As electronics of high frequency, high speed, and the rapid development of integrated circuit technology, electronic components for the big increase in the total power density and the physical size is smaller and smaller, the heat flux density also will increase, so the temperature of the high temperature environment is bound to affect the performance of electronic components, this requires more efficient thermal control on it. How to solve the heat dissipation problem of electronic components is the key point at present. Therefore, this article has carried on the simple analysis to the electronic component heat dissipation method.
The efficient heat dissipation of electronic components is affected by the principles of heat transfer and fluid mechanics. The heat dissipation of electrical devices is to control the operating temperature of electronic equipment, so as to ensure the temperature and safety of its work. It mainly involves the different contents of heat dissipation, materials and other aspects. At present, the main way of heat dissipation is natural, forced, liquid, refrigeration, dredging, heat pipe and other ways.
First, natural heat dissipation or cooling
Natural cooling or cooling way is under the condition of nature, do not accept any outside the influence of auxiliary energy, by local heating device for temperature control in the form of environment around the cooling, its main way is heat conduction, convection and radiation focused way, and the main application of convection and natural convection is several ways. Among them, natural heat dissipation and cooling methods are mainly applied in electronic components with low temperature control requirements, low-power equipment and components with relatively low heat flux. It can also be used in sealed and densely assembled devices where other cooling techniques are not required. In some cases, when the requirements for heat dissipation capacity are relatively low, the characteristics of electronic devices will be used to appropriately increase the influence of heat sink and heat conduction or radiation with neighboring devices, and the natural convection will be optimized by optimizing the structure to enhance the heat dissipation capacity of the system.
Forced heat dissipation or cooling method
Forced heat dissipation or cooling method is to speed up the air flow around electronic components by means of fans and other ways to take away heat. This method is relatively simple and convenient, and the application effect is remarkable. This method can be applied in electronic components if the space is large enough to allow air to flow or if some cooling facilities are installed. In practice, the main ways to improve this convective heat transfer capability are as follows: to increase the total area of heat dissipation appropriately, relatively large convective heat transfer coefficient should be generated on the heat dissipation surface.
In practice, the method of increasing the surface area of radiator is widely used. In engineering, the main way is to expand the surface area of radiator by fin, and then strengthen the heat transfer effect. Fin heat dissipation can be divided into different forms, in the surface of some heat consumption electronic devices and the application of heat exchanger parts in the air. Applying this mode can reduce the heat sink resistance and improve the heat dissipation effect. For some electronic periods with relatively large power, the turbulence mode in aviation can be applied to deal with them. By adding spoilers to the radiator, the effect of heat transfer can be improved by introducing spoilers into the surface flow field of the radiator.
Liquid cooling and heat dissipation method
The application of liquid cooling in the heat dissipation of electronic components is a heat dissipation method based on chips and chip components. Liquid cooling can be divided into direct cooling and indirect cooling. Indirect liquid cooling means that the liquid coolant applied directly contact with electronic components, through the intermediate media system, the use of liquid module, heat conduction module, injection liquid module, liquid substrate and other auxiliary devices in the transmission of thermal components. Direct liquid cooling can also be called immersion cooling, which is to directly contact the liquid with the relevant electronic components, absorb heat and take away heat through the coolant, mainly in some devices with relatively high volume density of heat consumption or in high temperature applications.
Cooling method of heat dissipation or cooling method
Cooling or cooling methods of refrigeration mainly have refrigerant phase change cooling and Pcltier refrigeration two ways, in different environments, the way it takes is also different, to integrate the actual situation and reasonable application. Phase change cooling of refrigerant is a way to absorb a lot of heat through the phase change of refrigerant, which can cool electronic devices in some specific occasions. The general state is mainly to take away heat from the environment through the evaporation of refrigerant, which mainly includes volume boiling and flow boiling. In general, cryogenic technology also plays an important role in the cooling of electronic components. In some relatively large power computer systems can be applied to cryogenic technology, not only can improve the efficiency of the cycle, the number of refrigeration and temperature range is also more extensive, the structure of the whole machine is relatively compact and the efficiency of the cycle is relatively high. Pcltier uses semiconductor cooling to dissipate heat or cool some conventional electronic components. It has the advantages of small size, convenient installation, strong quality and easy disassembly. This way, also known as thermoelectric refrigeration mode, is through the Pcltier effect of the semiconductor material itself, in the direct current through different semiconductor materials in series under the action of galvanic couple, can be absorbed heat at both ends of the galvanic heat release, so that the effect of refrigeration can be achieved. This way is a refrigeration technology and means to produce negative thermal resistance, its stability is relatively high, but because of its relatively high cost, efficiency is relatively low, in some relatively compact volume, and for refrigeration requirements are low in the environment application. Its heat dissipation temperature ≤100℃; Cooling load ≤300W.
Five, the way of energy dissipation in heat dissipation or cooling
Heat transfer is the transfer of heat from electronic devices to another environment through heat transfer elements. In the process of electronic circuit integration, high-power electronic devices are gradually increasing, and the size of electronic devices is getting smaller and smaller. In this regard, this requires that the heat dissipation device itself must have certain heat dissipation conditions, and the heat dissipation device itself must also have certain heat dissipation conditions. Because the thermal conductivity of the heat pipe technology itself has some characteristics of good isothermal characteristics of heat flux variability and constant temperature characteristics in the application of good, can quickly adapt to the environment advantages, which has been widely applied in electronic electrical equipment cooling, can effectively meet the cooling device of flexible, high efficiency and reliability characteristics, At present, it is widely used in the cooling of electrical equipment, electronic components and semiconductor components. Heat pipe is an efficient mode of heat conduction through phase change heat transfer, which is widely used in the cooling of electronic components. In practice, it is necessary to design heat pipes separately for different types of requirements, and analyze the influence of factors such as gravity and external force. In the process of heat pipe design to analyze the production of materials, technology and cleanliness, to strictly control the quality of the product, temperature monitoring treatment.
Six, heat pipe heat dissipation
A typical heat pipe consists of a shell, a porous capillary core and a working medium. After vaporization, the working medium absorbs the heat generated by the heat source from the evaporation section in the vacuum state, and rapidly flows to the condensing section under the action of tiny pressure difference, and releases latent heat to the cold source and condenses into liquid. The condensing liquid then returns to the evaporation section from the condensing section under the action of capillary suction force of the suction core, and then absorbs the heat generated by the heat source. The cycle repeats, transferring heat from the evaporating section to the condensing section. The biggest advantages of heat pipe can transmit a large amount of heat in the case of a temperature difference is small, the relative thermal conductivity is the hundreds of copper is known as "near superconducting hot body", but there any a heat pipe heat transfer limit, when the evaporation of the calorific value exceeds a certain limit, the heat pipe working medium inside the will all boil, led to the suspension of cycle heat pipe failure. Because the technology of micro heat pipe in China is not mature at present, the heat pipe has not been widely used in power electronic equipment cooling.