Abstract

Solder Joints in PCB’s are typically observed to be the weakest links in the drop impact of most consumer electronics products. A drop-shock analysis and particularly the failure of solder joints involves the modeling of meso-scale solder joints and macro-scale chip packages, which is a typical multi-scale problem. Conventional finite element approaches using beam elements for the representation of the solders and the one-way sub-modeling technique cannot offer a high-fidelity solution in a reasonable amount of time. The two-scale co-simulation approach discussed in this study provides an efficient analysis tool to enrich Integrated Circuit (IC) packaging models with detailed solder joints so that complex failure modes of solder joints and corresponding structural response can be accurately captured. In this context, a detailed solder joint model of a consumer electronics board has been studied using a multi-scale approach in a drop test scenario. The local solder joint models are coupled to the large-scale global packaging model without the need for a conformal mesh at the coupling interface, this largely simplifies the workflow in both meshing, analysis and provides the flexibility to vary the characteristics of local solder models without the added cost of changing the global model. Under this proposed co-simulation framework, data exchange between the two explicit jobs (at different scales) occurs at the coupling interface synchronously using the Message Passing Interface (MPI). Additionally, this approach eliminates the constraint on time step variation imposed by a mesh-sensitive explicit analysis. The concurrent solder joint models with much smaller time-step sizes run separately from the global model, and communication happens at every global time step resulting in low overhead cost. Lastly, the multi-scale analysis has been carried out using the thick-shell/solid-shell PCB’s which are embedded with all the copper traces (as reinforcements) from an ECAD file and have been compared against a trace-mapped shell PCB model and a single scale high-fidelity model. The axial forces in the solder are one of the major post-processing quantities compared among all cases along with the maximum forces in the solders over the entire time history of the drop, this helps identify failure prone solders in the PCB. The multiscale results show a good correlation with the single scale high fidelity model thus validating this approach. A detailed HPC scalability study and the dependency on the no. of processors on the master and slave processes of a multi-scale analysis have also been discussed in detail.