Stmicroelectronics S.r.l.

Sgs-thomson Microelectronics S.r.l.

Stefano Ferri

Roberto Rossi

Renato Poinelli

A method for forming a package of plastic material for a semiconductor electronic device having heat sink fully embedded within the package plastic case, is of the type which provides for forming the plastic case within a mold on whose interior a heat sink has been placed which has a first major surface to be insulated by means of a plastic material layer with a first thickness, whereon a metal leadframe and at least one semiconductor material die having an electronic circuit formed thereon have been fixed, and a second major surface opposite from the first and to be insulated by means of a plastic material layer with a second thickness, thinner than said first thickness; and at least one supporting element adapted to be positioned inside the mold cavity facilitating properly spacing the second surface of the heat sink out from a facing wall of the mold cavity during the process of introducing the plastic material for molding. During package formation, a tapered tip of the at least one supporting element is disposed within a trench defined along the second surface of the heat sink so that the heat sink trench is substantially filled with plastic material when the plastic material is introduced into the mold.

Package for electronic device having a fully insulated dissipator

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.

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Pioltello, Italy

Stefano Ferri