HY-510 thermal paste and thermal pad

This isn’t my first review of various thermal interface materials, and today I’m going to try another thermal paste and another thermal pad. They’re useful things for electronics hobbyists, computer enthusiasts, and others, so I decided to test them out of curiosity. There’s also a bonus in this review: a test of three types of thermal adhesive and one more thermal paste.


I originally ordered one piece of thermal pad and one tube of paste for the review. I should say right away that this review is in no way a comparison of their specifications. I ordered them together simply because my “test bench” is designed to test two thermal interface materials at once. In other words, it was just more convenient for me.


First up is the thermal pad. Of course, its performance is inherently worse than that of thermal paste (though I can imagine there may be exceptions). Its job is not only to transfer heat, but also to protect components from damage when several heat sources are mounted on the same heatsink. The most familiar example is a laptop.
Also, components can sometimes have different thicknesses, so to simplify things, the heatsink is made flat and the differences are compensated for with thermal pads. And let’s not forget about possible misalignment, impact protection, and so on. Another use is transferring heat away from a circuit board. Here, the pad helps accommodate small components and leads, and also acts as an insulator.
Thermal pads are available in various thicknesses, from very thin ones around 0.3–0.5 mm thick to very thick ones. I’ve personally come across 5, 6, and 8 mm versions, and I doubt that’s the limit. Though I imagine you can only dream of good performance from the thickest ones.

Blue thermal pad, 100 × 100 mm, 0.5 mm thick, price $1.59 - link.

The dimensions are as specified, nothing is damaged, and it’s even cut quite neatly.


There’s protective film on both sides: thin on one side and very stiff on the other. As you can see in the photo, in this state it even “remembers” its shape if you bend it, although the pad itself is soft.


There’s not much to inspect here. I cut out a square to match the outer dimensions of the test resistor and check the thickness while I’m at it. Uncompressed, it measures 0.53 mm.


The second item is HY-510 thermal paste. I’m sure you’ve already seen reviews of it, since it’s quite popular.
It comes in a 30 g syringe and costs $2.13 - link.

The claimed thermal conductivity is over 1.93 W/m·K. For comparison, the popular KPT-8 has a value of around 0.7 W/m·K.


Actually, when I placed the order, I was interested in the paste itself, so I didn’t even notice that it said 30 grams. When the package arrived, I was a little surprised by the size of the syringe. I’m more used to Chinese sellers’ photos making everything look huge, only for the item to arrive and make you feel like they took the photo through a microscope.


When I unpacked it, a familiar scene even came to mind :)
Now I’m wondering what I’m going to do with all this paste...


The paste is moderately thick and definitely doesn’t want to flow on its own. When I squeezed it out, it even curled upward a little, but I wouldn’t call it very thick either, since it spreads easily.


There’s not much else to say, so let’s move on to the tests.
The test “bench” consists of:
1. Adjustable power supply
2. Two identical heatsinks, with matte 3M electrical tape applied for accurate temperature measurements.
3. Two identical 15 Ω, 10 W resistors
4. An IR thermometer. Unlike larger models, it has a small temperature measurement area, which is just right for tests like these.
5. A 1 kg weight, made from a jar filled with hardware
6. A small piece of laminate.
7. Paper, pen.

Of course, you could say that the test conditions and the method itself are far from ideal, but the key point is that I used the same setup for every test. So if the results differ, they differ in the same way across all the tests.
The most tedious part is cleaning the heatsink after each test, especially when testing thermal paste.


I peel the protective films off the rubber pads and install a resistor. Thanks to its clean surface and tight contact, the rubber pad sticks in place.
I install the second resistor using thermal paste, applying it as in all the previous tests and squeezing out the excess by gently rubbing the resistor against the heatsink.


I place a weight on top and switch on the heaters, setting each resistor to 10 W, for a total of about 20 W.
The test runs for one hour, with temperatures measured every 10 minutes.


Here are the test results. What matters is not the absolute temperature but the difference: the smaller it is, the better. This will be easier to see at the end of the review.
I also ran an additional test, increasing the power to 15 W per resistor and taking two measurements (highlighted in yellow) at the same intervals. These results won't be included in the summary table; they're just here “for good measure.”


Summary table: lower is better.
The table also includes results from other reviews, some of which are rather... strange :)

HY-510 paste and 0.5 mm rubber are highlighted in red.


Now, for the conclusions.
Rubber showed a temperature difference of about 25 degrees, which is quite a lot. But if the heat output is lower than in my test and the contact area is larger, it can still be a viable option. Think of basic TV boxes, or the circuit boards in voltage converters, amplifiers, and similar devices, where heat is transferred directly to the circuit board itself.
HY-510 paste turned out to be only slightly better than ordinary KPT-8 in real-world performance. Its advantages are the price and the fact that these days you can often buy anything but genuine KPT-8 when you think you're buying the real thing. Oddly enough, cheap Chinese paste is less often counterfeited. It's convenient for all sorts of hobbyist projects where a difference of a few degrees isn't critical.

That's all for today. I hope you found this information useful.