Aim for large pads with tight fitting holes for
your leads.
The pad/land mass around the holes takes the
full strain exerted from the component leads. With only a thin annular
ring the smallest pressure applied onto a component lead can lift the
pad. As a rough guide multiply the hole diameter by a figure in the
range of 2.5 to 3. If space is at a premium elongating the pads works
well. Larger pads will also help prevent de-lamination should any rework
be required.
Unlike PTH boards it is very important to have
close fitting holes especially on connectors. Dry joints frequently
occur where the solder bridges over the gaps. In certain industries it
is normal to make S/S boards with plated through holes specifically to
eliminate the associated risk.
If larger clearances can be maintained it is often
possible to Silk Screen the etch resist onto single sided circuit boards
as opposed to using the more expensive dry film resists. Which can
lead to a moderate cost saving especially on the larger production
batches.
