Abstract: The solderability of pure tin coating on the external leads of IC devices in the integrated circuit industry has a significant impact on the soldering quality of products. The Improvement of wetting ability of external leads has great significance on enhancing soldering quality. This article takes LQFP packaging products as an example to study the effects of tin plating pretreatment, annealing temperature, and R angle of outer lead welding surface on the performance ofde-wetting during solderability testing. The growth behavior of intermetallic compounds and the surface tension differences formed by the R angle changes of the outer lead welding surface were studied. The results indicate that increasing the concentration of deoxidizing reagents is beneficial for improving the binding force between Cu and Sn grain boundaries and reducing the risk of de-wetting. Lowering the annealing temperature and increasing the annealing time are beneficial for forming a continuous and uniform intermetallic compound growth layer, which enhances the wetting ability. In addition, by reverse molding the external leads of the device, the larger R angle of the pin soldering surface is transferred to the non-soldering surface, reducing the surface tension of the soldering surface and enhancing the wetting ability of the solder on the outer-leads.Thus, the problem of abnormal wetting of the external leads of LQFP packaged products is completely solved. Finally, through the push-pull testing, it is shown that the improved device can withstand significantly greater thrust than before, providing a basis for the later analysis and control of such issues.