Black phosphorus (BP) has attracted significant interest as a monolayer or few-layer material with extraordinary electrical and optoelectronic properties. However, degradation in air and other environments is an unresolved issue that may limit future applications. In particular the role of different ambient species has remained controversial. Here, we report systematic experiments combined with ab-initio calculations that address the effects of oxygen and water in the degradation of BP. Our results show that BP rapidly degrades whenever oxygen is present, but is unaffected by deaerated (i.e., O 2 depleted) water. This behavior is rationalized by oxidation involving a facile dissociative chemisorption of O 2 , whereas H 2 O molecules are weakly physisorbed and do not dissociate on the BP surface. Oxidation (by O 2 ) turns the hydrophobic pristine BP surface progressively hydrophilic. Our results have implications on the development of encapsulation strategies for BP, and open new avenues for exploration of phenomena in aqueous solutions including solution-gating, electrochemistry, and solutionphase approaches for exfoliation, dispersion, and delivery of BP.

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Chrysotile nanotubes (ChNTs) were synthesized under hydrothermal conditions. The shape and size of individual ChNTs were examined by transmission electron microscopy (TEM). Specific surface area (SSA) of nanotubes surface treated with a silane coupling agent and of pristine nanotubes in the bulk was determined by BET analysis of N 2 adsorption at 77 K. The theoretical SSA of a single nanotube and of nanotubes organized in a bundle was calculated as a function of nanotube geometrical parameters and the bundle size, that is, number of nanotubes in the bundle. A comparison of experimental and theoretically calculated SSA values indicated that nanotubes form bundles in the bulk. The characteristic bundle size in the bulk was estimated. The tendency of ChNTs to form bundles was also investigated in polar (ethanol) and nonpolar (xylene) solvents by measuring the complex viscosity behavior of the corresponding colloidal solutions. Viscosity measurements showed that nanotubes form bundles and that they are larger, consisting of more nanotubes, in nonpolar xylene than in polar ethanol. The tendency of ChNTs to aggregate in the bulk and in the solution was reduced by surface treatment of nanotubes with a silane coupling agent.

A commercial Hitachi anisotropic conducting film (ACF) was used to form the electrical interconnection between aluminum pads on a glass plate substrate, and electrolysis tin coated copper pads on a polyimide flexible circuit. These interconnections were aged over 1,400 hours at 85°C and 79% relative humidity. Throughout the thermal aging period a variety of electrical properties were measured. Electrical resistance of the ACF bonds was monitored in situ providing a continuous record of the resistance increase toward failure. The specimens were periodically brought back to ambient and dried out to monitor the resistance recovery and how other electrical properties were affected due to aging. A continuous resistance monitoring during the temperature ramp provided the temperature coefficient of resistance as a function of aging. The other electrical properties measured at ambient conditions were the voltage coefficient of resistance, both at low currents and at high currents, where self-heating occurred, the magnitude of l/f noise, and the thermopower. As will be explained, each of these electrical properties provides an independent measurement of critical interconnection parameters. IntroductionAnisotropic conducting adhesive (ACA) films are currently the primary method to interconnect flat panel displays to external flexible circuits. Initial products have emerged and research is continuing on the use of ACA films for direct chip attach to circuit boards. ACAs have the advantage in fine pitch applications of eliminating the difficult registration problem between the interconnecting pad and the solder balls. ACAs also act as an underfill eliminating a separate underfill process needed for some applications. Other advantages are that the processing for ACAs require lower bonding temperatures, and are lead free. Tests by independent researchers [ 13 and ACA manufacturers [2] have demonstrated the reliability of the joints formed using ACA. The literature, however, is still lacking a satisfactory quantitative understanding of the conduction mechanism through all the redundant interfaces, and a consistent and complete understanding of the failure mechanisms for commercial products.Many flat panel displays use aluminum metallurgy on the bonding pads. Because the displays that prompted this study had aluminum, and tungsten clad aluminum pads, the test vehicles used in this study had aluminum contact pads and traces. The hard oxide coating present on aluminum and tungsten surfaces represents special challenges for the formation of stable mechanical contacts that are electrically conducting. Articles have indicated that these contacts are