[SI-LIST] Re: [SI-LIST]: Embedded capacitance on Flex..??

Lee, that is a good point.  But for rigid board applications, C-Ply can be 
had with a compromise Er that still supports 2500V / mil.

Steve.
At 04:38 PM 8/23/2005 -0700, Lee Ritchey wrote:
>Don't forget that ultra thin dielectrics can result in unreliable PCBs due
>to dielectric breakdown.  Gr86 core requires a 4 mil minimum separation
>between planes.
>
>Lee W. Ritchey
>Speeding Edge
>P. O. Box 2194
>Glen Ellen, CA 95442
>Phone- 707-568-3983
>FAX-    707-568-3504
>
>I just used the energy it took to be angry to write some blues.
>Count Basie
>
>
> > [Original Message]
> > From: steve weir <weirsi@xxxxxxxxxx>
> > To: <Larry.Smith@xxxxxxx>; <ray.anderson@xxxxxxxxxx>
> > Cc: <adsurevv@xxxxxxxxx>; <si-list@xxxxxxxxxxxxx>
> > Date: 8/23/2005 4:30:46 PM
> > Subject: [SI-LIST] Re: [SI-LIST]: Embedded capacitance on Flex..??
> >
> > Larry, DuPont and 3M both have thin dielectric with elevated Ers that is
> > nice stuff.
> >
> > Some caution is warranted though depending on the specific
> > application.  High Er material can do good things as you said.  For a
>given
> > skin and dielectric loss, the peak magnitude of the parallel resonant
>peak
> > falls approximately as the inverse square root of Er.  It tends to be
>even
> > better than that as higher dielectric loss pulls down the peak as
> > well.  But there are some potential rocks in that stream:
> >
> > 1. Reduced board modal resonant frequencies, good for damping,
>potentially
> > bad if too low
> > 2. Reduced board to discrete capacitor parallel resonant frequency.  Can
>be
> > a good or bad thing.  Introduces more variables to discrete bypass design.
> > 3. Increased risk of quarter wave resonance within power delivery band
> > between discrete caps and IC die.
> > 4. Much higher material cost.
> >
> > Best Regards,
> >
> >
> > Steve.
> > At 01:24 PM 8/23/2005 -0700, Larry Smith wrote:
> > >Virendra - I believe that Dupont has some thin, flexible dielectric
> > >that can be loaded with ceramic to bump up the dielectric constant.
> > >
> > >We have found that the best value comes from thin dielectric because
> > >it both reduces inductance and increases capacitance resulting in
> > >lower impedance.  The lower power plane impedance produces more
> > >damping, which is a good for reducing power plane resonances.
> > >
> > >By increasing the dielectric constant alone (no dimensional changes)
> > >the capacitance per square area is increased but it turns out that the
> > >capacitance available to a power consumer with in a given time frame
> > >(i.e. 1 nSec) is the same.  This is because the velocity of
> > >electromagnetic propagation goes down with increasing dielectric.  The
> > >cylindrical wavefront that goes out from a disturbance "uncovers" the
> > >same amount of capacitance per time, independent of the dielectric
> > >constant.
> > >
> > >So if you are looking for high frequency capacitance to satisfy those
> > >fast edges, thin dielectric is good, high dielectric constant is
> > >neutral.
> > >
> > >regards,
> > >Larry Smith
> > >Sun Microsystems
> > >
> > >Ray Anderson wrote:
> > > >
> > > > Typically the way I've seen it done in the past is to use a very thin
> > > > dielectric material (~2 mil thick) to achieve the higher than usual
> > > > capacitance.
> > > >
> > > > Most hi-k materials are loaded with some sort of ceramic material
>which
> > > > tends to make them somewhat less than flexible which could be an issue
> > > > with a flex board.
> > > >
> > > > Note that the materials people are always developing new and
>innovative
> > > > solutions, so what was true a couple of years ago when I looked at the
> > > > issue may no longer be the case.
> > > >
> > > > -Ray
> > > >
> > > > -----Original Message-----
> > > > From: si-list-bounce@xxxxxxxxxxxxx
>[mailto:si-list-bounce@xxxxxxxxxxxxx]
> > > > On Behalf Of Virendra
> > > > Sent: Tuesday, August 23, 2005 12:11 PM
> > > > To: si-list@xxxxxxxxxxxxx
> > > > Subject: [SI-LIST] [SI-LIST]: Embedded capacitance on Flex..??
> > > >
> > > > Hello All,
> > > > Does anyone have experience with embedded capacitance
> > > > (wih high K) on a flex circuit board? If yes, are
> > > > there any issues with bending the part of the flex
> > > > with the high k material..?
> > > >
> > > > thanks in advance,
> > > >
> > > > virendra
> > > >
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