Solder joint failures under thermo-mechanical loading conditions – A review

Abstract

Solder joints play a critical role in electronic devices by providing electrical, mechanical and thermal interconnections. These miniature joints are also the weakest links in an electronic device. Under severe thermal and mechanical loadings, solder joints could fail in 'tensile fracture' due to stress overloading, 'fatigue failure' because of the application of cyclical stress and 'creep failure' due to a permanent long-term load. This paper reviews the literature on solder joint failures under thermo-mechanical loading conditions, with a particular emphasis on fatigue and creep failures. Literature reviews mainly focused on commonly used lead-free Sn-Ag-Cu (SAC) solders. Based on literature in experimental and simulation studies on solder joints, it was found that fatigue failures are widely induced by accelerated thermal cycling (ATC). During ATC, the mismatch in coefficients of thermal expansion (CTE) between different elements of electronics assembly contributes significantly to induce thermal stresses on solder joints. The fatigue life of solder joints is predicted based on phenomenological fatigue models that utilise materials properties as inputs. A comparative study of 14 different fatigue life prediction models is presented with their relative advantages, scope and limitations. Creep failures in solder joints, on the other hand, are commonly induced through isothermal ageing. A critical review of various creep models is presented. Many of these strain ratebased creep models are routed to very well-known Anand Model of inelastic strain rate. Finally, the paper outlined the combined effect of creep and fatigue on solder joint failure.

Survey on Fatigue Life Prediction of BGA Solder Joints

“…Early creep modeling was carried out by separating the elastic and plastic deformation mechanisms. The creep, plastic, elastic, and other deformations were overlapped to form the creep [61,101], which is the main deformation failure mechanism of materials at high temperature. In particular, in microelectronic packaging, for example, for Sn-based lead-free solders, creep will occur when the operating temperature for the solder joint is 0.5 times more than the melting point of the solder [102].…”

Advanced Reliability Analysis of Mechatronic Packagings coupling ANSYS©and R

“…In operating conditions, Mechatronic packages are subject to large temperature variations [10]. The coefficient of Thermal Expansion (CTE) mismatch between the various materials used in the package construction leads to thermomechanical stresses in solder joints, which can cause the damage in solder joints and consequently the failure of the entire package [11].…”

The Effects of Temperature and Solute Diffusion on Volume Change in Sn-Bi Solder Alloys

“…3,4,7,8 It has been shown that the density of the eutectic Sn-Bi alloy decreases with increasing temperature, and the thermal expansion characteristics of this alloy have been characterized. 9 While the thermal expansion characteristics of solder alloys are recognized as one of the factors that affect the reliability of electronic assemblies in service, 10 the coefficients of thermal expansion (CTE) of eutectic Sn-Bi used in modeling is typically a single value (e.g., 15 9 10 À6 /°C). 8 In service, the solder joints of electronic circuitry are exposed to temperature changes from the environment in which they operate or because of the heat generated by the functioning of the circuitry.…”