Re: [SI-LIST] : Capacitance in a Ceramic changes ?i usedf

rbmccammon@mmm.com
Tue, 25 May 1999 10:22:32 -0500

It appears that you are using a Z5U ceramic. This dielectric is not
regarded as stable or even semi stable. Most folks use them only
for bypass.

- - - - - Original Message Date 05/25/99 06:40:41 AM - - - - -

Recently I experienced a SMT chip cap (0.047uf - 1206package) change from
a nominal capacitance that was within spec to a much larger capacitance
once 3 or more seconds of soldering iron heat was applied to the component.
Once it cooled down, I measured it again and to my dismay it measured
0.062uf
and 1 day later it still measured 0.062uf... This is telling me that
heat
changed
the value of the capacitance. My question to the group is this a bad
component
or is this typical - I tried other similar caps and some held to their
spec'd capacitance.
I did a statistical sample and not all 100 caps did this, although 92 out
of
the 100
went out of spec. (grm42-6z5u473m050 /// this was the part number that
gave
me the trouble).

any ideas?

Keith

* Outside 978-684-1574
* Internet: Kowal@ctron.com
* Fax: 978-684-1610

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