University of Wolverhampton, United Kingdom
pp. 282 - 285
Keywords: creep constitutive models, Garofalo creep constants, solder joint reliability, flip chip assembly, lead-free solder alloy, intermetallic compound, finite element modelling, fatigue damage, accelerated thermal cycling
This investigation employs four hyperbolic sine creep constitutive models to simulate the deformation in Sn[3.0-4.0%]Ag[0.5-1.0%]Cu solder joints of two surface mount components assembled on printed circuit board. These creep models are proposed by Schubert et al, 2003; Lau, 2003; Pang and Zang et al, 2003. The components are flip chip model FC48 D6.3C457DC and resistor model R102. The joints in the flip chip contain intermetallic compounds and the assemblies were subjected to accelerated high-temperature cycles utilising IEC Standard 60749-25 in parts. The study determines and compares the magnitude of accumulated creep strain and strain energy density generated from the different models and evaluates the effect of using the different creep constitutive relations to quantify damage and fatigue life of solder joints in surface mount component (SMC) assembly. The results show significant difference in the magnitude of the damage index generated from the various models. The findings demonstrate that the value of creep constants determines the magnitude of damage index generated from simulation. The predicted values of mean-time-to-failure of SnAgCu solder joints in SMC assembly using Garofalo model depends significantly on both the value of the constants used for the constitutive relation and which of the damage index is employed.