Cu wire neck fatigue fracturing elimination

This paper present the challenges of elimination on Cu wire neck fatigue fracturing issue after TC (Temperature Cycle) and IOL (Intermittent Operational Life Test). The qualification lots were detected fracturing after TC1000 cycles and IOL15000 cycles due to stress inner of package; after detail analyze the cross section samples, there is no any abnormal was found from fresh unit; but the minor cracks were detected along the grain edge of Cu crystalloid from TC/IOL units. A big challenge is to search out the key factors which are for fatigue fracturing. As presented in this paper, the Wire Looping Length, Looping Type, Loop Reversion Data, Free Air Ball Size, Wire Type, Wire Grain Size, Capillary Tip Angle, Compound Moisture, Curve Time and TC Profile were considered, DOE result indicate Tg & CTE of compound, package type and TC profile is Key factors for fracturing.