Stiffener-Integrated Flexible PCB Blistering Prevention

The patent applies preliminary action by forming a protective film on the flexible printed circuit board before attaching the stiffener. This protective film is designed to be removed after the reflow process, allowing the stiffener to be securely attached to the photosensitive resin composition without causing blistering. The protective film prevents adverse reactions during the reflow process while enabling strong adhesion between the stiffener and the resin composition.

The patent uses an intermediary substance (the protective film) between the stiffener and the photosensitive resin composition during the reflow process. This intermediary film acts as a mediator that prevents direct contact between the thermosetting adhesive and the photosensitive resin composition, thereby preventing blistering while still allowing the stiffener to be securely attached after the film is removed.

The patent replaces the mechanical punching and molding system with a photolithography-based system. Instead of using expensive molds and manual positioning for cover lay film production, the invention uses photoresist and UV exposure to create the protective film pattern. This substitution of mechanical processes with optical/chemical processes significantly reduces manufacturing costs while maintaining the protective functions.

The patent changes the manufacturing parameters from mechanical (punching, molding) to optical/chemical (photolithography, UV curing). This parameter change enables the production of cover lay films with complex patterns without requiring expensive molds, thereby reducing manufacturing costs while maintaining flame retardancy and protective properties.