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

Muhamad Zamri Yahaya,Ahmad Azmin Mohamad,Soorathep Kheawhom,Balázs Illés,Muhammad Firdaus Mohd Nazeri,Agata Skwarek

doi:10.1088/2053-1591/ab6b57

Abstract

This work aims to provide deep morphological observation on the incorporated TiO2 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 TiO2 near the Cu6Sn5 layer was attained for an optimum duration of 120 s. Clusters of TiO2 nanoparticles were entrapped by Cu6Sn5 and Ag3Sn intermetallic compound (IMC) layer network and at the solder/substrate interface. The presence of TiO2 nanoparticles at the solder interface suppresses the growth of the Cu6Sn5 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 Cu6Sn5 and Ag3Sn. It was found that TiO2 content facilitates the β-Sn removal, which allows better observation of the IMC phases as well as the TiO2 reinforcement particles.

Highlights

The Sn-Ag-Cu (SAC) and Sn-Ag alloys, Sn-3.0Ag-0.5Cu (SAC305), is the most commercially used solder alloy in current electronic assemblies [1, 2]
The presence of TiO2 nanoparticles at the solder interface suppresses the growth of the Cu6Sn5 intermetallic compound (IMC) layer
The cyclic voltammetry (CV) is essential in allowing the observation on the removal and deposition of the phases within the solder alloy with respect to the applied potential

Summary

Introduction

The Sn-Ag-Cu (SAC) and Sn-Ag alloys, Sn-3.0Ag-0.5Cu (SAC305), is the most commercially used solder alloy in current electronic assemblies [1, 2]. The solder joints of the SAC305 alloy is composed form β-Sn matrix and intermetallic compounds (IMCs) precipitations usually Cu6Sn5 and Ag3Sn. Demand for more and more miniaturized electronic devices resulted in numerous efforts to improve SAC305 solder alloys. The effect of reinforcement materials (mainly nanoparticles) such as NiO [1], TiO2 [4], graphene and TiO2 [5] and SiO2 [6] were investigated as an improved version of the SAC305 composite solder. The addition of 2.5 wt% NiO nanoparticles in SAC305 solder alloys decreased the IMC layer formation of 50% and increased the microhardness of the solder joints [1]

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