On Sunday, May 1, 2016 at 10:01:04 PM UTC-4, Phil Allison wrote:
wrote:

MJC wrote:

I thought that gold was tricky to solder precisely because it did tend
to dissolve unless the solder was already loaded with gold.

Not really. Gold is also somewhat lubricious - and things flow well on it. BUT, they do not STICK well to it. Solder will flow and appear to be nice and tight, until it peels off like cheap tape. But it takes more than heat to cause gold to dissolve.


** In fact gold dissolves readily in tin and hence solder.

Normally, gold plated parts have a nickel underlay which does not readily dissolve to form an alloy with solder. This results in joints that have poor mechanical strength.

https://en.wikipedia.org/wiki/Gold_p...ldering_issues

http://www.indium.com/blog/intermeta...-soldering.php


.... Phil

Phil:

Jewelry grade gold electroplate uses a three-metal process, first copper, then nickel, then gold. Electronic plating for other than switches and mechanical connectors DOES NOT go through this process as it would be far too costly, take too much time and often add too much thickness. We are discussing microns here, and they matter. Nor is appearance a concern. For flash plating electronic solder connectors, the gold is deposited directly on the copper.

http://download.springer.com/static/...e5a9 65d0d81b

Is a link that will take you to an article on how gold operates at/less than one micron of thickness - whereupon you are correct, and at greater thicknesses, where the solder simply does not stick.

Gold is a wretched soldering base for electronic purposes using traditional tin-based solders. As I stated previously, for any number of reasons, some not obvious.

Peter Wieck
Melrose Park, PA