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

Kowal, Keith (kowal@cabletron.com)
Tue, 25 May 1999 10:01:20 -0400

John,
the iron was 750F or so / we used MuRata and Kemet as
vendors... what's stranger yet today we measured the caps and
they, on the average, are about 0.055uf nom. when 2 days ago
the same caps were reading > 0.06uf

keith

> -----Original Message-----
> From: John Philips [SMTP:John.Philips@WhiteCross.com]
> Sent: Tuesday, May 25, 1999 9:11 AM
> To: si-list@silab.eng.sun.com
> Subject: RE: [SI-LIST] : Capacitance in a Ceramic changes ?i usedf
>
> 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
> >
> >
> >
> > **** To unsubscribe from si-list: send e-mail to
> > majordomo@silab.eng.sun.com. In the BODY of message put:
> > UNSUBSCRIBE si-list, for more help, put HELP. si-list archives
> > are accessible at http://www.qsl.net/wb6tpu/si-list ****
> >
> >
>
>
> **** To unsubscribe from si-list: send e-mail to
> majordomo@silab.eng.sun.com. In the BODY of message put: UNSUBSCRIBE
> si-list, for more help, put HELP. si-list archives are accessible at
> http://www.qsl.net/wb6tpu/si-list ****

**** To unsubscribe from si-list: send e-mail to majordomo@silab.eng.sun.com. In the BODY of message put: UNSUBSCRIBE si-list, for more help, put HELP. si-list archives are accessible at http://www.qsl.net/wb6tpu/si-list ****