基于撞针原理的高粘性微喷系统的设计与分析

为了实现对高粘性微量液滴的高效率喷射,研制了一种基于撞针原理的非接触式微喷装置。采用压电陶瓷作为驱动装置,再利用菱形放大机构进行微位移放大,采用有限元软件对菱形放大机构进行静、动态特性分析,确定喷针和喷嘴的配合形式及相关尺寸,然后利用MATLAB软件进行动力学方程的求解,仿真结果显示,喷针的位移和速度均满足喷射条件,最后针对5～10Pa.s粘度的液体进行了微喷实验。实验结果表明:该微喷装置可稳定地实现胶液的喷射,输出流量随着驱动电压的增大而增大。     

高性能LED封装点胶中流体运动与胶液喷射研究

LED照明具有高亮度、低能耗、体积小、环保等特点,因此被认为是未来替代传统照明方式的最佳光源。而对于高粘度、高频、微量、高一致性的LED荧光粉点胶,目前还存在无法出胶、点胶性能不稳定、胶滴一致性不好等问题。首先阐述了LED照明的应用特点以及当前照明封装产业的技术水平,随后结合将来主流的喷射式点胶技术,利用Flow-3D软件建立了LED喷射点胶过程的计算机仿真模型。随后得到了点胶过程中胶液在喷胶阀内的流动情况,在此基础上又探讨了各因素对胶液喷射的影响规律。其结果可以为后续的研究奠定基础,同时对具体的LED工业生产及封装装备制造也有一定的参考价值。     

喷射布胶胶液累积体积及其平均流速数值模拟

从喷射器出口端积聚的胶液体积及其平均流速,对胶滴形成及其特性具有重要的影响.喷射器出口胶液的流量是时刻变化的,导致在喷嘴出口端积聚的胶液体积及其平均流速不断变化.分别建立了牛顿流体和非牛顿流体胶液累积体积及其平均流速的离散化计算公式,结合ANSYS仿真得到的喷嘴出口处中心速度,通过MATLAB程序计算了喷射器一定参数条件下喷出胶液的累积体积及其平均流速.     

点胶工艺的新进展

喷射点胶是一种通过动量使胶水快速从喷嘴中喷出的点胶工艺.Nordson ASYMTEK公司在1993年推出喷射技术,从此喷射点胶工艺开始在电子制造业被广泛使用.这是一个革命性的概念,因为在此之前点胶工艺只能通过针头点胶来完成,在针头点胶的过程中z轴需要上下运动,而喷射点胶工艺则是通过由喷头每次喷射出一定量的胶体来实现点胶.由于不再需要针头点胶中用于克服胶水附着实现点胶的z轴运动,喷射技术大幅度提高了点胶速度.     

电子组装喷射点胶过程流体特性CFD模拟分析

喷射点胶技术是电子组装的核心技术,针对如何喷射小直径胶点以满足微电子封装要求这一问题。文中基于气压驱动点胶阀的工作原理,建立顶针和喷嘴碰撞结构二维几何模型,采用CFD计算机流体动力学分析软件对点胶过程中喷嘴口胶水喷射速度、密闭内腔胶水液压进行仿真模拟分析。数值仿真结果表明,顶针几何外形、顶针运动行程及喷嘴张角是影响胶水喷射速度的主要因素,喷射胶点的直径大小是由这些影响因素决定的。     

TSD6441BF高精度、高速喷射式点胶机

＊小至300UM的紧凑空问内喷射,是接触式无达到达的区域;＊最大流量300G／min,胶点最小直径0．3mm术微量控制,每次最小定量出胶量2nl;＊清洗方便,尤需专业工具：＊没有针头耗材,维护简单;＊搭配设备点胶时无Z轴运动,大幅度提高牛产效率术＊接触产品表面。     

车载应用中的电流检测

车载应用中的电流检测包括控制通过螺线管和喷射器的电流.例如,在柴油喷射时,我们用48V或更高的电压迅速地将感应喷射器的电流提高到20安培.一旦达到20A,电流检测电路就会向控制电路提供反馈信号,以保持喷射器电流为20A不变.     

Essemtec推出带两个喷射点胶系统的CDS6200

SMT生产机器制造商Essemtec推出带两个喷射点胶机的CDS6200。喷射滴胶技术可在多点按比例喷射大量介质。由于待点胶材料具备多种特有特征（部分取决于环境条件），选择适用于特定材料的阀门十分必要。CDS6200具备两个喷射点胶机，可提供实现以上目标的技术。     

基于PZT厚膜驱动的微喷芯片的设计

设计了一种基于双压电薄膜驱动的微喷芯片,该芯片中每个流体单元结构主要是由进样室、微管道、喷口以及集成了PZT驱动器的主副贮液室组成,其中主驱动器提供喷射液体的驱动力,副驱动器抑制液体回流;采用计算流体力学模拟(CFD-simulation)对其进行了结构设计、进样模拟和喷样模拟,结果表明,液体能成功进样及喷样。同时当微管道尺寸小于40μm时,喷样过程中微管道内将不再产生回流,证明双PZT驱动器的芯片设计合理,为该芯片的制作打下基础。     

Nordson ASYMTEK推出新一代喷射点胶技术-NexJet^TM

Nordson ASYMTEK公司，一家全球领先的点胶、涂装和喷射技术供应商，日前宣布推出新的NEXJetTM点胶系统并准备申请专利，这标志着现行的喷射技术又向前迈进了一大步。位于系统中心的是Genius^TM喷射模组，这是一种新型的一体化组件，无需使用任何工具，     

超声行波微流体驱动模型的耦合分析

介绍了带有微沟道的超声行波微流体驱动的圆环模型。在对模型结构部分进行模态分析和瞬态动力学分析的基础上,基于有限元分析,针对耦合模型作声固耦合分析,分别得到与空气和水耦合时模型的固有频率;进行耦合场的流固耦合分析,采用瞬态动力学方法,得到沟道内流体在超声行波激励下的流场情况。比较不同时间子步时流体域和固体域的位移云图,得到流体随固体振动情况;分析不同时间子步时流体域的速度矢量图,得到流体在超声行波方向上的流动情况,验证了超声行波微流体驱动的可行性。     

Versatile methodology for generating size-controlled composite micrometer beads capsulating nanomaterials

Our developmental investigations into aerodynamically assisted jetting have previously shown great promise (Jayasinghe and Suter in Micro and Nano Letts., 2006, 1, 35) in materials science and engineering. This processing approach is currently undergoing rapid development where it will join other related jet-based processes such as ink-jet printing and electrospraying with which the precision deposition of droplet residues (containing a wide variety of micro-and nanomaterials) is most useful in micro-and nanosciences. The ability for capsulating nanomaterials (having a mean particulate size of 5 nm) as micrometer-sized composite beads is demonstrated. Investigations reported here show the influence of the applied aerodynamic forces to the chamber or flow rate to the needle, respectively, having effect on the generated composite bead sizes, their distributions and on the jetting characteristics. These investigations imply the versatility of this processing science for capsulating a wide variety of nano-sized materials as composite beads for applications ranging from the formation of stable emulsions to a route for controlled delivery of drugs, which would be most useful to the pharmaceutical industry.     

Utilizing inkjet printing to fabricate electrical interconnections in a system-in-package

The printed interconnections for encapsulated electronic packages using nanoparticle metal inks and polymer dielectrics have been demonstrated. The printing has utilized a digital printing method, inkjet printing. The printing process has been adopted rather well, but process yield improvement required more attention to the control of individual manufacturing stages and error sources. The sources for possible errors can be roughly divided into separate groups: the substrate-ink interaction and treatment procedure related, ink jetting related, and moving stage related. In this paper, the individual stages were taken under consideration. The process performance was studied using statistical methods. The affecting factors were classified, and designed experiments were carried out to determine the most significant factors and to create a model to describe the behavior. According to the models, optimized process parameters were achieved, and implemented in practice.     

压电式喷射点胶控制系统的电路设计

基于新型压电式点胶头采用的双压电陶瓷的推挽驱动作为胶体喷射的作用机制,设计并搭建了压电式喷射点胶控制系统,完成了硬件与软件模块的组装调试,实现对下压电陶瓷信号的频率、占空比、幅值、上压电陶瓷信号幅值的连续可调,具备人机交互、清洗、喷射点数可调等功能。经测试,系统各参数达到预定指标,频率显示误差:±1.2 Hz;占空比显示误差:±1%;幅值显示误差:±8 mV。在驱动方波电压200 V、频率65 Hz、占空比20%、喷嘴直径250μm、供料压力4 bar、喷射高度3.5 mm的条件下,得到平均直径为1.07 mm左右的喷射胶滴,一致性误差为±2%。     

Control of on-demand nanoliter drop volume and jetting velocity in piezoelectric inkjet printing

Consistent dosages placed with high accuracy onto the substrate are critical for drop-on-demand (DoD) inkjet printing to be adopted in additive manufacturing and device characterization. Practically, the consistency of drop volume and drop jetting velocity is subject to process uncertainties, such as fluctuations of applied pressure and variations in printheads, for which open-loop approaches are unable to compensate. In this work, a stochastic process model of the relation between two control parameters of a firing waveform and two output features, drop volume and drop jetting velocity, is developed from standard printhead calibration data. An image-based control strategy based on a projection-based one-step-ahead Kalman estimator for model parameters estimation is proposed to regulate the drop volume and the drop jetting velocity. The effectiveness of the proposed control strategy is experimentally validated for three inks with broad properties. By including input boundary layers, an order of magnitude improvement in reducing drop volume and jetting velocity variations is also experimentally demonstrated.     

基于LIGA技术制作金属微针阵列

MEMS微针在生物领域中的应用日益广泛,为了方便微针刺入皮肤且减少疼痛,要求微针具有足够的强度和锐利的尖端。传统LIGA工艺只能制造出具有高深宽比的垂直侧壁结构。对传统LIGA工艺进行调整,对光刻胶PMMA进行两次曝光,并通过移动光刻胶台改变X射线的光刻方向,使两次X射线曝光方向相垂直,提出移动LIGA工艺,即移动光刻工艺。此外,利用等腰三角形作为掩膜板图案,显影之后得到截面与X射线掩膜板图案相似的三维实心PMMA微针阵列。再利用此PMMA微针阵列作为原始模具,PDMS转模形成PDMS一级模具,电镀镍得到与PMMA微针阵列相似的金属镍微针阵列。     

收缩管型压电微滴喷射理论分析与实验研究

为了得到驱动电压波形对收缩管型压电微滴喷射性能的影响规律,基于Bogy等提出的压力波传递理论,分析了收缩管型压电微滴喷射头喷腔中的压力传导过程。构建了压电微滴喷射系统的实验平台,以质量分数为58%的甘油和水混合液为实验中的喷射对象,对微滴喷射过程中驱动电压的脉冲宽度、幅值和频率对微滴喷射性能的影响进行了研究。研究结果表明,随着驱动电压脉冲宽度的增大,所形成的液滴速度和直径呈先增大后减小,微滴喷射过程存在最佳电压脉冲保持时间;随着驱动电压脉冲幅值的增大,所形成的液滴速度和直径均增大;随着操作频率的增大,在一定范围内,液滴速度和直径几乎不受影响,但频率过大时,喷射会发生混乱。     

Real-time image-based B-mode ultrasound image simulation of needles using tensor-product interpolation

In this paper, we propose an interpolation-based method for simulating rigid needles in B-mode ultrasound images in real time. We parameterize the needle B-mode image as a function of needle position and orientation. We collect needle images under various spatial configurations in a water-tank using a needle guidance robot. Then we use multidimensional tensor-product interpolation to simulate images of needles with arbitrary poses and positions using collected images. After further processing, the interpolated needle and seed images are superimposed on top of phantom or tissue image backgrounds. The similarity between the simulated and the real images is measured using a correlation metric. A comparison is also performed with in vivo images obtained during prostate brachytherapy. Our results, carried out for both the convex (transverse plane) and linear (sagittal/para-sagittal plane) arrays of a trans-rectal transducer indicate that our interpolation method produces good results while requiring modest computing resources. The needle simulation method we present can be extended to the simulation of ultrasound images of other wire-like objects. In particular, we have shown that the proposed approach can be used to simulate brachytherapy seeds.