Investigation on the Interfacial IMCs Layer of Sn-58Bi/Cu Solder Joints

Purpose The purpose of this paper is to investigate the effect of fullerene (FNS) reinforcements on the microstructure and mechanical properties of 96.5Sn3Ag0.5Cu (SAC305) lead-free solder joints under isothermal ageing and electrical-migration (EM) stressing. Design/methodology/approach In this paper, SAC305 solder alloy doped with 0.1 Wt.% FNS was prepared via the powder metallurgy method. A sandwich-like sample and a U-shaped sample were designed and prepared to conduct an isothermal ageing test and an EM test. The isothermal ageing test was implemented under vacuum atmosphere at 150°C, whereas the EM experiment was carried out with a current density of 1.5 × 104 A/cm2. The microstructural and mechanical evolutions of both plain and composite solder joints after thermal ageing and EM stressing were comparatively studied. Findings A growth of Ag3Sn intermetallic compounds (IMCs) in solder matrix and Cu-Sn interfacial IMCs in composite solder joints was notably suppressed under isothermal ageing condition, whereas the hardness and shear strength of composite solder joints significantly outperformed those of non-reinforced solder joints throughout the ageing period. The EM experimental results showed that for the SAC305 solder, the interfacial IMCs formulated a protrusion at the anode after 360 h of EM stressing, whereas the surface of the composite solder joint was relatively smooth. During the stressing period, the interfacial IMC on the anode side of the plain SAC305 solder showed a continuous increasing trend, whereas the IMC at the cathode presented a decreasing trend for its thickness as the stressing time increased; after 360 h of stressing, some cracks and voids had formed on the cathode side. For the SAC305/FNS composite solder, a continuous increase in the thickness of the interfacial IMC was found on both the anode and cathode sides; the growth rate of the interfacial IMC at the anode was higher than that at the cathode. The nanoindentation results showed that the hardness of the SAC305 solder joint presented a gradient distribution after EM stressing, whereas the hardness data showed a relatively homogeneous distribution in the SAC305/FNS solder joint. Originality/value The experimental results showed that the FNS reinforcement could effectively mitigate the failure risk in solder joints under isothermal ageing and high-current stressing. Specifically, the FNS particles in solder joints can work as a barrier to suppress the diffusion and migration of Sn and Cu atoms. In addition, the nanoidentation results also indicated that the addition of the FNS reinforcement was very helpful in maintaining the mechanical stability of the solder joint. These findings have provided a theoretical and experimental basis for the practical application of this novel composite solder with high-current densities.

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Formation of Kirkendall Voids at Low and High Aging Temperature in the Sn-0.7Cu-1.0wt.%Si3N4/Cu Solder Joints

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.1107.577 ◽

2015 ◽

Vol 1107 ◽

pp. 577-581

Author(s):

Norainiza Saud ◽

Flora Somidin ◽

Najib Saedi Ibrahim ◽

Mohd Arif Anuar Mohd Salleh

Keyword(s):

Solid State ◽

Low Temperature ◽

Aging Time ◽

Aging Temperature ◽

Solder Joints ◽

The Other ◽

Imcs Layer ◽

High Aging Temperature ◽

Kirkendall Voids ◽

Soldered Joint

The intermetallic compounds (IMCs) layer formed between Sn-0.7Cu-1.0wt.%Si3N4(SC-1.0SN) solder and Cu-substrate were investigated through isothermal solid-state aging. The SC-1.0SN/Cu solder joints were aged at 50°C and 150°C for 24h, 240h, 480h and 720h duration after reflow. The as-soldered joint IMC formed at interface was Cu6Sn5. In addition, only Cu6Sn5layer was observed at the interface of the samples aged at low temperature of 50°C although the aging duration was prolonged up to 720h and has begun to increase in thickness. On the other hand, the Cu3Sn layer was clearly observed in the sample of aged at 150°C up to 240h. However, at least no voids were vividly observed in the 50°C aged samples, while kirkendall voids were clearly found in Cu3Sn layer of samples aged at 150°C up to 480h of aging time will be discussed further.

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Influence of Interfacial Intermetallic Growth on the Mechanical Properties of Sn-37Pb Solder Joints under Extreme Temperature Thermal Shock

Applied Sciences ◽

10.3390/app8112056 ◽

2018 ◽

Vol 8 (11) ◽

pp. 2056 ◽

Cited By ~ 4

Author(s):

Chunjin Hang ◽

Ruyu Tian ◽

Liyou Zhao ◽

Yanhong Tian

Keyword(s):

Thermal Shock ◽

Solder Joints ◽

Extreme Temperature ◽

Bulk Diffusion ◽

Thermal Shock Test ◽

Interfacial Imcs ◽

Deep Space Exploration ◽

Pull Strength ◽

Quad Flat Package ◽

Interfacial Intermetallic Compounds

Solder joints in thermally uncontrolled microelectronic assemblies have to be exposed to extreme temperature environments during deep space exploration. In this study, extreme temperature thermal shock test from −196 °C to 150 °C was performed on quad flat package (QFP) assembled with Sn-37Pb solder joints to investigate the evolution and growth behavior of interfacial intermetallic compounds (IMCs) and their effect on the pull strength and fracture behavior of Sn-37Pb solder joints under extreme temperature environment. Both the scallop-type (Cu, Ni)6Sn5 IMCs at the Cu lead side and the needle-type (Ni, Cu)3Sn4 IMCs at the Ni-P layer side changed to plane-type IMCs during extreme temperature thermal shock. A thin layer of Cu3Sn IMCs was formed between the Cu lead and (Cu, Ni)6Sn5 IMC layer after 150 cycles. The growth of the interfacial IMCs at the lead side and the Ni-P layer side was dominated by bulk diffusion and grain-boundary diffusion, respectively. The pull strength was reduced about 31.54% after 300 cycles. With increasing thermal shock cycles, the fracture mechanism changed from ductile fracture to mixed ductile–brittle fracture, which can be attributed to the thickening of the interfacial IMCs, and the stress concentration near the interface caused by interfacial IMC growth.

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Influence of ultrasounds on interfacial microstructures of Cu-Sn solder joints

Soldering & Surface Mount Technology ◽

10.1108/ssmt-06-2020-0026 ◽

2021 ◽

Vol ahead-of-print (ahead-of-print) ◽

Author(s):

Xu Han ◽

Xiaoyan Li ◽

Peng Yao ◽

Dalong Chen

Keyword(s):

Design Methodology ◽

Solder Joints ◽

Nucleation And Growth ◽

Content Type ◽

Reaction Stage ◽

Interfacial Imcs ◽

Soldering Process ◽

Liquid Reaction ◽

Ultrasonic Assisted ◽

Solid Liquid

Purpose This study aims to investigate the interfacial microstructures of ultrasonic-assisted solder joints at different soldering times. Design/methodology/approach Solder joints with different microstructures are obtained by ultrasonic-assisted soldering. To analyze the effect of ultrasounds on Cu6Sn5 growth during the solid–liquid reaction stage, the interconnection heights of solder joints are increased from 30 to 50 μm. Findings Scallop-like Cu6Sn5 nucleate and grow along the Cu6Sn5/Cu3Sn interface under the traditional soldering process. By comparison, some Cu6Sn5 are formed at Cu6Sn5/Cu3Sn interface and some Cu6Sn5 are randomly distributed in Sn when ultrasonic-assisted soldering process is used. The reason for the formation of non-interfacial Cu6Sn5 has to do with the shock waves and micro-jets produced by ultrasonic treatment, which leads to separation of some Cu6Sn5 from the interfacial Cu6Sn5 to form non-interfacial Cu6Sn5. The local high pressure generated by the ultrasounds promotes the heterogeneous nucleation and growth of Cu6Sn5. Also, some branch-like Cu3Sn formed at Cu6Sn5/Cu3Sn interface render the interfacial Cu3Sn in ultrasonic-assisted solder joints present a different morphology from the wave-like or planar-like Cu3Sn in conventional soldering joints. Meanwhile, some non-interfacial Cu3Sn are present in non-interfacial Cu6Sn5 due to reaction of Cu atoms in liquid Sn with non-interfacial Cu6Sn5 to form non-interfacial Cu3Sn. Overall, full Cu3Sn solder joints are obtained at ultrasonic times of 60 s. Originality/value The obtained microstructure evolutions of ultrasonic-assisted solder joints in this paper are different from those reported in previous studies. Based on these differences, the effects of ultrasounds on the formation of non-interfacial IMCs and growth of interfacial IMCs are systematically analyzed by comparing with the traditional soldering process.

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Impact of Thermal Aging on the Growth of Cu-Sn Intermetallic Compounds in Pb-Free Solder Joints in 2512 Resistors

Volume 5: Electronics and Photonics ◽

10.1115/imece2009-10169 ◽

2009 ◽

Cited By ~ 3

Author(s):

Preeti Chauhan ◽

Michael Osterman ◽

Michael Pecht

Keyword(s):

Intermetallic Compounds ◽

Thermal Aging ◽

Room Temperature ◽

Elevated Temperatures ◽

Solder Joints ◽

Material Behavior ◽

Sac305 Solder ◽

Interfacial Imcs ◽

Aging Conditions ◽

The Impact

Interfacial intermetallic compounds (IMCs) in solder joints are formed during soldering and continue to grow after assembly. Excessive interfacial IMC growth may impact the reliability of solder interconnections due to changes in material behavior. The impact of thermal aging on IMC growth can be determined by subjecting assemblies to elevated temperatures and determining the interfacial IMC growth. This paper discusses the interfacial IMCs formed in the solder-Cu interface for SAC305, SAC105, and Sn-0.7Cu-0.05Ni+Ge (SN100C) assemblies. Test assemblies were produced using tin-finished 2512 resistors soldered onto OSP-finished copper lands. The assemblies were subjected to aging conditions of 100°C for 24 h and 600 h; and 150°C for 24 h and the impact of high temperature aging on the thickness of IMCs formed at solder-Cu interface was studied. Samples stored at room temperature for 600 h were the reference specimen for the experiment. The IMC growth observed in the lead-free solders was compared with that in eutectic SnPb. Interfacial IMCs formed in room temperature conditioned specimens were scallop shaped and non-uniform. The IMC structure evolved with aging temperature and duration resulting in smoother and more uniform IMCs in 100°C/600 h aged samples. A comparison of IMC thickness in the solders at given aging conditions revealed that SAC305 exhibited highest IMC thickness, followed by SAC105 and SN100C. SnPb showed the least IMC thickness at all aging conditions except at 150°C for 24 h. At this condition, SnPb showed IMC thickness comparable to SAC305 solder and was higher than other solders.

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Effect of Au-Sn IMCs’ formation and morphologies on shear properties of laser reflowed micro-solder joints

Soldering & Surface Mount Technology ◽

10.1108/ssmt-07-2014-0016 ◽

2015 ◽

Vol 27 (1) ◽

pp. 45-51 ◽

Cited By ~ 13

Author(s):

Wei Liu ◽

Rong An ◽

Chunqing Wang ◽

Yanhong Tian

Keyword(s):

Ductile Fracture ◽

Solder Joints ◽

Test System ◽

Imcs Layer ◽

Shear Properties ◽

Content Type ◽

Fracture Surfaces ◽

Solder Balls ◽

Shear Performance ◽

Nearly Continuous

Purpose – The purpose of this paper is to investigate the effect of typical morphologies of Au-Sn IMCs (intermetallic compounds) at the interfaces of solder and pads on shear properties of laser reflowed micro-solder joints. Design/methodology/approach – Sn-2.0Ag-0.75Cu-3.0Bi (SnAgCuBi) solder balls (120 μm in diameter), pads with 0.1, 0.5, 0.9 or 4.0 μm thickness of Au surface finish, and different laser input energies were utilized to fabricate micro-solder joints with Au-Sn IMCs having different typical morphologies. The joints were performed by a shear test through a DAGE bond test system. Fracture surfaces of the joints were analyzed by scanning electron microscopy and energy-dispersive X-ray spectrometry to identify fracture modes and locations. Findings – Morphologies of Au-Sn IMCs would affect shear properties of the joints remarkably. When needle-like AuSn4 IMCs formed at the interfaces of solder and pads, almost entire surfaces presented the manner of ductile fracture. Moreover, shear forces of this kind of solder joints were higher than those of joints without Au-Sn IMCs or with a nearly continuous/continuous Au-Sn IMCs layer. The reason was that the shear performance of the solder joints with needle-like AuSn4 IMCs was enhanced by an interlocking effect between solder and needle-like AuSn4 IMCs. As a nearly continuous or continuous Au-Sn IMCs layer formed, the fracture surfaces presented more character of brittle than ductile fracture. However, if an Au layer still remained under Au-Sn IMCs, the shear performance of the joints would be enhanced. Originality/value – The results in this study can be used to optimize microstructures and shear properties of laser reflowed micro-solder joints.

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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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Relationship between Nanomechanical Responses of Interfacial Intermetallic Compound Layers and Impact Reliability of Solder Joints

Nanomaterials ◽

10.3390/nano10081456 ◽

2020 ◽

Vol 10 (8) ◽

pp. 1456

Author(s):

Jenn-Ming Song ◽

Bo-Chang Huang ◽

David Tarng ◽

Chih-Pin Hung ◽

Kiyokazu Yasuda

Keyword(s):

High Speed ◽

Solder Joints ◽

Impact Load ◽

Substrate Material ◽

Joint Interface ◽

Impact Performance ◽

Interfacial Imcs ◽

High Speed Impact ◽

Reliability Of Solder Joints ◽

Impact Reliability

This study aims to evaluate solder joint reliability under high speed impact tests using nanoindentation properties of intermetallic compounds (IMCs) at the joint interface. Sn–Ag based solder joints with different kinds of interfacial IMCs were obtained through the design of solder alloy/substrate material combinations. Nanoindentation was applied to investigate the mechanical properties of IMCs, including hardness, Young’s modulus, work hardening exponent, yield strength, and plastic ability. Experimental results suggest that nanoindentation responses of IMCs at joint interface definitely dominates joint impact performance. The greater the plastic ability the interfacial IMC exhibits, the superior impact energy the solder joints possess. The concept of mechanical and geometrical discontinuities was also proposed to explain brittle fracture of the solder joints with bi-layer interfacial IMCs subject to impact load.

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