1kV smt capacitors

Define small. 1KV and 2KV ceramic chip capacitors are readily available from several manufacturers. Johanson Dielectrics springs to mind. They make 1KV rated caps down to 0805, but I would be careful about the spacing between the leads and pads.

================================

Greg Neff VP Engineering

*Microsym* Computers Inc. snipped-for-privacy@guesswhichwordgoeshere.com

Novacap

Murata

Regards,

Boris Mohar

Got Knock? - see: Viatrack Printed Circuit Designs (among other things)

I have used (and still use)

I think Digikey has 100pF in 1 or 2KV.

I think Venkel is the best source for small quantities of high voltage capacitors.

--
--
kensmith@rahul.net   forging knowledge

From Novacap

* Units rated above 800V may require conformal coating in use to preclude arcing over the chip surface

-- The suespammers.org mail server is located in California. So are all my other mailboxes. Please do not send unsolicited bulk e-mail or unsolicited commercial e-mail to my suespammers.org address or any of my other addresses. These are my opinions, not necessarily my employer's. I hate spam.

Good point, but I'm not sure that I like the recommendation of using coating to prevent creepage. What about *under* the chip between the chip and the PCB? It's hard to ensure that the conformal coating gets in there. This can be verified only by removing the capacitor, which is not practical for routine production inspection. I would make sure that the spacing between the terminations and the spacing between the PCB pads are adequate to provide sufficient creepage distance, without counting on coating for insulation.

================================

Greg Neff VP Engineering

*Microsym* Computers Inc. snipped-for-privacy@guesswhichwordgoeshere.com

Yes, of course. I'm sure Hal is referring to the creepage distance required for surfaces exposed to dust, grime and humidity. Coating the PCB means that short-but-adequate SMT dimensions aren't exposed.

--
 Thanks,
    - Win

Hello Winfield,

There is still some risk of contamination under the chip. The clearance is so small that even a thorough washing process can't guarantee cleanliness.

These HV chip caps are often not at all employed as surface mount. The ones I used were mostly in >100MHz filter stages. Others in high pass filters at the end of large power amplifiers where there will be several hundred volts of amplitude. There they are soldered in place "in the air", usually from a stripline or wire directly onto the wall. The distance between stripline or wire and cavity wall is calculated so it is equal to the length of the selected capacitors. Then the whole thing either gets sealed or potted.

Regards, Joerg

In our applications we coat our boards, but we are still required to assume that the boards are uncoated when calculating creepage distances. Some customers will allow smaller creepage distances when the boards are coated, but many will not.

================================

Greg Neff VP Engineering

*Microsym* Computers Inc. snipped-for-privacy@guesswhichwordgoeshere.com