Effect of 2-methylimidazole as a functional latent accelerator on the properties of low-temperature-curable conductive silver paste

The curing temperatures of silver conductive pastes typically exceed 180 ℃ when conventional anhydride or amine curing agents are used, with resistivity on the order of 10^{− 5} Ω•m. In this study, 2-methylimidazole (2-MI) was introduced as a latent accelerator into three different curing systems: dicyandiamide, p-hydroxyphenylacetic acid, and tetraethylenepentamine. The results showed that incorporating approximately 0.5 wt% 2-MI, the resistivity decreased from 4.1 × 10^{− 5} Ω•m to as low as 1.2 × 10^{− 6} Ω•m, the pencil hardness remarkably increased from 6B to 5 H, the curing time shortened from 40 min to 20 min, and the curing temperature lowered from above 180 ℃ to below 100 ℃. SEM reveals a more compact surface morphology, and DTA confirms a downward shift in exothermic peaks. FTIR detects new C ≡ C (≈ 2204 cm^{− 1}) and C ≡ N (≈ 2164 cm^{− 1}) triple bonds, likely induced by the ‘N’ atoms in 2-MI. These findings demonstrate that 2-MI acts as a multifunctional latent accelerator, enhancing both electrical and mechanical properties by promoting denser conductive networks and stronger chemical bonding.