Abd ul-Rahman or others,
        if I read his description correctly he is trying to do a plated
mounting hole with additional vias within the diameter of the larger pad for
the plated thru-hole. I am guess that he is trying to make this as a
component for simple re-use.
        The reasoning that I have heard behind doing this is to make the
plated through hole more reliable. The reliability is greater when the screw
may wear away or break the mounting hole plated barrel. The copper top and
bottom is still connected via the plated vias. This is also a common
practice in high freq. microwave applications where ground must be
maintained as ground by repetitive via stitching, every 50 - 100 mils in
some cases.
        I have similar structures in my library but they do not work as
fluidly as I would like so I have waiting for other responses to find out if
there is a better way myself.

Brad Velander,
Lead PCB Designer,
Norsat International Inc.,
#300 - 4401 Still Creek Dr.,
Burnaby, B.C., V5C 6G9.
Tel. (604) 292-9089 direct
Fax (604) 292-9010
website www.norsat.com


> -----Original Message-----
> From: Abd ul-Rahman Lomax [mailto:[EMAIL PROTECTED]]
> Sent: Tuesday, September 18, 2001 3:52 PM
> To: Protel EDA Forum
> Subject: Re: [PEDA] Pad with multiple holes surrounding it.
> 
> 
> At 02:22 PM 9/18/01 -0500, Ted Tontis wrote:
> >I believe he is trying to put supporting holes around the 
> top of the PTH.
> 
> I'd like to know what a "supporting hole" is, since holes 
> remove physical 
> support.
> 
> Holes placed for additional ground connection would be likely 
> to make only 
> a negligible contribution under most circumstances; the pad, 
> if it goes to 
> a ground plane or copper pour, should be made direct-connect 
> unless it is 
> to be soldered. Holes surrounding a central hole going to a plane may 
> remove connection to the inner hole unless they are direct-connect.
> 
> A .125 hole direct-connect to a ground plane is equivalent to a trace 
> almost a half-inch wide for a distance of perhaps 30 mils at most.
> 
<SNIP>
> 
> [EMAIL PROTECTED]
> Abdulrahman Lomax
> Easthampton, Massachusetts USA

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