RE: [SI-LIST] : Effects of thieving on SI and EMC.....

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From: Chris Padilla (cpad@cisco.com)
Date: Tue Aug 08 2000 - 12:27:07 PDT


Michael,

 From an EMI perspective, I have yet to notice any
measurable difference between "thieved" and "non-
thieved" boards.

We tell our fab vendor to keep the pattern at least
400 mils away from any trace, via, pad, part, etc.

As you point out, thieving increases manufacturability
by minimizing warping of the board.

----->Chris

>A thieving pattern is a bunch of very small shapes
>added to a layer that helps equalize the plating
>across a given layer (increases manufacturability).
>An auto thieving utility or program uses a set of
>criteria to determine how and where to put these
>shapes. Unfortunately these programs are almost
>exclusively focussed on mfg issues and not SI or
>EMC issues.
>
>Usually if you see a bunch of 1/16" width diamonds
>on an artwork layer, this is thieving.
>
>FYI
>
>MG
>
>-----Original Message-----
>From: Ray Anderson [mailto:raymonda@radium.eng.sun.com]
>Sent: Monday, July 31, 2000 11:12 AM
>To: Greim, Michael
>Cc: SI LIST
>Subject: Re: [SI-LIST] : Effects of thieving on SI and EMC.....
>
>
>OK, I'll bite. Educate me, what is a thieving pattern,
>and an auto-thiever ????
>
>
>-Ray
>
>
> > Does anyone out there have a tool or reference
> > that would allow one to calculate the effects of
> > thieving patterns on signal integrity and EMC.
> >
> > I am trying to come up with appropriate rule sets
> > for driving an auto-thiever utility.
> >
> > Thanks for the help.
> >
> > MG
> >
>
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