Grinding tool, machining equipment and groove bottom grinding method

Abstract

The invention relates to the technical field of PCB (Printed Circuit Board) processing, in particular to a grinding tool, processing equipment and a groove bottom grinding method, which are used for improving the groove bottom grinding efficiency of a metal matrix. The method comprises the following steps: based on a depth control process, controlling a drill bit to process a reference surface of a metal matrix on the PCB according to a cutting path so as to form a metal base trench with a target depth on the metal matrix; and a brush head of the grinding tool is controlled to grind the groove bottom of the metal base groove according to the cutting path of the drill bit.

Description

Technical Field

[0001] This invention relates to the field of PCB processing technology, and in particular to a grinding tool, processing equipment, and a bottom grinding method. Background Technology

[0002] With increasingly stringent requirements for heat dissipation in printed circuit boards (PCBs) from high-frequency (RF) and power amplifiers (PA), the industry has introduced a manufacturing process that embeds copper blocks within the PCB, known as embedded copper plates. Depending on the space utilization of the copper block and the need to create heat dissipation channels between different layers, the copper block may have recessed designs (such as...). Figure 1 As shown in the figure, this is to accommodate special functional modules or recessed devices. For example, a recess typically used to mount a power amplifier module is called a power amplifier slot.

[0003] Because the copper block has grooves and welding components with high heat dissipation requirements, there are specific requirements for the flatness of the bottom of the groove (e.g., standard ≤25um). Currently, the flatness requirement is mainly achieved by manually polishing the bottom of the groove with high-grit sandpaper after mechanical depth control. This method is very inefficient and has high labor costs for batch products. Summary of the Invention

[0004] This invention provides a grinding tool, processing equipment, and a bottom grinding method to solve the technical problem of low grinding efficiency for high-metal substrates.

[0005] A grinding tool for grinding the bottom of a metal base groove, wherein the metal base groove is a groove formed on a metal substrate, and the grinding tool includes a handle, a connector, a sleeve, and a brush head; One end of the tool holder is used to connect to the drive shaft of the processing equipment, and the other end of the tool holder is detachably connected to one end of the sleeve through the connector. The other end of the sleeve is fixedly connected to a brush head, wherein the brush head includes a plurality of hard brush needles arranged at intervals.

[0006] Furthermore, the connector includes a thermoplastic stop ring, with the other end of the knife handle inserted into one end of the sleeve, and the thermoplastic stop ring fitted around the outside of one end of the sleeve.

[0007] Furthermore, the hard brush needle is a silicon carbide brush needle or a silicon dioxide brush needle.

[0008] Furthermore, the cross-sectional outline of the plurality of spaced-apart hard brush needles is circular, and the diameter of the cross-section ranges from 4.0 to 6.0 ± 0.1 mm.

[0009] Furthermore, the hard brush needles include multiple groups, and the hard brush needles in different groups are arranged at intervals, wherein the spacing between the hard brush needles in adjacent groups is the same and greater than the spacing between the hard brush needles in the group.

[0010] Furthermore, the diameter of the hard brush needle is in the range of 0.4-0.6±0.1mm, and the exposed length of the hard brush needle is 3.5mm.

[0011] A processing apparatus, the processing apparatus comprising a drive shaft and a grinding tool as described in any of the preceding claims.

[0012] A method for bottom grinding based on the aforementioned grinding tool, the method comprising: Based on the depth control process, the drill bit is controlled to process the reference surface of the metal substrate on the PCB board according to the cutting path, so as to form a metal base groove of the target depth on the metal substrate. The brush head of the grinding tool is controlled to grind the bottom of the metal base groove according to the cutting path of the drill bit.

[0013] Furthermore, the cutting path includes parallel linear cutting segments and parallel connecting segments; The linear cutting segment causes the drill bit to cut in a straight line along the X-axis direction, and the paths of adjacent linear cutting segments are opposite. The connecting segment connects the paths of adjacent linear cutting segments in sequence, and the connecting segment causes the drill bit to cut in a straight line along the Y-axis direction. The X-axis direction is perpendicular to the Y-axis direction.

[0014] Furthermore, controlling the brush head to grind the bottom of the metal base groove according to the cutting path of the drill bit includes: The brush head is controlled to grind the bottom of the metal base groove once or multiple times according to the cutting path of the drill bit until the depth of the metal base groove is the target depth + 0.1mm.

[0015] In this embodiment of the application, a grinding tool is provided, which includes a handle, a connector, a sleeve, and a brush head for grinding the bottom of a metal substrate. Simply connecting it to processing equipment enables automated grinding. Because it uses a hard brush head, it can grind the bottom of the metal substrate, eliminating the need for manual grinding with high-grit sandpaper. This greatly improves grinding efficiency and reduces labor costs. The simplified tool utilizes mechanization to replace cumbersome manual processes, improving the efficiency of batch processing. Attached Figure Description

[0016] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the description of the embodiments of the present invention will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0017] Figure 1 This is a schematic diagram of the arrangement of a power amplifier slot; Figure 2 This is a schematic diagram of the structure of a grinding tool according to one embodiment of this application; Figure 3 This is a schematic diagram of a brush head structure of a grinding tool according to one embodiment of this application; Figure 4 This is a schematic flowchart of a grinding method according to an embodiment of this application; Figure 5 This is a schematic diagram of all the cutting processes of the drill bit in a grinding method according to an embodiment of this application; Figure 6 This is a schematic diagram of all cutting paths of the drill bit in a grinding method according to an embodiment of this application; Figure 7 According to one embodiment of this application Figure 6 A schematic diagram of a spliced ​​tool mark formed by the cutting method; Figure 8 This is a schematic diagram of a grinding path of a brush head in a grinding method according to an embodiment of this application. Detailed Implementation

[0018] To make the technical problems solved, the technical solutions, and the beneficial effects of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

[0019] It should be understood that the industry has begun to introduce a manufacturing process that embeds copper blocks inside printed circuit boards, known as embedded copper plates. Depending on the space utilization of the copper block and the need to build heat dissipation channels between different layers, the copper block will have a recessed design to accommodate special functional modules or recessed devices, thereby achieving overall miniaturization, improved heat dissipation, and reduced crosstalk in signal transmission. The copper block can also be made of other metal substrates; there are no specific limitations. Because the recessed areas have high heat dissipation requirements for soldering components, there are specific requirements for the flatness of the groove bottom.

[0020] Because copper and other metallic substrates are excellent conductors of heat and electricity, they are ideal metals for heat dissipation and excellent electrical conductivity in electronic components. Copper's ductility, malleability, and toughness make it a challenging material to mill. The heat generated during machining enhances copper's ductility. Given current conditions, achieving a smooth metal substrate groove bottom using current depth-controlled machining is difficult in the short term. The flatness of the groove bottom is strongly correlated with the machining capability; currently, the most mature control method is manual grinding to repair the copper substrate groove bottom. In other words, the current method mainly involves manually grinding the groove bottom with high-grit sandpaper after mechanical depth control to achieve the required flatness. This would result in significant labor costs and inspection time during mass production.

[0021] To address the aforementioned problems, this application provides a solution, primarily aimed at resolving these issues. Several embodiments are described below.

[0022] like Figure 2 and 3 As shown, Figure 2 This is a schematic diagram of the overall structure of a grinding tool provided in an embodiment of this application. In this embodiment, a grinding tool is provided for grinding the bottom of a metal base groove, wherein the metal base groove is a groove formed on a metal substrate. The grinding tool includes a handle 1, a connector 2, a sleeve 3, and a brush head 4. One end of the handle 1 is used to connect to the drive shaft (not shown in the figure) of a processing equipment. The other end of the handle 1 is detachably connected to one end of the sleeve 3 through the connector 2. The other end of the sleeve 3 is fixedly connected to the brush head 4, wherein the brush head 4 includes a plurality of hard brush needles 41 arranged at intervals.

[0023] In this embodiment, the metal substrate refers to the substrate or area from which the metal substrate groove needs to be processed. For example, the metal substrate may refer to a copper substrate formed on a conventional printed circuit board (PCB) using an embedded copper plate process; for instance, it could be... Figure 1 The power amplifier slot is located on a copper substrate; alternatively, it can be a substrate portion within a metal core PCB (MCPCB), the specific implementation of which is not limited in this application. Therefore, the embodiments of this application can be applied to slot bottom grinding of PCBs in various situations, providing diverse solutions and scenario applicability.

[0024] The brush head 4 includes a plurality of hard brush needles 41 arranged at intervals. For different grinding objects (copper substrate or other metal substrate), the hard brush needles 41 refer to brush needles formed of materials whose hardness meets the grinding requirements.

[0025] The processing equipment refers to a device that can drive the brush head 4 of the grinding tool to move intelligently via a drive shaft, such as a CNC machine tool, etc., without any specific limitation. In application, the tool holder 1 of the grinding tool is detachably and fixedly connected to the drive shaft of the processing equipment, so that the processing equipment can drive the tool holder 1 to move via the drive shaft through the driver program, thereby causing the brush head 4 to move along the required grinding path on the bottom of the groove used to install special functional modules or recessed devices, and complete the grinding of the bottom of the groove.

[0026] In this embodiment of the application, a grinding tool is provided, which includes a handle 1, a connector 2, a sleeve 3, and a brush head 4. It is used for grinding the bottom of a metal substrate tank. It can achieve automated grinding by simply connecting it to the processing equipment. Because it uses a hard brush head, it can grind the bottom of the tank formed by the metal substrate. Moreover, it eliminates the need for manual grinding of the tank bottom using high-grit sandpaper, which greatly improves grinding efficiency and reduces labor costs. It adopts the simplest grinding tool and uses mechanization to replace cumbersome manual processes, thereby improving the efficiency of batch processing products.

[0027] In one embodiment, the connector 2 includes a thermoplastic retaining ring. The other end of the tool handle 1 is inserted into one end of the sleeve 3, and the thermoplastic retaining ring is fitted over the outside of one end of the sleeve 3. During assembly, the thermoplastic retaining ring is first inserted into a designated position at the other end of the tool handle 1. The thermoplastic retaining ring may be an open, expandable retaining ring structure that can be inserted into a groove at the other end of the tool handle 1; or it may be heated and pressed into the sleeve and cooled to set (plastic has a certain elasticity). Then, the other end of the tool handle 1 is inserted into one end of the sleeve 3 and inserted all the way in, so that the thermoplastic retaining ring fits precisely against the end face of one end of the sleeve 3. During disassembly, locate the gap between the thermoplastic retaining ring and the tool handle 1, and gently pry up one side to allow the thermoplastic retaining ring to gradually pop out; or, if the thermoplastic retaining ring is an open retaining ring structure, retaining ring pliers can be used to clamp both ends and pull it outwards; or, a hot air gun can be used to slightly heat the thermoplastic retaining ring to soften it and make it easier to remove.

[0028] It should be understood that, in the embodiments of this application, the thermoplastic stop ring refers to a stop ring formed of thermoplastic or thermosetting plastic material with high hardness and structural strength, and the specific material type is not limited. In this embodiment, the stop ring connection method achieves a detachable connection between the sleeve 3 and the tool holder 1, while the plasticity of the thermoplastic stop ring facilitates fixing and disassembly, and is also low in cost and light in weight.

[0029] It should be noted that, in addition to Figure 2As shown, the connector 2 can also be a stop ring of other structural forms, without specific limitations. For example, as another example, the connector 2 can also refer to an embedded stop ring. Exemplarily, the stop ring is embedded in a groove or positioning cavity inside the sleeve 3. When the tool holder 1 is inserted, it is axially held by the stop ring, thereby forming a limiting, fixing, or locking mechanism. This method makes the fixation of the tool holder 1 and the sleeve 3 of the grinding tool more secure.

[0030] In one embodiment, the hard brush needle 41 is a silicon carbide brush needle or a silicon dioxide brush needle, that is, the brush needle material of the hard brush needle 41 is silicon carbide material or silicon dioxide material.

[0031] Silicon carbide and silicon dioxide brush needles differ in hardness, toughness, and wear resistance. Silica brush needles are harder and tougher than silicon carbide brush needles. Therefore, silicon dioxide brush needles are particularly suitable for grinding the bottom of grooves formed on copper substrates. Of course, silicon carbide brush needles may be more suitable for other applications; no specific limitation is made.

[0032] In this embodiment, the brush head 4 can be selected from either silica brush needles or silicon carbide brush needles depending on the working scenario, which has strong practicality and grinding specificity; moreover, the use of special materials ensures the deformation during the processing, ensuring the flat grinding of the bottom of the metal base tank and improving the flatness of the tank bottom.

[0033] In one embodiment, such as Figure 3 As shown, the rigid brush needles 41 comprise multiple groups, with the rigid brush needles 41 arranged at intervals between different groups. The spacing between the rigid brush needles 41 in adjacent groups is the same and greater than the gap between the rigid brush needles 41 within a group. For example, the different groups of rigid brush needles 41 can be arranged in a nested circular pattern, or in other ways; no specific limitation is made.

[0034] For example, the hard brush needles 4 on the brush head 4 include 1 group, 2 groups, ..., 9 groups. Each group includes one or more hard brush needles 41. In these 9 groups of hard brush needles 41, assuming that group 1 and group 2 are adjacent, and group 5 and group 6 are adjacent, the distance between group 1 and group 2 and the distance between group 5 and group 6 is a distance A and the same. However, this distance A is less than the distance B between the hard brush needles 4 within the group (such as group 1 or other groups).

[0035] In this embodiment, the hard brush needles 41 are arranged in a grouped ring or other distribution, with relatively small intervals between the hard brush needles 41 in each group along the circular track. This arrangement ensures that the brush needles have a uniform contact surface during use, increasing the local grinding intensity and facilitating the smoothing process.

[0036] In one embodiment, such as Figure 2 and 3 As shown, the cross-sectional outline of the plurality of spaced-apart hard brush needles 41 is circular, and the diameter of the cross-section ranges from 4.0 to 6.0 ± 0.1 mm. That is, when the plurality of spaced-apart hard brush needles 41 are cut perpendicularly along the radial direction of the tool holder 1, the cut surface is circular. It should be noted that designing the cross-sectional outline of the plurality of spaced-apart hard brush needles 41 to be circular ensures that the bristles formed by the hard brush needles 41 are evenly distributed and subjected to consistent force, which is beneficial for a smoother grinding of the groove bottom. It also helps the hard brush needles 41 maintain balance during rotation, reducing eccentric vibration and improving working stability during the grinding process of the groove bottom.

[0037] In one embodiment, the diameter of each hard brush needle ranges from 0.4 to 0.6 ± 0.1 mm, and the length of the brush needle is 3.5 mm. In this embodiment, the diameter range of each hard brush needle (0.4-0.6 ± 0.1 mm) has been proven to effectively guarantee the rigidity requirements during the grinding process.

[0038] As an example, the dimensions of the grinding tool provided in this application embodiment can be as follows: Figure 2 As shown, its total length is 38.10±0.5mm, the diameter of the handle 1 is 3.175±0.05mm, one end of the handle 1 is designed with a 45° chamfer, the chamfer length is 0.30mm, the height of the connector 2 (thermoplastic stop ring 2) is 4.60±0.1mm, the diameter is 7.65±0.1mm, the length of the sleeve 3 is 10mm, the diameter is 4.5~6.5±0.5mm, the diameter of the brush head is 4.0-6.0±0.1mm, the diameter range of each of the hard brush needles 41 is 0.4-0.6±0.1mm, the length of the hard brush needle is 3.5mm, and before installation, the distance between one end of the hard brush needle 41 and the end face of the thermoplastic stop ring 2 is 21±0.1mm.

[0039] It should be noted that the above examples are merely illustrative and can be modified according to actual processing requirements; no specific limitations are imposed. For example, a sleeve 3 with a diameter of 6.5mm matches a brush head 4 with a diameter of 6.05mm, and a sleeve 3 with a diameter of 4.5mm matches a brush head 4 with a diameter of 4.05mm; no specific limitations are imposed.

[0040] In one embodiment, a processing apparatus is provided, the processing apparatus including a drive shaft and a grinding tool as described in any embodiment.

[0041] As can be seen, this embodiment provides a processing device that can achieve automated grinding by simply connecting the grinding tool to the processing device. Due to the use of a hard brush head, it can grind the bottom of the groove formed on the metal substrate. Moreover, it eliminates the need for manual grinding of the groove bottom using high-grit sandpaper, which greatly improves grinding efficiency and reduces labor costs. The simplified tool uses mechanization to replace cumbersome manual processes, thereby improving the efficiency of batch processing products.

[0042] In one embodiment, such as Figure 4 The present invention provides a bottom grinding method based on the grinding tool described in any of the preceding claims, the method comprising: S101. Based on the depth control process, the drill bit is controlled to process the reference surface of the metal substrate on the PCB board according to the cutting path, so as to form a metal base groove of the target depth on the metal substrate. S102. Control the brush head of the grinding tool to grind the bottom of the metal base groove according to the cutting path of the drill bit.

[0043] It should be understood that depth control technology refers to precisely controlling the machining depth of the machined surface during processes such as machining, etching, and milling to ensure it meets design values, thereby achieving purposes such as functional limitations, insert positioning, and limit stops. When machining the reference surface of a copper-based groove or other metal-based groove, milling is limited by the internal angle of the groove. The milling cutter needs to reciprocate to form a machining reference plane. The deformation of the joint surface during copper-based cutting creates slight irregular burrs or machining marks along the cutting edge, resulting in an uneven bottom surface of the metal-based groove. This embodiment provides an automatic groove bottom grinding function that can simultaneously control the depth mechanically, thus directly integrating the requirements for groove size and bottom flatness, achieving low-cost and high-efficiency production goals. Therefore, based on the depth control process, the drill bit is controlled to process the reference surface of the metal substrate on the PCB board according to the cutting path, so as to form a metal base groove of the target depth on the metal substrate. The brush head of the grinding tool is controlled to grind the bottom of the metal base groove according to the cutting path of the drill bit. The specific depth control process is not limited in this application embodiment and will not be described in detail.

[0044] In this embodiment, the metal substrate refers to the substrate or area from which the metal substrate groove needs to be processed. For example, the metal substrate can refer to a copper substrate formed on a conventional printed circuit board (PCB) using an embedded copper plate process; for instance, it could be... Figure 1 The power amplifier slot is located on a copper substrate; alternatively, it can be the substrate portion of a metal substrate MCPCB, and the specific embodiments of this application are not limited thereto. It is evident that the embodiments of this application can be applied to the bottom grinding of PCB boards in various situations, providing diverse solutions and scenario applicability.

[0045] As can be seen, this embodiment provides a groove bottom grinding method based on the grinding tool described in any of the foregoing claims. Based on a depth control process, the drill bit is controlled to process the reference surface of the metal substrate on the PCB board according to the cutting path to form a metal groove of the target depth on the metal substrate. The brush head of the grinding tool is controlled to grind the bottom of the metal groove according to the cutting path of the drill bit to obtain a groove bottom with a flat bottom surface. This converts manual grinding into automated mechanical action, using an alternative automated solution design. Moreover, the developed mechanical grinding tool can match the processing characteristics of the equipment, and mechanical grinding has the ability to achieve automated processing. It can intelligently control the life of the grinding tool. Compared with manual grinding, it can also ensure that the actual accuracy of the depth-controlled groove bottom is not affected after grinding the bottom of the metal groove. Most importantly, the groove bottom grinding can eliminate the imperceptible tool marks of milling, so that the groove bottom surface remains flat under light-sensitive conditions. Subsequent simple visual inspection can verify whether the required flatness requirement is met.

[0046] In one embodiment, a cutting path is provided, comprising parallel linear cutting segments 101 and parallel connecting segments 102; wherein the linear cutting segments 101 cause the drill bit 5 to cut in a straight line along the X-axis direction, and the paths of adjacent linear cutting segments 101 are opposite; the connecting segments 102 are paths that sequentially connect adjacent linear cutting segments 101, and the connecting segments 102 cause the drill bit 5 to cut in a straight line along the Y-axis direction, wherein the X-axis direction and the Y-axis direction are perpendicular to each other.

[0047] For example, such as Figures 5-7 As shown, Figures 5-6 This diagram illustrates the cutting process and cutting path of drill bit 5 on the reference surface of metal substrate 6. Figure 7 In accordance with Figure 6 The cutting path creates spliced ​​tool marks. For example... Figure 5 As shown, during the cutting process, CNC machining equipment can be used to machine the reference surface of the metal substrate 6. During milling, due to the limitation of the inner angle of the groove, the milling cutter needs to reciprocate to form the machining reference plane, as shown below. Figure 6 As shown, D is the cutting starting point of drill bit 5, and the dashed arrow indicates the cutting path. It can be seen that drill bit 5, following the cutting method described above, forms a cutting path resembling a "Z". Figure 7 As shown, the deformation of the spliced ​​surface during cutting creates slight irregular burrs or machining marks along the cutting edge, forming splicing tool marks. Figure 8 As shown in this embodiment, according to the cutting path of the drill bit 5, the brush head 4 of the grinding tool is controlled to grind the bottom of the metal base groove according to the cutting path of the drill bit 5, that is, to perform grinding in a similar "Z" shaped grinding path.

[0048] As can be seen, this embodiment provides a groove bottom grinding method based on the grinding tool described in any of the foregoing claims. Based on a depth control process, the drill bit is controlled to process the reference surface of the metal substrate on the PCB board according to the cutting path, so as to form a metal base groove of target depth on the metal substrate; then the brush head of the grinding tool is controlled to grind the bottom of the metal base groove according to the cutting path of the drill bit.

[0049] It should be noted that, Figure 6 The cutting path shown here is only an example. There may be other cutting paths. When there are other cutting paths, the embodiments of this application can perform grinding according to their cutting paths to solve the unevenness problem caused by the limitation of the cutting position. Specific examples are not given here.

[0050] As can be seen, the grinding tool provided in this application embodiment can achieve grinding of the bottom of the groove formed on the metal substrate. Moreover, it eliminates the need for manual grinding of the groove bottom using high-grit sandpaper, greatly improving grinding efficiency and labor costs. The simplified tool replaces the cumbersome manual process with mechanization, improving the efficiency of batch processing products. Furthermore, this application embodiment will also form the same grinding path based on the cutting path of the drill bit, which can effectively eliminate the tool marks caused by the cutting path and further improve the flatness of the grinding. Taking copper substrate as an example, the grinding of the groove bottom can eliminate the imperceptible tool marks of copper surface milling, so that the copper surface remains flat under light-sensitive conditions, thereby achieving visual inspection to meet the flatness requirements of the bottom of the copper substrate groove.

[0051] In one embodiment, controlling the brush head to grind the bottom of the metal base groove according to the cutting path of the drill bit includes: The brush head is controlled to grind the bottom of the metal base groove once or multiple times according to the cutting path of the drill bit until the depth of the metal base groove is the target depth + 0.1mm.

[0052] In this embodiment, the brush head can be controlled to grind the bottom of the metal base groove once or multiple times according to the cutting path of the drill bit until the depth of the metal base groove is the target depth + 0.1mm.

[0053] In this embodiment, CNC technology can be used to enable the grinding tool to achieve automated processing capabilities, intelligently control the grinding blade life, and ensure that grinding the bottom of the power amplifier slot does not affect the actual accuracy of the depth control slot bottom. For example, until the depth of the metal base slot is the target depth + 0.1mm, the impact on the depth of the metal base slot is reduced, and the practicality is improved.

[0054] The above-described embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention, and should all be included within the protection scope of the present invention.

Claims

1. A grinding tool, characterized in that, For grinding the bottom of a metal base groove, wherein the metal base groove is a groove formed on a metal substrate, the grinding tool includes a handle, a connector, a sleeve, and a brush head; One end of the tool holder is used to connect to the drive shaft of the processing equipment, and the other end of the tool holder is detachably connected to one end of the sleeve through the connector. The other end of the sleeve is fixedly connected to a brush head, wherein the brush head includes a plurality of hard brush needles arranged at intervals.

2. The grinding tool according to claim 1, characterized in that, The connector includes a thermoplastic stop ring, with the other end of the tool holder inserted into one end of the sleeve, and the thermoplastic stop ring fitted over the outside of one end of the sleeve.

3. The grinding tool according to claim 1, characterized in that, The hard brush needle is a silicon carbide brush needle or a silicon dioxide brush needle.

4. The grinding tool according to claim 1, characterized in that, The cross-sectional outline of the plurality of spaced-apart hard brush needles is circular, and the diameter of the cross-section ranges from 4.0 to 6.0 ± 0.1 mm.

5. The grinding tool according to claim 1, characterized in that, The hard brush needles include multiple groups, and the hard brush needles in different groups are arranged at intervals. The spacing between the hard brush needles in adjacent groups is the same and is greater than the spacing between the hard brush needles in the same group.

6. The grinding tool according to any one of claims 1-5, characterized in that, The diameter of the hard brush needle is in the range of 0.4-0.6±0.1mm, and the exposed length of the hard brush needle is 3.5mm.

7. A processing equipment, characterized in that, The processing equipment includes a drive shaft and a grinding tool as described in any one of claims 1-6.

8. A method for bottom grinding based on the grinding tool as described in any one of claims 1-6, characterized in that, The method includes: Based on the depth control process, the drill bit is controlled to process the reference surface of the metal substrate on the PCB board according to the cutting path, so as to form a metal base groove of the target depth on the metal substrate. The brush head of the grinding tool is controlled to grind the bottom of the metal base groove according to the cutting path of the drill bit.

9. The bottom grinding method according to claim 8, characterized in that, The cutting path includes parallel linear cutting segments and parallel connecting segments. The linear cutting segment causes the drill bit to cut in a straight line along the X-axis direction, and the paths of adjacent linear cutting segments are opposite. The connecting segment connects the paths of adjacent linear cutting segments in sequence, and the connecting segment causes the drill bit to cut in a straight line along the Y-axis direction. The X-axis direction is perpendicular to the Y-axis direction.

10. The method for grinding the bottom of a groove according to claim 8 or 9, characterized in that, The control of the brush head to grind the bottom of the metal base groove according to the cutting path of the drill bit includes: The brush head is controlled to grind the bottom of the metal base groove once or multiple times according to the cutting path of the drill bit until the depth of the metal base groove is the target depth + 0.1mm.

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