Formation and Distribution of Sn-Cu IMC in Lead-Free Soldering Process Induced by Laser Heating

Hurtony, Tamás; Balogh, Bálint; Gordon, Peter

doi:10.2174/1876402911002030178

Cited by 5 publications

(3 citation statements)

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“…The moving inside the melted solder (Marangoni effect, natural convection etc.) contributes to a certain extent to the growth of intermetallic crystals and their spalling [16][17][18]. In [19], the influence of the direction of heat flow on the crystallographic orientation of solder balls SAC305 for soldering on the Dummy BGA case was determined, namely the creation of more nuclei with different crystallographic orientations for soldering from the top side and both sides at the same time (upper and lower heating).…”

Section: Discussionmentioning

confidence: 99%

Influence of heat flow direction on solder ball interfacial layer

Otahal

Szendiuch

2018

Journal of Electrical Engineering

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This paper deals with the research of an intermetallic layer of SAC305 solder balls soldered from three directions of the heat flow in the ball-attach process for BGA package. From the point of view of the heat flow direction, the samples were soldered by infrared heating. The heat sources were placed on the top, bottom and both lateral sides of the BGA package. After the solder balls-attach process, a metallographic cross-section was performed, followed by selective etching to visualize the relief of the intermetallic layer. Images of the interfacial between the solder and solder pad were taken from the created samples, followed by measurement of the average thickness and root mean square roughness of the intermetallic layer. The results showed changes in the intermetallic layer. The largest thickness of the intermetallic layer was observed on samples soldered from the top and both sides. Soldering with the bottom infrared heater resulted to the smallest thickness of the intermetallic layer. The same trend was in the roughness of the IMC layer. The greatest roughness was found for samples soldered by the top and both side heaters. The top soldered samples exhibit the smallest roughness.

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Section: Discussionmentioning

confidence: 99%

Influence of heat flow direction on solder ball interfacial layer

Otahal

Szendiuch

2018

Journal of Electrical Engineering

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“…and materials composition mainly define the resulting interfacial microstructure of the SAC/Cu system. The transient and spatially non-uniform temperature profile during laser soldering lead to interfacial microstructural evolution totally different from that of conventional isothermal reflow soldering [16] . The formation of interfacial IMCs of two different morphologies of IMC-prismatic and scalloped, at the interface of Sn/Cu and Sn-3.5Ag-0.5Cu/Cu systems, due to the alteration in the value of laser power and scan speed has been reported in [17] .…”

Section: Introductionmentioning

confidence: 90%

A data-driven framework to predict the morphology of interfacial Cu6Sn5 IMC in SAC/Cu system during laser soldering

Kunwar

Liu

et al. 2020

Journal of Materials Science & Technology

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A data-driven approach combining together the experimental laser soldering, finite element analysis and machine learning, has been utilized to predict the morphology of interfacial intermetallic compound (IMC) in Sn-xAg-yCu/Cu (SAC/Cu) system. Six types of SAC solders with varying weight proportion of Ag and Cu, have been processed with fiber laser at different magnitudes of power (30-50 W) and scan speed (10 -240 mm/min), and the resultant IMC morphologies characterized through scanning electron microscope are categorized as prismatic and scalloped ones. For the different alloy composition and laser parameters, finite element method (FEM) is employed to compute the transient distribution of temperature at the interface of solder and substrates. The FEM-generated datasets are supplied to a neural network that predicts the IMC morphology through the quantified values of temperature dependent Jackson parameter (αJ). The numerical value of αJ predicted from neural network is validated with experimental IMC morphologies. The critical scan speed for the morphology transition between prismatic and scalloped IMC is estimated for each solder composition at a given power. Sn-0.7Cu having the largest critical scan speed at 30 W and Sn-3.5Ag alloy having the largest critical scan speed at input power 2 values of 40 W and 50 W, thus possessing the greatest likelihood of forming prismatic interfacial IMC during laser soldering, can be inferred as most suitable SAC solders in applications exposed to shear loads.

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“…The power ( P ), scan speed ( V scan ) and other laser processing parameters, as well as material composition, primarily determine the interfacial microstructure of the Sn, Sn3.5Ag, SAC/Cu system (Kunwar et al , 2018). The interfacial microstructural evolution during laser soldering is completely different from that of traditional isothermal reflow soldering due to the transient and spatially non-uniform temperature profiles (Hurtony et al , 2010). As illustrated in Figure 6, the Sn-3.0Ag-0.5Cu/Cu system creates IMCs with a prismatic morphology at V scan = 100 mm/min, while the Sn/Cu system produces IMCs with a scalloped morphology even at a substantially slower scan speed of 70 mm/min.…”

Section: Laser Soldering Effect Onto Solder Joint Formationmentioning

confidence: 99%

A review: effect of copper percentage solder alloy after laser soldering

Abdullah

Idris

2022

SSMT

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Purpose This study aims to review the effect of copper percentage in Sn-based solder alloys (Sn-xCu, x = 0–5 Wt.%) on intermetallic compound (IMC) formation and growth after laser soldering. Design/methodology/approach This study reviews the interfacial reactions at the solder joint interface, solder joint morphology and the theory on characterizing the formation and growth of IMCs. In addition, the effects of alloying and strengthening mechanism, including wettability, melting and mechanical properties are discussed. Findings This paper presents a comprehensive overview of the composition of tin-copper (Sn-Cu) solders with a potential to enhance their microstructure, mechanical characteristics and wettability by varying the Cu percentage. The study found that the best Cu content in the Sn-xCu solder alloy was 0.6–0.7 Wt.%; this composition provided high shear strength, vibration fracture life value and ideal IMC thickness. A method of solder alloy preparation was also found through powder metallurgy and laser soldering to improve the solder joint reliability. Research limitations/implications This study focuses on interfacial reactions at the solder joint interface, solder joint morphology, modelling simulation of joint strength and the theory on characterising the formation and growth of IMC. Originality/value The paper comprehensively summarises the useful findings of the Sn-Cu series. This information will be important for future trends in laser soldering on solder joint formation.

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Formation and Distribution of Sn-Cu IMC in Lead-Free Soldering Process Induced by Laser Heating

Cited by 5 publications

References 0 publications

Influence of heat flow direction on solder ball interfacial layer

Influence of heat flow direction on solder ball interfacial layer

A data-driven framework to predict the morphology of interfacial Cu6Sn5 IMC in SAC/Cu system during laser soldering

A review: effect of copper percentage solder alloy after laser soldering

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