Abstract: The soldered joint flaws were studied and the optimum solutions were given on the base of classifying the flaws into two kinds.For the first flaw, the energy control equation was established to stimulate the effect of ball size and the relative position to the formation of soldered joint using the Surface Evolver software.The result shows that the optimum ball size is 120μm ±5μm, and length of the slidered pad to the suspension pad D_M-S is 2.5~5.0μm, the distance of the suspension pad to the slidered pad D_S-M is 20~40μm. For the second flaw, the Au layer is optimized from 5μm to 2~3μm and the leading wire was shorten to avoid the formation of intermetallics deposit flaws.The optimum result shows that the soldered joint undergo 700 circle test circulate, the percent of flaws in the solder joint was shorten from 7%~8% to 0.63%.