Review of DC Barrel Jack PCB footprint - Things don't add up!


Yes…I see this, then I click ECAD Model link, and it says “Pick Category?”


Size X/Y in the drill section are the size of the hole/slot. Size X/Y in the left column, under Position X/Y, are the size of the copper pad. Your pads need to be larger.


how much do you propose I have? – says 0.127mm – although I am not sure what I should have?


How much larger! What do you propose?


It depens on practical things, it should be convenient to solder. The oshpark minimum is the minimum and I think it would work with that, but something like 0.5mm would be better (EDIT: I’m more used to SMD components so I think small; 1 or 2 mm could be better). The larger the copper area, the more there is tin, and the sturdier it will be. But too large is also difficult to solder.

BTW, now I suppose the feet of the component are metal and you will solder them manually.


Much larger, given the type of connector and the stresses it will likely see, and you probably won’t need to run any tracks between them, your pads should be as large as possible with reasonable clearance.


This is the barrel jack FP in the Kicad library. You can see the dimensions of the aperture for the ‘Hole Shape’ is ‘Oval’ & 3mm x 1mm which will allow for tolerance. This is a KiCad 5 Footprint - it has two rounded pads so you will only be able to use it in KC5, but the design principle applies to 4.0.7 too. You can see that the Pad sizes are larger than the slot - in this case 3.5mm square.


Ok great advice.

This is now a 4mm x 1.8mm pad for a hole size of 3mm x 0.8mm

My footprint: 3_Pin_DC_Jack.kicad_mod (939 Bytes)

@eelik @1.21Gigawatts do you think the placement locations of the pads is accurate according to the datasheet? I still believe there is this issue:

Issue 1:
Pad 1, should be 13.6 to the very back of the jack.
On my footprint, it is 13.25
This doesn’t seem right.


Bigger! Look at the example @John_Pateman posted.

Then fix it. It should just be a simple matter of moving the front edge of the silkscreen, assuming your pad spacing is correct. (No, I haven’t opened your file)


I had a quick check - there is a Barrel Jack FP in the 4.0.7 stock libraries without the rounded pads - a quick check of the dimensions suggests that it is the correct size for your application. It is in the ‘Connectors’ library.


if you search for

then you get the footprint.

You can then compare your new one with what they give you …

you can always check it mechanically with the manufacturer 3D model
still not always 3D models are fully accurate… a review with the physical model is always necessary


That’s my problem. I have got the spacing correct as far as I believe but there is a still a problem, and I would like support to find out where I made a mistake.

@John_Pateman This may be the case - but I would also like to learn how to do this!


For reference, this is the footprint for this connector that i will add to the official library BarrelJack_Wuerth_6941xx301002.kicad_mod (2.4 KB)

Pull request:


On Kicad 5rc02, there is a helpful ‘Caliper’. Not sure if it is present in 4.0.7. The dimensions seem to accord with your initial requirements.


Where did you find that? From that site?

I just want to understand the mistake I have made in making the footprint - please can we focus on that for now?

In particular:

Issue 1:
Pad 1, should be 13.6 to the very back of the jack.
On my footprint, it is 13.25
This doesn’t seem right.


I just made it myself. (In accordance with the library convention because i also started the process for this to be added to the future kicad library.)


These are just two screen shots from the FP Editor. I am using V5 so it might look slightly different if you are using 4.0.7 - in particular, I am not sure if the ‘Caliper’ tool is available in 4. To measure something, you might have to use the spacebar technique in 4.0.7.

Place your cursor over the middle of a pad and press the space bar. Move the cursor to the point of reference - i.e.e the edge of the connector and look at the dX / dY or Distance reading on the bottom of the window to measure the distance between the two points.

As I said, this is the standard Barrel_Jack footprint from the stock Kicad ‘Connectors’ library.

Whilst it is an essential skill to be able to make your own footprints, in this case, there would seem to be a suitable footprint available in both the 4.0.7 and 5 standard KiCad libraries.


I already told you how to fix that, move the left (front) edge of the component outline.


That shouldn’t be necessary though, the outline is the correct length, 14.5 and the spacings appear valid.

Maybe you could take a look by importing the file because you won’t see what I am saying until you take a look.


In that case you move the entire outline to the left. But your pin spacing is incorrect. How is that possible if you followed the guidance of everyone else and set your grid accordingly?