I’ve been working with electronics and PCB design for my research for some time now, and the DC bias effect on (most?) multi-layer ceramic capacitors (MLCCs) is one of the newest details I’ve come across that warrants a post so I don’t forget about it.
Effectively, due to the nature of some of the dielectric material used in MLCCs, the actual capacitance of an MLCC exposed to some DC bias can be much lower than the rated capacitance.1 The strength of the effect is correlated to the size of the MLCC package, and is independent of the rated voltage of the MLCC.2
Not all dielectric materials are affected, however. MLCCs with C0G dielectric are unaffected, but these are fairly large for their capacitance (and expensive). X5R and X7R dielectrics are affected, and from what I understand it has to do with some ferroelectric effect due to the titanium in their compound.
To drive home the point, I found this really good 12 year old article from Maxim Integrated (now part of Analog Devices). In it, it has this nifty table:
Of particular note, notice how the 0603 X5R loses more than 50% of its rated capacitance with a DC bias voltage of just under 5 volts!
From what I can gather, some manufacturers have simulations on their product pages showing the DC bias effect on their capacitors, others may included in their datasheets, and others don’t bother. This is just something that needs to be kept in mind while designing with MLCC capacitors.