Search results

This study aims to investigate the interfacial microstructures of ultrasonic-assisted solder joints at different soldering times.

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.

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.

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.

This paper aims to investigate the effects of different ultrasonic-assisted loading degrees on the microstructure, mechanical properties and the fracture morphology of Cu/Zn+15%SAC0307+15%Cu/Al solder joints.

A new method in which 45 μm Zn particles were mixed with 15% 500 nm Cu particles and 15% 500 nm SAC0307 particles as solders (SACZ) and five different ultrasonic loading degrees were applied for realizing the soldering between Cu and Al at 240 °C and 8 MPa. Then, SEM was used to observe and analyze the soldering seam, interface microstructure and fracture morphology; the structural composition was determined by EDS; the phase of the soldering seam was characterized by XRD; and a PTR-1102 bonding tester was adopted to test the average shear strength.

The results manifest that Al–Zn solid solution is formed on the Al side of the Cu/SACZ/Al joints, while the interface IMC (Cu₅Zn₈) is formed on the Cu side of the Cu/SACZ/Al joints. When single ultrasonic was used in soldering, the interface IMC (Cu₅Zn₈) gradually thickens with the increase of ultrasonic degree. It is observed that the proportion of Zn or ZnO areas in solders decreases, and the proportion of Cu–Zn compound areas increases with the variation of ultrasonic degree. The maximum shear strength of joint reaches 46.01 MPa when the dual ultrasonic degree is 60°. The fracture position of the joint gradually shifts from the Al side interface to the solders and then to the Cu side interface.

The mechanism of ultrasonic action on micro-nanoparticles is further studied. By using different ultrasonic loading degrees to realize Cu/Al soldering, it is believed that the understandings gained in this study may offer some new insights for the development of low-temperature soldering methodology for heterogeneous materials.

This study aims to research properties of Cu/SAC0307 mixed solder balls/Al joints with different bonding temperature under ultrasonic-assisted.

A new method that 1 mm Zn particles and Sn-0.3Ag-0.7 (SAC0307) with a particle size of 25–38 mm were mixed to fill the joint and successfully achieved micro-joining of Cu/Al under ultrasonic-assisted.

The results indicated that when the bonding temperature was 180°C, there was only one layer of CuZn₅ intermetallic compounds (IMCs) at the Cu interface. However, when the bonding temperature was 190°C, 200°C and 210°C, the Cu interface IMCs had two layers: for one layer, the IMCs near the Cu substrate were Cu₅Zn₈ and for another layer, the IMCs near the solder were CuZn₅. In addition, the thickness of the Cu interfacial IMCs increased with the bonding temperature. In particular, the thickness of IMCs at the Cu interface of the Cu/Al joints soldered at 210°C was 4.6 µm, which increased by 139.6% compared with that of the Cu/Al joints soldered at 180°C. However, there was no IMC layer at the Al interface, but there might be a Zn–Al solid solution layer. The shear strength of Cu/Al joints soldered at 180°C was only 15.01 MPa, but as the soldering temperature continued to increase, the shear strength of the Cu/Al joints increased rapidly. When the soldering temperature was 200°C, the shear strength of the Cu/Al joints reached the maximum of 38.07 MPa, which was 153.6% higher than that at 180°C. When the soldering temperature was 180°C, the fracture of Cu/Al joints was mainly on the Al side. However, when soldering temperature was 190°C, 200°C and 210°C, the fracture of Cu/Al joints was mainly broken in the Zn particles layer.

A new method that 1 mm Zn particles and Sn-0.3Ag-0.7 (SAC0307) with a particle size of 25–38 mm were mixed to fill the Cu/Al joint at 210°C.

This study aims to evaluate the effect of thermal aging temperature on the properties of Cu/Cu joints.

A new method that 1 um Zn-particles and Sn-0.3Ag-0.7Cu (SAC0307) with a particle size of 25–38 µm were mixed to fill the joint and successfully achieved the micro-joining of Cu/Cu under ultrasonic-assisted at low-temperature, and then the effect of thermal aging temperature on the properties of Cu/Cu joints was researched.

The composition of the intermetallic compounds (IMCs) on the upper and lower interfaces of Cu/SACZ/Cu joints remained unchanged, which was Cu₅Zn₈ in aging process, and the thickness of the IMCs on the upper and lower interfaces of the Cu/SACZ/Cu joints increased accordingly. Compared with the as-received joints, the thickness of the upper and lower interfaces IMCs of the soldering aged time for 24 h increased by 404.7% and 505.5% at 150ºC, respectively. The IMCs formation tendency and the IMCs growth rate of the lower interface are larger than those of the upper interface because the soldering seam near the IMCs at the upper and lower interfaces of the as-received joints were mostly white SAC0307 balls black Zn-particles, respectively. The growth activation energy of IMCs in the upper and lower interfaces is about 89.21 and 55.11 kJ/mol, respectively. Under the same aging time, with the increase of the aging temperature, the shear strength of Cu/SACZ/Cu joints did not change significantly at first before 150ºC. When the aging temperature reached 150ºC, the shear strength of the joints decreased significantly; the shear strength of the joints was the smallest at 150ºC for 24 h, which was 39.4% lower than that of the as-received joints because the oxidation degree of Zn particles in the joint with the increase of aging temperature and time.

Cu/Cu joints were successfully achieved under ultrasonic-assisted at low-temperature.

Low-Ag SAC solder will lead to a series of problems, such as increased the melting range and declined the solderability and so on. These research studies do not have too much impact on the improvement of solders’ performance but were difficult to achieve satisfactory results. It is urgent to develop new soldering technology to avoid the bottleneck of lead-free solder. low-temperature-stirring soldering and ultrasonic-assisted soldering was developed in the authors’ early work, but slag inclusion and pore would gather and grow up to lead decreasing of the shear strength. In this paper, Cu/SAC0307 +Zn power/Cu joints with ultrasonic-assisted at low-temperature was successfully achieved.

45um Zn-powder and SAC0307 No.4 solder powder were mixed to fill the Cu-Cu joint, and the content of Zn-powder were 0 and 5%, 7.5% and 10%, 12.5% and 15% respectively. During the soldering process under ambient atmosphere %252C the heating platform provided a constant 220%253 F and the ultrasonic vibrator applied a constant pressure of 4 MPa to the copper substrate. The soldering process was completed after holding 70 s at 300 W.

The Zn particles made the IMC at the joint interface and in the soldering seam from scallop-type Cu₆Sn₅ to flat-type Cu₅Zn₈. The shear strength of joints without Zn was only 12.43 MPa, the shear strength of joints with 10% Zn reached a peak of 34.25 MPa, and the shear strength of joints containing 10% Zn was 63.71% higher than that of joints without zinc particles, and then the shear strength decreased. In addition, with the increase of zinc content, the fracture mode of the joint changed from the brittle fracture of the original layered tears to the mixed tough and brittle fracture.

A new method that Zn micron-size powders and SAC0307 micron-size powders was mixed to fill the joint, and successfully achieved micro-joining of Cu/Cu under ultrasonic-assisted without flux at low-temperature.

This study aims to research properties of Cu/SAC0307 mixed solder balls/Cu joints with different Zn-particles content at low-temperature under ultrasonic assisted.

A new method that 1µm Zn particles and Sn-0.3Ag-0.7 (SAC0307) with a particle size of 25–38 µm were mixed to fill the joint and successfully achieved micro-joining of Cu/Cu under ultrasonic-assisted at low temperature.

The results showed that with a continuous increase in the Zn-particle content, the interfacial intermetallic compounds (IMCs) of the upper and lower interfaces of joints gradually changed from scallop-shaped Cu₆Sn₅ to wavy-shaped Cu₅Zn₈. Moreover, the IMC thickness of the upper/lower interface of joints first decreased and then increased with increasing Zn-particle content. The shear strengths of joints increased with Zn-particle content, the shear strength of joints went to a maximum of 29.76 MPa when the Zn-particle content was 40%, an increase of 62.6% compared to joints without Zn particles. However, as the Zn-particle content continued to increase, the shear strengths of the joints decreased. Additionally, when the Zn content increased to 50%, because the oxidation degree of Zn particles increased, the joints were mainly broken among Zn particles.

A new method that 1µm Zn particles and Sn-0.3Ag-0.7 (SAC0307) with a particle size of 25–38 µm were mixed to fill the Cu/Cu joint at 180°C.

This study aims to investigate the effect of ultrasound on interfacial microstructures and growth kinetics of intermetallic compounds (IMCs) at different temperatures.

To investigate the effect of ultrasound on IMCs growth quantitatively, the cross-sectional area of IMCs layers over a confirmed length was obtained for calculating the thickness of the IMCs layer.

The generation of dimensional difference in normal direction between Cu₆Sn₅ and its adjacent Cu₆Sn₅, formation of bossed Cu₆Sn₅ and non-interfacial Cu₆Sn₅ in ultrasonic solder joints made the interfacial Cu₆Sn₅ layer present a non-scallop-like morphology different from that of traditional solder joints. At 260°C and 290°C, the Cu₃Sn layer presented a wave-like shape. In contrast, at 320°C, the Cu₃Sn in ultrasonic solder joints consisted of non-interfacial Cu₃Sn and interfacial Cu₃Sn with a branch-like shape. The Cu₆Sn₅/Cu₃Sn boundary and Cu₃Sn/Cu interface presented a sawtooth-like shape under the effect of ultrasound. The predominant mechanism of ultrasonic-assisted growth of Cu₆Sn₅ growth at 260°C, 290°C and 320°C involved the grain boundary diffusion accompanied by grain coarsening. The Cu₃Sn growth was controlled by volume diffusion during the ultrasonic soldering process at 260°C and 290°C. The diffusion mechanism of Cu₃Sn growth transformed to grain boundary diffusion accompanied by grain coarsening when the ultrasonic soldering temperature was increased to 320°C.

The microstructural evolution and growth kinetics of IMCs in ultrasonically prepared ultrasonic solder joints at different temperatures have rarely been reported in previous studies. In this study, the effect of ultrasound on microstructural evolution and growth kinetics of IMCs was systematically investigated.

This study aims to evaluate the effect of thermal aging temperature on the properties of Cu/Al joints.

A new method in which 1 µm Zn-particles and SAC0307 with a particle size of 25–38 µm were mixed to fill the joint and successfully achieved the micro-joining of Cu/Al under ultrasonic-assisted at 200°C, and then, the effect of aging temperature on the properties of Cu/Al joints at different aging times was researched.

The results showed that the Cu interface intermetallic compounds (IMCs) had the same composition and had two layers with Cu₅Zn₈ near the Cu substrate and CuZn₅ near the solder. As the aging time increased, CuZn₅ gradually transformed to Cu₅Zn₈, and the thickness of the CuZn₅ layer gradually decreased until CuZn₅ disappeared completely. There was a Sn–Zn solid solution at the Al interface, and the composition of the Al interface of the Cu/Al joints did not change with changing temperature. The IMC thickness at the Cu interface of the joints continued to increase, and the shear strength of the Cu/Al joints decreased with increasing aging temperature and time. Compared with the as-received samples, the IMC thickness of the Cu interface of joints increased by 371.8% and the shear strength of the Cu/Al joints was reduced by 83.2% when the joints were aged at 150°C for 24 h. With an increase in aging temperature, the fracture mode of the Cu/Al joints changed from being between solder balls and Zn particles to between Zn particles.

With increasing aging temperature, the shear strengths of the Cu/SACZ/Al joints decreased at the same aging time, the shear strength of Cu/SACZ/Al joints at 150°C for 24h decreased by 83.2% compared with that of the as-received joints.

This paper aims to investigate the effect of ultrasonic vibration (USV) on the evolution of intermetallic compounds (IMCs), grain morphology and shear strength of soldered Ni/Sn/Ni samples.

The Ni/Sn/Ni joints were obtained through ultrasonic-assisted soldering. The formation of IMCs, their composition, grain morphology and the fractured-surface microstructures from shear tests were characterized using scanning electron microscopy and energy-dispersive x-ray spectroscopy.

Without USV, a planar interfacial Ni₃Sn₄ layer was formed at the Ni/Sn interface, and a few Ni₃Sn₄ grains were distributed in the soldered joint. The morphology of these grains was needle-shaped. With USV, several grooves were formed at the interfacial Ni₃Sn₄ layer due to ultrasonic cavitation. Some deepened grooves led to “neck” connections at the roots of the Ni₃Sn₄ grains, which accelerated the strong detachment of Ni₃Sn₄ from the substrate. In addition, two types of Ni₃Sn₄ grains, needle-shaped and granular-shaped, were observed at the interface. Furthermore, the shear strength increased with longer USV time, which was attributed to the thinning of the interfacial IMC layers and dispersion strengthening from the Ni₃Sn₄ particles distributed evenly in the joint.

The novelty of the paper is the detailed study of the effect of USV on the morphology, size changes of interfacial IMC and joint strength. This provides guidance for the application of ultrasonic-assisted soldering in electronics packaging.

In present research work, the effects of rotational speed, feed rate and vibration amplitude have been investigated during novel method of ultrasonic-assisted bone grinding. During dissection of tumors, firstly a bone flap is removed near the target region to create passage for grinding burr. During abrasion, heat is produced, which sometimes increases the temperature to unsafe levels. So, efforts have been made to limit the temperature below the threshold levels of osteonecrosis during bone grinding.

The temperature produced during osteotomy has been measured using infrared thermography camera during the implementation of L18 Taguchi orthogonal array design. Subsequently, main effect plots and contour plots have been presented to analyze and visualize the effect of grinding parameters on temperature rise during bone grinding. Furthermore, the process parameters have been optimized for optimum results for response characteristics using Taguchi SN ratio-based optimization methodology. For multiobjective optimization, the process parameters are further optimized using grey relational analysis.

It is revealed that all three process parameters substantially affect the response characteristics. The proposed optimization methodology is successfully applied on the experimental findings and the optimum results for change in temperature are found to be rotational speed = 3,000 rpm, feed rate = 20 mm/min, amplitude = 10 µm and for standard deviation are 5,000 rpm, 60 mm/min, 10 µm.

The present research findings cannot be generalized, and researchers are encouraged to further investigate the proposed rotary ultrasonic-assisted bone grinding at higher rotational speed up to 60k rpm on the skull bone.

The research on osteotomy is still at its initial phase, and continuous research is carried out for making patients’ life comfortable. In this direction, the authors have proposed a novel osteotomy method to limit the temperature below the threshold limit of osteonecrosis. The outcomes of the present study will be beneficial for the neurosurgeons working in this field.