Crystalline Mapping
Scanning electron microscopes generate crystallographic data through electron backscatter diffraction during failure analysis on printed circuit board assemblies. Incident electrons strike tilted polycrystalline metallic structures and scatter backward from atomic planes to form coherent Kikuchi lines on a phosphor screen. Automated indexing software calculates local orientation angles and misorientation distributions across microstructural phases.
Thermal excursions during reflow soldering induce localized strain accumulation within copper interconnects and intermetallic compound layers. Crystallographic orientation mapping resolves residual stress fields and dynamic recrystallization zones around cracked solder joints by measuring localized lattice distortion.
Deformation Profiling
Directional strain gradients develop inside microvias during thermal cycling because mismatched coefficients of thermal expansion generate shear stresses along barrel walls. Crystallographic orientation data reveals localized lattice rotation angles exceeding standard thresholds near barrel wall fractures. Misorientation angles quantify plastic deformation severity across specific grain boundaries without destroying surrounding circuitry.
Localized orientation gradients pinpoint exact initiation sites for fatigue cracking within brittle intermetallic layers between copper pads and ball grid array spheres.
Fabrication Verification
Acceptance testing protocols require quantitative verification of grain boundary networks following laser ablation and chemical etching procedures. Orientation maps verify complete removal of deformed surface layers resulting from mechanical polishing before microhardness testing takes place. Phase identification algorithms differentiate between copper grain structures and intermetallic compounds formed during high temperature storage testing.
Crystallographic data confirms whether electroplated copper deposits exhibit desired columnar grain growth or random nucleation patterns that cause premature fatigue failure.
