Method of sealing electric parts mounted on electric wiring board with resin composition

A method of sealing electric parts mounted in a bare state on an electric wiring board using a screen having apertures formed by peripheral walls in the same pattern as the electric parts to be sealed wherein lower ends of the peripheral walls are formed with line contact portions surrounded with recesses so as to only come into line-to-line contact with a surface of the electric wiring board, the method comprising the steps of:

• positioning the screen in line-to-line contact with the surface of the electric wiring board;
• while maintaining said screen in line-to-line contact with said wiring board forcing a sealing resin in a liquid state into the apertures so as to seal the electric parts by using a squeegee moving from a squeegee stroke starting side to a stroke end side of each aperture to fill the apertures with the resin;
• while still maintaining said screen in line-to-line contact with said wiring board moving a doctor knife from the squeegee stroke end side over each screen aperture to an intermediate portion of each aperture, subsequent to the operations of the squeegee, for filling each said aperture with the liquid sealing resin, substantially uniformly from the stroke starting side of the aperture to the stroke end side thereof;
• retracting the screen from the board while the resin is in a liquid state to complete transfer of the resin from the screen to the board and prevent the resin from migrating to the rear side of said screen;
• and
• curing the resin transferred to the board.