The effective thermal conductivity
Here you can also find the interactive charts, which include the values at 25 µm for the TF9 and TFX, although at normal pressure it only goes up to 28 µm (TF9) and 35 µm (TFX). And once again, if you already have Rth, you don’t actually need λeff, i.e. the effective thermal conductivity. Please remember the possible anomalies I mentioned and also see how the values change over the BLT. The curves of the TF9 and the TFX are somewhat uneven, which is also reflected in the very difficult distribution. Please note the step-like gradations (TF9 and TFX), which were created when compressing in 25 µm steps. This is displacement by force and also frighteningly dimensionally stable!
Of course, the whole thing is also shown again as a bar chart for the most important layer thicknesses (again only from 50 µm due to relevance):
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). These values can also be used to make some very interesting considerations.
GPU simulation
Let’s 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.
Although the TF9 and TFX are ahead, they are almost impossible to handle properly in normal everyday use. The TF8 is almost on a par with the almost identical DOWSIL TC-5888 and TC-5550, even if the TF8 is slightly more viscous: Chapeau!
CPU simulation
Now I compare T3 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. The TIMA5 test does, however, because I can measure all distances, which is simply not possible on a single CPU.
Again, the same picture: The TF9 and TFX are ahead, but are highly complicated to use. The TF8 is again almost on a par with the almost identical DOWSIL TC-5888 and TC-5550.
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