AbstractMetallic whiskers are spontaneous filamentary protrusions that emerge from stressedconductive surfaces, especially in electroplated or polycrystalline thin metallic layers such astin, zinc, cadmium, and related alloys. Despite decades of experimental observation, theirphysical interpretation remains fragmented across mechanical, electrochemical,grain-boundary, diffusion-based, and reliability-oriented explanations. Existing accountsidentify relevant contributing factors, but often do not provide a unified formalism thatexplains why the system selects narrow filamentary extrusion as a preferred mode of localstress release.This work proposes a unified continuum field theory in which metallic whisker initiation isinterpreted as a localized anisotropic morphological relaxation event in a metastableconductive medium. In this formulation, the surface is treated as a nonequilibrium energeticmanifold carrying coupled fields of mechanical stress, chemical potential imbalance, defectdensity, geometric curvature, electrostatic asymmetry, and relaxation capacity. Whiskergrowth is therefore modeled not as an anomalous surface artifact, but as a thresholdedmorphological escape channel through which a constrained medium releases storedinstability. A generalized local instability functional is introduced together with a nucleation criterion, anevolution law for the surface height field, a strain-relaxation feedback term, and adimensionless instability number suitable for predictive interpretation. The frameworkpredicts: (1) thresholded nucleation zones, (2) preferred initiation at grain boundaries anddefect-rich interfaces, (3) delayed emergence after long dormancy, (4) branching and kinkingunder anisotropic field bifurcation, and (5) suppression under distributed relaxation, defecthomogenization, or reduction of local field concentration.The theory is formulated as a physically interpretable and experimentally extendable researchprogram. Its principal contribution is to reframe metallic whiskers as field-localizedmorphological discharge structures in metastably loaded conductive surfaces. This yields aunified conceptual and mathematical basis for reliability analysis, failure prediction, surfacedesign, and stress-topology control in thin-film systems./AbstractThis document translates the field-theoretic framework introduced in Part A into anengineering methodology for measurement, calibration, prediction, and control ofmetallic whisker formation in conductive thin films. The core objective is to transformwhisker formation from a post-failure observational problem into a predictive, spatiallyresolved reliability assessment task.We introduce a practical pipeline for reconstructing the local instability field from measurablequantities, define a calibrated instability index for risk mapping, and propose a validationprotocol based on blind prediction of whisker nucleation zones. The framework integratesestablished characterization techniques—including X-ray diffraction (XRD), electronbackscatter diffraction (EBSD), scanning electron microscopy (SEM), atomic forcemicroscopy (AFM), and surface potential mapping—into a unified diagnostic architecture.The resulting system enables pre-failure risk cartography, allowing identification ofhigh-probability whisker nucleation zones prior to morphological manifestation. In addition,we outline control strategies for suppressing instability localization through microstructural,mechanical, and interfacial design.This part establishes the framework as an engineering-ready predictive system, bridgingtheory and practice in thin-film reliability science.
Roman Lukin (Sun,) studied this question.