New Electronic Packaging Method for Potted Guidance Electronics to Sustain Temperature Cycling and Survive High-G Applications

Abstract

Potted Guidance Electronics have been widely used in precision guided munitions. In the current generation of projectiles, soft potting materials have been sufficient to protect the electronics from the G-forces of gun launch at approximately 15 kG while sustaining uncontrolled extreme low temperature storage environments at different locations around the world. With on-going development of long-range precision guided munitions, stronger and hardened potting materials will be needed to survive gun-launch accelerations of 30 kG and higher. In the case of uncontrolled storage environments, the daily temperature fluctuations can act to dislodge/fail electronic components due to the coefficient of thermal expansion (CTE) mismatches between the potting materials and the electronic components. In this paper, a new protective layer method is presented, which consists of two tightly fitted preformed polymer layers, acting to mitigate the CTE mismatches, while only producing insignificant degradation of the supporting structure during extreme high-G projectile launch. The effectiveness of this new method is demonstrated by using finite element based modeling and simulation methods to examine a simplified potted electronics example. In the first step, the example was simulated with and without protective layers during an accelerated temperature cycling (−67 °F to 185 °F), and found that the protective layers were able to mitigate the CTE mismatch problem. During second step, the example compared dynamic responses between potted electronics with and without protective layers during a high-G, ∼15 kG, gun-launch simulations; results also showed that the degradation of the supporting structure introduced by protective layers during gun launch was insignificant.