Molding method with the use of modified runners

Details Molding method with the use of modified runners Molding method with the use of modified runners

1998-11-10

2001-04-10

Ortiz, Angela (Department: 1732)

Plastic and nonmetallic article shaping or treating: processes

Mechanical shaping or molding to form or reform shaped article

To produce composite, plural part or multilayered article

C264S272170, C264S328400, C425S116000, C425S544000

Reexamination Certificate

active

06214273

ABSTRACT:

TECHNICAL FIELD OF THE INVENTION
This invention relates generally to the molding of plastics and more particularly to a boomerang runner system in a molding system.
BACKGROUND OF THE INVENTION
Plastics, or polymers, are used in a variety of products and applications ranging from the simple pen to the complicated wing of an aircraft. Different types of plastic, or polymers, as they are technically known, generally have different mechanical, chemical, and electrical properties that allow plastics to be used in many applications. Plastics are typically formed into a product through a molding process, such as extrusion, injection molding, sheet molding, or blow molding. For example, plastics are used extensively in the computer and semiconductor industry in a wide variety of applications. One such application is the encapsulation of semiconductor devices, particularly integrated circuits. Encapsulating a semiconductor device in plastic materials protects the device from environmental damage and also provides structural strength to the semiconductor device.
Conventional molding systems and processes suffer from numerous disadvantages. A disadvantage of some conventional systems that use a thin film, such as those used in “3P technology” molding processes, is that the film for prepackaging pencils of a molding material often restricts the flow of the molding material into a mold cavity. The restriction may cause turbulence that entraps air and may also cause the associated mold cavity to be under-filled with the molding material. The under-filled condition or the air contained in the molding material may form internal voids in the final molded product. Internal voids are bubbles and clusters of bubbles or voids in the molded product that affect the intended use of the molded product.
Internal voids often degrade the mechanical, electrical, and chemical properties, as well as the appearance, of the molded product. In the case of encapsulated semiconductor devices, internal voids reduce the reliability of the package because they allow moisture to accumulate within the voids. This moisture may cause corrosion of the semiconductor device and may promote cracking when the encapsulated semiconductor device is subjected to additional processing, such as vapor phase reflow or a similar process.
SUMMARY OF THE INVENTION
Accordingly, a need has arisen for an improved molding system and method. The present invention provides a molding system and method that addresses shortcomings of prior molding systems and methods.
According to one aspect of the invention, a method for encapsulating a semiconductor device includes forming a mold with a mold cavity. The mold cavity may be connected to a pot by a boomerang runner system. The pot may contain a non-solidified molding material for use in the molding process. The boomerang runner system may include a boomerang passage that includes an inner curvilinear surface and an outer curvilinear surface. A semiconductor is placed within the mold cavity and the non-solidified molding material in the pot is transferred from the pot through the boomerang runner system into the mold cavity. The non-solidified molding material in the mold cavity encapsulates the semiconductor device. The non-solidified molding material then hardens or solidifies around the semiconductor device.
According to another aspect of the invention, a molding system may include a mold cavity contained within a mold. A pot may be connected to the mold cavity by a boomerang runner system. The boomerang runner system may include an inner curvilinear surface and an outer curvilinear surface.
The invention provides several technical advantages. For example, the invention improves the quality of the finished molded product by reducing or eliminating internal voids by, at least in part, reducing the amount of air entrained in the molding material. The invention also increases the cross sectional flow area of a molding material flowing from a pot to a mold cavity. The increased cross sectional floor area is especially important when 3P technology release films are used in the molding process. In addition, the invention allows the density of the molded product or package density, to be increased. The increase in package density allows the encapsulation of a next generation of semiconductor devices that have an ever increasing number of leads and requires a finer resolution of detail in the encapsulation material.
Other technical advantages will be readily apparent to one skilled in the art from the following figures, descriptions, and claims.


REFERENCES:
patent: 5052907 (1991-10-01), Matumoto et al.
patent: 5071334 (1991-12-01), Obara
patent: 5182071 (1993-01-01), Knapp et al.
patent: 5384286 (1995-01-01), Hirai
patent: 5435953 (1995-07-01), Osada et al.
patent: 5596797 (1997-01-01), Bumsted
patent: 5645864 (1997-07-01), Higuchi
patent: 5891377 (1999-04-01), Libres et al.

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