Behaviors of ZnO-doped silver thick film and silver grain growth mechanism

The ZnO-doped silver paste with good thixotropy was prepared and its cofiring characteristics with ferrite green tapes were studied. The sheet resistivity of silver film decreased with an increasing temperature because of larger grain size and denser film. 2 wt.% ZnO-doped silver thick film showed low sheet resistivity (0.97 mΩ/□ (mΩ/mm2)), high adhesive strength (0.85 kgf·mm−2) and excellent compatibility. ZnO scattered at the silver grain boundaries according to SEM photographs. The pinning effect led to a decreased grain size when the amount of ZnO increased. A grain growth exponent n = 3.0–4.58 was evaluated by minimizing the deviation in the function Dn − D0n = k (T) t to the experimental data. The average activation energy (47 kJ/mol) indicated that surface diffusion mass transportation was the mechanism of silver grain growth.

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