Optimized Thermal Management From a Chip to a Heat Sink for High-Power GaN-Based Light-Emitting Diodes

To improve heat dissipation of sapphire-based LEDs, we develop a new LED package with a dual heat spreader design. The first heat spreader is a cup-shaped copper sheet, which was directly contacted with sapphire to enhance heat dissipation of the chip itself. The second heat spreader is the die-bonding material of diamond-added AgSnCu solder and a high thermal conductive metal-core printed circuit board (MCPCB), where the conventional dielectric layer was replaced with a thin diamond-like layer. Characterization results demonstrate that the diamond-added composite solder is useful in reducing LED thermal resistance, thus avoiding the thermal accumulation phenomenon. In addition, a LED packaged on the new MCPCB exhibits smaller total thermal resistance and larger light output power.