Assessment of Relative Thermal Fatigue Life of SAC Lead-Free and Tin-Lead Solders With Custom-Made BGA Assemblies Creating Various Stress Ranges

Author(s):  
Y. S. Chan ◽  
C. Yang ◽  
S. W. Ricky Lee

The present study evaluates the relative thermal fatigue life of tin-silver-copper (SnAgCu or SAC) lead-free and tin-lead (SnPb) solders with custom-made BGA assembly configurations generating various stress ranges under thermal cyclic loading. Although the SAC solder bears a lower creep strain rate compared with the SnPb solder in common thermal cycling conditions, it is found that there exits conditions at which the SnPb solder joint maintain a longer life than the SAC solder joint. The determination lies on the maximum normalized equivalent stress levels (σ/E) experienced by the two kinds of solder joint during the temperature cycles. Even under the same straining and thermal cycling condition, it is observed that the maximum σ/E induced in the two kinds of solder joint are normally different, as a result of their different rate of stress relaxation. The analysis shows that both the absolute and relative magnitude of σ/E experienced by the two kinds of solder joint affect the relative life. In general, the SAC solder joint sustain a longer life at low σ/E levels, while the SnPb solder joint outperform the SAC solder joint at high σ/E levels. There exists a critical σ/E level at which both solder joints acquire similar performance. However, this margin shifts with the relative magnitude of σ/E the two kinds of solder joint suffered. Having studied the variation of σ/E for the two kinds of solder joint under various loading conditions, this study uncovers the rationale for the difference in the relative thermal fatigue life of the two kinds of solder joint.

2008 ◽  
Vol 72 (3) ◽  
pp. 244-248 ◽  
Author(s):  
Tomotake Tohei ◽  
Ikuo Shohji ◽  
Keisuke Yoshizawa ◽  
Masaharu Nishimoto ◽  
Takayuki Kawano ◽  
...  

2008 ◽  
Vol 385-387 ◽  
pp. 433-436 ◽  
Author(s):  
Ikuo Shohji ◽  
Tomotake Tohei ◽  
Keisuke Yoshizawa ◽  
Masaharu Nishimoto ◽  
Yasushi Ogawa ◽  
...  

Accelerated thermal cycling (ATC) tests were conducted to investigate an effect of thermal cycle conditions on thermal fatigue life of a chip size package (CSP) lead-free solder joint. A ternary Sn-Ag-Cu alloy was used as a lead-free solder material. For frequency of thermal cycle (1~3 cycles/h) and maximum (388~423 K) and minimum (223~273 K) temperatures investigated, the effects of them on thermal fatigue life of the solder joint were slight. On the contrary, correlation was recognized between temperature amplitude and thermal fatigue life of the solder joint. The thermal fatigue life increased with decreasing temperature amplitude. The relationship obeyed the Coffin-Manson’s type equation.


2001 ◽  
Vol 42 (5) ◽  
pp. 809-813 ◽  
Author(s):  
Young-Eui Shin ◽  
Kyung-Woo Lee ◽  
Kyong-Ho Chang ◽  
Seung-Boo Jung ◽  
Jae Pil Jung

Author(s):  
Tomohiro Takahashi ◽  
Qiang Yu ◽  
Masahiro Kobayashi

For power module, the reliability evaluation of thermal fatigue life by power cycling has been prioritized as an important concern. Since in power cycling produces there exists non-uniform temperature distribution in the power module, coupled thermal-structure analysis is required to evaluate thermal fatigue mechanism. The thermal expansion difference between a Si chip and a substrate causes thermal fatigue. In this study, thermal fatigue life of solder joints on power module was evaluated. The finite element method (FEM) was used to evaluate temperature distribution induced by joule heating. Higher temperature appears below the Al wire because the electric current flows through the bonding Al wire. Coupled thermal-structure analysis is also required to evaluate the inelastic strain distribution. The damage of each part of solder joint can be calculated from equivalent inelastic strain range and crack propagation was simulated by deleting damaged elements step by step. The initial cracks were caused below the bonding Al wire and propagated concentrically under power cycling. There is the difference from environmental thermal cycling where the crack initiated at the edge of solder layer. In addition, in order to accurately evaluate the thermal fatigue life, the factors affecting the thermal fatigue life of solder joint where verified using coupled electrical-thermal-structural analysis. Then, the relation between the thermal fatigue life of solder joint and each factor is clarified. The precision evaluation for the thermal fatigue life of power module is improved.


2002 ◽  
Vol 2002.6 (0) ◽  
pp. 283-284
Author(s):  
Hiroyuki TAKAHASHI ◽  
Takashi KAWAKAMI ◽  
Minoru MUKAI ◽  
Mineo KOBAYASHI ◽  
Nobutada OHNO ◽  
...  

2015 ◽  
Vol 27 (2) ◽  
pp. 76-83 ◽  
Author(s):  
Jibing Chen ◽  
Yanfang Yin ◽  
Jianping Ye ◽  
Yiping Wu

Purpose – The purpose of this paper is to investigate the thermal fatigue behavior of a single Sn-3.0Ag-0.5Cu (SAC) lead-free and 63Sn-37Pb (SnPb) solder joint treated by rapidly alternating heating and cooling cycles. Design/methodology/approach – With the application of electromagnetic-induced heating, the specimen was heated and cooled, controlled with a system that uses a fuzzy logic algorithm. The microstructure and morphology of the interface between the solder ball and Cu substrate was observed using scanning electron microscopy. The intermetallic compounds and the solder bump surface were analyzed by energy-dispersive X-ray spectroscopy and X-ray diffraction, respectively. Findings – The experimental results showed that rapid thermal cycling had an evident influence on the surface and interfacial microstructure of a single solder joint. The experiment revealed that microcracks originate and propagate on the superficial oxide of the solder bump after rapid thermal cycling. Originality/value – Analysis, based on finite element modeling and metal thermal fatigue mechanism, determined that the rimous cracks can be explained by the heat deformation theory and the function of temperature distribution in materials physics.


2004 ◽  
Vol 7 (4) ◽  
pp. 308-313 ◽  
Author(s):  
Hiroyuki TAKAHASHI ◽  
Takashi KAWAKAMI ◽  
Minoru MUKAI ◽  
Nobutada OHNO

Author(s):  
T. E. Wong ◽  
C. Chu

A simplified method was developed to determine the fatigue life of a ceramic column grid array (CCGA) solder joint when exposed to thermal environments. The CCGA package with 90Pb/10Sn solder columns is soldered onto the printed circuit board with a tin-lead solder paste. Failure of the solder joint occurs at the CCGA solder column. A closed-form solution with the equilibrium of displacements of electronic package assembly was first derived to calculate the solder joint strains during the temperature cycling. In the calculation, an iteration technique was used to obtain a convergent solution in the solder strains, and the elastic material properties were used for all the electronic package assembly components except for the solder materials, which used elastic-plastic properties. A fatigue life prediction model, evolved from an empirically derived formula based upon a modified Coffin-Manson fatigue theory, was then established. CCGA test results, obtained from various sources, combined with the derived solder strains were used to calibrate the proposed life prediction model. In the model calibration process, the 625- and 1657-pin CCGA test results, which were cycled between 20°C/90°C, 0°C/100°C, −55°C/110°C, or −55°C/125°C, were reasonably well correlated to the calculated values of solder strains. In addition, this calibrated model is remarkably simple compared to the model used in an evaluation by a finite element analysis. Therefore, this model could be used and is recommended to serve as an effective tool to make a preliminarily estimate at the CCGA solder joint thermal fatigue life. It is also recommended to 1) select more study cases with various solder joint configurations, package sizes, environmental profiles, etc. to further calibrate this life prediction model, 2) use this model to conduct parametric studies to identify critical factors impacting solder joint fatigue life and then seeking an optimum design, and 3) develop a similar life prediction model for lead-free solder materials.


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