METAL MASK

PURPOSE:To certainly and easily apply a highly viscous substance containing minute particles of solder paste or the like by inclining the side edges of the openings of a metal mask with respect to the moving direction of a squeegee and widening the widths of the openings in the moving direction of the squeegee. CONSTITUTION:Each of openings 10 is formed into a trapezoidal shape whose height direction is set to the longitudinal direction of a lead 1 and the openings 10 are arranged so that the bottom side 11 and top side 12 of the trapezoidal shape become alternate and gaps each having constant width are provided between the adjacent openings 10. Each of the gaps must be set to 0.1mm or more from an aspect preventing the short-circuit due to molten solder. When the openings 10 of a metal mask are formed so as to have a trapezoidal shape and arranged alternately, the width on the bottom 11 side of each opening especially becomes wider than that of a conventional rectangular opening and, when solder paste is applied to a printed wiring board by a squeegee in such a state that the metal mask is in close contact with said board, the solder paste can be easily introduced into the openings 10.