元器件镀金引脚焊点开裂失效分析与控制

宇航元器件镀金引脚钎焊前，需对焊接位置进行去金搪铅锡处理，避免焊接界面生成脆性金锡化合物，防止在使用时受外力作用而发生焊点“金脆”开裂.文中针对某宇航型号所用霍尔元件镀金引脚的焊点经历环境试验后脱落的问题，对相关镀金引脚焊点的形貌、金相与界面结构进行分析. 结果表明，元件引脚焊接位置已进行去金处理，但其焊接位置末端局部去金不彻底，焊点界面局部区域生成脆性金锡化合物，导致焊点前端生成裂纹源；经历宇航级温度循环或外力冲击考核试验时，因裂纹前端存在应力集中，导致裂纹持续扩展并发生焊点开裂脱落失效.确保镀金引线焊接位置去金质量并严控钎焊位置，避免在焊点内局部区域生成脆性金锡化合物，对提升镀金引脚焊点可靠应用具有重要意义.

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.