EMC & Thermal Management


Selecting heatsinks efficiently H


eatsinks made of extruded aluminium are often the preferred method of choice when sourcing


heat dissipation solutions for electronic semiconductor devices. Heatsink solutions provide efficient


thermal management, but purchasers also need to consider thermo-technical performance and other functional features to determine how suitable a heatsink is for their project. The heat dissipation process of


electronic components is usually made by means of an active or passive system, also known as free convection and forced convection (by using additional fans or motors) forms of dissipation. The forced heat dissipation usually offers


increased performance of the heat dissipation air flow, but due to the application, specific features or the resulting noise level has to be applied in a certain way. Extruded heatsinks are an efficient source for dissipating electronic semiconductor devices for smaller and larger power losses. The surface enlargement of the fin


structure has its restrictions by way of construction size, like volume or weight and also physical limitations caused by the specific thermal conductivity of aluminium. Heatsink compatibility is a crucial


element in the selection process and with


such broad a range of design and sizes available on the market, it is often hard for buyers and engineers to determine the profile they need.


Selecting the right heatsink Selecting the most suitable heatsink for your requirement will depend on two factors; the application it is being used for, and whether it will achieve efficient dissipation results based on the geometry of the chosen design. 1) The easiest way to select the right


heatsink is to calculate the thermal resistance for the application and consider the maximum temperature range and the amount of heat dissipation required from the device. 2) Heatsink manufacturers tend to


specify the heatsinks thermal resistance in the form of numerical values, diagrams or datasheets. It is often more time-effective for buyers and engineers to contact the heatsink manufacturers direct to determine the heatsink specification required. 3) Another important element to


consider when selecting a heatsink is the installation position of the heatsink. If the optimum mounting direction of the heatsink in the application cannot be achieved due to mechanical conditions or space requirements, buyers will need to consider this in their thermal resistance


calculation. Differing heatsink installation positions can sometimes reduce thermal resistance depending on the heatsink geometry by approximately 10-15 per cent. 4) Alongside the heatsinks length, the fin


height also has to be adjusted to the heat source for the heatsink selection. It’s important to consider the fin efficiency of a heatsink, including the combination of thermal resistance of the heatsink impeding the flow and the heat lost due to convection, the temperature of the fin and the heat transfer to the fluid. The correct fin height in connection to


the right width enters a saturation region at a certain point which means that thermo- technically seeing an enlargement of the fin would have no affect. The fin temperature would be set to the level of the ambient temperature at a certain point. 5) Fin geometry is the next factor to


consider when selecting a heatsink. Rectangular fins are usually used for force convection and conical fin shapes are mainly used for free convection. If fans are required in the design, it is often recommended that the engineer uses rectangular fins. Efficient heatsinks are an essential


component of any power semiconductor system and GD Rectifiers have a wide range of extruded aluminium heatsinks available from stock.


GD Rectifiers is one of the UK’s leading


heatsink manufacturers, they can provide standard heatsinks from over 160 profiles in stock or customised heatsinks bespoke to their customer’s requirements. All extrusions can be supplied as cut


lengths or drilled and machined to customer specifications. They operate the latest CNC drilling and machining centres which provide accurately machined, cost- efficient parts on short lead times. GD Rectifiers’ extensive range of


aluminium, water-cooled and forced-air- cooled heatsinks can be supplied in a natural or black-anodised finish. They stock and machine the largest range of heatsinks suitable for LED lighting applications and stud, modules and capsule semiconductors. GD Rectifiers benefit from having their manufacturing facility in-house, offering a wide selection of high quality heatsinks readily available with material in stock.


gdrectifiers.co.uk


12 June 2019


Components in Electronics


www.cieonline.co.uk


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