Open Access Original Research Article

Analyzing and Eliminating Die Passivation Crack in a Power Leadframe Package using Submodeling Approach

Jefferson Talledo

Journal of Engineering Research and Reports, Page 1-6
DOI: 10.9734/jerr/2019/v7i216964

This paper presents the submodeling approach in thermo-mechanical simulation of the die passivation crack encountered in a power leadframe package subjected to temperature cycling condition.  Without using modeling and simulation in resolving semiconductor package development issues, the process would be very costly and time-consuming. For die passivation crack, the details of the different layers of the die passivation need to be modeled and this would result in a large simulation model with considerable solution time. However, a technique known as submodeling can be used to reduce solution time without sacrificing accuracy of results. In this study, submodeling was successfully used to analyze the stresses in the critical passivation layer that resulted in the best design that eliminated the passivation crack. The modeling result showed that the crack could be eliminated by using the right passivation material layer combination and thickness. An increase in the thickness of the material layers and the additional of sublayers have provided significant stress reduction in the topmost critical passivation layer resulting in crack elimination.

Open Access Original Research Article

Reliability Assessment of a Cement Industry by Application of Weibull Method

Onoriode K. Idiapho, William E. Odinikuku, Onomine M. Akusu

Journal of Engineering Research and Reports, Page 1-11
DOI: 10.9734/jerr/2019/v7i216965

The financial cost of downtime can be very significant, especially in manufacturing industries. As a result, no business wants to experience downtime. In this study, the reliability of two identical machines code named GDA and GDB used in a cement manufacturing industry was assessed by analysis of failure times data of components in the machines by applying Weibull distribution method. The estimates of the Weibull parameters, θ and β were obtained using a reliability software tool ‘Windchill Quality Solutions 11.0 Tryout’ and the mean time to failure, failure rate and reliability of the machines was successfully determined. The result obtained showed that, the machines are undergoing rapid wear out as the values of the shape parameter obtained were greater than four. The plots of the failure rate also showed that the machines are in their wear out periods as the failure rate curves were observed to be increasing. The values of the mean time to failure of the two machines were found to be very close. The reliability of the machines was found to be increasing as their values of scale parameter, θ increases with machine GDA having the highest reliability.

Open Access Original Research Article

Improving the Solder Joint Reliability of a Power Leadframe Package Using Thermomechanical Simulation

Jefferson Talledo

Journal of Engineering Research and Reports, Page 1-6
DOI: 10.9734/jerr/2019/v7i216966

Leadframe-based packages are commonly used for semiconductor power devices. With these packages, heat dissipation is much better compared with laminate substrated-based packages. However, the solder joint reliability requirement under thermal cycling condition is also higher and this is what makes the development of a power package challenging. One of the usual requirements from customers is that there should be no solder joint failure up to 2,000 thermal cycles. This paper presents the thermomechanical simulation of a power leadframe package that was conducted to improve its solder joint reliability. Board level solder joint cycle life was predicted using finite element analysis and the result was validated with actual solder life result from board level reliability evaluation. Since available solder prediction equation was for the characteristic life (63.2% accumulative failure), using the normalized characteristic life was implemented for predicting the number of cycles to first failure of the solder joint connection and the approach showed good agreement with the actual result. Results also indicated that the choice of epoxy mold material and the type of PCB (printed circuit board) have a significant contribution to the solder joint reliability performance.

Open Access Original Research Article

Assessment of Hazards and Safety Practices in Food and Beverage Industry in Nigeria

G. C. Afube, I. L. Nwaogazie, J. N. Ugbebor

Journal of Engineering Research and Reports, Page 1-18
DOI: 10.9734/jerr/2019/v7i216967

The assessment of safety hazards is fundamental to an effective risk management in any industry. Food and beverage production involves a variety of industrial processes with associated hazards. Effective safety practices are used to reduce workplace hazards and promote safety in the work environment. This paper evaluated safety hazards and safety practices in the food and beverage industry (FBI) in South-South, Nigeria. A structured questionnaire designed in accordance with World Health Organization standard was administered to a total of 144 workers, out of which 134 (93.0%) were completed and returned. The questionnaire was fashioned to extract information on types of hazards, awareness of safety hazards, implementation of hazards and risks control measures and the effectiveness of safety hazards and risk management programmes in the food and beverage industry. A modified four-point Likert Scale was used to analyze and evaluate the questionnaire. A Proportional Importance Index (PII) was used to rank each factor variable in the questionnaire. The study identified the major hazards in the FBI as working at height (with PII = 3.3, respondents = 91%); high voltage areas (PII = 3.1 and respondents = 90%), loud noise (PII = 3.0, respondents = 80%), machines and equipment vibration (PII = 2.8, respondents = 69%) and faulty machines and equipment (PII = 2.7, respondents = 65%). The level of awareness on safety hazards amongst the workers was statistically significant (p < 0.05, 95%CI; PII = 3.1 - 3.6). The outcome of intervention showed that FBI-2 improved from 79.62% to 96.82%, FBI-3 improved from 89.81% to 96.18%, FBI-4 improved from 78.34% to 95.54% on worker’s knowledge on the assessment of hazards and risk in the FBIs. There was effective implementation of safety hazards and risks management programmes and controls in the FBI. Administrative control measures are used to reduce hazards and workers make adequate use of personnel protective equipment. There is need to evaluate the risks associated with identified high ranking hazards and develop a risk management framework for the industry based on ISO 31000 and other relevant safety regulations and guidelines.

Open Access Original Research Article

Computational Fluid Dynamics (CFD) Modelling of Mixture Formation in Gasoline Direct Injection (GDI) Engine

Sherry Kwabla Amedorme, Joseph Apodi

Journal of Engineering Research and Reports, Page 1-13
DOI: 10.9734/jerr/2019/v7i216968

Automotive engine faces stringent regulations on emission with improved fuel consumption. As such, the Gasoline Direct Injection (GDI) engines which have the potential to meet these requirements are being improved on especially the mixture formation to the burning of the mixture. In GDI, late injection compared with early injection scheme generates charge stratification which contributes to the optimised fuel consumption and combustion. As a result, this strategy in GDI engines is considered to be promising with increasing research focus. This paper aims at evaluating the computational fluids dynamics (CFD) modelling of two-phase transient injection process in generic GDI engines with the late injection to study the features of fuel atomisation process, injection velocity and its influence on turbulence. The commercial CFD code Star CCM+ was used to perform this simulation due to its advanced polyhedral mesh technology and the user-friendly interface. Transient liquid and gas flow inside the combustion chamber was simulated using the Eulerian multiphase segregated flow model with k-epsilon turbulence. The contour plots show that during the injection period turbulence for each phase was independent of the spray shape predicted to be asymmetric under non-vaporisation conditions. In addition, increasing injection velocity of liquid fuel causes stronger turbulence for the liquid phase. The results also show that the variation of turbulence for gas-phase is mainly centred in the region of the inlet during the injection process and non-homogenous turbulent characteristics were observed for the late injection with the volume fraction of the liquid phase also seen to be asymmetric.