No brainer indeed Ed ; yo're dead right ; with more than 1um on leadless yo're doomed . As you went through IPC files ; you should have all contacts and references ; I'd just add the time factor (or timebomb if you prefer) on intermetalics growth (which shocks or vibro tests will not tell you) ; if Werner shakes his grankids off he'll tell you something proper which you may not have time for ; we cycled gold 7 months to get something resembling reality (IPC-SM-785) . See you Paul Klasek http://www.resmed.com PS Just a practical paradox ; there is an application where they might live : implantables [ no vibrations ; and constant 37'C ] ; hehehe (is Steve on holidays?) Wish you luck with the management > ---------- > From: Knowles, Ed[SMTP:[log in to unmask]] > Sent: Tuesday, 6 April 1999 7:28 > To: [log in to unmask] > Subject: [TN] Gold Embrittlement > > Please don't blast me on bringing this subject up again. I have searched > the TechNet archives and found lots of good information, and also noted > that > it is a somewhat sensitive subject, having been around for 30+ years. We > have a condition that I believe is clearly unreliable based on what I have > read. The condition is: > > - 4 lead LCCC's (leadless with castellations) > - Approximately 50 microinches of glod plating on untinned castellations. > - Untinned parts mass reflow soldered onto PWB's (parts were supplied on > tape and reel, so subcontractors did not see that they were untinned). > - Microsectioning shows a 50 to 100 microinch layer of Au/Sn intermetallic > after soldering, on top of copper/nickel surface. Au concentration > averages > about 25% in this intermetallic region. > - These assemblies will be subjected to high vibration and long term > (years) > thermal cycling in actual use. > > Replacement of these parts would be expensive since they are on many > boards > installed in closed and tested boxes. For this reason, mangement is hoping > that testing will qualify this condition. I hate to see the affected > program waste time and money, and am afraid they might even get a warm > fuzzy > and fly these parts. > > Can any of the numerous industry experts in this group give me something > concrete to present to the program such as actual experiences or > obtainable > reports? Is the above condition a no-brainer or is it not as bad as it > looks to me? I tried getting copies of the 2 reports listed in the > J-STD-001 Handbook, but struck out. > > Thank you for your time. > > Ed Knowles > Lockheed Martin > [log in to unmask] > > ################################################################ > TechNet E-Mail Forum 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's web site (http://www.ipc.org) "On-Line Services" > section for additional information. > For technical support contact Hugo Scaramuzza at [log in to unmask] or > 847-509-9700 ext.312 > ################################################################ > ################################################################ TechNet E-Mail Forum 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's web site (http://www.ipc.org) "On-Line Services" section for additional information. For technical support contact Hugo Scaramuzza at [log in to unmask] or 847-509-9700 ext.312 ################################################################