FEDEVEL
Platform forum

Clarice Starling , 09-06-2024, 09:34 PM

how should i design this screw hole?
should the main hole be plate?
should the thermals of the vias be direct?
do you have any other suggestions? (For M3 Screw)

Robert Feranec , 09-07-2024, 06:43 AM

I have never done this in Altium, but in Allegro this is done as a symbol + footprint where everything is a pad. Thermal is direct. https://fedevel.com/forum/altium-designer/9463-mounting-hole

QDrives , 09-07-2024, 04:01 PM

There are some opinions on mounting holes.
The main debate is on plating. Not just of the main hole.
My take on it is:
- Plate the main hole.
- Have the pad size bigger than the largest size + tolerance of the screw, bolt, washer, standoff, etc. used. For M3 this could be something like 7mm (hole is 3.4mm)
- For most reliable solution, the vias are outside the area of force (bolt, screw, etc.), but that would make it even bigger!
- And no need for thermal relief on the vias, so direct connection (all my vias are direct connection via rule anyway).
- Mounting holes are 'components' (schematic + footprint). A 'Standard (No BOM)' type.

Clarice Starling , 09-09-2024, 03:49 PM

Thank you so much 🙂

QDrives , 09-09-2024, 10:33 PM

What I forgot to make clear: the debate on plating is in relation to the force exerted by the screws. That is why some are stating it is better to not plate.
From recollection, the 'reasons' were not applicable to my designs.