Copper conductor compositions

Claim 1

A composition suitable for use in fritless conductor overprint applications which is an admixture of finely divided particles consisting essentially of (a) 10-50% wt. copper metal, all particles of which are less than 2 μm in largest dimension, less than 10% are less than 0.5 μm in largest dimension, have an average particle size of 0.7-1.2 μm and average surface area of less than 2 m 2 /g; (b) 90-50% wt. finely divided copper metal particles, substantially all of which are 1-10 μm in largest dimension and have an average particle size of at least 1.5 μm; (c) 0.2-2% wt. of less than 10 μm particles of a reducible heavy metal oxide selected from the group consisting of oxides of lead, bismuth, cadmium, cobalt, nickel and mixtures and precursors thereof; (d) 0-1.0% wt. of less than 5 μm particles of a refractory metal selected from the group consisting of tungsten, molyhadenum, thenium and mixtures and alloys thereof: and (e) 0-5.0% wt. of a noble metal selected from the group consisting of palladium, platinum, ruthenium, irridium, rhodium and mixtures thereof having a surface area of 2-10 m 2 /g.