Effect of Interfacial Resin Distribution on the Interfacial Properties of Overmolded Components With Woven and Unidirectional Laminates

ABSTRACT The interfacial bonding strength is critical for structural integrity and reliability of overmolded components. While extensive research has focused on optimizing processing parameters and applying surface modifications to enhance interfacial bonding, the fundamental role of interface resin still remains insufficiently understood. This study systematically investigated the effect of interface resin distribution on interfacial performance of overmolded components. Manufactured woven and unidirectional carbon fiber reinforced polyether ether ketone laminates were employed as inserts to represent different surface resin patterns. Results revealed that resin‐rich zones at intersections of warp and weft fibers in woven laminates significantly enhanced interfacial bonding compared to resin‐deficient surfaces of unidirectional laminates. Furthermore, by introducing resin films onto insert surface, it was demonstrated that an optimal interfacial resin layer acted as an engineered “adhesive,” promoting crack deflection from interface into injection part and thereby substantially improving bonding strength. Microscopic analysis confirmed transition of failure mode and associated strengthening mechanism. The interlaminar shear strength of overmolded components with woven and unidirectional laminates increased by 23.8% and 39.3%, respectively. This work elucidates the significant influence of insert's surface microstructure and provides a potential approach for strengthening interfaces through interface resin design, offering a practical guidance for manufacturing high‐performance overmolded composites.