SparkFun Forums

[roach]

I need to create some holes/vias for mount points on a PCB I'm working on. I'd like to mount the board to some sort of base (metal or wood) with some hex standoffs or something, but I really ahve no idea what drill size I should use for the holes, or how much copper trace I need around them. Ideally, I'd like to isolate these holes from the ground plane. Can anyone help me out with some dimensions?

[Philba]

It's pretty much up to you. I use 4-40 screws (er, bolts) but you can use smaller. 4-40 needs a bit less than 1/8" so I use 125 mil as my drill. I use them because they are readily available at HW stores. You might want to go up to the next available drill size for #4 screws to allow for more relaxed tolerances.

Eagle's default leaves enough room though you might want a copper ring so you can use the screw to ground to the case. I don't bother with the hex standoffs but they are nice. I just get nylon spacers from home depot. You can get nylon bolts/nuts, too, if you want.

Here's a table of drill/screw sizes: http://www.csgnetwork.com/screwnummachtable.html

Phil

[leon_heller]

I generally use 3 mm mounting holes. Most mounting hardware like pillars and spacers have 3 mm threads.

Leon