Let's suppose the caps are Pb-free. And has been pointed out as a
possibility, suppose they heat up faster (or to a higher temperature) than the
pcb. Is it possible that the alloy created has a higher melting point than
the oven profile is set up for? If all of that happened, maybe the solder
would cling to the part and refuse to flow back down to the board as the
reflow profile progressed. In that case, either raising or lowering the
temperature might just fix the issue (as would the previous suggestion by Ioan
of dropping the top-side temperature). I presume that if you add a little
solder paste and rework these parts that they work fine. Is that correct?
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Reuven Rokah
Sent: Monday, June 02, 2014 3:30 PM
To: [log in to unmask]
Subject: Re: [TN] Capacitor - strange soldering behavior
Hi Gil,
It seems a component plating failure.
Try to check what is the difference between this capacitor and other one with
good performance.
It seems your problematic cap. have grainy structure plating which that suck
the solder during the solder joint.
Try to work with 220 deg C.
On Mon, Jun 2, 2014 at 6:12 PM, Zilber Gil <[log in to unmask]> wrote:
> XRF was done on a new part before reflow. Before reflow the surface
> was shine. After reflow it was grayed and porous as seen in the picture.
> Thanks,
>
> Gil
>
> -----Original Message-----
> From: TechNet [mailto:[log in to unmask]] On Behalf Of Victor Hernandez
> Sent: Monday, June 02, 2014 6:06 PM
> To: [log in to unmask]
> Subject: Re: [TN] Capacitor - strange soldering behavior
>
> Would XRF plating alloy identification work here on a loose part?
>
> Victor,
>
> -----Original Message-----
> From: TechNet [mailto:[log in to unmask]] On Behalf Of David Hillman
> Sent: Monday, June 02, 2014 9:36 AM
> To: [log in to unmask]
> Subject: Re: [TN] Capacitor - strange soldering behavior
>
> Hi Gil - two questions: (1) Does the capacitor have a barrier layer of
> copper or nickel to prevent the underlying metallization from leaching
> into the solder joint?; (2) Have you completed a cross section to
> assess the solder joint microstructure?
>
> Dave Hillman
> Rockwell Collins
> [log in to unmask]
>
>
> On Thu, May 29, 2014 at 9:01 AM, Zilber Gil wrote:
>
> > Hello Technet,
> >
> > While soldering this ceramic capacitor (
> > http://ipc-technet.groupsite.com/gallery/27235), its looks like that
> > the capacitor suck the solder from the PCB`s pad to the capacitor
> > pad and the color is now grayish and porosity. XRF found Sn, Pb, Cu
> > on the capacitor pad. PCB Solderability was good and the profile was
> > SnPb at
> > 225 deg C under Nitrogen. Other capacitors and components on the
> > board look normal with shine soldering.
> > Can anybody seen something like that before? Any ideas?
> >
> > Thanks and have a wonderful weekend.
> >
> > Dr. Gil Zilber
> > Technologist, Elta system Ltd.
> >
> >
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> >
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