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Article
Publication date: 17 October 2019

Muhammad Aamir, Riaz Muhammad, Majid Tolouei-Rad, Khaled Giasin and Vadim V. Silberschmidt

The research on lead-free solder alloys has increased in past decades due to awareness of the environmental impact of lead contents in soldering alloys. This has led to the…

Abstract

Purpose

The research on lead-free solder alloys has increased in past decades due to awareness of the environmental impact of lead contents in soldering alloys. This has led to the introduction and development of different grades of lead-free solder alloys in the global market. Tin-silver-copper is a lead-free alloy which has been acknowledged by different consortia as a good alternative to conventional tin-lead alloy. The purpose of this paper is to provide comprehensive knowledge about the tin-silver-copper series.

Design/methodology/approach

The approach of this study reviews the microstructure and some other properties of tin-silver-copper series after the addition of indium, titanium, iron, zinc, zirconium, bismuth, nickel, antimony, gallium, aluminium, cerium, lanthanum, yttrium, erbium, praseodymium, neodymium, ytterbium, nanoparticles of nickel, cobalt, silicon carbide, aluminium oxide, zinc oxide, titanium dioxide, cerium oxide, zirconium oxide and titanium diboride, as well as carbon nanotubes, nickel-coated carbon nanotubes, single-walled carbon nanotubes and graphene-nano-sheets.

Findings

The current paper presents a comprehensive review of the tin-silver-copper solder series with possible solutions for improving their microstructure, melting point, mechanical properties and wettability through the addition of different elements/nanoparticles and other materials.

Originality/value

This paper summarises the useful findings of the tin-silver-copper series comprehensively. This information will assist in future work for the design and development of novel lead-free solder alloys.

Details

Soldering & Surface Mount Technology, vol. 32 no. 2
Type: Research Article
ISSN: 0954-0911

Keywords

Article
Publication date: 6 June 2016

Guang Chen, Li Liu, Vadim V. Silberschmidt, Y.C. Chan, Changqing Liu and Fengshun Wu

This paper aims to systematically study the effect of reinforcement type, processing methods and reflow cycle on actual retained ratio of foreign reinforcement added in solder…

Abstract

Purpose

This paper aims to systematically study the effect of reinforcement type, processing methods and reflow cycle on actual retained ratio of foreign reinforcement added in solder joints.

Design/methodology/approach

Two kinds of composite solders based on SAC305 (wt.%) alloys with reinforcements of 1 wt.% Ni and 1 wt.% TiC nano-particles were produced using powder metallurgy and mechanical blending method. The morphology of prepared composite solder powder and solder pastes was examined; retained ratios of reinforcement (RRoR) added in solder joints after different reflow cycles were analysed quantitatively using an Inductively Coupled Plasma optical system (ICP-OES Varian-720). The existence forms of reinforcement added in solder alloys during different processing stages were studied using scanning electron microscope, X-ray diffractometry and energy dispersive spectrometry.

Findings

The obtained experimental results indicated that the RRoR in composite solder joints decreased with the increase in the number of reflow cycles, but a loss ratio diminished gradually. It was also found that the RRoR which could react with the solder alloy were higher than that of the one that are unable to react with the solder. In addition, compared with mechanical blending, the RRoRs in the composite solders prepared using power metallurgy were relatively pronounced.

Originality/value

Present study offer a preliminary understanding on actual content and existence form of reinforcement added in a reflowed solder joint, which would also provide practical implications for choosing reinforcement and adjusting processing parameters in the manufacture of composite solders.

Details

Soldering & Surface Mount Technology, vol. 28 no. 3
Type: Research Article
ISSN: 0954-0911

Keywords

Content available
Article
Publication date: 3 August 2010

Vadim V. Silberschmidt

474

Abstract

Details

Assembly Automation, vol. 30 no. 3
Type: Research Article
ISSN: 0144-5154

Article
Publication date: 26 January 2010

Hui Xu, Changqing Liu, Vadim V. Silberschmidt, Zhong Chen and Jun Wei

Optimization of the process parameters remains a challenging task in thermosonic wire bonding due to relatively poor understanding of the bonding mechanism. The purpose of this…

Abstract

Purpose

Optimization of the process parameters remains a challenging task in thermosonic wire bonding due to relatively poor understanding of the bonding mechanism. The purpose of this paper is to understand initial bond formation in thermosonic gold wire bonding on aluminium metallization pads and the effect of bonding time on the initiation of bonding.

Design/methodology/approach

A gold wire (20 μm diameter/99.99 per cent wt%) was bonded to aluminium metallization pads (1 μm thick) on a silicon chip using a commercial ball/wedge automatic bonder. Bonding parameters were selected specifically to produce underdeveloped ball bonds so that ball lift‐off occurred during looping process. The lift‐off footprints on the aluminium metallization pads and their evolution were carried out using optical microscopy and scanning electron microscopy. A model is proposed to elaborate the effect of bonding time on initiation of bonding.

Findings

The obtained results showed that metallurgical bonding initiated at the peripheral areas of the contact area situated along the direction of ultrasonic vibration. Those areas extended inwards with bonding time, eventually covering the entire contact area.

Originality/value

This paper describes how bond initiation and its evolution in thermosonic gold wire bonding on aluminium metallization is ascertained by observing lift‐off footprints. The understanding of bonding mechanism benefits the optimization of process parameters and improvement of bondability in thermosonic wire bonding.

Details

Microelectronics International, vol. 27 no. 1
Type: Research Article
ISSN: 1356-5362

Keywords

Article
Publication date: 5 May 2015

Yuanming Chen, Shouxu Wang, Xuemei He, Wei He, Vadim V. Silberschmidt and Ze Tan

– The purpose of this paper is to form copper coin-embedded printed circuit board (PCB) for high heat dissipation.

2358

Abstract

Purpose

The purpose of this paper is to form copper coin-embedded printed circuit board (PCB) for high heat dissipation.

Design/methodology/approach

Manufacturing optimization of copper coin-embedded PCB involved in the design and treatment of copper coin, resin flush removal and flatness control. Thermal simulation was used to investigate the effect of copper coin on heat dissipation of PCB products. Lead-free reflow soldering and thrust tests were used to characterize the reliable performance of copper coin-embedded PCB.

Findings

The copper coin-embedded PCB had good agreement with resin flush removal and flatness control. Thermal simulation results indicated that copper coin could significantly enhance the heat-dissipation rate by means of a direct contact with the high-power integrated circuit chip. The copper coin-embedded PCB exhibited a reliable structure capable of withstanding high-temperature reflow soldering and high thrust testing.

Originality/value

The use of a copper coin-embedded PCB could lead to higher heat dissipation for the stable performance of high-power electronic components. The copper coin-embedded method could have important potential for improving the design for heat dissipation in the PCB industry.

Details

Circuit World, vol. 41 no. 2
Type: Research Article
ISSN: 0305-6120

Keywords

Article
Publication date: 19 October 2012

Ujjwal R. Bharadwaj, Vadim V. Silberschmidt and John B. Wintle

Inspection and maintenance of plant and machinery has traditionally been based on prescriptive industry practices. However, increased experience and a greater understanding of…

2162

Abstract

Purpose

Inspection and maintenance of plant and machinery has traditionally been based on prescriptive industry practices. However, increased experience and a greater understanding of operational hazards is leading sections of industry to take a more informed approach to planning inspection and maintenance, targeting resources to reduce the risk to as low as reasonably practicable. The purpose of this paper is to present an approach to asset management to minimize risks in the most cost effective way.

Design/methodology/approach

The approach shown optimizes run‐repair‐replace decision‐making in the integrity management of assets with the ultimate aim of maximising the impact of money spent on risk mitigation actions. The risk‐based approach, as opposed to the more conventional approaches, assesses failure in its wider context by considering not just the likelihood of failure, but also the consequences should the failure event occur.

Findings

The risk‐based methodology presents a cost‐effective way to minimise life cycle costs in the management of assets whilst maintaining reliability or availability targets, and operating within safety and environmental regulation.

Practical implications

In this paper, for demonstration, a wind turbine system consisting of a number of components including structural components is used. However, the methodology can be extended to any system in which components can be analyzed to provide the required inputs to the risk model.

Originality/value

At a time when competitive pressures force asset managers to prioritize their maintenance, the risk‐based methodology presented here is a rational, efficient and somewhat flexible way to asset integrity management.

Details

Journal of Quality in Maintenance Engineering, vol. 18 no. 4
Type: Research Article
ISSN: 1355-2511

Keywords

Article
Publication date: 16 November 2020

Riaz Muhammad and Umair Ali

This paper aims to analyze the effect of cerium addition on the microstructure and the mechanical properties of Tin-Silver-Copper (SAC) alloy. The mechanical properties and…

Abstract

Purpose

This paper aims to analyze the effect of cerium addition on the microstructure and the mechanical properties of Tin-Silver-Copper (SAC) alloy. The mechanical properties and refined microstructure of a solder joint are vital for the reliability and performance of electronics. SAC305 alloys are potential choices to use as lead-free solders because of their good properties as compared to the conventional Tin-Lead solder alloys. However, the presence of bulk intermetallic compounds (IMCs) in the microstructure of SAC305 alloys affects their overall performance. Therefore, addition of cerium restrains the growth of IMCs and refines the microstructure, hence improving the mechanical performance.

Design/methodology/approach

SAC305 alloy is doped with various composition of xCerium (x = 0.15, 0.35, 0.55, 0.75, 0.95) % by weight. Pure elements in powdered form were melted in the presence of argon with periodic stirring to ensure a uniform melted alloy. The molten alloy is then poured into a pre-heated die to obtain a tensile specimen. The yield strength and universal tensile strength were determined using a fixed strain rate of 10 mm per minute or 0.1667 mm s^(−1). The IMCs are identified using X-ray diffraction, whereas the elemental phase composition and microstructure evolution are, respectively, examined by using electron dispersive spectroscopy and scanning electron microscopy.

Findings

Improvement in the microstructure and mechanical properties is observed with 0.15% of cerium additions. The tensile test also showed that SAC305-0.15% cerium exhibits more stress-bearing capacity than other compositions. The 0.75% cerium doped alloy indicated some improvement because of a decrease in fracture dislocation regions, but microstructure refinement and the arrangement of IMCs are not those of 0.15% Ce. Different phases of Cu_6 Sn_5, Ag_3 Sn and CeSn_3 and ß-Sn are identified. Therefore, the addition of cerium in lower concentrations and presence of Ce-Sn IMCs improved the grain boundary structure and resulted refinement in the microstructure of the alloy, as well as an enhancement in the mechanical properties.

Originality/value

Characterization of microstructure and evaluation of mechanical properties are carried out to investigate the different composition of SAC305-xCerium alloys. Finally, an optimized cerium composition is selected for solder joint in electronics.

Details

Soldering & Surface Mount Technology, vol. 33 no. 4
Type: Research Article
ISSN: 0954-0911

Keywords

Article
Publication date: 6 September 2021

Y.J. Liu, Z.H. Wang and H.M. Wen

The purpose of this paper is to predict the response and perforation of fibre metal laminates (FMLs) subjected to impact by projectiles at different velocities.

Abstract

Purpose

The purpose of this paper is to predict the response and perforation of fibre metal laminates (FMLs) subjected to impact by projectiles at different velocities.

Design/methodology/approach

A finite element (FE) model is constructed in which recently proposed dynamic constitutive models for fibre reinforced plastic (FRP) laminates and metals are used. Moreover, a recently developed dynamic cohesive element constitutive model is also used to simulate the debonding between FRP laminates and metal sheets. The FE model is first validated against the test data for glass laminate aluminum reinforced epoxy (GLARE) both under dropped object loading and ballistic impact, then used to perform a parametric study on the influence of projectile nose shape on the perforation of FMLs.

Findings

It is found that the present model predicts well the response and perforation of GLARE subjected to impact loading in terms of load-time history, load-displacement curve, residual velocity and failure pattern. It is also found that projectile nose shape has a considerable effect on the perforation of GLARE FMLs and that the ballistic limit is the highest for a flat-ended projectile whilst for a conical-nosed missile the resistance to perforation is the least.

Originality/value

Recently developed constitutive models for FRPs and metals, together with cohesive element model which considers strain rate effect, are used in the FE model to predict the behaviour of FMLs struck by projectiles in a wider range of impact velocities; the present model is advantageous over such existing models as Johnson-Cook (JC) + Chang-Chang and JC (+BW) + MAT162 in terms of failure pattern though they produce similar results for residual velocity.

Details

Aircraft Engineering and Aerospace Technology, vol. 94 no. 2
Type: Research Article
ISSN: 1748-8842

Keywords

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