There are two types of heat exchangers commonly used; active and passive. The active type of exchanger uses an external source of power to transfer heat, however, the passive type works directly without any additional energy. Most common example of an active heat exchanger is a fan, and a passive heat exchanger is a heat sink or a kind of lighting housing
. A heat sink dissipates the energy produced by a mechanical or electronic source into a fluidic medium, such as air or water. This helps in regulating the temperature of a device and its efficient workability. For devices using high power semiconductors
and optoelectronics like Light Emitting Diodes (LEDs) and laser lightings, heat sinks are used for heat dissipation as the devices have insufficient capacity for exchange of heat.
Various factors under consideration for design and manufacturing of heat sinks are discussed in this article. Heat sink for an LED works by conducting heat away from the junction and then dissipating heat into air via convection or radiation. To adhere to the conduction process, material chosen must have a high thermal conductivity. As for the second process of convection or radiation, the area of the heat sink must be large enough for heat to convect into the surrounding air. This is usually carried out by forced convection to maintain effective circulation of air.
Design considerations for heat sinks have improved over time with modern LED heat sinks being aerodynamically designed with great aesthetics. This includes merging fins into the main structure which is not only visually appealing but also decreases the fin densities and depths.
Mingfa Tech goes a step forward in design considerations of their products by applying active cooling technology to their heat sinks. The new COB heatsink
helps overcome the discrepancies in the prior, in addition, to a simple and reasonable design. They possess good sealing performance and are anti-corrosion, waterproof, and dustproof, thus extending the service life of COB LED luminaire. With its high thermal conductivity, it is highly endorsed for promotion and application.
Manufacturing of heat sinks is carried out by various techniques. Each of the techniques has their own design benefits and limitations and yield different mechanical properties.
To fabricate die cast heat sinks, molten aluminum is forced into a die consisting of two halves of dies held together by hydraulic pressure. Complex shape aluminum heat sinks can be created using this technique. High dimensional accuracy and stability are obtained in die casted parts. Moreover, shapes with a high number of fins can be created easily. Mass production of LEDs is also easy in die casting processes and it is undoubtedly one of the most efficient metal forming processes.
Plastically deforming a metal material below its recrystallization temperature with the application of extremely high pressure is called cold forging. This process for LED heat sinks is the most popular one due to the properties obtained in a part such as thermal conductivity, strength, accuracy in dimensions, surface quality, cost, and productivity. Most commonly used material in cold forging heat sinks
is aluminum and its alloy. FanLED coolers
are an example of cold forged heat sinks for LEDs. They have an elegant design to offer and are widely compatible with more than 20 international COB brands. Customization of design is also an added feature in these coolers.
Heat sinks can also be manufactured by extrusion which includes plastic flow of material under compressive forces into desired shapes. As compared to die casting, extrusion based heat sinks provide better thermal conductivity as this process does not produce internal porosity. Complex profiles can be created using extrusion. This process is more commonly used for linear lighting systems.
Stamping method is adapted for sheet metal parts and is carried out by compressing metal sheets using a die. There are various methods associated with stamping including, punching, blanking, deep drawing, embossing, bending, and flanging. This process is usually used to make stake fins and insert fins.
Apart from the processes discussed above, heat sinks can also be machined into the desired shape. However, machining is not a preferred manufacturing process for heat sinks as it requires more resources, energy, and workforce as compared to the other methods.