Werner,
What we are possibly missing here is that they are soldering the
metalized bottom of the component as well as the leads. If the geometry
is not correct the large center pad will inhibit the leads to self-align
with their corresponding pads. This is/was a problem with D-Packs.
This center pad could be chassis ground, current node or thermal pad.
There are scenarios where this is really not needed or is over-kill and
we have designed this out in many areas. Soldering is much simpler now.
If it is still needed, one would question why bonding is required now
that you have the additional strength of the large soldered area. If it
is for alignment; see paragraph one.
Dewey

-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Werner Engelmaier
Sent: Monday, July 02, 2007 11:56 AM
To: [log in to unmask]
Subject: Re: [TN] When to epoxy heavy components

Hi Karen,
You did not give us a PCB material nor the size of the LLCCC. Your
biggest 
problem will be solder joint reliability, if, as I suspect, you use an
FR-4 PCB.
The global thermal expansion mismatch between the ceramic CC and the
FR-4 
will cause SJ creep-fatigue faulure. There is a long history on this.
To help you specifically with both the manufacturing and long-term 
reliability problem, I need more details.

Werner 


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