Potential incorrect footprints for Mini Fit Jr


Hi there,

I was making a PCB utilizing the Mini Fit Jr. footprints and I noticed that the Y spacing is different to Molex’s drawings.

Looking at the documents for a 2x4 pin connector, the Y spacing is written as 4.2mm:
( I can’t post more than one image :cry:, source for Y spacing can be found below, around about E9 )
( Source )
Whereas the actual connectors are 5.5mm:

( Source: Molex_MiniFit-JR-5556-08A_2x04x4.20mm_Straight )

Unfortunately that seems to be the case for all of the connectors, including the right angle connectors.

What should I do? I have a couple of options.

  1. Fix them all myself
    • Not advisable because I am a n00b
  2. Tell the proper authorities
    • I’m not sure who to notify or where!

Thanks muchly!


I think the 4.2mm spacing is for the socket on the top of the connector, as opposed to the pin spacing on the PCB.

5.5mm is shown in the drawing (hole layout at B12, and the side elevation at D6).


As @hackscribble alread wrote: The 5.5mm spacing is the correct pin spacing.

But to answer some of your points:

Don’t be to harsh on yourself. Everyone starts somewhere.
But a lot of footprints are script generated. (Including this connector footprints.)
This means you would need to change the script itself.

This should be done in the github repo of the footprint. Just raise an issue.


Oh darn, totally missed that! I reckon I might need to stop buying dodgy connectors. Sorry! Thanks for the advice too. Next time if there really is an issue I know where to go.



I also think there is an error here.

I just had some boards made and the Molex Mini Fit Jr connectors don’t fit. I choose the straight connector as the footprint on the board. It should have a 4.2mm pin spacing in x and y

The right angle connectors fit the 5.5mm spacing fine but the straight connectors don’t. The pins on the straight connectors go straight through and I have confirmed by measurement that they are indeed at a 4.2mm pitch.

Below are some pictures to demonstrate the differences.


That’s odd… I have some 2x2 Mini fits here, and the pitch and spacing is compatible between the straight and right angle versions.

Maybe something funny about 2x1 size? A 2x1 would be different to 1x2. I can’t see how there would be a manufacturing fault. There are several variants of mini-fit, sometimes distributors send mislabelled parts.


What does the datasheet of your connector say?
Is it really the same connector as the one given in the datasheet of the footprint?


Where did you get the connectors? If you got them off sleezebay or the like you could have counterfeits.


So it seems my Molex brand (Arrow.com) and cheap knock offs are not the same.

The AliExpress ones are 4.2mm pitch (x,y). The correct Molex are row (y) spacing of 5.5mm and pin (x) spacing of 4.2mm.

Lesson learned to always verify the pin spacing.


Interesting… the Chinese clones might be compatible on the connector side (4.2mm) but have a different PCB footprint.
Aliexpress 4.2mm connector
The pins seem to have a different construction as well. I’d be wary about cheap connectors if you are hoping to push a lot of current through, the current rating is usually 50% of what they claim, if that. I’ve seen a lot of melted connectors on 3d printer boards.


The plastic looks like a cheap polythene.


This is an interesting story. Someone counterfeiting SSRs and subbing under rate triacs. Otherwise the author claims they were surprisingly well built. How much money can you save scrimping on triacs when Mouser has the one off price for one quoted in the article at $1.84! I first learned about this on a home brew forum. Sad part is, people have notified websites and no action is ever taken.


And I stopped reading it after this line: “One change we made is we switched from buying directly from a Chinese supplier to buying through USA based suppliers selling on Amazon.com.”

He was buying electronic parts for production from “some guy” on Amazon? He got what he deserved.


Well, that was the point. It was a follow up to my initial post.