A review on effect of minor alloying elements on thermal cycling and drop impact reliability of low-Ag Sn-Ag-Cu solder joints

Purpose - The purpose of this paper is to discuss the reliability of board level Sn-Ag-Cu (SAC) solder joints in terms of both thermal cycling and drop impact loading conditions, and further modification of the characteristics of low Ag-content SAC solder joints using minor alloying elements to withstand both thermal cycle and drop impact loads.Design methodology approach - The thermal cycling and drop impact reliability of different Ag-content SAC bulk solder will be discussed from the viewpoints of mechanical and micro-structural properties.Findings - The best SAC composition for drop performance is not necessarily the best composition for optimum thermal cycling reliability. The content level of silver in SAC solder alloys can be an advantage or a disadvantage depending on the application, package and reliability requirements. The low Ag-content SAC alloys with different minor alloying elements such as Mn, Ce, Bi, Ni and Ti display good performance in terms of both thermal cycling and drop impact loading conditions.Originality value - The paper details the mechanical and micro-structural properties requirements to design a robust bulk SAC solder joint. These properties provide design and manufacturing engineers with the necessary information when deciding on a solder alloy for their specific application.