Abstract
High reliability and stable bond quality are required for industrial electronic devices. In this paper, we clarify how adding tiny amounts of Ni and Ge improves the properties of Sn-Ag-Cu alloy lead-free solder and the reliability of the bonded interface by inhibiting the effect of the generation-bonded interface-reaction phase and solder oxidation.
By adding a few hundred ppm of an element, granular Cu-Sn-Ni alloy compounds, which are formed from Cu-Sn alloy compounds, are generated in the bonded interface-reaction phase. This shows that it is possible to control of the growth of the bonded interface reaction phase. Also, we confirm that, as an antioxidant, a tiny amount of Ge will not inhibit the generation of granular chemical compounds owing to the addition of Ni, and it shows better bond reliability than the currently used antioxidant, P. Sn-Ag-Cu alloy lead-free solder with added Ni or Ge has already been put to practical use. There are application records in a number of industrial electronic devices over the past 15 years or so. Furthermore, these applications and the effectiveness of adding tiny amounts of these elements are recognized and registered in international standard ISO9453, and registration in domestic JIS standard is determined as well. This article introduces some approaches to solving the technical issues in the practical realization of Sn-Ag-Cu-Ni-Ge alloy solder.
