Ingemar I would not minimize either of the issues you mentioned below, gold embitterment and silicon migration under bias. Both mechanisms were originally identified by Bell Laboratories many years ago as the result of server field events. So far as I am aware the laws of Physics have not been repealed and the threats are still with us. We need to be on guard. The real risk is that we as a community are no longer as knowledgeable as we once were about these issues. Engineers, however, are paid for their knowledge and judgment even when the technology is dated. If a dog bits you once, shame on the dog; if he bits you a second time shame on you; even if it's an old dog. Best regards Lee -----Original Message----- From: TechNet [mailto:[log in to unmask]] On Behalf Of Ingemar Hernefjord (KC/EMW) Sent: Tuesday, December 07, 2004 2:44 AM To: [log in to unmask] Subject: Re: [TN] Gold Plated Board Dear Mr Indium & TN, don't you think the Au IMC brittlement risk is little exaggerated? The bright AuSnx are said to be strong, and the darkish ones rotten and risky. Our company have soldered billions of components last decades, a lot with gold flash, and rather few incidents are reported. IMHO there are other factors that are more important, like temperature profile, oxide and debris removal, underplate wetting, solder amount etc. The gold embrittlement hysteria reminds of the 'silicon hysteria' that appeared some years ago. It was reported, that silicon which happened to contaminate relay contacts, could cause severe function problems. This was correct, but the ghost spread to other areas, so now, lots of persons here have 'siliconitus' , which means that silicon is banned to 100%. Insane kind of extrapolation, I'd say. Same with the AuSn formations. Instead, investigate the solder joints and make a professional judgement, TN specialists are certainly eager to assist you. many micrometers of gold, that's another situation of course... Ingemar Hernefjord Ericsson Microwave Systems -----Original Message----- From: TechNet [mailto:[log in to unmask]]On Behalf Of Mike Fenner Sent: den 6 december 2004 18:00 To: [log in to unmask] Subject: Re: [TN] Gold Plated Board Down load the Applications Note "Soldering to gold" from our website, it says same as below but with the numbers, plus a bit more. Regards Mike -----Original Message----- From: TechNet [mailto:[log in to unmask]] On Behalf Of Jack C. Olson Sent: Monday, December 06, 2004 4:31 PM To: [log in to unmask] Subject: Re: [TN] Gold Plated Board The amount of gold on an "Immersion" plated board is only a few microinches think, usually less than 10. When you solder a component to that surface, some or all of the gold (depending on how long the solder stays heated/melted) mixes in with the solder joint. If the percentage of gold in the solder joint is high enough the joint will be brittle, but it won't be that high with such a thin immersion finish. Trying to solder to a thick electroplated gold surface is a different story, however, but you can calculate it yourself by comparing the thickness of gold plating with the amount of solder paste you are applying to the lands in question. I can't remember the exact percentage that means you are getting into the "danger zone", but someone here will know it, or you can search the TechNet archives at: http://listserv.ipc.org/archives/technet.html good luck, Jack --------------------------------------------------- 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 email, its content and any files transmitted with it are intended solely for the addressee(s) and may be legally privileged and/or confidential. 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