In one embodiment of the invention, photolithographic masking and etching is used to form a matrix array of mutually isolated ferromagnetic elements (25'). The elements are magnetized and a single layer of conductive ferromagnetic particles (33) is adhered to an upper surface of each of the ferromagnetic...http://www.google.es/patents/US5221417?utm_source=gb-gplus-sharePatente US5221417 - Conductive adhesive film techniques
