Open Access Original Research Article

Rubber-tip Design Improvement for Die Crack Elimination at Diebond Process

Rennier S. Rodriguez, Frederick Ray I. Gomez

Journal of Engineering Research and Reports, Page 1-5
DOI: 10.9734/jerr/2020/v12i217074

The paper focused on the elimination of die crack occurrence at the diebond process. Design of experiment (DOE) was done on the pick and place rubber-tip design and an improved design was finalized. The improved rubber-tip configuration with smaller vacuum design and full contact surface eventually resolved the die crack issues, improving the manufacturability of thin silicon die during diebond process. For future works, the configuration could be applied for packages with similar requirement.

Open Access Original Research Article

Optimization of the Operational Conditions for Low-Head Pelton Wheel Turbine Developed for Power Generation

O. O. Oyebode

Journal of Engineering Research and Reports, Page 6-17
DOI: 10.9734/jerr/2020/v12i217075

In a bid to optimize the performance of a Pelton Wheel Turbine developed the performance evaluation of the turbine at various conditions was carried out using a portion of the overflow from the University of Ilorin (UNILORIN) dam. The collected overflow has a net head of 4 m, flow rate of 0.017m3/sec. and theoretical hydropower energy of 668W. The turbine was tested and the optimized value of operating conditions namely; angle of inclination (15o above tangent, tangential and 15o below tangent), height to impact point (200 mm, 250 mm and 300 mm) and length to impact point (50 mm, 100 mm and 150 mm) were pre-set at their various levels. The measured outputs were Turbine Speed, Turbine Torque, Alternator Speed as well as the output voltage. The optimum values of the process output or measured parameters were determined statistically using a 33X2 factorial experiment in three replicates. The optimum Turbine speed (538.38 rpm) in off load condition was achieved at 250 mm height to impact point, 150 mm length to impact point and angle at tangential inclination. Similar combination also yielded an optimum turbine torque of 46.16 kNm. The optimum Turbine speed (392.02 rpm) in on-load condition was achieved at 250 mm height to impact point, 150 mm length to impact point and angle at tangential inclination. Similar combination also yielded an optimum Turbine Torque of 36.46kNm, optimum Alternator speed of 1768.56 rpm and an optimum output voltage of 7.87V. The results therefore show that the turbine must be set at 250 mm height to impact point, 150 mm length to impact point and the water jet at a tangential flow for it to perform optimally.

Open Access Original Research Article

RF Matching Networks Using S-Parameters

Frederick Ray I. Gomez

Journal of Engineering Research and Reports, Page 18-24
DOI: 10.9734/jerr/2020/v12i217076

The paper presents a design and study of impedance matching for radio frequency (RF) circuit application of common-source amplifier topology. Matching networks for input and output sides of the amplifier were determined from the S-parameters given for the transistor at frequency of 2.6 GHz and ensuring unconditional stability requirement. Impedance matching is necessary in RF circuit design to provide maximum possible power transfer between the source and the load.  Two designs were modeled, simulated and analyzed employing L-network input and output matching networks. The design with inductor-capacitor combination in the L-matching networks exhibited a stable and smoother behavior for higher frequencies compared to an all-inductor design. Complex tradeoffs among technology specifications and design parameters are inevitable, therefore should be carefully handled in designing the impedance matching networks, to optimize the performance of the common-source amplifier. Ultimately, the common-source amplifier achieved a gain of 6.569 dB at 2.6 GHz. For future research, physical implementations of the impedance matching networks could be studied in order to improve and optimize the simulated models.

Open Access Original Research Article

Design and Fabrication of a Watermelon Ripeness Tester Using Matlab Software GUI

V. C. Okafor

Journal of Engineering Research and Reports, Page 25-36
DOI: 10.9734/jerr/2020/v12i217077

A non-destructive way to determine the ripeness of watermelon is very difficult, by outward characteristics such as size or external colour and used methods include different limitations. In this study a simple and intelligent method to determine the ripeness of watermelon was designed and developed by integrating a conventional method with electronics device, the ripeness of watermelon can be determined easily and reliable. Microphone was placed under the fruit sample to record a thumping signal. The recorded signals were converted into Fast Fourier Transform (FFT) waveform using MATLAB Software. The patterns of FFT waveforms were analysed using average magnitude at the frequency between 100 Hz and 4000 Hz to classify the ripeness. The average magnitude of was within the range of 0.00019 to 0.00030, and the magnitudes below 0.00025 were termed unripe and magnitudes above 0.00025 were termed ripe. Recommendations for further studies were stated.

Open Access Original Research Article

Non-stick on Pad Defect Reduction through Clamp and Insert Design Augmentation

Antonio Sumagpang Jr., Rennier Rodriguez, Frederick Ray Gomez

Journal of Engineering Research and Reports, Page 37-45
DOI: 10.9734/jerr/2020/v12i217078

With new and continuous technology development and breakthroughs, few to several challenges in semiconductor assembly manufacturing are inevitable. One critical assembly process often affected with these technology trends and changes is the wirebond process. In due course, this paper focused on the elimination of non-stick on pad (NSOP) assembly defect at the wirebond process. Fishbone analysis and why-why analysis were done to comprehensively investigate the root-cause and eventually address the problem. High NSOP rejection rate was identified to be attributed to clamp and insert design, and was verified through series of analysis, design of experiment (DOE) and validation runs. Results revealed that by using the modified clamp and insert design with more holes would address NSOP rejection with around 90% defect reduction.