摘要
研究热冲击条件下细间距倒装微焊点的裂纹萌生及扩展,通过观察裂纹生长路径,并结合累积塑性应变能密度及应变在焊点上的分布,分析裂纹的生长机理.结果表明,裂纹形成在微焊点外侧,位于镍焊盘界面IMC与焊料基体之间的界面上;随着循环次数的增加,裂纹进入镍焊盘附近的焊料基体中,沿着焊盘平行的方向扩展,累积塑性应变能密度及应变在微焊点上的分布与裂纹扩展方向一致.对裂纹生长机理探讨可知,IMC与微焊点之间的界面处于双重应力集中状态,因此裂纹易在微焊点及IMC之间的界面上萌生;随着循环次数的增加,焊料基体的塑性变形增加,高塑性的焊料区域为裂纹扩展提供了条件.
In this parper,initiation and propagation of the crack in flip chip solder joints under thermal shock,were studid and growth mechanism is analyzed by crack growth path and distribution of accumulated plastic work density and plastic strain at solder joints. Based on this study,it is seen that the crack formed outside solder joint,located in the interface between interfacial IMC and solder matrix,as cycles increasing,the crack propagated into solder matrix,and grew along the pad,the distribution of accumulated plastic work and density is consistent with crack growth direction. The discussion from crack growth mechanism shows that the interface locate in double-stress-concentration,and the plastic work is bigger,therefore the crack is inclined to form in the interface between the IMC and solder joint,as cycles increasing,the plastic strain of solder matrix is increased,which causes the region of higher solder matrix providing condition for crack propagation.
出处
《焊接学报》
EI
CAS
CSCD
北大核心
2016年第9期43-45,50,共4页
Transactions of The China Welding Institution
基金
国家自然科学基金资助项目(U1504507)
河南省科技攻关资助项目(162102410018)
河南工业大学高层次人才基金资助项目(2013BS052)
关键词
倒装芯片
微焊点
热冲击
可靠性
裂纹
flip chip assembly
micro-solder joint
crack growth
reliability
