that's scary.
On Jul 18, 2018, at 11:48 AM, John Maxwell wrote:

> High dielectric constant ceramic capacitors all exhibit aging due  
> to the crystal structure changing from ferroelectric (tetragonal or  
> diamond) to paraelectric (cubic) structures. Higher the dielectric  
> constant (k) and the thinner the dielectric the more rapidly the  
> parts age or lose capacitance.
>
> John
>
>
> Sent from my iPhone
>
>> On Jul 18, 2018, at 11:10 AM, Guy Ramsey <[log in to unmask]>  
>> wrote:
>>
>> Well, I'll Be.  I cooked them at 150C for an hour and they measure  
>> 100uF
>> I learned something today.
>>
>>> On Wed, Jul 18, 2018 at 8:08 AM <[log in to unmask]> wrote:
>>>
>>> Guy,
>>>
>>> Read this and try putting the parts through their Curie point and  
>>> test
>>> them again.  We have seen this on some parts here.
>>>
>>> https://www.johansondielectrics.com/ceramic-capacitor-aging-made- 
>>> simple
>>>
>>> Drew
>>>
>>> -----Original Message-----
>>> From: TechNet [mailto:[log in to unmask]] On Behalf Of Guy Ramsey
>>> Sent: Wednesday, July 18, 2018 7:00 AM
>>> To: [log in to unmask]
>>> Subject: [TN] capacitor measurement
>>>
>>> I got pulled into a Receiving Inspection problem. Our test  
>>> instrument, an
>>> old HP 4192A impedance meter, and a newer Instek 6020 tell us  
>>> that our X5R
>>> capacitors are out of spec.
>>> A 100uF, 10%, 6.3V capacitor measures between 25% and 30% below the
>>> nominal value.  The instruments have Kelvin probes and are zero  
>>> calibrated
>>> at frequrency, 120Hz the test waveform is 500mV rms.
>>> Does anyone have any advise?
>>>