With the rapid development of science and technology, today's electronic equipment tends to be lighter and thinner, and the internal electronic components tend to be more sophisticated and complex. Not only does the heat dissipation difficulty of internal components increase, but also the electrical characteristics between components must be taken into account to avoid short circuits, especially the problem of heat generation is related to The lifespan of the product and the amount of energy it needs to perform. In view of this, light, thin and short electronic products urgently need a better heat dissipation mechanism to solve the generated high heat problem.

Graphene is exfoliated from graphite. The color of single-layer and two-layer graphene is transparent, and the color of 3-10 layers is gray-black. The more layers, the darker the color will be. The black ones seen on the market are all carbon black or carbon tubes, posing as graphene. Or a large amount of carbon tubes and carbon black are compounded with a small amount of graphene, so the color is black, and the darker it is, the lower the graphene content is.

Graphene has excellent thermal conductivity properties, and the thermal emissivity coefficient exceeds 0.95. Therefore, in terms of thermal conductivity, heat dissipation or thermal management, from electronic components, components to LEDs, if graphene can provide product types that meet design requirements , it can effectively improve the performance of the current cooling products.

According to The Market for Thermal Management Technologies report, the market value of thermal management products in the global market is estimated to grow from US$10.7 billion in 2015 to US$14.7 billion in 2021, with a compound annual growth rate (CAGR) of 5.6%. It is an important industry and represents the strong demand for thermal management products in the market.

As we all know, the mid-to-high-end radiator Cui Rui also launched the Cui Rui c7 all-copper graphene-enhanced radiator. In addition, the solid-state drive Asgart also launched a solid-state hard disk with a graphene cooling vest, and even Huawei mobile phone mate20 also has graphite. Graphene heat dissipation blessing, then whether the blessing of graphene heat dissipation coating has any effect. First of all, we have to start with some principles of heat management.

Principle of heat conduction and heat dissipation

Integrated circuits are used extensively in electronic product components. As we all know, high temperature is the enemy of integrated circuits. High temperature will not only cause the equipment to run erratically, shorten its service life, and even burn some parts, and the portable equipment will also cause harm to the human body.

The heat that causes the high temperature does not come from outside the electronic device, but from the inside of the electronic device, or inside the integrated circuit. The function of the heat dissipation component is to absorb the heat and dissipate it into the device or outside the device to ensure that the temperature of the electronic components is normal.

Generally speaking, cooling methods can be divided into passive cooling and active cooling.

Active heat dissipation: The fluid circulation is pushed by external force to take away the heat.

Passive heat dissipation: It uses the principle of thermal expansion and contraction in physics, the natural circulation of fluid to dissipate heat or the use of the specific heat capacity of solid fluid to absorb heat to achieve the purpose of heat dissipation.

Heat dissipation methods can be subdivided into heat conduction, heat convection and heat radiation.

Thermal conduction: (thermal conduction)

It is the phenomenon of heat transfer when there is no macroscopic motion in the medium, and heat is transferred from one part of the system to another or from one system to another, which can occur in solids, liquids and gases.

Thermal convection: (thermal convection)

It refers to the relative displacement (convection) between various parts of the fluid caused by the macroscopic motion of the fluid, and the heat transfer process caused by the mixing of cold and hot fluids. Convective heat transfer can be divided into forced convection and natural convection. Forced convection is the circulation of fluids caused by external forces. Natural convection is due to the change of density gradient at different temperatures, and gravity causes low-temperature high-density fluid to flow from top to bottom, and high-temperature low-density fluid to flow from bottom to top.

thermal radiation

It is a heat transfer method in which an object dissipates heat energy in the form of electromagnetic radiation. It does not depend on any external conditions.

Among them, the fan forced cooling, as the name implies, is to generate strong air convection by the fan, and the hot air is led out of the heat source or the lamp body to dissipate heat. Using the fan forced cooling can effectively discharge the heat by adjusting the fan speed, such as computers or servers. If there is sufficient space for electronic products, most of them are forced to dissipate heat by fans, which is not only low-cost but also a very effective way of dissipating heat.

Passive heat dissipation includes natural convection heat dissipation and loop heat pipe heat dissipation, in which natural convection heat dissipation is through direct contact with air through radiators, such as heat dissipation fins, lamp housings, system circuit boards, etc. The hot air, then the hot air rises, and the cold air descends, which will naturally drive the air to generate convection to achieve the effect of heat dissipation. For electronic products with limited institutional space, such as mobile phones or tablet computers, and even products that are not suitable for installing fans, such as LED light sources, this heat dissipation method is mostly used. However, the driving force of heat exchange in this way only comes from the temperature difference between the heat source and the surrounding air, and the heat dissipation effect can be improved by increasing the contact area.

The principle of graphene heat dissipation

With the increasing operating frequency of processors and the introduction of high-power LED products, more and more waste heat needs to have a larger heat dissipation surface area. However, products using natural convection are focused on increasing the heat dissipation surface area in a limited space. This method is contrary to the original intention, and although the material of the heat dissipation fins is often made of metal materials such as aluminum and copper with high thermal conductivity, the high thermal conductivity of the metal can only effectively diffuse the heat of the heat source to the metal through a single point. On the other hand, the cooling mechanism still relies on the temperature difference between the metal surface and the air to dissipate in the form of natural heat convection, and generally the thermal radiation coefficient of the metal surface is low, and the surface heat dissipation capacity is relatively insufficient, which is not conducive to natural heat dissipation. cooling module. To further increase the heat dissipation effect, the heat radiation efficiency must be improved.

The surface emissivity of the metal radiator is very low, which can be confirmed by a small test. On the same heat source at 100°C, put an aluminum sheet coated with graphene on the surface, and at the same time put a The untreated aluminum sheet is then tested by an infrared temperature measuring gun, and you will find that the temperature of the untreated aluminum sheet is very low, the same heat source, why there is such a difference. Because the infrared thermometer mainly measures radiant heat, the surface emissivity of metal aluminum is very low and the heat dissipation is average, so the radiant heat is low, and the temperature measured by the infrared thermometer is also low, and the aluminum sheet with graphene coating , the surface emissivity becomes higher, the radiation heat dissipation becomes stronger, and the temperature measured by the infrared thermometer becomes higher.