Analytical Technique
Surface analysis using auger electron spectroscopy combined with ion beam etching quantifies chemical composition across thin solid films down to sub-nanometer depths. In printed circuit board quality assurance, aes depth profiling isolates elemental concentrations through surface coatings like electroless nickel immersion gold or immersion tin. Focused argon ion beams remove atomic layers sequentially while an electron beam excites auger electrons from the freshly exposed surface.
High vacuum conditions prevent contamination during sputtering operations. The resulting data plots atomic concentration against depth or sputtering time, revealing intermetallic diffusion zones and localized oxidation.
Interface Evaluation
Characterization of metallic plating boundaries exposes hyper-corrosion defects and trace contaminants that undermine solder joint integrity. When analyzing black pad anomalies in electroless nickel layers, the technique reveals localized nickel phosphorus ratios along with phosphorus accumulation beneath gold deposits. Sputtering rate calibration against standard reference materials converts ion beam etching time into precise physical thickness.
Oxidation fronts at copper plating interfaces become visible before mechanical shear testing fails. Discontinuities in atomic signals identify chemical contamination from process bath drag-out or incomplete rinse steps.
Sputter Boundary
Preferential etching effects and matrix variations constrain depth resolution when ion beam bombardment alters target material stoichiometry. Differential sputtering rates between distinct metallic phases cause surface roughening during ion beam erosion. Secondary ion mixing occurs at deeper interfaces, broadening signal transitions beyond their physical dimensions.
Profile interpretation requires offset factors derived from known layer thicknesses or profilometry measurements to correct etching velocity shifts.
