Integrated modelling of a time-pressure fluid dispensing system for electronics manufacturing

In electronics manufacturing the time-pressure dispensing system has been widely used to squeeze adhesive fluid in a syringe onto boards or substrates with pressurised air. For accurate control of the fluid volume, it is vital to have a thorough understanding of the whole process. However, the complexity of the process, which includes air-fluid coupling and their nonlinear uncertainties, makes it difficult to obtain an accurate process model. Using the spectral method, an approximate fluid flow model for both the Newtonian and non-Newtonian fluid can be developed. By taking into account nonlinear flow passing through the valve, attenuation and time delay in the pneumatic lines, syringe chamber dynamics and fluid flow dynamics, a simple but effective model is derived to describe the whole dispensing system with reasonable accuracy. Experiments performed thereafter validate the model.     

RUN TO RUN CONTROL OF TIME-PRESSURE DISPENSING SYSTEM

In electronics packaging the time-pressure dispensing system is widely used to squeeze theadhesive fluid in a syringe onto boards or substrates with the pressurized air. However complexity ofthe process, Which includes the air-fluid coupling and the nonlinear uncertaintes, makes it difficult tohave a consistent process performance. An integrated dispensing process model is first introduced andthen its input-output regression relationship is used to design a run to run control methodology for thisprocess. The controller takes EWMA scheme and its stability region is given. Experimental resultsverify the effectiveness of the proposed run to run control method for dispensing process.     

Design and characterization of a precision fluid dispensing valve

Precision fluid dispensing is a complicated but yet relevant process where fluid is dispensed in a controlled manner. It is important and applicable in an array of applications ranging from dispensing of food products, biomedical applications to dispensing of adhesive and encapsulants in the semi-conductor industry. This paper discusses the design and characterization of a precision fluid dispensing hybrid valve based on the time-pressure, positive displacement pump, and adhesive jetting technologies. The main advantage of this dispensing method is that the amount of fluid dispensed is independent of the standoff height and does not rely on surface tension between the substrate and the fluid for clean dispensation. Specifically, the dispensed fluid is jetted from a fixed needle height, and hence, repeatability and accuracy is improved while eliminating vertical travel. A prototype valve was built and tested for precision and accuracy of milligrams over a range of pressures and time. The test results are promising, indicating high repeatability and accuracy for low to medium viscous materials and are comparable to existing commercially available precision dispensing systems.     

基于图像匹配的自动点胶系统

在电子元器件装配领域,基于图像匹配的时间/压力型点胶机有着广泛的应用.它利用CCD,基于图像匹配的原理,在每个电子元器件上自动寻找点胶位置初始点,使得针头对着精密、微小的电子元器件在自动点胶时可以准确按照规定的轨迹进行动作.基于点胶设备的实际应用,综合考虑影响点胶效果的因素、温控系统,基于图像匹配的软件流程,描述出点胶设备的基本构架.实验结果验证了所提出的点胶效果的影响因素以及基于CCD的图像匹配技术应用的准确性.     

Model-based robust design for time�Cpressure fluid dispensing using surrogate modeling

In industry, the time?Cpressure dispensing system has been widely used to squeeze the adhesive fluid in a syringe onto boards or substrates with the pressurized air. For consistent dispensing of the fluid volume, it is vital to have a robust dispensing system insensitive to operation condition variation. In academia, much dispensing research has been done via modeling and control approach. However, a systematic design approach to determine an optimal operation condition for time?Cpressure dispensing is not available. This paper presents such a method for both line dispensing and dot dispensing, by means of model-based robust design. In particular, all kinds of the quantities involved in the dispensing task is classified into three groups: the design variables (DV), the design environment parameters (DEP) and performance functions, in the framework of model-based robust design. By this approach, the sensitivity analysis can be developed. While the sensitivity for DEP is analytic, whereas the sensitivity function for DV is more complex and have to be approximated by surrogate modeling. Thus the robust design can be used for time?Cpressure dispensing. The results show that dispensing performance robustness can be improved by choosing the appropriate system parameters. Simulations performed thereafter validate the effectiveness of this design method.     

参数自调整非接触式微量试剂分配系统

在高通量的蛋白质结晶操作中,需要对近千种试剂进行快速,微量,精确的试剂分配操作,而且对试剂分配系统的可靠性,灵活性和精确性要求也不断提高。本文研制了一款具有控制参数自调整功能的非接触式微量试剂分配系统。该系统采用精密微电磁阀控制预压液体的流动来实现试剂的分配操作。独特的试剂分配管路设计使电磁阀不易堵塞;非接触式的分配方式减少了试剂污染情况,分配速度更快,更易清洗;自行研制一款MEMS压差式微流量传感器并集成于系统中用于采集试剂分配过程中的流量信息,实现了试剂特性和体积变化时控制参数的自动调整功能,提高了分配精度和灵活性。文中详细介绍了系统的组成结构以及试剂分配过程原理。最后,针对不同粘性试剂进行分配精度的测试,结果表明该系统最小可分配50nl体积试剂,分配精度达8%。在分配试剂体积大于1μl时,重复精度<3%。     

机器人贴装涂胶过程建模与时序分析

空间太阳电池帆板的贴装生产过程目前在国内依旧采用单一手工操作,很难保证质量.该文对太阳电池帆板自动贴装机器人的涂胶过程进行了流动特性建模与时序状态分析,确定了机器人单片涂胶周期和串联涂胶周期,得到了机器人任一涂胶拐点处的时序值,及任意时刻机器人对应的涂胶位置坐标.通过对机器人的涂胶过程分析,得到了针管内胶体流动的速度场模型,并确定了胶体流量算式,给出了不同变量条件下涂胶过程的速度场模型及涂胶流量模型,为空间太阳帆板的自动贴装涂胶生产提供了可靠的数据模型.     

An empirical approach to modelling fluid dispensing for electronic packaging

Fluid dispensing is a popular process in semiconductor manufacturing industry which is commonly used in die-bonding as well as microchip encapsulation for electronic packaging. Modelling the fluid dispensing process is important to understand the process behaviour as well as determine optimum operating conditions of the process for a high-yield, low cost and robust operation. Previous studies of fluid dispensing mainly focus on the development of analytical models. However, an analytical model for fluid dispensing, which can provide accurate results, is very difficult to develop because of the complex behaviour of fluid dispensing and high degree of uncertainties of the process in a real world environment. In this project, an empirical approach to modelling fluid dispensing was attempted. Two common empirical modelling techniques, statistical regression and neural networks, were introduced to model fluid dispensing process for electronic packaging. Development of neural network based process models using genetic algorithm (GA) and Levenberg−Marquardt algorithm are presented. Validation tests were performed to evaluate the effectiveness of the developed process models from which a multiple regression model and a GA trained neural network with the architecture of 3-15-1 were identified to be the process models of the fluid dispensing respectively for the encapsulation weight and encapsulation thickness.     

Modeling manufacturing processes using fuzzy regression with the detection of outliers

Empirical modeling, which involves various common techniques such as statistical regression, artificial neural networks and fuzzy logic modeling, is a popular approach to developing models for manufacturing processes. Among those techniques, statistical regression is the most popular one used to develop the explicit type of empirical models. However, if the experimental data and results contain a substantial degree of fuzziness, fuzzy regression is more appropriate for use in developing empirical models based on such data and results. In recent years, attempts have been made to use fuzzy regression to model manufacturing processes. However, it has been recognized that the existence of outliers can have a great effect on the prediction accuracy of a fuzzy regression model. This problem has not been well addressed in the previous studies on fuzzy regression. In this paper, an algorithm for detecting outliers based on Peters’ fuzzy regression is proposed. The application of the algorithm to developing a fuzzy regression-based process model of the dispensing of fluid for IC chip encapsulation is described. Finally, the results of the validation of the models are discussed.     

Modeling of epoxy dispensing process using a hybrid fuzzy regression approach

In the semiconductor manufacturing industry, epoxy dispensing is a popular process commonly used in die-bonding as well as in microchip encapsulation for electronic packaging. Modeling the epoxy dispensing process is important because it enables us to understand the process behavior, as well as determine the optimum operating conditions of the process for a high yield, low cost, and robust operation. Previous studies of epoxy dispensing have mainly focused on the development of analytical models. However, an analytical model for epoxy dispensing is difficult to develop because of its complex behavior and high degree of uncertainty associated with the process in a real-world environment. Previous studies of modeling the epoxy dispensing process have not addressed the development of explicit models involving high-order and interaction terms, as well as fuzziness between process parameters. In this paper, a hybrid fuzzy regression (HFR) method integrating fuzzy regression with genetic programming is proposed to make up the deficiency. Two process models are generated for the two quality characteristics of the process, encapsulation weight and encapsulation thickness based on the HFR, respectively. Validation tests are performed. The performance of the models developed based on the HFR outperforms the performance of those based on statistical regression and fuzzy regression.     

Motion induced signals of Coriolis flowmeters

Rotation induced Coriolis flowmeter output was observed in a robotic fluid dispensing test. This motion sensitivity of Coriolis flowmeters was confirmed to be universal for various noninertial reference frames. It was also confirmed that this motion sensitivity is a general aspect of many Coriolis flowmeter types. Qualitative tests revealed that the motion induced signals appear to be proportional to frame rotation rate and are strongly dependent on the flow tube oscillation velocity vectors.     

微电子封装中的喷射点胶过程建模和控制

针对喷射点胶阀存在点胶一致性差的问题,提出了一种基于体积估计模型的批次PI控制策略。通过对胶体流变特性进行分析,基于胶体剪切应力和剪切速率关系建立了喷射点胶的流量模型,依此推导出体积估计模型。基于建立的模型,运用批次PI算法来实现喷射点胶阀的一致性控制。仿真和实验结果验证了体积估计模型的可靠性,并表明该控制方法能有效地改善喷射点胶的一致性。     

The process modelling of epoxy dispensing for microchip encapsulation using fuzzy linear regression with fuzzy intervals

Epoxy dispensing is a popular way to perform microchip encapsulation for chip-on-board (COB) packages. However, the determination of the proper process parameters setting for a satisfactory encapsulation quality is difficult due to the complex behaviour of the encapsulant during the dispensing process and the inherent fuzziness of epoxy dispensing systems. Sometimes, the observed values from the process may be irregular. In conventional regression models, deviations between the observed values and the estimated values are supposed to have a probability distribution. However, when data is scattered, the obtained regression model has too wide of a possibility range. These deviations in processes such as epoxy dispensing can be regarded as system fuzziness that can be dealt with satisfactorily using a fuzzy regression method. In this paper, the fuzzy linear regression concept with fuzzy intervals and its application to the process modelling of epoxy dispensing for microchip encapsulation are described. Two fuzzy regression models, expressing the correlation between various process parameters and the two quality characteristics, respectively, were developed. Validation experiments were performed to demonstrate the effectiveness of the method for process modelling.     

Review: geometric and dimensional tolerance modeling for sheet metal forming and integration with CAPP

The focus of this publication is a review of the state of the art in tolerance analysis, synthesis, and transfer for geometric and dimensional tolerances in sheet metal forming and the integration solutions with computer-aided process planning systems. In this context, the general tolerance methods are first described. Then, the mathematical models for sheet metal tolerance analysis and synthesis are examined in detail. To address the CAPP modeling concerns, the paper is then followed up with a brief review of past research works related to feature-based process planning. Finally, those imperative future research areas are identified.     

Integrated Modeling Framework for Manufacturing Systems: A Unified Representation of the Physical Process and Information System

The task of process modeling in a manufacturing environment centers around controlling and improving the flow of materials. This flow comprises a complicated web of control and physical systems. Despite a variety of manufacturing system modeling approaches, more rigorous process modeling is required. This paper presents an integrated modeling framework for manufacturing systems (IMF-M). Conceptual modeling of physical materials flow supported by a graphical representation facilitates improvement of operations in manufacturing environments. A declarative and executable representation of control information systems helps to improve information management by managing a variety of information models with improved readability and reusability. A unified representation of the physical process and information system provides a common modeling milieu in which efforts can be coordinated among several groups working in the different domains of scheduling, shop floor and logistics control, and information system. Since the framework helps adapt to the changes of the physical process and information system affecting each other in a consistent manner, the modeling output enhances integration of the manufacturing system.     

微电子封装点胶技术的研究进展

流体点胶是一种以受控的方式对流体进行精确分配的过程,它是微电子封装行业的关键技术之一。目前,点胶技术逐渐由接触式点胶向无接触式（喷射）点胶技术转变。从微电子封装过程的应用出发,对点胶技术的发展进行了概述;在对比各种点胶方式的同时,重点介绍了无接触式喷射点胶技术,以及其中所涉及的关键技术,并提出了评价点胶品质的标准。     

FLOW STRESS DATA FOR FINITE ELEMENT SIMULATION IN METAL CUTTING: A PROGRESS REPORT ON MADAMS

To obtain reliable results from Finite Element (FE) simulation of machining processes, it is necessary to have as input the properties of the workpiece and tool materials as well as the characteristics of the tool/chip interface. These input parameters include physical and thermal data, friction and heat transfer, and most importantly the flow stress of the workpiece material under high strain, strain rate and temperature conditions that exist during the process. This paper presents a brief review of FE simulation of machining processes, a review of the approaches used to determine the flow stress at high deformation rate, and the examples of different constitutive equations used to represent such flow stress data. A material property database (MADAMS) has been developed and provides useful information to conduct simulations of machining processes. The main objectives of the material database are to assist researchers in areas of machining analysis and material modeling and to promote collaboration between various international research groups.     

智慧药房上药机械手系统送药装置的设计与研究

针对目前国内智慧药房自动化设备发展中在上药速率和上药可靠性方面存在的问题,设计一种新的基于PLC的上药机械手系统。在分析了目前国内智慧药房自动化设备运行中存在的上药机械手对不同尺寸药盒适应范围小和对高就诊率的药盒补充需求不足等问题后,设计了一种带有限位机构的送药装置,并采用双送药装置的自动化上药机械手系统。根据上药机械手系统及其送药装置的动作过程和工作流程,设计了上药机械手系统的硬件控制系统组成和软件控制系统结构。结果表明:带有限位机构的送药装置能够保证不同尺寸大小的药盒在其内整齐叠放,且上药过程中不会出现药盒倾倒现象,具有较高的可靠性。采用双送药装置的自动化上药机械手系统相比于传统的单送药装置上药机械手系统,上药速度提高了近一倍。     

精密点胶螺杆泵胶液流动分析与数值仿真

分析了胶液在精密点胶螺杆泵内的流动过程。把胶液在螺杆泵内的流动分成入口段、螺杆段和针头段三段进行分析;建立三维几何模型,利用流体仿真软件FLUENT对胶液在螺杆旋转条件下的流动过程进行数值模拟,得到了螺杆转速、螺槽尺寸、入口压力和针头大小等参数对挤胶量的影响规律。通过试验验证了仿真结果的合理性。研究结果为确定合理的螺杆泵几何参数及外部条件提供了理论依据。     

Coriolis flowmeters: a review of developments over the past 20 years,and an assessment of the state of the art and likely future directions

This paper starts from a brief revisit of key early published work so that an overview of modern Coriolis flowmeters can be provided based on a historical background. The paper, then, focuses on providing an updated review of Coriolis flow measurement technology over the past 20 years. Published research work and industrial Coriolis flowmeter design are both reviewed in details. It is the intention of this paper to provide a comprehensive review study of all important topics in the subject, which include interesting theoretical and experimental studies and innovative industrial developments and applications. The advances in fundamental understanding and technology development are clearly identified. Future directions in various areas together with some open questions are also outlined.