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March 2003

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From:
Steve Thomas <[log in to unmask]>
Reply To:
TechNet E-Mail Forum.
Date:
Wed, 19 Mar 2003 13:30:10 -0800
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Jorge, you are on the money from our perspective too....

Adjusting the land pattern to Panasonic's recommendation (different that
the IPC recommendation for those package sizes) solved the tombstoning
problems for us. The "GX" style termination resolved the vast majority of 
our reflow problems. Unfortunately they only implemented that in the smaller
Interestingly enough, a paste change created more problems with the film 
caps than the old stuff, so we went back to the old version.  Now we're 
scurrying to find something else before it's discontinued.

We seemed to better results from a tent profile, for what that's worth.

Regards,

Steve

-----Original Message-----
From: [log in to unmask]
[mailto:[log in to unmask]]
Sent: Wednesday, March 19, 2003 1:12 PM
To: [log in to unmask]
Subject: Re: [TN] Panasonic Film Chip Capacitors and SMT Reflow


Rich,

        Once in a while there is always somebody having problems with these
components. Personally I've ran into problems with Panasonic plastic film
caps a couple of times, the first time almost three years ago. The problems
you are experimenting are very typical, I'd check four things:

1. Make sure the foot print matches what's recommended by Panasonic. These
components are very light weight and tend to tombstone if foot print is not
appropriate.
2. If I remember two to three years ago Panasonic released an  "X"  version
of the component. This is suppose to be improved for SMT operation/Reflow
process. You should look into it, maybe that by itself resolves your
problem.
3. The version "B" of the plastic film caps. seem to have some sort of
contamination on the leads that causes tombstoning. This contamination is
either the dielectric bleeding out or a resin. The bottom line is whatever
Panasonic did, the "X" version seems to solder better.
4. And the last recommendation. I'd implement a soak oven profile, that way
you let the board reach a thermal equilibrium before liquiduos and thus
eliminate/diminish the tombstoning or solder opens. We actually use this
type of profile when we have tombstoning concerns.

Hope this information is useful,

Jorge Rodriguez
Process Engineer
Varian Electronics Manufacturing
E-mail: [log in to unmask]


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