Active solid-state devices (e.g. – transistors – solid-state diode – Lead frame – With heat sink means
Reexamination Certificate
1998-11-02
2001-09-04
Potter, Roy (Department: 2822)
Active solid-state devices (e.g., transistors, solid-state diode
Lead frame
With heat sink means
C257S691000, C257S706000, C257S796000
Reexamination Certificate
active
06285075
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to integrated circuit packages. In particular, the present invention relates to integrated circuit packages with high electrical and thermal performances.
2. Discussion of the Related Art
In a plastic package, such as that described in the Copending Application, a heat sink or heat spreader coated with a layer of aluminum oxide for electrical isolation can be provided for heat dissipation. However, while such a package provides good thermal performance, imperfection in the aluminum oxide layer leads to high yield loss.
Further, in integrated circuit packages, the semiconductor die is typically attached to a die-attach pad, which may be formed integrally with the lead frame. The semiconductor die can be attached using an adhesive based on a B-stage polyimide resin. However, polyimide resins have weak bonding strength to metals and absorbs moisture. In addition, such an adhesive requires a curing step at an elevated temperature over an extended period of time.
SUMMARY OF THE INVENTION
According to one aspect of the present invention, an integrated circuit package is provided which includes: (a) a heat spreader; (b) a semiconductor die attached to the heat spreader by an adhesive; (c) leads each including an internal portion for bonding and an external portion to serve as an external terminal for the integrated circuit package; (d) bond wires each bonding one of the internal portions of the leads to a bonding pad of the semiconductor die; and (e) a resin encapsulation enclosing the heat spreader, the semiconductor die, the internal portions of the leads and the bond wires.
In one embodiment, a ceramic ring with conductive traces for bonding provided thereon is attached to the heat spreader using an adhesive. In that embodiment, a first bond wire electrically couples one of the conductive traces of the ceramic ring to the internal portion of one of the leads; and a second bond wire electrically coupling that conductive trace of the ceramic ring to one of the bonding pads. The adhesive attaching the ceramic ring to the heat spreader can include an acrylic adhesive. Such an acrylic adhesive can be impregnated with a thermally conductive material. In one embodiment, the acrylic adhesive is provided between the ceramic ring and the heat spreader in two layers, one of the layers being impregnated with a thermally conductive material. Each conductive trace can serve as either a ground or a power terminal. In one embodiment the conductive traces comprise gold. The ceramic can be provided with perforations into which the resin encapsulation material can flow during molding. The cured encapsulation material can then provide locking structures for properly securing the ceramic ring.
In accordance with another aspect of the present invention, a downset interposer ring can be attached to the heat spreader. The downset interposer ring can provide a segment positioned between the internal portion of one of the leads and the semiconductor die. Each segment can function as a power supply or ground signal terminal.
In accordance with another aspect of the present invention, an integrated circuit package includes (a) a die-attached pad; (b) a semiconductor die attached to the die-attach pad by an adhesive; (b) leads each including an internal portion for bonding and an external portion to serve as an external terminal for said integrated circuit package; (c) a downset interposer ring attached to the die-attach pad, the downset interposer ring having a segment positioned between the internal portion of one of the leads and the semiconductor die; (d) bond wires each electrically coupling one of the internal portions of the leads to one of the bonding pads of the semiconductor die, and a bond wire electrically coupling the segment of the downset interposer ring to a bonding pad of the semiconductor die; and (e) a resin encapsulation enclosing the die-attach pad, the semiconductor die, the internal portions of the leads and the bond wires. In one embodiment, a heat spreader is attached by adhesive to the die-attach pad.
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patent: 4862245 (1989-08-01), Pashby et al.
patent: 4975761 (1990-12-01), Chu
patent: 5172213 (1992-12-01), Zimmerman
patent: 5367196 (1994-11-01), Mahulikar et al.
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patent: 5757070 (1998-05-01), Fritz
patent: 5895966 (1999-04-01), Penchuk
patent: 4-137756 (1992-05-01), None
Combs Edward G.
Sheppard Robert
ASAT Limited
Gallagher Thomas A.
Gallagher & Lathrop
Potter Roy
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