Simulation and experimental study on temperature field of fluid jet-dispenser
Fluid jet-dispensing technology has been widely used in micro-electronic encapsulation industry. The fluid viscosity varies as temperature changes, while it affects the process remarkably. Besides basic method on temperature field solution, some thermal behaviors, including heat conduction and heat exchange, boundary conditions and some physical parameters are overall analyzed in this paper. Based on the simulation software platform ANSYS, a two-dimensional transient temperature field model of jet-dispenser was built, and simulation programs on temperature field for two sorts of fluid with obviously different thermal conductivity were performed. Then heating experiments were finished to validate the feasibility of FEA, and results show that temperature distribution is homogeneous along fluid area and it meets the conditions of jetting.
Fluid dynamics of jetting dispensing process based on simulation and experiment
Dispensing technology is widely applied in semiconductor packaging surface mounting technology, LED packaging, where needs accurate flow control. Jetting dispensing with high performance is the mainstream in dispensing technology in the future. In this paper, FLUENT software is introduced to simulate the formation process of the droplets with a two-dimensional axisymmetric swirl model. The data of pressure distribution in the interior of the dispenser under certain condition could be get during the process, then a jetting dispenser driven by mechanical collision with experiment test system is built based on simulation results to study the process of jetting dispensing. Using a High Speed Digital-Cram, the image of the glue droplets formation process in the high speed jetting dispensing could be obtained and the volume of droplets could be analyzed with Image Processing Technology. Finally, the actual volume of the glue droplets calculated by a precision measuring cylinder are compared with simulation results and the test results show that the experimental results closely match the theoretical simulation. Under the condition of normal temperature, the jetting dispenser could realize the viscosity of glue up to 1.2 Pa.s, and the volume of droplet for 86nL.
Effects of reservoir volume on performance of pulse tube cooler.
A pulse tube cooler has the advantages of long-life and low-vibration over conventional cryocoolers such as G-M and Stirling coolers because of the absence of moving parts at low temperature. On the other hand, the combination of a reservoir and orifice is indispensable to optimize the performance of pulse tube coolers. In order to make the pulse tube cooler compact for practical applications, the volume of reservoir should be minimized. This paper analyzes the effects of the reservoir volume on the thermodynamic performance of various components in a simple orifice and a double-inlet pulse tube cooler by combining a linearized model with a thermodynamic analysis. Expressions of entropy production for those components are presented. The results show that the reservoir volume has a significant influence on the entropy production in the various components when the reservoir to pulse tube volume ratio is smaller than about 5. The ratio is important to determine the minimum reservoir volume for a pulse tube cooler. Optimum settings for a double-inlet pulse tube cooler are also discussed.