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Article
Publication date: 1 February 1994

C. Melton

A quantitative dynamic solder wettability measurement was used to evaluate the effects of reflow processing on the wettability parameters associated with two non‐lead…

Abstract

A quantitative dynamic solder wettability measurement was used to evaluate the effects of reflow processing on the wettability parameters associated with two non‐lead bearing solders, 96.5% Sn/3.5% Ag and 58% Bi/42% Sn. An experimental design approach employing full factorial experiments was formulated to investigate the solder wetting dependence of the reflow parameters: atmosphere, peak reflow temperature, time above liquidus and metallisation. Solder wettability was determined with respect to the final degree of spread and the extent of solder wetting onto the lands of surface mount components. The solder alloy composition of 96.5% Sn/3.5% Ag was found to exhibit better wetting characteristics than the 58% Bi/42% Sn alloy. This wetting behaviour was enhanced under the reflow conditions of a nitrogen atmosphere and the use of a gold metallisation. The wetting of the conventional 63% Sn/37% Pb solder alloy was improved over the comparatively processed 58% Bi/42% Sn alloy. However, the 63% Sn/37% Pb solder alloy displayed a greater sensitivity to reflow atmosphere than the 96.5% Sn/3.5% Ag alloy, which generally exhibited better wetting characteristics than the Sn/Pb alloy.

Details

Soldering & Surface Mount Technology, vol. 6 no. 2
Type: Research Article
ISSN: 0954-0911

Article
Publication date: 4 April 2022

Lina Syazwana Kamaruzzaman and Yingxin Goh

This paper aims to review recent reports on mechanical properties of Sn-Bi and Sn-Bi-X solders (where X is an additional alloying element), in terms of the tensile…

Abstract

Purpose

This paper aims to review recent reports on mechanical properties of Sn-Bi and Sn-Bi-X solders (where X is an additional alloying element), in terms of the tensile properties, hardness and shear strength. Then, the effects of alloying in Sn-Bi solder are compared in terms of the discussed mechanical properties. The fracture morphologies of tensile shear tested solders are also reviewed to correlate the microstructural changes with mechanical properties of Sn-Bi-X solder alloys.

Design/methodology/approach

A brief introduction on Sn-Bi solder and reasons to enhance the mechanical properties of Sn-Bi solder. The latest reports on Sn-Bi and Sn-Bi-X solders are combined in the form of tables and figures for each section. The presented data are discussed by comparing the testing method, technical setup, specimen dimension and alloying element weight percentage, which affect the mechanical properties of Sn-Bi solder.

Findings

The addition of alloying elements could enhance the tensile properties, hardness and/or shear strength of Sn-Bi solder for low-temperature solder application. Different weight percentage alloying elements affect differently on Sn-Bi solder mechanical properties.

Originality/value

This paper provides a compilation of latest report on tensile properties, hardness, shear strength and deformation of Sn-Bi and Sn-Bi-X solders and the latest trends and in-depth understanding of the effect of alloying elements in Sn-Bi solder mechanical properties.

Details

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

Keywords

Article
Publication date: 22 February 2022

Rizk Mostafa Shalaby

This study aims to summarize the effects of minor addition of Ho REE on the structure, mechanical strength and thermal stability of binary Sn- Ag solder alloys for…

Abstract

Purpose

This study aims to summarize the effects of minor addition of Ho REE on the structure, mechanical strength and thermal stability of binary Sn- Ag solder alloys for high-performance applications.

Design/methodology/approach

This study investigates the effect of a small amount of holmium addition on the microstructure, thermal stability, mechanical behaviour and wettability of environmentally friendly eutectic melt-spun process Sn – Ag solder alloys. Dynamic resonance technique, X-ray diffraction (XRD) and scanning electron microscopy were carried to study stiffness, identification of the phases and the morphology features of the solder. Structure and microstructure analysis indicated that presence of rhombohedral ß-Sn phase in addition to orthorhombic IMC Ag3Sn phase dispersed in Sn-matrix. Also, the results showed that Ho rare earth addition at a small trace amount into Sn-Ag system reduces and improves the particle size of both rhombohedral ß-Sn and orthorhombic IMC Ag3Sn based on the adsorption effect of the active RE element. The adsorption of Ho at grain boundaries resulted in Ag3Sn more uniform needle-like which is distributed in the ß-Sn matrix. The fine and uniform microstructure leads to improvement of mechanical strength. The microstructure refinement is due to the high surface free energy of IMC Ag3Sn grains, and it prevents the dislocation slipping. This maybe enhance the micro-hardness and micro-creep hence delays the breaking point of the solder. Ho (RE) trace addition could enhance the melting temperature and contact angle up to 215°C and 31°, Respectively, compared with plain solder. All results showed that Ho trace addition element has an effective method to enhance new solder joints.

Findings

Effect of rare earth element Ho particles on the microstructure and mechanical behavior of eutectic Sn-3.5Ag solder alloy was studied. Some important conclusions are summarized in the following: microstructure investigations revealed that the addition of Ho particles to eutectic Sn-3.5Ag inhibited in reducing and refines the crystallite size as well as the Ag3Sn IMC which reinforced the strength of plain solder alloy. The mechanical properties values such as Young’s modulus, Vickers microhardness of Sn-3.5Ag solder alloy can be significantly improved by adding a trace amount of Ho particles compared with plain solder due to the existence of finer and higher volume fraction of Ag3SnIMC. These variations can be understood by considering the plastic deformation. The strengthening mechanism of the Sn-3.5Ag-Ho solder alloy could be explained in terms of Ho harden particles and finer IMC, which are distributed within eutectic regions because they act as pinning centres which inhibited the mobility of dislocation that concentrated around the grain boundaries. The results show that the best creep resistance is obtained when the addition of Ho 0.5 is compared to plain solder. The addition of Ho on Sn-3.5Ag lead-free solder alloy decreases the melting temperature to few degrees.

Originality/value

Development of holmium-doped eutectic Sn-Ag lead-free solder for electronic packaging.

Article
Publication date: 7 January 2022

Madhuri Chandrashekhar Deshpande, Rajesh Chaudhari, Ramesh Narayanan and Harishwar Kale

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

Abstract

Purpose

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

Design/methodology/approach

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.

Findings

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

Originality/value

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.

Details

Soldering & Surface Mount Technology, vol. 34 no. 4
Type: Research Article
ISSN: 0954-0911

Keywords

Article
Publication date: 10 August 2018

Md Hasnine

This paper aims to investigate the effect of In and Sb additions on the thermal behavior and wettability of Sn-3.5Ag-xIn-ySb (x = 0, 1.0 and 1.5 Wt.%, y = 0, 1.0, 1.4 and…

Abstract

Purpose

This paper aims to investigate the effect of In and Sb additions on the thermal behavior and wettability of Sn-3.5Ag-xIn-ySb (x = 0, 1.0 and 1.5 Wt.%, y = 0, 1.0, 1.4 and 2.1 Wt.%) solder alloys.

Design/methodology/approach

The thermal behavior of the Pb-free solder alloys was studied using differential scanning calorimetry. Wetting balance experiments were performed in accordance with the IPC standard, IPC-TM-650 and at a temperature of 260°C. Also, a solder spread test was performed on a Cu surface finish using the JIS-Z-3197 solderability standard.

Findings

It is shown that among the selected Sn-3.5Ag-xIn-ySb (x = 0, 1.0 and 1.5 Wt.%, y = 0, 1.0, 1.4 and 2.1 Wt.%) alloys, Sn-3.5Ag-1.5In-1Sb showed the lowest melting point and the lowest undercooling temperature. The best wettability was achieved when the In and Sb contents were approximately 1.5 and 1.0 Wt.%, respectively. The effect of the combined addition of In and Sb on solder spreadability on a Cu substrate was also demonstrated.

Originality/value

It was found that adding approximately 1.5 and 1.0 Wt.% of In and Sb, respectively, in Sn-3.5Ag solder provided the best wetting performance and improved the solder spreadability.

Details

Soldering & Surface Mount Technology, vol. 30 no. 4
Type: Research Article
ISSN: 0954-0911

Keywords

Article
Publication date: 7 February 2020

Min Wu and Bailin Lv

Viscosity is an important basic physical property of liquid solders. However, because of the very complex nonlinear relationship between the viscosity of the liquid…

Abstract

Purpose

Viscosity is an important basic physical property of liquid solders. However, because of the very complex nonlinear relationship between the viscosity of the liquid ternary Sn-based lead-free solder and its determinants, a theoretical model for the viscosity of the liquid Sn-based solder alloy has not been proposed. This paper aims to address the viscosity issues that must be considered when developing new lead-free solders.

Design/methodology/approach

A BP neural network model was established to predict the viscosity of the liquid alloy and the predicted values were compared with the corresponding experimental data in the literature data. At the same time, the BP neural network model is compared with the existing theoretical model. In addition, a mathematical model for estimating the melt viscosity of ternary tin-based lead-free solders was constructed using a polynomial fitting method.

Findings

A reasonable BP neural network model was established to predict the melt viscosity of ternary tin-based lead-free solders. The viscosity prediction of the BP neural network agrees well with the experimental results. Compared to the Seetharaman and the Moelwyn–Hughes models, the BP neural network model can predict the viscosity of liquid alloys without the need to calculate the relevant thermodynamic parameters. In addition, a simple equation for estimating the melt viscosity of a ternary tin-based lead-free solder has been proposed.

Originality/value

The study identified nine factors that affect the melt viscosity of ternary tin-based lead-free solders and used these factors as input parameters for BP neural network models. The BP neural network model is more convenient because it does not require the calculation of relevant thermodynamic parameters. In addition, a mathematical model for estimating the viscosity of a ternary Sn-based lead-free solder alloy has been proposed. The overall research shows that the BP neural network model can be well applied to the theoretical study of the viscosity of liquid solder alloys. Using a constructed BP neural network to predict the viscosity of a lead-free solder melt helps to study the liquid physical properties of lead-free solders that are widely used in electronic information.

Details

Soldering & Surface Mount Technology, vol. 32 no. 3
Type: Research Article
ISSN: 0954-0911

Keywords

Article
Publication date: 13 April 2010

Liang Zhang, Song-bai Xue, Li-li Gao, Yan Chen, Sheng-lin Yu, Zhong Sheng and Guang Zeng

The purpose of this paper is to investigate the effects of minor addition of the rare earth (RE) element cerium, Ce, on the microstructures and creep properties of…

Abstract

Purpose

The purpose of this paper is to investigate the effects of minor addition of the rare earth (RE) element cerium, Ce, on the microstructures and creep properties of Sn-Ag-Cu solder alloys.

Design/methodology/approach

The pure Sn, Sn-Cu alloy, Sn-Ag alloy and Cu-Ce alloy were used as raw materials. Sn-Ag-Cu alloys with different contents of RE Ce were chosen to compare with Sn-Ag-Cu. The raw materials of Sn, Sn-Cu alloy, Sn-Ag alloy, Cu-Ce alloy were melted in a ceramic crucible, and were melted at 550°C ± 1°C for 40 minutes. To homogenize the solder alloy, mechanical stirring was performed every ten minutes using a glass rod. During the melting, KC1 + LiCI (1.3:1), were used over the surface of liquid solder to prevent oxidation. The melted solder was chill cast into a rod.

Findings

It is found that the microstructure exhibits smaller grains and the Ag3Sn/Cu6Sn5 intermetallic compound (IMC) phases are modified in matrix with the addition of Ce. In particular, the addition of 0.03 wt.% Ce to the Sn-Ag-Cu solder can refine the microstructures and decrease the thickness of the IMC layers of Sn-Ag-Cu solder alloys. Meanwhile, thermodynamic analysis showed that these phenomena could be attributed to the reduction of the driving force for Cu-Sn IMC formation due to the addition of Ce. Results calculated using the thermodynamic method are close to the above experimental data. Thus, the optimum content of Ce in Sn-Ag-Cu solder alloys should be about 0.030 percent. Additionally, the effect of Ce on the creep rupture life of Sn-Ag-Cu soldered joints was studied. It was found that the creep rupture life may be increased up to 7.5 times more than that of the original Sn-Ag-Cu alloy, when Ce accounts for 0.030 percent.

Originality/value

This paper usefully investigates the effects of the RE cerium (Ce), on the microstructures and creep properties of Sn-Ag-Cu solder alloys, optimizing the quantity of Ce in the Sn-Ag-Cu solder alloy through a thermodynamic method and by creep-rupture life testing.

Details

Soldering & Surface Mount Technology, vol. 22 no. 2
Type: Research Article
ISSN: 0954-0911

Keywords

Article
Publication date: 27 May 2014

Ervina Efzan Mhd Noor and Amares Singh

The aim of the present study was to gather and review all the important properties of the Sn–Ag–Cu (SAC) solder alloy. The SAC solder alloy has been proposed as the…

Abstract

Purpose

The aim of the present study was to gather and review all the important properties of the Sn–Ag–Cu (SAC) solder alloy. The SAC solder alloy has been proposed as the alternative solder to overcome the environmental concern of lead (Pb) solder. Many researchers have studied the SAC solder alloy and found that the properties such as melting temperature, wettability, microstructure and interfacial, together with mechanical properties, are better for the SAC solder than the tin – lead (SnPb) solders. Meanwhile, addition of various elements and nanoparticles seems to produce enhancement on the prior bulk solder alloy as well. These benefits suggest that the SAC solder alloy could be the next alternative solder for the electronic packaging industry. Although many studies have been conducted for this particular solder alloy, a compilation of all these properties regarding the SAC solder alloy is still not available for a review to say.

Design/methodology/approach

Soldering is identified as the metallurgical joining method in electronic packaging industry which uses filler metal, or well known as the solder, with a melting point < 425°C (Yoon et al., 2009; Ervina and Marini, 2012). The SAC solder has been developed by many methods and even alloying it with some elements to enhance its properties (Law et al., 2006; Tsao et al., 2010; Wang et al., 2002; Gain et al., 2011). The development toward miniaturization, meanwhile, requires much smaller solder joints and fine-pitch interconnections for microelectronic packaging in electronic devices which demand better solder joint reliability of SAC solder Although many studies have been done based on the SAC solder, a review based on the important characteristics and the fundamental factor involving the SAC solder is still not sufficient. Henceforth, this paper resolves in stating all its important properties based on the SAC solder including its alloying of elements and nanoparticles addition for further understanding.

Findings

Various Pb-free solders have been studied and investigated to overcome the health and environmental concern of the SnPb solder. In terms of the melting temperature, the SAC solder seems to possess a high melting temperature of 227°C than the Pb solder SnPb. Here, the melting temperature of this solder falls within the range of the average reflow temperature in the electronic packaging industry and would not really affect the process of connection. A good amendment here is, this melting temperature can actually be reduced by adding some element such as titanium and zinc. The addition of these elements tends to decrease the melting temperature of the SAC solder alloy to about 3°C. Adding nanoparticles, meanwhile, tend to increase the melting temperature slightly; nonetheless, this increment was not seemed to damage other devices due to the very slight increment and no drastic changes in the solidification temperature. Henceforth, this paper reviews all the properties of the Pb-free SAC solder system by how it is developed from overcoming environmental problem to achieving and sustaining as the viable candidate in the electronic packaging industry. The Pb-free SAC solder can be the alternative to all drawbacks that the traditional SnPb solder possesses and also an upcoming new invention for the future needs. Although many studies have been done in this particular solder, not much information is gathered in a review to give better understanding for SAC solder alloy. In that, this paper reviews and gathers the importance of this SAC solder in the electronic packaging industry and provides information for better knowledge.

Originality/value

This paper resolves in stating of all its important properties based on the SAC solder including its alloying of elements and nanoparticles addition for further understanding.

Details

Soldering & Surface Mount Technology, vol. 26 no. 3
Type: Research Article
ISSN: 0954-0911

Keywords

Article
Publication date: 14 September 2012

Dhafer Abdul Ameer Shnawah, Suhana Binti Mohd Said, Mohd Faizul Bin Mohd Sabri, Irfan Anjum Badruddin and Fa Xing Che

The purpose of this paper is to investigate the effects of small additions (0.1 and 0.3 wt%) of Fe on the bulk alloy microstructure and tensile properties of low…

Abstract

Purpose

The purpose of this paper is to investigate the effects of small additions (0.1 and 0.3 wt%) of Fe on the bulk alloy microstructure and tensile properties of low Ag‐content Sn‐1Ag‐0.5Cu lead‐free solder alloy.

Design/methodology/approach

Sn‐1Ag‐0.5Cu, Sn‐3Ag‐0.5Cu and Sn‐1Ag‐0.5Cu containing 1 and 3 wt.% Fe solder specimens were prepared by melting pure ingots of Sn, Ag, Cu and Fe in an induction furnace and subsequently remelting and casting to form flat dog‐bone shaped specimens for tensile testing. The solder specimens were subjected to tensile testing using an INSTRON tester with a loading rate 10‐3 s‐1. To obtain the microstructure, the solder samples were prepared by dicing, molding, grinding and polishing processes. The microstructural analysis was carried out using scanning electron microscopy/Energy Dispersive X‐ray spectroscopy. Electron backscatter diffraction (EBSD) analysis was used to identify the IMC phases.

Findings

In addition to large primary β‐Sn grains, the addition of Fe to the SAC105 alloy formed large circular shaped FeSn2 IMC particles located in the eutectic regions. This had a significant effect in reducing the elastic modulus and yield strength and maintaining the elongation at the SAC105 level. Moreover, the additions of Fe resulted in the inclusion of Fe in the Ag3Sn and Cu6Sn5 IMC particles. The additions of Fe did not have any significant effect on the melting behaviour.

Research limitations/implications

The paper provides a starting‐point for studying the effect of minor additions of Fe on the drop impact and thermal cycling reliability of SAC105 alloy considering the bulk alloy microstructure and tensile properties. Further investigations should be undertaken in the future.

Originality/value

The effect of Fe addition on the bulk alloy microstructure and tensile properties of the SAC105 alloy has been studied for the first time. Fe‐containing SAC105 alloy may have the potential to increase the drop impact and thermal cycling reliability compared with the standard SAC105 alloy.

Details

Soldering & Surface Mount Technology, vol. 24 no. 4
Type: Research Article
ISSN: 0954-0911

Keywords

Article
Publication date: 20 January 2012

Dhafer Abdul Ameer Shnawah, Mohd Faizul Bin Mohd Sabri, Irfan Anjum Badruddin and Suhana Said

The purpose of this paper is to discuss the reliability of board level Sn‐Ag‐Cu (SAC) solder joints in terms of both thermal cycling and drop impact loading conditions…

Abstract

Purpose

The purpose of this paper is to discuss the reliability of board level Sn‐Ag‐Cu (SAC) solder joints in terms of both thermal cycling and drop impact loading conditions, and further modification of the characteristics of low Ag‐content SAC solder joints using minor alloying elements to withstand both thermal cycle and drop impact loads.

Design/methodology/approach

The thermal cycling and drop impact reliability of different Ag‐content SAC bulk solder will be discussed from the viewpoints of mechanical and micro‐structural properties.

Findings

The best SAC composition for drop performance is not necessarily the best composition for optimum thermal cycling reliability. The content level of silver in SAC solder alloys can be an advantage or a disadvantage depending on the application, package and reliability requirements. The low Ag‐content SAC alloys with different minor alloying elements such as Mn, Ce, Bi, Ni and Ti display good performance in terms of both thermal cycling and drop impact loading conditions.

Originality/value

The paper details the mechanical and micro‐structural properties requirements to design a robust bulk SAC solder joint. These properties provide design and manufacturing engineers with the necessary information when deciding on a solder alloy for their specific application.

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