- May 17, 2013
look at my earlier maths on the page 1 comment , I've shown that for the same heat sink design (volume fixed , material variable case)If your concern is runtime, there are other methods that will net an infinite increase in runtime.
Since I know how much you hate analogies, I'll add one. If you want to get better distance on a tank of gas, you could get a bigger gas tank... or you could get a more efficient car.
People often quote these numbers. But they are a bit misleading.
Take a length of wire, for example. Is 1mΩ/m better than 2mΩ/m? Yes, but only by a small amount. Both will work very well as a conductor. Take the reciprocal, however, and you have CONDUCTIVITY: 1000S/m and 500S/m respectively. Surely 1000 is WAY better than 500, right?
Copper heat sink holds more joules of heat than aluminium.
No , aluminium is not strong. It has a crap young's modulus and modulus of elasticity when you take into account that lasers tend to roll off tables.
Things DO tend to become more stable <----- Nerd joke
Are you sure your university cert isn't something written on a tissue paper? Cos I'm a bit skeptical
The question of whether you should choose a copper or an aluminum heatsink has never been a question of which one has a better performance , its always about the WALLET.
For 2 reason.
1: Higher Thermal Conductivity
2: Higher heat retention per m3 of copper
Copper: 401 W/(m.K)
Aluminium's : 205 W/(m.K)
Specific Heat Capacity:
Copper's specific capacity ( 0.3850J/g oC) is lower than aluminum by a factor of 3,
Aluminium 's higher specific capacity (0.902J/g oC) makes it "better" at "sinking heat" from the surface but that can't be farther from the truth
Copper : 8940 (kg/m3)
Aluminium : 2712 (kg/m3)
Case Study :
To put things into perspective .
Assuming a given heatsink is the same in design and only differ in material .
Our hypothetical heatsink (can't be arsed to bring out my casio) of has a volume of 1m3 :beer:
Joules needed to increased the heatsink temperature by 1C
Copper : 8940000 x 0.385 = 3441.900kJ
Aluminium :2712000 x 0.902 = 2446.224 kJ
Better Volumetric heat sinking : COPPER! WINS!
Heat transmissivity : COPPER WINS!
And we aren't even taking into the equilibrium condition where aluminum will just end up trapping heat within the diode
I don't think diode lasers face such a problem .
Since the diode will pop first ......
PS: It has been almost 2 semesters since my Thermomechanics course . So if I got anything wrong , please DO point it out. And if you feel like up to it . Do the maths for me
EDIT: Am i being trolled???? Cos I think I am :undecided: