A multi-scale approach to microstructure-sensitive thermal fatigue in solder joints

TL;DR

This study introduces a multi-scale modelling framework to understand how microstructure influences thermal fatigue damage in solder joints, combining macro-scale and micro-scale analyses to optimize solder microstructure design.

Contribution

The paper develops a coupled multi-scale model linking board-level and crystal microstructure-level analyses to predict damage in solder joints under thermal cycling.

Findings

Crystallographic orientation significantly affects fatigue damage.

Model predictions align with experimental observations.

Optimal solder microstructure design can enhance fatigue resistance.

Abstract

This paper presents a multi-scale modelling approach to investigate the underpinning mechanisms of microstructure-sensitive damage of single crystal Sn-3Ag-0.5Cu (wt%, SAC305) solder joints of a Ball Grid Array (BGA) board assembly subject to thermal cycling. The multi-scale scheme couples board-scale modelling at the continuum macro-scale and individual solder modelling at the crystal micro-scale. Systematic studies of tin crystal orientation and its role in fatigue damage have been compared to experimental observations. Crystallographic orientation is examined with respect to damage development, providing evidence-based optimal solder microstructural design for in-service thermomechanical fatigue.