Bonding and UV debonding behaviors of acrylate pressure-sensitive adhesives by rheological methods

UV debonding acrylate pressure-sensitive adhesives (UPSAs) are necessarily applied in the semiconductor industry. To establish a comprehensively understood method is important to detect their bonding and debonding behaviors. In this paper, rheological methods, including Three Interval Thixotropy tests (3ITT) and Tack test modes were used for characterizing series of UPSAs. Vinyl groups were successfully grafted onto the acrylate copolymer chains through isocyanate condensation reactions, which were characterized by nuclear magnetic resonance spectroscopy, Fourier transform infrared spectroscopy and gel permeation chromatography. From the maximum normal force in the Tack test modes, UPSAs after UV irradiation showed obvious debonding behaviors in short-time stress analysis. The recovery percentage of the storage modulus in 3ITT tests indicated that 0.6 wt% isocyanate curing agent made the UPSAs good resistance to deformation. Under the limit of 30 wt% pentaerythritol diacrylate (PETA), the rheological adhesion performance of UPSAs increases accordingly with the PETA content, which was also confirmed by 180° peel strength tests. From the microscope images of the wafer surfaces after peeling off the UPSA tapes, rheological characterization methods can help designing UPSAs with clean debonding properties.