I’m making a footprint for a standoff with a hex body.
I have the Hole shape as a diameter of 2.4 mm ( this is clearly the size of the hole opening)
The Pad shape is not 2.5 mm but I’m not sure what effect this will have on the board mfg. Is this the limit of the solder mask?
For the circumference of the hex, I’ve put that in the courtyard layers
Do I read this properly?
Thanks
John
How do you attach the standoff to the PCB?
If screws, you need a hole big enough for the screw to pass through comfortably. A 3mm screw needs at least 3mm (has a major diameter of 2.866 mm). A 2.5 mm screw needs at least a 2.5 mm hole.
If it is a push fit, expanding lug, plastic standoff, best to consult a data sheet.
Your courtyard needs to be a little larger than the major diameter of the hex or the screw head; whichever is larger.
A .1 mm annular width pad is not a great idea. The pad will probably strip off the PCB and lodge itself in a really destructive place on the PCB (Mr. Murphy says so). Either no pad or something at least as large as the screw head.
The core diameter of a 3mm screw is 2.366 mm. which is pretty close to 2.4mm. Is that what you are measuring?
The pad shape is primarily the shape/diameter of the copper circle, but it also affects the solder mask and the other layers you might have selected. If you don’t want copper, make the copper the same size as the hole. You might also want to set “Copper layers” to none, although I have no idea if this has any effect. The default mounting hole footprints have this set to “F.Cu and B.Cu”.
I have never done hole for standoff. I don’t see a difference between such hole and typical NPTH. I looked into my NPTH definitions I made by copying KiCad library definitions (may be coming from KiCad V4 library). In my definition for NPTH 2.4mm the Pad diameter (F.Cu, B.Cu, F.Mask, B.Mask) is also 2.4.
I have standoff’s that have a 2 mm thread. From what I read, for a 2 mm screw, 2.2 mm yields a “tight” fit, 2.4 mm is a normal fit.
I have 4.55 mm for the “courtyard”, in this case the OD of the circumscribed diameter of the hex standoff.
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