Chuang K C, Lee Wen-Hsi
Department of Electrical Engineering, National Cheng Kung University, Tainan, Taiwan, 71011, R.O.C.
J Nanosci Nanotechnol. 2021 Sep 1;21(9):4726-4734. doi: 10.1166/jnn.2021.19125.
With the development of thick-film paste, silver and copper are circulating in the market as the electric conductive fillings currently. Unfortunately, the cost of silver is exceedingly high, while the copper has to be sintered in the reducing atmosphere. In this study, we proposed to exert aluminum as the filling due to its low cost, good electrical conductivity, and capability of being sintered in air. By means of the fracture mechanism of the oxidation layer of the Al surface and the liquid phase sintering, the Al paste with high solid content is used to implement high electrical conductivity. Based on that Al powder with large particle size tends to fracture easily, while it is easy for Al powder with small size to fill the gap, we mixed Al powder with large and small particle sizes at different proportion, so that the internal micro-structure and the oxidization are observed. However, when glass frit was added into mixed Al powder, the Al particles are wet by glass frit for bonding Al particles as well as inhibiting oxidation. Effect of the glass frit content and the solid content of Al paste on conductivity are investigated in this study. The sheet resistance of Al paste sintered at 850 °C for 10 min. can be reduced to 4.5 mΩ/□ when Al paste is formulated based on the mixed Al particles with proportion of big to small (4:1) at 10 wt% glass frit content and 80 wt% solid content.
随着厚膜浆料的发展，银和铜作为目前的导电填料在市场上流通。不幸的是，银的成本极高，而铜必须在还原气氛中烧结。在本研究中，我们提议使用铝作为填料，因为其成本低、导电性好且能够在空气中烧结。借助铝表面氧化层的断裂机制和液相烧结，使用高固含量的铝浆料来实现高导电性。基于大粒径铝粉容易断裂，而小粒径铝粉易于填充间隙这一情况，我们将不同比例的大粒径和小粒径铝粉混合，以便观察其内部微观结构和氧化情况。然而，当将玻璃料添加到混合铝粉中时，铝颗粒会被玻璃料润湿，从而粘结铝颗粒并抑制氧化。本研究考察了玻璃料含量和铝浆料固含量对导电性的影响。当玻璃料含量为10 wt%、固含量为80 wt%，基于大粒径与小粒径比例为4:1的混合铝颗粒配制铝浆料时，在850℃烧结10分钟后，铝浆料的方阻可降至4.5 mΩ/□。
