Influence of Cu addition on intermetallic compound formation and microstructure of Sn–3Ag–1˙5Sb– x Cu solder joints (original) (raw)
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The Effect of Increased Cu Content on Microstructure and Melting of Utilized Sn-0.3Ag-0.7Cu Solder
Research Papers Faculty of Materials Science and Technology Slovak University of Technology, 2018
The influence of increased Cu and Ag contents on the microstructure evolution in the utilized Sn-0.3Ag-0.7Cu (wt. %) solder was studied. The utilized solder was exploited in the wave soldering process at the temperatures of about 260 °C for several days. The samples investigation involved the differential scanning calorimetry, the scanning electron microscopy including the energy dispersive X-ray spectroscopy, and the X-ray diffraction techniques. To predict phase equilibria at various temperatures and temperature dependences of heat capacity, the Thermo-Calc software and the COST531 lead-free solder database were used. The original and the utilized solders were found to be very similar regarding the phase occurrence, but slightly differ from one another in microstructure evolution due to higher bulk contents of Cu in the latter solder. The obtained results contribute to both the better understanding of the microstructure evolution in low-silver Sn-Ag-Cu solders and the determinatio...
Materials Science Forum, 2015
The effect of Si particulate addition on the commercial Sn-Cu-Ni solder system (SN100C) solder alloy has been investigated. The SN100C/Si composite solder was fabricated via powder metallurgy (PM) technique. In this study five different Si composition chosen were (0 wt. %, 0.25 wt. %, 0.5 wt. %, 0.75 wt. %, and 1.0 wt. %). The results indicated that adding a small amount of Si particulate can slightly improve the physical properties of the composite solder compared to monolithic solder alloy. Microstructural analysis revealed the reinforcement seen well distributed between the grains boundaries with additions of 1.0 wt. % resulted with highest hardness value.
Nanocomposite lead-free solders are gaining prominence as replacements for conventional leadfree solders such as Sn-Ag-Cu solder in the electronic packaging industry. They are fabricated by adding nanoparticles such as metallic and ceramic particles into conventional lead-free solder. It is reported that the addition of such nanoparticles could strengthen the solder matrix, refine the intermetallic compounds (IMCs) formed and suppress the growth of IMCs when the joint is subjected to different thermal conditions such as thermal aging and thermal cycling. In this paper, we first review the fundamental studies on the formation and growth of IMCs in lead-free solder joints. Subsequently, we discuss the effect of the addition of nanoparticles on IMC formation and their growth under several thermal conditions. Finally, an outlook on the future growth of research in the fabrication of nanocomposite solder is provided. Link to Full-Text Articles : http://iopscience.iop.org/1468-6996/16/3/033505/pdf/1468-6996\_16\_3\_033505.pdf
The effect of Ni addition on Cu-Sn intermetallic growth rate values in the SAC solder
2018
Due to environmental concerns, lead free solders were introduced in replacing the lead based solders in microelectronic devices technology. Among many lead-free solders, the Sn-3.5Ag-1.0Cu solder is the potential replacement for the Sn-Pb solder. This research was carried out to improve the properties of the Sn-3.5Ag-1.0Cu solder in terms of the reaction with copper substrate by adding small amount of Ni into the solder. The composite solders were synthesized via the powder metallurgy route, which consist of blending, compacting and sintering process. After soldering on copper substrate, the solder joint was aged at 150 o C for 1000 hours. The thickness of Cu 6 Sn 5 and Cu 3 Sn were measured and hence the growths kinetic of the intermetallics (k) were calculated. The results show that the SAC-0.05Ni solder has the lowest k value for Cu 6 Sn 5 intermetallic and SAC-0.5Ni has the lowest k value for Cu 3 Sn intermetallic.
Effects of addition of copper particles of different size to Sn-3.5Ag solder
Journal of Materials Science-Materials in Electronics, 2012
In this study, copper particles with different sizes 20-30 nm, 3 and 10 μm were incorporated into Sn-3.5Ag solder paste to form Sn-Ag-Cu composite solder. The Cu particles were added at 0.7 and 3% by paste mixing for 30 min. The composite solder samples were prepared on copper substrate at 240°C for 60 s. Differential scanning calorimetry was conducted to measure the melting point of the composite solder. The wetting angle and microstructure of the composite solder were studied using optical microscope and scanning electron microscope. Micro hardness was measured using a 10 gf load. It was reported that the lowest melting point was obtained at 216.3°C when Cu nanoparticles was added at 3% to Sn-3.5Ag. The microstructure of Sn-3.5Ag solder structure was dendritic in nature. With the addition of Cu nanoparticles, the microstructures were modified with more refined Sn structures. The existence of sunflower morphology of un-melted copper was observed when Cu microparticles were added. http://link.springer.com/content/pdf/10.1007%2Fs10854-011-0441-7.pdf
Journal of Electronic Materials, 2003
Intermetallic-layer formation and growth in Pb-free solder joints, during solder reflow or subsequent aging, has a significant effect on the thermal and mechanical behavior of solder joints. In this study, the influence of initial intermetallic morphology on growth rate, and kinetics were examined in a Sn-3.5Ag solder reflowed on Cu. The initial morphology of the intermetallic was tailered by cooling in water, air, or furnace conditions. Solder aging was conducted at 100°C, 140°C, and 175°C and aged for 0-1,000 h. Cooling rate, aging temperature, and aging time played an important role on microstructure evolution and growth kinetics of Cu 6 Sn 5 (η) and Cu 3 Sn (ε) intermetallic layers. Prior to aging, faster cooling rates resulted in a relatively planar Cu 6 Sn 5 layer, while a nodular Cu 6 Sn 5 morphology was present for slower cooling. Intermetallic-growth rate measurements after aging at various times, indicated a mixed growth mechanism of grain-boundary and bulk diffusion. These mechanisms are discussed in terms of the initial intermetallic thickness and morphology controlled by cooling rate, diffusion kinetics, and the competition between Cu 6 Sn 5 and Cu 3 Sn growth.
Journal of Electronic Packaging, 2016
The sandwich structure Cu/Sn/Cu solder joints with different thicknesses of the solder layers (δ) are fabricated using a reflow solder method. The microstructure and composition of the solder joints are observed and analyzed by scanning electron microscopy (SEM). Results show that the thickness of intermetallic compound (IMC) and Cu concentration in the solder layers increase with the decrease of δ after reflow. During thermal aging, the thickness of IMC does not increase according to the parabolic rule with the increase of aging time; the solder joint thickness affects markedly the growth rate of IMC layer. At the beginning of thermal aging, the growth rate of IMC in the thinner solder joints (δ ≤ 25 μm) is higher than that in the thicker ones (δ ≥ 30 μm). The growth rate of IMC (δ ≤ 25 μm) decreases in the thinner solder joints, while increases in the thicker solder joints (δ ≥ 40 μm) and is nearly invariable when the δ equals to 30 μm with aging time extending. The growth rate of...
The effect of adding Zn into the Sn–Ag–Cu solder on the intermetallic growth rate
Journal of Materials Science: Materials in Electronics, 2014
Due to toxicity of lead in the commercial solder, lead-free solders were proposed. Among the potential leadfree solders, the SnAg -Cu solders were considered as a potential replacement. To further improve the solder properties, a fourth element was added into the SnAg -Cu solder. The present study investigates the effect of different weight percentage of Zn (up to 0.7 wt%) into the Sn-3.5Ag-1.0Cu solder on intermetallic and growth rate (k) after long time thermal aging. The solders were prepared using powder metallurgy method and X-ray diffraction analysis shows that there were Cu 6 Sn 5 , Cu 3 Sn, CuZn and Ag 3 Sn phases present after solder preparation. The solders were reacted with Cu substrate at 250°C for 1 min and aged at 150°C until 1,000 h. The morphology of the intermetallic was observed under scanning electron microscope and the elemental distribution was confirmed by energy dispersive X-ray. Intermetallic thickness and growth kinetic result show that the additions of 0.4 % zinc is sufficient in retarding the Cu 6 Sn 5 and Cu 3 Sn intermetallic growth.