γ-ray irradiation effects on mechanical and thermophysical properties of Ajinomoto build-up film: A comparative study

Ajinomoto Build-up Film (ABF) has been extensively applied in advanced electronic packaging. Irradiation-induced degradation in its mechanical and thermophysical performances poses potential threats to the long-term reliability of packaging structures. In this work, commercial GL102 ABF samples were subjected to 10 kGy 60 Co γ-ray irradiation under ambient conditions, and their variations in microstructure, chemical composition, mechanical properties, and thermophysical behaviors were systematically characterized. SEM morphological analysis confirmed the generation and increased abundance of pore-like microdefects after γ-ray exposure, while the maximum projected size of inorganic filler particles remained basically stable with negligible changes. Mercury intrusion porosimetry (MIP) tests further demonstrated that irradiated ABF possessed a higher mass-normalized mercury intrusion volume, verifying distinct pore structural characteristics between the irradiated and pristine ABF samples. FTIR and XPS characterizations collectively revealed evident alterations in the resin matrix functional groups and near-surface chemical states triggered by irradiation. In terms of mechanical performances, the average tensile strength of ABF decreased from 64.38 MPa to 60.68 MPa after irradiation, whereas the elastic modulus exhibited only a slight decline from 7.15 GPa to 7.01 GPa, indicating mild irradiation-induced mechanical deterioration. For thermophysical properties, the density and thermal diffusivity of ABF remained nearly invariant before and after irradiation. Notably, DSC test results illustrated that the irradiated ABF possessed consistently higher specific heat capacity than the pristine sample across the entire tested temperature range, with a relative increment of approximately 5.5%–7.4%. Overall, 10 kGy γ-ray irradiations can induce distinguishable microstructural defects and chemical evolution in highly filled ABF composites, while the bulk mechanical properties, density, and thermal diffusivity exhibit excellent irradiation resistance with limited variation.