The increase in battery-powered handheld devices is driving the demand for faster charging converters. Gallium Nitride (GaN) converters allow frequencies of above 500 kHz, enabling a smaller footprint especially for magnetic components. In this paper molded interconnect device (MID) transformers with a height of 2.5 mm are produced via a two-step injection molding process using polyether ether ketone (PEEK) granulate. The two- step injection molding process encapsulates a water jet-cut ferrite core. Laser Direct Structuring (LDS) creates the coils around the core. This process produces multiple transformers in two designs with inductance values around 19 μH and 28 μH, each boasting a high coupling coefficient exceeding 95 %. CT images reveal cracks in the ferrite core after the second injection molding step, explaining discrepancies between measured and simulated results. Nevertheless, MID transformers can skip the complex process of winding and are already packed, which can lower the cost for an industrial production.

Ultracold atoms offer the highest sensitivity for quantum sensors. The industrial use of these systems requires miniaturization of the experimental setups. For this purpose, a concept for a miniaturized atom source using rubidium as atom species for the generation of vapor phase atoms was developed in this work. As an alkali metal, rubidium is highly reactive and reacts directly with small amounts of water or oxygen. In this source, pure rubidium is encapsulated by bonding two micromachined silicon components, a reservoir chip and an active release chip, together in a glovebox under an argon atmosphere. This prevents the rubidium from reacting when the source comes into contact with air. The active release chip had a thin silicon membrane and an additional gold structure that enables the membrane to be heated by Joule heating. After pumping down and baking the vacuum test chamber to an ultra-high vacuum, the release mechanism is triggered by a sharp increase in temperature within milliseconds. After opening the source, a rubidium signal was detected by analyzing the residual gas atmosphere of the vacuum with a quadrupole mass spectrometer.

Hermetic Packages are of great importance for the recent miniaturization of quantum systems to secure a defined vacuum and gas species. In this work, a silicon membrane pressure sensor based on platinum strain gauge structures to measure the pressure dependent deflection of the membrane is shown. The pressure sensors are used for inline monitoring of pressure and hermeticity of small-volume bonded packages. For this purpose, the sensors arc fabricated by silicon microtechnology, characterized in a developed calibration setup and finally the pressure monitoring and hermeticity test of bonded packages were carried out.

In the monitoring of mechanical components for lifetime prediction and detection of critical load conditions, especially strain gauges play a major role. They can be integrated into components to measure strain in the components themselves. This places special demands on the sensors used because of higher temperatures in the manufacturing phase of the components like additive manufacturing. This is why the sensors need to be polymer-free and cannot be applied with an adhesive. For this, directly deposited polymer-free sensors have been developed. In this article, the advantages of conventional polymer-foil based strain gauges (batch production) and directly deposited sensors (polymer-free) are combined by depositing the sensors on a metal foil and applying them polymer-free to metal specimens. This enables the batch production of strain gauges for use in harsh environments. Therefore, steel and aluminum foils were used as sensor carrier materials with aluminum oxide insulation layers and Platinum and NiCr sensor layers on the front side. On the back side, a tin layer was applied to enable thermocompressive bonding on the specimens leading to maximum tensile shear strengths of 10.7 MPa. After application, the sensors showed a k-factor of about 3.6 for the platinum sensors and about 2.4 for the NiCr sensors proving the functionality of the sensor concept.

This work focuses on designing and fabricating an optimized extraction electrode made out of borofloat glass. The electrode is a part of an emitter chip, where the field emitters are manufactured by the wafer dicing technique. The extraction electrode was fabricated by Selective Laser Etch (SLE) process, where the geometry comprises an array of Through-Glass-Vias (TGV) that are positioned concentrically over each emitter tip, a cavity in the area of the TGVs, additional cavities for lowering of the electrode and TGVs for dowel pins for alignment. The current-voltage experiments confirm the enhancement in the measured field emission current dependent on the geometry of the extraction electrode.

AbstractThis contribution summarizes the current state of research regarding so‐called sensor‐integrating machine elements as an enabler of digitalization in mechanical engineering and——if available—their application in industry. The focus is on the methodical aspects of the development of these machine elements in general as well as specific sensor‐integrating machine elements that are either already in use or currently under development. Developmental aspects include the robust design of initially evaluated concepts for sensor‐integrating machine elements as well as their modularization. Smart materials with sensory functions are included in the analysis as well as the differentiation with regard to add‐on sensors. The aim of the authors interlinked by a special research program funded by the German Research Foundation (DFG) is to facilitate the exchange with other researchers with the help of the comprehensive overview given in this contribution. The contribution concludes with a brief discussion of open challenges, such as the energy supply and data transfer in rotating systems and also data security.

Engineering in vacuum or under a protective atmosphere permits the production of materials, wherever the absence of oxygen is an essential demand for a successful processing. However, very few studies have provided quantitative evidence of the effect of oxidized surfaces to tribological properties. In the current study on 99.99% pure copper, it is revealed that tribo-oxidation and the resulting increased abrasive wear can be suppressed by processing in an extreme high vacuum (XHV) adequate environment. The XHV adequate atmosphere was realized by using a silane-doped shielding gas (1.5 vol% SiH4 in argon). To analyse the influence of the ambient atmosphere on the tribological and mechanical properties, a ball—disk tribometer and a nanoindenter were used in air, argon, and silane-doped argon atmosphere for temperatures up to 800 °C. Resistance measurements of the resulting coatings were carried out. To characterize the microstructures and the chemical compositions of the samples, the scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), and X-ray diffraction (XRD) were used. The investigations have revealed a formation of η-Cu3Si in silane-doped atmosphere at 300 °C, as well as various intermediate stages of copper silicides. At temperatures above 300 °C, the formation of γ-Cu5Si were detected. The formation was linked to an increase in hardness from 1.95 to 5.44 GPa, while the Young’s modulus increased by 46% to 178 GPa, with the significant reduction of the wear volume by a factor of 4.5 and the suppression of further oxidation and susceptibility of chemical wear. In addition, the relevant diffusion processes were identified using molecular dynamics (MD) simulations.

Precision machining is becoming more and more important with the increasing demands on surface quality for various components. This applies, for example, to mirror components in micro-optics or cooling components in microelectronics. Copper is a frequently used material for this purpose, but its mechanical properties make it difficult to machine. In this study, a process strategy for finishing copper surfaces with batch-manufactured micro-grinding tools in an electrochemically assisted grinding process is demonstrated. The tool heads are manufactured from a polyimide-abrasive-suspension and silicon as a carrier substrate using microsystems technology. The matching shafts are milled from aluminium. The tools are then used on pure copper and oxidised copper surfaces. By using finer abrasives grains (1.6–2.4 µm instead of 4–6 µm) than previously, similar surface roughness values could be achieved ( R a = 0.09 ± 0.02 µm, R z = 1.94 ± 0.73 µm) with the same grinding process. An optimised grinding process that combines the use of rough and fine tools, on the other hand, achieves significantly better surface finishes in just four grinding iterations ( R a = 0.02 ± 0.01 µm, R z = 0.83 ± 0.21 µm). In order to achieve a further increase in surface quality, this optimised grinding process is combined with the anodic oxidation of the copper workpieces. The surface modification is done to increase the machinability of the surface by creating an oxide layer. This is confirmed by the results of scratch tests carried out, which showed less force acting on the tool during machining with the oxide layer than with a pure copper surface. To realise this within the machine tool, an electrochemical cell is shown that can be integrated into the machine so that the oxidation can be carried out immediately before the grinding process. The copper layers produced inside the electrochemical cell in the machine tool show similar characteristics to the samples produced outside. Processing the oxidised samples with the optimised grinding process led to a further reduction of about 17% in the R z values ( R a = 0.03 ± 0.01 µm, R z = 0.69 ± 0.20 µm). The combination of the shown grinding process and the integration of anodic oxidation within the machine tool for the surface modification of copper workpieces seems to be promising to achieve high surface finishes.

Downsized and complex micro-machining structures have to meet quality requirements concerning geometry and convince through increasing functionality. The development and use of cutting tools in the sub-millimeter range can meet these demands and contribute to the production of intelligent components in biomedical technology, optics or electronics. This article addresses the development of double-edged micro-cutters, which consist of a two-part system of cutter head and shaft. The cutting diameters are between 50 and 200 μm. The silicon carbide cutting heads are manufactured from the solid material using microsystem technology. The substrate used can be structured uniformly via photolithography, which means that 5200 homogeneous micro-milling heads can be produced simultaneously. This novel batch approach represents a contrast to conventionally manufactured micro-milling cutters. The imprint is taken by means of reactive ion etching using a mask made of electroplated nickel. Within this dry etching process, characteristic values such as the etch rate and flank angle of the structures are critical and will be compared in a parameter analysis. At optimal parameters, an anisotropy factor of 0.8 and an etching rate of 0.34 µm/min of the silicon carbide are generated. Finally, the milling heads are diced and joined. In the final machining tests, the functionality is investigated and any signs of wear are evaluated. A tool life of 1500 mm in various materials could be achieved. This and the milling quality achieved are in the range of conventional micro-milling cutters, which gives a positive outlook for further development.

As copper is a rather difficult material to machine due to its ductility compared to aluminium, this study presents the approach of oxidizing the surface to improve the results of the grinding process. Therefore, batch manufactured flexible micro-grinding tools are used for grinding of copper and oxidized copper surfaces to machine microstructure or local areas of functional surfaces. Besides, we show a comparison of the performance of an abrasive layer made of silicon carbide (SiC) and cubic boron nitride (cBN). The tools are made of a polyimide-based abrasive layer and silicon as substrate and are fabricated by photolithography and deep reactive ion etching. The oxidation of copper surfaces is done by electrochemical processes and are directly machined with grinding tools. The surface quality is evaluated concerning the surface roughness by optical measurements with confocal microscopy. Lower roughness values are achieved on both, the pure copper and the oxidized copper by using SiC grinding tools. On pure copper this is reflected in a reduction of the arithmetical mean roughness value Ra to 0.04 µm. The unprocessed reference surface shows an Ra of 0.24 µm. In addition, the machined oxidized surfaces show a reduction of the mean roughness depth Rz from 7,60 µm to 1.10 µm, which is an optimization of factor 2 compared to the machined non-oxidized copper surfaces (2.32 µm). The machining of copper with cBN micro-grinding tools also shows improved roughness values, but in comparison to the SiC tools these are 50 % higher for machined copper surfaces and similar for machined oxidized copper surfaces. While the oxidation of the copper surface has a positive effect on the surface quality, no effect on tool wear can be observed.

The world's electrical energy demand is rising permanently and, at the same time, resources must be used economically and responsibly.An important part of the energy turnaround are wind mills, where conventional machine elements such as gears or rolling bearings find application.These parts have optimization potential in terms of service life and reliability.To advance this potential, sensor integration for intelligent system monitoring combined with a compact electronic solution has to be realized.In contrast to conventional condition monitoring systems (CMS), this article addresses thin-film sensors that will be applied inside the bearing system directly inside or close to the tribological contact enabling maximum information about the system's condition.For this purpose, thin-film strain gauges are directly deposited onto small steel bearing washers of a cylindrical roller thrust bearing system (CRTB) by photolithography and sputtering processes.The layer stack includes an aluminum oxide insulation layer, the sensor layer and an aluminum oxide wear protection coating.The sensor layer consists of an array of three differently aligned meander-shaped constantan strain gauges.Therefore, bearing washers with the sensors are tested on a pin-onplate tribometer under defined load conditions.The influence of normal force as well as velocity on the thin-film sensors could be detected in this study.During the tests, under Hertzian pressure up to 1 GPa and a constant sliding velocity of 8 mm/s, a maximum nominal resistance change ΔR/R 0 of up to -0.13 ‰ was measured.Changing the velocity from 1 mm/s to 8 mm/s resulted in maximum ΔR/R 0 values of -0.17 ‰.This enables the determination of the correlation between sensor signals and tribological stresses.Though Hertzian pressures of 950 MPa were applied, no sensor failure was observed during the experiments proving the functionality of the sensor layer system.

The quality of deep-drawn parts is subject to uncontrollable fluctuations, triggered by material property variations and process deviations, which occur despite extensive quality controls along the entire process chain. Monitoring and controlling the draw-in of the sheet material—which is an indicator of a faultless deep drawing process—would allow for a significant increase in process robustness. However, this requires sensor systems suitable for the industrial environment, which so far do not exist. This paper presents a newly developed inductive sensor in thin-film technology for measuring the flange draw-in. The sensor was designed with the aid of finite-element-analysis and then manufactured using thin-film processes. After integration into a deep-drawing tool, the system was tested and validated. Afterwards, the detection of typical deep-drawing defects was investigated. It was demonstrated that the sensor system can reliably detect both cracks and wrinkles as well as the time at which they occur.

We present the development of an atom chip system along with associated peripherals for a six-axis quantum inertial navigation sensor based on atom interferometry. Based on quantum mechanical measurement concepts, these sensors are expected to have high sensitivity and superior long-term stability compared to conventional inertial sensors. Furthermore, they enable offset-free absolute measurement. However, the low measurement rate proves to be a disadvantage. Compared to classical inertial sensors, quantum inertial navigation sensors thus exhibit complementary features, so that a combination of these two methods appears promising. The use of inertial measurement systems on board of aircraft or satellites is usually accompanied by limitations in size, payload and power consumption. To meet these requirements, we address both the atom chip system itself and the necessary environment in the form of pumps and vacuum enclosures which are crucial parts of the sensor head.

Current limitations of silver sintering are long processing times and high processing temperatures. To overcome these restrictions, different tin contents are added to the sintering paste. Various preheating times and processing times are evaluated at a processing temperature of 235°C. The positive effect of micro scale tin particles on shear strength and porosity at reduced process parameters is demonstrated. The addition of tin particles enables a reduction of both the processing temperature and time while maintaining high shear strengths. At a processing time of 60 s and no preheating time, the addition of 27.5 at% tin to the sintering paste leads to an increase in shear strength of 417 % from 4.6 MPa to 19.2 MPa, compared to the sintering paste without an alloying element. Energy-dispersive X-ray spectroscopy shows the homogeneous distribution of the alloying element in the joint that has been fabricated with the produced sintering paste. The porosity of the sintered layer is reduced by the addition of tin as alloying element which can improve the electrical and thermal properties as well.

Ultrasonic (US) wire bonding is a very complex process during which different mechanisms occur at different locations of the bonding interface. The change of these local mechanisms stays unclear. In this study, a 3 x 4 piezoceramic-based sensor array was created to in-situ measure the local tangential forces at different locations of the interface; by analyzing these forces, corresponding mechanisms were derived. The results showed the largest tangential forces on the two central columns, the smallest tangential forces on the columns at the four corners, and the largest expansion of the contact area on the remaining six columns (peripheral columns). In the beginning of the bonding process, a "1st fast increase - plateau - 2nd fast increase" of tangential force stage was detected on nearly all columns. In the following process, the tangential forces on the central columns decreased due to the decrease of the local normal forces; later, the decrease could be compensated by microweld formation. As the local normal forces increased, a gradual increase of tangential force occurred on the peripheral columns. This increasing stage could also occur on the corner columns while the increase was much smaller. The specific curves at different moments exhibited complex features consisting of static and sliding friction, microweld for-mation and breakage. Compared to central columns, sliding friction played a more dominating role on peripheral and corner columns. These findings deepen the understanding of mechanisms occurring at different locations of the bonding interface and provide potential to enhance the bonding process via changing the substrate structure.

This work presents the design and fabrication of a novel emitter chip comprising a silicon electron source with pyramidal structures and a glass extraction electrode. The emitters were fabricated using a wafer dicing technique. The glass extraction electrode was manufactured by Laser Induced Deep Etching (LIDE), metallized, and bonded onto the silicon chip using laser-assisted bonding. Current-voltage experiments confirm the excellent performance of the diced emitters, highlighting their potential for a wide range of applications.

We numerically explore synthetic crystal diamond for realizing novel light sources in ranges which are up to now difficult to achieve with other materials, such as sub-10-fs pulse durations and challenging spectral ranges. We assess the performance of on-chip diamond waveguides for controlling light generation by means of nonlinear soliton dynamics. The considered silica-embedded diamond waveguide model exhibits two zero-dispersion points, delimiting an anomalous dispersion range that exceeds an octave. Various propagation dynamics, including supercontinuum generation by soliton fission, can be realized in diamond photonics. In contrast to usual silica-based optical fibers, where such processes occur on the scale of meters, in diamond millimeter-scale propagation distances are sufficient. Unperturbed soliton-dynamics prior to soliton fission allow identifying a pulse self-compression scenario that promises record-breaking compression factors on chip-size propagation lengths.

Oxygen is often a significant disruptive factor in many production engineering processes and efforts have been made to limit or remove these oxide layers during manufacturing. However, the mechanical properties of oxide layers and their relationship to the raw material are not yet fully understood. In this work, we examine the nanoindentation process on Al surfaces covered with a native oxide layer of various thicknesses using molecular dynamics (MD) models and experiments. For MD simulations, the most advanced interatomic potentials, COMB3 and ReaxFF, are employed to model the interaction between Al and O elements. The two potentials were thoroughly tested and compared with the Embedded Atom Method (EAM). According to our findings, the oxide layer has a significant impact on defect emission in the substrate. However, the behavior of the oxide layer during the indentation process is different for the two potentials. In agreement with experiments, the COMB3 potential shows crack initiation and propagation. The ReaxFF potential displays a pile-up of atoms surrounding the indenter, but no cracks are visible.