Effect of polymer binders in screen printing technique of silver pastes

Silver pastes are widely used in the front-side metallization of crystalline silicon solar cells via screen printing technique, with an aim to print conductive lines bearing a high aspect ratio which helps reduce electric resistance and improve the overall device efficiency. Rheological features are very important to describe the paste behaviors during screen printing as well as in the formation of fine conductive lines on wafer substrate. In this study, three different silver pastes and two individual components (i.e., silver powder and polymer binder) have been systematically investigated, revealing how the altering rheological features due to the addition of polymer binders—despite a typically low weight percentage—can significantly impact the (simulated) printing quality of a silver paste. The results point to the imperative need to delve into the effects of polymer species, polymer molecular weight and its weight percentage in order to systematically improve the printing performance of metal pastes without altering its main (powders) component.