Grants and Contributions:

Grant or Award spanning more than one fiscal year (2017-2018 to 2018-2019).

Thermal management is a fundamental limiting factor in solid state lighting applications, affecting the devicex000D
reliability and luminous efficacy. In high-power applications, the increased chip density exacerbates the needx000D
for efficient heat dissipation pathways. Chip-on-board (COB) approaches improved the state of the art byx000D
removing the need to individually package LED chips, while yielding better cooling efficiencies by providing ax000D
more intimate thermal contact between the chip and heat sink. However, in COB LED products the flat boardx000D
design limits the heat spreading that can take place at the interface with heat sinks. A recessed heat sinkx000D
carrying the COB is proposed as an approach to improve the heat spread within the heat sink, and therebyx000D
improve the cooling efficiency of the COB assembly. While the idea is attractive, the design trade-offs in termsx000D
of cooling capabilities, recess depth & shape and their impact on the luminous intensity spatial distribution arex000D
unknown. Additionally, the recessed heat sink material and relative placement of the phosphor may have anx000D
adverse effect on the color output of the light fixture. Systematic studies of heat sink-recessed COB designs canx000D
yield insights into these trade-offs and optimum operating points. The research can improve the adoption ofx000D
high-power solid state lighting in industrial applications, with tremendous environmental benefits, as thex000D
increase in light output per watt consumed greatly reduces energy waste and green-house gas emission fromx000D
non-renewable energy sources.