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基于结构函数理论,运用改进电学测试法,对同一器件管壳与基板间的不同界面进行研究,发现其积分结构函数曲线发生了分离;通过该分离点确定器件稳态结壳热阻值,获得了器件内部各结构层的热阻分布。比较测试结果与理论值,两者基本一致。该测试方法简单、方便,比传统热阻测试法准确且重复性好。对比了采用不同封装工艺的器件的微分结构函数,观察发现,其峰值位置发生了偏移;进一步的超声波扫描证实了偏移的原因是存在焊料层空洞,提出了相应的改善措施。研究表明,利用结构函数理论分析功率VDMOS器件热特性是一种准确而可靠的方法。
Based on the structure function theory, the improved electrical test method is used to study the different interface between the package and the substrate of the same device, and the integral structural function curve is found to be separated. The thermal resistance of the device steady state crust is obtained through the separation point. Thermal resistance distribution of each structural layer inside the device. Comparison of test results and theoretical values, the two are basically the same. The test method is simple and convenient, accurate and repeatable than the traditional thermal resistance test method. The differential structure functions of devices with different packaging processes were compared. The peak positions of the devices were observed to be offset. The further ultrasonic scanning confirmed that the offset was due to the existence of the solder layer void and the corresponding improvement measures were proposed. The research shows that it is an accurate and reliable method to analyze the thermal characteristics of power VDMOS devices by using structural function theory.