Evaluating the Adhesive Properties of Electroless Cu on Glass-Reinforced Epoxy-Based Build-Up Dielectric Films via Nanoindentation

This study investigates the adhesion properties of electroless copper (Cu) plated on glass-reinforced epoxy-based build-up films (Ajinomoto Build-up Film, ABF) using nanoindentation techniques. The adhesion strength was quantified through critical load measurements in scratch tests, revealing critical loads of approximately 19.7 mN for chemical-U and 13.3 mN for chemical-A, corresponding to adhesion strengths of 0.46 kgf/cm and 0.16 kgf/cm, respectively. Microscopic analysis confirmed uniform copper distribution at the interface within the first minute of deposition, with notable differences in mechanical properties between the two plating chemicals. The study highlights the importance of epoxy exposure control via the desmear process, which significantly enhances ABF/Cu adhesion by expanding the contact area. Additionally, the role of the pegging effect and chemical bonding (C-O bond formation) in improving adhesion is emphasized. These findings provide valuable insights into optimizing the interfacial adhesion of ABF/Cu systems for advanced microelectronic applications.