Electronic thermal managment

Thermal coefficient and size.

Can't think of a third, those two are the most important criteria.

John.

John:

From a size perspective are you looking at minimum or maximum? What about CTE match is that a major factor or does the solder or TIM compensate?

Ribrin

Sorry Ribrin, I don't recognise those abbreviations.

What are CTE and TIM ??

CTE = coefficient of thermal expansion

TIM = thermal interface material ie. thermal gap pad, artic silver, etc.

The third one will be Thermal Resistance.

Thermal coefficient is the thermal resistance... i.e. 10*C/Watt

Sorry! I was in the office and busy - Had looked this up in a jiffy and added my comment.

But John, Thermal coefficient is generally related to expansion of matter you should have been careful in calling it as 'Thermal conduction coefficient' which is then nothing but thermal resistance.

Ribrin, in my personal opinion, the three most important criterion for selecting a heat spreader such that to achieve better heat dissipation would be:

First, to achieve, best possible contact between heat generating device and heat dissipating device. This is generally referred as contact resistance. You may use thermal pastes in-between the two and can also play with clamping force.

Second, is the characteristic thermal resistance of the dissipating device. This, more or less, decides the final base temperature of the heat source. Heat spreaders get involved here physically. The challange is to pick up heat instantaneously and transport it away. Just a metal mass (Al 'or' Cu), as heat spreaders just do not measure up to something like when assisted with Heat pipes.

The third important aspect is the area of heat spreader that is transporting this energy and giving it away to ambient and whether it is assisted by force cooling or is just dissipating naturally.

Ahhh ! I see what you mean.... i should have stipulated that it was thermal coefficient of transfer - I don't like using the ambiguous 'thermal resistance' as I don't think it describes adequately the mechanism.... or maybe it does?!!

I prefer to see the θ _{jn - amb} symbol which describes exactly where the measuring points are for the thermal resistance / coefficient etc...

John.