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Ways to solve LED heat dissipation

Apr 24, 2020

Ways to solve LED heat dissipation

3. 1 Substrate selection with good thermal conductivity

Select substrates with good thermal conductivity, such as Al-based metal core printed circuit boards (MCPCBs), ceramics, and composite metal substrates, to accelerate heat dissipation from the epitaxial layer to the heat sink substrate. By optimizing the thermal design of the MCPCB board, or directly bonding the ceramics to the metal substrate to form a metal-based low-temperature sintered ceramic (LTCC2M) substrate, a substrate with good thermal conductivity and a small thermal expansion coefficient can be obtained.

3.2 Heat release on the substrate

In order to spread the heat on the substrate to the surrounding environment more quickly, currently, metal materials with good thermal conductivity such as Al and Cu are usually used as heat sinks, and forced cooling such as fans and loop heat pipes are added. Regardless of cost or appearance, external cooling devices are not suitable for LED lighting. Therefore, according to the law of conservation of energy, the use of piezoelectric ceramics as a heat sink to convert heat into vibration and directly consume heat energy will become one of the focuses of future research.

3.3 Method of reducing thermal resistance

For high-power LED devices, the total thermal resistance is the sum of the thermal resistances of several heat sinks on the heat path from the pn junction to the outside environment, including the internal heat sink thermal resistance of the LED itself and the internal heat sink to the PCB board. The thermal resistance of the thermally conductive glue, the thermal resistance of the thermally conductive glue between the PCB and the external heat sink, and the thermal resistance of the external heat sink, etc., each heat sink in the heat transfer circuit will cause certain obstacles to heat transfer. Therefore, reducing the number of internal heat sinks and using a thin film process to directly produce the essential interface electrode heat sinks and insulation layers on the metal heat sink can greatly reduce the total thermal resistance. This technology may become a high-power LED in the future. The mainstream direction of heat dissipation package.

3.4 Relationship between thermal resistance and heat dissipation channel

Use the shortest possible heat dissipation channel. The longer the heat dissipation channel, the greater the thermal resistance and the greater the possibility of thermal bottlenecks.