| 摘要 |
A printed circuit board with metallized through holes is formed by punching or drilling the base board, depositing copper electrolessly on both sides of the board and in the holes to a thickness of about 0.5 mu , increasing the copper thickness by electroplating until a thickness of the order of 25 to 35 mu is obtained, applying a photoresist foil to each side of the board under the action of pressure and temperature, negatively exposing the photoresist foil with the required conductor patterns and processing the resist so that the foil protects the desired conductor pads and paths and areas of the copper layers which are not required are exposed for etching, and etching to remove the copper not protected by the resist foil. |
