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Article

J.G. Lee and K.N. Subramanian

To determine the role of microstructure in the creep and thermomechanical fatigue (TMF) properties of solder joints made with eutectic Sn‐Ag solder, and Sn‐Ag solder with…

Abstract

Purpose

To determine the role of microstructure in the creep and thermomechanical fatigue (TMF) properties of solder joints made with eutectic Sn‐Ag solder, and Sn‐Ag solder with Cu and/or Ni additions.

Design/methodology/approach

Quaternary alloys containing small amounts of Cu and Ni exhibit better high temperature creep resistance and also better resistance to damage under TMF cycles with a longer dwell time at the high temperature extreme, than eutectic Sn‐Ag, and Sn‐Ag‐Cu ternary alloy solder joints. Microstructural evaluation was conducted to investigate the effects of Ni additions to Sn‐Ag‐based solder joints.

Findings

Microstructural studies of the quaternary solder alloys revealed the presence of small ternary Cu‐Ni‐Sn intermetallic compound particles at Sn‐Sn grain boundaries. These precipitates can retard the grain boundary sliding that will occur during TMF with longer dwell times at the high temperature extreme, and during high temperature creep.

Originality/value

The findings of this paper will help to provide an understanding of the effects of alloying elements on Sn‐Ag based solder joints.

Details

Soldering & Surface Mount Technology, vol. 17 no. 1
Type: Research Article
ISSN: 0954-0911

Keywords

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Article

H. Rhee and K.N. Subramanian

To understand the roles of service‐related parameters, such as imposed cyclic strain amplitude and cyclic strain rate, on the stress relaxation behaviour of eutectic Sn‐Ag…

Abstract

Purpose

To understand the roles of service‐related parameters, such as imposed cyclic strain amplitude and cyclic strain rate, on the stress relaxation behaviour of eutectic Sn‐Ag solder joints.

Design/methodology/approach

Cyclic shear straining with associated stress relaxation at the shear strain extremes imposed was carried out on pre‐strained eutectic Sn‐Ag solder joints with various cyclic shear straining conditions. Results from such experiments were compared with previously reported findings from monotonic shear straining and stress relaxation tests.

Findings

At higher testing temperatures with a larger cyclic strain amplitude, stress states realized at the subsequent cycle are comparable with, or even gradually increase on, those experienced at the previous cycle, especially after few cycles. The maximum shear stress obtained at each cycle and residual stress during stress relaxation are strongly affected by cyclic strain rate. Stress relaxation during subsequent cycles of straining was found to be strongly dependent on the test temperature, and the imposed cyclic strain amplitude and cyclic strain rate.

Originality/value

In this paper, the experiments were carried out on eutectic Sn‐Ag solder joints with about a 100 μm joint thickness, which are, therefore, representative of those used in microelectronics. Also, there is no systematic study reporting the effects of cyclic straining conditions on the stress relaxation behaviour of eutectic Sn‐Ag solder for this joint configuration in the published literature.

Details

Soldering & Surface Mount Technology, vol. 18 no. 1
Type: Research Article
ISSN: 0954-0911

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Article

F. Guo, J. Lee and K.N. Subramanian

In an attempt to improve service life of lead‐free Sn‐based electronic solder joints, compatible reinforcements were introduced by in‐situ and mechanical mixing methods…

Abstract

In an attempt to improve service life of lead‐free Sn‐based electronic solder joints, compatible reinforcements were introduced by in‐situ and mechanical mixing methods. The reinforcements affect the steady‐state creep rate and the strain for the onset of tertiary creep of the solder joints. However, neither of these parameters, when considered alone, can be used for evaluating the reliability of solder joints. The Larson‐Miller parameter, and a new parameter proposed in the paper, can incorporate test parameters to arrive at a reliability prediction methodology. The role of these reinforcements in homogenising creep strain within the joint is analysed. The observed creep behaviour of these composite solders is discussed on the basis of interfacial bonding strength between the reinforcement and the solder matrix.

Details

Soldering & Surface Mount Technology, vol. 15 no. 1
Type: Research Article
ISSN: 0954-0911

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Article

H. Rhee, K.N. Subramanian, A. Lee and J.G. Lee

Deformation studies on eutectic Sn‐Ag solder (Sn‐3.5Ag in wt percent) joints were carried out at a range of temperatures using a rheometric solids analyzer (RSA‐III)…

Abstract

Deformation studies on eutectic Sn‐Ag solder (Sn‐3.5Ag in wt percent) joints were carried out at a range of temperatures using a rheometric solids analyzer (RSA‐III). Various performance parameters were evaluated with this equipment by subjecting geometrically realistic solder joints to shear loading at various temperatures (25, 75, 100, 125, and 150°C) with a nominal joint thickness of ∼100 μm and 1×1 mm solder joint area. Mechanical properties such as shear stress versus simple shear‐strain relationships, peak shear stress as a function of rate of simple shear‐strain and testing temperature, and creep parameters were evaluated to gain a better understanding of the parameters contributing to thermomechanical fatigue.

Details

Soldering & Surface Mount Technology, vol. 15 no. 3
Type: Research Article
ISSN: 0954-0911

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Article

Jan Patrick Deckers, Khuram Shahzad, Ludwig Cardon, Marleen Rombouts, Jozef Vleugels and Jean-Pierre Kruth

The purpose of this paper is to compare different powder metallurgy (PM) processes to produce ceramic parts through additive manufacturing (AM). This creates the potential…

Abstract

Purpose

The purpose of this paper is to compare different powder metallurgy (PM) processes to produce ceramic parts through additive manufacturing (AM). This creates the potential to rapidly shape ceramic parts with an almost unlimited shape freedom. In this paper, alumina (Al2O3) parts are produced, as Al2O3 is currently the most commonly used ceramic material for technical applications.

Design/methodology/approach

Variants of the following PM route, with indirect selective laser sintering (indirect SLS) as the AM shaping step, are explored to produce ceramic parts: powder synthesis, indirect SLS, binder removal and furnace sintering and alternative densification steps.

Findings

Freeform-shaped Al2O3 parts with densities up to approximately 90 per cent are obtained.

Research limitations/implications

The resulting Al2O3 parts contain inter-agglomerate pores. To produce higher-quality ceramic parts through indirect SLS, these pores should be avoided or eliminated.

Originality/value

The research is innovative in many ways. First, composite powders are produced using different powder production methods, such as temperature-induced phase separation and dispersion polymerization. Second, four different binder materials are investigated: polyamide (nylon-12), polystyrene, polypropylene and a carnauba wax – low-density polyethylene combination. Further, to produce ceramic parts with increased density, the following densification techniques are investigated as additional steps of the PM process: laser remelting, isostatic pressing and infiltration.

Details

Rapid Prototyping Journal, vol. 22 no. 3
Type: Research Article
ISSN: 1355-2546

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Article

Dirk C. Moosmayer, Muhammad Dan-Asabe Abdulrahman, Nachiappan Subramanian and Lars Bergkvist

Remanufacturing is the only end-of-life (EOL) treatment process that results in as-new functional and aesthetic quality and warranty. However, applying mental model…

Abstract

Purpose

Remanufacturing is the only end-of-life (EOL) treatment process that results in as-new functional and aesthetic quality and warranty. However, applying mental model theory, the purpose of this paper is to argue that the conception of remanufacturing as an EOL process activates an operational mental model (OMM) that connects to resource reuse, environmental concern and cost savings and is thus opposed to a strategic mental model (SMM) that associates remanufacturing with quality improvements and potential price increases.

Design/methodology/approach

The authors support the argument by empirically assessing consumers’ multi-attribute decision process for cars with remanufactured or new engines among 202 car buyers in China. The authors conduct a conjoint analysis and use the results as input to simulate market shares for various markets on which these cars compete.

Findings

The results suggest that consumers on average attribute reduced utility to remanufactured engines, thus in line with the OMM. However, the authors identify a segment accounting for about 30 per cent of the market with preference for remanufactured engines. The fact that this segment has reduced environmental concern supports the SMM idea that remanufactured products can be bought for their quality.

Research limitations/implications

A single-country (China) single-brand (Volkswagen) study is used to support the conceptualised mental models. While this strengthens the internal validity of the results, future research could improve the external validity by using more representative sampling in a wider array of empirical contexts. Moreover, future work could test the theory more explicitly.

Practical implications

By selling cars with remanufactured engines to customers with a SMM that values the at least equal performance of remanufactured products, firms can enhance their profit from remanufactured products. In addition, promoting SMM enables sustainable business models for the sharing economy.

Originality/value

As a community, the authors need to more effectively reflect on shaping mental models that disconnect remanufacturing from analogies that convey inferior quality and performance associations. Firms can overcome reduced utility perceptions not only by providing discounts, i.e. sharing the economic benefits of remanufacturing, but even more by increasing the warranty, thus sharing remanufacturing’s performance benefit and reducing consumers’ risk, a mechanism widely acknowledged in product diffusion but neglected in remanufacturing so far.

Details

International Journal of Operations & Production Management, vol. 40 no. 2
Type: Research Article
ISSN: 0144-3577

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Article

J.G. Lee, F. Guo, K.N. Subramanian and J.P. Lucas

The influence of the thermal reflow profile on the formation and resultant morphology of the intermetallic layer that developed at the Ni particle reinforcements within an…

Abstract

The influence of the thermal reflow profile on the formation and resultant morphology of the intermetallic layer that developed at the Ni particle reinforcements within an eutectic Sn‐Ag composite solder matrix was investigated. The composite solder was fabricated by mechanically dispersing 15 vol% Ni particles into eutectic Sn‐3.5Ag solder paste. Two distinct intermetallic compound (IMC) morphological microstructures were observed around the Ni reinforcements. IMC morphological microstructure apparently varied depending on the amount of heat input and differences in heating rates used in the reflow profile. A “sunflower” IMC morphology was typically noted when the total amount of heat input was small. However, with sufficient heat input, a faceted “blocky” IMC morphology was consistently achieved. Multiple‐reflow thermal profiling experiments were conducted to measure and compare the amount of heat input necessary to change the sunflower IMC morphology around Ni particle reinforcements to the blocky morphology.

Details

Soldering & Surface Mount Technology, vol. 14 no. 2
Type: Research Article
ISSN: 0954-0911

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Article

Chung-Yung Lin

This paper aims to derive a model of growth kinetics of the intermetallic compound (IMC) layer formed in the reaction between liquid Sn-based solders and Ni particle…

Abstract

Purpose

This paper aims to derive a model of growth kinetics of the intermetallic compound (IMC) layer formed in the reaction between liquid Sn-based solders and Ni particle reinforcements and to compare with the experimental data to verify the effects of Sn concentration and alloying element.

Design/methodology/approach

A composite solder was manufactured by mechanically introducing Ni particle reinforcements into a solder matrix. The effect of the non-reactive alloying elements, Ag, Pb and Bi, on the growth kinetics of the IMC formed between liquid Sn-based eutectic solders and Ni particles, reacting this composite solder at 250°C–280°C was studied.

Findings

Experimental results showed that only the IMC Ni3Sn4 was present as a reaction product. Using the diffusion-controlled reaction mechanism, a kinetic equation quantifying both Sn concentration and alloying element effects was derived and verified by comparing the kinetic data obtained using four different solders with different concentrations of Sn and the alloying elements.

Originality/value

The similarity between the activation energies of these four solders confirms that the diffusion of Sn atoms through the IMC is the rate-controlling step. Besides, the kinetic values are independent of the geometry of Ni, whether spherical particle or flat substrate.

Details

Soldering & Surface Mount Technology, vol. ahead-of-print no. ahead-of-print
Type: Research Article
ISSN: 0954-0911

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Article

Neal K. Vail, Badrinarayan Balasubramanian, Joel W. Barlow and Harris L. Marcus

Reports that measurable amounts of polymer degradation occur during the fabrication of objects from polymer coated ceramic powders by selective laser sintering (SLS)…

Abstract

Reports that measurable amounts of polymer degradation occur during the fabrication of objects from polymer coated ceramic powders by selective laser sintering (SLS). Argues that because the binder is important in achieving strong green parts that can be handled with minimal breakage during post‐processing operations, it is essential to minimize the extent of binder losses. As the first step towards understanding the mechanisms of binder degradation, this paper presents a thermal model of the physical system, noting that the agreement between theory and experiment are good. The model is used to help determine the most influential parameters affecting binder losses during fabrication from polymer coated powders. Predicts that adjustments to laser beam diameter, laser scanning distance and gaseous environment will strongly affect polymer binder degradation during processing. Further predicts correctly that polymer degradation during SLS processing is not sensitive to the inherent degradation kinetics of the polymer.

Details

Rapid Prototyping Journal, vol. 2 no. 3
Type: Research Article
ISSN: 1355-2546

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Article

Izhan Abdullah, Muhammad Nubli Zulkifli, Azman Jalar and Roslina Ismail

The purpose of this paper is to investigate the relationship between microstructure and varied strain rates towards the mechanical properties and deformation behaviour of…

Abstract

Purpose

The purpose of this paper is to investigate the relationship between microstructure and varied strain rates towards the mechanical properties and deformation behaviour of Sn-3.0Ag-0.5Cu (SAC305) lead-free solder wire at room temperature.

Design/methodology/approach

Tensile tests with different strain rates of 1.5 × 10−6, 1.5 × 10−5, 1.5 × 10−4, 1.5 × 10−3, 1.5 × 10−2 and 1.5 × 10−1 s−1 at room temperature of 25°C were carried out on lead-free Sn-3.0Ag-0.5Cu (SAC305) solder wire. Stress-strain curves and mechanical properties such as yield strength, ultimate tensile strength and elongation were determined from the tensile tests. A microstructure analysis was performed by measuring the average grain size and the aspect ratio of the grains.

Findings

It was observed that higher strain rates showed pronounced dynamic recrystallization on the stress-strain curve. The increase in the strain rates also decreased the grain size of the SAC305 solder wire. It was found that higher strain rates had a pronounced effect on changing the deformation or shape of the grain in a longitudinal direction. An increase in the strain rates increased the tensile strength and ductility of the SAC solder wire. The primary deformation mechanism for strain rates below 1.5 × 10−1 s−1 was grain boundary sliding, whereas the deformation mechanism for strain rates of 1.5 × 10−1 s−1 was diffusional creep.

Originality/value

Most of the studies regarding the deformation behaviour of lead-free solder usually consider the effect of the elevated temperature. For the current analysis, the effect of the temperature is kept constant at room temperature to analyze the deformation of lead-free solder wire solely because of changes of strain rates, and this is the originality of this paper.

Details

Soldering & Surface Mount Technology, vol. 29 no. 2
Type: Research Article
ISSN: 0954-0911

Keywords

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