M.A. Mujeebu

A Study on the Effect of Epoxy Molding Compound (EMC) Rheology During Encapsulation of Stacked-CHIP Scale Packages (S-CSP)

The numerical and experimental investigations of three-dimensional (3-D) mold filling during encapsulation process in stacked-chip scale package (S-CSP) are presented. The finite difference method (FDM) based on Navier—Stokes equations has been employed for the flow analysis in the mold cavity. The mold flow is assumed to be non-Newtonian and non-isothermal. The proposed models can take care of polymer rheology with cure effect (Castro—Macosko model) and without cure effect (Cross model). A package with five, six, and seven overhang stacking dies without wire bonds is considered for simulation. The epoxy molding compound (EMC) used is HITACHI CEL-9200. The effects of gap between die top and mold cap surface, and between adjacent dies on flow rheology are analyzed and presented. The flow retardation in the limitation region (gap region) and smooth flow in the free region of the package is being predicted. Higher initial conversion of EMC demonstrated higher viscosity and slower melt front advancement especially under the overhang area of same die stacking region and critical gap between the die and mold cap. The void mechanism occurred due to unbalanced mold flow and critical gap clearance. The simulation results are verified with those obtained from a typical electronic industry and found in good agreement. From the results; the Castro—Macosko model is found to be more stable and reliable on the flow rheology.

Husk-Fueled Steam Turbine Cogeneration for a Rice Mill with Power Export—A Case Study

Abstract Utilization of the husk-fueled cogeneration system to meet the requirement of thermal and electrical needs enhances the energy efficiency and production capacity of rice mills. This will not only result in considerable savings but also leads to a sustainable supply of electricity and additional revenue from the surplus electricity generated from saved rice husk. This article presents a case study that was conducted in a South Indian rice mill in order to study the technical and economic feasibility of implementing a steam turbine-based cogeneration with an option for power export. In the proposed scheme, the existing boiler will be replaced by a new one of higher capacity. By means of a steam turbine topping cycle, electricity is generated and the turbine exhaust steam is utilized for heating applications. It has been found that the introduction of cogeneration will enhance the rice production by a minimum of 30 tons per day. Furthermore, the proposed system in its full time operation could yield an annual savings of about INR 4 million (

Effect of piezoelectric fan height on flow and heat transfer for electronics cooling applications

0.12 m) compared to the existing facility and the additional investment would be paid back within a period of three years.

Study on the Effect of Stack Thickness During Encapsulation of Stacked-Chip Scale Packages (S-CSP)

Piezoelectric fan is used to remove the heat from the microelectronic devices, owing to their low power consumption, minimal noise emission and small in size. In the present study, a piezoelectric fan has been investigated to analyze the performance. The paper also discusses the capability of piezoelectric fan to cool the microelectronic device and its performance. The simulation and experimental investigations have been made for two different positions of piezoelectric fan i.e. vertical and horizontal positions. The Fluent 6.2.3 software which is a computational fluid dynamics (CFD) code has been used in the simulation to predict the heat transfer coefficient and the flow fields. In the experimental set-up, two heaters in line arrangement have been used in the set-up. The flow measurements have been carried out by using the particle image velocimetry (PIV) system at different piezoelectric fan height. The heat transfer coefficients have been plotted and compared with the experimental values. The simulation results obtained are found in satisfactory agreement with the experimental results.

Development of Flexible Wings and Flapping Mechanism with Integrated Electronic Control System, for Micro Air Vehicle Research

Development of microelectronics continues toward further miniaturization. Stacked-chip scale packages (S-CSPs) can address the issues associated with high-density packaging with reduction in cost and greater improvements in functional performance. However, the problems involved in the encapsulation of S-CSPs are complex because of the crucial gap thickness between the die top and mold surface. Air traps, void formation, and flow retardation are major problems. In this paper, three-dimensional (3-D) mold filling with different arrangements of stacked dice in S-CSPs is investigated with the objective of determining the optimum number of stacked dice. A 2-D view on the top surface is chosen because it is easier to visualize the melt front compared with the 3-D view. It is found that the time needed to fill the package and the chance of void formation increase with increasing number of stacked dice.

Numerical investigation of heat transfer in Plastic Leaded Chip Carrier (PLCC) packages in in-line arrangement

This paper presents the development of flexible wings, flapping mechanism, and integrated electronic control system (ECS) to emulate the bat wing flapping for the ongoing micro air vehicle (MAV) research. Three bat species having dimensions close to the design requirement of MAV, namely, Mormopterus Planiceps, Nytophilus Geoffroyi, and Scotorepens Balstoni were selected, and the average of their physical dimensions was chosen. The commercially available titanium alloy, Ti ± 6Al ± 4V, was used for the wing frame, and the membrane was made of latex. A four-bar slider-crank mechanism was designed and fabricated to facilitate the wing flapping; ECS controlled the flapping frequency in the real-time mode. The system was tested in open air wind tunnel at frequency6 Hz, angle of attack (AOA) 0–50°, and velocity range 2–7 m s−1. The experimental flapping angle which is compared with the theoretical flapping angle was obtained from the analytical kinematic model. The mean lift and drag coefficients were also measured and the results were found to be excellent. Compared to the manual control and measurement of flapping frequency, the proposed ECS demonstrates efficient control and accurate measurement. Moreover, the tedious procedure involved in the repeated calibrations for the manual system is totally eliminated by ECS.

Development and performance analysis of novel cast copper–SiC–Gr hybrid composites

Plastic Leaded Chip Carrier (PLCC) package has been emerged a promising option to tackle the thermal management issue of micro-electronic devices. In the present study, three dimensional numerical analysis of heat and fluid flow through PLCC packages oriented in-line and mounted horizontally on a printed circuit board, is carried out using a commercial CFD code, FLUENTTM. The simulation is performed for three configurations such as 4PLCC, 8PLCC and 12PLCC under natural, mixed and forced convection modes with different inlet velocities and chip powers. The contours of average junction temperatures are obtained for each package under different conditions. It is observed that the junction temperature of the packages decreases with increase in inlet velocity and increases with chip power. Moreover, the increase in package density significantly contributed to rise in temperature of chips. Thus the present simulation demonstrates that the chip density (the number of packages mounted on a given area), chip power and the coolant inlet velocity are strongly interconnected; hence their appropriate choice would be crucial. Keywords: PLCC package, Thermal management, Numerical simulation, Average junction temperature