Constitutive Modeling of Creep in Leaded and Lead-Free Solder Alloys Using Constant Strain Rate Tensile Testing

Environmental and safety concerns have necessitated a phase-out of lead-based alloys, which are often used in electronics solder applications. In order to properly assess suitable replacement materials, it is necessary to understand the deformation mechanisms relevant to the application. In the case of electronics solder, creep is an important mechanism that must be considered in the design of reliable devices and systems. In this study, Power-Law and Garofalo constitutive creep models were derived for two medium temperature solder alloys. The first alloy is known by the commercial name Indalloy 236 and is a quaternary alloy of lead, antimony, tin, and silver. The lead-free alternative is a binary alloy of tin and antimony known by the trade name Indalloy 264. Constant strain rate tests were conducted at temperatures from -20 to 175 Celsius using constant strain rate tensile testing in the range of e-5 s-1 to e-1 s-1. Creep constants were defined for use in materials selection and design analysis activities.