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I am designing a PCB for a Numitron clock. It is just my own project, not for a company. The milling machine at school can only deal with 16mil+ sized traces, so I have some troubles routing traces between IC pins, for example. I must also note that I can only have 2 layer PCB's made at school. I have attempted to route the board several times now, but I always hit dead end, because something always crosses another trace. If I were to introduce vias, that would make things a lot easier, although the PCB would not look as nice, because I would have to connect it with wires externally.

My question is - are vias an acceptable solution, or is it a last resort? I imagine that in real life each via increases production cost, and that is a part of PCB design considerations, but what other pros and cons are there to vias?

Willy Wonka
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    In real life the cost of each via is zero. – user110971 Apr 25 '18 at 11:54
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    "because I would have to connect it with wires externally" - What do you mean by this? Are you perhaps confusing vias with jumpers? – Dampmaskin Apr 25 '18 at 11:56
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    Vias are internally connection between layers, not externally. – Meenie Leis Apr 25 '18 at 11:57
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    @Dampmaskin I am assuming as they're milling the board the 'via' would be a hole with annular ring on both sides and they would solder a wire in, rather than having through plating. – Colin Apr 25 '18 at 12:04
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    Rather than vias you might try using "0 ohm resistors" or a bit of wire to help with routing a particularly complex part of the board. You can route many traces through the footprint of a standard through-hole resistor. – scotty3785 Apr 25 '18 at 16:26

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Vias are totally acceptable and used in almost any design, the most important things you have to worry about is the use of via's on high frequency lines and on power lines.

If you have a part which requires some higher currents or anything, say a design of a power supply for example, it is required you put several vias in the same line or in the same power polygon to be able to handle this current

Stack exchange current through via

The other problem with higher frequencies, is that if you have a multi-layer board the via can act as a stub, the stub can act as an unterminated transmission lines causing problems with your signal integrity.

More info about Stub and vias

To summarize: Vias won't increase production cost (unless you do special operations like blind vias or back drilled vias and are used in probably all two or more layer designs.

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Remco Vink
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  • For milled boards, vias definitely increase production cost. – Simon Richter Apr 25 '18 at 12:29
  • Will multiple vias cause ground loop problems ? – Meenie Leis Apr 25 '18 at 12:38
  • No ground loops are not in particular caused by via's, ground loops can occur if the the ground has a different potential on different places in your design. Thats why pcbs usually have one or multiple ground layers, and vias stitching all the grounds together at multiple locations on the board. A more likely problem can be a really lengthy or weird return path for the current which is mostly controlled by proper layouting and pcb design. – Remco Vink Apr 25 '18 at 12:56
  • @SimonRichter - Why? It's just a hole - there's no plating if the OP is referring to soldering a bit of wire through... – brhans Apr 25 '18 at 15:00
  • @brhans, "soldering a bit of wire through" is an extra step, and extra cost, compared to finding a way to design with no via. – The Photon Apr 25 '18 at 16:48
  • @ThePhoton - sure, but if you're milling boards you're counting volume on one hand (maybe two) and probably hand-assembling - so ... – brhans Apr 25 '18 at 16:50
  • @brhans, still you might be paying a tech to do it rather than doing it yourself. – The Photon Apr 25 '18 at 16:58