Kinetics-Based Modeling of Bond-Metal Dissolution and IMC During Soldering

Electronic and Photonic Packaging, Electrical Systems Design and Photonics, and Nanotechnology ◽

10.1115/imece2006-14658 ◽

2006 ◽

Author(s):

Mohammad Faizan ◽

Guo-X. Wang

Keyword(s):

Intermetallic Phase ◽

Molten Solder ◽

Lead Free ◽

Joint Interface ◽

Environment Friendly ◽

Soldering Process ◽

Substrate Dissolution ◽

Soldering Reaction ◽

Lead Free Solders ◽

Kinetics Of

Soldering has become an indispensable joining process in the electronic packaging industry. The industry is aiming for the use of environment friendly lead-free solders. All the lead-free solders are high tin-containing alloys. During the soldering process, an intense interaction of metallization on PCB and tin from the solder occurs at the metallization/solder interface. Intermetallic compound (IMC) is formed at the interface and subsequently PCB bond-metal (substrate) is dissolved into the molten solder. In the present study the terms bond-metal and substrate will be used interchangeably and the term 'substrate' refers to the top layer of the PCB which comes in contact with the molten solder during soldering reaction. Thickness of the intermetallic phase formed at the joint interface and amount of substrate lost is critical in achieving reliable solder joints. During the wet phase of soldering process, the IMC does not grow as layered structure; rather it takes the shape of scallops. The growth of scalloped IMC during the solder/substrate interaction entails complicated physics. Understanding of the actual kinetics involved in the formation of IMC phase is important in controlling the process to achieve desired results. This paper presents theoretical analysis of the kinetics involved in the formation of the scalloped intermetallic phase. The intermetallic phase growth is experimentally investigated to support the underlying kinetics of the process. Numerical model has been suggested to translate the physics of the process. The model is based on the basic mass diffusion equations and can predict the substrate dissolution and IMC thickness as a function of soldering time.

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Performance Assessment of a Low Temperature Polymer Conductor for Lead-Free Soldering Processes

International Symposium on Microelectronics ◽

10.4071/isom-tp33 ◽

2014 ◽

Vol 2014 (1) ◽

pp. 000251-000257

Author(s):

Steven Grabey ◽

Samson Shahbazi ◽

Sarah Groman ◽

Catherine Munoz

Keyword(s):

Low Temperature ◽

Thick Film ◽

Elevated Temperatures ◽

Printed Electronics ◽

High Reliability ◽

Sem Analysis ◽

Lead Free ◽

Sac305 Solder ◽

Soldering Process ◽

Lead Free Solders

An increased interest in low temperature polymer thick film products has become apparent due to the rise of the printed electronics market. The specifications for these products are becoming more demanding with expectations that the low temperature products should perform at a level that is typically reserved for their high temperature counterparts; including solderability with lead free solders, high reliability and strong adhesion. Traditionally, it has only been possible to use leaded solders for soldering to polymer based thick film conductors. Over the last 15 years environmental concerns and legislation have pushed the industry towards a lead free approach. The shift to lead free solders, while beneficial, provides new challenges during processing. The high temperatures required for a lead-free soldering process yield a naturally harsher environment for polymer thick film pastes. In the past these conditions have proven too harsh for the pastes to survive. The polymer thick film discussed in this document aims to address some of these concerns for a highly reliable and easy to process polymer thick film paste. Due to the poor leaching characteristics of polymer thick films, at elevated temperatures, the predecessors of this paste typically soldered at low temperatures with leaded solders. The goal of this paper is to present a low temperature paste that is compatible with a variety of substrates and readily accepts lead-free solder. This paper will discuss a newly formulated low temperature curing (150°C – 200°C) RoHS and REACH compliant paste that shows excellent solderability with SAC305 solder. The paste was evaluated using a dip soldering method at 235°C–250°C on a variety of substrates. The data presented includes solder acceptance, adhesion data, thermal analysis and SEM analysis.

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An Investigation of Copper Dissolution and Microstructural Development in Lead-Free Solders

Heat Transfer, Volume 1 ◽

10.1115/imece2003-42543 ◽

2003 ◽

Cited By ~ 2

Author(s):

M. Faizan ◽

R. A. McCoy ◽

D. C. Lin ◽

G.-X. Wang

Keyword(s):

Lead Free ◽

Microstructural Development ◽

Reflow Time ◽

Kinetics Parameters ◽

Soldering Process ◽

Copper Dissolution ◽

Joint Reliability ◽

Critical Issues ◽

Lead Free Solders ◽

Cu Dissolution

Copper dissolution and intermetallic compound (IMC) formation during reflow of soldered joints are critical issues for joint reliability. Most of studies in the literature aimed at the coarsening and growth of the IMC layer of the soldered joints during service and only limited data is available during soldering process. This is particularly true for lead-free solders, which have attracted the attention of researchers just recently. This paper presents an experimental study of copper dissolution and IMC growth of lead-free solders during the reflow process. Solder buttons of either Sn or Sn-3.5wt%Ag were reflowed over a copper (99.9% pure) substrate for various reflow time periods ranging from 10 seconds to 10 minutes. Four reflow temperatures were selected, 232°C, 250°C, 275°C and 300°C for pure tin and 221°C, 250°C, 275°C and 300°C for Sn-3.5%Ag respectively. The average thickness of the grown IMC layer and the amount of copper dissolved during reflow were determined using the images obtained from the metallurgical microscope. The kinetics of IMC growth and Cu dissolution were then quantified and the estimated kinetics parameters can be used to determine the copper dissolution and IMC layer thickness during reflow soldering.

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Influence of Content of Ni and Ag on Microstructure and Joint Strength of Lead-Free Solder Joint with Sn-Ag-Cu-Ni-Ge

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.353-358.2033 ◽

2007 ◽

Vol 353-358 ◽

pp. 2033-2036 ◽

Cited By ~ 3

Author(s):

Ikuo Shohji ◽

Satoshi Tsunoda ◽

Hirohiko Watanabe ◽

Tatsuhiko Asai

Keyword(s):

Reaction Layer ◽

Joint Strength ◽

Heat Exposure ◽

Layer Growth ◽

Lead Free ◽

Joint Interface ◽

Lead Free Solder ◽

Free Solder ◽

Kinetics Of ◽

Soldered Joint

An influence of content of Ni and Ag in a Sn-Ag-Cu-Ni-Ge lead-free solder has been investigated on microstructure and joint strength of the soldered joint under heat exposure conditions. The growth kinetics of the reaction layer formed at the joint interface has been investigated, and the apparent activation energy of the reaction layer growth has been also examined. Moreover, the soldered joints with Sn-Ag and Sn-Ag-Cu solders were prepared and were compared with the joints with the Sn-Ag-Cu-Ni-Ge solders.

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Optimising the wave soldering process for lead free solders

Proceedings of 2005 International Conference on Asian Green Electronics, 2005. AGEC. ◽

10.1109/agec.2005.1452331 ◽

2005 ◽

Author(s):

S. Stoyanov ◽

C. Bailey ◽

N. Saxena ◽

S. Adams

Keyword(s):

Lead Free ◽

Soldering Process ◽

Wave Soldering ◽

Lead Free Solders

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Investigation Of Intermetallic Compounds In Sn-Cu-Ni Lead-Free Solders

Archives of Metallurgy and Materials ◽

10.1515/amm-2015-0163 ◽

2015 ◽

Vol 60 (2) ◽

pp. 1511-1515 ◽

Cited By ~ 3

Author(s):

E. Nagy ◽

F. Kristaly ◽

A. Gyenes ◽

Z. Gacsi

Keyword(s):

Intermetallic Compounds ◽

Diffraction Method ◽

Lead Free ◽

Structural Behaviour ◽

Cu Content ◽

Soldering Process ◽

Cu Alloys ◽

Complex Structural ◽

Interfacial Intermetallic Compounds ◽

Lead Free Solders

Abstract Interfacial intermetallic compounds (IMC) play an important role in Sn-Cu lead-free soldering. The size and morphology of the intermetallic compounds formed between the lead-free solder and the Cu substrate have a significant effect on the mechanical strength of the solder joint. In the soldering process of Sn-Cu alloys, Cu6Sn5 intermetallic compounds are formed. The complex structural behaviour of Cu6Sn5 IMC is temperature- and composition-dependent and it is long since subject to scientific research. The Cu6Sn5 phase basically exists in two crystal structures: hexagonal η-Cu6Sn5 (at temperatures above 186°C) and monoclinic η’-Cu6Sn5 (at lower temperatures). In the presence of Ni in the solder, the η-η’ transformation does not occur, therefore, the η-Cu6Sn5 phase remains stable. In this study the role of Ni in the (Cu,Ni)6Sn5 intermetallic compound in Sn-Cu lead-free solders was examined. Sn-Cu alloys with different Cu content (0.5 to 1 mass%) were modified through Ni addition. The morphology of the intermetallic compounds of the modified Sn-Cu alloys was investigated by optical microscopy (OM) and scanning electron microscopy (SEM), the IMC phases were examined with X-ray diffraction method (XRD).

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Intermetallic phase detection in lead-free solders using synchrotron x-ray diffraction

Journal of Electronic Materials ◽

10.1007/s11664-004-0094-x ◽

2004 ◽

Vol 33 (12) ◽

pp. 1524-1529 ◽

Cited By ~ 8

Author(s):

Gavin J. Jackson ◽

Hua Lu ◽

Raj Durairaj ◽

Nick Hoo ◽

Chris Bailey ◽

...

Keyword(s):

Intermetallic Phase ◽

Lead Free ◽

Phase Detection ◽

X Ray Diffraction ◽

X Ray ◽

Lead Free Solders

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New Glass Sealing Method with Lead-Free Solders

Advances in Science and Technology ◽

10.4028/www.scientific.net/ast.45.1604 ◽

2006 ◽

Vol 45 ◽

pp. 1604-1607 ◽

Cited By ~ 1

Author(s):

Koichi Sakaguchi ◽

Shinjiro Domi ◽

Katsuaki Suganuma

Keyword(s):

Metal Plate ◽

Molten Solder ◽

Lead Free ◽

Capillary Action ◽

Eutectic Solder ◽

Glass Substrates ◽

Novel Technique ◽

Hermetic Sealing ◽

Lead Free Solders

We have developed a novel technique of joining a pair of glass substrates. In the process, molten solder penetrates the gap between the glass substrates while the solder-glass interfaces are being activated by friction. The activation is given by a metal plate, which slides through the gap along the edge of the paired glass substrates and brings in the molten solder by capillary-action. A Ti-doped Sn-Zn eutectic solder showed good hermetic sealing of glass. A eutectic In-Sn solder also yielded good joining, especially at low sealing temperatures.

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Comparison between SAC405 Lead-Free Solders and EN(P)EPIG and EN(B)EPIG Surface Finishes

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.773-774.232 ◽

2015 ◽

Vol 773-774 ◽

pp. 232-236 ◽

Cited By ~ 2

Author(s):

Osman Saliza Azlina ◽

Ali Ourdjini ◽

Mohd Halim Irwan Ibrahim

Keyword(s):

Isothermal Aging ◽

Optical Microscope ◽

Hazardous Substances ◽

Lead Free ◽

Grain Size Analysis ◽

Size Analysis ◽

Reflow Soldering ◽

Soldering Process ◽

Surface Finishes ◽

Lead Free Solders

In electronics industries, most of them had to shifted their solder materials from leaded solders into lead-free solders due to the environmental concerns and follow the legislation of Restriction of use Hazardous Substances (RoHS). Thus, Sn-Ag-Cu solder is one of the choices that can replace the leaded solder and also offer better properties. This study investigates the comparison between Sn-4.0Ag-0.5Cu (SAC405) and EN(P)EPIG and EN(B)EPIG surface finishes. Reliability of solder joint has been assessed by performing solid state isothermal aging at 150oC for 250 up to 2000 hours. After reflow soldering process, (Cu,Ni)6Sn5intermetallic compound (IMC) is dominated at near centre of solder meanwhile (Ni,Cu)3Sn4IMC is dominated at near outside of solder ball.Moreover, aging time resulted in an increase in thickness and changed the morphology into more spherical, dense and large grain size. Analysis by optical microscope revealed that the IMC thickness of EN(B)EPIG produced thicker IMC compared to EN(P)EPIG surface finish during reflow as well as isothermal aging.

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Investigation of Intermetallic Phases Formed in Lead-Free Solders

Materials Science Forum ◽

10.4028/www.scientific.net/msf.812.357 ◽

2015 ◽

Vol 812 ◽

pp. 357-362 ◽

Cited By ~ 1

Author(s):

Erzsébet Nagy ◽

Anett Gyenes ◽

Alíz Molnár ◽

Zoltán Gácsi

Keyword(s):

Copper Alloys ◽

Intermetallic Phases ◽

Lead Free ◽

Metallographic Examination ◽

Soldering Process ◽

Soldering Technology ◽

Tin Silver Copper Alloys ◽

Soldering Alloys ◽

Tin Silver Copper ◽

Lead Free Solders

Industry should gradually replace the tin-lead solder alloys used traditionally in the soft soldering technology by lead-free soldering alloys, which raises a lot of new technological and scientific problems to be solved. The introduction and application of lead-free alloys caused a number of soldering defects not observed earlier; mechanisms of their formation are still unclear. One of such defects is whisker formation, another one is intensified formation of intermetallic phases. The appearance of undesired intermetallic phases in the soldering material spoils its mechanical properties; therefore it is particularly important that these phases do not form in electronic components. Besides, the formation of intermetallic compounds may occur in the soldering bath, thus making the soldering process difficult or even impossible.Tin-copper-nickel and tin-silver-copper alloys are suitable for the replacement of tin-lead alloys. The components of these alloys were studied. After metallographic examination of the specimens the occurrence of intermetallic phases was determined by the XRD method. The identification of intermetallic phases was carried out by using literature data and phase diagrams.

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