Method and mold for manufacturing a plastic package for an electronic

Abstract

A method for forming a plastic package for a power semiconductor electronic device to be encapsulated within a plastic case and to be coupled thermally to a heat sink element having a major surface exposed and at least one peripheral portion extending outwards from at least one side of the plastic case. The method forms the plastic case of the package by molding inside a main cavity of a mold after positioning a heat sink element in a suitable housing provided in a lower portion of the mold which opens into the main cavity of the mold. The method forms the heat sink element such that at least side surfaces jutting out of said side of the plastic case are, at least in a zone adjacent to that side and in the peripheral portion, inclined to form an angle .alpha. substantially greater than zero with a normal line to the major surface, so as to have a negative slope from outside. The housing is formed such that its inner walls face the side surfaces of the heat sink element are inclined, at least in that zone, to form an angle substantially equal to the angle .alpha. with the normal line, with a positive slope from the housing interior. Thrust means engage from above with at least part of the peripheral portion of the heat sink element to exert thereon a compressive force substantially toward the housing bottom, thereby hermetically sealing the side surfaces of the heat sink element and the inner walls of the housing in the zone adjacent to said side of the plastic case during molding.