摘要
由于焊点区非协调变形导致的热疲劳失效是倒装芯片封装(包括无铅封装)结构的主要失效形式。到目前为止,仍无公认的焊点寿命和可靠性的评价方法。文中分别采用双指数和双曲正弦本构模型描述SnAgCu焊点的变形行为,通过有限元方法计算焊点累积蠕变应变和累积蠕变应变能密度,进而据此预测倒装芯片封装焊点的热疲劳寿命。通过实验验证,评价上述预测方法的可行性。结果表明,倒装芯片的寿命可由芯片角焊点的寿命表征;根据累积蠕变应变能密度预测的焊点热疲劳寿命比根据累积蠕变应变预测的焊点热疲劳寿命更接近实测数据;根据累积蠕变应变预测的热疲劳寿命比根据累积蠕变应变能密度预测的热疲劳寿命长;采用双指数本构模型时,预测的焊点热疲劳寿命也较长。
Thermal fatigue failure, due to the fi＇acture of solder joints which was caused by the mismatch deformation, is frequently encountered in flip chip （FC） assemblies. Unfortunately, there is no widely accepted method to evaluate the reliability of solder joints, especially for lead-free solder joints, in such assemblies up to now. The constitutive models of double power law and the hyperbolic sine law were implemented to simulate the deformation of SnAgCu solder joints in flip chip assemblies. The accumulated creep strain and accumulated creep strain energy density of the solder joints were calculated, via finite element method, and were use to predict the thermal fatigue life of flip chip assemblies. The applicability of the above life prediction methods was evaluated through cross check of the present results with that of the literatures. It was found that the life of the FC assemblies could be estimated by the prediction of the life of the cornet solder joints. The thermal fatigue life, estimated according to accumulated creep strain energy density is closer to the test data than that of the life estimated according to accumulated creep strain. The life predicated according to acctunulated creep strain shown a slightly high value than that predicated according to accumulated creep strain energy density. The double power law eonstitutive equation results in a higher oredicted life.
出处
《机械强度》
EI
CAS
CSCD
北大核心
2006年第6期893-898,共6页
Journal of Mechanical Strength
基金
国家自然科学基金(50475043)
北京市自然科学基金(2052006)
教育部博士点基金(20040005012)的资助。~~
关键词
热疲劳
寿命预测
倒装芯片焊点
无铅化
Themo-fatigue
Life prediction
Flip chip
Solder joint
Lead free
