The laptop sometimes stops working: its power drops, it periodically shuts down or makes a lot of noise. This happens when the internal electronics parts overheat. The consequences can be unpredictable, including the impossibility of repair. The technique must be monitored to avoid such problems. Especially if the computer is expensive and useful information is stored in it. For this and there are cooling systems.
Selection of thermal pads for a laptop.
The cooling system is the most common reason for visiting a repair shop. At best, the ventilation of the laptop may be clogged with dust, and at worst, the thermal interface may have deteriorated.
What is a thermal interface?
Thermal interface - a heat-conducting compound between the cooled plane and the heat sink device. The most common are thermal paste and compounds, they are used for personal computers and laptops. And they are also designed for various electronics chips.
Thermal interfaces are distinguished by type:
- thermal paste;
- polymeric compositions;
- adhesives;
- thermal pads;
- soldering with liquid metals.
Thermal grease - a soft substance with high thermal conductivity. It is used to reduce the thermal resistance between two contacting faces. Serves in electronics as a thermal interface between the part and the device that removes heat from it (for example, between the processor and the radiator). When applying a heat-conducting paste, it is necessary to take into account that it should be applied in a thin layer.
Guided by the manufacturer's instructions and applying a small amount of paste, you can see that it is crushed when the surfaces are pressed against each other. At the same time, it fills all the grooves and irregularities on the materials and spreads evenly throughout the part. Polymer compositions are used to improve the tightness and strength of electronic compounds. They are resins that harden after they have been poured onto the heat release surface.
Adhesives are used when it is impossible to screw the heat-conducting material to the processor, chipset, etc. It is rarely used because of the accuracy of adherence to the application of the technology on the plane. If you break them, it may cause damage. Recently, spike liquid metal is gaining popularity. This method gives a record in specific heat. However, it has a large number of difficulties, such as preparing material for soldering, as well as materials for brazed parts. After all, aluminum, copper and ceramics are unsuitable for this.
What is a thermal pad?
To date, the most popular thermal interface are thermal grease and thermal padding. Thermal pad is a small plate that is placed between the heating element of the laptop (for example, the chipset, memory, south bridge, video card) and the radiator (cooling element).
Many use for this thermal grease. But she can not give the same solution as the gasket. The thing is that with a large amount of work paste can not cope. The paste cannot completely fill the entire surface. There will always be a small gap, which is bad for the cooling system. Thermally conductive gasket has high heat-conducting properties, it is elastic and perfectly fills the gaps between the surfaces.
They come in different sizes depending on the size of the chip. The main thing is to choose the right thickness. There are from 0.5 to 5 mm and more. Most experts recommend choosing 1 mm. But best of all, when disassembling a device, measure your old insulation yourself. It is strictly forbidden to use it again. This will break the part.
The substrate cools parts that operate in high temperature mode. If it gets messed up, the desired part will not cool enough, causing the system to overheat. As soon as the computer starts to work slowly or shuts down, it is necessary to immediately disassemble it and clean the fans and at the same time change the thermal insulation.
If this is not done, the temperature will increase to 100 degrees Celsius or more. The microcircuits will begin to slowly melt, and that will end their function. Due to its elasticity, the heat sink will protect the chips from temperature and mechanical deformations. Therefore, to increase the life of the laptop, open the back cover and inspect the internal state regularly.
Elements of heat transfer come from different materials:
- ceramic;
- mica;
- silicone;
- copper.
Choosing a gasket material
Ceramic
Thermally conductive ceramic substrates are by far the best for removing heat from electronic circuits to a cooling radiator. The most effective ones are made of aluminum nitride (AlN).
ATTENTION. Aluminum nitride - ceramics of excellent microstructural and chemical homogeneity, with excellent characteristics. The thermal insulation made of aluminum nitride becomes a wonderful alternative to beryllium oxide. It should be noted that they are non-toxic.What are the benefits of using aluminum nitride substrates?
- First of all, it is their high resistance to temperature and chemical attack.
- Gaskets minimize the operating temperatures of semiconductors.
- The thermal conductivity of aluminum nitride does not decrease when heated, which, unlike beryllium, increases their service life.
It is believed that aluminum nitride ceramics are easy to break. But it is not. The substrate of the smallest thickness is able to withstand a small pressure. It bends slightly, which allows you to take the form of a radiator.
High thermal conductivity provides the ability to use insulation of increased thickness without deterioration of thermal resistance. This reduces the unnecessary gap between the circuit and the radiator. For example, the heat-conducting layer of aluminum nitride with a thickness of 1 mm reduces the gap in comparison with mica by 20 times, but loses in resistance by 10 times.
Electric strength of thermal strips made of aluminum nitride is guaranteed at a level of at least 16 kV / mm, which is almost twice as high as silicone substrates.
Silicone
It is resistant to high temperatures and is also used to cool laptop components. Most often it is used to remove heat from the processor, graphics chip, video memory, RAM, the north and south bridges.
Silicone is needed when there is no contact between two planes or when there is no guarantee that it will be. Then it becomes his task to fill the lumen and transfer heat from a hot to a cold surface more efficiently than thermal paste. This gasket is elastic, can be compressed and decompressed depending on the thickness of the lumen.
Silicone is easier to pick up in thickness. They are mostly sold in large sheets. If you put one size, and the gap still remains, you can cut and put another one. Therefore, it is not necessary to measure the distance between the two surfaces before installing insulation.
The substrate shrinks better than the rest. Therefore, when struck or vibrated, they soften the components. Another advantage of silicone is that it is not necessary to use sealant to install substrates. A minus of silicone laying is their short service life. This should also be considered when purchasing more expensive products.
Copper
Recently, this material has become increasingly popular. They are used for heat sink graphics and central processing units. The thermal conductivity of copper substrates is significantly higher than that of silicone ones. But when using them, a sealant is needed to hide the gap between the surfaces of the microcircuits and the radiator.
It is necessary to know exactly the thickness when choosing copper substrates, taking into account the use of thermal paste. They are not as elastic as silicone, and the gap between the surfaces needs to be measured. When exposed to a radiator, the sealant is slightly squeezed out, but it is harmless and under the effect of time it is removed. The use of copper insulation is more laborious, but more effective.
Thermal Strip Test
Silicone was chosen for the test as a material, and many other indicators were also taken into account. When checking the thermal conductivity, Bergquist products made in the USA showed the best performance with a stated value of 6 W / (m · K).
Almost the same result was shown by Russian gaskets Coolian and CoolerA with the same parameters. The only negative is the price, they are quite expensive. Swiss Arctic Cooling with a declared thermal conductivity of 6 W / (m · K), Russian Coolian with 3 W / (m · K) and Chinese Aochuan with 3 W / (m · K) show about one result in the degree of thermal insulation.,
Finally, designs with a thermal conductivity of 1.0–1.5 W / (m · K). This type of cooling is suitable for computers that do not overheat and use a small amount of resources. In this category, all products showed themselves equally. All had approximately the same properties, and all met the stated requirements.
Thermal pads, you can choose any, depending on what options you are suitable. It is better to entrust the replacement of the thermal insulation to the professionals in order not to damage the delicate laptop microcircuits.