Search

The aim of this research was to study the microstructure in soldered joint of SiC ceramics with Cu in cases of flux-less soldering with ultrasound assistance. The soldering was performed by ultrasonic activation of newly developed Bi–Ag–Ti based solder alloy. This new solder alloy was developed for flux-less soldering processes and meets the requirements for the versatility of its use for soldering metal and ceramic materials.Suitability for the application of Bi–Ag–Ti solder was assessed on the basis of analyses of joint boundaries and measuring the shear strength of the joint. Light analysis proved the formation of joints without cracks, pores or other imperfections. The SiC/Bi–Ag–Ti boundary was formed on the basis of the reaction between Si and Ti. The bond in Cu/Bi–Ag–Ti boundary was formed due to formation of mechanical mixture of Bi + Cu. The average shear strength of the SiC/Cu joint reached 40 MPa. [ABSTRACT FROM AUTHOR]

The study aimed at direct flux-free soldering of metal-ceramics composite (MMC) with a copper substrate. Soldering was performed with type Zn10In1Mg Zn-solder. The soldered joints were fabricated using power ultrasound. The solder used consists of a zinc matrix, while the solid solution (In) and MgZn2 phase were segregated on the grain boundaries. The soldered MMC joint is formed due to dissolution of the aluminium matrix in zinc solder. A new composite, composed of matrix consisting mainly of solid solution (Al) is thus formed. Moreover, there is also a solid solution present (In) and Cu3.2Zn0.7Al4.2 phase. The bond with copper substrate is formed due to interaction of Zn and Al from the solder at formation of two transient phases, namely Cu3.2Zn0.7Al4.2 and an unstable phase of Al(Cu,Zn)2. The average shear strength of combined joints of MMC/Cu is 16.5 MPa. [ABSTRACT FROM AUTHOR]

The aim of study was to characterize the Zn-In-Mg soldering alloy type and investigate the direct soldering of silicon and copper. The Zn-In-Mg solder type has a broad interval of melting, which depends on the indium content in the solder. Solder microstructure is formed of a matrix with pure Zn. The MgZn 2 phases and solid solution (In) β-In are precipitated along the grain boundaries. Tensile strength attains values from 46 to 124 MPa and is dependent on indium content. The bond with silicon is formed due to the reactions of active metals - In and Mg with the substrate surface. Diffraction analysis has also revealed the In 13 Mg 7 phase. In spite of that, the bond formation with a copper substrate in not affected by In and Mg content. The bond is formed owing to interaction between the zinc from the solder and copper substrates. Two phases, namely CuZn 4 and Cu 5 Zn 8 were observed. The shear strength of Cu/Zn-In-Mg/Cu joints attains values from 56 to 62 MPa and the shear strength of Si/Zn-In-Mg/Cu joint is within 34–42 MPa. [ABSTRACT FROM AUTHOR]

The work deals with the study of interaction Cu substrate (purity 5N) and Zn4Al and Zn6Al6Ag (purity 4N) solders for higher application temperatures. Soldering was performed with power ultrasound in the air without flux application at temperature 420 °C. Acting time of ultrasonic vibration was 5 s. Soldered joints were assessed by optical light microscopy, EDX microanalysis and DSC analysis. It was found out that the melting temperatures of solders were 404.9 °C and 396.9 °C. Intermetallic layers (IM) CuZn 4 and Cu 5 Zn 8 were formed at the Cu/Zn4Al boundary. At the boundary Cu/Zn6Al6Ag there were formed AgZn 3 and Cu 5 Zn 8 IM layers. Shear strength of joint Cu/Zn4Al was 34.5 MPa and shear strength of Cu/Zn6Al6Ag was 39 MPa. [ABSTRACT FROM AUTHOR]

Purpose – The purpose of this paper is to study the effect of the addition of a small amount of Al (0.1 percent) on the properties of lead-free solder type Sn-4Ag-0.5Cu (SAC 405). Design/methodology/approach – The soldering properties of wettability and spreadability on a Cu substrate were studied, and the effect of Al on the growth of intermetallic compounds (IMCs) was observed. The shear strength of soldered joints was assessed. For comparison, soldering and strength tests were carried out on SAC 405 and SAC 405+ Al solders. Soldering was performed with an activated flux type ZnCl2-NH4Cl, with non-activated flux (rosin), and without flux in the air. Findings – Experimental results show that Al addition slightly reduces the wettability and spreadability of SAC 405 solder. Also, the shear strength is moderately reduced, dropping by 8 MPa on average. Differential scanning calorimetry (DSC) analysis showed that the melting point of SAC 405+0.1%Al solder was increased to 221°C. Originality/value – The positive effect of a small Al addition is due to the fact that it hinders the growth of IMCs formed on the contact surface with Cu substrate. The width of the transition zone of IMC was reduced by approximately 2 to 3 μm, depending on the soldering temperature. [ABSTRACT FROM AUTHOR]

Purpose – The purpose of this paper is to study Bi-11Ag solder for higher application temperatures. The aim of the research work was to determine the soldering, thermal and mechanical properties of Bi-11Ag solder. Design/methodology/approach – To determine the melting point interval of experimental Bi-11Ag solder, DSC analysis was performed. The contact angles were studied on a copper, nickel and silver substrate by use of a sessile drop method. Wettability tests were realised at a temperature of 380°C in a shielding atmosphere (90% N2+10% H2). Based on experience achieved with wetting angle measurements, the specimens for measurement of shear strength of Cu, Ni and Ag/Bi-11Ag joints were fabricated. EDX analysis was used for the study of the solder interaction with the surface of the three metallic substrates. Findings – The best wettability at soldering in a shielding atmosphere was achieved with silver. The wetting angle at 30 min attained the value of 23°. The worst wettability was observed on copper, where at 30 min the wetting angle was 55°. Average shear strength varied from 31 to 45 MPa. The highest strength was obtained with the Cu substrate whereas the lowest was with the Ni substrate. The lowest strength achieved with the Ni substrate was caused by formation of brittle intermetallic phase NiBi3. Joint formation is realised by eutectic reaction at the contact of Bi with the surface of the copper substrate. Similar joint formation by eutectic reaction occurs also at Bi interaction with the surface of the Ag substrate. At Bi interaction with the nickel substrate a new intermetallic phase (NiBi3) is formed. Originality/value – Wettability of Bi-11Ag solder on Cu, Ag and Ni substrates was determined at application of a shielding atmosphere (90% N2+10% H2). Wettability was determined also at application of ZnCl2-NH4Cl flux. The shear strength of Bi-11Ag on different substrates was determined. The mechanism of joint formation was analysed. [ABSTRACT FROM AUTHOR]

Purpose – 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. Design/methodology/approach – 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. Findings – 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. Originality/value – 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. [ABSTRACT FROM AUTHOR]