Ex-situ Measurement of Internal Deformation in Ball Grid Array Package with Digital Volume Correlation

In spacecraft electronic devices, the deformation of solder balls within ball grid array（BGA） packages poses a significant risk of system failure. Therefore, accurately measuring the mechanical behavior of solder balls is crucial for ensuring the safety and reliability of spacecraft. Although finite element simulations have been extensively used to study solder ball deformation, there is a significant lack of experimental validation, particularly under thermal cycling conditions. This is due to the challenges in accurately measuring the internal deformations of solder balls and eliminating the rigid body displacement introduced during ex-situ thermal cycling tests. In this work, an ex-situ threedimensional deformation measurement method using X-ray computed tomography（CT） and digital volume correlation（DVC） is proposed to overcome these obstacles. By incorporating the layer-wise reliability-guided displacement tracking（LW-RGDT） DVC with a singular value decomposition（SVD） method, this method enables accurate