Journal of Engineering Research and Reports

This research work centers on the performance and stability analysis of the TCP queue based network system. The TCP is a vital organ in every wireless network and due to the increasing reliance on the wireless network by most human activities, it has suffered from different forms of disturbances most especially traffic congestion which eventually results to data loss or total collapse of the network. Many works were reviewed on the TCP model and the methods proposed to improve the performance of the TCP networks. However, from the review, the TCP queue model was not examined based on its performance and reliability, to ascertain the real behavior of the system without the control measures. The step function time domain plot and bode frequency domain plot analyses measures were employed in this work.  From the simulation results, the TCP queue with time delay model recorded a 0% overshoot and settling time of 1.96e+03 seconds. With the high settling time the system performance will be very poor as a result of very slow response and it cannot support the recent high data traffic. Therefore, the system will not be able to solve the problem of congestion due to its slow response. The system also recorded a negative gain margin of -71.9dB, hence; the system is unstable and not reliable.

This paper aims to identify and eliminate the weaknesses of the epoxy mold compound (EMC) thawing process that contributes to mold misprocessing occurrence such as wrong mold compound, under thawed or expired mold compound.

Creation of automation solutions addressing high risk areas such as barcoding of compound traceability, auto-locking system of thawing cabinet and thawing room access, automated map of compound status and upgrade of lot transaction system to link with EMC status and identity was implemented. Collectively this makes the process error proof from wrong judgement or negligence from human dependent activities.

The project was able to eliminate occurrence of possible mold misprocessing related to EMC thawing and serves as cost avoidance due to potential lots affected.

This paper presents the modification and improvement done on the wire clamp and top plate (WCTP) design to eliminate the bouncing effect of the silicon die that leads to smashed ball reject during the formation of wire. The protrusion of the unit on the vacuum hole produced movement and slight vibration that affects the consistency of wirebonding. Through changing the standard vacuum hole to micro-holes provides underneath support to the unit and eliminates the overhanging or protrusion during the formation of wire. The implementation of the micro-hole design reduced the defect parts per million (dppm) occurrence to zero.

Die attach epoxy dispensing is an automated factory environment that creates some special challenges. A robust production process begins with an understanding of the adhesives in their fluid state and which important parameters must be controlled. One of the most common problems encountered with adhesives in Die attach process is epoxy tailing. Tailing in this sense means the peak of the dispensed material falls away from the center of the dot when the nozzle finishes dispensing. Dispensing requirements, techniques, and equipment resulting from this experience are discussed. Guidelines for optimizing quality is given. In this research, epoxy-associated defects are eliminated by optimizing the Break tail parameter using the Design of Experiment (DOE) methodology. The DOE prediction profile result shows that the tailing parameters recommended is Broken tail delay: 200 ms and Break tail offset is 350 counts. This study is applicable for silver filled conductive adhesive epoxy with greater than 9K Viscosity and greater than 4 Thixotropic Index.

Heat-generating equipment (such as transformers, computer microchips, car engines, nuclear reactors, etc.) requires an efficient cooling mechanism to safeguard them from thermal degradation and to enhance their life span. The use of Nanofluids as opposed to conventional heat transfer fluids in their cooling system is to ensure that they are properly cooled. Nanofluids display superior thermal properties and they are synthesized from nanosized materials such as metals ((Copper (Cu), Silver (Ag), Nickel (Ni), and Gold (Au)), metal oxides (( Aluminum oxide (Al₂O₃), Cupric oxide (CuO), Magnesium oxide (MgO), Zinc oxide (ZnO), Silica (SiO₂), Iron (III) oxide (Fe₂O₃), and Titania  (TiO₂)), metal carbide (such as Silicon carbide (SiC)), metal nitride  (such as Aluminium nitride (AIN)), or Carbon materials ((Carbon nanotubes (CNTs), Multi-wall carbon nanotubes (MWCNTs), diamond, and graphite)) suspended in base fluids (such as water, ethylene glycol, engine oil, transformer oil, vegetable oil, kerosene, toluene, etc.). The current review explores methods used in the synthesis of nanofluids (One-step method, Two-step method, Solvothermal/Hydrothermal process), factors influencing their thermophysical properties (Particle volume concentration, pH, particle size, particle shape, particle material, base fluid material, temperature, shear rate, and surfactants) and their applications (Heat transfer applications, automotive applications, biomedical applications, electronic applications, Nano-based microbial fuel cells, and Nano-based brake fluids).