[TenTec] Soldering PL-259s and gold plating

[Dave Haupt]

I work in a company that does lots of connector work - some for satellite and aero.

Gold plating's main purpose in a soldered situation is to serve as an oxidation barrier to nickel.  If you look at the metallurgy involved, the gold is 99% of the time plated over nickel.

When you solder to gold using a tin-bearing solder (either standard tin-lead or 96.5%Sn, 3%Cu, 0.5%Ag, which is the standard lead-free formula), the gold leeches into the solder and forms gold-tin intermetallic compounts.  The solder has actually made its way through the gold onto the nickel.

On a contact surface, to which you do not solder but you depend on pressure connections, the two benefits are that gold is soft, so the two surfaces press into each other, increasing contact area and decreasing resistance, and that gold oxidizes more slowly than most other metals.

I have never seen a PL-259 with a gold-plated body, and that's the crucial part, for the soldering discussion.  Electrical-grade gold is actually more pure than jewelry-grade gold, and is difficult to get right.  If those connectors cost less than $30, I would be doubtful that it's a good grade of gold.  On the other hand, Amphenol PL-259s with silver plated bodies are commonly available for under $10, and I'm confident in that brand name.  And they solder very well.

73,

Dave W8NF