16 KINDS OF HEAT DISSIPATION METHODS FOR SEMICONDUCTOR (1)

The importance of thermal design for electronic equipment:

The manufacturer of electronic equipment specifies the maximum allowable temperature for the operation of the equipment. Above the temperature, the expected performance and life are not guaranteed. Therefore, it is very important to cool the electronic equipment and make it work below the maximum allowable temperature. With the high-performance microelectronic equipment put into the market, the heat dissipation of the equipment is larger, and more efficient cooling technology is needed to keep the equipment working at the allowable temperature.

There are many advantages for electronic devices to work at lower temperatures. With the decrease of temperature, the clock frequency of microprocessor increases and the performance improves. In addition, the reduction of temperature will reduce the probability of temperature related failures mentioned above.

In the design of electronic equipment, in addition to improving the performance and reliability of electronic equipment must have good heat dissipation performance, in addition to eliminating noise, reducing energy consumption, reducing equipment cost also need good heat dissipation. If the equipment is reasonable in some way, the noise, energy consumption and cost of cooling fan will be reduced. Especially for the living room and bedroom appliances, low noise is an important indicator; for consumer electronic products, low cost is very important; whether large or small electrical appliances, low energy consumption is very important.  

Heat dissipation solutions for semiconductor electronic components:

In the process of rapid development of electronic devices, the total power density of electronic components is also increasing, but its size is becoming smaller and smaller, and the heat flux density will continue to increase. In this high temperature environment, it is bound to affect the performance indicators of electronic components. Therefore, it is necessary to strengthen the thermal control of electronic components. How to solve the heat dissipation problem of electronic components is the focus at this stage. In this regard, the next main electronic components of the different cooling scheme for a simple introduction and analysis.

(1) Choose high thermal conductivity materials

The material properties are the important factors to determine the heat dissipation. The research and development of materials with high thermal conductivity is the fundamental way to solve the electronic heat dissipation.

(2) Fin radiator

Fin radiator is a passive heat exchange device which transfers heat. The heat sink is usually a metal part, which can be attached to the equipment. By increasing the working surface area and enhancing the flow of low-temperature fluid on the surface, the heat is dissipated to the surrounding fluid to prevent the equipment from overheating.

(3) Interface gap filling material

Thermal interface material is used to coat between radiator and heating device to reduce the contact thermal resistance between them.

All surfaces have roughness, so when two surfaces are in contact with each other, it is impossible to completely contact each other. There will always be some air gaps mixed in them, and the thermal conductivity of air is very small, thus causing relatively large contact thermal resistance. The air gap can be filled with thermal interface material, which can reduce the contact thermal resistance and improve the heat dissipation performance.

(4) Heat pipe

Heat pipe heat exchanger was born in 1964 in Los Alamos National Laboratory. As a noise-free heat dissipation technology, heat pipe radiator began to be used for heat dissipation of electronic equipment in the 1980s, and its application in PC has accelerated obviously in recent two years.

Heat pipe is a passive device. The working principle is that the saturated liquid absorbs heat and vaporizes from the higher temperature side, and the saturated gas releases heat and condenses to the lower temperature side. Since the operating temperature range of most electronic equipment is 25-150 ℃, the water heat pipe is the most commonly used. It has a series of advantages, such as high thermal conductivity, excellent isotherm, variability of heat flux density, reversibility of heat flow direction, long-distance heat transfer, constant temperature characteristics (controllable heat pipe), thermal diode and heat switch performance. The heat exchanger composed of heat pipe has the advantages of high heat transfer efficiency, compact structure and small fluid resistance loss.

(5) Vapor chamber

The vapor chamber is a vacuum chamber with micro structure on the inner wall, which is usually made of copper. When the heat is transferred from the heat source to the evaporation zone, the cooling liquid in the cavity begins to vaporize after being heated in a low vacuum environment. At this time, the heat energy is absorbed and the volume expands rapidly. The gas-phase cooling medium fills the whole cavity rapidly. When the gas-phase working fluid contacts a relatively cold area, condensation will occur. By releasing the heat accumulated during evaporation by condensation, the condensed coolant will return to the evaporation heat source through the microstructure capillary tube, and this operation will be repeated in the cavity.

(6) Fan forced convection cooling

Air cooled heat dissipation is the most common, and very simple, is to use a fan to take away the heat absorbed by the radiator. The price is relatively low, and the installation is simple, but it is highly dependent on the environment. For example, when the temperature rises, the heat dissipation performance will be greatly affected.