Abstract: It is often required to solder an electrical connection to a component or a lead thereto via a contact pad. At present pads are commonly of materials that tend to oxidize during any subsequent heat processing of the device, and are then difficult to solder. It has now been discovered that certain alloys of copper containing manganese may be used to construct contact pads that are both solderable and remain so even when ovened in air at 200.degree. C., and the invention provides a method of constructing solderable contact pads upon a chosen substrate, in which method there is formed on the relevant area of the substrate a layer of such a manganese/copper alloy.

Abstract: The diphthalocyanines of certain tri- and tetravalent metals, especially those of the empirical general formulae (PC).sub.2 H.M.sup.III (Ia) or (PC).sub.2. M.sup.IV (Ib) (wherein M.sup.III and M.sup.IV represent respectively the tri- and tetravalent metal, and "PC" represents the phthalocyanine ring system) are well-known for their semiconductor and/or electrochromic properties. They are presently prepared by a process in which an organic derivative of the metal (an acetate, for example) is reacted, at about 300.degree. C. in a sealed tube, with an appropriate phthalonitrile. This process is itself unsatisfactory, and the invention provides a novel preparative process, process technique and application method.