Isothermal low-cycle fatigue testing of microscale solder interconnections

A series of isothermal low-cycle fatigue studies of small to extremely small-volume solder joints has been conducted. These solder microjoints were designed and fabricated using processing which duplicates the microelectronics interconnection structures that might be used in high density, highly integrated flip-chip packaging and all fatigue tests were conducted in fully reversed simple shear both with and without dwells at maximum strain. Results of low-cycle fatigue tests of both single and double-bump 95/5 Pb/Sn solder microjoints in the form of Manson-Coffin (plastic strain amplitude versus fatigue life) plots and post-test failure mode analysis (FMA) carried out using scanning electron microscope (SEM) fractography are presented and evaluated. Paper was presented at the 1991 SEM Spring Conference on Experimental Mechanics held in Milwaukee, WI on June 9–12.