During a two week hiatus at Bell Labs I used a micro-manipulator to weld thin gold wires to power transistor elements and the case leads.

Basically, it was a three dimensional pantograph with a fractional motion ratio such that a relatively large hand motion produced a minute probe movement. You might want to experiment with a 2D version first; should be able to construct a trial version fairly quickly.

Or, if you're rolling in money, there's always the professionals...


https://micromanipulator.com/

https://www.wpiinc.com/applications/...n/manipulators