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Conjugated network polymer emitters are potential materials for use as solid detectors of chemicals. We demonstrated the synthesis of fluorescent network polymers through a facile route. Solid-state fluorescent network polymer emitters were synthesized through the Knoevenagel polycondensation of an arylaldehyde (tris(p-formylphenyl)amine) with an arylacetonitrile (phenylenediacetonitrile) in good yields. The molecular structure based on the electron-donor triphenylamine and electron-acceptor cyano-substituted phenylene-vinylene showed a highly efficient solid-state fluorescence. The synthesized model small molecule showed a well-defined solvatofluorochromism: the dielectric constants were esol of approximately 0–50 at λfl of 480–560 nm. The response to solvent chemicals was also shown for the network polymers. Surprisingly, the network polymer linked with para-phenylene-vinylene was only responsive to the solvents with a low dielectric constant (esol ca.

Power electronics is becoming more important than before with motor application expansion. For size reduction of inverter integrated motor design, accurate temperature prediction of power devices is becoming critical. For up to several hundred-watt motor system, inverter is designed with discrete power devices with standard package. This paper investigates package thermal resistance of a DPAK package as an example. Firstly, three-dimensional heat conduction simulation only with DPAK package model is conducted. It is found that its package thermal resistance changes by ∼6.2°C/W due to boundary condition variation. After that, simulation not only with DPAK package but also with PCB is conducted to understand package thermal resistance of a real system implementation case. It is found that package thermal resistance varies drastically by copper trace size. “Smallest” case with minimum copper traces shows ∼0.9 °C/W higher value than larger copper trace case and shows ∼1.5 °C/W higher value than the case that copper trace fully covers PCB top surface, in the case that horizontal PCB size is 50 × 50 mm. After that, two types of test boards with different trace size for of n-channel MOSFET with DPAK package are prepared. Measurements are conducted to know package thermal resistance variation by copper trace size. Transient thermal impedance curve is obtained from measurement result and is converted to a cumulative Rth-Cth curve to know and discuss the difference by copper trace size of these two test boards. The difference is also discussed with and compared to that of simulation results.

In recent years, not only static thermal design but also realtime thermal control become important for power efficiency on computing systems. Three-dimensional thermal simulation is widely used to design computing system, however, it takes too long time for intelligent power and thermal management validation because it requires transient thermal simulation with very short time step. To enable rapid simulation environment, compact thermal model which can be employed with both three-dimensional transient thermal simulation and transient thermal network is required. Therefore, this research aims to establish transient state compact thermal model for microprocessor package. This paper briefly introduces steady state compact thermal model for microprocessor, which is proposed as previous work, then, points out key point to extend the model to transient state model. Transient thermal spreading resistance is emulated and the effect is checked by comparing with three-dimensional simulation.

We have successfully synthesized π-conjugated microporous polymers (CMPs) via direct arylation of fluoroarenes with 2,4,6-tris(4-bromophenyl)-1,3,5-triazine. Both 1,2,4,5-tetrafluorobenzene and 1,3,5-trifluorobenzene were good monomers to give the networks, CMP1 and CMP2, respectively. Characterization of the insoluble materials was successfully achieved by high performance solid-state 13C and 19F CP/MAS NMR spectroscopy. The signals appeared in the aromatic region. No end group signals were observed in the 13C NMR spectrum of CMP1, but CMP2 showed the unreacted C–H signal of the trifluorobenzene unit. CMP2 showed higher Brunauer–Emmett–Teller (BET) surface area than CMP1. The number of branch controlled (or tailored) the porosity of the polymer networks. The polymers have microporocity with CO2 capture capacity. The CO2 capture capacity of CMP2 (16.75 cm3 g-1) was higher than that of CMP1 (11.49 cm3 g-1) at 1.0 bar.

The process of CO2 adsorption on silicalite-1 zeolite (MFI-type) is revealed using a single-crystal X-ray method. The structure of CO2-silicalite-1 with a small amount of CO2 in the pore is determined, wherein most of CO2 molecules are located in the straight channel. It indicates the straight channel is the most stable sorption site based on the van der Waals interactions between the CO2 and the framework, and the CO2 molecules initially adsorb in the straight channel in the adsorption process. This is the first report to describe the structure of MFI-type zeolites with the adsorbate molecules occupying only the straight channel.

Silicon carbide (SiC) is a promising semiconductor for high-power devices due to its superior material properties; high breakdown field, high electron saturation velocity, and high thermal conductivity. To implement SiC power devices, pn junction must be formed in the SiC. However, ion implantation for impurity doping has several issues for the SiC. For example, while a high-temperature (~1700 °C) post-implantation annealing is required to electrically activate implanted species [, it induces generation of crystallographic defects in the SiC, such as segregation of carbon atoms at the surface from the SiC bulk [. Therefore, development of new technology for local doping of SiC is highly demanded.

Structural analysis of CO2-silicalite-1 crystals using the single-crystal X-ray diffraction method reveals that the crystal system is twinned monoclinic. The structure of silicalite-1 (MFI-type zeolites) loaded with CO2 has previously been solved in orthorhombic system [1], but the R value is still large. Since CO2 molecules are too small to maintain the orthorhombic structure, it is considered that the CO2-silicalite-1 crystals should be in the relaxed monoclinic twin phase. The diffraction data in the previous report is recalculated in P21 /n as the monoclinic twinning.

The location of physisorbed CO2 molecules on silicalite-1 zeolite (MFI-type) is determined using a single-crystal X-ray method. There are four sorption sites for CO2 molecules in the three-dimensional channel system of the silicalite-1. Two of them are in the straight channel in disorder (STR1 and STR2), while the other sites are in the sinusoidal channel (SIN) and at the intersection (INT). Their occupancy factors indicate that a large portion of the CO2 molecules are located in the straight channel. It is also revealed that the straight channel is the most favorable for CO2 molecules as sorption sites.

This paper explores system level transient heat transfer behavior under natural convection cooling with slate style chassis assuming a tablet device design. Steady state analysis based on heat conduction simulation is conducted to see the effect on microprocessor silicon die temperature and skin temperature of the chassis by internal structure difference and determine final configuration for transient simulation. After that, transient state analysis is conducted assuming the case that a microprocessor starts running TDP (Thermal Design Power) equivalent application workload after system reaches steady state with static screen idle power consumed by the microprocessor.

A simple method for preparing monoclinic single crystals of ZSM-5 is developed. The ZSM-5 crystals are pressed with a weight of 50 g at an angle of 45° relative to the b and c crystallographic axes of twin ZSM-5 crystals while the temperature is simultaneously increased to 573 K. The temperature is then slowly reduced to 313 K, and these steps are repeated three times. The monoclinic structure of the single crystals of ZSM-5 produced using this method is then determined.

The thermal network method has a long history with thermal design of electronic equipment. In particular, a one-dimensional thermal network is useful to know the temperature and heat transfer rate along each heat transfer path. It also saves computation time and/or computation resources to obtain target temperature. However, unlike three-dimensional thermal simulation with fine pitch grids and a three-dimensional thermal network with sufficient numbers of nodes, a traditional one-dimensional thermal network cannot predict the temperature of a microprocessor silicon die hot spot with sufficient accuracy in a three-dimensional domain analysis. Therefore, this paper introduces a one-dimensional thermal network with average temperature nodes. Thermal resistance values need to be obtained to calculate target temperature in a thermal network. For this purpose, thermal resistance calculation methodology with simplified boundary conditions, which calculates thermal resistance values from an analytical solution, is also introduced in this paper. The effectiveness of the methodology is explored with a simple model of the microprocessor system. The calculated result by the methodology is compared to a three-dimensional heat conduction simulation result. It is found that the introduced technique matches the three-dimensional heat conduction simulation result well.Copyright © 2015 by ASME

This paper proposes a new compact thermal model (CTM) for the microprocessor package based on a one-dimensional thermal network with average temperature nodes. Different from the two-resistor model and the DELPHI model, the proposed CTM doesn't assume an isothermal surface, but sets plate heat sources along the top surface of the silicon die and the bottom surface of the solder balls layer. It is found that the temperature prediction result by a thermal network with the proposed CTM matches the three-dimensional heat conduction simulation result closely through a numerical experiment of a microprocessor system with a heat sink fan.

This paper investigates transient temperature prediction of microprocessor hot spot by utilizing one-dimensional thermal network with average temperature nodes. Different from traditional thermal network, introduced one-dimensional thermal network in this paper consists of not only material thermal resistances and material thermal capacitances but also thermal spreading resistances and a thermal local resistance. Basic concept and construction of the thermal network are firstly introduced, one-dimensional thermal network for the microprocessor system is secondly created and transient models for heat sink fan and thermal spreading resistances are thirdly introduced to obtain sufficient temperature transient result in this paper. After that, thermal analysis is conducted with constructed one-dimensional thermal network by applying microprocessor power consumption calculated by power estimation equation which considers voltage and temperature dependency time by time. Transient thermal resistance of heat sink fan and transient thermal spreading resistances are evaluated to discuss temperature transient result. It is found that heat sink thermal resistance need to be considered to obtain more precise temperature result though obtained result has practical accuracy.

This paper introduces and discusses one-dimensional thermal network for microprocessor silicon die temperature prediction both under steady and transient states. Firstly, one-dimensional thermal network with average temperature nodes is constructed with the thermal spreading resistance and the thermal local resistance. Secondly, characteristics of thermal resistances under steady state are discussed. By conducting three-dimensional heat conduction simulation, thermal resistance values are evaluated for the case with different cooling solutions and different heat distributions at silicon die bottom of microprocessor. Thirdly, thermal resistance behavior of introduced thermal network during transient state is explored for further understanding of temperature transition of the microprocessor silicon die. Since the thermal spreading resistance takes relatively large value and changes its value drastically, this paper investigates transient behavior of thermal spreading resistance from TIM (Thermal Interface Material) to heat sink base as an example.Copyright © 2013 by ASME

In this report, we extend our investigation to characterization of junctions produced by the excimer laser irradiation to 4H-SiC immersed in phosphoric acid.

An improved interference method is proposed to determine ordinary and extraordinary refractive index dispersions of nematic liquid crystals (LCs). In this method, an LC cell coated with a thin metal layer is used as a Fabry-Perot interferometer, which shows us a sharp transmission fringe. To ensure high reliability, the wavelength dispersion of the refractive index of the metal is taken into account in fitting calculation. In spite of measuring ordinary and extraordinary components, the LC cell, polarizers, and other equipment are not rotated during the experiment. The index evaluation from a single spectrum avoids errors depending on the measurement position owing to non-uniformities of molecular orientation and cell thickness because we can obtain the two indices at exactly the same position. This system can adapt to a wide frequency range and does not require any specific wavelength light source or laser. We demonstrate the determination of ordinary and extraordinary refractive index dispersions of a nematic liquid crystal in the visible and near-infrared regions. Furthermore, we quantitatively reproduce the measured spectrum by calculation using the measured refractive indices.

We have found that aluminum doping into 4H-SiC is performed by irradiating excimer laser light to 4H-SiC immersed in aluminum chloride solution. Aluminum is introduced in SiC at the concentration of over 1 ? 1020 cm?3 near the surface while, chlorine hardly diffuses into 4H-SiC. After the laser irradiation in aluminum chloride solution, the resistance of the laser-irradiated region decreases with increasing laser fluence. Hall effect measurement shows that the laser irradiation produces a p-type layer and that its sheet carrier concentration is 2.14 ? 1011 cm?2. In addition, we produce a pn junction by doping the surface of n-type 4H-SiC and by aluminum doping. The pn junction shows rectifying characteristics whose on/off ratio is about 7 decades and ideality factor is 1.15. This technique is one of the strong candidate local doping techniques for SiC.

We developed a method to dope phosphorus into 4H-SiC by irradiating excimer laser light to 4H-SiC immersed in phosphoric acid solution. A KrF excimer laser was used. The surface is slightly ablated by the laser irradiation. However, no amorphous layer is generated near the surface. Phosphorous is introduced at a concentration of over 1020 cm-3 near the crystal surface. The laser irradiation in phosphoric acid solution significantly improves the ohmic contact characteristic between metal and 4H-SiC. Hall effect measurement shows that the irradiation produces an n-type layer at the surface whose sheet carrier concentration is 2.25×1012 cm-2. In addition, we produce a pn junction by irradiating p-type 4H-SiC. The pn junction shows a rectifying characteristic whose on/off ratio is over 8 decades and ideality factor is 1.06.

Phosphorus doping of 4H SiC is performed by KrF excimer laser irradiation of 4H SiC immersed in phosphoric acid. Phosphorus is incorporated to a depth of a few tens of nanometers at a concentration of over 1020/cm3 without generating significant crystal defects. Formation of a pn junction diode with an ideality factor of 1.06 is demonstrated.