Fraunhofer-Institut für Zuverlässigkeit und Mikrointegration IZM

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  • Publication
    On the optimization of the return current paths of signal vias in high-speed interposers and PCBs using the M3-approach
    ( 2014)
    Ndip, I.
    ;
    Löbbicke, K.
    ;
    Tschoban, C.
    ;
    Ranzinger, C.
    ;
    Richlowski, K.
    ;
    Contag, A.
    ;
    Reichl, H.
    ;
    Lang, K.-D.
    ;
    Henke, H.
    In this paper, the return-current paths of signal vias transiting multilayered stack-ups are optimized using the M3-approach (methodologies, models, measures). A methodology for suppressing the excitation of parallel-plate modes in these stack-ups is first proposed. The result of this methodology is a stack-up with well-defined paths for the returning conduction currents. Secondly, a model of the stack-up is developed and experimentally verified using measurement results. The model is then applied to study the impact of the impedance of the return-current paths on the effectiveness of the proposed stack-up in suppressing the excitation of cavity resonance modes. Based on the results of this study, appropriate designs measures for optimizing the return-current paths of the signal vias are derived. To demonstrate the advantages of these measures, they are applied to fabricate a new test board with the proposed stack-up. The measurement results show excellent signal transmission and no dips in the insertion loss of the signal via for frequencies up to 20 GHz.
  • Publication
    Design and evaluation of a passive self-breathing micro fuel cell for autonomous portable applications
    ( 2013)
    Weiland, M.
    ;
    Wagner, S.
    ;
    Hahn, R.
    ;
    Reichl, H.
    A micro fuel cell system designed to power complex autonomous systems with dynamic pulse-shaped loads like wireless sensor nodes is presented in this work. The requirements posed by the corresponding pulse load profiles are considered for the design of the passive self-breathing micro fuel cell. The performance of the fuel cell is mainly affected by the oxygen and water management which is influenced by the openings in the cathodic current collector. Due to the comparatively low average cell current the performance can be strongly improved by retaining water within the cell using a reduced opening ratio and thus improving the ionic conductivity of the electrolyte. The impact of the opening ratio is studied in the range between 54% and 0.007%. The total active area of the fuel cell is only 0.1 cm(2). Prototypes are realized using printed circuit board technology and wet chemical etching of the micro-structured current collectors. The cells were characterized with an exemplary load profile with a 10 ms load pulse and a 1 s pulse period. Successful operation was demonstrated for all cells for different current densities. A significant power improvement was achieved by reducing the opening ratio down to 0.3%. Under these circumstances a power density of 220 mW cm(-2) could be generated during the pulse. This is more than twice in comparison to cells with large opening ratios of 54% where only approx. 100 mW cm(-2) was obtained.
  • Publication
    Electromagnetic interactions between interconnected patch-ring (IPR) structures and planes in electronic packages and PCBs
    ( 2013)
    Ndip, I.
    ;
    Bierwirth, M.
    ;
    Guttowski, S.
    ;
    Reichl, H.
    ;
    Lang, K.-D.
    In this contribution, an interconnected patch ring (IPR) structure for noise suppression in the cavity of power-ground plane pairs is designed, fabricated and measured. The impact of electromagnetic interactions between an integrated/embedded IPR and power/ground planes in electronic packages and printed circuit boards is extensively studied. Our results reveal that the presence of a metal layer (i.e., a power/ground plane) above an IPR causes the excitation of parallel-plate modes and undesired coupling, which leads to the disappearance of the stopband of the IPR. Design methods to prevent this disappearance are investigated.
  • Publication
    Modeling and minimizing the inductance of bond wire interconnects
    ( 2013)
    Ndip, I.
    ;
    Öz, A.
    ;
    Guttowski, S.
    ;
    Reichl, H.
    ;
    Lang, K.-D.
    ;
    Henke, H.
    In this paper, a novel analytical model for calculating the partial self-inductance of bond wires in dependent on bonding parameters such as loop height, distance between bonding positions and the thickness of the metallization on which the wire is bonded, is derived for the first time. An excellent correlation is obtained between inductances extracted using our proposed model and those extracted using Ansys Q3D, with a maximum deviation of approximately 1%. Furthermore, methods for minimizing the inductance of bond wires, based on the definitions of loop and partial inductances are discussed. Test bond wire structures are designed, fabricated and measured to quantify the implemented method.
  • Publication
    Analysis and comparison of methods for extracting the inductance and capacitance of TSVs
    ( 2012)
    Ndip, I.
    ;
    Lobbicke, K.
    ;
    Zoschke, K.
    ;
    Guttowski, S.
    ;
    Wolf, J.
    ;
    Reichl, H.
    ;
    Lang, K.-D.
    Closed-form expressions and numerical/measurement-based methods for extracting the inductance (L) and capacitance (C) of Through Silicon Vias (TSVs) are analyzed and compared for frequencies up to 40 GHz. The discrepancies between the methods are discussed. The TSVs are designed, fabricated and measured. Good correlation is obtained between L and C values of TSVs extracted from RF measurements and electromagnetic field simulations.
  • Publication
    Impact of process tolerances on the performance of bond wire antennas at RF/microwave frequencies
    ( 2012)
    Ndip, I.
    ;
    Öz, A.
    ;
    Tschoban, C.
    ;
    Schmitz, S.
    ;
    Schneider-Ramelow, M.
    ;
    Guttowski, S.
    ;
    Reichl, H.
    ;
    Lang, K.-D.
    Due to the multitude of advantages bond wire antennas have over conventional planar antennas (especially onchip planar antennas), they have received much research attention within the last four years. The focus of the contributions made so far has been on exploiting different configurations of single-element and array bond wire antennas for short-range applications at RF/microwave frequencies. However, the effects of process tolerances of bond wires on the radiation characteristics of bond wire antennas have not been studied in published literature. Therefore in this paper, we investigate the impact of up to 20% fluctuations in the parameters of bond wires on the performance of 42 GHz and 60 GHz bond wire antennas. Our results reveal that the length and radius of bond wires are the most and least sensitive parameters, respectively. Furthermore, the severity of the impact of process tolerances depends on the impedance bandwidth of the original antenna, before considering the tolerances. For example, a 10% change in the length of a bond wire causes the resonance frequency of a 42 GHz antenna to be shifted out of the specified 3GHz bandwidth (40.5 GHz-43.5 GHz) required for point-to-point communication. However, although a 10% change in length of a bond wire yields a 2.5 GHz shift in the resonance frequency of a 60 GHz bond wire antenna, it doesn't completely detune the antenna because of the original 6 GHz bandwidth available, prior to the fluctuation. Therefore, to prevent the impact of process tolerances from severely degrading the performance bond wire antennas, these antennas should be designed to have larger bandwidths than specified. For experimental verification, a bond wire antenna was designed, fabricated and measured. Very good correlation was obtained between measurement and simulation.
  • Publication
    Characterization of interconnects and RF components on glass interposers
    ( 2012)
    Ndip, I.
    ;
    Töpper, M.
    ;
    Löbbicke, K.
    ;
    Öz, A.
    ;
    Guttowski, S.
    ;
    Reichl, H.
    ;
    Lang, K.-D.
    As a result of their myriad of advantages over silicon and other conventional substrate technologies, glass substrates have received significant attention from the electronic packaging and system integration community worldwide. So far, most of the research effort on glass has concentrated on developing methods for fabricating cylindrical through glass vias (TGVs). However, to fully evaluate the potential of glass as an interposer material for microelectronic systems with computing and communication functions, an extensive characterization of interconnects and RF components on these substrates must be carried out. In this contribution, we go beyond state-of-the-art research and present an in-depth characterization of TGVs, coplanar lines and 60 GHz coplanar excited patch antennas on two glass substrates. One of these substrates has a low alkaline content (Borofloat33®) and the other is alkaline-free (AF32®). The effects of these glass materials on the RF performance of TGVs, coplanar lines and 60 GHz antennas are extensively studied, and recommendations for performance optimization are proposed. For experimental verification, test samples are fabricated and measured. Very good correlation is obtained between the measurement and simulation results from 100 MHz to 100 GHz.
  • Publication
    Systematic design and optimization of bond wire antennas using the M3-approach
    ( 2012)
    Ndip, I.
    ;
    Guttowski, S.
    ;
    Reichl, H.
    ;
    Lang, K.D.
    In this paper, all the three steps required for implementing the M3-approach are illustrated for bond wire antennas. First, a methodology for efficient and accurate electromagnetic modeling of bond wire antennas, based on parameterized models of the shape and length of bond wires, is developed. The resulting model is experimentally verified and applied to extensively study the RF performance of bond wire antennas. Based on these studies, reliable design measures are derived.
  • Publication
    Design and evaluation of a passive self-breathing micro fuel cell for autonomous portable applications
    ( 2011)
    Weiland, M.
    ;
    Wagner, S.
    ;
    Hahn, R.
    ;
    Reichl, H.
    A micro fuel cell specifically designed to power complex intelligent autonomous portable systems is presented in this work. The requirements posed by the corresponding pulse shaped load profiles are analyzed and considered for the design of the passive selfbreathing micro fuel cell. Prototypes with an active area of 0.1 cm2 are built based on printed circuit board technologies and wet etching technologies are used for micro structured current collectors. Successful operation of the cell was demonstrated with pulse power densities of up to 220 mW cm-2.
  • Publication
    Modeling and optimization of bond wires as transmission lines and integrated antennas at RF/microwave frequencies
    ( 2011)
    Ndip, I.
    ;
    Tschoban, C.
    ;
    Schmitz, S.
    ;
    Ostmann, A.
    ;
    Schneider-Ramelow, M.
    ;
    Guttowski, S.
    ;
    Reichl, H.
    ;
    Lang, K.-D.
    In this contribution, the authors present a systematic approach for optimizing the RF performance of bond wires. First of all, a comparative analysis between two of the most commonly used bond wire signal configurations, the two conductor and coplanar configurations, is done. Their results reveal that although the partial self-inductance of the signal wires is the same in both configurations, the partial mutual inductance of the coplanar configuration is higher, resulting in a smaller loop inductance. Consequently, the return and insertion losses are smaller. By reducing the distance between the signal and return currents, they further reduced the loop inductance, and significantly optimized the coplanar configuration. For example, considering a 1 mm long bond wire with a diameter of 25 micron, they successfully kept the power lost through the coplanar configuration below 10 % at 15 GHz, in comparison to the 70 % power lost through the two-conductor configuration at the same frequency. However, more than 30 % of the entire power is lost through the optimized coplanar configuration at 40 GHz. At such frequencies where bond wires are unsuitable to be used as transmission lines, they demonstrate that they are very efficient as antennas by designing a half-loop integrated bond wire antenna having a bandwidth of 3 GHz. For experimental verification, test samples were designed, fabricated and measured. An excellent correlation was obtained between simulation and measurement.