Fig. 1. Schematic illustration of chip-on-board (COB) type LED array module with ceramic-metal PCB: (a) single chip and (b) multichip mounted module.
Fig. 2. Circuit diagram of 50 watts rated LED array module consisted of 36 LED chips.
Fig. 3. Schematic illustration of LED array module with thermal-via type FR-4 PCB: (a) single chip and (b) multichip mounting module.
Fig. 4. Optical images of fabricated 50 watts rated LED array module panels: circuit layout of 4 × 9 LEDs arrayed on ceramic-metal hybrid PCB panel (a) without top protection layer, (b) with top protection layer, and (c) comparative LED array module made with thermal-via FR-4 PCB.
Fig. 5. Measurement of Ta in 50 watts LED array modules using multipoint temperature sensors (without thermal tape): (a) with COB type ceramic-metal PCB, (b) temperature measuring point, and (c) with thermal-via type FR-4 PCB.
Fig. 6. (a) Thermal resistance data obtained by cumulative structure functions of 50 watts rated 4 × 9 LEDs array modules with (I) COB type ceramic-metal PCB and (II) thermal-via type FR-4 PCB and (b) equivalent thermal resistances and thermal capacitances circuit by Cauer-type RC ladder model.