@inproceedings{9959,
  abstract     = {{Ultrasonic heavy wire bonding is a commonly used technology to conduct electrical devices in power electronics. In order to facilitate powerful solutions combined with an increased efficiency, involving a material change from aluminum to copper wire as conductor material takes place in recent years. Due to the material related properties, copper wire bonding requires significant higher bond processing parameters such as bond force and ultrasonic power compared to aluminum which can lead to damages or a failure of the bonded component. Therefore, a profound knowledge of the processes prevailing during wire bonding is essential to optimize the application of the copper wires and consequently to achieve the demands on quality and reliability. The behavior of different natural surface oxides of aluminum and copper are assumed to be one reason for the deviation in the required bond parameters. Accordingly, the impact of differently pre-treated substrates surfaces on which the bonding is applied were investigated in this study. First, all conditions investigated (as-received, oxidefree, AlOx and the CuOx) were characterized by utilizing scanning electron microscopy, energy dispersive X-ray spectroscopy, focused ion beam microscopy and atomic force microscopy. In addition, hardness tests were performed as well as perthometer measurements. Afterwards, a 500 $\mu$ m copper wire was bonded on the generated surfaces investigated. In consideration of the roughness, shear test of various bond times and microscopic images were evaluated. Finally, the results were compared and discussed. Overall, the current study indicates that an Al-oxide layer is beneficial for welding process in Cu wire bonding. On the contrary, the Cu-oxide is detrimental and leads to a delayed welding of the joining parts. Based on the obtained results, it can be expected that due to an ideal set of Al-oxide layers, lower optimal bond parameters can used to reach high bond strength with good reliability properties.}},
  author       = {{Eacock, Florian and Unger, Andreas and Eichwald, Paul and Grydin, Olexandr and Hengsbach, Florian and Althoff, Simon and Schaper, Mirko and Guth, Karsten}},
  booktitle    = {{IEEE 66th Electronic Components and Technology Conference}},
  keywords     = {{Ultrasonic copper wire bonding, Al-oxide, Cuoxide, oxide-free, roughness, morphology}},
  pages        = {{2111--2118}},
  title        = {{{Effect of different oxide layers on the ultrasonic copper wire bond process}}},
  doi          = {{10.1109/ECTC.2016.91}},
  year         = {{2016}},
}

@article{34439,
  abstract     = {{A method for the reconstruction of turned shaft surfaces with a (fractal) Weierstrass–Mandelbrot-function (WMF) is presented. The WMF is modified to allow to freely choose a phase-shift for every frequency. The reconstruction is based on distinct profiles in axial and tangential direction and the statistical distribution of low-wavelength portions of the surface is taken into account by adding t-distributed random deviations to the surface. The work is validated by reconstructing measured shaft surfaces with different manufacturing parameters, which shows good accuracy for periodic surfaces. This method allows for a characterization of surfaces with a limited number of parameters and can be used to store the characteristics of measured surfaces with a reduced amount of data compared to a point-cloud surface.}},
  author       = {{Thielen, Stefan and Magyar, Balázs and Piros, Attila}},
  issn         = {{0301-679X}},
  journal      = {{Tribology International}},
  keywords     = {{Roughness, Structure, Fractal, Machining}},
  pages        = {{349--357}},
  title        = {{{Reconstruction of three-dimensional turned shaft surfaces with fractal functions}}},
  doi          = {{https://doi.org/10.1016/j.triboint.2015.11.028}},
  volume       = {{95}},
  year         = {{2016}},
}

@article{9772,
  abstract     = {{A profound description of friction in wheel--rail contact plays an essential role for optimization of traction control strategies, as input quantity for railway simulations in general and for the estimation of wear and rolling contact fatigue. A multitude of wheel--rail contact models exists, however, traction--creepage curves obtained from measurements show quantitative and qualitative deviations. There are several phenomena which influence the traction--creepage characteristics: Mechanisms resulting from surface roughness, frictional heating or the presence of interfacial fluids can have a dominating influence on friction. In this paper, a new wheel--rail contact model, accounting for these influential parameters, will be presented. The presented model accounts for the interaction of an interfacial fluid model for combined boundary and mixed lubrication of rough surfaces with a wheel--rail contact model that additionally accounts for frictional heating. A quantitative comparison with measurements found in the literature is not conducted, since the exact conditions of the measurements are mostly unknown and parameters can easily be adjusted to fit the measurements. Emphasis is placed on the qualitative behavior of the model with respect to the measurements and good agreement is found. The dependence of the maximum traction coefficient on rolling velocity, surface roughness and normal load is studied under dry and water lubricated conditions.}},
  author       = {{Tomberger, Christoph and Dietmaier, Peter and Sextro, Walter and Six, Klaus}},
  issn         = {{0043-1648}},
  journal      = {{Wear}},
  keywords     = {{Wheel--rail contact, Rolling contact, Friction, Interfacial fluid, Lubrication, Surface roughness, Contact temperature}},
  pages        = {{2 -- 12}},
  title        = {{{Friction in wheel--rail contact: A model comprising interfacial fluids, surface roughness and temperature}}},
  doi          = {{10.1016/j.wear.2010.10.025}},
  volume       = {{271}},
  year         = {{2011}},
}