Development of a scanning electron microscope activity for upper division STEM labs.

Our goal was to develop a lab activity aimed at upper division physics or chemistry majors that utilizes solder balls to demonstrate the functions and capabilities of a scanning electron microscope (SEM). SEMs are becoming more and more common in both industry and graduate research labs. Alternative activities are also outlined for colleges and universities that do not have undergraduate access to an SEM. This lab has two main objectives. First, this lab will demonstrate the difference between the backscattered electron detector and the secondary electron detector. Students will note that the surface details of the solder balls are very sharp when using the secondary electron detector, and the elemental composition of the solder balls are much more distinctive when using the backscattered detector. The second objective is to use the energy-dispersive x-ray detector (EDS) to analyze the elemental composition of the samples. Students will compare the percentages of lead and tin in the solder balls measured by the EDS detector to the manufacturer labeled percentages on the packaging. Students will gain relevant experience that will benefit them in their post graduation plans.