Microwave characterization of low temperature cofired ceramic

The use of low temperature cofired ceramic (LTCC) materials for the manufacture of high performance microelectronic packages operating at very high frequencies has found widespread acceptance due to LTCC's durability, compactness and manufacturability. Extensive effort has been devoted to the characterization of the electrical performance of the dielectric and associated conductor materials to determine and predict performance when constructing electronic packages that operate over a broad band of frequencies from DC through high speed digital to the microwave and millimeter bands. This effort has focused on several different areas, including the effect of operating frequency on the bulk dielectric properties of the ceramic and the electrical properties of associated thick film materials, particularly conductors. The interaction of these materials during processing, has been investigated, to determine the interdependence of these characteristics, so that both design rules and processing guidelines for particular package configurations (such as microstrip and stripline) and applications may be optimized. The Ferro A6-M ceramic, has demonstrated low dielectric constant and low dielectric loss at a wide range of frequencies, is compatible with low cost, high performance conductor materials, such as silver, and may also be used in mixed metal configurations with combinations of gold and silver conductors, in applications where such an approach is necessary. This paper reviews some of the results which have been determined in electrical characterizations such as these and proposes new electrical evaluations that may prove useful in the future.