Intermetallic size and morphology effects on creep rate of Sn-3Ag-0.5Cu solder

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

“…and their interactions (Xu et al, 2021a). The rate-dependent anisotropic material properties of β-Sn at room temperature are obtained from micro-pillar compression tests, while the properties of the intermetallics are based on the literature (Lucas et al, 2003).…”

“…The combined effect of the solder joint location in the grid array for BGA components and the solder microstructure (and notably the combined effects of crystal orientation and the length-scale of intermetallics (Xu et al, 2021a) on the resulting thermal stresses, slip activation, and in turn the solder damage has received relatively little attention. The identification and understanding of the microstructure features which predominate in the fatigue performance remain to be established in SAC305 solder joints.…”

“…However, fatigue damage originates at the microstructural length scale, initiating with slip activation and dislocation pile-up with the consequent stress concentrations at the intragranular scale (Gustafson et al, 2020;Jiang and Dasgupta, 2021). In relation to research on the damage mechanisms of individual solder joints, several continuum models (Darbandi et al, 2014;Jiang and Dasgupta, 2021;Zamiri et al, 2009) were developed for SAC alloys, but intermetallic size and morphology effects (along with crystallographic anisotropy) were not considered, and recently it has been observed that they strongly affect the creep behaviour of SAC305 alloy (Xu et al, 2021a) using a particle-hardening model (Li et al, 2020). Previous studies (Maleki et al, 2011(Maleki et al, , 2013 did not fully include the crystallographic elasto-plastic anisotropy for the Sn phase, which has been extensively considered as a major driver for damage development within solders (Bai and Chen, 2009;Gong et al, 2007;Zhou et al, 2015) or the scale coupling to BGA board (Mukherjee et al, 2016).…”

A non-local methodology for geometrically necessary dislocations and application to crack tips

“…The GND density histograms for two distinct element types show good overlap for the non-local method, which is important since tetrahedral elements are widely used and necessary in applications for which complex geometries are involved, e.g. a particle matrix composite (PMC) modelling (Chawla et al, 2006;Xu et al, 2021a).…”

Grain-Scale Anisotropic Analysis of Steady-State Creep in Oligocrystalline SAC Solder Joints

“…The effect of morphometrics of submicron intermetallic compounds on mechanical response is investigated by multiscale modeling methods, where three-dimensional representative volume elements (RVEs) were imported directly from tomographic images [14,15]. Xu et al incorporates the multi-scale modeling strategy into CPFE, by modeling the SAC grains as particle matrix composites [16]. Fully representative models of the directionally solidified samples were developed based on the microstructures achieved at different loading rates, and compared with experimental results.…”