Electronics Forum | Thu Sep 03 14:21:29 EDT 2009 | davef
Creeping corrosion occurs on bare metal. Most commonly, it is seen on boards with thin protective coatings [eg, bare copper, immersion silver, organic solderability preservative]. Look here: * enthone.com/docs/AlphaSTARCreeping.pdf * circuitree.com
Electronics Forum | Wed Nov 29 21:00:02 EST 2017 | truthseeker
Thx for following up. We have a small PCB in a defense application that has copper sulfide issues. We are using Ion chromotagraphy to track down varions ionic species including sulfates. Your post was a aha moment for me. We have a sample being analy
Electronics Forum | Mon Sep 22 15:32:20 EDT 2008 | davef
We see this fairly often. It doesn't affect solderability. Our analysis makes us think this coloration is copper. The reason copper appears on the surface may be that heat cycles increase the thinness and porosity of the immersion silver [IAg] coatin
Electronics Forum | Thu Jul 31 15:41:23 EDT 2003 | davef
Q: Could any of you guys tell me what exactly is this greenish thing ? A: No, but is not copper oxide. Copper oxide is brown, the color of a penny [here in the US] or an untreated copper laminated trace on a board. Many copper salts are greenish in
Electronics Forum | Thu Mar 06 11:48:09 EST 2008 | muse95
Black pad with IAg??? Tarnish is NOT black pad. Tarnish is usually just some silver sulfide on the surface and can also usually be soldered through, by using a little additional, or slightly more agressive, flux, and still make a good quality solder
Electronics Forum | Mon May 14 17:12:20 EDT 2001 | davef
Continuing along the path that Brian took ... IPC-7525 gives design guideline for stepped stencils. It goes something like: * Stepped area SB GT 25 thou from pads located on the greatest thickness of the stencil * Pads in stepped area SB GT 35 tho
Electronics Forum | Fri Aug 20 12:18:11 EDT 1999 | Earl Moon
| I am being asked, by my vendor and Purchasing people about converting from Tin/lead pads on P.C.B's to Electroless Tin Plating. | Can any one tell me what I have to change in my SMT | process (paste, reflow, etc) If any? | I ran one P.C.Boar
Electronics Forum | Fri Aug 20 12:54:11 EDT 1999 | Carol Zhang
| | I am being asked, by my vendor and Purchasing people about converting from Tin/lead pads on P.C.B's to Electroless Tin Plating. | | Can any one tell me what I have to change in my SMT | | process (paste, reflow, etc) If any? | | I ran one
Electronics Forum | Fri Aug 20 14:22:02 EDT 1999 | Earl Moon
| | | I am being asked, by my vendor and Purchasing people about converting from Tin/lead pads on P.C.B's to Electroless Tin Plating. | | | Can any one tell me what I have to change in my SMT | | | process (paste, reflow, etc) If any? | | | I
Electronics Forum | Sun May 30 08:50:42 EDT 1999 | Dave F
| Yes l know this problem keeps cropping up on the forum but l've missed some of the follow-ups. | | Our problem is that the lifting only occurs on 3% of production so actually detecting an improvement is difficult. We're actually having to inspect
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