"liquid metal" as a thermal interface. Liquid metal for the processor: pros and cons

At ordinary temperatures, most metals are in a solid state. To make them liquid, you need to melt them. The only natural exception is mercury. Rest liquid metals- These are artificial alloys.

Properties of liquid metals

Such metals are similar to liquids through viscosity, diffusion and surface tension. However, their compressibility is much less. In addition, like any metal, they reflect electromagnetic waves. Plus, liquid metals inherited high thermal and electrical conductivity and other “metallic” features from representatives of their group.

The combination of good thermal conductivity and significant heat capacity of some liquid metals has found use for them as coolants. For example, sodium and potassium are used in nuclear reactors for cooling.

To create alloys (with a melting point below 40 0 ​​C), sodium, potassium, tin, zinc, mercury, gallium and other fusible metals are used. different proportions. The main disadvantage of such compounds is their high chemical activity or even toxicity, which seriously narrows the scope of their application.

But this difficulty was overcome, and non-toxic alloys were developed, which included gallium:

Application of liquid metals

The thermal interface, for simplicity called “thermal paste,” is a thermally conductive substance located between the surface that needs cooling and the device that removes heat.

Thermal pastes are used in electronic devices, measuring equipment, and household computers.

Requirements for thermal pastes serious are presented. They have to:

  • have minimal thermal resistance;
  • do not change the consistency during operation or storage;
  • maintain stability in the operating temperature range;
  • be resistant to corrosion and oxidation;
  • be non-flammable and non-toxic;
  • easy to apply and, if necessary, wash off;
  • in some cases, good electrical insulating properties are also required.

High thermal conductivity coefficient of liquid metals allows them to be successfully used as thermal pastes.

Liquid metal instead of thermal paste

In computers, thermal paste is used to regulate the heat generated by chips on printed circuit boards. The more powerful the processor, the more warmth it emits when working.

To avoid overheating and failure of the processor, a cooler is installed on top of it - a cooling mechanism. An air gap inevitably occurs between these devices, which reduces the efficiency of heat removal. Thermal pastes are designed to eliminate this annoying inconvenience.

One of the most advanced heat-conducting materials, consisting entirely of liquid metals, is the product created by the Coollaboratory company - Coollaboratory Liquid Pro.

Outwardly, it resembles mercury, but is completely non-toxic. It is completely free of solid particles and non-metallic additives (oxides, silicone and others).

This liquid metal has only one disadvantage: it is designed specifically for high-quality copper and silver coolers. Aluminum, used in cheap coolers, does not have sufficient resistance when interacting with Coollaboratory Liquid Pro.

But the undoubted advantages of the new liquid metal thermal interface include impressive thermal conductivity, tens of times superior to classical analogues.

10 years ago, a new thermal interface from Coollaboratory, Liquid Pro, appeared on the cooling systems market.
It has been repeatedly analyzed and tested (for example, here www.overclockers.ru/lab/22232.shtml).
However, I have not found a single test that would show what happens to the processor and radiator after long-term use of this drug.

So, when the MacBook Air with 32 windows howled when it started Firefox, and the monitoring program showed the CPU temperature at 92 degrees, it was decided to resort to Liquid Pro. The procedure for applying it to the crystal did not cause any special problems, but with the radiator substrate (copper ) there were difficulties. But, nevertheless, the system began to work significantly quieter and performed its functions properly for almost a whole year (since November 2014).
It's December 2015:

And the howling continues again.
And the cooler buzzes furiously.
And the stone is so hot.
And my heart beats anxiously.

An autopsy showed an almost complete absence of dust (an office, after all) on the radiator grille. We remove the heatsink from the processor and... we see a lunar crater at the base of the heatsink:

The surface is corroded as if by acid. It is not possible to smooth out unevenness with nylon sandpaper from Coollaboratory - you need regular sandpaper.

Strange, I thought. Copper, after all (there are probably plenty of impurities there, but it’s not aluminum). And if you take as a substrate not a liquid mixture, but a “dry” product from the same manufacturer - Liquid MetallPad. Fortunately, I bought them together... There were still a couple of pieces left. Imagine my surprise when, instead of a thin silver-gray metal plate, a collection of metal dust was found in the bag, which was stored in the original rigid, but no longer airtight, packaging:

And finally.
Literally a week before the “opening,” a set of Coollaboratory Liquid Ultra (CL-Liquid-Ultra-CS) was purchased as a more effective replacement. However, in connection with the revealed facts, it was decided to use this item in a less expensive device. But even here, as it turned out, the manufacturer, despite the high stated price, managed to screw up: instead of the stated 1 ml of mixture in the syringe, there is 2 times less of it. The photo shows that the stop stopped at the 0.5 ml mark. The piston does not go lower - there plastic insert silver color:

Therefore, before buying products with the words “Made in Germany” on all sides of the packaging, and even with exclamation marks, I advise you to think carefully.

What if so? Any thermal paste is a mixture based on thermally conductive dielectrics, which have a much higher thermal conductivity than air, but they are still very far from the thermal conductivity of metals. What if you use metal instead of thermocompounds? Theoretically, this can eliminate the bottleneck in the heat transfer chain from the processor to the cooler, which is the thermal paste; in this case, the cooling efficiency will depend only on the performance of the cooler. But what liquid metals do we know? Mercury is toxic and hazardous to health, so it is unlikely to be used as a thermal interface. What else? It is unlikely that it will be possible to find a metal that is in a liquid state and has the necessary physical and chemical properties and is environmentally friendly. But... he is. Coollaboratory has launched a new revolutionary metal-based thermal interface on the market, which has tens of times higher thermal conductivity than classic thermal pastes. This is exactly what advertising slogans sound like, but what kind of metal thermal interface is this? Let's get a look.

Сoollaboratory Liquid Pro

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The silver-colored thermal interface is located in a thin syringe with a short metal needle. Our test unit was in a plastic bag, while retail products are found in plastic packaging with detailed instructions by application. However, everyone can download the instructions from the manufacturer’s website for themselves, even in Russian. It is not yet easy to buy this thermal interface in Russia; you will have to use an online store. The ColdZero online store is listed on the official website for purchase in our territory. The current price of the product is 7.9 euros. But there is also a distributor in Russia - the company EiSEN. Coollaboratory Liquid Pro is not only a highly efficient heat conductor, it is also an equally efficient conductor electric current, due to its metal base. So when using it, it is important to follow the rules, starting from the preparation stage. An important point - the Coollaboratory Liquid Pro thermal interface can only be used with copper coolers (or silver-plated). And there are two reasons for this, the main one is that in some cases, with increasing air humidity, Coollaboratory Liquid Pro can form an alloy with aluminum, which will lead to deterioration in thermal conductivity. The second reason is obvious: what is the point of using a highly efficient thermal interface with an unproductive aluminum cooler, which costs the same 8 euros? Coollaboratory Liquid Pro will be most effective when using the most powerful and effective systems cooling. Before applying the thermal interface to the processor, you must carefully remove any remaining old thermal paste and degrease the surfaces of the processor and the base of the cooler. Next, the manufacturer recommends sanding the base of the cooler if it has unevenness, but if you have a serious top-end cooler, then most likely you won’t have to do this. A drop of liquid metal falls on the processor like a drop of solder, only it does not solidify. Next comes the fun part, smearing it with your finger liquid metal You can’t use the processor, your fingers are oily, and it will be harmful to the skin. The manufacturer recommends using talc-free rubber gloves or a cotton swab. You shouldn't use cotton wool, as it leaves lint, so a paper napkin was perfect for applying Coollaboratory Liquid Pro to the processor. It turned out to be very easy to smear the thermal interface over the surface of the processor if you “rub” it into the base with a napkin. But this should be done very carefully so as not to spread the electrically conductive thermal interface outside the processor. One drop of Coollaboratory Liquid Pro is enough to “tin” the entire surface of the processor’s heat distribution cover, after which you should try to attach the cooler and see if the thermal interface is in contact with its base. Considering the unevenness of the processor base, one drop may not be enough; it is advisable to apply the thermal interface to the base of the cooler using the same method. When the contact between the processor base and the cooler is complete, this process can be considered complete. In our case it looked like this:

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Important! Do not apply excess Coollaboratory Liquid Pro! The thermal interface is in a liquid state and is easily squeezed out; if a squeezed out drop gets on the electronic components of the system, it will cause contact shorting and damage to the equipment. That layer of Coollaboratory Liquid Pro, which is located between the processor and the cooler, is held there due to intermolecular adhesion forces. The Coollaboratory thermal interface can be just as successfully applied to the core of the video adapter, but you should be especially careful about the accuracy of the application and avoid excess, since the graphics core is surrounded by open hinged elements on the substrate, the shorting of which will not lead to anything good. Coollaboratory Liquid Pro thermal interface will be more difficult to remove than it is to apply. Liquid metal penetrates deep into the pores on the surface. The main mass can be wiped off with a simple paper napkin, but complete removal can only be achieved by polishing or using special metal cleaning products.

Coollaboratory Liquid MetalPad

More New Product company Coollaboratory, which is also a thermal interface based on liquid metal, but is initially in a solid state of aggregation, in the form of metal foil.

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Hidden under the plastic packaging are three squares measuring 38x38 mm and three squares 20x20 mm, for processors and video chips, respectively. In addition, the kit includes a kit for cleaning the surface from traces of the liquid metal thermal interface: two wipes soaked in alcohol-containing liquid and grinding.

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The instructions are written in English language, but a Russian-language version is also available on the manufacturer’s website. Coollaboratory Liquid MetalPad is a thermal interface similar in properties to Coollaboratory Liquid Pro, but is in a solid state, which facilitates the application process and increases safety of use. The foil is placed like a gasket between the processor and the base of the cooler, and the dimensions of the foil should in no case protrude beyond the contact area, otherwise the thermal interface will end up on other elements of the system. You can trim off the excess simply sharp scissors, and this should be done without removing the foil from the paper cover. The principle of operation of the Coollaboratory Liquid MetalPad is quite simple: being in the form of foil, it is placed on the surface of the processor without much difficulty, then the cooler is carefully installed so as not to displace the foil, and secured. This completes the first stage. In order for the metal foil to turn into a liquid state and fill the irregularities, it is necessary to heat it to a temperature of about 60°C. It's easy to do. After the system is assembled, turn on the computer and run one of the stress tests that warms up the processor the most, for example S&M or EVEREST. To control the processor temperature, you can use proprietary utilities from the motherboard manufacturer or special programs, for example SpeedFan. It happens something like this: after running the stress test, the processor temperature begins to rise sharply, after it exceeds 60-70 degrees, after a few seconds it suddenly drops just as sharply by 10-20 degrees and stabilizes within 5-10 minutes . If your processor does not reach the desired temperature, then you can go another way - manually slow down the fan on the cooler, and thereby reduce the cooling efficiency. To do this, you can use manually setting the fan speed in the motherboard BIOS, sometimes you can do it using software (SpeedFan). After achieving the melting effect (some time after the temperature drops), you should return the normal fan speed, or select the optimal one. For those who use water cooling, the technique is somewhat different - it is unlikely that it will be possible to warm the processor to the desired temperature with a simple stress test, since water cooling is usually highly efficient. To achieve the melting effect, you will have to disconnect the water pump from the power supply for a while and thereby stop the circulation of the refrigerant in the cooling circuit. The CPU temperature will continue to rise until the pump is activated again. Carefully! If overheating reaches a critical temperature for the processor, it may fail! So instead of stress testing, use slower methods to heat up the processor, such as archiving a large file. It should be remembered that after melting the foil using this method, there will be no sharp decrease in temperature, because heat is not removed from the water block, so you should carefully monitor the processor temperature and, after a slight decrease in temperature in the range of 60-70 degrees, reactivate the water pump. The result obtained should be confirmed by a decrease in the processor temperature compared to the previous thermal paste. To remove Coollaboratory Liquid MetalPad from the surface of the processor and cooler, the kit comes with a special polishing agent, which is used to clean off any remnants of the thermal interface that could not be removed with a napkin. Just be careful not to press the polish too hard to avoid scratching the surface. Buying Coollaboratory Liquid MetalPad in Russia is just as difficult as its liquid counterpart, but it is already included in the price lists of online stores. One of Coollaboratory’s key partners is a German online store

Thermal paste is needed to regulate heat generation printed circuit boards. It allows you to eliminate air gap between the processor and the cooler base, and increase the efficiency of heat dissipation. In some cases, you can replace thermal paste with liquid metal.

Liquid metal for the processor: pros and cons

Liquid metal for a processor, like any other thermal interface, has its pros and cons. Therefore, before you decide to replace conventional thermal paste with ZhM, you should adequately evaluate your hardware and various features this material. Thus, liquid metal differs in the following advantages:

"Pros"

  • High thermal conductivity;
  • Low viscosity;
  • Uniform texture.

Due to these characteristics, thermal paste ZhM 6 will be of interest primarily to seasoned overclockers, whose processors with conventional thermal paste suffer from high temperatures. However, when using liquid metal instead of thermal paste, you may encounter the following: negative points:

"Minuses"

  • Problematic application. The surface of the processor must be polished, degreased and, if there are any uneven surfaces, sanded. The liquid consistency material should be blotted into a napkin and thoroughly rubbed into the cooler and processor;
  • Difficulty in liquidating the composition. To remove liquid metal thermal interfaces, use special means cleaning;
  • Destruction of aluminum bases of coolers;
  • High cost of material;
  • High electrical conductivity.

The liquid metal thermal interface must be applied very carefully; if its excess accidentally gets onto the components of the motherboard, a short circuit may occur when the system unit is turned on!

Popular liquid metal thermal interfaces

Syringe with liquid metal ZhM-6

Among the popular liquid metal thermal interfaces are: Indigo Xtreme, Gallide ZhM-6 And Coollaboratory Liquid Pro. Reviews of these products can be found in any store or on a specialized forum. Separately, I would like to mention the “solid” liquid metal.

It looks like a thin plastic rectangle and is much easier to apply than regular ZhM-6. To do this, you need to cut out a square of material corresponding to the size of your processor, remove the bottom protective film, fix it on the lid. After this, remove the top protective film and attach the radiator.

We hope that our article helped you get acquainted with this type of thermal interface as liquid metal. Thank you for your attention!

Composed of metals high turnover, not containing mercury.

Is the most effective today thermal interface, which has the highest thermal conductivity (more 80 W/m*K). For example, one of the best thermal pastes Arctic Silver 5, has thermal conductivity less 9 W/m*K.

One of the first “liquid metal” thermal interfaces was Coollaboratory Liquid Pro .

Liquid metal also has its disadvantages:

· Difficult to apply. It is necessary to thoroughly degrease the surfaces with alcohol and sand them if there are any irregularities. Depending on the consistency, the liquid metal must be soaked into something and rubbed into the processor cover and preferably into the base of the cooler. A paper or non-woven napkin is best.

· Incompatibility With aluminum cooler bases. At a certain humidity, corrosion begins at the aluminum base when interacting with liquid metal.

· Thermal interface conducts electricity! So, you should not allow any excess that may fall onto the electronic components while pressing the cooler against the processor. Contact of liquid metal (even one small ball) on electronic components can damage them.

· Difficulty removing thermal interface. To remove it, it is better to use a regular napkin, but it does not completely remove the remaining liquid metal. To completely remove the thermal interface, you should use special metal cleaning products for the car, or a special kit from the manufacturer Coollaboratory Liquid Cleaning Set.

There is also liquid metal in solid aggregate condition (in the form of a rug), is called Coollaboratory Liquid MetalPad .

It has more profitable and simple conditions application for the common consumer.

His application much simpler. It is enough to cut a metal mat in the form of foil, a little smaller, or to the size of the chip (with direct pressure) and press the cooler.

To metal became liquid, enough warm up it within a few minutes up to 60 degrees or a little more. After this, the thermal interface is ready.