| abstract |
A printed circuit board capable of preventing electro- magenetic interference comprises a base plate composed of an insulating material. On the main surface of the base plate, a first electric conductive layer is formed by etching copper foil, which includes a signal electrode portion and a ground electrode portion. On the first electric conductive layer, an insulating layer such as a solder resist film is formed except for a part of the ground electrode portion, and on this layer, a second electric conductive layer is formed by screen-printing a copper ink so as to cover almost all of the first electric conductive layer. A part of the second electric conductive layer is connected to the ground electrode portion of the first electric conductive layer so that the second electric conductive layer actrs as an electromagnetic shield. The copper ink is a mixture of copper powder, binder and other materials. A solder layer may be formed on the second electric conductive layer composed of the copper ink. |