The effective thermal conductivity
If you have Rth, you don’t actually need λeff, i.e. the effective thermal conductivity. Please remember the anomalies I pointed out and also see that the value hardly changes below 50 µm. But despite these peculiarities, the pad is still miles above the TF8 from Thermalright.
Of course, the whole thing is also shown again as a bar chart for the four most important layer thicknesses:
Apart from the fact that I also have the temperatures of the heater and the water, which are of no use to us because they either adapt to the resistances or always remain constant, I have my measurement setup with temperature sensors 1 to 6 (see diagram on page 2). These values can also be used to make some very interesting considerations. Even though I will of course deal with the conversion of the Gallardo to the pad separately, I have included the usual simulations.
GPU emulation
Let us first take the values of T3 and T4, which show us the two temperatures at the respective contact surfaces between which the paste is located. These curves are no longer completely linear, as the interface resistance also changes slightly. And we no longer calculate with 6 points, but only with 2 absolute values for the temperature difference instead of a gradient as withTTim, whereby the sample temperature remains constant. And what is the point of all this? The behavior is similar to that of a graphics card, which has to manage without an IHS and where the delta is usually measured between the substrate and the water temperature. This can be projected quite well, because I test the temperature difference on the two surfaces between which the paste is located. And here, too, you can see that there is usually less than 1 to 2 degrees difference below around 100 µm.
CPU emulation
Now I compare T3 of both pastes. If we normalize the values for the heater, we already have sufficient thermal resistance in the copper reference block to simulate the CPU temperature and its differences with different pastes in comparison with each other and in relation to the layer thickness of the paste. It is precisely this variable evaluation that no test on a CPU can offer, because it is always individually different and therefore not really reproducible. In the TIMA5 test, however, it is. Here, too, the pad is clearly ahead.
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