This in vitro study aimed to evaluate and compare the dentine adhesion of two modern pulp capping materials: TheraCal LC (Bisco Inc. U.S.A.) and BioMTA (Cerkamed Poland). The samples have been prepared simulating in vivo conditions, in accordance with ISO/DIN standard protocols for this type of test. Twelve samples were prepared in this way, being preserved in good condition for each material in order to be investigated and the results interpretated. The values of the shear test, measured in kgf for each sample, have been recorded. A paired t-test was conducted to compare mean adhesion results in TheraCal and MTA groups. The results of our study showed a statistical significant difference between the measurements for TheraCal (M=1.27, SD=0.69) and MTA (M=0.22, SD=0.13); t(11)=4.80, p=0.0005. The results suggest that TheraCal has better adhesion properties than MTA.

ANTOANELA COVACI 1, LUCIAN TOMA CIOCAN 1∗ , SILVIU MIREL PIŢURU1, IOAN PLOTOG 2, GAUDENŢIU VĂRZARU2, MIHNEA IOAN NICOLESCU 1,3, CRISTIAN FUNIERU1*, ANDREEA CRISTINA DIDILESCU 1 1 Faculty of Dental Medicine, Carol Davila University of Medicine and Pharmacy, Bucharest, ROMANIA; 2 Center for Technological Electronics and Interconnection Techniques, Faculty of Electronics and Telecommunication, Polytechnic University, Bucharest, ROMANIA; 3 Victor Babeș National Institute of Pathology, Bucharest, ROMANIA.

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.

The paper presents the mechanical and electrical properties of the joints as function of curing temperatures. These are made by printing a SW180 type ECAP (Electrically Conductive Adhesives Pastes) on printed circuit boards (PCBs) having daisy chain interconnection structures: one type of structure realized by printing ECAP on FR4 support, the chip components being placed into ECAP volumes corresponding to pads zones, the other type was etched using classical PCB technology in two hot air solder leveling (HASL) finishing types, leaded and lead-free. The micro-sections analysis of electrical joints and the microfractography analysis after shear testes performed on zero ohms, 1206 casing chip components are presented and interpreted. The database created as experiments results assures much better understanding of ECAP bonding processes as function of their curing temperature and offers the possibility to increase the reliability of ECAP applications in electronics.

The SW150 and the new types SW180 of Electrically Conductive Adhesives (ECA) dedicated to printing circuits1, meeting RoHS EU Directive2, were used, according to REACH EU Regulation3, to bond optoelectronics components, LED type, on test printed circuit boards (TPCBs) having daisy chain interconnection structures. Mechanical properties of LEDs bonds function of temperatures by measuring shear forces applied on each of bonded LEDs maintaining TPCBs at different temperature from ambient to 398 K (125°C), were investigated. The shear forces measured values, the LEDs bonds micro sections and the microfractography after shear testes analyses and interpretations, facilitate the construction of a database that provides support for the development of temperature-sensitive optoelectronic device assembling solutions by bonding, using ECA. These solutions ensure avoidance of their functional temperature failures during classical assembly processes, comparing ECA curing and reflow temperatures.

The paper presents the investigations of bonds mechanical strain function of duration of curing at different fixed curing times to evaluate the possibilities of bonding process on SMT line by using electrically conductive adhesives pastes (ECAP). The experiments will be performed by keeping test PCBs up to 30 minutes (5/10/15/20/25/30 min) at 130°C. The test PCBs contain 0Ω 1206 chip resistors having conductive paste traces realized by printing on FR4 support. The paper presents the results and their interpretation of the microfractography analysis of the chip resistors bonds and the energy dispersive X-ray microanalysis (EDXMA) after resistors bonds shear tests as function of curing period. The experiments become a first step for defining ECAP for usage on SMT line in order to extend ECAP applications in electronics.

Generally, remote control of electric motors consists in commands for operation using two main methods, wireless and wired. Wired remote control implies a dedicated path for low voltage signals separated from the power line. The increased cost of copper wire and the problems caused by the cable routing between the control unit and the motor led to the solution of control over power line. In home automation, there are appliances or other equipment driven by the more efficient permanent magnet synchronous motors (PMSM). In the paper are present the work done in order to define the remote control over the power line solution for a new family of PMSM. The novelty is to reduce the two paths to one - such that communication to and feeding of the motor are supported by the power line. The goal of the work is to integrate the functionality of the power line modem as a new function to a controller charged for PMSM control using field orientated control algorithm.

Under the current conditions of reducing manufacturing costs and complying with the RoHS 2 EU Recast Directive in the automotive industry, without compromising functionality and reliability, it has become necessary to create a new Lead-Free Solder Pastes family [1]. Mechanical and thermal solder joints functionalities are determined by the microstructure morphology. In this respect, the paper presents the phases morphology as function of cooling rate in Vapour Phase Soldering Process (VPSP), for three alloys coming from the solder pastes: ALPHA ® OM-6106 (Sn62), ALPHA ® OM-340 (InnoLot) and ALPHA ® OM-535 (SBX02). The presented work extends the theoretical studies and experiments upon phase morphology in VPSP, in order to optimize soldering process of automotive electronic modules. The results could be extend for home and modern agriculture appliances industry [2].

In a vehicle, for electronic components, the working temperature may vary between the limits 358K and 478K. The manufacturing costs reduction necessity combined with the RoHS2 EU Directive consequence lead to create new Low Melting Point Lead-Free (LMPLF) solder pastes family. In the paper, are presented the shear tests of the solder joints (SJ) and thermal diffusivity (ThD) measurements made on samples cast from LMPLF solder pastes (ALPHA®CVP-520, and ALPHA®WS-852) into Vapour Phase Soldering Process (VPSP) characterized by different cooling rates (0.5K/s and 4.0K/s). The paper deals with the continuation of studies on the influence of thermal transfer (mainly thermal diffusivity) in the VPS process on the mechanical properties (shear tests) of the solder joint, for the new LMPLF alloys recently implemented in the automotive industry [1]. In this regard, it is emphasized the influence of solder joint shear force (SF) properties, depending on their ThD as function of solder alloy, which “set” the rate of heat transfer (convective versus conductive) to the substrate (PCB).

The maximum temperature of all parts of automotive electronics equipment is given by the location and can vary between 358 K and 478 K. RoHS EU Directive in the context of the manufacturing costs reduction, necessity led automotive industry to create new Low-Temperature Lead-Free (LTLF) solder pastes family. In the paper, the thermophysical properties of the alloys from ALPHA ® CVP-520 (SnBiAg) and ALPHA ® OM-535 (SBX02) test samples having as a source solder pastes were compared with similar from ALPHA ® OM-6106 (Sn62) solder paste. The presented work extend the theoretical studies and experiments upon heat transfer in VPSP in order to optimize the technology for soldering process (SP) of automotive electronic modules and could be extended for home and modern agriculture appliances industry.

The range of electronic components and as a consequence, all parts of automotive electronic equipment operating temperatures in a vehicle is given by the location of that equipment, so the maximum temperature can vary between 358K and 478K(1). The solder joints could be defined as passive parts of the interconnection structure of automotive electronic equipment, at a different level, from boards of electronic modules to systems. The manufacturing costs reduction necessity and the RoHS EU Directive(3, 7) consequences generate the trend to create new Low-Temperature Lead-Free (LTLF) solder pastes family(9). In the paper, the mechanical strength of solder joints and samples having the same transversal section as resistor 1206 case type made using the same LTLF alloys into Vapour Phase Soldering (VPS) process characterized by different cooling rates (slow and rapid) and two types of test PCBs pads finish, were benchmarked at room temperature. The presented work extends the theoretical studies and experiments upon heat transfer in VPSP in order to optimize the technology for soldering process (SP) of automotive electronic modules and could be extended for home and modern agriculture appliances industry. The shear forces (SF) values of the LTLF alloy samples having the same transversal section as resistor 1206 case type will be considered as references values of a database useful in the new solder alloy creation processes and their qualification for automotive electronics domain.

The paper presents some theoretical and experimental aspects regarding the tribological performances of lead-free solder joint connections, with application in the aerospace domain.In order to highlight the mechanical and tribological properties of solder joint in correlation with different pad finishes, there were made some mechanical determinations using a dedicated Share Test System.The theoretical model highlights the link between the experimental results and the influence of gravitational acceleration on the mechanical and functional integrity of the electronic assemblies that works in vibration environment.The paper novelty is provided by the interdisciplinary experiment that offers results that can be used in the mechanical, tribological, electronical and aerospace domains.

32.768 kHz low frequency crystals are found in a large part of today's embedded systems that use microcontrollers especially in battery supplied applications which need low power consumption(1]). Their main role is to offer a stable time reference. There are situations in which time measurement is needed when the system works in a mechanically unstable environment (cars, industrial equipment). The paper presents the studies done on the behavior of 32.768 kHz quartz crystals that are part of embedded systems which operate in a vibrating environment, in terms of period and long-time jitter of the generated time reference signal. The investigations of this effect were done using a test bench especially designed for this purpose which can measure the presented parameters determined by controlled mechanical stimulus (waveform, amplitude and frequency of the vibrations).

The subject of the present work is an irrigation controller able to satisfy the needs of a small farm for water, nutrients and pesticides having in view the consumption efficiency, as well as energy savings and cost effectiveness. In order to achieve these targets, the process is largely automated being a scheme with closed loop reaction based on the monitoring of several main parameters characterizing the soil and environment condition. The monitoring element is a multi-sensor device connected wirelessly to the central unit of the irrigation controller. For a small and medium size farm several devices are needed forming a wireless sensor network. The paper is focused on the peculiar solar supply of the wireless sensors network in order to exploit the data provided by the photovoltaic cell for a better management of the crops. Agronomists agree that crops needs are for a medium illuminance ranging from 20,000 to 50,000 lx, that corresponds to a shade illuminated by entire clear blue sky, midday. Therefore, the experiments were conducted mainly for establishing a threshold voltage for detecting 20,000 lx illuminance in order to count the days requested for proper harvesting.

The need for reliable data on thermophysical properties of materials has increased continuously in the last period. The existing data, except for some pure elements or alloys and compounds, often unreliable, and in many cases the need for accurate and acceptable data, can only be achieved by measuring a given property. This paper focuses on elements of the used test methods associated with the description of the newly introduced parameter (effectiveness of dental coating). The selected method was the “pulse method” for determining thermal diffusivity (the method allows simultaneous determination of thermal diffusivity, specific heat capacity and thermal conductivity) directly applicable in the study of the thermal compatibility of metal-ceramic systems in dental applications.

In this paper there are presented investigations regarding power IR LED efficiency in relation to operating temperature in order to define the reference values and conditions for using such devices for realizing long range proximity sensors, especially for applications in the automotive domain. The previous experiments done regarding the power LED used for infrared sources emphasize the optical power dependency to temperature. The new experiments were designed for measuring optical power and temperatures of LED heat sink and case, respectively of star and square type circuit boards (thermally conductive insulated metal substrate - IMS), at different points in the same time, for different values of LED driving current and various ambient temperatures, in order to make a correlation between LED efficiency and temperature. The results obtained and presented in this paper will be used further as references for designing an anticollision warning system with applications into automotive domain. Keywords: Power

The electronic modules are complex ensemble of electronic components having terminals (PIN) connected by solder joints on dedicated metallic surfaces (PAD) parts of conductive interconnection structure realized on rigid or flexible dielectric substrate having different core materials. The reliability of the electronic modules could be considered as expression of solder joints functionality (SJF) relating to working conditions and unique defined by their electrical, mechanical and thermal properties. These properties are in close connection with the solder joints microstructures, result of the soldering Process temperature gradient action over the trinomial solder alloy Paste, Pin and Pad. Consequently the solder joints quality can be correctly evaluated taking into consideration not only the severally intrinsic parameters of the trinomial elements Pin-Pad-Paste characterized by specific thermophysical properties (ThP), but also interrelate the complex reaction at the interface between them and interdependence with the soldering Process parameters.In the paper, will be analyzed the influencing factors of manufacturing processes, the most important assembling defects at macro and micro level, their causes relating to specific ThP and processes at interfaces Pin-solder joints-Pad, it will be identify the Key Process Input Variables (KPIV) and propose a structural model for assembling processes, 4P Soldering Model, as an useful tool in engineering of electronic product in order to assure the assumed goal for assembling stage.

The studies regarding magnetic field (MF) biotechnological applications in the range of Extremely Low Frequency (ELF: 3Hz to 300Hz, ITU Recommendation V. 431-7) were generally based on Helmholtz coils (HC) systems in order to obtain a constant intensity for a determined volume. The paper presents the comparative studies of HC and Maxwell coils (MC) consisting in modelling, simulations and measurements of MF intensity. For this the geometry of the external coils of the MC system was designed identically with HC type. Based on the obtained results, there are defined the internal field intensity distribution for both coils systems used to design biotechnological applications.

The electroluminescent (EL) tapes or foils having barrier films for an additional level of protection against the toughest environments conditions, offer a large area of applications. The EL lights, due to their characteristics, began to be used not only in the entertainment industry, but also for automotive and aerospace applications. In the paper, the investigations regarding EL foils technical performances in relation to their applications as light sources in automotive ambient light were presented. The experiments were designed based on the results of EL foils electrical properties previous investigations done in laboratory conditions, taking into account the range of automotive ambient temperatures for sinusoidal alternative supply voltage. The measurements for different temperatures were done by keeping the EL foils into electronic controlled oven that ensures the dark enclosure offering conditions to use a lux-meter in order to measure and maintain under control light emission intensity. The experiments results define the EL foils characteristics as load in automotive ambient temperatures condition, assuring so the data for optimal design of a dedicated inverter.

The paper aimed to present the investigation of the use of photovoltaic cells based devices for solar light measurements and analysis in order to forecast the pace of growth of plants and to estimate the appropriate timing of harvest culture. It is based on the continuous data measurements by a microcontroller based circuitry of a solar module used for supplying a multi-functional wireless sensor for agriculture. The solar module consists of two monocrystalline solar cells (c-Si) flat design, highly transparent and having UV stable front encapsulation. The data is not only a simple day and night information, but a measurement of the solar radiation. The device is able to measure the environment temperature as well, therefore the data is useful for evaluation of the photoperiodism, but the correlation between solar radiation and temperature is also possible. The data is transmitted to a host controller able to store and process higher volume information. As a conclusion, the research seeks to provide a low-cost solution for small and medium size farms based on the very solar cells used to supply low-power consumption electronic modules of the wireless network sensors for an optimal recovery of production depending on the type of culture.