Department of Materials Science and Engineering, KAIST, Yuseong-gu, Daejoen, Korea.
Nanotechnology. 2011 Jun 3;22(22):225701. doi: 10.1088/0957-4484/22/22/225701. Epub 2011 Apr 1.
To fabricate a low cost, highly conductive ink for inkjet printing, we synthesized a gram scale of uniformly sized Sn nanoparticles by using a modified polyol process and observed a significant size-dependent melting temperature depression from 234.1 °C for bulk Sn to 177.3 °C for 11.3 nm Sn nanoparticles. A 20 wt% of Sn nanoparticles was dispersed in the 50% ethylene glycol: 50% isopropyl alcohol mixed solvent for the appropriate viscosity (11.6 cP) and surface tension (32 dyn cm(-1)). To improve the electrical property, we applied the surface treatments of hydrogen reduction and plasma ashing. The two treatments had the effect of diminishing the sheet resistance from 1 kΩ/sq to 50 Ω/sq. In addition, conductive patterns (1 cm × 1 cm) were successfully drawn on the Si wafer using an inkjet printing instrument with conductive Sn ink. The maximum resistivity for an hour of sintering at 250 °C was 64.27 µΩ cm, which is six times higher than the bulk Sn resistivity (10.1 µΩ cm).
为了制造一种用于喷墨打印的低成本、高导电性油墨，我们使用改良的多元醇工艺合成了克级尺寸均匀的 Sn 纳米粒子，并观察到显著的尺寸依赖性熔化温度降低，从块状 Sn 的 234.1°C 降低到 11.3nm Sn 纳米粒子的 177.3°C。将 20wt%的 Sn 纳米粒子分散在 50%乙二醇：50%异丙醇混合溶剂中，以获得适当的粘度（11.6cP）和表面张力（32 dyn cm(-1)）。为了提高导电性，我们对 Sn 纳米粒子进行了氢气还原和等离子体灰化的表面处理。这两种处理方法都能将方块电阻从 1kΩ/sq 降低到 50Ω/sq。此外，还使用喷墨打印仪器在 Si 晶片上成功绘制了导电 Sn 油墨的导电图案（1cm×1cm）。在 250°C 下烧结 1 小时后的最大电阻率为 64.27µΩ cm，是块状 Sn 电阻率（10.1µΩ cm）的六倍。
