| dc.description.abstract | Recently, light-emitting diode (LED) has been playing an important role in solid-state lighting, especially the maturity of the micro process technology made the multiple microchips LED receive recognition in the market. The multiple microchips LED is a kind of new type LED which is connected by many multi-microchips in array way, if we design the multi-microchips in serial array, that we can not only raise the input voltage levels in the traditional single chip LED, but use the alternating current (AC), full-wave current and direct current (DC) these three ways to light up. However, the single chip only can drive in DC way. In my research, we put single chip and multiple microchips under the condition of same size and same epitaxy, driving with the DC. For different wattage, we can compare the difference of single chip and multiple microchips in the relation of electricity, temperature and light. Also, we use the result of light output power measurement to revise the governing equation of coupling of the thermal and electrical characteristics in the numerical
methods.
First, we use the measurement of junction temperature and optical characteristics to test and verify with the numerical analysis, then using the simulation result to analyze the different current density and temperature distribution between the single chip and the multiple microchips. According to the research, we found the electric distribution of the multiple microchips is partial-crowding, not alike the single chip is whole-crowding. This difference makes the multiple microchips is equally distributed and lower the junction temperature. Bacause of its series connection design, the multiple microchips turn into high voltage -low current and cause chip produce lower joule heat. Higher watts we use, the more different between the tradition single chip and multiple microchips. This is the reason why the multiple microchips can make lower temperature and better light output power. And last, we try to use numerical methods to simulate how high watts would caused LED destroy. From the result, we found the single chip under 8 watts has already reached Light saturation but the multiple microchips hasn’t because of its lower temperature. In addition, we can also calculate theses two LED can bear the temperature in about 5 watts . If we keep enhance the electric power may cause the package damaged and when the power reach about 8 watts, the junction
temperature of these two chips would be unbearable.
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