Abstract: A test apparatus and method that is used for a stress test of a semiconductor device.

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.