COMMON HEAT DISSIPATING MATERIALS FOR MOBILE PHONES

With the electronic products becoming more and more thin, due to the narrow internal of the body, its cooling capacity is also limited. The main sources of heat in smart phones include these five aspects:

① Energy generated by the main chip operation;

② Heat generated by LCD drive;

③ The heat of battery during discharging and charging;

④ The heat generated by CCM driving chip;

⑤ PCB structure design heat conduction and heat dissipation is uneven.

In order to solve these heat dissipation problems, the current manufacturers mainly use the following four kinds of heat dissipation materials:

Heat dissipation of graphene thermal sheets

Graphene sheets is a kind of ultra-thin heat dissipation material, which can effectively reduce the heat density of the heat source, achieve large-area rapid heat transfer, large-area heat dissipation, and eliminate the phenomenon of single point high temperature. The product thickness of graphene films can be varied (0.08mm ~ 2mm) and can also be shaped into any designated shape, which is convenient for use in various products, especially in electronic products with restrictions.

Graphene sheets are small in size. Due to their lightweight advantages, they will not increase the weight of the terminal products in the current heat dissipation scheme. Graphene sheets are soft in texture, excellent in process ability and usability, and will not generate additional electromagnetic interference. For example, they can solve the problem of heat dissipation and electromagnetic interference with specific absorbing materials.

Metal back heat dissipation

Apple uses a metal back plate heat dissipation technology in the iPhone with a metal shell. Based on the use of graphite heat dissipation film, a layer of metal heat conduction plate is also designed inside the metal shell, which can export graphite. The heat is directly transferred to all corners of the metal body through this layer of metal heat conduction plate, so that the heat in the enclosed can quickly diffuse and disappear, and people will not feel too much heat when holding it. 

Thermally conductive gel/thermally conductive silicone pad

The thermally conductive gel is semi-solid, similar to toothpaste. The thermally conductive gel inherits the advantages of silicone material's good affinity, weather resistance, high and low temperature resistance, and good insulation. At the same time, it has strong plasticity and can satisfy the filling of uneven interfaces. Meet the heat transfer needs of various applications. It has high thermal conductivity, low compressive force application, low pressure, high compression ratio, high electrical insulation, good temperature resistance, and can be used automatically.

Thermally conductive silicone pad is a very soft solid, similar to a sponge, directly attached to the heat source, and in contact with the heat source to conduct heat. The condensation reaction occurs through the moisture in the air to release low molecules to cause crosslinking and curing, and vulcanization into a high-performance elastomer. Has excellent resistance to cold and hot alternating performance, aging resistance and electrical insulation performance. And has excellent moisture resistance, shock resistance, corona resistance, anti-leakage performance and chemical resistance. Can be used continuously at -60 ~ 280 °C and maintain performance. It does not swell and has good adhesion to most metallic and non-metallic materials. 

Heat pipe cooling

The so-called heat pipe technology is to cover the vertex of a liquid-filled thermally conductive copper pipe on the mobile phone processor. When the processor generates heat, the liquid in the heat pipe absorbs the heat and vaporizes. These gases will reach the cooling area on the top of the mobile phone through the heat pipe to cool down. After condensing, it returns to the processor part again and again and again for effective heat dissipation.

In the mobile phone industry, it is also called water cooling. It's just that this heat dissipation technology takes up more and is used less in mobile phones. In fact, as early as three years ago, Japanese smartphone manufacturer NEC released the world's first mobile phone NEC N-06E using heat pipe cooling technology.