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This paper describes one of the new package cooling technology concepts using low melting point alloys in order to perform high density packaging. Two kinds of cooling alloy materials, Bi/Sn/In and Bi/Pb/Sn/ln, whose melting points were less than 80°C and whose costs were low, were selected. The experimental substrate sample was fabricated by greensheet technology on which a tungsten metallised resistor heater was formed. Two kovar weld rings were brazed together to the top side and back side surfaces of the substrate individually. One kovar metal shell was laser welded to the top side weld ring in order to protect many devices. Another kovar metal shell, with a hole in the centre, was laser welded to the back side weld ring. The low melting point alloy was melted and poured into the back side kovar shell through the hole in a liquid state. After it was cooled and changed into a solid state, the hole was sealed hermetically with a small kovar metal cap by a laser beam. The authors performed a thermal experiment and confirmed that the substrate back surface temperature was fixed at the cooling alloy material's melting point for several minutes by thermal absorption while the low melting point alloy phase changed from its original solid state into a liquid state. This new package cooling technology is extremely useful for a high power motor drive circuit package which consists of many high power transistor chips and other analogue IC chips, and whose motor drive operation is performed intermittently for several minutes with some interval times.

An empirical study was conducted to determine the thermal fatigue behaviour of 1.27 mm pitch, J‐bend and gullwing surface mount solder joints, manufactured with four low‐temperature solders. Selected solder alloys were: 58Bi‐42Sn (wt %), 43Sn‐43Pb‐14Bi, 52ln‐48Sn and 40ln‐40Sn‐20Pb. Accelerated thermal cycling was used in conjunction with metallographic analysis and mechanical (pull) strength measurement to test their behaviour. The relative merit of each solder composition was determined by comparing it with 63Sn‐37Pb solder, subjected to identical testing conditions. The strength decreased linearly with increased number of thermal cycles for gullwing solder joints of all four solder alloys. The fatigue lifetime was relatively longer for 58Bi‐42Sn and 40ln‐40Sn‐20Pb than for other alloys, but significantly lower than that obtained with 63Sn‐37Pb solder. No discernible degradation of strength was observed with the J‐bend solder joints of any solder alloy, even after the completion of 6000 thermal cycles. Thermal fatigue resistance of the latter joints was attributed to a more favourable coefficient of thermal expansion (CTE) mismatch. Solder joint cracking occurred only in gullwing components soldered with 52ln‐48Sn, 40ln‐40Sn‐20Pb and 43Sn‐43Pb‐14Bi alloys, after 1000 or 2000 thermal cycles. The crack initiated on the outside surface of the solder fillet, and appeared to propagate through both phases of the microstructure. The stress‐induced heterogeneous coarsening of the microstructure was evident only with 43Sn‐43Pb‐14Bi solder, although not as prevalent as that usually observed with eutectic Sn‐Pb solder. Fatigue cracks were absent from solder joints of 58Bi‐42Sn and 63Sn‐37Pb alloys.

This is the first of two papers reporting work carried out under a programme sponsored by the Department of Trade and Industry (DTI), involving collaboration between the International Tin Research Institute, GEC‐Marconi Ltd, BNR (Europe) Ltd and Multicore Solders Ltd. Part 1 describes the methodology used to select a number of candidate alloys as possible suitable lead‐free alternatives to tin‐lead solder.

This paper aims to propose a method that can directly print low-melting-point alloy In61Bi26Sn9Ga4 into a variety of macroscopic 3D structures at room temperature via adhesion mechanism.

In the first section, the principle of the direct printing system is described. As process parameters and material properties have both geometric and physical significance to printing, the approach the authors take is to study the relationships between key parameters and ultimate printed dimension. The surface tension of the fusible alloy is measured under different temperature ranges.

The interaction between the initial standoff distance and the geometry of the first layer is critically important for the adhesion of the liquid metal to the substrate and metal deposition. The characterization of the layer stacking in the direct printing process, stability ranges of the layer thickness and printing speed are also demonstrated. The direct printing system is suitable for making 3D structures with low-melting-point alloy under the summarized range of printing conditions.

This study may arouse big public attention among society.

This study shows possibilities of manufacturing macroscopic 3D metal objects by continuously depositing molten alloy with low viscosity and high surface tension around room temperature. This study provides a supplement to realize compound printing with metal and nonmetal materials together for building terminal functional devices in a low cost and efficient way.

In recent years, efforts to develop alternatives to lead‐based solders have increased dramatically. These efforts began as a response to potential legislation and regulations restricting lead usage in the electronics industry. Lead is extremely toxic when inhaled or ingested. As researchers began to focus on Pb‐free solders, they recognized their value in high temperature applications (e.g. automotive manufacturing) where Sn/Pb solders do not meet the requirements. There are many factors to consider when developing lead‐free alloys: manufacturability, availability, reliability, cost and environmental safety. Of these, the most challenging and time consuming is the reliability of alternative solders. The lead‐free alloys available cannot be used as a drop‐in replacement for the SnPb or SnPbAg. The introduction of lead‐free solder alloys may mean having to use alternative component and PCB metallizations, PCB materials, solder fluxes, etc.

Percival Aircraft Ltd. have recently adopted a most interesting sytem for the economical manufacture of small part press tools. The material used is the K.M. Alloy low melting‐point alloy and by its use the tool room work on punches and dies has been drastically cut. The method is not entirely original, but it is still comparatively little used.

Fused deposition modelling (FDM) has gained popularity owing to its capability of producing complex and customized profiles at relatively low cost and in shorter periods. The study aims to extend the use of FDM printers for 3D printing of low melting point alloy (LMPA), which has applications in the electronics industry, rapid tooling, biomedical, etc.

Solder is the LMPA with alloy’s melting temperature (around 200°C) lower than the parent metals. The most common composition of the solder, which is widely used, is tin and lead. However, lead is a hazardous material having environmental and health deteriorating effects. Therefore, lead-free Sn89Bi10Cu non-eutectic alloy in the form of filament was used. The step-by-step method has been used to identify the process window for temperature, print speed, filament length (E) and layer height. The existing FDM printer was customized for the present work.

Analysis of infrared images has been done to understand discontinuity at a certain range of process parameters. The effect of printing parameters on inter-bonding, width and thickness of the layers has also been studied. The microstructure of the parent material and deposited bead has been observed. Conclusions were drawn out based on the results, and the scope for the future has been pointed out.

The experiments resulted in the process window identification of print speed, extrusion temperature, filament length and layer height of Sn89Bi10Cu which is not done previously.

The purpose of this study is to investigate the tribological performance of the developed self-healing Al6061 composite and to optimize the operating conditions for enhanced tribo-performance of the developed material.

A unique procedure has been adopted to convert the sand casted Al6061 into self-healing material by piercing a low melting point solder material with and without MoS₂. Taguchi-based L9 orthogonal array has been used to optimize the number of experiments and analyze the influence of operating parameters such as speed, sliding distance and load on material wear.

The results reveal that the paper shows the self-healing and self-repair is possible in metal through piercing low melting point alloy. Then, the load has a significant influence over other input parameters in predicting the wear behavior of developed material. Moreover, addition of MoS₂ does not affect the tribo-performance of the developed material. The study concludes that the developed self-healing Al6061 has huge potential to be used in mechanical industry.

The concept of self-healing in metals are very challenging task due to very slow diffusion rate of atoms at room temperature. Therefore, researchers are encouraged to explore the other new techniques to create self-healing in metals.

The self-healing materials had shown huge potential to be used in mechanical industry. The current investigation established a structural fabrication and testing procedure to understand the effects of various parameters on wear. The conclusion from the experimentation and optimization helps researchers to developed and create self-healing in metals.

The previous research works were not focused on the study of tribological property of self-healing metal composite. With the best of author’s knowledge, no one has reported tribological study, as well as optimization of parameters such as speed, load and sliding distance on wear in self-healing metals composite.

A comparative characterisation of selective laser sintering (SLS) mechanisms of single‐ and two‐component powders is presented. The effects of the volume fraction of liquid phase and the powder absorptance were discussed. Single‐component Ni‐alloy, Fe and Cu powders as well as two‐component powder systems based on Ni‐alloy, Fe and Cu were investigated. In particular, the following types of two‐component powder systems were studied: Ni‐alloy‐Cu and Fe‐Cu powder mixtures as well as Cu‐coated Ni‐alloy powder and Cu‐coated Fe powders. SLS experiments were performed with a CW‐ Nd:YAG laser (λ=1.06 μm). The acting mechanism in all cases was liquid phase sintering.

Some components are too fragile, too awkwardly shaped or too highly finished for workholding by conventional clamping. One alternative to the specially made fixture – always slow and expensive to produce – is to use a bismuth‐based low‐melting‐point alloy as the work‐holding medium. Alloys specialist Mining and Chemical Products says that with melting points as low as 47°C and the unique property of expanding on solidification, fusible alloys can often provide a quick and cost‐efficient means of turning difficult work‐pieces into something much easier to hold for machining and handling. The low melting temperatures eliminate risks of heat damage to work‐pieces, while the non‐shrinking characteristic ensures extremely solid support even during the most arduous machining operations. According to MCP, bismuth alloys are also highly economic to use. They can be melted down and used again repeatedly. This is not true of other work‐holding media. Moreover, since many of them contract on solidification they cannot provide the firm and all‐embracing support that is almost always needed.