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. > > >