Electronic Component Cooling

[uwbsme]

Hi all,

Here is the situation. I am looking at material selection for a component acting as a heat sink. I need to determine the effect of each materials thermal conductivity on my entire system. I understand that as convection transfer decreases, thermal conductivity becomes less important as the convective transfer is the more limiting portion of the thermal system. Correct?

Here is the order of component interaction:
electronic component base, metal block, thermal pad, heat sink, air @ 25C

I am only recognizing convective heat transfer for the heat sink portion of this assembly.

I thought there was a relatively easy way to represent this system. I want to insert the thermal conductivity values for the different materials and compare the difference in junction temperature of the electronic component.

Thanks a lot for your help.

 

[IRstuff]

Is this for school?

TTFN

FAQ731-376

 

[uwbsme]

No this is not for school. Why do you ask?

 

[IRstuff]

Material selection exercises for heat sink design has been a done deal for decades, so it's hard to imagine a company deciding to start on a new effort to plow old ground.

TTFN

FAQ731-376

 

[uwbsme]

This happens when your company is getting into a new area of development. We want to estimate thermal temperatures analytically to try and correlate with lab testing. I was hoping to get some information on simplifying the thermal system w/o my values becoming extremely skewed.

If this problem is simple, please respond but include your answer as a tutorial. It will be helpful for some of us rookies. I recall setting up resistance diagrams and using that method for determining estimated temperatures, but that was a long time ago.

Where do I find the material selection exercises for heat sink design?

 

[IRstuff]

Well, just most component datasheets contains a paragraph or two on how to do the problem, as do a number of textbooks. There are even free, downloadable textbooks on heat transfer:

http://web.mit.edu/lienhard/

http://www/ahtt.html

As for heatsinks, the material of choice for more than 40 years is aluminum.

TTFN

FAQ731-376

 

[uwbsme]

As I'm sure you know there are various types of Aluminum, with varied levels of thermal conductivity. I have a Heat Transfer book from Incropera and Dewitt. I'll check out the free textbook again. We are already using Aluminum, currently Die-Cast A380, but we want to verify the difference in 6061-T651 and the die-cast A380, with respect to our system.

 

[Twoballcane]

I think you are thinking of doing a lump sum thermal study, however, this will just get you up to the heat sink. Then you have to do the extra step of calculating from thermal pad to metal block to case and then to junction (assuming that this is one thermal circuit). A spread sheet will have to be created if you want to see how a new heat sink will affect each of your junction temperatures.

Tobalcane
"If you avoid failure, you also avoid success."