Pad with non-plated hole (NPTH)

Layout Footprints
1

Hello everyone! KiCad 4.0.7 Win10.

Is there a proper way to make a pad with NPTH inside of that pad?

I tried to place NPTH directly into the SMD pad, but I can’t assign a pad number to NPTH pad, so when placing such component on the PCB I get a DRC error ErrType(19): Pad near pad.

I’m trying to create a footprint for a rectangular self capacitive button with a hole in the middle for a reverse-mount backlight diode.

2

Can you send a link to the button datasheet?

I think a PTH rectangular pad may work as well.

3

ButtonLED_SelfCapacitiveRect_14x10mm.kicad_mod (818 Bytes)
Hi pedro,
I attached an example. There is no datasheet as it’s custom made capacitive button which simply uses a huge rectangular copper pad (left covered with the soldermask).

A single PTH theoretically will do, but I need to ensure the hole is not plated.

4

Look at this

ButtonLED_SelfCapRect.kicad_mod (735 Bytes)

Well, if the whole pad is covered by soldermask, the hole will also be filled with soldermask.
@1.21Gigawatts is an expert on manufacturing, he could tell us.

I guess you need some metal surface not touching the button, since with the soldermask covering the pad nothing can be soldered.

5

Thank you! This probably gonna work, I will try to inform my PCB manufacturer not to plate those holes inside the buttons and hope that they will do it (on the opposite side there will be either ground plane or backlight LEDs pads, so if the hole will be plated - I’m dead).

Regarding the button: nothing needs to be soldered to this copper pad, the overlay will be glued on top of the PCB and when a user touches an overlay it will be sensed by the MCU with capacitive-sensing core (CapTIvate technology from TI).

6

There are still 3 options:

  • Hold your first design and be aware the DRC only complains at this point. Also ask your manufacturer in this case!
  • Edit the gerber files: cut this hole description of yourproject-PTH.drl and paste it in the yourproject-NPTH.drl file.
  • If a few copies of the board, drill yourself on the same hole to sweep up the copper. We did it yaers ago with a mounting hole that got plated by error.
1 Like
7

Thank you for your help!

I will go with the first option.
I will also leave some space between the electrodes copper and NPTH. This shouldn’t matter that much if there will be 0.1mm non-copper ring safe distance. The same goes for the bottom side.

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