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Different vacuum interrupters (VI) are equipped with Transversal Magnetic Field (TMF) contacts. Due to the current path, a transversal directed Lorentz-force is affecting the electric arc to move in a circular, in order to reduce the heat input and therefore the local erosion of the contact surface. The degree of the contact erosion is dependent on the local temperature of the arc root, which can...
Audible noise of automotive alternators is a key point for future cars. Its reduction requires a multiphysic approach including electromagnetic, vibro-acoustic and thermal aspects. In this perspective, this paper investigates the influence of stator temperature on the acoustic noise of a claw-pole alternator. Experimental results show a clear reduction of sound power level and change in noise peak...
High power density DC/DC converters have gained attention in automotive applications for Electric and Hybrid Vehicles. Inductors often appear as the largest component in DC/DC converters. DC/DC converters using a coupled inductor are well-known as one of the topologies which can achieve miniaturization of a magnetic component. Temperature of an inductor tends to be higher in high power density DC/DC...
Accurate sets of material constants and temperature coefficients are required to develop high temperature SAW sensors. It was previously shown that SAW Fractional Frequency Curve measurements combined with numerical optimization could help ease the burden of the experimental determination of some of these coefficients. To determine the other “missing” coefficients, it was suggested to use complementary...
This paper focuses on development of a low contact resistance interconnection for low temperature bonding applications. Alternative to conventional display interconnection mechanisms using anisotropic conductive film (ACF), solder and underfill method using low melting point Bi58-Sn solder is suggested. Solder bumping is carried out using a maskless Solder-on-Pad technology. An average bump height...
The demand for high performance white light LED devices for general illumination systems increases continuously. However, high illumination performance also implies higher thermo-mechanical stresses on the LED device and could lead to changes in quality parameters of the device like color stability, efficiency and of course a decrease in lifetime. This paper investigates the thermo-mechanical interaction...
A THz TDS study of permittivity and conductivity properties of new variant of Yttria-stabilized-Zirconia (YSZ) produced using tape-cast method is reported. This study extends the frequency coverage of some of the previously published work. We find a general agreement with published results but the frequency gap in the mm-wave range needs to be measured more carefully before final conclusions on the...
We have carried out a terahertz (THz) passive measurement of high-Tc superconductive materials down to liquid nitrogen temperature at 1.5–2.5 THz using a 4 K-cryocooled stressed Ge:Ga photoconductive detector. Using the calibration line, which gives the relation between THz signal emitted from sample, emissivity and temperature, we have derived the temperature-dependent THz emissivity of superconductive...
This paper deals with the development of a new test stand for determination the thermal conductivity of metals, semiconductors, highly conductive die attaches and substrates using the steady state technique. We designed the test stand and optimized it by FE simulation to have flexibility for the selection of the sample size and measurement parameters. We determine the thermal conductivity from the...
Radio frequency identification (RFID) tags are typically used for object identification in environments in which they are not exposed to very harsh conditions. However, there is an increasing demand for inexpensive RFID tags for use in harsh industrial environments, but the adequate performance of the materials used in them needs to be verified in such conditions. This paper reports the reliability...
This study focuses on the influences on undercooling of SnCu solder alloys. Therefore Differential Scanning Calorimetry (DSC) measurements were carried out on commercially available solders with varying Cu content (from 0 wt.% to 3.0 wt.%). Furthermore the diameter of the investigated solder spheres was varied from 131 μm to 1120 μm in order to represent typical interconnect sizes of electronic packages...
In this article it is presented how structural information and temperature distribution can be calculated from thermal transient measurement results. We show how the temperature distribution can be approximated from a time domain temperature transient using simple calculations and that not only the temperatures but the geometry of a three dimensional model can also be calculated from the thermal RC...
We investigated the mechanical properties of a silver sinter paste dependent on sintering and drying conditions. For these experiments we fabricated dedicated samples without silicon and leadframe to investigate the pure material properties. Our investigation on the influence of drying and sintering conditions demonstrated that the longer the sintering time and the higher the temperature the higher...
Solid State Lighting technologies are becoming more and more attractive in the lighting market. Thermal management is a key issue, which impacts efficiency but also colour stability and reliability of LED-based systems. In this paper, we describe and discuss such issues through various examples of different projects by analysing both the heat transfer mechanisms and their impact on the choice of materials...
The stress sensing system, which has been developed recently, allows measuring the magnitudes and the distribution of mechanical stresses induced in the silicon dies during fabrication and testing of the electronic packages. The studies already presented in the last years focused on the effects of temperature cycling, 4-point-bending, moisture swelling, and molding. This paper reports the results...
Nowadays monitoring physiological signals in real situations is essential to get the best diagnosis on patients. In this study we focus on the heat flux generated by the human body. We are developing a portable heat flux sensor using specific thermal materials.
Batteries are a critical component that largely governs the performance and cost of an electric vehicle. There are a variety of types of batteries competing for use, each with cons and pros. Among these options, Li_4 Ti_5 O_12 batteries excel with superior performance in terms of safety, stability, service life. In order to make better use of its merits for electric vehicle applications, understanding...
Low-grade waste heat and abundantly available thermal energy has the potential to be harvested by the pyroelectric effect. For uniaxial radiative heating we report elliptic temperature profiles in lead zirconium titanate and polyvinylidenefluoride. The geometry, heat diffusion coefficient and pyroelectric coefficient of the material determine the harvesting potential of a pyroelectric generator. At...
The influence of viscoelastic behavior of polybutylene terephthalate (PBT) on reliability of the thermal contact of a spotlight module is evaluated. The contact between a module and the heat sink is evaluated using non-linear finite element model. The viscoelastic behavior of PBT was obtained under multiple frequencies from single cantilever DMA experiments. The relevant viscoelastic parameters (i...
NiCu is one of the widely used thin-film materials, which is now commonly used as sensor and resistor in very-large-scale-integration (VLSI) because of its high resistivity and stability. However, with the scale decreasing and the temperature increasing in service condition, the limited reliability of NiCu thin-film material has been a key issue in microelectronics and packaging industry mainly due...
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