Evolution of interfacial intermetallic compound in small solder joint of fine pitch flip chip during reflow

Through the cyclic load-unload test of nano-indentation method,the effects of maximum load on cycling mechanics behavior for two kinds micro-solder joints of Sn-3.0Ag- 0.5Cu/Cu and Sn-0.3Ag-0.7Cu/Cu were investigated.The results indicated that the cycling F-h curves that before closed showed a hysteresis loop.The area of hysteresis loop and indentation residual depth of micro-soldered joints increased with the increase of the maximum load.The cumulative damage of microsoldered joints increased.When the maximum load was given, the area of hysteresis loop and increments of residual indentation depth decreased gradually with the loading time increasing.Indentation creep C of micro-soldered joints decreased with the increase of the maximum load.At the same time,indentation creep C of micro-soldered joints sharply decreased at first and then plateaued with the loading time increasing.Indentation creep C of Sn-3.0Ag-0.5Cu/Cu micro-soldered joint was less than that of Sn-0.3Ag-0.7Cu/Cu micro-soldered joint.