Electronics Forum | Tue Oct 26 14:11:25 EDT 1999 | Dave F
Gary: Two things: 1 Reworking golding fingers is an old topic, check the SMTnet archives to get started. 2 Gold fingers should not be discoloring, unless: * You are doing something bad to them ... OR * Your supplier has doinked the process, which
Electronics Forum | Tue Jan 22 20:26:18 EST 2002 | davef
Help us visualize this better. * What color white [ie, yellow/white, green/white, a haze, etc.] are we talking about? * What size and shape are the spots? * Where are the spots located? * Etc Help us understand what�s going on by describing the sp
Electronics Forum | Wed Jul 28 17:34:27 EDT 2004 | Steve Stach
Hi Ralf, This discoloration may be re-oxidation. Fluxes are supposed to do three things (1) remove oxide, (2) promote wetting, and (3) protect surface from reoxidation. The solder paste possibly is not protecting from reoxidation. Best Regards, St
Electronics Forum | Wed Jun 22 15:03:12 EDT 2005 | patrickbruneel
The only thing ammonia can do is tarnish copper and make it more difficult to solder. And the higher temp in lead-free will discolor the latex (giving it a sticky surface), but the functionality of the mask will be intact. There should be greater co
Electronics Forum | Mon Mar 06 07:42:48 EST 2006 | davef
Epoxy inks tend to be more resistant to discoloration than the acrylics that are used more widely now. The acrylic-based inks vary in their ability to maintain color after heat cycles. The technical data sheets from the ink supplier should indicate:
Electronics Forum | Tue Dec 11 15:31:53 EST 2007 | chrisatae
We accidentally mixed water wash with RMA flux. When the heat was applied during through hole soldering we noticed a problem and we cleaned it as soon as we discovered it. But now there's a discoloration where it was applied. Anyone experience this a
Electronics Forum | Fri Aug 22 10:01:52 EDT 2008 | robinj
I have seen this problem before. If the color is yellow usually it is caused by moisture left on the boards from poor drying after immersion silver. One of the ways to get rid of this is by dipping in acid cleaner solution. If the board supplier uses
Electronics Forum | Wed Aug 27 18:28:29 EDT 2008 | blnorman
We have an immersion silver board that has a brown discoloration after processing. It's not flux residue, that normally doesn't cause this condition. Elemental analysis shows less than 1% sulfur, and I thought silver sulfide is more a black color.
Electronics Forum | Fri Sep 12 17:07:05 EDT 2008 | davef
While you're waiting for others to reply, check these recently posted threads on discolored immersion silver [IAg] here on SMTnet: * http://www.smtnet.com/Forums/Index.cfm?CFApp=1&Message_ID=56220 * http://www.smtnet.com/Forums/Index.cfm?CFApp=1&Mes
Electronics Forum | Sun Aug 16 16:01:06 EDT 2009 | davef
White, lead free * Taiyo America PSR-4000 LEW1 * Huntsman (formerly Vantico, formerly Ciba Geigy) Probimer 77 white solder mask Also, search around LEDs Magazine [ http://www.ledsmagazine.com/ ]. White solder masks are often used as a reflective ba
