I would like to create a footprint that provides pads along the edge of the board where the holes are slotted. Similar to castellated pads but the holes must be slotted (oval) and are quite large to accommodate a 6-32 screw. The purpose is to provide a simple mechanism to connect a pcb with multiple connections to a power supply that has a screw barrier terminal strip. I have attached a couple photos that illustrate something like this. I do not think it is necessary to have plated slots but that would be helpful. The plating inside the slot would not have to extend all the way to the edge. Each pad of the footprint should include multiple vias surrounding the pad to ensure distribution of the current. The terminal connection is up to 20A and I would likely use additional layers to improve conductance. There was a discussion about castellated pads and an open ended slotted hole along the edge. This is quite close to what I want to accomplish and was wondering if there were any other thoughts about my specific use case. I tried starting with a NPTH hole in the footprint editor but when I do that, you cannot provide a pad number for the pad so was not sure if this would throw a DRC error later on. Using a Through-hole pad generates a warning “Warning: (PTH pad hole non fully inside copper)” so I was not sure if I should proceed that way either.
If the holes in the slotted pads are NOT on the Edge Cuts layer, they will get plated. The web between holes will not have plating on the edges, because it will be routed out when the board outline is cut. If you need plating all the way to the edge of the web, that whole profile needs to be NOT on the edge cuts layer, and it’s worth talking to your PCB manufacturer to see how they want to handle it.
Note that most commercial castellated products don’t bother with plating on the web:
The first time I ordered JLC did give me a warning that the quality could not be guaranteed if I did not specify them as castellated. This would have made them much more expensive though, so for the first prototypes I decided to take my chances on that. They turned out flawless.
I since ordered a first batch and another set of protos for a similar board and they are all as you can see on the photo.
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