High temperature solders containing Aluminum and Zinc

Abstract

In this study, we will consider the effect of adding 1–1.5wt.% of Al and Zn to SAC alloy solders in order to limit IMC growth between the solder and the contact metallization. The Al and Zn react strongly with the surfaces on the electronic component and the substrate metallizations that are to be joined. At the solder joint interface, the IMC layer continues to grow at high temperatures and, being brittle, becomes the weakest link in the solder joint. In present work, the interfacial reaction studies were carried out on Cu and Ni(P) substrates. The resultant solder joint microstructure after reflow and isothermal aging at 150 °C up to 500h were investigated under scanning electron microscopy (SEM) with energy-dispersive x-ray analysis (EDX) for phase identification and optical microscopy (OM) for qualitative and quantitative analysis. Our experimental results have confirmed that addition of Al and Zn alloys forms Al-Cu and Cu-Zn on Cu substrate and Al-Ni on Ni(P) substrate respectively. In addition, results have confirmed that addition of Zn alloys plays a crucial role in the composition of IMCs. Addition of Zn (>1wt.%) into basic SAC solder alloy, leads to massive spalling on Cu substrate during reaction. It has been found that additions of Zn into SAC solder alloy can significantly suppress the IMC growth during the aging treatment.