How to avoid thermal problems in circuit design?

- Dec 26, 2016-

The importance of thermal design is becoming more and more important.

Recalling this year's consulting content, the mind emerged is 4K, EV (electric vehicle), SiC, NAND flash and other keywords. The use of "4K" image equipment because of high precision image processing, so the processing load is high, the heat also increases. For this reason, TV sets, smart phones, digital cameras on the thermal design of the more stringent requirements. Achieve full cooling, help product differentiation. The advantages and disadvantages of thermal design will be about the characteristics of the product.

EV aspects, whether pure electric vehicles or hybrids, heating density are increasing. This is because, in order to improve fuel efficiency, extend mileage, power control unit (PCU), motors and batteries are to miniaturization and lightweight development. Moreover, intelligent vehicles need information processing equipment, to be used in more harsh environments than other consumer products, so heat is critical.

Although most of the current SiC only in local use, but to cool the heating density of small chips, it is necessary to optimize the heat source from the external air cooling path.

Thermal design should also take new initiatives.

Yes. In this market environment, more and more heat related technology topics. Different from the past, the problem of "getting hot and not working" is increasing. Due to the fine degree of improvement of manufacturing process, the leakage current increases, and thus fall into the "spiral cooling capacity slightly insufficient, the temperature increased slightly, the increase in leakage current, increasing heat, the temperature continues to rise. This phenomenon can be called "failure to enlarge", but also in the past do not attach much importance to the heat of the circuit designer, re aware of the terrible heat.

In the past, the cooling capacity is sufficient to deal with the maximum heat of heat design is more common, but the use of such design, the device size is too large to meet market requirements. So give priority to the development of miniaturization. In this way, the equipment can not have the ability to deal with the maximum heat of cooling capacity, the need to strictly regulate the use of equipment in the temperature rise after reducing processing performance (reduce screen brightness, etc.). What needs now is "how to use, how long can use" dynamic thermal design.

Moreover, in order to achieve both thermalization, averaging as much as possible, it is still widely research on heat pipe, heat cavity cooling device, and storage materials (PCM), small forced air cooling (micro fan).

To meet the future market requirements, what is necessary for thermal design?

All along, the thermal design from the release of heat "circuit design" and cooling "mechanical design" two aspects. Air cooling equipment (fan, radiator and other cooling devices as the center of the cooling system design equipment) can use this design structure.

However, for these recent by improving the circuit board configuration and wiring, a contact, without the use of cooling devices to cool the circuit board and the casing of the device, the design must be in the circuit board and the casing is embedded in the heat path. Therefore, all personnel involved in product design, must have a certain knowledge of heat dissipation, must have (Culture) from parts, circuits to the chassis, throughout the heat design personnel.

In addition to personnel staff, responsible for design cooling measures and detection simulation technology, quality assurance department, product evaluation department personnel to carry out the verification and evaluation of products in the development stage should also learn some knowledge of radiation. Evaluation of the real machine personnel, should master high-precision temperature detection methods, cooling devices and materials evaluation methods, personnel involved in simulation and design verification, should master the analytical modeling skills.

In order to break the status quo, many companies are using thermal fluid simulation. But often hear "analysis and measured results inconsistent" sound.

To improve the analysis accuracy, not only need to improve the accuracy of input data, but also need to control the results, that is, temperature detection error. From this perspective, the implementation of temperature detection, contact thermal resistance detection, fan characteristics testing.

In order to utilize the simulation, characteristic is very important to grasp the real machine. Of course, the accumulation of simulation using technology (modeling and meshing) is also very important.

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