title: Ultrasound aided smooth dispensing for high viscoelastic epoxy in microelectronic packaging.
abstract: Epoxy dispensing is one of the most critical processes in microelectronic packaging. However, due its high viscoelasticity, dispensing of epoxy is extremely difficult, and a lower viscoelasticity epoxy is desired to improve the process. In this paper, a novel method is proposed to achieve a lowered viscoelastic epoxy by using ultrasound. The viscoelasticity and molecular structures of the epoxies were compared and analyzed before and after experimentation. Different factors of the ultrasonic process, including power, processing time and ultrasonic energy, were studied in this study. It is found that elasticity is more sensitive to ultrasonic processing while viscosity is little affected. Further, large power and long processing time can minimize the viscoelasticity to ideal values. Due to the reduced loss modulus and storage modulus after ultrasonic processing, smooth dispensing is demonstrated for the processed epoxy. The subsequently color temperature experiments show that ultrasonic processing will not affect LED's lighting. It is clear that the ultrasonic processing will have good potential to aide smooth dispensing for high viscoelastic epoxy in electronic industry.
authors.affiliation: The Key Laboratory of Mechanical Equipment Manufacturing & Control Technology, School of Electromechanical Engineering, Guangdong University of Technology, Guangzhou 510006, China. Electronic address: chen.lojade@gmail.com.
authors.forename: Yun
authors.initials: Y
authors.lastname: Chen
authors.affiliation: School of Mechanical and Electrical Engineering, Central South University, State Key Laboratory of High Performance Complex Manufacturing, Changsha 410083, China; Department of Systems Engineering and Engineering Management, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong, China.
authors.forename: Han-Xiong
authors.initials: HX
authors.lastname: Li
authors.affiliation: School of Mechanical and Electrical Engineering, Central South University, State Key Laboratory of High Performance Complex Manufacturing, Changsha 410083, China.
authors.forename: Xiuyang
authors.initials: X
authors.lastname: Shan
authors.affiliation: The Key Laboratory of Mechanical Equipment Manufacturing & Control Technology, School of Electromechanical Engineering, Guangdong University of Technology, Guangzhou 510006, China.
authors.forename: Jian
authors.initials: J
authors.lastname: Gao
authors.affiliation: The Key Laboratory of Mechanical Equipment Manufacturing & Control Technology, School of Electromechanical Engineering, Guangdong University of Technology, Guangzhou 510006, China.
authors.forename: Xin
authors.initials: X
authors.lastname: Chen
authors.affiliation: School of Mechanical and Electrical Engineering, Central South University, State Key Laboratory of High Performance Complex Manufacturing, Changsha 410083, China.
authors.forename: Fuliang
authors.initials: F
authors.lastname: Wang
keywords: Epoxy; Fluid dispensing; Lowering viscoelasticity; Ultrasonic processing