High optical power light conversion device using phosphor elements attached by soldering

Abstract

A high-power light conversion device utilizing a soldered phosphor element is provided. The light conversion device includes a phosphor wheel comprising: an opto-ceramic phosphor element comprising one or more phosphors embedded in a ceramic matrix; a solderable metal stack comprising one or more metal layers deposited on the backside of the opto-ceramic phosphor element; and a metal heat sink, which is a metal disk rotatable about a central axis and attached to the solderable metal stack via a soldered bond on its outer edge. The opto-ceramic phosphor element does not crack in response to a light source applying a beam energy effective to heat the opto-ceramic phosphor element to a phosphor quenching point.

Description

[0001] This application is a divisional application of Chinese patent application No. 201680067495.7. Chinese patent application No. 201680067495.7 is a Chinese national phase application of international application PCT / US2016 / 053367, which claims the benefit of U.S. Provisional Application No. 62 / 265,117, filed on December 9, 2015, entitled “HIGH OPTICAL POWERLIGHT CONVERSION DEVICE USING A PHOSPHOR ELEMENT WITH GLASS HOST.” The entire contents of U.S. Provisional Application No. 62 / 265,117, filed on December 9, 2015, are incorporated herein by reference.

[0002] This International Application PCT / US2016 / 053367 also claims the benefit of U.S. Provisional Application No. 62 / 232,702, filed on September 25, 2015, entitled “HIGHOPTICAL POWER LIGHT CONVERSION DEVICE USING AN OPTOCERAMIC PHOSPHOR ELEMENTWITH SOLDER ATTACHMENT,” which is hereby incorporated by reference in its entirety. Technical Field

[0003] The following relates to optical technologies, phosphor technologies, wavelength conversion technologies and related technologies, and to optoelectronic, photonic and similar applications using these technologies, such as (but not limited to) projection displays (e.g., digital light processing), automotive lighting, etc. Background Art

[0004] Phosphor devices are known for converting the wavelength of light, typically from a shorter wavelength to one or more longer wavelengths. In a typical approach, a phosphor material is dispersed in a transparent or translucent binder material (such as epoxy, silicone, etc.). The phosphor is excited or "pumped" by a laser or other pump light source to emit phosphor light. The phosphor device can be static or can be configured as a phosphor wheel in which the phosphors are arranged near the outer edge of a rotating wheel. The phosphor wheel is designed to advantageously provide a temporal sequence of different colors (or more generally, different spectra) by using different phosphors in different phosphor arc segments. Zero emission periods can also be provided by leaving arc-shaped gaps between the phosphor arc segments. For example, such a wheel can be used to provide sequential red, green, and blue light for a digital light processing (DLP) projector or other DLP display device.

[0005] A problem with high optical power applications is that the binder materials typically used in phosphors are susceptible to thermal damage due to heating from high-power pump lasers. For example, in a typical down-conversion task where blue or ultraviolet laser light is converted to white light (or yellow light mixed with a blue pump laser to form white light), the laser power can be on the order of 25 watts or more, resulting in significant heating.

[0006] A solution to this problem is to replace the binder material with a ceramic material, i.e., to use a photovoltaic ceramic phosphor. Typical ceramic materials are made by sintering a mixture of a powdered substrate, a binder, and a stabilizer at high temperature and optionally under high pressure. Other manufacturing processes such as chemical vapor deposition (CVD) or chemical reactions can be incorporated into the ceramic manufacturing process. For photovoltaic ceramic phosphors, the substrate is selected to contain the desired phosphor components, and the mixture and sintering are designed to produce a matrix material that is optically transmissive over the operating spectrum (including both pump light and phosphorescence). Ceramic materials are denser than conventional phosphor binder materials such as epoxy resins or silicone resins, and photovoltaic ceramic phosphors are generally heat-resistant at least up to sintering temperatures of typically at least several hundred degrees Celsius, and can be as high as 1000°C or higher depending on the sintering process. Therefore, photovoltaic ceramic phosphors are expected to be thermally stable when pumped with high-power lasers.

[0007] Some commercially available photovoltaic ceramic phosphors include yttrium aluminum garnet (YAG), cerium-doped YAG (YAG:Ce), lutetium YAG (LuYAG), silicate-based phosphors, silicon-aluminum-oxynitride (SiAlON) phosphors, etc., embedded in a ceramic matrix such as polycrystalline alumina (Al2O3, PCA), yttrium oxide doped with lanthanum oxide (Y2O3-La2O3), yttrium aluminum garnet (Y3Al5O12 ), magnesium aluminate spinel (MgAl2O4), dysprosium oxide (Dy2O3), aluminum oxynitride (Al 23 O 27 N5), aluminum nitride (AlN), etc. See, for example, Raukas et al., “Ceramic Phosphors for Light Conversion in LEDs,” ECS Journal of Solid State Science and Technology, Vol. 2, No. 2, pp. R3168-76 (2013).

[0008] This article discloses some improvements. Summary of the Invention

[0009] According to some disclosed embodiments, a light conversion device includes an optoelectronic ceramic phosphor element including one or more phosphors embedded in a ceramic matrix; a metal heat sink; and a solder bond attaching the optoelectronic ceramic phosphor element to the metal heat sink.

[0010] According to some disclosed embodiments, a light-converting device includes: a phosphor element comprising one or more phosphors embedded in a solid matrix element; a metal heat sink; and a solder joint attaching the phosphor element to the metal heat sink. In some embodiments, the phosphor element comprises one or more phosphors embedded in a solid glass matrix element.

[0011] According to some disclosed aspects, a light generator includes a light conversion device as described in one of the preceding two paragraphs, and a light source configured to apply a light beam to the light conversion element. In response to the light beam applied by the light source having an energy effective to heat the opto-ceramic phosphor element to a phosphor quenching point, the opto-ceramic phosphor element does not crack.

[0012] According to some disclosed embodiments, a method of manufacturing a light conversion device includes depositing a solderable metal stack on a backside of an optoelectronic ceramic phosphor element comprising one or more phosphors embedded in a ceramic matrix; and attaching the optoelectronic ceramic phosphor element to a metal heat sink by soldering the solderable metal stack to the heat sink.

[0013] According to some disclosed embodiments, a method of manufacturing a light conversion device is disclosed. The method includes depositing a solderable metal stack on the backside of a phosphor element comprising one or more phosphors embedded in a solid matrix element, and attaching the phosphor element to a metal heat sink by soldering the solderable metal stack to the heat sink. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1A phosphor wheel comprising six phosphor segments is shown. Figure 1 Section SS shows a cross section of one of the phosphor elements and a portion of its welded attachment to the metal wheel;

[0015] Figure 2 Shown Figure 1 An exploded view of section SS of FIG. 1 (left side) and a flow chart schematically illustrating the main manufacturing operations (right side); and

[0016] Figure 3 A variant embodiment is shown, in which a heat sink (e.g. Figure 1 The metal wheel) has a recess shaped and sized to accommodate at least the solder attachment portion and optionally a lower portion of the phosphor element. DETAILED DESCRIPTION

[0017] As used herein, and as is common in the art, terms such as "spectrum," "optical," "wavelength," "frequency," "light," "beam," and the like are not limited to the visible spectrum, but may extend through a given filter into or lie entirely within the infrared and / or ultraviolet spectral regions.

[0018] Contrary to the expectation that opto-ceramic phosphors would be thermally stable when pumped with high-power lasers, the inventors discovered that, in fact, opto-ceramic phosphors fail catastrophically as the output of the high-power pump laser increases. Specifically, static opto-ceramic phosphor components mounted to a heat sink using adhesive or thermally conductive paste experience catastrophic cracking during periods of increased high-power pump laser output.

[0019] As disclosed herein, the inventors have discovered that this catastrophic cracking failure mode can be overcome by employing a soldered connection between the opto-ceramic phosphor and a heat sink (e.g., Al or Cu). With solder attachment, the pump laser power can be increased to high pump powers sufficient to produce phosphor quenching without destroying the opto-ceramic phosphor element. Without being limited to any particular theory of operation, the catastrophic failure mode is believed to be caused by insufficient heat conduction out of the opto-ceramic phosphor, either in terms of the thermal resistance of the attachment or the thermal reactance of the attachment (i.e., the delay before thermal conduction increases), and solder attachment improves heat conduction by providing sufficient attachment to overcome the catastrophic cracking failure mode. Given this, it is contemplated that, in addition to solder bonds, other attachment bonds that provide the necessary thermal conductivity properties may be used. For example, it is contemplated that, in place of solder bonds, a bond formed by sintering a powder or paste of silver (Ag) nanoparticles in an organic diluent (to provide a uniform dispersion) may be utilized. Sintering is suitably performed at a temperature below the melting temperature of silver, for example, at approximately 250°C, although in some embodiments, the optimal process temperature depends on factors such as the size, density, and average surface area of the Ag nanoparticles. When sintering occurs, slight pressure may optionally be applied, and / or sintering may optionally be performed in a controlled atmosphere. After sintering, the silver may be operated at a temperature much higher than the sintering temperature. Without being limited to any particular theory of operation, the bonding process in this method is believed to be attributable to an atomic diffusion mechanism.

[0020] More generally, as disclosed herein, a solid phosphor element is attached to a heat sink (e.g., Al or Cu) using a solder connection. Solder attachment can improve thermal conductivity by providing sufficient adhesion, thereby overcoming catastrophic cracking or other thermal failure modes. In view of this, it is contemplated that other attachment bonds, in addition to solder bonds, may be employed that provide the necessary thermal conductivity properties.

[0021] The solder bonding methods disclosed herein can provide benefits for various types of high temperature phosphor elements, such as single or multi-crystalline phosphor elements, glass phosphor elements, etc., in which the phosphor is bonded into a crystal, glass, or other solid matrix material. The solder bonding methods disclosed herein can provide similar benefits for other types of high temperature phosphor elements, such as single or multi-crystalline phosphor elements in which the phosphor is bonded into a crystal with high thermal stability during the crystal growth process.

[0022] Figure 1A phosphor wheel 10 is schematically shown and includes a metal disk or "wheel" 12 made of copper, a copper alloy, an aluminum alloy, or the like. One or more electroceramic phosphor elements (e.g., segments 14) are attached to the periphery of the wheel 12, i.e., at or near the outer edge of the wheel 12. Thus, the metal disk or wheel 12 serves both as a carrier and as a heat sink for the electroceramic phosphor segments 14. The schematic electroceramic phosphor segments 14 are a geometrically advantageous design that minimizes the amount of electroceramic phosphor material while enabling phosphor coverage of the entire wheel circumference. The schematic phosphor wheel 10 includes six electroceramic phosphor segments 14 of equal size; however, more or fewer phosphor segments (including as few as a single electroceramic phosphor segment forming a complete 360° circle) may be used. Although six schematic electro-ceramic phosphor segments 14 are generally illustrated and labeled, it should be understood that different electro-ceramic phosphor segments may include different phosphors (e.g., to emit different colors of phosphor light), and / or that gaps may exist between adjacent electro-ceramic phosphor segments. In operation, the metal wheel 12 is rotated about the central axis 16, for example, by connecting the motor shaft of a motor (not shown) to the central axis 16 and operating the motor to rotate the phosphor wheel 10 in the illustrated clockwise direction CW (counterclockwise rotation is also contemplated). While rotating, pump light is applied to a localized area - this is Figure 1 Schematically illustrated in FIG. , a pump laser beam spot L is applied by laser 18. As metal wheel 12 rotates, it sequentially carries electro-optical ceramic phosphor segments 14 and contacts laser beam L, causing phosphorescence to be emitted. It will be readily appreciated that by appropriately selecting the phosphors of the various electro-optical ceramic phosphor segments 14, a temporal sequence of various colors can be generated, such as red-green-blue-red-green-blue, which is suitable for use in DLP display applications.

[0023] Continue to refer Figure 1 And further reference Figure 2 , section SS schematically shows a cross section of one photovoltaic ceramic phosphor segment 14 and a portion of its welded attachment to the metal wheel 12 . Figure 2 An exploded view of the cross section SS is shown (left) and a flow chart schematically showing the main manufacturing operations (right). It should be noted that the layer thickness is Figure 1 The schematic cross section SS and its Figure 2The exploded view shown in FIG is not drawn to scale. The electro-ceramic phosphor arc segment 14 includes an electro-ceramic phosphor element 20, which (by way of non-limiting example) may include a phosphor such as yttrium aluminum garnet (YAG), cerium-doped YAG (YAG:Ce), lutetium YAG (LuYAG), a silicate-based phosphor, a silicon-aluminum-oxynitride (SiAlON) phosphor, or the like, embedded in a ceramic material that is optically transmissive in the visible spectrum and is, for example, polycrystalline aluminum oxide (Al2O3, PCA), yttrium oxide doped with lanthanum oxide (Y2O3-La2O3), yttrium aluminum garnet (Y3Al5O 12 ), magnesium aluminate spinel (MgAl2O4), dysprosium oxide (Dy2O3), aluminum oxynitride (Al 23 O 27 N5), aluminum nitride (AlN), and the like. See, for example, Raukas et al., “Ceramic Phosphors for Light Conversion in LEDs,” ECS Journal of Solid State Science and Technology, Vol. 2, No. 2, pp. R3168-76 (2013). In other embodiments, phosphor element segment 14 includes phosphor element 20. As non-limiting examples, phosphor element 20 may include a phosphor such as yttrium aluminum garnet (YAG), cerium-doped YAG (YAG:Ce), lutetium YAG (LuYAG), a silicate-based phosphor, a silicon-aluminum-oxynitride (SiAlON) phosphor, and the like, embedded in a crystal, glass, or other solid matrix material that is optically transmissive in the visible spectrum. For example, the matrix material may be glass such as B270, BK7, P-SF68, P-SK57Q1, P-SK58A, P-BK7, and the like.

[0024] The phosphor or phosphor dopant can be appropriately selected to emit a desired emission color, for example, green, yellow, red, or a combination of light colors (e.g., a white phosphor mixture). The optoelectronic ceramic phosphor element 20 can be manufactured using any suitable process, such as (by way of non-limiting example) sintering a mixture of a powdered base material, a binder, and a stabilizer at a high temperature. In other embodiments, such as using a glass matrix material, the phosphor element 20 can be manufactured using a suitable process such as (by way of non-limiting example) melting, molding, sintering, etc.

[0025] In the illustrative example, an opto-ceramic phosphor element is used for illustration. Optionally, one or more optical coatings may be applied to one or more surfaces of the opto-ceramic phosphor element 20. For illustrative purposes, the opto-ceramic phosphor arc segment 14 includes a front anti-reflection (AR) coating 22 and a back dielectric or metal or mixed dielectric / metal mirror coating 24. The term "front" as used herein refers to the side of the opto-ceramic phosphor element 20 that is illuminated by the optical pump laser 18 or other pump beam; and the term "back" as used herein refers to the side of the opto-ceramic phosphor element 20 that is attached to the heat sink 12 (wherein, in the illustrative example, the metal wheel 12 of the phosphor wheel 10 serves as a heat sink for the opto-ceramic phosphor element 20). The AR coating 22 is designed to minimize reflection of the pump laser impinging on the opto-ceramic phosphor element 20 while not hindering the emission of phosphor light. The dielectric mirror coating 24 is designed to reflect phosphor light and is optionally also designed to reflect pump laser light. As Figure 2 As shown, these coatings may be applied by sputter deposition S1, but deposition S1 may be performed using any other deposition technique suitable for depositing the materials comprising these coatings 22, 24. It will also be understood that either or both of the optical coatings 22, 24 may be omitted, and / or that other optical coatings may be provided, such as wavelength selective filter coatings, light scattering coatings, deposited Fresnel lenses, and the like.

[0026] Continue to refer Figure 1 and 2, the opto-ceramic phosphor element 20 and the dielectric or metallic mirror coating 24 (if present) are generally not materials well-suited for solder bonding. To facilitate attaching the opto-ceramic phosphor arc segment 14 to the metal wheel 12 by soldering, the opto-ceramic phosphor arc segment 14 further includes a solderable metal stack 30 deposited on the back side of the opto-ceramic phosphor element 20 (or, more specifically, on the back side of the dielectric mirror coating 24 in the illustrative example). The solderable metal stack 30 can include as little as a single metal layer; in the illustrative embodiment, the solderable metal stack 30 includes: an adhesion layer 32 adjacent to the element 20 of (as non-limiting illustrative examples) chromium, titanium, or a titanium-tungsten (TiW) alloy; a diffusion barrier layer 34 of (as non-limiting illustrative example) nickel; and a solderable metal layer 36 of (as non-limiting illustrative example) gold. This is merely an illustrative example, and a wide variety of solderable solder stacks known in the art for facilitating the soldering of non-metallic elements to metallic elements may be used. By way of some additional non-limiting illustrative examples: solderable metal layer 36 may be silver, platinum, or another solder-compatible metal or metal sub-stack, rather than gold; the nickel diffusion barrier layer may include a few percent (e.g., 5%) of vanadium to reduce its magnetic properties, thereby facilitating deposition by magnetron sputtering; diffusion barrier layer 34 may be omitted entirely and / or adhesion layer 32 may be omitted entirely; and so forth. Figure 2 As shown, in the metal deposition operation S2, the solderable metal stack 30 can be deposited on the back side of the optoelectronic ceramic phosphor element 20 (or more specifically, on the back side of the dielectric mirror coating 24 in the illustrative example) by, for example, sputtering, electroplating, vacuum metal evaporation (e.g., using electron beam evaporation, thermal evaporation), etc., but the deposition S1 can also be performed using any other deposition technology suitable for depositing the materials constituting these solderable metal stacks 30.

[0027] Continue to refer Figure 1 and 2 The optoelectronic ceramic phosphor arc segment 14 comprising the optoelectronic ceramic phosphor element 20, the optional optical coatings 22, 24 and the solderable metal stack 30 is attached to the metal substrate 12 (at Figure 1 In the schematic example of the metal wheel 12). Figure 2In one suitable method, schematically illustrated in FIG, soldering operation S3 entails placing the optoelectronic ceramic phosphor arc segment 14 on the metal heat sink 12 via a solder preform 401 coated with flux 402, with the solder preform 401 interposed between the optoelectronic ceramic phosphor arc segment 14 and the metal heat sink 12. In another contemplated embodiment, the flux is mixed into the solder preform rather than being applied to the solder preform. Various solder alloys can be used as the solder preform 401, such as, by way of non-limiting example, lead / indium / silver solder alloys, gold / tin solder alloys, gold-silicon (AuSi) alloys, and the like. The assembly is then heated to a soldering temperature that effectively causes the solders 401, 402 to form a soldered joint 40 between the solderable metal stack 30 and the metal heat sink 12. Other methods for performing soldering operation S3 are contemplated, such as using a soldering gun to apply premixed solder material and flux to one or both surfaces to be soldered together and then pressing them together. For commercial manufacturing, welding operation S3 should be a high-throughput automated process.

[0028] Brief Reference Figure 3 In a modified embodiment, the heat sink substrate 12 to which the solder attachment is to be formed includes a recess 44 having a shape and depth sufficient to receive a solder preform 401 coated with flux 402, thereby facilitating the soldering operation S3. The resulting device will then have a solder joint 40 disposed in the recess 44. Alternatively, the recess 44 may be deep enough to fully receive the lower portion of the opto-ceramic phosphor arc segment 14, such that the resulting device has the solder joint 40 and the lower portion of the opto-ceramic phosphor element 20 disposed in the recess 44.

[0029] Exemplary embodiments relate to Figure 1 The phosphor wheel 10 is shown. However, it should be understood that the disclosed method for soldering an optoelectronic ceramic phosphor element 20 to a metal heat sink 12 is equally applicable to attaching a static phosphor element to a heat sink. For example, in one application, the optoelectronic ceramic phosphor element 20 contains one or more phosphors that produce yellow or yellowish phosphorescence, and the pump laser beam is a blue laser beam. By appropriately adjusting the phosphor concentration in the optoelectronic ceramic phosphor element 20 and the blue pump beam power, a mixture of blue pump light and yellow or yellowish phosphorescence is produced to approximate white light. The optoelectronic ceramic phosphor element can be used in any desired optical system. As a non-limiting example, a static optoelectronic ceramic phosphor element soldered to a heat sink as disclosed herein can be used in conjunction with a light tunnel, where the high optical power in the light tunnel is accommodated by efficient heat transfer from the optoelectronic ceramic phosphor element to the heat sink via the solder bond as disclosed herein.

[0030] In experimental testing, photovoltaic ceramic phosphor components soldered to a copper heat sink were tested and compared to components attached to the copper heat sink via thermal paste. Some of the tested photovoltaic ceramic phosphor components included a front-side anti-reflective coating 22 and a rear-side dielectric mirror coating 24, the latter designed to act as a backside air interface. In the tests, the photovoltaic ceramic phosphor components attached to the heat sink via soldering were observed to exhibit no cracking for beam energies that effectively heated the photovoltaic ceramic phosphor components up to and beyond the phosphor quenching point. In contrast, photovoltaic ceramic phosphor components attached to the heat sink via thermal paste exhibited catastrophic cracking with increasing pump laser power, and this cracking occurred before the phosphor quenching point was reached, thus limiting the thermal envelope of the device. Deterioration of the anti-reflective coating 22 was also observed in photovoltaic ceramic phosphor components mounted using thermal paste, resulting in a reduced laser-induced damage (LITD) threshold compared to photovoltaic ceramic phosphor components mounted using the disclosed soldering combination. It was also surprisingly observed that the back dielectric mirror coating 24 designed for a back-air interface provided significant light output improvement, even though the back interface was for a solder joint 40, rather than for the design basis air (refractive index n=1). Without being limited to any particular theory of operation, it is believed that this may be due to the significant reflection provided by the multiple stacked layers, resulting in a low fraction of light reaching the back mirror / solder interface.

[0031] These results demonstrate that the disclosed solder attachment method enables the construction of a passive light conversion device comprising an optoelectronic ceramic phosphor element 20 comprising one or more phosphors embedded in a ceramic matrix, a metal heat sink 12, and a solder bond 40 attaching the optoelectronic ceramic phosphor element 20 to the metal heat sink 12. The metal heat sink 12 can operate at pump beam energies up to the phosphor quenching point without cracking the optoelectronic ceramic phosphor element 20. In contrast, conventional thermal paste attachment can lead to catastrophic cracking at values well below the phosphor quenching point, thereby limiting device performance. It should be noted that the disclosed solder bond provides improved device performance for passive optical components, which, in many embodiments, do not include electrical or electronic components.

[0032] It will be appreciated that the various features and functions disclosed above and other features and functions, or alternatives thereof, may be desirably combined into many other different systems or applications. It will be further appreciated that various currently unforeseen or unanticipated alternatives, modifications, variations, or improvements may be subsequently made by those skilled in the art, which are also intended to be encompassed by the appended claims.

[0033] The following items correspond to the originally filed claims of the parent case of this application.

[0034] Item 1. A light conversion device comprising:

[0035] a phosphor wheel comprising;

[0036] Photovoltaic ceramic phosphor elements comprising one or more phosphors embedded in a ceramic matrix;

[0037] Metal heat sink; and

[0038] A solder bond attaches the optoelectronic ceramic phosphor element to the metal heat sink.

[0039] Item 2. The light-conversion device of item 1, wherein the light-conversion device is a static light-conversion device or a phosphor wheel.

[0040] Item 3. The light conversion device according to any one of Items 1 to 2, further comprising:

[0041] A mirror coating is disposed on the back side of the optoelectronic ceramic phosphor element between the optoelectronic ceramic phosphor element and the solder joint.

[0042] Item 4. The light conversion device of Item 3, wherein the mirror is a dielectric mirror designed to operate with a backside air interface.

[0043] Item 5. The light conversion device according to any one of Items 3 to 4, further comprising:

[0044] a weldable metal stack comprising one or more metal layers disposed on the mirror coating between the mirror coating and the weld joint;

[0045] wherein the solder bond is attached to the solderable metal stack.

[0046] Item 6. The light conversion device according to any one of Items 1 to 2, further comprising:

[0047] a solderable metal stack comprising one or more metal layers disposed on a backside of the optoelectronic ceramic phosphor element between the optoelectronic ceramic phosphor element and the solder bond;

[0048] wherein the solder bond is attached to the solderable metal stack.

[0049] Item 7. The light-conversion device of any one of Items 5 to 6, wherein the solderable metal stack comprises one of the following stacks:

[0050] a chromium / nickel / gold layer stack, wherein the solder bond is attached to the gold layer;

[0051] a titanium / nickel / gold layer stack wherein the solder bond is attached to the gold layer;

[0052] a chromium / nickel / silver layer stack, wherein the solder bond is attached to the silver layer; and

[0053] Titanium / nickel / silver layer stack, wherein the solder bond is attached to the silver layer.

[0054] Item 8. The light-conversion device of Item 7, wherein the nickel layer of the solderable metal stack comprises vanadium.

[0055] Item 9. The light conversion device according to any one of Items 1 to 8, wherein the metal heat sink includes a recess, and the solder joint is disposed within the recess.

[0056] Item 10. The light conversion device of Item 9, wherein a lower portion of the optoelectronic ceramic phosphor element is also disposed within the recess of the heat sink.

[0057] Item 11. The light conversion device of any one of Items 1 to 10, wherein the optoelectronic ceramic phosphor element does not crack in response to an applied beam of light having an energy effective to heat the optoelectronic ceramic phosphor element to a phosphor quenching point.

[0058] Item 12. A light generator comprising:

[0059] The light conversion device according to any one of items 1 to 11; and

[0060] a light source arranged to apply a light beam to the light converting element;

[0061] The opto-ceramic phosphor element is responsive to a beam of light applied by the light source having an energy level effective to heat the opto-ceramic phosphor element to a quenching point of the phosphor without cracking.

[0062] Item 13. A light conversion device, comprising:

[0063] a phosphor element comprising one or more phosphors embedded in a solid matrix element;

[0064] Metal heat sink; and

[0065] A solder joint is used to attach the phosphor element to the metal heat sink.

[0066] Item 14. The light-conversion device of Item 13, wherein the light-conversion device is a static light-conversion device or a phosphor wheel.

[0067] Item 15. The light conversion device according to any one of Items 13 to 14, further comprising:

[0068] A mirror coating is disposed on the back side of the phosphor element between the phosphor element and the solder joint.

[0069] Item 16. The light conversion device of Item 15, wherein the mirror is a dielectric mirror designed to operate with a backside air interface.

[0070] Item 17. The light conversion device according to any one of Items 15 to 16, further comprising:

[0071] a solderable metal stack comprising one or more metal layers on the mirror coating between the mirror coating and the solder joint;

[0072] wherein the solder bond is attached to the solderable metal stack.

[0073] Item 18. The light conversion device according to any one of Items 13 to 14, further comprising:

[0074] a solderable metal stack comprising the one or more metal layers on the back side of the phosphor element between the phosphor element and the solder bond;

[0075] wherein the solder bond is attached to the solderable metal stack.

[0076] Item 19. The light-converting device of any one of Items 17 to 18, wherein the solderable metal stack comprises one of the following stacks:

[0077] a chromium / nickel / gold layer stack, wherein the solder bond is attached to the gold layer;

[0078] a titanium / nickel / gold layer stack, wherein the solder bond is attached to the gold layer;

[0079] a chromium / nickel / silver layer stack, wherein the solder bond is attached to the silver layer; and

[0080] Titanium / nickel / silver layer stack, wherein the solder bond is attached to the silver layer.

[0081] Item 20. The light conversion device of Item 19, wherein the nickel layer of the solderable metal stack comprises vanadium.

[0082] Item 21. The light conversion device of any one of Items 13 to 20, wherein the metal heat sink includes a recess, the solder joint being disposed within the recess.

[0083] Item 22. The light conversion device of Item 21, wherein a lower portion of the phosphor element is also disposed within the recess of the heat sink.

[0084] Item 23. The light conversion device of any one of items 13 to 22, wherein the phosphor element comprises one or more phosphors embedded in a solid glass matrix element.

[0085] Item 24. The light-converting device of Item 23, wherein the solid glass matrix element comprises B270, BK7, P-SF68, P-SK57Q1, P-SK58A, or P-BK7.

[0086] Item 25. A light generator comprising:

[0087] The light conversion device according to any one of items 13 to 24; and

[0088] a light source arranged to apply a light beam to the light converting element;

[0089] The opto-ceramic phosphor element is responsive to a beam of light applied by the light source having an energy level effective to heat the opto-ceramic phosphor element to a quenching point of the phosphor without cracking.

[0090] Item 26. A method of manufacturing a light-conversion device, comprising:

[0091] depositing a solderable metal stack on the backside of an optoelectronic ceramic phosphor element comprising one or more phosphors embedded in a ceramic matrix; and

[0092] The optoelectronic ceramic phosphor element is attached to the metal heat sink by soldering the solderable metal stack to the heat sink.

[0093] Item 27. The method according to Item 26, further comprising:

[0094] A dielectric mirror coating is deposited on the back side of the electro-optical ceramic phosphor element before depositing the solderable metal stack on the back side of the electro-optical ceramic phosphor element, thereby depositing the solderable metal stack on the dielectric mirror coating.

[0095] Item 28. The method of any one of items 26 to 27, wherein depositing a solderable metal stack on the back side of the photovoltaic ceramic phosphor element comprises:

[0096] depositing a chromium layer or a titanium layer onto the back side of the optoelectronic ceramic phosphor element or onto a dielectric mirror coating disposed on the back side of the optoelectronic ceramic phosphor element;

[0097] depositing a nickel layer on the chromium layer or the titanium layer; and

[0098] A silver layer, a platinum layer or a gold layer is deposited on the nickel layer.

[0099] Item 29. The method of Item 28, wherein the nickel layer comprises vanadium.

[0100] Item 30. The method of any one of items 26 to 27, wherein depositing the solderable metal stack on the back side of the optoelectronic ceramic phosphor element comprises:

[0101] depositing a solderable silver layer, platinum layer or gold layer on the nickel layer;

[0102] The welding comprises welding the weldable silver layer, platinum layer or gold layer to the heat sink.

[0103] Item 31. The method according to any one of Items 26 to 28, wherein the attaching comprises:

[0104] disposing the optoelectronic ceramic phosphor element on the metal heat sink with a solder preform sandwiched between the optoelectronic ceramic phosphor element and the metal heat sink to form an assembly; and

[0105] The assembly is heated to a soldering temperature effective to cause the solder pre-form to form a solder bond between the solderable metal stack and the metal heat sink.

[0106] Item 32. The method of Item 31, wherein the solder pre-form includes a flux coated on or mixed into the solder pre-form.

[0107] Item 33. The method of any one of items 31 to 32, wherein the solder preform comprises a lead / indium / silver solder alloy or a gold / tin solder alloy.

[0108] Item 34. A method of manufacturing a light-conversion device, comprising:

[0109] depositing a solderable metal stack on the backside of a phosphor element comprising one or more phosphors embedded in a solid matrix element; and

[0110] The phosphor element is attached to the metal heat sink by soldering the solderable metal stack to the heat sink.

[0111] Item 35. The method according to Item 34, further comprising:

[0112] A dielectric mirror coating is deposited on the back side of the phosphor element prior to depositing the solderable metal stack on the back side of the phosphor element, thereby depositing the solderable metal stack on the dielectric mirror coating.

[0113] Item 36. The method of any one of items 34 to 35, wherein depositing the solderable metal stack on the back side of the phosphor element comprises:

[0114] depositing a chromium layer or a titanium layer on the back side of the phosphor element or on a dielectric mirror coating provided on the back side of the phosphor element;

[0115] depositing a nickel layer on the chromium layer or the titanium layer; and

[0116] A silver layer, a platinum layer or a gold layer is deposited on the nickel layer.

[0117] Item 37. The method of any one of items 33 to 34, wherein depositing the solderable metal stack on the back side of the phosphor element comprises:

[0118] depositing a solderable silver layer, platinum layer or gold layer on the nickel layer;

[0119] The welding comprises welding the weldable silver layer, platinum layer or gold layer to the heat sink.

[0120] Item 38. The method according to any one of Items 33 to 34, wherein the attaching comprises:

[0121] disposing the phosphor element on the metal heat sink with a solder preform sandwiched between the phosphor element and the metal heat sink to form an assembly; and

[0122] The assembly is heated to a soldering temperature effective to cause the solder pre-form to form a solder bond between the solderable metal stack and the metal heat sink.

[0123] Item 39. The method of Item 38, wherein the solder pre-form includes a flux coated on or mixed into the solder pre-form.

Claims

1. A light conversion device comprising: A phosphor wheel comprising: an optoelectronic ceramic phosphor element comprising one or more phosphors embedded in a ceramic matrix; A metal radiator, which is a metal disk rotatable around its own central axis; a solder joint on the metal heat sink for attaching the photovoltaic ceramic phosphor element to an outer edge of the metal heat sink; a solderable metal stack comprising more than one metal layer, at least one metal layer comprising a solderable metal layer, the solderable metal stack being on a back side of the optoelectronic ceramic phosphor element between the optoelectronic ceramic phosphor element and the solder bond; and a mirror coating located on a back side of the optoelectronic ceramic phosphor element between the optoelectronic ceramic phosphor element and the solderable metal stack, the mirror coating being a dielectric mirror designed for use with an air interface having a refractive index of 1 on the back side; wherein the weldable metal stack is located on the mirror coating between the mirror coating and the weld joint, The metal heat sink is attached to the solderable metal stack via the solder joint on the outer edge of the metal heat sink.

2. The light conversion device of claim 1 , wherein the solderable metal layer is composed of gold, silver, platinum, or another metal or metal sub-stack compatible with soldering, and the solderable metal stack further comprises one of the following stacks: a diffusion barrier layer between the optoelectronic ceramic phosphor element and the solderable metal layer; an adhesive layer between the optoelectronic ceramic phosphor element and the solderable metal layer; and, An adhesive layer and a diffusion barrier layer, wherein the adhesive layer is adjacent to the optoelectronic ceramic phosphor element, the diffusion barrier layer is located between the adhesive layer and the solderable metal layer, the solder bond being attached to the solderable metal layer.

3. The light conversion device according to claim 2, wherein: The diffusion barrier layer comprises nickel; The bonding layer comprises chromium or titanium or titanium-tungsten alloy; or The structure consisting of the adhesion layer, the diffusion barrier layer and the solderable metal layer comprises one of the following stacks: a chromium / nickel / gold layer stack, wherein the solder bond is attached to the gold layer; a titanium / nickel / gold layer stack, wherein the solder bond is attached to the gold layer; a chromium / nickel / silver layer stack, wherein the solder bond is attached to the silver layer; and Titanium / nickel / silver layer stack, wherein the solder bond is attached to the silver layer. The light conversion device of claim 3 , wherein the diffusion barrier layer comprising nickel further comprises vanadium. 5 . The light conversion device according to claim 1 , wherein the solder joint is formed from a solder preform comprising a flux coated on or mixed into the solder preform. 6 . The light conversion device of claim 5 , wherein the solder preform comprises a lead / indium / silver solder alloy, a gold / tin solder alloy, or a gold-silicon alloy.

7. The light conversion device according to any one of claims 1 to 4, further comprising an anti-reflection coating located in front of the opto-ceramic phosphor element. 8 . The light conversion device according to claim 1 , wherein the metal heat sink comprises a recess, and the solder joint is disposed within the recess.

9. The light conversion device of claim 8, wherein a lower portion of the optoelectronic ceramic phosphor element is also disposed within the recess of the metal heat sink.

10. The light conversion device of any one of claims 1 to 4, wherein the optoelectronic ceramic phosphor element does not crack in response to an applied light beam having an energy effective to heat the optoelectronic ceramic phosphor element to a phosphor quenching point.

11. A light generator comprising: The light conversion device according to any one of claims 1 to 10; as well as a light source arranged to apply a light beam to the light conversion device; The opto-ceramic phosphor element is responsive to a beam of light applied by the light source having an energy level effective to heat the opto-ceramic phosphor element to a quenching point of the phosphor without cracking.

12. A light conversion device comprising: A phosphor wheel comprising: a phosphor element comprising one or more phosphors embedded in a solid matrix element; A metal heat sink, which is a metal disk rotatable around a central axis; a solder joint on the metal heat sink for attaching the phosphor element to an outer edge of the metal heat sink; a solderable metal stack comprising more than one metal layer, at least one metal layer comprising a solderable metal layer, the solderable metal stack being on a back side of the phosphor element between the phosphor element and the solder bond; and a mirror coating located on a back side of the phosphor element between the phosphor element and the solderable metal stack, the mirror coating being a dielectric mirror designed for a back side that is an air interface with a refractive index equal to 1; wherein the weldable metal stack is located on the mirror coating between the mirror coating and the weld joint, The metal heat sink is attached to the solderable metal stack via the solder joint on the outer edge of the metal heat sink.

13. The light conversion device of claim 12, wherein the solderable metal layer is composed of gold, silver, platinum, or another metal or metal sub-stack compatible with soldering, the solderable metal stack further comprising one of the following stacks: a diffusion barrier layer between the phosphor element and the solderable metal layer; an adhesive layer between the phosphor element and the solderable metal layer; as well as, An adhesive layer and a diffusion barrier layer, wherein the adhesive layer is adjacent to the phosphor element, the diffusion barrier layer is located between the adhesive layer and the solderable metal layer, the solder bond being attached to the solderable metal layer.

14. The light conversion device according to claim 13, wherein: The weldable metal stack comprises one of the following: The diffusion barrier layer comprises nickel; The bonding layer comprises chromium or titanium or titanium-tungsten alloy; or The structure consisting of the adhesion layer, the diffusion barrier layer and the solderable metal layer comprises one of the following stacks: a chromium / nickel / gold layer stack, wherein the solder bond is attached to the gold layer; a titanium / nickel / gold layer stack, wherein the solder bond is attached to the gold layer; a chromium / nickel / silver layer stack, wherein the solder bond is attached to the silver layer; and Titanium / nickel / silver layer stack, wherein the solder bond is attached to the silver layer. The light conversion device of claim 14 , wherein the diffusion barrier layer comprising nickel further comprises vanadium.

16. The light conversion device of any one of claims 12 to 15, wherein the solder joint is formed from a solder pre-form comprising a flux coated on or mixed into the solder pre-form. 17 . The light conversion device of claim 16 , wherein the solder preform comprises a lead / indium / silver solder alloy, a gold / tin solder alloy, or a gold-silicon alloy. 18 . The light conversion device according to claim 12 , wherein the metal heat sink comprises a recess, and the solder joint is disposed within the recess.

19. The light conversion device of claim 18, wherein a lower portion of the phosphor element is also disposed within the recess of the metal heat sink.

20. The light conversion device of any one of claims 12 to 15, wherein the phosphor element comprises one or more phosphors embedded in a solid glass matrix element.

21. The light conversion device according to any one of claims 12 to 15, wherein the light conversion device further comprises: An anti-reflective coating is located in front of the phosphor element.

22. A light generator comprising: The light conversion device according to any one of claims 12 to 21; as well as a light source arranged to apply a light beam to the light conversion device; The phosphor element does not crack in response to the light source applying a beam of energy to the beam effective to heat the phosphor element to a quenching point of the phosphor.

23. A method of manufacturing a light conversion device, comprising: depositing a solderable metal stack comprising more than one metal layer, at least one metal layer comprising a solderable metal layer, on a back side of an optoelectronic ceramic phosphor element of a phosphor wheel, the optoelectronic ceramic phosphor element comprising one or more phosphors embedded in a ceramic matrix; depositing a dielectric mirror coating on the back side of the optoelectronic ceramic phosphor element before depositing the solderable metal stack on the back side of the optoelectronic ceramic phosphor element, whereby the solderable metal stack is deposited on the dielectric mirror coating, the mirror coating being a dielectric mirror designed for a back side that is an air interface with a refractive index equal to 1; Providing a metal heat sink, wherein the metal heat sink is a metal disk rotatable about its own central axis; as well as attaching the optoelectronic ceramic phosphor element to the outer edge of the metal disk by welding the weldable metal stack to the outer edge of the metal disk, wherein depositing the solderable metal stack on the back side of the optoelectronic ceramic phosphor element comprises one of: depositing an adhesion layer on the dielectric mirror coating on the back side of the optoelectronic ceramic phosphor element and depositing the solderable metal layer on the adhesion layer; depositing a diffusion barrier layer on the dielectric mirror coating on the back side of the optoelectronic ceramic phosphor element and depositing the solderable metal layer on the diffusion barrier layer; An adhesion layer is deposited on the dielectric mirror coating on the back side of the optoelectronic ceramic phosphor element, a diffusion barrier layer is deposited on the adhesion layer, and the solderable metal layer is deposited on the diffusion barrier layer.

24. The method according to claim 23, further comprising: An antireflective coating is deposited on the front face of the optoelectronic ceramic phosphor element.

25. The method of any one of claims 23 to 24, wherein depositing the solderable metal stack on the back side of the optoelectronic ceramic phosphor element comprises: depositing the adhesion layer on the dielectric mirror coating on the back side of the optoelectronic ceramic phosphor element, the adhesion layer comprising chromium or titanium or a titanium-tungsten alloy; depositing the diffusion barrier layer on the adhesion layer or on the dielectric mirror coating on the back side of the optoelectronic ceramic phosphor element, the diffusion barrier layer comprising nickel; and The solderable metal layer is deposited on the adhesion layer or the diffusion barrier layer, the solderable metal layer consisting of gold, silver, platinum or another metal or metal sub-stack compatible with soldering, and the solderable metal layer is soldered to the metal heat sink.

26. The method of claim 25, wherein the diffusion barrier layer comprising nickel further comprises vanadium.

27. The method of claim 25, wherein depositing the solderable metal stack on the back side of the optoelectronic ceramic phosphor element comprises: depositing the solderable metal layer comprising a solderable silver layer, platinum layer or gold layer on the diffusion barrier layer comprising a nickel layer; The welding comprises welding the weldable silver layer, platinum layer or gold layer to the metal heat sink.

28. The method of claim 25, wherein the attaching comprises: placing the optoelectronic ceramic phosphor element on the metal heat sink, wherein a solder preform is sandwiched between the optoelectronic ceramic phosphor element and the metal heat sink to form an assembly, the solder preform including a flux coated on or mixed into the solder preform; as well as The assembly is heated to a soldering temperature effective to cause the solder pre-form to form a solder bond between the solderable metal stack and the metal heat sink.

29. The method of claim 28, wherein the solder preform comprises a lead / indium / silver solder alloy or a gold / tin solder alloy.

30. A method of manufacturing a light conversion device, comprising: depositing a solderable metal stack comprising more than one metal layer, at least one metal layer comprising a solderable metal layer, on a backside of a phosphor element of a phosphor wheel, the phosphor element comprising one or more phosphors embedded in a ceramic matrix; depositing a dielectric mirror coating on the back side of the phosphor element before depositing the solderable metal stack on the back side of the phosphor element, whereby the solderable metal stack is deposited on the dielectric mirror coating, the mirror coating being a dielectric mirror designed for a back side that is an air interface having a refractive index equal to 1; Providing a metal heat sink, wherein the metal heat sink is a metal disk rotatable about its own central axis; as well as attaching the phosphor element to the outer edge of the metal disk by welding the weldable metal stack to the outer edge of the metal disk, wherein depositing the solderable metal stack on the back side of the phosphor element comprises one of: depositing an adhesion layer on the dielectric mirror coating on the back side of the phosphor element and depositing the solderable metal layer on the adhesion layer; depositing a diffusion barrier layer on the dielectric mirror coating on the back side of the phosphor element and depositing the solderable metal layer on the diffusion barrier layer; An adhesion layer is deposited on the dielectric mirror coating on the back side of the phosphor element, a diffusion barrier layer is deposited on the adhesion layer, and the solderable metal layer is deposited on the diffusion barrier layer.

31. The method of claim 30, further comprising: An anti-reflective coating is deposited in front of the phosphor element.

32. The method of any one of claims 30 to 31 , wherein depositing the solderable metal stack on the back side of the phosphor element comprises: depositing the adhesion layer on the dielectric mirror coating on the back side of the phosphor element, the adhesion layer comprising chromium or titanium or a titanium-tungsten alloy; depositing the diffusion barrier layer on the adhesion layer or on the dielectric mirror coating on the back side of the phosphor element, the diffusion barrier layer comprising nickel; and The solderable metal layer is deposited on the adhesion layer or the diffusion barrier layer, the solderable metal layer consisting of gold, silver, platinum or another metal or metal sub-stack compatible with soldering, and the solderable metal layer is soldered to the metal heat sink.

33. The method of claim 32, wherein the diffusion barrier layer comprising nickel further comprises vanadium.

34. The method of claim 32, wherein depositing the solderable metal stack on the back side of the phosphor element comprises: depositing the solderable metal layer comprising a solderable silver layer, platinum layer or gold layer on the diffusion barrier layer comprising a nickel layer; The welding comprises welding the weldable silver layer, platinum layer or gold layer to the metal heat sink.

35. The method of claim 32, wherein the attaching comprises: disposing the phosphor element on the metal heat sink, wherein a solder preform is sandwiched between the phosphor element and the metal heat sink to form an assembly, the solder preform including a flux coated on or mixed into the solder preform; as well as The assembly is heated to a soldering temperature effective to cause the solder pre-form to form a solder bond between the solderable metal stack and the metal heat sink.

36. The method of claim 35, wherein the solder preform comprises a lead / indium / silver solder alloy or a gold / tin solder alloy.

Images