Cold Welding of Copper Wire

Join it to what? And you may have to compromise on something. There is no way to join it without affecting something. Technically, joining it to anything is to effect it mechanically.

You should look into ultrasonic welding.

Companies like www.sonobondultrasonics.com and www.amtechultrasonic.com have what you need.

Eric Girard

I am assuming you want to join copper wire to copper wire. When joining thermocouple wires, any type of solder would create another cold junction, so the two dissimilar wires need to be joined without introducing another metal. Thermocouple welders are moderately priced, small and easy to use. I made my own, using argon gas to shield the wires and a small arc welder. This should work for your application even if its intended purpose is thermocouple wires. DCC corporation makes a small unit. http://www.dcccorporation.com/