Effect of castor oil based urethane oligomer on properties of UV-curable pressure sensitive adhesive for peelable wafer dicing tape
Panpan Hao, Bingyan Sun, Xiaomeng Chu, Yujuan Sun, Xuteng Xing, Shaojie Liu, Erjun Tang, Xiaodong Xu
Abstract
In this work, the isocyanate terminated castor oil based urethane oligomer (CO-IPDI) was prepared by the reaction of castor oil and isophorone diisocyanate (IPDI) without adding any organic solvent. After the acrylic copolymer pressure sensitive adhesive (PSA) was heated at 80 °C for 20 min, it was mixed with CO-IPDI, trifunctional acrylic monomer and photo-initiator in a certain proportion to give a UV-curable peelable adhesive for silicon wafer cutting process. Before UV irradiation, the acrylate copolymer chains were cross-linked by CO-IPDI to form a network. After UV irradiation, another polymer network formed by photo-polymerization of trifunctional acrylic monomer hold together with it to form an interpenetrating network (IPN) structure. The results showed that this IPN structured UV-curable peelable PSA had a high peeling strength of 13.99 N/25 mm before UV curing to meet the suggested requirements for silicon wafer cutting process. The peeling strength was significantly decreased to 0.49 N/25 mm after UV curing, and the tape was easily peeled off from wafer with about 0.96% residual adhesive estimated by the area ratio of all residual adhesive particles to silicon wafer observed by scanning electron microscopy. This work provides a new candidate idea for green and efficient preparation of UV-curable peelable PSA.