Kevin,
I see some good stuff already coming across the net so I will try to direct
my answer to just the cracking issue.
High value 0805 caps are very susceptible to thermal shock cracking.
IMHO this can be correlated to device height.
You might try to find a shorter cap (in the Z direction) from a different
manufacturer or in a different dielectric (make sure you get the customer's
OK due to signal integrity issues)
As a rule though I would not recommend wave soldering 0805s larger than 0.01
uF.
Feel free to call if you want to discuss further.
Hope it helps,
FNK


Frank N Kimmey, C.I.D.
Senior PCB Designer
Powerwave Technologies
PH. 916-941-3159
Fax 916-941-3195



-----Original Message-----
From: Kevin Stokes [mailto:[log in to unmask]]
Sent: Thursday, August 16, 2001 1:26 PM
To: [log in to unmask]
Subject: [TN] To wave or not to wave, that is the question...



Old problem: mounting ceramic capacitors to the bottom side of an assembly
and your customer wants you to wave them on.

We are having problems with 0805 0.22 uF and 0.1 uF caps going through wave
and cracking during the process.  We are following all of the standard
protocols (preheat, etc.).  My understanding is that 0805s are typically
capable of handling this process.

Anyone got any ideas short of moving the cap to the top or doing a double
sided reflow?

Kevin

Kevin Stokes
Reliability Manager
Kimball Electronics Group
(812) 634-4207

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