Capacitor aging questions, should i Replace this MLCC to another type?

[alexg]

Hi All, simple practical question:
I have a simplest circuit in which I feel mic output into opamp and then into microcontroller to sample output with ADC
the schematic for mic part is as simple as this example, except my capacitor and resistor value is different.

I chose the capacitor to be ceramic, package size 0402 to keep it small and everything works just fine, however because that capacitor and opamp resistors form a high pass filter I chose capacitor value to be very specific - 9nF, (X5R type)
I read that ceramic capacitors have aging effect and I have concern that overtime that 9nF capacitance will change and circuit won't operate as desired, however as I said so far everything works just fine.
My question is, should I be concerned about aging effect, will if affect this value much? I know what C0G (NP0) type capacitors do not have aging effect, but unfortunately for me they start at 0805 and I wanted to keep things as small as possible so I am trying to avoid that, however I can go for 0805 if absolutely necessary. What would you recommend?

Thanks.

[Jwillis]

I have tested ceramics from the 1930s and all come within spec.So I would say no you don't need to worry about aging effect.Really old electrolytics and really old wax yes.They do dry out.

[alexg]

I have tested ceramics from the 1930s and all come within spec.So I would say no you don't need to worry about aging effect.Really old electrolytics and really old wax yes.They do dry out.

Thank you for reply, for last day I been studying variety of capacitors that are available to order and it seems that X7R have a bit better aging characteristics comparing to X5R plus I am ordering "high reliability" series from TDK so that should provide some peace of mind.

[ovnr]

I really wouldn't worry about aging, especially for this sort of application with no self-heating or losses. A DC/DC going full tilt with multiple amps of ripple current, sitting at 80-90 deg C 24/7? Might be iffy. This is pretty much as far as you can get from that.

Also, you can get 0603 C0G/NP0 caps up to 18n. You don't have to jump straight to an 0805.