Open Access Case study

Evaluation of the Practice of Building Survey for Maintenance of Public Building in South-East Nigeria

Osuagwu Andrew Chima, Nkeleme Emmanuel Ifeanyichukwu, Amafili Tochukwu Nnamdi, Ike Goodluck Chukwuemeka, Nzeneri Oluchukwu Precious-favour

Journal of Engineering Research and Reports, Page 108-122
DOI: 10.9734/jerr/2021/v20i317288

The maintenance of public building is evasive without a conscious practice of  building surveying as it avails the maintenance personal insight  that informs the building maintenance this The research evaluates the practice of building \surveying in South-East Nigeria  and its impact in the maintenance of public buildings. It was pursuit through the use of a structured questionnaire. Public buildings within Abia, Enugu and Imo state of study were studied with the respondent drawn from the users and officials in charge of the maintenance of the building.  A total of 390 questionnaires were administered with 314 returned giving a response rate of 80.5%.  A random sampling technique was adopted and the data was analyzed using a computer based Software SPSS version 21. Result were presented using statistical tools Mean, Relative Importance Index (RII).The result revealed among others that there is  no significant development in the condition of public buildings in South East states. In addition, the problems associates with building maintenance have significantly affected the building conditions in the study area. Proactive and well planned maintenance are recommended as against corrective measure commonly used. Prompt replacement of nonfunctional, aged or malfunctioning building parts. Government should ensure that most of the public buildings have a maintenance policy and there is an effective communication between the maintenance department and the building occupants. Government should ensure that there is a condition survey for the public building adopting the approach of the framework developed in this study.

Open Access Short Research Article

Modeling of Leadframe Strip Warpage after Die Attach Cure Process

Jefferson Talledo

Journal of Engineering Research and Reports, Page 50-56
DOI: 10.9734/jerr/2021/v20i317281

In the leadframe package assembly process, silicon die is attached to the leadframe using a die attach adhesive material and the bonded strip is then cured. However, excessive strip warpage after the die attach cure process is a challenging problem that also affects the succeeding assembly processes. In this study, strip warpage modeling was done using a finite element analysis (FEA) technique to understand the warpage mechanism after die attach cure and find options to reduce strip warpage. The effect of changing the leadframe thickness, die thickness, and the leadframe design in terms of the number of strip panels or changing the connecting bar was analyzed. Modeling demonstrated that lead frame contracts faster than the silicon die resulting in the “frowning” warpage that agrees with the actual observation. It was also shown that increasing the die thickness by 25% results in 27% warpage reduction. Results also showed that increasing the number of panels or maps in a strip could significantly reduce the strip warpage. Improving the panel-to-panel isolation using stress relief cuts is also another option to reduce warpage after die attach cure.

Open Access Original Research Article

Augmented Leadframe Design for Stable Multi-Wire Ground Bonding

Frederick Ray I. Gomez, Alyssa Grace S. Gablan, Anthony R. Moreno, Nerie R. Gomez

Journal of Engineering Research and Reports, Page 1-5
DOI: 10.9734/jerr/2021/v20i317273

Technological change has brought the global market into broad industrialization and modernization. One major application in the semiconductor industry demands safety and high reliability with strict compliance requirement. This technical paper focuses on the package design solution of quad-flat no leads (QFN) to mitigate the leadframe bouncing and its consequent effect of lifted wire and/or non-stick on leads (NSOL) defects on multi-wire ground connection. Multi-wire on single lead ground (or simply Gnd) connection plays critical attribute in the test coverage risk assessment. Cases of missing wire and/or NSOL on the multi-wire Gnd connection cannot be detected at test resulting to Bin1 (good) instead of Bin5 (open) failure. To ease the failure modes mechanism, a new design of QFN leadframe package with lead-to-diepad bridge-type connection was conceptualized for device with extended leads and with multiple Gnd wires connection. The augmented design would provide better stability than the existing leadframe configurations during wirebonding. Ultimately, the design would help eliminate potential escapees at test of lifted Gnd wire not detected.

Open Access Original Research Article

Understanding Package Crack Signatures in a Leadframe Semiconductor Package

Jefferson Talledo

Journal of Engineering Research and Reports, Page 6-14
DOI: 10.9734/jerr/2021/v20i317274

This paper presents the simulation approach used to understand package crack signatures of a leadframe package under different mechanical loading scenarios. Package crack is one of the common problems with semiconductor packages. A better understanding of the different crack signatures would help identify the root cause quickly and be able to find the correct solution. In this study, a high precision materials testing system was used to apply mechanical loading to the package simulating different scenarios that could produce the crack. Based on the testing results, cracks have distinct signatures depending on how the force is applied. With the different signatures identified, this approach makes it easy to find the root cause of the crack in actual applications or assembly processes and resolve the problem faster.

Open Access Original Research Article

Glue Voids Reduction on QFN Device through Material and Process Improvement

Edwin M. Graycochea Jr., Endalicio D. Manalo, Rennier S. Rodriguez, Frederick Ray I. Gomez

Journal of Engineering Research and Reports, Page 15-19
DOI: 10.9734/jerr/2021/v20i317275

The paper is focused on the glue voids reduction on critical semiconductor quad-flat no-leads (QFN) device processed on a stencil printing type of die attach machine. Process optimization through material preparation improvement was done to mitigate the silver lumps of the sintering glue which is a main contributor on the voids occurrence. Eventually, the glue voids were reduced to less than the allowed 5% limit. For future works, the learnings and configuration could be used on devices with similar requirement.

Open Access Original Research Article

Mathematical Skills and the Academic Performance of Junior and Senior Electrical Engineering Students of the University of Eastern Philippines

Kenneth Bryan F. Abaigar, Benjamin D. Varela

Journal of Engineering Research and Reports, Page 20-31
DOI: 10.9734/jerr/2021/v20i317276

The study was conducted to determine the mathematical skills and the academic performance of the junior and senior electrical engineering students of the University of Eastern Philippines. Descriptive-correlational method of research was used with a total enumeration of the regular students from third year to fifth year electrical engineering students.



The findings revealed that male students dominated all the three year levels of the electrical engineering course. It was also found out that there were more regular fifth year engineering students than the third year and fourth year students. Meanwhile, the third year students got the highest average rating in the final grades of first year and second year mathematics and the lowest average rating belonged to the fifth year students. The learning style of the three-year levels was found to be visual while in terms of study habits, the third year students have very good study habit.

It was also found out that the level of mathematical skills of the three-year levels were low, but the level of academic performance of the three-year levels were found out to be good. Multiple regression analysis was used to determine the relationship of the student profile and their mathematical skills. The results showed that the average of final grades in all first-year mathematics, and the students’ year level have significant relationship with the mathematical skills of the students.

Meanwhile, the profile variables found to be significantly related to academic performance were the average of final grades in first year mathematics, average of final grades in second year mathematics and study habits of the students’ respondents.

Lastly, the mathematical skills had no significant relationship to the academic performance of the student-respondents.

Open Access Original Research Article

Die Crack Resolution through Pick-up Process Optimization for BGA Package

R. Rodriguez, E. Graycochea Jr., F. R. Gomez, E. Manalo

Journal of Engineering Research and Reports, Page 32-36
DOI: 10.9734/jerr/2021/v20i317277

With the new devices and new technologies in the semiconductor industry are getting more challenging to process because issues are unavoidable especially on thin dies. The paper is focused on the improvement done on a ball grid array (BGA) substrate package assembly to address the quantity of rejection of die crack during die picking at the die attach process station. High pick force and high needle top height found out during the pick-up process is the main root cause of die crack. Parameter optimization particularly for die picking with the combination of pick force and needle top height parameter was done to eliminate this type of issue after the die attaches process. With the die attach process improvement, a reduction of 100 percent of die crack occurrence was successfully achieved. For future works, the improvement and learnings could be used for devices with similar constraints.

Open Access Original Research Article

Modeling Study on the Solder Joint Reliability of a Leadframe Package under Powered Thermal Cycling

Jefferson Talledo

Journal of Engineering Research and Reports, Page 37-43
DOI: 10.9734/jerr/2021/v20i317279

This paper aims to present a thermo-mechanical modeling approach to predict the solder joint reliability of a leadframe-based package under powered thermal cycling (PTC) test from -40oC to 105oC. The study involves modeling the PTC condition as a standard thermal cycling with a modified temperature boundary to account for the temperature increase due to the applied power to the device package mounted on board. The temperature ramp and dwell times were maintained. Based on the finite element analysis (FEA) results and comparison with actual data, modeling a PTC as a modified thermal cycling process provides a good prediction of the solder joint life. The analysis is simpler and would be beneficial for getting quick assessments of new leadframe package designs.

Open Access Original Research Article

Establishing Robust Control for Epoxy Open Time

Michael D. Capili

Journal of Engineering Research and Reports, Page 44-49
DOI: 10.9734/jerr/2021/v20i317280

The Open time is called the time it takes for this chemical transition from liquid to solid. The epoxy moves into a gel state from the liquid state as it recovers, until it enters a solid-state. This article will address the development of a new, regulatory-compliant in die attach epoxy that establishes robust Epoxy Open Time control to improve the performance of product reliability with the following quality output response characteristic in Die Attach was consider; Epoxy Coverage, epoxy voids, Bond Line Thickness (BLT), and Die Shear Test (DST) strength response.

Open Access Original Research Article

Enhanced Wirebonding Technique on QFN Device with Critical Die Reference

Jonathan C. Pulido, Frederick Ray I. Gomez

Journal of Engineering Research and Reports, Page 57-61
DOI: 10.9734/jerr/2021/v20i317283

Wirebonding is one of the most challenging assembly manufacturing processes in semiconductor packaging industry. This paper discussed the wirebonding challenge and the solution to mitigate misplaced ball issues and prevent pattern recognition alignment errors. Parameter optimization particularly on wirebond looping was done to ensure that the silicon die’s L-fiducial is visible and not obstructed by the wires, which is the operator point or die reference of the unit during wirebonding setup. Ultimately, the optimized wirebonding parameter prevented the pattern recognition alignment error and misplaced ball issues during the lot process.  For future works, the configuration and technique could be applied on packages with the similar situation.

Open Access Original Research Article

Response Surface Optimization of Corn Husk Fiber Mercerization Using NaOH

Julius Mmelikam Chukwuemeka, Joseph Tagbo Nwabanne, Victor Ifeanyi Ugonabo

Journal of Engineering Research and Reports, Page 62-82
DOI: 10.9734/jerr/2021/v20i317284

The optimum mercerization parameters for treatment of corn husk using NaOH were analyzed by response surface methodology (RSM). The surface morphology and chemical structures of the raw and NaOH-treated fibers were studied using scanning electron microscopy (SEM), X-ray diffraction (XRD) and Fourier-transform infrared spectroscopy (FTIR) to validate the RSM results. The optimum chemical characteristics of corn husk treated with NaOH obtained when 100g of corn husk biomass was mercerized in 2.5Mol/dm3 NaOH for 8 days were: cellulose -70.51%, hemicellulose -8.99%, lignin -6.54, weight loss – 92.27%, ash content -10.11% and extractive -3.78%. The model summary statistics showed that quadratic model best fitted the optimization analysis. The ANOVA results showed that weight loss, hemicellulose, cellulose and lignin contents of corn husk biomass were affected by retting time, retting concentration and weight of biomass. Cellulose content of corn husk was observed to increase with increment in retting time and retting concentration while the reverse is the case for hemicellulose and lignin contents. The NaOH-treated corn husk has higher cellulose content than the untreated corn husk biomass while the reverse is the case for hemicellulose and lignin. SEM images showed that untreated corn husk biomass has irregular cross-section, non-uniform surface and some impurities while NaOH treated is finely packed together. XRD graphs showed that cellulose is the predominant content of the fiber. The FTIR results also indicated a variation of the peaks of the curves after treatment which favors an increase in the cellulose content.

Open Access Original Research Article

Investigation on Die Crack in a Stacked Die Package Using Finite Element Analysis

Jefferson Talledo

Journal of Engineering Research and Reports, Page 83-91
DOI: 10.9734/jerr/2021/v20i317285

Die crack is one of the problems in stacked die semiconductor packages. As silicon dies become thinner in such packages due to miniaturization requirement, the tendency to have die crack increases. This study presents the investigation done on a die crack issue in a stacked die package using finite element analysis (FEA). The die stress induced during the package assembly processes from die attach to package strip reflow was analyzed and compared with the actual die crack failure in terms of the location of maximum die stress at unit level as well as strip level. Stresses in the die due to coefficient of thermal expansion (CTE) mismatch of the package component materials and mechanical bending of the package in strip format were taken into consideration. Comparison of the die stress with actual die crack pointed to strip bending as the cause of the problem and not CTE mismatch. It was found that the die crack was not due to the thermal processes involved during package assembly. This study showed that analyzing die stress using FEA could help identify the root cause of a die crack problem during the stacked die package assembly and manufacturing as crack occurs at locations of maximum stress. The die crack mechanism can also be understood through FEA simulation and such understanding is very important in coming up with robust solution.

Open Access Original Research Article

Enhanced Die Attach Process Defect Recognition on QFN Leadframe Packages

Marque Ryan Salcedo, Alyssa Grace Gablan, Jerome Dinglasan, Frederick Ray Gomez

Journal of Engineering Research and Reports, Page 92-96
DOI: 10.9734/jerr/2021/v20i317286

Advanced packaging at the back-end semiconductor manufacturing characterizes various equipment capabilities per device requirement. High resolution imaging for inspection system during die attach process has gained its interest to feature automated selections during in-line processing. Increasing yet stringent requisites of today’s applications give us leading indicators of market’s demand at more functionality in a smaller and complex package. In light with the technology trend, vision inspection system is a well-known challenge. Instead of using a high magnification microscope off-line after assembly processing, leadframe inspection feature uses optical image-based system to recognize real-time feedback on lead-related defects. Such leadframe inspection activation provides good accuracy, monitoring process integrity in real-time for quad-flat no-leads (QFN) leadframe packages. This paper presents how leadframe inspection at die attach machine takes advantage of simultaneous detection of early die attach defect manifestations.

Open Access Original Research Article

Automotive Package Lead Pullback Elimination Using Monte Carlo Analysis for Determining Leadframe and Blade Design

Jefferson S. Talledo, Patricio A. Cabading Jr., Rogelio A. Real

Journal of Engineering Research and Reports, Page 97-107
DOI: 10.9734/jerr/2021/v20i317287

This study focuses on eliminating the lead pullback problem in an automotive quad flat no lead (QFN) package in order to meet the non-negotiable requirement to have a solder wettable or solderable lead sidewall. It involves using a non-traditional approach of Monte Carlo tolerance analysis to determine the final leadframe and singulation blade design solution. It was found out that the zero lead pullback could be achieved by reducing the leadframe lead to lead distance from 0.275 mm to 0.225 mm and increasing the blade thickness from 0.325 mm to 0.350 mm. Actual results from 10 line stressing lots all showed zero pullback validating the effectiveness of the final design and the use of Monte Carlo tolerance analysis technique. Costly investment for a lead pullback inspection system was avoided and the 100% manual inspection eliminated.

Open Access Original Research Article

Increasing Singulation Machine UPH through Characterization and Standardization of Saw and Handler Parameters through DMAIC Methodology

Lloyd L. Rolluqui, Patricio A. Cabading Jr, Jimmy P. Domingo

Journal of Engineering Research and Reports, Page 123-140
DOI: 10.9734/jerr/2021/v20i317289

This study aims to address the problem of machine saturation and low capacity at package singulation, caused by increasing product loading and new devices that requires frequent machine setups and conversions.

With this evaluation, the process and equipment engineering group collaborated to improve the machine unit per hour (UPH) of package singulation machines at the manufacturing assembly.  Target improvements were divided into three phases, so that the team could focus more on each phase and was able to define robust parameters without compromising the product quality.  DMAIC methodology was used to improve the productivity of package singulation machines. With the help of our methodology, we identified the root cause and contributing factors to the problem.

UPH improvements per machine were validated and assessed in terms of machine efficiency and product quality, because of characterization and standardization of every parameter in each phase of the project. The achieved total improvement was of 17.64%.