Choice of voltage rating ceramics capacitors?

[carpenter]

What should be safe voltage class capacitors in these cases?

1 Ceramic capacitor in snubler over output diode in Two-Switch Forward Power Supply (frequency 66 or 122kHz).


2. Ceramic capacitor in output network RF amplifier class E
C43 as DC blocking capacitor and C44 as filters, Amplifier frequency for examples 15MHz

 

[dick_freebird]

I'd go 2X the DC or pulse-peak worst case voltage for
a fairly benign environment; more if you have abnormal
conditions that expose it to worse. The derating regime
(what's acceptable) varies a lot by application / end use
and who's criticizing the design and components. In the
snubber case realize that the worst case pulse stress
may also be affected by the capacitor's value-drift with
temperature, lower C at the same corner where the basic
cap reliability is least.

 

[carpenter]

In output netvork of E amplifier I designet 100V, but I'm worried.
Unfortunately capacitor must be SMD 1206 or 1210 with high stability i.e. ceramic N0P or silvermica.
Silver mica is best choice with high voltage rating, but have terrible price ( in design have 20pcs capacitor in output networks)
I would therefore like to use ceramic N0P, but for example Farnel have required value (10pF when 150 pF) only in size 1206 and 100V