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Copper vs. Aluminium

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April 26, 2006 5:40:37 AM

whats better for cooling, copper or aluminium?
i herd that copper absorbs heat faster but the aluminium dissipates
heats faster, and new vga cards are comin out with aluminium heatsinks
so.... comments?

More about : copper aluminium

April 26, 2006 6:14:57 AM

copper=better heat transfer
aluminum=cheaper and lighter.

when you are talking about mounting a heatsink on an add on card, going heavy is asking for trouble, especialy in the OEM market. I am sure that is the last thing you want is to buy a brand new brand X puter only to have yer vid card snapped in half from shipping...
April 26, 2006 6:52:29 AM

Copper is better than aluminum when it comes to heat transfer, that is why mostly all heatpipes on cpu coolers are made of copper. Aluminum is not as good but it is lighter and they made up of mostly all radiators and fins on cpu HSF or water-cooling rads where weight is a concern. Some of the best cpu coolers and water cooling rad are made up of both copper and aluminum.
Related resources
April 28, 2006 4:54:35 AM

Copper is better at heat transfer, however it is heavier than aluminum. Also copper will tarnish after a while but aluminum wont.
April 28, 2006 5:35:56 AM

The thermal resistance of copper is lower than aluminum as is its electrical resistance. This is the case with all precious metals. From lowest to best conductivity of heat and electricity; aluminum, copper, silver, gold, platinum. That is the scale of the precious industrial metals excluding high noble metal processes and alloys. The bottom line on the video heatsink are as previously stated light weight against brittle silicon pcb and aluminum is way cheaper and easier to work with. It's all economics mostly but some heatsink manufacture use a copper heat spreader with a massive aluminum fin structure to get the most surface area per unit of weight.
April 28, 2006 7:39:36 AM

Quote:
The thermal resistance of copper is lower than aluminum as is its electrical resistance. This is the case with all precious metals. From lowest to best conductivity of heat and electricity; aluminum, copper, silver, gold, platinum. That is the scale of the precious industrial metals excluding high noble metal processes and alloys. The bottom line on the video heatsink are as previously stated light weight against brittle silicon pcb and aluminum is way cheaper and easier to work with. It's all economics mostly but some heatsink manufacture use a copper heat spreader with a massive aluminum fin structure to get the most surface area per unit of weight.


Sir, your knowledge of the relevant chemistry is inadequate. I shall attempt to remedy the situation.

I refer you now to WebElements.com, and the image below which has been reproduced from there in terms of the WebElements copyright.



Nature's best performers in terms of thermal conductivity for pure metals are the group 11 metals. Copper, Silver, and Gold. The relative value of precious and semi precious metals have nothing to do with their thermodynamic properties. The value of a metal is completely arbitrary in humans terms, and is a result of its rarity, and/or usefulness for a particular purpose. For example, if copper was more scarce than gold, it would traditionally (in pre-industrial times) have been hardly be more valuable than gold, simply because it tarnishes, discolours skin, and as such its desirabity as a cosmetic metal would have been low when compared to gold.

But I digress.

As you can see from the graph, Platinum's (group 10, next to gold) TC is woefully inadequate for heatsink use. Even a heatsink made from pure silicon, would offer better thermal conductivity. And yet, ultra-pure silicon is in fact used as a thermal insulator on the Space Shuttle's exterior tiles....

Copper's thermal properties seem too good to be true - it closely follows that of Silver, the metal with the highest thermal conductivity, yet it is cheap and abundant. However, aluminium's popularity is due to a number of factors, notably, Aluminium's high TC:D ensity ratio, BUT PRIMARILY, its low melting point. The low melting point allows extrusions to be made very cheaply. Molten Aluminium is "squeezed" through a shaped orifice, which are cooled to form long extrusions (complete with fins, etc). These are then cut up into individual items and machined for detail)

What is interesting, is that while pure carbon (a non-metal) has a low thermal conductivity, nothing beats carbon in one of its allotropic forms, which of course is pure diamond.

Another thing, the core of a cpu is not called a "PCB". PCB is notionally "Printed circuit board", but actually it stands for what the early circuit boards were traditionally made of - Polychorinated Biphenyls. Today, the substrates used for circuit boards are much less hazardous.
April 28, 2006 8:50:54 AM

wth r u ppl chemistry teachers or somthin, even i didnt learn this mch in Chemistry or IT classes
April 28, 2006 9:00:28 AM

:) 

No, but if you're passionate about computers and overclocking, you aquire this sort of knowledge over time. Wait 'till you start messing around with phase-change cooling, then you'll learn all about the difference between mineral and synthetic compressor oils, the different refrigerants, and calculating heat load and capillary tube lengths, and so on.

It's a very satisfying hobby, if you can afford all the equipment :?
April 28, 2006 11:37:06 AM

dude this is jus interacting with ppl in the forums and a way to "make friends", yes i admit i probably did overdid it on the forums, but theres totally nofin wrong with replying to ppl, its a friendly thing to do, theres nothing wrong with doing so
April 28, 2006 11:46:43 AM

Quote:
shadowjagans, stop flooding the forums with your worthless questions. and then you say stuff like "what are you chemistry teachers?". dude, get lost. why do you people even respond to his stufff? i did just now cause i'm pretty tired of his stuff and one other person i know for sure is too... don't you have your avatar or whatever it is already? geez...


This tirade is utterly uncalled for. The "chemistry teacher" bit sounded somewhat like a compliment, if you ask me.

Habitat87, you may not like his questions, but they have their place. If everybody knew everything, then these forums would not exist. Neither you nor myself are entitled to draw an arbitrary line as to what sort of question is "worthless" or not.

What we are entitled to, is to establish whether answering a question is worth our time, and you are not excercising that right properly. If the questions bother you, then ignore them. You are able to see who created the thread, yet you still chose to enter and reply.

Considering the above, the fact that you entered the thread only to end up flaming, your behaviour can arguably be described as trolling, not so?
April 28, 2006 11:59:48 AM

i have to thank PhyberOptik for backing me up =]
April 28, 2006 12:06:52 PM

I'm curious as to all the questions so quickly together, I don't have a problem with it.
They are good and general questions, just jump around from topic to topic.
April 28, 2006 12:08:24 PM

Shadowjagans, no sweat. As you learn more and more, you'll ask less questions and start answering more of them for others.

Of course, one must never ever stop asking questions.
April 28, 2006 12:11:51 PM

geez, alrite, i apologize for making ppl unhappy in this forum, so no need to argue with each other
April 28, 2006 12:20:08 PM

Quote:

habitat87 is right, forums has one purpose and that's to be productive. 90% of your threads aren't and have already been discussed in past threads.


Well, I don't agree. How does one measure "productivity"? "Productivity" is not the goal, because you cannot quantify it in real terms. If the goal of a forum is technical discussion, then the asking and answering of technical questions, no matter how mundane, fullfills that goal admirably.

The aim is not "to further the aim of the hardware/overclocking/hacking art", because not everybody here is at the cutting edge. If that's the sort of community you wish to have exclusively, then it exists elsewhere such as at xtremesystems.org.

I agree that many questions may be answered if the asker chose to search first, but in my opinion, life shouldn't be a series of googles. The internet, such a great bringer-together of people, fails dismally if its citizens were to choose not to interact for silly reasons such as the meritocracy in question here.
April 28, 2006 12:29:44 PM

Quote:
yeah, but i didn't realize this was a "make a friend" forum... and as for the trolling, yes i agree, but that has it's place when something seems completely stupid and wasteful am i not correct? if you can make a comment that mines wasn't appropriate i can express my opinion that his was a completely waste of time too. except your was all opinion, his pasts posts evidently a waste of time... why would you want to start of with a complete waste of a forum? i stand with with what i say.


I'd like to point out that by using the original post's "worthlessness" as a rationale for your own "waste of time" post, you are logically validating the original post existence, and therefore you're not allowed to comment on it in the first place. Can you see the circular logical paradox that you are creating?

The correct way to avoid the paradox, is to sidestep it and not comment on posts that you feel are worthless. They may be worthless to you, and you might be 100% correct, but you're obviously not the only person who frequents this forum, not so?

On the topic of perceived "productivity", I'd like to point out the irony of what this particular thread has devolved into - from a technical discussion about cooling and heatsinks, into one about the desired ettiquette of the forum. Yet the devolution was created exactly by those who purport to reject worthless, "unproductive" posts.
April 28, 2006 12:45:19 PM

I studied A-Level Physics, which I learnt quite a bit about thermal dynamics, including what makes a better coolant. In terms of an HSF, I will just reiterate what everyone has said before. Aluminium is popular purely for the reason it has a high heat capacity (takes more energy to heat it up than copper) and its very easy to work with in order to produce thin fins for heatsinks. However, Aluminium does suffer slightly that its thermal conductivity isn't as good as copper's, so the heat doesn't spread across a aluminium fin as quickly as a fin made out of copper. Also, aluminium doesn't surrender the heat as easily to air because of its high heat capacity, but this is usually overcome by making sure the heatsink has a very high dissapation area, so the more surface area exposed to the air, the easier it is to dump heat into it.
April 28, 2006 12:53:36 PM

Quote:
Also, aluminium doesn't surrender the heat as easily to air because of its high heat capacity


This is certainly interesting! If you ask most people in the hardware and overclocking game, we've been led to believe that it's the other way round. I certainly thought that it was the other way round (which answered the question of why many heatsinks have a copper base with aluminium fins - issues of mass aside).

I'll definitely have to read up on it more.
April 28, 2006 1:08:15 PM

Quote:
whats better for cooling, copper or aluminium?
i herd that copper absorbs heat faster but the aluminium dissipates
heats faster, and new vga cards are comin out with aluminium heatsinks
so.... comments?


Alrighty there pal...this has to be the 7th or 8th thread that you've created asking these BS questions about "Which is better, this or that?"...wtf dude...seriously, you got nothing else to do with your time...c'mon, I'm all for people asking questions and participating in the forumz to find answers, but for effin' sake, this is just friggin' ridiculous!

Not for nothing, but a simple google search will return scads of info on the thermal conductivity of copper and aluminum. Better yet, go to school, take some engineering or physics classes, and learn this $hit for yourself and answer your own damned questions!

Wtf...another bull$hit thread!!!!
April 28, 2006 1:47:15 PM

Forgot to address your "absorb" vs "dissipate" conjecture. I think that's related to how much heat a given material can hold. Here's another link:

http://www.ami.ac.uk/courses/ami4817_dti/u01/supplement...

aluminum = 0.896 kJ per kg per Kelvin
copper = 0.383 kJ per kg per Kelvin

It appears that aluminum is the clear winner at storing heat, however the table shows specific heat in terms of mass. We know that copper is a lot denser than aluminum. We are probably interested in comparing a given volume of aluminum vs the same volume of copper, so gotta convert the table to volume instead of mass.

Here is a table of densities for various materials:

http://www.mcelwee.net/html/densities_of_various_materi...

aluminum = 0.002643 kg/cm^3
copper = 0.0089 kg/cm^3

multiplying by these factors,

specific heat of aluminum = 0.00237 kJ per cm^3 per Kelvin
specific heat of copper = 0.00341 kJ per cm^3 per Kelvin

so by mass, aluminum is better at absorbing heat. But by volume, copper is the clear winner. Given that we are usually space-constrained inside a computer case, copper would be both better at absorbing heat and dissipating it (see my previous post). Sorry I had to run you through this calculator exercise, but i couldn't google up any webpage showing specific heat in terms of volume.
April 28, 2006 2:50:08 PM

Quote:
Also, aluminium doesn't surrender the heat as easily to air because of its high heat capacity


This is certainly interesting! If you ask most people in the hardware and overclocking game, we've been led to believe that it's the other way round. I certainly thought that it was the other way round (which answered the question of why many heatsinks have a copper base with aluminium fins - issues of mass aside).

I'll definitely have to read up on it more.

Aluminium is used because it stores a lot of energy without increasing in temperature much, so its easier to keep cool despite it being rather deficient in transferring the heat. Thats why copper is used for bases and heatpipes, and why heat pipes are used so much in high quality heatsinks, to overcome the deficiency in heat transfer in aluminium fins. The copper transfers the heat, and the aluminium stores the heat away from the CPU, thus keeping the CPU cool.
April 28, 2006 2:55:57 PM

that must be one of the best explanations ever... except im too dumb to understand most of it... O_O
April 28, 2006 2:56:36 PM

Quote:
shadowjagans, stop flooding the forums with your worthless questions. and then you say stuff like "what are you chemistry teachers?". dude, get lost. why do you people even respond to his stufff? i did just now cause i'm pretty tired of his stuff and one other person i know for sure is too... don't you have your avatar or whatever it is already? geez...


Amen. Enough BS questions from this guy... he's definitely exceeded his quota.
April 28, 2006 4:18:03 PM

"Sir, your knowledge of the relevant chemistry is inadequate. I shall attempt to remedy the situation. " PhyberOptik

Slur, your knowledge of being a jerk off is irrelevant, but certainly adequate.
Congratulations you are a fool with a search engine! You don't even know what a PCB is in a computer forum. It is commonly used as an abbreviation for PRINTED CIRCUIT BOARD a substrate for the video card. But since you are concerned with chemistry it's root is in older substrates that were made from Polychlorinated Biphenyl. Also Mr. Search engine, copper, was more precious than gold through out history. In the Americas the Native Americans used to sell gold for copper and much of the territories and trading was done in precious copper. This is something you would learn if you actually went to college and had to take anthropology. But chemistry man lets stick to the question at hand which is METALURGY not chemistry. The process of manufacture and rare earth elemental formations and heavy isotopes of a material alter its properties. This was covered in my disclaimer of high nobles and alloys (iridium), but maybe you can't read. As to the silicon conductors on the shuttle that is industrially produced silicon that sub-atomically is quite different than what occurs naturally on earth anyway. Maybe we could argue the thermo dynamic properties of Jupiter’s Hydrogen metal core? Listen up here, synthetic and bort diamonds are not special they are assembling a molecular structure conducive to heat and electrical transfer using a delocalized plane of free electrons to "glide" energy across excited electrons. Hey you forgot nano tubes! You should spend more time actually reading and trying to comprehend, instead of crawling the internet in an attempt at trying to look cool in front of people who have better things to do. Hey I got something for you it's your AXX. Now if you'll excuse me I have better things to do than hand it to you all day. P.S. Nice graph Search Engine, Maybe you were Lord Kelvin in your last life .
P.P.S No Search Engines were harmed in the production of this response.

Yeah that's right you call me sir, and next time, I'll send you a bill.
April 28, 2006 4:56:27 PM

Quote:

Slur, your knowledge of being a jerk off is irrelevant, but certainly adequate.
Congratulations you are a fool with a search engine!... This is something you would learn if you actually went to college and had to take anthropology. But chemistry man lets stick to the question at hand which is METALURGY not chemistry.... but maybe you can't read....You should spend more time actually reading and trying to comprehend, instead of crawling the internet in an attempt at trying to look cool in front of people who have better things to do. Hey I got something for you it's your AXX. Now if you'll excuse me I have better things to do than hand it to you all day.......
Yeah that's right you call me sir, and next time, I'll send you a bill.


This is why I love this place. So many friendly people willing to take a small part of their day to politely help others and debate ideas in a civilized manner
April 28, 2006 6:06:18 PM

First of all, I'm not here to argue which of the metals is better. They are both good at what they do and there is a reason they are used the way they are. Like others have said the question posed could easily be answered by a quick internet search, or even by delving into your old chemistry book.

One of the reasons to be on this forum however, is to interact, if he feels that he would rather ask someone here than do one of the alternatives, that is his right as a member (even if it is annoying). If someone answers him then great for both of them.

Also, the computer (and other) "geeks" on this forum (and most of us are at least a little or we wouldn't be on a computer forum) are very defensive of what they perceive to be their expertise (whether they actually are or not) but a little politeness should be used to prevent flaming and other behavior that you probably wouldn't use face to face.

I personally skip over most posts that begin with "well you're a moron" type starts regardless of whether they may contain relevant information or not. At times it is very humorous to see how riled up people get on forums, IRC, chat rooms... etc.

I'm not totally immune to this type of online behavior, as my wife can attest to when she hears me yelling at team members on CSS quite often, but generally I use the same method for forums as I do in my business emails. Write it, save it, read it again 5 minutes later, then send it or edit it then send it. You can usually save yourself a lot of grief this way.


Just my 2 cents.
April 28, 2006 7:03:10 PM

I'd just like to say thank you to PhyberOptik for some well reasoned, well articulated, points! I appreciate it when people take the time to express themselves well; good written English rare on a forum.

I don't know about anyone else, but I've learned more than just about the relative merits of copper and aluminium here...
Anonymous
a b K Overclocking
May 1, 2009 1:46:57 AM

wun911 said:
Copper is better at heat transfer, however it is heavier than aluminum. Also copper will tarnish after a while but aluminum wont.


Tarnish is a layer of corrosion that forms over copper, brass, silver, aluminum, and other semi-reactive metals as they undergo oxidation. It is analogous to rust, but with a slower rate of occurrence. Tarnish is mainly caused by chemicals in the air, such as sulfur. It often appears as a usually dull, gray or black film or coat over metal.
a c 330 K Overclocking
May 1, 2009 1:18:31 PM

Only 3 years (almost to the day) late on that argument. :) 
May 1, 2009 5:21:09 PM

Lol yeah Rubix. Looks like we have been having of rash of "Frankstien'ed" threads lately.
a c 330 K Overclocking
May 1, 2009 7:26:03 PM

I'm just wondering how long people searched back threads to find these things...?
May 1, 2009 10:10:57 PM

copper has a conductivity of about 9 watts/inch degree C; Aluminum, about 5 watts/inch degree C.

in other words, copper conducts heat almost twice as much as aluminum.

However, that doesn't mean the copper part will work better, because the primary "delta" in the thermal schematic is heat sink to air - regardless of whether the heat sink is copper or aluminum.

so, for a typical CPU putting out 50 watts, let's say it has a case to junction thermal resistance of .1 degrees C per watt. so you'll see a 5 degrees C rise from, well, case to junction.

then there's a thermal resistance across the interfact with the thermal grease, usually less than .1 degrees C per watt.

then there will be a gradient in the heat sink. the gradient will be bigger if the heat sink is aluminum - in the example, the tips of the fins might be 4 degrees C higher than the base (if it's aluminum), versus 2 degrees C (for copper).

then there's a huge temperature gradient from the heat sink fin to air. like 20 degrees, which would correlate to a thermal resistance of about .4 degrees C per watt, in the example. obviously related to how many fans you have blowing, etc.

i did these kind of calc's working as a mechanical engineer from about 1980 to 2004, then started studying animation in 2005.

a good example would be the Zalman 7000 (or 7700 ?) series. they have the same geometry with the same metal volume available in aluminum, or copper.

my guess is a website like
http://www.frostytech.com/

or some other tech site that has lots of heat sink reviews would have a comparison.
May 1, 2009 11:26:17 PM

lol here we go again.
May 19, 2009 9:12:37 PM

Copper and aluminum are both effective materials for heat sink construction, but they have different requirements. If you want to know why, consider a great chef's kitchen.

Aluminum sure can move heat, if it has been done right. It very efficiently absorbs and transfers heat to it's environment and things that interact with it. This works great for bacon in the morning, and even for boiling water, but isn't so good for a large, thick filet mignon. That cold slab of beef sucks the heat right out of the aluminum, and there isn't any left to keep up the cooking. Many people who buy aluminum cookware have a lot of trouble doing steaks properly for this very reason. Aluminum has a low thermal capacity, and a very high thermal conductivity.

As such, aluminum just wicks heat away with little concern for anything else. It won't wick as much as copper, but it sure will move it quickly; Dumping it's capacity as soon as any heat leaves the sink, and quickly soaking up more.

Copper moves heat as well, even if it hasn't been done all that well. Copper very efficiently absorbs and transfers heat as does aluminum. It does it faster, as well. That said, copper has an incredibly high thermal capacity. That big fat steak just can't suck up all the heat that copper will hold on to, and this is where copper and aluminum differ in requirements. Copper won't readily dump all the heat energy it picks up, because it holds so much of it before it changes temperature to any great degree.

That leaves us with a problem. Copper needs help. Somehow, you have to remove all that heat from the copper, as it will just hold on to it otherwise. A copper heat sink can work much better than an aluminum one, but you have to either have loads of pipes and lots of fins and airflow, or you need peltier/water cooling with excellent transfer to help it out.

The thermal capacity of copper, when compared to an aluminum heat sink of the same design, completely removes the benefit of using copper in the first place without help. As a matter of fact, a poorly designed copper sink can be much worse than an aluminum model.

The best way to use the materials is being tried nowadays, and that is combining them. As with most good things, they work better together than apart.
August 31, 2009 11:57:45 PM

Aluminum has much lower anisotropic values (1.22) compared to copper (3.16). This results in lower vibrational entropy which microscopically (quantumly) means much lower thermal capacity leading to lower heat storage levels than that of copper. So, yes! while copper tends to conduct and accelerates heat diffusion much faster than aluminum, copper's higher vibrational entropy stores heat energy longer while it is being transformed from thermal to vibrational entropy back to thermal, and that is why its release speed of heat is significantly lower than that of copper. so while for cooling heat diffusion is faster in copper, heat release is lower in copper and higher in aluminum. For heating, not quite so! while for coils inside the warmer medium (condenser is now inside the room) heat is dissipated faster by aluminum coils, which is what we need to get warm, evaporator coils outside in colder temperatures need to be copper so that they absorb heat faster, and store heat longer.
a b K Overclocking
September 1, 2009 12:07:15 AM

^You noob! DON'T BRING UP DEAD THREADS!
a c 86 K Overclocking
September 1, 2009 3:12:03 AM

Wow, the pefessor is smart. What was the chap meaning to bring to this conversation, long long after the barn doors closed and the cow is long dead and eaten?

But he's smart, just short on the concept of time and common sense.
September 1, 2009 5:07:52 AM

He said the same thing I said, but dolled it up with 50 cent words, and then bungled it in the middle so it doesn't mean anything.

Vibrational entropy: A function of variance within a system being calculated, relating to it's readiness or resistance to change based upon various subatomic probabilities, or thermodynamic properties. Doesn't always mean the same thing, depending on the level of the system being analyzed.

Quantum=More accurately relating to subatomic.

By his post directly, copper dissipates heat energy at a lower rate than copper.

What he was trying to do is more directly describe the system being explored. Were it not for the bungle in the middle, it would have been a very valid contribution to the thread.

There is nothing wrong with him posting here this late in the game when he has something constructive to add, so don't chastise him for bringing back a dead thread. He is leaving more information for a future search to find, to help an uneducated user out who may have a question on the subject.

I hope he comes back in and fixes his minor mistake so the information is valid. This sort of information clears up all the idiot arguments that populate the internet. What he has to say matters. Now, he said the same thing I said, but he didn't dumb it down for you like I did. It's good to have the complex version as well, for those who are interested.
a b K Overclocking
September 1, 2009 5:42:59 AM

I saw AlaskaFox and chuckshissle and new this was a necro thread without looking at dates.
!