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  Flexible interconnect structures for electrical devices and light sources incorporating the sameUSPTO Application #: 20060292722Title: Flexible interconnect structures for electrical devices and light sources incorporating the same Abstract: A flexible interconnect structure allows for rapid dissipation of heat generated from an electrical device that includes light-emitting elements, such as light-emitting diodes (“LEDs”) and/or laser diodes. The flexible interconnect structure comprises: (1) at least one flexible dielectric film on which circuit traces and, optionally, electrical circuit components are formed and at least a portion of which is removed through its thickness; and (2) at least a heat sink attached to one surface of the flexible dielectric film opposite to the surface on which circuit traces are formed. The flexible interconnect structure can include a plurality of such flexible dielectric films, each supporting circuit traces and/or circuit components, and each being attached to another by an electrically insulating layer. Electrical devices or light sources having complex shapes are formed from such flexible interconnect structures and light-emitting elements attached to the heat sinks so to be in thermal contact therewith. (end of abstract) Agent: Fay, Sharpe, Fagan, Minnich & Mckee, LLP - Cleveland, OH, US Inventors: Charles Adrian Becker, Stanton Earl Weaver, Thomas Elliot Stecher USPTO Applicaton #: 20060292722 - Class: 438028000 (USPTO) Related Patent Categories: Semiconductor Device Manufacturing: Process, Making Device Or Circuit Emissive Of Nonelectrical Signal, Packaging (e.g., With Mounting, Encapsulating, Etc.) Or Treatment Of Packaged Semiconductor, Plural Emissive Devices The Patent Description & Claims data below is from USPTO Patent Application 20060292722. Brief Patent Description - Full Patent Description - Patent Application Claims
[0001] This application claims the benefit of U.S. patent application Ser. No. 10/063,104, filed Mar. 21, 2002, entitled "FLEXIBLE INTERCONNECT STRUCTURES FOR ELECTRICAL DEVICES AND LIGHT SOURCES INCORPORATING THE SAME", the disclosure of which is incorporated herein in its entirety, by reference. BACKGROUND OF INVENTION [0002] The present invention relates to flexible interconnect structures that support circuits for controlling or operating electrical devices and light sources incorporating the same. In particular, the present invention relates to such flexible interconnect structures and devices that incorporate light-emitting elements and have improved thermal management capability. [0003] Light-emitting diodes ("LEDs") are now widely applied in a variety of signs, message boards, and light sources. The relatively high efficacy of LEDs (in lumens per watt) is the primary reason for their popularity. Large power savings are possible when LED signals are used to replace traditional incandescent signals of similar luminous output. One aspect of LED technology that has not been satisfactorily resolved is the efficient management and removal of waste heat, especially for high optical power LEDs, requiring increased electrical power. The waste heat results in excessive junction temperatures, degrading performance and reducing device life. LED lamps exhibit substantial light output sensitivity to temperature, and can be permanently degraded by excessive temperature. For example, the maximum recommended operating temperature for LEDs that incorporate indium in their compositions is between about 85.degree. C. and about 100.degree. C. These devices can exhibit typical (half brightness) lives on the order of 50,000 to 100,000 hours at 25.degree. C. However, degradation above 90.degree. C. is rapid as the LEDs degrade exponentially with increases in temperature. [0004] Permanent thermal degradation of LEDs may also occur during array fabrication if care is not taken, when the LEDs are soldered to the supporting and/or interconnecting circuit board. For example, typical soldering temperatures can exceed 250.degree. C. and seriously affect the performance of the LEDs even before they are put into service, if the LEDs remain at or near such high temperatures for an extended period of time. Therefore, it is very advantageous to remove heat rapidly from the vicinity of LEDs whether such heat is generated by the LEDs during normal use or applied during the assembly or manufacturing process. [0005] One common method for dissipating heat generated from LEDs that are mounted on an insulating printed circuit board ("PCB"), such as the commonly available FR-4 fiber composite circuit board, is to form a plurality of vias under each LED through the thickness of the PCB. The vias are filled with a metal or alloy having high thermal conductivity and connected to a heat sink attached to the PCB opposite to the LED. However, the formation of such vias adds to the cost of manufacturing the pcb. In addition, the rate of heat dissipation is limited by the rate of heat conduction through the vias because of their typical small cross section. [0006] Another approach is to provide thermally conductive substrates on which electronic components are mounted. These substrates generally perform a function of mechanical support, also provide for electrical interconnection to and between components, and assist in the extraction and dissipation of heat generated by the electronic components. These substrates often are costly or require complicated multi-step manufacturing processes. For example, substrates have been made of thermally conductive ceramics or metals coated or laminated with dielectric materials. Thermally conductive ceramic substrates are costly compared to metals and are, therefore, more appropriately reserved for high temperature applications or for devices the price of which is a secondary concern. When coated or laminated metallic substrates are used, the electrical insulating property of the coating is important. Puncture voltage and dielectric dissipation of the insulating coating directly depend on film thickness, but the rate of heat dissipation inversely depends on the film thickness. Thus, a compromise must be accepted which often results in a less efficient overall device. [0007] Therefore, there exists a continued need to provide interconnect structures for LEDs that allow for rapid heat dissipation and are cost effective and simple to make. In addition, it is also very desirable to provide interconnect structures for LEDs that are mechanically flexible such that devices having substantial curvature are made. SUMMARY OF INVENTION [0008] A flexible interconnect structure comprises a flexible dielectric film having at least a first surface and a second surface and circuit traces being disposed on at least one of the film surfaces. In addition, one or more electrical circuit components can be disposed on a surface of the dielectric film and connected to at least a circuit trace to form an electrical circuit. Portions of the flexible dielectric film are removed through the thickness of the film. Flexible interconnect structures of the present invention allow for rapid dissipation of heat generated during the fabrication or use of electrical devices which comprise such flexible interconnect structures. [0009] In one aspect of the present invention, an electrical device comprises: (1) a flexible interconnect structure comprising a flexible dielectric film having a first surface and a second surface, electrical circuit components and circuit traces being disposed on at least one of the film surfaces, at least a portion of the flexible dielectric film being removed through the thickness thereof and at least a heat sink attached to one of said film surfaces, said heat sink covering said portion of said flexible film that has been removed and being electrically isolated from said circuit components and at least one of said circuit traces; and (2) at least one light-emitting diode ("LED") or a laser diode ("LD") attached to said at least a heat sink through said portion of said flexible film that has been removed such that said LED or LD is in thermal contact with said heat sink and is electrically connected to at least one of said circuit traces. [0010] In another aspect of the present invention, an electrical device of the present invention is a light source. [0011] In still another aspect of the present invention, a method is provided for making a flexible interconnect structure that allows for a dissipation of heat generated during a fabrication or use of electrical devices which comprise such flexible interconnect structures. The method comprises: (1) providing a flexible dielectric film having a first surface and a second surface; (2) disposing electrical circuit components and circuit traces on at least one of said surfaces; and (3) removing at least a portion of said film through a thickness thereof, said portion being devoid of said circuit components and said circuit traces. [0012] In still another aspect of the present invention, the method further comprises attaching at least a heat sink to one of said surfaces of said flexible dielectric film, said heat sink covering said at least a portion of said film that has been removed. [0013] In still another aspect of the present invention, a method for making an electrical device comprising at least a LED comprises: (1) providing a flexible dielectric film having a first surface and a second surface; (2) disposing electrical circuit components and circuit traces on at least one of said surfaces; (3) removing at least a portion of said film through a thickness thereof, said portion being devoid of said circuit components and said circuit traces; (4) attaching at least a heat sink to one of said surfaces of said flexible dielectric film, said heat sink covering said at least a portion of said film that has been removed and being electrically isolated from said circuit components and at least one of said circuit traces; and (5) attaching at least one LED to said at least a heat sink through said portion of the flexible film that has been removed such that the LED is in thermal contact with the heat sink and is electrically connected to at least one of the circuit traces. [0014] Other features and advantages of the present invention will be apparent from a perusal of the following detailed description of the invention and the accompanying drawings in which the same numerals refer to like elements. BRIEF DESCRIPTION OF DRAWINGS [0015] FIG. 1 shows schematically a section of a flexible interconnect structure of the present invention. [0016] FIG. 2 shows the cross-sectional view of the flexible interconnect structure of FIG. 1 along the cut A-A. [0017] FIG. 3 illustrates a flexible interconnect of the present invention that includes multiple layers supporting electrical circuits. [0018] FIG. 4 illustrates another embodiment of the multilayer flexible interconnect of the present invention. [0019] FIG. 5 shows schematically a flexible interconnect including heat sinks. [0020] FIG. 6 shows another embodiment of the flexible interconnect with heat sinks extending through removed portions of the dielectric film. [0021] FIG. 7 shows schematically a LED-based electrical device of the present invention. Continue reading... Full patent description for Flexible interconnect structures for electrical devices and light sources incorporating the same Brief Patent Description - Full Patent Description - Patent Application Claims Click on the above for other options relating to this Flexible interconnect structures for electrical devices and light sources incorporating the same patent application. ###  How KEYWORD MONITOR works... a FREE service from FreshPatents1. Sign up (takes 30 seconds). 2. Fill in the keywords to be monitored. 3. Each week you receive an email with patent applications related to your keywords. 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