There is actually a lot of data regarding conductive adhesives on nearly 
every substrate, many by independent organizations; IVF (Swedish Research 
Institute), DELTA (Danish Research Group), MCC. Adhesives can be designed 
for good junction stability on Sn/Pb and several companies are in 
production with same. Our criterion is less than 20% change in junction 
resistance after 1000 hr. 85/85 and a properly designed product can 
actually increase in conductivity after T&H. The real weakness (based on 
customer response) is lower mechanical strength and poor shock (NCMS drop 
test) resistance compared to Sn/Pb, especially with J-leads. Adhesives 
work in many, but not all applications. For more information, see article 
Polymer Electronics at Web site http:/www.alphametals.com and/or read the 
new book, "Polymer Thick Film", Van Nostrand Rheinhold, NY, which covers 
adhesive assembly.