Fraunhofer-Institut für Zuverlässigkeit und Mikrointegration IZM

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  • Publication
    Characteristics of Li-ion micro batteries fully batch fabricated by micro-fluidic MEMS packaging
    ( 2022)
    Hahn, R.
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    Ferch, M.
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    Kyeremateng, N.A.
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    Hoeppner, K.
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    Marquardt, K.
    ;
    Elia, G.A.
    A cost-effective and reliable technology allowing extreme miniaturization of batteries into glass chips and electronic packages has been developed, employing a dispense-print process for battery electrodes and liquid electrolyte. Lithium-ion micro-batteries (active area 6 × 8 mm2, 0.15-0.3 mAh) with interdigitated electrodes were fabricated, tested and finally compared with the traditional battery architecture of stacked electrodes. Commercial graphite and lithium titanate anode as well as layered nickel cathode materials were used. All the processes for the micro-battery fabrication were established during this work; in particular the micro fluidic electrolyte filling process that allows simultaneous electrolyte supply to all cells on a planar substrate. Electrode mass reproducibility was sufficient for adequate electrode balancing. Current capability similar to the conventional face-to-face electrode configuration was achieved with interdigital electrodes that can be fabricated much easily on a substrate level. The cells were successfully cycled; several 100 cycles can be achieved. Additional results of life-time characteristics and electrochemical impedance spectroscopy are presented as well. These rechargeable micro-batteries can be used for future extremely miniaturized electronic products.
  • Publication
    Catastrophic Optical Damage in Semiconductor Lasers: Physics and New Results on InGaN High-Power Diode Lasers
    ( 2022)
    Hempel, M.
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    Dadgostar, S.
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    Jimenez, J.
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    Kernke, R.
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    Gollhardt, A.
    ;
    Tomm, J.W.
    Among the limitations known from semiconductor lasers, catastrophic optical damage (COD) is perhaps the most spectacular power-limiting mechanism. Here, absorption and temperature build up in a positive feedback loop that eventually leads to material destruction. Thus, this is truly an ultimate mechanism, and its continued suppression is a manifestation of progress in device design and manufacturing. After an overview of the current state of knowledge, new investigations of COD using artificially micrometer-sized starting points created within the active zone in the cavity of 450 nm GaN semiconductor lasers are reported on. Defect growth mechanisms and characteristics are studied during 800 ns current pulses. The defect growth follows the highest light intensity. Secondary defect patterns are studied: complete destruction of the active zone and generation of a point defect cloud at least ≈10 μm into the remaining surrounding material. Extremely large angles (>90°) of damage growth are traced back to the material properties and the aging scenario. The results are compared with former experiments with GaAs-based lasers.
  • Publication
    Cure Kinetics Modeling of a High Glass Transition Temperature Epoxy Molding Compound (EMC) Based on Inline Dielectric Analysis
    ( 2021)
    Franieck, E.
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    Fleischmann, M.
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    Hölck, O.
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    Kutuzova, L.
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    Kandelbauer, A.
    We report on the cure characterization, based on inline monitoring of the dielectric parameters, of a commercially available epoxy phenol resin molding compound with a high glass transition temperature (>195 °C), which is suitable for the direct packaging of electronic components. The resin was cured under isothermal temperatures close to general process conditions (165-185 °C). The material conversion was determined by measuring the ion viscosity. The change of the ion viscosity as a function of time and temperature was used to characterize the cross-linking behavior, following two separate approaches (model based and isoconversional). The determined kinetic parameters are in good agreement with those reported in the literature for EMCs and lead to accurate cure predictions under process-near conditions. Furthermore, the kinetic models based on dielectric analysis (DEA) were compared with standard offline differential scanning calorimetry (DSC) models, which were based on dynamic measurements. Many of the determined kinetic parameters had similar values for the different approaches. Major deviations were found for the parameters linked to the end of the reaction where vitrification phenomena occur under process-related conditions. The glass transition temperature of the inline molded parts was determined via thermomechanical analysis (TMA) to confirm the vitrification effect. The similarities and differences between the resulting kinetics models of the two different measurement techniques are presented and it is shown how dielectric analysis can be of high relevance for the characterization of the curing reaction under conditions close to series production.
  • Publication
    Towards a wireless system that can monitor the encapsulation of mm-sized active implants in vivo for bioelectronic medicine
    ( 2021)
    Rodrigues, G.
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    Neca, M.
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    Silva, J.
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    Brito, D.
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    Rabuske, T.
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    Fernandes, J.
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    Mohrlok, R.
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    Jeschke, C.
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    Meents, J.
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    Nanbakhsh, K.
    ;
    Giagka, V.
    Active neural interfaces for bioelectronic medicine are envisioned to be mm-sized. Such miniaturization is at the moment hampered by the available wireless power techniques as well as the large volume the conventional hermetic packaging adds to the implant. Alternatively, conformal coatings are being explored for the protection of the implant electronics. Such approach has the potential to allow for the use of RF (radio-frequency) energy for powering, and miniaturization to the extreme of having a single IC (integrated circuit) as the whole implant (single chip implants). The longevity of conformal encapsulation can be assessed using accelerated soak tests in a dedicated apparatus in vitro, but these are usually not sufficient, as they fail to reveal additional failure modes that manifest themselves in vivo. Therefore, to investigate the performance of conformal coatings in vivo a compact, mm-sized wireless monitoring system is required. The development of such a system exhibits several challenges, mostly concerned with how to receive enough energy in such a small implant to power the monitoring sensor and transmit information regarding the integrity of the coating. In this paper we propose a system architecture for such a mm-sized wireless system, suitable for medium-to-Iong term monitoring of implants, by designing the whole system as a single monolithic IC. It is shown, by experiments, simulation or analytically that the identified challenges are possible to overcome, allowing to proceed towards the practical prototype.
  • Publication
    Quantifying the environmental impact of clustering strategies in waste management: A case study for plastic recycling from large household appliances
    ( 2021)
    Bracquené, E.
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    Martinez, M.G.
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    Wagner, E.
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    Wagner, F.
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    Boudewijn, A.
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    Peeters, J.
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    Duflou, J.
    The complex composition of waste electrical and electronic equipment (WEEE) plastics represents a challenge during post-consumption plastic recycling. A single WEEE category, e.g. large household appliances (LHA), can contain several different plastic types with overlapping material properties, making the sorting of individual plastics a challenge. Significant increases in plastic recovery rates can be expected by clustering product categories, as clustering can avoid mixing of non-compatible plastics with overlapping material properties. For this purpose, a life cycle assessment (LCA) is conducted to investigate the influence of different clustering strategies on the environmental performance of waste treatment and the production of recycled plastic from LHA waste stream. To assure comparability between waste treatment scenarios a system expansion approach is applied, and to allocate the burden of shared processes over the first and second use cycle of the material partitioning is applied. Results show that an increased separation of product clusters by plastic type can improve the plastic recovery rate from 5.8% to 47.1% and reduce the overall environmental impact, quantified with the ReCiPe (2016) method, by up to 23%. The environmental impacts of using recycled plastics from LHA waste can be reduced by 27 to 38% compared to single-use plastic. The holistic approach used in this study demonstrates (1) the potential benefits of implementing product clustering strategies for LHA plastic recycling, (2) the relevance of different allocation procedures when integrating recycling into an LCA, (3) the importance of using less virgin material and avoiding final waste treatment, and (4) the limitation of the recycling system to reduce the environmental burden associated with products.
  • Publication
    Recent Advances and Challenges of Nanomaterials-Based Hydrogen Sensors
    ( 2021)
    Wang, B.
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    Sun, L.
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    Schneider-Ramelow, M.
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    Lang, K.-D.
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    Ngo, H.-D.
    Safety is a crucial issue in hydrogen energy applications due to the unique properties of hydrogen. Accordingly, a suitable hydrogen sensor for leakage detection must have at least high sensitivity and selectivity, rapid response/recovery, low power consumption and stable functionality, which requires further improvements on the available hydrogen sensors. In recent years, the mature development of nanomaterials engineering technologies, which facilitate the synthesis and modification of various materials, has opened up many possibilities for improving hydrogen sensing performance. Current research of hydrogen detection sensors based on both conservational and innovative materials are introduced in this review. This work mainly focuses on three material categories, i.e., transition metals, metal oxide semiconductors, and graphene and its derivatives. Different hydrogen sensing mechanisms, such as resistive, capacitive, optical and surface acoustic wave-based sensors, are also presented, and their sensing performances and influence based on different nanostructures and material combinations are compared and discussed, respectively. This review is concluded with a brief outlook and future development trends.
  • Publication
    RF Modeling and Measurement of a Novel Aperture-Coupled Hybrid Glass-Silicon 5G Antenna Array
    ( 2021)
    Le, T.H.
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    Rossi, M.
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    Ndip, Ivan
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    Kaiser, Michael
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    Manier, Charles-Alix
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    Gernhardt, Robert
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    Oppermann, Hermann
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    Lang, Klaus-Dieter
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    Reichl, Herbert
    In this work, the electromagnetic modelling and measurement of a novel aperture-coupled hybrid glass-silicon 1x2 antenna array is presented. The patch elements are located under a glass substrate, which is placed on a silicon layer. The antenna array is fed using aperture coupling. A cavity is etched in the silicon layer to reduce the impact of silicon, and thus ensures significant improvement of the antenna efficiency and gain. The proposed antenna was fabricated and measured. Very good correlation is obtained between simulation and measurement.
  • Publication
    Washable, Low-Temperature Cured Joints for Textile-Based Electronics
    ( 2021)
    Szalapak, J.
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    Scenev, V.
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    Janczak, D.
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    Werft, L.
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    Rotzler, S.
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    Jakubowska, M.
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    Krshiwoblozki, M. von
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    Kallmayer, C.
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    Schneider-Ramelow, M.
    Low-temperature die-attaching pastes for wearable electronics are the key components to realize any type of device where components are additively manufactured by pick and place techniques. In this paper, the authors describe a simple method to realize stretchable, bendable, die-attaching pastes based on silver flakes to directly mount resistors and LEDs onto textiles. This paste can be directly applied onto contact pads placed on textiles by means of screen and stencil printing and post-processed at low temperatures to achieve the desired electrical and mechanical properties below 60 °C without sintering. Low curing temperatures lead to lower power consumption, which makes this paste ecological friendly.
  • Publication
    Influence of Ball Size and Geometry on the Reliability and RF Performance of mmWave System-in-Package: A Simulation Approach
    ( 2021)
    Dilek, S.
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    Ndip, I.
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    Rossi, M.
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    Tschoban, C.
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    Kuttler, S.
    ;
    Wittler, O.
    ;
    Lang, K.-D.
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    Goetze, C.
    ;
    Berger, D.
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    Wieland, M.
    ;
    Schneider-Ramelow, M.
    Solder ball reliability is a long-discussed topic in microelectronic packaging. With new package types needed for mmWave applications a trade-off between reliability and RF performance may arise, when the solder ball geometry has to be selected for specific package assemblies. In this work, the lifetime for different solder ball geometries is investigated within a numerical simulation workflow, by means of a sensitivity analysis in which the ball diameter, pad sizes and stand-off distance are varied. Next to lifetime estimations, 3D full-wave simulations have been applied to analyze the RF performance of the structures under investigation at 77-79 GHz (E-band) center frequencies relevant for automotive radar applications. Finally, the trade-off between RF performance and reliability is illustrated and quantified.
  • Publication
    Thermo-mechanical-optical coupling within a digital twin development for automotive LiDAR
    ( 2021)
    Tavakolibasti, Majid
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    Meszmer, Peter
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    Böttger, Gunnar
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    Kettelgerdes, Marcel
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    Elger, Gordon
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    Erdogan, Hüseyin
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    Seshaditya, A.
    ;
    Wunderle, Bernhard
    In the current work, the steps of the development of a Reduced Complexity Model (RCM) of a Light Detection and Ranging (LiDAR) system and the requirements for the preparation of a Digital Twin (DT) from such system are discussed. Preliminary thermal and optical simulations are presented, along with different concepts for cooling of the system. Additionally, the current barrier of coupling of the thermo-mechanical simulations produced in Ansys Mechanical and optical simulations done by Zemax OpticStudio is discussed.