Electronic – What reasons are there to avoid vertical through-hole resistors

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I'm working on a layout for a PCB and I need to include a handful of pull-up resistors. The board I'm working on will be a proof of concept, and it is likely I will only need one (and order two). That being said, I'd like to keep the board area small. In addition, I'm using through-hole components to make any revisions easy.

For these pull-up resistors, vertically mounting them would save some space and cost instead of alternatively mounting them horizontally. However, I rarely see vertically mounted resistors in commercial or industrial products. So, should I avoid using the vertical resistors even though they will save cost up front?

Upon searching Google for an answer to my question, I came across these two links:
http://www.head-fi.org/t/162556/any-reason-why-i-shouldnt-use-resistors-vertically
http://www.proaudiodesignforum.com/forum/php/viewtopic.php?f=6&t=90

The consensus is that vertical resistors are less popular because:

  1. Auto-insertion machines can't (or don't prefer) vertical resistors. This isn't an issue for me since I'll be soldering the board myself.
  2. Horizontal mounting provides more stress relief. This is also no problem since my board will be safe in an enclosure that is only going to get light use to prove a concept.

Are there any other reasons I am overlooking? Granted, most modern designs use SMT components that take up even less space. If the best answer to my particular situation is to just break down and learn to solder the SMT components, I would still like the background knowledge as to why the horizontal resistors are more popular.

Best Answer

Mounting a resistor vertically creates a bigger loop that can pick-up interference magnetically. Compare this with a resistor being mounted on the PCB flat against a flooded ground-plane. The voltage pick-up level is proportional to frequency and area of loop formed by the resistor. This is why surface-mount resistors are preferred a lot of the time.

Also, A high value resistor mounted vertically is also asking for trouble in the presence of HF electric fields - what you can create is a mini-antenna.

As for pull-ups and downs, surely you won't be swapping these out in your prototype - I'd consider using surface mount devices for these parts.

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