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340 results on '"Wunderle, B."'

4. Full-Field Through-Chip IR-Thermography-based Quality Testing & Failure Analysis on Electroplated Aluminium Interconnects for Cryogenic Applications in Ion-Trap Quantum Computers

Author

May, D., primary, Wunderle, B., additional, Cirulis, I., additional, Braun, S., additional, Zschenderlein, U., additional, Heilmann, J., additional, Pantou, R., additional, Schacht, R., additional, Rzepka, R., additional, Ras, M. Abo, additional, Kurth, S., additional, and Kuhn, H., additional

Published
2024
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6. Nanomechanics of CNTs for Sensor Application

Author

Wagner, C., Hartmann, S., Wunderle, B., Schuster, J., Schulz, S. E., and Gessner, T.

Subjects
Condensed Matter - Mesoscale and Nanoscale Physics
Abstract

A nanoscopic simulation for an acceleration sensor is aimed based on the piezoresistive effect of carbon nanotubes (CNTs). Therefore, a compact model is built from density functional theory (DFT), compared with results of molecular dynamics (MD) that describes the mechanics of carbon nanotubes in a parameterized way. The results for the interesting kind of CNTs [(6,3) and (7,4)] within the two approaches agree in a satisfying way, when DFT-calculations are performed with atomic configurations obtained by MD geometry optimization. Geometry optimization yields the Poisson ratio for CNTs. Thus, values from MD and DFT are compared. The simulation finally aims the modeling of the conductive behavior of CNTs when strain is applied, but this needs further verification. Here, we present the prediction of the tight binding model for suitable CNTs., Comment: 5 pages, 4 figures, 2 tables

Published
2017
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7. Characterization of Thermal Interface Materials to Support Thermal Simulation

Author

Schacht, R., May, D., Wunderle, B., Wittler, O., Gollhardt, A., Michel, B., and Reichl, H.

Subjects
Condensed Matter - Materials Science
Abstract

In this paper new characterization equipment for thermal interface materials is presented. Thermal management of electronic products relies on the effec-tive dissipation of heat. This can be achieved by the optimization of the system design with the help of simulation methods. The precision of these models relies also on the used material data. For the determi-nation of this data an experimental set-up for a static measurement is presented, which evaluates thermal conductivity and interface resistance of thermal inter-face materials (e.g. adhesive, solder, pads, or pastes). A qualitative structure-property correlation is pro-posed taking into account particle size, filler content and void formation at the interface based on high resolution FIB imaging. The paper gives an overview over the set-up and the measurement technique and discusses experimental and simulation results., Comment: Submitted on behalf of TIMA Editions (http://irevues.inist.fr/tima-editions)

Published
2007

30. Nondestructive failure analysis and simulation of encapsulated 0402 multilayer ceramic chip capacitors under thermal and mechanical loading

Author

Wunderle, B., Braun, T., May, D., Michel, B., and Reichl, H.

Subjects
Finite element method -- Usage, Reliability (Engineering) -- Evaluation, Electronic equipment and supplies -- Plastic embedment, Electronic equipment and supplies -- Mechanical properties, Electronic equipment and supplies -- Thermal properties, Electronics
Abstract

The use of multilayer ceramic chip capacitors as integrated passive in, e.g., system in package applications needs methods to examine and predict their reliability. Therefore, a nondestructive failure analytical technique is described to detect cracks in the ceramic and the metallic layers within encapsulated 0402 surface mount device (SMD) capacitors. After choosing from techniques to reproducibly generate cracks, it is shown that an in situ capacitance measurement is a convenient method to detect these failures unambiguously. Finite element simulations support the experimental results. A reliability estimate for capacitor integrity under given loading conditions is given. [DOI: 10.1115/1.3078187]

Published
2009

39. Carbon nanotubes for mechanical sensor applications

Author

Wagner, C., Blaudeck, T., Meszmer, P., Böttger, S., Fuchs, F., Hermann, S., Schuster, J., Wunderle, B., Schulz, S.E., and Publica

Subjects
strain, reliability, carbon nanotubes (CNTs), micro- and nano electromechanical systems (MEMS, NEMS), sensors
Abstract

Herein, the evolution of carbon nanotubes (CNTs) as functional material in nano‐ and microelectromechanical systems (N/MEMS) is featured. Introducing material morphologies for the CNTs in a homologue series (single CNTs-bundles, fibers, yarns-networks and thin films), different concepts for mechanical sensors based on the intrinsic and extrinsic properties of the CNT materials are introduced (piezoresistive effect, strain‐induced band bending, charge tunneling). In a rigorous theoretical treatment, the limits of the achievable sensor performance (i.e., gauge factor) are derived and discussed in the context of applications. A careful literature survey shows that highest sensitivity is reached for devices exploiting the intrinsic transport properties of single CNTs. For reliability tests of such sensor systems made from nanomaterials and classical MEMS, the specimen‐centered approach (SCA) is introduced to give viable insights into the structure property relationships and failure modes of CNT mechanical sensors. CNT actuation occurs on the macro‐, micro‐, and nanoscales via atomic force microscopy, electrostatic gating, integration in N/MEMS systems, or through substrate bending.

Published
2019

40. Advanced characterization methods for electrical and sensoric components and devices at the micro and nanoscale

Author

Sheremet, E., Meszmer, P., Blaudeck, T., Hartmann, S., Wagner, C., Ma, B., Hermann, S., Wunderle, B., Schulz, S. E., Hietschold, M., Rodriguez, R. D., and Zahn, D. R. T.

Subjects
atomic force microscopy, Scanning probe microscopy, nanoanalysis, Raman spectroscopy, Kelvin probe force microscopy
Abstract

This feature article covers the nano-analysis methods for four key material characteristics: electrical and electronic properties, optical, stress and strain, and chemical composition. With the downsizing of the geometrical dimensions of electronic, optoelectronic, and electromechanical devices from the micro to the nanoscale at the one hand and the increase of functionality density at the other, the previous generation of micro-analysis methods is no longer sufficient. Therefore, the metrology of materials’ properties with nanoscale resolution has become prerequisite in materials research and development. The article shortly reviews the standard analysis methods and focuses on advanced methods with a nanoscale spatial resolution based on atomic force microscopy (AFM): current-sensing AFM (CSAFM), Kelvin probe force microscopy (KPFM), and hybrid optical techniques coupled with AFM including tip-enhanced Raman spectroscopy (TERS), photothermal-induced resonance (PTIR) characterization methods (nano-Vis, nano-IR), photo-induced force microscopy (PIFM) and photothermal microspectroscopy (PTMS). The simultaneous acquisition of multiple parameters (topography, charge and conductivity, stress and strain, chemical composition) at the nanoscale is a key for exploring new research on structure-property relationships of nanostructured materials such as carbon nanotubes (CNTs) and nano/microelectromechanical systems (N/MEMS). Advanced nanocharacterization techniques foster the design and development of new functional materials for flexible hybrid and smart applications.

Published
2019

41. Highly Miniaturized MEMS‐Based Test Platforms for Thermo‐Mechanical and Reliability Characterization of Nano‐Functional Elements - Technology and Functional Test Results

Author

Meszmer, P., Hahn, S., Hiller, K., Wunderle, B., and Publica

Abstract

This paper reports on concepts, technology, integration aspects, and results of a MEMS‐based test platform for reliability tests of micro and nano objects. Building blocks of this platform to be used in in‐plane push‐pull‐configurations are a thermal actuator, a force sensor, and a displacement sensor as well as several types of samples to be integrated directly or indirectly. The technology concept is proven for aluminum wires as a first demonstrator for an integrated specimen. The modular concept enables the adoption of the platform for further types of samples and test configurations. The building blocks are simulated using a Finite‐Element approach and the results are compared to experimentally obtained data sets. According to the specifications, the thermal actuator is capable of providing displacements up to 1.5 mm. The displacement and the force sensor are specified to provide sensitivities of 3 fF nm−1 and 2.5 mV nN−1, respectively. SEM image of a piezoresistive force sensor attached to an integrated Al wire as test sample − building blocks of MEMS‐based test platforms.

Published
2019

47. Quantitative in-situ scanning electron microscope pull-out experiments and molecular dynamics simulations of carbon nanotubes embedded in palladium.

Author

Hartmann, S., Blaudeck, T., Hölck, O., Hermann, S., Schulz, S. E., Gessner, T., and Wunderle, B.

Subjects
CARBON nanotubes, SCANNING electron microscopes, MOLECULAR dynamics, PALLADIUM, CANTILEVERS
Abstract

In this paper, we present our results of experimental and numerical pull-out tests on carbon nanotubes (CNTs) embedded in palladium. We prepared simple specimens by employing standard silicon wafers, physical vapor deposition of palladium and deposition of CNTs with a simple drop coating technique. An AFM cantilever with known stiffness connected to a nanomanipulation system was utilized inside a scanning electron microscope (SEM) as a force sensor to determine forces acting on a CNT during the pull-out process. SEM-images of the cantilever attached to a CNT have been evaluated for subsequent displacement steps with greyscale correlation to determine the cantilever deflection. We compare the experimentally obtained pull-out forces with values of numerical investigations by means of molecular dynamics and give interpretations for deviations according to material impurities or defects and their influence on the pull-out data. We find a very good agreement of force data from simulation and experiment, which is 17 nN and in the range of 10-61 nN, respectively. Our findings contribute to the ongoing research of the mechanical characterization of CNT-metal interfaces. This is of significant interest for the design of future mechanical sensors utilizing the intrinsic piezoresistive effect of CNTs or other future devices incorporating CNT-metal interfaces. [ABSTRACT FROM AUTHOR]

Published
2014
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48. Transient thermal storage of excess heat using eutectic BiSn as phase change material for the thermal management of an electronic power module: design, technology, performance and reliability within a system approach

Author

Wunderle, B., primary, Springborn, M., additional, May, D., additional, Heilmann, J., additional, Manier, C. -A., additional, Ras, M. Abo, additional, Oppermann, H., additional, Sarkany, Z., additional, and Mitova, R., additional

Published
2018
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