Abstract
The validity of the application of angle lapping method of investigation of the microstructure between the Sn-3.5wt%Ag-0.75wt%Cu Pb-free solder and substrate has been tried. Some of interface layers were too narrow to analyze the microstructure even using TEM of standard cross sectional analysis. But angle lapping method enabled showing elemental mapping by EPMA because of the apparent width was a few micrometer whose original width was less than 0.1 μm. The reaction layer formed between Sn-3.5wt%Ag-0.75wt%Cu and Ni-electroless plate was divided two phases composed void rich layer of (Ag, Cu)-Sn phase and another one was Sn-Cu phase. The component analysis of both layer could not be delected by the standard cross sectional analysis. This results indicated that angle lapping method is powerful for the thin area analysis.
