Thermodynamic Analysis of Various Dehumidifying Dryers for Wood

Typical methods of dehumidification of air circulating in the dehumidifying driers (indirect and direct cooler and partial exchange of the air) were analysed. Energy aspect of cooler operation was evaluated. The method for minimization of unit thermal energy consumption in a dehumidifying drier by the optimal selection of the cooler point was also given. Methods of the heat recovery of heat conveyed in a cooler lending to save energy (heat regeneration. expansion and compression of the air, a dehumidifier) were analysed. It was indicated that introduction of dehumidifiers into contemporary wood driers caused significant improvement of energy aspects of their operation     

Transparent flexible plastic substrates for organic light-emitting devices

In this paper, we describe the properties of flexible plastic substrates with a transparent conducting electrode (TCE), which are important for organic light-emitting devices (OLEDs). Specifically, we have evaluated the TCE electrical resistivity, surface roughness, electrode patterning, optical transmission, and the substrate water vapor/oxygen transmission. We have studied the effect of ultraviolet (UV)-ozone treatment on the TCE surface by using contact angle measurements and x-ray photoelectron spectroscopy (XPS). A decrease in the advancing contact angle by 30–40° and an increase of oxygen content on the TCE surface by 10 at.% were observed after the UV-ozone treatment. These changes facilitate the polymer adhesion to the TCE surface and increase the TCE surface work function, respectively. A sheet resistance of 12–13 Ω/□, an optical transmission greater than 80% over the visible range, and a surface roughness of 1.4–2.2-nm RMS over 50×50 μm² have been obtained for the plastic substrates. These properties are adequate for OLED applications based on United States Display Consortium specifications. Finally, we have found that a combination of hydrogenated amorphous silicon-nitride and silicon-oxide layers deposited on one side of the substrate at low-temperature reduces the water vapor and oxygen transmission rates (TRs) to less than 10⁻⁵ g/cm²-day-atm and about 10⁻⁷ cc/cm²-day-atm, respectively.     

Discrete Approach to PWL Analog Modeling in VHDL Environment

In this paper a discrete approach to analog modeling is presented. It is a functional-level, piecewise-linear (PWL) technique implemented in the VHDL environment. Since the models are based on some explicit formulas, fully behavioral architectural bodies have been proposed for them. Their most distinguishing features are discussed in detail. The models of practical circuits are illustrated with simulation results.     

MLEK crystal growth of (100) indium phosphide

We have used a combined magnetic liquid encapsulated Kyropoulos/Czochralski (MLEK/ MLEC) technique to produce twin-free indium phosphide (InP) crystals. This technique has advantages over the standard LEC method used for commercial production of InP. By stabilizing convective flows with a magnetic field and controlling the angle between solid and liquid, one can grow large diameter twin-free (100) InP crystals; they are shaped with a flat top as is typical for Kyropoulos growth, and then pulled from the magnetically stabilized melt as in Czochralski growth. This shaping method has the benefit of maximizing the number of single crystal wafers which can be sliced from the boule. MLEK InP growth is distinguished from other methods such as LEC and MLEC with respect to solid-liquid interface shape, dislocation density, and impurity distribution. This process has demonstrated that twin-free InP (100) crystals can be consistently grown.     

Wideband Low‐Reflection Transmission Lines for Bare Chip on Multilayer PCB

The pad pitch of modern radio frequency integrated circuits is in the order of few tens of micrometers. Connecting a large number of high‐speed I/Os to the outside world with good signal fidelity at low cost is an extremely challenging task. To cope with this requirement, we need reflection‐free transmission lines from an on‐chip pad to on‐board SMA connectors. Such a transmission line is very hard to design due to the difference in on‐chip and on‐board feature size and the requirement for extremely large bandwidth. In this paper, we propose the use of narrow tracks close to chip and wide tracks away from the chip. This narrow‐to‐wide transition in width results in impedance discontinuity. A step change in substrate thickness is utilized to cancel the effect of the width discontinuity, thus achieving a reflection‐free microstrip. To verify the concept, several microstrips were designed on multilayer FR4 PCB without any additional manufacturing steps. The TDR measurements reveal that the impedance variation is less than 3 Ω for a 50 Ω microstrip and S11 better than –9 dB for the frequency range 1 GHz to 6 GHz when the width changes from 165 µm to 940 µm, and substrate thickness changes from 100 µm to 500 µm.     

Determination of transistor infant failure probability in InGaP/GaAs heterojunction bipolar technology

A novel circuit for measuring the infant mortality rate in InGaP/GaAs HBT Technology is presented. The circuit allows reliability stressing to be performed on as many as 100,000 transistors per wafer and is necessary in order to predict the infant circuit failure rate in circuits with >500 transistors without costly burn-in screens. This new circuit allows for the rapid identification of failed transistors and subsequent failure analysis to allow for process improvements. A variation of the same circuit has also been used to estimate the activation energy, E_a, of the infant failure mechanism. Rough estimates of E_a indicate that the infant failure mechanism is 0.5 eV, and that there may be two distinct failure mechanisms responsible for infant failures. Process defects have not been found on the vast majority of failed transistors, and there is good correlation between the substrate dislocation density and the infant failure rate. We have concluded that substrate dislocations are the leading cause of infant mortality in our HBT process.     

Isolation of Failing Scan Cells through Convolutional Test Response Compaction

This paper describes a non-recursive fault diagnosis technique for scan-based designs with convolutional test response compaction. The proposed approach allows a time-efficient and accurate identification of failing scan cells using Gauss–Jordan elimination method.

Textural and microstructural transformation of Cu damascene interconnects after annealing

Influence of annealing on the textural and microstructural transformation of Cu interconnects having various line widths is investigated. Two types of annealing steps have been considered here: room temperature over 6 months and 200°C for 10 min. The texture was determined by x-ray diffraction (XRD) of various cross-sectional profiles after electropolishing, and the surface, microstructure, and grain boundary character distribution (GBCD) of Cu interconnects were characterized using electron backscattered diffraction (EBSD) techniques. In order to analyze a relationship between the stress distribution and textural evolution in the samples, microstresses were calculated with decreasing line widths at 200°C using finite element modeling (FEM). In this investigation, it was found that the inhomogeneity of stress distribution in Cu interconnects is an important factor, which is necessary for understanding textural transformation after annealing. A new interpretation of textural evolution in damascene interconnects lines after annealing is suggested, based on the state of stress and the growth mechanisms of Cu electrodeposits.     

The role of grain orientation in microstructure evolution of pure aluminum processed by equal channel angular pressing

A new approach describing the role of crystallographic orientation in the microstructural refinement of commercially pure aluminum during the successive passes of equal channel angular pressing (ECAP) is introduced. The study is based on analysis of X-ray diffraction texture data that is used to calculate the geometrical position of crystallographic slip planes with respect to the shearing plane of the ECAP die. The angular deviations of {111} slip planes from the macroscopic deformation plane for different processing routes were calculated and compared. The microstructure evolution was investigated using electron back-scattered diffraction (EBSD). The grain size and grain boundary character distribution obtained for each processing route are related to the angles between {111} planes and the shearing plane. It was shown that the more effective routes in grain refinement have higher angles between {111} slip planes and the shearing plane.