Study On Copper Conductor Slurry And Its Sintering Process

As foundation materials of electronic components, high quality of electronic paste has a big demand. As scarce of precious metal resources and precious metal of price increasing, development of base metal which has good properties and low-cost becomes a pressing problem. High-frequency characteristics and electrical conductivity of copper is better than gold, and copper doesn’t have migration phenomena of silver ion. Copper paste becomes a new research hotspot.In this paper, preparation of high tap density of copper powders which used in copper paste and sintering process of copper paste were investigated. The aim was to prepare a copper film which has a high relative density, a good conductivity and an excellent adhesion strength. The products were characterized by XRD、SEM、TG-DSC、nitrogen adsorption specific surface analyzer and particle size distribution. Effects of copper powders and sintering process on microstructures and properties of copper films were discussed.Copper powders were prepared by a two-step liquid reduction method. Cuprous oxide particles were used as precursors and the effect of the precursors on morphologies, particle size and properties of copper powders was investigated. Moreover, effects of density of copper powders on microstructures and properties of copper films were discussed. The results showed different particle sizes of cubic, spherical, octahedral cuprous oxide particles were prepared at different glucose concentrations and PVP amounts. And spherical copper powders which were prepared using cubic cuprous oxide particles as precursors had a high tap density (4.0g/cm3), a small specific surface area and a narrow size-distribution, and applied to conductive copper paste. In addition, the copper film which was prepared using high tap density of copper powders had a high relative density, a small square resistance, an excellent adhesion strength and a good weldability.Heating rate, sintering holding time and sintering temperature were investigated. The better sintering process of copper paste was obtained:heating rate of low-temperature section (23-500℃) was 75℃/min; heating rate of high-temperature section (500-850℃) was 70℃/min; sintering temperature was 850℃; sintering holding time was 8 min. The copper film which was prepared at the sintering process had a high relative density, a small square resistance (2.1mΩ), an excellent adhesion strength (0.944kg/mm2) and a good weldability.