Lutz Rissing

This paper presents the fabrication and characterization of a microtransformer device for high-frequency power applications using electroplating and photolithography techniques. These devices are realized on an oxidized silicon wafer. They have the identical geometry on the primary and the secondary side combined with a core thickness value of 6 μm...

This paper presents a comparative study on different microfabricated inductors (microtransformers), which are suitable for high frequency power application. The main topic of this study is comparing and analyzing the effect of some factors like material type, number of turns, and coil form on microinductor performance considering a fixed chip size,...

A sensor concept for humidity measurement has been invented at the Institute of Micro Production Technology. The sensor element is manufactured on silicon oxide wafers with respect to the requirements of a new direct deposition process. This new process allows for thinner sensors with higher measuring accuracy. High purity 4N zinc oxide is used for...

Data storage is one of indispensable technical assets defined in a frame work of Industry 4.0. Among many data storage technologies, inherent magnetic data storage on surfaces of technical components is promising, especially when the components are employed in harsh environments. Comparing with other storage technologies like labels, RFID tags and...

80Ni-17Fe-3W alloy films are electroplated on Si wafer. The as-plated film is smoothed and annealed at different substrate temperature values of 200 °C, 300 °C, 400 °C, and 500 °C. The atomic force microscopy results show that the roughness of the as-plated alloy film increases with an increase in the annealing temperature. It is found that an incr...

The paper presents an overview of the development and the optimization of a thin-film micro-transformer built on a silicon wafer. Here, the solenoid-core micro-transformer is fabricated by means of thin-film technologies. The main impetus of further research is driven by optimization of electrical and magnetic properties. The micro-transformer is d...

Nanocrystalline soft magnetic Ni-Fe-W alloy films are electroplated by applying different substrate temperatures. In this paper, the effect of substrate temperatures on the magnetic properties is investigated. The morphology and the composition of the plated layers are determined by atomic force microscope and scanning electron microscope equipped...

To enable polymer films to be used in manufacturing flexible systems, additive fabrication methods need to be adapted to the polymer material and to the roll-to-roll mass production process. In this regard, coating processes, such as sputter deposition, thermal evaporation, vapor deposition, and so on, are discarded because of the complex patternin...

We have performed magneto-optical measurements of sputter deposited permalloy (NiFe 81/19) thin films on a polyimide based spin-on substrate and a silicon oxide substrate. Experiments were performed by means of the magneto-optic Kerr effect in order to complement the findings concerning soft magnetic behaviour on the macroscopic scale presented pre...

While automatic hot embossing systems are available for large- and small-scale productions of polymeric devices, one of the process challenges remains to be the manufacturing of precise, durable, and yet inexpensive hot embossing stamps. The use of metallic stamps manufactured by electroplating a photoresist pattern or by precision milling and thei...

Intrinsically and locally stored information on components is one of keys technologies for the next industrial revolution. One possibility is an integration of a magnetic storage into a component. Magnetic recording technologies from hard disk drives is adapted and used to create a flexible magnetic reading/writing system that can store information...

The research and development in the field of magnetoresistive sensors has played an important role in the last few decades. Here, the authors give an introduction to the fundamentals of the anisotropic magnetoresistive (AMR) and the giant magnetoresistive (GMR) effect as well as an overview of various types of sensors in industrial applications. In...

Kurzfassung In dieser Arbeit wird der Entwurf eines flexiblen, magnetischen Schreibkopfes vorgestellt. Die zentralen technologischen Herausforderungen stellen dabei die Fertigung und Montage des Systems dar. Anders als bei konventionellen Schreibköpfen, deren Kerne aus starren Komponenten bestehen, muss bei einem flexiblen Schreibkopf der Kern auf...

We compare the thermomechanical stresses in solar cell interconnections based on electrically conductive adhesives (ECA) with soldered joints by using bending experiments and finite element analysis (FEA). Additionally, the influence of an increasing number of busbars is studied. The FEA is validated by measuring the bending of cell strips after co...

Electrical properties of thin films of La1-xSrxF3-x solid solutions with x = 0 ÷ 0.24 were measured in temperature range from RT to 300°C and wide frequency range from 10−1 to 106 Hz by impedance spectroscopy method. The spectrums of impedance were analyzed with equivalent circuits contain RC and Warburg parts. DC-conductivities were calculated fro...

Would it be possible to insert intricate magnetic phenomena, such as spintronic effects (anisotropic, giant or tunnel magneto-resistance) on a sheet of paper? And, how could we exploit these phenomena in engineering unorthodox paper-based devices for leisure, medical and educational use? These are some of the questions that we tackle.

Manufacturing of ceramic based parts is the main challenge for future application in MEMS for automotive, medicine and mobile technology. To benefit from their superior properties like mechanical strength, high temperature and chemical resistance, high precision and low-cost processes are required.

With the chemical mechanical polishing (CMP) technology the material removal is made with conventional abrasives and chemical dissolution instead of using expensive diamond abrasives. In this investigation, we report on successful CMP polishing of Sintered Silicon Carbide (SSiC) wafer surfaces using concentrated colloidal silica slurries with diffe...

We investigated the impact of polymer substrates on the magnetic properties of soft magnetic thin films. Experiments were carried out to evaluate the performance of AMR (anisotropic magnetoresistive) sensors deposited on polymeric substrates and to give indications for the design of future sensors on flexible substrates. Sputtered permalloy (NiFe 8...

As shown in previous investigations, a correlation between a NiMn-based spin valve's thermal stability and its inherent exchange bias exists, even if the blocking temperature of the antiferromagnet is clearly above the heating temperature and the reason for thermal degradation is mainly diffusion and not the loss of exchange bias. Samples with...

A notable advantage of electroplated binary Co-Fe alloys in MEMS applications like sensors and actuators is the high saturation flux density Bs, which may reach values of 2.4 T in a composition range of 50-70 wt% Fe. In contrast, there are certain disadvantages limiting the use of these alloys, e. g. high film stress, high corrosion sensitivity and...

Fe-Ni-W alloys are electroplated from an ammonical citrate bath by applying three different current density values of 28, 56, and 84 mA/cm2. The morphology and structure of Fe-Ni-W alloys are detected by Scanning Electron Microscope (SEM) and X-ray diffraction (XRD), respectively. The deposits are smooth and well adhered to the substrate at a curre...

Driven by low-cost, resource abundance and distinct material properties, the use of paper in electronics, optics and fluidics is under investigation. Considering sensor systems based on magneto-resistance principles (anisotropic, giant, tunnel) that are conventionally manufactured onto inorganic semiconductor materials, we propose the use of paper...

In the field of modern information technology, optoelectronics are being widely used, and play an increasingly important role. Meanwhile, the demand for more flexible circuit carriers is rapidly growing, since flexibility facilitates the realization of diverse functions and applications. As a potential candidate, transparent polymer substrates with...

Mechanically flexible and one-dimensional electronic interconnects are nowadays a standard, enabling various applications such as invasive medical instruments, and offering a wide range of advantages from light-weight to high-density. Taking planar one-dimensional flexible systems onto the next level of low-cost yet high-speed and high-performance...

Ultrasonic non-destructive testing is presented as a method to determine differences in material distribution at elevated temperatures in hybrid workpieces made of different metals. Varying material distribution causes differences in transit time and can be detected by ultrasonic transit time measurements. Therefore, custom transducers are manufact...

This paper deals with the dependence of NiMn-based spin valves' functionality on temperature and time and with the factors influencing their thermal stability. As will be shown, the NiMn-based systems can be used for more than 660 h at 250 degrees C without degradation, but also an application up to 400 degrees C for short time is possible. The inv...

We compare the thermomechanical stresses in solar cell interconnections based on electrically conductive adhesives (ECA) with soldered joints by using bending experiments and finite element analysis (FEA). Additionally, the influence of an increasing number of busbars is studied. The FEA is validated by measuring the bending of cell strips after co...

Magnetic field sensors are used for contact free position detection of machine components for example. Fabricating these sensors on a flexible substrate enables the user to attach the sensor on various surfaces and different installation situations [1]. Within the Collaborated Research Center 653 a modular anisotropic magnetic field sensor on a fle...

In the frame work of Collaborative Research Center (CRC) 653, magnetic data storage on surfaces of components has been developed. The principle is based on magnetic data storage of hard disk drives. Rigid magnetic writing heads successfully developed so far still have limited capabilities; they cannot be adapted to rough or curved surfaces and cann...

To guarantee the deposition of sensors on functional surfaces, a reliable thin insulation layer is required. Within this paper, the results of the investigation of a capable insulation layer are presented. Challenges occurring during the manufacturing process will be discussed. A focus is set on parameters that influence the breakdown field strengt...

In this work, we conduct a numerical investigation of the structural feasibility of a flexible, monolithic and planar opto-electronic system based on low Tg polymers using ANSYS™. In particular, we explore the effectiveness of two eutectic compounds 52w.%In 48w.%Sn and 58w.%Bi 42w.%Sn to solder light sources and sinks to multimode light waveguides....

The combination of materials with new processing setups often leads to new opportunities in well-known technologies. Polyvinylidene fluoride (PVDF) is widely used because of its chemical resistance and thermal properties. Usually, it is shaped by spray casting to produce plumber components. PVDF is also known for its piezoelectric behavior, which c...

A wide range of applications increasingly requires sensors with high performance. By use of soft magnetic materials, the sensitivity of the aforementioned systems can be improved significantly. Here, one promising material is NiFeMo. Employing electrodeposition techniques, the material can be integrated into the sensorial system. However, the proce...

Hot embossing techniques enable the use of inexpensive polymers, e.g. as functional materials in optical devices or structural materials in fluidic systems. While automatic hot embossing systems are available for large and small-scale productions, the main challenge remains to be the manufacturing of precise, inexpensive and durable hot embossing s...

We present a cost-efficient and reproducible technique for assembling 3D components to mechanically bendable low glass transition temperature (Tg) polymeric interposers. First, we propose localized soldering using a focused hot air gun. Second, we use eutectic solders, which permit reflow at temperatures close to the Tg of the interposer. Then, we...

The magnetic capture and manipulation of metallic nanoparticles can be interesting for many small-scale synthetic reactions e.g. in the area of fine chemical production. Here, the separation of colloidal platinum nanoparticles from solution by means of magnetic beads is investigated. Therefore, magnetic beads functionalized with avidin are employed...

This paper presents a development of a microtransformer device fabricated using MEMS technology. The device is designed for higher switching frequencies beyond to 50 MHz power applications. The microtransformer features a closed magnetic core and six identity coils (three coils on primary and three coils on secondary side). Depending on connecting...

Soft magnetic materials are widely used as flux guides in sensor and actuator applications. Iron-rich binary Co–Fe alloys offer high saturation flux densities $B_{{s}}$ up to 2.4 T, which make them suitable as a flux guide material for high field applications. Their fabrication by electrodeposition has been examined to a large extent these last few...

Current MEMS technologies are focusing on higher integration, long-term stability, batch processing, and low-cost production. These challenges should be met with high quality and quantities for a wide range of applications and environments. To develop new and to adapt existing MEMS, a rising number of various advanced materials are used. These...

An electromagnetic microactuator, for controlling of a tuneable lens, with an integrated electrostatic element is fabricated by thin film technology. The actuator consists of two parts: the first part with microcoil and flux guide and the second part with a ring shaped back iron on a polyimide membrane. The back iron is additionally useable as elec...

The ultra-precision dicing of hard and brittle materials causes high wear on the abrasive tool which results in the deterioration of blade cross section as well as the decrease of diamond grain exposure. Resin-bonded diamond blades are used due to their in-process self-sharpening capability. Nevertheless, the shape of the blade cross section genera...

In the present work we have used a piezoresponse force microscopy (PFM) technique for the study of the polar surface structure of potassium tantalate doped with Li+ ions (KLT-3%) single crystal at low temperatures. The results of our measurements confirmed the existence of polar nanoregions in the temperature range of 10 – 80 K. We obtained a tempe...

A ''gentelligent component'' inherently stores all information necessary for its distinct identification, reproduction as well as for its manufacturing process and thus has both genetic and intelligent character. For the data storage directly on the components' rough surface a magnetic recording system is required. The goal is to develop a flexible...

Magnetic micro electro–mechanical systems (MEMS), such as magnetic sensors or actuators, are used in various areas of application, including bio-medical, wireless communication or power supplies. Many functional elements of these systems are made of soft magnetic materials. The increasing demands on miniaturization and higher efficiency of these fu...

Two approaches for fabricating polymer lenses are presented in this paper. Both are based on filling circular holes with UV curing adhesives. Initially, the viscous adhesive material creates a liquid and spherical free surface due to its own surface tension. This shape is then preserved by curing with UV-hardening light. For the first approach, the...

This paper describes a development of a microtransformer device fabricated using thin film technology. The device is designed for higher switching frequencies beyond to 50 MHz power applications. A especially by the microtransformer is a design, which allows wide flexibility of a device by choosing a different values of an inductance and of a windi...

Dicing still represents a main technology for separating or structuring hard and brittle materials. However, the high and frequent wear of machining tools (dicing blades) does not allow efficient machining. A new ceramic material and machining process are introduced to overcome this restriction. For this purpose, a porcelain-based ceramic is used....

Increasing efficiency for dicing of hard and brittle materials still represents a major challenge for ultra-precision machining. At the same time is dicing the most effective technology for structuring of material composites or stacks consisting of different materials. This paper describes a new approach to structure multi material stacks by using...

Nanowires are of great interest for technical devices, because of their special electric and magnetic behaviour. The main challenge in micro production technology is to realize a reproducible process for handling these nanowires. Otherwise it leads to a high rejection rate depending on failures in critical process steps. To avoid this, new producti...

Mononuclear iron complexes in which the iron(III) ion is coordinated by a pentadentate Schiff base ligand L5 with two phenolate, two imino and one amino group can exhibit a spin crossover. In this contribution experimental results are presented for complexes with cyanate and thiocyanate as co-ligands. Furthermore, theoretical results of quantum che...

Surface modification with Cu and Sn followed by bonding provides a suitable method to create a hermetic package in MEMS. By using the eutectic phase of these two materials the bonding temperature can be limited by 300 degrees C, which is in working range for the most micro electro-mechanical systems (MEMS) applications. In this investigation Si chi...

A magnetic field is generated by feeding electric current to micro coils. The higher the current, the higher the magnetic field is. A main disadvantage of coils in micro systems is the limited thermal resistance and as a result of a restriction concerning the maximum current densities. This work shows the modelling, design, numerical calculation an...

Cutting of hard and brittle materials as Sintered Silicon Carbide SSiC is an obstacle for implementing SSIC into MEMS applications. Wear and accuracy loss of resin-bonded diamond blades are significant. In contrast, metal-bonded diamond blades have a better shape accuracy during dicing of SSiC but require frequent dressing to renew the worn-out dia...

Cutting of hard and brittle materials as Sintered Silicon Carbide SSiC is an obstacle for implementing SSIC into MEMS applications. Wear and accuracy loss of resin-bonded diamond blades are significant. In contrast, metal-bonded diamond blades have a better shape accuracy during dicing of SSiC but require frequent dressing to renew the worn-out dia...

In contrast to existing microelectromechanical systems (MEMS), this paper describes the development, fabrication, and testing of an anisotropic magnetoresistance (AMR) microsensor using a 7 μm thick polymer foil as substrate material. The modular magnetic field micro sensors are fabricated on a standard 4 in Si Wafer due to handling purposes during...

This paper describes the development and fabrication of a modular eddy current micro sensor on a flexible polymer foil. Due to handling purposes during the micro sensor fabrication process the modular eddy current micro sensors are fabricated on a temporary Si substrate. To enable a release of the micro sensors at the end of the fabrication process...

Soft magnetic materials are used in a multitude of applications in magnetic micro electro-mechanical systems (MEMS) such as microsensors or microactuators. The most commonly applied softmagnetic material for microsensor applications is permalloy with a composition of NiFe81/19. This paper investigates the magnetic material properties as a function...

Soft magnetic materials are used in a multitude of applications in magnetic micro electro-mechanical systems (MEMS) such as microsensors or microactuators. The most commonly applied softmagnetic material for microsensor applications is permalloy with a composition of NiFe81/19. This paper investigates the magnetic material properties as a function...

With its chemical resistance and easy structurability, polyimide (PI) makes for a fine candidate for membranes of tuneable optical systems. Disadvantages of the material are its high absorption coefficient and its mechanical stability, which prevents high deflections of the membrane. To improve the optical capabilities of the material, different va...

Adapted ultra-precision dicing processes are required for implementing hard and brittle materials such as sintered silicon carbide (SSiC) into MEMS applications. Wear and accuracy loss of resin-bonded dicing blades are significant when processing SSiC. Metal-bonded dicing blades can better resist the harsh environment during dicing of SSiC but requ...

In order to design an electromagnetically driven microsystem serving as an ear implant to overcome amblyacousia, Finite Element Method (FEM) simulations were conducted. The system consists of three parts, an upper system part, a lower system part and a plunger. The design process included mechanical, electromagnetic, and thermal simulations. Based...

We present an optofluidic system based on electromagnetic manipulation of a ferrofluid to tune a liquid lens. Both studies of the dynamics of fluid transport and of the optical properties of the liquid lens have been carried out. Thermal and magnetic field simulations of the microcoil actuators are presented. Proof-of-principle experiments demonstr...

By using inline dressing, the tool can be in-situ controlled and dressed on demand. This way, constant machining conditions can be obtained during the entire processing time. Especially for dicing of hard and brittle materials, which causes high blade wear, is a very important issue regarding process control and efficiency. The first step to integr...

Dicing of hard and brittle materials is still a major challenge for ultra-precision machining. The main goals, in order to rationalize the process as well as to enhance the surface finish and form accuracy, are reducing the tool wear and supporting the removal mechanisms. For this purpose, a profound understanding of the forces generated in the too...

A 3-D magnetic field sensor based on the giant magnetoresistive (GMR) spin valve (SV) was designed for improving the energy efficiency in intelligent automating devices. Generally GMR SV sensors are selective only in the plane of the substrate due to fabrication restraints. For this application, a sensor with ultra-thin dimensions is required for t...

Magnetic flux guides are often a part of MEMS. These flux guides are usually made by electroplating of soft magnetic materials like NiFe. The geometry of the flux guides influences the magnetic anisotropy. A new method for the fabrication of the flux guides is the embossing of the surface to influence the magnetic anisotropy. For this purpose the I...

For a magnetic MEMS application, the integration of soft magnetic flux guides with high saturation flux density is often needed. A complex form including a trench in substrate was designed to achieve its flux guide function. Electroplating CoFe with followed Chemical-mechanical Polishing (CMP) process was chosen as fabrication technology. Pulse cur...

Magnetic Nano Beads (MNBs) can be successfully manipulated not only in vitro but also in vivo by a magnetic field generated by a permanent magnet or an electromagnet. Nonetheless, the magnetic flux has to be concentrated in a well defined area for a precise positioning of the MNB. The idea is to collect the MNBs after a medical application in a def...

Alkaline silica-based slurries have been pinpointed as a conventional solution for Chemical-mechanical Polishing (CMP) of Silicon Carbide (SiC). Nevertheless, these slurries may exhibit insufficient performances concerning material removal rates (MRR) and surface quality, when applied on SiC as bulk material. Investigations on MRRs and resulting su...

Parts which inherently store data about their fabrication, gain load data during their life cycle, machine components that autonomously monitor themselves and arrange inspections as required will be reality in the Collaborative Research Centre 653. The vision of the CRC 653 ‘Gentelligent Components in their Lifecycle - Utilisation of Inheritable Co...