[PEDA] imperial or metric, mounting without pads

[Dennis Saputelli]

there are other ways to keep a track from coming too close,
such as keep out arcs bound into a mounting hole component or a design
clearance rule based on the pad/hole

the trouble with having a big pad and through plating is twofold:

i have seen the thru plate barrels shed metal or rip out on occasion,
and assuming the boards are wave soldered at some stage the holes need
to be plugged or masked to keep from filling with solder

for these reasons i generally spec mounting holes as NTP and i make a
big clearance for the solder mask so that the lock washer does not tear
the solder mask

of course sometimes you do need to ground a mounting hole so these
comments would not apply in that case


Dennis Saputelli


_______________________________________________________________________
CONTACT INFORMATION:
_______________________________________________________________________
Integrated Controls, Inc.           Tel: 415-647-0480  EXT 107
2851 21st Street                    Fax: 415-647-3003
San Francisco, CA 94110             www.integratedcontrolsinc.com
_______________________________________________________________________
NOTE! TO PASS OUR SPAM FILTER PUT THE FOLLOWING IN SUBJECT LINE: I.C.I.


Peter Bennett wrote:
> Bevan Weiss wrote:
> 
> 
> I prefer to set the pad size for mounting holes to match the diameter of the
> screw head or other hardware - this ensures that I can't put a track under the
> screw head, where it might get damaged, or shorted to ground. (And, with a pad
> size of zero, Protel may allow you to place a track _across_ the hole, which
> wouldn't be good...)
> 
>