X-ray micro-CT and digital-volume correlation based three-dimensional measurements of deformation and strain in operational electronics

Electronic components 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. Previously, deformations in in electronic components and assemblies have been measured using optical methods including moiré interferometry and digital image correlation - both of which require the cross-sectioning of the solder joint to gain access to the joint of interest for the purpose of strain and deformation measurement. Cross-sectioning is an invasive technique which requires discarding a portion of the package. In addition, the measurements are often limited to line of sight allowing measurement of only the optically visible cut-section. In this paper, a new method has been presented for measurement of displacements in solder joints non-invasively using a combination of x-ray computed tomography and digital volume correlation. 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. It is envisioned that the method will allow the validation of the deformation and strain field in interconnects of the electronic package. Measurements of deformation and strain on light-emitting diodes and ball-grid array packages have been made using the combination of digital volume correlation and x-ray computed tomography.