The development of glaze capacitors for thick film circuits

For low-value capacitors (tens of picofarads) glass dielectrics have been chosen, whereas for higher values it has been necessary to use a mixture of a high-permittivity ceramic and a binder material. Existing thick-film conductor compositions have been used for electrodes. In the work on the low-value systems, a large number of combinations of different dielectric and electrode materials and their processing conditions have been assessed, and several usable systems have been determined. The reasons for the poor performance of other systems have been studied and are described. The need to use multi-phase dielectrics for higher values, and the behaviour to be expected from such systems are discussed. Dielectrics have been made from mixtures of high-permittivity ceramics based on barium titanate and various glasses or bismuth oxide, and the various materials and processing parameters have been varied to attain the optimum performance. Data on the performance of high- and low-value capacitor systems are included.