Sustainability Strategies for Ceramic-Based Power Electronics

Why is sustainable power electronics even of interest to ceramics experts?

L. Rebenklau: As key areas of technology such as mobility and industry become increasingly electrified, there is increasing demand for power electronics. Ceramics have a key role to play here because they ensure the robustness of substrates and packages, especially at high temperatures and in harsh operating conditions. Modern concepts such as wide bandgap semiconductors also rely heavily on ceramic wiring substrates. At the same time, we need to develop technical solutions that meet regulatory requirements such as the EU Ecodesign Directive. And we also have to find answers to the so-called R strategies. Ceramics don’t receive any special treatment compared to competing material classes.
 

What are the R strategies and how are they implemented with ceramics?

L. Rebenklau: The nine R strategies are a circular economy concept aimed at conserving valuable resources. Well-known examples include “Reuse” and “Recycle,” which present challenges for all ceramic materials as well as other materials used in electronics.

U. Langklotz: Less well known but just as important are strategies such as “Rethink”, “Repair”, “Refurbish” and “Remanufacture.” Here, modern solutions such as those created by Fraunhofer IKTS allow ceramic electronic packages to be designed from the outset so they can be repaired, refurbished or repurposed more easily.
 

Aren’t these rather abstract concepts?

L. Rebenklau: Not at all! Repairing printed circuit board-based electronics and enabling their future reuse is already a key issue in industrial energy and drive technology today. The same applies to device reuse and the legally required long-term availability of spare parts. Industry needs solutions for “Repair” and “Remanufacture”, but above all for a broader “Rethink.”

U. Langklotz: Let’s take a closer look at “Rethink”. Under the Ecodesign Directive, we have to ask not only: “What’s inside?” but also: “Can it be repaired?” and: “Can its service life be extended as far as possible?” As ceramics experts, we can always find solutions to increase reliability and service life. This might include new thin-film coatings that protect against corrosive attacks. At the same time, such solutions can make accessibility, dismantling and clean material separation of individual components more difficult in the event of repair or at end of life. So, we’re dealing with conflicting requirements that call for smart solutions.
 

Are there other approaches to “rethinking” power electronics?

U. Langklotz: Yes, indeed. In addition to smart material combinations, we can also make the power electronic system itself more intelligent. Here, we’re talking about integrating sensors that enable condition monitoring of the package. This opens up new options for preventive maintenance concepts. The system’s integrity and reliability can be assessed during service or repair, enabling evidence-based and more targeted decisions about repair or replacement.
 

How exactly does that work in practice?

U. Langklotz: Take encapsulation compounds that protect electronics from environmental influences. These have to adhere very strongly, so they’re inherently difficult to remove during servicing. If the interface between the encapsulation compound and the ceramic fails – which can happen due to minor manufacturing defects – moisture can penetrate. Metal components begin to corrode and the electronics fail. At IKTS, we developed a simple solution in which printed conductive tracks on the ceramic surface are used to perform electrochemical impedance measurements at the interface between encapsulation compound and electronics. If the interface is intact, impedance values remain within defined target ranges, making it easy to determine whether the encapsulation is still uncompromised or whether corrosion has occurred. This simple, non-destructive diagnostic approach prevents “just in case” precautionary replacement and simplifies troubleshooting – and therefore repairability.
 

What solutions does Fraunhofer IKTS offer when repair is actually required?

L. Rebenklau: We start with material solutions. Ceramic power modules used to be designed in such a way that they couldn’t be repaired. We’re changing that by developing new layer systems that allow simple separation of substrate and semiconductor – in other words, detachable connections. We’re also working on specific repair techniques that will enable component replacement. In the long term, these techniques have to be standardized and certified so that industry can rely on renewed long-term reliability in operation.
 

What happens if the electronics can no longer be repaired?

A. Gerbeth: If repair is no longer possible, material recycling must follow – as completely as possible of course. Power electronic packages are highly compact and stable by design and contain a large number of valuable components in a very small space. “Rethink” at the design stage is essential when it comes to optimizing the recycling process, because design decisions determine whether material-selective pre-separation of components is feasible. In recycling itself, we draw on the full breadth of IKTS expertise. Using electrohydraulic separation, we’re able to break down composite materials such as ceramic packages in a very energy-efficient way and separate them into metallic and ceramic particles. Hydrometallurgical and electrochemical purification processes then allow us to recover metals very efficiently. IKTS has been applying these methods for years in battery recycling and resource technologies, and there are significant synergies.

So these issues aren’t actually that new to Fraunhofer IKTS?

L. Rebenklau: No. IKTS has been actively involved in many of these fields for decades, but we’re now combining them under the umbrella of sustainable power electronics. Ceramics for electronics has long been an IKTS research area – from material development and thick-film technology through to packaging technology. What’s new are electrochemical approaches such as integrated sensors, electroplated protective and functional coatings, along with a deeper understanding of corrosion processes.

Are there external partners collaborating with IKTS?

L. Rebenklau: TU Dresden and TU Bergakademie Freiberg in particular contribute a tradition of outstanding expertise in processing and recycling technologies. We also work with industry partners. Currently, a number of automotive suppliers are highly engaged in sustainable power electronics as they navigate the transition to electromobility and seek new business opportunities.

Together with our partners, we’re actively involved in the Industrial Collective Research project GANZ Power Electronics, where we pursue a holistic approach to sustainable power electronics – from new protective and functional coatings through to integrated self-monitoring and repair concepts, as well as efficient dismantling and recovery technologies for critical raw materials. These solutions are specifically tailored to the needs of SMEs.
 

How will the results of these projects be transferred to practical applications?

L. Rebenklau: We’re pursuing two paths here. On the one hand, we’re developing design concepts and processes that are to become industry standards. These may include specific layer systems that require standardized joining and soldering processes or defined repair protocols for refurbished systems. On the other hand, we engage directly with users, working with them to develop solutions and devices that can be used by independent repair service providers for power electronics or integrated as sensor components into packages.

A. Gerbeth: On the materials side, we primarily offer consulting services, for example when recycling providers are looking to make their processes more selective and energy-efficient. We have robust process engineering expertise and pilot-scale hardware that facilitate adoption and scaling of recycling processes for our customers.