High-voltage flip-chip LED light source

Abstract

The present invention discloses a high-voltage flip-chip LED light source, which comprises a heat-conducting substrate and a high-voltage flip-chip LED chip. An electrode is provided on the first surface of the chip, and the second surface is a light-emitting surface. The first surface and the second surface are arranged opposite to each other. At least one convex platform is formed on the surface of the heat-conducting substrate, and the first surface of at least one of the chips is connected to the top surface of one of the convex platforms through a heat-conducting insulating bonding adhesive. The chip comprises an electrode region and a light-emitting region, and the electrode region and the light-emitting region are arranged at intervals. In the high-voltage flip-chip LED light source of the present invention, the chip can be seamlessly combined with the substrate, and the problem that the bonding adhesive overflows to the conductive electrode can be avoided, so that the effectiveness of electrical connection can be ensured, the heat dissipation uniformity of the LED flip-chip can be enhanced, and at the same time, the adopted LED chip is a single-chip integrated high-power high-voltage flip-chip LED chip, which has the characteristics of good stability, high anti-failure rate and high area utilization rate.

Description

Technical Field

[0001] The present invention relates to a packaging structure of an LED, and particularly to a high-voltage flip-chip LED light source, belonging to the field of semiconductor technology. Background Art

[0002] Compared with a front-mounted chip, a flip-chip has the advantages of lower thermal resistance, better light extraction, no need for gold wires, better integration, and simpler manufacturing. At present, due to technical limitations, in order to ensure the yield of chips, industrial-level flip-chip LED chips generally have the characteristics of small power, small area, and low integration. These characteristics have greatly restricted the application of flip-chip LEDs, resulting in a blank in the flip-chip LED market. To fill this blank and expand the application range of flip-chip LEDs, it is urgent to obtain high-power high-voltage integrated flip-chip LED chips that can be used industrially. However, at present, high-power high-voltage integrated flip-chips face multiple technical problems during packaging, such as: the problem that the insulating connection glue overflows and affects the conductivity of the electrodes; and the thermal conduction and insulation problem between the light-emitting area of the chip and the substrate. However, the industry has not been able to explore effective solutions. Summary of the Invention

[0003] The main purpose of the present invention is to provide a high-voltage flip-chip LED light source to overcome the deficiencies in the prior art.

[0004] To achieve the foregoing invention purpose, the technical solutions adopted by the present invention include:

[0005] An embodiment of the present invention provides a high-voltage flip-chip LED light source, including a heat-conducting substrate and a high-voltage flip-chip LED chip. The first surface of the LED chip has an electrode, and the second surface is a light-emitting surface. The first surface and the second surface are arranged opposite to each other. At least one convex platform is formed on the surface of the heat-conducting substrate, and the first surface of at least one LED chip is connected to the top surface of one of the convex platforms through a thermally conductive insulating connection glue.

[0006] In some more preferred embodiments, the high-voltage flip-chip LED chip is a monolithic integrated high-power high-voltage flip-chip LED chip. The LED chip includes an electrode region and a light-emitting region. The electrode region and the light-emitting region are arranged at intervals. The light-emitting region includes a plurality of independently light-emitting unit cells. The plurality of unit cells are connected in series and / or in parallel, and the plurality of unit cells are electrically connected to the electrode region.

[0007] In some more preferred embodiments, the distance between the light-emitting region and the electrode region satisfies the following condition: during the process of connecting the first surface of the LED chip to the top surface of the convex platform through the thermally conductive insulating connection glue, no thermally conductive insulating connection glue overflows to the surface of the electrode region.

[0008] Compared with the prior art, the present invention has at least the following beneficial effects: In the provided high-voltage flip-chip LED light source, the LED flip-chip can be seamlessly combined with the substrate, and the problem of the connection glue overflowing to the conductive electrode can be avoided. Thus, both the effectiveness of the electrical connection can be ensured, and the heat dissipation uniformity of the LED flip-chip can be enhanced. At the same time, the flip-chip LED chip adopted is a monolithic integrated high-power high-voltage flip-chip LED chip, which has characteristics such as good stability and high anti-failure rate. The special position design of the electrode region and the light-emitting region can effectively improve the area utilization rate of the chip, maximize the area of the light-emitting region, and also ensure that the thermally conductive insulating layer material does not overflow to the electrode surface during packaging and that the solder does not overflow to the light-emitting region to cause a short circuit. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Figure 1 FIG. is a schematic structural diagram of an existing flip-chip LED light source.

[0010] Figure 2 FIG. is a schematic diagram of an existing flip-chip LED light source.

[0011] Figure 3 FIG. is a schematic diagram of a high-voltage flip-chip LED light source in the first embodiment of the present invention.

[0012] Figure 4 FIG. is a schematic structural diagram of a high-voltage flip-chip LED chip in the first embodiment of the present invention.

[0013] Figure 5 FIG. is a schematic diagram of a high-voltage flip-chip LED light source in the second embodiment of the present invention.

[0014] Figure 6 FIG. is a schematic diagram of a high-voltage flip-chip LED light source in the third embodiment of the present invention.

[0015] Figure 7 FIG. is a schematic diagram of a high-voltage flip-chip LED light source in the fourth embodiment of the present invention.

[0016] Figure 8 FIG. is a schematic diagram of a high-voltage flip-chip LED light source in the fifth embodiment of the present invention.

[0017] Figure 9 FIG. is a schematic structural diagram of a high-voltage flip-chip LED chip in an embodiment of the present invention.

[0018] Figure 10 FIG. is a schematic structural diagram of a high-voltage flip-chip LED chip in another embodiment of the present invention.

[0019] Figure 11 FIG. is a schematic structural diagram of a high-voltage flip-chip LED chip in yet another embodiment of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0020] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments recorded in the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0021] Furthermore, it should be noted that in this specification, relational terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the term "comprising", "including" or any other variant thereof is intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements not only includes those elements, but also includes other elements not expressly listed, or also includes elements inherent to such process, method, article or device. Without further limitation, the element defined by the statement "including at least one..." does not exclude the existence of additional identical elements in the process, method, article or device including the said element.

[0022] One aspect of the embodiments of the present invention provides a high-voltage flip-chip LED light source, which includes a heat-conducting substrate and a high-voltage flip-chip LED chip. The first surface of the LED chip has an electrode, and the second surface is a light-emitting surface. The first surface and the second surface are arranged opposite to each other. At least one convex platform is formed on the surface of the heat-conducting substrate, and the first surface of at least one of the LED chips is connected to the top surface of one of the convex platforms through a thermally conductive insulating adhesive.

[0023] Furthermore, a thermally conductive insulating layer is further covered on the top surface of the convex platform, and the first surface of the LED chip is connected to the thermally conductive insulating layer through a thermally conductive insulating adhesive.

[0024] Among them, the thermally conductive insulating layer is formed of a thermally conductive insulating material. And, the thermally conductive insulating layer is transferred from the outside, or at least the thermally conductive insulating layer is integrally formed on the top surface of the convex platform.

[0025] Furthermore, the material of the heat-conducting substrate includes a conductive and heat-conducting metal material, and the conductive and heat-conducting metal material includes copper or aluminum, etc., and is not limited thereto.

[0026] Furthermore, the thermally conductive insulating layer is a dense thermally conductive insulating passivation layer formed by chemically treating the surface of the heat-conducting substrate.

[0027] Furthermore, the whole heat-conducting substrate or the convex platform is formed of a thermally conductive insulating material.

[0028] Further, the thermally conductive insulating material includes any one of oxides, nitrides, and carbides, and is not limited thereto.

[0029] For example, the oxides include aluminum oxide, copper oxide, etc., the nitrides include aluminum nitride, silicon nitride, beryllium nitride, etc., and the carbides include silicon carbide, etc., but are not limited thereto.

[0030] Further, the high-voltage flip-chip LED chip is a monolithic integrated high-power high-voltage flip-chip LED chip. The LED chip includes an electrode region and a light-emitting region. The electrode region and the light-emitting region are arranged at intervals. The light-emitting region includes a plurality of independently light-emitting unit cells. The plurality of unit cells are connected in series and / or in parallel, and the plurality of unit cells are electrically connected to the electrode region.

[0031] Further, a gas storage space is also distributed in the LED chip. The gas storage space includes a groove structure formed between the unit cells.

[0032] Further, the LED chip has more than one set of electrode regions. Each set of electrode regions includes two symmetrically arranged electrode regions. The electrode region is a triangular structure or a linear structure.

[0033] Preferably, the LED chip has a set of electrode regions, and the set of electrode regions are two symmetrically arranged triangular electrode regions.

[0034] Further, a hard conductive material (such as a metal sheet, a metal wire, etc., and is not limited thereto) is bonded to the electrode region of the LED chip. The hard conductive material is electrically connected to the conductive circuit on the substrate through silver paste or an electrical welding material.

[0035] Further, the distance between the light-emitting region and the electrode region satisfies the following condition: during the process of connecting the first surface of the LED chip to the top surface of the boss through a thermally conductive insulating adhesive, no thermally conductive insulating adhesive overflows onto the surface of the electrode region.

[0036] Hereinafter, the technical solutions of the present invention will be further explained and illustrated in conjunction with several embodiments and the accompanying drawings.

[0037] Please refer to Figure 3Shown is a high-voltage flip-chip LED light source in the first embodiment of the present invention, which includes a heat-conducting substrate 1 (hereinafter also simply referred to as "substrate") and a high-voltage flip-chip LED chip 2 (hereinafter also simply referred to as "chip" or "LED chip"). The first surface 201 of the LED chip has an electrode, and the second surface 202 is the light-emitting surface. The first surface and the second surface are arranged opposite to each other. One or more bosses 11 are formed on the surface of the heat-conducting substrate. The first surface of one of the LED chips is connected to the top surface of one of the bosses through a heat-conducting insulating connection glue 3 (hereinafter simply referred to as "connection glue").

[0038] Further, the aforementioned boss should match the size of the light-emitting area of the LED chip and have a certain height.

[0039] Furthermore, the aforementioned high-voltage flip-chip LED chip is a monolithic integrated high-power high-voltage flip-chip LED chip. The LED chip includes an electrode region and a light-emitting region. The electrode region and the light-emitting region are arranged at intervals. The light-emitting region includes a plurality of independently light-emitting unit cells. The plurality of unit cells are connected in series and / or in parallel, and the plurality of unit cells are electrically connected to the electrode region.

[0040] Please refer to Figure 4 As shown, in the aforementioned high-voltage flip-chip LED chip 2, each unit cell can be electrically connected through an interconnecting metal layer 26 formed on the first surface of the chip. To ensure the reliability of the electrical connection, an insulating dielectric layer 25 can also be provided on the first surface of the chip. A typical chip 2 can include a substrate 21 (such as a sapphire substrate) and an epitaxial structure formed on the substrate. The epitaxial structure can include an N-type GaN layer 22, a light-emitting region 23, a P-type GaN layer 24, etc.

[0041] The aforementioned unit cell is an independent and complete functional device unit processed in the epitaxial structure, and the conductive semiconductor layers of any two unit cells are isolated from each other, making any unit cell electrically independent; through metal interconnection, a plurality of unit cells are electrically connected to form the monolithic integrated high-power high-voltage flip-chip LED chip.

[0042] Preferably, the substrate can be "wafer-level", that is, the diameter of the substrate is more than 2 inches. Correspondingly, the monolithic integrated high-power high-voltage flip-chip LED chip can also be considered a wafer-level device.

[0043] The material of the aforementioned substrate includes aluminum nitride, silicon nitride, beryllium nitride, alumina, silicon carbide, etc., and is not limited thereto.

[0044] Preferably, a phosphor layer 27 can also be covered on the light-emitting surface of the aforementioned LED chip to achieve the conversion of the chip light-emitting wavelength, for example, to achieve a white light LED chip.

[0045] On the surface of the aforementioned heat-conducting substrate 1, there is also a conductive structure 12 formed by solder or silver paste for electrically connecting with the electrodes of the aforementioned chip 2. These conductive structures 12 can be electrically connected to an external power supply etc. through leads 13. Similarly, to ensure the reliability of the electrical connection, an insulating layer 14 can also be provided on the surface of the substrate.

[0046] When manufacturing the aforementioned high-voltage flip-chip LED light source, the aforementioned LED chip can be bonded to the heat-conducting substrate. To ensure there is no gap between the LED chip and the heat-conducting substrate, it is necessary to let the connecting glue overflow slightly. However, if the connecting glue flows to the conductive electrodes, it will affect the electrical connection. In the existing LED packaging structure, generally, grooves are made on the heat-conducting substrate. However, when the chip is bonded, the air in the grooves cannot be discharged, which will generate a large number of bubbles and seriously affect the heat dissipation uniformity of the chip. Therefore, the method of using a boss to store glue is adopted. When the chip is bonded to the substrate, the gas is discharged to the surroundings, and the excess connecting glue flows down along the side of the boss and accumulates around the boss under the action of force. At the same time, it does not affect the electrical connection.

[0047] Furthermore, please refer back to Figure 4 As shown, the groove-like structure formed between the unit cells in the aforementioned LED chip can also be used as a gas storage space. In this way, when the chip is connected to the substrate with the connecting glue, the gas in the connecting glue can be discharged into this gas storage space, reducing or eliminating the possible bubbles therein, thereby further enhancing the connection reliability between the chip and the substrate.

[0048] For comparison, please refer to Figure 2 As shown, in an existing flip-chip LED light source, the light-emitting surface of the chip 2' is a continuous plane, that is, there is no Figure 4 As shown in the gas storage space of the LED chip, therefore, in its packaging structure, the gas etc. in the connecting glue 3' cannot be released and are distributed in the connecting glue in the form of bubbles 31'. On the one hand, this will affect the bonding strength between the chip and the substrate, and on the other hand, it will also greatly reduce the heat dissipation efficiency.

[0049] Please refer to Figure 5 Shown is a high-voltage flip-chip LED light source in the second embodiment of the present invention, which has a similar structure to the aforementioned first embodiment. The difference is that the aforementioned substrate 1 can be made of heat-conducting and electrically conductive metal materials such as copper and aluminum, and an additional layer of heat-conducting and insulating ceramic is added on the boss as the heat-conducting and insulating layer 4. In this way, the choice of the substrate can be more free, and the heat-conducting performance can be given priority. At the same time, there is no need to consider the insulation of the connecting glue, which reduces the thickness of the connecting glue and is beneficial to heat conduction. The heat-conducting and insulating ceramic can include aluminum nitride etc., and is not limited thereto.

[0050] Please refer to Figure 6Fig. 0 shows a high-voltage flip-chip LED light source in the third embodiment of the present invention, which has a similar structure to the aforementioned first embodiment. The difference is that the aforementioned substrate 1 can be made of heat-conducting and electrically-conducting metal materials such as copper and aluminum. Through a chemical reaction, a dense heat-conducting and insulating passivation layer 5 can be directly generated on the convex platform of the substrate as the heat-conducting and insulating layer. The aforementioned chemical reaction can be an oxidation reaction or the like, and is not limited thereto. In this way, the selection of the substrate can be made more freely, and the heat-conducting performance can be given priority. At the same time, the insulation of the connecting glue does not need to be considered, so that the thickness of the connecting glue is greatly reduced, which is beneficial to heat conduction. Moreover, the thickness of the passivation layer 5 can reach several micrometers, which can well meet the requirements of heat conduction and insulation. Of course, the aforementioned passivation layer can also be deposited on the surface of the substrate by other chemical deposition or physical deposition methods, such as CVD, PECVD, PVD, ALD, etc. The material thereof can include aluminum nitride, silicon nitride, beryllium nitride, aluminum oxide, silicon carbide, etc., and is not limited thereto.

[0051] In the aforementioned first to third embodiments, a phosphor layer is pre-coated on the light-emitting surface of the LED chip, so it can be considered as a chip-type phosphor layer encapsulation structure. In the fourth embodiment of the present invention, another optimized solution can be adopted, that is, please refer to Figure 7 as shown in the figure. First, a high-voltage flip-chip LED chip can be fabricated; then, referring to the aforementioned embodiment, the chip is pasted onto the substrate to electrically connect the chip to the substrate. Then, a phosphor layer 28 is coated on the surface of the chip, and then external leads are connected. Thus, the so-called "substrate-type phosphor layer encapsulation structure" is realized. The advantage of this encapsulation method is that the process is simple and the cost is low.

[0052] In the fifth embodiment of the present invention, another optimized solution can also be adopted, that is, please refer to Figure 8 as shown in the figure. A hard conductive material 6 (metal sheet or metal wire) is added to the chip electrode region, which is equivalent to the extension of the electrode. Then, the hard conductive material 6 is connected to the substrate 1 with silver paste or an electrical welding material 7. The advantage of this method is that it ensures the electrical connection between the chip and the substrate. When pasting the chip, there is no need to consider the problem of insulation between the chip and the substrate caused by the overflow of the connecting glue, reducing the distance between the chip electrode region and the light-emitting region, and improving the chip area utilization rate.

[0053] The aforementioned high-voltage flip-chip LED chip 2 can have Figure 9The structure shown. There is a certain distance between the light-emitting region 203 and the electrode region 204. This ensures that the thermally insulating layer material does not overflow onto the electrode surface during encapsulation, causing electrode open circuit, and at the same time ensures that the solder does not overflow onto the light-emitting region, causing short circuit. The light-emitting region 203 is composed of several of the aforementioned unit cells, and the unit cells can adopt the series-parallel structure as shown in the figure. The characteristics of this structure are as follows: If a unit cell is short-circuited, the parallel stage fails. Since the LED is driven by constant current, the other stages of the chip can still work normally. If a unit cell is open-circuited, the remaining unit cells in this parallel stage share the excess current, and this stage can still work normally. Therefore, the chip as a whole can still work normally. This structure is beneficial to improving the chip's anti-failure rate. In addition, the Figure 9 In the structure shown, the electrode region is a triangular structure. This is beneficial to increasing the area of the light-emitting region and improving the chip utilization rate. This chip adopts a monolithic integration technology, without the need for die separation and wire bonding processes, saving costs and improving the area utilization rate.

[0054] The aforementioned high-voltage flip-chip LED chip 2 can also have Figure 10 , Figure 11 the structure shown. Of course, the Figure 9 structure shown is the optimal one because designing the electrode region as a triangle can effectively improve the chip's area utilization rate and maximize the area of the light-emitting region.

[0055] It should be understood that the above embodiments are only used to illustrate the technical concept and characteristics of the present invention, and the purpose is to enable those who are familiar with this technology to understand the content of the present invention and implement it accordingly. It cannot be used to limit the protection scope of the present invention. Any equivalent changes or modifications made according to the spirit and essence of the present invention should be covered within the protection scope of the present invention.

Claims

1. A high-voltage flip-chip LED light source, characterized in that, Comprising: A high-voltage flip-chip LED chip, which is a monolithic integrated high-power high-voltage flip-chip LED chip and includes an electrode region and a light-emitting region. The electrode region and the light-emitting region are spaced apart. The light-emitting region includes a plurality of independently light-emitting unit cells. The plurality of unit cells are connected in series and / or in parallel. The plurality of unit cells are electrically connected to the electrode region. And the LED chip has a first surface and a second surface facing each other. The first surface has an electrode. The second surface is a light-emitting surface. And a gas storage space is also distributed in the LED chip. The gas storage space includes a groove-like structure formed between the unit cells; A heat-conducting substrate, on the surface of which at least one boss is formed. The first surface of one LED chip is connected to the top surface of one boss through a thermally conductive insulating adhesive. The boss is sized to match the light-emitting region of the LED chip; And, the distance between the light-emitting region and the electrode region satisfies the following condition: during the process of connecting the first surface of the LED chip to the top surface of the boss through the thermally conductive insulating adhesive, no thermally conductive insulating adhesive overflows onto the surface of the electrode region; The gas storage space is used to accommodate the gas discharged from the thermally conductive insulating adhesive.

2. The high-voltage flip-chip LED light source according to claim 1, wherein: A thermally conductive insulating layer is further covered on the top surface of the boss. The first surface of the LED chip is connected to the thermally conductive insulating layer through a thermally conductive insulating adhesive; wherein, the thermally conductive insulating layer is formed of a thermally conductive insulating material, and the thermally conductive insulating layer is transferred from the outside, or the thermally conductive insulating layer is at least integrally formed on the top surface of the boss.

3. The high-voltage flip-chip LED light source according to claim 2, wherein: The material of the heat-conducting substrate includes a conductive and heat-conducting metal material. The conductive and heat-conducting metal material includes copper or aluminum.

4. The high-voltage flip-chip LED light source according to claim 2, wherein: The thermally conductive insulating layer is a dense thermally conductive insulating passivation layer formed by chemically treating the surface of the heat-conducting substrate.

5. The high-voltage flip-chip LED light source according to claim 1, wherein: The whole heat-conducting substrate or the boss is formed of a thermally conductive insulating material.

6. The high-voltage flip-chip LED light source according to claim 2 or 5, characterized in that: The thermally conductive insulating material includes any one of oxides, nitrides, and carbides; the oxides include aluminum oxide or copper oxide, the nitrides include aluminum nitride, silicon nitride, or beryllium nitride, and the carbides include silicon carbide.

7. The high-voltage flip-chip LED light source according to claim 1, characterized in that: The LED chip has more than one set of electrode regions. Each set of electrode regions includes two symmetrically arranged electrode regions. The electrode region is in a triangular structure or a linear structure.

8. The high-voltage flip-chip LED light source according to claim 1, characterized in that: A hard conductive material is combined on the electrode region of the LED chip. The hard conductive material is electrically connected to the conductive circuit on the substrate through silver paste or an electrical welding material.

9. The high-voltage flip-chip LED light source according to claim 1, characterized in that: The LED chip has a set of electrode regions. The set of electrode regions are two symmetrically arranged triangular electrode regions.

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