Richard, Pd does on the surface of a board what it does in a catalytic converter in a car (i.e., it pulls "stuff" out of the environment) so they put Au over the Pd to protect the Pd. Electroless Pd over electroless Ni was originally being advertised as a universal surface finish that is solderable, wirebondable, and could be used as a contact surface. However, I think the real question that needs to be asked is if electroless processes are hard to control and gold is needed as a final finish because it doesn't corrode then why would anyone use Immersion Gold over Electroless Palladium over electroless Nickel when one could use Immersion Gold over Electroless Nickel and only have one electroless process to control? Regards, George George M. Wenger, Andrew Corporation Reliability / FMA Engineer Base Station & Subsystems Group 40 Technology Drive, Warren, NJ 07059 (908) 546-4531 [log in to unmask] -----Original Message----- From: Stadem, Richard [mailto:[log in to unmask]] Sent: Monday, August 22, 2005 4:19 PM To: TechNet E-Mail Forum; Wenger, George M. Subject: RE: [TN] Black pad If Pd is used over the nickel, then why does one need the gold? The gold is put on to preserve the solderability of the nickel. Does not the palladium do the same thing? I know we would not solder to the palladium. From my bad experiences in the past with palladium applied as a final termination finish to leaded SMT components, I would not want to solder with palladium in the mix if I can help it. -----Original Message----- From: TechNet [mailto:[log in to unmask]] On Behalf Of Wenger, George M. Sent: Monday, August 22, 2005 3:09 PM To: [log in to unmask] Subject: Re: [TN] Black pad Jason, I don't type as fast as I think. I meant to say "without any reference to" not "with any reference to". Regards, George George M. Wenger Reliability / FMA Engineer Base Station and Subsystems Group Andrew Corporation, 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 Wenger, George M. Sent: Monday, August 22, 2005 4:07 PM To: [log in to unmask] Subject: Re: [TN] Black pad Jason, Let me try to answer your question with any reference to "Black Pad". I don't like to use an appearance name to describe a failure mode. The short answer to the question can a brittle interface fracture be present if using NiPdAu is YES. Regards, George George M. Wenger Reliability / FMA Engineer Base Station and Subsystems Group Andrew Corporation, 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 Jason Gregory Sent: Monday, August 22, 2005 3:44 PM To: [log in to unmask] Subject: [TN] Black pad Hello all, after a short hiatus, I'm back. I have a question - Can the Black Pad Defect be present if using NiPdAu? Can the palladium prevent black pad? 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