Positive-tone photodefinable polyimide for low temperature cure

• Main Authors: Matsukawa, Daisaku, Enomoto, Tetsuya, Ono, Keishi, Ohe, Masayuki
• Format: Conference Proceeding
• Language: English
• Subjects: Adhesives; Chemicals; Low Temperature Cure; Photosensitivity; Polyimide; Polyimides; Resistance
• ISSN: 2373-5449; 2475-8418
• DOI: 10.1109/ICSJ.2014.7009603

Photodefinable Polyimides (PI) and polybenz-oxazoles (PBO) which have been widely used for various electronic applications such as buffer coating, interlayer dielectric and protection layer usually need high temperature cure condition over 300 °C to complete the cyclization and achieve good film properties. In addition, PI and PBO are also utilized recently for re-distribution layer of wafer level package. In this application, lower temperature curability is strongly required in order to prevent the thermal damage of the semi-conductor device and the other packaging material. Then, to meet this requirement, we focused on pre-cyclized polyimide with phenolic hydroxyl groups since this polymer showed the good solubility to aqueous TMAH and there was no need to apply high temperature cure condition. As a result of our study, the positive-tone photodefinable material could be obtained by using DNQ and combination of epoxy cross-linker enabled to enhance the chemical and PCT resistance of the cured film made even at 170 °C. Furthermore, the adhesion to copper was improved probably due to secondary hydroxyl groups which were generated from reacted epoxide groups. In this report, we introduce our concept of novel photodefinable positive-tone polyimide for low temperature cure.