Open Misca1234 opened 6 years ago
I noticed that nxp uses SC-88 as the name for these packages not SC-70.
Using IPC-7351b calculation on the first nxp datasheet i would get the following parameters for the pads: (heel and toe fillet = 0.35, side fillet = 0.02)
position y = 0.8375mm, pad size x = 1.275mm, y = 0.4mm
This would result in a rather small clearance between the inside of the pads. reducing the heel fillet to 0.15 (arbitrary value chosen by me.) would result in the follwoing:
position y = 0.9375mm, pad size x = 1.075mm, y = 0.4mm and an inside clearance of 0.8mm
I noticed that nxp uses SC-88 as the name for these packages not SC-70.
Yes, but I guess people have reused the foot print because it is so similar, I have not search for which original component the foot print was made for, the foot print does not have a data sheet link
I would not pick a single vendor's document for our reference footprint. See https://github.com/KiCad/TO_SOT_Packages_SMD.pretty/pull/26.
IPC is the way to go, but unfortunately IPC-SM-782 doesn't have reference dimensions for SOT363 and the superseding 7351 doesn't have package drawings. I found a doc (I think it was in Japanese) that had tons of JEDEC outlines, but naturally I didn't save it and I can't find it now.
Once we have industry-standard reference drawings for a package, I favor splitting up the footprints instead of doing combo ones. After v5 is released and we've settled down, of course.
Even if we finally add specialized footprints we should keep the combo ones for backwards compatibility till v6 development is started.
Foot print Package_TO_SOT_SMD:SOT-363_SC-70-6
pin 1,3,4 and 6 are larger in the data sheet for both
https://assets.nexperia.com/documents/data-sheet/BC846BPN.pdf https://assets.nexperia.com/documents/data-sheet/BAV756S_BAW56_SER.pdf
https://assets.nexperia.com/documents/outline-drawing/SOT363.pdf
Should we remake the foot print