I’m trying to create the following footprint:
I know how to create an SMD pad with the Clearance Overrides and Settings → Solder mask clearance, but this is symmetric about the pad center. I tried creating two different pads (one for the mask and solder, and another for copper), but I couldn’t find a way to remove the copper layer from the one defining the mask and solder. Any better way to do this that I’m not realizing?
To clarify the attempts so far: I can create a symmetric offset like so:
Or I can create separate pad definitions like so:
See how paste openings are made in KiCad packages with one thermal pad and many paste openings. QFN packages are one of many examples.
In V5 when defining SMD pad you can select layers and for Copper specify None.
How in V6 and V7 I can’t check now.
This pads have symmetric mask. They only have smaller paste openings than the pad. The tin is wet during soldering and in fact only the surface of the paste hole is important, not its exact location (specially if there are no vias in those pads).
I see. It looks like they use a SMD Aperture Pad Type for the paste/mask in the QFN packages rather than SMD, which allows for a “None” Copper Layer.
I was also under this assumption, so not sure why they spec the footprint shown with specific dimensions for the offset. It might be the first time I’ve seen it spec’d like that, so I guess I can just ignore it. Curious if anyone else has any valid reason for requiring this though. Maybe something to with surface tension, or the exposed metal locations of the LED part in question. Not sure.
I think so.
Rather not. If surface tension works than where the paste was placed has nothing to do (I think).
I’m not sure if Pbfree tin melts just as well as the classic one. So may the thinking (like my insecurities) was behind such definition.