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Recently nanoparticles reinforced lead free solders are vastly developed in electronics packaging industry. Studies and investigations have been conducted to learn and investigate the types, properties, method, availability and importance of nanoparticles in this field.

Mechanical properties, melting temperature and microstructural conditions are taken into major considerations in any of the preparation on nanoparticles and being reviewed in this paper. Segregation of the types of nanoparticles being added together with their properties is summarized in this paper. High temperature reliability is crucial in providing a good viable solder and hence addition of nanoparticles have been seen to give a positive outcome in this particular property.

This paper reviews on the beneficial of the various nanoparticles addition in the solder. Briefed explanations and the factors are revealed in this review.

This paper reviews on the beneficial of the various nanoparticles addition in the solder.

Soldering and diffusion bonding each have benefits and drawbacks. Solders are capable of bridging joints of irregular geometry but the joints tend to have significant void levels if they are of large area. Erosion of joint surfaces and embrittlement through interalloying with parent materials represent additional weaknesses. Diffusion bonding avoids these problems, but it is not as tolerant to rough mating surfaces and joint quality is highly sensitive to the cleanliness of the surfaces. This type of process usually requires the application of high loads. A hybrid of these two methods of joining known as diffusion soldering combines the merits of both. The metallurgical principles and some features of diffusion soldering are outlined, with reference to the silver/indium and silver/tin systems. The benefits of applying diffusion soldering processes to the fabrication of assemblies in the electronics industry are explained.

High silicon Si–Al alloys (50–70 wt% Si) have been developed by Osprey Metals Ltd for use in electronic packaging. They have the advantages of a coefficient of thermal expansion that can be tailored to match ceramics and electronic materials (6–11 ppm/K), low density (<2.8 g/cm³) high thermal conductivity (>100 W/m K). These alloys are also environmentally friendly and are easy to recycle.These Osprey alloys can be fabricated readily into electronic packages by conventional machining with tungsten‐carbide or polycrystalline diamond (PCD) tools and electro‐discharge machining (EDM). Generally more than one of these conventional machining operations is required in the fabrication process. A new and much faster method has been developed which has been used to produce complete electronic packages from plates of Si–Al alloys in a single machining step. In this novel method, known as thin‐shell electroforming (TSE), an accurate model of the package is produced directly from the drawing in wax using a 3D Systems ThermoJet Modeller. This model is mounted into a frame and it is then plated with a thin copper electroform. The wax model is then melted leaving the electroform attached to the frame. This is backfilled with solder and used as the EDM tool for machining the package from a plate of Si–Al alloy.

The comparatively new process of diffusion soldering combines the merits of Soldering and diffusion bonding. It is tolerant to surfaces that are not perfectly flat while, at flat while, at the same time, it is capable of producing large‐area joints that are void free, a normal failing of conventional soldering. Diffusion soldering processes have been successfully developed, based copper, silver and gold. The metallurgical principles behind the design of these processes are explained and prospective applications of each of the diffusion soldering systems are described. These range from the attachment of heat‐sinks to silicon power devices, to jewellery and the fabrication of semiconductor packaging.

The purpose of this paper is to investigate the effects of addition Co nanoparticles on the characteristic properties of Sn‐3.8Ag‐0.7Cu solder.

Cobalt (Co) nanoparticles were added to Sn‐Ag‐Cu solders by thoroughly blending various weight percentages (0‐2.0 wt%) of Co nanoparticles with near eutectic SAC387 solder paste. Blending was done mechanically for 30 min to ensure a homogeneous mixture. The paste mixture was then reflowed on a hot plate at 250°C for 45 s. The melting points of nanocomposite solder were determined by differential scanning calorimetry. Spreading rate of nanocomposite was calculated following the JIS Z3198‐3 standard. The wetting angle was measured after cross‐sectional metallographic preparation.

No significant change in melting point of the solder was observed as a result of Co nanoparticle addition. The wetting angles of the solder increased with the addition of nanoparticles, while the spreading rate decreased. Although the wetting angle increased, the values were still within the acceptable range. Scanning micrograph observations revealed that the as‐solidified microstructure of the composite solder was altered by the addition of Co nanoparticles. Microhardness of the solders slightly increased upon Co nanoparticles addition to SAC387.

The paper demonstrates that a simple process like paste mixing can be used to incorporate nanoparticles into solder.

The set of properties required for microwave packaging materials intended for aerospace applications is discussed in relation to the current range of materials that are commercially available. Initiatives are being taken to replace kovar, the established packaging material, with substitutes which are lighter, stiffer and offer superior heat‐sinking. Promising in this regard are new family of beryllium‐beryllia and also silicon‐aluminium (Si‐Al) alloys high in silicon, with ratios of constituents chosen such that they optimally complement gallium arsenide MMIC devices and alumina circuit boards. Both types of material are relatively easy to machine and electroplate. Demonstrator microwave amplifier modules incorporating the Si‐Al alloys have been designed for space applications and have been successfully produced and tested. The manufacturing technology that has been developed for this purpose is described.

This article aims to explore the challenges posed by the conceptual framework and diversity of practice of education for sustainable development (ESD). The implications of plurality of ESD perspectives and methodological approaches as well variations in ESD practice will be addressed. Critical framework for conceptualizing of ESD which takes environmental ethics into account will be proposed through the discussion of The Ecocentric and Anthropocentric Attitudes Toward the Sustainable Development (EAATSD) scale.

The paper opted for a general review approach, covering literature that provides an overview of the concepts and practices of ESD, as well as program evaluation studies. Additionally, qualitative evaluation of EAATSD scale with students of higher professional education was conducted, using in-depth interviews and dialogue with individual students as well as classroom discussions.

It was found that there are wide and inconclusive debates about the aims of ESD based on the critique of sustainable development discourse in general and instrumentalism embedded in ESD in particular. According to the qualitative evaluation, EAATSD scale can be used for testing anthropocentric and Ecocentric Attitudes Towards Sustainable Development in students of higher education. Based on these results, this scale was found to be revealing of the critical view of paradoxes and challenges inherent in multiple goals of sustainable development as well as useful for testing anthropocentric and ecocentric attitudes in students of higher education.

Reliability of the scale needs further statistical testing, and as is the case in conventional EE/ESD evaluations, and consequent research is necessary to improve institutional, national, and international applicability to particular cases. Future research should draw from this critical review in order to devise alternative evaluation tools.

In practice, this implies that currently administered evaluations of generic ESD, while useful in concrete cultural or institutional settings, might be premature. The article concludes with the reflection upon which conceptual, methodological, cultural, and ethical challenges of ESD which should be useful for ESD researchers and practitioners in different national settings.

This article fulfills an identified need to address the paradoxes of sustainable development and to study how ESD can be more effective.

This study aims to develop indium-based solders for cryogenic applications.

This paper aims to investigate mechanical properties of indium-based solder formulations at room temperature (RT, 27 °C) as well as at cryogenic temperature (CT, −196 °C) and subsequently to find out their suitability for cryogenic applications. After developing these alloys, mechanical properties such as tensile and impact strength were measured as per American Society for Testing and Materials standards at RT and at CT. Charpy impact test results were used to find out ductile to brittle transition temperature (DBTT). These properties were also evaluated after thermal cycling (TC) to find out effect of thermal stress. Scanning electron microscope analysis was performed to understand fracture mechanism. Results indicate that amongst the solder alloys that have been studied in this work, In-34Bi solder alloy has the best all-round mechanical properties at RT, CT and after TC.

It can be concluded from the results of this work that In-34Bi solder alloy has best all-round mechanical properties at RT, CT and after TC and therefore is the most appropriate solder alloy amongst the alloys that have been studied in this work for cryogenic applications

DBTT of indium-based solder alloys has not been found out in the work done so far in this category. DBTT is necessary to decide safe working temperature range of the alloy. Also the effect of TC, which is one of the major reasons of failure, was not studied so far. These parameters are studied in this work.

Date: 26 October 1994 Venue: The Regency Hotel, Shirley, Solihull, West Midlands This conference will highlight technological advances being made as we approach the 21st century. Papers cover a wide range of scientific and technical developments and latest advances in production techniques, particularly those which may involve environmental considerations. The programme will appeal to end‐users, planners, designers and production technologists, as well as development engineers and scientists.