HEAT DISSIPATION FROM CIRCUITS THROUGH QUANTOM DOT OPTICS AND LED INTEGRATION
20170250332 · 2017-08-31
Inventors
Cpc classification
International classification
Abstract
A method is presented for forming a structure for dissipating heat. The method includes forming a first conductive material, forming a dielectric layer over the first conductive material, and forming a second conductive material over the dielectric layer such that the first and second conductive materials are coplanar along a longitudinal axis defined by a mounting surface of the first and second conductive materials. The method further includes attaching an electronic component to the mounting surface of the first and second conductive materials such that a first electrode of the electronic component electrically contacts the first conductive material and a second electrode of the electronic component electrically contacts the second conductive material.
Claims
1. A method of forming a structure for dissipating heat, the method comprising: forming a first conductive material; forming a dielectric layer over the first conductive material; forming a second conductive material over the dielectric layer such that the first and second conductive materials are coplanar along a longitudinal axis defined by a mounting surface of the first and second conductive materials; and attaching an electronic component to the mounting surface of the first and second conductive materials such that a first electrode of the electronic component electrically contacts the first conductive material and a second electrode of the electronic component electrically contacts the second conductive material.
2. The method of claim 1, further comprising coupling one or more conducting layers to the mounting surface of the first and second conductive materials before attaching the electronic component thereto.
3. The method of claim 1, wherein the electronic component is one or more light emitting devices.
4. The method of claim 1, wherein, in an assembled state, to enable electrification of the electronic component, the first conductive material includes one or more first interconnects and the second conductive material includes one or more second interconnects.
5. The method of claim 1, further comprising offsetting the first conductive material from the second conductive material along the mounting surface.
6. The method of claim 5, further comprising forming a reflective cavity surrounding the electronic component and including a photoluminescent material within an inner surface of the reflective cavity, the photoluminescent material being hermetically sealed within the reflective cavity.
7. The method of claim 6, wherein the photoluminescent material has one or more down-converting quantum dots or phosphors.
8. The method of claim 7, wherein the quantum dots include a protective aluminum oxide shell.
9. The method of claim 1, further comprising encasing the structure with a reflective material such that a reflective cavity is defined to interface with the electronic component, the reflective cavity including a photoluminescent material having one or more down-converting quantum dots or phosphors.
10. The method of claim 9, further comprising integrating a light guide with the reflective material encasing the structure.
11. A method of forming a structure for dissipating heat, the method comprising: forming a dielectric layer; forming a plurality of first conductive materials defining a first type of configuration on a first side of the dielectric layer; forming a plurality of second conductive materials defining a second type of configuration on a second side of the dielectric layer, where the second type of configuration is different than the first type of configuration; and attaching an electronic component to each of the plurality of first and second conductive materials such that a first electrode of the electronic component electrically contacts a first conductive material and a second electrode of the electronic component electrically contacts a second conductive material on opposed ends of the dielectric layer.
12. The method of claim 11, wherein each of the plurality of first conductive materials includes a first opening and each of the plurality of second conductive materials includes a second opening such that the first and second openings align with an opening of the plurality of openings of the dielectric layer.
13. The method of claim 12, wherein inner surfaces defined by the first opening, the second opening, and the opening of the dielectric layer include a conductive material.
14. The method of claim 11, wherein a bus is formed adjacent the dielectric layer such that the plurality of first conductive materials are separated into one or more first groups and the plurality of second conductive materials are separated into one or more second groups.
15. The method of claim 11, wherein the electronic component is one or more light emitting devices.
16. The method of claim 11, further comprising encasing the structure with a reflective material such that a reflective cavity is defined to interface with the electronic component attached to each of the plurality of first and second conductive materials, the reflective cavity including a photoluminescent material, the photoluminescent material being hermetically sealed within the reflective cavity.
17. The method of claim 16, wherein the photoluminescent material has one or more down-converting quantum dots or phosphors.
18. The method of claim 17, wherein the quantum dots include a protective aluminum oxide shell.
19. The method of claim 11, further comprising encasing the structure with a reflective material such that each electronic component is associated with a reflective cavity, each reflective cavity including a different photoluminescent material for production of a plurality of different colors.
20. The method of claim 19, further comprising integrating a light guide with the reflective material encasing the structure.
21. A structure for dissipating heat, the structure comprising: a first conductive material; a dielectric layer formed over the first conductive material; a second conductive material formed over the dielectric layer such that the first and second conductive materials are coplanar along a longitudinal axis defined by a mounting surface of the first and second conductive materials; and an electronic component attached to the mounting surface of the first and second conductive materials such that a first electrode of the electronic component electrically contacts the first conductive material and a second electrode of the electronic component electrically contacts the second conductive material.
22. The structure of claim 21, wherein the electronic component is one or more light emitting devices.
23. The structure of claim 21, further comprising encasing the structure with a reflective material such that a reflective cavity is defined to interface with the electronic component attached to each of the plurality of first and second conductive materials, the reflective cavity including a photoluminescent material, the photoluminescent material being hermetically sealed within the reflective cavity.
24. The structure of claim 23, wherein the photoluminescent material has one or more down-converting quantum dots or phosphors.
25. The structure of claim 24, wherein the quantum dots include a protective aluminum oxide shell.
26. The structure of claim 21, further comprising encasing the structure with a reflective material such that each electronic component is associated with a reflective cavity, each reflective cavity including a different photoluminescent material for production of a plurality of different colors, the different photoluminescent materials being hermetically sealed within their reflective cavity.
Description
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS
[0011] The invention will provide details in the following description of preferred embodiments with reference to the following figures wherein:
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[0045] Throughout the drawings, same or similar reference numerals represent the same or similar elements.
DETAILED DESCRIPTION
[0046] In one or more exemplary embodiments, a substrate which reduces thermal resistance between a given component and its circuit is presented. The substrate may also serve as a way to electrify electrical components which are mounted thereon. In one example embodiment, an electrical component, e.g., a light emitting diode (LED) is mounted directly onto the substrate. However, this is not a limiting electronic component as other electronic components requiring heat dissipation may be mounted thereof.
[0047] In one or more exemplary embodiment, the substrate is designed to accommodate eutectic attach die where substantially coplanar electrodes are lined up on the substrate. These die are usually bonded via, e.g., thermal processes. However, this is not a limiting example, as other functionally equivalent processes for attaching components may exist, such as, but not limited to, ultrasonic bonding. Other methods, such as soldering can also be used, which requires less coplanarity.
[0048] In one or more embodiments, a dielectric layer is flanked between a first conductive material and a second conductive material to form a structure. The first and second conductive materials can be copper (Cu) materials. The first and second conductive materials can be offset from each other along a mounting surface. An electronic component is attached to the structure such that first and second electrodes of the electronic component are coplanar with the mounting surface of the first and second conductive materials. The electronic component can be, e.g., a light emitting diode (LED). The electronic components can interfaced with, e.g., a quantum dot matrix or a phosphor matrix. The quantum dot can include, e.g., a protective aluminum oxide shell.
[0049] In one or more embodiments, a reflective cavity including a photoluminescent material therein can be incorporated to surround the electronic component or light emitting device. The reflective cavity allows for directing light in one direction toward, e.g., a lens to produce one or more colors.
[0050] In one or more embodiments, a plurality of first conductive materials can be formed on one side of a dielectric layer and a plurality of second conductive materials can be formed on another side of the dielectric layer to form another structure. The first and second sides may be in opposed relation to each other. The plurality of first and second conductive materials can be arranged in a number of different types of configurations. One such example configuration can be an angled configuration. However, one skilled in the art may contemplate other suitable configurations. A bus can be formed on the dielectric layer such that the plurality of first conductive materials can be grouped into a number of first groups and the plurality of second conductive materials can be grouped into a number of second groups. The structure can be encased within a reflective material such that a reflective cavity is defined. The reflective cavity can be defined in such a way to interface with the electronic components (e.g., light emitting devices) including a photoluminescent material. In one example, the reflective material encasing the structure can be integrated with, e.g., a light guide.
[0051] The term “color” as used herein with reference to light is meant to describe light having a characteristic average wavelength. It is not meant to limit the light to a single wavelength. Thus, light of a particular color (e.g., green, red, blue, yellow, etc.) includes a range of wavelengths that are grouped around a particular average wavelength.
[0052] The term “direct contact” or “directly on” means that a first element, such as a first structure, and a second element, such as a second structure, are connected without any intermediary conducting, insulating or semiconductor layers at the interface of the two elements.
[0053] The terms “overlying”, “atop”, “positioned on” or “positioned atop” means that a first element, such as a first structure, is present on a second element, such as a second structure, wherein intervening elements, such as an interface structure can be present between the first element and the second element.
[0054] The term “electrically connected” means either directly electrically connected, or indirectly electrically connected, such that intervening elements are present; in an indirect electrical connection, the intervening elements can include inductors and/or transformers.
[0055] As used herein, “p-type” refers to the addition of impurities to an intrinsic semiconductor that creates deficiencies of valence electrons. In a silicon-containing substrate, examples of p-type dopants, i.e., impurities, include but are not limited to: boron, aluminum, gallium and indium.
[0056] As used herein, “n-type” refers to the addition of impurities that contributes free electrons to an intrinsic semiconductor. In a silicon containing substrate examples of n-type dopants, i.e., impurities, include but are not limited to antimony, arsenic and phosphorous.
[0057] The terms, chip, integrated circuit, monolithic device, semiconductor device, and microelectronic device, are often used interchangeably in this field. The present invention is applicable to all the above as they are generally understood in the field.
[0058] The terms metal line, interconnect line, trace, wire, conductor, signal path and signaling medium are all related. The related terms listed above, are generally interchangeable, and appear in order from specific to general. In this field, metal lines are sometimes referred to as traces, wires, lines, interconnect or simply metal. Metal lines, generally aluminum (Al), copper (Cu) or an alloy of Al and Cu, are conductors that provide signal paths for coupling or interconnecting electrical circuitry. Conductors other than metal are available in microelectronic devices. Materials such as doped polysilicon, doped single-crystal silicon (often referred to simply as diffusion, regardless of whether such doping is achieved by thermal diffusion or ion implantation), titanium (Ti), molybdenum (Mo), and refractory metal silicides are examples of other conductors.
[0059] The term “processing” as used herein includes deposition of material or photoresist, patterning, exposure, development, etching, cleaning, stripping, implanting, doping, stressing, layering, and/or removal of the material or photoresist as required in forming a described structure.
[0060] As used herein, a surface is “substantially planar” if the surface is intended to be planar and the non-planarity of the surface is limited by imperfections inherent in the processing steps that are employed to form the surface.
[0061] As used herein, a “mounting structure” is any structure to which a semiconductor chip can be mounted by making electrical connections thereto. A mounting structure can be a packaging substrate, an interposer structure, or another semiconductor chip or any other electronic component.
[0062] As used herein, the term “about” modifying the quantity of an ingredient, component, or reactant of the invention employed refers to variation in the numerical quantity that can occur, for example, through typical measuring and liquid handling procedures used for making concentrates or solutions. Furthermore, variation can occur from inadvertent error in measuring procedures, differences in the manufacture, source, or purity of the ingredients employed to make the compositions or carry out the methods, and the like. In one aspect, the term “about” means within 10% of the reported numerical value. In another aspect, the term “about” means within 5% of the reported numerical value. Yet, in another aspect, the term “about” means within 10, 9, 8, 7, 6, 5, 4, 3, 2, or 1% of the reported numerical value.
[0063] The word “exemplary” is used herein to mean “serving as an example, instance, or illustration.” Any embodiment described herein as “exemplary” is not necessarily to be construed as preferred or advantageous over other embodiments. Likewise, the term “embodiments” does not require that all embodiments include the discussed feature, advantage or mode of operation.
[0064] It is to be understood that the present invention will be described in terms of a given illustrative architecture; however, other architectures, structures, substrate materials and process features and steps/blocks can be varied within the scope of the present invention. It should be noted that certain features cannot be shown in all figures for the sake of clarity. This is not intended to be interpreted as a limitation of any particular embodiment, or illustration, or scope of the claims.
[0065] Various illustrative embodiments of the invention are described below. In the interest of clarity, not all features of an actual implementation are described in this specification. It will of course be appreciated that in the development of any such actual embodiment, numerous implementation-specific decisions must be made to achieve the developers' specific goals, such as compliance with system-related and business-related constraints, which will vary from one implementation to another. Moreover, it will be appreciated that such a development effort might be complex and time-consuming, but would nevertheless be a routine undertaking for those of ordinary skill in the art having the benefit of this invention.
[0066] The present subject matter will now be described with reference to the attached figures. Various structures, systems and devices are schematically depicted in the drawings for purposes of explanation only and so as to not obscure the present invention with details that are well known to those skilled in the art. Nevertheless, the attached drawings are included to describe and explain illustrative examples of the present invention. The words and phrases used herein should be understood and interpreted to have a meaning consistent with the understanding of those words and phrases by those skilled in the relevant art. No special definition of a term or phrase, i.e., a definition that is different from the ordinary and customary meaning as understood by those skilled in the art, is intended to be implied by consistent usage of the term or phrase herein. To the extent that a term or phrase is intended to have a special meaning, i.e., a meaning other than that understood by skilled artisans, such a special definition will be expressly set forth in the specification in a definitional manner that directly and unequivocally provides the special definition for the term or phrase.
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[0068] The structure 5 includes a conductive layer 4 formed over a dielectric layer 2. An electronic component 6 is mounted to the top surface 3 of the conductive layer 4 by a first electrode 7 and a second electrode 8. The electronic component 6 is, e.g., a heat generating electronic component. The conductive layer 4 is e.g., a circuit conductor. The dielectric layer 2 can be, e.g., FR4, ceramic or any other type of dielectric material.
[0069] The dielectric layer 2 introduces thermal resistance to the electronic component 6. Generally, electrodes 7, 8 are configured to be close to one another, thus introducing dimensional constrains to the placement of bond pads (not shown) on a given printed circuit board (PCB). Due to fabrication limitations of etching patterns or circuits onto these PCB's or other circuits, the overall thickness of pads is limited. Because of these limitations, these conductors are not able to serve as effective heat spreaders, heatsinks or thermal dissipators.
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[0071] The structure 10 includes a first conductive material 12, a second conductive material 14, and a dielectric layer 16 sandwiched between the first and second conductive materials 12, 14. Stated differently, the first and second conductive materials 12, 14 flank the dielectric layer 16. The first conductive material 12 can have a thickness substantially equal to the thickness of the second conductive material 14. Alternatively, the first conductive material 12 can have a thickness that is not equal to the thickness of the second conductive material 14. The first and second conductive materials 12, 14 can have a thickness that is greater than the thickness of the dielectric layer 16. In one example embodiment, the first and second conductive materials 12, 14 can be copper (Cu) or aluminum (Al). Of course, one skilled in the art may contemplate using any other suitable materials.
[0072] An electronic component 18 is attached or connected or bonded to the first and second conductive materials 12, 14. In particular, the electronic component 18 includes a first electrode 20 and a second electrode 22. The first electrode 20 is connected or bonded or attached to the first conductive material 12, whereas the second electrode 22 is connected or bonded or attached to the second conductive material 14. A top surface 11 of the first conductive material 12 contacts or engages a bottom surface of the first electrode 20. Similarly, a top surface 13 of the second conductive material 14 contacts or engages a bottom surface of the second electrode 22. The first electrode 20 can be referred to as an anode and the second electrode 22 can be referred to as a cathode, and vice versa.
[0073] The top surfaces 11, 13 of the first and second conductive materials 12, 14 are substantially coplanar in order to facilitate alignment of the electrodes 20, 22. Stated differently, the first and second conductive materials 12, 14 are coplanar along a longitudinal axis X-X′ defined by mounting surfaces 11, 13 of the first and second conductive materials 12, 14 (as well as an axis Y-Y′). In other words, the top surfaces of the conductive materials 12, 14 are coplanar with the bottom surfaces of the electrodes 20, 22, respectively. The coplanarity of the two surfaces 11, 13 can be, e.g., within or less than about 1 μm. In a preferred embodiment, the two surfaces 11, 13 can be, e.g., within or less than about 3 μm. In another example embodiment, the coplanarities can range from about 1 μm to about 50 μm. Additionally, coplanar refers to both conductive materials 12, 14 being planar with respect to each other. The coplanarity can be exhibited on any mounting surface and is not limited to surfaces 11, 13. This is merely an illustrative example.
[0074] By mounting the electrodes 20, 22 directly on the conductive materials 12, 14, respectively, substantial reduction of thermal resistance is realized. The conductive materials 12, 14 can be substantially thick, thus providing heat spreading, heat-sinking, and thermal dissipation capabilities while also electrifying components. This methodology allows for enhanced thermal dissipation while electrifying the electrical/electronic component 18. One additional benefit is that the conductive materials 12, 14 can serve as convecting surfaces to dissipate heat into surrounding fluids, such as gases or liquids.
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[0076] In various example embodiments, a structure 15 includes a first conductive material 12, a second conductive material 14, and a dielectric layer 16, where the dielectric layer 16 is flanked by the first and second conductive materials 12, 14.
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[0078] In various example embodiments, an electronic component 18 is attached on a side surface of the structure 15, thus resulting in structure 17. The electronic component 18 can be attached or bonded or connected or mounted on any side surface of the structure 17. The electronic component 18 can be centrally disposed with respect to the dielectric layer 16. Of course, one skilled in the art may contemplate attaching the electronic component 18 on any location of the side surface of structure 17, whether centered or not. Additionally, a longitudinal axis Y-Y′ can extend through the structures 15, 17.
[0079] In one example embodiment, the electronic component 18 can be, e.g., a light emitting diode (LED) or a laser diode. Of course, one skilled in the art may contemplate any type of light emitting device serving as the light emitting device 18.
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[0081] In various example embodiments, the electronic component 18 is shown attached to a side surface 19 of the structure 17 of
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[0083] In various example embodiments, the electrodes 20, 22 are shown with respect to the first and second conductive materials 12, 14. The first electrode 20 extends a distance X.sub.1 over the mounting surface 11 (
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[0085] In various example embodiments, a plurality of electronic components 18 can be attached to a side surface 19 of the structure 21. Additionally, a reflective cavity 50 including a photoluminescent material 52 filled or coated thereto can be formed around or surrounding one or more electronic components 18. The reflective cavity 50 will be described in more detail below with reference to
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[0087] In various example embodiments, the structure 21 of
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[0089] In various example embodiments, a staggered array 10″ can be formed. In the staggered array 10″, the first conductive material 12 is offset from the second conductive material 14. The first conductive material 12 can extend a length L1, whereas the second conductive material 14 can extend a length L2. An overlap region can be created by lengths L1 and L2. Additionally, gaps 26 are formed due to the formation of the staggered array 10″. The gaps 26 can extend a length L3. The gaps 26 are created for cooling purposes.
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[0091] In various example embodiments, an enlarged view of the electronic component 18 is shown to illustrate the electrodes 20, 22 formed underneath. The first electrode 20 extends a distance X.sub.1 over the mounting surface 11 of the first conductive material 12 and the second electrode 22 extends a distance X.sub.2 over the mounting surface 13 of the second conductive material 14.
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[0093] In various example embodiments, a side surface of structure 15 of
[0094] One skilled in the art may also contemplate using more than two conducting layers. Moreover, one or more electronic components 18 can be attached to the conducting layers 30, 32. Thus, the conducting layers 30, 32 are formed between the side surface of the structure 15 and one or more electronic components 18 attached thereto. It is also contemplated that more than one side surface of structure 15 includes conducting layers 30, 32. For example, two side surfaces of the structure 15 can be configured to receive the conducting layers 30, 32. These surfaces may be adjacent surfaces or opposed surfaces. Of course, even all surfaces may be configured to receive conducting layers 30, 32. The conducting layers 30, 32 can extend along an entire or partial side surface of the structure 15. The structure 15 can have a width “W” and a height “H.” Thus, in one example, the conducting layers 30, 32 can extend along an entire width “W” or height “H” of the side surfaces of the structure 15.
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[0096] In various example embodiments, a structure 25 can be formed by flanking a dielectric layer 16 between a first conductive material 12′ and a second conductive material 14′. The first conductive material 12′ may include one or more interconnects 36. Interconnects 36 can be, e.g., protruding tabs. The interconnects 36 can also each include an aperture or opening 37. The second conductive material 14′ may include one or more interconnects 38. Interconnects 38 can be, e.g., protruding tabs. The interconnects 38 can also each include an aperture or opening 39. The interconnects 36 can be offset from the interconnects 38. The interconnects 36, 38 aid in the electrification of electrical components 18.
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[0098] In various example embodiments, a structure 40 can include a first conductive material 42 that is offset from a second conductive material 44. A dielectric layer 46 is disposed between a section where the first and second conductive materials 42, 44 overlap. The dielectric layer 46 can extend a distance “B” from a first end 45 to a second end 47. The first conductive material 42 can extend a distance “D” away from the dielectric layer 46, whereas the second conductive material 44 can extend a distance “C” away from the dielectric layer 46. The offset creates a longer heat path. Stated differently, the heat generated by the electronic component 48 can be spread across a greater surface. Thus, the first and second conductive materials 42, 44 can be referred to as convecting surfaces.
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[0100] In various example embodiments, an electronic component 48 is attached or connected or bonded to the top surfaces 41, 43 of the first and second conductive materials 42, 44, respectively. The electronic component 48 can be, e.g., centered over the dielectric layer 46 such that the electronic component 48 substantially equally contacts or engages the top surfaces 41, 43 of the first and second conductive materials 42, 44, respectively.
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[0102] In various example embodiments, a reflective cavity 50 is formed around or surrounding the electronic component 48. The reflective cavity 50 can have, e.g., a substantially circular configuration. Of course, the reflective cavity 50 can be arranged in a variety of other suitable shapes. The reflective cavity 50 can further have a photoluminescent material 52 therein. The photoluminescent material 52 can be, e.g., coated or deposited by any manner. The photoluminescent material 52 can be positioned, e.g., by a fill technique. The final structure can be designated as 40′.
[0103] The photoluminescent material 52 can be, e.g., a quantum dot or a phosphor, as described below. The reflective cavity 50 can be referred to as an optical cavity having reflective properties for assisting in reflecting light in the context of light emitting devices. The reflective materials 52 can include, but are not limited to, multi-layer polymer films, metallized polymers, polished metals, a distributed Bragg reflector, white surfaces or other functional equivalents. Each reflective cavity 50 can be standalone cavity or can be configured in an array of row columns or other patterns. The reflective cavities 50 can be formed, stamped, injection molded, printed or assembled from separate components. Each reflective cavity 50 can include a single LED or a plurality of LEDs. Each reflective cavity 50 can include a quantum dot matrix or a phosphor matrix. Matrices are defined as optical materials including a dispersion of quantum dots (nano-semiconductor crystals or rare earth phosphors). Optical materials can further include polymers, such as acrylics, ultraviolet (UV) cured materials, silicones or other optically transmissive materials. Reflective cavities 50 and reflective materials 52 will be discussed further below with reference to
[0104] Moreover, high refractive index materials, such as titanium dioxide, cubic zirconium or other functional equivalents can be added to the optical matrix to enhance light extraction from the electrical component 48. By more closely increasing the refractive index of the matrix interfacing the chip to match the refractive index of the chip, a reduction of total internal reflection in the chip occurs, thus allowing more light to escape a boundary layer of the electronic component 48 and travel into the optical matrix, which includes down converting materials, such as quantum dots and phosphors.
[0105]
[0106] In various example embodiments, a hermetic seal 54 can be included over the electronic component 48. The hermetic seal 54 can extend along the entire portion of the reflective cavity 50 such that it seals the entire contents of the reflective cavity 50. Thus, the quantum dots or phosphors can be hermetically sealed or encapsulated within the reflective cavity 50. The final structure including the seal 54 can be designated as 40″.
[0107]
[0108] In various example embodiments, the structures 40′, 40″ can be mounted onto a circuit board 68 to create series circuits and/or parallel circuits 60. The circuit board 68 can include a plurality of pads. For example, pads 62, 64, 66 can be formed onto the circuit board 68 to enable electrical connection between the structures 40′, 40″, which include a plurality of photoluminescent materials, such as LEDs or down-converting quantum dots or phosphors.
[0109] Light emitting diodes (LED or LEDs) are solid state devices that convert electric energy to light, and generally comprise one or more active layers of semiconductor material sandwiched between oppositely doped layers. When a bias is applied across the doped layers, holes and electrons are injected into the active layer where they recombine to generate light. Light is emitted from the active layer and from all surfaces of the LED.
[0110] Light that is perceived as white is necessarily a blend of light of two or more colors (or wavelengths), and light emitting diodes are inherently narrow-band emitters. No single light emitting diode junction has been developed that can produce white light. A representative example of a white LED lamp or LED package includes a blue LED chip (e.g., made of InGaN and/or GaN), coated with a broad-band emitter, such as phosphor (typically YAG:Ce or BOSE). A broad-band emitter generally has an emission pattern with an approximate full width half maximum (FWHM) greater than 100 nm. Blue LEDs made from InGaN exhibit high efficiency (e.g., external quantum efficiency as high as 70%). In a blue LED/yellow phosphor lamp, a blue LED chip may produce an emission with a wavelength of about 450 nm, and the phosphor may produce yellow fluorescence with a peak wavelength of about 550 nm upon receipt of the blue emission. Part of the blue ray emitted from the blue LED chip passes through the phosphor, while another portion of the blue ray is absorbed by the phosphor, which becomes excited and emits a yellow ray. The viewer perceives an emitted mixture of blue and yellow light (sometimes termed ‘blue shifted yellow’ or ‘BSY’ light) as cool white light.
[0111] As an alternative to stimulating a yellow phosphor with a blue LED, another method for generating white emissions involves combined use of red, green, and blue (“RGB”) light emitting diodes in a single package. The combined spectral output of the red, green, and blue emitters may be perceived by a user as white light. Each “pure color” red, green, and blue diode typically has a full-width half-maximum (FWHM) wavelength range from about 15 nm to about 30 nm. Due to the narrow FWHM values of these LEDs (particularly the green and red LEDs), aggregate emissions from the red, green, and blue LEDs exhibit very low color rendering in general illumination applications.
[0112] A quantum dot (semiconductor nanocrystallites) is a material, generally semiconductor material, having a crystalline structure only a few nanometers in size, and typically includes about a few hundred atoms to about a few thousand atoms. Because of their small size, quantum dots display unique optical and electrical properties that are different in character to those of the corresponding bulk material. The most immediately apparent of these is the emission of photons under excitation, which are visible to the human eye as light. Quantum dots absorb and emit light at wavelengths determined by their size. Quantum confinement of both the electron and hole in all three dimensions leads to an increase in the effective band gap of the material with decreasing crystallite size. Consequently, both the optical absorption and emission of quantum dots shift to the blue (higher energies) as the size of the dots gets smaller and shift to the red as the size of the dots increase. It has been found that a cadmium selenide (CdSe) quantum dot, for example, can emit light in any monochromatic, visible color, where the particular color characteristic of that dot is dependent only on its size. Dots can even be tuned beyond visible light, into the infra-red or into the ultra-violet. The light emitting characteristics of the quantum dot can be adjusted by controlling the size and composition of the quantum dot, and therefore the quantum dot may be employed in various light emitting devices.
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[0114] In various example embodiments, a structure 70 is formed with a dielectric layer 71 flanked between a plurality of first conductive materials 72 and a plurality of second conductive materials 74. The plurality of first conductive materials 72 are formed on one side of the dielectric layer 71, whereas the plurality of second conductive materials 74 are formed on the other side of the dielectric layer 71. The first and second sides of the dielectric layer 71 are in opposed relation to each other. The dielectric layer 71 can include a plurality of openings 78. The plurality of openings 78 can be arranged, e.g., in a series configuration. Of course, the plurality of openings 78 can be arranged in other suitable configurations. In one example, no openings 78 are used. Instead, the conductive materials 72, 74 are connected by a variety of other means (e.g., through pins, crimping, wire bonding, solder, etc.).
[0115] The plurality of first conductive materials 72 may be of a first type of configuration and the plurality of second conductive materials 74 may be of a second type of configuration. In one example, the first and second conductive materials 72, 74 can be formed or arranged in parallel rectangular shapes. Stated differently, the plurality of first conductive materials 72 can be, e.g., arranged at a first angle such that the conductors are parallel to each other along an entire first surface of the dielectric layer 71. Similarly, the plurality of second conductive materials 74 can be, e.g., arranged at a second angle such that the conductors are parallel to each other along an entire second surface of the dielectric layer 71. Each of the plurality of first and second conductive materials 72, 74 further includes an opening at a distal end thereof configured to be aligned with respective openings 78 of the dielectric layer 71. Of course, the conductive materials 72, 74 need not be arranged in an angled configuration. Other different shaped conductors may be contemplated.
[0116] In one example, as shown in
[0117] Similarly, in one example, at a proximal end of the dielectric layer 71, a first conductive material 72B is arranged to contact a first electrode P1 and a second conductive material 74B is arranged to contact a second electrode Ni of a common electronic component 76B. At a distal end of the dielectric layer 71, the first conductive material 72B extends at an angle to align its opening with an opening 78 of the dielectric layer 71 in region R3.
[0118]
[0119] In various example embodiments, the structure 70′ is shown where the entire second surface of the dielectric layer 71 has been covered with the second conductive material 74. It is noted that the first surface of the dielectric layer 71 has been covered with the first conductive material 72. This configuration of conductive materials 72, 74 allows electrical components 76 to be connected in a series configuration. This series configuration can create edge mounted light emitting devices for a variety of applications.
[0120]
[0121] In various example embodiments, the structure 70″ is shown where the entire second surface of the dielectric layer 71 has been covered with the second conductive material 74. It is noted that the first surface of the dielectric layer 71 has been covered with the first conductive material 72. The structure 70″ differs from the structure 70′ in that a bus 80 is formed. The bus 80 is formed such that it splits the plurality of second conductive materials 74 into one or more groups. In this example, two groups are shown, a first group 82 and a second group 84. The grouping of the chips can be based on design choice to suit, e.g., power supply requirements. Similarly, the bus 80 is formed such that it splits the plurality of first conductive materials 72 into one or more groups (not shown). One skilled in the art may contemplate splitting the conductive materials 72, 74 into a number of different groups. Therefore, multiple strings of electrical components 76 can be grouped together.
[0122]
[0123] In various example embodiments, the opening 78 at the bus 80 is shown. The inner surfaces of the first conductive material 72, the second conductive material 74, and the dielectric layer 71 are illustrated. Such inner surfaces of the opening of the bus 80 are not provided (e.g., coated) with any material. In contrast, the openings 78 of the conductive materials 72, 74 are, e.g., provided with a metallic material 79. The metallic material 79 can be, e.g., aluminum, nickel, gold, etc. In one example, no openings 78 are used. Instead, the conductive materials 72, 74 are connected by a variety of other means (e.g., through pins, crimping, wire bonding, solder, etc.).
[0124]
[0125] In various example embodiments, the structure 70″ of
[0126]
[0127] In various example embodiments, a structure including a dielectric layer 16 flanked between a first conductive material 12 and a second conductive material 14, where a plurality of electronic components 18 are attached thereon is introduced. The structure is, e.g., encased within, e.g., a reflective material 100. The reflective material 100 includes front and back walls 102 and side walls 104. The reflective material 100 is not limited to the illustrated shape. One skilled in the art may contemplate various geometric configurations for reflective material 100. Alternatively, the reflective cavities can be formed by other methods, such as, but not limited to, injection molding, etc.
[0128] The reflective material 100 is configured to form a reflective cavity defined to interface with the electronic components 18. Stated differently, the electronic components 18 are positioned within the reflective cavity, thus creating a linear array of electronic components within the reflective cavity. The reflective cavity can be sealed off by a photoluminescent material 106. The photoluminescent material 106 can have one or more down-converting quantum dots or phosphors (or quantum dot matrix or phosphor matrix). The quantum dots can include, e.g., a protective aluminum oxide shell. In the instant case, the electronic components 18 are all included within a single cavity formed by the reflective material 100, such that all the electronic components 18 are exposed to a, e.g., single photoluminescent material 106. Alternatively, the electronic components 18 can be exposed to a plurality of down-converting materials dispersed in the matrix, e.g., green QDs, red QDs, or additional wavelengths, or phosphors.
[0129]
[0130] In various example embodiments, a light guide 110 can be interfaced with the light emitting surface of the structures described herein encased within the reflective material 100.
[0131]
[0132] In various example embodiments, the reflective material 100 can include front and back walls 102, side walls 104, as well as a plurality of reflector divider walls 112. The divider walls 112 can be placed between the plurality of electronic components 18. Thus, each electronic component 18 can be isolated within its own reflector cavity.
[0133] This configuration 120 allows for a plurality of reflector cavities to be formed with separated monochromatic colors in an array. This configuration 120 allows each electronic component 18 to be associated with a respective photoluminescent material. For example, one electronic component 18 is associated with photoluminescent material 121, another electronic component 18 is associated with photoluminescent material 123, another electronic component 18 is associated with photoluminescent material 125, and another electronic component 18 is associated with photoluminescent material 127.
[0134] The first photoluminescent material 121 can be configured to allow its respective electronic component 18 to emit, e.g., a red light. The second photoluminescent material 123 can be configured to allow its respective electronic component 18 to emit, e.g., a green light. The third photoluminescent material 125 can be configured to allow its respective electronic component 18 to emit, e.g., a yellow light. The fourth photoluminescent material 127 can be configured to allow its respective electronic component 18 to emit, e.g., a blue light. Therefore, each reflective cavity can have or produce a separate color. This configuration 120 prevents cross talk between colors, thus reducing system inefficiencies. In addition, each reflective cavity (or cell) can produce light of a different wavelength, which is then emitted into either ambient environments or in a light guide 110 (
[0135]
[0136] In various example embodiments, the light guide 110 interfaces with the structure 70′ of
[0137]
[0138] In various example embodiments, an optical structure 130 can be used. The optical structure can be referred to as a reflector 130. The reflector 130 defines a reflector cavity 132. The reflector cavity 132 can include a photoluminescent material 134. The photoluminescent material 134 can be, e.g., a quantum dox matrix or a phosphor matrix. The quantum dot matrix can include, e.g., a protective aluminum oxide shell. An optical dichroic filter 136 can be positioned at a distal end of the reflector cavity 132 and the distal end of the quantum dot matrix 134. An optical silicone 138 (or other optically transmissive material) can be positioned adjacent the optical dichroic filter 136. An electronic component 140 can be attached adjacent the optical silicone 138. The electronic components 140 can be a light emitting device. The light emitting device can be, e.g., an LED or a plurality of LEDs. The proximal end of the reflector 130 can include a lens 145. The reflector cavity 132 enables emission of light to be directed in one direction, indicated by arrows “A,” that is, toward the lens 145. The optical dichroic filter 136 blocks any light going in the direction of the electronic components 140. Thus, a higher intensity beam of light can be directed toward the lens 145. The dichroic filter 136 is a thin-film filter or an interference filter that is a very accurate color filter used to selectively pass light of a small range of colors while reflecting other colors.
[0139] This is only one non-limiting example of an optical structure 130. One skilled in the art may contemplate forming a number of different optical structures having different geometric configurations and including a number of different components therein. The exemplary embodiments of the present invention are not limited to this type of optical structure of
[0140]
[0141]
[0142]
[0143] Quantum dots are particularly sensitive to oxygen, moisture, and heat. In the exemplary embodiments of
[0144] The hermetic seal system 200 includes a substrate 202 for mounting a light emitting device 206 via a pad 204. The light emitting device 206 can be, e.g., an LED. The matrix of quantum dots 210 may contain one or more quantum dots of different output wavelengths (colors) dispersed. The quantum dot matrix 210 can be coupled to the light emitting device 206 and the substrate 202. The hermetic seal 212 can include a glass section 213. The hermetic seal 212 is attached to the quantum dot matrix 210 via the glass section 213 by, e.g., bonding, welding, soldering, etc. The reflective cavity 208 can be, e.g., bonded, welded, soldered or brazed to the substrate 202. This construction allows for complete encapsulation of the quantum dot matrix 210 within the hermetic seal 212, which serves as an oxygen/moisture sealed cavity. However, light can be transmitted through the glass section 213. The substrate 202 can be, e.g., a metallized ceramic or other type of circuit board, which allows for hermetically sealing of the quantum dot matrix 210. The pad 204 can be connected to traces 215 that extend beyond the reflective cavity 208. The traces 215 can be directed through the substrate in the z-axis and connected to another circuit layer. One of the traces 215 can be connected to the reflective cavity 208. The reflective cavity 208 can be mounted on a bonding pad to create the hermetic seal and also allow for electrical connection to the chip and any outside circuit trace.
[0145] In summary, by directly coupling the electronic components (or LEDs), less heat can be generated and better heat dissipation can be achieved for integrated circuit packages. The exemplary embodiments of the present invention basically form a novel heat sink with interconnects.
[0146] It is to be understood that the present invention will be described in terms of a given illustrative architecture; however, other architectures, structures, substrate materials and process features and steps/blocks can be varied within the scope of the present invention.
[0147] The present embodiments can include a design for an integrated circuit chip, which can be created in a graphical computer programming language, and stored in a computer storage medium (such as a disk, tape, physical hard drive, or virtual hard drive such as in a storage access network). If the designer does not fabricate chips or the photolithographic masks used to fabricate chips, the designer can transmit the resulting design by physical mechanisms (e.g., by providing a copy of the storage medium storing the design) or electronically (e.g., through the Internet) to such entities, directly or indirectly. The stored design is then converted into the appropriate format (e.g., GDSII) for the fabrication of photolithographic masks, which typically include multiple copies of the chip design in question that are to be formed on a wafer. The photolithographic masks are utilized to define areas of the wafer (and/or the layers thereon) to be etched or otherwise processed.
[0148] Methods as described herein can be used in the fabrication of integrated circuit chips. The resulting integrated circuit chips can be distributed by the fabricator in raw wafer form (that is, as a single wafer that has multiple unpackaged chips), as a bare die, or in a packaged form. In the latter case, the chip is mounted in a single chip package (such as a plastic carrier, with leads that are affixed to a motherboard or other higher level carrier) or in a multichip package (such as a ceramic carrier that has either or both surface interconnections or buried interconnections). In any case, the chip is then integrated with other chips, discrete circuit elements, and/or other signal processing devices as part of either (a) an intermediate product, such as a motherboard, or (b) an end product. The end product can be any product that includes integrated circuit chips, ranging from toys and other low-end applications to advanced computer products having a display, a keyboard or other input device, and a central processor.
[0149] Reference in the specification to “one embodiment” or “an embodiment” of the present invention, as well as other variations thereof, means that a particular feature, structure, characteristic, and so forth described in connection with the embodiment is included in at least one embodiment of the present invention. Thus, the appearances of the phrase “in one embodiment” or “in an embodiment”, as well any other variations, appearing in various places throughout the specification are not necessarily all referring to the same embodiment.
[0150] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of example embodiments. As used herein, the singular forms “a,” “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “comprises,” “comprising,” “includes” and/or “including,” when used herein, specify the presence of stated features, integers, steps, operations, elements and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components and/or groups thereof.
[0151] Spatially relative terms, such as “beneath,” “below,” “lower,” “above,” “upper,” and the like, can be used herein for ease of description to describe one element's or feature's relationship to another element(s) or feature(s) as illustrated in the
[0152] Having described preferred embodiments of a method of device fabrication and a semiconductor device thereby fabricated for dissipating heat through quantum dot optics and light emitting diode (LED) integration (which are intended to be illustrative and not limiting), it is noted that modifications and variations can be made by persons skilled in the art in light of the above teachings. It is therefore to be understood that changes can be made in the particular embodiments described which are within the scope of the invention as outlined by the appended claims. Having thus described aspects of the invention, with the details and particularity required by the patent laws, what is claimed and desired protected by Letters Patent is set forth in the appended claims.