In addition to the paste tested today, the 1:1 comparison already includes all pastes that have also been tested and recorded up to the current point in time and is also automatically updated with every additional paste that is added. So all you have to do is select a paste of your choice on the right-hand side and refresh the display by clicking “Show”, that’s all. In principle, you can already see the database today, but still without search fields and GUI. But that will come soon, because of course we have to make the whole thing user-safe.
Compare
General Information
Manufacturer Specifications
Measurements
Minimum Possible Layer Thickness
That's exactly why I wanted to see how far we could go with a bit of pressure and how much a paste can still be compressed. Here, I use the usual 60 psi (41 N) on the measurement surface of 1 cm², which is more than sufficient and higher than what, for instance, a GPU cooler would achieve.
Thermal Resistances Rth
Let's start with the most important aspect, the thermal resistance Rth. The key feature of Rth is that it correlates linearly with the layer thickness, while thermal conductivity follows a different curve and is far from linear. But experienced readers already know this. We are mainly interested in layer thicknesses of 200 µm or less for CPUs, and usually 100 µm or much thinner for GPUs, depending on bending.
I have now prepared a bar chart comparing the relevant layer thicknesses from 50 to 400 µm for Rth.
Effective Thermal Conductivity and Cooling Simulation
As is always the case in my other reviews: once you have Rth, λeff (effective thermal conductivity) is not really needed. We can also see how the values change across BLT (Bond Line Thickness), though we can't expect a linear curve anymore due to the included area and BLT.
I have now prepared a bar chart comparing the relevant layer thicknesses from 50 to 400 µm for λeff.
GPU Simulation
Let's start with the values for T3 and T4, which indicate the temperatures at the respective contact surfaces between which the paste sits. These curves are no longer entirely linear because the interface resistance changes slightly. And we’re not working with six points anymore but rather two absolute values for the temperature difference, instead of a gradient as in TTim, with the sample temperature remaining constant. And why do we need all this? The behavior is quite similar to a graphics card that operates without an IHS (Integrated Heat Spreader), where the temperature delta is measured between the substrate and the water temperature. This can be projected fairly well, as I measure the temperature difference at the two surfaces where the paste is located.
CPU Simulation
Now, I compare T3 values for each of the tested products. When the heater values are normalized, we already have sufficient thermal resistance in the copper reference block to simulate CPU temperatures and their differences with various pads in comparison to one another, depending on the layer thickness as a substitute for paste. This type of variable assessment cannot be achieved in a CPU test because individual CPUs bend differently, making it non-reproducible. But in the TIMA5 test, I can measure all distances, something that simply isn't possible on a single CPU.
9 Antworten
Kommentar
Lade neue Kommentare
Veteran
1
Urgestein
Veteran
Urgestein
Urgestein
Mitglied
Veteran
Mitglied
Alle Kommentare lesen unter igor´sLAB Community →