Ni underlayer efficiency investigation for whisker mitigation in IC packaging

In the study, the Ni underlayer plus matt Sn plated packages in PLCC, PDIP and LQFP were subject to SnAgCu and SnPb surface mounting and wave soldering respectively on the PCB with OSP surface finish, then followed by TCT (-55 to 85) 1000 cycle, THT (60 /90%RH) 3000 hrs to investigate whisker growth propensity. The practical whisker performance confirmation on the PCB beyond reflow simulation and component level was concluded to understand the Sn whisker potential in term of Ni underlayer efficiency. Additionally, various Sn thickness over Ni layer in package level was also applied to explore the Sn thickness effect on the whisker growth over TCT.