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908) 685-706 1 substrate itself. Integal substrate technology optimizes space utilization whle maintaming near outimal uerformance, and Abstract Trends in the electronics industry, requiring products to be smaller, lighter, and cheaper, are driving the development of integral passive technology. New design system, test system, and manufacturing processes provide new challenges and the opportunity to employ new passive materials. In general, metalkeramic based materials provide better resistance stability, however, high processing temperatures, (up to SOOT), make them unusable with organic substrates. In contrast, polymeric materials (e.g. polymer thick films or F'TFs), provide a wide range of resistivity with reasonable curing temperatures. However, unstable electrical resistance, especially under high temperature and humidity conditions over a long period of time, is a major hurdle.A structure-property-performance study was conducted on a series of commercially available polymer thick film (PTF) materials. The objective was to identify the fundamental failwe mechanisms contributing to unstable electrical resistivity. For the materials studied, interfacial failure was the dominant mechanism and the resistance drift was found to be irreversible. These results suggested that corrosion of the metal substrate at the metal-PTF interface caused the increase in resistance. Based on this fmdjng, a series of new PTF materials have been developed with improved resistance stability. Resistance drift, ((R-Ro)Ro), has been reduced from 800% for the commercial materials to 15% for the novel F' TF materials.

Processing graphene and graphene polymer nanocomposites in an aqueous medium has always been a big challenge due to the hydrophobic nature of graphene (or reduced graphene oxide) nanosheets. In this work, a waterborne latex of polyurethane has been used both as the matrix material for embedding the graphene nanosheets and as a unique stabilizer to help produce an up to 5 wt% graphene/PU nanocomposites. The graphene oxide/polyurethane latex aqueous suspension is reduced in-situ using hydrazine, without any trace of aggregation/agglomeration upon completion of the reduction process, which would otherwise have occurred severely were PU not present. A highly aligned nanostructure is produced when graphene content is increased beyond 2 wt%, resulting in a remarkable improvement in electrical and mechanical properties of the nanocomposite. The exceptionally low electrical percolation threshold of 0.078%, as well as 21-fold and 14 fold increases in tensile modulus and strength, respectively, have been attained thanks to the alignment of graphene nanosheets in the polymeric matrix.