中文摘要：

研究了Cr元素对液态Sn-3.0Ag-0.5Cu（SAC305）焊料在280℃下表面抗氧化性能的影响,并通过扫描电镜（SEM）、俄歇电子能谱（AES）分析了焊料的表面氧化,探讨了Cr改善合金抗氧化性能的机制及其对SAC305无铅焊料显微组织和润湿性能的影响。结果表明,Cr元素的加入可有效提高焊料的抗氧化性,Cr元素在熔融的焊料表面易于生成Cr2O3,其先于Sn氧化形成一种保护性的致密氧化膜,阻碍了焊料的进一步氧化。当焊料中Cr的质量分数达到0.1%（质量分数）时,焊料表面的氧化膜光滑致密,SAC305-0.1Cr液态焊料具有很好的抗氧化性能。另一方面,Cr的加入降低了焊料的润湿性能,随着Cr含量的不断增加,焊料的铺展面积逐渐减少。微量P元素的添加可以改善SAC305-0.1Cr焊料的润湿性。

英文摘要：

The effect of Cr on the oxidation resistance of lead free solder Sn-3.0Ag-0.5Cu （ SAC305 ） at 280 ℃ was studied. Based on the analysis of the surface oxidation with scanning electron microscope （SEM） and auger electron spectroscopy （AES） , the mechanism of oxidation resistance improvement was also discussed. The effects of Cr on the mierostmcture and surface wettability of lead-free solder were revealed. The results showed that the oxidation resistance of lead-free solder could be effectively improved by Cr addition. Cr element in the molten solder surface was easy to generate Cr203, resulting in that Sn oxiding preceded to form a dense protective ox- ide film, thus protecting the further oxidation of the solder. When Cr content was 0.1% （ mass fraction） , the liquid solder formed a smooth and compact oxide layer on the surface. The oxidation resistance of liquid SAC305-0. ICr was correspondingly improved. In addition, the surface wettability reduced after the Cr addition, and as the Cr content increased, the solder spreading area gradually reduced. It was also shown that the addition of P could improve the surface wettability of SAC305-0.1Cr.