October 14, 2010

 

Folks, we have several OEMs who use the subject parts.  The part
manufacturer involved  has designed in four small vent holes in the
middle of the top of the part to allow out-gassing during the
manufacture of the parts (apparently the adhesive used to mount a heat
sink internally to the top of the part can outgas).  There is a
Government issued Alert that indicates that certain cleaning solvents
and/or just plain DI water has been known to enter the parts via the
vent holes and this has caused bypass capacitors inside the FPGA to
corrode.  

 

We are considering mandating that all vent holes be sealed, on a
temporary basis, after the reflow soldering process is completed, but
prior to the cleaning process using Kypton tape or some other acceptable
method.

 

What do folks recommend be done for cases where vented parts must be
used but have not yet been soldered on an assembly?  

Have any vented FPGAs that are known to have corroded internal bypass
capacitors actually caused functional failures in the end-item
equipment?

If folks use liquid masking material, RTV, epoxy or other non solid
substance to seal the vent holes prior to cleaning, is there any concern
if this material actually enters the part via the vent holes?

Is anyone permanently sealing the vent holes?  If so, is this done prior
to or after reflow soldering?  What material and process is used to seal
the holes?

I did find some information via June 2010 historical Technet files on
this subject but want to see if there is any new information out there.

Is there any reliability data available that shows whether moisture
entering the vent holes in fielded equipment will cause failures?


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