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

John Philips (John.Philips@WhiteCross.com)
Tue, 25 May 1999 14:11:00 +0100

When you hand soldered the component at what temperature did you have the
iron set ? Soldering at high temperatures will damage the dielectric of the
capacitor. Rohm for example only specify 230+/- 5C for soldering their MCH18
series of SMD caps.

John

> -----Original Message-----
> From: owner-si-list@silab.eng.sun.com
> [mailto:owner-si-list@silab.eng.sun.com]On Behalf Of Kowal, Keith
> Sent: 25 May 1999 12:41
> To: 'si-list@silab.eng.sun.com'
> Cc: Kowal, Keith
> Subject: [SI-LIST] : Capacitance in a Ceramic changes ?i usedf
>
>
> 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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