Are these caps worthy of consideration ?

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They are Z5U, which is the ultimate ceramic doo-doo dielectric. Capacitance varies radically with both temperature and applied voltage. Coupling is definitely out of the question. Bypass, maybe. X&R diecectric will be much more stable and not all that hard to find, but still only for bypass purposes.
What's the application?


I cant think of one that would make this part excel. (that's why ive unused mine, I originally bought them thinking they could clean up SMPS)
so many disadvantages from the start. worst place would be in the feedback path of a high OL gain stage.
hard to beat a 0.1 uF and a small electro. PS bypass.
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With todays digital electronics and the ever increasing signal rise times, PTH capacitors are no use for decoupling, far too much parasitic inductance, SMD small case chip devices are best (ceramic because you can get bigger values in smaller packages X7Rs are the main choice these days) preferably 0201 packages, though 0402's are the most commonly used these days, placed as close to the pins as possible... though planar capacitance from closely space (>0.1mm) power planes is the best option.
That said we are talking best practice for high rise time digital, but the decoupler power loop is critical in all decoupling applications...
If you look at some of the DAC offerings from ebay etc. they have modern DACs and digital ICs in nice small SMD packages then add PTH decoupling capacitor... Not the best rout to optimum signal and EMC integrity.
That said I did highish speed boards in the past when all we had was 0.1" pitch PTH ceramic caps.... But today for digital SMD is your best choice...
Disregarding (for a moment) leads or not,
shouldn't good de-coupling imply good coupling ?
And vice-versa ?

why? PS bypass is generally low impedance high dV/dt and signal coupling / timing most likely isn't. Microphonics due to Hi-K ceramics can be problematic for the latter esp. inside a gain stage. Timing usually requires precise parts under all voltage and temperature conditions can be a major concern with ceramic dielectrics too. use X7R for bypass and NP0 or C0G for coupling / timing. (in Audio) Film caps are usually prefered in coupling/ timing applications due to costs / size constraints of low K ceramic. Hard to beat SMD ceramics in PS bypass. as always smaller lead (terminal) spacing is a concern for high speed (delta t ) signals
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