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I have a board in Kicad that uses a mixture of plated and non-plated through holes. It generates two drill files for these. However, manufacturers seem to expect only a single file. If they don't support NPTH, how can I generate a single file? Can they be safely concatenated?

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  • \$\begingroup\$ I actually changed my mechanical holes to be all plated ones, which gave me a single drill file. I'm still interested in the answer, though. \$\endgroup\$
    – Isvara
    Aug 4, 2013 at 11:48
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    \$\begingroup\$ If you have plated holes, make sure you have at least a small annular ring in the PCB top and bottom layers or the hole plating can peel off in later life and cause swarf that might get into the electronics. \$\endgroup\$
    – Jay M
    Aug 4, 2013 at 11:54
  • \$\begingroup\$ If you like, paste you two files in a pastebin somewhere and I'll merge them in CAMtastic, however absolutely no guarantees. \$\endgroup\$
    – Jay M
    Aug 4, 2013 at 19:25

3 Answers 3

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In KiCad, in the dialog for generating drill files, there is a checkbox "Merge PTH and NPTH holes into one file."

As others have said, it may be only certain fabs (e.g. OSHPark) that require at most one drill file.

Another gotcha is that in the KiCad footprint, in the pad for a NPTH hole, you must insure that the size of the pad is same size as the drill size. (KiCad won't let you specify "None" for copper layers.) Otherwise, 1) KiCad generates copper under and surrounding the hole in the Gerbers, and 2) the fab algorithms will see a thin ring of copper around the hole, and proceed to plate the hole, despite that the type of the pad in KiCad is "NPTH".

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You can't simply concatenate them as they have a structure even though they are text (or are binary files for EIA ones).

It would be very easy to write a simple tool in a language such as Python to merge them, or use a CAM tool which can easily do the same.

A requirement for only one file and no more is very uncommon.

On many occasions I've been asked to produce two (or more) drill files, but the file requirement varies between manufacturers, some want separate PTH and NPTH others don't.

I just send both files and let the manufacturer worry about it. If you mess with it after production and make a mistake it's then your problem, not theirs.

Once they get your data, they do an import using a CAM tool (Computer Aided Manufacture) All CAM tools I've ever used allow you to load more than one drill file.

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  • \$\begingroup\$ I tried that and at OSH Park the non-plated ones didn't drill. That might have been an artifact of their rendering, though. \$\endgroup\$
    – Isvara
    Aug 4, 2013 at 19:08
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The answer from OSH Park, where I ended up going, was this:

I can do both, they just need to be in the same file.

In US manufacturing, any hole with a copper pad gets plated, and any hole without copper on both sides is unplated.

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