Effects of minor alloying additive on the shear strength of Sn-58Bi solder joint

The use of Pb has been limited in the electronic industry because of the toxicity of lead. As the result, the research and development activities in developing lead-free solders have been accelerated and some lead-free solders were introduced as alternative. Sn-Bi-based alloys are an alternative to replace Pb-based solders in the low temperature ranges. However, Sn-Bi-based solders show brittle behavior in both the bulk and the interface. Generally, the addition of impurity elements to the solders can improve the ductility of the solder joint in both the bulk and the interface by refining the solder microstructure and suppressing the intermetallics at the interface, respectively. In this study, the effect of third elements, i.e., Ni and In (1 and 0.5wt.%) on the microstructure of the Sn-58Bi solder and thickness of the interface between Sn-58Bi solder and Cu substrate were investigated. Solid state IMC compound layer growth was also examined following the thermal aging of the solder joint. Results after aging show that minor added elements were effective in suppressing the intermetallics at the interface during solid state growth. The results also show that the added In was highly effective in limiting the Bi phase coarsening. Mechanical properties of solder joints, before and after heat treatment, were also investigated by shear and micro-vickers tests.

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Effect of 0.05% Cr on intermetallic compound layer growth for Sn-Ag-Cu Lead-free Solder joint during isothermal aging

2009 16th IEEE International Symposium on the Physical and Failure Analysis of Integrated Circuits ◽

10.1109/ipfa.2009.5232623 ◽

2009 ◽

Author(s):

Guobiao Su ◽

Yongjiu Han ◽

Chunyan Wang ◽

Hongbin Wang ◽

Xicheng Wei

Keyword(s):

Intermetallic Compound ◽

Solder Joint ◽

Isothermal Aging ◽

Compound Layer ◽

Layer Growth ◽

Lead Free ◽

Intermetallic Compound Layer ◽

Lead Free Solder ◽

Free Solder

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Seed-Free Solid-State Growth of Large Lead-Free Piezoelectric Single Crystals: (Na1/2K1/2)NbO3

Journal of the American Ceramic Society ◽

10.1111/jace.13723 ◽

2015 ◽

Vol 98 (10) ◽

pp. 2988-2996 ◽

Cited By ~ 30

Author(s):

Minhong Jiang ◽

Clive A. Randall ◽

Hanzheng Guo ◽

Guanghui Rao ◽

Rong Tu ◽

...

Keyword(s):

Solid State ◽

Single Crystals ◽

Lead Free ◽

State Growth

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Solder Joint Reliability of Sn-Cu and Sn-Ag-Cu Lead-Free Solder Alloys Solidified on Copper Substrates with Different Surface Roughnesses

Materials Science Forum ◽

10.4028/www.scientific.net/msf.830-831.265 ◽

2015 ◽

Vol 830-831 ◽

pp. 265-269

Author(s):

Satyanarayan ◽

K.N. Prabhu

Keyword(s):

Solder Joint ◽

Solder Matrix ◽

Lead Free ◽

Lead Free Solder ◽

Solder Alloys ◽

Cu Substrate ◽

Cu Substrates ◽

Free Solder ◽

Substrate Surfaces ◽

Lead Free Solders

In the present work, the bond strength of Sn-0.7Cu, Sn-0.3Ag-0.7Cu, Sn-2.5Ag-0.5Cu and Sn-3Ag-0.5Cu lead free solders solidified on Cu substrates was experimentally determined. The bond shear test was used to assess the integrity of Sn–Cu and Sn–Ag–Cu lead-free solder alloy drops solidified on smooth and rough Cu substrate surfaces. The increase in the surface roughness of Cu substrates improved the wettability of solders. The wettability was not affected by the Ag content of solders. Solder bonds on smooth surfaces yielded higher shear strength compared to rough surfaces. Fractured surfaces revealed the occurrence of ductile mode of failure on smooth Cu surfaces and a transition ridge on rough Cu surfaces. Though rough Cu substrate improved the wettability of solder alloys, solder bonds were sheared at a lower force leading to decreased shear energy density compared to the smooth Cu surface. A smooth surface finish and the presence of minor amounts of Ag in the alloy improved the integrity of the solder joint. Smoother surface is preferable as it favors failure in the solder matrix.

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Experimental and numerical fatigue life assessment of SAC305 solders subjected to combined temperature and harmonic vibration loadings

Soldering & Surface Mount Technology ◽

10.1108/ssmt-10-2019-0030 ◽

2020 ◽

Vol 32 (3) ◽

pp. 181-187

Author(s):

Mohammad Gharaibeh

Keyword(s):

Fatigue Life ◽

Compound Layer ◽

Harmonic Vibration ◽

Life Assessment ◽

Lead Free ◽

Intermetallic Compound Layer ◽

Loading Test ◽

Content Type ◽

Vibration Loading ◽

Lead Free Solders

Purpose This paper aims to investigate the fatigue life performance of SAC305 ball grid array solders under combined temperature and harmonic vibration loading conditions. Design/methodology/approach Fatigue tests were performed using a sine dwell with resonance tracking vibration and temperature loading experiment. Finite element stress analysis was also performed to help in understanding the observed failure trends. Findings Fatigue test results showed that the lead-free solders tend to fail quickly in higher temperatures and higher vibration loading test conditions. The failure analysis results revealed that in low temperatures, the solder cracks are initiated and propagated at the package side. However, in high temperatures, the cracks are observed at the board side of the interconnect. In all conditions, the cracks are propagated throughout the intermetallic compound layer. Originality/value In the published literature, there is a lack of data in the area of fatigue assessment of lead-free solders under combined temperature and vibration loadings. This paper provides useful insights into combined thermal/vibration fatigue, i.e. reliability behavior of lead-free solder joint types.

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Non-Metal Reinforced Lead-Free Composite Solder Fabrication Methods and its Reinforcing Effects to the Suppression of Intermetallic Formation: Short Review

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.421.260 ◽

2013 ◽

Vol 421 ◽

pp. 260-266 ◽

Cited By ~ 21

Author(s):

M.A.A. Mohd Salleh ◽

Stuart McDonald ◽

Kazuhiro Nogita

Keyword(s):

Intermetallic Compound ◽

Solder Joint ◽

Composite Solder ◽

Short Review ◽

Lead Free ◽

Nanoparticle Size ◽

Intermetallic Formation ◽

Reinforcing Effects ◽

Lead Free Solders

To increase the solder joint robustness, researches and studies on composite solder carried out by many researchers in an effort to develop viable lead-free solders which can replace the conventional lead-based solders.This paper reviews the fabrication processes of the lead-free composite solder and its non-metal reinforcing effects to the suppression of intermetallic formation. Most researchers using different solder fabrication methods have found that byadditions of non-metal reinforcement from micron up to nanoparticle size had suppressed the intermetallic compound formations of lead-free composite solders.

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Cracking of the Intermetallic Compound Layer in Solder Joints Under Drop Impact Loading

Journal of Electronic Packaging ◽

10.1115/1.4004870 ◽

2011 ◽

Vol 133 (3) ◽

Cited By ~ 9

Author(s):

Tong An ◽

Fei Qin

Keyword(s):

Intermetallic Compound ◽

Solder Joint ◽

Impact Loading ◽

Driving Force ◽

Solder Joints ◽

Compound Layer ◽

Drop Impact ◽

Lead Free ◽

Intermetallic Compound Layer ◽

Crack Driving Force

The significant difference between failure modes of lead-containing and lead-free solder joints under drop impact loading remains to be not well understood. In this paper, we propose a feasible finite element approach to model the cracking behavior of solder joints under drop impact loading. In the approach, the intermetallic compound layer/solder bulk interface is modeled by the cohesive zone model, and the crack driving force in the intermetallic compound layer is evaluated by computing the energy release rate. The numerical simulation of a board level package under drop impact loading shows that, for the lead-containing Sn37Pb solder joint, the damage in the vicinity of the intermetallic compound layer initiates earlier and is much greater than that in the lead-free Sn3.5Ag solder joint. This damage relieves the stress in the intermetallic compound layer and reduces the crack driving force in it and consequently alleviates the risk of the intermetallic compound layer fracturing.

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