We had a big bang problem with SMT tantalum caps let me tell
you about it. The application of the tant was bottom side assy
which went through a wave solder. Normal process of 260deg C
the dwell times were fine and all that. It is a no clean process so
aqueous cleaning was not an issue. During our Gen Rad testing
the tants were Bang-ing. Why? So we beat up the manufacturer.
Isn't that always the thing to do? Well what we found out-during my
visit to the vendor was this. Tantalums hate thermal shock. When
we explained our process the vendor said, "Oh I see. So you don't
believe in pre-heat before subjecting these tiny little parts to a temp
of 500degsF!!!
We changed our process to a moderate pre-heat and ba-da-bing,
No more failures. I'd say check your process.
Don Fumia
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