Numerical Simulation for the Thermal Fatigue of Flip Chip Solder Joints

2010 ◽  
Vol 97-101 ◽  
pp. 3963-3966
Author(s):  
Yong Cheng Lin ◽  
Jing Hong Lu ◽  
Jun Zhang

Fatigue failure of solder joints is a serious reliability concern in area array technologies. A non-linear finite element model was made to study the effects of underfill material and substrate flexibility on solder joint thermal fatigue. Accelerated temperature cycling loading was imposed to evaluate the reliability of solder joints in test flip chip assembly. The results show that the underfill material and substrate flexibility can improve the distribution of stress/strain and reduce the magnitude of stress/strain in the solder joints. Therefore, the reliability of solder joints under thermal cycling condition can be enhanced by applying underfill material and selecting the Flex substrates during temperature cycling.

2007 ◽  
Vol 353-358 ◽  
pp. 2932-2935
Author(s):  
Yong Cheng Lin ◽  
Xu Chen ◽  
Xing Shen Liu ◽  
Guo Quan Lu

The reliability of solder joints in flip chip assemblies with both compliant (flex) and rigid (PCB) substrates was studied by accelerated temperature cycling tests and finite element modeling (FEM). In-process electrical resistance measurements and nondestructive evaluations were conducted to monitor solder joint failure behavior, hence the fatigue failure life. Meanwhile, the predicted fatigue failure life of solder joints was obtained by Darveaux’s crack initiation and growth models. It can be concluded that the solder joints in flip chip on flex assembly (FCOF) have longer fatigue life than those in flip chip on rigid board assembly (FCOB); the maximum von Mises stress/strain and the maximum shear stress/strain of FCOB solder joints are much higher than those of FCOF solder joints; the thermal strain and stress in solder joints is reduced by flex buckling or bending and flex substrate could dissipate energy that otherwise would be absorbed by solder joint. Therefore, the substrate flexibility has a great effect on solder joint reliability and the reliability improvement was attributed to flex buckling or bending during temperature cycling.


2011 ◽  
Vol 264-265 ◽  
pp. 1660-1665
Author(s):  
Yong Cheng Lin ◽  
Yu Chi Xia

More and more solder joints in circuit boards and electronic products are changing to lead free solder, placing an emphasis on lead free solder joint reliability. Solder joint fatigue failure is a serious reliability concern in area array technologies. In this study, the effects of substrate materials on the solder joint thermal fatigue life were investigated by finite element model. Accelerated temperature cycling loading was imposed to evaluate the reliability of solder joints. The thermal strain/stress in solder joints of flip chip assemblies with different substrates was compared, and the fatigue life of solder joints were evaluated by Darveaux’s crack initiation and growth model. The results show the mechanisms of substrate flexibility on improving solder joint thermal fatigue.


2005 ◽  
Vol 127 (4) ◽  
pp. 466-473 ◽  
Author(s):  
B. L. Chen ◽  
X. Q. Shi ◽  
G. Y. Li ◽  
K. H. Ang ◽  
Jason P. Pickering

In this study, a thermoelectric cooler-based rapid temperature cycling (RTC) testing method was established and applied to assess the long term reliability of solder joints in tape ball grid array (TBGA) assembly. This RTC testing methodology can significantly reduce the time required to determine the reliability of electronic packaging components. A three-parameter Weibull analysis characterized with a parameter of failure free time was used for assembly reliability assessment. It was found that the RTC not only speedily assesses the long-term reliability of solder joints within days, but also has the similar failure location and failure mode observed in accelerated temperature cycling (ATC) test. Based on the RTC and ATC reliability experiments and the modified Coffin-Manson equation, the solder joint fatigue predictive life can be obtained. The simulation results were found to be in good agreement with the test results from the RTC. As a result, a new reliability assessment methodology was established as an alternative to ATC for the evaluation of long-term reliability of electronic packages.


Author(s):  
Qiang Yu ◽  
Masaki Shiratori ◽  
Kimimasa Murayama ◽  
Kazuhiro Igarashi ◽  
Takashi Nakanishi

In recent years many electric equipments have come to be used for cars. Solder joints in electric device utilizing car are exposed to harder environment and required higher reliability than that in electric household appliances. Because of this reason, thermal fatigue reliability of solder joints has become one of the most important issues in car electronics. Generally thermal fatigue reliability is estimated by thermal cycle examination, but it needs long time. Estimation by FEM enables it to improve reliability and to reduce time. Analysis of solder life generally can predict only initial crack. But it is important to predict crack propagation and solder joints break down, considering that a function of solder joints is electric connection. In this study, the authors proposed a method to predict break down life by analytical approach.


2006 ◽  
Vol 5-6 ◽  
pp. 359-366 ◽  
Author(s):  
J. Gong ◽  
C. Liu ◽  
P.P. Conway ◽  
Vadim V. Silberschmidt

SnAgCu solder is a promising lead-free material for interconnections in electronic packages. However, its melting temperature (490°K) is considerably higher than that of the traditional SnPb solder (456°K). At the same time, SnAgCu has much better creep resistance at high temperature. These properties may cause large residual stresses during manufacturing processes due to the mismatch of thermal properties of electronic components that can influence the reliability of solder joints in electronic packages. This paper studies the residual stresses in solder joints in a flip chip package under different cooling conditions and their influence on the subsequent cyclic test by means of a finite element approach. The results show that the initial temperature of 453°K is high enough to induce residual stresses due to manufacturing procedures. Simulations, based on traditional creep-fatigue models, demonstrate that the residual stresses affect the mechanical behaviour of solder joints in several initial thermal cycles but have little effect on their reliability.


Author(s):  
Xing QIU ◽  
Jeffery Lo ◽  
Yuanjie CHENG ◽  
Shi-Wei Ricky Lee ◽  
Yong Jhe TSENG ◽  
...  

Abstract Cu pillar micro-bumps with polymer cores have been demonstrated to effectively reduce thermomechanical stress and improve joint reliability. Fabricating polymer cores by a printing approach was proposed to overcome the limitations in conventional fabrication process. Cylindrical polymer cores with diameter of 20 µm and height of 30 µm were successfully printed. Surface metallization was subsequently applied on the printed polymer cores and Cu pillar micro-bumps with printed polymer cores with diameter of 35 µm and height of 35 µm were eventually achieved. To study the reliability performance of the interconnect joints made of Cu pillar micro-bumps with printed polymer cores, flip-chip bonding technology was successfully introduced and the interconnect joints between a designed BT substrate and a silicon chip were formed. The interconnect joints made of conventional Cu pillars with identical dimensions were prepared for comparison. The reliability performance of the joints was investigated under temperature cycling condition and drop condition, respectively. Printed polymer cores increased the characteristic life by 32% in a temperature cycling test (0°C-100°C), while the drop test showed that printed polymer cores increased the characteristic life by 4 times due to the extra compliance provided by the printed polymer cores. It can be concluded that Cu pillar micro-bumps with printed polymer cores can effectively reduce stress and improve joint reliability.


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