Heatsink Staining

[nomdeplume]

Ripped apart every computer in the house, working or non, to get experience removing/replacing TIM. All were heavily used daily for multiple years with little care other than very occasional dust removal. Three of the laptops had near zero coverage on the processor. After all the melting and chiseling and melting and chiseling, anywhere on the copper heatsink that had TIM was heavily stained. Scorched more likely.

So the question is if there is a way to remove this or if it even has any impact on cooling (at this late and uncorrectable stage)? If there is some restorative measure I can take it would be helpful for future encounters. Abrasive pads, sanding, chemicals, surely some of you meet as bad or worse than what I managed to do.

 

[Solaris17]

The staining even extreme staining caused by liquid metal doesn't deteriorate the cooling performance. Im not talking about the residue etc, just specifically the stain remaining after a proper cleaning. As for "restoring" it back to its former glory, its really not necessary since its purely cosmetic, but if you really are inclined to do so 2000+ grit sand paper will finish the surface very nicely and improve cooling performance depending on how bad the factory mill of the surface was.

 

[nomdeplume]

My concern was that before replacing thermal paste you want to get every remaining trace out of the microscopic irregularities in the surface. On the other hand copper does discolor. Without fairly significant assurance I could go at the heatsink with a specific abrasive I won't worry about it. Nobody is really interested in using a Celeron M 370 laptop with more keys missing than present.

 

[RejZoR]

I always use only toilet paper to wipe off the thermal paste and then regular A4 80g paper to polish it. Only time I used actual sandpaper was when I lapped the Thermalright's TRUE cooler.

Actually, I lied, I used alcohol wipes for application of Conductonaut. But just because you need to get everything off for it to even stick to surface and because they came with it.

 

[nomdeplume]

Thanks both, I'll store all this away in case I ever need it. Copper is pretty soft so the A4 idea might get tried out sooner than later.

 

[RejZoR]

I usually just place it on a glass or some flat surface and just pull the base few times on it in all directions and it's done (if base is truly flat).

It also works by simply tearing off a small piece, place it on a finger like you would a rug or paper towel and just polish the surface hard with one finger. It's gritty enough to polish it nicely. Also, no mess and you always have this stuff around home for sure.

 

[Bill_Bright]

I could go at the heatsink with a specific abrasive

Abrasive? No way! Don't do that.

I use a clean, very fine microfiber cloth (as used to clean eyeglasses) and 91-93% isopropyl alcohol to thoroughly clean the mating surfaces.

I would not worry about any discoloration seen after cleaning.

If I really wanted to polish, I would NEVER use paper, even toilet paper. Would you use A4 paper on your eyeglasses, monitor screen or camera lens? I would stick with the microfiber cloth and maybe some lens cleaner or just plain demineralized water.

If I really really wanted to polish that surface to get rid of coloration (and I wouldn't), I would use my clean thumb with a tiny dab of plain white tooth paste. Then rub the surface in circular motions completely, then clean it completely again with a clean, very fine microfiber cloth and 91-93% isopropyl alcohol.

Note plain white toothpaste (NOT gel) works wonders to polish out tiny scratches in things like watch crystala, DVDs and other things too.

Do not use the commonly available 70% isopropyl (rubbing) alcohol as that leaves a film residue. You can find the 91-93% stuff at your local pharmacy.

But again, I would not worry about discoloration assuming it is not due to extreme corrosion that can eat into the surfaces. In that case, I would throw the heat sink away.

 

[sneekypeet]

I clean bases of coolers with Eagle One Never-Dull all the time. Of course, I also clean with alcohol after to remove the leftover chemicals from the polish.

 

[newtekie1]

I've removed the staining, as well as other imperfections, by giving the heatsink a quick lap with 1500 grit sand paper. I do it often when replacing TIM on laptops, because some of the bases on those coolers look like they "polished" the base with a rock.

 

[Solaris17]

I've removed the staining, as well as other imperfections, by giving the heatsink a quick lap with 1500 grit sand paper. I do it often when replacing TIM on laptops, because some of the bases on those coolers look like they "polished" the base with a rock.

lol "lets just drag this across the parking lot real quick".

 

[newtekie1]

lol "lets just drag this across the parking lot real quick".

Seems accurate!

 

[AsRock]

If it's really bad you could try ArctiClean, but rubbing alcohol should even do it.

http://www.arcticsilver.com/arcticlean.htm

 

[nomdeplume]

I've removed the staining, as well as other imperfections, by giving the heatsink a quick lap with 1500 grit sand paper. I do it often when replacing TIM on laptops, because some of the bases on those coolers look like they "polished" the base with a rock.

Exactly. If I'm having to use the slightly rounded edge of a stiff piece of plastic to chip dried remnants off. It cannot be anywhere near smooth. There is enough texture for it to have somewhere to grab onto pretty strongly. Considerably more than a well ground base that purposely was left unpolished would have. I was picking up flecks of metal in with the chunks of dried on paste cleaning one of the heatsinks. That means there was weak exposed metal the paste ripped off. Plastic is softer than metal and cannot cut or scratch it without considerable pressure being exerted. This was mixed in with shattered paste from somewhere the plastic never touched.

Paper is probably a great material you would really have to go at copper hard with to damage. Very fine grit sandpaper would remove particulates and any other obstructions with one or two light passes. The answer I actually expected was a specific plastic based abrasive pad. Being synthetic and highly engineered they can cut, lift, and polish in one pass. You would still need to clean it with alcohol and wipe with a cloth. Burnishing with a final polish basically.

 

[phanbuey]

Ketchup.

 

[nomdeplume]

If it's really bad you could try ArctiClean, but rubbing alcohol should even do it.

http://www.arcticsilver.com/arcticlean.htm

I was using 91% alcohol. After the surface is clear it still isn't clean. I soaked it for a couple minutes and then rubbed at it with a lens cloth for a couple more. This is buried in the small surface valleys a cloth won't reach into.

Ketchup.

Naturally occurring acid, interesting.

 

[sneekypeet]

Ketchup.

While it does tend to lift some of the oxidation, many cycles are needed (rinse and repeat coating it) to get good results. It also matters what you rinse off the ketchup with, as tap water will oxidize the surface again anyways. Tried this years back on an old 939 Zalman (CNPS9500) CPU cooler. It sort of worked is the best I can say about it. Although, maybe the brand of ketchup I was using could have played a factor in its lack of impressing me for the work I had to do.

@nomdeplume Some of that pre-applied garbage is a real pain to remove. I recall this from the days of 939 chipset cooler replacements. Best you can do it attempt to dissolve the TIM with chemicals. I wouldn't go to lapping just yet, as even with some form of block or the paper taped to a table, the bits left on the heatsink will likely shift the base out of line, causing the base not to ride level against the surface you are lapping it on. Go easy on the chemicals too IMHO, start with something like Electronic Component cleaner, then if that don't work, try things like WD40 or maybe Automotive Brake cleaners. Alcohol can work, maybe soak it in some for a while and see what happens.

 

[Bill_Bright]

That means there was weak exposed metal the paste ripped off.

No it doesn't. It means something gouged out chunks (microscopically speaking) of metal. Not good. If there was "weak exposed metal", that would suggest a manufacturing defect and a lack of quality control before it left the factory. Or something very corrosive came into contact with it after sale. Not good either.

I hope ketchup was a joke. I would never use it on a surface that is supposed to be perfectly smooth because it is, as noted, acidic.

 

[nomdeplume]

Toothpaste is acidic.

I certainly have enough test subjects laying around I might pull some of them back open and go from least to most aggressive solutions until I see a noticeable change.

 

[hat]

Those type of stains aren't harmful. As mentioned before, the best way to get rid of it is with some really fine grit sandpaper. Lapping a heatsink though, or a CPU, is a different matter. You typically need many grits of sandpaper, usually starting at 400 and on up to whatever finish you desire. You generally start by securing the paper to a very flat surface, such as glass. The lower grit paper is used to "quickly" remove material, trying to get the surface as flat as possible. Once it's flat, then you would go up to 800, until the markings from the 400 paper are gone, then maybe 1500 until the markings from 800 are gone. You can go above 1500, but I find little to no benefit in doing so, so I would stop at 1500. You can also introduce water to the process. Especially for big heatsinks, it helps remove some of the resistance that comes from pushing the heatsink against the sandpaper. Too much resistance and you're more likely to be applying uneven pressure, thus making the surface uneven. Just be sure to get sandpaper that can withstand getting wet, like 3M wetordry.

 

[newtekie1]

Paper is probably a great material you would really have to go at copper hard with to damage. Very fine grit sandpaper would remove particulates and any other obstructions with one or two light passes. The answer I actually expected was a specific plastic based abrasive pad. Being synthetic and highly engineered they can cut, lift, and polish in one pass. You would still need to clean it with alcohol and wipe with a cloth. Burnishing with a final polish basically.

Damaging the copper isn't a huge concern if you do things right. Maybe it is because I remember the days of lapping heatsinks. Sometimes you'd have to start with 400 Grit because the bases were that warped! But really, taking a little copper off is not going to kill a heatsink. There is plenty of material there to spare. Using a 3M scotch brite pad to clean as much off of the surface as you can first would probably be a good idea, and won't remove any copper, but it also won't get rid of the staining. Then doing a few lapping passes with 1000 or 1500 grit sand paper to smooth the surface and remove a small layer of copper to help get rid of the staining. Or even better get yourself a 1500 grit sharpening stone. It's a lot easier to use a sharpening stone than sand paper, it already is a damn flat surface, and the silicone base holds it in place. Just remember, no matter if you are using sandpaper or a sharpening stone, you need a small bit of water on the paper/stone to make things slide easily and not skip around.

I've even lapped direct touch heatpipes before, that is really the only time you really do have to be careful about not taking too much material. The heatpipes tend to be thin, and usually the machining of the base has already removed some of the heatpipe wall material making them even thinner. I haven't ruptured a heatpipe by lapping, but I know people have.

 

[hat]

Good point @newtekie1 it's been a long time since I lapped anything, forgot about that skipping. Also forgot to mention that bit about the HDT coolers... personally I wouldn't bother lapping an HDT cooler for that reason, but lapping the chip could still be a good idea.

 

[Totally]

Damaging the copper isn't a huge concern if you do things right. Maybe it is because I remember the days of lapping heatsinks. Sometimes you'd have to start with 400 Grit because the bases were that warped! But really, taking a little copper off is not going to kill a heatsink. There is plenty of material there to spare. Using a 3M scotch brite pad to clean as much off of the surface as you can first would probably be a good idea, and won't remove any copper, but it also won't get rid of the staining. Then doing a few lapping passes with 1000 or 1500 grit sand paper to smooth the surface and remove a small layer of copper to help get rid of the staining. Or even better get yourself a 1500 grit sharpening stone. It's a lot easier to use a sharpening stone than sand paper, it already is a damn flat surface, and the silicone base holds it in place. Just remember, no matter if you are using sandpaper or a sharpening stone, you need a small bit of water on the paper/stone to make things slide easily and not skip around.

I've even lapped direct touch heatpipes before, that is really the only time you really do have to be careful about not taking too much material. The heatpipes tend to be thin, and usually the machining of the base has already removed some of the heatpipe wall material making them even thinner. I haven't ruptured a heatpipe by lapping, but I know people have.

If the base was rough, I'd have no qualms recommending sandpaper but to me personally it doesn't make sense to mechanically remove a layer of copper for a bit of tarnish that can easily removed with some salt and vinegar or dozens of other solutions specifically for restoring copper finish.

 

[nomdeplume]

So a few of you have convinced me how good we have it now. At least in regards to cooling products being finished to a higher level. Done more complete resurfacing of other items than I care to remember. Would be a pretty physically demanding way to needlessly remove a couple thousandths of industrial byproducts repurposed as TIM in the prebuilt factory.

 

[hat]

It's never been a necessity, but it was good for those of us who wanted to push the boundaries of overclocking or just run a bit cooler by getting... 5c cooler on average? More improvement the worse your CPU and/or heatsink was to begin with.

 

[newtekie1]

Good point @newtekie1 it's been a long time since I lapped anything, forgot about that skipping. Also forgot to mention that bit about the HDT coolers... personally I wouldn't bother lapping an HDT cooler for that reason, but lapping the chip could still be a good idea.

In my case it was a a Xigmatek cooler that had a big gouge in one of the heatpipes. It was big enough for my thumb nail to catch and stick in it. I lapped it to get most of the gouge out, but didn't get all of it. It was a lot better though.