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A little lesson on heatsinks

EpicHam

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Actually copper is superior for small heatsinks as well as enclosed systems. Its also superior for large heatsinks equally as much. Think about it. It takes longer to heat up and cools faster while pulling heat away from the diode faster as well. In a nutshell, its thermally superior in every way.

Rick Trent using copper in the lasers is an improvement if you do not mind the corrosion tendencies. My favorite solution to that issue is gold plating. The downsides being cost and that gold is not as good at thermal conduction as copper but still superior to aluminum. Its volumetric heat capacity is irrelevant due to the extremely low volume used(still slightly better than aluminum though :p).
you know.... a much better solution would be a finned design .
cheaper , more efficient but look kinda bad
 

ApexProxy

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you know.... a much better solution would be a finned design .
cheaper , more efficient but look kinda bad
I have seen some pretty sweet finned designs. I actually plan to make my own hosts some day and I am going to attempt to make fins flow with the design.
 

EpicHam

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I have seen some pretty sweet finned designs. I actually plan to make my own hosts some day and I am going to attempt to make fins flow with the design.
Here's a little extra reading to finned heatsink optimization if you intend to machine the parts yourself :beer:

https://docs.google.com/viewer?url=http://www.mhtlab.uwaterloo.ca/pdf_papers/mhtl01-2.pdf



PS: How the hell do you people find all these room and time for machining stuff??
Am i the only one who live in an apartment around here?
 

ApexProxy

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I wish designing hosts could revolve around optimal specs for heatsinking but unfortunately there are issues with durability and also just looking good. Optimally the fins would have to be too thin, too deep, and too numerous, to be sturdy or practical.
 

EpicHam

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I wish designing hosts could revolve around optimal specs for heatsinking but unfortunately there are issues with durability and also just looking good. Optimally the fins would have to be too thin, too deep, and too numerous, to be sturdy or practical.
Well... I can imagine the Dominator using one of this
 
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I found this info on a computer website, but thought that it might be a least somewhat relevant:

Making the base plate out of copper offers a few advantages over aluminum with the main reason being that copper transfers heat faster than aluminum. However, copper retains heat longer. Aluminum does everything the opposite way. It transfers heat more slowly, but retains it for a much shorter period of time.

So the best design is to have a copper baseplate on the bottom of your aluminum heatsink to transfer the heat away from your CPU quickly. Then the aluminum transfers the heat a little more slowly from the copper to itself. Then, finally, the aluminum releases the heat to the air more quickly than the copper, thus forming the optimum heatsink system.

This is probably the reason why the Hedgehog (all-copper heatsink) works poorly with a stock fan. Because it retains heat really bad and cools poorly if it doesn't have a mammoth CFM fan to assist it in releasing that heat. If it has a great fan -one that is big enough to suck the heat away fast enough for the high transfer speed of copper to perform at it's best- then the headgehog will work great (you would also need some good case fans to keep the ambient air inside the case cool enough to keep up the heat transfer efficiency).

If you ask me, you are better off with a smaller copper/aluminum heatsink. Because it's more effective for it's size, less noisy (since you don't need as many fans or as big), it doesn't stress your motherboard with it's weight, and costs less.

To sum it all up:

Copper= Transfer fast, release slow
Aluminum= Transfer slow, release fast
 

EpicHam

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I found this info on a computer website, but thought that it might be a least somewhat relevant:

Making the base plate out of copper offers a few advantages over aluminum with the main reason being that copper transfers heat faster than aluminum. However, copper retains heat longer. Aluminum does everything the opposite way. It transfers heat more slowly, but retains it for a much shorter period of time.

So the best design is to have a copper baseplate on the bottom of your aluminum heatsink to transfer the heat away from your CPU quickly. Then the aluminum transfers the heat a little more slowly from the copper to itself. Then, finally, the aluminum releases the heat to the air more quickly than the copper, thus forming the optimum heatsink system.

This is probably the reason why the Hedgehog (all-copper heatsink) works poorly with a stock fan. Because it retains heat really bad and cools poorly if it doesn't have a mammoth CFM fan to assist it in releasing that heat. If it has a great fan -one that is big enough to suck the heat away fast enough for the high transfer speed of copper to perform at it's best- then the headgehog will work great (you would also need some good case fans to keep the ambient air inside the case cool enough to keep up the heat transfer efficiency).

If you ask me, you are better off with a smaller copper/aluminum heatsink. Because it's more effective for it's size, less noisy (since you don't need as many fans or as big), it doesn't stress your motherboard with it's weight, and costs less.

To sum it all up:

Copper= Transfer fast, release slow
Aluminum= Transfer slow, release fast
Uhh no , I don't see any scientific support for the statement that copper "retains heat" better.

Don't believe everything you read on Tom's Hardware :beer:
 

ApexProxy

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Copper transfer's heat faster which inherently means is moves heat faster as well as cools off faster. Look up the term "Thermal Conductivity". Some people don't realize is that for ex copper at 50C and Aluminum at 50C are two drastically different amounts of stored energy. Copper would store significantly more energy to attain the same temperature which means it would take longer to heat up but it also means that it now has to get rid of more heat once heated. If you heat copper and aluminum with equal amounts of energy the copper would be cooler and would cool off faster. For this look up the term "Volumetric Heat Capacity.

I think I am starting to sound like a stuck record....
 
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EpicHam

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Copper transfer's heat faster which inherently means is moves heat faster as well as cools off faster. Look up the term "Thermal Conductivity". Some people don't realize is that for ex copper at 50C and Aluminum at 50C are two drastically different amounts of stored energy. Copper would store significantly more energy to attain the same temperature which means it would take longer to heat up but it also means that it now has to get rid of more heat once heated. If you heat copper and aluminum with equal amounts of energy the copper would be cooler and would cool off faster. For this look up the term "Volumetric Heat Capacity.

I think I am starting to sound like a stuck record....
By how many times this topic has come up , IT IS a stuck record
 

ApexProxy

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I think that last post of mine summarizes the whole debate pretty well in fairly few words :D

Granted I did simplify things a lot in that but its still technical enough to prove the point don't you think?
 
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grainde

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Well this is has been going round and round...



Enough already! ;) :beer:

Edit: @ EpicHam not calling you a dog...lol
 
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EpicHam

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Well this is has been going round and round...



Enough already! ;) :beer:

Edit: @ EpicHam not calling you a dog...lol
I never understood how does someone muster the patience to be a teacher.
The same questions for 40 YEARS!
Imagine that!

We are getting fed up in like.... 2 months :crackup:
 

hwang21

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Sooo then would a copper module matched to an aluminum heatsink be the ideal combo for lasers?

Also, how do you correct the corrosion problem with using copper?
 

EpicHam

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Sooo then would a copper module matched to an aluminum heatsink be the ideal combo for lasers?

Also, how do you correct the corrosion problem with using copper?
No.
Copper module matched to be a copper heatsink would be ideal.
Aluminum modules DOES NOT hold more heat and copper does not radiate heat slower (aka, it does not have better heat retention)
Maybe I'm wrong , but if that is the case, I WOULD LOVE to read on the source
:D

As for the corrosion problem.
Scientifically, aluminum corrodes a LOT faster due to being lower electronegativity in the series.

(Pardon the BIG CHART, if its any smaller, it might get hard to read)
Its the oxide layer that rapidly forms as its exposed to air which protects aluminum from further corrosion.

As copper is a LOT less likely to corrode, it also mean that its oxide layer is a LOT easier to remove the corroded layer.
7 Ways to Clean Copper - wikiHow
Regular copper cleaner fluid would do the trick , as for the copper module , cleaning would be a bit tougher ,since the diode is in it so you'll have to remove the diode first.


HOWEVER, copper's cleaning cycle is in the once a few years . So that shouldn't be too much hassle.
 
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grainde

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Sooo then would a copper module matched to an aluminum heatsink be the ideal combo for lasers?

Also, how do you correct the corrosion problem with using copper?
Thats what Ive done with most of my lasers and it works fantastically. Due to the low thermal conductivity of most of the thermal greases and epoxies however, it probably still isnt as good as a direct press heat sink (ie without module) of Al or better still Cu. Wrt tarnishing if you are only talking about the module, its not really an issue; your grubby fingers :p and hence sweat shouldnt come into contact with it and it is hidden behind the focus adapter anyway... ;)

I do clean the modules before I use them though, in a salt and lemon juice mix prior to use. :beer:
 
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