Near-Field UHF RFID Transponder with a Screen-Printed Graphene Antenna

As a method of producing RFID tags, printed graphene provides a low-cost and eco-friendly alternative to the etching of aluminum or copper. The high resistivity of graphene, however, sets a challenge for the antenna design. In practice, it has led to using very large antennas in the UHF RFID far field tags demonstrated before. Using inductive near field as the coupling method between the reader and the tag is an alternative to the radiating far field also at UHF. The read range of such a near field tag is very short, but, on the other hand, the tag is extremely simple and small. In this paper, near field UHF RFID transponders with screen-printed graphene antennas are presented and the effect of the dimensions of the tag and the attachment method of the microchip studied. The attachment of the microchip is an important step of the fabrication process of a tag that has its impact on the final cost of a tag. Of the tags demonstrated, even the smallest one with the outer dimensions of 21 mm * 18 mm and the chip attached with isotropic conductive adhesive (ICA) was readable from a distance of 10 mm with an RF power marginal of 19 dB, which demonstrates that an operational and small graphene-based UHF RFID tag can be fabricated with low-cost industrial processes.Comment: 8 pages, 9 figures. IEEE Transactions on Components, Packaging and Manufacturing Technology, 201

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

Flexible and stretchable electronics for wearable healthcare

Measuring the quality of human health and well-being is one of the key growth areas in our society. Preferably, these measurements are done as unobtrusive as possible. These sensoric devices are then to be integrated directly on the human body as a patch or integrated into garments. This requires the devices to be very thin, flexible and sometimes even stretchable. An overview will be given of recent technology developments in this domain and concrete application examples will be shown

Parasitic Effects Reduction for Wafer-Level Packaging of RF-Mems

In RF-MEMS packaging, next to the protection of movable structures, optimization of package electrical performance plays a very important role. In this work, a wafer-level packaging process has been investigated and optimized in order to minimize electrical parasitic effects. The RF-MEMS package concept used is based on a wafer-level bonding of a capping silicon substrate to an RF-MEMS wafer. The capping silicon substrate resistivity, substrate thickness and the geometry of through-substrate electrical interconnect vias have been optimized using finite-element electromagnetic simulations (Ansoft HFSS). Test structures for electrical characterization have been designed and after their fabrication, measurement results will be compared with simulations.Comment: Submitted on behalf of TIMA Editions (http://irevues.inist.fr/tima-editions

Active and passive component embedding into low-cost plastic substrates aimed at smart system applications

The technology development for a low-cost, roll-to-roll compatible chip embedding process is described in this paper. Target applications are intelligent labels and disposable sensor patches. Two generations of the technology are depicted. In the first version of the embedding technology, the chips are embedded in an adhesive layer between a copper foil and a PET film. While this results in a very thin (< 200 µm) and flexible system, the single-layer routing and the incompatibility with passive components restricts the application of this first generation. The double-sided circuitry embedding technology is an extension of the single-sided, foil-based chip embedding, where the PET film is replaced by a second metal foil. To obtain sufficient mechanical strength and to further reduce cost, the adhesive film is replaced by a substrate material which is compatible with the chip embedding concept. Both versions of the foil-based embedding technology are very versatile, as they are compatible with a broad range of polymer materials, for which the specifications can be tuned to the final application

Experimental and modelling studies of electronic packaging interconnections formed with lead-free materials

Both the experimental and the modelling techniques have been investigated and used to investigate factors that influence the formation, quality and reliability of electronic packaging interconnections formed using solder alloys and anisotropic conductive films (ACFs). The wetting behaviours of new lead-free solders (i.e. Sn-2.8Ag-0.5Cu-1.0Bi and Sn-0.7Cu-0.3Ni) have been evaluated using the wetting balance test. This assessment ahs been performed for three soldering temperatures with three different types of fluxes. The results have been compared with the conventional Sn-Pb, Sn-Ag-Cu and Sn-Cu solders. It has been found that the wettability of the lead-free solders is not as good as that of the Sn-Pb solder. The additions of Bi into the Sn-Ag-Cu solder and Ni into the Sn-Cu solder improve the wettability that is strongly dependent on the type of the flux and the soldering temperature. In general, NC-flux is suitable for Cu-substrate whereas Ws-flux is suitable for Ni substrate, but for the Sn-2.8Ag-0.5-Cu solder on Ni substrate, good wettability has been observed with both the NC and the R-type fluxes. Computational modelling of this test has revealed that the increase in the depth and the radius of the solder bath has little effect on the wetting force, but the meniscus height decreases when the bath radius exceeds 14 mm. Dissolution of solid metals into liquid solders has been investigated through experiments and computer modelling. Microstructural studies have been carried out and the growth behaviours of the intermetallic compounds (IMCs) during wetting, solidification and isothermal ageing have been investigated. It has been found that the addition of Bi into the Sn-Ag-Cu solder reduces the consumptions of the substrates and suppresses the growth of IMCs during wetting and ageing. Similarly, the addition of Ni into the Sn-Cu solder reduces both the consumptions of the substrates and the growth of IMCs during wetting and short term ageing but enhances the growth of IMCs during long term ageing. Experimental and computer modelling techniques have been used to measure the temperature in the ACF during bonding. The temperature in an ACF joint becomes very close to the required maximum bonding temperature within the first 1 s of bonding time. The impact of this temperature on the cure process and on the ACF physical properties such as loss modulus, storage modulus, and glass transition temperature has been investigated. It has been found that the higher the bonding temperature the more the curing degree of ACF is. Rapid changes occur in the physical properties of ACF at temperatures above the glass transition point. When the ACF is cured for a long time at a high temperature, the physical properties may degrade. The adhesion strength of ACF joint increases as the curing degree increases. However, when the ACF joint undergoes a thermal aging treatment, the adhesion strength increases for the samples bonded at lower temperatures, but decreases for the samples bonded at higher temperatures. The rate of increase in the contact resistance is dramatically higher for the samples bonded at lower temperatures than for those bonded at higher temperatures. Computer modelling of the isothermal ageing of ACF joint confirms that the thermal load causes the expansion of the adhesive matrix and generates high stresses on the conductive particle. This may result in the permanent damage of the outermost conductive metallic layers as well as electrical failure. The effect of external bending loads on the electrical reliability of ACF-based interconnection has also been studied through computer modelling. The analysis reveals that ACF thickness increases at the corners of the chip-ACF joint more than that of the middle position. This causes a gap between the chip and the substrate results in the failure of the electrical interconnections

Assembly of planar array components using anisotropic conducting adhesives: a benchmark study. Part I - experiment

This paper presents new results from an experimental and theoretical program to evaluate relevant process parameters in the assembly of a 500 m pitch area array component using anisotropic conductive adhesive (ACA) materials. This experimental configuration has features of micro ball grid array ( BGA), chip scale packaging (CSP), and also flip-chip and conventional ball grid array (BGA) package structures. A range of materials combinations have been evaluated, including (random filled) adhesive materials based on both thermoplastic and thermosetting resin systems, combined with both organic and thick-film on ceramic substrate materials. The ACA’s used have all been applied as films, and hence are also known as anisotropic conducting films (ACF). The test assemblies have been constructed using a specially developed instrumented assembly system which allows the measurement of the process temperatures and pressures and the consequent bondline thickness reduction and conductivity development. The effects of the process parameters on the resulting properties, particularly conductivity and yield, are reported. A complementary paper [1] indicates the results of computational fluid dynamics (CFD) models of the early stages of the assembly process which allow the extrapolation of the present results to finer pitch geometries

Electrical conduction characteristics of solid metal anisotropic conductive adhesive particles

Anisotropic Conductive Adhesives (ACAs) have been used in fine pitch electronics packaging for over a decade and provide a high density and low temperature bonding method in a range of niche applications. In an ACA assembly, individual particles act as electrical conductors, providing current paths for fine pitch electronics interconnections. This paper presents a model of the electrical conduction characteristics of the solid metal particles used in some ACAs. Conduction through such ACA particles results from contact between the component and substrate pads and the particle, which is deformed by the assembly process. In order to investigate the effect of the extent of particle deformation, or transformation degree, upon the particle resistance, the particle transformation factor is defined. A mathematical model of the electrical resistance of an ACA particle, which is an integral function of the transformation factor and the particle geomehy, has been developed from a physical model of the ACA particle. MuthCAD software has been used to provide solutions for this function. According to these numerical solutions, the greater the particle transformation, the lower the particle resistance will be. In conclusion, it is shown that the ACA particle resistance is determined by the particle transformation and the particle geometries. Finally, the resistance function will explain the conductive mechanism of a deformed metal ACA particle