<p class="MsoNormal" style="text-align: justify; line-height: 150%">The reoccurring cyclic load imposed onto soldered electronic components during their operation time leads to accumulation of inelastic strains in the structure. On a microscale level, the degree of plastic deformation is determined by formation and annihilation of dislocations, leading to continuous refinement by creation of new grain boundaries, precipitates relocation and growth. This microstructure rearrangement, triggered by increasing amount of inelastic deformation, is defined as dynamic recrystallization.</p><p class="MsoNormal" style="text-align: justify; line-height: 150%">This work present a macroscale modelling approach for description of continuous dynamic recrystallization observed in Sn-based solder connections. Microstructure evolution is investigated based on scanning electron microscope (SEM) micrographs at initial and different aging states of various solder joint geometries exposed to cyclic loading. Independently from the initial grain size, a similar saturated value of grain size in the vicinity of crack is discovered. Additionally, crack formation and propagation is observed along grain boundaries of a refined microstructure. The rate and distribution of dynamic recrystallization is further numerically modelled dependent on accumulated inelastic strain and governing stress multiaxiality. Parameter study of the presented model and its implementation in finite element (FE) simulation is further described. Finally, FE simulation of the grain size evolution is demonstrated on example of bulky sample under isothermal cyclic mechanical loading, as well as BGA-like structure under temperature cyclic load.</p>

Numerical Modeling of Continuous Dynamic Recrystallization in Sn-Based Solder Connection Under Cyclic Loading

Paper Proceedings: https://asmedigitalcollection.asme.org/InterPACK/InterPACK2021/volume/85505

ASME 2021 International Electronic Packaging Technical Conference and Exhibition (InterPACK2021)

Supporting the need among researchers worldwide for additional online and multimedia content, ASME now offers the ASME Conference Video Collection. This platform will collect and provide long-term access to conference presentation videos, encompassing all technology areas within ASME's technical conference and events program. About 30,000-40,000 engineers across all mechanical engineering and related disciplines participate in ASME conferences each year. This includes authors of approximately 6,000 to 8,000 technical papers published by ASME, the majority of whom also submit video presentations for our virtual conferences. The video collection will be available as an add-on to existing product packages or as a separate subscription.