Have been soldering like that for years, all seems to be about soldering profile (underlined!!), pad size, solder amount, board warpage and CTE matching. And, finally, length x width x thickness of cercaps seems to be key to successable soldering as well as direction of caps vs long/short sides of the board. Ain't quite straight that way, but doable. We soldermount lots of cercaps, even 2225, without cracks (at least I hope so...)
I assume you have already been reading AVX internet pages in the matter, lot's of recipes to make best ceramic pie..
Ingemar Hernefjord
Ericsson Microwave Systems
-----Original Message-----
From: Kasprzak, Bill (sys) USX [mailto:[log in to unmask]]
Sent: den 18 juni 2002 16:30
To: [log in to unmask]
Subject: [TN] Wavesoldering Ceramic Caps
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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