solder two wire inside vacuum

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steve_rb
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solder two wire inside vacuum

Post by steve_rb »

Hello, I want to solder two pieces inside high vacuum. Any advice how to do this? Soldering usually has some fumes come out due to the cleaning oil or vaporizing Tin which in my case will disturb vacuum. Anyone has any experience of soldering or brazing inside high vacuum or has any advice

THX
John Futter
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Re: solder two wire inside vacuum

Post by John Futter »

Steve
This is why most manufacturers spot weld things together ---no fumes condensing out
get yourself a battry pack spot welder off Aliexpress
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Rich Feldman
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Re: solder two wire inside vacuum

Post by Rich Feldman »

OTOH, an Internet search for "vacuum brazing" reveals it to be a well established technology.
This blog talks about need for special vacuum furnaces for aluminum brazing.
https://www.ipsenharold.com/2020/08/can ... m-brazing/
CA_Brazing_MichiganBluffPhotography-Cleaned-Up-2-1536x1025.jpg
Note large diffusion pump.


Soft soldering in vacuum is less popular, but vacuum reflow ovens are available in many sizes for void-free soldering.
https://youtu.be/WekVFbDZiJI?t=14

As John hints, it's not an easy thing to do at home.
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Re: solder two wire inside vacuum

Post by steve_rb »

Thank you but non of the above can not help me because I need weld to be high vacuum tight as well after taking the soldered pieces out of the vacuum chamber. Also my pieces are about 10 mm dimensions and can't afford to use furnaces design for industrial means.

thx
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Rich Feldman
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Re: solder two wire inside vacuum

Post by Rich Feldman »

Soldered joints should work fine in high vacuum applications that don't get too hot.
Tin and lead are NOT remarkably volatile like zinc and cadmium. Here's a relevant article.
https://www.mtm-inc.com/vacuum-compatib ... lloys.html

Why does your soldering need to happen in vacuum?

Does it need to be in same chamber that reaches high vacuum pressure at other times, using same vacuum pumps?
If not, then take hints from vacuum soldering apparatus on Internet.
How about a vacuum pot like those made for de-gassing mixed resin, or a horizontal tube just big enough for your work. The tube could be heated from outside. Pressure spike & internal contamination from solder fumes ought to be OK
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Re: solder two wire inside vacuum

Post by Jerry Biehler »

As long as you get all the flux residue off solder is just fine in a vacuum. Neither lead or tin have a high enough vapor pressure to worry about, heck, lead wire is often used in old vacuum flange seals.
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Re: solder two wire inside vacuum

Post by Jerry Biehler »

Ok, I might not understand what you want to do. You want to solder the parts while under vacuum, specifically a high vacuum? This is going to be tough if thats what you want to do. You'd probably have a better chance e-beam or laser welding under a vacuum, soldering is probably not going to be so great.
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Richard Hull
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Re: solder two wire inside vacuum

Post by Richard Hull »

I kind of understood this in the first post, but demurred as I figured there was just about no easy way to do this. Questions like are the wires already in full and intimate contact within the vacuum? So many issues and unknowns.

Richard Hull
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Re: solder two wire inside vacuum

Post by steve_rb »

Thank you for the comments. I have a tiny cylindrical detector (1 cm diameter, 1 cm height). I need to mount window on the front using epoxy. there are two options:

1- Mounting window inside high vacuum: Resin is a two part type (Hysol 1C) and can't be mixed prior to starting vacuum because acording to datasheet there is only 20 minute time to apply mixed resin which is too short to reach high vacuum (at least 1x10E-7 torr). I may need few hours to reach high vacuum. So resin should be applied unmixed (part A to the To8 mount and part B to the window periphery) and parts should stay in standby till few hours and when high vacuum reached push two parts against each other and hold which will do the mixing job too (resin layers are too tin about 10 micron) and wait for a few hours for curing. Then take detector out.

2- Mounting window outside: After mounting wait for resin to cure. Then drill a 1 mm whole at the detector side and put it inside vacuum and start vacuum until get high vacuum. Now it is the time to fill that 1 mm hole using soldering or some other means before taking the finished detector out. That is why I asked for soldering wire inside high vacuum to see if it is possible.

I prefer second option because window mounting can be done easier without defects but problem of blocking that 1 mm hole using soldering is there. First method will remove soldering step but I am not sure whether or not resin unmixed parts can stand for hours in vacuum in standby? And even if so then pushing them against each other will give a good mixing?

THX
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Rich Feldman
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Re: solder two wire inside vacuum

Post by Rich Feldman »

Thanks for the clarification.

There are resin systems that come from the factory in mixed form and must be stored cold, and have a practical pot life at room temperature. You could use something like that, and contrive to cure the joint with heat after the whole works is in high vacuum.

For your second option, a more conventional approach is to fabricate the small chamber with a metal or glass tube for evacuation. That gets sealed and parted, with high vacuum inside and atmosphere outside, by pinching or fusion. As in manufacture of vacuum tubes (e.g. MWO magnetrons).

I think a fundamental problem is your expectation that gluing the window in place makes a hermetic seal, and that the atmosphere inside the tiny can will remain at 1e-7 pressure level for a long time. Providing getter materials inside is important even for things like capacitance manometers, which _do_ have hermetic seals.
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steve_rb
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Re: solder two wire inside vacuum

Post by steve_rb »

According to the manufacturer datasheet window is mounted either using vacuum compatible epoxy adhesive or metal diffusion bonding. Epoxy adhesive is easier and best vacuum compatible epoxy I have found so far is Hysol 1C.
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Re: solder two wire inside vacuum

Post by Frank Sanns »

The hard seal way, with literally no leakage, is to use an interlocking indium solder joint.

Once the seal is in place, and this can also be with a resin seal, the tube is evacuated via a metal or glass side tube. It is there that the vacuum is pulled then the tube is crimped in the case of metal or melted off in the case of glass.

As Rich has mentioned, a getter is essential in these systems as oxygen WILL be inside the system even at deep vacuums.
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steve_rb
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Re: solder two wire inside vacuum

Post by steve_rb »

I can not have side metal or glass tube because there is no room for the tail after crimping. Soldering or resining has to be done inside vacuum chamber with a robot like apparatus. In case of resin it has to be left inside high vacuum until curing process ends.

By the way why Oxygen is a problem? I don't think some oxygen will harm since vacuum inside is just for lower conduction and getting to low temperature (-25 degC).
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