A COB light source

Abstract

The utility model discloses a COB light source, including mirror surface substrate, set up in the middle light emitting area of mirror surface substrate multiple LED chips, the insulating structure layer of the edge area setting of sticking mirror surface substrate, set up the circuit structure layer of the surface of insulating structure layer side away from mirror surface substrate, wherein, LED chip is vertical structure chip and the bottom electrode of each LED chip is fixedly connected through conductive die bonding adhesive and mirror surface substrate, or, LED chip is flip structure chip and the anode and cathode of each LED chip are fixedly connected through two conductive die bonding adhesive and mirror surface substrate of mutual isolation, and the electric connection of between each LED chip and between LED chip and circuit structure layer is all through the conductive die bonding adhesive and metal wire of LED chip connection is carried out. In the application, the circuit connection of LED chip is realized by metal wire and conductive die bonding adhesive, avoids forming the circuit structure on the mirror surface substrate, and the working performance of COB light source is improved.

Description

Technical Field

[0001] This utility model relates to the field of optical device technology, and in particular to a COB light source. Background Technology

[0002] COB (Chip on Board) light sources are a high-power integrated surface light source technology. They achieve high luminous efficiency and uniform light distribution by directly mounting LED chips onto a mirrored metal substrate to form a polycrystalline array. The strong reflectivity of the mirrored metal substrate in COB light sources improves the output efficiency of light energy to some extent; however, it also presents the challenge of forming circuit structures on the mirrored metal substrate. Utility Model Content

[0003] The purpose of this invention is to provide a COB light source that improves the performance of the light source without forming a circuit structure on a mirrored metal substrate.

[0004] To solve the above-mentioned technical problems, this utility model provides a COB light source, including a mirror substrate, a plurality of LED chips disposed in the light-emitting area in the middle of the mirror substrate, an insulating structure layer disposed in the edge area of ​​the mirror substrate, and a circuit structure layer disposed on the surface of the insulating structure layer on the side away from the mirror substrate.

[0005] Wherein, the LED chip is a vertical structure chip and the bottom electrode of each LED chip is fixedly connected to the mirror substrate by conductive die bond adhesive; or, the LED chip is a flip structure chip and the positive and negative electrodes of each LED chip are fixedly connected to the mirror substrate by two mutually isolated conductive die bond adhesives respectively.

[0006] Each of the LED chips and the LED chips and the circuit structure layer are electrically connected through the conductive die bond adhesive and metal wires connected to the LED chips.

[0007] In an optional embodiment of this application, when the LED chip is a vertical structure chip, the negative electrode of the LED chip is fixedly connected to the surface of the mirror substrate through the conductive die bond and the surface of the substrate; in two LED chips that are electrically connected to each other, the positive electrode of one LED chip is electrically connected to the conductive die bond connected to the negative electrode of the other LED chip through the metal wire.

[0008] In an optional embodiment of this application, when the LED chip is a flip-chip, the positive and negative electrodes of the LED chip are fixedly connected to the mirror substrate through a first conductive die bond and a second conductive die bond that are mutually insulated; among the two LED chips that are electrically connected to each other, the first conductive die bond connected to one LED chip is electrically connected to the second conductive adhesive connected to the other LED chip through the metal wire.

[0009] In one optional embodiment of this application, the circuit structure layer is a copper foil circuit structure layer; the insulating structure layer is a BT insulating layer; and the mirror substrate is a mirror aluminum plate or a silver-plated substrate.

[0010] In one optional embodiment of this application, the conductive die bond adhesive is a conductive silver paste or a nano-conductive paste.

[0011] In one optional embodiment of this application, the LED chip includes a first color temperature chip and a second color temperature chip that are alternately distributed.

[0012] The first color temperature chip is coated with a first color temperature fluorescent adhesive layer, and a second color temperature fluorescent adhesive layer is coated on the outer surface of the first color temperature fluorescent adhesive layer.

[0013] The second color temperature chip is coated with a second color temperature fluorescent adhesive layer, and the outer surface of the second color temperature fluorescent adhesive layer is coated with the first color temperature fluorescent adhesive layer.

[0014] In one optional embodiment of this application, each of the first color temperature chips is connected in series with each other; each of the second color temperature chips is connected in series with each other; and the first color temperature chip and the second color temperature chip are electrically connected to the circuit structure independently.

[0015] In one optional embodiment of this application, the central light-emitting area of ​​the mirror substrate is further covered with a silicone protective layer.

[0016] In one optional embodiment of this application, the silicone protective layer comprises multiple layers of silicone protective layers stacked sequentially with increasing refractive index.

[0017] In one alternative embodiment of this application, the refractive index of the silicone protective layer is 1.40~1.52.

[0018] The COB light source provided by this utility model includes a mirror substrate, multiple LED chips disposed in the light-emitting area in the middle of the mirror substrate, an insulating structure layer disposed in the edge area of ​​the mirror substrate, and a circuit structure layer disposed on the surface of the insulating structure layer facing away from the mirror substrate. The LED chips are vertical structure chips, and the bottom electrode of each LED chip is fixedly connected to the mirror substrate by conductive die-bonding adhesive; alternatively, the LED chips are flip-chip chips, and the positive and negative electrodes of each LED chip are fixedly connected to the mirror substrate by two mutually isolated conductive die-bonding adhesives. The LED chips are electrically connected to each other and to the circuit structure layer through conductive die-bonding adhesives and metal wires connected to the LED chips.

[0019] In the COB light source of this application, the LED chip can adopt two different chip structures: vertical structure chip and flip-chip structure chip. Furthermore, the electrode of the LED chip near the mirror substrate is bonded to the mirror substrate using conductive die-attach adhesive, and electrical connections between the LED chips are achieved using metal wires. In addition, the circuit structure layer is placed on an insulating structure layer surrounding the central light-emitting area, eliminating the need to place it on the mirror substrate. Similarly, electrical connections between the LED chip and the circuit structure layer are achieved using metal wires. Therefore, by using either vertical or flip-chip structure chips as the LED chip in this application, normal circuit connections of the LED chip can be achieved without forming pads or other circuit structures on the mirror substrate. This allows the COB light source to achieve the better heat dissipation of vertical structure chips or the high light output efficiency of flip-chip chips, while avoiding the difficulty of forming circuit structures on the mirror substrate; thus, to a certain extent, the working performance of the COB light source is improved. Attached Figure Description

[0020] To more clearly illustrate the technical solutions of the embodiments of this utility model or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0021] Figure 1 A top view of the COB light source provided in an embodiment of this application;

[0022] Figure 2 This is a cross-sectional structural diagram of a COB light source provided in an embodiment of this application;

[0023] Figure 3 Another cross-sectional structural diagram of the COB light source provided in the embodiments of this application;

[0024] In the attached diagram, 1 is a mirror substrate, 2 is an LED chip, 3 is an insulating structure layer, 4 is a circuit structure layer, 5 is a conductive die bond, 51 is a first conductive die bond, 52 is a second conductive die bond, 6 is a metal wire, 71 is a first color temperature fluorescent adhesive layer, 72 is a second color temperature fluorescent adhesive layer, and 8 is a silicone protective layer. Detailed Implementation

[0025] In conventional COB light sources, LED chips mostly adopt a positive-mount structure. A positive-mount structure means that the positive and negative electrodes are located on the upper surface of the LED chip on the side away from the mirror metal substrate. In this way, the LED chips can be electrically connected to each other through metal wires, etc. There is no need to form solder joints for electrical connection between the LED chips and the mirror surface of the mirror metal substrate, so there is no need to damage the mirror surface of the mirror metal substrate, and there is no problem of difficulty in forming circuit structures on the mirror surface.

[0026] However, besides upright LED chips, LED chips also include vertical and flip-chip chips. Vertical LED chips have the positive and negative electrodes located on the top and bottom surfaces of the LED chip, respectively, and have better heat dissipation compared to upright LED chips. In essence, the structural characteristics of flip-chip chips are not much different from those of upright LED chips, with the positive and negative electrodes located on the same side of the LED chip. The difference is that during installation, the surface with the positive and negative electrodes needs to be mounted downwards against the substrate, so that the top surface facing away from the substrate is completely unobstructed. Compared to upright LED chips, flip-chip LED chips have higher light output efficiency because the top surface is unobstructed.

[0027] As mentioned above, both vertical and flip-chip LEDs require mounting on a mirrored metal substrate to the side with electrodes. Based on the conventional mounting methods for vertical and flip-chip LEDs, pads for electrical connection to the electrodes need to be formed on the surface of the mirrored metal substrate. On one hand, the mirrored surface of the metal substrate is very smooth, making the pad formation process difficult. On the other hand, once pads are formed on the mirrored metal substrate, it is important to avoid damaging the mirrored surface, which could affect its reflective performance to some extent. Therefore, using vertical or flip-chip LEDs in COB light sources presents certain limitations, affecting the performance of the COB light source to some degree.

[0028] Therefore, this application provides a COB light source that can package vertical or flip-chip LED chips on a mirror substrate without forming pads on the mirror substrate and damaging the mirror substrate, thereby improving the working performance of the COB light source.

[0029] To enable those skilled in the art to better understand the present invention, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0030] like Figure 1 and Figure 3 As shown, Figure 1 A top view of the COB light source provided in an embodiment of this application; Figure 2 This is a cross-sectional structural diagram of a COB light source provided in an embodiment of this application. Figure 3 This is a schematic diagram of another cross-sectional structure of the COB light source provided in an embodiment of this application.

[0031] It should be noted that, in fact Figure 1 LED chip 2 should not be visible from a top-down view. Figure 1 In order to show the layout of LED chip 2, LED chip 2 is shown with its outline as a dashed line.

[0032] In one specific embodiment of this application, the COB light source may specifically include:

[0033] A mirror substrate 1, multiple LED chips 2 disposed in the light-emitting area in the middle of the mirror substrate 1, an insulating structure layer 3 disposed in the edge area of ​​the mirror substrate 1, and a circuit structure layer 4 disposed on the surface of the insulating structure layer 3 facing away from the mirror substrate 1.

[0034] Among them, the LED chip 2 is a vertical structure chip and the bottom electrode of each LED chip 2 is fixedly connected to the mirror substrate 1 through conductive die bond 5; or, the LED chip 2 is a flip structure chip and the positive and negative electrodes of each LED chip 2 are fixedly connected to the mirror substrate 1 through two mutually isolated conductive die bond 5.

[0035] Each LED chip 2 is electrically connected to the others, as well as to the circuit structure layer 4, through conductive die bond adhesive 5 and metal wires 6 connected to the LED chips 2.

[0036] like Figure 1As shown, the mirror substrate 1 in this embodiment can be a mirrored aluminum plate or a silver-plated substrate, etc., as long as it has a mirror surface with good reflective properties. Multiple LED chips 2 are arranged in a circular area in the center of the mirror substrate 1. The area where the LED chips 2 are distributed is also the central light-emitting area. The LED chips 2 can be arranged in an array, and the LED chips 2 together form a surface light source. The annular area surrounding the surface of the central light-emitting area is the edge area. An insulating structure layer 3 is provided covering this edge area, which is generally a BT resin (Bismaleimide Triazine Resin) insulating layer. Furthermore, on the side of the insulating structure layer 3 facing away from the mirror substrate 1, a circuit structure layer 4 is further formed on top of a layer of white glue. It should be noted that this circuit structure layer 4 is the circuit that realizes the electrical connection between the LED chips 2 and the external power supply circuit. Specifically, it can be a copper foil circuit structure layer 4, which can be formed on the upper surface of the insulating structure layer 3 by printing or other methods, and electrically connected to the LED chips 2.

[0037] Based on this, the LED chip 2 in this embodiment can be a vertical structure chip or a flip-chip chip. Regardless of the structure, the LED chip 2 has electrodes on the surface facing the mirror substrate 1. Therefore, in this application, several conductive connection points formed by conductive die-bonding adhesive 5 can be printed on the mirror substrate 1 according to the layout of the LED chip 2. This allows the surface of each LED chip 2 with electrodes to be fixedly connected to the mirror substrate 1 through the conductive die-bonding adhesive 5. In other words, the conductive die-bonding adhesive 5 not only acts as a connecting adhesive layer between the LED chip 2 and the mirror substrate 1, but also makes electrical connections with the electrodes of the LED chip 2. Thus, the electrical connections between each LED chip 2 and between the LED chip 2 and the circuit structure layer 4 can be realized through the metal wire 6 and the conductive die-bonding adhesive 5.

[0038] In this embodiment, the conductive die bond 5 can be a highly conductive silver paste, a thermosetting nano-conductive paste, or other adhesive layers with excellent conductivity and adhesion. The conductive die bond 5 can be uniformly applied to the light-emitting area by spraying, screen printing, dispensing, or other methods. The coating area should be 2 to 3 times larger than the bottom surface size of the LED chip 2 to be mounted, so as to ensure the formation of a complete and effective electrode contact surface and good current diffusion capability.

[0039] Therefore, the COB light source provided in this application can achieve circuit connection of the LED chip 2 without forming pads on the surface of the mirror substrate 1, based on the use of vertical or flip-chip LED chips 2. This allows the COB light source to have the characteristics of good heat dissipation of vertical LED chips 2 or high light output efficiency of flip-chip LED chips 2, while reducing the packaging difficulty of LED chips 2, ensuring the high reflectivity of the mirror substrate 1, and thus improving the overall working performance of the COB light source.

[0040] Based on the above discussion, for ease of understanding, the packaging structure of different types of LED chips 2 will be further described in detail based on specific embodiments.

[0041] like Figure 2 As shown, in an optional embodiment of this application, when the LED chip 2 in the COB light source is a vertical structure chip, the negative electrode of the LED chip 2 is fixedly connected to the surface of the mirror substrate 1 through the conductive die bond 5; among the two LED chips 2 that are electrically connected to each other, the positive electrode of one LED chip 2 is electrically connected to the conductive die bond 5 connected to the negative electrode of the other LED chip 2 through the metal wire 6.

[0042] exist Figure 2 In the illustrated embodiment, the LED chip 2 is a vertical structure chip, and the electrode on the surface of the LED chip 2 that is attached to the mirror substrate 1 is the negative electrode, while the electrode on the surface of the LED chip 2 that is away from the mirror substrate 1 is the positive electrode. For LED chips 2 connected in series, two adjacent LED chips 2 connected in series are electrically connected by a metal wire 6, that is, the conductive die-attach adhesive 5 connected to the positive electrode of one LED chip 2 and the negative electrode of another LED chip 2 are electrically connected, thereby realizing the electrical connection between the positive electrode of one LED chip 2 and the negative electrode of another LED chip 2. By analogy, multiple LED chips 2 can be connected in series to form a series circuit of LED chips 2. In this series circuit of LED chips 2, the positive electrode of one LED chip 2 can also be electrically connected to the circuit structure layer 4 through the metal wire 6, while the conductive die-attach adhesive 5 connected to the negative electrode of the other LED chip 2 can be electrically connected to the circuit structure layer 4, thereby realizing the electrical connection between a group of LED chips 2 and the circuit structure layer 4.

[0043] It should be noted that in practical applications, all LED chips 2 can be connected in series sequentially, and only the two LED chips 2 located at the end of the circuit and the positive and negative terminals in the circuit structure layer 4 are electrically connected respectively. Alternatively, each LED chip 2 can be divided into multiple groups, and each group of LED chips 2 can be connected in series sequentially to form a series circuit of LED chips 2. Each group of LED chip 2 series circuits is independently connected to the positive and negative terminals of the circuit structure layer 4. This application does not specifically limit this.

[0044] In addition, in this embodiment, the electrode of the LED chip 2 fixedly connected to the conductive die bond adhesive 5 and the mirror substrate 1 can also be the positive electrode. The negative electrode of one LED chip 2 is electrically connected to the negative electrode of another LED chip 2 through the conductive die bond adhesive 5 connected to the metal wire 6.

[0045] like Figure 3 As shown, in another optional embodiment of this application, when the LED chip 2 is a flip-chip, the positive and negative electrodes of the LED chip 2 are fixedly connected to the mirror substrate 1 through a first conductive die bond 51 and a second conductive die bond 52 that are mutually insulated; among the two LED chips 2 that are electrically connected to each other, the first conductive die bond 51 to which one LED chip 2 is connected is electrically connected to the second conductive adhesive to which the other LED chip 2 is connected through a metal wire 6.

[0046] Unlike the vertical structure LED chip 2 described above, the LED chip 2 in this embodiment is a flip-chip structure, meaning that both the positive and negative electrodes of the LED chip 2 are located near the lower surface of the mirror substrate 1. Therefore, this embodiment requires two conductive die-attach adhesives 5 for each LED chip 2. Thus, each LED chip 2 is fixedly connected by a first conductive die-attach adhesive 51 and a second conductive die-attach adhesive 52. The first conductive die-attach adhesive 51 is electrically connected to the positive electrode of the LED chip 2, while the second conductive die-attach adhesive 52 is electrically connected to the negative electrode of the LED chip 2. Furthermore, the first conductive die-attach adhesive 51 and the second conductive die-attach adhesive 52 should be mutually insulated. Specifically, an insulating structure can be provided between the first conductive die-attach adhesive 51 and the second conductive die-attach adhesive 52 connected to each LED chip 2; a transparent insulating adhesive can be used. Alternatively, a gap can be provided between the first conductive die-attach adhesive 51 and the second conductive die-attach adhesive 52 to prevent them from contacting each other, thereby ensuring mutual insulation.

[0047] Similar to the vertical structure chip described above, in this embodiment, the LED chips 2 can also be connected in series to form an LED chip 2 series circuit, and then the LED chip 2 series circuit and the circuit structure layer 4 are electrically connected. The electrical connection between the LED chips 2 can also be achieved using metal wires 6 and conductive die-attach adhesive 5. Specifically, between two adjacent electrically connected LED chips 2, the first conductive die-attach adhesive 51 connected to one LED chip 2 and the second conductive die-attach adhesive 52 connected to the other LED chip 2 can be electrically connected using metal wires 6. In a similar manner, multiple LED chips 2 can be connected in series. Similarly, the electrical connection between the LED chip 2 series circuit and the circuit structure layer 4 can be achieved by connecting the first conductive die-attach adhesive 51 and the second conductive die-attach adhesive 52 connected to the two LED chips 2 at both ends of the circuit to a metal conductor, and then connecting the positive and negative terminals of the circuit structure layer 4 through metal wires 6.

[0048] Obviously, in this embodiment, the metal wires 6 that connect each LED chip 2 in series are all led out from the bottom of each LED chip 2, and do not need to go around the top surface of the LED chip 2. This avoids the metal wires 6 blocking the output optical fiber of the LED chip 2, thereby ensuring the high-efficiency output of light from the LED chip 2 to a certain extent.

[0049] As discussed above, regardless of whether the LED chip 2 in this application is a vertical structure chip or a flip structure chip, it can be electrically connected to the circuit structure layer 4 through conductive die bond 5 and metal wires 6, and then electrically connected to the external power supply circuit through the circuit structure layer 4. There is no need to form solder pads on the mirror substrate 1, thus ensuring the high reflectivity of the mirror substrate 1.

[0050] Based on any of the above embodiments, in an optional embodiment of this application, the COB light source in this application may further include:

[0051] LED chip 2 includes a first color temperature chip and a second color temperature chip that are alternately distributed;

[0052] The first color temperature chip is wrapped with a first color temperature fluorescent adhesive layer 71, and the outer surface of the first color temperature fluorescent adhesive layer 71 is wrapped with a second color temperature fluorescent adhesive layer 72.

[0053] The second color temperature chip is covered with a second color temperature fluorescent adhesive layer 72, and the outer surface of the second color temperature fluorescent adhesive layer 72 is covered with a first color temperature fluorescent adhesive layer 71.

[0054] like Figure 2 and Figure 3As shown, in the COB light source of this application, each LED chip 2 may be further provided with a phosphor layer, and in order to obtain light formed by mixing multiple different colors of fluorescent light, at least two different colors of phosphor layers are stacked on each LED chip 2.

[0055] It is understandable that when the light output by LED chip 2 is used as excitation light to excite the phosphor particles in the phosphor layer, causing the phosphor to output fluorescent light of a specific wavelength, the light output by LED chip 2 is generally mostly blue light; and the wavelength of the blue light output by LED chip 2 is slightly different depending on the type of LED chip 2 and the power supply voltage; and correspondingly, the optimal wavelength of the excitation light is also different for different types of phosphor layers.

[0056] Based on this, the LED chip 2 in this embodiment includes a first color temperature chip and a second color temperature chip, and the phosphor layer disposed on the LED chip 2 includes a first color temperature phosphor layer 71 and a second color temperature phosphor layer 72; wherein, the blue light band output by the first color temperature chip after the voltage is turned on can more efficiently excite the first color temperature phosphor layer 71 to output first band light, and the blue light band output by the second color temperature chip after the voltage is turned on can more efficiently excite the second color temperature phosphor layer 72 to output second band light.

[0057] Based on this, a first color temperature fluorescent adhesive layer 71 is first wrapped around the first color temperature chip, and then a second color temperature fluorescent adhesive layer 72 is wrapped around the first color temperature fluorescent adhesive layer 71; while on the second color temperature chip, a second color temperature fluorescent adhesive layer 72 is first wrapped around the second color temperature fluorescent adhesive layer 72, and then a first color temperature fluorescent adhesive layer 71 is wrapped around the second color temperature fluorescent adhesive layer 72.

[0058] Therefore, in practical applications, the first color temperature chip can be a high color temperature chip, and the second color temperature chip can be a low color temperature chip. The light output from the first color temperature chip can efficiently excite the first color temperature phosphor layer 71 to output first-band light. The portion of the light output from the first color temperature chip that is not absorbed by the first color temperature phosphor layer 71, along with the first-band light, is incident on the second color temperature chip. While absorbing the light output from the first color temperature chip, the second color temperature chip also absorbs a few wavelengths of light in the first-band light, thereby outputting second-band light. The second-band light and the first-band light are mixed to output a mixed light of the two bands. Thus, the light output based on the excitation of the first color temperature chip is a mixture of the first-band light and the second-band light, but the first-band light may have a few missing wavelengths.

[0059] Similarly, when the light output by the second color temperature chip can efficiently excite the second color temperature phosphor layer 72 to output the second band light, and then excite the first color temperature phosphor layer 71 to output the first band light, obviously a few wavelengths of light in the second band light may also be absorbed by the first color temperature phosphor layer 71. The light output by the second color temperature chip is also a mixture of the first band light and the second band light, but a few wavelengths of the second band light may be missing.

[0060] Based on this, when the first and second color temperature chips operate simultaneously, the mixed light emitted by the two chips mixes and complements each other, forming mixed light with better spectral continuity and improving the final color rendering index of the light source. Furthermore, although both the first and second color temperature chips can ultimately output mixed light of two wavelengths, their excitation efficiencies for the two phosphor layers are clearly different. Therefore, the brightness ratio between the first and second wavelengths of light output by each chip is not entirely the same, and the wavelength ranges between the first and second wavelengths may also differ slightly. However, the combined output of the mixed light from the first and second color temperature chips, respectively, also complements each other in terms of color brightness, improving the performance of the COB light source.

[0061] In an optional embodiment of this application, both the first color temperature chip and the second color temperature chip can be LED chips that output blue excitation light. The first color temperature chip is a high color temperature chip with higher output light brightness, while the second color temperature chip is a low color temperature chip with relatively weaker output light brightness. The first color temperature phosphor layer 71 can be a green phosphor layer (i.e., its phosphor is excited to output green light), and the second color temperature phosphor layer 72 can be a red phosphor layer (i.e., its phosphor is excited to output red light). That is to say, a green phosphor layer is first covered on the high color temperature chip, and then a red phosphor layer is covered on the green phosphor layer.

[0062] When the high color temperature chip is powered on, the high color temperature blue excitation light output can first excite the green phosphor layer. The generated green fluorescence and unabsorbed blue light will be incident on the red phosphor layer and further absorbed. Since the red phosphor layer has a wider excitation band, there is a significant reabsorption phenomenon of green fluorescence, which causes a certain loss of brightness of green fluorescence.

[0063] When the low color temperature chip is powered on, the low color temperature blue excitation light it outputs can first excite the red phosphor layer. The resulting red fluorescence and unabsorbed blue light will then be incident on the green phosphor layer and further absorbed. However, the green phosphor layer does not reabsorb the red fluorescence. On the contrary, the green fluorescence it outputs can, to some extent, supplement the missing green light portion in the fluorescence output from the high color temperature chip, ensuring the continuity of the spectrum. In addition, the thickness of the red phosphor layer on the low color temperature chip can be relatively thinner to avoid the problem of it absorbing too much blue light energy.

[0064] Furthermore, in this embodiment, the first color temperature chips can be connected in series with each other; the second color temperature chips can also be connected in series with each other; and the first and second color temperature chips are independently electrically connected to the circuit structure. Therefore, in practical applications, the first and second color temperature chips can operate independently. Only the first color temperature chip can be connected to the power supply voltage, so that the COB light source only outputs the mixed light excited by the first color temperature chip; or only the second color temperature chip can be connected to the power supply voltage, so that the COB light source only outputs the mixed light excited by the second color temperature chip. Of course, this embodiment does not exclude the possibility that the first and second color temperature chips are simultaneously connected to the power supply voltage, thereby outputting the mixed light excited by both the first and second color temperature chips. In summary, this embodiment can output light with slightly different colors in different wavelength ranges of the same color mixed beam, i.e., outputting gradient color light, to meet the personalized needs of users, based entirely on the actual application requirements.

[0065] Based on the above discussion, in another optional embodiment of this application, the central light-emitting area of ​​the mirror substrate 1 is further covered by a silicone protective layer 8 to protect the LED chip 2. The silicone protective layer 8 may include multiple layers stacked sequentially, and the refractive index of each silicone protective layer 8 increases progressively from the mirror substrate 1 away from it. This results in a gradual increase in the refraction angle and divergence angle of the light emitted after passing through each silicone protective layer 8, which is beneficial for the thorough mixing of light emitted by different LED chips 2 and improves the uniformity of the final output light color.

[0066] Furthermore, in this embodiment, the refractive index of the silicone protective layer 8 covering the central light-emitting area of ​​the mirror substrate 1 can be in the range of 1.40 to 1.52; taking the stacking of three silicone protective layers 8 in the central light-emitting area of ​​the mirror substrate 1 as an example, the refractive indices of the three silicone protective layers 8 can be 1.40, 1.45, and 1.51 respectively.

[0067] In summary, in the COB light source of this application, the LED chip can adopt two different chip structures: vertical structure chip and flip-chip structure chip. Furthermore, the electrode of the LED chip near the mirror substrate is bonded to the mirror substrate using conductive die-attach adhesive, and electrical connections between the LED chips are achieved using metal wires. Additionally, the circuit structure layer is placed on the insulating structure layer surrounding the central light-emitting area, eliminating the need to place it on the mirror substrate. Similarly, electrical connections between the LED chip and the circuit structure layer are achieved using metal wires. Therefore, by using vertical or flip-chip structure chips as LED chips in this application, normal circuit connections of the LED chips can be achieved without forming pads or other circuit structures on the mirror substrate. This allows the COB light source to possess the advantages of good heat dissipation of vertical structure chips or high light output efficiency of flip-chip chips, while avoiding the difficulty of forming circuit structures on the mirror substrate; thus, to a certain extent, the working performance of the COB light source is improved.

[0068] It should be noted that, in this document, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that the elements inherent in a process, method, article, or apparatus that includes a list of elements are included. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element. Additionally, portions of the technical solutions provided in the embodiments of this application that are consistent with the implementation principles of corresponding technical solutions in the prior art have not been described in detail to avoid excessive elaboration.

[0069] This article uses specific examples to illustrate the principles and implementation methods of this utility model. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of this utility model. It should be noted that for those skilled in the art, several improvements and modifications can be made to this utility model without departing from the principles of this utility model, and these improvements and modifications also fall within the protection scope of the claims of this utility model.

Claims

1. A COB light source, characterized in that, It includes a mirror substrate, multiple LED chips disposed in the light-emitting area in the middle of the mirror substrate, an insulating structure layer disposed in the edge area of ​​the mirror substrate, and a circuit structure layer disposed on the surface of the insulating structure layer facing away from the mirror substrate. Wherein, the LED chip is a vertical structure chip and the bottom electrode of each LED chip is fixedly connected to the mirror substrate by conductive die bond adhesive; or, the LED chip is a flip structure chip and the positive and negative electrodes of each LED chip are fixedly connected to the mirror substrate by two mutually isolated conductive die bond adhesives respectively. Each of the LED chips and the circuit structure layer are electrically connected to each other through the conductive die bond adhesive and metal wires connected to the LED chips.

2. The COB light source as described in claim 1, characterized in that, When the LED chip is a vertical structure chip, the negative electrode of the LED chip is fixedly connected to the surface of the mirror substrate through the conductive die bond adhesive; in two LED chips that are electrically connected to each other, the positive electrode of one LED chip is electrically connected to the conductive die bond adhesive connected to the negative electrode of the other LED chip through the metal wire.

3. The COB light source as described in claim 1, characterized in that, When the LED chip is a flip-chip, the positive and negative terminals of the LED chip are fixedly connected to the mirror substrate through a first conductive die bond and a second conductive die bond that are mutually insulated; among the two LED chips that are electrically connected to each other, the first conductive die bond connected to one LED chip is electrically connected to the second conductive die bond connected to the other LED chip through the metal wire.

4. The COB light source as described in claim 1, characterized in that, The circuit structure layer is a copper foil circuit structure layer; the insulation structure layer is a BT insulation layer; and the mirror substrate is a mirror aluminum plate or a silver-plated substrate.

5. The COB light source as described in claim 1, characterized in that, The conductive die-bonding adhesive is a conductive silver paste or a nano-conductive paste.

6. The COB light source according to any one of claims 1 to 5, characterized in that, The LED chip includes a first color temperature chip and a second color temperature chip that are alternately distributed. The first color temperature chip is coated with a first color temperature fluorescent adhesive layer, and a second color temperature fluorescent adhesive layer is coated on the outer surface of the first color temperature fluorescent adhesive layer. The second color temperature chip is coated with a second color temperature fluorescent adhesive layer, and the outer surface of the second color temperature fluorescent adhesive layer is coated with the first color temperature fluorescent adhesive layer.

7. The COB light source as described in claim 6, characterized in that, Each of the first color temperature chips is connected in series with each other; each of the second color temperature chips is connected in series with each other; the first color temperature chip and the second color temperature chip are independently electrically connected to the circuit structure.

8. The COB light source as described in claim 5, characterized in that, The central light-emitting area of ​​the mirror substrate is also covered with a silicone protective layer.

9. The COB light source as described in claim 8, characterized in that, The silicone protective layer comprises multiple layers of silicone protective layers stacked sequentially with increasing refractive index.

10. The COB light source as described in claim 8, characterized in that, The refractive index of the silicone protective layer is 1.40~1.52.

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