Design of Lead-Free Solders and Pollution Control of Lead

2014 ◽  
Vol 881-883 ◽  
pp. 1435-1438 ◽  
Author(s):  
Gui Sheng Gan ◽  
Chang Hua Du ◽  
Chun Tian Li
Keyword(s):  
Pollution Control ◽  
Surface Film ◽  
Lead Content ◽  
Lead Free ◽  
Soldering Temperature ◽  
Soldering Process ◽  
Lead Production ◽  
Lead Free Solders

Due to increase refined lead production and slow industrialization of lead-free solders, hazard of lead to human and environment still existed. Based on pollutions of lead depending on the volatility and the solubility of lead, the new ways to prevent and reduce the pollution of lead were put forward. The lead content in lead-solders could be reduced appropriately and the dense surface film could be formed by micro-alloying in the view of material for reducing the pollution. Low soldering temperature and the optimal soldering process or equipment could also be taken to reduce the pollution of lead.

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

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.

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

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.

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

2003 ◽  
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.

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

2015 ◽  
Vol 60 (2) ◽  
pp. 1511-1515 ◽  
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).

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

2015 ◽  
Vol 773-774 ◽  
pp. 232-236 ◽  
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.

Investigation of Intermetallic Phases Formed in Lead-Free Solders

2015 ◽  
Vol 812 ◽  
pp. 357-362 ◽  
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.

Wetting characteristics of Sn-5Sb-CuNiAg lead-free solders on the copper substrate

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Xiuqi Wang ◽  
Fenglian Sun ◽  
Bangyao Han ◽  
Yilun Cao ◽  
Jinyang Du ◽  
...  
Keyword(s):  
High Temperature ◽  
Copper Substrate ◽  
Contact Angles ◽  
Alloying Elements ◽  
Lead Free ◽  
Content Type ◽  
Soldering Temperature ◽  
Solder Balls ◽  
Lead Free Solders ◽  
Wetting Behaviors

Purpose The purpose of this paper is to investigate the wetting behaviors of Sn-5Sb-CuNiAg solders on copper substrates in different soldering processes and the effects of alloying elements on the wettability. Design/methodology/approach Sn-5Sb-CuNiAg solder balls (750 µm in diameter) were spread and wetted on 40 × 40 × 1 mm copper plates, in different fluxes, soldering temperatures and time. The contact angles were obtained by a home-made measuring instrument. The samples were polished and deep etched before analyzed by scanning electron microscopy. Energy dispersive X-ray spectroscopy was used to identify the composition of the joints. Findings The effects of different soldering processes and alloying elements on the wetting behaviors of Sn-5Sb-CuNiAg solders on copper substrates were calculated and expounded. The rosin-based flux could effectively remove oxidation layers and improve the wettability of Sn-5Sb-CuNiAg solders. Then with the increase of soldering temperature and time, the contact angles decreased gradually. The soldering processes suited for Sn-5Sb-CuNiAg solders were RMA218, 280°C and 30 s. Considered the effects of alloying elements, the wettability of Sn-5Sb-0.5Cu-0.1Ni-0.5Ag was relatively favorable on copper substrates. Besides, Ni could accumulate at the solder/Cu interface and form a jagged (Cu,Ni)6Sn5 IMC. Originality/value This work was carried out with our handmade experiment equipment and the production of the quinary lead-free solder alloy used in wetting tests belongs to us. The investigated Sn-5Sb-CuNiAg alloys exhibited higher melting point and preferable wettability, that was one of the candidates for high-temperature lead-free solders to replace high-Pb solders, and applied extremely to high temperature and frequency working environments of the third-generation semiconductors components, with a greater potential research and development value.

scholarly journals Modification in Bi-Ag Lead-Free Solder-Bearing Alloying Elements

2018 ◽  
Vol 14 (2) ◽  
pp. 5504-5519 ◽  
Author(s):  
Rizk Mostafa Shalaby ◽  
Musaeed Allzeleh ◽  
Mustafa Kamal
Keyword(s):  
Rare Earth ◽  
Electrical Resistance ◽  
Creep Resistance ◽  
Melting Behavior ◽  
Lead Free ◽  
Lead Free Solder ◽  
Soldering Temperature ◽  
Urgent Task ◽  
Free Solder ◽  
Lead Free Solders

The development of lead-free solder has an urgent task for material scientist due to health and environmental concerns over the lead content of traditional solders. The objective of this study is to examine Bi-Ag-rare earth (RE) element considered as one of the more attractive lead-free solders since it can easily replace Sn-Pb eutectic alloy with increasing soldering temperature while causes for high-temperature applications. In order to enhance the soldering properties of Bi-Ag alloys, a trace eare earth (RE) element of Ho added into Bi-Ag alloys. The results indicated that the addition of RE led to the refining of coarse Bi-Ag grains, in the microstructure. The tensile strength, Hv and creep resistance increased with a decrease in melting point and electrical resistance. This paper brief the influences of rare earth alloying element and rapid solidification on both of the microstructure, intermetallic compounds, creep resistance, melting behavior, electrical resistance and mechanical behavior.

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