As an accurate 2D/3D fabrication tool,inkjet printing technology has great potential in preparation of micro electronic devices.The morphology of droplets produced by the inkjet printer has a great impact on the accur...As an accurate 2D/3D fabrication tool,inkjet printing technology has great potential in preparation of micro electronic devices.The morphology of droplets produced by the inkjet printer has a great impact on the accuracy of deposition.In this study,the drop-on-demand(DoD)inkjet simulation model was established,and the accuracy of the simulation model was verified by corresponding experiments.The simulation result shows that the velocity of the droplet front and tail,as well as the time to disconnect from the nozzle is mainly affected by density(ρ),viscosity(μ)and surface tension(σ)of droplets.When the liquid filament is about to disconnect from the nozzle,the filament length and filament front velocity are found to have a linear correlation withσ/ρμand ln(ρ/(μσ1/2)).展开更多
The droplet formation dynamics of a Newtonian liquid in a drop-on-demand (DOD) inkjet process is numerically investigated by using a volume-of-fluid (VOF) method. We focus on the nozzle geometry, wettability of the in...The droplet formation dynamics of a Newtonian liquid in a drop-on-demand (DOD) inkjet process is numerically investigated by using a volume-of-fluid (VOF) method. We focus on the nozzle geometry, wettability of the interior surface, and the fluid properties to achieve the stable droplet formation with higher velocity. It is found that a nozzle with contracting angle of 45° generates the most stable and fastest single droplet, which is beneficial for the enhanced printing quality and high-throughput printing rate. For this nozzle with the optimal geometry, we systematically change the wettability of the interior surface, i.e., different contact angles. As the contact angle increases, pinch-off time increases and the droplet speed reduces. Finally, fluids with different properties are investigated to identify the printability range.展开更多
Inkjet printing has emerged as a potential solution processing method for large-area patterned films.During inkjet printing,a single droplet without satellite droplet is required for high-quality film.Herein,we propos...Inkjet printing has emerged as a potential solution processing method for large-area patterned films.During inkjet printing,a single droplet without satellite droplet is required for high-quality film.Herein,we propose a strategy for obtaining a single droplet by adjusting the reduced concentration(c/c^(*),where c^(*)is the critical overlap concentration)in the range of 1.0-1.5.Droplet formation can be categorized into three distinct regimes:(1)c/c^(*)<1.0,satellite droplet;(2)c/c^(*)=1.0-1.5,single droplet;(3)c/c^(*)>2.0,no droplet.Furthermore,an inertial-capillary balance led to the 2/3-power scaling of the minimum radius with time for the solutions of c/c^(*)<1.0.However,for the solutions of c/c^(*)=1.0-1.5,the ligament radius decreased exponentially with time.Moreover,the Weissenberg number was higher than the critical value of 0.5,indicating that the polymer chains underwent coil-stretch transition.The viscoelastic-capillary balance dominated instead of the inertial-capillary balance.The resulting viscoelastic resistance reduced the length of the ligament and increased the velocity difference between the satellite and main droplets.Consequently,a single droplet was formed.In addition,the law can be successfully generalized to various molecular weights,molecular structures and solvents.展开更多
目的设计一种打印规则,在喷墨技术作为一种高效的生产工具被用于先进制造时提高其喷墨打印精度。方法通过墨滴观测系统分析喷点火频率对喷射状态的影响;分析串扰对喷嘴间的影响,获得高频连续喷射参数,并用高精度打印平台对不同模式进行...目的设计一种打印规则,在喷墨技术作为一种高效的生产工具被用于先进制造时提高其喷墨打印精度。方法通过墨滴观测系统分析喷点火频率对喷射状态的影响;分析串扰对喷嘴间的影响,获得高频连续喷射参数,并用高精度打印平台对不同模式进行测试。表征方法包括传统的图像质量分析方法以及喷墨制造获得的导电网格的导电性能对比。结果使用提出的打印规则,喷墨点火频率达到78 k Hz,打印样张网点面积率误差小于1%,竖线粗糙度方差约等于3μm2。宏观和微观的视觉效果得到提升,打印制作的柔性触摸屏网格线条均匀线宽约65μm,导电性良好。结论优化后的打印规则可以弱化残余振动和串扰对其他喷嘴的影响,在提升打印效率的同时提高打印精度和点火频率,有效地促进压电喷头在喷墨制造领域的应用。展开更多
目的研究喷墨过程中流体物性参数对喷墨质量的影响。方法采用数值模拟方法,基于流体体积法建立仿真模型,以不同粘度和表面张力的流体为研究对象,通过分析墨滴形成及铺展过程的形态变化,探索流体的物性参数(粘度、表面张力)对于墨滴成形...目的研究喷墨过程中流体物性参数对喷墨质量的影响。方法采用数值模拟方法,基于流体体积法建立仿真模型,以不同粘度和表面张力的流体为研究对象,通过分析墨滴形成及铺展过程的形态变化,探索流体的物性参数(粘度、表面张力)对于墨滴成形过程的影响,得出高质量喷墨印刷的流体物性参数范围,并在柔性基底上印刷UHF(超高频)天线来验证模拟结果的可靠性。结果使用无量纲常数Z表征流体的可喷印性能,数值模拟结果表明表面张力为40 m N/m,粘度为10 Pa·s的墨水能达到良好的喷印状态。结论通过实验观测墨水的喷射过程,与模拟结果对比具有较高的重合度,数值模拟结果可以较准确地预测墨水印刷质量,经测量可知印制天线满足使用要求。展开更多
基金supported by the Tsinghua University–Toyota Research Center Project。
文摘As an accurate 2D/3D fabrication tool,inkjet printing technology has great potential in preparation of micro electronic devices.The morphology of droplets produced by the inkjet printer has a great impact on the accuracy of deposition.In this study,the drop-on-demand(DoD)inkjet simulation model was established,and the accuracy of the simulation model was verified by corresponding experiments.The simulation result shows that the velocity of the droplet front and tail,as well as the time to disconnect from the nozzle is mainly affected by density(ρ),viscosity(μ)and surface tension(σ)of droplets.When the liquid filament is about to disconnect from the nozzle,the filament length and filament front velocity are found to have a linear correlation withσ/ρμand ln(ρ/(μσ1/2)).
基金Project supported by the National Natural Science Foundation of China(No.11802004)
文摘The droplet formation dynamics of a Newtonian liquid in a drop-on-demand (DOD) inkjet process is numerically investigated by using a volume-of-fluid (VOF) method. We focus on the nozzle geometry, wettability of the interior surface, and the fluid properties to achieve the stable droplet formation with higher velocity. It is found that a nozzle with contracting angle of 45° generates the most stable and fastest single droplet, which is beneficial for the enhanced printing quality and high-throughput printing rate. For this nozzle with the optimal geometry, we systematically change the wettability of the interior surface, i.e., different contact angles. As the contact angle increases, pinch-off time increases and the droplet speed reduces. Finally, fluids with different properties are investigated to identify the printability range.
基金financially supported by the National Natural Science Foundation of China(No.51873212)the CAS-Croucher Funding Scheme for Joint Laboratories:Poly U-CIAC Joint Laboratory(No.121522KYSB20200040)。
文摘Inkjet printing has emerged as a potential solution processing method for large-area patterned films.During inkjet printing,a single droplet without satellite droplet is required for high-quality film.Herein,we propose a strategy for obtaining a single droplet by adjusting the reduced concentration(c/c^(*),where c^(*)is the critical overlap concentration)in the range of 1.0-1.5.Droplet formation can be categorized into three distinct regimes:(1)c/c^(*)<1.0,satellite droplet;(2)c/c^(*)=1.0-1.5,single droplet;(3)c/c^(*)>2.0,no droplet.Furthermore,an inertial-capillary balance led to the 2/3-power scaling of the minimum radius with time for the solutions of c/c^(*)<1.0.However,for the solutions of c/c^(*)=1.0-1.5,the ligament radius decreased exponentially with time.Moreover,the Weissenberg number was higher than the critical value of 0.5,indicating that the polymer chains underwent coil-stretch transition.The viscoelastic-capillary balance dominated instead of the inertial-capillary balance.The resulting viscoelastic resistance reduced the length of the ligament and increased the velocity difference between the satellite and main droplets.Consequently,a single droplet was formed.In addition,the law can be successfully generalized to various molecular weights,molecular structures and solvents.
文摘目的设计一种打印规则,在喷墨技术作为一种高效的生产工具被用于先进制造时提高其喷墨打印精度。方法通过墨滴观测系统分析喷点火频率对喷射状态的影响;分析串扰对喷嘴间的影响,获得高频连续喷射参数,并用高精度打印平台对不同模式进行测试。表征方法包括传统的图像质量分析方法以及喷墨制造获得的导电网格的导电性能对比。结果使用提出的打印规则,喷墨点火频率达到78 k Hz,打印样张网点面积率误差小于1%,竖线粗糙度方差约等于3μm2。宏观和微观的视觉效果得到提升,打印制作的柔性触摸屏网格线条均匀线宽约65μm,导电性良好。结论优化后的打印规则可以弱化残余振动和串扰对其他喷嘴的影响,在提升打印效率的同时提高打印精度和点火频率,有效地促进压电喷头在喷墨制造领域的应用。
文摘目的研究喷墨过程中流体物性参数对喷墨质量的影响。方法采用数值模拟方法,基于流体体积法建立仿真模型,以不同粘度和表面张力的流体为研究对象,通过分析墨滴形成及铺展过程的形态变化,探索流体的物性参数(粘度、表面张力)对于墨滴成形过程的影响,得出高质量喷墨印刷的流体物性参数范围,并在柔性基底上印刷UHF(超高频)天线来验证模拟结果的可靠性。结果使用无量纲常数Z表征流体的可喷印性能,数值模拟结果表明表面张力为40 m N/m,粘度为10 Pa·s的墨水能达到良好的喷印状态。结论通过实验观测墨水的喷射过程,与模拟结果对比具有较高的重合度,数值模拟结果可以较准确地预测墨水印刷质量,经测量可知印制天线满足使用要求。
