Interactive charts
In the meantime, the database is also taking shape in the background and I am busy filling it with newly tested pastes, pads and putty. This finally allows me to insert interactive charts as curve or bar charts. Interactive means that I can define certain products relevant to the article as set in these charts and then fill the rest with the best products at the current time. These charts are also updated retrospectively because they are regenerated each time the page is called up. This also means that from now on, all subsequent articles are also constantly updated automatically.
The products in the curve diagrams can be shown or hidden by clicking in the legend; moving the mouse pointer over the node points of a curve shows the real measured values stored there. In general, nothing is interpolated. Some bar charts can also be switched for predefined layer thicknesses so that, for example, the thermal conductivity of the relevant products can be clearly displayed with the best stored database entries. However, I would like to take this opportunity to point out that all results are subject to copyright and that I generally require permission to use them for my own purposes.
Control curves in the TIMA analysis
In the data interface, you can check the determined values in advance, test them for plausibility and deselect the deviating values for the determination. In this way, you can also recognize the slight anomalies that may exist at certain layer thicknesses, where the thermal resistance no longer correlates particularly linearly with the layer thickness. But this is exactly what you have to question, because there must be reasons for this. For the CX-H1300, I measure a bulk thermal conductivity of 6.835 W/(m-K) for all measuring points that are reasonably in line (I have deactivated excessive deviations). This is an excellent value!
Although the Value32 is significantly worse at 4.717, it is well above the self-declared value of just 3.2 W/(m-K). This is also still really good and usable. However, bulk thermal conductivity is not everything, effective thermal resistance and effective thermal conductivity for the different layer thicknesses (BLT) are more important.
The thermal resistances Rth
Let’s start with the most important aspect, the thermal resistance Rth. The most important property of Rth is that it correlates nicely linearly with the layer thickness, while the thermal conductivity describes a completely different curve and remains anything but linear. But the experienced reader already knows all this, of course. We are interested in the layer thicknesses of 200 µm to around 3000 µm on the memory modules and voltage converters. Everything else is really for the gallery. Some manufacturers also state the pure, idealized bulk value here, but this is completely unrealistic.
I now have the relevant layer thicknesses from 250 to 3000 µm as a bar chart for Rth in comparison between the putties and the best lists in the database:
Minimum possible layer thickness
But at least I wanted to know how far you can go with a little pressure and how much the putties can still be compressed. I use the usual 60 Psi (41 N) on the measuring surface of 1 cm², which is completely sufficient and is more than what a GPU cooler, for example, achieves.
Interface Resistance
What also seems interesting is the contact resistance, in our case the interface resistance. Here you can see how well the surface of the material “clings” to the contact surfaces (IHS, heatsink). These values are also easy to compare and meaningful, as they are always the same calibrated reference blocks. Coarser degrees of grinding or a less favorable microstructure can be just as much a negative factor, which then influences the effective thermal resistance and thus also the conductivity, as too low temperatures and too high a viscosity. But putties have their own rules, because the values are higher than for more fluid pastes.
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