Powerful engine for the energy transition: Setting off into a green future with the packaging of efficient electronic power modules

Climate-friendly, sustainable, and resource-efficient – to create a future worth living for coming generations, the energy transition has to be accelerated. Alongside the development of renewable energy sources, electric mobility is a key element on the way to a green future with reduced CO₂ emissions. Characterized by an electrified automotive landscape, it is successfully helping to shape a climate-friendly transportation and energy transition. Highly complex electronic power modules are the key to modern drive systems in today’s electric vehicles. Based on many years of expertise in the field of innovative packaging and contacting technologies, Fraunhofer ENAS is co-developing them in Chemnitz. Together with its partners, the institute is laying the foundations for making precise packaging technologies for power modules significantly more efficient and increasing the speed of their market launch in the fields of electric mobility and renewable energies.

The energy transition is a key issue of our time. It is synonymous with the development of renewable energy sources, a sustainable energy supply without fossil fuels, and a climate-friendly and green future. Electric mobility is a key driver on this path. Thanks to ongoing technological advances, it can make a decisive contribution to climate-friendly road traffic and the energy transition.

Along with autonomous driving, vehicle digitization, connectivity, new mobility services, and the electrification of the vehicle powertrain with a shift away from the combustion engine is one of the four megatrends in the mobility sector that will contribute to fundamental changes in the automotive industry. Combined drive solutions consisting of environmentally friendly electric drives and energy recovery systems are ideally suited to enable climate-friendly and CO₂-free mobility. On the one hand, they support a reduction in pollutants and, on the other, virtually silent driving, which significantly reduces noise pollution in road traffic and thus contributes to a better quality of life in cities.

 

Sophisticated: High quality and performance requirements for module elements of power electronics

Efficient high-performance modules are at the heart of electric drive solutions for electric vehicles. Using innovative assembly and interconnection technologies, they connect module elements of power electronics via mechanical, electrical, and thermal contacts as well as combine them on application-specific carriers and substrates.

Their particular strength lies in their robustness, temperature resistance, and stability: “The power modules produced in this way are extremely reliable, durable, and insensitive, so that they can withstand harsh environmental conditions as well as high energy and heat densities,” explains Christian Hofmann, scientist in the “Systems Packaging” department at Fraunhofer ENAS, who is co-developing the power packages in Chemnitz. The modules are not only used in electric drives, but also in photovoltaic systems and wind energy plants as well as for energy storage, distribution, and recovery.

A key challenge of such power-intensive applications is the heat generation. To prevent damage or failure of electronic components due to overheating, the resulting heat loss must be dissipated quickly and reliably. This place high demands on the system design of the power modules, the choice of materials, and the packaging technologies, which must be optimally coordinated and work together efficiently. This ensures that the heat generated is dissipated through bonding layers, substrates, and base plates before it is released to the environment using a heat exchanger or heat sink.

 

Powerful: Packaging technologies in the focus of current developments

Ready-to-use, innovative, and cost-efficient production and interconnection technologies are essential for the production of power electronics components and assemblies. Power modules are packaged into robust solutions using state-of-the-art technologies and processes, such as soldering, wire bonding, and encapsulating. The mechanical, thermal, and electrical connections of the power semiconductor devices to the substrate (die attach) as well as the substrates to the base plate and heat sink (large area attach) are optimally coordinated in order to meet the increasing requirements for power density, performance, and reliability during manufacturing.

Inductive soldering and particle sintering, developed at Fraunhofer ENAS in cooperation with Chemnitz University of Technology, represent highly innovative approaches to meet the continuously increasing challenges of the future. The two processes enable fast, precise, and energy-efficient heat input into the primary bonding zone, thus reducing the thermal load on the entire assembly. They also offer the advantage of significantly reduced process and cycle times in power components manufacturing, optimizing production processes and speeds.

Reducing system losses is another important focus of current research efforts, particularly for battery-electric drives in the field of electric mobility – driven by the desire for greater range and shorter charging times. One promising approach is to change the semiconductor material of the switching elements for power electronics from silicon to silicon carbide (SiC) and gallium nitride (GaN). This innovation offers the potential to significantly reduce conduction and switching losses in the inverter, increase switching speeds, and improve the temperature resistance of the module elements. 

 

Strong together: Your partner for innovative packaging technologies as well as characterization and reliability analysis of power components

As an established research and development partner, Fraunhofer ENAS in Chemnitz has many years of comprehensive core competencies in the field of innovative packaging technologies as well as characterization and reliability analyses, which are essential for the development of highly efficient power modules. This is reflected in a wide range of technologies and extensive technical expertise:

1. Packaging processes and associated technologies:

• Printing technologies for the deposition of bonding layers (for example, stencil and screen printing, aerosol jetting, dispensing)
• High-precision mounting/chip placement
• Bonding technologies for single and multi-die attach as well as large-area attach for the realization of complex power modules based on convective, conductive, and inductive heating technologies
  • Soldering processes (for example, tin-silver)
  • Transient liquid phase soldering using two-component systems (for example, copper-tin)
  • Silver and copper particle sintering
  • Reactive material systems (integrated layers and particle pastes)
• Innovative contacting technologies
• Wafer-level bonding for the production of base substrates/semifinished products (such as silicon carbide wafers at reduced cost) for the production of power semiconductor devices
• Modeling and finite element analysis (FEA) for process optimization and the design of module and system components (electromagnetic, thermal, or fluidic), especially for inductive energy input

2. Quality and reliability analyses:

• Based on experimental studies:
  • Failure analysis using destructive and non-destructive test methods, high-resolution analysis techniques, micromechanical, electrical, and thermal characterization methods
  • Lifetime tests with associated error analysis
  • Derivation of load-based service life models
• Based on virtual methods using finite element analyses (electrical-thermal-mechanical coupled fields)
  • For the design of reliable structures (design for reliability)
  • Derivation of stress-based lifetime models (material-specific)
  • Delivery of compact models for condition monitoring

 

Mastering challenges: Collaboration in research and industry

Within the scope of its research activities, Fraunhofer ENAS is working with its cooperation partners to identify current and future requirements for assembly and interconnection technology for high-performance power modules and to implement them in even more efficient solutions.

If you would like to work with us to develop strategies to meet your challenges, have specific requirements in the area of packaging, or have questions about individual processes, please do not hesitate to contact us. We look forward to working with you to shape a more sustainable and greener future and accelerate the pace of energy transition.