High power LED heat dissipation path

In the structural design of high power LED is attached great importance to the cooling. Figure 2 is the internal structure of K2 series Lumiled company, figure 3 is the internal structure of NICHIA NCCW022 company. Can be seen from the chart below the tube core has a size larger metal cooling pads, it can make the tube core heat reached out through the cooling pads.

high power LED is welded on the PCB ( PCB) , as shown in figure 4. Cooling pads of the bottom of the PCB surface coated copper welding together, with larger coated copper radiating surface layer. In order to improve the cooling efficiency, the use of double coated copper layer PCB, its positive and negative graphics as shown in figure 5. This is one of the simplest heat dissipation structure.

heat from high temperature to low temperature heat dissipation. The main path of the heat dissipation is high power LED is the tube core - cooling pads - PCB apply to printed circuit board, copper layer ambient air. If the LED junction temperature for TJ, ambient air temperature for TA, cooling the temperature of the bottom part of the Tc ( TJ>Tc>TA) , the cooling path is shown in figure 6.

in the process of heat conduction, heat conduction performance of various materials, which have different thermal resistance. If the tube core conduction to the thermal resistance to heat dissipation on the surface of the bottom (RJC Thermal resistance of leds) Conduct, cooling pads to the PCB surface coated copper layer of thermal resistance for RCB, PCB conduction thermal resistance for the RBA to ambient air, from the junction temperature of tube core TJ conduction of the total thermal resistance of the air TA RJA relation with the thermal resistance for

RJA = RJC + RCB + the RBA

the thermal resistance of the unit is ℃ / W. Can understand the thermal resistance is smaller, the thermal conductivity, the better, the better the performance of the heat dissipation.

if the cooling pads of the LED and PCB apply copper layer USES the reflow soldering together, the RCB = 0, the type can be written as RJA = RJC + the RBA

Sophy

China lighting network