A Rapid Surface Modification Method for Copper Based on Bipyridine Coordination Chemistry and Its Enhanced...

In aerospace, electronic systems of spacecraft are regularly subjected to extreme temperature fluctuations, which pose significant challenges to the bonding reliability. However, the critical role of interfacial interaction in alleviating the deleterious stresses due to thermal expansion coefficient disparities between dissimilar materials is often underappreciated. In this study, we introduce a simple method to enhance adhesion by ultrasonicating copper in a 0.2% amino-bipyridine solution, inspired by pyridine-copper coordination chemistry, which increases the polyurea adhesive strength from 13.97 to 16.92 MPa and ensures bond integrity through 48 thermal cycles ranging from -196 to 120 °C. Characterization using SEM, XPS, and contact angle measurements elucidates the mechanisms underlying the improved adhesion. Moreover, we reveal for the first time that the thermal diffusivity and thermal contact resistance are closely associated with the decline in the shear strength of bonding joints after thermal cycling. These findings may offer novel insights into the nondestructive evaluation of bonding durability. In summary, the bipyridine-based surface modification enhances the durability of copper adhesive joints under extreme thermal conditions, offering a promising approach to improve the reliability of aerospace electronic devices.