Sintering of screen-printed platinum thick films for electrode applications

Pt electrodes with a 6-8-mum thickness were produced on alumina substrates by a double-print Pt screen-printing process that included a sequential heat treatment at 600 degreesC and 1300 degreesC. This process improved the final sintered double-print film because the first printed layer acted as a sintering template for the second printed layer. The sintered Pt films have a 95% coverage of the alumina surface, 92% density, 0.73-mum average surface roughness, and 16.10(-5) Omega cm resistivity. The sintering behavior of Pt films exhibited three stages of densification: Stage I (T degreesC < 700 <degrees>C), exhibiting neck growth, and Stage II (700 < T <degrees>C < 1300 <degrees>C), exhibiting grain growth, have activation energies of 64 kJ/mol and 125 kJ/mol, respectively. Stage III exhibits a decrease in shrinkage due to Pt coalescence and island formation. The transition temperature, 700 degreesC, between Stages I and II corresponds to an anomalous increase in surface roughness and resistivity. The thickness of Pt films was a critical parameter for achieving alumina surface coverage. Uniaxial pressing of dried Pt films increased densification and reduced the surface roughness of double-print Pt films.