METAL MASK FOR SOLDER PASTE PRINTING

PURPOSE:To prevent the occurrence of drooping and a solder bridge after a solder paste is printed, by specifying diameters of ports on the injection side and the other side of a through hole so formed in a metal mask as to correspond to a wiring pattern position, and a diameter between the two ports. CONSTITUTION:In a part of a metal mask 1, openings 3 and 4 are formed at positions corresponding to wiring patterns 2 formed on a printed circuit board P. The diameters of ports 5 and 6 of the openings 3 and 4 on the squeeze side, i.e. on the side whereon a solder paste is injected, are formed to be (a) and (b) respectively, while the diameters of ports 7 and 8 thereof on the printed circuit board side are formed to be (c) and (d) respectively, and a construction is made so that the diameters (c) and (d) are about 1.5 times larger than the diameters (a) and (b) respectively. When the metal mask 1 thus constructed is superposed on the printed circuit board P and the solder paste is printed, solder pastes 9 are printed in the shape of a trapezoid. In the printed solder pastes 9, the occurrence of drooping and a solder bridge is reduced. On the occasion when the metal mask 1 is removed from the printed circuit board P after the solder paste is printed, in addition, the metal mask 1 can be detached excellently from the board.