Remaining Useful Life Assessment of Field Deployed Electronics Using X-Ray Micro-CT Based Digital Volume Correlation and Finite-Element Analysis

A new method for residual life assessment of field extracted electronic systems using X-ray MicroCT data in conjunction with digital volume correlation (DVC) and finite element analysis (FEA) has been presented. Electronic components deployed in harsh environments may be subjected to significant deformation under the action of thermal and mechanical loads during operation and storage. The use of thin material layers in addition to fine embedded interconnects limits the possibilities for the integration of sensors to measure deformation and strain. In addition, models for semiconductor assemblies are created using nominal dimensions from a material datasheet. However, the use of nominal dimensions does not account for the dimensional variabilities of the geometry due to process-variance in the manufacturing process window. In this paper, a new method has been presented for measurement of displacements and assessment of remaining useful-life in solder joints non-invasively using a combination of X-ray computed tomography, DVC and FEA. The new method does not require cross-sectioning of the part for the purpose of deformation and strain measurement. In addition, the measurements are not limited to the joints in the line of sight. The three-dimensional measurements of deformation and strain have been visualized on the geometry of the solder joints in the package. Furthermore, the X-ray MicroCT grayscale data has been ported into a finite element platform. Anand Viscoplasticity model of SAC305 has been utilized and merged into the FEA software to model material behavior of solder interconnects. The method has been applied to a field extracted assembly for analysis of residual life of solder joints with partial cracks in cyclic thermal environments. The cumulative plastic work and stress-strain hysteresis loop have been plotted.