Electroless copper plating onto printed lines of nanosized silver seeds

It was demonstrated that continuous copper films could be grown onto printed lines of nanosized silver colloids. These silver colloids, with an average size of similar to 55 nm, were printed on alumina substrates by either an ink- jet printer or a felt-tip pen and then served as a seed layer for subsequent electroless copper plating. A complete copper film could be obtained in less than 10 min when the surface density of silver particles was greater than 1.5 x 10(9) cm(-2) and an appropriate plating solution to produce a mean copper growth rate of 7.2 mu m h(-1). After 30 min of growth and a resulting film thickness of similar to 3.6 mu m, the measured electric resistivity of the lines was about 1.8 x 10(-6) Omega cm, being very close to bulk copper. In addition, the measured peel adhesion strength between the deposited copper film and the Al2O3 substrate was larger than 6 kg/cm. (c) 2007 The Electrochemical Society.