Heat Dissipation Analysis Of LED General Lighting Lamps Based On Thermally Conductive Plastics

Light emitted diode (abbr. LED), a semiconductor diode which is able to convert electrical energy into light energy, has been hailed as the fourth generation light source with several advantages of energy saving, environment-friendly design, long service life, small size, good monochromaticity, and short starting time. LED shows a promising future in each area.However, LED whose lifetime depends on the quality of thermal management is different from traditional lighting sources. Nowadays, with the development of thermal conductive plastics, there is a new direction in designs of LED general lighting lamps with the aim to offer a set of feasible heat dissipation scheme.This thesis, starts from the introduction of LED’s structure, and shows the present situation of thermal technology of LED lighting products both at home and abroad. On the basis of presentation of varieties and characteristics of thermal conductive plastics, the feasibility of whether heat conductive plastics can be developed into thermal material would be analyzed. In the use of high-power LED as lighting sources (operating current over 100mA) and MCPCBs, MR16 spotlights are taken as the research object to measure the junction temperatures and luminous decays of LED between under the condition of a thermal conductive plastics heat sink and under an aluminum heat sink.The experimental results show that although thermal conductive plastics, as the heat sink of MR 16 spotlights, can be used as thermal material, the junction temperature of LED is 91.8℃ (30℃ ambient temperature), which is 4.5℃ higher than aluminum heat sink and the LED luminous decay rate is faster as well, in case where three LEDs and 350mA forward current are used.After the forward current is changed from 350mA to 310mA, and the junction temperature of LED in thermal conductive plastics heat sink is reduced to the same level with aluminum heat sink, the junction temperature of LED is successfully maintained at about 84.7℃ (30℃ ambient temperature), which secures long service life of LED. Meanwhile, the illuminance of it is deceased by only 9.8%, which can totally satisfy the demand in a number of locations where requirement for illuminance is not seen as quite demanding.