Welds on the good side


I making a PCB, using KiCad&Freeroute.

I try to make sure that my components are systematically welded on the good side, that is to say on the other side of the plate.

In other words, I would like the tracks of each component to leave on this side, even if it means increasing the number of vias…

Do you know if there is a way to do that? Logically, i think it should be in the rules, but I do not see anything like that.

Thank you

I’ll make this as clear as humanly possible:


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Ok, sorry for my english, let’s use a picture x)


I want to avoid this, and weld only on the other side of the pcb. You know what I mean ?

There’s not too much you can do about that other than to check lead diameters and their tolerances carefully and to ensure a max 0,1mm clearance around the lead (so a lead which is 0,75 to 0,82 diameter should go into a hole which is 0,9+/-0,05). This small clearance will help to reduce solder wicking through the hole but will not prevent it.

In the image you posted, the board was likely placed in a wave solder machine; in that case there will be a solder fillet on both sides if the copper is exposed on both sides. If you want to reduce the formation of a fillet on the top side, you can use the footprint editor to change the pad’s properties so that the solder mask aperture only appears on the bottom side. In principle you should then also place a pad on top which has the same number but only has a top mask aperture with a clearance of 0,1mm from the hole; you don’t want to take chances that the solder mask runs into the hole.


Well i have not read your last comment (you made it while i wrote my answer). My answer applies to this part of your question:

If you use a professional manufacturer it does not matter on which side your trace connects to the pin of your component. This is because such manufacturers produce so called plated through holes. (There is an electrical connection created along the full depth of the drill hole. The solder joint is also created over the full thickness of the pcb.)
A schematic of how this looks like:

The only reason why you might need to connect the pads on only one side is if you don’t have the luxury of a plated through hole process. (An example would be if you produce your pcbs yourself.)
In this case i would remove the pad from the top layer of the footprints. (In the footprint editor, the bottom layer is the layer opposite to the component.)

This way the auto router can not connect a trace on the top copper layer because there is no copper pad to connect to.
Again a schematic to explain how it can be done in a non plated through hole process (NPTH)

For this added information:

@cbernardo has the correct answer.


Thank you so much for your answers, very completes :slight_smile:

I’ll use the manufacturer of my engineering school, and at this moment I don’t have these sorts of informations about it.

I never used such machines before, and didn’t think it was so well-thought. You learned me something ^^.

In the case I’ve to use less sophisticated process, then I think deleting the top pads is indeed the properest way. But is there any way to make it quite fast ? Because there is a lot of pads in a pcb x)

I’m not sure the picture helps :slight_smile: It’s a stock photo, which means a photographer was asked to take some pictures without knowing anything about the subject.

Apart from the fact the soldering iron isn’t turned on, the user is applying it to the wrong side of the board. The board shown has probably been wave soldered and reflowed, and never hand soldered. So I’m not sure what it is trying to show.

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You should start calling it soldering, welding is something different.

Also, what is the problem of solder to come up on the ‘top’ of a PTH (plated through hole) and creating a meniscus there?

If you want a fast way out:

  • make a 2 sided board
  • place your PTH components on the top side (usually red)
  • lay tracks only on the back side (usually green)
  • send ONLY the back copper gerber layer and OMMIT the front gerber layers to the fabricator

I was wondering if this question is really about single-sided boards, which is a frequent question.

I’ve noticed Chinese speakers use “welding” to mean “soldering”. Although the process of joining might seem similar (involving molten metal), these words are never interchangeable in English.

I have had “welding” come out of Google translate from German describing soldering. Brazing is closer to soldering

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  • soldering = (weich) loeten (ger)
  • brazing = hart-loeten (ger)
  • welding = schweissen (ger)

There really should be no dis-ambiguity there in translations (ger <> eng).


Ahah you’re right ^^. In french “soudure” is used for welding and soldering, then I made the confusion.

The manufacturer isn’t “through-holes”, then I’ll have to delete all the pads on the component-side. But won’t it risk to connect the ground-plan to the pin ?

There should be a clearance left around the drill hole. For zones you can set the clearance in the zone properties themselves.
Edit: I just tested it in kicad stable 4.0.2: It works as expected.

Here my test project (There is a .pretty library included that has my modified resistor footprint)
footprint_test.zip (8.5 KB)

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Sorry, for being off-topic, but you’re right and this just sucks.
Can’t really believe it… :scream:


They seem to know braser though.

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