@article{64678,
  abstract     = {{One of the major topics in the modern automotive industry is reducing emissions and increasing the mileage
range. To tackle this challenge, on the one hand, modifying the powertrain system is a possibility, and on the
other hand, lightweight design offers various possibilities. Multi-Material Design (MMD) involves designing car
bodies that combine different materials that require joining. Given the variety of materials, mechanical joining
processes are preferred. Especially the current development of the Giga/Mega-casting process concerning
aluminium casting and the subsequent mechanical joining illustrates the challenges of this material group. In car
production, aluminium castings are mainly made from aluminium-silicon (AlSi) alloys. Ultimately, the alloy
system's insufficient ductility leads to crack initiation during mechanical joining. Cast parts are therefore often
used in areas of the car body that are exposed to high-pressure loads. For example, self-piercing riveting (SPR) is
used due to its high load-bearing capacity. In this study, improved joinability is demonstrated by influencing the
microstructure through tailored solidification rates and a developed heat-treatment chain strategy adapted for
hypoeutectic AlSi systems. Data on microstructure, mechanical, and joining properties are used to develop a
solidification-joining correlation for the SPR process across a range of Si contents and solidification rates. The
purpose is to develop the ability to produce suitable aluminium castings with sufficient joinability, thereby
improving versatility.}},
  author       = {{Neuser, Moritz and Kaimann, Pia Katharina and Stratmann, Ina and Bobbert, Mathias and Klöckner, Johann Moritz Benedikt and Mann, Moritz and Hoyer, Kay-Peter and Meschut, Gerson and Schaper, Mirko}},
  journal      = {{Journal of Manufacturing Processes}},
  keywords     = {{Mechanical joining, Aluminium, Self-piercing riveting, Casting, Microstructure, Joinability AlSi-alloys}},
  publisher    = {{Elsevier}},
  title        = {{{Solidification-joinability correlation of hypoeutectic aluminium casting alloys for self-piercing riveting (SPR)}}},
  doi          = {{https://doi.org/10.1016/j.jmapro.2026.02.040}},
  volume       = {{164}},
  year         = {{2026}},
}

@inbook{65689,
  abstract     = {{The use of aluminium materials in the structural and bodywork areas of assemblies has proven to be a targeted option for lightweight design. How-ever, the reliable and cost-efficient joining of aluminium components remains a challenge. Mechanical joining methods, such as riveting, are frequently used in the automotive and aerospace construction industries. Rivets are made from heat-treated steels. Compared to steel, the use of aluminium materials for fasten-ers offers several advantages in terms of joining properties, particularly in terms of recyclability, corrosion resistance and reduced weight of the joined structure. Additionally, the manufacturing process is shorter since aluminium fasteners do not require coating. However, aluminium rivets can often not be used due to the insufficient mechanical strength of the fastener material in relation to the joining component materials.
This study systematically investigates the requirements for using solid alu-minium self-piercing rivets. The influence of rivet geometry adjustments on the joint quality is analysed using numerical simulation. The results are used to derive and evaluate an optimised rivet geometry for joining pure aluminium sheets. On this basis, solid self-drilling rivets with optimised geometry are manufactured from particle-reinforced aluminium produced in a continuous extrusion process by machining. The integration of particles increases the material’s strength. Exper-imental tests are conducted to evaluate the use of optimised solid self-piercing rivets. The quality-relevant parameters are determined and evaluated based on macrographs of the joints.}},
  author       = {{Koch, Steffen and Weber, Joshua and Meschut, Gerson and Stadelmann, Claudia and Böhm, Wolfgang and Merklein, Marion}},
  booktitle    = {{Proceedings in Engineering Mechanics}},
  isbn         = {{9783032236401}},
  issn         = {{2731-0221}},
  keywords     = {{Solid self-piercing riveting cdot particle-reinforced aluminium cdot continuous powder extrusion cdot Joining technology cdot Rivet geometry cdot lightweight design}},
  location     = {{Coimbra}},
  publisher    = {{Springer Nature Switzerland}},
  title        = {{{Particle-Reinforced Aluminium Solid Self-piercing Rivets for Joining Aluminium Alloy Sheets}}},
  doi          = {{10.1007/978-3-032-23641-8_1}},
  year         = {{2026}},
}

@article{58163,
  abstract     = {{Fibre-reinforced polymers are increasingly used due to their high specific strength, making them suitable for local sheet metal reinforcement. This allows improved overall mechanical properties with reduced wall thickness of the sheet metal part and, thus, lower weight of the components. One of the main focuses of research into such hybrid structures is on the adhesive properties and the respective failure behaviour of the interfaces. Generally, the failure behaviour under the influence of mechanical loads can be divided into adhesive, cohesive and mixed-mode failure. The correlation between observed failure behaviour and adhesion properties of the hybrid composite materials is analysed in detail in this work. The hybrid composite consists of an aluminium sheet of the alloy EN AW‑6082 T6 and thermoset carbon fibre-reinforced plastic (CFRP) prepreg. The aluminium sheet was laser pretreated before hybrid production to improve the adhesion properties. The specimens studied were produced by the prepreg pressing process, in which the components are cured and joined simultaneously. The influences of the thickness of the CFRP part, the layup, the fibre orientation at the boundary layer, and the laser pretreatment parameters on the properties of the hybrid joints were investigated.}},
  author       = {{Wu, Shuang and Delp, Alexander and Freund, Jonathan and Walther, Frank and Haubrich, Jan and Löbbecke, Miriam and Tröster, Thomas}},
  issn         = {{0021-8464}},
  journal      = {{The Journal of Adhesion}},
  keywords     = {{Prepreg pressing process, hybrid joints, laser surface pretreatment, intrinsic manufacturing, CFRP, aluminium, materials engineering}},
  pages        = {{1--26}},
  publisher    = {{Informa UK Limited}},
  title        = {{{Correlation between interlaminar shear strength of CFRP and joint strength of aluminium-CFRP hybrid joints}}},
  doi          = {{10.1080/00218464.2024.2439956}},
  year         = {{2025}},
}

@article{59872,
  abstract     = {{Lightweight design is a driving concept in modern automotive engineering to minimize resource consumption over a vehicle's lifecycle through multi-material design, which relies on the use of joining techniques in car body fabrication. Multi-material design and the increasing trend towards producing large structural components using the megacasting process pose considerable challenges, particularly in the mechanical joining of aluminium-silicon (AlSi) castings. These castings typically exhibit low ductility and are prone to cracking when mechanically joined. Based on the excellent castability of hypoeutectic AlSi alloys, these are applied in sand casting and die casting as well as in megacasting. With a silicon content between 7 wt% and 12 wt%, these AlSi-alloys have a plate-like silicon phase that initiates cracks during mechanical joining. To enhance the joinability of castings, the research hypothesis is that improved solidification conditions enable a significant modification in the microstructure and therefore, increase the mechanical properties. During the manufacture of the castings using the sand casting process, the solidification conditions within the structural elements are varied to modify the microstructure to obtain castings with graded microstructure. The castings are evaluated using mechanical, microstructural and joining testing methods and finally, a microstructure-joinability correlation is established.}},
  author       = {{Neuser, Moritz and Schlichter, Malte Christian and Hoyer, Kay-Peter and Bobbert, Mathias and Meschut, Gerson and Schaper, Mirko}},
  journal      = {{44th Conference of the International Deep Drawing Research Group (IDDRG 2025)}},
  keywords     = {{Joining, Casting, Self-pierce riveting, Aluminium casting alloy}},
  location     = {{Lissabon (Portugal)}},
  title        = {{{Mechanical joinability of microstructurally graded structural components manufactured from hypoeutectic aluminium casting alloys}}},
  doi          = {{10.1051/matecconf/202540801081}},
  volume       = {{408}},
  year         = {{2025}},
}

@article{58807,
  abstract     = {{One of the most important strategies for reducing CO2 emissions in the mobility sector is lightweight construction. In particular, the car body offers several opportunities for weight reduction. Multi-material designs are increasingly being applied to select the most suitable material for the respective load and ultimately achieve synergy effects. For example, aluminium castings are used at the nodes of a spaceframe body. Subsequently, these are joined with profiles to form the bodyshell. To join different materials mechanical joining techniques, such as semi-tubular self-piercing riveting, are deployed. According to the current state of the art, cracks occur in the aluminium castings during the mechanical joining process as a result of the high degree of deformation. Although the aluminium casting alloys of the AlSi-system exhibit low ductility, these alloys reveal excellent castability. In particular, the ability to cast thin structural parts is enabled by the low liquidus point of the near eutectic aluminium casting alloys.
This study addresses the mechanical joining properties of the near eutectic aluminium casting alloy AlSi12, depending on different microstructures. These are achieved by annealing processes and modifying agents. Through an adapted heat treatment, the previously lamellar morphology can be transformed into a globular morphology, which leads to increased ductility and prevents the formation of cracks during the self-piercing riveting (SPR). The joinability is investigated using different die geometries, whereas the joint formation is analysed regarding crack initiation. To evaluate the increased ductility, microstructural and mechanical tests are performed and finally, a microstructure-joinability correlation is established.}},
  author       = {{Neuser, Moritz and Holtkamp, Pia Katharina and Hoyer, Kay-Peter and Kappe, Fabian and Yildiz, Safak and Bobbert, Mathias and Meschut, Gerson and Schaper, Mirko}},
  journal      = {{The Journal of Materials: Design and Applications, Part L}},
  keywords     = {{aluminium, casting, microstructure, joinability, self-piercing riveting}},
  location     = {{Porto, Portugal}},
  publisher    = {{Sage Publications}},
  title        = {{{Mechanical properties and joinability of the near-eutectic aluminium casting alloy AlSi12}}},
  doi          = {{10.1177/14644207251319922}},
  year         = {{2025}},
}

@inproceedings{60645,
  abstract     = {{Die Wandlungsfähigkeit einer Prozesskette erfordert Fügeverbindungen mit gezielt einstellbaren mechanischen, elektrischen, thermischen oder chemischen Eigenschaften. Dieser Beitrag beschreibt die Untersuchungen, inwiefern beim Clinchen zweier Bleche aus der ausscheidungshärtbaren Aluminiumlegierung EN AW-6014 bereits auf Basis der Prozessüberwachung des Kraft-Weg-Verlaufs bzw. des sich daraus ergebenden Energieeintrags auf die mechanischen und elektrischen Eigenschaften der Fügeverbindung geschlossen werden kann. An einer ausgewählten Fügeaufgabe werden im Stufenversuch die gegenseitigen Abhängigkeiten der einzelnen Einflussgrößen sowie des Wärmebehandlungszustands aufgezeigt. Dabei wird zwischen den Bindemechanismen Formschluss und Kraftschluss unterschieden. Die Formschlusskomponente wird anhand der geometrischen Kenngrößen wie Bodendicke, Halsdicke und Hinterschnitt in Mikroskopieuntersuchungen an Schliffbildern und den mechanischen Eigenschaften der Fügeverbindung untersucht, die im Scherzug- und Kopfzugversuch bestimmt werden. Dazu erfolgt zudem die Charakterisierung der Versagensbilder. Zur Quantifizierung der Kraftschlusskomponente der Fügeverbindung werden das Losbrechmoment im Torsionsversuch und der elektrische Widerstand mittels Vier-Leiter-Methode ermittelt und korreliert.}},
  author       = {{Lüder, Stephan and Kalich, Jan and Oesterle, Hannes and Schmale, Hans Christian}},
  booktitle    = {{Tagung Werkstoffprüfung 2024: Werkstoffe und Bauteile auf dem Prüfstand, Prüftechnik – Kennwertermittlung – Schadensvermeidung}},
  editor       = {{Krupp, Ulrich and Steller, Ingo}},
  isbn         = {{978-3-941269-97-2}},
  keywords     = {{Clinchen, Aluminium, Stufensetzversuch, Bindemechanismus, Formschluss, Kraftschluss, Zugversuch, Torsionsversuch, Widerstandsmessung}},
  location     = {{Krefeld}},
  pages        = {{205--210}},
  title        = {{{Prozessüberwachte Eigenschaftseinstellung beim Clinchen der ausscheidungshärtbaren Aluminiumlegierung EN AW-6014}}},
  year         = {{2024}},
}

@phdthesis{41971,
  abstract     = {{Ultraschall-Drahtbonden ist eine Standardtechnologie im Bereich der Aufbau- und Verbindungstechnik von Leistungshalbleitermodulen. Um Prozessschritte und damit wertvolle Zeit zu sparen, sollen die Kupferdickdrähte für die Leistungshalbleiter auch für die Kontaktierung von eingespritzten Anschlusssteckern im Modulrahmen verwendet werden. Das Kontaktierungsverfahren mit diesen Drähten auf Steckern in dünnwandigen Kunststoffrahmen führt häufig zu unzureichender Bondqualität. In dieser Arbeit wird das Bonden von Anschlusssteckern experimentell und anhand von Simulationen untersucht, um die Prozessstabilität zu steigern.

Zunächst wurden Experimente auf Untergründen mit hoher Steifigkeit durchgeführt, um Störgrößen von Untergrundeigenschaften zu verringern. Die gewonnenen Erkenntnisse erlaubten die Entwicklung eines Simulationsmodells für die Vorhersage der Bondqualität. Dieses basiert auf einer flächenaufgelösten Reibarbeitsbestimmung im Fügebereich unter Berücksichtigung des Ultraschallerweichungseffektes und der hierdurch entstehenden hohen Drahtverformung.

Experimente an den Anschlusssteckern im Modulrahmen zeigten eine verringerte Relativverschiebung zwischen Draht und Stecker, was zu einer deutlichen Verringerung der Reibarbeit führt. Außerdem wurden verminderte Schwingamplituden des Bondwerkzeugs nachgewiesen. Dies führt zu einer weiteren Reduktion der Reibarbeit. Beide Effekte wurden mithilfe eines Mehrmassenschwingers modelliert. Die gewonnenen Erkenntnisse und die erstellten Simulationsmodelle ermöglichen die Entwicklung von Klemmvorrichtungen, welche die identifizierten Störgrößen gezielt kompensieren und so ein verlässliches Bonden der Anschlussstecker im gleichen Prozessschritt ermöglichen, in dem auch die Leistungshalbleiter kontaktiert werden.}},
  author       = {{Althoff, Simon}},
  isbn         = {{978-3-8440-8903-5}},
  keywords     = {{heavy copper bonding, wire bonding, quality prediction, friction model, point-contact-element}},
  pages        = {{192}},
  publisher    = {{Shaker}},
  title        = {{{Predicting the Bond Quality of Heavy Copper Wire Bonds using a Friction Model Approach}}},
  volume       = {{15}},
  year         = {{2023}},
}

@inproceedings{44036,
  abstract     = {{<jats:p>Abstract. In order to reduce global energy consumption in production and industry along with the associated CO2 emissions, existing resources must be used more efficiently. This includes the energy-efficient and comprehensive recycling of a wide range of metals. Especially for the production of aluminium, there is a large potential for saving energy using efficient recycling processes. With regard to the recycling of aluminium studies have shown that solid-state recycling processes are significantly more efficient considering the used energy and resources compared to the conventional, smelting-metallurgical recycling process. In this paper, the direct and energy-efficient friction-induced recycling process (FIRP) based on the conform process is further described and analysed in terms of the temperature-property relationships. For this purpose, the influence of the processing temperature on the microstructure and properties of the recycled semi-finished products is investigated using the toll system that enables an ECAP forming. Specific sections of the (in theory) infinite, recycled semi-finished product are taken and analysed at different process temperatures of the solid state recycling process. Based on these sections, the properties in terms of mechanical hardness, strength, ductility and grain size are analysed and a degressive relationship between process temperature and mechanical hardness up to a temperature of 270 °C can be shown. Applying the Hall-Petch relationship, it is analysed whether there is a correlation between the strength and the microstructure in the form of the grain size. </jats:p>}},
  author       = {{Borgert, Thomas and Homberg, Werner}},
  booktitle    = {{Materials Research Proceedings}},
  issn         = {{2474-395X}},
  keywords     = {{Recycling, Aluminium, Friction-Induced, Energy Efficiency}},
  location     = {{Kraków}},
  publisher    = {{Materials Research Forum LLC}},
  title        = {{{Analysis of temperature effect on strength and microstructure in friction induced recycling process (FIRP)}}},
  doi          = {{10.21741/9781644902479-211}},
  year         = {{2023}},
}

@inproceedings{43044,
  abstract     = {{<jats:p>Abstract. The combination of incremental sheet metal forming and high-speed forming offers new possibilities for flexible forming processes in the production of large sheet metal components of increased complexity with relatively low forming energies. In this paper, the general feasibility and process differences between the pulse-driven high-speed forming technologies of electrohydraulic and electromagnetic forming were investigated. An example component made of EN AW 6016 aluminum sheet metal was thus formed incrementally by both processes and the forming result evaluated by an optical 3D measurement system. For this purpose, a forming strategy for electromagnetic incremental forming (EMIF) was developed, tested and adapted to the electrohydraulic incremental forming process (EHIF). The discharge energy, the tool displacement and the pressure field of the forming zone were determined as relevant parameters for the definition of an adequate tool path strategy. It was found that the EHIF process is less affected by larger distances between the tool and the blank, while this is a critical variable for force application to the component during EMIF. On the other hand, the more uniform pressure distribution of the EMIF process is advantageous for forming large steady component areas. </jats:p>}},
  author       = {{Holzmüller, Maik and Linnemann, Maik and Homberg, Werner and Psyk, Verena and Kräusel, Verena  and Kroos, Janika}},
  booktitle    = {{Materials Research Proceedings}},
  issn         = {{2474-395X}},
  keywords     = {{Incremental Sheet Forming, Aluminium, High-Speed Forming}},
  location     = {{Nürnberg}},
  pages        = {{11--18}},
  publisher    = {{Materials Research Forum LLC}},
  title        = {{{Proof of concept for incremental sheet metal forming by means of electromagnetic and electrohydraulic high-speed forming}}},
  doi          = {{10.21741/9781644902417-2}},
  volume       = {{25}},
  year         = {{2023}},
}

@inproceedings{60647,
  abstract     = {{Das umformtechnische Fügeverfahren Clinchen ermöglicht ein energiearmes Fügen von Blechen und dient traditionell der Übertragung mechanischer Kräfte. Neue Einsatzgebiete erfordern eine elektrische oder thermische Leitfähigkeit, sodass es notwendig ist, das Clinchen entsprechend zu qualifizieren. Es wurden Untersuchungen an Aluminiumverbindungen durchgeführt, welche mit hohen Kurzzeitströmen belastet wurden. Der Einfluss verschiedener Oberflächenvorbehandlungen wurde betrachtet. Als Charakterisierungsmethode für die Bauteile und die geclinchten Fügeverbindungen wird die Messung des elektrischen Widerstandes herangezogen. Die untersuchten Clinchverbindungen sind fähig, die im Fehlerfall auftretenden Kurzzeitströme zu übertragen. Der Oberflächenzustand übt dabei einen signifikanten Einfluss auf die Clinchpunktausbildung und damit auf deren elektrische Eigenschaften aus. Durch Messung des elektrischen Widerstandes vor und nach dem Fügen sowie nach einer Bestromung mit Fehlerströmen, kann das Kontaktverhalten qualifiziert werden.}},
  author       = {{Reschke, Gregor and Kalich, Jan and Füssel, Uwe}},
  booktitle    = {{Tagung Werkstoffprüfung 2022: Werkstoffe und Bauteile auf dem Prüfstand, Prüftechnik – Kennwertermittlung – Schadensvermeidung}},
  editor       = {{Zimmermann, Martina}},
  isbn         = {{978-3-88355-430-3}},
  keywords     = {{Clinchen, Bindemechanismen, elektrische Eigenschaften, Aluminium, Kurzzeitbestromung}},
  location     = {{Dresden}},
  pages        = {{374--379}},
  title        = {{{Methoden zur Charakterisierung der Bindemechanismen bei geclinchten elektrischen Kontakten}}},
  year         = {{2023}},
}

@article{24589,
  abstract     = {{Additive manufacturing, e.g. by laser powder bed fusion (LPBF), is very attractive for lightweight constructions, as complex and stress-optimised structures integrating multiple functions can be produced within one process. Unfortunately, high strength AlZnMgCu alloys tend to hot cracking during LPBF
and thus have not so far been applicable. In this work the melting and solidification behaviour of
AlZnMgCu alloy powder variants with particle surface inoculation was analysed by Differential Fast
Scanning Calorimetry. The aim is to establish a method that makes it possible to assess powder modifications in terms of their suitability for LPBF on a laboratory scale requiring only small amounts of powder.
Therefore, solidification undercooling is evaluated at cooling rates relevant for LPBF. A method for the
temperature correction and normalisation of the DFSC results is proposed. Two ways of powder modification were tested for the powder particles surface inoculation by titanium carbide (TiC) nanoparticles:
via wet-chemical deposition and via mechanical mixing.
A low undercooling from DFSC correlates with a low number of cracks of LPBF-manufactured cubes. It
appears that a reduced undercooling combined with reduced solidification onset scatter indicates the
possibility of crack-free LPBF of alloys that otherwise tend to hot cracking.}},
  author       = {{Zhuravlev, Evgeny and Milkereit, Benjamin and Yang, Bin and Heiland, Steffen and Vieth, Pascal and Voigt, Markus and Schaper, Mirko and Grundmeier, Guido and Schick, Christoph and Kessler, Olaf}},
  issn         = {{0264-1275}},
  journal      = {{Materials & Design}},
  keywords     = {{Aluminium alloy 7075, Differential fast scanning calorimetry, Solidification, Undercooling, Additive manufacturing}},
  title        = {{{Assessment of AlZnMgCu alloy powder modification for crack-free laser powder bed fusion by differential fast scanning calorimetry}}},
  doi          = {{10.1016/j.matdes.2021.109677}},
  year         = {{2021}},
}

@phdthesis{37579,
  abstract     = {{Leichtmetalle mit einem breiten Eigenschaftsspektrum gewährleisten die Realisierung ressourcenschonender Produkte und ermöglichen die Intensivierung sortenreiner Kreislaufwirtschaften. Die vorliegende Arbeit untersucht einen wärmeunterstützten Ansatz zur Erhöhung der Formgebungsgrenzen stark kaltverfestigter AlMg4,5 Blechwerkstoffe bei gleichzeitiger Beschränkung des Festigkeitsverlustes durch Erholungseffekte. Experimentelle Untersuchungen stellen eine wissenschaftlich fundierte Erkenntnisbasis über die werkstofftechnischen Wirkzusammenhänge des untersuchten Prozesses dar. Gepaart mit an realen Bauteilgeometrien validierten numerischen Simulationsmodellen legt diese Arbeit einen methodischen Grundstein für die industrielle Umsetzung des hier untersuchten Blechumformprozesses. Die erzielte mittlere Dehngrenze des exemplarisch untersuchten Bauteils übersteigt die Dehngrenze eines konventionellen AlMg4,5 Werkstoffes um 190 %. Mit 320 MPa entspricht sie dem Festigkeitsniveau des walzharten Blechhalbzeuges im Lieferzustand, ein Wert, der nach dem aktuellen Stand der Technik auf Bauteilebene ausschließlich mit aushärtbaren AlMgSi Legierungen darstellbar ist. }},
  author       = {{Camberg, Alan Adam}},
  isbn         = {{978-3-8440-8271-5}},
  keywords     = {{Aluminium, Blechumformung, AlMg, Materialmodellierung, Duktiles Versagen, Halbwarmumformung, Automobil, Leichtbau, Uni-Alloy, 5000-Serie, 5182, GISSMO}},
  pages        = {{230}},
  publisher    = {{Shaker Verlag}},
  title        = {{{Festigkeitssteigerung von Aluminiumblechformteilen der 5000-Serie durch Erweiterung der Formgebungsgrenzen stark kaltverfestigter Ausgangswerkstoffe}}},
  doi          = {{10.2370/9783844082715}},
  volume       = {{2021,52}},
  year         = {{2021}},
}

@article{21436,
  abstract     = {{Ultrasonic wire bonding is a solid-state joining process, used in the electronics industry to form electrical connections, e.g. to connect electrical terminals within semiconductor modules. Many process parameters affect the bond strength, such like the bond normal force, ultrasonic power, wire material and bonding frequency. Today, process design, development, and optimization is most likely based on the knowledge of process engineers and is mainly performed by experimental testing. In this contribution, a newly developed simulation tool is presented, to reduce time and costs and efficiently determine optimized process parameter. Based on a co-simulation of MATLAB and ANSYS, the different physical phenomena of the wire bonding process are considered using finite element simulation for the complex plastic deformation of the wire and reduced order models for the transient dynamics of the transducer, wire, substrate and bond formation. The model parameters such as the coefficients of friction between bond tool and wire and between wire and substrate were determined for aluminium and copper wire in experiments with a test rig specially developed for the requirements of heavy wire bonding. To reduce simulation time, for the finite element simulation a restart analysis and high performance computing is utilized. Detailed analysis of the bond formation showed, that the normal pressure distribution in the contact between wire and substrate has high impact on bond formation and distribution of welded areas in the contact area.}},
  author       = {{Schemmel, Reinhard and Krieger, Viktor and Hemsel, Tobias and Sextro, Walter}},
  issn         = {{0026-2714}},
  journal      = {{Microelectronics Reliability}},
  keywords     = {{Ultrasonic heavy wire bonding, Co-simulation, ANSYS, MATLAB, Process optimization, Friction coefficient, Copper-copper, Aluminium-copper}},
  pages        = {{114077}},
  title        = {{{Co-simulation of MATLAB and ANSYS for ultrasonic wire bonding process optimization}}},
  doi          = {{https://doi.org/10.1016/j.microrel.2021.114077}},
  volume       = {{119}},
  year         = {{2021}},
}

@article{19973,
  abstract     = {{As a result of lightweight design, increased use is being made of high-strength steel and aluminium in car bodies. Self-piercing riveting is an established technique for joining these materials. The dissimilar properties of the two materials have led to a number of different rivet geometries in the past. Each rivet geometry fulfils the requirements of the materials within a limited range. In the present investigation, an improved rivet geometry is developed, which permits the reliable joining of two material combinations that could only be joined by two different rivet geometries up until now. Material combination 1 consists of high-strength steel on both sides, while material combination 2 comprises aluminium on the punch side and high-strength steel on the die side. The material flow and the stress and strain conditions prevailing during the joining process are analysed by means of numerical simulation. The rivet geometry is then improved step-by-step on the basis of this analysis. Finally, the improved rivet geometry is manufactured and the findings of the investigation are verified in experimental joining tests.}},
  author       = {{Uhe, Benedikt and Kuball, Clara-Maria and Merklein, Marion and Meschut, Gerson}},
  journal      = {{Production Engineering}},
  keywords     = {{Self-piercing riveting, Joining technology, Rivet geometry, Multi-material design, High-strength steel, Aluminium}},
  pages        = {{417--423}},
  title        = {{{Improvement of a rivet geometry for the self-piercing riveting of high-strength steel and multi-material joints}}},
  doi          = {{10.1007/s11740-020-00973-w}},
  volume       = {{14}},
  year         = {{2020}},
}

@inproceedings{9999,
  abstract     = {{Ultrasonic wire bonding is an indispensable process in the industrial manufacturing of semiconductor devices. Copper wire is increasingly replacing the well-established aluminium wire because of its superior electrical, thermal and mechanical properties. Copper wire processes differ significantly from aluminium processes and are more sensitive to disturbances, which reduces the range of parameter values suitable for a stable process. Disturbances can be compensated by an adaption of process parameters, but finding suitable parameters manually is difficult and time-consuming. This paper presents a physical model of the ultrasonic wire bonding process including the friction contact between tool and wire. This model yields novel insights into the process. A prototype of a multi-objective optimizing bonding machine (MOBM) is presented. It uses multi-objective optimization, based on the complete process model, to automatically select the best operating point as a compromise of concurrent objectives.}},
  author       = {{Unger, Andreas and Hunstig, Matthias and Meyer, Tobias and Brökelmann, Michael and Sextro, Walter}},
  booktitle    = {{In Proceedings of IMAPS 2018 – 51st Symposium on Microelectronics, Pasadena, CA, 2018}},
  keywords     = {{wire bonding, multi-objective optimization, process model, copper wire, self-optimization}},
  title        = {{{Intelligent Production of Wire Bonds using Multi-Objective Optimization – Insights, Opportunities and Challenges}}},
  doi          = {{10.4071/2380-4505-2018.1.000572}},
  volume       = {{Vol. 2018, No. 1, pp. 000572-000577.}},
  year         = {{2018}},
}

@article{13186,
  abstract     = {{Ligands DMEG6etqu, TMG6etqu, DMEG6buqu, and TMG6buqu were developed on the basis of guanidine quinoline (GUAqu) ligands 1,3-dimethyl-N-(quinolin-8-yl)imidazolidin-2-imine (DMEGqu) and 1,1,3,3-tetramethyl-2-(quinolin-8-yl)guanidine (TMGqu). These ligands feature an alkyl substituent at the C6 of the quinoline backbone. The synthetic strategy developed here enables inexpensive syntheses of any kind of C6-substituted GUAqu ligands. On one hand, the alkylation increases the solubility of corresponding copper complexes in apolar atom transfer radical polymerization (ATRP) monomers like styrene. On the other hand, it has a significant electronic influence and thus an effect on the donor properties of the new ligands. Seven CuI and CuII complexes of DMEG6etqu and TMG6etqu have been crystallized and were studied with regard to their structural and electrochemical properties. CuI and CuII complexes of DMEG6buqu and TMG6buqu turned out to be perfectly soluble in pure styrene even at room temperature, which makes them excellent catalysts in the ATRP of apolar monomers. The key characteristics of the ATRP equilibrium, KATRP and kact, were determined for the new complexes. In addition, we used our recently developed DFT methodology, NBO analysis, and isodesmic reactions to predict the influence of the introduced alkyl substituents. It turned out that high conformational freedom in the complex structures leads to a significant uncertainty in prediction of the thermodynamic properties.}},
  author       = {{Rösener, Thomas and Hoffmann, Alexander and Herres-Pawlis, Sonja}},
  journal      = {{European Journal of Inorganic Chemistry}},
  keywords     = {{Copper, Polymerization, Redox chemistry, Structure elucidation, Ligand effects}},
  number       = {{27}},
  pages        = {{3164--3175}},
  title        = {{{Next Generation of Guanidine Quinoline Copper Complexes for Highly Controlled ATRP: Influence of Backbone Substitution on Redox Chemistry and Solubility}}},
  doi          = {{10.1002/ejic.201800511}},
  volume       = {{2018}},
  year         = {{2018}},
}

@article{13187,
  abstract     = {{Abstract The reaction of Cu(I) bisguanidine complexes with nitric oxide and the formation of intermediate species were monitored via UV-vis spectroscopy at low temperature, with the occurrence of characteristic absorption bands. The origin of the emerging species and their character were substantiated by electron paramagnetic resonance (EPR) measurements and density functional theory (DFT) studies showing a delocalized {CuNO}11 radical species. Furthermore, this system was transferred to the SuperFocus mixer setup, which allows rapid mixing and the determination of decay constants at ambient temperatures of the thermally sensitive species. However, these experiments demonstrated the limits of these systems, such as the NO saturation in organic solvents and a preferably precise temperature control within the SuperFocus mixer, which should be addressed in the future.}},
  author       = {{Oppermann, Alexander and Laurini, Larissa and Etscheidt, Fabian and Hollmann, Katharina and Strassl, Florian and Hoffmann, Alexander and Schurr, Daniela and Dittmeyer, Roland and Rinke, Günter and Herres-Pawlis, Sonja}},
  journal      = {{Chemical Engineering \& Technology}},
  keywords     = {{Copper guanidine complexes, Nitric oxide, SuperFocus mixer}},
  number       = {{8}},
  pages        = {{1475--1483}},
  title        = {{{Detection of Copper Bisguanidine NO Adducts by UV-vis Spectroscopy and a SuperFocus Mixer}}},
  doi          = {{10.1002/ceat.201600691}},
  volume       = {{40}},
  year         = {{2017}},
}

@inproceedings{9959,
  abstract     = {{Ultrasonic heavy wire bonding is a commonly used technology to conduct electrical devices in power electronics. In order to facilitate powerful solutions combined with an increased efficiency, involving a material change from aluminum to copper wire as conductor material takes place in recent years. Due to the material related properties, copper wire bonding requires significant higher bond processing parameters such as bond force and ultrasonic power compared to aluminum which can lead to damages or a failure of the bonded component. Therefore, a profound knowledge of the processes prevailing during wire bonding is essential to optimize the application of the copper wires and consequently to achieve the demands on quality and reliability. The behavior of different natural surface oxides of aluminum and copper are assumed to be one reason for the deviation in the required bond parameters. Accordingly, the impact of differently pre-treated substrates surfaces on which the bonding is applied were investigated in this study. First, all conditions investigated (as-received, oxidefree, AlOx and the CuOx) were characterized by utilizing scanning electron microscopy, energy dispersive X-ray spectroscopy, focused ion beam microscopy and atomic force microscopy. In addition, hardness tests were performed as well as perthometer measurements. Afterwards, a 500 $\mu$ m copper wire was bonded on the generated surfaces investigated. In consideration of the roughness, shear test of various bond times and microscopic images were evaluated. Finally, the results were compared and discussed. Overall, the current study indicates that an Al-oxide layer is beneficial for welding process in Cu wire bonding. On the contrary, the Cu-oxide is detrimental and leads to a delayed welding of the joining parts. Based on the obtained results, it can be expected that due to an ideal set of Al-oxide layers, lower optimal bond parameters can used to reach high bond strength with good reliability properties.}},
  author       = {{Eacock, Florian and Unger, Andreas and Eichwald, Paul and Grydin, Olexandr and Hengsbach, Florian and Althoff, Simon and Schaper, Mirko and Guth, Karsten}},
  booktitle    = {{IEEE 66th Electronic Components and Technology Conference}},
  keywords     = {{Ultrasonic copper wire bonding, Al-oxide, Cuoxide, oxide-free, roughness, morphology}},
  pages        = {{2111--2118}},
  title        = {{{Effect of different oxide layers on the ultrasonic copper wire bond process}}},
  doi          = {{10.1109/ECTC.2016.91}},
  year         = {{2016}},
}

@inproceedings{9966,
  abstract     = {{Usage of copper wire bonds allows to push power boundaries imposed by aluminum wire bonds. Copper allows higher electrical, thermal and mechanical loads than aluminum, which currently is the most commonly used material in heavy wire bonding. This is the main driving factor for increased usage of copper in high power applications such as wind turbines, locomotives or electric vehicles. At the same time, usage of copper also increases tool wear and reduces the range of parameter values for a stable process, making the process more challenging. To overcome these drawbacks, parameter adaptation at runtime using self-optimization is desired. A self-optimizing system is based on system objectives that evaluate and quantify system performance. System parameters can be changed at runtime such that pre-selected objective values are reached. For adaptation of bond process parameters, model-based self-optimization is employed. Since it is based on a model of the system, the bond process was modeled. In addition to static model parameters such as wire and substrate material properties and vibration characteristics of transducer and tool, variable model inputs are process parameters. Main simulation result is bonded area in the wiresubstrate contact. This model is then used to find valid and optimal working points before operation. The working point is composed of normal force and ultrasonic voltage trajectories, which are usually determined experimentally. Instead, multiobjective optimalization is used to compute trajectories that simultaneously optimize bond quality, process duration, tool wear and probability of tool-substrate contacts. The values of these objectives are computed using the process model. At runtime, selection among pre-determined optimal working points is sufficient to prioritize individual objectives. This way, the computationally expensive process of numerically solving a multiobjective optimal control problem and the demanding high speed bonding process are separated. To evaluate to what extent the pre-defined goals of self-optimization are met, an offthe- shelf heavy wire bonding machine was modified to allow for parameter adaptation and for transmitting of measurement data at runtime. This data is received by an external computer system and evaluated to select a new working point. Then, new process parameters are sent to the modified bonding machine for use for subsequent bonds. With these components, a full self-optimizing system has been implemented.}},
  author       = {{Meyer , Tobias and Unger, Andreas and Althoff, Simon and Sextro, Walter and Brökelmann, Michael and Hunstig, Matthias and Guth, Karsten}},
  booktitle    = {{IEEE 66th Electronic Components and Technology Conference}},
  keywords     = {{Self-optimization, adaptive system, bond process, copper wire}},
  pages        = {{622--628}},
  title        = {{{Reliable Manufacturing of Heavy Copper Wire Bonds Using Online Parameter Adaptation}}},
  doi          = {{10.1109/ECTC.2016.215}},
  year         = {{2016}},
}

@inproceedings{9868,
  abstract     = {{In order to increase mechanical strength, heat dissipation and ampacity and to decrease failure through fatigue fracture, wedge copper wire bonding is being introduced as a standard interconnection method for mass production. To achieve the same process stability when using copper wire instead of aluminum wire a profound understanding of the bonding process is needed. Due to the higher hardness of copper compared to aluminum wire it is more difficult to approach the surfaces of wire and substrate to a level where van der Waals forces are able to arise between atoms. Also, enough friction energy referred to the total contact area has to be generated to activate the surfaces. Therefore, a friction model is used to simulate the joining process. This model calculates the resulting energy of partial areas in the contact surface and provides information about the adhesion process of each area. The focus here is on the arising of micro joints in the contact area depending on the location in the contact and time. To validate the model, different touchdown forces are used to vary the initial contact areas of wire and substrate. Additionally, a piezoelectric tri-axial force sensor is built up to identify the known phases of pre-deforming, cleaning, adhering and diffusing for the real bonding process to map with the model. Test substrates as DBC and copper plate are used to show the different formations of a wedge bond connection due to hardness and reaction propensity. The experiments were done by using 500 $\mu$m copper wire and a standard V-groove tool.}},
  author       = {{Althoff, Simon and Neuhaus, Jan and Hemsel, Tobias and Sextro, Walter}},
  booktitle    = {{Electronic Components and Technology Conference (ECTC), 2014 IEEE 64th}},
  keywords     = {{adhesion, circuit reliability, deformation, diffusion, fatigue cracks, friction, interconnections, lead bonding, van der Waals forces, Cu, adhering process, adhesion process, ampacity improvement, bond quality improvement, cleaning process, diffusing process, fatigue fracture failure, friction energy, friction model, heat dissipation, mechanical strength, piezoelectric triaxial force sensor, predeforming process, size 500 mum, total contact area, van der Waals forces, wedge copper wire bonding, Bonding, Copper, Finite element analysis, Force, Friction, Substrates, Wires}},
  pages        = {{1549--1555}},
  title        = {{{Improving the bond quality of copper wire bonds using a friction model approach}}},
  doi          = {{10.1109/ECTC.2014.6897500}},
  year         = {{2014}},
}