Maybe I'm reading something wrong, but I think that certain footprints may be slightly off so I'd like a second opinion.
smd-ipc.lbr claims that it is based on IPC-SM-782. I'm looking at that document from here: https://www.pcb-3d.com/wordpress/wp-content/uploads/ipc-sm-782a_amendment_1_and_2.pdf
I'm working off of page 73 in the Surface Mount Design and Land Pattern Standard Chapter section 5.0 Land pattern dimensions.
When I read Figure 3, it looks like they've used the label "X" for the vertical pad size and "Y" for the horizontal size. That's unintuitive... but the figure very clearly marks the dimensions. And my drawn pads don't match up with smd-ipc.lbr for the 0603 part -- they match perfectly when the X and Y are transposed, so perhaps the smd-ipc.lbr author got confused with the X and Y labelling.
Can someone check my reading of this doc?
A lot of the other resistor footprints in smd-ipc.lbr are slightly different than this doc as well but not clearly transposed. As we all know from experience, there is quite a bit of fudge in the pads of SMT resistors, which is probably why these footprints are generally working. However, the doc is supposed to be the "best" (that is, providing the best yields) land pattern, so if fixing smd-ipc.lbr stops a few tombstones in everybody's runs that would be a worthy goal I think. ... Or maybe the doc is obsolete and the smd-ipc dimensions are what is currently considered "best"?
Regards,
Andrew
