Assessment of 3D micro-computed tomography for PV interconnection technology development

Abstract

X-ray (micro-)computed tomography is a non-destructive characterization method using photons to obtain multiple radiographic projections, which generates a 3D volume rendering of a scanned object after reconstruction. It is recently used in the research and development of photovoltaic modules to investigate smaller volumes in a PV module, for example, detection of cavities in solder joints and visualization of module volumes up to connection ribbon sizes. This work shows that current advanced devices are able to scan larger volumes, using a single-cell 20 x 20 x 0.5 cm(3) module with back-contact multi-ribbon interconnection technology as an example. The generated 3D volume renderings show the interconnection structures and give information on ribbon-metallization interconnections. Next to this, also the solder reflow volume is visible, indicating that the technology has great potential to be used in further interconnection technology development. Finally, a destructive cross section analysis using scanning electron microscopy is performed; it has a higher resolution and can differentiate elements with similar photon absorption coefficients, thus enabling microstructure and intermetallic compound analysis. The findings show the potential for micro-computed tomography as a nondestructive and relatively fast visualization method and how it can give complementary information to other characterization techniques for photovoltaic interconnection research.