| 摘要 |
826,117. Printed circuits. PHILIPS ELECTRICAL INDUSTRIES Ltd. June 4, 1958 [June 7, 1957], No. 17865/58. Class 37. A method of manufacturing a printed circuit panel, in which an insulating layer is provided on each side with a metal layer, parts of which, in the form of the required conductive pattern, are covered with a protective layer, the remaining parts being removed by dissolving or etching the metal. The layer consists of a small number of paper sheets impregnated with a partially cured thermo-setting synthetic resin, and after removing the non-covered parts of the metal layer it is divided parallel to its surface into two separate insulating layers, each having a conductive pattern on one side. At least one of these layers is then joined to an insulating substratum in a heated press, during which process the conductive pattern is pressed into the insulating layer and the thermosetting resin fully cured. In the embodiment shown, thin metal foils 3 and 4 of, for example, copper or aluminium, are laid on each side of the stack 2 which consists of four paper sheets impregnated with a thermosetting resin, for example a phenolformaldehyde or a cresol-formaldehyde condensate. Before being laid on the stack the foils are preferably provided with an adhesive layer of, for example, a combination of butadiene-acryl nitryl and phenol-aldehyde condensate, or condensates of malamine and formaldehyde or epoxy resins. The stack and the metal foils are then pressed in a heated press, which part cures the resin and causes the foils to adhere to the stack, etching resists are then provided on the metal foils by silk screen stencil and the plate subsequently immersed in an etching bath, e.g. ferric chloride. For detailed patterns the etching resist is preferably provided by photographic means, the whole surface first being covered by, for example, a layer of polyvinyl butyral sensitized by a bichromate. After etching, the resist may be removed by alcoholic hydrochloric acid, and the plate divided into two separate layers of 41 and 42. One of these layers is then laid on an insulating plate 51, which may also be a thermosetting resin and the resultant stack pressed in a heated press 50. The metal pattern thus sinks into the layer 41 and at the same time the resin is fully cured, and adhesion is obtained between the layer 41 and plate 51. Alternative methods of forming the conductive pattern are possible, for example electro-depositing, and patterns may be provided on both sides of the plate 51. The layers may be mounted on the plate with the conductive patterns on the side adjacent to the plate and since the layer is thin and consequently flexible the final shape after pressing need not be flat. |
