Effects of doping trace Ni element on interfacial behavior of Sn/Ni (polycrystal/single-crystal) joints

Purpose The purpose of this article is the effect of doping minor Ni on the microstructure evolution of a Sn-xNi (x = 0, 0.05 and 0.1 wt.%)/Ni (Poly-crystal/Single-crystal abbreviated as PC Ni/SC Ni) solder joint during reflow and aging treatment. Results showed that the intermetallic compounds (IMCs) of the interfacial layer of Sn-xNi/PC Ni joints were Ni3Sn4 phase, while the IMCs of Sn-xNi/SC Ni joints were NiSn4 phase. After the reflow process and thermal aging of different joints, the growth behavior of interfacial layer was different due to the different mechanism of element diffusion of the two substrates. The PC Ni substrate mainly provided Ni atoms through grain boundary diffusion. The Ni3Sn4 phase of the Sn0.05Ni/PC Ni joint was finer, and the diffusion flux of Sn and Ni elements increased, so the Ni3Sn4 layer of this joint was the thickest. The SC Ni substrate mainly provided Ni atoms through the lattice diffusion. The Sn0.1Ni/SC Ni joint increases the number of Ni atoms at the interface due to the doping of 0.1Ni (wt.%) elements, so the joint had the thickest NiSn4 layer. Design/methodology/approach The effects of doping minor Ni on the microstructure evolution of an Sn-xNi (x = 0, 0.05 and 0.1 Wt.%)/Ni (Poly-crystal/Single-crystal abbreviated as PC Ni/SC Ni) solder joint during reflow and aging treatment was investigated in this study. Findings Results showed that the intermetallic compounds (IMCs) of the interfacial layer of Sn-xNi/PC Ni joints were Ni3Sn4 phase, while the IMCs of Sn-xNi/SC Ni joints were NiSn4 phase. After the reflow process and thermal aging of different joints, the growth behavior of the interfacial layer was different due to the different mechanisms of element diffusion of the two substrates. Originality/value In this study, the effect of doping Ni on the growth and formation mechanism of IMCs of the Sn-xNi/Ni (single-crystal) solder joints (x = 0, 0.05 and 0.1 Wt.%) was investigated.

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Reflow of tiny 01005 capacitor/SAC305 solder joints in protective atmosphere

Soldering & Surface Mount Technology ◽

10.1108/ssmt-10-2016-0021 ◽

2017 ◽

Vol 29 (3) ◽

pp. 144-150 ◽

Cited By ~ 4

Author(s):

Yeqing Tao ◽

Dongyan Ding ◽

Ting Li ◽

Jason Guo ◽

Guoliang Fan

Keyword(s):

Solder Joint ◽

Oxygen Concentration ◽

Solder Joints ◽

Protective Atmosphere ◽

Low Oxygen ◽

Reflow Process ◽

Sac305 Solder ◽

Content Type ◽

Placement Accuracy ◽

Component Assembly

Purpose This paper aims to study the influence of reflow atmosphere and placement accuracy on the solderability of 01005 capacitor/SAC305 solder joints. Design/methodology/approach The 01005 capacitors were mounted on OSP-coated pads, and the samples were fabricated in four different atmospheres, i.e. 200 ppm O2/N2, 1,000 ppm O2/N2, 3,000 ppm O2/N2 and air. After the reflow process, visual inspection and X-ray detection were carried out to examine the solder joint shapes and possible defects. Some of the samples fabricated in different conditions were cross-sectioned and the solder joint microstructures were analyzed. On the other hand, besides placing the components on their normal pad positions, a 50 per cent offset of the x-axis (long axis) or y-axis (short axis) was introduced into the chip mounter programs to evaluate the 01005 capacitor’s assembly sensitivity to placement accuracy. The process-induced defects were investigated. Findings Experimental results indicated that an N2-based protective atmosphere was necessary for 01005 type assembly, as it could obviously improve the 01005 solder joint quality, compared with the air condition. The protective atmosphere had little effect on the appearance, quality and microstructure of solder joints when the oxygen concentration was below 3,000 ppm. But a very low oxygen concentration could increase the risk of tombstoning defects for the assembly process. The N2-based protective atmosphere containing 1,000-2000 ppm O2 was acceptable and appropriate for the assembly of tiny components. Originality/value The results of this work provide a set of reflow process parameters and recommendations for 01005 size component assembly in manufacturing.

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Geometric size effect on IMC growth and elements diffusion in Cu/Sn/Cu solder joints

Soldering & Surface Mount Technology ◽

10.1108/ssmt-04-2016-0007 ◽

2017 ◽

Vol 29 (2) ◽

pp. 85-91 ◽

Cited By ~ 6

Author(s):

Yan Zhu ◽

Fenglian Sun

Keyword(s):

Solder Joint ◽

Isothermal Aging ◽

Design Methodology ◽

Solder Joints ◽

Control Element ◽

Correlation Model ◽

Reflow Process ◽

Content Type ◽

Root Cause ◽

Geometric Size

Purpose The purpose of this paper is to investigate the effect of geometric size on intermetallic compound (IMC) growth and elements diffusion of Cu/Sn/Cu solder joint and establish the correlation model between the thickness of the IMC layer and size of the solder joint on the dozens of microns scale. Design/methodology/approach The sandwich-structured Cu/Sn/Cu solder joints with different gaps between two copper-clad plates (δ) are fabricated using a reflow process. The microstructure and composition of solder joints are observed and analyzed by scanning electron microscopy. Findings After reflow, the thickness of the IMC and Cu concentration in solder layers increase with the reduction of δ from 50, 40, 30, 20 to 10 μm. During isothermal aging, the thickness of the IMC fails to increase according to the traditional parabolic rule due to changes in Cu concentration. The reduction of δ is the root cause of changes in Cu concentration and the growth rule of the IMC layer. A correlation model between the thickness of the IMC layer and δ is established. It is found that the thickness of the IMC layer is the function of aging time and δ. With δ reducing, the main control element of IMC growth transfers from Cu to Sn. Originality/value This paper shows the changes of IMC thickness and elements concentration with the reduction of the size of solder joints on the dozens of microns scale. A correlation model is established to calculate the thickness of the IMC layer during aging.

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Microstructure evolution and growth behavior of Cu/SAC105/Cu joints soldered by thermo-compression bonding

Soldering & Surface Mount Technology ◽

10.1108/ssmt-08-2018-0025 ◽

2019 ◽

Vol 31 (4) ◽

pp. 227-232

Author(s):

Mengjiao Guo ◽

F. Sun ◽

Zuozhu Yin

Keyword(s):

Microstructure Evolution ◽

Solder Joints ◽

Growth Behavior ◽

Bonding Process ◽

Effect Of Temperature ◽

Content Type ◽

Interfacial Imcs ◽

Short Time ◽

Cu Dissolution ◽

Bonding Technique

Purpose This paper used a novel technique, which is thermo-compression bonding, and Sn-1.0Ag-0.5Cu solder to form a full intermetallic compound (IMC) Cu3Sn joints (Cu/Cu3Sn/Cu joints). The purpose of the study is to form high-melting-point IMC joints for high-temperature power electronics applications. The study also investigated the effect of temperature gradient on the microstructure evolution and the growth behavior of IMCs. Design/methodology/approach In this paper, the thermo-compression bonding technique was used to form full Cu3Sn joints. Findings Experimental results indicated that full Cu/Cu3Sn/Cu solder joints with the thickness of about 5-6 µm are formed in a short time of 9.9 s and under a low pressure of 0.016 MPa at 450°C by thermo-compression bonding technique. During the bonding process, Cu6Sn5 grew with common scallop-like shape at Cu/SAC105 interfaces, which was followed by the growth of Cu3Sn with planar-like shape between Cu/Cu6Sn5 interfaces. Meanwhile, the morphology of Cu3Sn transformed from a planar-like shape to wave-like shape until full IMCs solder joints were eventually formed during thermo-compression bonding process. Asymmetrical growth behavior of the interfacial IMCs was also clearly observed at both ends of the Cu/SAC105 (Sn-1.0Ag-0.5Cu)/Cu solder joints. Detailed reasons for the asymmetrical growth behavior of the interfacial IMCs during thermo-compression bonding process are given. The compound of Ag element causes a reduction in Cu dissolution rate from the IMC into the solder solution at the hot end, inhibiting the growth of IMCs at the cold end. Originality/value This study used the thermo-compression bonding technique and Sn-1.0Ag-0.5Cu to form full Cu3Sn joints.

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Effect of Thermal Aging on the Microstructure Evolution and Solder Joint Reliability in Hard Disk Drive Under Mechanical Shock

IEEE Transactions on Components and Packaging Technologies ◽

10.1109/tcapt.2008.2007930 ◽

2008 ◽

Vol 31 (4) ◽

pp. 831-836 ◽

Cited By ~ 1

Author(s):

Hongtao Chen ◽

Chunqing Wang ◽

Mingyu Li ◽

Dewen Tian

Keyword(s):

Solder Joint ◽

Hard Disk Drive ◽

Microstructure Evolution ◽

Thermal Aging ◽

Hard Disk ◽

Disk Drive ◽

Mechanical Shock ◽

Solder Joint Reliability ◽

Joint Reliability

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Microstructural evolution and IMCs growth behavior of Sn-58Bi-0.25Mo solder joint during aging treatment

Materials Research Express ◽

10.1088/2053-1591/aaad71 ◽

2018 ◽

Vol 5 (2) ◽

pp. 026304

Author(s):

Li Yang ◽

Lu Zhu ◽

Yaocheng Zhang ◽

Shiyuan Zhou ◽

Yifeng Xiong ◽

...

Keyword(s):

Solder Joint ◽

Microstructural Evolution ◽

Aging Treatment ◽

Growth Behavior ◽

Imcs Growth

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Anisotropic Behavior of Single Grain Cu6Sn5 Intermetallic

Volume 10: Micro- and Nano-Systems Engineering and Packaging ◽

10.1115/imece2014-40196 ◽

2014 ◽

Author(s):

Soud Farhan Choudhury ◽

Leila Ladani

Keyword(s):

Grain Size ◽

Yield Strength ◽

Solder Joint ◽

Single Crystal ◽

Solder Joints ◽

Reflow Process ◽

Plastic Properties ◽

Growth Orientation ◽

Loading Direction ◽

Single Grain

Intermetallic (IMC) layers (Cu6Sn5 and Cu3Sn) are an essential component of a solder joint for good metallurgical bonding. However, the mechanical and physical properties of IMC layers differ significantly from the solder and substrate, and excessive IMC layers can lower the reliability of solder joints due to their brittle nature. Moreover, continuous miniaturization of packages and joints has increased the volume fraction of IMCs to a point where smaller joints could be completely composed of IMCs. Further miniaturization of joints may result in statistical grain size effects. One of the most common types of IMCs in microelectronic joints is Cu6Sn5, which is formed in a variety of bonding materials with different compositions of Sn, Cu, and Ag. Due to its large percentage of volume in solder joint; to predict the reliability of micro solder joints, it is necessary to characterize single crystal Cu6Sn5 IMC completely. This study reports the information on grain growth orientation and elastic-plastic properties such as young’s modulus, hardness, yield strength and strain hardening exponent of single grain of Cu6Sn5 in Sn-3.5Ag/Cu solder alloy system. IMCs materials were grown using reflow process using an experiment in which the time and temperature of reflow process was varied. Electron backscatter diffraction (EBSD) analysis was conducted after the reflow to measure the grain size and determine the preferred grain orientation. It was found that the growth orientation is in the orientation of the c-axis. Nanoindentation was carried out in 4 individual grains with different crystallographic orientation along normal to the growth axis to determine the elastic properties of Cu6Sn5 single crystal. Plastic properties were predicted using the nanoindentation results and Dao reverse analysis model. The results indicate that the hardness for Cu6Sn5 grains with different orientation along normal to growth axis is statistically indistinguishable. Lower elastic modulus was observed for a grain with [010] direction parallel to the loading direction. Yield strength of a grain with (001) plane parallel to the loading direction was slightly lower than other grain orientations. Overall, the experimental results obtained were found to be within the range shown in the literature.

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Microstructure evolution and shear strength of full Cu3Sn- microporous copper composite joint by thermo-compression bonding

Soldering & Surface Mount Technology ◽

10.1108/ssmt-10-2020-0047 ◽

2021 ◽

Vol ahead-of-print (ahead-of-print) ◽

Author(s):

F Sun ◽

Zhen Pan ◽

Yang Liu ◽

Xiang Li ◽

Haoyu Liu ◽

...

Keyword(s):

Shear Strength ◽

High Temperature ◽

Microstructure Evolution ◽

Composite Solder ◽

Growth Behavior ◽

Composite Joints ◽

Content Type ◽

Composite Joint ◽

Cu Substrates ◽

Copper Composite

Purpose The purpose of this paper is to quickly manufacture full Cu3Sn-microporous copper composite joints for high-temperature power electronics applications and study the microstructure evolution and the shear strength of Cu3Sn at different bonding times. Design/methodology/approach In this paper, a novel structure of Cu/composite solder sheet/Cu was designed. The composite solder sheet was made of microporous copper filled with Sn. The composite joint was bonded by thermo-compression bonding under pressure of 0.6 MPa at 300°C. The microstructure evolution and the growth behavior of Cu3Sn at different bonding times were observed by electron microscope and metallographic microscope. The shear strength of the joint was measured by shear machine. Findings At initial bonding stage the copper atoms in the substrate and the copper atoms in the microporous copper dissolved into the liquid Sn. Then the scallop-liked Cu6Sn5 phases formed at the interface of liquid Sn/microporous copper and liquid Sn/Cu substrates. During the liquid Sn changing to Cu6Sn5 phases, Cu3Sn phases formed and grew at the interface of Cu6Sn5/Cu substrates and Cu6Sn5/microporous copper. After that the Cu3Sn phases continued to grow and the Cu3Sn-microporous copper composite joint with a thickness of 100 µm was successfully obtained. The growth rule of Cu3Sn was parabolic growth. The shear strength of the composite joints was about 155 MPa. Originality/value This paper presents a novel full Cu3Sn-microporous copper composite joint with high shear strength for high-temperature applications based on transient liquid phase bonding. The microstructure evolution and the growth behavior of Cu3Sn in the composite joints were studied. The shear strength and the fracture mechanism of the composite joints were studied.

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