It is basically a turned flat wire inductor for higher current usage. The “Recommended PC Board Layout” indicates rectangular TH of suitable spacing and dimensions.
The footprint I created used obround of suitable dimensions since I was thinking about manufacturing and such a slot would be milled and thus an obround is the logical realisation.
Unable to achieve solder fill as per IPC-####
DFM recommendation - change footprint to align to OE
The irony is that DFM was considered since an obround is exactly how a boardhouse would prefer to make this…
ASSUMING a boardhouse was willing to use a smaller routing bit to create a rounded-rectangle hole (suitably sized to their prefered routing bit and the dimensions of the turned flat wire…), how exactly would such a pad be made in KiCad?
NOTE: I stand by the pad dimensions and type but I am curious how this could be done
It’s weird indeed. Maybe it’s about assembly, not manufacturing, if you have outsourced THT assembly there. First, there may be too much extra length so that the component doesn’t fit tight enough. Second, there’s quite much empty space to waste solder in the ends of the oblong hole.
Does this “concern” mean they don’t want to do it, or that they just ask if you accept it?
There’s no rounded rectangle hole in KiCad, it should be routed in edge.cuts or maybe in a separate layer, depending on how they want it. It’s possible to have edge.cuts in a footprint even in v5.1 but you have to draw it in another layer and change the layer manually in the footprint text file. In 5.99 this can be done directly in the GUI. Or you can just draw graphics and use it as a guide and draw it in the layout.
It is the actual assembly, the local solderpot applied to the THT. The specific concern raised was due to the larger hole w.r.t. the leg the solder fill is below their quality level and thus a concession was requested and also that the footprint “corrected” going forward
This was a prototype run, and while a variant may or may not got to production, Mentor librarians are equally perplexed. I was just curious as to how it could be done for kicad since edge.cut would produce the hole, but how to ensure its marked as PTH so the board fabricator will plate it.
I’m sure the best way forward is find the best way to assemble rather than a hacky approach in any eCAD tool along with causing fabrication concerns but that’s a wider picture issue
Cover the hole with copper (i.e. with SMD pads), just like in a THT pad. I don’t know of any other way to mark an inner slot in edge.cuts layers as plated. Copper going over an edge is usually interpreted as edge plating, but it’s an interpretation and convention, not an official standard, just like many other things in gerber.
Setting aside ‘who’ will make the board, for a moment…
I make these holes frequently on my cnc mill. The Pad has an ‘Oval’ hole but, that’s a misnomer as it’s not really Oval. It’s Rectangular with fully radius’d ends.
Just change the hole type to Oval in the pad Footprint/Pad editor.
Note: you can also draw the rectangle with any hole. Check with PCB house to see if they can make it. JLCPCB does (last screenshot)
FWIW, I had forgotten that oval means egg-shaped until you had mentioned it, and I hadn’t looked up the OP’s term obround until now. (I was previously unaware of that term and assumed it was a British English vs American English issue but had figured out what he was talking about through context.) I’d like to thank you both for helping me with my vocabulary. (Yeah, I started a little snarky, but I’m actually being serious. Thanx for the vocab.)
Back to snark, maybe the assemblers want that hole drilled with a square milling bit to get a rectangular hole…
I hadn’t found (and don’t use so was unaware) of the term stadium in the context of a shape (instead of my previously incomplete usage only as a building). My quick checks of the term ‘oval’ seemed to only indicate flattened circles and all the examples that I saw were egg-shaped. (I know the terms ellipse in mathematical and cone projection terms.) It seems that the term “oval” isn’t well defined, and about the only round-ish shape that I have found that isn’t referred to as oval is a circle… (Though according to the definition of oval specific to projective geometry a circle does fit.)
Back to the topic at hand…
I read this as the problem was flagged at the assembler. PCB fab houses usually don’t care about MFG suggested footprints, only copper clearances, hole/slot sizes, board stackup, etc. They also don’t care about solder fill.
The assembler (or whoever flagged this) should be asked how they would suggest to specify drilling a rectangular hole to fit the manufacturers recommendation in the data sheet. Do they know of a manufacturer recommendation that isn’t in the datasheet? What is required to fill out a waiver for those two holes to allow deviation from IPC-####, and do they have a suggestion for dimensions of the obround hole to get closer to the solder fill that they want?
(Yeah, I started a little snarky, but I’m actually being serious. Thanx for the vocab.)
