Fraunhofer-Institut für Zuverlässigkeit und Mikrointegration IZM

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Characteristics of Li-ion micro batteries fully batch fabricated by micro-fluidic MEMS packaging

2022 , Hahn, R. , Ferch, M. , Kyeremateng, N.A. , Hoeppner, K. , 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.

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Bewertung der thermischen Alterung von Klebverbindungen

2021-06-16 , Hölck, Ole

Klebverbindungen sind zum Teil erheblichen Temperaturen ausgesetzt. Diese Belastungen können die Eigenschaften der Klebstoffe und somit die Beständigkeit der Klebverbindung über längere Zeiträume beeinträchtigen. Die Methode der dielektrischen Spektroskopie ermöglicht mit Hilfe von Monitorstrukturen, den Alterungszustand von Klebstoffen und -verbindungen zu bewerten.

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Methodology for Modeling the Energy and Material Footprint of Future Telecommunication Networks

2021 , Stobbe, L. , Nissen, N.F. , Druschke, J. , Zedel, H. , Richter, N. , Lang, K.-D.

This paper presents important methodical aspects in conjunction with the ongoing development of a novel multi-level-model in support of lifecycle environmental assessments of telecommunication networks. The new approach is, to some extent, emulating the OSI-layer model (Open Systems Interconnection), starting at the bottom with the main physical components, followed by product configurations, network architecture and control. On the top layer, the model scales through application and use case scenarios. This complex inventory model furthermore distinguishes between constructive (hardware-defined) elements on the one hand and operational (software-defined) elements on the other. By combining technical data as fixed values with application data as variable values, it is now possible to analyze the causal interaction between different technology generations, network configurations, and utilization intensity. It will allow identifying the best starting point for eco-design and improvement measures. Due to fact that the new methodology is not limited to energy consumption only, it supports a holistic understanding of the environmental impact of telecommunication networks.

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Cure Kinetics Modeling of a High Glass Transition Temperature Epoxy Molding Compound (EMC) Based on Inline Dielectric Analysis

2021 , Franieck, E. , Fleischmann, M. , Hölck, O. , Kutuzova, L. , 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.

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Catastrophic Optical Damage in Semiconductor Lasers: Physics and New Results on InGaN High-Power Diode Lasers

2022 , Hempel, Martin , Dadgostar, S. , Jimenez, J. , Kernke, R. , Gollhardt, Astrid , 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.

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Dorsal root ganglion (DRG) versatile stimulator prototype developed for use in locomotion recovery early clinical trials

2021-06-02 , Soloukey, S. , Huygen, F.J.P.M. , Harhangi, B.S. , Serdijn, W.A. , Kolovou-Kouri, Konstantina , Giagka, Vasiliki

This paper presents the development of a Dorsal Root Ganglion (DRG) stimulator system intended for use in early clinical trials for motor recovery after Spinal Cord Injury (SCI). It allows for independent control of multisite/multilevel bilateral (on both sides of the spinal cord) stimulation, it can supply a high output current of 25.4mA, and has the ability to program pulse sequences similar to actual locomotion patterns. These characteristics ultimately provide the required versatility for examining the effects of DRG stimulation on locomotion recovery, which is lacking in currently available commercial systems. The device is created using commercially available components to make the design reproducible by other research labs and to facilitate the critical approval procedure for use in a clinical research environment. Throughout the design phase, essential considerations regarding the safety of the participating patient, as well as of the medical personnel involved, were taken into account and these are analyzed and demonstrated in this paper. Such considerations are very rarely discussed in scientific literature and the authors consider that, apart from the design of the system itself, this discussion is a critical contribution of this paper.

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A Gel Polymer Electrolyte for Aluminum Batteries

2021 , Elia, G.A. , Acevedo, C.I. , Kazemi, R. , Fantini, S. , Lin, R. , Hahn, R.

Herein, the use of a gel polymer electrolyte (GPE) comprising polyacrylonitrile and 1-ethyl-3-methylimidazolium chloride:aluminum trichloride (EMIMCl:AlCl3) ionic liquid in aluminum batteries is investigated. The investigated GPE is characterized in terms of conduction properties. The obtained ionic conductivity values are suitable for battery applications. The ability of the GPE to sustain an efficient aluminum stripping deposition process is verified, revealing the need of a swelling process to enable the aluminum plating/stripping. The mitigation of the chloroaluminate corrosivity in the GPE is confirmed by evaluating the corrosion current of stainless steel 316 current collectors. The long-term ability of GPE to sustain the stripping deposition process is tested, evidencing a good Al/GPE interface stability. Finally, the GPE electrolyte suitability in the Al battery is verified by assembling an Al/GPE/pyrolytic graphite (PG) cell. The test cell shows a good cycling ability, demonstrating the suitability of the GPE electrolyte for the realization of aluminum batteries.

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Comparison of Chloroaluminate Melts for Aluminum Graphite Dual-Ion Battery Application

2021-11-06 , Elia, G.A. , Höppner, Katrin , Hahn, Robert

Herein, we report a comparison of aluminum graphite dual-ion cells (AGDICs) electrochemical characteristics employing the conventional 1-ethyl-3-methylimidazolium chloride:aluminum trichloride (EMIMCl : AlCl3) electrolyte and two popular deep eutectic solvents (DESs), namely urea : AlCl3 and acetamide:AlCl3. The three electrolytes' characteristics have been evaluated in terms of Al-stripping deposition capability and cycling behavior in AGDICs. The results evidence the EMIMCl : AlCl3's Al-stripping deposition and rate capability in AGDICs superior characteristics addressed to the lower viscosity and higher conductivity with respect to the urea : AlCl3 and acetamide:AlCl3. On the other hand, the urea : AlCl3 guarantees a much higher columbic efficiency in AGDICs, thanks to the superior electrochemical window stability.

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Fan-Out Wafer and Panel Level Packaging - A Platform for 3D Integration

2021 , Braun, T. , Becker, K.-F. , Töpper, M. , Aschenbrenner, R. , Schneider-Ramelow, M.

The constant drive to further miniaturization and heterogeneous system integration leads to a need for new packaging technologies that also allow large area processing and 3D integration with strong potential for low cost applications. Here, Fan-Out Wafer Level Packaging [FOWLP] is one of the latest packaging trends in microelectronics. The technology can be also used for multi-chip packages or System in Package (SiP). 3D integration is typically done by package on package (PoP) stacking where the electrical 3D routing is done by through mold (TMV) or through package vias (TPV) and a redistribution layer on both sides of the FOWLP. In summary the paper will give a review of the different technology approaches for through mold vias in a Fan-out Wafer or Panel Level Package.

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Recent Advances and Challenges of Nanomaterials-Based Hydrogen Sensors

2021 , Wang, B. , Sun, L. , Schneider-Ramelow, M. , Lang, K.-D. , 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.

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