Fraunhofer-Institut für Zuverlässigkeit und Mikrointegration IZM

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  • Publication
    Energy harvesting and conversion - applications of piezoelectric transformer and transducer MEMS
    ( 2018)
    Radecker, Matthias
    ;
    Kunzmann, Jan
    ;
    Quenzer, Hans-Joachim
    ;
    Gu-Stoppel, Shan-Shan
    ;
    Yang, Yujia
    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.
  • Publication
    Panel Level Packaging for Power Applications
    ( 2017)
    Aschenbrenner, Rolf
    Traditional manufacturing of packages like BGAs, QFNs or QFPs is performed on lead frame formats. The number of packages on a lead frame is rather limited. The introduction of Wafer-Level Packaging (WLP) allowed a significant reduction of cost, especially for small chips due to the simultaneous processing of thousands of Chip Size Packages (CSPs). However CSPs are limited to the die size, which means that chips with a high number of I/Os cannot be redistributed to a relaxed interconnect pitch. This can only be achieved by a fan-out redistribution. The introduction of Fan-Out Wafer Level Packaging (FO-WLP) allowed the efficient manufacturing of fan-out packages on wafer formats up to 300 mm. Nevertheless Smart Phones, Wearables and similar applications ask for further cost reduction, which means more efficient processes on large production formats, i e. the introduction of Panel Level Packaging (PLP). A highly efficient method to realize PLP is the already established embedding technology. It uses Printed Circuit Board (PCB) materials, processes and equipment. PLP embedding is already performed in volume manufacturing on large PCB formats of 18""x24"" (456x610 mm²). Today's applications are power packages for MOSFETs, power System-in-Packages (SiPs) and DC/DC converter modules. Manufacturing of larger BGA packages with embedded chips will start soon. Besides its high potential for cost reduction the PLP embedding offers high reliability and unique features like 3D integration of sensors with data processing units or the combination of power switches (IGBTs or MOSFETs) together with drivers and capacitors in one package. This presentation will show examples of PLP embedding from volume manufacturing as well as results of recent research activities. In particular current R&D effort to realize power modules for voltages up to 600 V with integrated electrical isolation will be described. A further example is the realization of a highly integrated intelligent camera module with embedded 32 bit signal processor and memory.
  • Publication
    Miniaturization of power converters by piezoelectric transformers - chances and challenges
    ( 2017)
    Radecker, Matthias
    ;
    Quenzer, Hans-Joachim
    ;
    Gu-Stoppel, Shan-Shan
    ;
    Reich, Torsten
    ;
    Buhl, René
    ;
    Yang, Yujia
    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.
  • Publication
    Panel Level Embedding for Power and Sensor Applications
    ( 2017)
    Aschenbrenner, Rolf
    Traditional manufacturing of packages like BGAs, QFNs or QFPs is performed on leadframe formats. The number of packages on a leadframe is rather limited. The introduction of Wafer-Level Packaging (WLP) allowed a significant reduction of cost, especially for small chips due to the simultaneous processing of thousands of Chip Size Packages (CSPs). However CSPs are limited to the die size, which means that chips with a high number of I/Os cannot be redistributed to a relaxed interconnect pitch. This can only be achieved by a fan-out redistribution. The introduction of Fan-Out Wafer Level Packaging (FO-WLP) allowed the efficient manufacturing of fan-out packages on wafer formats up to 300 mm. Nevertheless Smart Phones, Wearables and similar applications ask for further cost reduction, which means more efficient processes on large production formats, i e. the introduction of Panel Level Packaging (PLP). A highly efficient method to realize PLP is the already established embedding technology. It uses Printed Circuit Board (PCB) materials, processes and equipment. PLP embedding is already performed in volume manufacturing on large PCB formats of 18""x24"" (456x610 mm²). Today's applications are power packages for MOSFETs, power System-in-Packages (SiPs) and DC/DC converter modules. Manufacturing of larger BGA packages with embedded chips will start soon. Besides its high potential for cost reduction the PLP embedding offers high reliability and unique features like 3D integration of sensors with data processing units or the combination of power switches (IGBTs or MOSFETs) together with drivers and capacitors in one package. This presentation will show examples of PLP embedding from volume manufacturing as well as results of recent research activities. In particular current R&D effort to realize power modules for voltages up to 600 V with integrated electrical isolation will be described. A further example is the realization of a highly integrated intelligent camera module with embedded 32 bit signal processor and memory.
  • Publication
    Modular power electronics, realized by PCB embedding technology
    ( 2017)
    Böttcher, Lars
    ;
    Karaszkiewicz, Stefan
    ;
    Manessis, Dionysios
    ;
    Ostmann, Andreas
    This paper will describe the use of embedded die technologies for various application fields. The main focus of the paper will be the development work within the European funded project EmPower, which concentrates on power electronic applications. Here, three different power levels are of interest: - 50W single die packages with fast rectifier diodes - 500W power modules for electric bicycle application - 50kW power modules for HEV and EV application All three application fields are based on a similar concept. The so called power core provides the base for the package/module. This power core contains the embedded semiconductor(s) and is manufactured using printed circuit board processing on a large panel format of 18 by 24 inches. Electrical contacts to the embedded dies are made by laser drilled micro vias and copper filling. A major advantage of such a direct copper contact, compared to the conventionally used wire bond, is its high reliability and the improved electrical performance. By the reduction of the inductance of these interconnects, switching losses can be reduced significantly, allowing an improved and faster switching. For the higher power modules additionally thermal management is required. Here a construction of IMS substrates and the power core is chosen. This construction enables a double sided cooling and also the electrical isolation of the module to the cooler. The connection between power core and IMS substrates is made by low temperature and low pressure Ag sintering. All three applications fields will be described in detail. This will cover the development of the manufacturing process for all three power class demonstrators, as well as detailed structural analysis and reliability testing. The development work toward highly reliable modules will be discussed in depth. Finally the resulting demonstrators for 50W, 500W and 50kW power application and their characteristics will be presented in detail.
  • Publication
    Materials and Concepts for Textile Sensor Systems
    ( 2017)
    Aschenbrenner, Rolf
    ;
    Kallmayer, Christine
    In recent years, the integration of electronics in textiles has gained increasing attention. In order to make the step towards industrial manufacturing of wearable electronics as well as smart technical textiles it is necessary to develop modular concepts as well as integration processes suitable for high volume production. By introducing new concepts for electronic packaging and interconnects, a seamless, comfortable and robust integration of electronics in textiles is possible. Besides the large area technical textiles with integrated sensors for structural health monitoring and environmental conditions, smart garments for the monitoring of movement and physiological parameters play the most important role. These systems can cover various aspects: prevention, diagnosis, therapy and rehabilitation. For these applications sensors can be textile based but also miniaturized conventional sensors can be required. Different polymers and metals can be used as yarns, printable pastes or foils to realize a broad range of measurement principles. While the performance of textile and polymer sensors cannot compete with conventional sensors, the mechanical properties of these materials allow completely new applications, e.g. in strain measurements. The mechanical reliability is essential for smart textiles. Especially different degrees of stretchability and drapeability have to be achieved while maintaining the sensor properties. Various diagnostic sensor systems have been developed over the last decade and the feasibility of ECG and EMG is proven, there are not a lot of products on the market yet. Systems which fulfill lower requirements can be used e.g. in prevention. Currently a major trend in prevention can be seen in posture and movement monitoring as the number of patients having problems with their musculoskeletal system grows continuously. This type of application has the advantage to be also applicable in sports where the barriers for market entrance are much lower.
  • Publication
    Panel Level Embedding for Power and Sensor Applications
    ( 2016)
    Aschenbrenner, Rolf
    Traditional manufacturing of packages like BGAs, QFNs or QFPs is performed on leadframe formats. The number of packages on a leadframe is rather limited. The introduction of Wafer-Level Packaging (WLP) allowed a significant reduction of cost, especially for small chips due to the simultaneous processing of thousands of Chip Size Packages (CSPs). However CSPs are limited to the die size, which means that chips with a high number of I/Os can not be redistributed to a relaxed interconnect pitch. This can only be achieved by a fan-out redistribution. The introduction of Fan-Out Wafer Level Packaging (FO-WLP) allowed the efficient manufacturing of fan-out packages on wafer formats up to 300 mm. Nevertheless Smart Phones, Wearables and similar applications ask for further cost reduction, which means more efficient processes on large production formats, i e. the introduction of Panel Level Packaging (PLP). A highly efficient method to realize PLP is the already established embedding technology. It uses Printed Circuit Board (PCB) materials, processes and equipment. PLP embedding is already performed in volume manufacturing on large PCB formats of 18?x24? (456x610 mm²). Today's applications are power packages for MOSFETs, power System-in-Packages (SiPs) and DC/DC converter modules. Manufacturing of larger BGA packages with embedded chips will start soon. Besides its high potential for cost reduction the PLP embedding offers high reliability and unique features like 3D integration of sensors with data processing units or the combination of power switches (IGBTs or MOSFETs) together with drivers and capacitors in one package. This presentation will show examples of PLP embedding from volume manufacturing as well as results of recent research activities. In particular current R&D effort to realize power modules for voltages up to 600 V with integrated electrical isolation will be described. A further example is the realization of a highly integrated intelligent camera module with embedded 32 bit signal processor and memory.
  • Publication
    Integration Technologies for Smart Textiles
    ( 2016)
    Aschenbrenner, Rolf
    There is a growing demand for ""intelligent environments"" or ""ambient assisted living"" where sensors and actuators that surround people or equipment are constantly exchanging information. Such environments require large area carriers for the electronic components - textile carriers are a good solution due to the large area capability at low cost. They allow the integration of electronic systems in the environment as well as in clothing. Integrating electronics into textiles is still an emerging field. In the development of smart textiles there is a strong drive to go for integration of electronic components into textiles in high volume manufacturing. Different types of smart fabrics, interconnection technologies, and applications have already been developed. But the technologies reported so far have not yet proven to be suited for reliable mass production. Novel concepts are required for the use of conductive textiles as sensors or the integration of conventional sensors in fabric. New yarns with well-defined properties as well as special fabrication processes for the textile are will be needed to obtain reproducible results. On different levels integration technologies have already been developed and qualified. For very small components a direct integration of chips into the yarn is possible. Larger and more complex modules require a specific package with contacts that allow the interconnection to the yarn - e.g. crimping, embroidery and adhesive bonding. Another alternative is the integration of stretchable interposers on the fabric. For all these solutions the I/O count is limited - on the one hand due to the limitations of the fabric, on the other hand due to the necessary size of the contacts of the modules. Together the technologies nonetheless build a platform, which allows the realization of a wide range of textile applications.
  • Publication
    Chip embedding - The key for efficient power electronics solutions
    ( 2016)
    Aschenbrenner, Rolf
    In most of these packages the power semiconductors are connected by bond wires, resulting in large resistances and parasitic inductances. Power chip packages have to carry semiconductors with increasing current densities. Conventional wire bonds are limiting their performance. Today's power modules are based on DCB (Direct Copper bonded) ceramic substrates. IGBT switches are mounted onto the ceramic and their top side contacts are connected by thick Al wires. This allows one wiring layer only and makes an integration of driver chips very difficult. Additionally bond wires result in a high stray inductance which limits the switching frequency. Especially the use of ultra-fast switching wide-bandgap semiconductors, like SiC and GaN, is very difficult. The embedding of chips offers a solution for many of the problems in power chip packages and power modules. While chip embedding was an academic exercise a decade ago, it is now an industrial solution. This paper will show today's available power packages and power modules realized in industrial production as well as in European research projects. The presentation try to show what concrete form such systems may take in the industrial reality, what requirements these package types will be subjected to and where the development trends may lead in the future. This presentation addresses the impact of the IC´s, materials, processes and end product requirements on packaging, interconnect technology, and assembly.