Effect of Die Thickness on the Reliability of Solder Joint in Clip-bonded Packages

Thin die is more and more widely used in power packages for automotive applications due to their lower electrical resistance and better thermal dissipation. For thin wafers, die pickup operation is a critical aspect in the assembly manufacture process. The use of inappropriate tape stickiness and ejection parameter settings can cause microcracks that can eventually lead to die cracking. Increasing die thickness may be an alternative solution to reduce die cracks ppm issues (by increasing the mechanical strength of the die). Obviously, the increase of die thickness will result again to high die resistance. Additionally., thicker die may worsen the thermal fatigue behavior of the die attach solder. The scope of this study is to confirm the impact of solder joints fatigue behavior in clip bonded package using different die thicknesses by subjecting devices to temperature cycling (TC) and thermal fatigue tests (IOL/TFT). Furthermore, simulations and visual inspection using cross-sectioning were used to inspect the die attach degradation on various samples after aging tests. This study also provides a vital information of the relationship between solder degradation and different die thicknesses, which can be used as reference for future wafer thickness reduction programs to achieve a better product RDSon.