Determination of Anand Parameters From Creep Testing of SAC305 Solder Joints

Abstract

Solder Joints are among the most vulnerable components within electronic packages, and solder joint fatigue is regarded to be one of the major methods of electronic package failure. The prediction of solder joint reliability is thus of great importance and most finite element packages utilize the Anand Viscoplastic Model to model the mechanical behavior of the solder joint material. In this work, 3 × 3 arrays of SAC305 solder joints of roughly 750 μm in diameter were reflowed in between two FR-4 printed circuit boards to create a sandwich structural sample. These samples were then subjected to creep testing in shear at various temperatures (T = 25, 50, 75, 100 °C) and stress levels (τ = 5, 10, and 15 MPa). A set of specially designed fixtures was used to grip the solder joint specimens. The nine Anand model constants were then extracted from the creep data. The Anand model predicted creep response curves were then compared with the experimental creep measurements to determine the accuracy of the model. The Anand model predictions were found to match the measured data very well over a wide range of temperatures and stress levels.