1、A Conceptual Approach to Integrate Design and Control for the Epoxy Dispensing ProcessH.-X. Li, S. K. Tso and H. DengDepartment of Manufacturing Engineering and Engineering Management, School of Science and Engineering, City University of Hong Kong, Hong KongPerformance improvement of manufacturing
2、systems in the semiconductor industry involves interdisciplinary expertise, such as physical modeling, mechanical design, electrical control, and even material science. Integration of these different disciplines is a challenging problem in the semiconductor industry. The paper presents a conceptual
3、approach to integrate design and control methodology for complex processes with specific application to an epoxy-dispensing control systema critical equipment in the semiconductor packaging process. This methodology includes three hierarchical levels: process design (system-level and component-level
4、), multivariable control and the statistics-based supervision. This paper deals with conceptual design at system-level by integrating an approximate model with an axiomatic approach, and briefly introduces approaches at other levels. In the conceptual design at system level, the primitive model of t
5、he system is sufficient to show some basic properties of the process, by which the axiomatic design can be easily integrated to evaluate the system design and suggest an optimal system configuration with invariant properties to internal variations. Under minimal internal variation, the multivariable
6、 control that is intended to suppress external variations can be approximately constructed by a set of independent controllers. Statistics-based supervision will provide suitable setpoints for the multivariable control so as to maintain good performance in the dynamic environment.Keywords: Conceptua
7、l and axiomatic design; Epoxy dispensing process; Hybrid process control1. IntroductionManufacturing systems in the semiconductor industry are processes with a high degree of complexity, consisting of heterogeneous subsystems and materials. Design and control for this kind of system involve differen
8、t domains, such as, mechanical engineering, electrical control, software and hardware, and even material science and physics. A typical example is an epoxy dispenser which is widely used in the semiconductor industry where accurate fluid control is needed. In the die bonding process in the semicondu
9、ctor industry, the epoxy dispenser is critical for the die attachment. Inconsistent dispensing quality is caused by internal and external variations, particularly when wide speed variations are required. Though much attention has been focused on the problems, little improvement has been made.For a h
10、eterogeneous process, the factors or variables that affect the process performance could be classified into three different types:Controllable variables that can be unconditionally handled by the external controller.Partially controllable variables that can be handled conditionally by the external c
11、ontroller.“Uncontrollable” variables that cannot be handled by the external controller.These “uncontrollable” and even partially controllable variable often cause internal variations of the process, which will eventually affect the process performance. The relationship between all these variables an
12、d the performance output is also unknown, which makes the direct control of performance extremely difficult. Therefore, an appropriate design should be found with a minimum internal variation or coupling, to reduce the “uncontrollable” variables before a better control can be achieved for each contr
13、ollable variable.Based on the above discussion, an integrated design and control methodology is proposed for the conceptual level for industrial processes, as shown in Fig. 1. This methodology involves different expertise in fundamental analysis, design, experiment, and control. The fundamentals of
14、the methodology can be classified into three hierarchical levels:1. Process designConceptual design at system level a qualitative design that is intended to achieve a proper system configuration with minimal internal variation, based on a primitive or approximate model.Quantitative design at compone
15、nt and experimental level to achieve an optimal system structure, and to explore the detailed relationship between controllable variables, based on an accurate model of the system.Fig. 1. Integrated design and control methodology for a heterogeneous process.2. Multivariable control at machine level
16、to achieve a proper decoupled control for each controllable variable.3. Statistics-based supervision at high-level to provide suitable setpoints for the multivariable controller so as to maintain the decoupling effects in the dynamic environment, through a run-by-run approach. This paper attempts to apply this methodology for a dispensing control system, with emphasis on the first phase conceptual design. A primitive model of the di
