Solder joining technologies have become increasingly important in the electronics industry in recent years from the viewpoints of miniaturization of electronic components and wide adoption of lead-free solder alloys. This article introduces an example of analysis of the solder joint interface of a printed wiring board on which components were mounted with a lead-free solder alloy (Sn-3.0Ag-0.5Cu) and a crack in the solderusing a Shimadzu EPMA™ electron probe microanalyzer (EPMA-8050G, hereinafter, EPMA).