Minimum Reccomended Through-Hole Pad Size?

[jdupre]

Is there a general rule for the minimum manufacturable pad size on a plated through hole? Also what is the minimum distance that a plated through hole should be placed near the edge of a board?

[ Some connectors I use have plastic registration pins that need a hole. It is my understanding that non-plated holes must be drilled after plating, so it is essentially an extra process that should be omited if possible. Thats why I'm using plated holes on these non-electrical "pins". ]

Thanks,

- Joe

[randychase]

Non plated thru holes are a secondary operation but are sometimes required for tooling holes or mounting holes where a screw might cause problems with a barrel.

With a plastic mounting pin, the only issue is the possibility of the barrel falling out because there is no annular ring to retain it. It probably would not fall out in any case, but a small annular ring of .1mm or .005" on the side would be enough I think.

Note, the cost of the operation to use non-plated holes is pretty minor and is not always passed on to the customer from the board house.

The min distance for me would depend on the technology and requirements. I have had holes right up to the edge of the pcb because I had to. If I can, I try to keep the edge of the pad for a hole at least .5mm or .020 from the edge of the pcb. If you have a lot of room, make it even more. I have seen too many designs with traces close to the edge and they did not need to be.

Mounting holes need more room, as you don't want a small web section.

We have some documentation on the website about general guidelines I think.