低银无铅焊料SAC105性能研究-材料加工工程专业论文.docx

华 华 中 科 技 大 学 硕 士 学 位 论 文 万方数据 万方数据 Abstract Due to the environment and health problems causing by the use of lead, lead-free electronic packaging has come into the manufacturing for modern electronic products. The key problem of lead-free electronic packaging is the lead-free soldering process. And the lead-free solder materials play a crucial role in the lead-free soldering process. SAC lead-free solder is recognized as the alternative to take place of the traditional tin-lead eutectic solder. And the SAC305 solder is recommended as the best choice. But due to the high content of Ag, the cost increases nearly 3 times compared to tin-lead eutectic solder. To reduce the cost of solder, low-silver lead-free solder comes into people’s vision. SAC105 is a kind of low-silver lead-free solder with a composition of 98.5% Sn, 1.0% Ag, and 0.5% Cu. This paper focuses on the performance of SAC105 solder through the designed experiments and tests. Studies have shown that : the microstructure and inter metallic compounds of SAC105 are similar to SAC305; the reduce of Ag content increases the solder’s melting points, and the melting temperature range of SAC105 is 215-231°C nearly 5°C higher than SAC305; SAC105 alloys possess lower tensile strength and higher elongation ratio than SAC305, but in the solder joint shear strength tests , SAC105 and SAC305 show almost the same shear strength; the wetting angle of SAC105/Cu is 31° and is about to achieve the excellent evaluation of wetting criteria(below 30°) ; in the high temperature storage experiments, the SAC105/Cu IMC grows a little bit faster than SAC305 and shows similar changes in morphology to SAC305, after 2000 hours storage the SAC105 joint shear strength decreases about 13% and is close to SAC305. As can be seen, the low-silver lead-free solder SAC105 shows similar performance to the recommended lead-free solder SAC305, while providing much lower cost. Proper use of low-silver lead-free solder can reduce the cost signifi