<p>The Al-Zn-LDH sealing film, owing to its intrinsically strong hydrophilicity, is prone to interfacial failure in humid–thermal and salt spray environments, which restricts its long-term application in electronic materials. In this study, a combined modification strategy involving thiourea intercalation and stearic acid surface treatment is employed to improve both the chemical corrosion inhibition behavior and the physical barrier properties of the film. Thiourea partially substitutes the interlayer anions, introducing a stable corrosion-inhibiting effect, whereas stearic acid surface modification markedly enhances film compactness and hydrophobicity. After optimization, the TU-SA5-LDH film exhibits superior overall protective performance with a significantly increased hydrophobic character. The corrosion current density is reduced to 3.644 × 10^–6 A·cm⁻², nearly two orders of magnitude lower than that of the unmodified LDH film. Moreover, after 10 d of salt spray exposure, the film maintains a relatively high interfacial impedance of approximately 1.764 × 10⁵ Ω·cm², indicating a pronounced improvement in barrier stability. These results demonstrate that the combined regulation of interlayer chemistry and surface characteristics effectively alleviates the inherent hydrophilicity of LDH sealing films and provides a practical modification route and experimental basis for enhancing the long-term corrosion resistance and interfacial reliability of aluminum-based electronic materials under complex humid and saline conditions.</p>