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March 2012

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Subject:
From:
Gerry Gagnon <[log in to unmask]>
Reply To:
TechNet E-Mail Forum <[log in to unmask]>, Gerry Gagnon <[log in to unmask]>
Date:
Sat, 3 Mar 2012 04:33:43 -0500
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Inge, I agree with you.  It has been many years since I have run the infamous nitric acid porosity test, but it looks to me like copper migration through nickel (if present) and gold. This will give the greenish look. If the gold is thin/porous and there is nickel underneath, the spots will appear black. Also, the sidewalls of the fingers will generally not get plated well (if at all) and there may be some copper exposed there. Gerry
 > Date: Fri, 2 Mar 2012 16:03:01 +0100
> From: [log in to unmask]
> Subject: Re: [TN] Field Return Product w/corrosion product
> To: [log in to unmask]
> 
> Victor,
> I did not have sufficient time to search, but found at least one of my  old
> reports. This solder joint was taken for a corrosion issue, but it was not.
> Instead it was about copper that had migrated to the surface and then
> oxidized. Bad finish, with other words. I post the photo ufflein to you.
> 
> Inge
> 
> On 29 February 2012 18:32, Inge Hernefjord <[log in to unmask]> wrote:
> 
> > Hola amigo; quizás no está una cosa de c. I have seen lots of cases where
> > you have misjudged intermetallic formations and taken them for corrosion.
> > Typical example is the much discussed ' purple plague ' . So, before
> > anything else you should have a look at the object in a high magnification
> > optical microscope, or even better, a SEM. I'll  see if I can find pictures
> > from my old reports.
> >
> > By the way, Dave, I have not forgotten your question about the Metal
> > Institute report. They have changed business and this antique report has to
> > be looked for in the deepest cellars.
> >
> > Inge
> >
> >   On 29 February 2012 15:53, Victor Hernandez <[log in to unmask]
> > > wrote:
> >
> >> Fellow TechNetters;
> >>
> >>   Do No Clean LF fluxes, Rosin Core/molten solder, have a corrosive ion?
> >>   Every so often when conducting analysis on Field Return Product I notice
> >> small amount of corrosion product on gold plated contact on DIMM and PCI
> >> Slot connector.   Sometimes on other gold plated connector leads.   So I am
> >> trying to understand which component had a corrosive ion waiting for the
> >> right conditions to flourish.   Small amount of greenish/bluish residue.
> >> It can be seen on wipe zone and/or stamp edge of contact.   Where is this
> >> active corrosive ion coming from?
> >>
> >>   Can someone provide the link to Stevezea home page for posting pictures?
> >>
> >> Victor,
> >>
> >>
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