Replacing notebook thermal pads with copper

Discussion in 'Highly Technical' started by Zxian, May 9, 2012.

  1. Zxian

    Zxian Senior member

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    I'm typing this on my Thinkpad X120e netbook, which I love in terms of it's performance, battery life, and overall usefulness, but there's one small thing that's niggling at me. The fan is almost constantly running, even when it's sitting here doing nothing. The power draw of this laptop is about 15 watts, most of which is going into the screen backlighting, so there's no real reason why the APU should be idling at ~60C. I've tried TPFanControl as well, but the "Smart Fan 1" setting still has the fan running and has a far worse behaviour than the BIOS fan control as soon as the temperature does rise (fan toggles from high to low constantly).

    After a bit of digging, I managed to find the hardware maintenance manual from Lenovo. On page 77, it describes the thermal rubbers that come with a replacement heatsink/fan assembly. I've dealt with other laptops that used these rubber pads before, and manufacturers often rely on their thickness to fill the gap between the heatsink and the CPU/GPU/APU. I was thinking of removing my existing heatsink, and adding a copper shim (with TIM top and bottom) to fill the gap.

    I was hoping that someone might have some insight as to whether this would help my laptop cooling scenario. I'm also wondering if I would have to take any additional precautions to prevent the shim from moving (thermal adhesive to the existing heatsink?) or if the pressure of the mounting system would/should hold it in place.
     
  2. serpretetsky

    serpretetsky Senior member

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    no experience, but if you do it tell us how it works. I've considered doing this on the crappiest designed hp on earth before.

    You may still consider using a smaller amount of that rubber pad in case the chip is making direct contact with part of the laptop case. That way if the laptop takes a knock the impact doesn't translate directly to the chip. If the chip is simply making contact with some internal cooling mechanism it probably wont matter.
     
  3. A5

    A5 Diamond Member

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    You'll probably want to use a TIM with epoxy-like features to ensure that a knock doesn't take out your shim and fry the laptop. I think Arctic Silver used to make something like this for RAMsinks - they may still make it.

    I also don't think it will help performance that much, but I'd be interested to see your results if you do it.
     
  4. SpatiallyAware

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    We tried this with a couple of Dell D630 that were known for overheating issues. IT removed the heatsink and it was only touching in the middle.. Someone had the idea to use the copper shims from some other heatsink, basically CPU > thin Thermal Paste > copper shim > soft pad > heatsink


    Long story short the temp issues and fan speeds were the same. They ended up ordering new replacement heatsinks from dell that had 'new' soft pads which solved the entire problem.
     
  5. Zxian

    Zxian Senior member

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    @SpatiallyAware - In the situation you described, you were still using the existing thermal pads, correct? I'm thinking that copper likely has a higher thermal conductivity than the bit of stuff that's there (I don't know what the material is). If I can eliminate the thermal pad altogether, then my overall heat dissipation might improve.
     
  6. serpretetsky

    serpretetsky Senior member

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    good point, i think i would only epoxy the side attaching to the heatsink-shim though, and then regular thermal paste or thin pad the chip-shim contact.
     
  7. imagoon

    imagoon Diamond Member

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    As thin as it is, it isn't going to be drastic. Also even polished to a mirror like finish, you will need a compound to fill in the surface area cracks you can't see. In most cases I have worked with, the pads were there to fill in poor tolerances in the heat sink.
     
  8. Zxian

    Zxian Senior member

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    Yes. If you re-read my original post, I did indicate that I was planning on using thermal paste between both the shim and the existing heatsink and between the shim and the APU.

    My point is that the thermal conductivity of these pads is questionable at best compared to TIM. What I'm unsure about is whether or not the overall thermal conductivity would improve with the "5-layer" solution of die-paste-shim-paste-heatsink compared to the "3-layer" solution of die-pad-heatsink.
     
  9. imagoon

    imagoon Diamond Member

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    My point was that the shim is so tiny it will be minimal even preped well beyond "normal." Most laptops the issue is the contact surface and the crappy accuracy of the machining.
     
  10. wirednuts

    wirednuts Diamond Member

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    my mom has an hp laptop that has had overheating issues since day 1. i plan on opening it up this sunday and seeing if i can at least repaste the heatsinks... or find some way to get it to cool properly. damn thing overheats on web browsing
     
  11. imagoon

    imagoon Diamond Member

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    A lot of that is what I am talking about. For example there was the Compaq 1700 series. Some of the heatsinks we would get to do repairs had enough space that you could bolt the heatsink over the CPU and slide sheets of paper between them. Compaq also used "super thick" pads.
     
  12. Zxian

    Zxian Senior member

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    @imagoon - That gap you're describing for the Compaq laptops is precisely the point of the copper shim - to fill the space between the heatsink that is not flush with the die. I've found that those laptops that use thermal pads instead of thermal paste require the thickness of the pad in order to make any sort of physical contact between die and heatsink. The finish or machining quality of the heatsink has nothing to do with this.
     
  13. wirednuts

    wirednuts Diamond Member

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    well i know on my netbook the heatsink is a sprawling metal plate, and when i had this thing open to work on it i scraped off the shitty spongy crap they used and put my own paste on it. i also physically bent the plate by bowing it out... so when i put everything back together there was much more pressure on the dies (cpu and gpu). the result was dramatic, and 2 years later this thing still stays cool to the touch, while spitting out hot air from the side vent. as it should be.
     
  14. imagoon

    imagoon Diamond Member

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    Yeah but the main issue [besides the gap] was the surface also not being true. The pads would often melt / burn in the middle but the edges didnt touch. Basically you would have needed to machine the heatsink flat then add a shim other wise the contact area was 1/4 -> 1/3 of the core.
     
  15. PlasmaBomb

    PlasmaBomb Lifer

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    I think it was called Arctic epoxy. 100% Arctic epoxy is permanent, 50% epoxy 50% AS5 was supposed to be semi permanent (you could remove it if you really really tried...).
     
  16. SpatiallyAware

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    From what I recall, the heatsink had 'arms' where it touched the GPU and CPU, and yes they left the pads on.

    There would be no way whatsoever to get a copper block to lay flat on both die locations. Even if you could, a bump in the wrong place would likely crack the die. In this case, it seems like the CPU had 4 screws and was directly attached to the heatsink but the GPU part just brached out with nothing holding it down.


    I would imagine that the OEM would've used copper blocks if it made more sense to do so.
     
  17. mindless1

    mindless1 Platinum Member

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    I have done this to an HP DV6000, it's one of the models that had the notorious nVidia IGP overheating to cause solder ball cracking, issue.

    Well, actually HP replaced the mainboard when it failed and the first thing I did when I received the replacement, after taking temperatures and confirming it worked, was to replace a rather thick silicone impregnated thermal pad over the chipset (left the thin CPU pad as-is) with an old all copper penny lapped flat and polished on both sides.

    It did reduce the temperature of the chip by about 10C though it varied since the fan speed was tied to CPU temperature not IGP... which is likely one of the original problems that made it run so hot in addition to the thick stock thermal pad.

    I also lapped the heatsink assembly itself over the mating area and lastly polished it with Arctic Ceramique (sp?) thermal paste as it is abrasive and if any micro gaps remained, they'd be filled with a mixture of the metal polished away and the thermal grease. The result was it required very little thermal grease to get complete contact on both sides of the penny, what little I applied squished out the sides.

    Once it was screwed down I poked at the penny to see if it seemed like it would remain in place. It didn't budge so I decided to leave it like that instead of using thermal epoxy since the epoxy has a lower thermal transfer coefficient. Originally I had thought about soldering the penny onto the heatsink with a blow torch and solder paste but I was concerned that might be problematic as the design of the heatsink had a copper heatpipe already soldered to the metal heat spreader plate directly above where I'd be soldering the penny, odds seemed too high it would fall apart during the process of soldering.

    Just to be cautious, I also put a piece of adhesive backed foam around the die of the chip with a hole cut out in the middle - just in case the penny ever did start to slip. I don't know the best place to get the foam I used nor what it's called, it was a sample pack handed down to me a few years ago.

    I did not use the laptop for very long after that, I'd already bought another one to make due while it was away at the HP repair center. I did some stress tests and played a few old games but that was about it. A month or two later I sold it to a friend cheap, and he still uses it as his primary AFAIK, it's been at least 18 months since and it still runs fine... so I can't guarantee success with the project but it worked for me.

    If the laptop suffered a severe impact, I suppose it is possible that the rigid interface could cause damage, but I suspect that an impact of that magnitude would have already damaged other portions of the laptop enough that it wouldn't matter.

    However, I did the switch on mine because I had assumed the board HP installed as a replacement was exactly the same and would have the same failure again after the warranty period had ended, if it were only a matter of the fan running faster than I'd like and having it at 60C (it was over 80C), I wouldn't have done anything except make sure the fan and air passages never get clogged with dust.
     
    #17 mindless1, May 12, 2012
    Last edited: May 13, 2012
  18. wirednuts

    wirednuts Diamond Member

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    this was EXACTLY my line of thinking. i opened up my moms dv2610 today. my god you have to destroy the thing just to get to the heatsink. they put it on the bottom of the board and you must remove the board completely to get to it. i still have 9 screws leftover and i think 2 of them look fairly important. oh well, its working better then the day it was new.

    funny you shielded around the core with foam. i used electrical tape (super33). my thought was the penny, if anything, will slip out. it stays in tight it seems though. i lapped my penny with a knife honing block... took 1 hour, no joke but end result was a really nice shim (penny was year 1976).

    it made a dramatic difference. the laptop barely gets warm around the chip area now. the hard drive is now the biggest problem, that little sucker gets hot! what garbage parts they put into these laptops, ugh. once i get a new drive for it the machine will feel cool to the touch at idle, something of a dream for this model.

    and about the penny pressing against the core... unless these cores are different then old athlon xp chips, i dont see them breaking. we used to put giant heatsinks on those things with tremendous awkward pressure as our flatblade screwdrivers slipped off the tension hook and blasted a hole in our atx motherboards... the core rarely chipped and even if they did they usually still worked.

    it looked like almost a 1/8 inch gap between the heatsink and the gpu when i first saw it. that foam just barely filled the air gap. it was crazy, and just as i suspected the gpu was heatsinking entirely though the motherboard- and not the actual heatsink that even has a nice heatpipe running to cooling fins. how can manufactures even think this is ok? it clearly never worked right from the day we bought it, and a simple copper shim completely changes how the laptop performs. its just ridiculous. now all i hope is those 9 missed screws dont come back to bite me....
     
  19. Modelworks

    Modelworks Lifer

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    One program you might try that worked for my notebook when nothing else worked is notebook hardware control, the interface is easy and it has multiple target temp settings.
    http://www.pbus-167.com/

    Be careful using copper shims. Copper isn't going to adjust for the difference in thickness like the rubber, meaning it will not adjust as the temperature changes inside the laptop, you could have a situation where it works great when really hot as the copper expands, but does nothing when cooler and your chips experience high temps before the copper expands.
     
    #19 Modelworks, May 15, 2012
    Last edited: May 15, 2012
  20. serpretetsky

    serpretetsky Senior member

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    heh, 9 screws, wow. I dont think i've ever had so many screws leftover after taking apart a laptop, maybe 1 or 2 the first time i took one apart. Jeesus, 9?

    anyways, about your hard drive problem, I have taken apart an hp with the strangest design. The hard drive drive was getting RIDICULOUSLY hot. it was mounted directly to the motherboard. I flipped over the motherboard, and to my surprise, found the GPU chip mounted directly on the other side with only 1/3 of its surface contacting a really fat rubber thermal pad that was attached to the keyboard to use as a heatspreader o_O. Maybe that applies to you, dont know.
     
  21. mindless1

    mindless1 Platinum Member

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    Yeah I think I'd want to get those screws back where they belong, a lot of laptops are so integrated that their structural rigidity depends on everything being held tightly together.