Study on leadframe overflow prevention of soldering paste using fluid-structure coupling analysis

With the development of social demand for power semiconductor packaging., the leadframe's design developed with high density manufacturing quality and low cost. The market demands packaging technology with high performance/price., handiness size., excellent thermal and electrical performance., optimizing packaging space., and reducing the lead spacing. On the other hand., we can also reduce the packaging size by reducing the die-attach area of the leadframe placement as much as possible. However., the overflow of solder paste in the baking process has always been the main challenge faced by QFN packaging. Based on the principle of fluid-structure coupling analysis of solder paste on the leadframeleadframe., We had analyzed the flow state of solder paste on the groove structure and selected the structure that can effectively prevent solder paste from overflowing. According to the manufacturing process of the leadframe., different models such as V-shaped grooves., rectangular grooves., and trapezoidal groove had established on the position of the frame where the chip had been placed., and different parameters are setting for these structures., e. i. The volume., spacing and depth of the grooves analyze the influence of the above parameters on solder flow. The results of simulation and experiment show that the rectangular groove is the most effective structure to prevent the overflow of solder paste. The wider the groove spacing at the edge of the leadframe., the shorter the solder flow distance. And when the depth and width of the groove are the same., the solder paste overflow is more effectively prevented. The leadframeleadframe's anti-overflow design prevents the short circuit of power dies to reduce the package device reliability and is used as a reference for the packaging process of power devices to solve electronic products' high-density packaging.