How long does it tkae for Tin-Lead solder to rust if put outside

The short answer is immediately after reflow the problem occurs. To be more exact, what you are describing is not "rust". Rust occurs in iron. The oxidation that occurs in Tin-Lead has been sometimes called "white rust".

Either way, oxidation occurs immediately after exposure to oxygen. You are suggesting the potential for environmental conditions that will affect your PCA. Depending on the severity, a no-clean process can be a conformal coating like protective barrier that will greatly reduce the oxidation. If a harsh environment is to be experience, the answer to prevent the oxidation would be conformal coating.

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Yes of course,

From Wkipedia:
"As rust has higher volume than the originating mass of iron, its buildup may force apart adjacent parts - a phenomenon known as rust smacking."

The smacking formula is as follows; again from Wikipedia:

"Fe(s) -> Fe2+(aq) + 2e-
"harply, but this is of no consequence since OH- ions are always present, even in pure water.) The cations then react with the OH- or even the H+ ions and dissolved oxygen to form a variety of compounds, which constitute rust:

Fe2+(aq) + 2OH-(aq) -> Fe(OH)2(s)

4Fe2+(aq) + 4H+(aq) + O2(aq) -> 4Fe3+(aq) + 2H2O(l)

Fe3+(aq) + 3OH-(aq) -> Fe(OH)3(s)

From the above equations, it is seen that the pH and amount of dissolved oxygen can affect the outcome of the reactions. In water with limited dissolved oxygen Fe3O4(s) is formed, which is a black solid and commonly called lodestone:

6Fe2+(aq) + O2(aq) + 12OH-(aq) -> 2Fe3O4(s) + 6H2O(l)

The porous Fe(OH)3 rust can slowly disintegrate into a crystallized form, which is the familiar red-brown rust:

2Fe(OH)3(s) -> Fe2O3�H2O(s) + 2H2O(l)

Iron oxide (FeO) can also be formed. The presence of other ions, such as calcium or calcium carbonates reacts with the iron hydroxides and iron oxides to form a variety of precipitates. Other metals corrode via similar chemical processes."

Now we got the other variable you called "tin-lead-something" to put into the equation:
The short answer to this is: yes, it will take some time, more than a while...

Best Regards, Mika
Ps. If you are going to solder something to be exposed "outside", concider to glue the whole thing. Maybe some other nice fellows at this forum can tell you how. Ds.

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A simple answer is never. Tin lead will oxidize when exposed to oxygen, but it will not rust away like normal steel. I have old equipment from the 1920�s and 1930� that have solder joints as robust as the day they were made. Maybe not as shinny, but far from where this thread was going.

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So, a test probe from ICT will not make solder rust?

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The simple answer is probably a lot longer than it'll take for it to short circuit due to moisture of some sort bridging two conductors. I say moisture of some sort because it doesn't necessarily have to be liquid water. A slug will do nicely.

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Dang back button!

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