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Subject:
From:
John Burke <[log in to unmask]>
Reply To:
TechNet E-Mail Forum <[log in to unmask]>, [log in to unmask]
Date:
Thu, 21 Dec 2017 21:49:22 +0000
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text/plain
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		If that is ENIG you probably either have a severe case of hyper corroded nickel (black pad) or skip plating where there is no nickel under the gold usually caused by inadequate tin stripping of the via holes connected to the BGA pads “poisoning” the nickel plating process.
		

		Sent from my iPad Pro
	





On Thu, Dec 21, 2017 at 1:44 PM -0800, "Guy Ramsey" <[log in to unmask]> wrote:










ENIG

On Thu, Dec 21, 2017 at 2:56 PM, David Hillman <
[log in to unmask]> wrote:

> Hi Steve - do you know what original board finish was used? ENIG? ImAg?
> ImSn?
>
> Dave Hillman
> Rockwell Collins
> [log in to unmask]
>
> On Thu, Dec 21, 2017 at 1:39 PM, Steve Gregory  wrote:
>
> > Hi all,
> >
> > I've been asked to post this to the Technet by a dear friend:
> >
> > *We installed this little processor. At test we identified opens on the
> > device. When we removed it we saw a number of pads that were matte gray
> > with no evidence of solder adhered to the pad. *
> > *We attempted to bump the pads with solder, they did not wet easily. In
> > some cases we had to scrape through the matte finish to a shiny metal.
> > But, we did get all the pads to appear wetted.*
> >
> > *We cleaned the site well and then fluxed the bumps with a tacky flux
> ROLO
> > designed for POP, placed the BGA and reflowed it on a rework station.*
> >
> > *The assembly failed test with similar result, opens under the
> processor.*
> >
> > *The attached photo shows that the bump process only appeared to wet the
> > pads. The condition returned when we removed the BGA  second time.*
> >
> > * http://stevezeva.homestead.com/2017-12-21_11.21.17.jpg
> > *
> >
> > *Have you seen this before? Is there any recovery? This assembly is worth
> > about $45K. *
> >
> > Thanks,
> >
> > Steve
> >
> > --
> > Steve Gregory
> > Kimco Design and Manufacturing
> > Process Engineer
> > (208) 322-0500 Ext. -3133
> >
> > --
> >
> >
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