Solderless assembly for electronics is a subject approached ever since RoHS EU Directive enforced lead-free technology especially since this one has revealed its limits. Electrically Conductive Adhesives (ECA) actually with a large... more
Solderless assembly for electronics is a subject approached ever since RoHS EU Directive enforced lead-free technology especially since this one has revealed its limits. Electrically Conductive Adhesives (ECA) actually with a large commercial offer but not very well characterized, became one of the alternatives to lead-free. The paper presents ECA qualification methods from mechanical and electrical properties point of view for usage as promising solution to build the electronic module, optimum on Surface Mount Technology processes or in the Occam concept using an additive process for interconnection structure. For a complete information about the bonds mechanical failure and their electrical resistance, shear tests, respectively four point electrical measurements were performed.
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Although only at the stage of proof of concept, a basic approach in Occam technology is: placement of components on a dielectric substrate, encapsulation, reversal of the substrate, drilling down to pins of components, creation of... more
Although only at the stage of proof of concept, a basic approach in Occam technology is: placement of components on a dielectric substrate, encapsulation, reversal of the substrate, drilling down to pins of components, creation of conductive traces, a.s.o. Since a reversed order of construction of a simple circuit is considered to be much cheaper in terms of required equipment, this paper presents some preliminary tests regarding conductive traces issues. As new materials [1] and new technologies [2, 3] are emerging on the market, a new conductive paste proposed to interconnect layers of a multi-layer printed circuit board through filled vias [4] was used to create traces. Printing of conductive paste and electrical measurements at the pin and trace interface were investigated.
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Side-channel attacks (SCA) have become more and more popular among hackers all over the world because they can provide access to sensitive information stored in a circuit, only by exploring physical data leakages. The most well-known... more
Side-channel attacks (SCA) have become more and more popular among hackers all over the world because they can provide access to sensitive information stored in a circuit, only by exploring physical data leakages. The most well-known SCA's are based on power consumption (e.g. Differential/Simple Power Analysis), electromagnetic radiations (e.g. Differential/Simple Electromagnetic Analysis), analyze of consumed time while performing cryptographic operations and inducing of faults (e.g. Optical Faults). Both power and electromagnetic analysis require acquiring a large number of traces by using specialized equipment. The problem appears when the environmental conditions are rough and the captured traces are noisy, making it hard to extract the signal from the noise. In this paper we focus on finding an optimal mechanism to denoise the signals captured from the electromagnetic radiations emitted by a microcontroller. In order to do so, Wavelet functions were used and results were compared depending on the threshold's levels and methods that were applied. Wavelet functions are a comprehensive tool with applications like signal denoising and data compression. All the obtained results are presented in this paper and conclusions regarding this process are drawn.
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Tamper detection circuits provide the first and most important defensive wall in protecting electronic modules containing security data. A widely used procedure is to cover the entire module with a foil containing fine conductive mesh,... more
Tamper detection circuits provide the first and most important defensive wall in protecting electronic modules containing security data. A widely used procedure is to cover the entire module with a foil containing fine conductive mesh, which detects intrusion attempts. Detection circuits are further classified as passive or active. Passive circuits have the advantage of low power consumption, however they are unable to detect small variations in the conductive mesh parameters. Since modern tools provide an upper leverage over the passive method, the most efficient way to protect security modules is thus to use active circuits. The active tamper detection circuits are typically probing the conductive mesh with short pulses, analyzing its response in terms of delay and shape. The method proposed in this paper generates short pulses at one end of the mesh and analyzes the response at the other end. Apart from measuring pulse delay, the analysis includes a frequency domain characterization of the system, determining whether there has been an intrusion or not, by comparing it to a reference (un-tampered with) spectrum. The novelty of this design is the combined analysis, in time and frequency domains, of the small variations in mesh characteristic parameters.
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Random numbers represent one of the most sensible part of a cryptographic system, since the cryptographic keys must be entirely based on them. The security of a communication relies on the key that had been established between two users.... more
Random numbers represent one of the most sensible part of a cryptographic system, since the cryptographic keys must be entirely based on them. The security of a communication relies on the key that had been established between two users. If an attacker is able to deduce that key, the communication is compromised. This is why key generation must completely rely on random number generators, so that nobody can deduce the. This paper will describe a set of public and free Random Number Generators (RNG) within Android-based Smartphones by exploiting different sensors, along with the way of achieving this scope. Moreover, this paper will present some conclusive tests and results over them.
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The main purpose of SIMREM project (Integrated System for the Management of the Material Resources) is to setup a new and complex integrated software system for management of university material resources, putting emphasis on purchasing... more
The main purpose of SIMREM project (Integrated System for the Management of the Material Resources) is to setup a new and complex integrated software system for management of university material resources, putting emphasis on purchasing correlated to organization's approved budget. The system has to be designed and developed for using also by any other public institution or private company. In these respects, a software application was developed as platform independent (Windows, Linux etc.), for relational databases (Oracle, Microsoft SQL Server etc.) using the newest WEB technologies (J2EE/JEE), JDBC, Hibernate and JasperReports, which are sustained by ORACLE and by the Open Source Java community. The innovative development technology enables access to system from anywhere, either Intranet or Internet, using only a regular internet browser (e. g. Internet Explorer). Besides ease-of-use for end users, this unique and remarkable feature significantly reduces system costs (acquisi...
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The system is able to identify a vehicle according to the license plate and the model of the car and it decides if the vehicle has or not has access in a limited access area. The access of the vehicle in this area is made by a barrier... more
The system is able to identify a vehicle according to the license plate and the model of the car and it decides if the vehicle has or not has access in a limited access area. The access of the vehicle in this area is made by a barrier actuated by a servomotor. If the vehicle information exists in the implemented database, a green LED will light for indicate that the vehicle has access in the area and the barrier will be raised. If the vehicle is not in database, a red LED will light and the position of the barrier will not change.
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The paper presents the investigation of composite structures made by overlapping two or more layers of resins, including conductive resins, at different time intervals, as well as different temperatures. This situation occurs in the case... more
The paper presents the investigation of composite structures made by overlapping two or more layers of resins, including conductive resins, at different time intervals, as well as different temperatures. This situation occurs in the case of a model of implementing an innovative concept of manufacturing electronic modules without using solder alloy, the Occam process. According to this approach, the interconnection structure is arranged on several layers with conductive paths separated from each other by dielectric layers. It is interesting to characterize the interface between layers to determine the possible effect on the reliability of the module. Samples of at least two layers of three types of resins were investigated using Scanning Electron Microscopy/Energy Dispersive X-Ray Spectroscopy analyses. These analyses emphasized there is no chemical bonding at the interface between the layers of resins, but only mechanical. This is a major disadvantage that can lead to the dismantling of the assembly under the action of mechanical forces and environment conditions.
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Planar transformers in DC-to-DC converters are attractive due to compactness at high power applications. Usually, converters work in the sub-MHz range and naturally the questions of losses both in-core and in-winding appears. The present... more
Planar transformers in DC-to-DC converters are attractive due to compactness at high power applications. Usually, converters work in the sub-MHz range and naturally the questions of losses both in-core and in-winding appears. The present work provides a comparative analysis of winding losses in two types of planar transformer PCB stack structure. The study aims to analyze the influence of winding arrangement on a step-up planar transformer over the leakage inductance based on the magneto motive force. The results show the impact of losses on the full converter in two FR4 structure embodiments: one with the secondary on a single inner layer and the second with the winding in multiple layers. For this approach a planar core transformer was modeled for sub-MHz range (0.4–1.0 MHz) analysis.
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This paper presents how to design and setup a Simple Power Analysis (SPA) attack and a Differential Power Analysis (DPA) attack on a smartcard and on a 32 bit microcontroller. SPA and DPA are power analysis attacks developed by Paul... more
This paper presents how to design and setup a Simple Power Analysis (SPA) attack and a Differential Power Analysis (DPA) attack on a smartcard and on a 32 bit microcontroller. SPA and DPA are power analysis attacks developed by Paul Kocher, Joshua Jaffe, and Benjamin Jun in 1995. These are non-invasive techniques which allow us to observe electrical patterns of different types of cryptographic algorithms, only by measuring the power consumption of the cryptographic devices. This paper presents the results obtained by measuring the power consumption of a secure smartcard and a 32 bit microcontroller programmed with the tiny AES128 implementation and introduces the mathematical knowledge needed to extract the encryption keys based only on measurements. Using the DPA correlation coefficients algorithm, implemented in Matlab, we were able to extract the AES128 encryption key from captured power consumption traces. To obtain the measurements, an USB Scope was used. The interface to the smartcard was made using a Java platform to connect to the card reader.
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Super-capacitors are highly reliable devices, outlasting any existing battery in operating conditions, cycle number and ruggedness. They are perfect candidates for energy storage in remote wireless sensor network nodes. Other applications... more
Super-capacitors are highly reliable devices, outlasting any existing battery in operating conditions, cycle number and ruggedness. They are perfect candidates for energy storage in remote wireless sensor network nodes. Other applications [1] use a combination of rechargeable battery as the main storage device and a low capacity EDLC as energy buffer. This paper describes the design and the results from a module consisting of a single large capacitor, a MPPC charger and a boost converter. Unlike other devices, this prototype uses one storage device (a single EDLC), it does not involve software components [2] and it can operate from a single solar cell.
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Research Interests: Engineering, Power Electronics, Electromagnetic Compatibility, Experience Design, Modeling and Simulation, and 11 moreNew Product Development, Power Semiconductor Devices, Power Control, Design Methodology, Electromagnetic Field, Electromagnetics applications, Point of View, Modelling and EMC Compatibility, New Products, Simulation Software, and Electromagnetic Simulation
Abstract All types of passive components present variations of most parameters as function of the operating temperature. Depending on the component type and thermal management, in a specific application, these parameter variations can... more
Abstract All types of passive components present variations of most parameters as function of the operating temperature. Depending on the component type and thermal management, in a specific application, these parameter variations can sometimes exceed 20% over the ...
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Research Interests: Engineering, Computer Science, Artificial Intelligence, Computer Vision, Image Processing, and 15 moreData Mining, Autonomous Robotics, Optical Imaging, GPS, Cross Correlation, Navigation, Calibration, ROBOT, Data acquisition, Accelerometers, Sensor Fusion, Shape, Inclinometer, Image Sensors, and Odometer
The assembling of the electronic components on PCBs becomes a key issue in electronic packaging reliability. The solder joints resulting from the soldering process represent an important outcome for the PCB assembling. Moreover, the... more
The assembling of the electronic components on PCBs becomes a key issue in electronic packaging reliability. The solder joints resulting from the soldering process represent an important outcome for the PCB assembling. Moreover, the Lead-Free soldering requests, imposed by the RoHS Directive, can cause difficulties in obtaining a high quality/reliable soldering process. Considering the reliability of electronic modules as expression of solder joints functionality, could be emphasized the lack of tests over solder joints functionality on assembling line. Usually are realized optical inspections and, in precise situation, X-Ray analysis are done over assembled PCBs being followed by “in circuit” electrical functional tests. The defects type “hide” or “cold/dry joints” could be not found. In the paper are presented the results of the functional tests of solder joints realized in two soldering technology, infrared-convection and vapor phase. Regarding to thermal functionality, infrared analysis of temperature distribution on the surface of a populated PCBs using thermovision were done. A correlation among functionality, reliability and thermovision functional analysis will be realized based on the experiments results. In consequence, the authors emphasize thermovision as available in circuit indirect test method for “hide” defects of solder joints.
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Education 4.0 is being empowered more and more by artificial intelligence (AI) methods. We observe a continuously growing demand for adaptive and personalized Education. In this paper we present an innovative approach to promoting AI in... more
Education 4.0 is being empowered more and more by artificial intelligence (AI) methods. We observe a continuously growing demand for adaptive and personalized Education. In this paper we present an innovative approach to promoting AI in Education 4.0. Our first contribution is AI assisted Higher Education Process with smart sensors and wearable devices for self-regulated learning. Secondly we describe our first results of Education 4.0 didactic methods implemented with learning analytics and machine learning algorithms. The aim of this case study is to predict the final score of students before participating in final examination. We propose an Early Recognition System equipped with real data captured in a blended learning course with a personalized test at the beginning of the semester, an adaptive learning environment based on Auto Tutor by N. A. Crowder theory with adaptive self-assessment feedback. It is obvious that focusing on students' success and their experiences is a win-win scenario for students and professors as well as for the administration.
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The actual generations of integrated circuits are characterized, inter alia, by very high frequencies or very high speeds. The dramatic evolution ofthe semiconductor's technology establishes a greater “pressure” to the design and the... more
The actual generations of integrated circuits are characterized, inter alia, by very high frequencies or very high speeds. The dramatic evolution ofthe semiconductor's technology establishes a greater “pressure” to the design and the manufacturing of the passive interconnection structure from PCB/MCM electronic modules. In these conditions the reference planes (power and ground planes) have a more and more important contribution. The paper intents to present the effect of different configuration reference planes on the characteristics of the high speed/high frequency interconnection lines. The first part deals with modeling and simulation of usual practical interconnection geometries. A computer modeling of meshed structures was realized and Spice models for a good compatibility with circuit simulators were obtained.S-,Y-,Z- parameters and radiation patterns were calculated, too. The second part contains measurements made by a vector network analyzer as regards to different prac...
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Reţeaua informatică dezvoltată în cadrul proiectului IN-TECH-TRANSFER vine în sprijinul exploatării oportunităţilor existente pe piaţă în ceea ce priveşte inovarea şi transferul tehnologic. Pentru ca transferul tehnologic să fie încununat... more
Reţeaua informatică dezvoltată în cadrul proiectului IN-TECH-TRANSFER vine în sprijinul exploatării oportunităţilor existente pe piaţă în ceea ce priveşte inovarea şi transferul tehnologic. Pentru ca transferul tehnologic să fie încununat de succes trebuie să aibă ca ţintă nevoia de satisfacere a pieţei cu produse, tehnologii şi servicii. În sprijinul acestei idei a fost creat un sistem informatic care să poată fi accesat cu uşurinţă de potenţialii utilizatori ai rezultatelor cercetării-dezvoltării. The information network developed through the IN-TECH-TRANSFER project is aimed to support the best exploitation of existing market opportunities, as far as innovation and technological transfer are concerned. For a successful technological transfer, the final goal should be market supply of products, technologies and services. To support this idea, an information system easily accessible to potential users of R&D results was created.
Acest proiect îşi propune realizarea unui robot autonom capabil să se deplaseze pe un traseu cu minim de informaţii apriori. Informaţia necesară parcurgerii traseului dorit se va achiziţionar în timpul deplasării folosind un ansamblu... more
Acest proiect îşi propune realizarea unui robot autonom capabil să se deplaseze pe un traseu cu minim de informaţii apriori. Informaţia necesară parcurgerii traseului dorit se va achiziţionar în timpul deplasării folosind un ansamblu elaborat de senzori. Acest ansamblul de senzori a fost conceput și testat de autori. Acest sistem de navigaţie este compus în principal de două module: modulul inerţial şi cel de vedere stereo optică. The project aim is to build an autonomous robot able to move on a track with minimum of priory knowledge. The information required to complete the route will be acquired during the trip by using an elaborated sensors system. This sensor system was developed and tested by the authors. The navigation system is mainly made out of two subsystems: the inertial navigation system and the stereo optic vision system
Includerea senzorilor rezistivi în designul dispozitivelor electronice organice este necesară pentru a extinde domeniul aplicaţiilor posibile. Pentru aceasta este necesară identificarea materialelor rezistive, a proceselor şi metodelor de... more
Includerea senzorilor rezistivi în designul dispozitivelor electronice organice este necesară pentru a extinde domeniul aplicaţiilor posibile. Pentru aceasta este necesară identificarea materialelor rezistive, a proceselor şi metodelor de structurare, precum şi analiza proprietăţilor rezistive pe substrat flexibil ale acestora. Două materiale cu aplicaţie largă în electronica organică sunt polimerii umpluţi cu carbon (carbon filled polymer, CFP) şi polimerii cu conducţie intrinsecă (ICP, poly (3, 4-ethylendioxythiophene) doped with polystyrene sulfonate acid, PEDOT:PSS). Lucrarea are ca scop prezentarea comportării acestor polimeri conductivi pe suport flexibil sub influenţa curentului continuu şi în impulsuri, subliniind variaţiile rezultate ale proprietăţilor rezistive. Lucrarea este prezentată în două părţi, prima parte analizează comportarea polimerilor umpluţi cu carbon iar partea a doua pune accentul pe polimerii cu conducţie intrinsecă. There is a necessity to include sensors...
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The present paper represents a study of a hybrid electric system that uses a battery of electrochemical double-layer capacitors (EDLC), a conventional lead-acid battery and a proprietary electronic system, designed to obtain minimum... more
The present paper represents a study of a hybrid electric system that uses a battery of electrochemical double-layer capacitors (EDLC), a conventional lead-acid battery and a proprietary electronic system, designed to obtain minimum electromagnetical disturbances, with uses in automotive applications. The electronic control module offers the possibility of programming the control method of the distribution of electricity in the hybrid system. Electromagnetic compatibility assessments of the electronic were also performed according to CISPR 22 standard and the results are compared with the limits specified by the standard. Electrical tests performed on both charge / discharge cycles of the battery of supercapacitors and in combination with a reversible electric motor highlights the benefits of using EDLC in automotive applications.
Includerea senzorilor rezistivi în designul dispozitivelor electronice organice este necesară pentru a extinde domeniul aplicaţiilor posibile. Pentru aceasta este necesară identificarea materialelor rezistive, a proceselor şi metodelor de... more
Includerea senzorilor rezistivi în designul dispozitivelor electronice organice este necesară pentru a extinde domeniul aplicaţiilor posibile. Pentru aceasta este necesară identificarea materialelor rezistive, a proceselor şi metodelor de structurare, precum şi analiza proprietăţilor rezistive pe substrat flexibil ale acestora. Două materiale cu aplicaţie largă în electronica organică sunt polimerii umpluţi cu carbon (carbon filled polymer, CFP) şi polimerii cu conducţie intrinsecă (ICP, poly (3, 4-ethylendioxythiophene) doped with polystyrene sulfonate acid, PEDOT:PSS). Lucrarea are ca scop prezentarea comportării acestor polimeri conductivi pe suport flexibil sub influenţa curentului continuu şi în impulsuri, subliniind variaţiile rezultate ale proprietăţilor rezistive. Lucrarea este prezentată în două părţi, prima parte analizează comportarea polimerilor umpluţi cu carbon iar partea a doua pune accentul pe polimerii cu conducţie intrinsecă. There is a necessity to include sensors...
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The laboratory platform developed and presented in this paper is destined to teach and train the under-graduate students on the importance of post-layout analysis in advanced PCB/HDI design. The electronic project consists in a digital... more
The laboratory platform developed and presented in this paper is destined to teach and train the under-graduate students on the importance of post-layout analysis in advanced PCB/HDI design. The electronic project consists in a digital high speed pseudo-random generator, designed with high-speed logic families and operating at 50 MHz. Two (of four) modules of the platform, one non-optimized (“wrongly”) created
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This paper describes the motivation and realization of an electronic measuring unit destined for an electrochemical sensor. It's main purpose is to be used for... more
This paper describes the motivation and realization of an electronic measuring unit destined for an electrochemical sensor. It's main purpose is to be used for residual pesticide detection in aliments. The sensor is based on the configuration with three electrodes, and is realized in thick film technology using specific silver and carbon conductive depositions, and was described in a previous
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Development of a large perspective for the e-global economy requires a new approach for learning and training processes. Corporate and governmental organizations are significantly shifting their strategies from hierarchical work... more
Development of a large perspective for the e-global economy requires a new approach for learning and training processes. Corporate and governmental organizations are significantly shifting their strategies from hierarchical work structures, creating departmental layers, toward team-based flat organizations. These human centered holons may cut across responsibilities. Large transnational companies try to learn behavior as “local” citizens everywhere, whilst local SMEs try to learn how to operate “in the global market”. Local and regional economics are a source of innovative activity but competitiveness has to be global. Accordingly, with this trend of an e-activities based society, it is necessary to develop a new concept based on the concurrent engineering methodology involving team building and operation. The paper aims to launch a discussion about change management for a well balanced curriculum between traditional “face to face” classes and e-learning facilities. A case study for...
Research Interests: Packaging, Engineering Management, Concurrent Engineering, Change Management, Regional Economics, and 11 moreTeaching, Face to Face, Team Building, Case Study, Team work, Resource Management, Electronic Packaging, Global Economy, Electrical Engineering Education, Management of Change, and Electronic Commerce
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The paper is focused on PWB structures and laminates, based on glass as dielectric substrate or even a conductive substrate as solid aluminum and the dielectric as a thin sheet between the base metal and the layer containing traces. The... more
The paper is focused on PWB structures and laminates, based on glass as dielectric substrate or even a conductive substrate as solid aluminum and the dielectric as a thin sheet between the base metal and the layer containing traces. The purpose is to evaluate these structures from the electromagnetic viewpoint and to observe, when metallic interconnection structures are placed on
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Includerea senzorilor rezistivi in designul dispozitivelor electronice organice este necesară pentru a extinde domeniul aplicaţiilor posibile. Pentru aceasta este necesară identificarea materialelor rezistive, a proceselor si metodelor de... more
Includerea senzorilor rezistivi in designul dispozitivelor electronice organice este necesară pentru a extinde domeniul aplicaţiilor posibile. Pentru aceasta este necesară identificarea materialelor rezistive, a proceselor si metodelor de structurare, precum si analiza proprietăţilor rezistive pe substrat flexibil ale acestora. Două materiale cu aplicaţie largă in electronica organică sunt polimerii umpluţi cu carbon (carbon filled polymer, CFP) si polimerii cu conducţie intrinsecă (ICP, poly (3, 4-ethylendioxythiophene) doped with polystyrene sulfonate acid, PEDOT:PSS). Lucrarea are ca scop prezentarea comportării acestor polimeri conductivi pe suport flexibil sub influenţa curentului continuu si in impulsuri, subliniind variaţiile rezultate ale proprietăţilor rezistive. Lucrarea este prezentată in două părţi, prima parte analizează comportarea polimerilor umpluţi cu carbon iar partea a doua pune accentul pe polimerii cu conducţie intrinsecă. There is a necessity to include sensors...
Research Interests:
The present paper represents a study of a hybrid electric system that uses a battery of electrochemical double-layer capacitors (EDLC), a conventional leadacid battery and a proprietary electronic system, designed to obtain minimum... more
The present paper represents a study of a hybrid electric system that uses a battery of electrochemical double-layer capacitors (EDLC), a conventional leadacid battery and a proprietary electronic system, designed to obtain minimum electromagnetical disturbances, with uses in automotive applications. The electronic control module offers the possibility of programming the control method of the distribution of electricity in the hybrid system. Electromagnetic compatibility assessments of the electronic were also performed according to CISPR 22 standard and the results are compared with the limits specified by the standard. Electrical tests performed on both charge / discharge cycles of the battery of supercapacitors and in combination with a reversible electric motor highlights the benefits of using EDLC in automotive applications.
Reţeaua informatică dezvoltată în cadrul proiectului IN – TECH – TRANSFER vine în sprijinul exploatării oportunităţilor existente pe piaţă în ceea ce priveşte inovarea şi transferul tehnologic. Pentru ca transferul tehnologic să fie... more
Reţeaua informatică dezvoltată în cadrul proiectului IN – TECH – TRANSFER vine în sprijinul exploatării oportunităţilor existente pe piaţă în ceea ce priveşte inovarea şi transferul tehnologic. Pentru ca transferul tehnologic să fie încununat de succes trebuie să aibă ca ţintă nevoia de satisfacere a pieţei cu produse, tehnologii şi servicii. În sprijinul acestei idei a fost creat un sistem informatic care să poată fi accesat cu uşurinţă de potenţialii utilizatori ai rezultatelor cercetării – dezvoltării.
Random numbers generators are widely used in different fields like cryptography, gaming development, artificial intelligence, etc. Being the engine of some security (cryptographic) protocols, the development of good and secure Random... more
Random numbers generators are widely used in different fields like cryptography, gaming development, artificial intelligence, etc. Being the engine of some security (cryptographic) protocols, the development of good and secure Random Number Generators aroused the attention of the research communities worldwide. Random Number Generators split into two categories: True Random Number Generators (based on physical non-deterministic processes, like the jitter of an oscillator) and Pseudo Random Number Generators (based on mathematical properties, where the output at the time t is based somehow on the output on time t-1). It is well known that the output distribution of a Random Number Generator (either True or Pseudo) output tends toward 50%. There are some particular cases where this probability must be different (some of these situations will be described here) and this paper will present a way of obtaining this. The novelty of this paper is based on a new approach on the classic Gollmann Cascade PRNG and starting from this, the development of a FPGA implementation to increase its security.
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The present stage of development of electronics technology there is an increased interest in the study of new materials used as solder that replaces the already banned tin-lead alloy. Many investigations were done in direction of... more
The present stage of development of electronics technology there is an increased interest in the study of new materials used as solder that replaces the already banned tin-lead alloy. Many investigations were done in direction of metallurgic compatibility between the printed circuit board finishing, component terminal finishing and solder itself. Other studies are taken in direction of mechanical characterization of lead free alloys. We propose a study from electrical point of view. So we will analyze the current capabilities of solder joints by thermographical investigations. The finite conductivity of the solder alloy will act as a dissipating media and will heat the adjacent region to the joint. In order to make this effect more pregnant it is necessary to dispose of very precise low-ohm resistors and to pass through them relatively high currents. Based on a high resolution infrared camera the temperature gradient will be better observed. The measured results are compared to the results derived from finite element modeling and simulation. In the simulations, the whole D structure of solder joint is modeled. It has practically a very complex shape and is difficult to be analyzed using other methods. Our tests will be realized on organic rigid substrates using a configuration that was intended to characterize the solder joint dissipation. The data derived from this analysis will be very useful in the design process of high power circuits that could be used in advanced electronic modules.
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Accumulators used in electric vehicles being in production to date have the disadvantage of a limited number of charge-discharge cycles (lead-acid accumulators) or high acquisition price (NiMH, Li-Ion) and long full recharge duration.... more
Accumulators used in electric vehicles being in production to date have the disadvantage of a limited number of charge-discharge cycles (lead-acid accumulators) or high acquisition price (NiMH, Li-Ion) and long full recharge duration. This paper presents a study on a solution to increase the life cycle of a typical battery pack used in automotive applications by recovering the deceleration energy
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ABSTRACT This paper continues the study in the field of microheaters on flexible substrates. The idea of using flexible substrates comes together with the need for low manufacturing costs, having in mind the applications of sensors for... more
ABSTRACT This paper continues the study in the field of microheaters on flexible substrates. The idea of using flexible substrates comes together with the need for low manufacturing costs, having in mind the applications of sensors for home usage and other possible applications as monitors for buildings or basements where possible toxic gases can be accumulated, for instance mathane, carbon monoxide or carbon dioxide. In the current paper we propose the use of poly(3,4-ethylenedioxythiophene) doped with polystyrenesulfonic acid (PEDOT:PSS) as active heating element. The data from literature and our previous experiments have proven that this material can be used as resistive material having the possibility to operate within the desired range of temperatures for sensor applications, between 80 and 100 °C. The test samples with different patterns will be prepared by ink-jetting, with silver ink used as terminations.
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In order to investigate the behavior for very high current densities on polymer resistors on flexible substrates, a pulsed measurement technique was applied. The analytical test technique of transmission line pulsing (TLP) allows, on the... more
In order to investigate the behavior for very high current densities on polymer resistors on flexible substrates, a pulsed measurement technique was applied. The analytical test technique of transmission line pulsing (TLP) allows, on the basis of square pulses, the in-situ monitoring of the voltages and currents at the device under test (DUT) during pulsing and helps to gain fundamental
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ABSTRACT The paper presents the result of studies and investigations related to planar thermoelectric generators, intended to be realized through printing technologies. The recent development in printing technologies and materials makes... more
ABSTRACT The paper presents the result of studies and investigations related to planar thermoelectric generators, intended to be realized through printing technologies. The recent development in printing technologies and materials makes possible the realization of thermoelectric pairs in planar configuration as an alternative to the already used devices. The use of printing technologies permits the realization of a higher density of structures, keeping the overall volume very low. The main problem is that the materials required to print the thermoelements are still under test and there was not yet found an optimal paste system solution. In the same time, the Seebeck coefficients are smaller in comparison with bulk materials. We have used the finite element software features in order to include thermoelectric generation effects. This was done by performing a thermal-electric coupled analysis for two type of layouts. One is a known complex configuration of thermoelectric module, for which a model validation exists and the other is a real planar configuration.