Cold welding GIF

[Toolmaker51]

re: Cold Electronic Welding

GIF of cold welding of two gold nanowires.


https://diqn32j8nouaz.cloudfront.net/cold_welding.gif

During cold welding, metals can join without heat, by mechanical contact alone. It can happen with clean, flat surfaces of similar (but not necessarily identical) metals, under vacuum. We first discovered cold welding in the 1940s.

I think this is performed ultrasonically. Used in lots of miniature and micro-miniature electronics.
Here, the link illustrates Ball, Wedge and Ribbon bonding. Its just 1:14 long, enough to set 740 bonds!