Abstract
Crack propagation tests of lead-free solder were conducted using center-notched plates under three cyclic tension-compression load controlled waveforms: pp wave is fast loading and unloading, cp-h wave is tension-hold and cc-h wave is tension and compression hold. Creep crack propagation rate of cc-h and cp-h wave shape was calculated by the subtraction of fatigue crack propagation rate from total crack propagation rate. The relationship between creep crack propagation rate and creep J-integral showed parallel two lines for cc-h and cp-h wave shares, showing 10 times faster for cp-h than cc-h. Microscopic crack propagation path was examined with SEM in correlation with the microstructual change measured by EBSD. Grain fragmentation and KAM (karnel average misorientation) observed near the crack tip with EBSD changed depending on the wave form.
