Thanks Bob,
        I didn't overlook your point, I just didn't think it was necessary
to go into so much detail. The point was simply that for whatever reason the
thru-hole barrel was damaged and no longer effective. Multiple removals and
re-installation definitely adds to the problem.
        For more detail, I would add that it is best of the additional vias
(or small pads) are placed so that they are not under the crown of the
screw. Usually the crown of the screw has a radius so the via may appear to
be partially under the crown but there may be little or no compression on
the via because of this radius. This lessens the possibility that the via
barrels could also become damaged by compression. I thought that this would
also be apparent but since some responder(s) commented about this I thought
I would clarify.

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: Bob Fearon [mailto:[EMAIL PROTECTED]]
> Sent: Tuesday, September 18, 2001 2:39 PM
> To: Protel EDA Forum
> Subject: Re: [PEDA] Pad with multiple holes surrounding it.
> 
> 
> Brad
>     You are correct as usual, but may have overlooked one aspect.
>     If this is a mounting hole(where there can multiple 
> installation and
> removals of the screws),
>     it could break the barrel of the via. Not to bad for a 
> double sided pcb, but
> terrible for a
>     multilayer. If the inner layers are planes connected to 
> different screw
> terminals, scrap the board.
>     I use this a lot on switch mode power supplies.
> 
>     Bob Fearon

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