Publications

This paper discusses a new approach to making hybrid power electronic circuits by combining a low-temperature (850 C to 950 C) co-fired ceramic (LTCC) substrate, planar LTCC ferrite transformers/inductors and integrated passive components into a multilayer monolithic package using a ferrite-based LTCC material system. A ferrite tape functions as the base material for this LTCC system. The material system includes physically and chemically compatible dielectric paste, dielectric tape and conductor materials which can be co-fired with the base ferrite LTCC tape to create sintered devices with excellent magnetic coupling, high permeability ({approx}400), high resistivity (> 10{sup 12} {Omega} {center_dot} cm) and good saturation ({approx}0.3 T). The co-fired ferrite and dielectric materials can be used as a substrate for attaching or housing semiconductor components and other discrete devices that are part of the power electronics system. Furthermore, the ability to co-fire the ferrite with dielectric and conductor materials allows for the incorporation of embedded passives in the multilayer structure to create hybrid power electronic circuits. Overall this thick film material set offers a unique approach to making hybrid power electronics and could potentially allow a size reduction for many commercial dc-dc converter and other power electronic circuits.

Abstract not provided.

This paper is a continuation of the work presented in SAND2007-2591 'Planar LTCC Transformers for High Voltage Flyback Converters'. The designs in that SAND report were all based on a ferrite tape/dielectric paste system originally developed by NASCENTechnoloy, Inc, who collaborated in the design and manufacturing of the planar LTCC flyback converters. The output/volume requirements were targeted to DoD application for hard target/mini fuzing at around 1500 V for reasonable primary peak currents. High voltages could be obtained but with considerable higher current. Work had begun on higher voltage systems and is where this report begins. Limits in material properties and processing capabilities show that the state-of-the-art has limited our practical output voltage from such a small part volume. In other words, the technology is currently limited within the allowable funding and interest.

Abstract not provided.

Abstract not provided.

This paper discusses the design and use of low-temperature (850 C to 950 C) co-fired ceramic (LTCC) planar magnetic flyback transformers for applications that require conversion of a low voltage to high voltage (> 100V) with significant volumetric constraints. Measured performance and modeling results for multiple designs showed that the LTCC flyback transformer design and construction imposes serious limitations on the achievable coupling and significantly impacts the transformer performance and output voltage. This paper discusses the impact of various design factors that can provide improved performance by increasing transformer coupling and output voltage. The experiments performed on prototype units demonstrated LTCC transformer designs capable of greater than 2 kV output. Finally, the work investigated the effect of the LTCC microstructure on transformer insulation. Although this paper focuses on generating voltages in the kV range, the experimental characterization and discussion presented in this work applies to designs requiring lower voltage.