Re: [SI-LIST] : 2 mil plane-plane separation

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From: Dave Hoover (dave_hoover@yahoo.com)
Date: Fri Sep 08 2000 - 06:48:20 PDT


Fabrizio,

The .002" dielectric has the copper foil layers
flipped so the drum sides are facing each other.

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Additionally, the dielectric is HiPot tested at
500 VDC to assure there is no imperfections or
manufacturing defects that would cause breakdown
or arcing on actual product. Telecordia (Bellcore)
has tested this and approved it. The laminate
suppliers
who build this (ZBC-2000 [TM]) have submitted samples
into UL and have had them tested. One of the pattern
limits for UL will list this .002" (min) dielectric
if both the material supplier and the PCB fabricator
has submitted samples for eval (recognition) from UL.

Dave Hoover (aka, Groovy)

--- "zanella, fabrizio" <zanella_fabrizio@emc.com>
wrote:
> There have been a few discussions lately about the
> merits of using 2 mils of
> dielectric between a power and ground plane in a PCB
> in order to achieve
> maximum decoupling. Some vendors were mentioned
> which can fabricate pcbs
> with such a small spacing between the planes.
> Assume boards which contain 2 mil plane-plane
> separation get tested at
> voltage and temperature extremes, there could be the
> chance of shorts and
> fires (the UL minimum plane to plane spacing is 3.8
> mils). Can anyone
> comment on this?
>
> Thanks and regards,
>
> Fabrizio Zanella
> Hardware Engineering
> EMC Corporation
> 508-435-2075, x14645
> fzanella@emc.com
>
>
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