Sorry, I see that I posted to the wrong guy... I meant that message for Ralph Richart... I believe he was the originator... I concur with your findings however. The thing that amazes me is that the buyer or QC dept of whatever company is purchasing these boards is trying to backtrack to the gold immersion stage of the process after the board has already been assembled correctly... Obviously they were successful in assembling the board with HASL as a preparatory coating and have no further need of any other processes to complete the assembly. It was probably not a requirement to conformal coat the board, in the first place... they just replaced a process that is intended to prepare the surface of the board to receive components...with another that is totally acceptable in most all applications, HASL...., which obviously, has been successfully accomplished.... they have populated the boards... They will ruin the boards if they try to plate gold over the soldered component lands and leads....the exposure to the chemicals will oxidize and etch the surface of the tin-lead and any vulnerable components.. and make the boards rejectable due to bad solder and damaged components.....a no-win scenario..... Bill Brooks Sr. PCB Designer -----Original Message----- From: Alain Savard [mailto:[log in to unmask]] Sent: Thursday, June 08, 2000 11:58 AM To: [log in to unmask] Subject: Re: [TN] still confused Sorry Bill, but my post was accidental.. I accidently clicked the send button before typing my answer. Conformal coating prevents corrosion at that point, NOT gold. Adding gold over the solder will NOT significantly increase corrosion-resistance, but the chemicals used to gold-plate are very likely to damage the components. Alain Savard, B.Sc. Chemical Process Analyst CAE Electronics Ltd. -----Original Message----- From: Brooks Bill [mailto:[log in to unmask]] Sent: June 8, 2000 2:26 PM To: [log in to unmask] Subject: Re: [TN] still confused Alain, I feel for your situation.... It sounds to me like a messed up note on the drawing. Gold - OVER - solder has never been a recommended procedure in any documentation I have ever seen in my 30 years of doing boards... especially after the board has been populated. The only use of gold I have seen is those repair kits for adding gold to edge connector fingers like the type used on PCI cards that may have worn the gold down over time... IF I WERE YOU... I would make an effort to get past the buyer to the designer behind the board and get him to straighten out the buyer.... Tough situation.... good luck. - Bill Brooks -----Original Message----- From: Alain Savard [mailto:[log in to unmask]] Sent: Thursday, June 08, 2000 10:09 AM To: [log in to unmask] Subject: Re: [TN] still confused -----Original Message----- From: Ralph Richart [mailto:[log in to unmask]] Sent: June 8, 2000 12:55 PM To: [log in to unmask] Subject: [TN] still confused We have answers.... So I had a long talk with my customer this morning to provide input based on the invaluable advice from you all. I said - "is there a specific reason for choosing 3-8u" of immersion gold over tin/lead solder?" He said - "absolutely, the gold provides corrosion resistance, the gold does not" I said - "even such a thin amount - only 3-8u"?" He said - "definitely, all we need is the coverage, the thickness is irrelevant" Is this true? Needless to say, we are rebuilding the parts as we speak. Rework sounds difficult to say the least, although I may try to come up with some scheme for fun as they have a bunch of boards that are no good right now. thanks for all the help..... ralph PS - more on the larrylobster story later; it's more silly than anything else. Paul's poem may soon become our own, however. Very funny! Off to build some boards.... ############################################################## TechNet Mail List provided as a free service by IPC using LISTSERV 1.8c ############################################################## To subscribe/unsubscribe, send a message to [log in to unmask] with following text in the body: To subscribe: SUBSCRIBE TECHNET <your full name> To unsubscribe: SIGNOFF TECHNET ############################################################## Please visit IPC web site (http://www.ipc.org/html/forum.htm) for additional information. 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