Creep Properties of Environmentally Friendly Lead-Free SAC solder in Ball Grid Array Solder Connection Subjected to Cyclic Loading

Abstract

This paper investigates the creep properties of lead-free (Sn3.8Ag0.7Cu) and lead-containing (Sn37Pb) solder alloys. To simulate the working environment of solder joints in a Microelectronic Packaging Module (EPM), creep failure was estimated using isothermal and combined thermal-mechanical fatigue tests on Ball Grid Array (BGA) specimens over the temperature range 25−75∘⁢. A steady-state power law creep relationship was employed to determine creep parameters, including stress exponent and activation energy. The results showed that creep exponent (n) increases with temperature in lead-free Sn3.8Ag0.7Cu and decreases in lead-containing Sn37Pb solders. The activation energy and average creep exponent of lead-free solder were, respectively, ∼7% and ∼105% greater than those of lead-containing solder, indicating that Sn3.8Ag0.7Cu alloy has better creep resistance compared to the Sn37Pb solder. The potential sustainability advantages associated with the improved creep resistance of Sn3.8Ag0.7Cu solder are discussed.