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Development of Embedded Power Electronics Modules for Automotive Applications

: Böttcher, Lars; Karaszkiewicz, S.; Manessis, D.; Ostmann, A.

Surface Mount Technology Association -SMTA-:
SMTA International Conference 2012. Vol.1 : Orlando, Florida, USA, 14 - 18 October 2012
Red Hook, NY: Curran, 2013
ISBN: 978-1-62276-896-7
Surface Mount Technology Association (SMTA International Conference) <2012, Orlando/Fla.>
Fraunhofer IZM ()

Packaging of power devices is a strong challenge in terms of thermal and reliability challenges. The use of Printed Circuit Board (PCB) technology for device packaging offers new opportunities to solve these challenges. During the past decade embedding of semiconductor chips into PCB structures evolved from a research topic to volume production. The paper will briefly describe this development and categorize today's embedding technologies. First modules with embedded chips are in production in Asia and Europe, mainly for mobile applications. In Europe embedding has gained a strong interest for power modules, especially in automotive applications. Main drivers are the capability for compact and thin packaging, the high reliability and cost saving potential. The automotive industry has a strong demand for highly reliable and cost-efficient electronics. Especially the upcoming generations of hybrid cars and fully electrical vehicles need compact and efficient 400 V power modules. Within the engine compartment installation space is of major concern. Therefore small size and high integration level of the modules are needed. Today IGBTs and diodes are soldered to DCB (Direct Copper Bond) ceramics substrates and their top contacts are connected by heavy aluminum wire bonds. These ceramic modules are vacuum soldered to water-cooled base plates. Embedding of power switches, and controller into compact modules using PCB (Printed Circuit Board) technologies offers the potential to further improve the thermal management by double-sided cooling and to reduce the thickness of the module. In order to replace DCB ceramics, a structure of thermal laminate material between Cu layers has been developed and the capability for thermal conduction and electrical insulation has been evaluated. For the assembly of large power IGBTs with sizes of 100 mm² and larger, new silver sintering pastes have been evaluated. They enable a pressure-less sintering at 200 °C, compatible with PCB materials. To handle the high switching current of up to 200 A, suitable copper tracks in the PCB are required. The realization of such thick copper lines with thickness up to 1 mm requires advanced processing, compared to conventional multilayer PCB production. In order to form complex power systems out of modules with embedded chips interconnections by Ag sintering are under development.