Failure analysis and control of gold-plated lead solder joint cracks

After experiencing the mechanical and thermal environment test, one kind of electronic assembled Hall element experienced partial function failure due to the gold-plated pin solder joint cracking. Re-examination results showed that part of the Hall element pin solder joints also suffered partial cracking before environmental assessment tests. Due to the small assembly space of the component, it is difficult to effectively check the solder joint status after electrical installation. Therefore, analysis based on the cause of solder joint failure and targeted improvements are of great significance for improving the reliability of the spacecraft. The failure reasons were analyzed by observation of cracking morphology, metallographic testing and analysis of chemical composition. When the component pin welding position is not completely gold removed, brittle Au-Sn intermetallic compound (IMC) was observer along the cracked welding interface, which led to the generation of cracking source. Due to the stress concentration at the crack front, the crack expansion continued and caused solder joints failure under the effect of temperature alternating or external force. Ensuring the de-gold quality at soldering position and controlling the soldering position are of great significance for improving the reliability of the solder joints at the gold-plated leads.