The influence of surface modification processes on the airtightness of copper sheet inserts

This study addresses the demand for improving the airtightness of copper sheet inserts in new energy vehicles by conducting surface treatments on copper sheets before injection molding. Through microscopic morphology characterization, surface roughness testing, and airtightness testing, it systematically compares the effects of three surface modification techniques—chemical etching, plasma etching, and composite chemical etching—on enhancing the airtightness of copper busbar inserts. Experimental results indicate that chemical etching forms micron-scale granular structures on the copper substrate, reducing high-pressure gas leakage by 49.63% and low-pressure gas leakage by 64.90%. Ar/O2 mixed plasma treatment generates nanoscale porous structures and oxide particles, while plasma-induced highly polar groups enhance interfacial bonding strength, leading to a 55.59% reduction in high-pressure gas leakage and an 82.39% reduction in low-pressure gas leakage. Composite chemical etching increases surface roughness while introducing polar groups, thereby improving surface activity and achieving a 65.79% decrease in high-pressure gas leakage and an 84.20% decrease in low-pressure gas leakage. Therefore, we believe that research on copper sheet surface modification techniques can enhance the airtightness of copper sheet inserts, providing better guidance for their production in the new energy vehicle industry.