Coating apparatus – Projection or spray type – Plural projectors
Reexamination Certificate
2000-07-11
2002-05-07
Edwards, Laura (Department: 1734)
Coating apparatus
Projection or spray type
Plural projectors
C118S411000, C118S412000
Reexamination Certificate
active
06383292
ABSTRACT:
TECHNICAL FIELD
The invention pertains to methods of encapsulating semiconductor devices, such as, for example, methods of forming electronic packages, as well as to encapsulator devices.
BACKGROUND OF THE INVENTION
Semiconductor chips are frequently connected to a circuit board and subsequently encapsulated within a sealant compound to form a sealed package during semiconductor device manufacture. Among the methods that can be utilized for connecting chips to circuit boards are, for example, wire bonding, flip chip, chip on board, and tape automated bonding. All four methods can be followed by the application and curing of one or more liquid encapsulants over the chips and nearby circuitry. The cured encapsulants can protect the chips and their associated electronic interconnections to the boards from physical damage and ionic contamination.
The liquid encapsulants are typically applied by dispensing the encapsulants to form a glob over one or more chips and their associated electrical interconnections. Hence, the technology of providing such encapsulants is frequently referred to by the term “glob-top” encapsulation. The encapsulants can be provided as single globs over single chips (so-called “single chip modules”), or as single globs encompassing multi-chip units (so-called “multi-chip modules”).
Glob-top encapsulation was originally introduced for consumer packages such as, for example, video games, but the demand for miniaturized circuitry led to the use of glob-top as a preferred assembly method for many types of products including, for example, smart credit cards, and microprocessor circuitry. Glob-top encapsulation technology can enable manufacturers to make relatively thin devices, and also enables many companies to produce packages with cost equal to or less than conventional plastic packages. Typical glob-top compositions include epoxy or silicone encapsulating resins which provide protection against corrosion, vibration and mechanical stresses.
An exemplary automated process for applying a glob-top encapsulant to a chip is as follows. First, an integrated circuit chip is provided on a circuit board. The chip has exposed electrical leads (or pads) provided in electrical contact with corresponding leads (or pads) on the circuit board. The electrical connection can comprise, for example, a wire bond comprising exposed gold wires connecting the leads of the chip with those of the circuit board. Next, encapsulant is pumped through a single syringe to form a glob over the chip and over the electrical connections of the chip to the circuit board. Typically, the single syringe is moved relative to the chip as the encapsulant is provided. In one method, the syringe is first moved to dispense encapsulant around a periphery of the chip and form a dam of encapsulant material. The syringe is then moved over a center of the chip to provide encapsulant onto the chip. The encapsulant provided onto the chip is prevented from flowing beyond the periphery of the chip by the dam that was initially provided. The encapsulant utilized for the dam can be different than that provided over a center of the chip. Specifically, the encapsulant utilized for forming the dam can be a so-called “dam” encapsulant and that provided over the center of the chip can be a so-called “fill” encapsulant. Dam encapsulants are generally more viscous than fill encapsulants. After the encapsulant is provided, it is cured by, for example, thermal processing to solidify the encapsulant material.
A continuing goal in semiconductor processing is to increase speed of semiconductor device fabrication. Accordingly, it would be desirable to increase the speed with which chips are encapsulated.
SUMMARY OF THE INVENTION
In one aspect, the invention encompasses a method of encapsulating a semiconductor device. A semiconductor device is provided. A dispensing apparatus is provided proximate the semiconductor device. The dispensing apparatus has a plurality of orifices. A liquid encapsulating material is dispensed through the plurality of orifices and over the semiconductor device.
In another aspect, the invention encompasses a method of forming an electronic package. A circuit board comprising a circuit pattern is electrically connected with a semiconductor device. A dispensing apparatus is provided proximate the semiconductor device. The dispensing apparatus has a plurality of dispensing orifices. A liquid encapsulating material is dispensed through the plurality of orifices and onto the semiconductor device. The encapsulating material is then cured.
In yet another aspect, the invention encompasses a semiconductor device encapsulator comprising a vessel configured for containing liquid encapsulant material, and a liquid dispensing apparatus in fluid communication with the vessel. The apparatus has a plurality of dispensing orifices. At least one of the dispensing orifices is configured for receipt over and within lateral confines of a semiconductor device being encapsulated.
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Brand Joseph M.
Gooch Scott
Edwards Laura
Micro)n Technology, Inc.
Wells St. John P.S.
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