Functionalized Auto-Structured insulating composite materials Tailored by ElectRic field for stress grading in 3D integrated electronic modules – FASTER-3D

Composites with electrical conductivity gradient or thermal conductivity anisotropy are made up with an epoxy matrix loaded with nonlinear (silicon carbide, SiC) or high thermal conductivity (boron nitride, BN) particles, respectively. Applying a DC electric field (electrophoresis) on the initially liquid resin for its shaping and loaded with SiC particles causes their accumulation towards the electrode of higher potential, thus forming a highly charged layer, which gives to this region a very high nonlinear conduction which is strongly electric field dependent. On the contrary, applying an AC electric field (dielectrophoresis) favors the formation of chains of BN particles in the direction of the applied field, thus increasing the thermal conduction in this direction, fostering the extraction of heat. Thus, the application of these physical principles coming from electrokinetics makes it possible to locally, and only where it is necessary within a conversion system that has to be insulated, to functionalize the properties of the insulation polymers in a highly relevant way in order to make them more efficient.

The obtained epoxy-SiC composite materials with electrical conductivity gradient exhibit a well-controlled accumulation of SiC particles around the high-voltage electrode depending on the parameters of the electrophoresis process (variation of voltage or deposition time). A behavioral electrical model was proposed based on homogeneous composites and further verified with the composites with conduction gradient that quantitatively describe the field-dependent conduction characteristics for different concentrations of SiC particles. Furthermore, anisotropic epoxy-BN composites made by dielectrophoresis showed a significant improvement in the thermal conductivity with an increase of up to 65% compared to an unmodified homogeneous composite.

Among the prospects for this work, we can list the adaptation and optimization of these two innovative processes and developed composite materials to apply to test structures representative of power conversion systems (like power module) in order to verify the performances of the electrical insulation or the thermal management. Subsequently, the implementation of these solutions into systems that integrate power devices will be performed with the evaluation of their impact on the reliability at system level.

- A. Can-Ortiz, L. Laudebat, Z. Valdez-Nava, S. Diaham, Nonlinear Electrical Conduction in Polymer Composites for Field Grading in High-Voltage Applications: A Review, Polymers, Vol. 13, No. 9, 1370, 2021.
- A. Can-Ortiz, Z. Valdez Nava, L. Laudebat and S. Diaham, Epoxy-Based ZnO and SiC Composites with Non-Linear Electrical Properties for Field Grading Applications, IEEE Conference on Electrical Insulation and Dielectric Phenomena (CEIDP), 12-15 December, Vancouver, Canada, pp. 411-413, 2021.
- T. T. Le, Z. Valdez-Nava and S. Diaham, Dielectrophoretic Chain Assembly of BaTiO3 Particles in Silicone Gel Composites and Effects on Dielectric Properties, 4th IEEE International Conference on Dielectrics (ICD), 3-7 July, Palermo, Italy, pp. 289-292, 2022.
- S. Diaham, Electric Field Grading in High-Voltage Integrated Electronic Systems: State-of-the-Art and Future Prospects, Invited Lecture at the International Workshop on Integrated Power Packaging (IWIPP), Grenoble, France, 24-26 August 2022.
- S. Diaham, Z. Valdez-Nava, L. Laudebat, M.-L. Locatelli, Advanced Functionalization of (Nano)Composite Insulating Polymers for Power Conversion Systems, Présentation invitée à la Journée Ciblée sur une Thématique Primes (JCT1): Matériaux Innovants pour la Conversion d’Energie Electrique, Tarbes, France, 24 Novembre 2020.

The FASTER-3D project proposes a breakthrough approach to address the reliability issues of standard packaging materials (encapsulation, substrate, interconnect, thermal interface material) in 3D electronic modules by replacing all of them by tailored functionalized polymer-based composites with advanced dielectric, thermal conductive, electrical conductive and thermo-mechanical properties. It is expected that the proposed multifunctional materials will allow a large reduction of the physical constraints (electrical, thermal, mechanical) into 3D integrated modules involving new wide bandgap power devices thanks to tailored stress relaxation. An efficient reduction of all the constraints with the proposed materials should have a major impact on the overall performances and reliability of the next generation of 3D power modules. Consequently, this project strongly supports the development of more efficient power electronic systems to help electrical energy saving during its conversion and distribution.