A viscoplastic-fatigue-creep damage model for tin-based solder alloy

Abstract

During the past decade the demand for high performance automotive electronics is steadily increasing. An efficient development of such products requires the use of durability assessment techniques throughout the whole design optimization process. Since typical components comprise a large number of different materials and complex geometrical structures, Finite Element (FE) analysis is preferably used for durability evaluation and continuously replaces analytical calculations. However, a direct lifetime calculation by means of FE-techniques is still not achieved, partly due to the lack of material models capable of mapping the intrinsic material degradation under the relevant thermo-mechanical loads. Here, we propose a material model for a tin-based solder alloy which describes the non-linear mechanical behavior at the beginning of deformation as well as during continuous cyclic aging. We investigated the evolution of the mechanical properties and microstructure of the solder alloy Sn96:5Ag3:5 by cyclic strain-rate controlled fatigue- and creep-tests on as-casted standardized specimens. Material modeling is focused on the description of the complex interplay between viscoplastic, fatigue and creep processes observed in the experiment. Finally, a very good agreement is obtained between the measurements and the numerical model, which can offer new opportunities for lifetime simulations of lead-free solder joints

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

“…An obvious choice of modeling the time-dependent inelastic behavior of solder is by using the state-variable based unified viscoplasticity approach [1,2]. For considering the complex thermomechanical responses of lead free solders, some of the recent studies modified the Chaboche-model framework to incorporate features such as static recovery, temperature dependence and damage evolution [3][4][5][6]. Rate-or temperature-dependent model parameters were also implemented in the McDowell-model and Anand-model frameworks [7][8][9] to consider the solder behavior under a wide range of strain rates and temperatures.…”

Experimental and numerical investigation of fatigue damage development under multiaxial loads in a lead-free Sn-based solder alloy

“…For this, extended material characterization are necessary including cyclic fatigue tests, creep tests and combined fatigue-relaxation tests. The observed damage behavior can be simulated using a continuum damage mechanic approach as reported in [6]. Besides, most of the material characterization focused on lead free solder is conducted under uniaxial loads.…”

Effects of Creep Failure Mechanisms on Thermomechanical Reliability of Solder Joints in Power Semiconductors

“…This approach expresses that the material degradation through energy dissipative mechanisms plays a key role in crack initiation and propagation and the cracks follow paths similar to cracks produced under quasi-static cycling. Metais et al [16] proposed a viscoplastic-fatigue-creep damage model based on a non-linear mechanical behavior of solder at the beginning of deformation as well as during continuous cyclic aging. Material modeling concentrated on the interpretation of the complicated interaction between fatigue and creep and viscoplastic processes.…”