Detection of cracks in multilayer ceramic capacitors by X-ray imaging
Abstract A non-destructive method using X-ray imaging to find cracks in multilayer ceramic capacitors (MLCCs) mounted in different orientations with respect to the bending direction is presented. In total 300 MLCCs were investigated by 2D and 3D X-ray imaging after bending to varying levels of strain, and cross-section analysis was done to verify the findings. With X-ray imaging it was possible to not only detect the continuously cracked MLCCs, but also the cracked ones which were mounted 45° to the bending direction. These non-continuous cracks are difficult to identify even with cross-section analysis because the crack can be absent at the selected interface. None of the cracks could be identified by external optical inspection of the components using optical microscopy. The MLCCs mounted perpendicular to the bending direction were not cracked during the experiments, whereas the MLCCs mounted 45° or parallel to the bending direction were cracking at 3100 and 4300 μStr, respectively. Finding cracks with a non-invasive technique such as X-ray imaging is very advantageous because of its possible implementation as a screening test in a production environment.