High voltage applications of low temperature co-fired ceramics

Abstract

PurposeThe purpose of this study was to design, fabricate and test devices based on transformers integrated with low-temperature co-fired ceramic (LTCC) modules with isolation between primary and secondary windings at the level between 6 and 12 kV.Design/methodology/approachInsulating properties of the LTCC were examined. Dielectric strength and volume resistivity were determined for common LTCC tapes: 951 (DuPont), 41020, 41060 (ESL), A6M (Ferro) and SK47 (KEKO). According to the determined properties, three different devices were designed, fabricated and tested: a compact DC/DC converter, a galvanic separator for serial digital bus and a transformer for high-voltage generator.FindingsBreakdown field intensity higher than 40 kV/mm was obtained for the test samples set, whereas the best breakdown field intensity of about 90 kV/mm was obtained for 951 tape. The materials 41020 and 951 exhibited the highest volume resistivity. Fabricated devices exhibited safe operation up to a potential difference of 10 kV, limited by minimum clearance. Long-term stability was assured by over 20 kV strength of inner dielectric.Practical implicationsThis paper contains description of three devices made in the LTCC technology for application in systems with high-voltage isolation requirement, for example, for power or railway power networks.Originality/valueThe results show that LTCC is a suitable material for fabrication of high-voltage devices with integrated passives. Technology and properties of three examples of such devices are described, demonstrating the ability of the LTCC technology for application in reliable high-voltage devices and systems.