microelectronic

Focus on Electrical Engineering. The fifth E-Science Day at Schmalkalden University of Applied Sciences

Focus on Electrical Engineering. The fifth E-Science Day at Schmalkalden University of Applied Sciences

Tobias Braun

This summer, the Faculty of Electrical Engineering at Schmalkalden University of Applied Sciences hosted the E-Science Day for the fifth time. The aim of this event is to offer both the university community and the wider public an insight into the breadth of the faculty’s subject areas and its current research. Much of what happens in science may seem distant at first, but is actually very close to people’s everyday lives.

Electrical Engineering at Schmalkalden University of Applied Sciences covers a broad spectrum of modern technologies – ranging from electrical power engineering and automation, through vehicle electronics and embedded systems, to microelectronics, autonomous systems and information technology. In doing so, the faculty combines traditional engineering disciplines with future-oriented topics such as digitalisation, AI, robotics, the energy transition and modern electronics – in a practical, innovative way and with a focus on specific applications.

From construction monitoring

Professor Maria Schweigel presented her BauKIRo project, ‘Automatic monitoring of construction progress through the application of artificial intelligence and robotics’, which ran for three years and has now been completed. The aim was to improve the monitoring of building structures under construction. To date, construction progress and adherence to the schedule have been checked manually, which is a time-consuming and costly process. At the same time, the earlier corrections are identified and addressed in the construction process, the more cost-effective they are.

The approach taken by the BauKIRo project was to develop a drone capable of carrying out monitoring tasks autonomously and precisely with the aid of artificial intelligence. This solution has the advantage of combining low costs with continuous monitoring of the building site, whilst also not disrupting construction progress, as the drone can carry out its monitoring even at night.

The Building Information Model (BIM) was utilised for the inspection; this not only enabled the comparison of plans with the actual situation but also facilitated the coordination of movement within the construction site. One problem encountered was that the BIM was available in various formats, which complicated data processing. As GPS does not function reliably enough indoors and solutions using other sensors were also inadequate, the project team opted for a semantics-based localisation approach: distinctive features such as door frames served as orientation points for positioning, enabling an accuracy of less than 10 cm to be achieved.

A practical challenge during implementation was precisely this movement of the drone within an active construction site: paths may be blocked, cables may be hanging down, or many other contingencies may hinder the drone’s exploration. It was therefore necessary to implement protective measures without placing too great a burden on the drone’s weight and, consequently, its range. This required striking a balance between safety and factors such as range, which presented a challenge both in the design of the drone and in the selection of sensors and image recognition hardware.

In addition to tracking movement within the rooms, a further challenge lay in generating and converting the images – in the form of point clouds – into three-dimensional representations of buildings, which could then be aligned with the BIM model. Achieving the most accurate representation possible was just as labour-intensive as detecting unknown objects (including machinery). These had first to be identified and then excluded during the alignment process with the BIM model. As there are no relevant datasets available to guide artificial intelligence applications in recognising such objects within the ‘construction site’ context, customised solutions – such as a specialised deep learning network – had to be developed here too.

The project succeeded in creating a functional demonstrator capable of meeting the requirements of active construction sites. Future projects can build on this and expand the possibilities to include increasingly complex technologies and AI applications. In addition to Schmalkalden University of Applied Sciences, the Friedrich-Alexander University of Erlangen-Nuremberg participated in BauKIRo. At the same time, it was an IGF project and was funded via the DLR Project Management Agency – German Aerospace Centre (DLR) – with funding from the then Federal Ministry for Economic Affairs and Climate Action (BMWK).

And the development of evacuation aids

Following the completion of this project, attention turned to a venture that is still in its infancy: EvacEye – No Life Unseen. With the aim of successfully participating in the Cosima competition, students at Schmalkalden University of Applied Sciences are tackling an important issue: preventing casualties in the event of a fire. In the event of a fire, time is a critical factor, and every gain in time can help to facilitate evacuations and save lives. To date, the fire service has relied on manual procedures during operations, using floor plans to prioritise and work through areas based on the estimated number of people present. The idea behind the project is to provide the fire service with early information on the number and distribution of people in the event of an emergency, thereby optimising evacuation procedures.

In doing so, the project had to take into account the harsh environmental conditions, such as those caused by smoke and darkness. Instead of a camera-based solution, radar and thermal sensors are to be used to detect the presence of people through the combined detection of heat and movement. A low resolution is sufficient here to enable reliable detection of people. This solution also has the major advantage of posing no data protection concerns and, from the end-users’ perspective, causing far less hesitation. In the event of a fire, the system is activated and transmits its measurements to the emergency services, who can then take appropriate action.

At the end of the year, the team led by Leonard Maletzke, Luis Marcus, Karl Schwennicke Plata and Marius Weimann will present their project at the electronica trade fair in Munich.

On MEMS integration and chip interconnection

These two presentations were followed by a talk focusing on the specific field of wafer bonding, a process in which two ultra-thin semiconductor wafers are permanently bonded together to produce more complex electronic or micro-engineering components. The process is a key technology for applications such as microchips, sensors, power electronics and microsystems engineering, as it enables different materials and functional layers to be combined with precision and in a compact manner.

Arti Rana, a research assistant at Schmalkalden University of Applied Sciences, examined a specific method for sealing and integrating microelectromechanical systems (MEMS) – known as anodic bonding – and investigated the properties of a specific material. In anodic bonding, glass is used to create the connection, the hermetic seal and the encapsulation of the components. The material used for this purpose must possess specific properties and meet quality standards in order to be suitable for these applications.

Arti Rani investigated the specific behaviour of a new glass from Schott, Borofloat 33 HT, in comparison with the company’s standard glass. Particularly for industrial upscaling, the material properties must be examined in detail; this concerns not only behaviour during the production process – i.e. bonding – but also medium- and long-term durability.

Macjonathan Okereke, who is also a research assistant at Schmalkalden University of Applied Sciences, presented his research into so-called under-bump metallisation (UBM), which must also possess specific material properties. In short, his work focuses on direct soldering for the assembly and connection of chips to printed circuit boards. In order to solder chips sawn from the wafer directly onto printed circuit boards as a modern alternative to traditional chip and wire bonding in packages (important for the smallest form factors), without using a surrounding encapsulation, specially adapted contact points are required: one option is the application of small solder balls, via which the connection to the component is then established. Macjonathan Okereke’s work focuses on the area beneath the balls, and thus the connection to the wafer. Under-bump metallisation consists of thin metal layer systems on the semiconductor chip which serve as a stable bridge, a bonding agent and a protective layer between the chip’s aluminium or copper contacts and the solder bumps; it is used in certain interconnection and integration processes and constitutes a directly solderable chip metallisation.

However, this method has so far relied on an electroplating process, which is neither environmentally sustainable nor cost-effective. The aim of this work was to demonstrate that sputtering processes are also suitable. In this process, material is removed from a target under vacuum and deposited as an ultra-thin layer onto a wafer – for example, to coat surfaces with metals or other materials for the purpose of forming contacts. As the study shows, this method is suitable for the production of high-quality UBMs and is therefore a more environmentally friendly and cost-effective alternative to electroplated coating systems.

Right through to drones and humanoid robots

Dr. Vitas Grimaila is an associate professor in the Department of Electrical Engineering at Kaunas University of Technology (KTU), a close partner of HSM, and specialises in the field of drone defence and the development of corresponding systems. Drones have long been a central component of armed conflicts and will therefore play a major role in future security measures. The development of drone technology is just as dynamic as the variety of their designs.

Drone defence systems are tasked with addressing this complexity and minimising the threat posed by drones. To do so, these systems must operate with precision, reliability and speed. The first step is detection, achieved through a combination of various sensors, including those that detect radio waves and propeller signatures. The drone must then be identified or classified in order to rule out false detections and initiate appropriate countermeasures. By tracking the drone and processing telemetry data, its movements are calculated and a favourable opportunity for interception is identified. The final stage is the interception, which ranges from disrupting the flight path to interrupting communication between the drone and the satellite navigation system. For the countermeasures to be effective, it is crucial that the drone is correctly classified.

André Lopes and Professor Christoph Menz presented a project dedicated to a novel approach to instructing humanoid robots, in this case the training of movements. The movement sequences for these robots are extremely complex, due, amongst other things, to the difficult coordination of numerous joints and motors. The project’s ambitious aim was to enable robots to learn movements via video, rather than having to input them laboriously. A key challenge in this endeavour lay in coordinating the various components and processes, and in avoiding movements that could cause damage.

To solve this problem, it proved useful to separate two areas: firstly, a catalogue (dataset) of possible and safe robot movements was created in the form of vectors. At the same time, a motion recognition system was developed that focuses on the intention behind the movement – in other words, the goal to be achieved. The robot was therefore designed to recognise and replicate the movement in the video, drawing on the catalogue of possible actions whilst imitating it. In doing so, particular emphasis was placed on flexibility: the optimal combination of movement sequences is calculated in real time and can react to factors such as obstacles in the path.

Outlook and Conclusion

Following this, Dominik Müller from the Sonneberg-based company HySON and Professor Martin Schreivogel presented the latest developments in hydrogen research. As a new teaching and research facility was also unveiled during this session, we will address this topic in a separate article.

The examples from E-Science Day impressively demonstrate just how diverse and application-oriented research is at the Faculty of Electrical Engineering at Schmalkalden University of Applied Sciences. Whether intelligent drones, digital construction sites, modern semiconductor technologies, innovative sensor systems or adaptive robots – the projects presented combine scientific fundamentals with specific challenges from industry and society. It is precisely this connection that highlights the contribution that application-oriented research can make at the university: it generates new knowledge, develops practical solutions from it and, at the same time, opens up new perspectives for future technologies.

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Panta rhei. Materials science and its view of the dynamics of the world

Panta rhei. Materials science and its view of the dynamics of the world

Tobias Braun

Heraclitus’ Greek aphorism, according to which everything flows, takes on additional significance in the field of materials science. The principle of eternal becoming and change can be translated here as meaning that nothing is truly fixed and, contrary to expectations, some things are not really sharply separated. This is a unique perspective on the structure of materials and their relationships, on the interplay between substances and things. And what all this has to do with the production of modern microchips, which are found in our smartphones and smartwatches, will be discussed on the following pages.

At first, it makes sense to introduce the subject itself: Materials science is a discipline that lies between chemistry, physics, and engineering, linking these fields in a unique perspective. It is therefore an interdisciplinary field that deals with the research, development, and application of materials. As a science that focuses on materials, it aims to understand mixtures of substances, their interactions, and the resulting properties. It deals with chemical descriptions as well as physical, chemical, and mechanical characterizations, analyses of the structures and composition of substances, and the manufacturing conditions described by factors of thermodynamics and kinetics. The focus is therefore on thermodynamic and kinetic fundamentals for materials that are important in engineering:  approaches are developed through the creation of phase diagrams, the investigation of diffusion processes, and the characterization of internal interfaces.

Furthermore, one subfield of materials science deals with the development of new or adapted materials with specific properties that are tailored to the requirements of certain applications. When we think of the highly specialized materials used in modern microelectronics, for example, which form the basis for miniaturization and increased performance, it becomes clear how materials science taps into innovative potential through its combination of natural science and engineering approaches. This also demonstrates the bridge between basic research and its transfer into application-oriented reality, which is particularly important as a productive link between research and development for universities of applied sciences. 

How do materials scientists work?

Phase diagrams, i.e., representations of phase transitions as a function of various parameters, are useful for understanding the properties of substances and how they change in different states. In these diagrams, phase transitions (from solid to liquid to gas, etc.) are represented by influencing factors such as composition and temperature. The substances or individual components have different relevant properties depending on their state and, among other things, during the transitions, which need to be characterized. These diagrams can be used to investigate thermodynamic and kinetic behavior, which can then be used specifically in manufacturing processes, for example.

Another aspect within materials science is diffusion, i.e., the interactions between substances, for example, between two metal layers. Our everyday understanding suggests that there are no interactions between the two metals, as both are solid bodies that exist completely separately. However, if we use low-scale observation methods such as electron microscopes, in which the atoms and atomic lattices become visible, the picture changes: to stay with our example, relationships can exist between the metals, which can lead, among other things, to mutual mixing or even to the incorporation of one substance by the other. When different metals and alloys are combined, as in microchip manufacturing in electrical engineering, such effects must be taken into account, which is the focus of materials science.

The investigation of such interdiffusion processes is one aspect of materials science that leads us to Martin Seyring and his research at Schmalkalden University of Applied Sciences. Dr. Martin Seyring joined HSM in October 2022 as a research assistant for scanning electron and optical microscopy at the Faculty of Electrical Engineering. Previously, he researched and taught at Friedrich Schiller University in Jena, where he also earned his doctorate.

Materials science research at HSM

Martin Seyring’s research focuses on phase imbalances at metallic interfaces, which in the field of materials science encompasses processes such as interdiffusion. At HSM, he works with Roy Knechtel, who holds the professorship for Autonomous Intelligent Systems. Both are now conducting research into the development of microelectronic components, known as MEMS. Among other things, this involves pressure, acceleration, rotation rate, infrared radiation, and tilt sensors, which form the technological basis of our modern devices such as smartphones and smartwatches. While Roy Knechtel focuses on the microelectronic design and integration of the sensors, Martin Seyring is dedicated to the integration of the sensors, which is achieved through processes such as bonding and soldering, for example, thus contributing his experience in the metallurgical field of materials science. In order to advance the goal of achieving ever higher integration densities and realizing smaller, more efficient, and more powerful components, the related materials and their complex relationships are increasingly coming into focus.

One goal is to maximize the technical potential when connecting the tiny structures on and with the silicon wafer. Of course, there is not just one bonding process, but various methods that are suitable for different applications. In addition to anodic bonding and, for example, glass frit bonding, metals or alloys can also be used for bonding in metallic bonding, and this is where Martin Seyring’s research and his experience with metallic materials and the behavior of thin films come into play. What are the relationships between the individual metal layers—some of which are created during bonding, soldering, and coating—and how can these be optimized in various ways?

An important aspect of the interactions is time: diffusion and chemical reactions sometimes proceed very slowly, but their consequences are significant.  Naturally, temperature is a factor that accelerates both of these processes. This also presents an opportunity for research: by controlled increases in temperature, a longer period of time can be simulated and the effects on the materials studied. This makes it possible to answer questions such as how hot components can become or how thin the related layers can be, which is particularly relevant from the perspective of efficient high-volume production.

Where technology and ecology meet

Sustainability is an important aspect that leads us neatly to a current research project by Martin Seyring and Roy Knechtel. The title of the project is MatInWLP, which stands for material innovations in wafer-level packaging. Once again, the topics we have discussed so far come together in a new context. In addition to the focus on materials, WLP is at the center of attention: This refers to the attempt to apply the components directly to the wafer, thereby eliminating many individual process steps. In other words, with WLP, the steps involved in building semiconductor chips into usable components take place simultaneously and directly at the wafer level, including the steps of encapsulation and contacting. This project also addresses innovative 3D printing technologies that could play a role in WLP.

To understand the innovative nature of this technology, it is important to consider the current state of chip production: despite or regardless of the enormous increase in the quantity – as well as the quality – of microelectronic components produced, their manufacture still involves an immense logistical effort. The components travel around the globe for the many individual manufacturing steps, leaving a significant ecological footprint. Furthermore, the sometimes sensitive origins of related materials such as cobalt must be taken into account: the trend toward ever greater miniaturization is offset in terms of material consumption by the sheer mass of chips produced. The MatInWLP project combines technological and ecological ambitions: on the one hand, it involves the technical realization of direct integration of the components on the wafer, which is challenging enough in itself. On the other hand, it involves an attempt to minimize not only transport costs but also material usage through direct bundling on the wafer, thereby further reducing the ecological follow-up costs.

The MatInWLP research project is funded by the Carl Zeiss Foundation, which recognizes the technological, economic, and ecological potential of optimizing manufacturing processes and material combinations. Added to this are the advantages of applied sciences, such as their practical orientation, which places particular emphasis on the implementation of the knowledge gained. The project will run until early 2027 and has been awarded €1,000,000 in funding.

Endowed professorships as a source of impetus for research using the example of Roy Knechtel

Endowed professorships as a source of impetus for research using the example of Roy Knechtel

Tobias Braun

Even though endowed professorships are still quite new structures, they have now become firmly established in the German academic landscape. They offer a genuine advantage that is particularly important from the point of view of research and transfer: endowed professorships take up the innovative potential of technological developments and promote their translation into university institutions. Their number has increased in the recent past, with endowed professorships now accounting for up to 2% of the total number in Germany. Before we turn to a specific example of such an endowed professorship at Schmalkalden University of Applied Sciences, it is important to clarify what distinguishes traditional professorships from endowed professorships.

Unlike traditional professorships, the funding is not provided by the state, but by the respective donor, i.e. institutions, companies or private individuals. In addition, the period of the actual endowed professorship is limited, usually to five, sometimes ten years. In consultation with the universities, the endowed professorship is then usually converted into a traditional professorship, thus ensuring the continuity of research and the expertise acquired. A key advantage of these endowed professorships is that innovative fields of research can be developed using this method: The donors determine the thematic focus of the professorship in consultation with the relevant university committees, and provide the funds for the professorship as well as other material and investment resources (e.g. for laboratory equipment). Through these external initiatives, new topics and areas can be introduced that were previously not part of the established canon.

The attraction of these facilities for universities, apart from the point of reduced costs, largely stems from these impulses for research, as can be seen from Roy Knechtel’s endowed professorship through the Carl Zeiss Foundation at Schmalkalden University of Applied Sciences. This gave the university the opportunity to build up expertise and skills in a promising field of research. As the funding period for this endowed professorship recently came to an end, now is a good time to take stock.

Opportunities and challenges

On the one hand, newly appointed professors are usually faced with the task of having to determine the direction of their chair in research and teaching based on their interests and ideas. In addition to personnel and technology, this also includes defining thematic priorities. On the other hand, the chairs usually already exist, which means that there is a certain framework and a stock of existing personnel as well as research and teaching resources. In contrast to these continuations of traditional professorships, it is a characteristic of endowed professorships that they are newly established and not linked to an existing chair, which offers opportunities but also poses challenges.

At Schmalkalden University of Applied Sciences, Roy Knechtel was appointed to the “Autonomous Intelligent Sensor Technology” research professorship funded by the Carl Zeiss Foundation in April 2019. The professorship was funded for a period of five years and therefore lasted until March 2024. The professorship, which was funded by the Carl Zeiss Foundation as part of a program advertised at, was aimed at an area in which Roy Knechtel had acquired expertise and experience in over twenty years as part of his work at the Erfurt-based company X-FAB: The development of MEMS (Micro Electromechanical Systems) sensor technology.

In addition to smaller projects on sensor applications, a particular focus of his research in recent years has been on technological sub-steps for the realization of sensors and their 3D integration with microelectronics to create complex electronic systems, especially sensor assemblies. It goes without saying that specific systems, laboratories and equipment are required for these research questions. In the best case, these are already available, otherwise the more or less costly path of acquiring them must be taken.

When Roy Knechtel took up his professorship at Schmalkalden University of Applied Sciences, he found a cleanroom laboratory which, in addition to being particle-free, also allowed the ambient conditions such as temperature and humidity to be controlled. This was already a favorable starting point. In addition, the air conditioning technology in the clean room laboratory was modernized by the end of last year. But Roy Knechtel was also able to build on an existing foundation in terms of plant technology: Not only was there a high-temperature oven that can generate up to 800°C for glassing processes of screen printing materials, but also a screen printer and a screen cleaner. In addition to chemical boxes and a wire bonder, microscope technology, including a scanning electron microscope with EDX technology for material analyses and a soldering technology inventory with a hotplate and a semi-automatic soldering station were already available.

Laying the foundations for research

As a result, Roy Knechtel did not have to start from scratch, but was able to concentrate on systems that are central to the new field of research. The new focus on modern integration technologies in microelectronics and microsystems technology, particularly with regard to sensor integration, made it necessary to acquire processing equipment – such as various types of 3D printers – and special analysis technology in the form of microscopes.

The various 3D printers serve as the basis for research. The Anycubic Photon Mono m5s pro enables the 3D printing of plastics using photolithographic means, i.e. light. Special polymers that react to the UV component of light are used for this purpose. A resolution of up to 18.5µm can be achieved in the production of mechanical components, which represents a high level of precision. The Bambulab X1E is a filament 3D printer with various outlet nozzles for printing fine structures. Thanks to its numerous sensors and software applications, precise and fast printing is possible. Another advantage is the processing of up to 5 colors and materials in one print.

The term 3D printer only begins to describe the most important purchase: The KRONOS 15XBT[1] system is more of a 3D integration system that allows many different possibilities of processes and related components to produce electronic components in three dimensions. For example, the 5-axis system enables the use of 10 printing technologies, and furthermore, with 8 supported modules, it offers extensions of imaging processes, pre- and post-processing and result optimization. The system allows the processing of a wide variety of materials with widely differing viscosities and properties on topographically complex substrates. As a result, the range of applications is many times wider: not only can different processes for printing, curing and testing be used and combined simultaneously, but almost anything from electrically conductive pastes and insulating inks to viscous glass can also be printed.

These printing technologies are complemented by classic photolithography, which is the technological basis of modern semiconductor production. Although the newly acquired maskless digital imagesetter MLA100 from Heidelberg Instruments offers a slower working speed, it does not require expensive masks and still enables a resolution of up to one micrometer (one thousandth of a micrometer). In combination with a table-top sputtering system, it can be used to produce metallic microstructures (also as a combination of two metals) with electronic and magnetic functions or as joining systems. The combination with printing processes is the subject of current research.

In order to enable the continuation of an important research field of Roy Knechtel from his time in industry, wafer bonding, i.e. the defined stacking and joining of semiconductor wafers for the realization of three-dimensional substrates and electronic and sensor solutions, a wafer bonder system was procured thanks to special funding from the Carl Zeiss Foundation. This is now being used very intensively. As process control, i.e. analyzing the results, is also very important for wafer bonding, a Scanning Acoustic Microscope (SAM) was loaned by the company PVA Tepla, which has raised research in the field of wafer bonding to an even higher level.

Another area of acquisition is microscopy, which can be used to measure and evaluate process results, among other things. A Zeiss light microscope (LSM 700) uses a laser to reproduce the smallest features. The laser beam moves over the object and scans each point individually using the reflected light. An image is then compiled from this individual information. The microscope can also capture different layers, making it possible to create a three-dimensional model. Finally, the microscope also offers instruments for correcting the imaging.

The other microscope is also from Zeiss: it is an EVO MA15 scanning electron microscope. The objects that this microscope can capture are even smaller. In order to be able to image things the size of a strand of hair, the device does not use light, but electrons. A beam of particles is directed at the materials and the electrons knock out other electrons or bounce off them. An image is then obtained from this information. The microscope’s sharpness of detail is useful when it comes to the surfaces of microchips, for example. The tiny patterns (i.e. micro- and nanostructures) used in the manufacture of these chips can also be captured in this way. The microscope also has the option of energy dispersive X-ray (EDX), which is useful, for example, for analyzing the mixing of two metals to form an alloy. This technology makes it possible to determine which new material is involved.

The team and new challenges

With the successful acquisition of these devices, the next phase can now begin – that of intensive research on and with the devices. Micalea Wenig is a technologically adept research assistant. She ensures the smooth operation of the clean room and the equipment, is now an expert at SAM and conducts her own research. With Lukas Hauck, Roy Knechtel was able to recruit a doctoral student who is working on the 15XBT and investigating whether basic rules can be established for the use of the system with different processes and materials. In addition, Dr. Martin Seyring has joined the team as a research associate who covers an area that is highly relevant to microelectronics: materials science. In order to be able to produce ever smaller and more complex electronic components and circuits, the materials and processes involved are important. In short, a team has now come together that can make the best possible use of the technical possibilities for further research.

This is demonstrated by several research projects with Thuringian industry over the last few years. A current project funded by the Carl Zeiss Foundation has led to a further strengthening of this research group in terms of personnel and expertise (which we will be reporting on soon) and to more than ten scientific publications (reviewed articles in specialist journals and conference papers).

In conclusion, it can be said that the endowed professorship has been implemented as planned: The infrastructural foundations for state-of-the-art research have been created and expanded, an efficient research group has been established that continues to grow and work on relevant projects and has many ideas for new future research. The scientists involved and Schmalkalden University of Applied Sciences would like to express their special thanks to the Carl Zeiss Foundation for its extensive financial support, as well as for further training events such as the networking meeting of the foundation professors it has appointed, which have made this sustainable research development possible.

[1] Printing system 3D electronics integration Co-financed by the European Union as part of the funding program Directive for the Promotion of Research FTI Thuringia Research, project no. 2022 FGI 0019