Michael said:
Greetings dudes and dudettes of the SED:
I feel like I've seen various PCB standoffs over the years that you
could solder on to a PCB. Heck - I feel like I have even seen some
surface mount ones. Anybody know where I can find these buggers?
What you're looking for might be a hex or round standoff. The brass
ones are solderable. Most are nickel plated and solderable. Be
careful not to get something where the plating can't be soldered such
as cadmium plated. See:
<
http://www.keyelco.com/products/sprod09.asp?CategoryID=11>
Also,
do you think using a surface mount one would be completely insane?
Of course it's insane. All good ideas are deemed insane until proven
otherwise. Just assume that it's an insane idea and blunder onwards.
You'll be yelled at by production at the appropriate time if you need
confirmation of insanity.
(I'd be somewhat scared about it ripping up nearby traces if it was
tugged on too hard)
No, that won't be the problem if you use a through hole and a screw to
maintain mechanical integrity. For small tin boards, something like a
2-56 thread might be appropriate. If you're relying on the copper
ground plane to support the standoffs, it can be done. However, the
last time I did that, I had to use 2-oz copper on 0.062" G10/FR4 (due
to high currents). The much thinner 0.5-oz copper on 0.032 board
would never have worked, so we used screws and plastic spacers for
those.
You may also have a problem soldering it without destroying the board.
If you use a vapor reflow or IR heating to solder the surface mount
board, the large mass of the standoff will absorb enough heat to burn
the board. If not burned, it will warp it due to uneven cooling. It
may also be too big to handle, too close to the edge to clamp, and too
difficult to rework (if soldering fails). However, if you install the
standoffs as a post soldering operation, you could probably control
the heating and simplify the fixturing effectively.
Is there some reason you need to solder the standoff to the board?
Wouldn't a small screw do just as well? If you're worried about
breakage, don't put the hole too close to the edge, use washers, and
assemble it in a fixture.