Caring for your disabled heatsink

[ivor]

I'm pulling laptops apart and cleaning them up.  Sometimes they are just filthy inside.  On some of them the heatsinks are totally choked and there's some sort of reside on the heatsinks which I assume is tar from cigarette smoke.  I dunno, that's just a guess.  Anyway, I'd like to dunk them in something to clean them off.  Maybe something acidic, rinse them in water and then dip them in some sort of chemical to protect them or at least keep them from corroding.  What should I use? Usually they're copper or at least some sort of copper alloy.  Other times they appear to be aluminum.

[Swatopluk]

If it's aluminium, don't use isopropyl alcohol or glycerol. Organic filth is usually resistant to most chemicals and those that would work tend to be nasty. Scrubbing will have to do 90% of the work, supported by some surfactant (be careful with ionic surfactants again, if it's aluminium).
Is pressurized hot water an option (with a small amount of detergent mixed in)?

[Aggie]

The best thing I've found for cleaning really egregious grease is citrus oil or a cleaner based on it.  It might not be safe for aluminum and will destroy many plastics, but some of the citrus-based cleaners are a bit more mild. 

Straight-up orange oil will take off all sorts of ugly gunk, and usually part of what you're cleaning with it.

[ivor]

Thanks guys!

I can't use a whole lot of pressure or I might bend the fins but will try detergent and hot water on the aluminum.  I'll try diluted orange oil on the copper ones.  Of course I'll try it on one I don't intend to reuse first.

How about a protective coating?  Something that wouldn't attract dust or lint?

[Swatopluk]

How hot do these things get? A lot of potential coats would not stand much heat (and maybe work as insulation)

[Bluenose]

I've cleaned out a fair few heatsinks like this in my time.  I generally don't worry too much about anything other than the dust clogging the fins.  I suspect that attempting to clean anything that's coated the metal is likely to make more trouble than it wil save.  In my experience simply allowing air flow to return seems to be all that is required anyway.

[Sibling Zono (anon1mat0)]

How hot do these things get? A lot of potential coats would not stand much heat (and maybe work as insulation)

Generally it will go from the 50s C to 90s C, depending on model/load.

[ivor]

I'm just worried that if I clean them with a chemical they'll corrode later.

Yeah, they get pretty dang hot so may not be much I can do for a coating...

Wasn't there some trick people used to do with radiators.  Something like put a charge on them to keep them from corroding? That would be hard though as I imagine most are connected to the ground in one way or another.

What I need is something like a little filter to clip on to the intake vent like or stick on with a removable washable filter kinda like my Antec tower chassis has.  That would be easier.

[Aggie]

Aluminum doesn't need a coating as it makes it's own.  Provided you rinse off whatever chemical you're using thoroughly, I don't think you should cause too many problems.

PTFE (Teflon) would take the heat range and help with the dust, but I'm not sure how to bond it to the metal in a non-industrial setting.

Putting a charge on the heat sink would probably be a bad idea in context of computer internals, and you'd need something to catch the dust anyways.  Charged dust particles get stuck to the charged plates in that kind of setup, but I think you can optimize them to go one way or the other (can't recall if it's the cathode or anode).  You could presumably set up this kind of a system on the way in to trap dust, but it'd clog eventually.  Better to use some sort of filter like you suggest.

I should clean out my PC - it sits on the floor and gets full of dust.  I think that's why my last one died.... thanks for the reminder!

[ivor]

Yeah, if you look you can find cases like mine that have the built-in filters.  I can service any laptop now.  Mostly they are choked with dust and I can tune them up for around $100 to $200 or so and make them run 5-10 times faster than they came stock if it was bought with bottom-end configuration.  Most all of them I get are.  They hold their value if you do upgrade them.

Thanks everybody!