Wide Temperature, High Energy Density Capacitors for Power System Conditioning

Active Signal Technologies, in collaboration with Novacap and Alfred University, will advance the development of two bismuth sodium titanate (NBT) ceramic materials with very promising dielectric properties across the temperature range -55°C to 300°C. The work will include enhanced formulation variants and improved processing techniques to optimize for permittivity, loss, breakdown voltage and resistivity. NBT-based materials were selected because Type H (the most mature example of the class) has low combined temperature and voltage coefficient resulting in a net capacitance change < 20% across the band from -40°C to +200°C at full voltage stress. At the end of Phase I the team will deliver 3 fully-packaged 1-ìF, 600-V multilayer capacitors of each type produced on standard manufacturing equipment in a production plant. The selected materials represent two different methods of achieving the same goal of very compact, reliable, temperature stable capacitors but with property mixes suitable for quite distinct power conditioning applications. Because ceramic capacitors raise concerns about adverse failure modes, the proposal addresses key issues of reliability with advanced sorting and quality control methods, and capacitor design for graceful degradation. In Phase II nano processing is introduced to reduce intrinsic flaw size and raise breakdown strength.