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Solder Crack Improvement For A Power Package During TCT And PTC By Simulation

As one of challenges, clip design and BOM selection leadframe design for power package is becoming a key to achieve high requirement from customer. However, solder cracks is a key concern for power package during thermal cycling test (TCT) and power cycling test (PTC). Therefore, design optimization has to be done to reduce the risk on reliability as low as possible.In this study, simulation models are setup considering different factors, such as EMC, clip design, solder thickness and die thickness for a power package during PTC. Simulation data show effects of these factors on solder plastic strain, indicating solder crack improvement by higher-CTE EMC, thicker solder, thinner die, and continuous clip design. Based on recommendation by simulation, samples with selected EMC, J-bent clip and thicker die solder thickness were made for reliability testing, which already passed 4000 cycles TCT. Experimental data well matched simulation data. The paper demonstrated a good case of simulation driven development.