Patent Application
20080012103
The foregoing and other advantages and features of the invention will become apparent upon reading the following detailed description and upon reference to the drawings in which:
As used herein, the term “electronic device” refers to one or more electronic components, and unless otherwise mentioned, the terms “electronic device” and “electronic component” have been used interchangeably throughout the specification. As used herein, “EM noise” and “RF noise” are used merely to refer to “electromagnetic (EM) radiation” emitted from an electronic device. Moreover, EM noise and RF noise, unless otherwise stated, have been used interchangeably throughout the specification.
The electronic device 106 may comprise one or more components of various electronic instruments for example, LCDs, TFTs, plasma displays, laptops, high speed personal computers, video game consoles, mobile phones or the like. Besides emitting EM radiation, electronic device 106 produces heat when in operation. The heat dissipater 104 is placed above the electronic device 106 to dissipate the excessive heat to the surrounding environment. The heat dissipater 104 may be secured to the electronic device 106 using various securing means, such as mechanical fasteners, for example clips, screws, rivets, clamps nut and bolts, soldering, adhesive and the like. However, the surfaces of the heat dissipater 104 or the electronic device 106 are not perfectly smooth. Consequently, the interface of the heat dissipater 104 and the electronic device 106 may contain substantially smaller gaps (not shown in the figures). These smaller gaps are filled up by air. Since air is considerably thermally non-conductive, these smaller gaps impede the conduction of heat through the interface of the heat dissipater 104 and the electronic device 106.
According to an aspect of the invention, the gap filling material 102 is advantageously placed at the interface between the heat dissipater 104 and the electronic device 106. The gap filling material 102 increases the contact area of the heat dissipater 104 and the electronic device 106 by filling in the smaller gaps. The gap filling material 102 facilitates the thermal conduction across the interface of the heat dissipater 104 and the electronic device 106. The gap filling material 102 also absorbs at least a portion of EM noise generated by electronic device 106. Thus, the gap filling material 102 retards the emission of EM noise from electronic device 106. The gap filling material 102 may exist in various forms and configurations. A non-exhaustive list of such forms and configurations of the gap filling material 102 includes greases, adhesives, compounds, films, elastomeric tapes, sheets, pads and the like.
Further, according to various embodiments, the present invention comprises a means for removing air from the interface (not shown in the figures). The means for removing air may be selected from various types of embossments and through holes. Specifically, any of the gap filling material 102, the heat dissipater 104 and the electronic device 106 may comprise one or more grooves, one or more channels, a series of holes through the material, or a combination thereof. The air gap may be trapped at a first interface of the gap filling material 102 and the electronic device 106, or at a second interface of the gap filling material 102 and the heat dissipater 104, or at both the first and second interfaces. The grooves, channels, and holes help to expel any air trapped in both the first and second interfaces. Air can be expelled from the interfaces through grooves, channels, or holes, when pressure is applied at the first and second interfaces.
Besides providing thermal conductivity, the gap filling material 102 absorbs EM noise generated by the electronic device 106 (as shown in
As will be apparent to one skilled in the art, the magnetic filler 310 may be obtained from various magnetic materials, composites, alloys or a mixture of like materials. A non-exhaustive list of magnetic materials, composites and alloys includes Iron (Fe), Nickel (Ni), Cobalt (Co), Ferrites, Alinco, Awaruite (Ni3Fe), Wairauite (CoFe), MnBi, MnSb, CrO2, MnAs, Gd or the like. The magnetic materials may also have various physical forms and chemical forms. Any of these various physical or chemical forms may be used to prepare the magnetic filler 310. An iron (Fe) based magnetic filler may, for example, include particles of a soft grade Carbonyl iron, a soft grade Carbonyl iron coated SiO2 or FePO4, Sendust FeAlSi, or Permalloy Fe—Ni and the like. In certain embodiments of the present invention, the magnetic filler 310 may comprise a mixture of magnetic particles from various magnetic materials.
Generally, the magnetic filler 310 imparts thermal conductivity to gap filling material 102. However, to further increase the thermal conductivity of the gap filling material 102, fillers of materials with high thermal conductivity may be dispersed in the binder material 308. These fillers may be obtained from a magnetic material, a non-magnetic material or a mixture thereof. A non-exhaustive list of non-magnetic thermal conductive materials includes aluminum, copper, silicon carbide, titanium diboride and the like.
According to certain embodiments of the present invention, the binder material 308 may be constructed from various materials depending on the form of the gap filling material 102. A non-exhaustive list of various forms of the gap filling material 102 includes greases, adhesives, compounds, films, elastomeric tapes, sheets, pads or the like. As will be apparent to one skilled in the art, the binder material 308 may include, for example, silicone elastomers, thermoplastic rubbers, urethanes, acrylics and the like. Silicone elastomers are constructed from silicone gums crosslinked using a catalyst. Thermoplastic rubbers are typically thermoplastic blockpolymers for example, a styrene-ethylene-butylene-styrene block copolymer having a styrene/rubber ratio of 13/87.
Alternatively, thermoplastics, such as crosslinked block copolymers of styrene/olefin polymers with suitable functional groups, for example, carboxyl groups, ethoxysilanol groups, and the like. In order to form a crosslink, a crosslinking agent and a crosslinking catalyst are combined with the crosslinkable copolymer. In certain embodiments of the present invention, where the gap filling material 102 is in the form of a film, the binder material 308 can include polyolefins, such as polyethylene, polyimides, polyamides, polyesters and the like. These films have poor thermal conductivities, and the addition of thermal conductive filler, such as titanium diboroide, boron nitride, aluminum oxide, or the like, or a mixture thereof, improves the thermal properties of the film.
In certain embodiments of the present invention, where the gap filling material 102 is in the form of a tape or an adhesive, the binder material 308 can be a pressure sensitive adhesive material, such as a silicone, urethane or an acrylic adhesive resin.
Further, in certain embodiments of the present invention, where the gap filling material 102 is in the form of a grease, the binder material 308 can be uncrosslinked silicone. In the elastomeric or tape configuration, one or more layers of conductive support materials may be incorporated into the binder material 308 to increase the toughness, resistance to elongation, and resistance to tearing of the gap filling material 102. A non-exhaustive list of supporting materials includes synthetic and non-synthetic fibers such as, glass fiber, glass mesh, glass cloth, plastic fiber, plastic mesh, plastic cloth, plastic films, metal fiber, metal mesh, metal cloth, metal foils and the like. Some of the supporting materials are thermally conductive and others are thermally non-conductive. As will be apparent to one skilled in the art, one or more types of thermal conductive fillers may be added to a thermally non-conductive supporting material to make it thermally conductive.
Each of the gap filling materials shown in
According to various embodiments, the present invention may be used as a method to provide a gap filling material as discussed previously. The method includes providing a binder material and dispersing at least one magnetic filler into the binder material. The method may be used for conducting heat across an interface of a first surface and a second surface. The method may also be used for absorbing EM radiation emitted from the first surface and/or the second surface. The method includes providing a binder material and dispersing at least one magnetic filler into the binder material thereby forming a gap filling material. The method further includes placing the gap filling material in the interface. The gap filling material provides conduction of the excessive heat generated by an electronic device. At the same time, the gap filling material retards emission of EM noise emitted from the electronic device.
Among other advantages that will be apparent to those skilled in the art, the gap filling material provides a thermal conduction at the interface between the heat dissipater and the electronic device, and at the same time, absorbs EM noise emitted by the electronic device. Further, the gap filling material is available for use in many convenient forms, such as greases, adhesives, compounds, films, elastomeric tapes, sheets, pads and the like depending upon the particular application and requirements. Furthermore, the gap filling material is also usable for the shielding of electronic devices. Yet furthermore, the gap filling material is easy to manufacture and cost effective.
While the invention may be susceptible to various modifications and alternative forms, specific embodiments have been shown by way of example in the drawings and have been described in detail herein. However, it should be understood that the invention is not intended to be limited to the particular forms disclosed. Rather, the invention is intended to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the invention as defined by the following appended claims.
This application claims the benefit of priority of U.S. Provisional Application No. 60/807,216, filed on Jul. 13, 2006, the disclosure of which is incorporated herein by reference thereto in its entirety.
| Number | Date | Country | |
|---|---|---|---|
| 60807216 | Jul 2006 | US |
