For LEDs with original structure and copper heat spreader, the highest surface temperatures of 3×3 array LEDs
modules were 52.6 and 42.67 °C (with 1050 mA injection current), while the highest surface temperatures of 4×4 array
LEDs modules were 58.55 and 48.85 °C (with 1400 mA injection current), respectively. As the 5×5 array LEDs modules
with original structure and copper heat spreader were fabricated, the highest surface temperatures at 1750 mA injection
current were 68.51 and 56.73 °C, respectively. The thermal resistance of optimal LEDs array module with copper heat
spreader on heat sink using compound solder is reduced obviously. On the other hand, the output powers of 3×3, 4×4 and
5×5 array LEDs modules with original structure were 3621.7, 6346.3 and 9760.4 mW at injection currents of 1050, 1400
and 1750 mA, respectively. Meanwhile, the output powers of these samples with copper heat spreader can be improved
to 4098.5, 7150.3 and 10919.6 mW, respectively.
The optical and thermal characteristics of array LEDs module have been improved significantly using the
cup-shaped copper structure. Furthermore, various types of epoxy-packaged LEDs with cup-shaped structure were also
fabricated. It is found that the light extraction efficiency of LED with semicircle package has 55% improvement as
compared to that of LED with flat package. The cup-shaped copper structure was contacted directly with sapphire to
enhance heat dissipation. In addition to efficient heat dissipation, the light extraction of the lateral emitting in high-power
LEDs can be improved.