Microstructure Of Lead-free Solder Research Articles

Investigation of the Electroless Nickel Plated Sic Particles in Sac305 Solder Matrix

In the present study, an electroless nickel (EN) plating method is applied for the coating of silicon carbide (SiC) particles. The particles of SiC(Ni) were added to the Sn–3.0Ag–0.5Cu matrix for the production of SAC305/SiC(Ni) composite by the powder metallurgy route. SAC305/xSi(Ni) composite was prepared by a planetary ball milling of the starting powder, followed by compacting and sintering. Nickel-coated silicon carbide particles and the lead-free solder matrix react together, forming different phases during sintering at temperature 200°C for 3 h. The microstructure, mechanical (compressive strength, microhardness, wettability, and porosity) and physical properties (density) of lead-free solder composite SAC305/SiC(Ni) were studied. The current research shows the successful application of electroless nickel (EN) plating method, and how nickel-coated SiC particles subsequently improve the mechanical properties and microstructure of lead-free solder.

Electrochemical Impedance Spectroscopy as a Prospective Tool for the Characterization of the Intermetallic Microstructure of Lead Free Solder

In this study the possibility to apply electrochemical impedance spectroscopy as an alternative method for the characterisation of the intermetallic microstructures of Sn-3.5Ag lead free solder samples was investigated. The aim of the study is to compare the electrochemical impedance spectra of solder samples, reflowed with different heat profiles. A quenching technique was applied in order to solidify the solder samples in cylindrical crucibles. Differences in the microstructures of the solidified alloys were achieved by changing the temperature of the quenching media. The molded and cross sectioned specimens were observed using both optical microscopy and scanning electron microscopy (SEM) combined with energy dispersive spectroscopy (EDS). The microstructure of the ingots was revealed by selective electrochemical etching. The electrochemical impedance spectrum (EIS) was measured before and also after the selective etching process. The complex impedance spectra contain information regarding the characterized microstructure. Our aim is to determine quantitative parameters which are identical to the characteristics of the microstructure.