SparkFun Forums

[MCPorche]

I'm creating a custom footprint in Eagle, and I've got a question.

The recommended footprint is for holes that are 0.92 +/- 0/08mm in diameter. So, I want to make my holes a hair over 1mm (I was thinking 1.2mm). But, I also know that when the holes are plated, that will decrease the size.

So, my question is, in order to end up with a 1.2mm hole after plating, what size drill should I specify in my Eagle file?

[Ross Robotics]

0.92 +/- 0/08mm in diameter. So, I want to make my holes a hair over 1mm (I was thinking 1.2mm).

1.2mm is way too large.. 0.92mm +/- 0.08mm is 0.94mm - 1.0mm.. The plating is not going to be 0.2mm thick.. You haven't told us what the hole is for. This info would tell us whether the hole should be plated or not. Even if it needs to be plated, the board house could tell you the hole plating thickness, which would change depending on the board's copper thickness you specify.

[MCPorche]

The hole is for pins on a USB connector. I figured since it "could" be as big as 1.0mm, I'd need to make it a little bigger just in case the drill was a tad undersized (I'd hate for the 1.0mm drill to be .98, and my pin to actually be 1.0).

Just for clarification..when I typed 1.2, I meant 1.02.

[Ross Robotics]

Just for clarification..when I typed 1.2, I meant 1.02.

Just for clarification, you typed in 1.2 twice.

The hole is for pins on a USB connector.

And which connector would that be? Is it one of the reinforcement pins? It doesn't matter if the pin is smaller than a plated hole. It's going to get soldered anyway.

[MCPorche]

Just for clarification, you typed in 1.2 twice

Yes, I know. I did the same thing in another forum.

And which connector would that be? Is it one of the reinforcement pins? It doesn't matter if the pin is smaller than a plated hole. It's going to get soldered anyway.

No, it's for the 8 data pins on a stacked, double usb-A connector.

[InactiveUser001]

In general:
Always specify your drill sizes in mm and 0.05mm increments only.
Do not use something like a 1.02mm or 0.83mm as the next increment of 0.05mm up will be used instead.

When you specify the drill size, you specify the finished size - the board manufacturers will increase this by 0.1mm for the plating, if you specify 1.2mm because you want 1.1mm plated then your likely to end up with 1.2mm including the plating.

If you make a drill\manufacturing drawing - on it identify that your drill sizes are finished size.

[MCPorche]

Thanks for all of the info, guys.

[delmoresky]

Generally,CAM engineers will enlarge all your hole size when they create production file. You just need to make your holes to 1 mm and tell the manufacture to ensure finished hole size is 1 mm.They know how to deal with it.