High Resolution of Negative Photosensitive Polyimide With Low Coefficient of Thermal Expansion

ABSTRACT According to the different application scenarios in the field of electronic packaging, it is of great research significance to screen out the suitable PSPI with low coefficient of thermal expansion (CTE). The introduction of a rigid structure into the backbone structure can effectively reduce the CTE. In this paper, polyamine esters (PAEs) were prepared by acyl chlorination method using diamine 2,5‐bis(4‐aminophenyl)pyridine (PRD) containing pyridine structure and four different dianhydrides, and then a series of films were finally obtained by heat curing treatment at different temperatures and heat curing treatment at different temperatures after light curing. The CTE value of all films decreased with the increase of heat treatment temperature. The CTE value of the films of PSPI and PSPI‐p series is higher than that of PI series films, and the PP series has the lowest CTE value in PI, PSPI, and PSPI‐p due to the stronger rigidity of PMDA. The photoresists formed by the four different backbone structures can achieve an optical resolution of 10 μm. The research results and laws of this paper can screen different spindle structures and heat treatment temperatures according to the required different CTE values for the field of electronic packaging.