Passive Cooling Methods on Metal Laptop Bodies / Frames

I'm messing around with a silly idea that popped into my head a while ago. Just wondering if anybody has tried something like this yet? You might even laugh when you see what I did. lol. I feel like the right implementation of this could complement or even out-perform a traditional lap fan pad cooler (whatever the hell you call them). Additionally, an external fan, whether it be a USB based fan or a simple oscillating fan in the average joe's office could boost cooling performance further once these are in place.

The idea is to use aluminum or copper heat sinks and the thinnest (silicone) thermal pads available to sink the heat directly from the top side (exterior) of any aluminum / magnesium / metal alloy laptop body that has the right characteristics. This is not really needed for my Dell 7577 for instance, but its chassis does make a good candidate for experimentation. The idea is for it to be removeable and reusable indefinitely (or at least at an extremely cheap cost to replace the thermal padding / TIM sink material occasionally) with no fuss or cleaning to deal with, no risks, and no permanent modifications to your machine. I think if developed as a single chunk of metal and with the right TIM, this could actually help a bit since many laptop manufacturers have moved to metal bodies and made deliberate attempts to concentrate heat buildup around the perimeter / lesser used regions of the keyboard and user-surface-area. I also might just be a bit ridiculous- I am okay with that too.

DELL 7577 SURFACE TEMPS:



ADDITIONAL SURFACE SINKS (using what I had around):

 

UPDATE:

Here is my (almost final) prototype. At this point it is no longer considered passive cooling however. I have still got to buy a few more things to really finish it. Unfortunately it's difficult to determine how much it is actually helping, especially since it is so many layers away from the CPU / heat source itself. The idea is to get as much aluminum/copper heat sinking mass and surface area and put a wind tunnel at its core. When gaming the top external heatsinks do get warm, so that at least tells me it is soaking up the heat as intended.

The top (external) heatsinks are affixed using 0.15mm double sided thermal tape (extremely sticky). The internal heatsinks are affixed with the same thermal tape as well or if you prefer, 0.5mm or 1.0mm thermal pads for easy removal or resizing while testing. As pictured, I ran out of heat sink pieces to mount internally on the top (but there is enough space) and the bottom needs one more piece mounted internally as well. I wish I had more time and money to put towards this right now but I'm about to move across the country so it's not exactly a priority.

I used 1 inch (~25mm) aluminum square tube stock, hand cut with a hacksaw and used a file and sandpaper to debur and clean up the surfaces a bit. It has a cheap 30mm hobby fan rated at 5VDC and a really low wattage. I simply used the double stick tape and an exacto knife to secure the fan tightly to the end of the tube and left the backing intact since I don't want to permanently affix this to the exterior of my laptop. The heatsinks are 25mm x 100mm x 10mm and needed a single fin sawed off to fit internally. Externally they are a perfect match as is for the 1 inch square stock. Currently I've been powering the fan from a simple home made DC power circuit for testing. But ultimately the idea will be to run it from USB power or something equally simple. The fan pushes a good amount of air at ~9VDC but I wouldn't push it much higher than that (I managed to burn up my first fan during initial testing.) (I actually used to mount two of these fans and a 9 volt battery on the brow vent area of my paintball mask back in the day to prevent my mask from fogging up in the humid Florida weather and it worked great.)

With that said, it definitely has room for improvement which is what I intend to do to see if I can get any viable / definitive results out of it. I haven't really had enough time for any real testing yet.

For example, if you make a more compact version of this and were able to permanently fix it (via epoxy or soldering) to whatever needs heat dissipation, it would conduct heat from the source much better/more efficiently. Also as mentioned I want to fill the majority of the internal tubular volume with heat sinking mass and fins by adding sinks to the top surface internally.

This was mostly just a proof of concept of a silly idea that popped into my head and isn't necessarily laptop specific. In fact there's a good chance I might toy with this sinking method on future electronics hobby diy projects involving lasers or small motor controllers etc.

 

Brilliant, looking forward for more!

 

Very cool idea (pun fully intended)!

I can see this working. The more surface area for cooling, the better. Looking forward to your results.

Charles

 

Btw here is the hardware I grabbed from Amazon to make it work. (The tube came from Lowe's or Home Depot or any other typical hardware store.)

The initial fan I had that burned up came out of a Blu-ray player I salvaged components from a long time ago.

I also picked up a 20mm square fan that will fit completely internally inside the tube, but for now I like the value of the 30mm fans much more. (The 20mm square fan from DigiKey was ~$15 after shipping!)

I have also considered mounting additional 30mm fans flat on the center of each top heat sink section that are fixed to the tube. (So, 3 additional fans on top.)

 

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Charles

 

Oh wow, that's very cool, and definitely unexpected. I really appreciate the shout out.

I actually ordered some more aluminum sinks and thermal pads yesterday. Hopefully I can find a tiny bit of time to rework my prototype without upsetting my wife, lol. The new stuff arrives Thursday and we are supposed to pick up our moving truck and pack it on Friday/Saturday so it might be a couple weeks until I get to really follow up with this.

In the meantime, here is a shot of my DC power supply circuit that is driven from a 13.8VDC bench testing power supply meant for testing low power car electronics products. It could also be driven by a 12VDC lead acid automobile battery all the same as well.

Each dip switch path creates a specific output voltage which is handy for testing various things.



And here are a few more shots of my setup and hardware.

 

PSA:

To anyone even remotely considering using the double stick thermal tape I have screenshotted above, DO NOT USE IT ANYWHERE OR ON ANYTHING YOU WOULD NOT CONSIDER A PERMANENT INSTALLATION! IT IS EXTREMELY DIFFICULT TO SEPARATE AND EVEN HARDER TO REMOVE THE ADHESIVE IT LEAVES BEHIND.

It is EXTREMELY sticky and I had to use a flathead screwdriver to pry the top sinks off my tube because it was bothering me they were hanging off the end of the tube by 2mm! (Lol, **** you OCD!)

Not only did that leave some marring and gouges in the aluminum where I had to pry (not a big deal for me to re-dress afterwards), but it left behind ample amounts of gooey adhesive that the finest rubbing alcohol won't even barely begin to take off.

In the end, heating the sinks up under my kitchen faucet's pure hot water (~145F) and using a green brillo pad dipped in rubbing alcohol while also using a bar of Lava soap and some Gojo pumice based hand cleaner with lanolin along with some elbow grease got the sinks nice and clean again while simultaneously gumming up the brillo pad and my kitchen sink with tiny balls of adhesive that are still a PITA to remove from the sink/my hands even.

Thankfully 95% of the adhesive stuck to the individual heat sink sections because cleaning the partially mounted tube with fan permattached to one end is exponentially harder if not nearly impossible without fully disassembling all of it.

Lesson learned- that double stick pro thermal tape is no joke. Its core is a woven cloth with a generous amount of serious adhesive. The cloth peels up relatively easy but the gooey adhesive it leaves behind just wants to get smeared around and not actually dissolve or wipe off easily. Might've had better luck with mineral spirits or acetone or some other equally more heavy duty cleaners but I wasn't in the mood to deal with those and wouldn't assume most average DIYers have them on hand anyways. I would consider it just barely below an epoxy application in terms of permanent-ness.

All said, it was worth learning the properties of the tape first hand since I had originally considered trying to use it to stick the cooling tube to my laptop's keyboard surface, thinking to myself, "a little rubbing alcohol should probably take off any residue it leaves behind." Nope! I even tested the idea by sticking a tiny square of it to the palm rest area (easy to clean if the test didn't work out) and it seemed easy enough to remove and it came off cleanly even, but after getting baked, that is absolutely not the case. I am beyond happy I did not do it despite a quick initial test telling me otherwise.

 

You could try with brake cleaner, a can is cheap, try both the chlorinated and non chlorinated versions.

 

thermal adhesive is 99% of the time meant to be semi permanent

 

Ersa canned flux remover would cut through that with ease, used it to remove stuck heatsinks inside OEM cable tv boxes, but that thing was also more or less canned carcinogenics, with MEK, toluene, chlorinated dont know what, among other good stuff, not sure if the current cans are as good, employer had a big stock of the older not really legal to use due to new laws, but was that thing good at removing any gunk!

 

I had brake cleaner out back but at 1AM didn't really feel up to getting into it shortly before bed. I bet turpentine would do well too.

 

100% of 99% of the time, it is meant to be semi-permanent sometimes...

 

After several hours of reworking my TurboTube (lol) I managed to bring it from having only 2 inner sinks on the bottom wall to having 3 inner sinks on the bottom wall AND 3 inner sinks on the top wall IN ADDITION TO the 3 external sinks sitting on top of the top wall.

If anyone wants to attempt to replicate this design, I would suggest going for a 200mm total length and saving yourself the hassle of trying to secure 3 (100mm) sinks for each section.

This thing is a brick now! (In a good way.) My only concern is that I had to go with 2mm of total thermal pads height on the padding that physically connects the TT to the laptop body due to ever so slightly upward bevels at the edges of the 7577's keyboard body surface area. However with the correct clearances that means the entire tube makes nice even contact with the body of the laptop unlike the last revision. (I wasn't confident in the previous connection despite it looking decent.)

Anyways, it's late and I'm tired with a big day tomorrow. I plan on running Prime95 a bit tomorrow while I do stuff around the house to see what I can see.