Axial vs Radial Film Capacitor

Question

When using film capacitors for high frequency (100's kHz) applications, is one type better then the other? Historically it seems like axial capacitors were used in audio etc. where frequency characteristics were important. I am assuming that is because axial was just easier to make back then vs now...

For instance, is it better to use a Radial or Axial capacitor for a half bridge? What about decoupling ringing due to high frequency switching? Does one have less internal inductance? Or does it really not matter?

Answer 1

Axial leaded capacitors are generally considered obsolete in this day and age -- their ESL is higher than even radial leaded parts. In other words, if you want high frequency performance, you're best off with a SMT part, with a radial leaded part second by quite a bit, and an axial leaded part a distant third.

The main reason that T/H resistors are still axial leaded is because their internals don't natively fit well into a radial leaded form factor, at least for small-signal power levels. This is unlike the wound construction of a film or wet electrolytic cap, which can be made radial leaded just as easily as it can be made axial leaded.

Answer 2

In many cases radial is the only through-hole package offered in many brands and many styles of film, PU,PET,P,PP.

• When it comes to choice, 1st define your voltage rating, capacitance, cost, tolerance d.f. V/us and ESR, SRF if given, then size, pitch choices.
• In some cases axial parts are very low ESR and very high cost and other cases they are similar
• The best parts are not the shape but rather the material qualities and adequate size, price and tolerance.