Method of making a flexible printed circuit board
An exemplary method of making an FPC includes forming a substrate comprising metal foil layers interleaved with intervening layers by: (a) laminating intervening layers with metal foil layers; (b) adhering a covering film to outermost surfaces of the substrate; (c) defining a hole in one side of the substrate through the covering film and at least two metal foil layers and the intervening layer between the at least two metal foil layers by etching or laser technology; and (d) plating a portion of an inner wall of the hole with conductive material to form a via to electrically connect the at least two metal foil layers.
1. A method of making a flexible printed circuit board (FPC) which comprises a substrate comprising a first metal foil layer, a second metal foil layer, a first intervening layer interleaved the first and second metal foil layers, a second intervening layer covered on the second metal foil layer, and a third metal foil layer covered on other side of the second intervening layer, the method comprising:
(a) laminating the substrate;
(b) adhering a covering film to outermost surfaces of the substrate;
(c) defining a hole in one side of the substrate through the covering film and the first and second metal foil layers and the first intervening layer and an additional hole in an opposite side of the substrate through the second and third metal foil layer and the second intervening layer; and
(d) plating a portion of an inner wall of the hole and the additional hole with a conductive material to form a via to electrically connect the at least two metal foil layers.
2. The method as claimed in claim 1 , further comprising removing the covering film from the substrate.
3. The method as claimed in claim 1 , wherein the hole is defined by etching or laser technology.
4. The method as claimed in claim 1 , wherein the covering film is made of insulative plastic.
5. The method as claimed in claim 1 , wherein the first intervening layer comprises two insulating layers and an adhesive layer adhering the insulating layers together.
6. The method as claimed in claim 1 , wherein the second intervening layer comprises an insulating layer and an adhesive layer to adhere the insulating layer to the second metal foil layer.