Temperature management in electronics housings.
One of the basic challenges related to electronics housings is heat dissipation, which is related to the heating of electrical, and thus mechanical elements inside the housings.
In most cases, the critical temperatures for the individual components are not exceeded. However, if the components reach their performance limits, sufficient heat transfer must be provided to lower the temperature, otherwise the device may be damaged.
Empty electronics housings need to accommodate much more than just a PCB with electronic circuits. The power connection and signal connections must go to the PCB and back out. Enclosures should be as compact as possible, while ensuring protection against contamination and accidental contact with live parts. Electromechanical and electronic miniaturization leads to ever higher packing densities If high-performance processors or other power components that dissipate large amounts of heat are used on PCBs, it can overheat the system.
Thanks to passive heat sinks developed for the ICS family of housings, the finished devices can be used in applications designed to operate in high temperature conditions. By performing thermal simulations, Phoenix Contact also supports the optimization of printed circuit board layouts.
Figure 1: Miniaturization has its limits - higher packing densities require cooling.
Air vents, fans and cooling fins
One of the heat dissipation options uses the physical direction of the air flow. The casing is equipped with ventilation holes, so that, when mounted on a DIN rail, cooling air can flow through it. The generated heat losses are dissipated upwards. Thermally stressed components should be installed close to the lower vents to allow "fresh air" to circulate around them. At the same time, these hot spots should not affect other temperature-sensitive components.
The width of the ventilation slots plays a key role. If it is less than 2 mm, the gaps are practically ineffective, and above 2.5 mm they limit the desired protection against contact. Side elements with any number of vents can be placed over the ICS housing lenses as needed.
Figure 2: ICS housing family with modular Push-in technology - 50 mm wide housing has an integrated heat sink.
In an attempt to improve cooling air circulation and prevent heat build-up, it may be advantageous to select a wider housing. Circulation can also be supported by active elements such as fans. They cause the airflow velocity in the housing to increase rapidly, allowing much more heat to be dissipated. The disadvantage of the fan is the risk of its failure and energy consumption. The cooling air also allows a significant part of the contaminants to enter the housing. Many device manufacturers are reluctant to include moving components in their applications. Peltier modules are also a possible solution, but due to their power consumption and the possible cooling capacity they are only of limited use.
If the normal convection of air flowing through the enclosure is insufficient for cooling, passive heat sinks made of heat-conducting metals such as copper or lighter aluminum are an alternative. Ribs are often added to hollow aluminum heat sinks to significantly increase the surface area of the heat sink.
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