Effect of Cerium Addition on Board Level Reliability of Sn-Ag-Cu Solder Joint
In order to study the effect of rare earth doping on temperature cycle (TC) and drop reliabilities of the SnAgCu solder joints, cerium (Ce) was added to Sn2.5Ag0.5Cu solder by the amount of 300, 500, 1000 ppm, respectively. Solder joints were formed. TC and drop tests were conducted.Results show that 500 ppm Ce addition has the least influence on TC reliability of the solder joints, while less or more addition of cerium may deteriorates the TC performance. Most cracks in TC tests occurred in solder bulk or between the solder bulk and the interfacial IMC layer. 300 ppm cerium doped solder joint shows best drop reliability among all samples. Cracks mainly occurred between the interfacial IMC layer and board pad. Drop reliabilities were also tested for samples after high temperature aging (125 ℃,300h). It can be inferred that the more Ce was added, the better thermal stability was achieved in drop tests. Among all high temperature treated samples, 1000 ppm Ce added sample exhibits best drop reliability. Cross-section view of the solder joints show that Ce addition refined the microstructure of the solder joint. Ce tends to segregate on grain boundaries, which restraints the growth of β-Sn grains and Ag3Sn IMC and in result improves mechanical properties of the solder. Ce also tends to accumulate at the interface between bulk solder and the Cu6Sn5 IMC layer and reacts with Sn, thus depress the interfacial IMC layer growth.
Le Liang Qian Wang Zhenqing Zhao
Samsung Semiconductor(China) R&D Co., Ltd, Science Plaza 7F, International Science Park, Suzhou Industrial Park Suzhou, Jiangsu, China, 215021
国际会议
第八届电子封装技术国际会议(2007 8th International Conference on Electronics Packaging Technology ICEPT2007)
上海
英文
305-308
2007-08-14（万方平台首次上网日期，不代表论文的发表时间）