Lead‐free Solders for Electronic Packaging and Assembly

Circuit World ◽  
1994 ◽  
Vol 20 (4) ◽  
pp. 19-25 ◽  
Author(s):  
J.S. Hwang ◽  
Z. Guo
Keyword(s):  
Electronic Packaging ◽  
Lead Free ◽  
Lead Free Solders

Reliability Analysis of Lead-Free Solders in Electronic Packaging Using a Novel Surrogate Model and Kriging Concept

2018 ◽  
Vol 140 (4) ◽  
Author(s):  
Hamoon Azizsoltani ◽  
Achintya Haldar
Keyword(s):  
Response Surface ◽  
Electronic Packaging ◽  
Limit State ◽  
Experimental Studies ◽  
Lead Free ◽  
Evaluation Procedure ◽  
Design Parameters ◽  
State Function ◽  
Thermomechanical Loading ◽  
Lead Free Solders

A novel reliability evaluation procedure of lead-free solders used in electronic packaging (EP) subjected to thermomechanical loading is proposed. A solder ball is represented by finite elements (FEs). Major sources of nonlinearities are incorporated as realistically as practicable. Uncertainties in all design variables are quantified using available information. The thermomechanical loading is represented by five design parameters and uncertainties associated with them are incorporated. Since the performance or limit state function (LSF) of such complicated problem is implicit in nature, it is approximately generated explicitly in the failure region with the help of a completely improved response surface method (RSM)-based approach and the universal Kriging method (KM). The response surface (RS) is generated by conducting as few deterministic nonlinear finite element analyses as possible by integrating several advanced factorial mathematical concepts producing compounding beneficial effect. The accuracy, efficiency, and application potential of the procedure are established with the help of Monte Carlo simulation (MCS) and the results from laboratory investigation reported in the literature. The study conclusively verified the proposed method. Similar studies can be conducted to fill the knowledge gap for cases where the available analytical and experimental studies are limited or extend the information to cases where reliability information is unavailable. The study showcased how reliability information can be extracted with the help of multiple deterministic analyses. The authors believe that they proposed an alternative to the classical MCS technique.

Recent progress of Sn–Ag–Cu lead-free solders bearing alloy elements and nanoparticles in electronic packaging

2016 ◽  
Vol 27 (12) ◽  
pp. 12729-12763 ◽  
Author(s):  
Jie Wu ◽  
Song-bai Xue ◽  
Jing-wen Wang ◽  
Shuang Liu ◽  
Yi-long Han ◽  
...  
Keyword(s):  
Electronic Packaging ◽  
Recent Progress ◽  
Lead Free ◽  
Bearing Alloy ◽  
Lead Free Solders

Evolution of the Microstructure of Lead Free Solders Subjected to Both Aging and Cyclic Loading

2019 ◽  
Author(s):  
Md Mahmudur R. Chowdhury ◽  
Mohd Aminul Hoque ◽  
Jeffrey C. Suhling ◽  
Sa’d Hamasha ◽  
Pradeep Lall
Keyword(s):  
Cyclic Loading ◽  
Electronic Packaging ◽  
Solder Joints ◽  
Regions Of Interest ◽  
Lead Free ◽  
Microstructural Changes ◽  
Mechanical Fatigue ◽  
Mechanical Cycling ◽  
Lead Free Solders ◽  
Electronic Assemblies

Abstract Currently, lead-free solders are being widely used as an alternative to traditional Sn-Pb solders in micro-electronic packaging industry due to the environmental concern of lead. Fatigue failure of solder joints is one of the common failure modes in electronic packaging which might be attributed to the experiences of thermo-mechanical fatigue (e.g. Power switching) or mechanical fatigue (e.g. vibration) loading. To design these lead-free solders more strategically for specific applications, it is important to understand the failure mechanism of lead-free solders under fatigue loading. Moreover, the microstructure and constitutive properties of conventional lead free solder joints in electronic assemblies such as SAC305 changes when exposed to isothermal aging. These changes consequently reduce the reliability of lead free electronic assemblies significantly due to aging. In this study, we have examined the effects of prior aging on damage accumulation occurring in SAC305 and SAC_Q (SAC+Bi) solder materials subjected to mechanical cycling (fatigue testing). Uniaxial samples have been prepared and polished so that the microstructural changes could be tracked after the initial aging, and then subsequently with mechanical cycling. In particular, we have examined the microstructural changes that occurred in small fixed regions in the solder samples, rather than using several different regions. Regions of interest near the center of the sample were marked using small indents formed with a nanoindentation system. Samples were then subjected to aging at 125 °C for various durations to produce several different initial microstructures. Scanning electron microscopy (SEM) were used to investigate the aging induced microstructural changes in the regions of interest in the solder sample. After aging, the samples were then subjected to mechanical cycling. After various durations of cycling (e.g. 0, 10, 25, 50, 75, 100, 200, 300 cycles) that were below the fatigue life of the materials, the regions of interest were again examined using SEM. Using the recorded images, the microstructural evolutions in the fixed regions were observed, and the effects of the initial aging on the results were determined. In case of SAC305, It was found that the number of IMC particles decreased while the average diameter of the particles increases significantly due to the initial aging. The distribution and size of the intermetallic particles in the inter-dendritic regions were observed to remain essentially unchanged with the application of the mechanical cyclic load. Relative to the non-aged samples, there were significant differences observed in the rate and intensity of the micro crack growth occurring in the heavily aged samples that began with much coarser microstructures. Later, the cycling induced microstructure evolutions observed in the SAC_Q lead free alloy has been compared with the observed changes in the microstructure of SAC305 that occurred during the cyclic loading. Due to the presence of bismuth, significant difference in the microstructural evolution of the SAC_Q alloy during cycling were observed. Thus, the doped alloys have shown a high potential for use in thermal cycling conditions because of their improved resistance to aging-induced evolution.

Effect of aluminum content on structure, transport and mechanical properties of Sn-Zn eutectic lead free solder alloy rapidly solidified from melt.

2015 ◽  
Vol 10 (1) ◽  
pp. 2641-2648
Author(s):  
Rizk Mostafa Shalaby ◽  
Mohamed Munther ◽  
Abu-Bakr Al-Bidawi ◽  
Mustafa Kamal
Keyword(s):  
Mechanical Properties ◽  
Melting Point ◽  
Lead Free ◽  
Al Alloy ◽  
Lead Free Solder ◽  
Pronounced Increase ◽  
Mass Unit ◽  
Size Refinement ◽  
Free Solder ◽  
Lead Free Solders

The greatest advantage of Sn-Zn eutectic is its low melting point (198 oC) which is close to the melting point. of Sn-Pb eutectic solder (183 oC), as well as its low price per mass unit compared with Sn-Ag and Sn-Ag-Cu solders. In this paper, the effect of 0.0, 1.0, 2.0, 3.0, 4.0, and 5.0 wt. % Al as ternary additions on melting temperature, microstructure, microhardness and mechanical properties of the Sn-9Zn lead-free solders were investigated. It is shown that the alloying additions of Al at 4 wt. % to the Sn-Zn binary system lead to lower of the melting point to 195.72 ˚C.  From x-ray diffraction analysis, an aluminium phase, designated α-Al is detected for 4 and 5 wt. % Al compositions. The formation of an aluminium phase causes a pronounced increase in the electrical resistivity and microhardness. The ternary Sn-9Zn-2 wt.%Al exhibits micro hardness superior to Sn-9Zn binary alloy. The better Vickers hardness and melting points of the ternary alloy is attributed to solid solution effect, grain size refinement and precipitation of Al and Zn in the Sn matrix.  The Sn-9%Zn-4%Al alloy is a lead-free solder designed for possible drop-in replacement of Pb-Sn solders.  

Shear Strength and Dsc Analysis of High-Temperature Solders

2013 ◽  
Vol 58 (2) ◽  
pp. 529-533 ◽  
Author(s):  
R. Koleňák ◽  
M. Martinkovič ◽  
M. Koleňáková
Keyword(s):  
Shear Strength ◽  
High Temperature ◽  
Lead Free ◽  
Dsc Analysis ◽  
Ultrasonic Activation ◽  
Metallic Substrates ◽  
Cu Substrate ◽  
Lead Free Solders

The work is devoted to the study of shear strength of soldered joints fabricated by use of high-temperature solders of types Bi-11Ag, Au-20Sn, Sn-5Sb, Zn-4Al, Pb-5Sn, and Pb-10Sn. The shear strength was determined on metallic substrates made of Cu, Ni, and Ag. The strength of joints fabricated by use of flux and that of joints fabricated by use of ultrasonic activation without flux was compared. The obtained results have shown that in case of soldering by use of ultrasound (UT), higher shear strength of soldered joints was achieved with most solders. The highest shear strength by use of UT was achieved with an Au-20Sn joint fabricated on copper, namely up to 195 MPa. The lowest average values were achieved with Pb-based solders (Pb-5Sn and Pb-10Sn). The shear strength values of these solders used on Cu substrate varied from 24 to 27 MPa. DSC analysis was performed to determine the melting interval of lead-free solders.

scholarly journals Effects of Yttrium Addition on the Microstructure Evolution and Electrochemical Corrosion of SN-9zn Lead-Free Solders Al-Loy

Materials ◽  
2021 ◽  
Vol 14 (10) ◽  
pp. 2549
Author(s):  
Wenchao Yang ◽  
Jun Mao ◽  
Yueyuan Ma ◽  
Shuyuan Yu ◽  
Hongping He ◽  
...  
Keyword(s):  
Corrosion Resistance ◽  
Microstructure Evolution ◽  
Electrochemical Corrosion ◽  
Lead Free ◽  
Nacl Solution ◽  
Rich Phase ◽  
Yttrium Addition ◽  
Electrochemical Corrosion Behavior ◽  
Lead Free Solders ◽  
Addition Amount

Electrochemical corrosion behavior of ternary tin-zinc-yttrium (Sn-9Zn-xY) solder alloys were investigated in aerated 3.5 wt.% NaCl solution using potentiodynamic polarization techniques, and the microstructure evolution was obtained by scanning electron microscope (SEM). Eight different compositions of Sn-9Zn-xY (x = 0, 0.02, 0.04, 0.06, 0.08, 0.10, 0.20, and 0.30 wt.%) were compared by melting. The experimental results show that when the content of Y reached 0.06 wt.%, the grain size of Zn-rich phase became the smallest and the effect of grain refinement was the best, but there was no significant effect on the melting point. With the increases of Y content, the spreading ratio first increased and then decreased. When the content of Y was 0.06 wt.%, the Sn-9Zn-0.06Y solder alloy had the best wettability on the Cu substrate, which was increased by approximately 20% compared with Sn-9Zn. Besides, the electrochemical corrosion experimental shows that the Y can improve the corrosion resistance of Sn-9Zn system in 3.5 wt.% NaCl solution, and the corrosion resistance of the alloy is better when the amount of Y added is larger within 0.02–0.30 wt.%. Overall considering all performances, the optimal performance can be obtained when the addition amount of Y is 0.06.

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