Viscoplastic Anand model for solder alloys and its application

Abstract

A viscoplastic constitutive model, the Anand model, in which plasticity and creep are unified and described by the same set of flow and evolutionary relations, was applied to represent the inelastic deformation behavior for solder alloys. After conducting creep tests and constant strain rate tests, the material parameters for the Anand model of the Pb‐rich content solder 92.5Pb5Sn2.5Ag were determined from the experimental data using a nonlinear fitting method. The material parameters for 60Sn40Pb, 62Sn36Pb2Ag and 96.5Sn3.5Ag solders were fitted from the conventional model in the literature where plasticity and creep are artificially separated. Model simulations and verifications reveal that there is good agreement between the model predictions and experimental data. Some discussion on this unified model is also presented. This viscoplastic constitutive model for solder alloys possesses some advantages over the separated model. The achieved Anand model has been applied in finite element simulation of stress/strain responses in solder joints for chip component, thin quad flat pack and flip‐chip assembly. The simulation results are in good agreement with the results in the literature. It is concluded that the Anand model could be recommended as a useful material model for solder alloys and can be used in the finite element simulation of solder joint reliability in electronic packaging and surface mount technology.

In Situ Optical Creep Observation of Joint-Scale Tin–Silver–Copper Solder Shear Samples

“…On the other hand it is much cheaper and faster to have a general test procedure that allows for testing of all materials under conditions which are close to application. However, most FEA simulations are based on properties measured using bulk tensile solder specimens, [6][7][8][9] and these may not represent the properties of a solder joint in an application due to scaling and microstructural effects. 10,11 A good testing procedure has to be comparable to electronic components in terms of stress state and level, scale, and temperature.…”

Effect of viscoelasticity of ethylene vinyl acetate encapsulants on photovoltaic module solder joint degradation due to thermomechanical fatigue

“…Where s 0 is the initial deformation resistance value. These material parameters for 60Sn40Pb solder alloy are well-defined in the literature 33) and are given in Table I. The mini-modules fabricated at Loughborough consist of a single cell soldered using a 60Sn40Pb solder alloy and copper-based interconnecting ribbons.…”

Chip-on-board assembly of 800V Si L-IGBTs for high performance ultra-compact LED drivers

“…The solder viscoplastic properties were extracted from Cheng et al [8]. The standard temperature cycling with ramp and dwell time of 3 and 15 minutes with range of (-25, 125) was imposed on the model.…”