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Enhanced Schapery Theory Software Development for Modeling Failure of Fiber-Reinforced Laminates

This tool captures the physics of the damage and failure mechanisms. Progressive damage and failure analysis (PDFA) tools are needed to predict the nonlinear response of advanced fiber-reinforced composite structures. Predictive tools should incorporate the underlying physics of the damage and failure mechanisms observed in the composite, and should utilize as few input parameters as possible.

Posted in: Materials, Briefs, TSP

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High-Performance, Low-Temperature-Operating, Long-Lifetime Aerospace Lubricants

The synthesis and characterization of six new ionic liquids, with fluoroether moeties on the imidazolium ring, each with vapor pressures shown to be

Posted in: Materials, Briefs, TSP

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Carbon Nanotube Microarrays Grown on Nanoflake Substrates

This process creates materials comprised predominantly of single-walled carbon nanotubes. This innovation consists of a new composition of matter where single-walled carbon nanotubes (SWNTs) are grown in aligned arrays from nanostructured flakes that are coated in Fe catalyst. This method of growth of aligned SWNTs, which can yield well over 400 percent SWNT mass per unit substrate mass, exceeds current yields for entangled SWNT growth. In addition, processing can be performed with minimal wet etching treatments, leaving aligned SWNTs with superior properties over those that exist in entangled mats.

Posted in: Materials, Briefs

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A Room Temperature, Low-Stress Bonding Process to Reduce the Impact of Use Stress on a Sputtering Target Assembly

As semiconductor processing has moved to 300mm wafers, the size of deposition targets, including tungsten (W), tantalum (Ta), and molybdenum (Mo), has grown, and process complexity has increased as well. This added size and complexity contributes to the stress on a target assembly during the physical vapor deposition (PVD) process, and the target assembly’s ability to withstand this stress has a large effect on the resulting deposition rates, yields, and film properties. One of the major sources of stress is the coefficient of thermal expansion (CTE) mismatch between metal targets in semiconductor processes, such as tungsten (CTE of 4.5*10-6/°C), tantalum (6.5*10-6/°C), and molybdenum (5.1*10-6/°C) compared with their backing plates, which are typically made of aluminum (23*10-6/°C), brass (21.2*10-6/°C), or copper-chrome (17.6*10- 6/°C). Standard soldering and solid state joining processes have difficulty controlling stress produced by the CTE-mismatch. We will demonstrate how the NanoBond® process can be used to control stresses during the bonding and deposition processes. Modeling will be conducted to compare standard bonding processes to the NanoBond process, accounting for CTE mismatches.

Posted in: Materials, White Papers

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Achieving High Reliability SAC Solder Joints via Min Doping

In this study, the reliability of low Ag SAC alloy doped with Mn (SACM) was evaluated under JEDEC drop, dynamic bending, thermal cycling, and cyclic bending test conditions and compared to eutectic SnPb, SAC105, and SAC305 alloys. SACM is a patent pending alloy consisting of 0.5-1% Ag, 0.5-1% Cu, <0.1% Mn. SACM alloy achieved a higher drop test and dynamic bending test reliability than SAC105 and SAC305, and exceeded SnPb for many test conditions. More significantly, SACM matched SAC305 in thermal cycling performance. In other words, the low cost SACM achieved a better drop test performance than the low Ag SAC alloys, plus the desired thermal cycling reliability of high Ag SAC alloys. The mechanism for high drop shock performance and high thermal cycling reliability can be attributed to a stabilized microstructure, with uniform distribution of fine IMC particles, presumably through the inclusion of Mn in the IMC. The cyclic bending results showed SAC305 to be the best and all lead-free alloys were equal or superior to SnPb. The reliability test results also showed that NiAu is a preferred surface finish for BGA packages over OSP.

Posted in: Materials, White Papers

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Phase Change Material for Temperature Control of Imager or Sounder on GOES Type Satellites in GEO

An imager or sounder on satellites, such as the Geostationary Operational Environmental Satellite (GOES), in geostationary orbit (GEO) has a scan mirror and motor in the scan cavity. The GEO orbit is 24 hours long. During part of the orbit, direct sunlight enters the scan aperture and adds heat to components in the scan cavity. Solar heating also increases the scan motor temperature. Overheating of the scan motor could reduce its reliability. For GOES-N to P, a radiator with a thermal louver rejects the solar heat absorbed to keep the scan cavity cool. A sunshield shields the radiator/louver from the Sun. This innovation uses phase change material (PCM) in the scan cavity to maintain the temperature stability of the scan mirror and motor.

Posted in: Materials, Briefs, TSP

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Preparation of a Bimetal Using Mechanical Alloying for Environmental or Industrial Use

This technology could be of use for catalyst production or environmental applications. Following the 1976 Toxic Substances Control Act ban on their manufacture, PCBs remain an environmental threat. PCBs are known to bio-accumulate and concentrate in fatty tissues. Further complications arise from the potential for contamination of commercial mixtures with other more toxic chlorinated compounds such as polychlorinated dibenzodioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs). Until recently, only one option was available for the treatment of PCB-contaminated materials: incineration. This may prove to be more detrimental to the environment than the PCBs themselves due to the potential for formation of PCDDs.

Posted in: Materials, Briefs

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