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The purpose of this paper is to investigate the wettability of an active Sn2Ti solder on an Al₂O₃ ceramic material at temperatures of 700°C and higher. Based on the results of the wettability study, soldered joints of Al₂O₃ ceramics/Sn2Ti solder/steel type AISI 321 were fabricated and the variation of shear strength with time was determined.

For determining melting points, differential scanning calorimetry analysis was performed. The wetting angle of Sn2Ti solder on Al₂O₃ ceramics was measured using specially developed equipment with a 10‐3 Pa vacuum at temperatures of 700, 800, 850 and 900°C. The wetting angle on AISI 321 steel at a temperature of 850°C was also determined. The joints of Al₂O₃ ceramics/Sn2Ti solder/steel type AISI 321 were prepared at 900°C, in a vacuum for times 5, 10, 15 and 20 min.

The best wettability of Sn2Ti solder was achieved at a temperature of 900°C. The wetting angle at the parameter of 900°C/ for 15 min was 47.5°. The joints of Al₂O₃ ceramics/Sn2Ti solder/steel type AISI 321 attained a strength of 18.3 MPa. It was found that the microstructure of Sn2Ti solder consists of a tin matrix with the presence of a αTi6Sn5 phase.

The results of the work are of significance for the further development of soldering with active solders in a vacuum, as well as with the application of power ultrasound. The possibility of soldering Al₂O₃ ceramics with SnTi‐based solders was thus demonstrated.

The work aims to study the direct bonding of silicon substrate with solders type Sn-Ag-Ti.

During the bonding process with ultrasound assistance, the active element (Ti,Ce,Mg) is distributed from the solder to interface with a silicon substrate, where it supports the bond formation.

Formation of a reaction layer, 1-2 μm in thickness, was observed. The new Si2Ti phases and Mg2Si phase were identified in the reaction layer.

The results of analysis suggest that the Si/Sn-Ag-Ti joint is of diffusion character. The highest average strength on silicon substrate (39 MPa) was achieved with Sn-Ag-Ti(Mg) solder.

This paper aims to investigate the effect of solder alloying with a small amount of La and Y on bond formation with the Si and Cu substrates.

Bi₂La and Bi₂Y solders were studied. Soldering was performed using a fluxless method in air and with ultrasonic activation.

It was found that in the process of ultrasonic soldering, the La and Y were distributed at the interface with Si and Cu substrates, which enhanced the bond formation. Addition of La or Y elements in a Bi-based solder also ensured wetting of non-metallic materials such as Si, Al₂O₃ and SiC ceramics.

The addition of lanthanides offers a method for ensuring wetting of non-metallic materials. The bond with Si was of an adhesive character without the formation of a new contact interlayer. This resulted in lower shear strength of the bond with Si (8-10 MPa). The shear strength of the bond with a Cu substrate was 22-30 MPa.

The loss of reliability of a PTH soldered joint caused by unnecessary re‐working after wave soldering is considered. Standardised joints are re‐worked under conditions that closely control the temperature of the soldering iron tip, the time of contact of the tip to the joint, the angle and the contact pressure of the soldering iron, the amount of flux and the amount of extra solder applied. The service life of the joints is assessed using accelerated thermal cycling between ‐20°C and +100°C. In all cases, the service life of these test joints is degraded by re‐working. The effect becomes worse when the temperature and time of re‐work are increased. The degradation of fatigue performance is associated with changes in the solder fillet microstructure. The effects on fatigue performance of changing the fillet size by adding extra solder during re‐work are complex, but explainable in general terms. The results obtained from the controlled laboratory rework tests are corroborated by test assemblies re‐worked to companies' in‐house workmanship standards and by field data.

This study aims to solder AlN ceramics with a Cu substrate using an active type Sn-Ag-Ti solder. Soldering was performed with power ultrasound. The Sn3.5Ag2Ti alloy was first studied.

It was found to contain a Sn matrix, where both Ag phase – ɛ-Ag₃Sn – and Ti phases ɛ-Ti₆Sn₅ and Ti₂Sn₃ – were identified. Ti contained in these phases is distributed to the interface with ceramic material. A reaction layer was thus formed. This layer varies in thickness from 0.5 to 3.5 µm and ensures the wettability of an active solder on the surfaces of ceramic materials.

X-ray diffraction analysis proved the presence of new NTi and AlTi₂ phases on the fractured surface. Sn plays the main role in bond formation when soldering the Cu substrate with Sn-Ag-Ti solder. The Cu₃Sn and Cu₆Sn₅ phases, which grow in direction from the phase interface to solder matrix, were found in all cases within the solder/Cu substrate interface. The combination of AlN ceramics/Cu joint maintained a shear strength of 29.5 MPa, whereas the Cu/Cu joint showed a somewhat higher shear strength of 39.5 MPa.

The present study was oriented towards soldering of AlN ceramics with a Cu substrate by the aid of ultrasound, and the fluxless soldering method was applied. Soldering alloy type Sn-Ag-Ti was analysed, and the interactions between the solder and ceramic and/or Cu substrate were studied. The shear strength of fabricated soldered joints was measured.

The use of nitrogen‐based soldering environments, rather than ambient air, has been widely promoted for both reflow and machine soldering. Earlier claims of process improvements derived mainly from the enhancement of process windows related to improved solderability. The improvements seem to be accepted in the industry but may not be very significant except when accompanying other changes in production soldering facilitated by the use of inert environments. Appropriate process changes include the use of finer pitch devices and more densely populated boards and changes in cleaning technology or the use of no‐clean processes. Material changes include the increased use of new technology for both pastes and fluxes (generally no‐clean), increased use of high temperature solder alloys and the possible need to use lead‐free alloys for environmental reasons. This paper discusses the relationship between atmosphere effects on soldering processes, and process and material changes which favour soldering in atmospheres other than air. It presents some recent data on improvements to soldering resulting from the use of nitrogen environments.

In this article the author discusses various aspects of sacrificial corrosion. He refers to the relationship which exists between corrosion and electrolysis and draws attention to the considerable development of knowledge in this field since the war. He concludes by referring to the relationship which exists between atomic number, atomic weight and corrodibility.

Though lead‐free replacements for SnPb eutectic alloys for reflow, wave, and hand soldering have been developed, relatively little has been reported on practical experience of lead‐free wave soldering processes. In wave soldering, the interaction between the PCB, flux, solder alloy and processing equipment makes it desirable to develop the consumables and the wave soldering machine concurrently. A crossfunctional project team was formed and a lead‐free wave soldering process developed and validated through nine months of industrial use in production of broad‐band communications technology products.

This study aims to address the problem of low-temperature wave soldering in industry production with Sn-9Zn-2.5 Bi-1.5In alloys and develop qualified process parameters. Sn–Zn eutectic alloys are lead-free solders applied in consumer electronics due to their low melting point, high strength, and low cost. In the electronic assembly industry, Sn–Zn eutectic alloys have great potential for use.

This paper explored developing and implementing process parameters for low-temperature wave soldering of Sn–Zn alloys (SN-9ZN-2.5BI-1.5 In). A two-factor, three-level design of the experiments experiment was designed to simulate various conditions parameters encountered in Sn–Zn soldering, developed the nitrogen protection device of waving soldering and proposed the optimal process parameters to realize mass production of low-temperature wave soldering on Sn–Zn alloys.

The Sn-9Zn-2.5 Bi-1.5In alloy can overcome the Zn oxidation problem, achieve low-temperature wave soldering and meet IPC standards, but requires the development of nitrogen protection devices and the optimization of a series of process parameters. The design experiment reveals that preheating temperature, soldering temperature and flux affect failure phenomena. Finally, combined with the process test results, an effective method to support mass production.

In term of overcome Zn’s oxidation characteristics, anti-oxidation wave welding device needs to be studied. Various process parameters need to be developed to achieve a welding process with lower temperature than that of lead solder(Sn–Pb) and lead-free SAC(Sn-0.3Ag-0.7Cu). The process window of Sn–Zn series alloy (Sn-9Zn-2.5 Bi-1.5In alloy) is narrow. A more stringent quality control chart is required to make mass production.

In this research, the soldering temperature of Sn-9Zn-2.5 Bi-1.5In is 5 °C and 25 °C lower than Sn–Pb and Sn-0.3Ag-0.7Cu(SAC0307). To the best of the authors’ knowledge, this work was the first time to apply Sn–Zn solder alloy under actual production conditions on wave soldering, which was of great significance for the study of wave soldering of the same kind of solder alloy.

Low-temperature wave soldering can supported green manufacturing widely, offering a new path to achieve carbon emissions for many factories and also combat to international climate change.

There are many research papers on Sn–Zn alloys, but methods of achieving low-temperature wave soldering to meet IPC standards are infrequent. Especially the process control method that can be mass-produced is more challenging. In addition, the metal storage is very high and the cost is relatively low, which is of great help to provide enterprise competitiveness and can also support the development of green manufacturing, which has a good role in promoting the broader development of the Sn–Zn series.

To make wave soldering of SMDs a success, one must realise that not only the process involved is important, but also the board design and SMD mounting aspects play an important role as they may differ considerably from the rules established for reflow soldering. To elucidate this difference is the main issue of this article.