Method for preparing dispersed crystalline copper particles for electronic applications
- PDF / 804,578 Bytes
- 4 Pages / 584.957 x 782.986 pts Page_size
- 27 Downloads / 194 Views
Method for preparing dispersed crystalline copper particles for electronic applications Ionel Halaciuga, Sylas LaPlante, and Dan V. Goiaa) Center for Advanced Materials Processing, Clarkson University, Potsdam, New York 13699 (Received 25 June 2009; accepted 21 July 2009)
Dispersed crystalline copper particles were prepared by reacting aqueous dispersions of CuCl with ferrous citrate. We report that the Fe(II) citrate complex can reduce rapidly and completely cuprous chloride to metallic copper and propose a mechanism for the reaction observed. By changing the precipitation conditions, copper particles with sizes varying from 250 nm to 2.0 mm were obtained. The method described represents a simple and versatile approach for preparing copper powders for electronic applications. Due to their applications in catalysis, medicine, biology, microelectronics, metallurgy, and energy sustainability, metallic particles have been recently the object of intense research. In the electronic industry, copper is the material of choice in many applications because it offers excellent electrical conductivity at a fraction of the cost of noble metals. For this reason, copper particles of various sizes and shapes are used extensively as precursors for conductive structures incorporated in multilayer ceramic capacitors,1 printed circuit boards,2 and other electronic devices.3 Various methods including atomization,4 pyrolysis,5 electrolysis,6 radiolysis,7 and reduction of copper salts in reverse micelles8 and solutions9,10 have been used to prepare dispersed copper particles. Precipitation in homogeneous solutions is a versatile approach11,12 because it takes advantage of a broad range of solvents and a large variety of reductants,13 dispersants, and complexing agents.14–16 For optimum performance, the copper particles used in microelectronics should be uniform with modal diameters in the 0.5- to 2.0-mm range. Also, they need to be non-aggregated and display good oxidation resistance. To provide these features, many existing precipitation protocols use high-molecular-weight polymers/ dispersants. As a result, the powders obtained contain significant amounts of residual organic matter, which often interferes with their processing into electronic devices. Furthermore, most processes involve toxic reagents17 or result in environmentally undesirable byproducts. This study shows that dispersed copper particles can be prepared without polymeric dispersants by reducing cuprous chloride with Fe(II) citrate. The low organic residue, good oxidation resistance, and desirable thermo-mechanical a)
Address all correspondence to this author. e-mail: [email protected] DOI: 10.1557/JMR.2009.0390 J. Mater. Res., Vol. 24, No. 10, Oct 2009
http://journals.cambridge.org
Downloaded: 14 Mar 2015
properties make the resulting copper powders particularly suitable for electronics applications. Copper (I) chloride (CuCl), trisodium citrate dihydrate (Na3C6H5O72 H2O), iron (II) sulfate heptahydrate (FeSO47 H2O), and sodium dioctyl sulfosuccinate (AOT; A
Data Loading...
