Design Of Electronic Equipment Research Articles

Experimental Evaluation of Air-Cooling Electronics at High Altitudes

The effect of altitude on electronic cooling is evaluated experimentally. Material properties of air vary as a function of altitude due to changes in atmospheric pressure and temperature. These changes have a negative impact on the heat transfer effectiveness and result in higher component temperature when compared to sea level conditions. Experiments are carried out in a hypobaric chamber using electronic printed circuit boards populated with heated rectangular blocks placed in a small wind tunnel. The altitude is varied between 0 and 5000 m above sea level and the air speed is varied between 1 and 5 m/s. The results show the local adiabatic heat transfer coefficient and thermal wake function diminish with altitude. This information is useful for design and analysis of electronic equipment for operation over a range of altitudes and air speeds typically encountered in forced air convection cooling applications.

Operation fulcrum and the fulcrum concept

GE Plastics’ vast design and materials knowledge about engineering thermoplastics has been helping shape the design and manufacture of handheld, portable, and mobile electronic products and equipment since their inception. Now, with the findings from Operation Fulcrum and the analysis of 15 commercially available notebooks, GE Plastics is helping the portable electronics community employ leading edge design solutions. Key findings of the program have been incorporated into an industry first: the Fulcrum Notebook Concept, which combines best-in-class thermal management and EMI shielding solutions and advances in engineering thermoplastics design for manufacturing and assembly. The Fulcrum Notebook Concept has been further enhanced by GE Plastics’ developments in thinwall technology and the creative solutions devised by the team at Polymer Solutions Inc. (PSI), a joint venture of GE Plastics and Fitch.

Investigation of Convergence of Optimal Design of Die press using Finite Elements and Optimization Technique

Various optimization methods, such as Rosenbrock method (RBM), simulated annealing method (SAM), genetic algorithm (GA), evolution strategy (ES), are trying to be used in the optimal design of electrical machines and electronic equipment. In order to apply these optimization methods to the practical design of magnetic devices using the finite element method, problems in using the optimization methods, such as acceleration technique of the convergence of optimization method, effect of finite element subdivision on the obtained optimal value, should be investigated.In this paper, effects of initial value, searching region, convergence criterion, number of elements on the obtained optimal value are examined using the die press model (Problem 25) which is the standard model of TEAM International Workshop. It is shown that the fine mesh having about 1% accuracy of flux density is necessary in order to obtain the optimal dimension having about 1% accuracy. The number of iterations of RBM and SAM can be reduced by using the initial value which is obtained using the experimental design method (EDM). Finally, features of RBM, SAM, ES and combination methods are compared with each other from the viewpoints of obtaining the global optimal value and quick convergence.

Material and geometry factors in joint design of electronic equipment to minimize electromagnetic interference

Reducing electromagnetic interference in electronic equipment is of great importance. This is normally accomplished by increasing the shielding effectiveness of the enclosure. In this study, shielding effectiveness is examined against enclosure material, joint geometry, and operating frequency. An experimental apparatus is designed and manufactured to aid in finding the suitable joint configurations and materials with high shielding effectiveness. Three groups of material, namely, metallic, filled polymers, and metalized filled polymers, are investigated. In addition to the choices of material, effect of joint configurations on shielding behavior are examined. Based on the experimental results, empirical relations are developed that relate shielding effectiveness to effective length, shape factor, and aperture dimensions ofthejoint structure. Finally, the best material and joint geometry among the investigated cases are presented.

Investigation of composite materials selection and joint layout design to enhance EMI shielding of electronic equipment

AbstractElectromagnetic shielding is a critical issue in the design of electronic equipment. This is mostly due to the high receptivity of electronic components to unwanted electromagnetic emission and interference. To reduce this interference, a study is initiated to determine the effect of material and joint types on the shielding effectiveness of an electronic enclosure. Eight different but progressively more complex joints are designed and investigated in this study. Filled polymers and metallized filled polymers are selected and compared with the all metallic structures. An analytical approach utilizing conformal mapping to calculate the shielding effectiveness of joints is attempted. An experimental apparatus is designed and manufactured to aid in finding the best possible joint configurations. Economic factors in selecting optimum joint layout are also studied. A cost index relating the effective length, design factors, and the total length of the part is developed. Results are presented for the best joint configuration and material with the highest shielding effectiveness.

Flow Resistance Correlation of Wire Nets in a Wide Range of Reynolds Numbers for Thermal Design of Electronic Equipment

Flow Resistance Correlation of Wire Nets in a Wide Range of Reynolds Numbers for Thermal Design of Electronic Equipment

Problem of optimal synthesis of load components in the design of electronic equipment

This paper presents a method for solution of the problem of optimal synthesis of designs capable of handling given operational loads. Results of solving the problem of synthesizing shape for a design are given.

Review of Heat Transfer Technologies in Electronic Equipment

Thermal control has become a critical factor in the design of electronic equipment because of the recent trends in the electronic industry towards increased miniaturization of components and device heat dissipation. A great demand on the system performance and reliability also intensifies the needs for a better thermal management. The further evidence of importance of thermal consideration to an electronic system is due to the survey by the U.S. Air Force indicating that more than fifty percent of all electronics failures are caused by the undesirable temperature control. This paper reviews recent technologies in thermal control and management of electronic equipment.

Predicting the reliability of electronic equipment

The use of reliability predictions in the design and operation of electronic equipment has been an evolutionary and very controversial process, and over the past decade, reliability prediction methods have been a focal point for a flurry of books, papers, editorials, opinions, special sessions, and workshops. While it is generally believed that reliability assessment methods should be used to aid in product design and development, the integrity and auditability of the reliability prediction methods have been found to be questionable; in that, the models do not predict field failures, cannot be used for comparative purposes, and present misleading trends and relations. This paper discusses the role of reliability prediction and assessment in design, development, and deployment of electronic equipment; overviews the history of reliability predictions for electronics; discusses the advantages and disadvantages of some current methods; and presents some of the key research questions which need to be addressed.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Developments in simulation information technology and use in electronic equipment design

Descriptions are given of simulating-system structure and the interaction with the user, which determine the simulation, which is part of a large iterative optimal design process.

Comparison of electronics-reliability assessment approaches

Two general approaches available for assessing the reliability of electronics during design are device failure rate prediction, and physics-of-failure. This work broadly compares these two approaches in a way that is readily understandable by the wide range of readers concerned with the design, manufacture, and support of electronic equipment.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Power electronics in warships

‘Warships are different’—a truism that is often used in maritime circles to explain the difference between the use of equipments in naval vessels and in other maritime and industrial environments. This article sets out to explain some of the differences and their effect on the design of power electronic equipment, as fitted typically in the Royal Navy&apos;s latest frigate, the Type 23.

Comparison of standards and power supply design options for limiting harmonic distortion in power systems

Harmonic distortion in power systems is growing due to the popularity of switch-mode power electronic equipment. This equipment has recognized advantages, such as reducing weight and improving control and efficiency in power converters and supplies. A disadvantage of switch-mode power converters is that their lowest-cost circuit may burden the power system with harmonic loading. Methods to reduce this distortion are recognized, but economic incentives are yet to be realized. Standardization is the most effective means to influence equipment design and to control distortion in power systems. The authors compare the major European and American standards, as well as some of the electronic equipment design changes that are supposed to limit harmonics. >

Surviving hell and high water (electronic equipment design)

How to arrest corrosion and clean off contaminants after equipment is exposed to fire or flooding is described. Designing electronic equipment that sustains minimum flooding or fire damage is addressed.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

The influence of temperature on integrated circuit failure mechanisms

AbstractTemperature is generally considered to be a key parameter in the design of electronic equipment, and cautions concerning temperature and its relationship to reliability are widely documented. While some studies suggest that temperature is the most critical stress influence on microelectronic device failures, the actual failure mechanisms have generally not been quantified in terms of whether a steady state temperature, temperature change, rate of temperature change, or spatial temperature gradient induced failure. In this paper, the influence of temperature on major integrated circuit failure mechanisms is discussed, with emphasis placed on those failure mechanisms which occur in the temperature range of ‐55°C to 125°C. This paper shows that no simple expression can adequately describe temperature as a failure accelerator for all integrated circuit failure mechanisms. In fact, a generic statement that can be attributed to temperature is lacking. This suggests that a much deeper level of insight into temperature dependencies is necessary to achieve reliable equipment and avoid unnecessary thermal design complexities. Thermal management in electronic equipment can involve additional costs and system complexities that can be of consequential importance, and temperature control should not be routinely employed without close study and justification.

How failure prediction methodology affects electronic equipment design

AbstractElectronic equipment designs embody measures and techniques to enhance reliability. Often, concepts of designing for failure avoidance are inferred from various failure prediction methodologies (FPM) such as MIL‐HDBK‐217,1 BellCore2 etc. However, these FPM models do not accurately predict actual failures of completed assemblies, for they usually emphasize component parts as the dominant cause of problems, and the models cannot be kept up to date. Furthermore, the true causes of failure are not described, and thus they cannot be accomodated by design. As such, use of FPM as a source of guidance for reliability‐enhancing activities in producing reliable products may have less effectiveness than originally intended. Some FPM encouraged features can impose heavy costs, complexities and other penalties. By adopting solutions to problems that are inaccurately defined, true problems may be unaddressed.

Computer aids for electronic equipment design — 21 years on

In 1968, Eric Wolfendale wrote an article entitled ‘Computer aids for electronic equipment design’ in the first issue of Computer-Aided Design. At the time Wolfendale led a team within Racal Research Ltd that was investigating the possibilities for automating aspects of the process of designing electronic equipment. In the intervening twenty years, Wolfendale's research team has transformed itself into a supplier of electronic design automation (EDA) systems, the Racal Redac Group. Reading Wolfendale's article now is an enlightening task, because it reveals that while substantial progress has been made in developing software to support EDA, the pioneers in the field had clearly identified most, if not all, of the major issues.

Control of the Topside Electromagnetic Environment

ABSTRACTThe surface combatant's topside electromagnetic environment is becoming more complex. The quantity of antennas has been increasing, radiation characteristics are becoming more varied, and there are more modes of operation and a larger library of radiating parameters. Automatic computer control of radiators is more prevalent as is increased output power. Furthermore, there has been a reduction in maximum safe exposure limits for personnel, and there is an increased awareness of the importance of radar cross section reduction. The result is that ship designers and system operators are faced with conflicting requirements. The future will require electronic equipment designers to be more innovative and replace traditional systems with those of more flexibility. Potential solutions to the situation will require increased attention to both topside design and to the tools provided to the operators. Areas warranting further attention include the physical shape of the topside structure and equipment, movable antennas, increased use of radiation absorbing material, and movable radiation barriers. Safe radiation limits for personnel need to be made more flexible. Wartime rules and battle conditions will be different than peacetime. Some of our ordnance needs to be tested and possibly redesigned, so as to be less susceptible to electromagnetic radiation. And finally, complex surface combatants will require computer‐based expert systems to assist the operators in making decisions as to what to radiate, how to permit or restrict the movement and firing of ordnance, and the limitations to be placed on personnel access topside under peacetime, wartime and battle conditions.

Quo Vadis Printed (Circuit) Board?

Printed (circuit) boards have been used in the electronics industry for the past 25 years and more. The technology used to design and manufacture PCBs is well known and accepted. Recently, however, designers of electronic equipment have shown that the use of newer materials and systems, such as flexible and moulded circuits, hybrid circuits, or a combination of these, can significantly improve the cost/performance ratio for electronic interconnects. This paper examines some of the many possibilities open to electronics designers and how these new opportunities can improve the economics and performance of electronic equipment.

Silicon Integration and Its Impact on the Hybrid Industry

Rapid advances in silicon, including ever higher complexity and easier access to customised approaches, are forcing dramatic changes in electronic equipment design and manufacture. This paper examines the developing role for hybrid microcircuits and concludes that hybrid technology, often thought of as optional, should now be regarded as an essential partner for monolithic silicon technology.