Changes in technology trends and thermal design
In recent years, "miniaturization", "high functionality", and "design flexibility" have become the development trend of semiconductor component technology. What we need to consider here is how these trends in semiconductor components will affect thermal and thermal design.
"miniaturization"
The demand for miniaturization of products has promoted the miniaturization of ICs, mounting circuit boards, and other capacitors. In the process of miniaturization of semiconductor components, for example, IC chips packaged in larger through-hole packages such as TO-220 are not currently packaged in much smaller surface mount packages. Rare.
Moreover, some methods to improve integration have been adopted. For example, the IC chips mounted in the same package are adjusted to two to double them, or the integration level is increased by putting in chips equivalent to two chips, thereby increasing the functions per unit area (functional area ratio).
The miniaturization and high integration of such components will increase the heat generation. Examples are shown below. The thermal image on the left is an example of package miniaturization, which is a comparative example of a 20×20×20mm package and a 10×10×10mm package with the same power consumption. Obviously, the red color that indicates high temperature is more concentrated in the smaller package, that is, the heat is greater. On the right is an example of high integration. When comparing products with one chip and two chips in the same size package, you can clearly see that the temperature difference is also very obvious.
High-density mounting reduces the effective heat dissipation range of surface mount devices that dissipate heat to the circuit board, and the heat generation increases. If the ambient temperature in the shell is higher, the amount of heat that can be dissipated will be reduced. From the results, although the original high temperature was only around the heating components, the entire circuit board is now in a high temperature state. This even leads to an increase in the temperature of components that generate less heat.
To improve the function of the equipment, it is necessary to increase the components, or use a larger integrated IC with higher capability, and also need to increase the data processing speed, increase the frequency of the signal, and so on. These methods have led to an increasing trend of power consumption, which ultimately leads to an increase in heat generation. In addition, in order to suppress noise radiation when dealing with high frequencies, shielding is required in many cases. Since heat is accumulated in the shielding layer, the temperature conditions of the components in the shielding layer become worse. Moreover, it is difficult to increase the size of the device for the reason of improving the function, so it becomes the above-mentioned high-density state, which causes the temperature in the housing to rise.
"Design Flexibility"
In order to make products unique or to reflect aesthetics, more and more products begin to attach importance to design, and even give priority to design flexibility. The disadvantage is that the housing has a high temperature due to excessive high-density installation and inability to dissipate heat reasonably. In short, holding a portable device in your hand will feel very hot. In order to improve the design flexibility of components, that is, the degree of freedom of appearance, as described above, small or flat products can be used, but there are not a few products that give more priority to design flexibility.
The problem is not just the increase in heat generation and difficulty in heat dissipation
As mentioned above, due to the changes in the three technological development trends of "miniaturization", "high functionality", and "design flexibility", the heat generation has increased, and accordingly, heat dissipation has become more difficult. Therefore, thermal design faces more stringent conditions and requirements. It is true that this is a very big problem, but at the same time there is another problem that we need to consider.
In most cases, the company's equipment design has set evaluation standards for thermal design. If the evaluation standard is relatively old, and the recent technological development trend is not taken into account and revised again, then the evaluation standard itself has problems. If such considerations are not made, and the design is based on evaluation criteria that does not take into account the status quo, very serious problems may occur.
In order to respond to changes in technological development trends, the evaluation criteria for thermal design need to be revised.
