Effect of Non-Uniform Temperature Field on Sintering Performance of Conductive Silver Paste in Laser Sintering

The non-uniform temperature field in laser sintering critically affects conductive silver paste performance, yet its quantitative relationship with sintering mechanisms remains unclear. This study addresses this issue by proposing effective sintering temperature (<i>T_a</i>) and effective sintering time (<i>S_a</i>) as metrics to link laser parameters and sintering temperature field with sintering performance. Through full-factorial experiments, finite element simulation, and in situ thermal monitoring, it was revealed that (1) Increasing laser power and reducing laser scanning speed effectively reduce resistivity. For example, at 10 W and 0.1 mm/s, the resistivity reached 6.81 μΩ·cm, which was 88.9% lower than the value of 61.11 μΩ·cm at 2 W and 0.5 mm/s. (2) The resistivity exhibits a threshold effect in its reduction across low-power (<3 W), medium-power (3~4 W), and high-power (>5 W) ranges. (3) The action of laser sintering parameters on sintering performance through <i>T_a</i> and <i>S_a</i>. The resistivity decreases are correlated with <i>T_a</i>, exceeding the exothermic peaks (<i>T</i>₁ = 196 °C and <i>T</i>₂ = 232 °C). Unlike prior qualitative analyses, this work quantifies how non-uniform temperature fields govern sintering through <i>T_a</i> and <i>S_a</i>, offering a quantitative method to analyze the temperature field's effect on sintering performance.