Gregg, 

What was the baking temperature?

Doug

Gregg Klawson wrote:
> 
> on Thu, 15 Aug 1996 15:10:15 -0400
> [log in to unmask] (Howard Feldmesser) asked :
> 
> >        A vendor recently received back from us a batch of multilayer
> >ceramic chip capacitors that failed their dissipation factor specification.
> >They claimed that the parts were merely aged and put them through a
> >"de-aging" process, apparently a vacuum bakeout.  The parts now meet the
> >spec!  Does anyone have any idea what the process is and what it does?  How
> 
> De-aging of ceramic capacitors is a bake above their Curie point
> temperature.  I've had to bake caps anywhere from 1 to 16 hours to de-age
> them.  No vacuum is involved.
> 
> >long will the parts remain "de-aged?"  What about parts already installed;
> 
> As soon as they are cooled they start the ageing process.  All parts with
> the same dielectric formulation should age similarly.  Your cap vendor
> should be able to give you the ageing characteristics for your parts.  It is
> expressed in % percent per decade, with each decade being a power of 10
> hours.  DC voltage can also accelerate the ageing process (did you do a DWV
> test before you measured DF??).  I'm familar with capacitance ageing
> characteristics, not DF - the dielectric loss decays with time also which I
> take to mean increases(?).  So perhaps DF increases at the same rates as the
> capacitance changes.  Capactitance ageing examples - class I ceramics
> (NPO-COG)  0%/decade; Class II(BX-X7R) -3%/decade, (Z5U) -4%/decade.  YMMV
> 
> >does D increase with age on all parts?  Do you have any citations in the
> 
> C/DF ageing depends on the dielectric used.
> 
> >literature?  Can the de-aging process work on humans?
> 
> Hmmmmm.  There's supposed to be a fountain somewhere for that....
> 
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