On Fri, 10 Jun 2005 05:04:42 +0200, David McNab <
david@...>
wrote:
> Even though I'm using a good drill press, the drilling played havoc with
> the fine pads, and left me with having to either:
If that is the case you definitely have too small pads.
Remember the pads are not only for electrical connection, but also for
mechanical mounting, and nothing is more annoying than a PCB with the pads
lifting off.
You surely understand they must be MUCH bigger in non-PTH boards as the
plating acts like a rivet that holds things together - and still i have
managed to pull PTH padstacks out with improper soldering, so they were
too small too. Most PCB software is set to tiny pads meant for PTH boards.
Make bigger pads, make oblong pads if the spacing doesn't allow more, for
example, for a 100mil pitch DIL IC you can make 4mm long pads which still
look good.
I tend to make bigger pads for components that are either mechanically
large, are connectors, or have many pins. This helps those components that
have the highest stress (e.g. electrolytic caps are often pulled/pushed by
handling of the board because they are higher), And helps the parts that
are hard to desolder.
If you make oblong pads, it is best never to go with the trace into the
pad in the center at right angles to the orientation of the pad. I have
had the fault that drilling did cut the trace free from the rest of the
pad, but it was not visible easily. So always go into one of the ends of
the pads.
ST