Open Access Original Research Article

Flux Shorting Mitigation on Semiconductor BGA Device through Process Design Enhancement

Antonio R. Sumagpang Jr., Edwin M. Graycochea Jr., Frederick Ray I. Gomez

Journal of Engineering Research and Reports, Page 1-5
DOI: 10.9734/jerr/2020/v19i317231

With the new and upcoming technologies in semiconductor industry, packages like the ball grid array (BGA) are getting more challenging to process due to inherent issues that come along. Process improvement through modification in the design of indirect material is one key direction to improve the productivity during assembly manufacturing. In this paper, an enhanced design of dipping plate is presented to solve the issue of flux shorting due to out-of-specs dipping plate at ball attach process. The study used a side by side comparison to prove that the new design  is better than that of the out-of-specs indirect material. With the new enhanced design of  dipping plate and the optimized flux depth parameter, flux shorting occurrence was successfully mitigated.

Open Access Original Research Article

The Effect of a Dynamic Lens Structure on the Open Circuit Voltage of a Concentrated Photovoltaic Model

Mamoun Lyes Hennache, Ali Hennache

Journal of Engineering Research and Reports, Page 6-14
DOI: 10.9734/jerr/2020/v19i317232

The current concerns of energy shortage and global warming have brought the development of strategies to utilize renewable energy resources at the forefront of public interest. Solar power is one of renewable energy's most promising sources. Concentrated photovoltaics can significantly improve a photovoltaic (PV) system's electricity production. This paper presents a novel approach of a CPV unit with a dynamic lens structure. Design and Implementation of both electrical and mechanical design in order to move the lens to achieve a better voltage output. Experiments had been carried out and measurements were taken according to the light source which was the sun in one case and the artificial light in the other. Based on the experimental results the effect of the dynamic lens was studied and compared to the fixed lens. The results showed that the dynamic lens CPV model was more effective and efficient than the fixed one.

Open Access Original Research Article

Addressing Off-Centered Ball through Solder Paste Material Evaluation

B. C. Bacquian, F. R. Gomez, E. Graycochea Jr., N. Gomez

Journal of Engineering Research and Reports, Page 15-18
DOI: 10.9734/jerr/2020/v19i317233

Stencil printing using solder paste material is one of the challenging processes in semiconductor assembly manufacturing. During evaluation of a semiconductor device, off-centered ball issue    was encountered. The study aimed to mitigate the off-centered ball issue at stencil printing  process by exploring the effect of different solder paste materials. Both solder paste materials  were cured using the same reflow condition. However, solder paste material 1 (S1) resulted  to cold solder joints while material 2 (S2) showed cured solder paste characteristic. With S2 material used in stencil printing, the off-centered ball occurrence was eventually eliminated. For future works, the solder paste material and configuration could be used for devices with similar requirement.

Open Access Original Research Article

Possibility of Usage of Seawater for Mixing and Curing of Concrete in Salty Water Localities

E. I. Ogunjiofor

Journal of Engineering Research and Reports, Page 19-27
DOI: 10.9734/jerr/2020/v19i317234

Aims: This study examines the possibility of using seawater as an alternative to freshwater in concrete mixing and curing in areas prone to saltwater. The study was as a result of shortage and scarcity of Freshwater in some parts of the world; mostly in the coastal areas, where seawater is the only source of water.

Place and Duration of Study: Seawater was obtained from Port Harcourt Tourist beach, River State, Nigeria was used to mix and cure a set of concrete cubes (CSW). And freshwater obtained from our Civil Engineering laboratory was used to mix and cure another set of concrete cubes (CFW) that serves as a control. The maximum days of curing were 28days.

Methodology: Concrete cubes of 150x150x150mm3 were produced and cured with sea and freshwater respectively. The compressive strength of those cubes were determined using Compression Testing Machine. The studied variable was only water used for mixing and curing of the concrete cubes. Other constituents of the concrete: cement, fine aggregate, and coarse aggregate were kept constant.

Results: It was found that the compressive strengths of concrete cubes mixed and cured with seawater at 7, 14, 21 and 28days were within the acceptable limits and a bit higher than those of cubes mixed and cured with fresh water. The variation in compressive strength of CSW and CFW at the 28th day of curing was just 1.45%. Hence, the seawater didn’t affect the compressive strength.

Conclusion: With the little variation in compressive strength between the CSW and CFW at the 28th day of curing; it is recommended that seawater can possibly be used for concrete mixing and curing in areas where freshwater is not available; provided that the concrete is kept inherently dry to prevent corrosion. In addition, higher concrete covers can be provided when designing the concrete structures. Meanwhile, careful and adequate design, well-supervised construction, and curing should be ensured to improve the ingress resistance of the concrete structures. However, the long-term effect of the seawater on the properties of concrete and reinforcements were not investigated.

Open Access Original Research Article

Characterization, Grading and Flexural Modelling of Rubberwood (Hevea brasiliensis); for the Local and International Construction Industry

O. I. Akpokodje, H. Uguru, D. Esegbuyota

Journal of Engineering Research and Reports, Page 28-47
DOI: 10.9734/jerr/2020/v19i317235

Rubberwood, hitherto solely employed as fuel wood has found fairly suitable use in the Nigerian construction industry. This paper investigated the engineering properties of this low cost, alternative, timber material, produced from Rubber trees (Hevea brasiliensis); often employed within two weeks of felling, for the construction of formworks and related wood works. No real attempt has been made to formally grade or coordinate the properties of rubber wood as employed in the Nigerian construction industry. The research was aimed to achieve the determination of the physical and mechanical properties of naturally seasoned rubber wood obtained from the Niger Delta region of Nigeria, and assigned to it a strength/grade class. Specific properties required for grading were determined using suitable standard methods. The structural and mechanical properties of the timber wood were determined using the three point bending test in accordance with standards presented by BS EN 408 and ASTM D193, but with an aspect ratio of 12. Characteristic values for the wood properties (at the tested moisture content “MC”) were determined in accordance with BS EN 384. Adjustments were made to the characteristic values for the mechanical properties, and the density of the timber species at the test MC; to conform with the international reference MC condition of 12% (as specified by BS EN 338), and also 18% MC, to suit standards required for the Nigerian environmental condition (NCP 2). Grading was carried out in accordance with BS EN 338. The characteristic values for the mechanical properties (at 12% and 18% MC) evaluated from test results are as follows; characteristic values for MOR and MOE were 20.191 N/mm2 and 19.283 N/mm2, and 2285.784 N/mm2 and 2195.606 N/mm2 respectively. Mean values for densities (at 12% and 18% MC) were 406.169 Kg/m3 and 431.058 Kg/m3, while the characteristic values for the related densities were 338.474 Kg/m3 and 359.215 Kg/m3. Furthermore, the mean green density and characteristic green density for the rubberwood were 988.148 Kg/m3 and 900.352 Kg/m3 respectively. From the results obtained, rubberwood procured from the Niger Delta region was categorized as a grade D30 and D35 timber material at 18% MC and 12% MC respectively. Rubberwood from the Niger Delta can be conveniently employed as an alternative material to conventional timber, in both the furniture and the construction industry, but with special considerations.