SnBi基焊点在热作用下的可靠性和失效分析  

Reliability and Failure Analysis of SnBi-Based Solder Joints Under Thermal Effect

作　　者：徐衡 陈旭 罗登俊 颜炎洪 李守委 徐罕 Xu Heng;Chen Xu;Luo Dengjun;Yan Yanhong;Li Shouwei;Xu Han(The 58^(th) Research Institute,China Electronics Technology Group Corporation,Wuxi 214072.China;Suzhou Eunoiv Company Limited,Suzhou 215152,China;Wuxi Zhong Wei High-Tech Electronics Co.,Ltd.,Wuxi 214072,China)

机构地区：[1]中国电子科技集团公司第五十八研究所,江苏无锡214072 [2]苏州优诺电子材料科技有限公司,江苏苏州215152 [3]无锡中微高科电子有限公司,江苏无锡214072

出　　处：《微纳电子技术》2021年第4期365-370,共6页Micronanoelectronic Technology

摘　　要：基于电子封装技术不断趋于3D结构发展,SnBi基焊料合金以其低熔点、低成本和良好的润湿性被用作新一代封装焊料材料,但器件工作过程中的热和电循环作用会影响其互连焊点的可靠性。用SnBi57AgCuCo和SnBi45AgCuNi焊料合金将球栅阵列焊球和印刷电路板回流形成SnBi基焊点,通过微观组织表征与失效模式分析研究等温时效和温度循环对SnBi基焊点可靠性的影响。结果表明,在100℃时效500 h后,SnBi基焊点微观组织中的Bi元素向焊点两端发生明显的聚集生长,形成粗大的块状Bi相组织,且金属间化合物(IMC)的厚度明显增加。Cu3Sn和Cu6Sn5共同组成焊点的IMC层,其厚度增加主要是由于Cu3Sn的形成。经过温度循环后在焊点微观组织中也发现Bi元素的扩散生长和IMC厚度的增加,但在1000次循环后IMC厚度不再明显增加。对互连焊点断裂失效模式分析发现,Bi元素扩散和IMC厚度增加的初期释放了焊点应力,焊点强度增加。随着温度循环的继续,形成的脆性Bi相和较厚的IMC降低了焊点强度。As electronic packaging technology continuously tends to the development of 3 D structure,the SnBi-based solder alloys are used as a new generation of packaging materials for the low melting point,low cost and good wettability.But the reliability of interconnect solder joints is affected by the thermal and electrical cycle during the device operation.SnBi57 AgCuCo and SnBi45 AgCuNi solder alloys were used to reflow ball grid array solder balls and printed circuit boards to form SnBi-based solder joints.The effects of isothermal aging and temperature cycling on the reliability of SnBi-based solder joints were studied by microstructure characterization and failure mode analysis.The results show that the Bi element in the SnBi-based solder joints microstructure obviously aggregates and grows to both sides of the solder joints after aging at100℃for 500 h,leading to the formation of bulk Bi phase structure and significant increase of the thickness of intermetallic compound(IMC).Besides,the IMC layer of the solder joints is composed of Cu3 Sn and Cu6 Sn5,and the increase of the thickness is mainly due to the formation of Cu3 Sn.The diffusion growth of Bi element and the increase of the IMC thickness are found in the microstructure of solder joints after temperature cycle,but the thickness increase of the IMC is no longer significant after 1000 cycles.By analyzing the fracture failure mode of the interconnect solder joints,it is found that the stresses of the solder joints are released at the preliminary stage of the Bi element diffusion and IMC thickness increase,and the strengths of the solder joints increase.However,as the temperature cycle continues,the formed brittle Bi phase and thicker IMC reduce the strengths of the solder joints.

关 键 词：焊料合金 温度循环 等温时效 微观组织 金属间化合物(IMC) 

分 类 号：TG425.1[金属学及工艺—焊接] TN306[电子电信—物理电子学]