So far, we have had to resort to having the
Tester/Assemblers physical inspect each item with a tantalum cap, using
the silkscreen as a guide. So far, so good, though we have had a couple
of small fires when the product goes under test. (Not within the last
year though.)
I have not seen any studies, or had problems of any sort
with through-hole versions.
Cobey Schmidt
VisionTek
1175 lakeside Drive
Gurnee, IL 60031
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-----Original Message-----
From: TOSTEVIN_BC
[SMTP:[log in to unmask]]
Sent: Thursday, June 25, 1998 2:31 PM
To: [log in to unmask]
Subject: [TN] tantalum caps
We've been doing some investigative work
into tantalum capacitor
failures. Some portion of the failures has
been traceable to defects
within a vendor's lotcode. Other failures
are undoubtedly caused by
well-meaning, but incorrect hand placement
of missing components.
However, there is a third group of failed
parts, where the capacitor
was installed backwards, but for which no
rework or operator
intervention is indicated in the card's
production history. This
leads to several questions.
1. Is anyone aware of studies or data,
which attempted to determine
a DPM for reversed tantalum capacitors, as
received on the tape & reel
from the component manufacturer? The
vendors would have you believe
that the DPM is zero, but we all know,
nothing is perfect.
2. What are some of the inspection / test
methods, and equipment
that you're using (or not using as the case
may be), to ensure that
these parts are installed correctly on the
final assemblies?
3) What about through-hole caps, where
the polarity markings are
less visible on the side of the part than
on the top of smt caps?
Bruce Tostevin
Benchmark Electronics
Hudson, NH
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