Thick film resistors on dielectrics

This thesis investigates the viability of using thick film materials on a range of thick film dielectrics. They are usually
formulated so as to be compatible with 96% alumina substrates. It is sometimes desirable, however, to deposit them on thick film dielectrics. This may produce both technical and commercial advantages. The electrical changes produced and the chemical interactions observed are discussed. It is concluded that viable systems are possible provided the materials are carefully selected. In particular, there is evidence that the presence of barium in a resistor material affects the conduction mechanisms. This means that, in cases where the dielectric contains barium, the effects on the properties of the resistors may be very marked.
It is observed, however, that ceramic filled dielectrics with a high content of glasses should form a satisfactory class of
dielectric for use as an underlayer for thick film resistors. This conclusion appears to be in agreement with recently published commercial developments.
The thesis also discusses materials selection and the preparation of samples and gives detailed results of electrical tests. The figures includes plots of the results of SEM/EDX analyses made on polished cross-sections of samples.

A thesis submitted in partial fulfilments of the requirements for the Degree of Master of Philosophy of the Council for National Academic Awards.