Developing the knowledge-based human resources that support the implementation of the National Dual Training System (NDTS): evaluation of TVET teacher's competency at MARA Training Institutions

Development in the world of technical and vocational education and training (TVET) on an ongoing basis is a challenge to the profession of the TVET-teachers to maintain their performance. The ability of teachers to identify the competencies required by their profession is very critical to enable them to make improvements in teaching and learning. For a broader perspective the competency needs of the labour market have to be matched by those developed within the vocational learning processes. Consequently, this study has focused on developing and validating the new empirical based TVET-teacher competency profile and evaluating teacher’s competency. This study combines both quantitative and qualitative research methodology that was designed to answer all the research questions. The new empirical based competency profile development and TVET-teacher evaluation was based upon an instructional design model. In addition, a modified Delphi technique has also been adopted throughout the process. Initially, 98 elements of competencies were listed by expert panel and rated by TVET institutions as important. Then, analysis using manual and statistical procedure found that 112 elements of competencies have emerged from seventeen (17) clusters of competencies. Prior to that, using the preliminary TVET-teacher competency profile, the level of TVETteacher competencies was found to be Proficient and the finding of 112 elements of competencies with 17 clusters was finally used to develop the new empirical based competency profile for MARA TVET-teacher. Mean score analysis of teacher competencies found that there were gaps in teacher competencies between MARA institutions (IKM) and other TVET institutions, where MARA-teacher was significantly better than other TVET teacher. ANOVA and t-test analysis showed that there were significant differences between teacher competencies among all TVET institutions in Malaysia. On the other hand, the study showed that teacher’s age, grade and year of experience are not significant predictors for TVET-teacher competency. In the context of mastering the competency, the study also found that three competencies are classified as most difficult or challenging, twelve competencies are classified as should be improved, and eight competencies are classified as needed to be trained. Lastly, to make NDTS implementation a reality for MARA the new empirical based competency profile and the framework for career development and training pathway were established. This Framework would serve as a significant tool to develop the knowledge based human resources needed. This will ensure that TVET-teachers at MARA are trained to be knowledgeable, competent, and professional and become a pedagogical leader on an ongoing basis towards a world class TVET-education system

The Threat of Plant Toxins and Bioterrorism: A Review

The intentional use of highly pathogenic microorganisms, such as bacteria, viruses or their toxins, to spread mass-scale diseases that destabilize populations (with motivations of religious or ideological belief, monetary implications, or political decisions) is defined as bioterrorism. Although the success of a bioterrorism attack is not very realistic due to technical constraints, it is not unlikely and the threat of such an attack is higher than ever before. It is now a fact that the capability to create panic has allured terrorists for the use of biological agents (BAs) to cause terror attacks. In the era of biotechnology and nanotechnology, accessibility in terms of price and availability has spread fast, with new sophisticated BAs often being produced and used. Moreover, there are some BAs that are becoming increasingly important, such as toxins produced by bacteria (e.g., Botulinum toxin, BTX), or Enterotoxyn type B, also known as Staphylococcal Enterotoxin B (SEB)) and extractions from plants. The most increasing records are with regards to the extraction / production of ricin, abrin, modeccin, viscumin and volkensin, which are the most lethal plant toxins known to humans, even in low amounts. Moreover, ricin was also developed as an aerosol biological warfare agent (BWA) by the US and its allies during World War II, but was never used. Nowadays, there are increasing records that show how easy it can be to extract plant toxins and transform them into biological weapon agents (BWAs), regardless of the scale of the group of individuals

Bonding strength of multiple SiC die attachment prepared by sintering of Ag nanoparticles

3 mm × 3 mm dummy SiC dies with 100\200\200 nm thick Ti\W\Au metallization have simultaneously been attached using sintering of Ag nanoparticle paste on AlN-based direct bonded copper substrates with 5\0.1 μm thick NiP\Au finish. The effect of preparation and sintering parameters including time of drying the printed paste, sintering temperature and time, and pressure, on the average shear strength for multiple die attachments was investigated. The surfaces of the die attachments after the shear tests were observed and the individual shear strength values correlated with the “apparent” porosity and thicknesses of the corresponding die attachments (sintered layer). The results obtained are further discussed and compared with typical data reported in existing literature. Main conclusions include: (i) the present shear strength values and their variations are comparable with those reported for single die attachment samples, (ii) the effects of sintering parameters can be ascribed to the effectiveness of the organic content burnout and appropriate rate of growth and coalescence of the Ag nanoparticles during the sintering process, and (iii) thickness values of the sintered Ag die attachments may be taken as non-destructive measurements to monitor/evaluate the quality of die attachment during power electronic module manufacturing/assembly process

Characterization of Multifunctional Nanomaterials for Electronics Thermal Management and Sintering Applications

The science of manipulating materials at their nanoscale level is nowadays allowing endless possibilities to disrupt the current limitations on the conventional production processes and products. In electronics, the need for more capable thermal management strategies led to the exploration of advanced approaches and focus on new materials and allowed to push further the thermal dissipation capabilities of each generation of products. In this thesis, we investigate different thermal management concepts and propose new solutions based on carbon and metallic nanomaterials, while we explore the possibility to combine the size effect with the composition effect of the nanoscale materials.Due to their high surface to volume ratio, nanoscale particles show different thermodynamics properties that led to their potential implementation in electronics fabrication processes. More specifically, silver nanoparticles (Ag NPs) have been under focus in recent years for applications to replace lead-free solder and contribute to energy saving. Due to a poor trade-off between the process parameters, the production costs, and the reliability of the silver related application, different strategies are being suggested to optimize its applications. In this present study, we investigate multiple sintering parameters of Ag NPs and use the nanoscale effect in a hybrid approach for the sintering of microscopic powder. The results of the sintering parameters are correlated to the density of the samples and their properties in terms of thermal and electrical conductivity. While the sintering of Ag NPs occurs at low temperatures and allows to obtain relatively high densities, the thermal and electrical properties are still limited and the increase in the temperature and fraction of the NPs higher than 400 degrees and 2wt.% has a much- pronounced effect to improve the physical properties of the samples.The sintering of Ag NPs was also explored in this thesis to propose a novel approach to use graphene foam as a heat sink. While graphene is known for its outstanding physical, chemical, and mechanical properties, its integration as a practical solution in electronics is still missing. The use of Ag NPs in this work allowed to successfully attach the 3D graphene foam on its substrate and further improve both its mechanical and thermal properties by coating the graphene with Ag NPs. Also, the integration of Ag NPs as a die-attach for the 3D porous structure allowed its further use as a container for Phase Change Materials (PCM). Different amounts of PCM were introduced in the lightweight foam and the junction temperature of the hot spot was correlated to the power and the presence of the PCM. We found that graphene foam presents a real advantage for its use in thermal dissipation strategies.2D graphene material is developed herein as a coating for micro-and nanoscale particles. Using Chemical Vapor Deposition (CVD) and Arc Discharge (AD) methods, we introduce the possibility to produce graphene coating on copper particles for application in thermal management. In addition, we explore the possibility to introduce a doping effect on the coated NPs to further study its effect on the thermal performances of NPs. The morphology and the composition of the coating were investigated and correlated with the bottom-up production process of CVD and AD. The thermal conductivity and chemical stability of the produced particles were studied for their use as fillers in thermally conductive pastes and additives water-based nanofluids. The thermal properties of the different systems were linked to the fraction of the additives and nanofillers. The graphene-coated particles were found to have a multifunctional effect. In both micro-and nanoscale particles, the graphene coating was found to act as a corrosion resistance that stabilizes the metallic core of the particles. The graphene coating also was found to act as a carbon source to reduce the microparticles in a bimodal powder at high temperatures. Finally, the encapsulation of the nanoscale powder allowed to observe a melting point depression related to the composition of the core of the nanoparticles and their nanoscale size.In an effort to combine the size effect of the nanoparticles and their compositions, different alloyed nanoparticles were produced using AC. The morphology, the composition, and their sintering properties were compared to highlight their composition effect. The produced nanopowders were also used as a sintering aid in the spark plasma sintering approach (SPS) and the results show a positive contribution of the nanopowders in the reduction of the sintering temperature and the densification of the samples. An additional effect is also reported and arises from the possibility to use those particles to fine-tune the chemical composition of the bimodal particles

Power Module Packaging in Automotive Applications

In this study, nano silver paste was used as die attach material with the aim of increasing reliability of joints in power modules in automotive applications. Prior to joining, nano silver paste was spread on the interface between silver coated copper substrates and dummy chips by screen printing method. 5 groups of samples were produced using three different joining techniques based on different combinations of ultrasonic force and persistent pressure in air and vacuum atmospheres. The bonding quality of the interface region was evaluated by microstructural examination and quasi-static shear tests. On the other hand, electrical properties of sintered nano silver particles within the joints were characterized through resistivity measurements. Sintered nano silver regions in all samples exhibited two types of porosity, namely, macro and micro porosity. Macro pores formed during the evaporation and removal of organics present in the starting paste, while micro pores were left in the structure because of insufficient sintering of silver nano powders. Although the sintered silver interface in samples produced using 5 MPa persistent pressure in air displayed a minimum amount of porosity, pores as large as 5 m in diameter were observed in joints produced in air by a preload of 0.01 MPa with or without ultrasonic force. In addition, vacuum sintering yielded relatively porous interfaces compared to samples manufactured in air even though the same compaction pressure was applied during sintering. Accordingly, in the samples produced either in air by the application of low preloads of 0.01 MPa or in vacuum at 5MPa, additional microcracks were formed, particularly in the interface region between silver coating and sintered nano silver particles. Stress-strain curves of the joints exhibited linear elastic, small strain hardening and fracture regions similar to wrought alloys. The strengths of the joints increased proportionally to the degree of sintering as expected. The shear strength reached to 32 MPa in samples sintered in air at 5 MPa constant pressure, whereas shear strength decreased to 4 MPa in highly porous joints produced by ultrasonic force and preloading with 0.01 MPa. All samples revealed shear-type dimples in the direction of mechanical testing indicating ductile behavior of joints. The electrical resistivity of the sintered nano silver layer showed the same trend as the mechanical properties. The weakest or most porous joint had the highest electrical resistivity of approximately 125.5 μΩ-cm). On the other hand, the least porous silver joint, manufactured at 5 MPa constant pressure in air exhibited the lowest electrical resistivity (7.8 μΩ-cm); however, it was five times higher than that of bulk silver. The results have presented that the nano silver paste is the most promising die attach material to replace conventional solder and conductive epoxies

過度液相焼結法によるパワーモジュールと銅ヒートスプレッダの低温及び低圧力接合

早大学位記番号:新7685早稲田大

ISPET: Interface Sintering Process Enhanced Technology

The research presented in this thesis was carried out in VISHAY Semiconductor Italiana S.P.A. at Borgaro Torinese - Italy. The framework of this thesis is the study of new materials for power electronics application, analysing their thermal, mechanical and electrical properties. Emerging application of high power systems requires new methods for power electronics integration and packaging. Stringent requirements in size and weight, reliability, durability, ambient and operation temperatures are pushing to go beyond the limits in industrial applications. As a consequence, our studies are focused on power modules, incorporating new materials and technology processes (sintering) for dies or chips (silicon), substrates and interconnection materials (wire bonding). This thesis work starts introducing the power semiconductor devices used in power electronics and their integration on Power Integrated Circuits (low and medium power density) and Power Modules (medium, high and very high power density). This chapter will explain technology evolution, power semiconductor device utilization mode and some applications. Chapter 2 will be focused on power modules packages. They have an important role for providing cooling, electrical connection and correct insulation, between the internal semiconductor devices and the external circuit. Isolated and non isolated packages are analysed and compared. Chapter 3 will make a point on the methods of thermal characterization and reliability tests, that were implemented to evaluate the impact of the introduction of new materials and processes into the device. In chapter 4, first experimental results, related to the sintering process will be discussed. In this chapter the attention will be focused on the Chip to substrate Joint of the device, analysing methods to mechanically fix die to substrate. The sintering process will be treated, analysing the process and the results will be thermally and mechanically characterized. The chapter 5 will present the experimental part oriented to the combinations of materials to produce a better heavy wire bonding, supported by a Design of Experiments (DOE). The behaviour of didifferent wires will be compared through thermal characterization methods and reliability test

Evaluation of high temperature reliability of SiC die attached structure with sinter micron-size Ag particles paste on Ni-P/Pd/Au plated substrates

C. Chen, Z. Zhang and K. Suganuma, "Evaluation of high temperature reliability of SiC die attached structure with sinter micron-size Ag particles paste on Ni-P/Pd/Au plated substrates," 2020 IEEE 8th Electronics System-Integration Technology Conference (ESTC), Tønsberg, Vestfold, Norway, 2020, pp. 1-5, doi: 10.1109/ESTC48849.2020.9229850

Design and Implementation of Solder Paste Dispenser Based on Linear Drive System

In the technology to create prototypes for electronic hardware is usually constructed using surface mount device printed circuit board (SMD PCB). In this paper introduces the design and implementation of low-cost electrical solder paste dispenser that supports the PCB solder process. The design consists of a nozzle and linear drive systems based on stepper motors operating with electric power to push the plunger down to drop the solder paste on the board. To test the performance of solder paste that has been designed verified by experiment. Solder paste dispenser design was tested using SMD resistor with the solder pads of different sizes for R0603, R0805, and R1206 on PCB. The results showed that the design of the prototype was able to put the pasta in various field pads between 0.54 mm2, 0.91 mm2 and 1.44 mm2 for standard solder pads with an error in the 2% - 5%. Based on the results, the device has been shown to potentially be used to attach electronic components to printed circuit boards