DEK Solar’s senior process development specialist, Tom Falcon, presented a paper on the latest advances in print-on-print (PoP) technology to assembled delegates at a metallization workshop organized by the Energy research Centre of the Netherlands (ECN). Falcon outlined the findings of a major research project conducted by DEK, along with associated opportunities for solar cell metallization.
Falcon said, “Print-on-Print itself is not a new idea; but the implementation of this technique in a high volume manufacturing environment requires much more than an accurate printing machine. Our new research outlines the development of a successful PoP process to show how we can deliver a measurable and consistent improvement over a single print for dramatically improved productivity.”
The paper describes the development of a PoP process for high aspect ratio front-side conductors, with in-depth results spanning the testing of various screen types, aperture widths, emulsion thickness, paste types and process parameters to empirically determine optimization.
Among the conclusions reached was the fact that paste choice is critical to maximize performance and that quality screens are essential for alignment. Finer meshes and moderate emulsion are identified as delivering optimal prints while screen life is proven to stand at around 7.5K wafers. DEK Solar also found that an approximate increase of 40% in conductor aspect ratio is possible and sustainable in high volumes over a single print.