I used Connector > Molex_Mini_Fit_Jr_5566_20A_2x10_P4.20mm_Vertical and when my board arrived I found the pitch (between rows) was 5.50 mm not the P4.20mm stated. I have checked the footprints in KiCad and it seems all the different footprints of this style are the same wrong value, ie all footprints from 2x1 up to 2x12 pins and both Vertical and Horizontal layout.
There is an old post from Apr 2017 that mentions this: https://forum.kicad.info/t/potential-incorrect-footprints-for-mini-fit-jr/6006
so its a very old problem, and not just a single footprint.
Edit: To be clear, I have since downloaded the footprint direct from the Molex website, and that downloaded footprint also has pitch 5.50mm, but the component I bought has the 2 rows at 4.20 pitch, as defined in the name.
Searching online, this connector is used for PC power supplies, and the pitch is described as 4.20mm, eg https://en.wikipedia.org/wiki/ATX
" The connector pin pitch is 4.20 mm…(about one sixth of an inch)."
From old forum thread you pasted above seems like some knock-offs of the original Molex connectors have 4.2mm row spacing, so probably yours is not original Molex.
This is a very confusing part where the plug/socket pin to pin pitch is 4.40 x 4.40 mm, but the PCB pitch is 5.50 x 4.40 mm.
Normally in connectors we are talking about the plug/socket pitch
What I am saying is that the socket I bought to go on my board does not fit the 5.50 mm between rows, and my PC power supply fits into the socket I bought. So my 2 items are 4.20 pitch in both directions.
It would be strange if someone was trying to sell knock-off items that are wrong.
This is a diagram of power connectors:
On my computer screen, the pins are equally spaced pin pitch and row pitch, and the pitch is nearer 4mm than 5mm.
Read the comment from the old forum thread you sent a link earlier.
Molex is 4.5 / 5.2mm, while cheap Aliexpress knockoffs are 4.4 / 4.5mm.
So I’ll say that again - looks like your is not original Molex. So Molex footprint may be (and in this case it not) correct for your connector.
the receptacle holes are indeed 4.2 mm apart in both axes. But the pad centres are 5.5 mm apart, probably because the pins are “turned outwards”. Have you fitted pins into the receptacle yet, or are they prefitted?
