The best study I have ever seen on "ground trace vs. air gap" was at a PC
Design conference. Unfortunately I only copied the pages that had actual
data, and that was on pgs 146 and 147 of the proceedings (I think it was
1995, but the pages aren't dated). I can get more info if you can't find a
copy, but to summarize, the results showed that the gap is the critical
factor.

hope you get some better answers <grin>,
Jack

> -----Original Message-----
> From: Pat Paulson [SMTP:[log in to unmask]]
> Sent: Friday, May 15, 1998 5:53 AM
> To:   [log in to unmask]
> Subject:      [DC] Clock lines...
>
> Next question is concerning special considerations for clock signals and
> EMI.  Some of the Engineers want a ground trace surrounding the clock
> lines
> and others say it would be better to just leave the space around the clock
> line that the guard band would normally take up. The clock speeds are 40
> Mhz and below using 6/6 on the inners and 8/8 on the outers.

################################################################
DesignerCouncil E-Mail Forum provided as a free service by IPC using LISTSERV 1.8c
################################################################
To subscribe/unsubscribe, send a message to [log in to unmask] with following text in the body:
To subscribe:   SUBSCRIBE DesignerCouncil <your full name>
To unsubscribe:   SIGNOFF DesignerCouncil 
################################################################
Please visit IPC web site (http://jefry.ipc.org/forum.htm) for additional information.
For technical support contact Hugo Scaramuzza at [log in to unmask] or 847-509-9700 ext.312
################################################################