I'm not sure I can give you a direct answer for tin but I c Bev, I'm not sure I can give you a direct answer for tin but I can give you an answer for SnPb solder. In the RF world there are lots of gold plated components that can have very thick gold (>2.5um). Because of solder joint reliability reliability concerns it has been standard practice to pre-tin (expose to SnPb wave or use a double dip in to solder pots) to dissolve most of the gold) and the resulting pre-tinned surface does contain some gold. The amount of gold remaining in the solder on the surface of the components is dependent on the quality of the pr-tinning process. However, we've seen many surfaces of pre-tinned components with up to at least 4% gold and have not seen any solderability issues. Regards, George George M. Wenger Senior Principle FMA / Reliability Engineer CommScope / Andrew Wireless Solutions 40 Technology Drive, Warren, NJ 07059 (908) 546-4531 [log in to unmask] -----Original Message----- From: Bev Christian [mailto:[log in to unmask]] Sent: Wednesday, January 16, 2008 9:04 AM To: Wenger, George M.; TechNet E-Mail Forum Subject: RE: [TN] Solderability of Tin-Gold Intermetallic George, Correct of course. That is what I meant. How about my question? Bev RIM -----Original Message----- From: Wenger, George M. [mailto:[log in to unmask]] Sent: Wednesday, January 16, 2008 9:03 AM To: TechNet E-Mail Forum; Bev Christian Subject: RE: [TN] Solderability of Tin-Gold Intermetallic Bev, I think I would re-state your first sentence. "We all know that tin-copper intermetallic that has come to the surface and been exposed to the environment has terrible solderability." I view tin-copper as the glue layer between solder and copper when solder touches copper and forms an intermetallic the solder above the intermetallic must wet it otherwise it would fall off. Regards, George George M. Wenger Senior Principle FMA / Reliability Engineer CommScope / Andrew Wireless Solutions 40 Technology Drive, Warren, NJ 07059 (908) 546-4531 [log in to unmask] -----Original Message----- From: TechNet [mailto:[log in to unmask]] On Behalf Of Bev Christian Sent: Wednesday, January 16, 2008 8:52 AM To: [log in to unmask] Subject: [TN] Solderability of Tin-Gold Intermetallic Technetters, We all know that the tin-copper intermetallic has terrible solderability. I also know there are high melting tin-gold solders. My question is: what is the solderability of surfaces of tin with small amounts of gold (<4%) in it? As good as 100% tin, better, worse? If worse, how much so? 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