气动膜片式微滴喷射系统原理与实验

Theoretical and experimental study on pneumatically actuater diaphragm-driven micro-droplet jetting system

利用压电式微滴喷射技术驱动力传递路径短、驱动可控和气压直接驱动微滴喷射耐高温的优点,提出了一种气动膜片式微滴喷射技术.以压缩气体为驱动源,膜片为驱动部件,通过电磁阀通断控制流体形成射流,并使射流颈缩分离形成微滴.以无粘性流体伯努利方程和粘性流体动量守恒方程为基础,建立了微滴喷射过程的数学模型.以气动膜片式微滴喷射装置对焊料进行微滴喷射实验,得到了直径偏差在3%以内的焊球.在喷嘴孔径为80μm和100μm的情况下,分别获得最小直径为85μm和105.3μm的金属焊球.

Aimed at the system＇s working on high temperature for molten metal and other materials, a pneumatically-actuator diaphragm-driven drop-on-demand micro-drop generator was proposed, after the merits of piezoelectric-driven method and pneumatic-driven methods were combined. The apparatus consists of five parts： a throttle, a solder reservoir, a diaphragm, a vent hole and a dispensing nozzle. Derived from Bernoulli＇s equation, when viscous effects are not important, or from the general integral momentum balance, when viscous effects are important, a mathematical model of jetting process was developed also. Using the home-made micro-drop generator, uniform micro droplets with diameter variation less than 3 % was obtained. Ideal micro solder ball of 85 μm and 105.3 μm in diameter were ejected from micro nozzle of 80μm and 100 μm in diameter respectively.