Prototype Design And Testing Of Efficient Metal Printed Circuit Boards (M-Pcbs) As Heat Sink For High Power Leds
Loading...
Date
2016-01
Authors
Ong, Zeng Yin
Journal Title
Journal ISSN
Volume Title
Publisher
Universiti Sains Malaysia
Abstract
In solving the thermal challenges in LED operation, an investigation on designing the thermally efficient printed circuit board (PCB) has drawn the attention of many industries. Metal-core printed circuit board (MCPCB) has been an excellent choice. Though it is an excellent heat spreader in reducing the excessive temperature at the LED junction, the fabrication of MCPCB involves various process steps and number of layers. More PCB layers create high thermal resistance (Rth) which is contributed by several interface layers. Therefore, it is necessary to identify high thermal conductive material on metal substrate with minimal interface layers for better heat transfer and efficient LED operation. In this research, boron doped aluminium nitride (B-AlN) thin films on Al substrates were prepared by two different techniques which are DC & RF co-sputtering and low temperature chemical vapour deposition (CVD) at atmospheric pressure with alternative precursor. The synthesis parameters were varied and developed to obtain good quality B-AlN thin film. Among the synthesis techniques, films prepared by CVD method showed better structural properties and were chosen for fabrication of prototype PCBs. Prior to the PCB fabrication, B-AlN coated Al substrates were tested for their thermal and optical performances as heat sink (Thermal Substrates) using transient analysis method of the high power LED and LED spectrometer. Several prototype PCBs (M-PCBs) were eventually fabricated on B-AlN coated Al substrates and tested for their thermal and optical performances with high power LEDs mounted on prototypes. The comparison between M-PCB and commercial MCPCB had shown that the M-PCB prepared from B-AlN thin film coated by CVD process (CVD 4) had better thermal performance than MCPCB. At 700 mA driving current, M-PCB significantly achieved lower Rth-tot
and Rth-pcb as compared to MCPCB under the same operating condition. The rise in junction temperature of LED (ΔTJ) was controlled and reduced drastically from 65.77 °C to 52.55 °C by using M-PCB as compared to that with MCPCB. The correlated colour temperature (CCT) value of the LED on M-PCB at 700 mA was lower (≈8100 K) when compared with commercial MCPCB (≥10000 K) and avoided the colour shifting towards ―bluish‖ colour. It was found that M-PCB also showed increased luminous flux (68.38 lm) as compared with MCPCB (61.83 lm).
Description
Keywords
LED operation.