I am laying out a 2-layer PCB that has only through hole components, and I need it to be as small as possible. I was wondering how small I can set the clearance rule between the components?

enter image description here

When I searched I found very dense PCBs that has components nearly very close to one another like this one:

enter image description here

Does any component spacing work as long as pad to pad clearance is nearly 1 mm for easy soldering?


Here is a screenshot of my PCB: enter image description here

I am leaving very small distance between the fuse holder, pin header and the diode (aprox. 1 mm), is there any thing I need to consider?

  • 1
    \$\begingroup\$ If everything will be soldered on one side then not much to consider. If you are soldering on both sides, make sure you can get the iron into all the spots you need to. I am assuming all voltages are touch safe. If not, then there could be issues. \$\endgroup\$
    – user57037
    Nov 1, 2020 at 7:08
  • 2
    \$\begingroup\$ Make sure your mechanical models are accurate. I guess. If you think you are leaving 1mm but then the real part is bigger than your model, you could have difficulties. \$\endgroup\$
    – user57037
    Nov 1, 2020 at 7:10
  • \$\begingroup\$ Does PCB houses have problem with this spacings? \$\endgroup\$
    – Bavly
    Nov 1, 2020 at 7:25
  • 4
    \$\begingroup\$ PCB fabricators only make the PCB. They only care about spacings on the bare board. Copper to copper. 1mm spacing is huge by PCB fabrication standards. They can often do 0.1mm spacing. And 0.2mm is no problem even for lower cost PCB's. They don't care whether the components fit. That is not their problem. They just make the PCB according to the gerbers you send them. From the 3d rendering it looks like your board is fine. The only caveat is that you don't have a model for D1 so I am assuming it is no wider than the silkscreen rectangle. \$\endgroup\$
    – user57037
    Nov 1, 2020 at 7:54
  • \$\begingroup\$ ”I need it to be as small as possible” This does not makes sense given the ginormous boards you show. Why aren’t you using SMD components? Why are you not using both sides? \$\endgroup\$
    – winny
    Nov 1, 2020 at 8:46

2 Answers 2


Unless you have

  • high voltage issues

  • crosstalk (by electric fields) between components

  • heat dissipation issues

then pack the components as tightly as you are able to insert the thru holes.

You can even have components flush with the PCB, with alternate components raised up a few millimeters, with the solder pads offset as you wish.

And you can hand_form the leads, to be LONGER than usual, to act as very useful jumpers across troublesome traces.

In other words, use the components as a way to have 3 layers or even 4 layers of routing.


Just so you know, that PCB example you posted has very wide spacings.

How closely together you can place traces and components depends is limited by things like how the high voltage and noise. But as far as how close you can physically produce something, this depends on the PCB house you are using. But even a subpar PCB house should be able to accurately produce spacings as small as 0.3mm/12mil, and your typical PCB house will be able to be able to produce spacings much less than this standard.

You should order a PCB ruler from some place like Adafruit, Digikey, or Mouser that has examples of how wide different PCB traces actually are. It gives you a good feel for how things will come out. You will find that a 1mm trace/spacing looks a lot bigger as a trace than it will just looking at the markings on a ruler.


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