Modeling on phosphor sedimentation phenomenon during curing process of high power LED packaging

Wang, Yiman; Zheng, Hao; Hu, Run; Luo, Xiaobing

doi:10.1186/2196-1107-1-2

Cited by 24 publications

(11 citation statements)

References 9 publications

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“…Generally, the silicone would spontaneously spread over the LED substrate due to the small contact angle of silicone on the substrate [12], [13], which leads to the TIR phenomenon. However, the silicone is reported to be thermosetting, which means its viscosity increases with time when it is heated [14], and the increasing rate of the viscosity is highly related to the temperature [15].…”

Section: Methodsmentioning

confidence: 99%

A Cylindrical Tuber Encapsulant Geometry for Enhancing Optical Performance of Chip-on-Board Packaging Light-Emitting Diodes

Xie

Shang

et al. 2016

IEEE Photonics J.

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Low light efficiency and poor angular color uniformity (ACU) are the key challenges of chip-on-board packaging light-emitting diodes (LEDs). In this paper, we demonstrate a phosphor geometry, and its controlling method for enhancing the optical performance of chip-on-board packaging LEDs, its fabrication flexibility, and availability are validated by experiments, and its effect on the optical performance is analyzed by optical simulations and experiments. The simulation results show that compared with the conventional flat geometry, the cylindrical tuber geometry can effectively improve the light efficiency and ACU, and the light efficiency enhancement increases with correlated color temperature. Experimental results show that for the case that the encapsulation layer only consists of silicone, the proposed geometry enhances the light efficiency up to 63.1%. In addition, for another case, in which the encapsulation layer consists of silicone and phosphor particles, when the average correlated color temperature (CCT) is about 5000 K, the proposed geometry increases the light efficiency by 11.7%, and the angular CCT deviations for the flat geometry and the proposed geometry are 1805 and 475 K, respectively.

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Section: Methodsmentioning

confidence: 99%

A Cylindrical Tuber Encapsulant Geometry for Enhancing Optical Performance of Chip-on-Board Packaging Light-Emitting Diodes

Xie

Shang

et al. 2016

IEEE Photonics J.

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“…3 and Table 1, is the key component that converts part of the blue light into yellow light, so as to finally generate white light. The phosphor gel is a kind of non-Newton fluid, which may cure after a period of time, and the curing time can be shortened when heated [11][12][13]. Fig.…”

Section: Existing Heat and Fluid Flow Problemsmentioning

confidence: 99%

Heat and fluid flow in high-power LED packaging and applications

Luo

Qiu

Liu

et al. 2016

Progress in Energy and Combustion Science

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412

121

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Light-emitting diodes (LEDs) are widely used in our daily lives. Both light and heat are generated from LED chips and then transmitted or conducted through multiple packaging materials and interfaces. Part of the transmitted light converts into heat along the light propagation; in return, the accumulation of heat leads to the degradation of light output. The accumulated heat negatively influences the reliability and longevity of LEDs, and thus thermal management is critical for LED packaging and applications. On the other hand, in LED packaging processes, many fluid flow problems exist, such as phosphor coating, silicone injection, chip bonding, solder reflow, etc. Amongst them, phosphor coating is the most important process which is essential for LED performance. Phosphor gel is a kind of non-Newton fluid and its coating process is a typical fluid-flow problem. Overall, since LED packaging and applications present many heat and fluid flow problems, obtaining a full understanding of these problems enables advancements in the development of LED processes and designs. In this review, the emphasis is placed on heat generation in chips, heat flow in packages and application products, fluid flow in phosphor coating process, etc. This is a domain in which significant progress has been achieved in the last decade, and reporting on these advances will facilitate state-of-the-art LED packaging and application technologies.

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“…The platelets will settle in silicone matrix in the case of no magnetic force (at step 1). Referring to the researches [28][29], we estimate the time for the platelets settling to bottom based on density difference, viscosity of silicone and dimensions of platelet. The result is about 17 hours.…”

Section: Evaluation Of Locally Reinforced Composites Thermal Performancementioning

confidence: 99%

Locally reinforced polymer-based composites for efficient heat dissipation of local heat source

Yuan

Bin

et al. 2016

International Journal of Thermal Sciences

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Local heat source in electronic device is likely to produce hot spot which can degrade the reliability and performance of the device. Various materials have been attempted to enhance the heat dissipation of local heat source. Many theoretical studies have demonstrated that the heterogeneous composite materials with fillers concentrated at the preferential paths of heat flux are effective in cooling the local heat source. However, this unique control of microstructure and property for polymer-based composites has less been achieved in practice due to the technical difficulties in controlling the fillers positions. In this paper, a locally reinforced heterogeneous composite with conductive particles concentrated at the preferential path of heat flux was fabricated to cool the local heat source. The local reinforcement was achieved by using magnetically responsive particles as reinforcing elements and a specific magnetic field to organize the elements into the predefined structure. To evaluate the thermal performance of the proposed material, we performed the comparative thermal tests. The results show that compared to the homogeneous composites, the present composites with local reinforcement can significantly enhance the heat dissipation of local heat source. When heat flux is 5840 W m-2 , the locally reinforced composites with a fillers volume fraction of 5% reduced the average and maximum temperature of heater 7.7 °C and 8.7 °C, respectively.

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Modeling on phosphor sedimentation phenomenon during curing process of high power LED packaging

Cited by 24 publications

References 9 publications

A Cylindrical Tuber Encapsulant Geometry for Enhancing Optical Performance of Chip-on-Board Packaging Light-Emitting Diodes

A Cylindrical Tuber Encapsulant Geometry for Enhancing Optical Performance of Chip-on-Board Packaging Light-Emitting Diodes

Heat and fluid flow in high-power LED packaging and applications

Locally reinforced polymer-based composites for efficient heat dissipation of local heat source

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