Modeling of Rotary Screw Fluid Dispensing Processes

[+] Author and Article Information
X. B. Chen

Department of Mechanical Engineering, University of Saskatchewan, Saskatoon SK S7N 5A9, Canadaxbc719@mail.usask.ca

J. Electron. Packag 129(2), 172-178 (Jul 21, 2006) (7 pages) doi:10.1115/1.2721090 History: Received January 04, 2006; Revised July 21, 2006

Fluid dispensing is a process widely used in electronics packaging manufacturing, by which fluid materials are delivered in a controlled manner for the purpose of bonding, sealing, coating, or conducting. Among various dispensing approaches, the use of a motor-driven screw is recognized as one of the most promising approaches due to its capacity of achieving high flow rates without the need of refilling. In a dispensing process, the flow rate of fluid dispensed is critical to control the volume or amount of fluid dispensed. This paper presents the development of a model for the rotary screw dispensing process. By using the power law equation, the flow behavior of the fluid being dispensed is characterized and then, based on the fundamentals of flow in screw channels and circular tubes, a model is developed to represent the flow rate in the rotary screw dispensing process. Experiments and simulations were carried out to verify the model effectiveness as well as to investigate the performance of the rotary screw dispensing process.

Copyright © 2007 by American Society of Mechanical Engineers
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Figure 1

Dispensing applications: (a) die encapsulation; and (b) surface mount technology

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Figure 2

Schematic of a dispensing system employing the rotary screw approach

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Figure 3

Geometry of a screw channel

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Figure 4

Dispensing system and the pressures of interest

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Figure 5

Circular tube consisting of m segments with different diameters

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Figure 6

Rotary screw pump (DV-8000, Asymtek)

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Figure 7

Flow rate versus screw rotational speed at different applied air pressures (needle heater temperature=50°C)

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Figure 8

Flow rate versus screw rotational speed at different needle heater temperatures (applied air pressure=4bar)

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Figure 9

Simulated flow rate versus screw rotational speed: (a) dispensing materials with different power law indexes; and (b) using different needle diameters




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