Laser Activated and Electroless Metalized Polyurethane Coatings Containing Copper(II) L-Tyrosine and Glass Microspheres

Polyurethane coatings containing copper(II) L-tyrosine and glass microspheres were laser irradiated and underwent electroless metallization. Various sizes of glass microspheres were incorporated into the polyurethane coating matrix in order to examine their effects on surface activation and electroless metallization. The surface of the coatings was activated by using ArF excimer laser emitting ultraviolet radiation (λ = 193 nm) using different number of laser pulses and their fluence. The effects of surface activation and metallization were evaluated mainly based on optical and scanning electron microcopies (SEM), energy-dispersive X-ray spectroscopy (EDX) and photoelectron spectroscopy (XPS). It was found that the presence of glass microspheres enabled the reduction in copper complex content, intensified the ablation process (higher cone-like structures created) and resulted in higher content of copper metallic seeds. On the other hand, the glass microspheres concentration, which was higher for lower size microspheres, was advantageous for obtaining a fully metallized layer.

On the Possibility of Using Epoxy Prepregs for Carcass-Inflatable Nanosatellite Antennas

The possibility of using epoxy prepregs (fabric impregnated with epoxy resin) for carcass-inflatable antennas on space nanosatellites was investigated. It is shown that the optimal method of obtaining such devices is the use of reactive mixtures of hot cure, when the chemical reaction of curing of antenna deployed in space occurs under the action of solar radiation. In this case, the antenna is put into orbit in the nanosatellite in a compact form and no additional mechanisms are needed to give it the final working shape. The rheological properties of the mixture of epoxy resin YD-128 with hardener TEAT-1, suitable for making hot-curing prepregs and its use in near-earth orbit, are investigated. The dependence of rheological properties on temperature, hardener concentration and curing time is established. With the help of computer simulation, the temperature is calculated, to which the antenna carcass can be heated in near-earth orbit under the influence of thermal radiation from the Sun and the Earth taking into account its orientation in relation to the sources of heat. It is established that the process of hot curing of the antenna is possible due to solar and terrestrial radiation only when the frame is covered with a thin metallized layer that is close in characteristics to the layer of aluminum foil.

Diamond Photodiodes for X-ray Applications

Single crystal high purity CVD diamonds have been metallized and calibrated as photodiodes at the National Synchrotron Light Source (NSLS). Current mode responsivity measurements have been made over a wide range (0.2-28 keV) of photon energies across several beamlines. Linear response has been achieved over ten orders of magnitude of incident flux, along with uniform spatial response. A simple model of responsivity has been used to describe the results, yielding a value of 13.3±0.5 eV for the mean pair creation energy. The responsivity vs. photon energy data show a dip for photon energies near the carbon edge (284 eV), indicating incomplete charge collection for carriers created less than one micron from the metallized layer.

Microstructural characterization of Cu-Sn-Ni Solder in microelectronic packaging

Microelectronic packaging has experienced exciting growth in the past years, and solder joints plays important roles in the reliability of package system. Lead-tin (Pb-Sn) alloys are the most prominent solders for the interconnection and packaging of modern electionic components and devices. However, there are environmental concern on the toxicity of Pb. These concerns have inspired a great deal of research to study the feasibility of lead-free replacement alloys. It is known that the presence of intermetallic is often an indication of good wetting in solder joints. Nevertheless, excessive intermetallic growth may be detrimental to joint reliablity. The purpose of this study is to investigate the growth evolution between unleaded Cu-Sn-Ni alloys and metallized layer. These results will help to characterize the effect of aging on the microstructural and mechanical properties of solder / metallized layer / substrate systems.