Electronics Forum | Wed Sep 03 11:42:21 EDT 2008 | robinj
If the tarnish is really dark, it is very difficult to remove. Since it is yellowish it is only in the early stages. Replating will definitely work. I have used sulfuric acid based cleaners to remove this yellowish color. But rinse well and dry quick
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 | Wed Feb 21 19:55:12 EST 2001 | davef
References on corrosion are: * "ASM Corrosion Handbook No. 13" [0871700077]. * "Electronic Packaging and Corrosion" ME Nicholson [0871702916]. Please explain how you determined that you have silver-sulfide contamination. Where is the silver comin
Electronics Forum | Mon Feb 26 09:36:08 EST 2001 | blnorman
ASTM E 443 is a test for sulfur by Oxygen Flask Combustion. Other instruments will detect sulfur (I assume a SEM with EDS capability will pick up the sulfur). We had an addition cure silicone potting compound inhibition problem last year that was t
Electronics Forum | Mon Apr 26 14:40:07 EDT 2010 | blnorman
We had one product that used immersion silver plating. There were a couple of instances where we saw tarnishing, and elemental analysis confirmed the presence of sulfur. These boards did have the anti-tarnish sheets between boards, but somehow they
Electronics Forum | Wed Feb 21 21:28:24 EST 2001 | davef
I don't know where sulfur would get into your resistor supplier's process. Your processes are more likely candidates.
Electronics Forum | Sun Feb 23 14:32:42 EST 2003 | davef
Sources of sulphur in PCB fabrication are: * Some locales have high H2S concentrations in the air. * Metal etching steps that use sulfuric acid or a sulfonated buffering compound may result in sulfate residues. * Sulfates can come from contact with
Electronics Forum | Thu Jul 26 23:52:24 EDT 2007 | gioblast
HI..anyone who can give me a link to enlighten me on this plating for pb-free..Most people say this is the same? ARe they really? or different in process?? ..Any info on best storage for this plating? I have read all those stuff like avoiding sulfuri
Electronics Forum | Thu Sep 03 12:03:52 EDT 2009 | Sean
Hi All, I have few questions about creeping corrosion that potentially happen on lead free immersion silver PCB as below: 1) What test that we can conducted to verify whether the failure we seen is due to creeping corrosion? 2) I heard that lead fr
Electronics Forum | Wed Feb 22 08:31:42 EST 2006 | davef
Q1 Are there any standard regulating the subject? Very few infos found on IPC. A1 We�re unaware of standards for packing and storage for most types of boards. * IPC 4553 standard for Immersion Silver Finish, 3.8 Packing and Storage. * J-STD-033 and E
