I'm not an expert, but have just enough knowledge to be dangerous. My understanding of one of the causes of tombstoning is that the solder paste on the leading end of the component turns liquid before the trailing end and the capillary action causes enough force on the component to cause it to tombstone. 

Are all capacitors tombstoning in the same direction? Is it always the same ones, or in the same area? If so, a slight profile change may help.

Blair Hogg
QA Manager
GAI-Tronics Corp.

>>> [log in to unmask] 03/19/03 03:51PM >>>
Good afternoon everyone,

I am currently reviewing a tombstoning problem that we are having with the
capacitors listed below.  We are seeing this problem on two separate
electronic assemblies but only with this component style.  We place 40 caps
per array and approx. 3 - 5 of them tombstone.  Both assemblies go through
the SMT process and they both are using a Panasonic ECH-U1H152JB5 and
ECH-U1C153JB5 film capacitors.  The placement of the capacitors pre-reflow
is centered correctly between the pads.  But of course post reflow -
tombstone!

Any thoughts, ideas, or experiences with this part would be helpful.

Thanks in advance for your help.

Rich Lasko
Badger Electronics

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