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This paper presents numerical studies on thermal performance of LED filament light bulbs with different bulb sizes, phosphor diameters, and phosphor shapes. A quarter of numerical model of LED filament light bulbs was built to analyze the temperature field, velocity field and distributions for convective heat flux coefficient on the filament surface. The effects of bulb sizes, phosphor diameters and...
In this paper, a mechanical lock is first proposed and designed for LED silicone lens mounting. Since LED has many new applications in areas such as automobile headlight, micro-projector and local network optical communication, a potential serious issue must be solved. Due to the poor adhension between silicone and mostly materials including silicon, silicone lens may drop off from the silicon substrate...
Rapid and extensive changes in airport lighting have been made within several years. The necessity for providing elevated light intensity runway under low visibility conditions, which has been written into airport construction standard. Intensity distribution is a key parameter for aircraft illumination system. Generally, different aircraft taxilane conditions have different standards calling for...
In this paper, we present our recent research on phosphor glass ceramic technology, consisting of a ceramic plate of Ce (III) doped yttrium aluminum garnet (YAG:Ce) YAG glass ceramic. The glass ceramic is fabricated through high temperature solid state reaction method, and is detected to confirm crystal phase by SEM and XRF. The white light is successfully observed by packaging the glass ceramic slice...
As the most promising candidate for the realization of high-efficiency light sources for general lighting, the high power lighting emitting diodes (LEDs) still have reliability issues that hinder the large scale application of LED devices. Nowadays, the reliability is becoming an essential barrier for LED devices to substitute the traditional light sources. Before it is applied into mass production,...
Phosphor geometry is one of key factors which affect the optical performance for white light emitting diode (LED). In the optical simulation of LED packaging, the phosphor geometry was usually assumed as a sphere cap, but in fact, it is not a sphere cap. Therefore, the simulation results based on such an assumption may not be accurate. In this paper, a precise model of phosphor geometry for a common...
Low light extraction efficiency (LEE) is one of the most challenging points for light-emitting diode (LED) array packaging. Analysis of LEE enhancement of LED array packaging with micro-structures on packaging silicone is presented. To obtain high LEE, micro-structures including inversed cone, inversed frustum of a pyramid (FP) and V-groove are introduced. Two types of LED chips consisting of conventional...
The degradation of high power GaN-based blue light-emitting diodes (LEDs) was investigated by considering the electrical, optical and electroluminescence spectrum aging characteristics. The LED samples are stressed at the condition of 85°C and 85% RH using an injection current of 1000 mA. Optical output power decreases to 80% of initial value after 1000 hours of temperature/humidity accelerated tests...
Multi-physics multi-scale modeling issues in various stages of the LED manufacturing, 3D-SiP, and nano interconnects have been discussed. Molecular dynamics (MD) and finite element method (FEM) have been used to study the scale effect of the material properties and the prediction of the module behaviors which are critical to LED fabrication. We propose a new concept to integrate multi-physics/multi-scale...
Undesired residual stress always exists in light emitting diode (LED) after the process of metalorganic chemical vapor deposition (MOCVD) due to difference in thermal expansion coefficient of different layers, doping, and lattice mismatch. Residual stress would mostly induce defects in the process of LED chips, the packaging, accelerated testing and their applications. The influence of strain/stress...
As high power LEDs develop rapidly, sapphire substrate on which LED's chips are grown, cannot meet the needs of the increasing performance any longer. Therefore, transfer of the devices from the former sapphire substrates to more thermally and electrically conductive receptor substrates is recommended. Laser peeling has been a new technology of separating films of GaN from the substrate on which they...
In this paper, we demonstrate a packaging method for component of light emitting diode (LED) by silicon bulk micromachining technologies and using a silicon substrate with Cu/M/Cu foil to dissipate heat and match thermal expansion coefficient (CTE). The objective is to develop an LED package that can overcome high brightness LED life, high operating current and the ability to drive the devices at...
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