Stars-922 Thermal Conductive Adhesive

I've run into situations several times where using thermal paste was either inconvenient or impossible, since it requires constant pressure to keep the heatsink against the component. So I decided to try something just as useful: thermally conductive adhesive.
Today, then, a short review and, of course, a test—especially since I've already posted a couple of reviews of various thermal interface materials.


It doesn't cost much and takes up no space on my desk, but I'd heard it can dry out if left sitting for a long time. Just in case, I chose the listing with two tubes, although the seller also offers a single-tube option.
Two-piece lot: $1.79 + $0.81 shipping — link.
One-piece lot: $0.98 + $0.86 shipping — link.
Shipping to Russia is free.

I placed the order on May 5 this year, but the tubes ended up sitting unused until I found a job for them. I decided to put together a short review while I was at it.
Delivery took about three weeks, so no complaints there. The order also included protection boards for 2S battery packs, but I'll cover those another time.

According to the markings, they were made either on May 3 or March 5. Either way, they're fresh.


The tube is tiny. The stated adhesive weight is 5 g; with the tube, it weighs 7.35 g. I can't say for sure that it really contains 5 g, but that seems about right. Some product reviews complained that the tubes were very small. Personally, I'd rather have five small 5 g tubes than one 25 g tube, since this is adhesive, not just paste.
There's a membrane under the cap that you have to pierce. It keeps the contents from hardening prematurely.


The store page listed the following specifications:
Thermal conductivity: > 0.671 W/m·K
Tensile strength: 1.5 MPa
Surface curing time: 10 min at 25°C

I also came across a claim that it takes 25 kgf to pull the parts apart, but checking all of this would be tedious and inconvenient, so I decided to keep the test brief.

First, I took four RAM chips and glued them to an aluminum heatsink, applying roughly the same amount of adhesive to each. I wanted to glue on a larger chip too, but I only had one, so testing several smaller ones was more convenient.


Next, I tried removing the chips at one-hour intervals. The first came off relatively easily, mostly because I pried it up from one edge. The second and third came off with about the same amount of effort. I wouldn't call it easy—roughly like removing something glued with silicone sealant. The adhesive does resemble sealant, but it has no smell at all.

I removed the fourth chip after about six hours, and it was holding quite well.



But in fact, only the part that squeezed out when I pressed the chips down had hardened. The adhesive underneath them was still viscous. You can see marks on the second spot from the left; I tried moving a pair of tweezers around there after removing the chip.
Everything hardens after about 10 minutes, so it cures quickly in the open air—around 10–15 minutes—but takes a long time where there's no air.


For the second test, I'll check how well the adhesive conducts heat. I put together a test rig that I've already used in two reviews of thermal paste and thermally conductive rubber. It uses the same components as before: a power supply, two heatsinks, two resistors, a thermometer, and a board.


I apply the adhesive to the heatsinks. A quick aside: the one on the left is the first one I applied, and the one on the right is the second. I noticed that after the adhesive has been sitting for at least a day or two, white paste and some kind of liquid come out first. If you keep squeezing, there's almost no liquid, and the consistency becomes more viscous. The adhesive is fairly runny, so squeezing out the excess is easy. It's clearly thinner than KPT-8 paste.


I could have managed with just one heatsink. I usually use two for comparisons, and decided to do a small comparison here as well.
I applied the adhesive on the left while it was more liquid, and on the right after it had thickened as some of the liquid separated out. Then I installed the resistors, pressed them down with a weight, and left them for three hours.


Since, unlike thermal paste, this doesn't need to stay under pressure afterward, we can remove the weight and move on to the test.


I set the power supply to the same 20 W as in the previous tests. With the same heatsinks and resistors, this makes the results repeatable and lets us compare them with other thermal interface materials later.


After an hour, I got these results. The initial reading comes first, followed by six measurements taken at 10-minute intervals, for a total of one hour. Don't let the fact that the first heatsink is a little hotter put you off. There's a desk lamp with a halogen bulb nearby, and it warms the heatsink slightly. What matters is the temperature difference.


For comparison, here are the results of tests with КПТ-19 and КПТ-8 pastes, carried out a couple of years ago under the same conditions. In my opinion, there's no difference.
You can find more tests in the relevant reviews:
Thermally Conductive Rubber
K5 Pro, or what to do if you don't have thermal paste on hand


As I mentioned, the adhesive looks a lot like silicone sealant. For comparison, here are the results of testing it on the same "test rig". By the way, below is an example of installing a heatsink in a TV box. Before that, I tried a different heatsink with silicone sealant.
But judging by the results, what's in the tube definitely isn't silicone sealant. It doesn't smell like sealant either, although not all sealants smell.


The thermal image shows roughly the same thing, and you can clearly see why I stuck a piece of black electrical tape on the heatsink.
While I was at it, I checked the power supply and noticed that it gets hot in one spot. I'll have to take a look and see what's heating up there.


I've also already used this paste for its intended purpose, as shown in my recent review of a TV box.


Since the heatsink was large and the chip was small, I had to apply paste to the RAM and flash memory too, although that's not the right way to do it.


And here's the result. About a day after gluing it on and running various tests, I tried to pull the heatsink off. I can say it holds very well. At any rate, I applied more force than it would experience in normal use, even if the device were dropped.


That's all from me. The test results speak for themselves, I have no complaints about the seller, and I think I can confidently recommend it for situations where there's no way to clamp the heatsink in place.