Lead-free photoimageable silver conductor paste formulation for high density electronic packaging

In the present communication, we have explored the possibility of using bismuth oxide (fritless permanent binder) in place of lead borosilicate glass in our aqueous-developable photoimageable thick film conductor formulation. We have varied the weight percentage of bismuth oxide from 0% to 10% maintaining the inorganic to organic ratio of 72:28 for formulating the pastes. We have employed physicochemical techniques such as TG/DTA, SEM/EDAX and sheet resistance measurement to arrive at optimized weight percentage of Bi2O3 yielding the desired line/space resolution, minimal line shrinkage, better adherence and expected sheet resistance.