KiCad’s “1pin” footprint uses a plated hole, and I’ve noticed that many commercial boards also use plated holes for screw holes.
Is there some advantage of using plated holes instead of non-plated holes for mechanical connections?
Thanks!
The extra copper inside the hole can keep the screw head from “squishing” the board when the screw is tightened.
If the Pcb is installed into a metal case, the screw can provide an additional ground path.
I’m certain there are more answers.
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It saves an additional step as NPTH have to be drilled after the PTH plating.
This saves money in high volume and low margin products like cheap DVD players
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Thanks for the info!
One thing I wanted to clarify: pads of type “NPTH, Mechanical” come out as plated holes unless the pad size and drill size are the same. So, am I correct in thinking that I should always use pads of type “NPTH, Mechanical” for screw holes, even if I want plated holes?
Not an expert here, but it is generally good advice to be as clear as possible your intent when sending your files to a board fab house.
Pretty certain that if you specify a NPTH that you will end up with a Non-Plated hole. So, if you want a plated hole, the board fab house is going to need to know which one is which.
As mentioned above, the board fab house has to take different steps to achieve the different holes.
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At least with OSH Park, when I have specified an NPTH hole with a pad size larger than the drill size, I have gotten a plated hole. But I wasn’t sure if this was a feature or a bug. In order to get a non-plated hole with OSH Park, I need to specify the pad size equal to the drill size.
So, you’re saying that if I want a plated screw hole, I should really be using a Pad Type of “Through-hole”? Is there any way then to distinguish it from an electrical pad that needs to be hooked up?
For example, in the footprint Adafruit_HUZZAH_ESP8266_breakout_WithMountingHoles, there are 20 electrical pads and four screw holes. How do I tell KiCad that only the 20 count? (Because if the schematic has 20 pins and the footprint has 24, then cvpcb will filter out the footprint by default because it has the wrong number of pins.)
Thanks!
OSH Park has gone through a lot of steps to figure out what customers want, even if the customer asks for it wrong. Not every board fab house will treat your files the same. BTW, did you send native KiCad files to OHS Park, or just the gerbers?
I did not download the example footprint. However, if the footprint is built correctly there are 20 pins, it should filter properly; the extra holes are not seen as “pins”. When selected as a NPTH KiCad removes the pin number from the hole. If you are having a problem with this footprint you should probably create a new thread about it.
Holes and Vias are a little quirky in KiCad at the moment. I have to go back and look at my notes if it has been a while since I’ve used them.
I sent the .kicad_pcb, not Gerbers.
Right, which is why I currently have the screw holes set as NPTH. But you’re saying that if I want my screw holes to be plated, I should set them to “Though-hole”, not NPTH. This would make them indistinguishable from the electrical pads, so then wouldn’t it have too many pins?
So, to be clear, I’m not having any problems with the footprint now… but it sounds like I’ve done it incorrectly, since I’m using NPTH for plated holes. I’m trying to figure out what the “proper” way to do it would be.
Thanks!
A Google will show results for the interviews of the guy who started/created OSH Park. He really cares that you get what you want, and realizes that KiCad is used by many newcomers in the maker world.
KiCads gerber creation tool settings may even “fix” some issues. However, I still recommend trying to convey your intent to the board fab house.
Even I used the terminology incorrectly in this thread earlier. Electrical Symbols have pins, while Footprints have pads. A Footprint can have more pads then the symbols has pins. PcCvb checks for pin count, not pad count.
I think the correct way to make a mechanical through hole to be plated is done in one of two ways.
- Is for it to not have any net connection. In the “Pad number” box, use the “~” (tilde) symbol.
- Is to connect it to a net (and I don’t currently remember how).
Hopefully some more experienced regulars will chime in and let us know some more details.
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This entirely depends on your symbol and how you get the footprint into your layout and how you manage your libraries…
I usually place mechanical holes (either PTH/NPTH) directly in PCBnew, not as a symbol via the schematic.
Most often the holes are already part of a footprint module, to not screw up relative positions/distances down the track.
As those do not have any net connected to them they also do not have a pin number that can be used by a symbol/netlist import to hook them up to a net.
If I have mounting holes that shall be tied to a net I have a symbol for them and place them in the schematic, where they are then connected to the net in question.
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go into the options/settings of the pad in question in PCBnew, you can change it’s net in there.
I have no idea how this behaves with netlist imports though, so be aware of that.