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.
Jetting Technology for Microelectronics
Selective dispensing of fluid onto electronic packages without physical contact in a reliable and consistent manner seems a natural alternative to traditional mass transfer methods that are often invasive and lack consistency. With the advances and improvements in technology of the microelectronic industry and the nano-electronic, the scale of components used has consistently grown smaller. This has allowed for more efficient use of resources (a silicon chip that once held hundreds of transistors now holds millions) and more convenient and consumer friendly products (palm sized computers compared to warehouse sized computers forty years ago). However, as advances lead to decreases in the scale of components, similar advances must be made in the production process in order to assemble these components. One method used in current printed circuit board assembly is attaching components to the board with a surface mount adhesive (SMA). A small dot of adhesive is placed between two pads. Passive components i.e., 0402 can be attached to the board by jetting small dots of SMA material. The component is then placed on top of the SMA. The SMA is then cured, fixing the component in place. When applying the SMA, it is vital that the adhesives not cover any part of the leads, as this may decrease the quality of the solder connection. As components decrease in size, so does the gap between the leads. It is therefore necessary for the size of the adhesive dot to decrease to the same degree as the components decrease. Current technology can produce dots of surface mount adhesive of approximately 20 mil diameter and roughly 0.03-0.04 ml volume. Anticipating the continuing trend in component scale reduction, however, predicts that dots in the 8-10 mil diameter range will be required. The experiment described in this paper attempted to reach this measure of dot size using SMA and silver epoxy materials. Small dot jetting has additional leading edge applications. The present work shows the capability of jetting material in volumes of about 3 nano-liters. The underfilling 3D-packages with small gaps that are required to accomplish thin packages, as well as the underfilling of small die present yet another challenge to the consistency and accuracy of dispensing processes. This paper addresses the underfilling of 3D stacked die by jetting material on die surfaces with small dot to accomplish gaps of just a few microns gap. The challenge of jetting abrasive materials is addressed here by monitoring wearout evolution on the jet itself and corresponding effects on the jetted fluid characteristics.
Laminar heat or mass transfer in rectangular channels and in cylindrical tubes for fully developed flow: comparison of solutions obtained for various boundary conditions
Abstract A comparison is made of results obtained with various boundary conditions at the wall of the channels. By comparing blood Sherwood numbers for finite wall resistance with those for constant concentration boundary condition only a small variation is found for various points along the blood channel.