To: Msg to Internet M2I From: David Estes DGE1 Subj: Re: TechNet inquiry re: immersion gold reliability if not soldered Subj: Reliability of immersion gold if not soldered 1. Does anyone have any data or recommendations regarding long-term reliability of immersion gold that is NOT soldered at assembly? Please describe the gold thickness and nickel barrier thickness associated with your response. 2. Are there other alternate solderable finishes that if NOT soldered will not create an oxidation or corrosion risk? Looking for an alternative to a selectively plating a thick layer of electroplated gold. The specific application is a commercial or consumer application whose typical operating conditions would be standard indoor temperature/humidity and a average duty of several hours/day for 10 years. The board has a fine pitch device or socket mounted to the board with a conductive elastomeric adhesive. Current board design has this land pattern (selectively) electroplated with nickel-gold with selective HASL for the rest of the board. The reliability concern is this: if a corrosion-resistant coating is not applied to the land pattern, corrosion to the base copper or the coating could impact electrical performance (and system reliability). Would like to find a single finish which is solderable and, when not soldered, resists corrosion. If this is not possible, would consider an alternate selective finish that is lower cost than electroplated gold. Regards, David Estes PCB Commodity Engineer Texas Instruments, Inc. e-mail: [log in to unmask] Phone: (214) 995-5238 Fax: (214) 995-1106