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PublicationVery-Thin System-in-Package Technology for Structural Analysis( 2019)The integration of very-thin electronic systems will enable new application fields like structural analysis of components used in aviation, windmills or other critical applications. Presented are two integration options, by using flexible substrates or a RDLFirst packaging approach suitable for multiple device assembly. The RDLFirst is very thin and the flip-chip devices can be thinned also, so that the overall system gets very thin. One main difference to flexible substrate is the possible line space, which is in the region of 100um for flexible substrates and down to some um for RDLFirst.
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PublicationEnergy harvesting and conversion - applications of piezoelectric transformer and transducer MEMS( 2018)A systematic investigation of the feasibility to integrate complete piezo-based power supply on silicon was done. Up to now, fully integrated off-line power supplies on chip are available as products for below 1 Watts. Higher power levels up to 10 Watts and more are strongly desired for many miniaturized applications as Off-Line LED light sources, integrated power supplies for communication devices as iPhone, portable devices for medical applications, portable beamers an others. The integration of high-efficient power supplies based on magnetic transformers (PT) including galvanic isolation is limited due to the physics of electromagnetism. Piezoelectric transformers can be integrated as MEMS when PZT material is applied on silicon to a height of several Micrometers to form an oscillating device which will be processed after micro-bonding in an etching process. Although power density of discrete PT is already high, it can be increased by a factor of 100 to 1000 in integrated devices on silicon taking advantage of uniform crystal structure of sputtering process and improved heat removal through silicon. Serial piezo-transformer-strings allow for high isolating voltage up to 4 kV and provide efficiency up to 95% or more, but unfortunately on the cost of significant large chip area. However, piezoelectric transformers will gain higher acceptance in power converters if a magnetic-field-free environment is requested as for magnetic resonance tomography. Promising piezoelectric applications can be found for transformer-transducer units to harvest ultrasonic energy, preferably in medical therapy-diagnosis applications, but further, in industrial autonomous sensor supplies with avoidance of electromagnetic disturbance. Piezoelectric energy harvesting becomes attractive using ultrasonic energy harvester MEMS with wide range frequency excitation using permanent magnet cantilever construction. Ultrasonic MEMS loudspeakers are miniaturized alternatives to traditional magnetic devices. The advantage of piezoelectric MEMS applications will result in an extreme miniaturization compared to conventional power conversion by magnetic or electrostatic solutions. High reliability including intelligent integrated functions in some cases may improve the practicability of piezoelectric MEMS.
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PublicationInterposer-based smartcard system with active wireless communication( 2017)The trend to integrate more and more functionality into smaller and smaller devices is still ongoing. Most smart systems are communicating wireless, while non-stationary systems require an integrated power supply. This paper presents a system, which is integrated into a standardized smartcard format and is capable of active wireless transmission and can be used for location detection, ranging, localization or access control. The dimension of an ISO 7816 ID-1 smartcard, which is the most common used smartcard, is about 86 by 54 mm. Integrating a smart system on this dimensions is not an problem. But the maximal height of a smartcard is only 0.76 millimeters. So integrating functionality by using multiple components is still an issue.
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PublicationMiniaturization of power converters by piezoelectric transformers - chances and challenges( 2017)A systematic approach of the feasibility to integrate complete piezo-based power supply on silicon is the focus of research activities within Fraunhofer EAS, ISIT an IZM. Up to now, fully integrated off-line power supplies on chip are available for below 1 Watts, e.g. from Texas Instruments. Higher power levels up to 10 Watts and more are strongly desired for many miniaturized applications as Off-Line LED light sources, integrated power supplies for communication devices as iPhone, portable devices for medical applications, portable beamers an others. The integration of high-efficient power supplies based on magnetic transformers (PT) including galvanic isolation is limited due to the physics of electromagnetism. Piezoelectric transformers can be integrated when PZT material is applied on silicon to a height of several Micrometers to form an oscillating device which will be processed after micro-bonding in an etching process. Although power density of discrete PT is already high, it can be increased by a factor of 100 to 1000 in integrated devices on silicon taking advantage of uniform crystal structure of sputtering process and improved heat removal through silicon. The driving topology can be formed by high-voltage Mosfets or multi-level low-voltage Mosfet topology based on SOI or GaN on Si and integrated micro-inductors in the future. Serial piezo-transformer-strings allow for high isolating voltage up to 4 kV and provide efficiency up to 95% or more. Synchronous rectifying devices can be formed by low-voltage Mosfets at the output stage of the power supply. The advantage will be an extreme miniaturization compared to discrete power supplies, reduction of blocking capacitors by interleaving techniques, and thus, high reliability including intelligent integrated functions as stabilization circuits, sensors or control.
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PublicationEntwurfsmethoden für verbesserte robuste Batteriemanagementsysteme. Teilvorhaben(Fraunhofer IIS / EAS, 2016)
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PublicationVertical interconnections using through encapsulant via (TEV) and through silicon via (TSV) for high-frequency system-in-package integration( 2014)In this paper we investigate two vertical interconnect options for high-frequency system-in-package (SiP) integration: through encapsulant via (TEV) applied to the embedded wafer level ball grid array (eWLB) technology and through silicon via (TSV). We compare both solutions in terms of size and electrical performance. We use analytic expressions and electromagnetic simulations for our analysis and present measurement results of selected structures for verification. The results show that the choice of TEV and TSV depends on application and cost window.
