Optimal Design of Vibration and Thermal Reliability of Printed Circuit Board Mounting Components for Space Electronic Equipment

Vibration and thermal factors are crucial in the reliability design of aerospace electronic equipment, particularly regarding its internal electronic components. These components must not only adhere to specific temperature derating requirements but also withstand vibration environments to ensure the mechanical integrity of leads and solder joints. The paper employs a flat package component in aerospace electronic equipment as a case study. Initially, utilizing the heat conduction theory, the case and junction temperatures of the component were computed using theoretical formulas for various heat dissipation methods. The validity of the theoretical analysis was then confirmed through finite element analysis. Subsequently, the stresses experienced by the component leads were determined via finite element analysis under random vibration. Following this, the fatigue life and damage ratio of the component leads were calculated using the Palmgren-Miner cumulative damage theory. The analysis reveals that without a thermal conductive bracket, the stress on the component lead remains minimal, meeting mechanical environment requirements, yet failing to meet thermal design specifications. Upon integration of the thermal conductive bracket, varying thicknesses of the bracket affect the junction temperature of the component inversely proportional to the stress on the component lead. A thicker bracket results in a lower junction temperature but higher stress and reduced fatigue life, and vice versa. Finally, a comprehensive consideration of vibration and thermal factors led to the selection of the optimal thickness for the thermal conductive bracket. This selection not only satisfies the component junction temperature derating criteria but also ensures that the fatigue life of the component leads meets usage requirements.