HK1158826A - Phosphor-converted led - Google Patents

Description

Phosphor converted light emitting diode

Background

Light Emitting Diodes (LEDs) are an excellent alternative to conventional Light sources such as incandescent and fluorescent Light sources, LEDs having substantially higher luminous efficiency and longer lifetime than incandescent lamps. In addition, some LEDs have higher luminous efficiency than fluorescent light sources, and LEDs with higher luminous efficiency have been proved by experiments. Finally, LEDs require lower voltages than fluorescent lamps and are therefore more suitable for use in light source applications powered by low voltage power sources such as batteries or computer internal dc power sources.

Unfortunately, LEDs produce light in a relatively narrow band. In order to replace conventional lighting systems, a light source consisting of LEDs is required, which emits light that appears "white" to a person. By using a phosphor layer covering the blue LED, a light source exhibiting white color and having a luminous efficiency comparable to that of a fluorescent lamp can be constructed by converting a part of blue light into yellow light through the phosphor layer. Such a light source is referred to as a "phosphor converted" light source in the following discussion. If the ratio of blue to yellow is chosen correctly, the resulting light source will appear white to a person. In order to provide the correct ratio, the thickness of the phosphor layer must be controlled. In addition, the uniformity of the phosphor layer on the die (die) from which the LED is fabricated must be maintained to avoid color variations of the light on the light emitting surface of the light source.

Cost (measured in lumens per money) is an important factor in any light source that is intended to replace a traditional light source. The package cost of the die is an important part of the final light source cost. The packaging cost is increased because of the need to extract the light that exits the sides of the die. Most of the light generated by blue LEDs used in phosphor converted light sources is trapped between the top and bottom surfaces of the die due to total reflection caused by the difference in refractive index between the die fabrication material and the surrounding medium. Most of this trapped light leaves the die through the die side. To improve the light output of the die, a reflector plate is typically included in the light source to redirect light exiting the sides of the die so that it exits the die in the same direction as light exiting the top surface of the die.

The packaging costs associated with providing a uniform phosphor thickness and reflector plate are considerable. For example: in one design, the reflector plate is provided in the form of a cup having a reflector wall. The cup is mounted on a substrate that contains the die power supply circuitry. A portion of the substrate is exposed through an opening in the bottom of the cup. The die is mounted on the portion of the substrate exposed through the bottom of the cup and connected to the electrical lines. The cup is then filled with a material having phosphor particles suspended therein, which provides a solid layer that is curable so that the phosphor particles can remain suspended. The process of suspending the phosphor particles with an epoxy or silicone material is well known in the art.

These processes are difficult to automate and automated processes can ensure that the light emitted from the die is uniform. In particular, the portion of the light exiting the top surface of the die converted by the phosphor layer must be the same as the portion of the light exiting the side surface of the die converted by the phosphor layer. In these processes, the phosphor layer is formed in the cup during the final assembly of the light source on the light source assembly line by curing a carrier material containing the phosphor particles. The phosphor particles tend to settle within the carrier material during the distribution stage. To avoid sedimentation, the suspension must be supplemented with a number of materials that slow down sedimentation. In addition, the carrier must be formulated so that it solidifies in a short time to avoid the particles settling around the grains in the cup. If the particles settle at the bottom of the cup, the amount of phosphor that light leaving the sides of the die must pass through is significantly different from the amount of phosphor that light leaving the top of the die must pass through. As a result, the light redirected by the reflector plate has a different color than the light leaving the top surface of the die. Thus, the color presented by the light source on the surface is not uniform.

Furthermore, the process of providing individual cups for each die typically involves many additional manufacturing steps. In the simplest design, the cup is separately secured to the substrate below it after manufacture. Although designs have been proposed that place cups made using a single layer of material over several dies, the manufacture of the "cup layer" still represents a significant portion of the cost of the final light source.

Disclosure of Invention

The invention includes a light source and a method of manufacturing the light source. The light source includes a die, a light conversion element and a scattering ring. The die emits light of a first wavelength through a top surface of the die and one or more side surfaces of the die, the die being bonded to a surface of a mounting substrate. The light conversion element includes a layer of luminescent material that converts light of the first wavelength to light of the second wavelength, the light conversion element having a bottom surface bonded to the top surface of the die. The light conversion element has lateral dimensions such that a space is present around the die, the space being defined by the substrate and the light conversion element. The scattering ring surrounds the side surface of the die and is disposed in the space such that a portion of light emitted from the side surface of the die is scattered by the scattering ring into the light conversion element. In one aspect of the invention, the scattering ring comprises a transparent material having suspended particles therein. In another aspect of the invention, the light conversion element comprises a planar layer of transparent material having a light emitting material therein. The light conversion element further includes a light management layer comprising a layer of transparent material bonded to the planar layer, the light management layer having a non-planar surface overlying the planar layer.

The light source may be fabricated as a group of light sources in which a plurality of dies emit light at a first wavelength through a top surface of the die and one or more side surfaces of the die, the dies being bonded to a surface of a mounting substrate. A sheet of light conversion elements is disposed on the mounting substrate, each light conversion element including a layer of luminescent material that converts light of the first wavelength to light of the second wavelength. Each light conversion element corresponds to one of the dies and is aligned with the die such that a bottom surface of the light conversion element is disposed above a top surface of the die. The sheet of light conversion elements is then bonded to the top surface of the die. The light conversion element has lateral dimensions selected such that a space is present around the corresponding die, the space being defined by the substrate and the corresponding light conversion element. A scattering ring is then created around the sides of each die. The scattering ring is disposed in the space surrounding the die, so that a portion of light emitted from the side surface of the die is scattered by the scattering ring into the light conversion element corresponding to the die. In one aspect of the invention, the scattering ring comprises a transparent material having suspended particles therein. The transparent material has a liquid precursor that wets the bottom surface of the light conversion element and the substrate surface. The scattering ring is generated in the following way: suspending the scattering particles in the liquid precursor to form a liquid ring precursor, introducing the liquid ring precursor into the space around the grains, and solidifying the liquid ring precursor to form a transparent medium suspending the scattering particles. In other aspects of the invention, the liquid precursor is drawn into the space by capillary phenomenon.

Drawings

FIG. 1 is a cross-sectional view of a conventional phosphor converted LED light source;

FIG. 2 is a cross-sectional view of a light source according to one aspect of the present invention;

FIGS. 3-4 are cross-sectional views of a light source at various stages in the process according to one aspect of the present invention;

FIG. 5 is a cross-sectional view taken along line 5-5 of FIG. 6;

FIG. 6 is a top view of a portion of the substrate shown in FIG. 5;

FIG. 7 is a cross-sectional view of a portion of a substrate 71 having two light sources using this aspect of the invention;

FIGS. 8 and 9 illustrate a light source using another aspect of the present invention;

fig. 10 and 11 illustrate a light source using another aspect of the present invention.

Detailed Description

The advantages provided by the present invention can be more readily understood by reference to FIG. 1, which is a cross-sectional view of a typical phosphor converted LED light source 20 of the prior art. A light emitting semiconductor die 22 is mounted in a cavity on a substrate 21, the die 22 comprising an LED. The LED is powered by the contacts on the bottom of the die 22 and corresponding conductors on the substrate. The connection of die 22 to conductors on substrate 21 has been omitted to simplify the drawing.

The light source 20 comprises a cup 29 having a reflective side 27. Cup 29 may be manufactured by making a conical hole in the material layer and then bonding to substrate 21 after coating the inner wall of the hole with a reflective material. The cup is typically bonded to substrate 21 before die 22 is attached to substrate 21. However, embodiments are also known in which the cup is created by digging a conical recess in the base plate 21.

Suspended phosphor particles 24 in carrier material 25 are introduced into cup 29 after die 22 is bonded to substrate 21. The carrier material is typically an epoxy or silicone; however, the use of carriers of other materials is also known in the art. The carrier is typically cured to produce a solid material that holds the phosphor particles therein. Even if the phosphor particles are uniformly distributed within the carrier material when the carrier is cured, the amount of phosphor that passes light 28 exiting from the sides of the die 22 is different than the amount that passes light 26 exiting from the top surface of the die. Generally, more of the light exiting the sides of the die is converted to yellow than the light exiting the top surface of the die. Thus, the light reflected from the inner wall of the cup has its wavelength shifted towards yellow, resulting in a circular light source with a white center and a yellow halo appearing as the light source.

Further, the uniformity of the light source between devices depends on the accuracy of the distribution of the carrier material into each cup and the concentration of phosphors in the carrier. In this respect, it has to be noted that the phosphors in the distribution groove may precipitate when manufacturing several light sources, and therefore the concentration of the phosphors in the carrier cannot be kept constant during the distribution of the carrier material into several light sources.

Now referring to fig. 2, a cross-sectional view of a light source according to one aspect of the invention is shown. The light source 30 includes a die 31 having an LED that emits light through the top surface of the die 31 and through the side surfaces of the die 31. Die 31 is bonded to substrate 32 using contacts on the bottom surface of die 31. To simplify the drawing, the electrical connection between the die 31 and the substrate has been omitted from the drawing.

A phosphor layer 33 is bonded to the top surface of die 31 with an adhesive layer 36. The fluorescent layer 33 converts a part of the light emitted from the crystal grains 31 into light having a different spectrum from the light emitted from the crystal grains 31. As mentioned above, a white light source can be created by using grains that emit in the blue spectrum and a phosphor that can convert blue light to yellow light. However, other combinations of grains and phosphors may be used to practice the invention. As described in more detail below, layer 33 is prefabricated prior to bonding layer 33 to die 31. The fluorescent layer 33 may include dispersed phosphor particles suspended in a carrier or be made of a soluble phosphor dissolved in a carrier.

Light leaving the sides of the die 31 is scattered by a layer 35 of scattering particles suspended in a layer 34 of material transparent to the light generated by the die 31. Material layer 34 forms a scattering ring around the sides of die 31 and fills the gap between substrate 32 and layer 33 in the region adjacent die 31. The thickness of the scattering ring can be chosen such that the amount of light exiting the die through the side faces and emanating from surface 38 is negligible compared to the light exiting through the top face of phosphor layer 33 in the light source. In one aspect of the invention, the amount of light exiting the sides of the die 31 and passing through the layer 38 from the light source 30 is less than 10% of the light exiting the sides of the die and passing through the side 38 of the scattering ring.

The top surface 37 of the substrate 32 may be covered with a reflective material to redirect any light scattered toward the substrate 32 back toward the phosphor layer 33. The scattering particles replace the conventional reflective plates discussed above. Consider light exiting from the sides of die 31 that is scattered such that the light is redirected toward phosphor layer 33. This light and the light emitted from the top surface of the die 31 pass through the same phosphor thickness; the light source has a more uniform light field than the prior art light sources discussed above. In addition, the overall horizontal dimension of the light source is significantly smaller than light sources using individual reflective plates.

As explained in more detail below, the height h of material layer 34 may be set such that material layer 34 may be fabricated by introducing a liquid precursor suspending scattering particles therein between phosphor layer 33 and substrate 32 after phosphor layer 33 is bonded to die 31. This aspect of the invention determines that the carrier and the scattering particles are confined under the fluorescent layer 33. The width of the scattering layer is not critical as long as the width is greater than the minimum width. The width must be wide enough to ensure that most of the light exiting from the sides of the die 31 is reflected. Furthermore, the width must be larger than the wavelength of the light redirected by the scattering particles. If other materials are present, the apparent size or color of the light source is not substantially changed, since most of the light is already scattered before reaching the other materials. Therefore, it is not necessary to precisely control the amount of material to be distributed at the edges of the phosphor layer 33.

It has to be noted that any variation of the scattering particle density changes the light field diameter of the light source and the brightness distribution of the edges; the color of the light source does not change, however, because the thickness of the phosphor through which the light passes is independent of the scattering medium. Since the eye is more sensitive to color differences than to differences in brightness, small differences in brightness on the edges are generally acceptable.

The manner in which a light source according to one aspect of the present invention may be manufactured may be better understood with reference to fig. 3-6, which illustrate how several such light sources may be manufactured. Fig. 3-5 are cross-sectional views of a portion of a substrate 41 at various stages in the process. Fig. 6 is a top view of a portion of the substrate 41 shown in fig. 5, and fig. 5 is a cross-sectional view through line 5-5 shown in fig. 6.

Referring to fig. 3, the process begins by bonding a plurality of dies, such as die 42, to substrate 41. The die is connected to an electric line on the surface of the substrate 41, and light is emitted from the side of the die and the opposite side with respect to the substrate 41. The light emitting surface is covered by an adhesive layer 45 which is transparent to the light emitted by the die after the adhesive has cured.

The phosphor layers are pre-fabricated to form individual phosphor elements 43 that can be reverse bonded to a carrier substrate 44. In one aspect of the invention, the phosphor elements may be cast as a sheet of material that is divided into individual phosphor elements that are later secured to the substrate 44. In other aspects of the invention, a liquid precursor material having the phosphor is applied to the substrate 44 as a patterned layer having individual phosphor elements disposed just above the substrate 44. The pre-reactants may be distributed using a "printing operation" such as a stencil process, or using a mechanism similar to that used in ink jet printers. The precursor material is then cured to provide the phosphor element discussed above.

The phosphor elements are positioned such that when the carrier substrate 44 is properly aligned with the substrate 41, one phosphor element will be located exactly on each die. After both substrates 41 and 44 are properly aligned with each other, the substrates are pressed together so that the phosphor element is in contact with the adhesive layer. The adhesive layer is then cured to provide bonding between each phosphor element and the corresponding die. After the adhesive layer is cured, the substrate 44 is removed leaving the light source as shown in fig. 4.

Referring now to fig. 5 and 6, after the phosphor elements have been bonded to the die, a scattering layer 48 is formed by distributing an appropriate liquid precursor in the spaces between the phosphor elements. The liquid precursor contains the scattering particles and has a desired surface tension so that the liquid is drawn into the space between the phosphor element and the substrate 41 by capillary phenomenon. The liquid may be distributed by a single nozzle 47 interposed between a pair of phosphor elements, such as the phosphor elements 45 and 46 shown in fig. 5 and 6. In addition, multiple nozzles may be used to simultaneously distribute the precursor and the scattering particle suspension.

The liquid precursor must be maintained in a liquid state until it is absorbed into the space between the phosphor element and the substrate 41. The liquid precursor may be any material that hardens into a transparent medium and maintains the scattering particles in suspension. The medium must be transparent to the light emitted by the die. The compositions discussed above for distributing the phosphor layer into the reflective cup while maintaining the phosphor particles in suspension can be used herein. Such compositions typically comprise a carrier with various additives that slow down the precipitation of particles. For example: a transparent epoxy resin composition that is cured using heat or UV light may be used. Silicone compositions may also be utilized.

In one aspect of the invention, the scattering particles are titanium oxide particles having a diameter greater than the wavelength of light emitted by the grains. However, other materials may be used. For example: colorless particles may be used having a refractive index significantly different from the refractive index of the medium in which the particles are suspended. For example, glass particles suspended in epoxy resin may be utilized.

The phosphor element can be fabricated in several ways and the phosphor element can be pre-molded from the same materials used to fabricate the phosphor layer in the prior art methods discussed above. Since the phosphor elements are manufactured using separate molding processes, the problems discussed above with respect to providing a uniform layer are substantially reduced. As described above, the phosphor element can also be manufactured by printing the phosphor material onto a carrier.

The phosphor element has to maintain a certain uniformity of phosphor particles in the horizontal direction so that light leaving the top surface of the die or leaving the scattering particles will pass through the same thickness of phosphor material. However, unlike prior art elements, the vertical distribution of phosphor particles within the phosphor element can be substantially non-uniform, since most of the light converted by the phosphor is relatively independent of the phosphor particle distribution within the layer. Thus, if the phosphor element is provided using a molding process, the molding process does not require a curing time that is shorter than the settling time of the particles in a carrier used to suspend the particles. Similarly, if the phosphor is distributed on the carrier using a stencil or printing process, the proportion of converted light is determined mainly by the amount of the applied phosphor, unlike the vertical distribution of the phosphor within the layer. Finally, the preparation of the carrier with the phosphor elements can be separated from the encapsulation process, so that the process can be individually optimized.

The above-described example of a light source according to various aspects of the present invention uses a manufacturing method that provides individual phosphor elements on a carrier, which is then transferred to the dice. In some applications, it may be preferable to include additional optical elements on the phosphor layer for reducing the amount of light left in the phosphor layer due to total reflection. Total reflection occurs at the boundary between the phosphor element and the air surrounding the finished light source. These optical elements need to have a curved design which complicates the bonding of the individual phosphor elements to the carrier.

In one aspect of the invention, these problems are substantially reduced by bonding a plate of the phosphor element prefabricated with the optical element to the dice on the die carrier. The scattering material is then introduced into the space between the grains and the phosphor element as discussed above. Finally, the phosphor plate is cut at the same time as the die and the die carrier are cut to provide a finished LED.

It has to be noted that the optical element can also be manufactured by molding one dome on each finished light source. Now referring to FIG. 7, a cross-sectional view of a portion of a substrate 71 having two light sources using this aspect of the invention is shown. Each light source includes a dome 72 molded into each light source over the phosphor element 73. The diameter of the dome 72 is selected such that light entering the dome 72 from the phosphor element 73 will strike the surface of the dome 72 at an angle of incidence less than the critical angle of the dome 72, and thus, this light will exit the dome 72 without being trapped within the dome 72 by internal reflection at the air/dome interface. To reduce manufacturing costs, the dome of the entire light source board may be molded in a single molding operation before cutting individual light sources.

The above example uses a phosphor conversion layer fabricated by suspending phosphor particles in a transparent medium. However, other methods may be used to manufacture the phosphor element. For example: a phosphor conversion layer made of a single crystal semiconductor material possessing fluorescent properties due to appropriate doping may be used for the phosphor conversion layer.

The single crystal phosphor can be grown by a bulk crystal growth method such as a Czochralsky method or an epitaxial method such as liquid phase or vapor phase epitaxy. For example: U.S. patent No. 4,873,062, published 10/10 1989, describes an apparatus and method for growing single crystals using this method. Since this method is well known in the semiconductor material industry, it will not be discussed further here. For purposes of discussion, it is sufficient to note that the growth of single crystal phosphor utilizes a single seed crystal lowered into a crucible having melted phosphor material. As the crystal grows, a bulk crystal is pulled from the molten material. The crystalline bulk is then cut into thin sheet layers and cut or broken into smaller pieces to be suitable for use in the present invention. The thickness of this layer depends on the particular application, and is between 0.05 and 5mm, with 0.25mm being preferred in many applications.

When the single crystal phosphor layer is transparent, light transmission is not hindered by scattering at the phosphor particle boundaries. Since the light conversion fluorescent layer has a uniform thickness, the color conversion effect is the same over the entire surface.

The choice of crystalline material is based on the particular application. For white LEDs, the LED emits light in a first frequency band, and the light conversion layer converts a portion of that light to light in a complementary frequency band. For example: white LEDs may use a single crystal phosphor comprising cerium-activated Yttrium Aluminum Garnet (Yttrium Aluminum Garnet) YAG: Ce to convert blue light emitted by their LEDs to yellow light. Similarly, an LED emitting indigo (blue-green) can be matched to a single crystal phosphor emitting red light to provide a near white light source.

It has to be noted that also a plurality of phosphor layers may be used. For example: if UV emitting LEDs are used, at least two phosphors are required to provide a light source that appears white to an observer. In this case, the phosphor layer may comprise two different phosphor layers, one for each phosphor. Each phosphor layer converts a portion of the UV light. To provide maximum efficiency, all UV light should be converted by the combination of phosphors.

Light sources using different color LEDs are also used to produce light that appears to a viewer as a particular color. For example: light sources using three LEDs, each LED producing a different color of light, e.g., red, green, and blue, are used. The light source is typically used to provide a light source that can be designed to provide a specific color of viewing light, which can be selected from a wide color gamut. By changing the brightness ratio of the three primary color light sources, the observed color of the light sources can be changed. It is also prior art to use more light sources of different colors. Such light sources have a large color gamut that can be produced by varying the brightness of the individual LEDs. Now referring to fig. 8 and 9, a light source using this aspect of the invention is illustrated. Fig. 9 is a top view of the light source 90, and fig. 8 is a cross-sectional view of the light source 90 through line 8-8 of fig. 8. Light source 90 comprises 4 dies, shown as 82-85. Each grain is covered by a phosphor element using a different phosphor. Exemplary phosphor elements are labeled 92 and 93 in the drawings. Four dies are covered by a common dome 95 in a manner similar to that discussed above.

To provide the appearance of a "point" light source of a desired color, the LEDs must be as close to each other as possible. The present invention may also be adapted to make such a light source because the dies may be closer together than the dies in a light source where each die is in a separate reflector cup.

In such light sources, different phosphors are used to make phosphor elements that cover adjacent grains in the light source plate. Suitable for such light sources according to the manufacturing technique of printing or stencil-molding the phosphor onto the carrier. After the light sources are manufactured, the panel is divided so that three or four dies having corresponding phosphor elements are included in each light source.

Another problem faced by LED light sources is the relatively low light output of the individual LEDs. Currently, a single die can operate at a maximum of several watts of power. Therefore, in order to provide a light source that replaces a conventional incandescent lamp, several dies must be combined to provide a desired brightness even when the light sources are the same color. Likewise, the present invention is suitable for making a multi-grain light source sufficient to be a point light source. Now referring to fig. 10 and 11, a light source 100 using this aspect of the invention is illustrated. Fig. 11 is a top view of light source 100, and fig. 10 is a cross-sectional view of light source 100 through line 10-10 in fig. 10. The light source 100 uses 4 dies sharing a phosphor element 102. Exemplary dies are labeled 103 and 104 within the drawing. The grains and the phosphor element are encapsulated within the dome 105 to provide enhanced light extraction. The scattering medium, which redirects the light leaving the sides of the dies, is directed into the locations shown as 111 and 114 and moves to the regions between the dies through capillary phenomenon. Thus, the dies can be as close to each other as possible without losing light emitted through the sides of the dies.

As mentioned above, the phosphor element is preferably manufactured using different processes, such as rotary molding, injection molding, printing or casting. In one aspect of the invention, the phosphor is mixed with a transparent medium such as epoxy, silicone, polycarbonate, acrylic, polyurethane, polypropylene, or similar plastic or polymer, and then formed into the desired shape using molding, casting, printing, or other suitable processes. Inorganic glasses with low melting points may also be used as the transparent medium.

The phosphor is preferably a material that does not present scattering problems. To reduce scattering of light within a light source using particles of inorganic phosphor suspended in a transparent medium, the particle size is preferably less than or equal to the wavelength of light emitted by the LED on the die. In addition, a luminescent material that is soluble in the transparent medium may be used, such as: an organic light emitting material such as a phosphor dye may be used.

Scattering from the particle surface can also be reduced by appropriate selection of the transparent medium in which the particles are suspended. In particular, a material having a refractive index matching that of the phosphor material may be used, thereby reducing light scattering. For example: the low melting point glass can be used as a casting material to reduce the difference in refractive index between the phosphor particles and the casting material.

The above examples of the present invention have been disclosed to create a light source that appears "white" to a viewer. However, the invention can be used to produce other light sources that operate by converting a portion of the light emitted by the primary light source using a phosphor.

The above-described light source example according to the present invention is to convert light emitted from an LED into light of a different wavelength using a phosphor. However, other forms of luminescent material may be used. In general, any material that converts light of the wavelength generated by the LED to light of the desired wavelength may be used.

The above-described example of a light source according to the invention relates to a number of transparent elements. For purposes of the present invention, a medium is defined as transparent if it allows more than ninety percent of the light generated by the LEDs within the light source to pass through.

Many modifications to the present invention will become apparent to those skilled in the art from the foregoing description and accompanying drawings. Accordingly, the invention is to be limited only by the scope of the following claims.

Claims (19)

1. A light source, comprising:

a die emitting light of a first wavelength through a top surface of the die and one or more side surfaces of the die, the die being bonded to a surface of a mounting substrate;

a light conversion element comprising a layer of luminescent material that converts light of the first wavelength to light of a second wavelength, the light conversion element having a bottom surface bonded to the top surface of the die, the light conversion element having lateral dimensions such that a space is present around the die, the space being defined by the substrate and the light conversion element; and

a scattering ring surrounding the side surface of the crystal grain and arranged in the space so that a part of the light emitted from the side surface of the crystal grain is scattered by the scattering ring into the light conversion element.

2. The light source of claim 1, wherein the scattering ring comprises a transparent material with particles suspended therein.

3. The light source of claim 1, wherein the transparent material has a liquid precursor wetting the bottom surface of the light conversion element and a surface of the substrate.

4. The light source of claim 2, wherein the transparent material comprises an epoxy.

5. The light source of claim 2, wherein the transparent material comprises silicone.

6. The light source of claim 2, wherein the particles comprise titanium oxide.

7. The light source of claim 1, wherein the light conversion element comprises a transparent material with phosphor particles suspended therein.

8. The light source of claim 1, wherein the light conversion element comprises a single crystal phosphor.

9. The light source of claim 1, wherein the light conversion element comprises a planar layer of transparent material having a light emitting material therein, the light conversion element further comprising a light management layer comprising a layer of transparent material bonded to the planar layer, the light management layer having a non-planar surface overlying the planar layer.

10. The light source of claim 1, further comprising a layer of transparent material over the mounting substrate shaped to provide an optical element having a non-planar surface corresponding to the die.

11. A method of manufacturing a light source, comprising:

mounting a plurality of dies that emit light of a first wavelength through a top surface and one or more side surfaces of the dies, the dies being bonded to a surface of a mounting substrate;

providing a sheet of light conversion elements, each light conversion element comprising a layer of luminescent material that converts light of the first wavelength to light of a second wavelength, each light conversion element corresponding to one of the dies and aligned with the die such that a bottom surface of the light conversion element is positioned on a top surface of the die;

bonding the sheet of light conversion elements to the top surfaces of the dies, wherein each light conversion element has lateral dimensions selected such that a space exists around the corresponding die, the space being defined by the substrate and the corresponding light conversion element; and

a scattering ring is generated, which surrounds the side surface of each crystal grain and is arranged in the space around the crystal grain, so that a part of the light emitted from the side surface of the crystal grain is scattered into the light conversion element corresponding to the crystal grain through the scattering ring.

12. The method of claim 11, wherein the scattering ring comprises a transparent material with scattering particles suspended therein.

13. The method of claim 12, wherein the transparent material has a liquid precursor that wets the bottom surface of the light conversion element and a surface of the substrate, the scattering ring is generated by suspending the scattering particles in the liquid precursor to form a liquid ring precursor, introducing the liquid ring precursor into the die surrounding space, and solidifying the liquid precursor.

14. The method of claim 13, wherein the liquid ring precursor is drawn into the space by capillary action.

15. The method of claim 11, wherein providing the sheet of light conversion elements comprises attaching individual light conversion elements to a carrier.

16. The method of claim 11, wherein providing the sheet of light conversion elements comprises creating a patterned phosphor layer on a carrier.

17. The method of claim 16, wherein the phosphor layer comprises a liquid precursor material comprising the phosphor, and the patterned phosphor layer is created by printing the liquid precursor material on the carrier.

18. The method of claim 11, further comprising molding a layer of transparent material over the mounting substrate to provide optical elements having a non-planar surface corresponding to each die.

19. The method of claim 18, wherein one of the optical elements comprises a plurality of the dies.