A laser drilling structure and drilling process for a multi-layer circuit board

Abstract

The present invention belongs to the technical field of circuit board processing, and particularly relates to a multi-layer circuit board laser drilling structure and a drilling process thereof, comprising a workbench, a fixture unit is arranged on the upper surface of the workbench, a laser drill is installed directly above the workbench through a moving unit, a protective cover is sleeved on the outer bracket of the laser drill, and the two sides of the protective cover are respectively connected to a cold air pipe and a return pipe, a recessed cavity is opened at the center of the workbench, and a cooling protection mechanism is installed in the recessed cavity through a moving unit, and the cooling protection mechanism is used for cooling and protecting the multi-layer circuit board being laser drilled; the present invention can cool the surrounding area of ​​the lower surface of the circuit board after perforation, and at the same time can prevent the leakage of exhaust gas and smoke generated after perforation.

Description

Technical Field

[0001] The invention belongs to the technical field of circuit board processing, and in particular relates to a multi-layer circuit board laser drilling structure and a drilling process thereof. Background Art

[0002] Circuit boards can be called printed circuit boards or printed circuit boards. Circuit boards can be divided into three major categories according to the number of layers: single-sided boards, double-sided boards, and multi-layer circuit boards. Laser drilling refers to the laser processing process in which the laser is focused as a high-intensity heat source to heat the material, causing the material in the laser action area to melt or vaporize and then evaporate, thereby forming a hole.

[0003] Because the existing laser drilling equipment will generate a high burning temperature on the circuit board when drilling holes in the multi-layer circuit board. Therefore, not only the circuit board cannot be quickly removed from the fixture unit after drilling, but also a certain amount of smoke and dust exhaust gas will be generated during the drilling process. If the smoke and dust exhaust gas cannot be discharged in time, it is easy to cause safety hazards to the staff. Summary of the invention

[0004] In order to solve the above technical problems, the present invention is achieved through the following technical solutions:

[0005] The present invention is a laser drilling structure for a multi-layer circuit board, comprising a workbench, a fixture unit is arranged on the upper surface of the workbench, a laser drill is installed directly above the workbench through a movable unit, a protective cover is sleeved on the outer bracket of the laser drill, and the two sides of the protective cover are respectively connected to a cold air pipe and a return pipe, a recessed cavity is opened at the center of the workbench, and a cooling protection mechanism is installed in the recessed cavity through a movable unit, and the cooling protection mechanism is used for cooling and protecting the multi-layer circuit board drilled by laser.

[0006] Furthermore, the cooling and protection mechanism includes a support plate, a lifting cylinder, a bottom disc, a cooling hood, a fitting ring, a flow air pipe and an exhaust pipe. The support plate is installed on a movable unit arranged in the recessed cavity. At least two lifting cylinders are vertically fixed on the support plate, and a bottom disc is fixed on the upper end surface of the piston rod of the lifting cylinder. A cooling hood is installed on the upper surface of the bottom disc, and the cooling hood corresponds to the protection hood directly above the workbench. A fitting ring is installed on the upper cover opening of the cooling hood, and the fitting ring is fitted to the lower surface of the circuit board. One side of the bottom outer ring surface of the cooling hood is connected to the flow air pipe, and the other side of the outer ring surface is connected to the exhaust pipe.

[0007] Furthermore, the cooling protection mechanism also includes a circular collecting box and a material guiding boss. The bottom outer ring surface of the cooling cover is fixed with a circular collecting box, and a plurality of flow air holes are provided in a circumferential array on the box wall of the circular collecting box and the cover body of the cooling cover. The interior of the circular collecting box is sealed by a sealing block to form two semicircular box cavities, one of which is connected to a flow air pipe, and the other is connected to an exhaust pipe. A material guiding boss is installed on the upper surface of the bottom disc, and the bottom of the material guiding boss is aligned with the orifice of the flow air hole.

[0008] Furthermore, the cooling hood is made of elastic material, and a hole wall cleaning assembly is arranged inside the cooling hood, and the hole wall cleaning assembly includes a driving cylinder, a shunt pipe, a support shaft, fan blades, a threaded rod and a cleaning brush. A driving cylinder is fixed at the center of the lower surface of the bottom disk, and two shunt pipes are connected on the outer ring wall of the driving cylinder, and the two shunt pipes are connected to the flow air pipe and the exhaust pipe through solenoid valves respectively. A support shaft is rotatably installed at the center of the bottom disk through a bearing, and the bottom end of the support shaft extends into the driving cylinder and is installed with fan blades, and the fan blades are aligned with the pipe mouths of the symmetrical shunt pipes, and the top end of the support shaft rotates upward and passes through the material guide boss to open a threaded hole, and a threaded rod is threadedly connected in the threaded hole, and a cleaning brush is detachably installed on the top surface of the threaded rod.

[0009] Furthermore, the cleaning brush is configured as a conical structure, and the brush rod of the cleaning brush is made of elastic metal material.

[0010] Furthermore, a scraper plate is slidably fitted inside the protective cover, and a push cylinder is vertically fixed on the top of the protective cover, and the piston rod of the push cylinder extends into the protective cover and is connected to the scraper plate, and the outer ring surface of the scraper plate is in fit contact with the inner wall of the protective cover.

[0011] Furthermore, a contact turntable is rotatably mounted on the lower surface of the scraper disk via a rotating ring, and the contact turntable contacts the bent cleaning brush.

[0012] A multi-layer circuit board laser drilling process, which is used for drilling holes in a multi-layer circuit board using the multi-layer circuit board laser drilling structure described above, and comprises the following steps:

[0013] S1: The multi-layer circuit board to be drilled is clamped and fixed on the workbench by a fixture unit;

[0014] S2: using the laser drilling module to import drilling data, and dividing the surface of the circuit board into multiple processing sub-areas according to the drilling data;

[0015] S3: Then the moving unit drives the laser drill head to descend, and makes the protective cover fit to the sub-area position of the circuit board to be drilled, and the cooling protection mechanism also fits to the lower surface of the sub-area position synchronously;

[0016] S4: laser drilling is performed on the protective cover circuit board using a laser drilling module, and the protective cover and the cooling protection mechanism cool down the sub-area after drilling;

[0017] S5: After the laser drilling of the processing sub-area is completed, repeat steps S3 and S4 to process the next processing sub-area; until the laser drilling of all processing sub-areas of the circuit board is completed, the circuit board is removed from the workbench.

[0018] The present invention has the following beneficial effects:

[0019] The present invention installs a protective cover at the laser drill bit and a cooling protection mechanism in a recessed cavity at the center of the workbench. The protective cover and the cooling cover can be synchronously covered at the sub-area to be processed of the circuit board. A cold air pipe introduces cooling gas into the protective cover, and the cooling gas flowing in the protective cover can centrally cool the area around the drill hole of the circuit board, so that the blown cooling gas will not be wasted, and the circuit board can be quickly cooled. At the same time, the cooling cover below can also cool the area around the lower surface of the perforated circuit board, and can prevent the leakage of exhaust gas and smoke generated after the perforation.

[0020] The present invention arranges a hole wall cleaning component in a cooling cover made of an elastic material, and the piston rod of the lifting cylinder continues to extend, so that it pushes the cooling cover made of the elastic material to compress upward, and then the cleaning brush is inserted into the drilling hole of the circuit board, and the downward sliding of the scraper plate will first scrape and clean the dust adhering to the inner wall of the protective cover, and when the scraper plate descends to contact the head of the cleaning brush, the cleaning brush will be bent and fit against the surface of the circuit board, and then the continued rotation of the support shaft will drive the bent cleaning brush to not only clean the carbonized residue on the wall of the hole, but also scrape and clean the dust and re-condensed matter that have fallen around the upper surface of the hole, so that it can further improve the accuracy and quality of laser drilling of the circuit board.

[0021] Of course, any product implementing the present invention does not necessarily need to achieve all of the advantages described above at the same time. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings required for describing the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without paying creative work.

[0023] Figure 1 It is a schematic diagram of the structure of the circuit board clamping to be drilled disclosed by the present invention;

[0024] Figure 2 It is a structural schematic diagram of the drilling structure disclosed in the present invention;

[0025] Figure 3 A cross-sectional view of the protective cover disclosed in the present invention;

[0026] Figure 4 It is a structural schematic diagram of the temperature reduction protection mechanism disclosed in the present invention;

[0027] Figure 5 It is a cross-sectional view of the cooling cover disclosed in the present invention;

[0028] Figure 6 The present invention discloses Figure 5 A partial enlarged view of the middle part;

[0029] Figure 7 The present invention is a flow chart of the laser drilling process disclosed in the present invention.

[0030] In the figure: 1. workbench; 2. fixture unit; 3. moving unit; 4. laser drill; 5. protective cover; 51. cold air pipe; 52. return pipe; 53. scraper plate; 54. push cylinder; 55. contact turntable; 6. cooling protection mechanism; 61. support plate; 62. lifting cylinder; 63. bottom disc; 64. cooling cover; 65. fitting ring; 66. flow air pipe; 67. exhaust pipe; 68. circular ring collecting box; 681. flow air hole; 682. semicircular box cavity; 69. material guide boss; 7. hole wall cleaning assembly; 71. drive cylinder; 72. diverter pipe; 73. support shaft; 74. fan blade; 75. threaded rod; 76. cleaning brush. DETAILED DESCRIPTION

[0031] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0032] In the description of the present invention, it should be understood that the terms "opening", "upper", "lower", "thickness", "top", "middle", "length", "inside", "all around" and the like indicating orientation or positional relationship are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the components or elements referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0033] See also Figure 1-Figure 7 As shown, the present invention is a laser drilling structure for a multi-layer circuit board, comprising a workbench 1, a fixture unit 2 is arranged on the upper surface of the workbench 1, a laser drill 4 is installed directly above the workbench 1 through a moving unit 3, a protective cover 5 is sleeved on the outer bracket of the laser drill 4, and the two sides of the protective cover 5 are respectively connected with a cold air pipe 51 and a return pipe 52, a recessed cavity is opened at the center of the workbench 1, and a cooling protection mechanism 6 is installed in the recessed cavity through the moving unit 3, and the cooling protection mechanism 6 is used for cooling and protecting the multi-layer circuit board drilled by laser;

[0034] Specifically, the present invention sleeves a protective cover 5 on the outer bracket of the laser drill 4. When the multi-layer circuit board with holes is clamped on the workbench 1 by the clamp unit 2, the moving unit 3 drives the laser drill to descend to the area to be drilled, and the bottom end of the protective cover 5 is attached to the upper surface of the circuit board, and the cooling protection mechanism 6 located in the recessed cavity is synchronously moved to the right below the hole to be drilled in the circuit board through the moving unit 3. When the laser drill is drilling the circuit board, the pump body inside the workbench 1 generates a suction force into the protective cover 5 through the reflux pipe 52, and the valve on the cold air pipe 51 is opened, so that The suction force generated by the reflux pipe 52 will suck away the waste gas and smoke generated when the circuit board is being drilled. When the laser drilling is completed, the cooling air pump in the workbench 1 will pass cooling gas into the protective cover 5 through the cold air pipe 51, and the cooling gas flowing in the protective cover 5 will centrally cool the area around the drilling hole of the circuit board, so that the blown cooling gas will not be wasted, and the circuit board can be quickly cooled. At the same time, the cooling protection mechanism 6 below can also cool the area around the lower surface of the perforated circuit board, and at the same time, it can prevent the leakage of waste gas and smoke generated after the perforation.

[0035] In this embodiment, the cooling protection mechanism 6 includes a support plate 61, a lifting cylinder 62, a bottom disc 63, a cooling cover 64, a fitting ring 65, a flow air pipe 66 and an exhaust pipe 67. The support plate 61 is installed on the moving unit 3 arranged in the recessed cavity. At least two lifting cylinders 62 are vertically fixed on the support plate 61, and the bottom disc 63 is fixed on the upper end surface of the piston rod of the lifting cylinder 62. A cooling cover 64 is installed on the upper surface of the bottom disc 63, and the cooling cover 64 corresponds to the protection cover 5 directly above the workbench 1. A fitting ring 65 is installed on the upper cover opening of the cooling cover 64, and the fitting ring 65 is fitted to the lower surface of the circuit board. One side of the outer ring surface of the bottom of the cooling cover 64 is connected to the flow air pipe 66, and the other side of the outer ring surface is connected to the exhaust pipe 67.

[0036] Specifically, the moving unit 3 located in the recessed cavity can drive the support plate 61 to slide horizontally forward, backward, left and right, so as to be aligned with the protective cover 5 that can be moved directly above, and the piston rod of the lifting cylinder 62 can be extended and retracted, and can drive the cooling cover 64 to move upward through the bottom disc 63, so that it can be attached to the lower surface of the circuit board clamped by the clamp unit 2 through the fitting ring 65. When the laser drill 4 drills through the circuit board, the flowing air pipe 66 will fill the cooling cover 64 with cold gas, and the exhaust pipe 67 will extract the cold gas flowing in the cooling cover 64, so that the cold gas can The gas circulates in the cooling hood 64, thereby facilitating cooling of the bottom plate of the circuit board after drilling. At the same time, the flowing gas will suck out and collect the smoke and dust collected in the cooling hood 64 or the waste chips generated by drilling, to prevent them from diffusing into the atmosphere and causing harm to the workers. The piston rod of the lifting cylinder 62 is retracted, which will drive the cooling hood 64 and the fitting ring 65 from the lower surface of the circuit board after drilling, and the moving unit 3 located in the recessed cavity can drive the cooling hood 64 to move to the next point to be drilled, so as to perform sealed cooling treatment on the circuit board.

[0037] In this embodiment, the cooling protection mechanism 6 further includes a circular collecting box 68 and a material guiding boss 69. The circular collecting box 68 is fixed to the outer ring surface of the bottom of the cooling cover 64, and a plurality of flow holes 681 are provided in a circumferential array on the box wall of the circular collecting box 68 and the cover body of the cooling cover 64. The interior of the circular collecting box 68 is sealed by a sealing block to form two semicircular box cavities 682, one of which is connected to the flow air pipe 66, and the other is connected to the exhaust pipe 67. The upper surface of the bottom disc 63 is installed with a material guiding boss 69, and the bottom of the material guiding boss 69 is aligned with the opening of the flow hole 681.

[0038] Specifically, when cooling the circuit board, the air flow pipe 66 will deliver the cold gas into the cooling cover 64 through the semicircular box cavity 682, and the exhaust pipe 67 will extract the gas in the cooling cover 64, so that the cooling cover 64 first allows the cold gas to flow freely to cool the lower surface of the circuit board and remove dust by suction; when the circuit board has been cooled for a period of time, only the gas can be introduced into the protective cover 5, and the valve on the return pipe 52 is closed. Therefore, the cold air flow entering the protective cover 5 will only enter the cooling cover 64 downward through the drilled hole, so that The flowing cooling gas can also cool down the holes drilled in the multi-layer circuit boards. At the same time, the flowing airflow will drive the residue or dust generated by the drilling downward into the cooling cover 64, and the falling dust will first fall on the material guide boss 69, and then enter the semicircular box cavity 682 corresponding to the exhaust pipe 67 through the multiple flow holes 681. The semicircular box cavity 682 corresponding to the flow air pipe 66 will only send the cooling airflow through the other half of the multiple flow holes 681 into the cooling cover 64 to cool down the circuit boards.

[0039] In the present embodiment, the cooling cover 64 is made of elastic material, and a hole wall cleaning assembly 7 is arranged inside the cooling cover 64. The hole wall cleaning assembly 7 includes a driving cylinder 71, a shunt pipe 72, a support shaft 73, a fan blade 74, a threaded rod 75 and a cleaning brush 76. The driving cylinder 71 is fixed at the center of the lower surface of the bottom disc 63, and two shunt pipes 72 are connected on the outer ring surface of the driving cylinder 71. The two shunt pipes 72 are respectively connected to the flow air pipe 66 and the exhaust pipe 67 through the solenoid valve. The support shaft 73 is rotatably installed at the center of the bottom disc 63 through a bearing, and the bottom end of the support shaft 73 extends into the driving cylinder 71 and is installed with a fan blade 74. The fan blade 74 is aligned with the pipe mouth of the symmetrical shunt pipe 72. The top end of the support shaft 73 rotates upward and passes through the material guide boss 69 to open a threaded hole, and the threaded hole is threadedly connected with a threaded rod 75, and the top end surface of the threaded rod 75 is detachably installed with a cleaning brush 76;

[0040] Specifically, after the circuit board is laser drilled, burnt carbonized residues are left on the hole wall, and the carbonized residues and dust will affect the normal use of the circuit board; therefore, when the drilling position of the circuit board is cooled down, the piston rod of the lifting cylinder 62 continues to extend, so that it pushes the cooling cover 64 made of elastic material to compress upward, and then the cleaning brush 76 is inserted into the drilling hole of the circuit board, and then the solenoid valve corresponding to the flow air pipe 66 connected to the annular collection box 68 is closed, and then the solenoid valves on the two shunt pipes 72 are opened, so that the flow air pipe 66 will pass the gas through the shunt pipe 72 into the drive cylinder 71, so that the fan blade 74 rotates in the drive cylinder 71, and then the support shaft 73 will pass through the thread The rod 75 drives the cleaning brush 76 to rotate rapidly in the drilled hole of the circuit board, so that it can clean the carbonized residues and other dust remaining on the hole wall, and the exhaust pipe 67 will extract the gas entering the cooling cover 64 through the drilled hole, and at the same time will scrape the cleaning brush 76 to clean and discharge the carbonized residues that have fallen; when the hole wall is cleaned, the piston rod of the lifting cylinder 62 will contract, the bottom disc 63 will drive the cleaning brush 76 to be drawn out of the drilled hole, and the cooling cover 64 will be stretched, and the airflow from the flowing air pipe 66 into the cooling cover 64 through the semicircular box cavity 682 will clean and discharge the residues or dust adhering to the cleaning brush 76, so that the cleaning brush 76 can be inserted into the hole of the circuit board again to clean the residue.

[0041] In this embodiment, the cleaning brush 76 is configured as a conical structure, and the brush rod of the cleaning brush 76 is made of elastic metal material; specifically, the cleaning brush 76 that moves upward is configured as a conical structure, which facilitates the cleaning brush 76 to enter the drilled hole of the circuit board and achieve rapid cleaning of the hole wall; and the cleaning brush 76 whose rod body is made of elastic metal material can prevent the cleaning brush 76 from being rigidly inserted into the hole and causing damage to the hole.

[0042] In this embodiment, a scraper plate 53 is slidably attached to the inside of the protective cover 5, and a push cylinder 54 is vertically fixed to the top of the protective cover 5, and the piston rod of the push cylinder 54 extends into the protective cover 5 and is connected to the scraper plate 53, and the outer ring surface of the scraper plate 53 is in contact with the inner wall of the protective cover 5;

[0043] Specifically, when the cleaning brush 76 is inserted into the drilled hole, the head of the cleaning brush 76 will extend out for a certain length, and the protective cover 5 will slide down a short distance under the drive of the upper moving unit 3, so that the hole on the scraper plate 53 and the cleaning brush 76 are misaligned, and then the downward sliding of the scraper plate 53 will first scrape off and clean the dust adhering to the inner wall of the protective cover 5, and when the scraper plate 53 descends to contact the head of the cleaning brush 76, the cleaning brush 76 will bend, and as the scraper plate 53 continues to descend, the cleaning brush 76 will bend and fit to the upper surface of the drilled hole, thereby supporting the shaft 73. Continuing to rotate will drive the bent cleaning brush 76 to not only clean the carbonized residue on the wall of the hole, but also scrape and clean the dust and recondensed materials that have fallen around the upper surface of the hole, so that it can further improve the accuracy and quality of laser drilling of the circuit board; and when the hole wall is cleaned, the scraping plate 53 slides upward to the initial position driven by the piston rod of the push cylinder 54, and the rod body of the cleaning brush 76 will become a vertical state under its own elastic restoring force, and then the piston rod of the lifting cylinder 62 will be retracted, and the bottom disc 63 will drive the cleaning brush 76 to be pulled out of the hole.

[0044] In this embodiment, a contact turntable 55 is rotatably installed on the lower surface of the scraper disk 53 through a rotating ring, and the contact turntable 55 contacts the bent cleaning brush 76; specifically, when the scraper disk 53 descends to bend the cleaning brush 76, the contact turntable 55 will contact the cleaning brush 76, and then when the bent cleaning brush 76 rotates, the contact turntable 55 will also rotate synchronously, which can prevent the friction between the bent cleaning brush 76 and the lower surface of the scraper disk 53 from being too large, causing the cleaning brush 76 to be worn or unable to rotate normally.

[0045] A multi-layer circuit board laser drilling process, which is used for drilling holes in a multi-layer circuit board using the multi-layer circuit board laser drilling structure described above, and comprises the following steps:

[0046] S1: The multi-layer circuit board to be drilled is clamped and fixed on the workbench 1 by the clamp unit 2;

[0047] S2: using the laser drilling module to import drilling data, and dividing the surface of the circuit board into multiple processing sub-areas according to the drilling data;

[0048] S3: Then the moving unit 3 drives the laser drill 4 to descend, and makes the protective cover 5 fit to the sub-region position of the circuit board to be drilled, and the cooling protection mechanism 6 also fits to the lower surface of the sub-region position synchronously;

[0049] S4: laser drilling is performed on the circuit board of the protective cover 5 by using a laser drilling module, and the protective cover 5 and the cooling protection mechanism 6 cool down the sub-area after drilling;

[0050] S5: After the laser drilling of the processing sub-area is completed, repeat steps S3 and S4 to process the next processing sub-area; until the laser drilling of all processing sub-areas of the circuit board is completed, the circuit board is removed from the workbench 1.

[0051] In the description of this specification, the description with reference to the terms "one embodiment", "example", "specific example", etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0052] The preferred embodiments of the present invention disclosed above are only used to help illustrate the present invention. The preferred embodiments do not describe all the details in detail, nor do they limit the invention to the specific implementation methods described. Obviously, many modifications and changes can be made according to the content of this specification. This specification selects and specifically describes these embodiments in order to better explain the principles and practical applications of the present invention, so that those skilled in the art can understand and use the present invention well. The present invention is limited only by the claims and their full scope and equivalents.

Claims

1. A laser drilling structure for a multi-layer circuit board, characterized in that: The invention comprises a workbench (1), wherein a fixture unit (2) is arranged on the upper surface of the workbench (1), a laser drill head (4) is installed directly above the workbench (1) via a moving unit (3), a protective cover (5) is sleeved on the outer bracket of the laser drill head (4), and the two sides of the protective cover (5) are respectively connected to a cold air pipe (51) and a return pipe (52), a recessed cavity is opened at the center of the workbench (1), and a cooling protection mechanism (6) is installed in the recessed cavity via a moving unit (3), and the cooling protection mechanism (6) is used for cooling and protecting the multi-layer circuit board being laser drilled; The cooling protection mechanism (6) comprises a support plate (61), a lifting cylinder (62), a bottom disc (63), a cooling cover (64), a fitting ring (65), a flow air pipe (66) and an exhaust pipe (67); the support plate (61) is mounted on a moving unit (3) arranged in the recessed cavity; at least two lifting cylinders (62) are vertically fixed on the support plate (61); the bottom disc (63) is fixed on the upper end surface of the piston rod of the lifting cylinder (62); a cooling cover (64) is mounted on the upper surface of the bottom disc (63); the cooling cover (64) corresponds to the protection cover (5) directly above the workbench (1); a fitting ring (65) is mounted on the upper cover opening of the cooling cover (64); the fitting ring (65) is fitted to the lower surface of the circuit board; one side of the bottom outer ring surface of the cooling cover (64) is connected to the flow air pipe (66); and the other side of the outer ring surface is connected to the exhaust pipe (67); The cooling protection mechanism (6) further comprises a circular collecting box (68) and a material guiding boss (69); the circular collecting box (68) is fixed to the outer ring surface of the bottom of the cooling cover (64); a plurality of flow holes (681) are provided in a circular array on the box wall of the circular collecting box (68) and the cover body of the cooling cover (64); the interior of the circular collecting box (68) is sealed by a sealing block to form two semicircular box cavities (682); one of the semicircular box cavities (682) is connected to a flow air pipe (66); the other semicircular box cavity (682) is connected to an exhaust pipe (67); the upper surface of the bottom disc (63) is provided with a material guiding boss (69); and the bottom of the material guiding boss (69) is aligned with the opening of the flow hole (681).

2. A multi-layer circuit board laser drilling structure according to claim 1, characterized in that: The cooling cover (64) is made of elastic material. A hole wall cleaning assembly (7) is arranged inside the cooling cover (64). The hole wall cleaning assembly (7) comprises a driving cylinder (71), a shunt pipe (72), a support shaft (73), a fan blade (74), a threaded rod (75) and a cleaning brush (76). The driving cylinder (71) is fixed at the center of the lower surface of the bottom disk (63). Two shunt pipes (72) are connected to the outer wall of the driving cylinder (71). The two shunt pipes (72) are connected to the flow air pipe (76) through electromagnetic valves. 66) is connected to the exhaust pipe (67), a support shaft (73) is rotatably mounted at the center of the bottom disk (63) through a bearing, and the bottom end of the support shaft (73) extends into the driving cylinder (71) and is mounted with a fan blade (74), the fan blade (74) is aligned with the pipe mouth of the symmetrical diversion pipe (72), the top end of the support shaft (73) is rotated upward and passes through the material guide boss (69) to form a threaded hole, and a threaded rod (75) is threadedly connected in the threaded hole, and a cleaning brush (76) is detachably mounted on the top surface of the threaded rod (75).

3. A multi-layer circuit board laser drilling structure according to claim 2, characterized in that: The cleaning brush (76) is configured as a conical structure, and the brush rod of the cleaning brush (76) is made of elastic metal material.

4. The laser drilling structure for a multi-layer circuit board according to claim 1, characterized in that: A scraper plate (53) is slidably fitted inside the protective cover (5), and a push cylinder (54) is vertically fixed on the top of the protective cover (5), and a piston rod of the push cylinder (54) extends into the protective cover (5) and is connected to the scraper plate (53), and the outer ring surface of the scraper plate (53) is in fit contact with the inner wall of the protective cover (5).

5. A multi-layer circuit board laser drilling structure according to claim 4, characterized in that: A contact rotating disk (55) is rotatably mounted on the lower surface of the scraping disk (53) via a rotating ring, and the contact rotating disk (55) is in contact with the bent cleaning brush (76).

6. A laser drilling process for a multi-layer circuit board, characterized in that: The process is used for drilling holes in a multilayer circuit board using the multilayer circuit board laser drilling structure described in any one of claims 1 to 5, and the process comprises the following steps: S1: The multilayer circuit board to be drilled is clamped and fixed on the workbench (1) by a clamp unit (2); S2: using the laser drilling module to import drilling data, and dividing the surface of the circuit board into multiple processing sub-areas according to the drilling data; S3: Then the moving unit (3) drives the laser drill head (4) to descend, and makes the protective cover (5) fit to the sub-region position of the circuit board where the hole is to be drilled, and the cooling protection mechanism (6) also fits to the lower surface of the sub-region position synchronously; S4: using a laser drilling module to perform laser drilling on the circuit board of the protective cover (5), and the protective cover (5) and the cooling protection mechanism (6) will perform cooling treatment on the sub-area after drilling; S5: After the laser drilling of the processing sub-area is completed, repeat steps S3 and S4 to process the next processing sub-area; until the laser drilling of all processing sub-areas of the circuit board is completed, the circuit board is removed from the workbench (1).

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