Preparation of micron-sized flake copper powder for base-metal-electrode multi-layer ceramic capacitor

The preparation of flake micron-sized copper powders with the chemical–mechanical method was investigated. Reaction of [Cu(NH3)4]2+ complex with hydrazine hydrate at 85 °C produced monodispersed fine spherical copper powders, which were used as precursor to synthesize flake copper powders by the ball milling process. The flake copper powders having an excellent dispersibility and a uniform size of 9 ± 2 μm could be achieved. Thermogravimetry (TG), differential thermogravimetry (DTG) and differential thermal analysis (DTA) of the flake copper were investigated with thermal analyzer. The results showed that the oxidizing temperature increased with a decreasing specific area. The flake copper powder particles were employed as functional conductive materials in copper thick film paste for base-metal-electrode multi-layer ceramic capacitors (BME-MLCCs). Excellent connection between internal and terminal electrode and even distribution of glass in copper thick film can be observed by polarized light photograph. The dense thick films were also found by scanning electron microscopy (SEM) analysis, and the high densification of the fired films could be attributed to the “framework” effects.