No one likes being controlled by the cost of silver. We deal with fluctuating Ag costs here at Indium Corporation on a very large scale – so I understand the issues with using Ag-filled low temperature metallization paste for thin-film solar cell interconnection.
People always ask for alternative fillers like copper – although the chemistry of metallization paste doesn’t allow the substitution of most filler materials. Our solution is a new material: silver-plated copper particles.
Silver-plated copper particles allow us to utilize a very low amount of silver precisely where it needs to be, on the surface of the particles. By tricking our metallization paste chemistry into thinking it is still working with silver flakes, we are able to maintain the same high levels of flexibility, fine line printing, and adhesion that we have become accustom to with materials such as LT-918 metallization paste.
Due to the inherent bulk conductivity difference between copper and silver, very lowest resistances will still be achieved with solid silver flake metallization pastes. The silver-plated copper material has performed unexpectedly well in electrical performance though, winning over some customers due to a substantial difference in price.
Our new silver-plated copper particle material is currently in beta testing, and has completed over 2,000 hours of dry and damp heat testing. Our data so far has confirmed superior print performance, and customers like the fact that the material can be shipped at room temperature. If you are interested in beta testing the material, please let me know.