电子电路中焊点的热疲劳裂纹扩展规律  

Thermal Fatigue Crack Growth of Solder Joint in Electronic Circuit

作　　者：林健[1] 雷永平[1] 赵海燕[2] 鲁立[2] 

机构地区：[1]北京工业大学材料学院,北京100124 [2]清华大学机械工程系,北京100084

出　　处：《机械工程学报》2010年第6期120-125,共6页Journal of Mechanical Engineering

基　　金：北京市属市管高等学校人才强教计划;北京工业大学青年科研基金资助项目

摘　　要：采用试验方法研究表面贴装结构焊点在热疲劳过程中的疲劳裂纹扩展规律。试验研究中选用两种不同尺寸的焊盘及两种不同的钎料(包括传统的锡铅钎料和锡银铜无铅钎料SAC305),通过观测焊点截面上的裂纹萌生及扩展过程来研究焊点中的热疲劳裂纹扩展规律。研究结果表明,在热疲劳过程中,焊点经历热疲劳裂纹萌生和扩展的两个不同阶段,其中裂纹萌生所占的时间比例较小。在热疲劳后期,裂纹贯穿整个焊点从而造成焊点结构失效。研究发现,焊点结构失效过程中存在着两种不同的裂纹扩展模式,并且锡铅钎料焊点和SAC305无铅钎料焊点的裂纹扩展规律表现出明显的差异。另外研究还发现,当焊盘尺寸较小时,焊点的抗热疲劳性能相对较差;SAC305无铅钎料焊点的抗热疲劳性能优于传统锡铅钎料焊点。The crack growth in solder joint of SMT during thermal fatigue process is investigated by experimental method. Two kinds of land shapes and two kinds of solders, including lead-tin eutectic solder and lead-free solder （SAC305）, are selected. In order to investigate the crack growth in solder joint, the solder joint is sliced and the crack on the cross section of solder joint is observed. Some conclusions are drawn： During thermal fatigue process the solder joint experiences two stages of crack growth, including crack initiation and crack propagation, in which the period of crack initiation is shorter. In the late period of thermal fatigue, crack goes through the solder joint, to fail. And there are two kinds of crack growth modes observed in the experiment. The crack growth mode of lead-free solder joint is obviously different from that of lead-tin solder joint. Experimental results also show that the solder joint with small land shape has a relatively poor thermal fatigue resistance and the lead-free solder joint of SAC305 has a thermal fatigue resistance better than that of lead-tin solder joint.

关 键 词：表面贴装结构 焊点 热疲劳 裂纹 

分 类 号：TG40[金属学及工艺—焊接]