| 摘要 |
<p>1277615 Printed circuits STANDARD TELEPHONES & CABLES Ltd 16 Oct 1970 [21 Oct 1969] 51479/69 Heading H1R In order that a resonator element 16 of an electromechanical resonator, Fig. 8, shall be spaced apart parallel to the substrate 15 carrying the conductor pattern 14a, 13, 12a &c. the method of manufacture includes the step of providing a layer of chemically different material to that of the elements and substrate between the resonator element and the substrate, the layer having a "window" etched in it to allow the area 11a of conductor to extend from the substrate, and support the resonator element such that when the latter step of etching away the layer is performed, the element is left supported parallel to the substrate. The resonator element may be of Ni-Fe alloy, e.g. Ni Span C Elinovar and Thermolast; the chemically different layer of copper; the conductors of gold; and the insulating substrate of glass or epoxy glass board. In a preferred method, a layer of copper is electroplated on to a sheet of Ni-Fe material from which the resonator element is to be made and a "window" etched in the copper corresponding to the "root" of the element, further holes being etched through both layers to form reference points, for the photo-lithographic process used to mask the surfaces. Conductor areas 11a, 12a &c. are formed on the copper surface and infill the window area 11 (Fig. 5A) and the substrate bonded to the conductors using an epoxy base resin. The Ni-Fe layer is then etched to the shape of the resonating element and the copper layer is then removed by further etching. Ammonium persulphate in ammonia may be used as the copper etch, potassium iodide and iodine to etch the gold when forming the conductors and ferric chloride to etch the Ni-Fe layer, which also attacks the copper layer. Fig. 10 and Figs. 16, 25 (not shown) show further forms of resonator wherein conductors and substrates are formed on both sides of the resonator element, addition layers of copper being provided as required above the element, windows, extending through these layers to the substrate, being provided to define supports for the upper conductive and substrate areas. The method of producing the arrangement of Fig. 8 may be reversed if required, i.e. starting with the substrate and building up layers therefor.</p> |
