Fabrication Of Micro-lens Array By Ion Wind And Its Applications In LED Packaging

As a promising candidate for the next generation light source,high-power light-emitting diode(LED)have been widely applied into various illumination applications.The Chip-on Board technology(COB)combines with advantages of chip array packaging technology and Surface Mount Technology(SMT).It has a lot of advantages,such as high integration,small in size,light in weight,low cost,good heat dissipation performance.At present,the luminous efficiency of commercial single chip package LED has reached180~200 lm/W,while the luminous efficiency of COB package LED is only 160~180lm/W,which is far lower than the single chip package LED products and has great potential for improvement.In order to improve the optical performance of COB package LED source,this paper first proposes a fabrication method of micro-lens array by ion wind,and using the micro-lens array in COB package process for improving the optical performance.The COB package LED with the micro-lens array has high luminous efficiency,ideal light intensity distribution.The detailed contents are described as follows:The micro-lens array has been fabricated by ion wind for the COB package,moreover the fabrication principle has been analyzed.This paper first presents a new method of fabricating the micro-lens by ion wind.The voltage between electrodes,the distance between electrodes,the circuit current is the main factor that impact the micro-lens diameter and the gap distance between the lenses.Under the fixed distance between electrodes,the circuit current gets larger with the increase of the voltage between electrodes,while the micro-lens particle diameter decreases.As the thickness of silica gel thin film is60 ?m and the distance between the electrodes is 10.0 mm,the micro-lens diameters are less than 400 ?m,the gap distance between micro-lenses are less than 20 ?m when the voltage reaches 6.0 kV.A new package method is proposed to enhance the light extraction efficiency of COB package LEDs through hemispherical micro-lens array.The experimental results show that compared with the COB package module without micro-lens array,the light extraction efficiency of COB packaging modules with micro-lens array can be enhanced by 6.9%,8.7%,8.2% respectively.According to the different characteristics of micro-lens array structure,the optical model of LED package module with and without micro-lens array has been built.With the micro-lens diameter increasing,the light extraction efficiency of COB decreases gradually.A new package method is proposed to improve the light extraction efficiency of COB package LED through concave micro-lens array by ion wind.The characteristic parameters of concave micro-lens array are decided by the pore size and shape of mesh.Three different mesh sizes concave micro-lens array have been fabricated respectively using 60 mesh,100 mesh,180 mesh wire mesh.Compared with the COB module without micro-lens array,the light extraction efficiency of COB package modules with concave micro-lens array have been increased by 0.9%,4.9%,7.0% respectively.According to the different characteristics of concave micro-lens array structure,the optical model of LED package module with and without concave micro-lens array has been built.With the pore size of concave micro-lens array increasing,the light extraction efficiency of COB package module decreased.