| With the development of LED manufacturing technology,the performance of UV-LEDs is also steadily increasing,replacing traditional mercury lamps as a new generation of ultraviolet light sources.At present,the wavelength of the UV-LEDs gradually develops toward the deep ultraviolet short-wave direction,and the irradiation intensity develops toward the high power direction,which raises a higher demand for the packaging process and reliability of UV-LED.In order to obtain low thermal resistance,high light efficiency and high reliability of ultraviolet light source,this paper starts from the bonding process,combined with simulation and experiment,carries out related research around the enhancement of light extraction efficiency,and uses graphene oxide nanomaterial for reliability packaging.The optimized packaging process is applied to DUV-LED purification source design.The main research contents include1)Optimization of AuSn Eutectic Packaging ProcessBased on the direct AuSn bonding process,low void ratio and low thermal resistance of UV-LED chips can be realized,which can meet the requirements of high reliability packaging The thermal resistance and aging attenuation of samples with different void ratios were analyzed.The relationship among the void ratio of bonding layer,thermal resistance,junction temperature,and lifetime of devices was established.The temperature distribution of bonding layer was simulated by finite element analysis method to verify the experimental results.The results show that,compared with the structure with 30%void ratio,the thermal resistance of the UV-LED with 3%void ratio in the bonding layer can be reduced by 48%.In addition,the quartz window with metal frame was designed and prepared.The quartz window with metal frame and ceramic substrate were sintered and bonded by using silver-copper nano-paste The high reliability UV-LED package was completed,and long-term stability of the structure was studied2)Research on light extraction efficiency(LEE)The main factors affecting the light extraction efficiency of UV-LED were studied.On this basis,a variety of methods to improve the light extraction efficiency of UV-LED were proposed,including the use of high refractive index AIN nanoparticle sealant,nano array lens,and moth-eye structure flexible fluoropolymer film(F2MF).The experimental results show that when 0.4 wt%AIN nanoparticle sealant is used,the light output power of UV-LED increases by 17.4%;Compared with the planar lens structure,the light output power of the DUV-LED packaged by the nano array lens is increased by 24.7%at most,and the maximum increase of the emission angle is about 14°.The light output power of the DUV-LED bonded with F2MF is increased by 26.7%,the TE and TM modes are increased by 20.5%and 21.8%,respectively,and the full mode light extraction efficiency of the AlGaN-based DUV-LED is improved.3)Graphene Oxide Composite MaterialBased on the high thermal conductivity of graphene oxide,graphene oxide silicone was proposed and prepared to meet the requirement of low thermal resistance structure.At the same time,a thermal resistance network model was established to carry out theoretical analysis of heat transfer,and the experimental results were verified by finite element analysis method.The results show that 4 wt%graphene oxide silicone can reduce the interfacial thermal resistance of bonding layer by 30%,and the junction temperature is also reduced by 1.2?.In addition,a new type of graphene oxide fluoropolymer was proposed and prepared,and the relationship between the voidage of the sealing layer and the interacial bonding ability was analyzed through experiments.The results show that graphene oxide fluoropolymer combined with silane coupling agent can realize anchoring structure" at the bonding interface of DUV-LED,enhancing the bonding capability of 425%.It is effectively improve the service life of DUV-LED.4)Design and application verification of DUV-LEDApplying the above packaging technology and sterilization dynamics principle,a DUV-LED light source was designed.The effective ultraviolet irradiation dose and irradiation intensity model of the light source were defined to meet the actual sterilization application effect.For DUV-LED with different emitting angles,different models were set up,and ray-tracing method was used to simulate the radiation intensity distribution of the receiving surface.Meanwhile,the influence of obstructions on the radiation intensity distribution was discussed.Finally,the actual sterilization effect and packaging reliability of proposed light source were verified by simulated biological experiments and high-low temperature impact test... |
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