# Tool Talk >  Cold welding GIF

## Jon

GIF of cold welding of two gold nanowires.


https://s3-us-west-1.amazonaws.com/h...ld_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.

Interestingly, cold welding is problematic in space travel. Cold welding is usually prevented by the various contaminants and oxides present on metal surfaces. However, the absolute vacuum of space eliminates these, leaving two perfectly clean metal surfaces. This was notably brought to attention after studying an incident in 1991, during which an antenna attached to the Galileo spacecraft failed to open.

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dubbby (May 31, 2020),

PJs (Jan 9, 2017),

thoms_here (Jan 8, 2017),

Toolmaker51 (Oct 13, 2018)

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## Toolmaker51

re: Cold Electronic Welding



> GIF of cold welding of two gold nanowires.
> 
> 
> https://s3-us-west-1.amazonaws.com/h...ld_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!

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dubbby (May 31, 2020)

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