Multifunctional three-dimensional assemblies, so-called mechatronic integrated devices (3D MID for short), are spatial molded parts with integrated conductor track structures that combine both mechanical and electrical functions in one component. Consequently, MID technology offers enormous technical rationalization potential in terms of material usage and process chain compared to conventional PCB technologies. Despite the existing technology potential and isolated industrially realized applications, there are currently a number of economic and technological hurdles that make it difficult for small and medium-sized companies in particular to enter this innovative field of technology. These include long process times, high process costs and, depending on the manufacturing process used, limitations in the spatial design freedom of the 3-D circuit carriers. Likewise, despite the steadily increasing demand for ceramic circuit carriers in the field of renewable energies and electric drives, there are high hurdles in the production of these power electronic components due to complex process chains and plant technology. In the planned research project, laser powder cladding (DED-LB/M; Laser based Direct Energy Deposition of Metals; coll. Laser-Cladding), which is an industrially established process for coating and repairing metallic capital goods, will be researched for the direct production of conductive structures on 3D ceramic substrates. In this context, the scientific-technical challenge is to deposit structures with high electrical conductivity and current-carrying capacity based on metallic powder materials directly on the ceramic surface by laser powder cladding without using complex upstream and downstream process steps.
Figure 1: Process technology: 5-axis laser buildup welding system; Source: LPT
For this purpose, the metallization process must be further developed to ensure that the ceramic carrier substrate is not damaged by stress cracks when the metallization is applied as a result of the thermal interaction with the incident laser beam and the molten metal powder. From a scientific point of view, one of the main objectives is to investigate the influence of process parameters and material properties on the process and the resulting structural properties. In addition, the identification of suitable metal/ceramic material combinations will be the content of scientific investigations. Within the scope of the project, initially simple linear conductor tracks and, in the further course, also more complex conductor track structures such as meander structures or aspherical conductor tracks made of significantly copper-based metallization materials directly onto ceramic carrier substrates by means of the DED-LB/M process are planned. The thermomechanical stress behavior of the ceramic plays a decisive role in the metallization process and the resulting structural properties. In past research projects, transparent thermoplastics such as trogamide have already been successfully metallized using the DED-LB/M process due to their low laser absorption capacity. However, the need to use ceramic substrate materials instead of thermoplastics for high current carrying structures, which may also be able to efficiently dissipate operating heat from high power dissipation components, was identified as a finding of the previous preliminary work. In this context, process parameter windows for the direct generation of conductive structures on ceramics will be derived by means of statistical experimental design. The adhesion of the deposited metal layer to the ceramic is based on a kind of mechanical wedging (positive connection) between the metallization material applied in the molten state and the rough ceramic surface. Furthermore, by means of established and simple thermal and atmospheric-modified post-treatment processes, it is possible to further increase the adhesion strength considerably by means of interfacial interaction. In addition, excellent current carrying capacity can be expected from the deposited copper traces with continuously fused trace core. Failure mechanisms of the deposited copper metallizations and the material composite will be investigated in both active load tests and passive environmental simulation in order to analyze their influence on the structural properties and the material composite.
The research objective is the qualification and establishment of an efficient and flexible process for the direct generation of three-dimensional ceramic circuit carriers for power electronic applications. To achieve this goal, laser powder cladding is used for selective copper deposition on 3D ceramics. For the planned target application, the process to be used is unique, innovative and still largely unknown in the literature. As a result, the construction of a functional and efficient 3D demonstrator is planned.
Figure 2: Ceramic Metal Demonstrator, Pseudo Alloy; Source: LPT
Benefits and economic significance for SMEs
Due to the flexible and efficient possibility of manufacturing power electronic 3D ceramic circuit carriers by means of laser powder buildup welding (laser powder buildup welding), this process is predestined for use by SMEs. In particular, the required conventional IR laser sources are often already available at SMEs and only require adaptation. This enables SMEs to participate in the enormously growing market for inverter components as a result of the energy transition and the electrification of mobility, and to maintain and expand their competitiveness. The R&D results of the project will directly contribute to the implementation of marketable products at SMEs. A limited level of required investment will keep the market entry barriers for SMEs to use laser powder cladding as low as possible.
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Friedrich-Alexander-University Erlangen-Nürnberg (FAU)
Institute for Factory Automation and Production Systems (FAPS)
Laser Zentrum Hannover e.V.
Project accompanying companies
The Research Association 3-D MID is still looking for companies to accompany the project. If you are interested, please contact the office via phone (+49 911 5302-9100) or E-Mail (firstname.lastname@example.org). E-Mail to office