To obtain white LED, usually using a combination of phosphor and blue LED, which is one of the industry‘s most mature white package, which encapsulates the process materials LED Street Light light failure has no small impact.
1, the impact of the wafer on the white LED light failure
Judging from the results of the current experiment, the impact of bad light wafer is divided into two categories: the first is the wafers of different materials lead to different decay, the most commonly used material for the Blu-ray wafer substrate of silicon carbide and sapphire, silicon carbide general structural design single electrode, its thermal effect is better, sapphire generally designed for dual electrode, is more difficult to export heat, poor thermal effects; second is the size of the wafer, the wafer material is the same, the size of the gap between the different attenuation are also different.
2, the impact of solid crystal glue on the bottom of the white LED light failure
In the white LED packaging industry commonly used in solid crystal glue epoxy insulating plastic, silicone rubber insulation, silver plastic. Three have advantages and disadvantages, to be considered in the selection. Epoxy glue thermal insulation is poor, but the high brightness; silicone rubber thermal insulation effect is slightly better than the epoxy resin, high brightness, but because a certain percentage of silicon components accounted when the residual solid silicone wafers beside fluorescent plastic ring inside will produce the oxygen barrier resin combined with the phenomenon, after peeling lead to thermal shock after death of lights; thermal conductivity than the previous two silver plastic are good, you can prolong the life of the chip led street light, but light silver plastic absorption is relatively large, resulting in low brightness. For dual-electrode blue chips in solid crystal with silver plastic, the amount of glue is also very strict control, or prone to short-circuit a direct impact on the yield of the product.
3, the impact of phosphor white LED light on the decline
Way to achieve a variety of white LED, currently the most widely used one is the most mature by applying a layer of yellow phosphor on blue chips, so blue and yellow mixed into white, so white LED phosphor material attenuation significant influence. Most mainstream market YAG phosphor is yttrium aluminum garnet phosphors, phosphor silicate nitride phosphor, and blue LED chips have accelerated aging compared to white LED phosphor role, and different vendors phosphor light failure is not the same degree of influence, which is closely related to raw ingredients phosphor. Lehman photoelectric finest white phosphor material that made ??the white LED has been greatly improved compared to peers in the attenuation control.
4, the impact of the glue on the white LED light fluorescence decay of
Traditional packaged white LED, fluorescent plastic commonly used epoxy or silicone, after the light fades experimental results obtained with silica powder with white LED life is significantly longer than the epoxy resin. One reason is that with the above two methods packaged into finished LED, silicone anti-UV capability than epoxy and silicone heat better than epoxy; but under the same conditions, with an initial brightness of silica gel with epoxy powder than resin with a powder to be low, the most important is due to the refractive index of silica gel (1.3-1.4) lower than the epoxy resin (1.5 and above), the initial high light efficiency is less than epoxy.
5, the impact of the stent on the white LED light decline
LED stents are mainly copper bracket, aluminum frame and iron bracket. Copper Bracket thermal conductivity, good electrical conductivity, high price. The thermal conductivity of iron brackets, electrical conductivity is relatively poor, more likely to rust, but the price is cheap. Currently used relatively plenty aluminum frame. Stents of different materials affect the performance of led street light is different, especially on light attenuation is particularly prominent.