The infrared grey-field polariscope (IR-GFP) has been developed to provide rapid, full-field stress analysis for infrared-transparent materials. Grey-field photoelastic theory is outlined and the advantages of this implementation for microelectronic materials inspection highlighted. The capabilities of this scientific tool are proven using standard sample geometries fabricated from single crystal silicon substrates and the general applicability of the instrument demonstrated on bonded devices and silicon wafer geometries. Stress resolution in silicon wafers is better than 0.1MPa at wafer inspection speeds of 10s for a 100mm wafer. Initial applications of the IR-GFP have shown that the tool provides improvements in defect detection and stress quantification when compared to conventional infrared transmission imaging while also providing several important advantages over other currently utilized inspection technologies.
A full-field thermoelastic technique for measuring stress intensity factors in dynamically loaded fatigue crack specimens is outlined. Thermoelastic Stress Analysis (TSA) uses an infrared focal plane array detector and high-speed processing electronics to produce stress images of cyclically loaded specimens. The TSA data is then used in combination with a fitting algorithm to determine stress intensity factors for mode I and mixed mode I and II crack geometries. The technique is non-contacting, fast and accurate, and has the potential to greatly enhance the efficiency of fatigue and fracture testing. An analytical solution for the complete stress state in terms of the first stress invariant is derived in support of the full-field TSA technique. Results using the technique on mode I and mixed mode specimens are presented, and show good agreement with accepted values.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.