Dear Mr. Yang,
go to www.kester.com. I think I saw something there. if not, try
www.aimsolder.com
do you happen to know about a good (free) online database that will list
inter-diffusion coefficients of binary metallic system (Ag-Sn, for example)?

sincerely,

Micha Kemelman
972 - 58 - 555802
www.bgu.ac.il/~kemelman