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Cu-Cu hybrid bonding has gained attention, yet ensuring process reliability requires robust methodologies for bond strength characterization. The widely used Double-Cantilever-Beam (DCB) test is restricted to wafer edges. To address these limitations, this study employs the 4-PointBending (4PB) and Nanoindentation (NI) tests to evaluate bond strength variation at both wafer and die levels. The 4PB test revealed strong environmental dependence: higher bond strength was obtained under anhydrous conditions, whereas degradation occurred in ambient air due to water stress corrosion (WSC). For high-strength samples after post bond annealing (PBA), fracture of the Si substrate occurred before interfacial delamination, indicating the measurement limit of this method. In contrast, the NI test, inherently localized and destructive, was reinforced with statistical approaches. This ensured reliability and enabled high-resolution visualization of spatial variations in bond strength. Wafer-level analysis showed radial and angular variations, with locally elevated bond strength in middle regions and stable values at edges. At the die level, PBA-free samples exhibited reduced bond strength at corners and higher strength near the center. After PBA, average bond strength increased substantially, but pronounced nonuniformities persisted. These findings demonstrate that <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\mathbf{4 P B}$</tex> and NI tests together provide a comprehensive framework for optimizing bonding processes and ensuring reliability in nextgeneration 3D integration.