[volt-nuts] any unheated Vref better than LT1021-7 (at 7 ppm/khr typ.) ?

[Bob Paddock]

> 2) I have seen mention of dipping a PCB in molten paraffin as a conformal coat. Can anyone say if that is hermetic enough to remove the "typically >100 ppm" drift from relative humidity changes

Such coating may give you a gain over the 1,000 hours you question,
but it may be a detriment for  longer time frames.

As Conformal Coating is not a hermetic seal, what real happens is the
impurities in the water are kept away from the circuit, but the water
itself reaches the traces. Since the water is now fairly devoid of
contaminates the water acts more like a dielectric insulator. You
never notice it in a low impedance digital circuit, but unless
debugging is an obsession don't let it get near a RF tuning circuit, a
high impedance Wireless Sensor Network circuit, or a reference setting
voltage divider.





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