Micro-LED chip module of flip-chip technology and manufacturing method of Micro-LED chip module

Abstract

The invention relates to the field of LED chips, in particular to an inverted Micro-LED chip module and a manufacturing method thereof.The inverted Micro-LED chip module comprises a circuit board, a lap joint substrate is arranged on the surface of the top of the circuit board, and air holes are formed in the surface of the bottom of the lap joint substrate; a heightening strip is arranged on the inner side wall face of the lap joint base plate and located at the edge of the bottom, and a heat absorption copper strip is arranged on the surface of one side of the heightening strip. When the Micro-LED chips are stacked on the inner side wall face of the lap-joint substrate, multi-angle heightening supporting is carried out on the peripheral edge positions of the bottoms of the Micro-LED chips in cooperation with the heightening strips and the heightening columns, so that a cavity is formed between the middle positions of the bottoms of the Micro-LED chips and the inner side wall face of the lap-joint substrate, and when the Micro-LED chips are powered on to run, the Micro-LED chips are not prone to falling off from the lap-joint substrate. And a heat source generated in the Micro-LED chip can be accumulated in the cavity.

Description

Technical Field

[0001] The present invention belongs to the technical field of LED chips, and specifically relates to a flip-chip Micro-LED chip module and a manufacturing method thereof. Background Art

[0002] The flip-chip Micro-LED uses a reflective p-electrode to reflect the light emitted from the active area to the sapphire surface. Compared with the horizontal structure, it can effectively improve the light output efficiency of the chip. The light generated from the active area of the flip-chip Micro-LED chip will be totally reflected at the interface between the sapphire and the air after entering the sapphire substrate until it is absorbed by the chip and converted into heat energy. This also greatly limits the front light output of the flip-chip Micro-LED chip.

[0003] Patent publication number CN117153956A discloses a flip-chip Micro-LED chip and its fabrication method. The method comprises sequentially growing an n-type AlGaN layer, a multi-quantum well active region layer, a p-type AlGaN layer, and a p-type GaN layer on the surface of a sapphire cell; the sapphire cell is provided with orderly arranged pores; the p-type GaN layer, the p-type AlGaN layer, the multi-quantum well active region layer, and the n-type AlGaN layer are then etched. After etching, the n-type AlGaN layer forms a mesa structure with a bottom, a shoulder, and an upper protrusion. An n-type electrode is formed on the shoulder of the etched n-type AlGaN layer, and a p-type electrode is formed on the surface of the etched p-type GaN layer. A solder pad is used to connect the n-type and p-type electrodes, and a corrugated pattern is formed on the other side of the sapphire cell, resulting in a flip-chip Micro-LED chip. The present invention uses a high-reflectivity, low-resistance Ni / Rh / Ni / Au electrode to form a good ohmic contact with the p-type GaN, creating the orderly arranged pores and corrugated pattern. This reduces the voltage of the flip-chip Micro-LED chip and enhances the light extraction efficiency, resulting in a high-efficiency flip-chip Micro-LED chip.

[0004] In the current existing technology, the power of a single LED tube on the market is usually 1-5W, and the light output is only a few hundred lumens. To truly apply LEDs on a large scale to public places such as road lighting, the luminous flux of the LED light source must reach thousands or even tens of thousands of lumens. Such a high light output will generate a lot of heat internally. However, for high-power LED multi-core integrated light source modules, they still face the problems of slow heat dissipation and serious vulcanization.

[0005] To this end, the present invention provides a flip-chip Micro-LED chip module and a manufacturing method thereof Summary of the Invention

[0006] In order to make up for the deficiencies of the prior art, at least one technical problem raised in the background technology is solved.

[0007] In the first aspect, the technical solution adopted by the present invention to solve its technical problems is: the Micro-LED chip module of the flip-chip process described in the present invention includes a circuit board, a bonding substrate is provided on the top surface of the circuit board, and a ventilation hole is opened on the bottom surface of the bonding substrate. A padding strip is provided on the inner wall surface of the bonding substrate and located at the bottom edge position, and a heat-absorbing copper strip is provided on one side surface of the padding strip. The inner wall surface of the bonding substrate is fixedly connected with padding columns at the four corners, and the Micro-LED chip is movably sleeved inside the bonding substrate.

[0008] Preferably, a tin bar is provided at the junction of the top surface of the circuit board and the overlapping substrate, and snap-in slots are provided on the top surface of the overlapping substrate and at the four edges thereof, and the bottom surface of the overlapping substrate is movably overlapped on the top surfaces of the raising strips, raising columns and heat-absorbing copper strips.

[0009] Preferably, a closing cover is movably overlapped on the top surface of the overlapping base plate, a docking head is fixedly connected to the bottom surface of the closing cover, and the outer surface of the docking head is movably mounted on the inner wall of the clamping slot.

[0010] Preferably, a plurality of grooves are provided on the top surface of the overlapping substrate, an elastic strip is fixedly connected to the inner wall surface of the groove, a trapezoidal block is fixedly connected to the outer surface of the elastic strip, and the bottom surface of the trapezoidal block is movably overlapped on the top surface of the Micro-LED chip.

[0011] In a second aspect, a method for manufacturing a Micro-LED chip module using a flip-chip process includes the following steps: S1, performing weak acid cleaning on a substrate; S2, dividing the substrate into a plurality of identical substrate units, and providing an epitaxial growth layer on the surface of each substrate unit; S3. Detect the epitaxial growth layer of each substrate unit to see if there are any defects. If there are any defects, return to S1 to perform acid cleaning on the substrate unit. If not, proceed to the next step. S4, preparing an electrode layer on the surface of the epitaxial growth layer; S5. Fixing the chip by laser irradiating the transfer substrate.

[0012] Preferably, the S1 further comprises the following steps: The substrate is placed in an acid cleaning tank, and the first acid cleaning is performed using a mixture of HNO3, HF, CH3COOH and H2SO4 in a volume ratio of 9:9:12:4, and the cleaning time is 110 to 125 seconds; the cleaned substrate is taken out and dried, and the substrate is placed in a second acid cleaning tank, and the second acid cleaning is performed using a mixture of H3PO4, H2O2, H2O and CH3COOH in a volume ratio of 1:0.8:3:0.2, and the cleaning time is 70 to 78 seconds; The organic pollutants and particles on the surface of the substrate are removed, and the substrate is placed in an ultrasonic cleaning tank, immersed in ammonia water and hydrogen peroxide, and cleaned using ultrasonic waves.

[0013] Preferably, the step S2 further comprises the following steps: The metal organic chemical vapor deposition (MOCVD) technology is used to grow a GaN buffer layer, an n-type GaN layer, and a p-type GaN layer on the surface of the substrate under high temperature conditions; A patterned photoresist is formed on the surface of the epitaxial growth layer, and then the n-type GaN layer is etched using an inductively coupled plasma etching process.

[0014] Preferably, the step S2 further comprises the following steps: Etching the epitaxial layer to the surface of the n-type GaN layer to form an n-type GaN mesa structure; Etching the exposed n-type GaN layer region of the n-type GaN mesa structure to the surface of the target substrate to obtain a Micro-LED array structure; The Micro-LED array structure includes a plurality of Micro-LED structures, and the plurality of Micro-LED structures are electrically isolated from each other.

[0015] Preferably, the S4 further comprises the following steps: A current blocking layer, a first current layer, and a second current layer are provided on the surface of the electrode layer, the second current layer is provided on the surface of the p-type GaN layer, the current blocking layer is provided between the first current layer and the second current diffusion layer, the second current layer is provided on the extension surface in an exposed area of the current blocking layer, the first current layer is provided on the surface of the current blocking layer and the p-type GaN layer, and is in contact with the exposed second current layer, a positive electrode is provided on the surface of the first current layer and on the other side of the surface of the current blocking layer, and the contact surfaces between the positive electrode, the first current layer, the second current layer, and the p-type GaN layer all form ohmic contacts; The first current layer and the second current layer are both made of light-transmitting conductive materials, the current blocking layer is made of light-transmitting insulating material, and a sealing transparent adhesive layer is provided at the edge of the light-transmitting insulating material.

[0016] Preferably, the S5 further comprises the following steps: The laser device irradiates the peripheral position of the chip through the transfer substrate. The first current layer and the second current layer absorb the laser and are fixed on the positive and negative electrodes respectively using reflow soldering. The gravity of the transfer substrate is used to reduce the chip displacement and complete the electrical connection between the chip and the substrate electrode.

[0017] The beneficial effects of the present invention are as follows: 1. The present invention discloses a flip-chip Micro-LED chip module and its manufacturing method. When the Micro-LED chips are stacked on the inner wall of the bonding substrate, the bottom edges of the Micro-LED chips are supported at multiple angles using support bars and support columns. This creates a cavity between the bottom center of the Micro-LED chips and the inner wall of the bonding substrate. When the Micro-LED chips are powered on, heat generated within the Micro-LED chips accumulates within the cavity. This heat is then dissipated through vents on the bottom surface of the bonding substrate, achieving a cooling effect. 2. The present invention discloses a flip-chip Micro-LED chip module and its manufacturing method. When the Micro-LED chip is placed into the bonding substrate, the bottom surface of the Micro-LED chip presses down the inclined surface on the top surface of the trapezoidal block, causing the trapezoidal block to move toward the inside of the groove. When the Micro-LED chip is completely closed into the bonding substrate, the trapezoidal block is pushed in the opposite direction by the elastic bar, so that the bottom surface of the trapezoidal block is snapped onto the top surface of the Micro-LED chip. The trapezoidal block is used to simply define the position of the Micro-LED chip, thereby greatly preventing the Micro-LED chip from shaking excessively and falling during movement. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The present invention will be further described below with reference to the accompanying drawings.

[0019] Figure 1 It is a schematic flow diagram of the present invention; Figure 2 is a three-dimensional diagram of a circuit board in the present invention; Figure 3 It is an expanded stereoscopic view of the overlapping substrate in the present invention; Figure 4 It is a perspective view of a cross-section of the overlapping substrate in the present invention; Figure 5 It is a sectional three-dimensional view of the overlapping substrate in the present invention.

[0020] In the figure: 11, circuit board; 111, tin bar; 112, overlapping substrate; a1, groove; a2, elastic strip; a3, trapezoidal block; 113, ventilation hole; 114, heightening strip; 115, heat-absorbing copper strip; 116, snap-in slot; 117, heightening column; 12, Micro-LED chip; 13, closing cover; 14, docking joint. DETAILED DESCRIPTION

[0021] In order to make the technical means, creative features, objectives and effects achieved by the present invention easier to understand, the present invention is further described below in conjunction with specific implementation methods. Example

[0022] like Figures 2 to 4 As shown, a flip-chip Micro-LED chip module and a manufacturing method thereof described in an embodiment of the present invention include a circuit board 11, a bonding substrate 112 is provided on the top surface of the circuit board 11, a ventilation hole 113 is opened on the bottom surface of the bonding substrate 112, a padding strip 114 is provided on the inner wall surface of the bonding substrate 112 and located at the bottom edge position, a heat-absorbing copper strip 115 is provided on one side surface of the padding strip 114, and the inner wall surface of the bonding substrate 112 is fixedly connected to the four corner positions with padding columns 117, and the Micro-LED chip 12 is movably sleeved inside the bonding substrate 112.

[0023] When the Micro-LED chips 12 are stacked on the inner wall of the bonding substrate 112, the padding strips 114 and padding columns 117 are used to provide multi-angle support around the bottom edges of the Micro-LED chips 12. This creates a cavity between the bottom center of the Micro-LED chips 12 and the inner wall of the bonding substrate 112. When the Micro-LED chips 12 are powered on, heat generated within the Micro-LED chips 12 can accumulate within the cavity. This heat is then dissipated through the vents 113 on the bottom surface of the bonding substrate 112, resulting in a cooling effect. When the Micro-LED chip 12 is overlapped on the top surface of the heightening strip 114 and the heightening column 117, the heat-absorbing copper strip 115 is attached to the bottom surface of the Micro-LED chip 12. The heat-absorbing copper strip 115 is made of a thermally conductive material, so that the heat-absorbing copper strip 115 can quickly absorb the heat source on the bottom surface of the Micro-LED chip 12 and dissipate the heat source into the cavity, thereby increasing the thermal conductivity efficiency of the Micro-LED chip 12.

[0024] like Figures 2 to 4As shown, a tin bar 111 is provided at the junction of the top surface of the circuit board 11 and the bonding substrate 112, and a snap-in slot 116 is provided on the top surface of the bonding substrate 112 and at the edges thereof. The bottom surface of the bonding substrate 112 is movably bonded to the top surfaces of the heightening strip 114, the heightening column 117 and the heat-absorbing copper strip 115, and a closing cover 13 is movably bonded to the top surface of the bonding substrate 112. A docking joint 14 is fixedly connected to the bottom surface of the closing cover 13, and the outer surface of the docking joint 14 is movably sleeved on the inner wall of the snap-in slot 116.

[0025] After the Micro-LED chip 12 is clamped into the inside of the bonding substrate 112, the closing cover 13 is placed on the top surface of the bonding substrate 112. At this time, the docking joint 14 on the bottom surface of the closing cover 13 is docked and extended into the inside of the clamping slot 116 to limit the position of the closing cover 13, wrapping the Micro-LED chip 12 and reducing excessive contact between the Micro-LED chip 12 and the outside world.

[0026] like Figures 2 to 5 As shown, a plurality of grooves a1 are provided on the top surface of the overlapping substrate 112, an elastic strip a2 is fixedly connected to the inner wall surface of the groove a1, a trapezoidal block a3 is fixedly connected to the outer surface of the elastic strip a2, and the bottom surface of the trapezoidal block a3 is movably overlapped on the top surface of the Micro-LED chip 12.

[0027] When the Micro-LED chip 12 is placed inside the bonding substrate 112, the bottom surface of the Micro-LED chip 12 is used to press down the inclined surface on the top surface of the trapezoidal block a3, and the trapezoidal block a3 is moved toward the inside of the groove a1. When the Micro-LED chip 12 is completely closed into the bonding substrate 112, the elastic strip a2 is used to push the trapezoidal block a3 in the opposite direction, so that the bottom surface of the trapezoidal block a3 is clamped on the top surface of the Micro-LED chip 12. The trapezoidal block a3 is used to simply limit the position of the Micro-LED chip 12, which greatly prevents the Micro-LED chip 12 from shaking too much and falling when moving. Example

[0028] like Figure 1 As shown, a method for manufacturing a Micro-LED chip module using a flip-chip process includes the following steps: S1. Cleaning the substrate with weak acid; S2, dividing the substrate into a plurality of identical substrate units, and providing an epitaxial growth layer on the surface of each substrate unit; S3. Detect the epitaxial growth layer of each substrate unit to see if there are any defects. If there are any defects, return to S1 to perform acid cleaning on the substrate unit. If not, proceed to the next step. S4, preparing an electrode layer on the surface of the epitaxial growth layer; S5. Fixing the chip by laser irradiating the transfer substrate.

[0029] like Figure 1 As shown, S1 further includes the following steps: Place the substrate in the pickling tank for the first pickling: use a mixture of HNO3, HF, CH3COOH and H2SO4 in a volume ratio of 9:9:12:4, and the cleaning time is 110 to 125 seconds; take out the cleaned substrate and dry it, and then place the substrate in the second pickling tank for the second pickling: use a mixture of H3PO4, H2O2, H2O and CH3COOH in a volume ratio of 1:0.8:3:0.2, and the cleaning time is 70 to 78 seconds; The organic pollutants and particles on the surface of the substrate are removed, and the substrate is placed in an ultrasonic cleaning tank, immersed in ammonia water and hydrogen peroxide, and cleaned using ultrasonic waves.

[0030] S2 also includes the following steps: Using metal organic chemical vapor deposition (MOCVD) technology, a GaN buffer layer, an n-type GaN layer, and a p-type GaN layer are grown on the surface of the substrate under high temperature conditions. A patterned photoresist is formed on the surface of the epitaxial growth layer, and then etched to the n-type GaN layer using an inductively coupled plasma etching process.

[0031] S2 also includes the following steps: Etching the epitaxial layer to the surface of the n-type GaN layer to form an n-type GaN mesa structure; Etching the n-type GaN layer from the exposed area of the n-type GaN mesa structure to the surface of the target substrate to obtain a Micro-LED array structure; The Micro-LED array structure includes multiple Micro-LED structures, and the multiple Micro-LED structures are electrically isolated from each other.

[0032] S4 also includes the following steps: A current blocking layer, a first current layer, and a second current layer are provided on the surface of the electrode layer, the second current layer is provided on the surface of the p-type GaN layer, the current blocking layer is provided between the first current layer and the second current diffusion layer, the second current layer is provided on the extension surface in an exposed area of the current blocking layer, the first current layer is provided on the surfaces of the current blocking layer and the p-type GaN layer, and is in contact with the exposed second current layer, a positive electrode is provided on the surface of the first current layer and on the surface on the other side of the surface of the current blocking layer, and ohmic contacts are formed on the contact surfaces of the positive electrode, the first current layer, the second current layer, and the p-type GaN layer; The first current layer and the second current layer are both made of light-transmitting conductive materials, the current blocking layer is made of light-transmitting insulating materials, and a sealing transparent adhesive layer is provided at the edge of the light-transmitting insulating materials.

[0033] S5 also includes the following steps: The laser device irradiates the periphery of the chip through the transfer substrate. The first and second current layers absorb the laser and are fixed to the positive and negative electrodes respectively. Reflow soldering is used to reduce chip displacement by using the gravity of the transfer substrate to complete the electrical connection between the chip and the substrate electrodes.

[0034] Working Principle: When the Micro-LED chip 12 is stacked on the inner wall of the bonding substrate 112, the bottom edges of the Micro-LED chip 12 are supported at multiple angles by the support bars 114 and support columns 117. This creates a cavity between the bottom center of the Micro-LED chip 12 and the inner wall of the bonding substrate 112. When the Micro-LED chip 12 is powered on, heat generated within the Micro-LED chip 12 accumulates within the cavity. This heat is then dissipated through the vents 113 on the bottom surface of the bonding substrate 112, achieving a cooling effect. When the Micro-LED chip 12 is placed inside the bonding substrate 112, the bottom surface of the Micro-LED chip 12 is used to press down the inclined surface on the top surface of the trapezoidal block a3, and the trapezoidal block a3 is moved toward the inside of the groove a1. When the Micro-LED chip 12 is completely closed into the bonding substrate 112, the elastic strip a2 is used to push the trapezoidal block a3 in the opposite direction, so that the bottom surface of the trapezoidal block a3 is clamped on the top surface of the Micro-LED chip 12. The trapezoidal block a3 is used to simply limit the position of the Micro-LED chip 12, which greatly prevents the Micro-LED chip 12 from shaking too much and falling when moving.

[0035] The basic principles, main features, and advantages of the present invention are shown and described above. Those skilled in the art should understand that the present invention is not limited to the foregoing embodiments. The foregoing embodiments and descriptions are merely illustrative of the principles of the present invention. Various changes and modifications may be made to the present invention without departing from the spirit and scope of the present invention. Such changes and modifications are intended to fall within the scope of the present invention. The scope of protection claimed in the present invention is defined by the appended claims and their equivalents.

Claims

1. A flip-chip Micro-LED chip module, comprising a circuit board (11), characterized in that: A bonding substrate (112) is provided on the top surface of the circuit board (11), a ventilation hole (113) is provided on the bottom surface of the bonding substrate (112), a padding strip (114) is provided on the inner wall surface of the bonding substrate (112) and at the bottom edge position, a heat-absorbing copper strip (115) is provided on one side surface of the padding strip (114), and padding columns (117) are fixedly connected to the inner wall surface of the bonding substrate (112) at the four corner positions, and a Micro-LED chip (12) is movably sleeved inside the bonding substrate (112).

2. The flip-chip Micro-LED chip module according to claim 1, characterized in that: A tin bar (111) is provided at the junction of the top surface of the circuit board (11) and the lapping substrate (112); a clamping slot (116) is provided on the top surface of the lapping substrate (112) and at the four edges thereof; and the bottom surface of the lapping substrate (112) is movably overlapped with the top surfaces of the padding bar (114), the padding column (117) and the heat-absorbing copper bar (115).

3. The flip-chip Micro-LED chip module according to claim 1, characterized in that: A closing cover (13) is movably overlapped on the top surface of the overlapping base plate (112), a docking joint (14) is fixedly connected to the bottom surface of the closing cover (13), and the outer surface of the docking joint (14) is movably mounted on the inner wall of the clamping slot (116).

4. The flip-chip Micro-LED chip module according to claim 1, wherein: The top surface of the overlapping substrate (112) is provided with a plurality of grooves (a1), the inner wall surface of the groove (a1) is fixedly connected to an elastic strip (a2), the outer surface of the elastic strip (a2) is fixedly connected to a trapezoidal block (a3), and the bottom surface of the trapezoidal block (a3) is movably overlapped with the top surface of the Micro-LED chip (12).

5. A method for manufacturing a flip-chip Micro-LED chip module, applicable to the flip-chip Micro-LED chip module according to any one of claims 1-4, characterized in that: The following steps are involved: S1. Cleaning the substrate with weak acid; S2, dividing the substrate into a plurality of identical substrate units, and providing an epitaxial growth layer on the surface of each substrate unit; S3. Detect the epitaxial growth layer of each substrate unit to see if there are any defects. If there are any defects, return to S1 to perform acid cleaning on the substrate unit. If not, proceed to the next step. S4, preparing an electrode layer on the surface of the epitaxial growth layer; S5. Fixing the chip by laser irradiating the transfer substrate.

6. The method for manufacturing a Micro-LED chip module using a flip-chip process according to claim 5, wherein: Said S1 further comprises the following steps: The substrate is placed in an acid cleaning tank, and the first acid cleaning is performed using a mixture of HNO3, HF, CH3COOH and H2SO4 in a volume ratio of 9:9:12:4, and the cleaning time is 110 to 125 seconds; the cleaned substrate is taken out and dried, and the substrate is placed in a second acid cleaning tank, and the second acid cleaning is performed using a mixture of H3PO4, H2O2, H2O and CH3COOH in a volume ratio of 1:0.8:3:0.2, and the cleaning time is 70 to 78 seconds; The organic pollutants and particles on the surface of the substrate are removed, and the substrate is placed in an ultrasonic cleaning tank, immersed in ammonia water and hydrogen peroxide, and cleaned using ultrasonic waves.

7. The method for manufacturing a Micro-LED chip module using a flip-chip process according to claim 5, wherein: The S2 further comprises the following steps: The metal organic chemical vapor deposition (MOCVD) technology is used to grow a GaN buffer layer, an n-type GaN layer, and a p-type GaN layer on the surface of the substrate under high temperature conditions; A patterned photoresist is formed on the surface of the epitaxial growth layer, and then the n-type GaN layer is etched using an inductively coupled plasma etching process.

8. The method for manufacturing a Micro-LED chip module using a flip-chip process according to claim 7, wherein: The S2 further comprises the following steps: Etching the epitaxial layer to the surface of the n-type GaN layer to form an n-type GaN mesa structure; Etching the exposed n-type GaN layer region of the n-type GaN mesa structure to the surface of the target substrate to obtain a Micro-LED array structure; The Micro-LED array structure includes a plurality of Micro-LED structures, and the plurality of Micro-LED structures are electrically isolated from each other.

9. The method for manufacturing a Micro-LED chip module using a flip-chip process according to claim 5, wherein: The S4 further comprises the following steps: A current blocking layer, a first current layer, and a second current layer are provided on the surface of the electrode layer, the second current layer is provided on the surface of the p-type GaN layer, the current blocking layer is provided between the first current layer and the second current diffusion layer, the second current layer is provided on the extension surface in an exposed area of the current blocking layer, the first current layer is provided on the surface of the current blocking layer and the p-type GaN layer, and is in contact with the exposed second current layer, a positive electrode is provided on the surface of the first current layer and on the other side of the surface of the current blocking layer, and the contact surfaces between the positive electrode, the first current layer, the second current layer, and the p-type GaN layer all form ohmic contacts; The first current layer and the second current layer are both made of light-transmitting conductive materials, the current blocking layer is made of light-transmitting insulating material, and a sealing transparent adhesive layer is provided at the edge of the light-transmitting insulating material.

10. The method for manufacturing a Micro-LED chip module using a flip-chip process according to claim 9, wherein: The S5 further comprises the following steps: The laser device irradiates the peripheral position of the chip through the transfer substrate. The first current layer and the second current layer absorb the laser and are fixed on the positive and negative electrodes respectively using reflow soldering. The gravity of the transfer substrate is used to reduce the chip displacement and complete the electrical connection between the chip and the substrate electrode.

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