> Afaik, no. What's the use anyway? > This would seem to serve no other purpose than to increase the > impedance of the plane (larger holes = less copper) > Leo
I think you might have thing backwards, or, misunderstoo what I really want to do. For example: With a via drill hole = 15 mil, outer pad = 50 mil. Power plane clearance = 15 mil. Polygon plane clearance = 15 mil, trace size = 10 mil. General PCB gap clearance = 10 mil. On a polygon plane, 2 vias side by side require a distance of 90 mil between them before the polygon plane can make fill between them. 90 mil = ( 25(radius of outer pad) + 15(clearance from pad) + 10(trace size inbetween) + 15(clearance from outer pad) + 25(radius of outer pad)) On a power plane, 2 vias side by side require a distance of 55 mil between them before the polygon plane can make fill between them. 55 mil = ( 7.5(radius of drill hole) + 15(clearance from pad) + 10(trace size inbetween) + 15(clearance from outer pad) + 7.5(radius of drill hole)) The power plane obviously will have a much LOWER impedance if I have a lot ov vias in a regieon closer than 90 mil. Even vias with 90 mil spacing on a power plane will have much thicker copper between the via holes. My goal is to make the Polygon fill emulate the power plane for the lower the impedance, however, if I have trace on a via in the middle of the fill, I would expect Protel to expand the via's outer pad to the via pad size & push away the polygon like the standard polygon fill. Can I somehow make protel do this? I do know that in the gerber generation options, there is an option to ommit pads on unconnected layers, however, the polygon fill ignores the option even if on the gerber, the pad may be missing offering extra room for the polygon to fill in. (Note that I have not seen the option do anything at all. Maybe I missunderstood the meaning of 'ommit pads on unconnected layers') ____________ Brian G. ----- Original Message ----- From: "Leo Potjewijd" <[EMAIL PROTECTED]> To: "Protel EDA Discussion List" <[email protected]> Sent: Wednesday, September 27, 2006 4:53 PM Subject: Re: [PEDA] P99se, Unconnected vias in the middle of a polygon fill. > At 27/09/06 21:05, Brian Guralnick wrote: >> Ok, my last PCB for the first time I used true power planes. I >> noticed >>that unconnected pads/vias on the plane layers had no copper pad to them, >>they were blank hole allowing for the power plane to fill more completely >>where there may be many vias in a cramped space. >> >> Is there a way to setup the PCB design rules so that the polygon >> fills >>create the same effect for the unconnected vias & pads. > > Afaik, no. What's the use anyway? > This would seem to serve no other purpose than to increase the > impedance of the plane (larger holes = less copper) and to increase > the parasitic capacitance between the unconnected vias and the plane, > neither of which is desirable (at least, in my designs). > > Unless, of coarse, you have the planes on the outside of the PCB (and > even then the above still applies). > In which case I would use a polygon with grid = 0.... > > BTW, the gap between the barrel (plated hole) of the via and the > plane is controlled by a rule under manufacturing. Just in case you > missed it.... > > Leo > > > > ____________________________________________________________ > You are subscribed to the PEDA discussion forum > > To Post messages: > mailto:[email protected] > > Unsubscribe and Other Options: > http://techservinc.com/mailman/listinfo/peda_techservinc.com > > Browse or Search Old Archives (2001-2004): > http://www.mail-archive.com/[email protected] > > Browse or Search Current Archives (2004-Current): > http://www.mail-archive.com/[email protected] ____________________________________________________________ You are subscribed to the PEDA discussion forum To Post messages: mailto:[email protected] Unsubscribe and Other Options: http://techservinc.com/mailman/listinfo/peda_techservinc.com Browse or Search Old Archives (2001-2004): http://www.mail-archive.com/[email protected] Browse or Search Current Archives (2004-Current): http://www.mail-archive.com/[email protected]
