I don't know the answer to your questions Nora, but while you are preparing to change finishes, you might want to take a look at Palladium/Nickle finish too. We were looking for a flatter finish on fp smt and had started to look at Pd/Ni as a possibility when the project was sidelined. A buyout and other changes have moved this to a far back burner for now. Good luck! Charlie Barker Manufacturing Engineer Input/Output, Inc. Stafford, Texas To: TechNet @ ipc.org @ Internet cc: (bcc: Charles Barker/IO-US) From: qun.n.xiao @ bangate1.tek.com @ Internet Date: 01/16/96 01:58:49 PM Subject: Solderability issue on Ni/Au We are switching from HASL to Ni/Au process and realize that on Ni/Au boards, solder paste is not spread out as well as HASL process. Wettability of the pad edge becomes a major concern. I have some questions regarding Ni/Au process and would like to discuss with anyone who have been involved with this alternative surface finish. Is this problem associated with the inherent nature of Ni/Au material surface characteristics, or is it associated with the oxidation and/or contamination of the metal surface (Although Au is very stable, Ni tends to oxidize even at moderate temperature ) ? It has been recommended to use sulfuric acid or plasma to clean Ni/Au surface, is it a feasible approach? If yes, who shall perform this cleaning step: PCB fabricator or PCB assembler? By the way, what is the shelf life of Electroless Ni/Immersion Au board under normal storage condition? Our vendor claims that HASL and OSP both have the avg. shelf life as 12 months, but is unable to provide the corresponding avg shelf life for Ni/Au. Thanks in advance for any response. Nora Xiao Process Engineer Tektronix, Inc. Beaverton, OR