With the rapid development of new energy vehicles and offshore wind power systems in coastal cities, the application scale of power devices is constantly increasing. However, the corrosion problem of power packaging interconnection materials caused by the humid air and chlorine-rich environment near the sea is gradually emerging. This study addresses the corrosion protection of sintered nano-copper by innovatively employing atmospheric pressure plasma jet (APPJ) technology with hexamethyldisiloxane (HMDSO) as precursor to construct organic-inorganic hybrid hydrophobic coatings on copper surfaces. Experimental results demonstrate that the coating exhibits a three-dimensional crosslinked Si-O network structure. The synergistic effect between surface micron-scale spherical clusters and methyl groups elevates the contact angle by 50 % to 153.1° Electrochemical characterization reveals that the coating positively shifts corrosion potential by 0.035 V and reduces corrosion current density from 6.008×10−7 A/cm2 to 5.542×10−7 A/cm2, while maintaining higher activation energy across the experimental temperature range (30–60℃). EIS tests show that the coating effectively increases the charge transfer impedance of the sample, indicating an improvement in corrosion resistance. The 168-hour immersion test confirms effective barrier against Cl−corrosive attack with preserved substrate integrity. Density functional theory (DFT) simulations elucidate that unsaturated methylated fragments in HMDSO preferentially graft onto copper surface via chemisorption, where strong interfacial bonding energies (-2.26 ∼ -4.38 eV) facilitate cleavage and crosslinking to form stable siloxane networks. This work proposes a novel anti-corrosion surface engineering strategy for copper interconnects, while revealing the plasma-induced interfacial bonding mechanisms of hybrid coatings, providing both theoretical and experimental foundations for developing durable electronic packaging materials.

In harsh offshore environments, large-area sintered nano-copper (Cu) interconnections, which serve as die attachment material or thermal interface material (TIM), are prone to degradation from hydrogen sulfide (H2S) corrosion. This study introduced a film-forming technique based on atmospheric pressure plasma jet (APPJ) to improve the corrosion resistance of large-area sintered nanoCu joint. The corrosion protection mechanism against H2S-containing atmospheric corrosion was investigated using both experimental methods and density functional theory (DFT) simulations. The key findings were as follows: (1) The deposition film, primarily composed of a Si-O3 network, effectively protected sintered Cu plate from corrosion by H2S gas, and maintaining the mechanical performance of sintered Cu joint after 384 h of H2S testing. (2) The dissociation products of the APPJ-treated precursor hexamethyldisiloxane (HMDSO), −OSiCH3 and −OSi(CH3)3, formed stable chemical bonds on the sintered nanoCu surface, resulting in the formation of −OSiCH3(O-CH3)2 fragments. (3) The −OSiCH3(O-CH3)2 fragments were unreactive toward to corrosion agents such as H2S, O2, and H2O, and also serving as a barrier to block their access to the sintered nanoCu surface. This study provided a comprehensive understanding of the corrosion protection mechanism of sintered nanoCu using APPJ-deposited films, offering valuable insights for improving the reliability of power electronics.