Research advances in the ultrasonic-assisting adhesive bonding

Adhesive bonding is integral across countless industrial domains, although conventional practices present limitations. Ultrasonic-assisting adhesive bonding has recently emerged as an enabling technology, yet a comprehensive review elucidating the fundamentals of this approach is lacking. A critical assessment of ultrasonic-assisted bonding in comparison to traditional and other field-assisting adhesive bonding methodologies is provided. The advantages of ultrasonic assistance are highlighted, including enhanced joint strength, accelerated curing, and reduced defects. The requisite ultrasonic bonding equipment and procedural steps are outlined. The multifaceted physical and chemical impacts of ultrasonic vibrations are summarized, encompassing effects on interface interlocking, wettability, chemical bonding, and adhesive flow and curing. Critical ultrasonic parameters are discussed, including ultrasonic amplitude and time, and surface pretreatment. The transition in failure modes from adhesive and cohesive failure to substrate-interfacial failure when ultrasonic energy is applied is documented for single-lap joints. Techniques integral for characterization are summarized, including AFM, SEM, contact angle analysis, FTIR, ultrasonic capillary experiments, viscosity measurement, and XPS.