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american-pi
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is JB weld good idea to attach HeatSink to 4b ?

Thu Jul 18, 2019 8:15 pm

just got my heat sinks from aliexpress
trying to figure out what would be the best solution to attach these heat sinks to my pi 4/4gb.

Thanks!

wh7qq
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Re: is JB weld good idea to attach HeatSink to 4b ?

Fri Jul 19, 2019 1:14 am

3M heatsink tape has had good reviews here...thin and easy to use. Personally, as I never expect to reuse the heatsinks, I have used Arctic aluminum epoxy with good success but it has to be applied in a thin, even coat and avoid the contacts on the edge. It is permanent once cured. The black, gooey, two-sided tape is terrible and eventually the heat will cause it to melt and slip off if the RPi is on its side. Many bargain heatsinks come with this garbage applied already. Scrape it off and clean residue with a strong solvent like "Goof-off" or throw away the heatsinks. It does not work well.

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Imperf3kt
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Re: is JB weld good idea to attach HeatSink to 4b ?

Fri Jul 19, 2019 1:34 am

Jb weld has decent thermal properties, but do not get it anywhere except on the top of the CPU (it contains iron, so can very easily create short circuits)

Also note that if you mount your Pi on its edge, and a large heatsink has been "JB welded" in place with nothing else securing it, the weight could potentially rip your SOC apart.
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PhatFil
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Re: is JB weld good idea to attach HeatSink to 4b ?

Fri Jul 19, 2019 4:54 am

Its a bit of a PERMANENT solution!

How confident are you that this particular heatsink is the last option you will possibly want to try? will it fit/function in every case/enclosure your pi could live in?

heatsink compound and thermal pads are not very expensive unless you buy premium products, and even then still cheaper than a new pi, if for example you end up wanting to sit the pi in a flikr metal case..

Moonmarch
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Re: is JB weld good idea to attach HeatSink to 4b ?

Fri Jul 19, 2019 8:10 am

Wouldn't the JB Weld epoxy become brittle eventually with all the exposure to heat unless that is all you have to choose from in your house, I don't know if the epoxy is safe to use on electronics or has better thermal conductivity.

Here are some ideas to attaching heat sinks to the RPI computer, thermal tape, thermal paste, thermal adhesive, you only need apply a small amount of paste to cover the heated surface, according to articles I read about the RPI4, the computer will overheat don't know if this situation is solved recently, heat sinks can help with overheating if there is no air travelling through the heat sink fins then the heat stays trapped in the heat sink.

Heater
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Re: is JB weld good idea to attach HeatSink to 4b ?

Fri Jul 19, 2019 8:23 am

Do note that whatever you use between the chip and the heatsink should be as thin as possible.

Even proper heatsink compound is a terrible conductor of heat. But almost anything is better than air. So the idea is only to displace air from the spaces between micro-irregularities of the chip and heatsink surfaces and fill those tiny gaps with something more heat conductive.

When your layer of heatsink compound, or whatever it is, is thicker than required to do that you are making the transfer of heat worse. It's definitely a case of "more is worse".

I imagine that any kind of tape is universally terrible but I have never done any measurements on that.

Compounds that don't conduct electricity are essential in many cases. Perhaps one can get away with sparing amounts of such things under a Pi heatsink but I would not want to be slopping conductive gloop over the board.

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Imperf3kt
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Re: is JB weld good idea to attach HeatSink to 4b ?

Fri Jul 19, 2019 9:26 am

Heater wrote:
Fri Jul 19, 2019 8:23 am
Compounds that don't conduct electricity are essential in many cases. Perhaps one can get away with sparing amounts of such things under a Pi heatsink but I would not want to be slopping conductive gloop over the board.
Best stay away from most thermal paste/grease then, most of the better ones are excellent conductors of electricity, containing aluminium or even silver particles.

Here's a nice breakdown of some different types of thermal interface material one can get.
https://graphicscardhub.com/best-thermal-paste-cpu-gpu/
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Moonmarch
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Re: is JB weld good idea to attach HeatSink to 4b ?

Sat Jul 20, 2019 8:05 am

Applying thermal paste is not difficult, I actually build my own computers that's how I know, how did I notice the difference in temperature when I applied the thermal paste in comparison to what was being used as a thermal conductor, which was some stock thermal putty I have this old gaming laptop which would overheat all the time after applying the thermal paste, the load temperature is now 65C which used to be over 90C.

If you are mounting the RPI computer to a computer monitor which means the computer will be stacked vertically, I had this idea of using JB Weld to hold the heat sink in place, you can glue the finned side of the heat sink to a RPI case don't know what you can use as a shim to fill in the space between the heat sink and the case, then apply the "thermal conductive material" to the RPI board components which should hold all of the heat sinks in place.

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