| With the implementation of the economic policy of energy-saving and the progess of production technology of the light emitting diode(LED), led solid-state lighting has become a trend. How to improve the light efficiency of the leds and extend its service life has become the key problem about how to popularize and apply the leds. The key factors which affect the LED's light efficiency is the packaging materials on top of the chip. The top package materials needs high light transmittance, high refractive index and high resistance to ultraviolet aging. C urrently, the widely used encapsulation structure is the double- layer package structure of silicone resin and polycarbonate on the market. Silicone resin is a kind of soft material, has a poor bonding strengt h, low refractive index, and polycarbonate is a kind of thermoplastic plastics, has a poor UV light resistant ability. All these will influence the life and the optical efficiency of the LEDs.As the packaging material of the LEDs, the cured epoxy resin has a higher bonding strength, higher hardness and the refractive index ratio is more higher than silicone's. This paper adopts epoxy resin as the base material for preparing the packaging material whit a high optical properties. But the refraction of the epoxy resin rate is still not up to high light LEDs' requirements, and its transmission is not high enough and easy to get yellow. Aiming at solving these problems, this paper added surface modified MgO and ZnO nanoparticles into epoxy resin by a certain proportion, to prepare the package material on top of the chip of high-power led, which can not only improve the led the luminous efficiency and also simplify the packaging process by using a single- layer encapsulation.Three kinds of nanocomposite materials were prepared in this experiment, which were nano MgO/ epoxy resin composite, nano ZnO/ epoxy resin composite and nano MgO/ZnO/ epoxy resin composite. The results showed that the transmittance, refractive index and aging resistance of the epoxy resin compo sites were improved by surface treatment, high speed stirring and ultrasonic mixing under the action of nanoparticle of ZnO and MgO :1: Adding nano MgO into epoxy resin can improve the materials' transmittance and refractive index: the transmittance of nanocomposite material is first increased and then decreased whit increases of the mass fraction of nano MgO. When mass fraction of MgO is 0.015%, the transmittance increases from 80.04% of pure epoxy resin to 88.07%; the index of refraction of the material increases with the increase of the mass fraction of nano MgO. When the mass fraction of MgO is 0.05%, the refractive index increased from pure epoxy resin 153.5 to 1.553.2: Adding nano ZnO into the epoxy resin can improve the material' transmittance and refractive index and anti- ultraviolet aging ability: the transmittance of nano-composite material is first increased and then decreased whit increases of the mass fraction of nano ZnO. When the mass fraction of ZnO is 0.04%, the composite's light transmission reached 86.94%. The index of refraction of the material increases with the increase of the mass fraction of nano ZnO. When the mass fraction of ZnO is 0.06%, the composite's index reached 1.572. In addition, adding nano ZnO into epoxy resin can greatly reduce the effect on the light transmittance of the material by the ultraviolet aging.3: Nano MgO/EP composite material and nano ZnO/EP composite material cannot improving epoxy resin's transmittance and refractive index concurrently: adding low mass fraction of nanoparticle can increase the transmittance but the refraction rate is small. When we increase the mass fraction of nanoparticle, the refractive index increased but the transmittance decreased. In order to improve the transmittance, the refractive index and the anti-aging ability at the same time, this experiment added two kinds of nano materials into the epoxy resin: when the ZnO, MgO and epoxy resin mass ratio is ZnO:MgO:EP=4:1:10000, composite's transmittance was 86.64%,the refractive index was 1.565. With respect to the double- layer structure of the silicone resin, the nanocomposite with a mass ratioof ZnO :MgO :EP=4:1:10000led the top of the package of a light angle increases 6.43 degrees; compared to the pure epoxy resin encapsulation structure, the LED top package transmission rate increased by 6.6%, resorted to the light angle improves the 1.1 degrees and the LED has a good stability, improve the service life of the LED.4: Through the surface treatment of nanoparticles, the nanoparticles were dispersed more uniform in epoxy resinwithout agglomeration. The nanoparticle were uniformly dispersed in the epoxy resin whit a diameter of 50 nm. |
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