Coffin-Manson constant determination for
a Sn-8Zn-3Bi lead-free solder joint
Peng Sun
Key State Lab for New Displays and System Integration (Chinese Ministry of Education), SMIT Center, Shanghai University,
Shanghai, People’s Republic of China
Department of Microtechnology and Nanoscience, SMIT Center, Chalmers University of Technology, Go
¨
teborg, Sweden
Cristina Andersson
Department of Microtechnology and Nanoscience, SMIT Center, Chalmers University of Technology, Go
¨
teborg, Sweden
Xicheng Wei
Key State Lab for New Displays and System Integration (Chinese Ministry of Education), SMIT Center, Shanghai University,
Shanghai, People’s Republic of China
Zhaonian Cheng
Department of Microtechnology and Nanoscience, SMIT Center, Chalmers University of Technology, Go
¨
teborg, Sweden
Dongkai Shangguan
Flextronics International, San Jose, California, USA, and
Johan Liu
Key State Lab for New Displays and System Integration (Chinese Ministry of Education), SMIT Center, Shanghai University,
Shanghai, People’s Republic of China
Department of Microtechnology and Nanoscience, SMIT Center, Chalmers University of Technology, Go
¨
teborg, Sweden
Abstract
Purpose – To determine the Coffin-Manson (CM) equation constants for fatigue life estimation of Sn-8Zn-3Bi solder joints, since Sn-8Zn-3Bi solder has
a melting temperature of around 1998C which is close to that of the conventional Sn-Pb solder which has previously been used in the electronics
assembly industry.
Design/methodology/approach – Three dimensional finite element (FE) simulation analysis was used for comparison with the experimentally
measured data and to determine the CM constants. Low cycle fatigue tests and FE simulations were carried out for these lead-free solder joints, and
eutectic Sn-37Pb solder was used as a reference.
Findings – The CM equation for Sn-8Zn-3Bi solder joints was fitted to the lifetimes measured and the shear strains simulated. The constants were
determined to be 0.0294 for
C
, the proportional constant, and for the fatigue exponent,
b
, 2 2.833.
Originality/value – The CM equation can now be used to predict the reliability of Sn-8Zn-3Bi solder joints in electronics assembly and the knowledge
base for the properties of the Sn-Zn solder system has been increased.
Keywords Finite element analysis, Fatigue, Joining materials, Simulation, Solders
Paper type Research paper
1. Introduction
The eutectic tin lead alloy has been widely used in surface
mount technology for the interconnection and mechanical
attachment between electronic components and printed
circuit boards (PCB). In real service conditions, thermal
stresses arise as a result of a coefficient of thermal expansion
mismatch between components and PCBs. Since, the solder
is the softer material in the package, most of the cyclic strains
are concentrated in the solder joint, resulting sooner or later
in failure of surface mounted components.
Environmentally conscious manufacturing is becoming a
very important objective for the electronics industry. It is
highly desirable to minimize the environmental impact of
electronic manufacturing processes. The electronics industry
is being forced to eliminate lead from products, due to the
The current issue and full text archive of this journal is available at
www.emeraldinsight.com/0954-0911.htm
Soldering & Surface Mount Technology
18/2 (2006) 4 –11
q Emerald Group Publishing Limited [ISSN 0954-0911]
[DOI 10.1108/09540910610665071]
The authors gratefully acknowledge the financial support provided by the
SMIT Center member companies including: Flextronics; Heller
Industries,USA;Toyo-Kohan,Sumitomo Chemicals and Hitachi
Chemicals, Japan; Nera and Conpart, Norway; and Mydata
Automation, Note, and Foab Elektronik, Sweden. The authors also
gratefully acknowledge the financial support provided by the research
program “EU project of Flex-Eman” with the contract no: COOP-CT-
2003-507983 and appreciation is extended also to the Shanghai Science
and Technology Commission, PRC for financial support under contract
number 045107006 and 035007031.
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