Research On Picosecond Laser Stealth Dicing Of LED

The current LED chip cutting mainly is laser cutting,this technology can overcome the property of sapphire’ substrate hardness,difficult to cut.In order to further improve the quality of LED chip cutting,many companies choose to use laser stealth dicing technology to cut LED chips,this dicing method can overcome the laser scribing slag pollution,and the process is simple.However,many researches on stealth dicing are mostly based on invisible cutting and laser scribing.It is difficult to find the internal mechanism of stealth dicing,and how the parameters of laser affect the effect of stealth dicing.So this thesis will analyze theoretically the internal mechanism of stealth cutting,and the influence of special laser parameters on stealth dicing.In this paper,a 1064 nm picosecond laser is used to cutting the LED chip.The main work is:(1)It has been analyzed the future of LED market and development,the developing direction of LED technology,the development process of LED chip dicing technology,as well as the focus of this article,stealth dicing.(2)It has been analyzed the material structure of LED chip,and then the interaction between laser and material based on physical theory,material intermal temperature changeds when LED chip is diced by lase stealth dicing.Finally introduces the characteristics of Gaussian beam.(3)It has been analyzed the laser stealth dicing experimental equipment and the theory of the laser parameters of the factors,including the laser,optical systems,control systems and quality testing devices.In the laser parameters,I mainly introduced the laser power,the focal radius,the pulse width,the repetition frequency and so on theoretically to the cutting effect influence.(4)In view of the above-mentioned theory and problems,experimental study.In the experiment,the influences of the depth of the hidden focal plane,the cutting speed and the power density on the quality of the stealth dicing were studied by using the control variable method.The study shows that when cutting 100 um thick LED chip,the Optimum parameter is that power is 0.8W,the scanning speed is 600mm/s,and the focal plane depth is 40 um.