Semiconductor device manufacturing: process – Packaging or treatment of packaged semiconductor – Encapsulating
Reexamination Certificate
1999-04-05
2001-02-27
Bowers, Charles (Department: 2813)
Semiconductor device manufacturing: process
Packaging or treatment of packaged semiconductor
Encapsulating
C438S617000, C257S687000, C257S784000, C257S787000
Reexamination Certificate
active
06194251
ABSTRACT:
This invention relates generally to packaging integrated circuits and particularly to overmolded integrated circuit packaging.
BACKGROUND OF THE INVENTION
Integrated circuit dice, commonly called integrated circuit chips, are typically mounted inside packages having contacts extending therefrom for communication with the outside world. These contacts may be used to output signals from the chip, to input signals to the chip, or for supplying power or ground connections.
In conventional overmolded technology, a package is formed around the integrated circuit chip which may be mounted on a metal lead frame. The chip may be mechanically connected to the lead frame paddle or to the leads in the case of a lead-on-chip (“LOC”) configuration. The chip assembly may also be electrically interconnected by fine wires from chip bond pads to a variety of lead frame fingers which connect to the exterior contacts on the package. The chip assembly is then positioned in a mold and the final package configuration is defined by plastic molding around the chip assembly. Since the lead frame assembly is relatively flexible, the position of the die with respect to the overmolded portion of the package is not necessarily fixed.
Conventionally, the overmolding or encapsulant, which may be a plastic or epoxy, protects and insulates not only the intervening die or chip but the lead frame and the wire bonding wires as well. With a chip assembly in a mold, the encapsulant is injected into the mold and air is exhausted from the opposite end of the mold.
The way the encapsulant enters the mold may cause the die to be displaced, either up or down depending on the lead frame, mold, and package design and on the encapsulation material and process. This may result in package bowing, stress location changes, increased delamination or cracking due to internal stress.
Thus, there is a need for techniques which help to maintain the die centered in overmolded packaging.
SUMMARY OF THE INVENTION
In accordance with one aspect of the present invention, a packaged integrated circuit device includes a die and a plurality of leads. First bond wires are connected between the leads and the die for electrical communication. A second wire bond wire extends vertically over the die above the height of the first wire bond wires. The second wire bond wire is electrically nonfunctional.
In accordance with another aspect of the present invention, an integrated circuit package includes a die assembly including a die and a plurality of leads. A spacer extends upwardly from the die assembly to space the die from the overmolding mold.
In accordance with yet another aspect of the present invention, a packaged integrated circuit device includes a die and a plurality of leads. The integrated circuit device has wire bond wires connected between the leads and the die for electrical communication. A spacer, connected to the die, extends upwardly above the die and is arranged to contact a mold utilized for overmolding of the die.
In accordance with yet another aspect of the present invention, a method of forming integrated circuit packages includes the step of wire bonding a die to a plurality of leads. A spacer wire is formed by wire bonding. The spacer wire extends upwardly over the wire bonding between the die and the leads.
In accordance with yet another aspect of the present invention, a method of forming an integrated circuit device includes the step of electrically connecting a die to a plurality of electrical contacts using wire bonding to form a die assembly. The integrated circuit device forms a spacer secured to the die assembly and extending upwardly. A mold contacts the spacer during the course of overmolding the die.
In accordance with still another aspect of the present invention, a method of forming an integrated circuit device includes the step of electrically connecting the die to a plurality of contacts to form a die assembly. The die assembly is placed in a mold. The die assembly is spaced from the mold using a spacer that extends over the die assembly and connects to the die assembly. The die assembly is then overmolded.
In accordance with yet another aspect of the present invention, a method of centering a die during encapsulation includes the step of forming a die assembly. The die assembly is secured to an element and the element is arranged to extend upwardly so as to center the die during encapsulation.
In these ways, the die may be maintained in the desired centered orientation, and the adverse effects of die displacement may be lessened.
REFERENCES:
patent: 5814892 (1998-09-01), Steidl
Berezny Nema
Bowers Charles
Micro)n Technology, Inc.
Trop, Purner & Hu, P.C.
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