When designing double-sided PCBs, Retromaster kept running into the same annoying problem: how in the world do I set my vias without them sticking out too much? A via must protrude from the board only very little, otherwise it cannot be placed under an IC. So placing copper wire in the via hole and soldering both ends is out. In light of this, Retromaster came up with a great solution. Use some copper wire and a vice. Sounds easy enough, right? Fantastic news – it is!
The best solution I’ve come up with so far is using “mechanical vias”. In a nutshell, I place a small piece of copper wire in the via hole. It needs to be a tight fit so that it won’t slip out of the hole. I trim the ends of the wire so that very little (perhaps less than a millimeter) of it sticks out of the hole in both sides. Then, I place the board in something like a vice (what I referred to as a “via press” …) and applying pressure to the board crushes both ends of the copper via and produces what seems like a reliable connection between the two sides.
It’s really simple to set one of these “via presses” up. Pretty much all you need for instructions on this is to refer to the picture above, and make sure you’re using steel plates on your vice which your PCB will be sandwiched in between. This is just to ensure that the copper wire gets crushed correctly, as the steel plates are harder than the copper wiring.
You can see Retromaster’s full DIY article here.