A large number of solar cells is metallized by printing and firing glass containing silver pastes. However, the contact formation is not fully understood so far. There is still a lack of understanding the role of the glass phase in the complex contact formation scenario because single effects could not been seperatly observed and evaluated up to now. To overcome this, an in-situ method to observe the contact formation via a contact resistance measurement was introduced. A special measuring device was applied to characterize two typical front side pastes, featuring a PbO-containing as well as a PbO-free glass frit during firing. The viscosity of the paste glass showed decisive influence for the etching of the anti-reflection coating (ARC). The ARC was opened immediately after entering the softening range of the respective glass, regardless of large differences in glass chemistry. Furthermore, the viscosity-temperature behaviour of the paste glass determines the intensity of the redox-reaction and related silver precipitation at the interface, which takes part between ARC opening and glass resolidification. The cooling slope was confirmed to have decisive influence on the final interface conductivity, because a crucial part of silver colloids can be formed here
New conductor pastes for AlN as substrate material with fired films of a sheet resistance below 25 mOhm/sq were investigated. The pastes consist of AgPd as conductive phase for leach resistance. Other paste ingredients are glasses of matched composition for adhesion and densification properties, little amounts of inorganic additives and organic vehicles for film deposition. The latter has a significant influence on the paste deposition and the resulting film properties as well. In order to shine light into these relationship systematic rheological studies of the organic vehicle and the manufactured pastes were performed. The rheological investigations include measurements in rheological steady-state as well as dynamic experiments. In addition, the solder properties of the fired film were studied. FESEM analyses were performed on the surface of the fired films.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.