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Author: Warmuth, Jens ×

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Now showing 1 - 6 of 6
  • Publication
    Failure mechanism detection algorithm with MOSFET body diode
    ( 2021)
    El Khatib, Mohamad
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    Reitz, Sven orcid-logo
    ;
    Warmuth, Jens
    Autonomous driving is playing a big role in the automotive industry and defines the future of mobility on a big scale. However, autonomous driving faces several challenges, such as the performance of artificial intelligence and hardware reliability. To ensure safe functionality, the reliability of the electronic components plays an essential role and must be taken into consideration. One aspect of studies that analyze the electronics reliability is the observation of the system's thermal impedance and deriving a correlation between the failure mechanisms and thermal impedance behavior. In recent times, several new approaches have been suggested to improve the electronics reliability. Many studies were carried out to determine the effect of solder voiding on the thermal impedance of chip-level packages. In this paper, a defect diagnosis and physical damage detection method for electronic packaging are studied by measuring the thermal impedance through the body diode of the device under test (DUT). The detection method uses MOSFET body diode temperature measurements to investigate different failure mechanisms at different locations in the electronic packaging system.
  • Publication
    Thermal On-Board Spectroscopy: Thermal Impedance Simulation Using FEM and Thermal Modelling
    ( 2020)
    Khatib, Mohamad el
    ;
    Reitz, Sven orcid-logo
    ;
    Warmuth, Jens
    Autonomous driving, together with electromobility, is the next major innovation step in future mobility. Not only does it add a gain in comfort but also increases vehicle and road safety. In addition to the more obvious challenges, such as the performance of algorithms (artificial intelligence), there are also major open issues regarding hardware reliability. A computer-controlled vehicle is directly relying on the functionality of its electronic components. In completely autonomous operation, with lack of human supervision, the functional failure of electronic components becomes a central issue. That's why, a safe electronic surveillance system must take over the role of human supervision in the future. To improve the electronics' functional safety, much research has already been done in recent years. On a basic level, the on-board sensor implementation to observe the system temperature and observing the thermal management for electronic devices is a well advanced topic and has been existing for a while in the automotive industry in general. However, an "intuitive" early detection of physical defects was rarely in focus. In this paper, a defect diagnosis and physical damage detection method for electronics packaging and assembly is being presented. This process of thermal on-board spectroscopy uses intelligent temperature sensors to monitor the status of electronic assemblies and ECUs during vehicle use by analyzing the thermal impedance and the time-dependent thermal changes of the electronic packaging system.
  • Publication
    Reliability testing and stress measurement of QFN packages encapsulated by an open-ended microwave curing system
    ( 2019)
    Adamietz, Raphael
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    Desmulliez, Marc P.Y.
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    Pavuluri, Sumanth Kumar
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    Tilford, Tim
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    Bailey, Chris
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    Schreier-Alt, Thomas
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    Warmuth, Jens
    In this paper, the influence of microwave curing on the reliability of a representative electronic package is examined by reliability testing and measurement of residual stresses. A LM358 voltage regulator die was mounted to an open Quad Flat No-leads package (QFN) for reliability testing. For the stress measurement, a specifically designed stress measurement die was mounted to the QFN package. The chips were encapsulated with ULHysol EO1080 thermosetting polymer material. Curing was performed using an open-ended microwave oven system equipped with in situ temperature control. Three different temperature profiles for microwave curing were selected according to the requested degree of cure and chemical composition of the cured material. A convection cure profile was selected for the control group samples. Thermal cycling and HAST tests were performed on a total number of 80 chips. 95 QFN packages with stress measurement chips were also manufactured. Increased lifetime expectancy of the microwave cured packaged chips was experimentally demonstrated and measured between 62% to 149% increased lifetime expectancy after Temperature Cycling Test (TCT), and between 63% and 331% after highly Accelerated Ageing Test (HAST) and TCT compared to conventionally cured packages. Analysis of specifically designed stress test chips showed significantly lower residual stresses ranging from 26 MPa to 58.3 MPa within the microwave cured packages compared to conventionally cured packaged chips which displayed residual stresses ranging from 54 MPa to 80.5 MPa. This article therefore provides additional confidence in the industrial relevance of the microwave curing system and its advantages compared to traditional convection oven systems.
  • Publication
    Analysis of 28 nm SRAM cell stability under mechanical load applied by nanoindentation
    ( 2018)
    Clausner, André
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    Schlipf, Simon
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    Kurz, G.
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    Otto, M.
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    Paul, J.
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    Giering, Kay-Uwe
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    Warmuth, Jens
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    Lange, André orcid-logo
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    Jancke, Roland
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    Aal, A.
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    Rosenkranz, Rüdiger
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    Gall, Martin
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    Zschech, Ehrenfried
    28 nm high-k metal gate CMOS SRAM circuits were subjected to controlled mechanical load by nanoindentation. A thinning procedure down to about 35 mum of remaining Si enables high stress fields in the vicinity of operational SRAM cells which were embedded in a flip chip package and subjected to loads from the Si backside. It was found that the loading leads to an increase of the bit cell fail probability around the nanoindentation point. The loading effects are reversible, i.e. failures are completely released upon load relieve. The results attained here provide a quantitative estimate about the influence of package-related stress on performance and reliability of microelectronic products during field operation, shedding light on CPI-and CBI-effects.
  • Publication
    Prediction of SRAM reliability under mechanical stress induced by harsh environments
    ( 2018)
    Warmuth, Jens
    ;
    Giering, Kay-Uwe
    ;
    Lange, André orcid-logo
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    Clausner, André
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    Schlipf, Simon
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    Kurz, Gottfried
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    Otto, Michael
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    Paul, Jens
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    Jancke, Roland
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    Aal, Andreas
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    Gall, Martin
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    Zschech, Ehrenfried
    On the example of a 28nm SRAM array, this work presents a novel reliability study which takes into account the effect of externally applied mechanical stress in circuit simulations. This method is able to predict the bit failures caused by the stress via the piezoresistive effect. The stability of each single SRAM cell is simulated using static noise margin. Finally, the whole array's behavior is reproduced by including device parameter variations in Monte-Carlo simulations. The results show good agreement with corresponding experiments in which mechanical stress was introduced into the SRAM array by indentation. This validates the presented simulation method for future use in the design of electronic products, especially for harsh environment applications, where high stress is expected.
  • Publication
    Prediction and compensation of reference voltage shift in IC sensors due to mechanical stress
    ( 2017)
    Warmuth, Jens
    ;
    Schreier-Alt, Thomas
    With the continuing miniaturization and integration of sensors challenges besides the scaling of the sensor itself arise especially for high precision measurements. Here the problem often lies in the growing impact of environmental influences compared to the smaller usable signals. In this talk the challenge of obtaining online high precision voltage measurements in the automotive environment using only ICs is discussed. The focus is set on the impact of mechanical stress on the reference voltage circuit needed to convert the analogue sensor signal into digital data. An approach of combining results of specialized measurement equipment to determine the expected use case specific stress influence with FEA and circuit simulations to develop a stress resilient on-chip voltage reference is presented.