Hi Alejandro! Take a look back in the TechNet archives - there was a good
discussion on the pros/cons of Sn62 versus Sn63 solderpaste in terms of
tombstoning a number of weeks ago. Don't discount a pad geometry or
solderability problem as Phil or Daan suggested. We recently completed a
tombstoning investigation in which an 0805 resistor was giving us fits. The
component fabricator believed we had a problem in our reflow profile but
when an alternative component fabricator's capacitor was used the
tombstoning was eliminated. Both component fabricator's were supplying the
same 0805 cap - same dimensions, same termination finish, etc. - but it
turned out that the tombstoning capacitor had enough oxidation of the
termination finish to upset the wetting characteristics during reflow.
Solderability tests did not identify the problem - we had to use Auger
analysis. Good Luck. Time to get a breakfast Coke!

Dave Hillman
Rockwell Collins
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Becerra Alejandro <[log in to unmask]>@ipc.org> on 12/02/2002 07:23:52 PM

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Subject:    [TN] Tombstoning Film Chip Capacitor




Hello to All,

We have had tombstoning in a Film Chip Capacitor (Size 1206).
It is being soldered in a normal reflow process, and this is the only
component that it is showing tombstoning.
Reviewing the specs. of the component in the web I found that this
capacitor is recommended for Wave Soldering.
Does anyone know the difference in construction between the Capacitors for
Reflow and Wave Soldering?
Is it possible that this be cause for the tombstoning?
I am also sending pictures for cross section for the capacitors that we are
using (Recommended for Wave Soldering).
They could be seen at Steve's site.

Regards

Alejandro Becerra
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