Thermally Conductive Materials in LED Assemblies
Although LEDs are considerably more efficient than traditional lighting forms, they do still produce heat. This heat can have an adverse effect on the LED and therefore must be managed to ensure the true benefits of this technology are realized. If excessive junction temperatures are reached, particularly above the maximum operating temperature of the LED (~120-150˚C), a non-recoverable effect could occur, leading to complete failure. Operating temperature is a directly related to the lifetime of the LED; the higher the temperature, the shorter the LED life.
Depicts a Typical LED Package Design [Image credit: "LED package" by Chaohsinwu at English Wikipedia]
Since heat is lost from a component to its surroundings at its surface, the rate of dissipation will increase with surface area. This is where heat sinks are used - varying in size and shape, heat sinks can be designed to offer a significantly increased surface area to maximize heat dissipation. Heat sinks are often used in LED applications and fix onto the back of the component. Ideally, these mating surfaces should be perfectly smooth enhancing the efficiency of heat conduction, but this is not usually possible. As a result, air gaps will be present at the interface of the device and the heat sink, significantly reducing the efficiency of heat transfer.
There are many ways to improve upon the thermal management of LED products and therefore, the correct type of thermally conductive material must be chosen in order to ensure the desired results for heat dissipation are achieved.
Marian offers a variety of Thermal Interface Materials die-cut to specific shapes for LED Lighting Assemblies: Gap pads, phase change, pressure sensitive adhesive pads.
Also, read our guide to selecting the right thermal interface material for your application.