A method of producing a multilayer system comprises depositing a seed layer (4) of copper on an electrically insulating substrate (2). A resist is formed on the copper seed layer (4), and the seed layer is electroplated with copper to produce a desired conductor pattern (8). An air firing dielectric (10) is screen printed over the pattern (8) and the exposed parts of the seed layer (4) are fired in air. The outer skin of the pattern is oxidised as is also the whole of the seed layer other than where it underlies the copper pattern. The oxidised regions of the copper both form a firm bond with the dielectric and inhibit the migration of oxgen into the inner regions of the conductor pattern (8). Also the oxidation of the seed layer renders it non-conductive and therefore obviates the need for its removal. Through holes 12 produced in the dielectric enable electrical connection to the pattern (8).