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Article
Publication date: 15 February 2021

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. 33 no. 4
Type: Research Article
ISSN: 0954-0911

Keywords

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Article
Publication date: 13 January 2021

Gui-sheng Gan, Liujie Jiang, Shiqi Chen, Yongqiang Deng, Donghua Yang, Zhaoqi Jiang, Huadong Cao, Mizhe Tian, Qianzhu Xu and Xin Liu

Low-Ag SAC solder will lead to a series of problems, such as increased the melting range and declined the solderability and so on. These research studies do not have too…

Abstract

Purpose

Low-Ag SAC solder will lead to a series of problems, such as increased the melting range and declined the solderability and so on. These research studies do not have too much impact on the improvement of solders’ performance but were difficult to achieve satisfactory results. It is urgent to develop new soldering technology to avoid the bottleneck of lead-free solder. low-temperature-stirring soldering and ultrasonic-assisted soldering was developed in the authors’ early work, but slag inclusion and pore would gather and grow up to lead decreasing of the shear strength. In this paper, Cu/SAC0307 +Zn power/Cu joints with ultrasonic-assisted at low-temperature was successfully achieved.

Design/methodology/approach

45um Zn-powder and SAC0307 No.4 solder powder were mixed to fill the Cu-Cu joint, and the content of Zn-powder were 0 and 5%, 7.5% and 10%, 12.5% and 15% respectively. During the soldering process under ambient atmosphere %252C the heating platform provided a constant 220%253 F and the ultrasonic vibrator applied a constant pressure of 4 MPa to the copper substrate. The soldering process was completed after holding 70 s at 300 W.

Findings

The Zn particles made the IMC at the joint interface and in the soldering seam from scallop-type Cu6Sn5 to flat-type Cu5Zn8. The shear strength of joints without Zn was only 12.43 MPa, the shear strength of joints with 10% Zn reached a peak of 34.25 MPa, and the shear strength of joints containing 10% Zn was 63.71% higher than that of joints without zinc particles, and then the shear strength decreased. In addition, with the increase of zinc content, the fracture mode of the joint changed from the brittle fracture of the original layered tears to the mixed tough and brittle fracture.

Originality/value

A new method that Zn micron-size powders and SAC0307 micron-size powders was mixed to fill the joint, and successfully achieved micro-joining of Cu/Cu under ultrasonic-assisted without flux at low-temperature.

Details

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

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Article
Publication date: 1 January 1992

N. Brady and T.J. Ennis

Tensile pull strength tests were used to study the strength of solder joints of 25 mil gull wing leads on 132 pin quad flat pack components. The authors generated…

Abstract

Tensile pull strength tests were used to study the strength of solder joints of 25 mil gull wing leads on 132 pin quad flat pack components. The authors generated quadratic and linear models which can be used to predict the pull strength of a solder joint given its geometry. The shape parameters studied were stand‐off height between the lead and substrate, height of heel fillet, radius of curvature of heel fillet, length of heel fillet, height of solder at toe region, and thickness of solder on the lead. The most significant parameters in determining the tensile pull strength of the solder joint are the height and length of the heel fillet. A study was performed to quantify the effect of lead finish on the accuracy of these models. The lead finish was found to have a significant effect on the solder joint strength. The effect of lateral misregistration on the tensile pull strength of solder joints was also investigated. No correlation between the extent of lateral misregistration and joint pull strength has been found.

Details

Soldering & Surface Mount Technology, vol. 4 no. 1
Type: Research Article
ISSN: 0954-0911

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Article
Publication date: 6 April 2012

Duncan Camilleri

Power electronics are usually soldered to Al2‐O3 direct‐bond‐copper (DBC) substrates to increase thermal diffusivity, while at the same time increasing electrical…

Abstract

Purpose

Power electronics are usually soldered to Al2‐O3 direct‐bond‐copper (DBC) substrates to increase thermal diffusivity, while at the same time increasing electrical isolation. However, soldering gives rise to inherent residual stresses and out‐of‐plane deformation. The purpose of this paper is to look at the effect of soldering processes of Al2‐O3 DBC substrates to copper plates and power electronics, on their thermal fatigue life and warpage.

Design/methodology/approach

A numerical thermo‐mechanical finite element model, using the Chaboche material model, was developed to identify the thermal plastic strains evolved during soldering of DBC substrates to copper plates and power electronics. The plastic strains in conjunction with established extremely low cycle fatigue life prediction model for ductile material were used to predict the number of soldering cycles to failure. The predicted out‐of‐plane deformation and number of soldering cycles to failures was compared to realistic tests.

Findings

Soldering processes drastically reduce the thermal fatigue life of DBC substrates, giving rise to thermal cracking and premature failure. In this study the soldering process considered gave rise to out‐of‐plane deformations, consequently reducing heat dispersion in soldered DBC substrate assemblies. Furthermore, soldering gave rise to interface cracking and failed after three soldering cycles. Numerical finite element models were developed and are in good agreement with the experimental tests results.

Research limitations/implications

The influence of soldering processes of DBC substrates to copper plates and electronics on the thermal fatigue life should be taken into consideration when establishing the design life of DBC substrates. Finite element models can be utilised to optimize soldering processes and optimize the design of DBC substrates.

Originality/value

The effect of soldering processes on DBC substrates was studied. A numerical finite element model used for the prediction of design life cycle and out‐of‐plane deformation is proposed.

Details

Soldering & Surface Mount Technology, vol. 24 no. 2
Type: Research Article
ISSN: 0954-0911

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Article
Publication date: 1 January 1989

E.E. de Kluizenaar and M.M.F. Verguld

Strength measurements of soldered joints in electronics are widely used for the assessment of joint quality. However, a variety of experiments, reported in this article…

Abstract

Strength measurements of soldered joints in electronics are widely used for the assessment of joint quality. However, a variety of experiments, reported in this article, clearly show that a strong relationship between initial strength and joint quality does not exist. Far more important for joint reliability is the resistance of soldered constructions to low‐cycle fatigue of the solder metal, caused by thermal expansion differences upon temperature cycling during use. A temperature cycling test is proposed as a standard accelerated ageing method for the prediction of the low‐cycle fatigue life of soldered joints in electronics.

Details

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

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Article
Publication date: 13 April 2010

R.L. Xu, Y.C. Liu, C. Wei and L.M. Yu

The interfacial structure is vitally important for achieving a good joint reliability during service. The purpose of this paper is to systematically explore the effects of…

Abstract

Purpose

The interfacial structure is vitally important for achieving a good joint reliability during service. The purpose of this paper is to systematically explore the effects of Zn addition into the Sn-3.5Ag eutectic solder on the formation of intermetallic compound (IMC) layer at the interface between Sn-3.5Ag-xZn (x = 0, 0.9 and 3) solders and Cu pad.

Design/methodology/approach

To obtain useful information on the formation of interfacial structure and to determine an effective way to avoid the formation of brittle joints, a series of Sn-Ag lead-free solders with different Zn contents were prepared and soldered. To investigate the IMC layers between Sn-3.5Ag-xZn (x = 0, 0.9 and 3) lead-free solders and the Cu pads, three specimens of the Sn-3.5Ag-xZn/Cu were soldered at 250°C for one min.

Findings

It is found that the addition of Zn in the Sn-3.5Ag eutectic solder can prompt the formation of Cu5Zn8 IMCs, and restrain the formation of the Cu6Sn5 IMCs. Moreover, the addition of Zn in the Sn-3.5Ag eutectic solder will reduce the solubility of Cu in the liquid solder, which accelerates the growth of the formed IMCs. Consequently, the thickness of IMC layer increases with increasing the content of Zn.

Originality/value

This paper usefully demonstrates how the addition of Zn favoured the formation of the Cu5Zn8 phase and restrained the formation of the Cu6Sn5 phase. Moreover, the addition of Zn in the Sn-Ag eutectic solder would reduce the solubility of Cu in the liquid solder, which accelerates the growth of the formed IMCs. Consequently, the thickness of the IMC layer increased with increasing concentration of Zn.

Details

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

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Article
Publication date: 4 May 2012

Dhafer Abdul‐Ameer Shnawah, Mohd Faizul Mohd Sabri, Irfan Anjum Badruddin and Fa Xing Che

The purpose of this paper is to investigate the effect of Al addition on the bulk alloy microstructure and tensile properties of the low Ag‐content Sn‐1Ag‐0.5Cu (SAC105…

Abstract

Purpose

The purpose of this paper is to investigate the effect of Al addition on the bulk alloy microstructure and tensile properties of the low Ag‐content Sn‐1Ag‐0.5Cu (SAC105) solder alloy.

Design/methodology/approach

The Sn‐1Ag‐0.5Cu‐xAl (x=0, 1, 1.5 and 2 wt.%) bulk solder specimens with flat dog‐bone shape were used for tensile testing in this work. The specimens were prepared by melting purity ingots of Sn, Ag, Cu and Al in an induction furnace. Subsequently, the molten alloys were poured into pre‐heated stainless steel molds, and the molds were naturally air‐cooled to room temperature. Finally, the molds were disassembled, and the dog‐bone samples were removed. The solder specimens were subjected to tensile testing on an INSTRON tester with loading rate 10−3 s−1. 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. To obtain the microstructure, the solder samples were prepared by dicing, molding, grinding and polishing processes.

Findings

The addition of Al to the SAC105 solder alloy suppresses the formation of Ag3Sn and Cu6Sn5 IMC particles and leads to the formation of larger Al‐rich and Al‐Cu IMC particles and a large amount of fine Al‐Ag IMC particles. The addition of Al also leads to refining of the primary β‐Sn grains. The addition of Al results in a significant increase on the elastic modulus and yield strength. On the other hand, the addition of Al drastically deteriorates the total elongation.

Originality/value

The addition of Al to the low Ag‐content SAC105 solder alloy has been discussed for the first time. This work provides a starting‐point to study the effect of Al addition on the drop impact and thermal cycling reliability of the SAC105 alloy.

Details

Microelectronics International, vol. 29 no. 2
Type: Research Article
ISSN: 1356-5362

Keywords

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Article
Publication date: 1 April 2002

P.M. Beckett, A.R. Fleming, J.M. Gilbert and D.G. Whitehead

Laser soldering provides a useful tool for the electronics manufacturer and has found a number of successful industrial applications. The laser provides highly…

Abstract

Laser soldering provides a useful tool for the electronics manufacturer and has found a number of successful industrial applications. The laser provides highly controllable localised heating in a manner similar to hand soldering and has distinct advantages over other soldering methods. However, the heating processes that occur in laser soldering are complex making it difficult to predict whether a particular operation will be successful. Numerical modelling provides a valuable tool in answering such questions but the modelling process and the assumptions upon which it is based must be understood if the results are to be reliable.This paper explains the assumptions made in deriving a suitable model and describes the use of a commercial finite element modelling package to aid the understanding of laser soldering processes, with a particular emphasis on single and multi‐pass scanned beam soldering operations.

Details

Soldering & Surface Mount Technology, vol. 14 no. 1
Type: Research Article
ISSN: 0954-0911

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Article
Publication date: 4 January 2016

Yang Liu, Fenglian Sun, Cadmus A. Yuan and Guoqi Zhang

The purpose of this paper is to discuss the possibility of using soldering process for the bonding of chip-on-flexible (COF) light-emitting diode (LED) packages to heat…

Abstract

Purpose

The purpose of this paper is to discuss the possibility of using soldering process for the bonding of chip-on-flexible (COF) light-emitting diode (LED) packages to heat sinks. The common bonding materials are thermal conductive adhesives. For thermal performance and reliability concerns, Tin-Bismuth (SnBi) lead-free solder paste was used for the connection of the COF packages and the Cu heat sinks by a soldering process in this study. Meanwhile, the geometrical effect of the SnBi solder layer on the thermal performance was also investigated.

Design/methodology/approach

The effects of the bonding materials and the area of the solder layers on the thermal performance of the LED modules were investigated by finite element simulation and experimental tests.

Findings

The SnBi soldered modules show much lower thermal resistance at the bonding layers than the adhesive-bonded LED module. Vertical heat transfer from the LED chips to the heat sinks is the primary heat dissipation mode for the SnBi soldered modules. Thus, the LED module with local solder layer shows similar LED thermal performance with the full-area soldered module. Meanwhile, the local soldering process decreases the possibility to form randomly distributed defects such as the large area voids and residue flux in the solder layers.

Research limitations/implications

The research is still in progress. Further studies mainly focus on the reliability of the samples with different bonding materials.

Practical implications

COF package is a new structure for LED packages. This study provides a comparison between SnBi solder and adhesive material on the thermal performance of the LED. Meanwhile, the authors optimized the geometrical design for the solder layer. The study provides a feasible bonding process for COF packages onto heat sinks.

Originality/value

This study provides a soldering process for the COF LED packages. The thermal performance of the LED light source was improved significantly by the new process.

Details

Microelectronics International, vol. 33 no. 1
Type: Research Article
ISSN: 1356-5362

Keywords

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Article
Publication date: 1 December 2000

Qinong Zhu, Mei Sheng and Le Luo

The effects of Pb contamination on the microstructure and shear strength of lead‐free solder joints with non‐lead containing finishes on both the PCB and terminals of…

Abstract

The effects of Pb contamination on the microstructure and shear strength of lead‐free solder joints with non‐lead containing finishes on both the PCB and terminals of 1,206 chip capacitors at different temperatures were investigated. Two kinds of lead‐free solders (Sn96.5Ag3.5 and Sn95Sb5) were selected, and different amounts of eutectic Sn‐Pb were added to these lead‐free solders according to the potential Pb contamination in a 1,206 chip capacitor solder joint. It was found that there was no difference in shear strength of solder joint at room temperature for those with or without Pb contamination, but the shear strength at 1258C for the solder joint without Pb contamination was about 15 percent higher than for those with Pb contamination.

Details

Soldering & Surface Mount Technology, vol. 12 no. 3
Type: Research Article
ISSN: 0954-0911

Keywords

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