Hi Richard! The gold acts as an "environmental barrier" to the prevent the Pd from collecting things from the use environment. Pd is a real cool element - it has properties which allow some pretty nice physics (Pd is used to seed plated thru holes for plating). A thin flash of gold over the Pd dramatically increases long term solderability and wettability. Texas Instruments has been putting a flash of gold on their classic Pd/Ni component finish for several years now as a surface finish improvement. Rockwell Collins did some testing of Au/Pd/Ni and Au/Pd/Cu pwb finishes in the late 90's - we had great success in the testing portion of the program but the expense/availability of the finish are big disadvantages. Au/Pd/Ni has been called the "universal" finish as it can be both a wirebondable and solderable surface finish. You can also get Pd embrittlement of solder joints in a similar fashion to Au embrittlement - the embrittlement is another issue that some folks don't want to deal with so the finish is avoided. Good control of the Pd thickness and your soldering process can result in avoidance of Pd embrittlement issues. Dave Hillman Rockwell Collins [log in to unmask] "Stadem, Richard" <Richard.Stadem@G D-AIS.COM> To Sent by: TechNet [log in to unmask] <[log in to unmask]> cc Subject 08/22/2005 03:18 Re: [TN] Black pad PM Please respond to TechNet E-Mail Forum <[log in to unmask]> ; Please respond to "Stadem, Richard" <Richard.Stadem@G D-AIS.COM> 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? Jason Gregory Manufacturing Engineer Innova Electronics (281)653-5593 (281)653-5594 fax (281)212-0844 cell [log in to unmask] --------------------------------------------------- Technet Mail List provided as a service by IPC using LISTSERV 1.8e To unsubscribe, send a message to [log in to unmask] with following text in the BODY (NOT the subject field): SIGNOFF Technet To temporarily halt or (re-start) delivery of Technet send e-mail to [log in to unmask]: SET Technet NOMAIL or (MAIL) To receive ONE mailing per day of all the posts: send e-mail to [log in to unmask]: SET Technet Digest Search the archives of previous posts at: http://listserv.ipc.org/archives Please visit IPC web site http://www.ipc.org/contentpage.asp?Pageid=4.3.16 for additional information, or contact Keach Sasamori at [log in to unmask] or 847-615-7100 ext.2815 ----------------------------------------------------- ------------------------------------------------------------------------ ------------------------ This message is for the designated recipient only and may contain privileged, proprietary, or otherwise private information. 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