RE: [SI-LIST] : Decoupling capacitors (again!)

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From: Dave Hoover (dave_hoover@yahoo.com)
Date: Fri Aug 18 2000 - 17:59:07 PDT


Actually for the ZBC-2000 [TM] material the laminate
suppliers have to hold very tight tolerances.
.002" +/- .0005" with a .0002" std dev process.
The drum sides of the (DT) copper foil facing each
other work well for providing a tighter tolerance
material along with having flat plate (plane)
capacitance.

Dave
--- Michael Khusid <mkhusid@sitaranetworks.com> wrote:
> Barry,
>
> Based on my experience with prepreg vendors, it is
> practically next to
> impossible to define the prepreg thickness. First of
> all, the material is
> not of identicaly thickness, and second, the
> material changes properties
> during the manufacturing process. The story is only
> slightly better with
> cores. Normally, I've seen tolerances up to
> plus/minus 1 mil on the <10 mil
> prepregs.
>
> Another thing, the manufacturer may be the best
> person to know the actual
> thickness of the material after fabrication, and
> that's really what
> designers care about. I would be surprised if any
> material vendor can claim
> after-fabrication thickness accuracy to 0.1 mil,
> that's why I would be
> surprised if any vendors sells different materials
> for 1.8 and 2 mils
> thicknesses.
>
> Mike Khusid
> Sitara Networks
>
>
> > -----Original Message-----
> > From: Barry Ma [mailto:barry_ma@altavista.com]
> > Sent: Thursday, August 17, 2000 2:05 PM
> > To: si-list@silab.eng.sun.com
> > Subject: RE: [SI-LIST] : Decoupling capacitors
> (again!)
> >
> >
> > On Thu, 17 August 2000, Larry Smith wrote:
> >
> > > Zycon (bought by Hadco) got a patent on this
> > > concept. Right now, anybody who uses 2 mil FR4
> between power planes
> > > must consider their legal position with this
> patent. ...
> >
> > ---------
> >
> > How about 2.2 or 1.8 mil?
> >
> > Barry
> >
>
> >
>
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