PCS-photoformed conductors on ceramic substrates

PCS, a system for the formation of high-definition metal powder images that are transformed into the corresponding conductive patterns by firing, is described with particular reference to gold conductors. The PCS process consists of coating precleaned alumina substrates with a thin, amorphous layer of a mixture of nitrophenyl dihydropyridine derivatives, exposing this layer through a mask to UV light thereby changing the exposed material into a tacky state, toning the exposed areas, and firing the toned substrate by a conventional thick-film method. The PCS process creates high resolution conductors, up to 25-microns-resolution line/space with an excellent edge definition of +or-3 microns, which can be fired several times. The sheet resistivity, which depends on the toner materials used, can be adjusted in the range of 10-20 m Omega /square at fired thicknesses in the range of 3-5 microns. Bondability is comparable to that of conventional thick film gold pastes with pull forces higher than 10 cN for 37.5-micron gold wire. Compatibility with dielectric and resistor pastes as well as with light-sensitive dielectric thick-film materials is shown.<>