Microstructural analysis of Sn-3.0Ag-0.5Cu-TiO2 composite solder alloy after selective electrochemical etching

Abstract

This work aims to provide deep morphological observation on the incorporated TiO _2 nanoparticles within the SAC305 by selective electrochemical etching. Cyclic voltammetry and chronoamperometry were used to investigate the selective etching performances. The removal of β -Sn matrix was conducted at a fixed potential of −350 mV. Average performances of 2.19 and 2.30 mA were attained from the chronoamperometry. The efficiency of β -Sn removal was approved according to the reduction of the intensities on the phase analysis. Successful observation of the TiO _2 near the Cu _6 Sn _5 layer was attained for an optimum duration of 120 s. Clusters of TiO _2 nanoparticles were entrapped by Cu _6 Sn _5 and Ag _3 Sn intermetallic compound (IMC) layer network and at the solder/substrate interface. The presence of TiO _2 nanoparticles at the solder interface suppresses the growth of the Cu _6 Sn _5 IMC layer. The absence of a β -Sn matrix also allowed in-depth morphological observations to be made of the shape and size of the Cu _6 Sn _5 and Ag _3 Sn. It was found that TiO _2 content facilitates the β -Sn removal, which allows better observation of the IMC phases as well as the TiO _2 reinforcement particles.

Keywords

• intermetallic compounds
• microstructure
• SAC
• reflow soldering
• TiO2 nanoparticles