Compositional effects on microstructure evolution and microwave properties of silver–palladium based thick film microstrips

Recent improvements in materials and processing technologies have dramatically increased the frequency range where ceramic thick film circuits can be utilized. Coupled with inherent advantages of thick film technology viz. low manufacturing cost, multilayering capability and relative insensitivity to substrate surface characteristics, such improvements have resulted in circuits that are penetrating the domain which was previously reserved to thin film technology. In view of newer developments in modern electronics, there is still ample scope for the development of new materials and processes especially in thick film technology. In thick films, conductors play a major role and silver–palladium is one of the important conductor materials in microelectronic circuits. Efforts are made in this work towards the development of suitable silver–palladium thick film conductors from the standpoint of microwave applications. The properties such as surface microstructure, sheet resistance, adhesion and microwave performance of the indigenously developed silver–palladium paste compositions is reported here. Highly porous surface structure, low adhesion and low characteristic impedance of thick film microstrip are observed for pastes with high palladium concentration.