A study of thermal cycling and radiation effects on indium and solder bump bonding

The BTeV hybrid pixel detector is constructed of readout chips and sensor arrays which are developed separately. The detector is assembled by flip-chip mating of the two parts. This method requires the availability of highly reliable, reasonably low cost fine-pitch flip-chip attachment technology. We have tested the quality of two bump-bonding technologies; indium bumps (by Advanced Interconnect Technology Ltd. (AIT) of Hong Kong) and fluxless solder bumps (by MCNC in North Carolina, USA). The results have been presented elsewhere[l]. In this paper we describe tests we performed to further evaluate these technologies. We subjected 15 indium. bump-bonded and 15 fluxless solder bump-bonded dummy detectors through a thermal cycle and then a dose of radiation to observe the effects of cooling, heating and radiation on bump-bonds.