Welcome to Laser Pointer Forums - discuss green laser pointers, blue laser pointers, and all types of lasers



Copper vs Aluminum vs Ect.

TheDukeAnumber1

Well-known member
Joined
Jun 7, 2012
Messages
2,064
Points
63
After searching LPF for discussions concerning heat sink materials, I've seen several members mention that aluminum outperforms copper for the purpose of heat removal. This part is for you.

Simply put, copper outperforms aluminum in every way for the purpose of removing heat. Aluminum in many cases is used instead of copper because it costs less, is lighter, can be anodized to any color, and it can be extruded where copper cannot. Comparing the volumetric heat capacities of Al and Cu shows that when energy is applied to similar sized heat sinks, for every 1°C copper rises aluminum will rise 1.4°C, and similarly for every 1°F copper rises aluminum will rise 1.4°F. Ignoring thermal conductivity and comparing duty cycles, copper will run 40% cooler than aluminum and give an overall +40% to runtime. When you consider copper's thermal conductivity that's about twice that of aluminum, copper is much better suited to protect laser diodes from heat than aluminum.


Comparing Copper to other metals


There already is a good thread created my rhd that discusses heat capacity vs conductivity and how copper might not be the best heat sink choice.

http://laserpointerforums.com/f54/i-want-copper-copper-copper-well-maybe-not-72698.html


He brings up a very good point. When a diode heats up the heat sink, it's limited by how much heat it can dissipate to the air around it and that materials like iron, steel, or nickel could be better options for a heat sink than copper. Although I appreciate the analysis I don't agree with it. Using materials like iron or steel will give the heat sink a higher heat capacity, but they have a much lower thermal conductivity, about 5 times less than that of copper. A diode creates a very small hot spot inside of a host, and removing heat from such a small spot calls for material with a high thermal conductivity like copper to draw the heat away to other parts of the heat sink and host. When it comes to heat sinking thermal conductivity is very important.

Steel will take more energy per degree change, but it will conduct the heat away much more slowly than copper. The heat distribution in steel will hold more heat near the diode where copper will distribute it more evenly keeping the diode cooler. Steel will actually provide a shorter duty cycle because it does not move heat away fast enough, and you wouldn't know until it's too late because the inside of the host remains much hotter than the outside. An example of this in computer processing applications is addressed in this link by a thermshield engineer. Where there are "hot spots" ,copper is preferred to move heat away quickly. Thermal conductivity is a very important characteristic in continuously cooled operations and even more so in passively cooled systems like handheld lasers. Where the host can be looked at as the heat sink fins.

http://www.thermshield.com/ThermshieldPages/Copper_vs_Aluminum.pdf


Laser diodes create hot spots and need heat to be moved away quickly. In the previously mentioned thread it was noted that you want to avoid heat choke points in builds, and that putting a copper axis module in a steel sink would be a good idea. That would be placing a choke point around the module causing extra heat build up and not be better than using solid copper.

With copper's nearly unmatched thermal conductivity and respectable heat capacity, it's the best metal for nearly all heat sinking, but especially for laser diode applications.
 

Wolfman29

Well-known member
Joined
Jan 14, 2011
Messages
3,830
Points
63
That's what I've been saying! Except I think silver is maybe a bit better. And cooler ;)
 

Flaminpyro

Well-known member
Joined
May 4, 2009
Messages
5,462
Points
113
Of course silver is better than copper and copper is better than aluminum and that's better than stainless steel which is better than concrete.

here is a silver direct press heat sink I made a few days ago for one of the members here :)

This started out as a cast piece weighing in at 2 oz. you can see a bit of porosity from being cast and maybe
impurities or the metal was just too hot when cast.


The side was clean and smooth when finished off.


You can see the lumpy grainy texture here where I have not machined it yet.


Silver turnings are so shiny and white, there is nothing else like them.
 
Last edited:

Cyparagon

Well-known member
Joined
Sep 12, 2007
Messages
9,610
Points
113


Copper is better than aluminum, just as a 1mΩ clicky switch is better than a 2mΩ clicky switch. Yes, one is twice the conductivity of the other, but it doesn't matter.
 

BShanahan14rulz

Well-known member
Joined
Dec 29, 2009
Messages
3,175
Points
63
Heck, I've been saying we should desolder the dice and directly attach them to aligned graphene enhanced carbon nanotubes for years :p
 

TheDukeAnumber1

Well-known member
Joined
Jun 7, 2012
Messages
2,064
Points
63
Of course silver is better than copper
I'm sorry Flamin but you wasted your time using silver, copper is better. Using silver you gain a 7% increase in thermal conductivity, but you lose 41% of your heat capacity. Silver is like an aluminum but with copper's thermal conductivity.

Copper is better than aluminum, just as a 1mΩ clicky switch is better than a 2mΩ clicky switch. Yes, one is twice the conductivity of the other, but it doesn't matter.
I searched, and either I didn't find, or I found false information. At least this thread's title will be easy to search and I take it you might not have really read this thread because their is more to it than what you have addressed.
 

jander6442

New member
Joined
Jan 8, 2009
Messages
3,220
Points
0


Copper is better than aluminum, just as a 1mΩ clicky switch is better than a 2mΩ clicky switch. Yes, one is twice the conductivity of the other, but it doesn't matter.
Always so positive.:na:
 

pullbangdead

Well-known member
Joined
Aug 25, 2007
Messages
2,045
Points
63
If you care about diode runtime and long life, then you don't put them in a handheld to begin with, and you definitely don't run them at more than twice the rated current as many do here.

It's all relative. You get even better runtimes and even longer life with active cooling via TEC. You get even better runtimes and even longer life with water cooling, or any number of other heat transfer systems.

You're choosing an arbitrary set of options, under a limited number of conditions, and generalizing it to say "this one is always better".

And you're not even the first one to do so on this forum.
 
Last edited:

TheDukeAnumber1

Well-known member
Joined
Jun 7, 2012
Messages
2,064
Points
63
If you care about diode runtime and long life, then you don't put them in a handheld to begin with, and you definitely don't run them at more than twice the rated current as many do here.

It's all relative. You get even better runtimes and even longer life with active cooling via TEC. You get even better runtimes and even longer life with water cooling, or any number of other heat transfer systems.

You're choosing an arbitrary set of options, under a limited number of conditions, and generalizing it to say "this one is always better".

And you're not even the first one to do so on this forum.
Did you read the title or thread all because you've completely missed the point. This is a comparison of metals used for cooling, not cooling systems. Obviously active cooling works great and also depends on what metals you use in it. It's seems like you just want to bash.

And if so many people have made threads just like this one, please... show me.
 

Blord

New member
Joined
Dec 24, 2007
Messages
5,368
Points
0
Beside the thermal capabilities between these two metals there is also the aesthetic look. The golden color of the copper appeals people much more than the aluminum look. Also the relative high mass density speaks in favor of copper.
 

Apocalypse

Member
Joined
Sep 11, 2011
Messages
250
Points
18
I think people also made solid silver hosts because of the weight and the feel in their hands.
 

ARG

Well-known member
Joined
Feb 27, 2011
Messages
6,987
Points
113
Copper is only noticably better when air flow speeds are very high. We do not use finned heat-sinks in our hobby, rather use blocks of metal to absorb as much heat as possible before having to turn the laser off.

Copper does have an advantage, but the difference between aluminium is so small that it's not even worth it unless it's for a module. Copper is more expensive, harder to machine, looks awful and it corrodes.

Did you read the title or thread all because you've completely missed the point. This is a comparison of metals used for cooling, not cooling systems. Obviously active cooling works great and also depends on what metals you use in it. It's seems like you just want to bash.
What he is saying is relevant to this, this thread is about thermal dissipation after all. No need to be rude.
 
Last edited:

Cyparagon

Well-known member
Joined
Sep 12, 2007
Messages
9,610
Points
113
Did you read the title or thread all because you've completely missed the point.
Not quite. He's just saying your point is not helpful in the grand scheme of things. It's sorta like:

op says "fact: dog sh:)t tastes better than cat sh:)t."
PBD says "It depends on what you're feeding the dog. I prefer lasagna, anyways."
 

jander6442

New member
Joined
Jan 8, 2009
Messages
3,220
Points
0
Of all the materials to use in this hobbie for heatsinks aluminum just makes sense... sure every once in a while when funding calls for by all means build using copper. This is why the copper builds fetch more mula right?

Hypothetically if you were to be sending a astronaut to Mars and need to build the best possible pointer HeHe:na: then ya go copper...:fightin: or not.
 




Top