Nonexposed heat sink for semiconductor package

A leadframe comprising:

• a metal frame including a central region within the frame;
• a plurality of metal leads extending from a first end integral with the frame to a second end adjacent to the central region, wherein at least a plurality of the leads gradually increase in width as those leads extend from the frame toward the central region;
• and
• a flat metal plate supported in the central region, wherein a first portion of each said lead overhangs a periphery of said plate.

A semiconductor package comprising:

• a semiconductor chip;
• a package body formed of a hardened encapsulant material;
• a plurality of metal leads, wherein each lead is electrically connected to the chip;
• a flat metal plate fully encapsulated within said package body, wherein the chip is mounted on the plate, and an encapsulated first portion of each of the leads overhangs the periphery of the plate, and the plate has a thickness that is at least two times a thickness of the leads;
• and
• a plurality of encapsulated members, wherein each said member extends from a perimeter of the package body toward the plate, and overhangs a periphery of the plate, and is in a metal to metal connection with a surface of the plate.

A semiconductor package comprising:

• a semiconductor chip;
• a package body formed of a hardened encapsulant material;
• a plurality of metal leads each electrically connected to the chip, wherein at least a plurality of the leads increase in width as those leads extend from a perimeter of the package body, and wherein two leads of increasing width are adjacent and extend from opposite sides of a first corner of the perimeter of the package body, said two leads defining a first slot between them, said first slot extending from the first ends of the two leads to their respective second ends;
• a flat metal plate fully encapsulated within said package body, wherein the chip is mounted on the plate, and an encapsulated first portion of each of the leads overhangs a periphery of the plate, and the plate has a thickness that is at least two times a thickness of the leads;
• a metal first member located at a first corner of the package body and extending into the first slot for only a portion of a length of the first slot, the first member being encapsulated by the package body and including intersecting straight edges that taper to a point aligned with a central axis of the first slot;
• and
• three metal pseudo tie bars each extending diagonally from a first end located at a second corner, a third corner, and a fourth corner, respectively, of the perimeter of package body to a second end overhanging the periphery of the plate and each being in a connection with the plate.

A leadframe comprising:

• a metal frame including four corners and a central region within the frame;
• three metal pseudo tie bars each extending diagonally from a first end integral with a second corner, a third corner, and a fourth corner, respectively, of the frame to a second end adjacent to the central region;
• a plurality of metal leads each extending from a first end integral with the frame to a second end adjacent to the central region, wherein at least a plurality of the leads increase in width as those leads extend from the frame toward the central region, and wherein two leads of increasing width are adjacent and extend from opposite sides of a first corner of the frame, said two leads defining an open first slot between them, said first slot extending from the first ends of the two leads to their respective second ends;
• and
• a flat metal plate supported in the central region, wherein the plate has a thickness that is at least two times a thickness of said leads, and wherein a first portion of each said lead overhangs a periphery of the plate, and wherein a first portion of each said pseudo tie bars overhangs the periphery of the plate and is in a connection with the plate.