I need to join a 316 stainless steel tube to a copper plated fibreglass circuit board which can only withstand lead tin soldering temperatures (180 C). . If I 'tin' the stainless using silver solder (Weldcote Metals 50 N) will I be then be able to use 60/40 tin/lead solder to join it to the copper?
If that isn't going to work then I'll have to silver solder a copper ring around the tube then solder to that.
Mike
Why? Take the stainless tube. Clean it VERY well on the end. Use a stainless wire brush and while you brush the stainless use regular solder to tin the stainless. Then solder as normal.
I've had zero luck soft soldering stainless with 60/40. Years ago I tried a silver based soft solder and that didn't work either.
Mike
Mike B wrote in news: snipped-for-privacy@4ax.com:
It works fine if you have the right flux. I used to solder to stainless RF connectors all the time, using a small bottle of clear liquid flux. Unfortunately, I don't remember the brand or name of the stuff. The catch is that it is an acid, and it boils & spatters when you solder with it. It eats soldering iron tips, and the spatter will corrode everything in sight. It's best to have a separate iron & work in a well protected or separate environment from whehre you do most of your work. And definitely wear safety glasses!
I got tired of the hassle, and now only specify gold plated connectors, which solder without any trouble.
Doug White
It's called Tinners Flux, and is made and sold under many names, and some kinds are specialized for use on stainless steel (usually because the flux has some Phosphoric Acid in it), but I've used ordinary hardware-store tinners flux on stainless without difficulty.
Careful mechanical cleaning of the steel to be soldered is always helpful.
Joe Gwinn
On Sunday, October 14, 2012 7:14:47 AM UTC-7, Doug White wrote: [ soft-solder to stainless steel]
It takes an acid flux to solder nickel or nickel alloys, like stainless. I use Nokorode liquid flux and it's acid and somewhat sticky, and one does NOT want to keep it near the fine tools or next to delicate metal items. There's fumes, I suspect; nearby objects corrode.
The acid flux also works well on brass, and it's how to make a good solder connection to a battery (NiCd or the nickel-plated ends on a AA cell).
Yes, it will work ok.
Kristian Ukkonen.
Stainless has the same trouble as tinning aluminum, it has an oxide coating. So the same answer exists to tin it. Heat it up, submerge it in molten solder and scrub the surface under the solder with a stainless brush until satisfied that it's well tinned. Wipe off excess and sweat to your other piece. You'd have the same trouble using silver braze except that fluxes intended for stainless will remove the oxide layer for you so the brazing filler can wet the surface. As far as sticking lead/tin solders to brazing filler, I'd have no idea. I imagine it would work, depending on the filler. High copper-content fillers would probably work best.
Stan
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