Back-Scattered Electron Images From a High Resolution SEM
When an electron beam hits a sample, back-scattered electrons, among other
signals, are emitted. The quantity of back-scattered electrons is highly dependent
on the atomic number of the sample. Material with a larger atomic number
will give off more backscattered electrons.
This is a backscattered electron image of lead-tin solder. Lead has a
much higher atomic number than tin and therefore gives off many more electrons.
The lead signal is much more intense, and in this picture the lead particles
appear brighter than the surrounding tin.
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Document last reviewed November 14th. 2002.