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Basic Adhesion Mechanisms in Thick and Thin Films.

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Quarterly technical rept. no. 1, 1 Jan-31 Mar 76,

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The first quarterly report of 1976 reviews the present understanding of gold-platinum thick-film inks, their solderability, and the degradation of adhesion strength of the soldered film caused by thermal aging. In addition, metal powders for the model ink program and some commercially available gold-platinum inks have been chemically analyzed. Specifically, high surface area, e.g., 10 to 15 sq mgm, platinum and palladium powders were obtained, analyzed by flame emission spectroscopy and characterized in terms of particle size distribution and morphology. Additional MB-1 gold powder was analyzed as well. Isothermal densification curves were determined for the gold, platinum and palladium powders as well as isothermal weight-gain oxidation curves for the palladium powder. The weight gain indicated the need to sinter palladium-bearing compositions above 800 C to preclude oxidation and facilitate rapid densification. All powders were discussed in terms of classical sintering behavior, i.e., neck growth, pore closure, and grain growth. Twenty-two commercial inks were analyzed by x-ray fluorescence spectrometry XRFS to identify the gold-platinum-palladium ratios and binding agent elements. Gold-platinum intensity ratios were found to vary about an order of magnitude, and gold-palladium ratios were considerably less than that. Initial soldered adhesion strengths varied by more than a factor of two. After thermal aging at 150 C for 250 hours, about the same ratio existed but some inks had decreased in strength by more than 50 percent. Chemical analyses of platinum and palladium foil were also completed in preparation for glass frit wetting studies on these materials. Author

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  • Electrical and Electronic Equipment

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