Industry news

2016August

Effect of silica gel and phosphor on LED brightness

From: www.szbako.com Data:31/08/2016


the increasingly serious energy crisis today, energy conservation is imminent, the high efficiency LED much favored by the lamps and lanterns around the factory, how to improve the efficiency of light.


silica gel for each do LED package in a familiar but, the U. S. Dow Corning, Japan's shin Etsu when Premier, I want to most of the packaging manufacturers are inseparable from the two companies of the silica gel, but if the assessment price which is better, it can only be benevolent see benevolence, the wise see wisdom. For the silica LED brightness of refraction depends on the adhesive rate, at present, we are in the LED package process mainly selects the refractive index of silica gel, mainly from chip and silica gel interface considered instead of glue and air refractive index of the chip's rate of about 2, selection of refractive index the silica gel > 1.5, two such material refractive index close to the total reflection angle, light emitted by the chip at the interface of loss is also reduced, light can be effectively derived from the chip, this conclusion can be n1*sinØ from the angle of total reflection formula, =n2*sin90, N2/N1; when the greater total reflection angle is the more that reflects more light, brightness will increase. Within the company recently there have been some problems, oven conditions change, brightness downward, in fact, the explanation and the content similar, can also attributes to the glue of the refraction rate, because the silica gel with increasing temperature, inside the silica gel heat stress led to increased silica refractive index decreases, then light emitted by the chip will have a part is reflected back, it is not difficult to explain why the temperature rise, luminance decreased the

for the fluorescent powder in the LED package is also one of the important part, it is how to affect the LED luminous efficiency? We used the fluorescent powder in more than 1um, refractive index greater than or equal to 1.85, and silica gel refraction rate at about 1.5 due to both refractive index mismatch, and phosphor particles far outweigh the light scattering limit (30 nm) and fluorescent powder surface of light scattering reduces the light efficiency, by nano phosphor doped in silica gel but refractive index increased to more than 1.8, reduce the light scattering, will help to improve the LED luminous efficiency.

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