Vias to the bottom layer


I’m trying to place Power tracks on the bottom layer, also a GND Zone. Surface mount on top side.

I know how to make the GND zone, and tracks, but I am unable to add and connect VIAS. The power tracks are 1MM, but the component PINs are smaller.

Here is an attempt to connect a track to a component PIN, it just won’t connect. I’ve tried custom tracks, but I presume the fault is the custom track is on a different NET to the POWER/GND tacks. How do I get round this please?


I think it is a clearance issue. The thin red line around a pad define the clearance. You can see that the GND pin3 clearance overlaps pin2. Try to turn off the DRC to test if it allows you the connection.

Then, change the clearance to a lower value at Setup->Design rules and work with the DRC on.

1 Like

But first make sure that your fab can produce boards with the new DRC settings. If not then either search for a fab that can or use a component in a larger package (with more clearance between leads and therefore pads)
It might even be the case that the footprint at hand is designed wrong. Check that the pads are not too wide (either against the datasheets suggested footprint or against IPC suggestions.)

Hi P,

I tried DRC off, no difference.
I selected this component and changed the clearance to 0.75, no difference.

I’ll try the next reply from R.

Hi R,

You may be correct. This is the mystery component, that I couldn’t find previously, and used one found for me.

Here is an image from a previous PCB, before I updated. As you can see it has smaller pads.

It looks like I’m going have to make a new one.



Hurray! I somehow managed to copy the DATA-SW from the old PCB, save it and change the one on the new PCB.

I also succeeded in adding VIAs. I’ve been trying for days :slight_smile:

Here is an image. The footprint is much bigger.

Thanks, C.

Make sure the footprint you are using actually fits the physical part you are planning on using. You can:

  • Measure the part and compare to your footprints.
  • Compare the datasheet to your footprints.
  • print the footprint out at 1:1 scaling and put a component on the paper and visually confirm.
  • If you are comfortable using (or wanting to learn) FreeCAD, follow this FAQ: Tutorial: How to check footprint correctness?
  • Some or all of the above.

Getting a footprint that works in layout is all well and good, but if it doesn’t match your planned part it is useless. This is much more important with SMT parts that don’t have long legs that can be bent into tortuous shapes to fit an erroneous footprint.

1 Like

I may be off base here but I noticed in your first post the Via had no net association, However in the 5th post it was associated with ground. Could this have also contributed to the issue?


1 Like

Check the trace connecting to pin 3 closely. It might be a bit too wide for the pad. (Notice that the rounded end of it protrudes into the area between pads 2 and 3)
You might either want to use a thinner trace or a zone to connect this via.

I also notice that you have very limited copper on your via. (Annular ring might be a bit small.) So it might be necessary to either decrease the hole size or increase the copper size. (Check your manufacturers minimum annular ring requirements. If they do not give this info then you need to check the drill size and drill positioning tolerances to calculate the minimum needed for yourself.)

Hi S,
You may have noticed that I said I copied the footprint from an old PCB, this is where the component fitted then, so I assume it will also fit the new PCB.

Hi J,

On the first post, I simply tried placing the VIA, so it was anonymous, the later post was when I copied another GND VIA.

I don’t know if this is the correct procedure, but I am not a good learner, so improvise, and hope I don’t have to pay for it later.

Hi R,

I see it, so I’l re-do it with the track coming from the VIA, using set size from start (Or something like that)

Before I make the PCB, I check it for such things, as VIA and TRACK width. I use wire for VIAS, and bend each end along the TRACK.


This topic was automatically closed 90 days after the last reply. New replies are no longer allowed.