面向微电子封装的压电驱动按需滴化喷射点胶形成机理与控制

Piezo-actuated drop-on-demand jet dispensing technology is an essential approach to distribute low volume liquid in many processes of microelectronic packaging, such as die attaching, epoxy based encapsulation and underfilling. To meet up the fast development of microelectronic packaging in the last decade and to facilitate producing efficiency, fluid dispensing has show clear trend in its faster speed, smaller dispensing volume and increasing complexity in printing geometry. The objective of the research is to the investigation of the formation of micro-droplets of fluids with any desired volume, velocity and reliability as high as possible. The narrow channel fluid movement mechanism, governing equation, traveling pressure wave principle, nozzle boundary and dynamics of micro-droplet will be explored through the theoretical modeling, VOF/CFS computation and experiment. By developing a novel model of drop-on-demand jet dispensing process, we will show the details of the drop break off, thermal coupling and the nozzle impact on non-Newton fluid properties as viscosity and surface tension, and optimize the geometry of nozzle. The physics behind the jet dispensing processing for electronic packaging comprise multi-coupling from the electrical and mechanical domain through the piezo-actuator, where an electrical signal is transformed into a mechanical movement. As result, the precise piezo-actuated drop-on-demand jet dispensing will be implemented by using novel control methodology.

压电驱动按需滴化喷射点胶是代表微电子封装领域最新发展的点胶技术；本申请拟从理论、计算机仿真和实验上系统研究连续流体在微细孔中运动机理与在喷嘴临界面微液滴形成之间复杂的非线性非平衡态内在本质、临界状态、控制因素、动力学机制和控制模式；通过建立微流体滴化的流体动力学模型、模拟微尺度下非牛顿流体参数变量与热传导物理过程、和进行模型实验，从而优化喷射点胶过程中的关键参数，揭示在微尺度下多参数、多介质热耦合和具有临界面流体滴化特征的动力学过程，为连续流体离散成液滴的可控性提供理论依据；构建基于多动态输入压电驱动器的非线性模型和相应的控制器，实现对不同流变特性点胶液的精密按需滴化喷射点胶控制。

压电驱动按需滴化喷射点胶是代表微电子封装领域最新发展的点胶技术；本项目从理论、计算机仿真和实验上系统研究连续流体在微细孔中运动机理与在喷嘴临界面微液滴形成之间复杂的非线性非平衡态内在本质、临界状态、控制因素、动力学机制和控制模式；本研究基于质量守恒定律和动量守恒定律对粘性不可压缩流体的层流运动建立了控制方程，根据流体体积法建立了自由表面，追踪喷射过程中液体表面在空气中变化并形成液滴的过程，并根据连续表面力法描述气相与液相间的表面张力作用; 通过建立微流体滴化的流体动力学模型、模拟微尺度下非牛顿流体参数变量与热传导物理过程、和进行模型实验，从而优化喷射点胶过程中的关键参数，揭示在微尺度下多参数、多介质热耦合和具有临界面流体滴化特征的动力学过程，为连续流体离散成液滴的可控性提供理论依据；构建基于多动态输入压电驱动器的非线性模型和相应的控制器，实现了喷射频率为100~500HZ和液滴为直径0.150~0.202mm液滴体积的压电驱动喷射，给出了供料压力、流体粘度、喷射频率、驱动电压及喷孔内径等因素对流体喷射和涂覆点质量的影响。