Hi all,

I need to connect and secure wires that will carry up to 3A of DC current during standard operation and will be raised to temperatures as high as 300C while not in use. These wires are ported through a glass cell which is under ultra-high vacuum (see attached). The wires are 16 AWG, stranded/braided and uninsulated. They were custom made for this part, so I don't have much more info than that. They appear to be solderable (non-aluminum), but are not tinned copper.

My first thought was screw terminals. Do they still perform OK if the wires are hot? Anyone have recommendations for a particular part?

Thanks in advance!

P.S. Please disregard the messy connections that are currently shown in the attached images. It was from before my time at this lab and not in use.

 

Cycling at 300°C, screw terminals will eventually loosen. Better to use a crimp. How are the leads kept from shorting together?

 

Crimp: a crude form of cold welding
There is also a method of quick spot welding with an electric current.
300C is too hot for lead solder, but the next level is called, "brazing".
If this has to go to Mars (no servicing allowed, forever) I would investigate what metal will braze at 400C.

 

Never use a screw terminal.

We normally use UHV rated crimps if the connection is in vacuum.
https://accuglassproducts.com/product.php?productid=16430
https://accuglassproducts.com/product.php?productid=17209&cat=486&page=1&variantid=916

 

How about a screw clamp terminal such as this?

 

Crimp for speed and low cost

Braze for a joint that will last longer than other components on your project.

Use screws if you are selling it to the Chinese or Iran.

 

How about a screw clamp terminal such as this?

He has a 300C cycle requirement (likely because of a vacuum chamber bake-out requirement).

Most of those are rated for cycles from -25°C to 70°C

A Molex Krimptite™ should work just fine outside of UHV level vacuum.
http://www.molex.com/molex/products...ily&key=high_temperature_temp_terms_terminals

 

Thanks all! I learned a fair bit from your replies.

The connections I need to make are out of vacuum (in atmosphere), but the wires run into the UHV chamber through the bottom of the glass wall I showed in my first picture.

The wires are pretty short and close to the wall of the glass UHV chamber, so I'm a little nervous about brazing. Crimping seems like a good way to go.

As far as keeping the leads from shorting, my thoughts are to crimp the wires to insulated wire and then ziptie the insulated wires in a way that (gently) pulls the leads apart, and then putting up a non-conducting shield to keep errant hands away from those wires.

Thanks again!

 

You can slip Teflon tubing over a lot of things, and it withstands 300°C. Even if you can't slip it, a split tube will do almost a well. Or, just a plane Teflon separator plate.

John