A multilayer flexible circuit board cover opening method

The invention relates to a multilayer flexible circuit board cover opening method comprising the steps of: (1) etching a copper layer of a single-sided board to form a first opening; (2) connecting the single-sided board with assembly glue and etching a PI layer of the single-sided board and the assembly glue to form a second opening, wherein the aperture of the second opening is smaller than the aperture of the first opening; (3) connecting the single-sided board and the assembly glue which have been connected to a double-sided board to enable the first opening and the second opening to form an open cover zone; (4) plating a copper layer on the bottom and side walls of the open cover zone; (5) using a dry film to cover the opening portion connected to the first opening of the second opening to enable the opening wall of the second opening and the bottom portion of the open cover zone to form a dry film covered zone; (6) selectively plating the area not covered by the dry film; (7) removing the dry film; and