Analysis of LED heat dissipation module heat transfer material
In LED product applications, it is often desirable to assemble multiple LEDs onto a circuit substrate. In addition to playing the role of the LED module structure, on the other hand, as the LED output power is getting higher and higher, the substrate must also play the role of heat dissipation to transmit the heat generated by the LED crystal, so in the material selection. Must meet structural strength and heat dissipation requirements.
Conventional LEDs do not have a large heat dissipation due to the small amount of heat generated by the LEDs. Therefore, a general copper foil printed circuit board (PCB) can be used. But with the increasing popularity of high-power LEDs, PCBs are no longer sufficient to meet cooling needs. Therefore, the printed circuit board needs to be attached to a metal plate, the so-called Metal Core PCB, to improve its heat transfer path. In addition, there is also a method of directly forming an insulating layer or a dielectric layer on the surface of the aluminum substrate, and then forming a circuit layer on the surface of the dielectric layer, so that the LED module can directly bond the wires to the circuit layer. At the same time, in order to avoid increasing the thermal impedance due to the poor thermal conductivity of the dielectric layer, a perforation method is sometimes adopted, so that the heat spreader at the bottom end of the LED module directly contacts the metal substrate, that is, the so-called chip is directly adhered. Next, several common LED substrate materials are introduced and compared.
Printed circuit board (PCB)
The commonly used FR4 printed circuit board has a thermal conductivity of 0.36 W/mK and a thermal expansion coefficient of 13 to 17 ppm/K. It can be a single layer design or a multi-layer copper foil design. Advantages: mature technology, low cost, and can be applied to large-sized panels. Disadvantages: Poor thermal performance, generally used in traditional low-power LEDs. As shown below:
(1) Heat dissipation
Conventional printed board substrates such as FR4 are poor conductors of heat, insulated between layers, and heat is not emitted. Metal-based printed boards can solve this heat dissipation problem.
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