View Full Version : silver/copper/phosphorus brazing strips

12-02-2014, 12:36 AM
Hmm, I see as I'm typing the title I've gone here before-

I've wanted to try this brazing strip as a contact material, and now I bit the bullet and bought some. Being brazing strip, it has 15% silver, mostly copper, and 5% phosphorus. So tonite I played with it. First thing I did was to try bending it in my new bender, and it snapped. Obviously it's quite brittle. It cut well in the shear, so I cut a few bits and soldered some bare copper around each piece. It takes solder like a hot damn as they say. Then I have my power supply on and an electric motor as a load, and I repeatedly make and break the circuit lots of times to see if I can detect a poor connection at any time. Seems like only a very light touch is required to get a good low resistance connection each time. There was a bit of sticking, but very little. The material is hard, so it would seem that it would take repeated wiping of contacts reasonably well. I know that a high temperature alloy or layer would take arcing better, but this is the experiment, and I think it turned out well. Pretty crude as far as test methods go, but it seems better than copper to copper, and better than brass. I think I'm going to be making contact points out of this for times when I need to make up a multi-pole switch, etc.

I'm sure I can braze with it as well :)

12-02-2014, 01:06 AM
Think your right, a funny thought popped into my head, the current connectors that overhead cranes and gantries use are copper or copper alloy, they are called shoes, they look like big heavy chisel soldering iron bits with a bolt hole and slide along the "rails" as they call them, one of those old shoes, as they get changed frequently would make dozens of contacts.

J Tiers
12-02-2014, 08:41 AM
That "Sil-Phos" material is somewhat self-fluxing in many cases, and may weld when used as a contact. It is, after all, intended to be used to join metal.

Don't let the brittleness fool you. When used for brazing, the brittleness from the phosphorus tends to disappear as the phosphorus is driven off in dross, while the copper/silver base material is ductile and strong.

loose nut
12-02-2014, 08:45 PM
Only downside is it shouldn't be used in a sulfur atmosphere IE: combustion area with sulfurous fuel.