Electronics Forum: sulfur (Page 1 of 4)

Soldermask - sulfur presence

Electronics Forum | Mon Jun 25 03:52:24 EDT 2012 | awtm

Our Customer had detected tarnished pad on ImAg PCBA and had conducted several SEM-EDX test at the soldermask below some of the chip resistors. High concentration of sulfur was found and it can be significantly reduced after further chemical cleaned

Soldermask - sulfur presence

Electronics Forum | Mon Jun 25 11:33:20 EDT 2012 | davef

The immersion silver is an active surface and readily combines with sulfur from the environment. Silver sulfide tarnishes the surface and creates doubt about the integrity of the finish at inspection. [uyemura.com/library-4.htm] Your customer's boar

Sulfur in ESD Mat

Electronics Forum | Wed Nov 29 20:54:32 EST 2017 | truthseeker

DAVEF: In "Soldermask - sulfur presence" [http://www.smtnet.com/Forums/index.cfm?fuseaction=view_thread&CFApp=1&Thread_ID=16291&#Message66659], how did you determined that sulfur was coming out of mats onto boards?

Silver Sulphide Contamination of Resistors

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

PCB becomes darken (yellownish)

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

Silver Sulphide Contamination of Resistors

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

PCB becomes darken (yellownish)

Electronics Forum | Fri Aug 22 09:07:22 EDT 2008 | blnorman

Sulfur is probably the culprit. Board supplier should be providing boards with anti-tarnish sheets between the individual boards. Also, cardboard is a major source of sulfur and so boards should not be shipped in cardboard.

Sulfur in ESD Mat

Electronics Forum | Wed Nov 29 20:57:10 EST 2017 | davef

Jez, you're digging away in the grass on this one. Long time ago. Look at: FED-STD-101, Method 3005 for reducible sulfur. The standard is maintained by some packing material group. Interestingly, it's not uncommon to see it referenced in other elec

Oxidation on PCB's

Electronics Forum | Mon Aug 04 12:38:25 EDT 2008 | blnorman

Avoid cardboard boxes as well. They are sulfur bearers, and silver has an affinity to form silver sulfide.

Silver Immersion Finish - Moisture bake out guideline?

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

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