Active packing method for blue light-emitting diodes with photosensitive polymerization: formation of self-focusing encapsulates

Wang, Hao; Ryu, Jae-Hyoung; Lee, Kyu-Seung; Tan, Chunhua; Jin, Lihua; Li, Songmei; Hong, Chang–Hee; Cho, Yong-Hoon; Liu, Songhao

doi:10.1364/oe.16.003680

Cited by 8 publications

(6 citation statements)

References 8 publications

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“…Low temperature and non-thermal curing reduces the thermal effects on materials and thereby improves the initial performance of LEDs. Photosensitive silicones can even realize the fabrication of self-focused lens without molds [111,112], which could reduce charges for the latter.…”

Section: Prospectmentioning

confidence: 99%

Status and prospects for phosphor-based white LED packaging

Liu

Wang

et al. 2009

Front. Optoelectron. China

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The status and prospects for high-power, phosphor-based white light-emitting diode (LED) packaging have been presented. A system view for packaging design is proposed to address packaging issues. Four aspects of packaging are reviewed: optical control, thermal management, reliability and cost. Phosphor materials play the most important role in light extraction and color control. The conformal coating method improves the spatial color distribution (SCD) of LEDs. High refractive index (RI) encapsulants with high transmittance and modified surface morphology can enhance light extraction. Multi-phosphor-based packaging can realize the control of correlated color temperature (CCT) with high color rendering index (CRI). Effective thermal management can dissipate heat rapidly and reduce thermal stress caused by the mismatch of the coefficient of thermal expansion (CTE). Chip-on-board (CoB) technology with a multilayer ceramic substrate is the most promising method for high-power LED packaging. Low junction temperature will improve the reliability and provide longer life. Advanced processes, precise fabrication and careful operation are essential for high reliability LEDs. Cost is one of the biggest obstacles for the penetration of white LEDs into the market for general illumination products. Mass production in terms of CoB, system in packaging (SiP), 3D packaging and wafer level packaging (WLP) can reduce the cost significantly, especially when chip cost is lowered by using a large wafer size.

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Section: Prospectmentioning

confidence: 99%

Status and prospects for phosphor-based white LED packaging

Liu

Wang

et al. 2009

Front. Optoelectron. China

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“…However, there is an active packaging method, which utilizes the light emitted from the LED chip itself to package the LED using a photosensitive epoxy, and it eliminates the need to utilize a mold. 1 The typical encapsulant shape obtained with this method is a mushroom-shaped, and the complete emission angles of the output light ranged from 132 • to 82 • . Both encapsulant shape and emission angles depend on the polymerization time, the current supplied to the LED chip, and its beam profile.…”

Section: Introductionmentioning

confidence: 98%

Caustic produced by refractive conic surfaces

López-Bautista

Avendaño‐Alejo

Ponce-Hernández

et al. 2022

Current Developments in Lens Design and Optical Engineering XXIII

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We study the formation of caustic produced by refraction through conic surfaces, considering a point source placed along the optical axis at arbitrary distances from the vertex of refracting surface. We demand that the optical surface is represented by a mathematical function, which is smooth, continuous, and derivable. We implement an exact ray trace to obtain a monoparametric equation that describes a family of refracted rays, which are propagated as a function of the angle of emission from the point source for each ray. Subsequently, by using the envelope's method, we provide an analytical equation for the caustic surface as a function of all the parameters involved in the process of refraction. We analyze the paraxial approximation assuming a very small angle about the axis of the system. Additionally, we provide a formula, which describes the conditions for total internal reflection. Finally, we present the formation of caustic surfaces by considering a liquid polymer in a rotating vessel forming a paraboloid surface, also we present the caustic surface produced by the package of a Light Emitting Diode, to produce an uniform illumination pattern.

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“…The photoinitiated polymerization provides advantageous means over the thermally initiated polymerization, owing to the fast and controllable reaction rates and the fact that high temperatures or pH conditions are not needed, thereby attracting extensive attention in various research disciplines and industrial sectors, such as packaging of LEDs [10] and MEMS devices [11], application of printing inks [12], and fabrication of photonic crystal structures [6] and microvascular networks [14]. In order to reduce the cost of LED fabrication, a novel LED packaging method, i.e., the active packaging (AP) method, has been presented [17]. This method utilizes the light emitted from the LED chip itself to package the LED with a photosensitive epoxy resin.…”

Section: Introductionmentioning

confidence: 99%

“…The encapsulation shape by photoinitiated polymerization (e.g., AP method) can be changed by using specific parameters in the polymerization reaction (e.g., LED power, polymerization time, absorptivity of the epoxy and photolysis, etc.). Some researches [17] conducted experiments with different parameters such as polymerization time and injection current, to demonstrate the geometries of the LED encapsulants by the AP method, but there is still not a solid mathematical model to predict and depict the size and shape of the encapsulant lens by the AP method. In this paper, we present a mathematical model to describe the LED radiation pattern and provide a numerical simulation process to analyze the kinetics of the photoinitiated polymerization system for the AP method.…”

Section: Introductionmentioning

confidence: 99%

Photoinitiated Polymerization for Active Packaging of Light-Emitting Diodes

Chin

Tseng

et al. 2013

IEEE Photonics J.

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The kinetics of photoinitiated polymerization for active packaging of light-emitting diodes (LEDs) is presented. The LED chip in our model was considered to consist of an upper emission surface and a lateral emission surface. Light emission from the LED chip triggers the photoinitiated polymerization reaction, leading to the formation of a mushroomshaped encapsulant lens on the LED chip. With our proposed simulation process, the concentrations of both the photoinitiator and monomer, and the photolysis as time evolves can be calculated by the finite-difference method. The time evolution of the lens profile during polymerization can be analyzed as the monomer concentration varies. The proposed technique can depict the shape and precise size of the mushroom-shaped lens for any specific parameters in the polymerization reaction, e.g., LED power, polymerization time, absorptivity of the epoxy, and photolysis. LED encapsulation experiments with different LED power and polymerization time were made to support our simulation results, and the simulation results agree well with the experiment results. Finally, the radiation patterns of the LEDs with the encapsulant lenses are measured to prove the light focusing characteristics of the mushroom-shaped lenses.

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Active packing method for blue light-emitting diodes with photosensitive polymerization: formation of self-focusing encapsulates

Cited by 8 publications

References 8 publications

Status and prospects for phosphor-based white LED packaging

Status and prospects for phosphor-based white LED packaging

Caustic produced by refractive conic surfaces

Photoinitiated Polymerization for Active Packaging of Light-Emitting Diodes

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