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Date: | Mon, 09 Jun 97 14:42:00 GMT |
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We are facing acute problem on blowing off caps . Specifically, these caps
are tantulam caps with high capacitance range of 220 MICROFARADS , rated at
10 voltage and tolerance in capacitance value is 20%.We have tried more than
one vendor: one vendor was worse than the present one--however failures are
always there.
These caps are processed ( assembled) alongwith other tantulum caps and
usually go through two heat cycles: first one on gluecure and second one
at wave. The standards (temp profiles) followed at reflow and wave are as
per process guidelines .
These caps when tested after wave pass 100% at 5v test. Fails 20 to 25% for
voltages above 7v . Dwell between wave and ATE does not matter much. Tried
with and without wash -- it does not make significant difference.
It is expected that the cap should pass 100% at rated voltage. Clearly there
is deterioration after assembly process. we ran DOE and observed caps
failing after wave. however our wave process does not seem to out of
control.
any one having experience on such a behaviour of Tantulum Caps -- we will
appreciate your technical advise on this problem as we are running out of
ideas and thinking to change process to bypass wave solder operation
altogether.But that is not easy to do in short time.
Please send your advise on this mail or email directly to me.
[log in to unmask]
Tel: 204-257-9199
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