Chip grinding equipment and application thereof

Abstract

The present invention discloses a chip grinding device and its application. The chip grinding device includes a grinding disc and a chip pressing assembly matched with the grinding disc; the chip pressing assembly includes a plurality of pressing pins and a plurality of sleeves matched with the pressing pins one by one, one end of the pressing pin is exposed from the sleeve for fixing the chip, the sleeve is filled with a pressure medium, and the pressing pin is slid in the sleeve by adjusting the pressure of the pressure medium. When grinding the chip, the chip to be ground is fixed at the lower end of the pressing pin and placed on the curved grinding area of ​​the grinding disc for grinding. The present invention also discloses the application of the chip grinding device in grinding the light-emitting surface of an LED chip. The length of the pressing pin of the grinding device of the present invention can be extended or retracted according to the shape of the curved surface, and the pressure distribution on different pressing pins can be kept uniform, so that the curved surface formed by grinding the chip surface is better fitted with the curved end face of the grinding disc, reducing the curvature difference of the chip surface caused by the pressure difference.

Description

Technical Field

[0001] The present invention relates to the technical field of chip packaging, and in particular to a chip grinding device and application thereof. Background Art

[0002] With the development of science and technology, especially materials, microelectronic information, and optical technology, LED (light-emitting diode) products are being used more and more widely, and have a good development prospect. In actual industry and life, LED is mainly used in information display electronic instruments, equipment and household appliances, such as information digital display, urban traffic lights, medium and large-sized LED backlights, semiconductor indoor and outdoor lighting, safety lighting and special lighting, automotive interior and exterior lights and turn signals, etc. The LED industry is a sunrise, environmental protection and energy-saving industry. my country is already the world's largest production base, and its upstream epitaxy and chip industries have also begun to take shape.

[0003] The backlight modules used in LCD TVs are divided into direct-type backlight and side-entry backlight. In direct-type backlight, the LED light bar is located directly below the LCD panel. Through optical materials such as diffuser plates and diaphragms, the point light source emitted by the LED is converted into a uniform surface light source, allowing the TV to obtain a good display picture without light shadows. There are two main factors that affect the conversion of LED light sources into uniform surface light sources: one is the refraction and reflection principle of the light source by the optical structure of the diffuser plate and diaphragm; the other is the light-emitting angle of the LED itself. The larger the light-emitting angle, the better the display effect.

[0004] At present, LED epitaxial wafers are obtained by MOCVD (metal organic chemical vapor deposition). After the wafer is grown into various epitaxial layers with light-emitting layer, P layer, N layer, etc. through etching / evaporation equipment, the P pole, N pole and light-emitting area are prepared by the front end of the chip, and finally the back end of the LED chip is ground, thinned and polished. When the wafer is grown by MOCVD, the wafer presents a very smooth surface, which determines that the light-emitting surface of the chip to be produced later is a flat surface. After the chip is packaged into an LED package, the light-emitting angle of the light source can only be improved by bracket design or external optical lens. Because the optical light-emitting design is ignored in the production process, the current chips are all emitted parallel from the light-emitting surface.

[0005] In order to obtain LED chips with more light output angles, in the prior art, after the P-pole and N-pole processes of the LED chip are completed, the plane of the ITO (indium tin oxide) in the light-emitting area is improved to an arc-shaped optical light-emitting surface. This makes the light originally emitted from the ITO plane in the light-emitting area refracted more, and the light-emitting angle of the chip is significantly increased. Figure 1 The figure shows the comparison of the light-emitting angles before and after the LED chip is improved to a curved optical light-emitting surface.

[0006] Specifically, in the prior art, the patent number is ZL201910665453.9, and the patent name is: A grinding structure, grinding method and LED chip for an LED chip, which discloses a device and method for preparing an LED chip with a curved light-emitting surface. In the technical solution disclosed in the patent, pressure acts on the chip strip, so that the abrasive of the grinding disc forms a curved light-emitting surface on the flat light-emitting surface of the LED, thereby increasing the light-emitting angle of the chip. However, the bearing capacity of each chip on the chip strip of this technical solution is different, and the curvature of the light-emitting surface finally formed will be different, especially the difference between the chips at both ends of the chip strip is more obvious; and due to the different pressures, the curvature of the light-emitting surface finally formed by each chip on the chip strip is quite different. Summary of the invention

[0007] In view of the above-mentioned defects of the prior art, the primary technical problem to be solved by the present invention is how to evenly apply force during the chip grinding process so that the curved surface formed on the chip surface fits better with the curved end surface of the grinding disk, thereby reducing the curvature difference of the chip surface caused by the pressure difference.

[0008] In order to solve the above technical problems, the present invention provides the following technical solutions.

[0009] The first part of the present invention first provides a chip grinding device, including: a grinding disk and a chip pressing assembly adapted to the grinding disk.

[0010] The chip pressing assembly includes at least one pressing needle, which is also called a pin needle, and a sleeve pressing needle that matches the pressing needle one by one. The pressing needle is at least partially placed in the sleeve, and the sleeve is filled with a pressure medium. The pressing needle slides in the sleeve by adjusting the pressure of the pressure medium, so that one end of the pressing needle is exposed from the sleeve, and the medium pressure in the sleeve is applied to the pressing needle. The pressing assembly and the grinding disc are arranged opposite to each other. Specifically, the end of the pressing needle in the pressing assembly away from the sleeve points to the direction of the grinding disc, and in particular, the end of the pressing needle away from the sleeve points to the direction of the grinding end surface; at the same time, the grinding disc is also facing the direction of the pressing assembly, and in particular, the grinding end surface is facing the direction pointed by one end of the pressing needle in the sleeve.

[0011] In the present invention, the pressure medium is used as a medium for transmitting pressure; when air pressure is used to push the pressing needle to slide, the pressure medium is gas; when hydraulic pressure is used to push the pressing needle to slide, the pressure medium is liquid.

[0012] When the chip grinding equipment is in use, the chip to be ground is fixed on the end of the pressing needle away from the sleeve. The pressing needle is pushed out by applying pressure in the sleeve to make the chip surface to be ground contact with the grinding disk, and the chip is further ground through the relative movement of the chip and the grinding disk.

[0013] In a preferred embodiment of the present invention, the pressing needle has a cylindrical structure, and the outer wall of the cylinder of the pressing needle cooperates with the inner wall of the sleeve. More preferably, the cylindrical structure is a cylindrical structure or a structure similar to a cylinder. The structure similar to a cylinder includes, but is not limited to, a cylinder with a hemispherical end, a cylinder with a needle-shaped end, and a cylinder with a spherical end.

[0014] In the present invention, preferably, the diameter of the pressing needle, especially the diameter of the end of the pressing needle away from the sleeve, is related to the size of the chip to be ground, so that the chip to be ground can be fixed to one end of the pressing needle. More preferably, the diameter of the pressing needle is 0.5mm to 1mm.

[0015] In the present invention, the chip pressing assembly includes at least one pressing pin. Preferably, the number of the pressing pins is not less than two, and more preferably, the number of the pressing pins is not less than three; and the plurality of pressing pins are evenly distributed on the surface of the chip to be ground.

[0016] In the present invention, the sleeve is made of a rigid material and is a rigid hollow tube with a rigid structure. In a specific embodiment, the sleeve is optionally a hollow steel tube. A pressing needle is placed in the sleeve, and the rigid tube ensures that the needle and the connecting sleeve can stably move up and down to press the chip module.

[0017] The grinding device further includes a pressure controller. In an optional embodiment, the sleeve is connected to a pressure medium pump through a pressure medium transmission pipe, and the pressure controller controls the pressure of the pressure medium by controlling the pressure medium pump. The pressure of the pressure medium in each sleeve is independently controlled by the pressure controller. The pressure controller includes a pressure parameter setting component, and preferably, the pressure parameter setting component is arranged on the grinding device.

[0018] The end surface of the grinding disc facing the pressing needle is the grinding area, also called the grinding end surface. Preferably, it is a curved grinding area, and the curved grinding area is used to contact the surface to be ground of the chip; an axial hole is provided at the center of the grinding disc, and the grinding disc rotates about the central axis of the straight line passing through the axial hole. When the grinding disc is in a rotating state, the curved grinding area grinds the chip and grinds the surface to be ground of the chip into a curved surface that matches the curved grinding area.

[0019] The central axis of the present invention is that the three-dimensional structure of the grinding disc can be axially symmetrical based on the straight line where the central axis is located. Specifically, based on the straight line where the central axis is located, an arbitrary plane is made, and the plane shape formed by the plane cutting the grinding disc is axially symmetrical with the straight line where the central axis is located. Select any point on the line segment where the central axis passes through the three-dimensional structure of the grinding disc to make a plane perpendicular to the central axis, and the plane shape formed by the plane cutting the grinding disc is centered on the point and is centrally symmetrical.

[0020] One method to determine the straight line where the central axis is located is: select any point on the grinding area of ​​the grinding disc, and draw a perpendicular line based on the microelement where the point is located on the surface of the grinding area; a plane can be determined in space based on the center point of the grinding disc and the above perpendicular line. Repeat the above steps, select another arbitrary point in the grinding area, draw a perpendicular line to the grinding surface passing through the point, and further determine another plane through the perpendicular line and the center point of the grinding disc. If the two planes intersect to obtain a straight line, then the straight line is the straight line where the central axis is located. If the two planes coincide, then repeat the above steps until the obtained plane intersects with the previously obtained plane.

[0021] The curved grinding area of ​​the grinding disc in the present invention is not limited to a spherical surface, but also includes grinding discs designed in various forms such as convex, concave, S or U shapes, so that the light-emitting surfaces of LED chips of different shapes required in practical applications can be realized. Preferably, the curved surface is selected from a concave spherical surface, a concave aspherical surface, a convex spherical surface, a convex aspherical surface, an S-shaped curved surface or a U-shaped curved surface. When the curved surface is a spherical surface, preferably, the radius of curvature of the spherical surface is 4 meters to 6 meters.

[0022] In the present invention, the grinding disc is not limited to tin Sn and bismuth Bi alloy materials, but also includes ceramics, other iron and aluminum products; the abrasive is not limited to diamond, but also includes SiC, zirconium oxide and other hard materials.

[0023] In the present invention, the grinding device may further include a chip buffer, which is disposed between the chip to be ground and the pressing needle, and is used to provide a buffer during grinding to prevent the chip from being damaged. Specifically, the chip to be ground is fixed to the end of the pressing needle away from the sleeve through the chip buffer. In a preferred embodiment of the present invention, the chip buffer is selected from one or a combination of soft rubber, soft rubber strip or soft rubber block.

[0024] In the present invention, the grinding equipment further includes a lubricating solvent spraying assembly, and the lubricant spraying assembly includes at least one nozzle, which is arranged on the end surface of the grinding disc facing the pressing assembly, and is used to spray the lubricating solvent onto the grinding disc; preferably, the lubricating solvent spraying assembly further includes a spraying controller, and the spraying controller is used to set the nozzle spraying time and the time interval between each two sprays.

[0025] The present invention further provides an application of the chip grinding device described in the first part of the present invention in grinding the light-emitting surface of an LED chip. The LED chip is fixed to the end of the pressing needle away from the sleeve, and is pushed by the other end in the sleeve until the chip contacts the grinding disc, and the grinding disc grinds the light-emitting surface of the LED chip through the end facing the pressing needle, and grinds the light-emitting surface of the LED chip into a curved surface.

[0026] It should be pointed out that the chips suitable for grinding are not limited to LED chips, but also include various ICs, diodes or transistors and other products that have the same manufacturing process as LED chips.

[0027] In the present invention, the end faces of the grinding disc refer to the faces at both ends of the grinding disc. The grinding disc can be roughly understood as a cylinder, and the end faces are the faces at both ends of the cylinder. It should be pointed out that the end faces are not the curved surfaces where the side walls of the grinding disc are located.

[0028] The present invention further provides a method for grinding a chip using the above chip grinding device, comprising the following steps:

[0029] (1) Fix the chip to be ground at the lower end of the pressing needle of the chip pressing assembly;

[0030] (2) adjusting the pressure of the pressure medium in the sleeve to push out the pressing needle, so that the surface to be ground of the chip contacts the curved surface grinding area;

[0031] (3) Turn on the grinding disc and rotate it at a preset speed to grind the surface to be ground of the chip into a curved surface that matches the curved surface grinding area.

[0032] Preferably, in step (1), a soft rubber is provided between the lower end of the pressing needle and the chip, the chip is fixed on the soft rubber, and the soft rubber is sticky.

[0033] In the above method, a preferred embodiment is to grind the light-emitting surface of the LED chip. At this time, the chip cut in step (1) is preferably a thinned epitaxial wafer cut into strip-shaped LED chips with a width of a single LED chip.

[0034] The last part of the present invention also provides a chip prepared by the chip grinding method based on the chip grinding device described in the first part. The grinding device based on the present invention can reduce the curvature difference of the chip surface caused by the pressure difference, and give the chip to be ground, especially the light-emitting surface of the LED chip, new structural features. Therefore, the ground chip with new structural features is also within the protection scope of this patent.

[0035] In addition, the present invention is based on and improves the technical solution of ZL201910665453.9. The technical information of this patent is also introduced into this patent in the form of reference, and can also be used as a description and explanation of the technical features of this patent that do not make a creative contribution.

[0036] For LED chips, the technical effect of using the present invention is that changing the shape of the light-emitting surface of the LED chip increases the divergence angle of the light and disperses the glare effect caused by excessive concentration of light, which can be applied to the design of direct-type LED backlight products or lighting products. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 : Light emission diagram of LED chip with curved light-emitting surface.

[0038] Figure 2 : This patent is compared with the existing grinding process.

[0039] Figure 3 : Schematic diagram of multi-pressure needle grinding equipment.

[0040] Figure 4 : Schematic diagram of the LED chip with the pressing pin fixed on the rubber.

[0041] Figure 5 : Side view and top view of arc chip grinding. DETAILED DESCRIPTION

[0042] In order to make the purpose, technical solution and advantages of the present invention clearer and more specific, the present invention is further described in detail below with reference to the accompanying drawings and examples. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0043] This embodiment provides a grinding device for LED chips, including: a grinding disc and a chip pressing assembly; the chip pressing assembly includes 6 pressing pins and 6 sleeves matched with the pressing pins one by one, such as Figure 4 As shown, the pressing assembly is compatible with the grinding disc. The pressing needle has a cylindrical structure with a diameter of 0.5 mm. The pressing needle and the inner wall of the sleeve cooperate with each other and are slidable. The pressing needle is partially placed in the sleeve. The pressure medium in the sleeve is gas. The pressure medium pushes the pressing needle out of the lower end of the sleeve and applies the air pressure in the sleeve to the pressing needle. The lower end of the pressing needle is used to fix the LED chip to be ground. The end face of the grinding disc facing the pressing needle is provided with a curved grinding area, and the curved grinding area is used to contact the light-emitting surface of the LED chip.

[0044] Before grinding, place the LED chip strip on the soft rubber. The soft rubber buffers the pressure between the pressing needle and the chip and distributes the pressure evenly. The LED chip strip to be ground is fixed to the lower end of multiple pressing needles through the soft rubber. Multiple pressing needles are evenly distributed and fixed on the LED chip strip. The pressing needles with the LED chip strip fixed are placed on the curved grinding area. The light-emitting surface of the chip to be ground contacts the grinding disc downward. There is a nozzle on the grinding equipment. Before grinding, the nozzle speed is set to spray organic solvents such as alcohols for lubrication at regular intervals.

[0045] For the soft rubber used in this embodiment, the LED chip is fixed on the soft rubber, and the soft rubber has a certain viscosity. During grinding, the soft rubber can provide a buffer to prevent the LED chip from being damaged.

[0046] The air pressure in the sleeve is set by the pressure parameter setting component, and the pressure of the pressing needle is further controlled. The pressure acts evenly on the soft rubber through the needle head of the pressing needle. The parameters of the air pressure in the sleeve and the grinding time can be obtained according to the following method. An initial chip strip is preset, and the air pressure parameters and grinding time are adjusted to achieve the same spherical radius of the initial chip strip presented on the grinding disk.

[0047] Specifically, before grinding, the initial chip strips are tested to determine the curvature of the ground surface of each chip, and the same air pressure and fixed initial grinding time are pre-set for each chip, such as 30 seconds. After 30 seconds, the ground curvature of each chip is tested again, and the grinding amount of each chip within 30 seconds is calculated. Then, the air pressure of the sleeve is adjusted in the same inverse proportion to the grinding amount, so as to ensure that the subsequent chip strips on the grinding disk can achieve a consistent grinding spherical radius.

[0048] The grinding equipment is equipped with a rotating table with a rotating shaft in the center of the table. The grinding disc is installed on the rotating shaft. The center axis of the grinding disc rotates coaxially with the rotating shaft at a uniform speed. The speed is adjusted through the equipment display screen. Generally, the grinding speed needs to be slow and controlled below 1 revolution per minute. The grinding disc presents a certain spherical shape, and its spherical curvature radius is controlled between 4 meters and 6 meters. The grinding disc is mainly composed of alloy materials such as tin Sn and bismuth Bi. The grinding disc is covered with a layer of diamond abrasive with a thickness below the micron level. The abrasive size is controlled below 100nm for fine grinding of the chip to ensure that the light-emitting surface after grinding is smooth and has the best light-emitting effect. The specific structure of the grinding equipment is as follows: Figure 3 shown.

[0049] When grinding starts, the grinding disc is controlled to rotate. During the rotation, the curved grinding area grinds the light-emitting surface of the LED chip and grinds the light-emitting surface of the LED chip into a curved surface that matches the curved grinding area. In this way, the light-emitting surface of the LED chip after grinding is a curved surface. When the curved grinding area is a convex curved surface, the light-emitting surface of the LED chip after grinding is a concave curved surface, which has the function of focusing light; when the curved grinding area is a concave curved surface, the light-emitting surface of the LED chip after grinding is a convex curved surface, which has the function of diverging light and increases the light-emitting angle.

[0050] After the ground LED chip is cleaned, it is finally obtained by laser scribing and splitting.

[0051] In this embodiment, the LED chip is not limited to the front chip and the flip chip; the front chip is sequentially: ITO and protective layer, P-GaN layer, multi-quantum well light-emitting layer, N-GaN layer, substrate layer; the ITO and protective layer are the light-emitting surface. The flip chip is sequentially: substrate layer, P-GaN layer, multi-quantum well light-emitting layer, N-GaN layer, ITO and protective layer; the substrate layer is the light-emitting surface.

[0052] In actual grinding, as the grinding disc is used for a longer time, the effect of the abrasive will also decrease, so it is necessary to monitor the arc condition of the light-emitting surface of the chip strip at regular intervals to extend the grinding time or replace the grinding disc. The grinding particles can be diamond or other hard grinding particles.

[0053] This patent uses a one-to-one correspondence between the pressing needles through the sleeves, and by adjusting the pressure of the pressure medium to be different, the difference in the curvature of the light-emitting surface finally formed by each chip on the chip strip can be reduced. In the embodiment of the present invention, the grinding disc is not limited to concave and convex curved surfaces, but can also be in various shapes such as S or polygons, which can realize the light-emitting surfaces of LED chips of different shapes required in practical applications. In this embodiment, the cylindrical pressing needle cooperates with the inner wall of the sleeve and can slide. The gas in the sleeve pushes the pressing needle out of the lower end part of the sleeve. The length of the pressing needle can be extended or retracted according to the shape of the curved surface, and due to the specific structure, it can maintain a uniform pressure distribution on different pressing needles. Therefore, this embodiment is more suitable for the grinding needs of grinding discs of various shapes, especially irregular shapes.

[0054] It should be understood that the application of the present invention is not limited to the above examples. For ordinary technicians in this field, improvements or changes can be made based on the above description. All these improvements and changes should fall within the scope of protection of the claims attached to the present invention.

Claims

1. A chip grinding device, characterized in that: include: A grinding disc and a chip pressing assembly matched with the grinding disc; wherein the grinding disc and the pressing assembly are arranged opposite to each other; the chip pressing assembly comprises at least one pressing needle and a sleeve matched with the pressing needle, wherein the pressing needle is at least partially placed in the sleeve, one end of the pressing needle is exposed from the sleeve for fixing the chip, the sleeve is filled with a pressure medium, and the pressing needle is slid in the sleeve by adjusting the pressure of the pressure medium; when the chip grinding device is used, the chip to be ground is fixed on the end of the pressing needle away from the sleeve, and the pressing needle is pushed out by applying pressure in the sleeve so that the grinding surface of the chip is in contact with the grinding disc, and the chip is further ground by the relative movement of the chip and the grinding disc; Among them, the end face of the grinding disk facing the pressing needle has a curved grinding area in the shape of a curved surface, and the curved grinding area contacts the surface to be ground of the chip, and grinds the surface to be ground of the chip into a curved surface that matches the curved grinding area; the length of the pressing needle can be expanded or contracted according to the shape of the curved surface, and the pressure on different pressing needles is evenly distributed, so as to reduce the curvature difference of the chip surface caused by the pressure difference.

2. The chip grinding equipment according to claim 1, characterized in that: The number of the pressing needles is not less than two.

3. The chip grinding equipment according to claim 1, characterized in that: The pressing needle has a column structure, and the outer wall of the column of the pressing needle cooperates with the inner wall of the sleeve.

4. The chip grinding equipment according to claim 3, characterized in that: The column structure is a cylindrical structure or a structure similar to a cylindrical structure.

5. The chip grinding equipment according to claim 1, characterized in that: The pressing needle has a diameter of 0.5 mm to 1 mm.

6. The chip grinding equipment according to claim 1, characterized in that: The sleeve is a rigid hollow tube; the pressure medium is gas or liquid.

7. The chip grinding equipment according to claim 1, characterized in that: The grinding device further comprises a pressure controller, wherein the pressure of the pressure medium in each casing is independently controlled by the pressure controller.

8. The chip grinding equipment according to claim 7, characterized in that: The pressure controller further includes a pressure parameter setting component.

9. The chip grinding equipment according to claim 8, characterized in that: The pressure parameter setting component is arranged on the grinding equipment.

10. The chip grinding equipment according to claim 1, characterized in that: An axial hole is provided at the center of the grinding disc, and the grinding disc rotates about a central axis passing through the axial hole. When the grinding disc is in a rotating state, the curved surface grinding area grinds the chip.

11. The chip grinding equipment according to claim 10, characterized in that: The curved surface is selected from a concave spherical surface, a concave aspherical surface, a convex spherical surface, a convex aspherical surface, an S-shaped curved surface or a U-shaped curved surface.

12. The chip grinding equipment according to claim 10, characterized in that: When the curved surface is a concave spherical surface or a convex spherical surface, the radius of curvature of the spherical surface is 4 meters to 6 meters.

13. The chip grinding equipment according to claim 1, characterized in that: The grinding device further comprises a chip buffer, and the chip to be ground is fixed to an end of the pressing needle away from the sleeve through the chip buffer.

14. The chip grinding equipment according to claim 13, characterized in that: The chip buffer is selected from one or a combination of soft rubber, soft rubber strip or soft rubber block.

15. The chip grinding equipment according to claim 1, characterized in that: The grinding device further includes a lubricating solvent spraying assembly, which includes at least one nozzle, which is arranged on the end surface of the grinding disc facing the pressing assembly and is used to spray the lubricating solvent onto the grinding disc.

16. The chip grinding equipment according to claim 15, characterized in that: The lubricating solvent spraying assembly further comprises a spraying controller, which is used to set the spraying time of the nozzle and the time interval between two sprayings.

17. Use of the chip grinding equipment according to any one of claims 1 to 16 in grinding the light emitting surface of an LED chip.

18. A method for grinding a chip using the chip grinding device according to any one of claims 1 to 16, characterized in that: The following steps are involved: (1) Fix the chip to be ground at the lower end of the pressing needle of the chip pressing assembly; (2) adjusting the pressure of the pressure medium in the sleeve to push the pressing needle out, so that the surface to be ground of the chip contacts the curved surface grinding area; (3) Turning on the grinding disc and rotating it at a preset speed to grind the surface to be ground of the chip into a curved surface that matches the curved surface grinding area.

19. The method for grinding a chip according to claim 18, characterized in that: In step (1), a chip buffer is provided between the lower end of the pressing pin and the chip, and the chip is fixed on the chip buffer.

20. The method for grinding a chip according to claim 19, characterized in that: The chip buffer is one or a combination of soft rubber, soft rubber strip or soft rubber block.

21. The method for grinding a chip according to claim 19, characterized in that: The chip buffer is sticky.

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