Surface activated bonding of LCP/Cu for electronic packaging

A lamination technique for liquid crystal polymer (LCP)/Cu was developed for high speed and high performance printed circuit boards (PCB). This approach was accomplished by using a modified surface activated bonding (SAB) process to achieve enhanced adhesion and a smooth interface. Systematic investigation of peel strength of four categories of samples, namely “as bonded”, “annealed”, “Cu-deposited”, and “Cu-deposited and annealed” showed highest peel strength in the “Cu-deposited and annealed” sample. Significant improvements in adhesion were observed in the samples cleaned with argon-radio frequency (Ar-rf) plasma (“as bonded” samples) followed by Cu deposition on LCP, which were heated after bonding in low vacuum pressure at 240∘C (about 70–75 times higher than that of “as bonded”). XPS analyses on peeled surfaces of the “Cu-deposited and annealed” sample reveal bulk fracture in the LCP. Threefold lower loss in conduction of SAB processed laminate than that of conventional heat laminate was most likely due to smooth interface of the SAB processed laminate (surface roughness was ninefold lower than that of conventional heat laminate). A plausible adhesion mechanism of Cu/LCP might be due to bonding of Cu adhesion sites to plasma induced dangling sites of LCP surface, and thermal reconstruction of Cu deposited layers.     

Application of compensating diode voltmeters in metrological practice

The distinctive features of calibration and application of compensating diode voltmeters as standards are examined and the principal error of a voltmeter calibrated as a first-class standard in the 10 Hz to 1500 MHz frequency range is calculated.The Editors call the attention of authors and readers to the desirability of replacing in technical documentation and submitted papers the obsolete (according to the “Law of Unity of Measurements” passed by the Russian Federation) terms “reference measuring instrument” and, nearly always, “metrological certification” with “standard” and “calibration” respectively.Translated from Izmeritel'naya Tekhnika, No. 2, pp. 43–45, February, 1995.     

Thawing and freezing of selected meat products in household refrigerators

Recently, several manufacturers of domestic refrigerators have introduced models with “quick thaw” and “quick freeze” capabilities. In this study, the time required for freezing and thawing different meat products was determined for five different models of household refrigerators. Two refrigerators had “quick thaw” compartments and three refrigerators had “quick freeze” capabilities. It was found that some refrigerator models froze and thawed foods significantly faster than others (P<0.05). The refrigerators with the fastest freezing and thawing times were found to be those with “quick thaw” and “quick freeze” capabilities. Heat transfer coefficients ranged from 8 to 15 Wm⁻²K⁻¹ during freezing, and the overall heat transfer coefficients ranged from 5 to 7 Wm⁻² K⁻¹ during thawing. Mathematical predictions for freezing and thawing time in the refrigerators gave results similar to those obtained in experiments. With the results described, manufacturers can improve their design of refrigerators with quick thawing and freezing functions.     

“The ‘De-materialisation’ Myth” and the Limits to Growth: a Commentary on Dr. Trainer's Paper

Dr. Ted Trainer's paper in this issue contends that “de-materialisation” (decreasing energy and material inputs per unit of output) is a “myth” that must now be dropped from arguments against the “limits to growth” thesis. His specific arguments against de-materialisation are questioned in this commentary. This paper goes on to argue that even if de-materialisation has not taken place, it does not follow that near-term “zero growth” becomes necessary. On the contrary, the “limits to growth” position rests on erroneous Malthusian projections, and if the scarcity and spillover effects of growth are appropriately priced, conservation and substitution will be induced. Economic growth will facilitate technological and economic solutions to pollution and depletion. Institutional arrangements that will structure incentives, such as making better use of markets to set appropriate prices, are at the heart of the sustainability problem.     

Ethics of family planning

The expression, “ethics of family planning,” it is argued, has no firm meaning, and should not be taken to imply that a full set of moral rules and principles governing family planning has been or is likely to be established. A survey is made of recent views on population and economic and social development, and it is argued that, although there is, indeed, no “universal problem” of population, the optimistic — as well as the pessimistic — view of this relationship is open to doubt. It is further argued that “ethics” cannot be imposed on subject matter of population from without: The very identification of a “problem” of population is evaluative from the start. A scheme of analysis to appraise the ethical status of measures to arrest or promote population growth is proposed, and a number of such measures are critically analyzed.     

A black tournai “marble” tombslab from Belgium imported to Trondheim (Norway) in the 12th century: Provenance determination based on geological, stylistic and historical evidence

Black Tournai “marble”, a fine-grained Lower Carboniferous (Tournaisian) limestone able to take a good polish has been widely used in the Flanders region (Belgium). Highly crafted baptismal fonts and tombslabs were also exported to England, France and elsewhere during the Middle Ages. Such objects are particularly valuable since their distribution aids the dating of historical events and the reconstruction of medieval trade. Similar black “marble” was extracted in the Meuse valley (Belgium) in the Middle Ages, and there are exploited sources in the UK, Ireland and elsewhere. Thus, it is not straightforward to determine the provenance of black “marble”. Based on geological, stylistic and historical evidence, this paper shows the likelihood that a black “marble” tombslab found in Nidaros Cathedral in Trondheim (Central Norway) was extracted and crafted in Tournai and shipped northwards around 1160, possibly for the grave of the first Norwegian archbishop, Jon Birgerson. The tombslab represents the first known crafted stone imported to Norway from the European continent/British Isles and is thus unique in a historical context. The properties of the Trondheim tombslab match those of black Tournai “marble”: It is a silicified, bioclastic packstone loaded with crinoids, featuring bryozoa and fragments of brachiopods and ostracods. The high silica content and absence of foraminifers distinguish the stone from the Viséan black “marble” quarried in the Meuse valley.     

A logical model for quantification of occupational risk

Functional block diagrams (FBDs) and their equivalent event trees are introduced as logical models in the quantification of occupational risks. Although a FBD is similar to an influence diagram or a belief network it provides a framework for introduction in a compact form of the logic of the model through the partition of the paths of the equivalent event tree. This is achieved by consideration of an overall event which has as outcomes the outmost consequences defining the risk under analysis. This event is decomposed into simpler events the outcome space of which is partitioned into subsets corresponding to the outcomes of the initial joint event. The simpler events can be further decomposed into simpler events creating a hierarchy where the events in a given level (parents) are decomposed to a number of simpler events (children) in the next level of the hierarchy. The partitioning of the outcome space is transferred from level to level through logical relationships corresponding to the logic of the model.Occupational risk is modeled trough a general FBD where the undesirable health consequence is decomposed to “dose” and “dose/response”; “dose” is decomposed to “center event” and “mitigation”; “center event” is decomposed to “initiating event” and “prevention”. This generic FBD can be transformed to activity—specific FBDs which together with their equivalent event trees are used to delineate the various accident sequences that might lead to injury or death consequences.The methodology and the associated algorithms have been computerized in a program with a graphical user interface (GUI) which allows the user to input the functional relationships between parent and children events, corresponding probabilities for events of the lowest level and obtain at the end the quantified corresponding simplified event tree.The methodology is demonstrated with an application to the risk of falling from a mobile ladder. This type of accidents has been analyzed as part of the Workgroup Occupational Risk Model (WORM) project in the Netherlands aiming at the development and quantification of models for a full range of potential risks from accidents in the workspace.     

Industry's role in improving the United States' economic and competitive performance

The author argues that the United States has paid insufficient attention in recent years to the relationship between its overall economic well-being and technology. He states that a major goal of the Clinton Administration, and the objective of the Technology Administration in the Department of Commerce, is to work with industry to address these issues. The ways in which this is being done are examined, and the issues involved in answering the questions: “Where are we?,” “Where are we going?,” and “How do we get there?” are discussed.     

Evaluation of the mean ice ratio as a function of temperature in a heterogeneous food: Application to the determination of the target temperature at the end of freezing

The freezing process is widely used in the food industry. In the 70s, French regulation authorities have created in collaboration with the food industry the concept of «surgélation» process with the objective of improving the image of high quality frozen foods. The process of “surgélation” which could be translated as “super freezing” corresponds to a freezing process for which a final temperature of −18 °C must be reached “as fast as possible”. This concept was proposed in opposition to a conventionally “freezing” process for which no specific freezing rate is expected and the final storage temperature can be of −12 °C only. The objective of this work is to propose a methodology to evaluate the mean amount of frozen ice in a complex food as a function of temperature and to deduce a target temperature that must be considered as the temperature for which the food may be considered as “frozen”. Based on the definition proposed by the IIF-IIR red book, this target temperature has been defined as the temperature for which 80% of the freezable water is frozen. A case study is proposed with a model food made of two constituents.     

Biomemory device composed of mutant azurin thin films modified by site-directed mutagenesis

A bioelectronic device composed of self-assembled mutant azurin thin films with memory function has been developed for molecular electronics. Azurin was recombined with a cysteine residue to enhance the stability of self-assembled protein on gold surface. The thin films of protein on gold substrate were investigated by surface plasmon resonance spectroscopy, scanning tunneling microscopy and Raman spectroscopy, respectively. The memory characteristics, including the “read”, “write” and “erase” functions of self-assembled azurin layer, were obtained with three distinct electrical states of azurin layers by cyclic voltammetry. These results show the proposed biomemory device as a step towards the protein based nanobiochip.     

Visible luminescence in photo-electrochemically etched p-type porous silicon: Effect of illumination wavelength

The effect of low power density of ~ 5 μW/cm² monochromatic light of different wavelengths on the visible photoluminescence (PL) properties of photo-electrochemically formed p-type porous silicon (PS) has been investigated. Two-peak PL “red” and “green” is resolved in PS samples etched under blue-green wavelength illumination; 480, 533 and 580 nm. It is found that the weight of “green” PL has maxima for the sample illuminated with 533 nm wavelength. Whereas, PL spectra of PS prepared under the influence of red illumination or in dark does not exhibit “green” PL band, but shows considerable enhancement in the “red” PL peak intensity. Fourier transform infrared (FTIR) spectroscopic analysis reveals the relationship between the structures of chemical bonding in PS and the observed PL behavior. In particular, the PL efficiency is highly affected by the alteration of the relative content of hydride, oxide and hydroxyl species. Moreover, relative content of hydroxyl group with respect to oxide bonding is seen to have strong relationship to the blue PL. Although, the estimated energy gap value of PS samples shows a considerable enlargement with respect to that of bulk c-Si, the FTIR, low temperature PL and Raman measurements and analysis have inconsistency with quantum confinement of PS.     

Urban security in perspective

Cities, which encompass a large and growing portion of the world population, are primary targets for terrorism and are particularly vulnerable because of the interdependence of their systems. Cities' threats and targets are reviewed and a series of principles and observations about the protection of cities are suggested. Some lessons learned from the events of September 11, 2001 are outlined and complemented by suggestions of needs, both technical and socio-technological, that need to be addressed.     

Development and validation of “grey-box” models for refrigeration applications: A review of key concepts

“Grey-box” modelling combines the use of first-principle based “white-box” models and empirical “black-box” models, offering particular benefits when: (a) there is a lack of fundamental theory to describe the system or process modelled; (b) there is a scarcity of suitable experimental data for validation or (c) there is a need to decrease the complexity of the model. The grey-box approach has been used, for example, to create mathematical models to predict the shelf life of chilled products or the thermal behaviour of imperfectly mixed fluids, or to create models that combine artificial neural networks and dynamic differential equations for control-related applications. This paper discusses the main characteristics of white-box, black-box and their integration into grey-box models, the requirements and sourcing of accurate data for model development and important validation concepts and measures.     

The effect of information types on diagnostic strategies in the information aid

Through experiments, this paper investigates the compatibility of information types with the diagnostic strategy in information aid. Compatibility with operator strategies is an important requirement for information aiding systems in nuclear power plants (NPPs). This paper used three typical types of information aids for MCR operators to investigate the effect of the aids on diagnostic strategies: “alarm (A),” “hypothesis on faults (H),” and “hypothesis on faults and expected symptoms (HS).” The experimental results indicate that the effectiveness of information aid types can vary, dependent on the strategies subjects employ. The results also show that the HS aid improved the diagnosis performance in the hypothesis-and-test strategy.     

Basic research: Its impact on China's future

Not only have science and technology received growing priority in China's development strategy, but basic research has also received greater attention in the country's policies on science and technology. From Deng Xiaoping's notion that “science and technology are the primary productive force” to the national strategy of “invigorating China through science and education,” China has experienced a deepening and maturing process in understanding the characteristics and values of modern science—especially basic research—and the roles of science in the country's economic and social development.     

Rare events probabilities estimation by “ Russian Roulette and Splitting ” simulation technique

An advanced Monte Carlo Simulation (MCS) technique—namely, “Russian Roulette and Splitting” (RR & S) technique is applied for the reliability assessment of mechanical systems under stochastic excitations. The basic features of the algorithm are described and discussed. As a numerical example the technique is used for the numerical solution of the first passage problem in the low probability range. Results are compared with available solutions, obtained by another variance reduction technique—“Double and Clump”(D & C) procedure.     

Corrosion resistance of AlN–SiC–TiB2 composite in air

The oxidation kinetics of AlN–SiC–TiB₂ composite in air has been investigated in terms of a theoretical analysis associated with the experiment data. The effects of temperature and temperature heating rate on the oxidation reaction have been discussed by using the “characteristic oxidation time”. The results show that the calculated results by our model can give a good agreement with the experimental data. From this study it is shown that, the “characteristic oxidation time” is a very useful parameter for comparing the property of oxidation resistance for different composites.     

The fast alternative cryogenic experiment testbed

Subsystems for a “proof of concept” cryogenic payload have been developed to demonstrate the ability to accommodate low temperature science investigations within the constraints of the Hitchhiker siderail (HH-S) carrier on the Space Shuttle. These subsystems include: a hybrid solid neon – superfluid helium cryostat, a multi-channel Versa Modular European (VME) architecture Germanium Resistance Thermometer (GRT) readout and heater control servo system, and a multiple thermal isolation stage “probe” for thermal control of helium samples. The analysis and tests of these subsystems have proven the feasibility of a cryogenic HH-S carrier payload.