Temporary bonding adhesives that enable damage-free fixation and on-demand debonding are critical for precision manufacturing processes such as semiconductor, OLED, and PCB/FPC fabrication. This study developed a 254 nm UV-responsive pressure-sensitive adhesive (PSA) based on thymine photodimerization for efficient and residue-free debonding. By integrating the thymine moiety into an acrylic PSA system with butyl acrylate (BA),methyl methacrylate (MMA), and acrylic acid copolymers, 254 nm UV light exposure triggers adhesion loss through photodimerization-induced crosslinking. As a result, the peel strength decreases significantly from 11.22 to 3.16 N/25 mm. Rheological analysis reveals a distinct debonding mechanism, where the reduction in adhesion is predominantly governed by a decrease in high-frequency loss modulus (G"), associated with the disruption of hydrogen-bonded networks, rather than conventional extensive crosslinking-induced dewetting. In addition, spatially controlled debonding is demonstrated via patterned UV irradiation. This work provides new insights into the design of photo-switchable PSAs, offering a promising strategy for high-precision temporary bonding applications in advanced manufacturing.