Nature's first green is gold, Her hardest hue to hold. Her early leaf's a flower; But only so an hour. Then leaf subsides to leaf. So Eden sank to grief, So dawn goes down to day. Nothing gold can stay. Inge ----- Original Message ----- From: "John Burke" <[log in to unmask]> To: <[log in to unmask]> Sent: Monday, October 16, 2006 7:07 PM Subject: Re: [TN] Suspect PCBs > Looks like gold, feels like gold, sounds like gold when running the > fingers > through large heaps of coin........Ahhhhhhhhhhhhhhh > > Oooops sorry, > > Got carried away there............8-) > > Late Friday moment, > > John > > -----Original Message----- > From: TechNet [mailto:[log in to unmask]] On Behalf Of Hfjord > Sent: Monday, October 16, 2006 10:01 AM > To: [log in to unmask] > Subject: Re: [TN] Suspect PCBs > > reminds of a problem we had once: there was no nickel at all under the > gold, > XRF or EDAX will tell you. Also, we have seen 'dull gold' from a chinese > supplier. In that case there was nearly no gold present, so what we saw > was > nickel. Again, agree with the others, don't wait, make a XRF or EDAX. > Wouldn't listen to the explanations given, gold is gold, and should look > like gold. Amen. > Inge > > > > ----- Original Message ----- > From: "Tom Parkinson" <[log in to unmask]> > To: <[log in to unmask]> > Sent: Monday, October 16, 2006 3:47 PM > Subject: [TN] Suspect PCBs > > > Hello All (DN & TN), > > I'm having a disagreement with one of my board vendors. We have rejected > some of the boards for "suspect bad pads" (ENIG). During visual > inspection, > the suspect pads 'jump out' at you by looking dark in color. At the very > least, they sure refract the light the wrong way making them look dark in > color. Rotating the board does not make them look better. > > In the past we have tried soldering to these pads and have run into > problems > with wetting. In my letter to the vendor, I mentioned the ENIG was either > too thick, or too thin, both which will cause problems. > > I'm especially worried about these when they are under BGAs. > > The vendor says there is nothing wrong with the pads as-is. In fact he > said > the following: > > ========================= > "Boards are good. There is no black Pad - only dull gold. Xxxxxx (board > vendor) is "Cleaning" the gold to make it look "Pretty". We will be > returning the boards on Monday to you. > > There is always a variation in surface color with any immersion gold > process. It may be minimal in some cases or more obvious as in the boards > in > question. But problem is not the correct description, variation is the > correct term. It will not effect form fit or function. > > The color variation you refer to is not because of the variation in > thickness. Three to seven micro-inches of gold is deposited over 100 to > 150 > micro-inches of nickel. The gold vaporizes during your reflow process and > the adhesion is solder to nickel. There will be no adherence problem. By > the > same token, there is no embrittlement problem with immersion gold as there > would be with electro-plated gold. For one thing electro-plated gold is 10 > times thicker than immersion gold. Secondly the grain structure of > immersion > gold and electro-plated gold is very different. Electro-plated gold having > a > long grain structure in comparison to immersion gold. > > Using a pencil eraser as you suggest only proves my point. The surface > color > variation is caused by an alkaline deposit on the surface of the gold > which > vaporizes on contact with molten solder. We propose to clean the boards > using a mild baking soda solution." > ========================== > > Looking forward to your inputs. > > Thanks, > > Tom > > > > Tom Parkinson > Quality System Manager - CIT > WinTronics, Inc. > Phone: 724-981-5770 - extension 235 > > --------------------------------------------------- > 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 > ----------------------------------------------------- > > --------------------------------------------------- > 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 > ----------------------------------------------------- > > --------------------------------------------------- > 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 > ----------------------------------------------------- --------------------------------------------------- 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 -----------------------------------------------------