Tuning Photocurable Solder Resist Performance via Tetrahydrophthalic Anhydride Content: Experimental and Molecular Dynamics Investigation

ABSTRACT The rapid development of 5G high‐frequency communication and electronic device miniaturization imposes stringent requirements on alkali‐developable solder resist (SR) inks for printed circuit boards. Tetrahydrophthalic anhydride (THPA) is the industry‐standard carboxyl‐introducing monomer for SR resins, yet the microscopic mechanism of THPA regulating resin performance remains underexplored. Herein, a series of THPA‐modified naphthalene‐based photocurable resins with gradient THPA contents was synthesized via an industrially compatible one‐pot method. We systematically characterized their UV curing kinetics, glass transition temperature ( T g ), tensile stress–strain properties, dielectric performance, and alkali developability, clarifying the regulation law of THPA content on the comprehensive properties. To provide molecular‐level interpretation for the experimental trends, we adapted a mature epoxy‐amine crosslinking simulation protocol to construct full‐atom molecular dynamics (MD) models of the CC crosslinked networks. The simulated variation trends of T g , tensile modulus, and density are qualitatively consistent with experimental results. MD simulations further interpreted how THPA regulates the macroscopic properties of resins from the perspective of crosslink density, chain mobility, free volume fraction, and carboxyl content. This work provides insights for high‐performance SR resin design.