Nanomechanical Properties Of Sn-Ag-Cu Solders Joint Under Different Loading Method

Miniaturization, high integration and appearance designed of electronic products has been became the main direction of the current electronics industry pursuit. With the size of Lead-free solder joints decreasing, the reliability of solder joints is particularly prominent, which the mechanical behavior of solder joint is critical to its reliability. In the actual production process, the solder joint stress are often complex is a variety of stress results. In this paper, through different test of nano-indentation method, the mechanical behaviors of high-silver, low-silver and the BGA solder joint were added to rare earth elements La (x= 0-0.25) based on the low silver SAC0307,including the creep behavior of BGA solder joint, The graded behavior and BGA solder joints in the cyclic behavior of the shear directions,and different load were analyzed.Through the graded load-unload test of nano-indentation method, the effects of different experimental parameters for two kinds of BGA solder joints of Sn-3.0Ag-0.5Cu and Sn-0.3Ag-0.7Cu on graded performance were all investigated. Indention hardness, With the increase of the maximum load the. cause of residual indentation depth increases, under the conditions of the same loading force, when load the number of steps is increased the solder BGA solder joint damage accumulated increases, the CIT the value decreases with increasing load the number of steps; With the increase of the loading rate will lead to the increase of the plastic deformation of BGA solder joints; the BGA solder joints damage cumulative increases with the increase of the hold time; the creep depth magnitude with Hold time from 5s increased to 60s is much larger than the hold time increased from 120s to 180s; When the load step number increases, the increase in solder BGA solder joints of plastic work, and the two the solder creep depth differences are first rose to a peak and then decline.Through the cycle load-unload test of nano-indentation method, the effects of different experimental parameters for two kinds of BGA solder joints on cycling performance of the shear directions were all investigated. The results indicated that the cycling performance of Sn-Ag-Cu series Lead-free BGA solder joint was load-dependent, and the cumulative damage of BGA solder joint was increased with the increase of maximum load, especially largely accumulated in the first few cycles, Increase in the number of cycles will be to cause a the plastic deformation on the shearing direction of the BGA solder joints increasing trend; the creep displacement increased with the hold time increasing and creep-fatigue interaction will accelerate of BGA solder joints failure; the energy loss of Sn-0.3Ag-0.7Cu BGA solder joints is greater than the Sn-3.0Ag-0.5Cu BGA solder joint, while the indentation hardness showed the opposite trend.Through the load-unload test of nano-indentation method on Sn-0.3Ag-0.7Cu, Sn-0.3Ag-0.7Cu0.03La, Sn-0.3Ag-0.7Cu-0.05La, Sn-0.3Ag-0.7Cu-0.07La, Sn-0.3Ag0.7Cu0.10La, Sn0.3Ag0.7Cu0.25La six solder joints; Exported by O & P method and comparative analysis of the different content of La in the hardness, elastic modulus and creep sensitive index n; With the analysis of the mechanical behavior, BGA solder joint hardness, elastic modulus increased when the rare earth La elements increased, the creep resistance become increased, but has little effect on BGA solder joints,hardness, elastic modulus.