The effective thermal conductivity
As of today, you will also only find interactive charts here, and I have already written everything you need to know about how to use them on the previous page. And if you already have Rth, you don’t really need λeff, i.e. the effective thermal conductivity. Please remember once again the possible anomalies I mentioned (BLT!) and also see how the values change over the BLT.
Of course, the whole thing is also shown again as a bar chart for the 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 the temperature sensors 1 to 6 (see diagram on page 2). You can now use these values to make some very interesting considerations.
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.
CPU simulation
Now I compare T3 of each of the tested products. 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 pads in comparison with each other and in relation to the thickness of the paste replacement. It is precisely this variable evaluation that no test on a CPU can offer, because the respective CPUs are bent differently and it is therefore not really reproducible. But the TIMA5 test does, because I can measure all distances, which is simply not possible on a single CPU.
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