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

Poulet P. (poulet@fax.ussj.ricoh.com)
Tue, 25 May 1999 11:02:16 -0700

Keith,

I recommend a good book I consult very often especially during the design phase, but I think could be useful at any phase of a project. It has a complete chapter about Capacitors talking about the different types their main
application, parameters, manufacturers, etc.. (even Unit cost)..

Book is:

The Circuit Designer's Companion
by Tim Williams
Publisher: Butterworth-Heinemann (Sd)

(B&N price $33)

Have a nice day.

"Kowal, Keith" wrote:

> 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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--
Philippe Poulet
Hardware Engineer
RICOH Corp
2071 Concourse Dr
San Jose CA95131-1817
Ph: (408) 944-3347
Fax: (408) 434-5390

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