Controlled Thermal Imidization of Thermoplastic Polyimide for Temporary Bonding and Debonding in Advanced Packages

Temporary bonding and debonding (TBDB) is a key technology in the semiconductor field to enable 2.5D/3D integration of devices. However, the conventional polyimides, which serve as the laser-response material in TBDB, exhibit extremely poor solubility in aprotic polar solvents due to high-temperature imidization, limiting the cleaning process for wafers after debonding. Herein, a feasible method of controlling the curing temperature to enhance the solubility of thermoplastic polyimide (TPI) has been developed. The results proved that the ultimate solubility of TPI cured at 200 °C (TPI-200 °C) could be as high as 28.4 wt %. Besides, TPI-200 °C exhibits excellent heat resistance, outstanding mechanical properties, and ultrahigh absorptivity (99.96%) at a 355 nm UV wavelength. Meanwhile, we demonstrate the feasibility of the as-prepared TPI material for application in the TBDB process, showing excellent efficiency and low cost, and the follow-up elemental analysis of the cleaned wafer surfaces proved that TPI-200 °C can be completely removed after debonding. All these results demonstrate that TPI materials that can be used for TBDB are promising for ultrathin chip packaging and wafer level packaging (WLP) in the field of advanced electronic packaging.