For those unfamiliar with the terminology, SAC305 = 96.5% Tin + 3.0% Silver + 0.5% Copper. I think the percentages are by weight, although I could be wrong. The chemical symbol for Tin is Sn, Silver’s symbol is Ag, and Copper’s symbol is Cu. Tin/Silver/Copper = Sn/Ag/Cu = SAC.
The report is available at www.ipc.org, a page explaining the major findings is here*. From discussions I have seen on the IPC lead-free discussion list, immersion silver (ImAg) was the finish used on all PCBs for the test, as the test was trying to compare different types of solder (not different types of finish). I also think someone said the tests were all for IR Reflow conditions, but I could be mistaken about that.
I don’t have a full copy of the report, but I have seen posts by some of the study participants who say that a lot of research was done, & if you purchase the report you get raw data, not just conclusions.
* – The full URL is http://www.ipc.org/3.0_Industry/ 3.5_Councils_Associations/3.5.1_Industry_Assoc/ spvc_bro/SVPC_Final_ExecSumm.pdf. Be sure to take out any spaces after forward slashes if you try to post that in your browser. I had to add the spaces otherwise this column won’t do its text-wrapping correctly on the website.