Thermodynamic Modeling of Equilibrium Subsolidus Phase Relations in the Ag-Pd-O₂ System

From literature values of the thermodynamic activity of Pd in Ag/Pd solid solutions and the Gibbs free energy of formation of PdO as a function of temperature, subsolidus equilibrium phase relations in the Pd-Ag-O2 system have been calculated and compared to results from high-temperature XRD analyses. the developed model takes into account the nonideal activity of Pd in Ag/Pd solid solutions and confirms that increasing the Ag/Pd ratio or decreasing the oxygen activity decreases the temperature at which PdO reduces. It also accurately predicts that the temperature range over which the PdO reduces is broad for Ag-rich compositions, and narrow for Pd-rich compositions

Silver-palladium Thick-film Conductors

The trends in integrated circuit packaging technology are toward high speed, high density, reliability, and low cost. These demand the improvement of material formulations and processing technology. Among the thick-film materials systems, conductor materials generally represent an important and the most expensive element. Therefore, attention has been centered on the performance of the fired metal film and its cost. Silver and palladium (Ag/Pd) conductors are important components of thick-film paste technology. Thick-film Ag/Pd conductors find applications in many aspects of electronics and electronic packaging, such as hybrid microcircuits, multichip modules, packaging for integrated microcircuits, and in passive electronic components such as multilayer capacitors, varistors, and inductors. in this paper, the performance and properties of fired Ag/Pd films are discussed through their physical and chemical aspects. the final film properties are correlated to a number of factors, including thermodynamics and kinetics of Pd oxidation during burnout and firing; chemical and physical reaction of the Ag/Pd with the ceramic substrate, organic vehicle, and solder; Ag diffusion and migration; inorganic and organic additives; powders characteristics; and paste properties