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Posted on 11 June 2019

Cooling Low Power Components

 

 

 

 

 

 

 

With low power semiconductor components, the case surface and the terminals are normally sufficient to dissipate heat losses. The tracks on the printed circuit board (PCB) that are used to solder the connections can also play a big role in dissipating heat losses. For this reason, the junction to ambient thermal resistances specified for low-power components only apply to the condition that the component is located directly on a PCB and that the tracks are of normal width (2-3 mm) and feature normal tin plating across their entire area.

Components with wire connections can also be integrated at a distance of 3-25 mm from the PCB. The thermal resistance increases in proportion to the length of the wires. Therefore, shorter wires result in a reduced resistance.

Thermal resistance  can also be reduced by 25-30% by using very wide tracks with all-over tin plating. In this case, the component must be mounted directly onto the PCB. Low power semiconductor devices with rectangular shaped plastic cases are sometimes mounted onto a cooling plate or chassis plate using a clamp. The permissible current load for a given plate (with a certain minimum size) will be specified in the datasheet. Sometimes, the thermal resistance between the junction and a reference point is specified at one of the terminals.

By measuring the temperature at the terminals or a specific reference point, as well as the power dissipation that occurs in the component, the virtual junction temperature can be monitored in an application to ensure the maximum permissible temperature is not exceeded.

 

For more information, please read:

Liquid Cooling Systems

Heat Dissipation Using Cooling Plates

Heat Dissipation and Cooling for Aluminium Capacitors

Thermal Dimensioning of Bridge Rectifiers

 

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