Intermetallic Compounds Ni3Sn4 Research Articles

Interfacial reaction between Ni particle reinforcements and liquid Sn-based eutectic solders

PurposeThis paper aims to derive a model of growth kinetics of the intermetallic compound (IMC) layer formed in the reaction between liquid Sn-based solders and Ni particle reinforcements and to compare with the experimental data to verify the effects of Sn concentration and alloying element.Design/methodology/approachA composite solder was manufactured by mechanically introducing Ni particle reinforcements into a solder matrix. The effect of the non-reactive alloying elements, Ag, Pb and Bi, on the growth kinetics of the IMC formed between liquid Sn-based eutectic solders and Ni particles, reacting this composite solder at 250°C–280°C was studied.FindingsExperimental results showed that only the IMC Ni3Sn4 was present as a reaction product. Using the diffusion-controlled reaction mechanism, a kinetic equation quantifying both Sn concentration and alloying element effects was derived and verified by comparing the kinetic data obtained using four different solders with different concentrations of Sn and the alloying elements.Originality/valueThe similarity between the activation energies of these four solders confirms that the diffusion of Sn atoms through the IMC is the rate-controlling step. Besides, the kinetic values are independent of the geometry of Ni, whether spherical particle or flat substrate.

Interfacial reactions between solid Ni and liquid Sn-Zn alloys

The limitation of the harmful lead-containing solders used in the electronics and other industry applications change lead with another metals. Interfacial reactions between Sn-Zn alloys and Ni substrate after annealing at 400 and 450?C were studied. Three intermetallic compounds Ni3Sn4, T1, ?-Ni5Zn21 and liquid Sn were observed in the Ni/Sn-Zn diffusion couples. Scanning electron microscope was used for the investigation of the microstructure. The microhardness measurement of the intermetallic layers was also performed.

Effects of multiple reflows on interfacial reaction and shear strength of SnAgCu and SnPb solder joints with different PCB surface finishes

Abstract The effects of multiple reflows (1, 2, 4, 6, 8, 10 numbers of reflow) on interfacial reaction and shear strength of Sn3.8Ag0.7Cu (SAC) and Sn37Pb (SP) joints were systematically investigated using electrolytic Ni/Au and organic solderability preservative (OSP) finished pad. In the case of OSP finished substrate, the well-known intermetallic compound (IMC) Cu6Sn5 was observed for both solders. While for the Ni/Au finished substrate, the IMC Ni3Sn4 and (CuNi)6Sn5 were formed on the interface of SP and SAC joints, respectively. With the increasing number of reflows, the thickness of IMCs on all reaction couples increased gradually and the IMC grain coarsened. The IMC growth kinetics showed that the interfacial IMC Cu6Sn5 was controlled by grain boundary diffusion and that the IMCs (Ni3Sn4 and (CuNi)6Sn5) near Ni layer had interactive diffusion control of grain boundary and volume diffusion. Moreover, IMC growth at Cu interface was faster than that at Ni interface, irrespective of the solder type. Shear test results showed that the shear force did not change much until eight numbers of reflow for each reaction couple. The ductile fracture indicated that the shear strength of solder joints could not be significantly influenced by the thickness and morphology of the interfacial IMC.

Electromigration effect upon the Sn–0.7 wt% Cu/Ni and Sn–3.5 wt% Ag/Ni interfacial reactions

This study investigates the effect of electromigration upon the interfacial reactions between the promising lead-free solders, Sn–Cu and Sn–Ag, with Ni substrate. Sandwich-type reaction couples, Sn–0.7 wt% Cu/Ni/Sn–0.7 wt% Cu and Sn–3.5 wt% Ag/Ni/Sn–3.5 wt% Ag, were reacted at 160, 180, and 200 °C for various lengths of time with and without the passage of electric currents. Without passage of electric currents through the couples, only one intermetallic compound Ni3Sn4 with ∼7 at. % Cu solubility was found at both interfaces of the Sn–0.7 wt% Cu/Ni couples. With the passage of an electric current of 500 A/cm2 density, the Cu6Sn5 phase was formed at the solder/Ni interface besides the Ni3Sn4 phase. Similar to those without the passage of electric currents, only the Ni3Sn4 phase was found at the Ni/solder interface. Directions of movement of electrons, Sn, and Cu atoms are the same at the solder/Ni interface, and the growth rates of the intermetallic layers were enhanced. At the Ni/solder interface, the electrons flow in the opposite direction of the Sn and Cu movement, and the growth rates of the intermetallic layers were retarded. Only the Ni3Sn4 phase was formed from the Sn–3.5 wt% Ag/Ni interfacial reaction with and without the passage of electric currents. Similar to the Sn–0.7 wt% Cu/Ni system, the movement of electrons enhances or retards the growth rates of the intermetallic layers at the solder/Ni and Ni/solder interfaces, respectively. Calculation results show the apparent effective charge za* decreases in magnitude with raising temperatures, which indicates the electromigration effect becomes insignificant at higher temperatures.

Preparation of solder bumps incorporating electroless nickel-boron deposit and investigation on the interfacial interaction behaviour and wetting kinetics

Investigation of a method for preparing solder bumps on Al pads incorporating electroless nickel deposition and soldering for solder bumps was undertaken. The experimental variables included bath temperature and dipping velocity. The formation of intermetallic compounds and wetting kinetics between electroless Ni-B deposit and molten solder was also investigated. The interfacial interaction behaviour was studied with the aid of Auger depth profile and scanning electron microscopy. Intermetallic compounds Ni3Sn4 and Ni3Sn2 were formed between the Ni-B deposit and solder. Aluminium atoms diffuse through the intermetallic compound layer and dissolve in the solder when the electroless Ni-B deposit is entirely consumed. The contact angles of molten solder on a Ni-B deposit, measured with the sessile drop method, decrease with increasing temperature and time. The activation energy for wetting of molten solder on a Ni-B deposit was estimated to be 208.27 kcal mol-1.

Wetting Kinetics and the Interfacial Interaction Behavior between Electroless Ni–Cu–P and Molten Solder

Formation of intermetallic compounds and wetting kinetics between an electroless Ni–Cu–P deposit and molten solder were investigated. The microstructure and phase of the interface were investigated with the aid of scanning electron microscopy (SEM) and X-ray diffractometry (XRD). Intermetallic compounds Ni3Sn4 and Ni3Sn2 were formed between Ni–Cu–P deposit and solder with Cu existing in the intermetallic layer. The contact angles of molten solder on a Ni–Cu–P deposit, measured with the sessile drop method, decrease with increasing temperature and time. The activation energy for wetting of molten solder on a Ni–Co–P deposit was estimated to be 193.7 kJ mol-1.