Reflectors for support structures in light-emitting diode packages

Abstract

A reflector for a support structure in a solid-state light emitting device including a light emitting diode (LED), particularly an LED package (48), is disclosed. The support structure includes a dielectric reflector (18) disposed relative to the LED chip (36) and conductive traces (14) patterned on a submount (12). The dielectric reflector includes a multiple dielectric layer structure forming a distributed Bragg reflector (DBR), or in some cases, an aperiodic Bragg reflector. Such a dielectric reflector (18) may be disposed over one or more of the conductive traces (14) and portions of the submount (12) not covered by the conductive traces, improving reflectivity across a range of wavelengths provided by the LED chip, including wavelengths in the ultraviolet (UV) spectrum. A cover structure (38) is further provided for each of the disclosed LED packages (34, 42, 44, 46, 48, 50, 52, 54, 56, 60, 62, 64).

Description

Technical Field

[0001]

[0001] The present invention relates to a solid-state light-emitting device including a light-emitting diode (LED), and more particularly to a reflector for a support structure in an LED package.

Background Art

[0002]

[0002] Solid-state light-emitting devices such as light-emitting diodes (LEDs) are increasingly being used in both consumer and commercial applications. Advancements in LED technology have enabled highly efficient, mechanically robust, and long-lasting light sources. Thus, modern LEDs are enabling a variety of new display applications and are increasingly being used for general lighting applications, frequently replacing incandescent and fluorescent light sources.

[0003]

[0003] An LED is a solid-state device that converts electrical energy into light and typically includes one or more active layers (or active regions) of semiconductor material disposed between oppositely doped n-type and p-type layers. When a bias is applied across the doped layers, holes and electrons are injected into one or more active layers where they recombine to generate light emission such as visible or ultraviolet light. An LED chip typically includes an active region that can be fabricated from, for example, silicon carbide, gallium nitride, gallium phosphide, aluminum nitride, gallium arsenide-based materials, and / or organic semiconductor materials. Photons generated by the active region travel in all directions.

[0004]

[0004] Typically, it is desirable to operate LEDs with the highest possible luminous efficiency, which can be measured by the luminous intensity as a percentage of the output power (e.g., lumens per watt). A practical goal for increasing luminous efficiency is to extract the light emitted by the active region to the maximum extent possible in the direction of desired light transmission. The light extraction and external quantum efficiency of an LED can be limited by several factors, including internal reflection. LED packages have been developed that can provide mechanical support, electrical connections, and encapsulation for LED emitters. The light emitted from the surface of the LED emitter can interact with elements or surfaces of the corresponding LED package, potentially increasing the chance of light loss. In addition, various operating conditions and wavelengths of emission can degrade various materials that have been conventionally used for LED packages. Therefore, there is a challenge in producing high-quality light with desirable emission characteristics while achieving high luminous efficiency in LED packages.

[0005]

[0005] In the art, there is a continuing demand for improved LEDs and solid-state light-emitting devices that have desirable illumination characteristics and can overcome the challenges associated with conventional light-emitting devices. [Overview of the project] [Means for solving the problem]

[0006]

[0006] The present invention relates to a solid-state light-emitting device including a light-emitting diode (LED), and more particularly to a reflector for a support structure in an LED package. The support structure includes the arrangement of a dielectric reflector on an LED chip and conductive traces patterned on a submount. The dielectric reflector includes a plurality of dielectric layer structures that form a distributed Bragg reflector, or optionally an aperiodic Bragg reflector. Such a dielectric reflector can be arranged on one or more conductive traces of the conductive traces and on a portion of the submount not covered by the conductive traces, and provides high reflectivity over a range of wavelengths provided by the LED chip, including wavelengths in the ultraviolet spectrum.

[0007]

[0007] In one embodiment, the LED package comprises a submount having a first surface and a second surface opposite to the first surface; at least one LED chip on the first surface of the submount; a cover structure positioned above the at least one LED chip; a patterned trace on the first surface of the submount, wherein the cover structure is mounted on the patterned trace in a cover structure mounting region outside at least one die mounting pad; and a dielectric reflector on a portion of the patterned trace between at least one die mounting pad and the cover structure mounting region, comprising a distributed Bragg reflector. In a particular embodiment, the distributed Bragg reflector is a nonperiodic distributed Bragg reflector. In a particular embodiment, the nonperiodic distributed Bragg reflector comprises a plurality of dielectric layers, each dielectric layer of the plurality of dielectric layers having an optical thickness unique to the other dielectric layers of the plurality of dielectric layers. In a particular embodiment, the plurality of dielectric layers comprises dielectric layers in which a first material type and a second material type alternate. In certain embodiments, there is an additional dielectric reflector on the portion of the submount not covered by the pattern trace and at least one LED chip. In certain embodiments, the dielectric reflector is further positioned between at least one LED chip and the submount in a gap formed by the pattern trace along at least one die mounting pad. In certain embodiments, at least one LED chip is configured to provide a peak wavelength in the range of 200 nm to 400 nm.

[0008]

[0008] In another embodiment, the LED package comprises a submount having a first surface and a second surface opposite to the first surface; at least one LED chip on the first surface of the submount; a cover structure disposed above the at least one LED chip and mounted on the submount in a cover structure mounting region spaced apart from the peripheral boundary of the at least one LED chip; a pattern trace on the first surface of the submount, forming at least one die mounting pad for the at least one LED chip; and a dielectric reflector on a portion of the submount laterally adjacent to the pattern trace, comprising a distributed Bragg reflector. In a particular embodiment, the dielectric reflector is further disposed on a portion of the pattern trace. In a particular embodiment, the dielectric reflector is further disposed between the cover structure and the submount in the cover structure mounting region. In a particular embodiment, the distributed Bragg reflector is a nonperiodic distributed Bragg reflector comprising a plurality of dielectric layers, each dielectric layer of the plurality of dielectric layers having an optical thickness unique to the other dielectric layers of the plurality of dielectric layers. In certain embodiments, the dielectric layers comprise dielectric layers in which a first material type and a second material type alternate. In certain embodiments, the dielectric layer having the greatest optical thickness among the dielectric layers is spaced apart from the upper surface of the aperiodic distributed Bragg reflector and located inside the aperiodic distributed Bragg reflector. In certain embodiments, at least one LED chip is configured to provide a peak wavelength in the range of 200 nm to 400 nm.

[0009]

[0009] In another embodiment, the LED package comprises a submount having a first surface and a second surface opposite to the first surface, at least one LED chip on the first surface of the submount, a pattern trace on the first surface of the submount, and a dielectric reflector having a distributed Bragg reflector on a portion of the pattern trace and on a portion of the submount laterally adjacent to the pattern trace. In a particular embodiment, the distributed Bragg reflector is a periodic distributed Bragg reflector. In a particular embodiment, the periodic distributed Bragg reflector comprises a plurality of dielectric layers, each dielectric layer having an optical thickness unique to the other dielectric layers of the plurality of dielectric layers. In a particular embodiment, the plurality of dielectric layers comprises dielectric layers in which a first material type and a second material type alternate. In a particular embodiment, the dielectric layer having the largest optical thickness among the plurality of dielectric layers is spaced apart from the upper surface of the periodic distributed Bragg reflector and located inside the periodic distributed Bragg reflector. In certain embodiments, the pattern trace comprises at least one die mounting pad for at least one LED chip, and a dielectric reflector is further disposed between the at least one LED chip and the submount in a gap formed by the pattern trace along the at least one die mounting pad. In certain embodiments, the at least one LED chip is configured to provide a peak wavelength in the range of 200 nm to 400 nm. The LED package may further comprise a cover structure disposed above the submount to form a cavity above the at least one LED chip. The LED package may further comprise a reflector structure disposed between the cover structure and the submount, with the sidewalls of the reflector structure enclosing a portion of the cavity. In certain embodiments, the dielectric reflector is disposed on the sidewalls of the reflector structure. In certain embodiments, the dielectric reflector is disposed between the reflector structure and the submount.

[0010]

[0010] In another embodiment, further advantages can be obtained by combining any of the above embodiments individually or together, and / or by combining various distinct embodiments and features described herein. Any of the various features and elements disclosed herein may be combined with one or more other disclosed features and elements unless otherwise indicated herein.

[0011]

[0011] Those skilled in the art will recognize the scope of the present disclosure and realize additional embodiments after reading the following detailed description of preferred embodiments in conjunction with the accompanying drawings.

[0012] The accompanying drawings incorporated herein and forming part thereof illustrate several aspects of this disclosure and, together with the description, are useful in illustrating the principles of this disclosure. [Brief explanation of the drawing]

[0012] [Figure 1]

[0013] This is a top view showing a portion of a light-emitting diode (LED) package, including a portion of a first pattern trace, collectively referred to herein as the first pattern trace, and a dielectric reflector, provided on a submount in accordance with the principles of this disclosure. [Figure 2]

[0014] This is a partial top view of an LED package similar to the LED package in Figure 1, for an alternative layout of a dielectric reflector. [Figure 3]

[0015] This is a cross-sectional view of an exemplary dielectric reflector that may be provided for any embodiment of the present disclosure. [Figure 4]

[0016] Figure 4A is a cross-sectional view of the structure including the first pattern trace and dielectric reflector.

[0017] Figure 4B is a cross-sectional view of the structure of the first pattern trace and the alternative arrangement of the dielectric reflector. [Figure 5]

[0018] Figure 5A is a cross-sectional view of an LED package cut along a portion of the LED package similar to the cross-sectional line AA in Figure 1, wherein the LED package is assembled with at least one LED chip and a cover structure according to the principles of this disclosure.

[0019] Figure 5B is a cross-sectional view of the LED package shown in Figure 5A, cut along a portion of the LED package that is similar to the cross-sectional line BB in Figure 1, in a region outside the LED chip. [Figure 6]

[0020] Figure 6A is a cross-sectional view of an LED package similar to the LED packages in Figures 5A and 5B, having an alternative arrangement of the cover structure.

[0021] Figure 6B is a cross-sectional view of the LED package shown in Figure 6A, cut along a portion of the LED package, similar to the cross-sectional line BB in Figure 1, in a region outside the LED chip. [Figure 7]

[0022] Figure 7A is a cross-sectional view of an LED package cut along a portion of the LED package similar to the cross-sectional line AA in Figure 1, where a dielectric reflector is provided between the cover structure and the submount in the cover structure mounting region.

[0023] Figure 7B is a cross-sectional view of the LED package shown in Figure 7A, cut along a portion of the LED package similar to the cross-sectional line BB in Figure 1. [Figure 8]

[0024] Figure 8A is a cross-sectional view of an LED package similar to the LED packages in Figures 6A and 6B, in which a dielectric reflector is provided between the cover structure and the submount in the cover structure mounting region.

[0025] Figure 8B is a cross-sectional view of the LED package shown in Figure 8A, cut along a portion of the LED package, similar to the cross-sectional line BB in Figure 1, in a region outside the LED chip. [Figure 9]

[0026] This is a cross-sectional view of an LED package similar to the LED package in Figure 5A, wherein a dielectric reflector is further provided on a portion of the submount adjacent laterally to the first pattern trace. [Figure 10]

[0027] A cross-sectional view of an LED package similar to the LED package of FIG. 7A, the cross-sectional view further including a dielectric reflector provided on a part of a submount that is laterally adjacent to a first pattern trace. [Figure 11]

[0028] A cross-sectional view of an LED package cut along a part of the LED package similar to the cross-sectional line A-A of FIG. 1, the cross-sectional view showing that no first pattern trace is provided in the cover structure mounting region. [Figure 12]

[0029] A cross-sectional view of an LED package similar to the LED package of FIG. 11, except that the dielectric reflector is not located inside the cover structure mounting region. [Figure 13]

[0030] A cross-sectional view of an LED package cut along a part of the LED package similar to the cross-sectional line A-A of FIG. 1, the cross-sectional view showing that the LED package includes a reflector structure disposed between a cover structure and a submount. [Figure 14]

[0031] A cross-sectional view of an LED package similar to the LED package of FIG. 13, the cross-sectional view showing that the dielectric reflector extends over the first pattern trace at a position between the reflector structure and the submount. [Figure 15]

[0032] A cross-sectional view of an LED package similar to the LED package of FIG. 13, the cross-sectional view showing that the dielectric reflector extends along a sidewall of the reflector structure. [Figure 16]

[0033] A cross-sectional view of an LED package similar to the LED package of FIG. 15, the cross-sectional view showing that the dielectric reflector extends along a sidewall of the reflector structure between the reflector structure and the first pattern trace.

Embodiments for Carrying Out the Invention

[0013]

[0034] The embodiments described below provide the information necessary to enable those skilled in the art to realize the embodiments and illustrate the best mode for realizing the embodiments. By reading the following description with reference to the accompanying drawings, those skilled in the art will understand the concepts of this disclosure and recognize applications of these concepts not specifically addressed herein. It should be understood that these concepts and applications are included within the scope of this disclosure and the accompanying claims.

[0014]

[0035] In this specification, terms such as "first," "second," etc., may be used to describe various elements, but it will be understood that these elements should not be limited by these terms. These terms are used solely to distinguish one element from another. For example, without departing from the scope of this disclosure, a first element may be called a second element, and similarly, a second element may be called a first element. As used herein, the term "and / or" includes any and all combinations of one or more of the relevant list items.

[0015]

[0036] When an element such as a layer, region, or substrate is described as being "on top of" another element, or extending "upwards" of another element, it will be understood that the element may be directly on top of the other element, or extend directly onto the other element, or there may be an intervening element. In contrast, when an element is described as being "directly on top of" another element, or extending "directly upwards" of another element, there is no intervening element. Similarly, when an element such as a layer, region, or substrate is described as being "above" another element, or extending "upwards," it will be understood that the element may be directly above another element, or extend directly onto the other element, or there may be an intervening element. In contrast, when an element is described as being "immediately above" another element, or extending "immediately above" another element, there is no intervening element. Furthermore, when an element is said to be “connected” or “joined” to another element, it will be understood that the element may be directly connected or joined to the other element, or there may be an intermediary element. In contrast, when an element is said to be “directly connected” or “directly joined” to another element, there is no intermediary element.

[0016]

[0037] In this specification, relative terms such as “downward,” “upward,” “upper side,” “lower side,” “horizontal,” or “vertical” may be used to describe the relationship between one element, layer, or region and another, as illustrated in the figures. It is understood that these terms and the terms discussed above are intended to encompass various orientations of the device, in addition to the orientation shown in the figures.

[0017]

[0038] The terms used herein are for the sole purpose of describing specific embodiments and are not intended to limit the disclosure. As used herein, the singular forms “a,” “an,” and “the” are intended to include the plural form unless the context clearly indicates otherwise. Furthermore, the terms “equipped,” “equipped,” “contains,” and / or “contains” as used herein identify the presence of a described feature, complete, step, action, element, and / or component, but are not intended to exclude the presence or addition of one or more other features, complete, step, action, element, component, and / or group thereof.

[0018]

[0039] Unless otherwise defined, all terms used herein (including technical and scientific terms) have the same meaning as those generally understood by those skilled in the art to the extent of this disclosure. Furthermore, terms used herein should be interpreted as having meanings consistent with their meanings in the context of this specification and related art, and it will be understood that they should not be interpreted in an idealized or overly formal sense unless expressly defined herein.

[0019]

[0040] In this specification, embodiments are described with reference to schematic drawings of embodiments of the present disclosure. Therefore, the actual dimensions of layers and elements may differ, and variations from the schematic shapes are expected, for example, as a result of manufacturing techniques and / or tolerances. For example, areas illustrated or described as squares or rectangles may have rounded or curved features, and areas illustrated as straight lines may have irregularities. Thus, areas illustrated in the drawings are schematic, and their shapes are not intended to illustrate the exact shapes of areas in the device, nor are they intended to limit the scope of the disclosure. In addition, the size of structures or areas may be exaggerated for illustrative purposes compared to other structures or areas, and are therefore provided to illustrate general structures of the subject matter, and may or may not be drawn to scale. Elements common to both drawings may be illustrated herein with common element numbers and may not be described again later.

[0020]

[0041] This disclosure relates to solid-state light-emitting devices, including light-emitting diodes (LEDs), and more particularly to reflectors for support structures in LED packages. The support structure includes the arrangement of dielectric reflectors on the LED chip and conductive traces patterned on a submount. The dielectric reflectors include a plurality of dielectric layer structures forming a distributed Bragg reflector, or optionally a non-periodic Bragg reflector. Such dielectric reflectors may be arranged on one or more conductive traces among the conductive traces and on portions of the submount not covered by the conductive traces, and enhance reflectivity over a range of wavelengths provided by the LED chip, including wavelengths in the ultraviolet (UV) spectrum.

[0021]

[0042] Before delving into the specific details of various aspects of this disclosure, an overview of the various elements that may be included in an exemplary LED package of this disclosure is provided for context. An LED chip typically comprises an active LED structure or region which can have a number of different semiconductor layers arranged in various ways. The manufacturing and operation of LEDs and their active structures are generally known in the art and will be discussed only briefly herein. The layers of an active LED structure can be manufactured using known processes, with appropriate processes such as metal-organic chemical vapor deposition. The layers of an active LED structure can comprise many different layers, and generally comprise an active layer sandwiched between oppositely doped n-type and p-type epitaxial layers, all of which are formed continuously on a growth substrate. It is understood that an active LED structure also includes additional layers and elements, including but not limited to buffer layers, nucleation layers, superlattice structures, undoped layers, cladding layers, contact layers, current diffusion layers, photoextraction layers and elements. The active layer may comprise a single quantum well, multiple quantum wells, a double heterostructure, or a superlattice structure.

[0022]

[0043] Active LED structures can be manufactured from different material systems, some of which are Group III nitride-based. Group III nitrides refer to semiconductor compounds formed from nitrogen (N) and elements of Group III of the periodic table, typically aluminum (Al), gallium (Ga), and indium (In). Gallium nitride (GaN) is a common binary compound. Group III nitrides also refer to ternary and quaternary compounds such as aluminum gallium nitride (AIGaN), indium gallium nitride (InGaN), and aluminum indium gallium nitride (AllnGaN). Other material systems include silicon carbide (SiC), organic semiconductor materials, and other Group III-V systems such as gallium phosphide (GaP), gallium arsenide (GaAs), and related compounds.

[0023]

[0044] Active LED structures can be grown on growth substrates that can contain many materials, including sapphire, SiC, aluminum nitride (AlN), and GaN. SiC has certain advantages, such as closer crystal lattice matching with Group III nitrides than other substrates, resulting in high-quality Group III nitride films. SiC also has very high thermal conductivity, so the total power output of Group III nitride devices on SiC is not limited by thermal dissipation of the substrate. Sapphire is another common substrate for Group III nitrides and also has certain advantages, such as lower cost, established manufacturing processes, and good optical properties with good light transmission.

[0024]

[0045] Different embodiments of the active LED structure can emit light of different wavelengths depending on the configuration of the active layer, n-type layer, and p-type layer. In some embodiments, the active LED structure emits blue light with a peak wavelength range of approximately 430 nanometers (nm) to 480 nm. In other embodiments, the active LED structure emits green light with a peak wavelength range of 500 nm to 570 nm. In yet another embodiment, the active LED structure emits red light with a peak wavelength range of 600 nm to 650 nm. In certain embodiments, the active LED structure may be configured to emit light outside the visible spectrum, including one or more portions of the UV spectrum. The UV spectrum is typically divided into three wavelength range categories, indicated by the letters A, B, and C. Thus, UV-A light is typically defined as having a peak wavelength range of 315 nm to 400 nm, UV-B as typically having a peak wavelength range of 280 nm to 315 nm, and UV-C as typically having a peak wavelength range of 100 nm to 280 nm. UV LEDs have attracted particular attention in applications related to the disinfection of microorganisms in air, water, and on surfaces. In other applications, UV LEDs can be equipped with one or more lumiphoric materials to provide concentrated emission with a broad spectrum and improved color quality for visible light applications within the LED package.

[0025]

[0046] Light emitted from the active layer or region of an LED chip can typically travel in various directions. For targeted applications, internal mirrors or external reflective surfaces can be used to redirect as much light as possible in the desired emission direction. Internal mirrors may consist of one or more layers. Some multilayer mirrors include a metallic reflective layer and a dielectric reflective layer, with the dielectric reflective layer positioned between the metallic reflective layer and multiple semiconductor layers. Passivation layers are positioned between the metallic reflective layer and first and second electrical contacts, with the first electrical contacts conductively communicating with the first semiconductor layer and the second electrical contacts conductively communicating with the second semiconductor layer. In the case of single-layer or multilayer mirrors that include surfaces exhibiting less than 100% reflectivity, some light may be absorbed by the mirror. In addition, light redirected through the active LED structure may be absorbed by other layers or elements within the LED chip.

[0026]

[0047] As used herein, a layer or region of an LED light-emitting device may be considered “transparent” if at least 80% of the emitted light that strikes that layer or region passes through it. Furthermore, as used herein, a layer or region of an LED may be considered “reflective” or embody a “mirror” or “reflector” if at least 80% of the emitted light that strikes that layer or region is reflected. In some embodiments, the emitted light comprises visible light, such as blue and / or green LEDs, with or without the light-emitting material. In other embodiments, the emitted light may comprise invisible light. For example, in the context of GaN-based blue and / or green LEDs, silver (Ag) may be considered a reflective material (e.g., reflecting at least 80%). In the case of UV LEDs, appropriate materials may be selected to achieve a desired, depending on the embodiment, high reflectivity and / or a desired, depending on the embodiment, low absorptivity. In certain embodiments, a “light-transmitting” material may be configured to transmit at least 50% of the emitted light of a desired wavelength.

[0027]

[0048] This disclosure may be useful for LED chips having various geometric shapes, including flip-chip geometry. The flip-chip structure of an LED chip typically includes anode and cathode connections formed from the same side or face of the LED chip. The anode and cathode sides are typically structured as mounting surfaces of the LED chip for flip-chip mounting on another surface, such as a printed circuit board. In this respect, the anode and cathode connections on the mounting surface serve to mechanically bond and electrically couple the LED chip to the other surface. When flip-chip mounted, the opposite side or face of the LED chip coincides with the light-emitting surface oriented in the intended direction of light emission. In certain embodiments, when flip-chip mounted, the growth substrate of the LED chip may form the light-emitting surface and / or be adjacent to the light-emitting surface. During chip manufacturing, the active LED structure may be epitaxially grown on the growth substrate.

[0028]

[0049] According to aspects of this disclosure, an LED package may include one or more elements, particularly a light-emitting material or phosphor for wavelength conversion, a encapsulant, a light-altering material, a lens, and electrical contacts, on which one or more LED chips are provided. In certain embodiments, the LED package may include support members such as a submount or lead frame. The light-altering material can be placed inside the LED package to reflect light from one or more LED chips or to redirect it in a desired emission direction or pattern in another way. As used herein, the light-altering material may include many different materials, including light-reflecting materials that reflect or redirect light, light-absorbing materials that absorb light, and materials that act as thixotropes.

[0029]

[0050] Aspects of this disclosure include support structures for LED packages. A support structure can refer to a structure of an LED package that supports one or more other elements of the LED package, including but not limited to the LED chip and cover structure. In certain embodiments, the support structure may include a submount on which the LED chip is mounted. Suitable materials for the submount include, but are not limited to, ceramic materials such as aluminum oxide or alumina, AIN, or organic insulators such as polyimide (PI) or polyphthalamide (PPA). In other embodiments, the submount may comprise a printed circuit board (PCB), sapphire, Si, or any other suitable material. For PCB embodiments, different types of PCBs can be used, such as a standard FR-4 PCB, a metal core PCB, or any other type of PCB. In further embodiments, the support structure may embody a lead frame structure. Aspects of this disclosure are provided in the context of support structures for LED chips that may emit light in any number of wavelength ranges, including wavelengths in the UV and / or visible light spectrum.

[0030]

[0051] UV LEDs have attracted particular attention in applications related to the disinfection of microorganisms, particularly in air, water, and on surfaces. In other applications, UV LEDs may also be provided with one or more emissive materials to provide concentrated broad emission with improved color quality in the visible spectrum. Certain embodiments of this disclosure may be well suited for applications where LED emission is provided in one or more of the UV-A, UV-B, and UV-C wavelength ranges. Lower peak wavelengths, such as one or more peak wavelengths in the UV-B and UV-C wavelength ranges, may have high energy levels and may lead to the decomposition of materials commonly used in other LED packages, including silicon, polymers, and / or other organic materials commonly used as encapsulants and / or binders for reflective particles and / or emissive materials. Cover structures for UV-based LED packages may need to provide protection from exposure to the external environment, such as providing hermetic sealing. As used herein, hermetic sealing generally refers to a seal that is airtight and waterproof and prevents the passage of air, gas, and / or liquid. In this regard, organic materials such as silicon and epoxy are not considered hermetic because they are permeable to air. Thus, the UV LED cover structure may include at least one of glass, quartz, and / or ceramic materials to reduce damage from exposure to UV radiation, while also being attached to or otherwise bonded to a package support structure to hermetically seal the underlying LED chip.

[0031]

[0052] The support structure of an LED package may include one or more conductive materials that can provide electrical connections to the LED chip. The conductive material may be provided as a metal trace or patterned metal trace on a submount, or the conductive material may form a lead frame structure that may or may not include a corresponding submount. The conductive material may include any number of materials, including copper (Cu) or its alloys, nickel (Ni) or its alloys, nickel-chromium (NiCr), gold (Au) or its alloys, electroless Au, electroless silver (Ag), NiAg, Al or its alloys, titanium-tungsten (TiW), titanium-tungsten nitride (TiWN), electroless nickel-palladium immersion gold (ENEPIG), electroless nickel immersion gold (ENIG), hot air solder leveling (HASL), and organic solderability preservative (OSP). In certain embodiments, the conductive material may include ENEPIG or ENIG, which includes a top layer of gold (Au). In other embodiments, the conductive material may include a top layer of silver (Ag). For UV-B and UV-C wavelength spectra, the reflectivity of Au and Ag is low (e.g., about 20% to 40%). In such embodiments, a layer with increased reflectivity to UV radiation, such as Al, may be placed on or incorporated into the conductive material in other ways.

[0032]

[0053] According to the principles disclosed herein, the arrangement of dielectric reflectors further improves the reflectivity of the LED package. In certain embodiments, the dielectric reflector may be configured to increase reflectivity to specific wavelengths, such as UV wavelengths, while at the same time being composed of a material resistant to degradation associated with UV exposure. As will be described in detail later, the dielectric reflector may include multilayer structures that form distributed Bragg reflectors or even non-periodic distributed Bragg reflectors. Such dielectric reflectors may be provided on and / or on a portion of the package submount on patterned metal traces and / or between patterned metal traces, thereby increasing the reflective surface without electrically short-circuiting adjacent electrical traces.

[0033]

[0054] Figure 1 is a top view showing a portion of an LED package 10, including a dielectric reflector 18 and portions 14-1 to 14-3 of a first pattern trace, collectively referred to herein as the first pattern trace 14, provided on a submount 12 in accordance with the principles of this disclosure. As used herein, the submount 12 is a form of support structure for the LED package 10. The first pattern trace 14 may form several discontinuous portions, i.e., traces 14-1 to 14-3, on the submount 12. For example, discontinuous portions of the first pattern trace 14, i.e., traces 14-2 and 14-3, may form die mounting pads for an LED chip, with one of the discontinuous portions 14-2, 14-3 forming the anode pad of the die mounting pad and the other of the discontinuous portions 14-2, 14-3 forming the corresponding cathode pad of the die mounting pad. In this way, the LED chip can be flip-chip mounted on the die mounting pad. Vias 16 may be provided to electrically connect the discontinuous portions 14-2 and 14-3 to corresponding electrical connections on the rear or bottom surface of the submount 12. In certain embodiments, the projections 14-2' and 14-3' of the discontinuous portions 14-2 and 14-3 may extend away from the die mounting pad area and form a mounting area for another element, such as an electrical overstress element (e.g., an ESD chip, a Zener diode, etc.), which may be coupled in parallel with the LED chip. As illustrated, a portion of the submount 12 between and around the discontinuous portions 14-2 and 14-3 is either without the first pattern trace 14 or not covered by the first pattern trace 14. In certain embodiments, the discontinuous portion 14-1 may be provided on the submount 12 around the discontinuous portions 14-2 and 14-3.

[0034]

[0055] The first pattern trace 14 may include one or more layers of copper, gold, silver, ENEPIG, ENIG, etc., which reduce reflectivity to UV-B and UV-C radiation. In certain embodiments, a dielectric reflector 18 is selectively provided on the first pattern trace 14. In Figure 1, the dielectric reflector 18 is provided on a portion of the discontinuous portion 14-1 (as better illustrated in the cross-sectional views of Figures 5A to 6B). The dielectric reflector 18 may include any material that exhibits a high reflectivity to a particular LED radiation, such as at least 60% reflectivity, at least 80% reflectivity, or at least 90% reflectivity, compared to the first pattern trace 14. For example, for UV-B and UV-C wavelengths, aluminum may provide at least 90% reflectivity, while the material of the first pattern trace 14 may exhibit less than 40% reflectivity. As will be described in detail later, the cover structure may be mounted to the submount 12 using a metallurgical bonding material. While the dielectric reflector 18 may exhibit improved reflectivity, the metallurgical bonding material may enhance the adhesion of the first pattern trace 14 to the material. In this regard, the dielectric reflector 18 is selectively provided on the first pattern trace 14, allowing the cover structure mounting region to directly access the first pattern trace 14. In Figure 1, the portion of the discontinuous portion 14-1 that lacks or is not covered by the dielectric reflector 18 forms a cover structure mounting region provided around the surface of the submount 12. Thus, the cover structure of the LED package 10 can be mounted such that the cover structure contacts the submount 12 only in the cover structure mounting region. In this way, the dielectric reflector 18 may be provided on a portion of the first pattern trace 14 between the die mounting pads (e.g., 14-2, 14-3) and the cover structure mounting region. As will be described in detail later, in other embodiments, the dielectric reflector 18 may alternatively extend over the cover structure mounting area, so that all or substantially all of the submount 12 outside the die mounting pads of the LED chip and the mounting area of ​​the electrically overstressed element are covered by the dielectric reflector 18.

[0035]

[0056] Figure 2 is a top view showing a portion of an LED package 20 similar to the LED package 10 in Figure 1, relating to an alternative layout of the dielectric reflector 18. As illustrated, the dielectric reflector 18 forms a circular shape on the discontinuous portion 14-1 of the first pattern trace 14. In this regard, the cover structure mounting area formed by the region of the discontinuous portion 14-1 where the dielectric reflector 18 is absent or not covered by the dielectric reflector 18 is also provided with a corresponding circular pattern. Such an arrangement may be suitable for a cover structure including a domed lens mounted above the submount 12. Similar to Figure 1, the dielectric reflector 18 can extend to the periphery of the submount 12 and cover all or substantially all of the submount 12 outside the die mounting pad of the LED chip, and the mounting area of ​​the electrically overstress element is covered by the dielectric reflector 18.

[0036]

[0057] Figure 3 is a cross-sectional view of an exemplary dielectric reflector 18 that may be provided for either the above-mentioned embodiments or the later embodiments of this disclosure. The dielectric reflector 18 may comprise a plurality of dielectric layers 18-1 to 18-9 configured to enhance the reflection of light from an associated LED chip. In certain embodiments, the material and / or thickness of the individual dielectric layers 18-1 to 18-9 may be adjusted to provide a varying optical thickness. Optical thickness may also be referred to as optical path length and may be defined as the product of the refractive index of the material and the geometric length, which is the optical path through the layer. Thus, the optical thickness of the individual layers 18-1 to 18-9 can be altered by increasing or decreasing the actual thickness of the layer and / or by providing the layer with a different material type than another layer of layers 18-1 to 18-9. In certain embodiments, the dielectric layers 18-1 to 18-9 may form layers of alternating optical thickness so that the dielectric reflector 18 comprises a distributed Bragg reflector. For example, each of the dielectric layers 18-1, 18-3, 18-5, 18-7, and 18-9 may comprise a first material type, and each of the dielectric layers 18-2, 18-4, 18-6, and 18-8 may comprise a second material type having a different refractive index than the first material type.

[0037]

[0058] The dielectric reflector 18 may also form a non-periodic distributed Bragg reflector in which the optical thickness of each of the dielectric layers 18-1 to 18-9 varies across the portion of the dielectric reflector 18. In certain embodiments, each individual dielectric layer 18-1 to 18-9 may have a unique optical thickness in comparison to the other dielectric layers 18-1 to 18-9. For example, each of the dielectric layers 18-1, 18-3, 18-5, 18-7, and 18-9 may comprise a first material type, but the relative thicknesses of the dielectric layers 18-1, 18-3, 18-5, 18-7, and 18-9 may vary. In certain embodiments, dielectric layer 18-3 inside the dielectric reflector 18 is the thickest layer, but the other layers 18-1, 18-5, 18-7, and 18-9 may also have thicknesses that vary relative to each other. Similarly, dielectric layers 18-2, 18-4, 18-6, and 18-8 may comprise a second material type having a different refractive index than the first material type, and one or more of the dielectric layers 18-2, 18-4, 18-6, and 18-8 may have thicknesses that vary relative to each other. Thus, the interfaces between each pair of adjacent dielectric layers 18-1 to 18-9 may provide different total internal reflection (TIR) ​​responses based on the angle and wavelength of the incident light. In general, a dielectric layer with a greater optical thickness (e.g., 18-3) promotes TIR for light at shallower angles of incidence more than another layer with a thinner optical thickness (e.g., 18-1). Thus, it may be advantageous to place the layer with the thickest optical thickness (e.g., 18-3) inside the dielectric reflector 18, away from the top surface of the dielectric reflector 18, or at the bottom of the dielectric reflector 18, so that light at larger angles of incidence can be redirected earlier, avoiding potential optical loss due to internal absorption. Therefore, multiple layers with varying optical thicknesses allow some layers to reflect more light at shallower angles of incidence, while other layers reflect more light at larger angles of incidence, resulting in improved total internal reflection across all angles in the multiple layers.

[0038]

[0059] The materials for dielectric layers 18-1 to 18-9 may include, among other things, aluminum oxide (Al2O3), hafnium oxide (HfO2), silicon dioxide (SiO2), zirconium dioxide (ZrO2), and / or silicon nitride. In the context of UV radiation, dielectric layers 18-1 to 18-9 with structures of greater optical thickness contrast and / or greater refractive index difference can be used to appropriately redirect such wavelengths. As an example, the ability to individually tune the optical thickness of each dielectric layer 18-1 to 18-9 can provide reflectance values ​​of at least 97%, or 97% to 99%, for UV radiation in the range of 250 nm to 315 nm, or 200 nm to 315 nm. Such reflectance values ​​surpass those of conventional metallic reflective layers commonly used in UV LED packages. In a further embodiment, the ability to individually adjust the optical thickness of each of the dielectric layers 18-1 to 18-9 may also provide the ability to specifically adjust the light emission pattern and / or wavelength range of the LED package.

[0039]

[0060] Figure 4A is a cross-sectional view of a structure 22 including a first pattern trace 14 and a dielectric reflector 18 according to a particular embodiment. For illustrative purposes, the dielectric reflector 18 is depicted without the detail of Figure 3, but it is understood that the dielectric reflector 18 may include any of the layers 18-1 to 18-9 described above with respect to Figure 3. Figure 4A may represent any embodiment of the present disclosure from a region on which the dielectric reflector 18 is formed on the first pattern trace 14. As illustrated, the first pattern trace 14 may embody a multilayer structure such as a first layer 24, a second layer 26, and a third layer 28 of the first pattern trace 14. In a particular embodiment, the first layer 24 may include a layer of Cu and / or an alloy thereof, the second layer 26 may include a layer of one or more of Ni, palladium (Pd), or an alloy thereof, and the third layer 28 may comprise a layer of Au. The first pattern trace 14 may include an electrolyte layer and may be collectively referred to as the ENEPIG layer. In certain embodiments, a thin adhesive layer containing titanium (Ti) and / or an alloy thereof may be provided on the bottom surface of the first layer 24 for adhesion to a lower submount.

[0040]

[0061] Figure 4B is a cross-sectional view 32 of a structure 30 with an alternative arrangement of the first pattern trace 14 and the dielectric reflector 18. In Figure 4B, the structure 30 includes a layer 31 that occupies most or even all of the first pattern trace 14. In certain embodiments, a thin adhesive layer may be provided on the bottom side of the layer 31. In embodiments that do not contain Cu, the layer 31 may comprise a layer of Au. Alternatively, the layer 31 may comprise a layer of Cu with a thin layer of silver on the upper side of the interface with the dielectric reflector 18.

[0041]

[0062] Figures 5A to 16 are cross-sectional views of LED packages having various configurations of the dielectric reflector 18 and the first pattern trace 14 as described above. Figures 5A to 16 are illustrated using the first pattern trace 14 as described above for Figure 4A. However, it can also be understood that the first pattern trace 14 in each of Figures 5A to 16 may alternatively have the structure described above for Figure 4B. In addition, the dielectric reflector 18 in Figures 5A to 16 may have any of the structures described above for Figure 3.

[0042]

[0063] Figure 5A is a cross-sectional view of an LED package 34 cut along a portion of the LED package 34 similar to section line AA in Figure 1, the LED package 34 being assembled with at least one LED chip 36 and a cover structure 38 in accordance with the principles of this disclosure. Depending on the embodiment and intended application, the LED chip 36 may be configured to emit a peak wavelength in either the visible spectrum or the UV spectrum, including a peak wavelength in the range of 200 nm to 750 nm or in the range of 200 nm to 400 nm. As illustrated, the LED chip 36 is mounted on a die mounting pad formed by a portion of a first pattern trace 14 (e.g., portions 14-2, 14-3 in Figure 1). Vias 16 extend across the entire thickness of the submount 12 and may provide an electrical connection between the LED chip 36 on the upper surface of the submount 12 and a corresponding portion of a second pattern trace 15 provided on the bottom surface of the submount 12. The second pattern trace 15 may be configured to accept an external electrical connection of the LED package 34. In addition, the second pattern trace 15 provides a sufficient surface area across the entire bottom surface of the submount 12, which can improve heat dissipation of the LED package 34. In certain embodiments, the second pattern trace 15 may include an arrangement similar to the first pattern trace 14, such that the first layer 24, the second layer 26, and the third layer 28 are sequentially provided on the bottom surface of the submount 12. In other embodiments, the second pattern trace 15 may include a different structure from the first pattern trace 14.

[0043]

[0064] The cover structure 38 is formed above the LED chip 36 and can be attached to the first pattern trace 14 around or near the LED package 34. Such a mounting area may be referred to as the cover structure mounting area. The cover structure 38 may include vertical side walls extending to the submount 12 at one or more locations below the height of the LED chip 36. In this respect, the cover structure 38 may form a cavity 40 or opening above the LED chip 36 and above the submount 12. In certain embodiments, the cavity 40 may be filled with air and / or nitrogen. In certain embodiments, depending on how the cover structure 38 is mounted, the cavity 40 may be in a vacuum relative to the ambient atmosphere. In certain embodiments, the cover structure 38 forms an airtight seal for the LED package 34. As illustrated, the cover structure mounting area is defined as the location where the cover structure 38 is attached to the first pattern trace 14 around or near the submount 12. In certain embodiments, the cover structure 38 may form a dome-shaped or hemispherical lens for directing light emitted from the LED chip 36. In certain embodiments, the lens may have many different shapes depending on the desired shape of the light output. Suitable shapes include hemispherical, elliptical, ellipsoidal, cubic, planar, hexagonal, and square. In certain embodiments, suitable shapes include both curved and planar surfaces, such as a hemispherical or curved top and planar sides. As illustrated in Figure 5A, the curved top edge of the cover structure 38 may be aligned with the corresponding edge of the cavity 40.

[0044]

[0065] While the material of the first pattern trace 14 may provide good adhesion for mounting the LED chip 36 and cover structure 38, the material of the first pattern trace 14 may have poor reflectivity, particularly in embodiments where the LED chip 36 provides UV-B and / or UV-C light. In this regard, the dielectric reflector 18 is provided on a portion of the first pattern trace 14 between the die mounting pad of the LED chip 36 and the cover structure mounting area. By positioning the dielectric reflector 18 above the portion of the first pattern trace 14 exposed inside the cavity 40, reflectivity is improved, and light emission from the LED package 34 is increased. The dielectric reflector 18 may be configured for all wavelengths of light, including visible and UV, but the dielectric reflector 18 may be particularly useful for UV applications where conventional insulating reflective materials, such as white solder masks, may degrade under UV radiation. As illustrated, in certain embodiments, at least a portion of the dielectric reflector 18 may self-align with at least one end of the first pattern trace 14.

[0045]

[0066] Figure 5B is a cross-sectional view of the LED package 34 of Figure 5A, cut along a portion of the LED package 34 similar to the cross-sectional line BB of Figure 1, in the region outside the LED chip 36. As illustrated, the dielectric reflector 18 may be provided along substantially all of the first pattern trace 14, which is outside the LED chip 36 and inside the cavity 40, in order to increase reflectivity. In Figures 5A and 5B, the dielectric reflector 18 is illustrated with a small gap near the cover structure 38 to ensure mounting tolerances for the cover structure 38. In other embodiments, the dielectric reflector 18 may extend completely without gap from one end to the other of the cavity 40.

[0046]

[0067] Figure 6A is a cross-sectional view of an LED package 42 similar to the LED package 34 in Figures 5A and 5B, having an alternative arrangement of the cover structure 38. The cross-sectional view provided in Figure 6A is a cross-sectional view cut along a portion of the LED package 42 similar to that provided for the illustration of the LED package 34 in Figure 5A. Figure 6B is a cross-sectional view of the LED package 42 of Figure 6A, cut along a portion of the LED package 42 similar to the cross-sectional line BB in Figure 1, in a region that is outside the LED chip 36. The LED package 42 is similar to the LED package 34 in Figures 5A and 5B, except that the cover structure 38 forms a flat or planar cover with vertical sidewalls that extend to the submount 12 above the submount 12 and below the height of the LED chip 36. In this respect, for certain applications, the LED package 42 may offer a lower profile.

[0047]

[0068] Figure 7A is a cross-sectional view of the LED package 44 cut along a portion of the LED package 44 similar to section line AA in Figure 1, wherein, in accordance with the principles of this disclosure, a dielectric reflector 18 is provided between the cover structure 38 and the submount 12 in the cover structure mounting region. Figure 7B is a cross-sectional view of the LED package 44 of Figure 7A cut along a portion of the LED package 44 similar to section line BB in Figure 1. The LED package 44 is similar to the LED package 34 of Figures 5A and 5B, except that the dielectric reflector 18 extends between the cover structure 38 and the submount 12 in the cover structure mounting region. In this respect, the dielectric reflector 18 may cover the entire region of the first pattern trace 14, which is discontinuous with the die mounting pad of the LED chip 36. Such a configuration may be suitable for embodiments in which the cover structure 38 is made of a material that does not require metallurgical mounting, such as glass. In this regard, the cover structure 38 may be mounted on a portion of the dielectric reflector 18, and in some cases, particularly in UV applications, the reflectivity of the cover structure mounting area of ​​the LED package 44 may be improved.

[0048]

[0069] Figure 8A is a cross-sectional view of an LED package 46 similar to the LED package 42 in Figures 6A and 6B, wherein a dielectric reflector 18 is provided between the cover structure 38 and the submount 12 in the cover structure mounting region. The cross-sectional view provided in Figure 8A is a cross-sectional view cut along a portion of the LED package 46 similar to the one provided for the illustration of the LED package 42 in Figure 6A. Figure 8B is a cross-sectional view of the LED package 46 of Figure 8A, cut along a portion of the LED package 46 similar to the cutting line BB in Figure 1 in the region outside the LED chip 36. The LED package 46 is similar to the LED package 44 of Figures 7A and 7B for embodiments in which the cover structure 38 forms a flat or planar cover above the submount 12 and the vertical sidewalls extend to the submount 12 at a position below the height of the LED chip 36. In this regard, for specific applications, the LED package 46 may offer a lower profile.

[0049]

[0070] Figure 9 is a cross-sectional view of an LED package 48 similar to Figure 5A, wherein a dielectric reflector 18 is further provided on a portion of a submount 12 laterally adjacent to the first pattern trace 14. Thus, the dielectric reflector 18 can be positioned on a portion of the submount 12 without the first pattern trace 14 in between. For example, a portion of the dielectric reflector 18 may be on a submount 12 in the gap between discontinuous portions of the first pattern trace 14 that form the die mounting pad (e.g., 14-2, 14-3 in Figure 1). Thus, the dielectric reflector 18 can be positioned between the LED chip 36 and the submount 12 to reflect downward-propagating light toward the cover structure 38. To avoid topographic differences for mounting the LED chip 36, such portions of the dielectric reflector 18 may have a thickness less than the thickness of the first pattern trace 14. In certain embodiments, the dielectric reflector 18 may cover a portion of the submount 12 between other discontinuous portions of the first pattern trace 14 outside the die mounting area. In Figure 9, such areas are illustrated to the left and right of the LED chip 36. Thus, all or substantially all of the floor portion of the cavity 40, including the upper surface of the first pattern trace 14 and the upper surface of the submount 12 not covered by the first pattern trace 14, may be covered with the dielectric reflector 18 to improve brightness. As further illustrated in Figure 9, by providing the dielectric reflector 18 inside the cover structure mounting area and on the portion of the submount 12 not covered by the first pattern trace 14, the dielectric reflector 18 may effectively cover the entire submount 12, except for the portion of the first pattern trace 14 on which the LED chip 36 and optionally electrically overstressed elements are mounted. In certain embodiments, the arrangement of the cover structure 38 in Figure 6A may be combined with the arrangement of the dielectric reflector 18 in Figure 9 to be provided for the LED package 48 in Figure 9.

[0050]

[0071] Figure 10 is a cross-sectional view of an LED package 50 similar to the LED package 44 of Figure 7A, wherein a dielectric reflector 18 is further provided on a portion of a submount 12 laterally adjacent to the first pattern trace 14. In a manner similar to that described above with respect to Figure 9, the dielectric reflector 18 may be located along a portion of the submount 12 between discontinuous portions of the first pattern trace 14, such as beneath the LED chip 36 in the gap between the die mounting pads, and / or along a portion of the submount 12 adjacent to the LED chip 36. In addition, the dielectric reflector 18 may extend along a portion of the first pattern trace 14 such that the dielectric reflector 18 is located between the cover structure 38 and the first pattern trace 14. In this way, the cover structure 38 can be attached to the dielectric reflector 18.

[0051]

[0072] Figure 11 is a cross-sectional view of an LED package 52 cut along a portion of the LED package 52 similar to section line AA in Figure 1, wherein, in accordance with the principles of this disclosure, the cover structure mounting region does not have a first pattern trace 14. As illustrated, the first pattern trace 14 may be provided only in the region of the submount 12 that forms the die mounting pad (e.g., 14-2, 14-3 in Figure 1). In this regard, the dielectric reflector 18 may be provided circumferentially surrounding the LED chip 36 and the first pattern trace 14, and on the region of the submount 12 where the first pattern trace 14 is absent. The dielectric reflector 18 may even be positioned to extend to and contact the sidewall of the first pattern trace 14 adjacent to the LED chip 36. Thus, the cover structure mounting region includes the dielectric reflector 18 instead of the first pattern trace 14. As illustrated, the dielectric reflector 18 may have the same or greater thickness as the first pattern trace 14 to facilitate the bonding of the cover structure 38. In other embodiments, the dielectric reflector 18 may have a thickness less than the thickness of the first pattern trace 14. In addition, a portion of the dielectric reflector 18 may be provided in the gaps between discontinuous portions of the first pattern trace 14 that form the die mounting pad (e.g., 14-2, 14-3 in Figure 1). To avoid topographic differences for mounting the LED chip 36, such portions of the dielectric reflector 18 may have a thickness less than the thickness of the first pattern trace 14.

[0052]

[0073] Figure 12 is a cross-sectional view of an LED package 54 similar to the LED package 52 of Figure 11, except that the dielectric reflector 18 is not located inside the cover structure mounting area. As illustrated, the first pattern trace 14 is provided in the area of ​​the submount 12 for the die mounting pad and the area of ​​the submount 12 for the cover structure mounting area. In this regard, the dielectric reflector 18 may cover a portion of the submount 12 inside the cavity 40 that is not covered by the first pattern trace 14. In certain embodiments, the dielectric reflector 18 may be positioned to extend to and even contact the sidewall of the first pattern trace 14 adjacent to the LED chip 36 and the cover structure mounting area.

[0053]

[0074] Figure 13 is a cross-sectional view of an LED package 56 cut along a portion of the LED package 56 similar to section line AA in Figure 1, the LED package 56 includes a reflector structure 58 positioned between a cover structure 38 and a submount 12. In certain embodiments, the reflector structure 58 is a separate element that can be mounted on one or more of the first pattern trace 14 and the submount 12, or otherwise attached. As illustrated, the cover structure 38 can be attached to the reflector structure 58, and the reflector structure 58 and the cover structure 38 are attached to a cover structure mounting area provided around the LED chip 36. In Figure 13, the cover structure mounting area of ​​the submount 12 may be defined as the location where the reflector structure 58 is mounted on the first pattern trace 14. The reflector structure 58 may have an internal side wall 58' that defines the lateral boundary of the cavity 40. In certain embodiments, the side wall 58' is angled relative to the submount 12, allowing light radiated laterally from the LED chip 36 to be redirected through the cover structure 38 to the desired light emission direction of the LED package 56. In other embodiments, the side wall 58' may form a vertical side wall substantially perpendicular to the submount 12 while redirecting the laterally emitted light from the LED chip 36.

[0054]

[0075] The reflector structure 58 may comprise a material having a sufficiently large coefficient of thermal expansion (CTE) compared to the rest of the LED package 56. In certain embodiments, the reflector structure 58 comprises silicon and optionally has a metallic coating on its sidewalls 58', for example, aluminum or an alloy thereof. In other embodiments, the entire reflector structure 58 may comprise a metal such as aluminum or an alloy thereof. In yet another embodiment, the reflector structure 58 may comprise a ceramic, such as one or more of aluminum oxide (Al2O3), zirconium dioxide (ZrO2), silicon dioxide (SiO2), and aluminum nitride (AlN). In embodiments where the reflector structure 58 comprises a ceramic material, the sidewalls 58' may be coated with metal, as described above, to increase reflectivity. As illustrated, the dielectric reflector 18 is provided on the exposed portion of the first pattern trace 14 inside the cavity 40 to increase reflectivity. The dielectric reflector 18 may also be positioned in part of the submount 12 between discontinuous portions of the first pattern trace 14, below the LED chip 36 within the die mounting area and / or adjacent to the LED chip 36. Although the cover structure 38 is illustrated as planar in Figure 13, the cover structure 38 may form a dome-shaped or hemispherical lens for directing light emitted from the LED chip 36.

[0055]

[0076] Figure 14 is a cross-sectional view of an LED package 60 similar to the LED package 56 of Figure 13, in which a dielectric reflector 18 extends over the first pattern trace 14 at a position between the reflector structure 58 and the submount 12. In this respect, the reflector structure 58 can be directly bonded to the dielectric layer 18. As illustrated, extending the dielectric reflector 18 over the first pattern trace 14 and a portion of the submount 12 can simplify the manufacturing steps and also provide electrical insulation between the reflector structure 58 and the dielectric reflector 18.

[0056]

[0077] Figure 15 is a cross-sectional view of an LED package 62 similar to the LED package 56 of Figure 13, in which a dielectric reflector 18 extends along the side wall 58' of the reflector structure 58. In this way, the dielectric reflector 18 can cover the floor and side wall 58' surrounding the cavity 40 to increase reflectivity. In such embodiments, the dielectric reflector 18 may be formed inside the LED package 62 after the reflector structure 58 is mounted and before the LED chip 36 is provided. As in other embodiments, the dielectric reflector 18 may be positioned on a portion of the submount 12 between discontinuous portions of the first pattern trace 14, such as below and / or adjacent to the LED chip 36 within the die mounting area.

[0057]

[0078] Figure 16 is a cross-sectional view of an LED package 64 similar to the LED package 62 in Figure 15, in which the dielectric reflector 18 extends along the side wall 58' of the reflector structure 58 between the reflector structure 58 and the first pattern trace 14. Thus, a portion of the dielectric reflector 18 on the first pattern trace 14 and the submount 12 may be formed before the reflector structure 58 is mounted, while a portion of the dielectric reflector 18 on the side wall 58' may be formed after the reflector structure 58 is mounted on the submount 12.

[0058]

[0079] Any of the embodiments described herein, and / or any of the various individual embodiments and features described herein, may be combined for further advantages. Any of the various embodiments disclosed herein may be combined with one or more other disclosed embodiments unless otherwise indicated herein.

[0059]

[0080] Those skilled in the art will recognize improvements and modifications to preferred embodiments of this disclosure. All such improvements and modifications are deemed to fall within the scope of the concepts disclosed herein and the following claims.

Claims

1. Light-emitting diode (LED) package, A submount comprising a first surface and a second surface facing the first surface, At least one LED chip on the first surface of the submount, A cover structure positioned above at least one LED chip, A pattern trace on the first surface of the submount, wherein the cover structure is attached to the pattern trace in a cover structure mounting region outside at least one die mounting pad, A dielectric reflector on a portion of the pattern trace between the at least one die mounting pad and the cover structure mounting region, comprising a distributed Bragg reflector and a dielectric reflector, The dielectric reflector is further located on a portion of the submount not covered by the pattern trace and the at least one LED chip, and the thickness of the dielectric reflector from the first surface is thinner than the thickness of the pattern trace from the first surface. LED package.

2. The LED package according to claim 1, wherein the distributed Bragg reflector is a non-periodic distributed Bragg reflector.

3. The aperiodic distributed Bragg reflector comprises a plurality of dielectric layers, The LED package according to claim 2, wherein each dielectric layer of the plurality of dielectric layers has an optical thickness unique to that of the other dielectric layers among the plurality of dielectric layers.

4. The LED package according to claim 3, wherein the plurality of dielectric layers comprises dielectric layers in which a first material type and a second material type alternate.

5. The LED package according to claim 1, wherein the dielectric reflector is further present on the entire submount that is not covered by the pattern trace and the at least one LED chip.

6. The LED package according to claim 5, wherein the dielectric reflector is further disposed between the at least one LED chip and the submount in a gap formed by the pattern trace along the at least one die mounting pad.

7. The LED package according to claim 6, wherein at least one LED chip is configured to provide a peak wavelength in the range of 200 nm to 400 nm.

8. Light-emitting diode (LED) package, A submount comprising a first surface and a second surface facing the first surface, At least one LED chip on the first surface of the submount, A cover structure positioned above the at least one LED chip, the cover structure being mounted on the submount in a cover structure mounting region spaced apart from the peripheral boundary of the at least one LED chip, A pattern trace on the first surface of the submount, which forms at least one die mounting pad for the at least one LED chip, An LED package comprising a dielectric reflector on a portion of the submount laterally adjacent to the pattern trace, the dielectric reflector comprising a distributed Bragg reflector, wherein the thickness of the dielectric reflector from the first surface is thinner than the thickness of the pattern trace from the first surface.

9. The LED package according to claim 8, wherein the dielectric reflector is further arranged on a portion of the pattern trace.

10. The LED package according to claim 8, wherein the dielectric reflector is further disposed between the cover structure and the submount in the cover structure mounting region.

11. The aforementioned distributed Bragg reflector is a non-periodic distributed Bragg reflector. The aperiodic distributed Bragg reflector comprises a plurality of dielectric layers, The LED package according to claim 8, wherein each dielectric layer of the plurality of dielectric layers has an optical thickness unique to that of the other dielectric layers among the plurality of dielectric layers.

12. The LED package according to claim 11, wherein the plurality of dielectric layers comprises dielectric layers in which a first material type and a second material type alternate.

13. The LED package according to claim 11, wherein the dielectric layer having the greatest optical thickness among the plurality of dielectric layers is spaced apart from the upper surface of the aperiodic distributed Bragg reflector and located inside the aperiodic distributed Bragg reflector.

14. The LED package according to claim 8, wherein at least one LED chip is configured to provide a peak wavelength in the range of 200 nm to 400 nm.

15. Light-emitting diode (LED) package, A submount comprising a first surface and a second surface facing the first surface, At least one LED chip on the first surface of the submount, The pattern trace on the first surface of the submount, An LED package comprising a dielectric reflector on a portion of the pattern trace and on a portion of the submount laterally adjacent to the pattern trace, the dielectric reflector comprising a distributed Bragg reflector, wherein the thickness of the dielectric reflector from the first surface is thinner than the thickness of the pattern trace from the first surface.

16. The LED package according to claim 15, wherein the distributed Bragg reflector is a non-periodic distributed Bragg reflector.

17. The aperiodic distributed Bragg reflector comprises a plurality of dielectric layers, The LED package according to claim 16, wherein each dielectric layer of the plurality of dielectric layers has an optical thickness unique to that of the other dielectric layers among the plurality of dielectric layers.

18. The LED package according to claim 17, wherein the plurality of dielectric layers comprises dielectric layers in which a first material type and a second material type alternate.

19. The LED package according to claim 17, wherein the dielectric layer having the greatest optical thickness among the plurality of dielectric layers is spaced apart from the upper surface of the aperiodic distributed Bragg reflector and located inside the aperiodic distributed Bragg reflector.

20. The pattern trace comprises at least one die mounting pad for the at least one LED chip, The LED package according to claim 15, wherein the dielectric reflector is further disposed between the at least one LED chip and the submount in a gap formed by the pattern trace along the at least one die mounting pad.

21. The LED package according to claim 15, wherein the at least one LED chip is configured to provide a peak wavelength in the range of 200 nm to 400 nm.

22. The LED package according to claim 15, further comprising a cover structure positioned above a submount to form a cavity above the at least one LED chip.

23. The LED package according to claim 22, further comprising a reflector structure disposed between the cover structure and the submount, wherein the side wall of the reflector structure surrounds a portion of the cavity.

24. The LED package according to claim 23, wherein the dielectric reflector is arranged on the side wall of the reflector structure.

25. The LED package according to claim 23, wherein the dielectric reflector is disposed between the reflector structure and the submount.

Images