多材料按需微滴喷射系统设计与实验研究
Design and Experimental Study on Droplet-on-demand Jetting System for Multi-materials

为满足微电子制造、封装领域中不同性质材料按需精确分配的需求，提出了一种由多微滴喷射单元构成的多材料按需微滴喷射系统。该系统的微滴产生模块由用于低黏度流体材料的气动膜片式微滴喷射单元、用于熔融金属流体的压电活塞式微滴喷射单元和用于高黏度流体的机械阀式微滴喷射单元组成。同时由数字相机、模拟相机+图像采集卡构成的图像采集系统，实现液滴沉积的视觉引导对准定位，以及微滴产生过程的图像采集。利用该系统，进行水基混合物、金属焊料和环氧树脂胶的微滴喷射实验，分析了不同黏度对液体微滴喷射过程的影响，实现了金属焊料的微滴喷射，获得了平均直径为70.5 μm的焊球及焊球阵列，其直径偏差小于2%。同时也获得了平均直径为0.6 mm的环氧树脂胶点阵列，其直径偏差小于4%。实验结果表明：该系统可用于包括高黏度环氧树脂胶、金属焊料等在内的多种不同黏度的材料，实现微米级微滴的按需喷射。
To meet the requirement of materials with different properties distribution in microelectronics manufacturing and packaging field, a concept design of multi-dispensing units' droplet on demand jetting system is presented in this paper. In the proposed system, the dispensing module consists of a pneumatic diaphragm droplet generating unit with stainless steel nozzle for low viscosity fluid, a piezoelectric piston droplet generating unit with stainless steel nozzle and stack piezoelectric element actuator for molten metal, a mechanical valve droplet generating unit for high viscosity fluid. At the same time, the image acquisition system with digital camera and analog camera for the visual guiding and droplet producing process image collection is established. With the proposed system, experiments are carried out for the materials of aqueous mixture, molten metal solder and epoxy resin. The paper analyzed the influence of different viscosity on the liquid droplet jetting process, obtained solder ball and ball grid array with an average diameter of 70.5 μm and the diameter deviation is less than 2%, and also obtained epoxy resin droplet and droplet array with average diameter of 0.6 mm and the diameter deviation is less than 4%. The experimental results show that the system can be used for a variety of different viscosity materials including high viscosity of epoxy resin, metal solder according to the need of microelectronics manufacturing process