Electronic – Accidental solder in vias

It depends very much on how the boards will be assembled and soldered. If you are doing it manually then it will not matter too much. I try to pick a slightly larger footprint for my DIY boards because that makes it easier.

If the boards will be professionally assembled then the footprint will definitely matter. There are often slightly different requirements for e.g. reflow soldering vs. wave soldering. This is when you'll need to work closely with the assembly house to work out what size and tolerances they can work with.

Recommended is a trace length 'L' to via of at least 5 mils, with a solder mask dam along the length L.

Otherwise you should use 'tented' vias (covered with solder mask), or offset plugged or blind vias.

The main concern is the via sucking the solder away from the joint. If you've followed reasonable design rules, you may not have a shorting problem.

Edit:

If you want to try coating the vias, you can get UV curable solder make in small quantities on eBay. Being UV rather than solvent base, it should be fairly low viscosity, and thus go down thin. I have not tried this, but at a few dollars it might be worth a try. You'll need a UV lamp to polymerize the coating.