Mike B someone@noplace wrote in
:

On Sun, 14 Oct 2012 08:54:28 -0400, "Steve W."
wrote:

Mike B wrote:
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.

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