TECHNET Archives

December 2017

TechNet@IPC.ORG

Options: Use Monospaced Font
Show Text Part by Default
Show All Mail Headers

Message: [<< First] [< Prev] [Next >] [Last >>]
Topic: [<< First] [< Prev] [Next >] [Last >>]
Author: [<< First] [< Prev] [Next >] [Last >>]

Print Reply
Subject:
From:
Guy Ramsey <[log in to unmask]>
Reply To:
TechNet E-Mail Forum <[log in to unmask]>, Guy Ramsey <[log in to unmask]>
Date:
Thu, 21 Dec 2017 16:43:37 -0500
Content-Type:
text/plain
Parts/Attachments:
text/plain (83 lines)
It may be. I have seen it before thin enough to be clear but it scraped off
clean. It also left the gold.  I expected if it the gold dissolves we have
a clear path to the nickel below.

On Thu, Dec 21, 2017 at 2:59 PM, Douglas Pauls <
[log in to unmask]> wrote:

> Could it be there was thin residual solder mask on those pads?  Enough to
> interfere with a metallurgical bond forming?
>
>
> Doug Pauls
> Principal Materials and Process Engineer
> Rockwell Collins
>
> On Thu, Dec 21, 2017 at 1:56 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 <[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.
> > >
> >
>

ATOM RSS1 RSS2