Numerical Implementation of a Unified Viscoplastic Model for Considering Solder Joint Response under Board-Level Temperature Cycling

Abstract

An implicit integration scheme was developed for simulating the viscoplastic constitutive behavior of Sn3.0Ag0.5Cu solder and programmed into a user material subroutine of the finite element software ANSYS. The numerical procedure first solves the essential state variables by using a three-level iterative procedure, and updates the remaining stress and state variables accordingly. The numerical implementation was applied to consider the responses of solder joints in an electronic assembly under temperature cycling condition. The viscoplastic strain energy density accumulation over one temperature cycle was identified as a feasible parameter for evaluating the thermomechanical reliability of the solder joints.

Analytical Models of Concrete Fatigue: A State-of-the-Art Review

“…This concept means that the internal fatigue damage variables of concrete only increase in the rising stage of every load cycle. Interestingly, there are similar models in the study of the fatigue response of other materials [101]. Here, the damage consistency parameter was directly expressed as:…”

Reliability Evaluation of Board-Level Flip-Chip Package under Coupled Mechanical Compression and Thermal Cycling Test Conditions

“…Thermal cycle on board (TCoB) tests have emerged as an important tool for evaluating the solder joint reliability in order to improve the packaging yield rate and physical integrity of the final assembly. Several studies have employed FE models to examine the TCoB reliability of solder interconnects [18][19][20]. Shao et al [21] used a three-dimensional (3D) digital image correlation (DIC) technique to measure the warpage of a 55 × 55 mm 2 2.5D lidded package, and then constructed a verified FE model based on the DIC measurements to analyze the board-level thermal reliability for various geometry factors and material properties.…”