Ceramic absorts moisture and will likely "POP" during the thermal cycle.
Bake the components ( ceramic cap) prior to wave solder.  Look up IPC or
JDECS standard for recommended time and temperature.





                      "Kasprzak, Bill
                      (sys) USX"               To:       [log in to unmask]
                      <[log in to unmask]        cc:
                      OM>                      Subject:  [TN] Wavesoldering Ceramic Caps
                      Sent by: TechNet
                      <[log in to unmask]>


                      06/18/2002 07:30
                      AM
                      Please respond to
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                      Forum."; Please
                      respond to
                      "Kasprzak, Bill
                      (sys) USX"






Hello gang,

We have a situation where a board design has some 2225 Ceramic Caps on the
bottom side of the board. Most of the advisories I've seen indicates that
wavesoldering these parts is not recommended. From what I can gather,
thermal shock induces micro fractures within the ceramic substrate that
leads to component failure. However, I'm thinking that if I could raise my
normal wave preheat and lower my pot temperature, I could minimize the
thermal shock. I could almost have a thermal profile that would be similar
to reflow soldering. Reflow soldering of these ceramic caps, from what I've
read, is OK. Some of the articles I've read on this cracking phenomenon
were
written in the late 80's, Is there any newer information out there?

Is anyone out there routinely wave soldering these parts that could give me
some pointers?

We use an OA flux with a DI water wash in our process.

As always your help is greatly appreciated.

Bill Kasprzak
Moog Inc. Manufacturing Engineering, Electronics

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