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I have to "fix" some 50 micron tungsten wire to copper/brass.

  • Has anyone soldered this material?
  • If so, what solder was used and what advice can you give?

Note that this is on a scale that is too small for a mechanical connection to be used (screws, clamps, etc.)

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    \$\begingroup\$ Tungsten wire ... let us know if this assembly is intended to be raised to high temperatures, that might affect the choice of "solder"... I have a feeling some form of cold weld or compressive join like crimping may be the answer. \$\endgroup\$
    – user16324
    Apr 28, 2017 at 11:10
  • \$\begingroup\$ Consider brazing or welding. \$\endgroup\$
    – JRE
    Apr 28, 2017 at 11:14
  • \$\begingroup\$ The assembly will not be going beyond 85degC. Looking at the possibility of replacing a Platinum/Iridium wire with something mechanically stronger. Think meter movement. \$\endgroup\$ Apr 28, 2017 at 11:15
  • \$\begingroup\$ What are you trying to make? \$\endgroup\$
    – Dampmaskin
    Apr 28, 2017 at 11:49
  • \$\begingroup\$ For unusual materials like this, I'd normally recommend crimping. \$\endgroup\$
    – Hearth
    Apr 28, 2017 at 12:11

3 Answers 3

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Assuming you need a Tungsten wire for high temperature heating, then :

Use a tiny copper pipe, hose and crimp to the filament ends. Screw or solder the copper terminals to PCB or whatever you need. In such way you will have a good contact which won't excessively heat when the filament will be turned on. In place of copper pipe you can use also a wrapped copper foil, but firmly crimping the copper will give best performance.

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I would first look at welding under a microscope using a tweezer handpiece.

http://www.amadamiyachi.com/products/resistance-welding/rw-accessories/thp#spec-page

If you don't have access to such a welder with fine low current control, contact the makers and they should be able to help you. The machine should be under $10K for a good one.

You could also consider using a platinum plated tungsten wire, which would be more resistant to corrosion and easier to deal with. They are used in some kinds of instrumentation.

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A small spot welder of the type used for thermocouple wires? I believe Omega sells systems like this.

Tungsten can also be soldered (at gas-torch temperatures) using silver-based "hard" solders and fluoride-based silver-solder flux.

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