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 <[log in to unmask]> 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
> <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
>
> --
>
>
> This email and any attachments are only for use by the intended
> recipient(s) and may contain legally privileged, confidential, proprietary
> or otherwise private information. Any unauthorized use, reproduction,
> dissemination, distribution or other disclosure of the contents of this
> e-mail or its attachments is strictly prohibited. If you have received this
> email in error, please notify the sender immediately and delete the
> original.
>