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For light-emitting diode (LED) packages, temperatures, especially junction and phosphor temperature, can greatly affect the optical performance. Thus, measuring the temperatures accurately is of significance for the performance estimation. Among the methods of measuring temperature, physical contact method, represented by thermocouple method, is most convenient and economical. In this paper, we measured...
Die attach process is widely used to realize the connection between die, device and the rest of the system in electronic packaging. During this process, the die moves under the capillary force induced by the liquidus solder. Such a die tilt phenomenon usually occurs and strongly worsens the reliability and performances of devices. In this paper, we built a numerical model based on fluid minimal free...
Analytical solution is established to calculate equivalent thermal resistances of the through silicon via (TSV) structure in both z direction and x y directions and is verified by the finite element simulation. The effects of the structural parameters such as the thickness of die, the diameter of copper via and the pitch of the copper via on the equivalent thermal conductivity of composite TSV structure...
As the power density enhances while package size decreases, thermal management becomes a primary concern of the reliability and performance of the electronic packaging. When the natural convective heat transfer can't meet the thermal budget, a forced convective heat transfer must be employed in order to prevent the inappropriate temperature and thermal induced stress which would cause many problems...
To analyze the effect of moisture on the reliability of LED modules, diffusivity of packaging materials must be provided. Polycarbonate (PC) is an important material for LED lens. Its diffusivity measurement is usually based on the solution of one-dimensional diffusion. In this paper, the diffusivity measurement of PC was conducted. Simulation and analytical close-form solution (CFS) were also used...
Unless their reliability is no longer a concern, light-emitting diodes (LEDs) will be unable to be used for broader applications. One important factor in the operating environment of LEDs is moisture, which is always present if the packaging is not hermetically sealed. In order to investigate the effects of moisture on the reliability of LEDs, several high-power white LEDs were subjected to extremely...
High power white light emitting diodes (LEDs) have begun to play an important role in many illumination applications due to their excellent performance. In this paper, an effective freeform lens design method for extended light source was suggested briefly for the first time and two compact LED packaging freeform lenses, with the material of polycarbonate (PC) and silicone respectively, were designed...
The state of phosphor will greatly influence the packaging performance such as luminous efficiency, quality of white light and color uniformity. The analysis presents that the small variations of thickness and concentration could significantly influence the light extraction efficiency and the correlated color temperature (CCT). With the increase of thickness and concentration, the light extraction...
High power LED packaging is crucial for the development of solid state lighting. Different optical structures with various states of phosphor will greatly influence the packaging performance such as luminous efficiency, quality of white light and color uniformity. Through the analysis of five different optical structures, it is found that the location of phosphor layer has low impact on the light...
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