Oxidize on Copper Heatsink

[Jittos]

I'm sure this has been discussed before, but I did a search and did not find anything.

Over time, the part of the copper heatsink that has contact to air oxidize and turn ugly brown or green. How does this affect the performance of the heat sink, if at all?

Please educate me.

Thanks,

 

[oynaz]

If I recall correctly, the thermal properties of copper is indepedent of whether it is oxidized or not. I will dig out my old book on the subject and have a look.

 

[farmercal]

It won't

 

[Jiggz]

Oxidation should not affect the hs performance but then of course, depending on the thickness or buildup of the oxidation. When the oxidation is starting to show scaling or scabbing, then it will start affecting the heat dissipation capability of the hs.

 

[Susquehannock]

When talking heatsinks there is a little thing called "film resistance".
Basically the resistance of the surface to transfer heat to the surrounding
environment.

As Jiggz said a little oxidation won't matter much. But the more you have
the higher the film resistance value.

BTW .... you can remove that oxidation with a little ketchup or vinegar.

For a really quick job combine vinegar & table salt.

Here's a bit of chemistry .....
Since table salt (NaCl) combines with acetic acid in the vinegar to produce
Sodium Acetate and Hydrogen Chloride. Hydrogen chloride is a strong acid
which combined with sodium acetate rapidly cleans the surface of your heatsink.
Just be careful not to soak it too long.

 

[StrangerGuy]

I wouldn't care about a mere 1 to 2 degree increase in CPU temps due to oxidation.

 

[GalvanizedYankee]

The OP says, ugly brown and*green*.

TY for posting a chemistry lesson Susque. Aside from what he offered, heavy oxidation
will collect dust much faster. Providing a lite sweater for the sink.

I did read, hot vinegar+salt or hot lemon juice+salt works well.

The one nasty copper sink cleaning I did was fast&fun. Pre-heated the sink in hot water,
sprinkeled it liberally with Tabasco, work it in with a small paint brush, hot rinse, let dry.
Works great.
I do wear glasses so none got in the eyes


...Galvanized

 

[Boyo]

Wow. That was a great lesson, Susquehannock. I'm actually glad that came up, because I don't think I would have even paid attention to it in my case.

 

[Jittos]

Thanks all the for replies. Very good info.

 

[Ivan05]

Its possible that IF (and that's a mightly big if) the fins on the hs are thin enough and IF the corrosion is also severe enough, the fins may eventually disintegrate. Like I said, its a mighty big if. I know it would have to be pretty severe and go unchecked for a long time before it would become a problem, but not knowing the environment that this particular machine is in, it is possiblity.

Does anybody who's smarter than me know, would the repeated expansion/contraction from the hs heating/cooling as the machine is turned on/off lead to an increase in the rate of corrosion?

 

[Zepper]

Deoxit from Caig labs will also remove oxidation or corrosion from most metals. It's not free, but it has thousands of uses... Big spray cans of it often show up on eBay for a decent price.

.bh.

 

[Susquehannock]

Originally posted by: Ivan05>>>>
Does anybody who's smarter than me know, would the repeated expansion/contraction from the hs heating/cooling as the machine is turned on/off lead to an increase in the rate of corrosion?

Not sure about contraction/expansion, but heat would definitely have an effect on the rate of oxidation.
Afterall, heat is the ultimate catalyst.

 

[Howard]

Originally posted by: Ivan05
Its possible that IF (and that's a mightly big if) the fins on the hs are thin enough and IF the corrosion is also severe enough, the fins may eventually disintegrate. Like I said, its a mighty big if. I know it would have to be pretty severe and go unchecked for a long time before it would become a problem, but not knowing the environment that this particular machine is in, it is possiblity.

Does anybody who's smarter than me know, would the repeated expansion/contraction from the hs heating/cooling as the machine is turned on/off lead to an increase in the rate of corrosion?

I think copper oxidation is much more benign than iron oxidation in that it doesn't result in the loss of material. Rust flakes off, but AFAIK, the green oxidized copper doesn't.

 

[Susquehannock]

Originally posted by: Howard
I think copper oxidation is much more benign than iron oxidation in that it doesn't result in the loss of material. Rust flakes off, but AFAIK, the green oxidized copper doesn't.

The "oxidized" copper may not flake off like rust, but make no mistake, the pure copper atoms
are still being combined with something else. Whether or not that constitutes "a loss of material"
depends on your definition.

Copper Oxide is dark bluish black and the result of a reaction with oxygen, thus "oxide".
While the green is a reaction with sulfur. Either from salts &/or oils in your fingerprints, or from
sulfides in the air.

 

[Jiggz]

So the bottom line, after "marinating" the thing with salt and vinegar and thoroughly rinsing it and the oxidation is still there or reoccurs in a more frequent and maybe worse than before, then it's time to get a new HS.