Scanning Electron Microscopy and Energy Dispersive X-ray (SEM/EDX) Characterization of Solder Solderability and Reliability

Abstract

SEM/EDX is a powerful way to characterize solder in resolving solderability and reliability problems. SEM/EDX is a combination tool, with two instruments working in partnership. These two instruments operate simultaneously to complement each other’s data acquisition, guided by the instrumental operator. Scanning electron microscopy (SEM) provides an image (i.e., morphological information or surface features) on a magnified scale—X10 to X100,000, although the usual range is perhaps X50 to X5000.1 Energy dispersive x-ray (EDX) determines the elemental composition of an area, with a sensitivity of perhaps 0.1 to 1 percent composition and with a spatial resolution of 1 µm.2 EDX is commonly used for elements with atomic number ≥11 (sodium), but thin window EDX systems can also detect elements with atomic number ≥5 (boron). With these two instruments operating together, the instrumentalist can scan areas of potential interest, zoom in with higher magnification, and determine elemental compositions in selected areas of interest.