| 초록 |
Light Emitting Diode(LED) is largely used in industry of consumer electronics such as cell-phones, PDAs, and computers. Since all light sources convert electric power into radiant energy and heat, LED also does the same. However, it only converts 15∼25% of electric power into visible light; the rest of the power, 75~85%, is converted into heat. This excess heat should be conducted away from the LED die to circuit boards or heat sinks since heat directly affects performance of the LED. As a short term effect, which is reversible, it will bring color shift and reduced light output. Furthermore, lifecycle of the LED will shorten non-reversibly if the problem continues. In order to prevent LED from these negative effects, low thermal resistance path needs to be achieved so that heat conducts from the LED to underlying circuit board. Thus, thermal-via optimization study is performed through experiment. 1W and 3W LED assembled printed circuit board (PCB) with 16 different via design is set up to measure its temperature for 4 hours in a real time. Via design is differed by number, diameter, and pitch of vias. For 1W LED assembled PCB, 350mA was given; and for 3W LED assembled PCB, 700mA was given. |
