Phosphor in polycrystalline ceramic structure and a light-emitting element comprising same

A technology of polycrystalline ceramics and light-emitting elements, which is applied in the field of phosphors and can solve problems such as high cost, back scattering, and low thermal conductivity

Active Publication Date: 2008-03-12
LUMILEDS HLDG BV
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  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

However, these fine pores and heterogeneous crystals also cause backscattering
The disadvantage of using YAG:Ce ...

Method used

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  • Phosphor in polycrystalline ceramic structure and a light-emitting element comprising same
  • Phosphor in polycrystalline ceramic structure and a light-emitting element comprising same
  • Phosphor in polycrystalline ceramic structure and a light-emitting element comprising same

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[0054] By deagglomeration of alumina particles (for example by wet ball milling (wet ball milling) or ultrasound, etc.) and stabilization (for example by using HNO 3 or polyacrylic acid), a powder consisting of fine and well-dispersible alumina particles (e.g. Taimei TM-DAR, Sumitomo AKP50) is mixed with a YAG:Ce type powder dispersed in water (e.g. Philios Lighting) . The alumina suspension is cast (for example by slip casting or gel casting) into the mold.

[0055] After drying and removal from the mold, the porous alumina product is calcined in oxygen at a temperature substantially below the sintering temperature to remove all unwanted components such as stabilizers and binders. Next, the material is sintered in a suitable sintering atmosphere (such as vacuum or oxygen atmosphere) until the density is higher than 95%. Hot isostatic pressing is performed after the sintering process to further increase the density without requiring higher sintering temperatures. The result...

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Abstract

The invention relates to a phosphor in a polycrystalline ceramic structure and a light-emitting element provided with the same comprising a Light-Emitting Diode (LED) in which a composite structure of phosphor particles is embedded in a matrix, characterized in that the matrix is a ceramic composite structure comprising a polycrystalline ceramic alumina material, hereafter called luminescent ceramic matrix composite. This luminescent ceramic matrix composite can be made by the steps of converting a powder mixture of ceramic phosphor particles and alumina particles into a slurry, shaping the slurry into a compact, and applying a thermal treatment, optionally in combination with hot isostatic pressing into a polycrystalline phosphor-containing ceramic alumina composite structure. The luminescent ceramic matrix composite further allows a method of tuning the light-diffusing properties by changing at least one of the fractions of phosphor particles and second ceramic particles, the grain size of the particles of the ceramic composite structure, the difference in the refractive index of the particles of the ceramic composite structure, and the porosity in the polycrystalline phosphor-containing ceramic composite structure.

Description

technical field [0001] The present invention relates to a phosphor in a polycrystalline ceramic structure, a light-emitting element including a light-emitting diode provided with the phosphor, a method of manufacturing the phosphor, and a method of adjusting the light-diffusing and luminescent properties of the phosphor. [0002] The phosphors in this polycrystalline ceramic structure form a luminescent ceramic composite. Background technique [0003] The case of state-of-the-art high-brightness white LEDs (Light Emitting Diodes) faces limitations. The phosphor layer deposited on the LED causes light loss by backscattering light into the LED. Backscatter loss is typically 20-30%. Also, heat transfer from the LED and phosphor is a problem for high power applications where the junction and phosphor temperatures get high and the optics (phosphor encapsulant and extraction lens) effectively insulate the LED . Commonly used packaging matrices are made of silicon and / or epoxy,...

Claims

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Application Information

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IPC IPC(8): H05B33/20H01L33/00C09K11/80C04B35/44
Inventor J·德格拉夫T·A·科普
Owner LUMILEDS HLDG BV
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