METHOD OF PRODUCING PARTICLES OF LOW MELTING POINT METAL AND APPARATUS THEREFOR

A method for producing particles of a low melting point metal, which comprises providing a mixture of a heat-resistant liquid having a continuous phase and molten metal particles and forcing said mixture to pass through a porous film, to thereby form metal particles having a prescribed particle diameter; and an apparatus for use in the above method which comprises a heating and dispersing mechanism, a cooling mechanism and, provided between them, a porous material in the form of a film, wherein a pressure vessel is connected to the heating and dispersing mechanism and a high pressure is applied to the heating and dispersing mechanism. Conventional low melting point metal particles for use in preparing a solder paste, which is a mixture of a flux and low melting point metal particles, have contained particles having various diameters, which has often resulted in the unsatisfactory packing of a solder paste using the above conventional metal particles into a fine hole of a mask for printing or applying onto a fine zone to be soldered or in the difficulty of separating the mask.