Dear Alexis Meehan,

Phil Dutton and Joe Hurst say good things.

I try to keep my component clearance much larger (0.15 inch from edge of screw
head for small components; more for taller componensts) than the minimum
distance so that when the screwdriver slips off the screw and I bang it into the
board, I don't crush any components. (It doesn't hurt to scuff traces with the
screwdriver, so I run traces right up to that minimum distance).

I used to insist that screw holes be *not* plated, to avoid plugging up the
holes during wave soldering. But it doesn't matter with reflow boards.

I suppose if I were using large enough washers, I wouldn't have to worry about
it -- the screwdriver would slip off the screw and bang into the washer. But I
am not using any washers. (the copper annular ring I draw under the screw head
seems more than adequate to keep it from chewing into the board).

--
David Cary

Alexis Meehan:

...
I am looking for the IPC recommended clearance of components/traces/vias to
mounting holes with screws.
I can't find it in IPC-2221; does someone out there know where it is? Thanks
in advance for any guidance.

********************
Alexis Meehan
PCB CAD Mgr.
408-328-4595
[log in to unmask]
LuxN, Inc.
...
http://www.LuxN.com <http://www.luxn.com/>