Heraeus Photovoltaic Business Unit, a developer of advanced front and back-side silver paste for crystalline solar cells has introduced the SOL200 Series for back-side tabbing conductors for mono- and multicrystalline silicon solar cell wafers. SOL200 has been claimed to demonstrate lower paste laydown while maintaining excellent solderability with both leaded and lead-free solders while maintaining high adhesion and high electrical performance.
Silver metallization pastes have become one of highest material cost parameters in c-Si solar cell fabrication due to the dependence on the core market price of silver (Ag). The need for both high-performance silver-based pastes for improved cell performance and cost-effective conducting materials is a critical requirement for PV manufacturers.
Following the successful development and market introduction of SOL230 a few years ago, Heraeus has developed the new SOL200 Series for back-side tabbing conductors that has demonstrated lower paste laydown while maintaining good solderability, high adhesion and high electrical performance. The increase in adhesion also demonstrates a better quality solder joint. The affect of humidity or contaminants on the integrity of the solder joint is minimized giving reliable thermal cycling and improved lifetime testing results, according to the company. Increased paste coverage with improved results can provide savings via improved performance. Coverage with SOL200 is claimed to be significantly better than competitive materials. Increased paste coverage translates into lower paste consumption.
Back-side tabbing conductors for mono- and multicrystalline silicon solar cell wafers.
The new SOL200 Series is available in SOL220, and SOL210. The SOL210 solver paste is said to use 10% less silver than the SOL230. Screen printing parameter recommendations include the use of a 200-280 mesh stainless steel screen with 10-14μm emulsion. Typically dried in an IR dryer with set points of 250-300°C in less than 20 seconds or 150°C for 10 minutes in a circulated air oven. Co-fireable with back-Al and front-Ag pastes.