Growth mechanism of Ni3Sn4 in a Sn/Ni liquid/solid interfacial reaction

Researchers have been working for some times to develop a Pb-free substitute for high-Pb containing solders in electronics. In this study the effect of Mg content on microstructure, melting behavior, thermal, electrical and mechanical properties of a new high-temperature Pb-free solder based on binary Zn-Mg alloy were investigated. The nominal compositions of Zn-xMg (x = 0.5-6.0) alloys were synthesized by conventional melting and casting route. The microstructures of the solders changed significantly on adding Mg content. Higher Mg containing alloys were found rich in intermetallic phases. The formation of the Mg 2 Zn 11 and metastable MgZn 2 intermetallic phases were identified and were also quantified by X-ray diffraction analysis. The presence of higher amount of intermetallic compounds in hypereutectic Zn-Mg systems deteriorated the tensile properties of the binary alloy. The results of electrical resistivity test indicated that the Mg could elevate the resistivity of newly developed Zn-Mg alloys. The melting behavior of the solder alloys studied by differential thermal analysis (DTA) analysis revealed that the melting temperature range of the solder alloys narrowed with Mg addition. Thermal mechanical analysis (TMA) analysis revealed that the co-efficient of thermal expansion (CTE) decreased on increasing Mg content.

Section: Chemical Compositionmentioning

confidence: 99%

Study of off-eutectic Zn–xMg high temperature solder alloys

Galib

Hasan

Sharif

2016

“…Generally, a thin, continuous and uniform IMC layer formed in solder joints is an essential requirement for a good metallurgical bonding [7]. However, due to the inherently brittle nature of IMC layers and their tendency to generate structural defects, too thick IMC layers at the solder/substrate material interface were easy to degrade the fatigue and fracture strengths of solder joints and led to poor reliability of electronic devices [8].…”

Section: Introductionmentioning

confidence: 99%

Microstructural evolutions of the Ag nano-particle reinforced SnBiCu-xAg/Cu solder joints during liquid aging

Shen

Peng

Zhao

et al. 2011

Ag nano-particle reinforced Sn30Bi0.5Cu-xAg (x = 1 wt%, 2 wt% and 5 wt%) solder pastes were prepared and reflowed on Cu substrates at 523 K. Then, the solder joints were liquid aged at 473 K for 6 and 12 h. Microstructural evolutions of these solder joints were observed by scanning electron microscopy (SEM). The results show that Bi-rich phase was refined in the as-reflowed Sn30Bi0.5Cu-xAg composite solder matrices. With the increase of the liquid aging time, Bi-rich phase was refined both in the Sn30Bi0.5Cu solder and in the Sn30Bi0.5Cu-xAg composite solders. The addition of Ag nano-particles changed the growth rate of the IMC layers during liquid aging due to the absorption effect of the Ag 3 Sn micro-particles.

“…The failure of solder joints often occurs at the interface between the IMC and solder or between the IMC and metallic substrate, and consequently leads to loss of function in interconnects and results in product failure. So far, there has been increasing attention towards the study of formation, growth and morphology evolution of interfacial IMC phases in lead-free solder joints by experimental characterization and numerical simulation [7][8][9][10][11][12][13][14][15]. According to the thermodynamics theory [8], at the initial stage of the metallic substrate (such as Cu or Ni) contacting to the molten solder, the metallic atoms rapidly dissolve into the molten solder and quickly become supersaturated in the interface regions; and subsequently the IMC phases start to nucleate and grow at the interface due to the local metastable equilibrium solubility of metallic atoms in the liquid solder alloy.…”

Section: Introductionmentioning

confidence: 99%

Premelting behavior and interfacial reaction of the Sn/Cu and Sn/Ag soldering systems during the reflow process

Zhou

Zhang

2012

The early interfacial reaction and premelting characteristics of the Sn/Cu and Sn/Ag soldering systems, and the formation and morphology transition of interfacial intermetallic compounds in the two systems during the reflow soldering process were investigated by using a differential scanning calorimeter. Results show that the initial interfacial eutectic reaction arising from atomic interdiffusion in solid-state Sn/Cu and Sn/Ag systems results in the premelting at each interface of the two systems at a temperature 4.9 and 10.6°C respectively lower than the actual melting point of pure tin, and consequently both of the Sn/Cu and Sn/Ag soldering systems exhibit morphology change of the intermetallic compound (IMC) as the solder experiences a transition from solid-state to liquid-state in a very small temperature range. The change in the interfacial energy between the solid (or liquid) Sn-rich phase and IMC phase is the essential factor leading to the morphology transition of the interfacial IMC in the Sn/Cu and Sn/Ag soldering systems.