Deng Guiling

Technology development and basic theory study of fluid dispensing - a review

Fluid dispensing is widely applied in chip package and circuit assembly. This paper reviews the advantage and limits of four kinds fluid dispensing technology, which are time-pressure dispensing, auger pump dispensing, piston valve dispensing, and jetting dispensing, and their existing status in both technology development and research, analyzes the challenge of advanced and high throughput packaging to fluid dispensing technology, discusses briefly basic theory study subject of fluid dispensing for next generation package technology.

Bump Thermal Management Analysis of LED with Flipchip Package

LED solid state lighting (SSL) has a good prospects, but there are some bottlenecks, the one is that efficiency of light emitting is not enough for general lighting, the other is too much heat generated by higher power which affect the efficiency and life of LED. Flipchips applying is good for improvement of efficiency of light emitting of LED and especially for thermal management. The effect of the layout and the number of bumps of LED flipchip to thermal management of LED light was analyzed by using FEM simulation. The results show that better effect of thermal management can get after optimizing layout of bumps, and also show that the more bump number used the better thermal management can get, but there is a best optimal number as there are some other limiting factors such as structure and cost

The Influence Regularity of Structural Parameters of Fluid Jetting Dispensing

Structural parameters of the jet-dispenser are the important factor of fluid jetting dispensing technology, them have important effect to the volume and velocity of the fluid that jetting from the nozzle outlet. This paper aim to the structural parameters of the jet-dispenser-the diameter of the nozzle and the gap between the ball-needle and the wall, through the calculation formulas of fluid cumulative volume and fluid mean flow velocity, according to MATLAB program computed cumulative fluid volume and fluid mean flow velocity under the condition of different structural parameters. The influence regularity of the diameter of the nozzle and the gap between the ball-needle and the wall are obtained preliminary, for the design and adjustment offers a certain foundation. The results show a good change characteristic of the fluid cumulative volume and fluid mean flow velocity, both of them decreases when the diameter of the nozzle gets small; but them increases when the gap between the ball-needle and wall gets small.

The Influence of Fluid Viscosity of Fluid Jetting Dispensing

Fluid viscosity is a very important factor for fluid dispensing, and it has important effect on the volume and velocity of the fluid that jetting from the nozzle outlet. This paper analyses the force that the fluid gives to needle both with low and high viscosity situation and establishes formulas. This paper compared the equivalent velocity based on fluid kinetic energy cumulative volume and fluid mean flow velocity on the condition of low viscosity and high viscosity and through comparison draws out the influence that the fluid viscosity affects on the fluid dispensing. The results well reflect the influence of the fluid viscosity effecting on fluid dispensing, and also show that the needle has long run duration in the same displacement when the fluid viscosity is high. On the high viscosity conditions, the cumulative volume and fluid mean flow velocity is less than the low viscosity situation accordingly, but their accretion process is coincident.

The influence discipline of temperature of high viscosity fluid jetting

Viscosity which varies with the temperature remarkably was one of an important factor for fluid jetting. In this paper finite element models of fluid jet-dispenser for thermal analysis and fluid-structure interaction analysis were built through ANSYS. The decided heat flux was loaded to the finite element model for thermal analysis to obtain the temperature field of the fluid field. So the average viscosity of the heated fluid can be worked out. And then the accumulative volume, average velocity and equivalent velocity of two different kinds of fluid between in heating and room temperature condition in fluid-structure interface analysis were compared. The results indicted that the heated fluid was apt to spout. And the losing heat was also worked out in jetting stage which was a reference to next work and designing the heater.

Numerical Simulations of 3D Flow in the Archimedes Pump and Analysis of Its Influence on Dispensing Quality

The fluid flow in the Archimedes pump on dispensing is analyzed. The flow process is divided into three sections: fluid feed path, screw and needle. The three-dimensional model is built, and the flow, when the screw is rotating, is simulated by using Fluent. The effects of rotate velocity, the geometric dimensions of screw, inlet pressure, needle size etc to mass flow rate are described, which provides a theoretical basis for choosing appropriate screw parameters and external conditions.

The influence of structural parameters of electromagnetic fluid jetting dispenser

The fluid flow in the fluid jetting dispenser was analyzed. We present a Numerical study of the jetting process using ANSYS fluid-structure interaction (FSI) analysis tools. The effects of gap between ball-needle and wall, the diameter of fluid chamber, the shape of the needle, the separation angle of dispensing body and the diameter of nozzle etc to mass flow rate are described. The calculation formula of cumulative fluid volume and mean flow velocity are deduced. The distribution of stress of adhesive in the jetting dispenser is obtained. Combining it with data by MATLAB show that the solution is effective, which provides a theoretical basis for choosing appropriate structural parameters of liquid jet-dispenser.

Analysis and modeling non-Newtonian fluid transferring process and dot formation in contact dispensing

Non-Newtonian fluid transferring-which denotes non-Newtonian fluid transfers from needle tip to the substrate-in contact fluid dispensing dot is very complicated and has important influences on dots qualities including dot shape and size, and dots consistency. But there have been no models and little research on non-Newtonian fluid transferring process and dot formation, although there are a few studies focusing on fluid flow in feed channel between syringe and needle exit and control models that slide over influence of fluid transferring. From the view of fluid dynamics, this paper puts forward an idea of phasing study fluid transferring mechanism and dividing the fluid transferring process into four different phases in contact dispensing dot. Also it establishes fluid dynamics models of non-Newtonian fluid transferring process from non-Newtonian fluid extrusion out of needle exit to dot formation such as model for evolvement of fluid drop at needle tip, fluid contact and spread on substrate, fluid separation into two independent part both at the needle tip and on the substrate, and dot formation. These models can study the important influences of some parameters such as dispensing height, surface tension and contact angle of the dispensing fluid material, needle tip configuration and sizes, and needle movement characteristics on dispensing dots qualities. They can also study the dispensing process parameters matching between some parameters such as dispensing height and parameters influencing fluid extrusion

Experiment study influences of some process parameters on dispensing dots consistency in contact dispensing process

Good dots consistency including both shape and size is a basic requirement in the process of fluid dispensing dot. Non-Newtonian fluid transferring, which denotes Non-Newtonian fluid transfers from needle tip to the substrate, has important influences on dots consistency in contact dispensing dot. Under dispensing condition the dispenser, needle and fluid material are selected, the main factors affecting Non-Newtonian fluid transferring are as following: the matching condition between dispensing height and parameters affecting fluid extrusion including both fluid volume and extrusion time; the fluctuation of both practical dispensing height and fluid extrusion. Through experiment, this paper studied both the matching relationship between the fluid extrusion and dispensing height and influence of fluctuation of dispensing height on dots consistency in contact dispensing dot process. Experiment results show that decrease the fluctuation of dispensing height by compensating dispensing height error caused by the flatness error of the substrate through software control can improve dots consistency, that dispensing height has direct influence on both dots size and dots consistency and there is a best matching between dispensing height and fluid extrusion volume to accomplishment best dots consistency under specific dispensing condition; and that fluid extrusion time also has some influences on dispensing dots consistency

Optimization of a zoom mechanism with flexible hinge for dispenser valve

In order to improve the life span of the jet valve, a novel structure of zoom mechanism is proposed. A hinge of the new zoom mechanism is set vertically in the new structure, compared with the horizontally hinge arranged way of the traditional zoom mechanism. Mechanical simulation models of traditional and new zoom mechanisms are established to calculate the stress of the flexible hinge. It is found that the stress of the hinge is 0.5 times smaller than the traditional hinge, and the life span is more than 10 times longer than the traditional one. Experimental results confirmed that the life span of the new jet valve exceeds 10 million times, and will provide a new structure for high frequency and heavy load zoom mechanism.