Sintered TiO2 powder containing metallic Co binder prepared via mechanical carbonization,and its mechanical properties

A TiO₂-Co-a composite powder was prepared via carbonizing and selective oxidation processing of a Ti-Co alloy. The conventionally mixed TiO₂-Co-c composite powder and pure TiO₂ were sintered at 1100, 1200, 1300, 1400?°C, respectively. The structural characterization was performed using X-ray diffraction, field emission scattering electron microscopy (FE-SEM), and transmission electron microscopy (TEM). The sintered samples were more densified, and melted bonding occurred at temperature higher than 1300?°C. The flexural strength and fracture toughness of the TiO₂-Co-a sample were higher than those of the TiO₂ and TiO₂-Co-c sintered at temperature higher than 1300?°C, while the Vickers hardness of TiO₂-Co-a was the lowest at all sintering temperatures. The sintered TiO₂-Co-a sample was more ductile and strengthened than the TiO₂-Co-c sample with added metallic Co binder via mechanical mixing. The enhanced mechanical properties of the TiO₂-Co-a sample were due to the fine dispersion of the metallic Co binder wetted with a TiO₂ matrix.     

Ultrasonic Bonding Using Anisotropic Conductive Films (ACFs) for Flip Chip Interconnection

In this paper, a novel anisotropic conductive film (ACF) flip chip bonding method using ultrasonic vibration for flip chip interconnection is demonstrated. The curing and bonding behaviors of ACFs by ultrasonic vibration were investigated using a 40-kHz ultrasonic bonder with longitudinal vibration. In situ temperature of the ACF layer during ultrasonic (U/S) bonding was measured to investigate the effects of substrate materials and substrate temperature. Curing of the ACFs by ultrasonic vibration was investigated by dynamic scanning calorimetry (DSC) analysis in comparison with isothermal curing. Die adhesion strength of U/S-bonded specimens was compared with that of thermo-compression (T/C) bonded specimens. The temperature of the ACF layer during U/S bonding was significantly affected by the type of substrate materials rather than by the substrate heating temperature. With room the temperature U/S bonding process, the temperature of the ACF layer increased up to 300degC within 2 s on FR-4 substrates and 250degC within 4 s on glass substrates. ACFs were fully cured within 3 s by ultrasonic vibration, because the ACF temperature exceeded 300degC within 3 s. Die adhesion strengths of U/S-bonded specimens were as high as those of T/C bonded specimens both on FR-4 and glass substrates. In summary, U/S bonding of ACF significantly reduces the ACF bonding times to several seconds, and also makes bonding possible at room temperature compared with T/C bonding which requires tens of seconds for bonding time and a bonding temperature of more than 180degC.     

Theoretical and experimental analysis of material deformation by microcontact

This paper reports on an investigation of contact damage induced in molds and substrate materials used in micro- and nanoimprint lithography. Silicon, polydimethylsiloxane (PDMS), glass, and silicon carbide were studied. A finite element analysis using ABAQUS software was conducted to investigate the stress induced in mold and substrate materials when they come in contact with each other at a uniaxial pressure of 1 MPa. A spherical indentation experiment was conducted for a model study for various indentation loads and numbers of contact cycles. We examined the contact damage during the spherical indentation. Indentation stress-strain curves, surface views of contact damage, and mechanical properties were characterized for the mold and substrate materials.     

Heat transfer analysis during a curing process for UV nanoimprint lithography

A heat transfer analysis during the curing process in UV-Nanoimprint lithography was carried out. To imprint nano/micro patterns into a large-area target glass such as LCD panels, a mold with a poly-urethane-acrylate layer is often used, on which layer the micro/nano patterns are inscribed for the UV-NIL process. After UV resin is coated between the target glass and the flexible mold, the UV resin is cured by exposing UV light on the resin. In the curing process, heat from the phase change of the resin and the radiation by UV lamp would induce a temperature change and thermal distortion of the mold. In this study, we measured the temperature change of the flexible mold, and established an analytic model of the heat transfer. From the result, we derived the thermal properties of the PUA layer, and a thermal resistance layer between the PUA and the cured resin layer. This paper was presented at the 4th Asian Conference on Multibody Dynamics(ACMD2008), Jeju, Korea, August 20–23, 2008. Jay Jeong received Ph.D. degree from Seoul National University in 2002. He held a Post-doctorate at Johns Hopkins University, USA from 2003 to 2006. Dr. Jeong is currently an assistant professor at the School of Mechanical and Automotive Engineering in Kookmin University in Seoul, Korea. His research interests are in the area of nano-robotics and intelligent mechanism.     

Improvement of Enterobacteriaceae enrichment broth by supplementation with sodium citrate for detection of Cronobacter sakazakii using real-time PCR

Food Science and Biotechnology - Enterobacteriaceae enrichment (EE) broth, a selective enrichment medium for Cronobacter sakazakii detection, has been shown to contain polymerase chain reaction...     

Optimization of control allocation with ESC,AFS, ARS and TVD in integrated chassis control

This paper presents an optimization of control allocation in integrated chassis control with active front steering, active rear steering, electronic stability control and torque-vectoring device under the saturation of lateral tire forces on front wheels. After a control yaw moment is calculated in the upper-level controller, a weighted pseudo-inverse based control allocation is used for yaw moment generation in the lower-level controller. Variable coefficients of the weighted pseudo-inverse based control allocation are used to represent various actuator combinations and are optimized for each actuator combination to enhance control performances using simulation on vehicle simulation package, CarSim. Due to severe cornering on low friction road, the front lateral tire forces can be easily saturated. Under the condition, the active front steering has little effect on control performance and, consequently, the desired control yaw moment cannot be generated. So, the lateral force generated by AFS should be restricted to its maximum, and a constrained weighted pseudoinverse based control allocation with electronic stability control, active rear steering and torque-vectoring device is applied to compensate the loss of the control yaw moment. Variable coefficients of the constrained weighted pseudo-inverse based control allocation with electronic stability control, active rear steering and torque-vectoring device are also optimized using simulated-based tuning. To validate the proposed method, simulation was done on CarSim. From simulation, it was verified which actuator combination is effective for integrated chassis control if the lateral forces on front wheels are saturated.