| 摘要 |
<p>A layer of copper foil (14, 16) is etched to a required conductor pattern, coated with a thin layer of uncured fibre-free epoxy polymer, (26, 28) and then another layer of copper foil (22, 24) is placed on top. The sandwich is bonded by heat and pressure which cures the layer of polymer (26, 28). The top foil (22, 24) is etched to form another required conductor pattern which is both electrically insulated from and mechanically adhered to the underlying conductor layer (14, 16) by the layer (26, 28) of cured polymer. These steps are repeated as often as is necessary to build up the required number of layers. Interconnections between different layers are either formed by drilling and plating through holes (30), or by a etching hole in a conductor (222) and then plasma etching through the exposed polymer (226) to the underlying conductor (214) with subsequent metal plating (235) to join the conductors in the different layers. The outermost conductive layer can be formed as physically isolated pads or islands of metal. Connections to and from these pads are through conductors buried in the underlying layer of the polymer.</p> |
