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I am new to pcb design, and I am using eagle for this purpose. I am confused by mounting holes and through holes. They are all holes, what's the difference?

In eagle, layer of drills(layer 44) is used for through holes, holes layer(layer 45) is used for mounting holes. am I right?

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I assume, that a mounting hole will not have an electrical connection, where as a through hole, used for components, will. – Tim Mottram Apr 11 '14 at 14:39

When eagle generates Gerbers, holes end up as non-plated holes. For a mounting hole, it's good when it's not plated.

Making non-plated holes requires an additional step in the fabrication process. Some PCB fabs do non-plated holes as a part of their standard service. Some automatically convert non-plated holes into plated holes. Some charge extra for non-plated holes.

screenshot of layout in Eagle

photo of a fabricated PCB with non-plated hole

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Thank you Nick. I know now. – user40237 Apr 16 '14 at 9:13

This may be Eagle-specific terminology for what others call "Plated" and "Non-plated" holes - Consult the Eagle manual for clarification.

Normally, the holes for leads and pins of through-hole components will be plated - they will have a conductive "tube" inside the hole to provide connection between layers.

If you don't want this connection between layers, you have to specify the holes as non-plated. This will require a separate drilling operation, so the board shop will require a second drill file for the the non-plated holes (and will probably charge extra. Having the plated and non-plated holes on separate layers will facilitate making the separate drill files.

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