Deborah Ann Haitko

Chip to System Levels Thermal Needs and Alternative Thermal Technologies for High Brightness LEDS

Light emitting diodes (LEDs) historically have been used for indicators and produced low amounts of heat. The introduction of high brightness LEDs with white light and monochromatic colors has allowed them to penetrate specialty and general illumination applications. The increased electrical currents used to drive the LEDs have resulted in higher heat fluxes than those for average silicon integrated circuits (i.e., ICs). This has created a need to focus more attention on the thermal management engineering of LED power packages. The output of a typical commercial high brightness, 1 mm 2 , LED has exceeded 100 1m at drive levels approaching 3 W. This corresponds to a heat fiux of up to 300 W/cm 2 . Novel thermal solutions need to address system architectures, packaging, phosphors for light color conversion, and encapsuianfs and fillers for optical extraction. In this paper, the effect of thermal management on packaging architectures, phosphors, encapsulants, and system design tire discussed. Additionally, discussions of microscopic defects due to packaging problems as well as chip active layer defects are presented through experimental and computational findings.

A convenient synthesis of copper(I) carboxylates

Abstract A simple procedure is described for the synthesis of aliphatic and aromatic copper(I) carboxylates by the reduction of copper(II) carboxylates with commercially available tin(II) 2-ethylhexanoate. In this way copper(I) acetate, benzoate and stearate have been prepared in good yield and purity from the corresponding copper(II) carboxylates.

Thermal Needs and Challenges for the Solid State Lighting Devices: Materials to Packages

Light emitting diodes historically have been used for indicators and produced low amounts of heat. The introduction of high brightness LEDs with white light and monochromatic colors have led to a movement towards specialty and general illumination applications. The increased electrical currents used to drive the LEDs have focused more attention on the thermal paths in the LED packages and developments in LED power packaging. The luminous efficiency of LEDs is soon expected to reach over 80 Lumens/Watt that is approximately 6 times more than a conventional tungsten bulb. The thermal challenges include but not limited to chip architecture, packaging, phosphors for light conversion, encapsulants and fillers for optical transparency, interconnects for both electrical and thermal reasons. A typical LED power-package has a 1mm2 surface area with a total heat generation of 1 W. This corresponds to a heat flux of 100 W/cm2 , which is much higher than heat fluxes at the current electronics packaging. In this paper, effect of the thermal management on packaging architectures, as well as phosphor and encapsulants are discussed. Discussions on the microscopic defects due to packaging problems as well as chip active layer defects are presented through experimental findings.Copyright