Re: MMC PCB

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "Terry Fritz" <twftesla-at-qwest-dot-net>

Hi Michael,

I would leave at least 1/4 inch between caps.  That will allow for cooling,
explosions, and most importantly, the voltage differences between the caps.
 The thin outer shell of such high voltage caps is not sufficient to
insulate the internal plates from a grounded object sitting next to the
cap.  You need some air space to act as the insulations between caps.  It
gets into how voltages divide across dielectric layers and all that, but
1/4 inch between caps in a string is fine.

The spacing from string to string needs to be pretty large like 1 inch or
more.  If a string is not used, there can easily be surface arcs between
used and unused strings.

Cheers,

	Terry

At 01:10 PM 8/13/2001 +0700, you wrote:
>I wish to thank everyone for their very helpful responses.
>Since we have an in-house PCB facility (design and build
>a few hundred PCBs every year) the cost and resources
>was not an issue.  One other question, should the resistors
>be mounted on opposite side of the board as the caps?  Also
>how much clearance between the components and the PCB
>should I make (for cooling purposes)?
>
>
>----- Original Message -----
>From: "Tesla list" <tesla-at-pupman-dot-com>
>To: <tesla-at-pupman-dot-com>
>Sent: Monday, August 13, 2001 5:27 AM
>Subject: Re: MMC PCB
>
>
>> Original poster: "Malcolm Watts by way of Terry Fritz
><twftesla-at-qwest-dot-net>" <m.j.watts-at-massey.ac.nz>
>>
>> On 10 Aug 2001, at 6:57, Tesla list wrote:
>>
>> > Original poster: "Michael Rhodes by way of Terry Fritz
>> <twftesla-at-qwest-dot-net>" <rhodes-at-fnrf.science.cmu.ac.th>
>> >
>> > I am laying out a printed circuit board (standard G10-Epoxy) for
>> > my MMC array.  I realize the traces have to be heavy enough
>> > for the high pulse currents but short enough to minimize inductance.
>> > Are there any 'gotchas' going this route such as high voltage
>> > breakdown of the PCB, etc?  Anyone else build an MMC this
>> > way?
>>
>> Yes. It works well. Make the traces as wide as possible while
>> maintaining a safe clearance between tracks that are at different
>> voltages.
>>
>> Malcolm
>>
>>
>>
>