Electricity: electrical systems and devices – Housing or mounting assemblies with diverse electrical... – For electronic systems and devices
Reexamination Certificate
2002-07-26
2004-08-31
Thompson, Gregory D (Department: 2835)
Electricity: electrical systems and devices
Housing or mounting assemblies with diverse electrical...
For electronic systems and devices
C361S710000, C361S718000, C165S080200, C165S185000, C257S707000, C257S713000, C257S719000
Reexamination Certificate
active
06785137
ABSTRACT:
TECHNICAL FIELD OF THE INVENTION
The present invention is directed in general to integrated circuits and, more specifically, to a method and system for removing heat from an active area of an integrated circuit device.
BACKGROUND OF THE INVENTION
A conventional integrated circuit package generally comprises an integrated circuit made of silicon, a laminate or leadframe substrate which provides support for and electrical interconnection to the integrated circuit (IC), and a protective material to protect the electrical connections between the integrated circuit and the substrate. During the manufacture of an integrated circuit package, the integrated circuit portion is generally referred to as a die.
The typical die is constructed such that the active electrical circuitry is located on one side of the die and occupies only the top few microns of its thickness. Thus, essentially all heat associated with operation of the IC is generated locally at the die surface. For normal semiconductor devices, the dice are made from Silicon (Si) or Germanium (Ge). Both of these materials are relatively poor thermal conductors with Germanium being the worst of the two.
To extract the heat generated at the surface of the die there are two possible conduction paths: (1) through the bulk material of the die (either Si or Ge) and thence connecting to other thermally conducting elements or (2) from the die through the encapsulating or “protecting” material surrounding the die (as described above).
Typically, the conduction path (1) is inefficient since the heat must traverse the bulk of the die (Si or Ge) and thence to other conducting elements. For this thermal conduction path, the thermal resistance encountered in traversing the bulk of the die is added to the thermal resistance of other elements in the conductive path, making it a less efficient path.
In conventional IC packages, the conduction path (2) is inefficient since the relatively thick protective material encasing the surface of the die is a thermosetting organic material, such as epoxy novolac resin, which has very poor thermal conductive properties. Thus, even though this path avoids traversing the bulk material of the die, it is rendered inefficient because of a relatively long thermal conduction path through a poorly conducting medium.
Because of the importance of removing heat from packaged semiconductor devices, many methods have been developed in attempts to improve this process. These methods typically include a thermally conductive element coupled to the outside of the package, i.e., not in direct or close contact with the active surface of the integrated circuit die. The thermally conductive element is used to conduct heat away from the semiconductor device.
As the heat is conducted away from the semiconductor device, the heat traverses a conductive path, which suffers resistance to the heat flow. This resistance to thermal conduction is a function of both the thermal conductivity of each element along the path and the distance the heat must travel through each of these elements. Thus, to remove heat, current solutions have included using materials with superior thermal conductivity in the extraction path and/or modifying designs to package geometry to minimize the length of the path.
However, as device scales become smaller and operating speeds become higher in integrated circuits, more power is generated and needs to be removed from the semiconductor devices to ensure a reasonable useful life span for the semiconductor devices. This is especially the case for the microprocessor family of digital integrated circuits. In these applications, currently available methods for removing heat may be insufficient.
SUMMARY OF THE INVENTION
In accordance with the present invention, a method and system for removing heat from an active area of an integrated circuit device are provided that substantially eliminate or reduce disadvantages and problems associated with conventional systems and methods. In particular, a thermally conductive element is coupled to the active area of the integrated circuit device, resulting in a minimized thermal conduction path and corresponding increase in efficiency of heat removal.
According to one embodiment of the present invention, a method for removing heat from an active area of an integrated circuit device is provided. The method includes applying a separator to the active area of the integrated circuit device. A thermally conductive element is coupled to the active area of the integrated circuit device outwardly of the separator.
According to another embodiment of the present invention, a system for removing heat from an active area of an integrated circuit device is provided that includes a separator and a thermally conductive element. The separator is coupled to the active area of the integrated circuit device. The thermally conductive element is coupled to the active area of the integrated circuit device outwardly of the separator.
Technical advantages of one or more embodiments of the present invention include providing an improved method for removing heat from an integrated circuit device. In a particular embodiment, a thermally conductive element is coupled to the active area of the integrated circuit device. As a result, the thermal conduction path from the active area of the integrated circuit device to the thermally conductive element is minimized. Accordingly, the efficiency of heat removal from the active area is increased.
Other technical advantages will be readily apparent to one skilled in the art from the following figures, description, and claims.
Before undertaking the DETAILED DESCRIPTION OF THE INVENTION, it may be advantageous to set forth definitions of certain words and phrases used throughout this patent document: the terms “include” and “comprise,” as well as derivatives thereof, mean inclusion without limitation; the term “or,” is inclusive, meaning and/or; the phrases “associated with” and “associated therewith,” as well as derivatives thereof, may mean to include, be included within, interconnect with, contain, be contained within, connect to or with, couple to or with, be communicable with, cooperate with, interleave, juxtapose, be proximate to, be bound to or with, have, have a property of, or the like; and the term “controller” means any device, system or part thereof that controls at least one operation, such a device may be implemented in hardware, firmware or software, or some combination of at least two of the same. It should be noted that the functionality associated with any particular controller may be centralized or distributed, whether locally or remotely. Definitions for certain words and phrases are provided throughout this patent document, those of ordinary skill in the art should understand that in many, if not most instances, such definitions apply to prior, as well as future uses of such defined words and phrases.
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Jorgenson Lisa K.
Munck William A.
STMicroelectronics Inc.
Thompson Gregory D
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