development of miniaturized potted smart munitions and the product qualification process. There are two basic tests that a potential new munition needs to satisfy: 1) a highly accelerated temperature-cycling life test (HALT), to emulate the un-controlled projectile storage environment and, 2) the extremely high-G acceleration during a projectile launch. In this paper, we will present, 1) the use of finite-element analysis to support design decisions to overcome the CTE differences between electronic components on the circuit board assembly and the potting material and, 2) the use of finite-element simulations to study and improve the survivability of the electronic components on the circuit board assembly during extremely high-G acceleration projectile launches.