W
Winfield Hill
Guest
Does anybody have any suggestions for good sources for small
1 or 2kV surface-mount capacitors?
--
Thanks,
- Win
1 or 2kV surface-mount capacitors?
--
Thanks,
- Win
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Greg Neff
Guest
On 7 May 2005 03:49:11 -0700, Winfield Hill
<hill_a@t_rowland-dotties-harvard-dot.s-edu> wrote:
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.
http://www.johansondielectrics.com/
================================
Greg Neff
VP Engineering
*Microsym* Computers Inc.
greg@guesswhichwordgoeshere.com
<hill_a@t_rowland-dotties-harvard-dot.s-edu> wrote:
Define small. 1KV and 2KV ceramic chip capacitors are readilyDoes anybody have any suggestions for good sources for small
1 or 2kV surface-mount capacitors?
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.
http://www.johansondielectrics.com/
================================
Greg Neff
VP Engineering
*Microsym* Computers Inc.
greg@guesswhichwordgoeshere.com
B
Boris Mohar
Guest
On 7 May 2005 03:49:11 -0700, Winfield Hill
<hill_a@t_rowland-dotties-harvard-dot.s-edu> wrote:
Murata http://www.murata.com/
Regards,
Boris Mohar
Got Knock? - see:
Viatrack Printed Circuit Designs (among other things) http://www.viatrack.ca
<hill_a@t_rowland-dotties-harvard-dot.s-edu> wrote:
Novacap http://www.novacap.com/Does anybody have any suggestions for good sources for small
1 or 2kV surface-mount capacitors?
Murata http://www.murata.com/
Regards,
Boris Mohar
Got Knock? - see:
Viatrack Printed Circuit Designs (among other things) http://www.viatrack.ca
K
Ken Smith
Guest
In article <d5i6f701mle@drn.newsguy.com>,
Winfield Hill <hill_a@t_rowland-dotties-harvard-dot.s-edu> wrote:
I think Venkel is the best source for small quantities of high voltage
capacitors.
--
--
kensmith@rahul.net forging knowledge
Winfield Hill <hill_a@t_rowland-dotties-harvard-dot.s-edu> wrote:
I think Digikey has 100pF in 1 or 2KV.Does anybody have any suggestions for good sources for small
1 or 2kV surface-mount capacitors?
I think Venkel is the best source for small quantities of high voltage
capacitors.
--
--
kensmith@rahul.net forging knowledge
H
Hal Murray
Guest
From Novacap http://www.novacap.com/
* 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.
* 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.
G
Greg Neff
Guest
On Sat, 07 May 2005 23:12:06 -0500, hmurray@suespammers.org (Hal
Murray) wrote:
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.
greg@guesswhichwordgoeshere.com
Murray) wrote:
Good point, but I'm not sure that I like the recommendation of usingFrom Novacap http://www.novacap.com/
* Units rated above 800V may require conformal coating in use to
preclude arcing over the chip surface
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.
greg@guesswhichwordgoeshere.com
W
Winfield Hill
Guest
Greg Neff wrote...
required for surfaces exposed to dust, grime and humidity. Coating
the PCB means that short-but-adequate SMT dimensions aren't exposed.
--
Thanks,
- Win
Yes, of course. I'm sure Hal is referring to the creepage distanceOn Sat, 07 May 2005, Hal Murray wrote:
From Novacap http://www.novacap.com/
* Units rated above 800V may require conformal coating in
use to preclude arcing over the chip surface
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.
required for surfaces exposed to dust, grime and humidity. Coating
the PCB means that short-but-adequate SMT dimensions aren't exposed.
--
Thanks,
- Win
J
Joerg
Guest
Hello Winfield,
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
http://www.analogconsultants.com
There is still some risk of contamination under the chip. The clearanceYes, 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.
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
http://www.analogconsultants.com
G
Greg Neff
Guest
On 8 May 2005 06:16:07 -0700, Winfield Hill
<hill_a@t_rowland-dotties-harvard-dot.s-edu> wrote:
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.
greg@guesswhichwordgoeshere.com
<hill_a@t_rowland-dotties-harvard-dot.s-edu> wrote:
In our applications we coat our boards, but we are still required toGreg Neff wrote...
On Sat, 07 May 2005, Hal Murray wrote:
From Novacap http://www.novacap.com/
* Units rated above 800V may require conformal coating in
use to preclude arcing over the chip surface
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.
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.
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.
greg@guesswhichwordgoeshere.com