Formation Mechanism and Suppression Strategies of Satellite Droplets for Piezoelectric Jet Dispensing within Short Distance

doi:10.3901/JME.2024.19.347

Abstract

Abstract: Jet dispensing is the core technology in the field of microelectronic packaging.The problems including substrate pollution, irregular shape of glue spots, etc., will be caused by the satellite droplets generating in jet breakup, which is a serious problem for the dispensing technology.The distance between nozzle and substrate is very short (0.7-1.2 mm) during piezoelectric driven dispensing, and jet breakup usually occurs after the droplet contact with the substrate.The process of jet breakup is complex, and the mechanism of satellites formation is still unclear.Numerical and experimental analysis for the dispensing of epoxy glue within short distance is implemented aiming to explore the mechanism of satellites formation, and the strategies to suppress satellites are presented.The results show that the formation modes of satellites can be classified into three types: the second breakup occurs under the satellite droplets, two breakups occur simultaneously at different positions, the second breakup occurs above the satellite droplets, and the third mode is worst, for which the satellites will become scattered spots.There is a negative relation between generation rate of satellite droplets and jet breakup time.The generation rate of satellites can be reduced by raising breakup time through decreasing the jet velocity, shortening the distance between nozzle and substrate, and reducing the temperature.In addition，the jet velocity can be decreased by increasing the angle of nozzle and the ratio of length to diameter of nozzle, or designing steps in the nozzle.

Key words: jet dispensing, satellite droplets, numerical analysis, jet crushing time, aspect ratio

CLC Number:

TH16
TP301

LI Yadong, TAO Yourui, WANG Chongshuai, DUAN Shuyong, LI Changfeng, JI Zhaoxin. Formation Mechanism and Suppression Strategies of Satellite Droplets for Piezoelectric Jet Dispensing within Short Distance[J]. Journal of Mechanical Engineering, 2024, 60(19): 347-355.

References

[1] ZHOU C，CHEN W，BAO Z，et al. A precision temperature control approach for piezoelectric jet dispenser[J]. Optik，2019，183：273-276.
[2] JEON J，HONG S M，CHOI M，et al. Design and performance evaluation of a new jetting dispenser system using two piezostack actuators[J]. Smart Materials and Structures，2014，24(1)：015020.
[3] 姚玉峰，路士州，刘亚欣，等. 微量液体自动分配技术研究综述[J]. 机械工程学报，2013，49(14): 140-153. YAO Yufeng，LU Shizhou，LIU Yaxin，et al. Research on automated micro-liquid dispensing technology[J]. Journal of Mechanical Engineering，2013，49(14)：140-153.
[4] LI H，LIU J，LI K，et al. Piezoelectric micro-jet devices: A review[J]. Sensors and Actuators A: Physical，2019，297： 111552.
[5] BU Z，LIN S，HUANG X，et al. A novel piezostack-driven jetting dispenser with corner-filleted flexure hinge and high-frequency performance[J]. Journal of Micromechanics and Microengineering，2018，28(7)： 075001.
[6] TSAI H L，HWANG W S，WANG J K，et al. Fabrication of microdots using piezoelectric dispensing technique for viscous fluids[J]. Materials，2015，8(10)： 7006-7016.
[7] 周诗贵，习俊通. 压电驱动膜片式微滴喷射仿真与尺度一致性试验研究[J]. 机械工程学报，2013，49(8)：178-185. ZHOU Shigui，XI Juntong. Simulation and experiment study on piezoelectric actuated diaphragm-driven microdroplet jetting[J]. Journal of Mechanical Engineering. 2013，49(8)：178-185.
[8] 陈恒，杨俊逸，张志航，等. 气动喷射阀点胶质量改善研究[J]. 现代制造工程，2018(5)：102-107. CHEN Heng，YANG Junyi，ZHANG Zhihang，et al. Research on improvement of dispensing quality of pneumatic jetting valve[J]. Modern Manufacturing Engineering，2018(5)：102-107.
[9] LU S，JIANG H，LI M，et al. Nozzle and needle during high viscosity adhesive jetting based on piezoelectric jet dispensing[J]. Smart Materials and Structures，2015，24(10)：105023.
[10] WANG T，LIN J，LEI Y，et al. Droplets generator: Formation and control of main and satellite droplets[J]. Colloids and Surfaces A：Physicochemical and Engineering Aspects，2018，558：303-312.
[11] ZHONG Y，FANG H，MA Q，et al. Analysis of droplet stability after ejection from an inkjet nozzle[J]. Journal of Fluid Mechanics，2018，845：378-391.
[12] SUN C，CHU X，YAN S，et al. Influence of input signal on injection performance for needle driven piezoelectric micro-jet device[J]. Microsystem Technologies，2021，27(5)：2009-2019.
[13] YANG Y，GU S，LV Q，et al. Influence of needle impact velocity on the jetting effect of a piezoelectric needle-collision jetting dispenser[J]. AIP Advances，2019，9(4)：045302.
[14] LU S，CHEN X，ZHENG H，et al. Simulation and experiment on droplet volume for the needle-type piezoelectric jetting dispenser[J]. Micromachines，2019，10(9)：623.
[15] LU S，ZHANG J，LIU Y，et al. Droplet formation study of a liquid micro-dispenser driven by a piezoelectric actuator[J]. Smart Materials and Structures，2019，28(5)： 055003.
[16] SHU X Y，ZHANG H H，LIU H Y，et al. Experimental study on high viscosity fluid micro-droplet jetting system[J]. Science in China Series E: Technological Sciences，2010，53：182-187.
[17] 占红武，胥芳，郭维锋，等. 压电喷墨过程动力学建模与供墨方法[J]. 机械工程学报，2017，53(1)：140-149. ZHAN Hongwu，XU Fang，GUO Weifeng，et al. Dynamics modeling and ink supply methods of piezoelectric ink-jetting process[J]. Journal of Mechanical Engineering，2017，53(1)：140-149.
[18] LU S，YAO Y，LIU Y，et al. Design and experiment of a needle-type piezostack-driven jetting dispenser based on lumped parameter method[J]. Journal of Adhesion Science and Technology，2015，29(8)：716-730.
[19] 刘赵淼，钟希祥，杨刚，等. 气动式微滴喷射中液滴稳定生成的动力学特性研究[J]. 机械工程学报，2021，56(23)：203-211. LIU Zhaomiao，ZHONG Xixiang，YANG Gang，et al. Study on the kinetic characteristics of droplet formation in pneumatic microdroplet injection[J]. Journal of Mechanical Engineering，2020，56(23)：203-211.
[20] MCKINLEY G H，SRIDHAR T. Filament-stretching rheometry of complex fluids[J]. Annual Review of Fluid Mechanics，2002，34(1)：375-415.
[21] 路崧. 压电驱动非接触喷射点胶阀的设计理论与试验研究[D]. 长春：吉林大学，2016. Lu Song. Mechanism and experimental research on the non-contact jet dispensing valve driven by piezoelectric actuator[D]. Changchun：Jilin University，2016.
[22] MCKINLEY G H. Visco-elasto-capillary thinning and break-up of complex fluids[J]. Annual Rheology Reviews，2005，1：1-48.
[23] JIAO T，LIAN Q，ZHAO T，et al. Influence of ink properties and voltage parameters on piezoelectric inkjet droplet formation[J]. Applied Physics A，2021，127：1-9.
[24] ZHAO Y，LONG Y，WANG Q，et al. Simulation and experiment on droplet dispensing for a valve-controlled pneumatic jetting system[J]. Journal of Adhesion Science and Technology，2021，35(11)：1185-1202.
[25] LIU Y F，TSAI M H，PAI Y F，et al. Control of droplet formation by operating waveform for inks with various viscosities in piezoelectric inkjet printing[J]. Applied Physics A，2013，111：509-516.