中文摘要：

应用差示扫描量热（DSC）法、润湿平衡分析技术和拉伸试验,研究了Sn-XAg-0.5Cu（X=0.1-3.0）无铅钎料合金的熔化特性、润湿性能及力学性能。实验结果表明：所有钎料合金的开始熔化温度均为217.3℃;随合金中Ag含量增加,熔化温度区间变窄。钎料的润湿铺展面积和润湿力随Ag含量的增加而先显著增加,而后趋于稳定;对润湿铺展面积和润湿力（或润湿时间）产生显著影响的阈值Ag含量为1.0%（质量分数,下同）。Ag含量在0.5%-3.0%时,随着Ag含量的增加,钎料的断后伸长率逐渐下降,而抗拉强度和0.2%屈服强度均逐渐增加。

英文摘要：

The melting property,wettability and mechanical property of Sn-XAg-0.5Cu（X=0.1-3.0） lead-free solder alloys were investigated by differential scanning calorimetry（DSC）,wetting balance technique,sessile drop method and tensile test.The DSC revealed that the endothermic onset temperature on heating appeared at about 217.3℃ for the all solder alloys.With increasing the Ag content of the solder alloys,the melting temperature ranges of the solders became narrow.It was also shown by the wetting balance and sessile drop experiments that the wettability remarkably increased with the Ag content increased,and then with Ag content farther increased,the wettability were kept constant approximately.The threshold value of the Ag content was 1.0%（mass fraction/%,the same below）,which considerably effected on wetting-spreading areas and wetting forces（or wetting time）.Meanwhile,when Ag content is between 0.5% and 3.0%,the specific elongation of solders decreased with the Ag content increased,while the tensile strength and 0.2% yield stresses increased,too.