A partitioned alignment and focusing method for an exposure machine

Abstract

This invention discloses a partitioned alignment focusing method for an exposure machine, comprising: (1) before exposure, the CCD camera captures the coordinates of the positioning holes at the four corners of the PCB board and compares them with the corresponding positioning hole coordinates in the electronic graphic file to establish the actual correspondence between the electronic graphic file and the PCB board; (2) before exposure, the area to be exposed is divided into M×N sub-regions; (3) the optimal focal plane distance of the four vertices of each sub-region is calculated respectively; if the maximum difference of the optimal focal plane distance of these four vertices is within the allowable error range, the average value of the optimal focal plane distance of these four vertices is used as the focal plane distance for the exposure of the sub-region; if the maximum difference of the optimal focal plane distance of these four vertices is not within the allowable error range, this step is repeated until the optimal focal plane distance of each sub-region is within the error range. The partitioned alignment focusing method provided by this invention can ensure accurate image exposure position and clear image exposure.

Description

[0001] This application is application number 201611025099.6, filed on November 22, 2016, and the invention title is "A..."

[0002] The divisional application for "DMD structure XY multi-axis movable optical path direct writing exposure machine". Technical Field

[0003] This invention relates to a partitioned alignment and focusing method for an exposure machine, belonging to the field of direct-write exposure technology. Background Technology

[0004] A PCB (Printed Circuit Board) is the support structure for electronic components and also the carrier for their electrical connections. Common PCB manufacturing equipment includes traditional exposure machines, multi-prism structure laser direct-write exposure machines, and DMD structure laser direct-write exposure machines. Laser direct-write exposure machines can directly image onto the PCB board, eliminating the need for film compared to traditional exposure machines, resulting in clearer images.

[0005] As market demands for PCB functionality increase, PCBs are becoming more complex and require greater system compatibility, sometimes necessitating very large substrates. However, current technology and equipment lack the capability to process ultra-large boards with widths exceeding 48 inches with high quality. Traditional exposure machines can produce ultra-large boards, but their processing precision is poor, failing to meet the requirements of high density and fine pitch. Prism-structured laser direct-write exposure machines currently cannot achieve optical path movement, requiring the entire board to be formed in one step. When processing ultra-large boards larger than 48 inches, the machine's width would exceed 3 meters, making it too bulky and difficult to pass through typical workshop doors. Therefore, prism-structured LDI cannot produce PCBs wider than 48 inches. Conventional DMD-structured laser direct-write exposure machines, due to their suction cups' maximum exposure width of only 24 inches, also cannot produce ultra-large boards larger than 48 inches.

[0006] If a DMD structure laser direct-write exposure machine is fabricated by increasing the size of the chuck that can be exposed, the required vacuum chuck size is relatively large, sometimes exceeding 55 inches, which presents the following problems: (1) When the actual size of the PCB board to be exposed is small, and the chuck structure supports a large vacuum range, air leakage will occur in areas not covered by the board, affecting the chuck's adsorption of the substrate; (2) Since the corners of the substrate may be raised during transportation, if the vacuum suction is insufficient, the chuck cannot flatten the board, which will affect the quality of the exposed PCB board and may cause the substrate to be scrapped. To solve this problem, there are currently three methods:

[0007] Method 1: Ignore the problem directly, but this will place high demands on the customer's PCB board. If the board is not level, it will require repeated manual bending, which will seriously affect production efficiency.

[0008] Method 2: Design different suction cup pads for different board sizes. The vacuum suction holes on the pad cover the same area as the board size. This method is simple, but slightly more complicated to operate. However, when producing 55-inch boards, a 55-inch pad needs to be replaced, which increases the difficulty exponentially. The time required to change the pad increases by 150% to 200%, seriously affecting production efficiency.

[0009] Method 3: For areas not covered by vacuum sealing, cover them with materials, commonly cut-up film. This method is economical but troublesome. Different PCB sizes require film to be cut into different sizes, which can lead to a buildup of cut film in the production area and make finding the required size difficult.

[0010] Therefore, it is evident that the existing technologies that typically involve replacing the suction cup with one of the appropriate size or finding a discarded film of the appropriate shape and size to seal the leak will significantly reduce production efficiency.

[0011] Furthermore, in PCB factories, large boards such as 52*40 inches are bulky and difficult to handle, potentially causing localized bending and deformation. While thin boards can generally be manually flattened, thicker boards (over 3mm) are more difficult to recover from deformation. Additionally, during actual exposure production, the substrate is manually dragged onto a suction cup. Perfect precision is impossible in this process; there will always be some rotation angle between the substrate and the electronic image, leading to image misalignment during exposure. Thirdly, in traditional exposure, the CCD camera captures four holes around the PCB board. Based on these holes, the CCD camera finds the clearest focal plane, determines the optimal focal plane and exposure focal length, and completes the focusing process. Exposure is then performed using this focal plane as a reference. However, in reality, the board is not perfectly level; some areas may have bulges or depressions, and the entire substrate may tilt during placement. These factors can cause inaccurate focusing in certain areas, severely impacting production quality.

[0012] In summary, current DMD structure laser direct writing exposure machines have problems such as inability to produce ultra-large plates, air leakage from the vacuum chuck, and inaccurate focusing and positioning during the exposure process, which urgently need to be solved. Summary of the Invention

[0013] To address the above problems, this invention provides a partitioned alignment and focusing method for an exposure machine, which solves the problems of existing technologies being unable to produce ultra-large plates, air leakage from vacuum suction cups, and inaccurate focusing and positioning during the exposure process.

[0014] The first objective of this invention is to provide a vacuum suction cup, which includes a suction cup body and a vacuum generating device. A certain number of air holes are distributed on the suction cup body in the form of rows and columns. Each row of air holes corresponds to a relay, and each column of air holes also corresponds to a relay. Each air hole is connected to the vacuum generating device by an air hole switch. The air hole switch is simultaneously connected to the relay in the row where the air hole is located and the relay in the column where the air hole is located.

[0015] In one embodiment of the present invention, the vent switch is located on the vacuum pipeline connecting the vent and the vacuum generating device.

[0016] In one embodiment of the present invention, the vent switch is an electromagnetic switch.

[0017] In one embodiment of the invention, the relay is connected to a main control device.

[0018] In one embodiment of the present invention, the air holes are distributed in a pattern of sparse distribution in the middle and dense distribution around the edges on the suction cup body.

[0019] In one embodiment of the present invention, the row spacing and column spacing of the air holes decrease uniformly from the middle of the suction cup body to both sides.

[0020] In one embodiment of the present invention, the row spacing or column spacing of the air holes located in the middle region of the suction cup body is a maximum of 1-3 inches, and the row spacing or column spacing of the air holes located in the edge region of the suction cup body is a minimum of 5-8 mm.

[0021] In one embodiment of the present invention, the opening shape of the air hole on the suction cup body can be any shape such as circle, ellipse, square, rectangle, etc., for example, circle.

[0022] In one embodiment of the present invention, the opening area of ​​the air hole on the suction cup body is 10 mm. 2 ~500mm 2 .

[0023] In one embodiment of the invention, the maximum width of the suction cup body is 55 inches.

[0024] In one embodiment of the present invention, the surface of the suction cup body is a single surface or is composed of multiple surfaces.

[0025] In one embodiment of the present invention, the suction cup body is composed of two equally sized discs.

[0026] In one embodiment of the present invention, the suction cup body can be divided into a suction cup support structure and a pad, or it can be an integral structure in which the pad and the suction cup support structure are integrated. When the suction cup body is a structure in which the suction cup support structure and the pad are separate, the pad is installed on the surface of the suction cup support structure, and the surface of the pad is designed with evenly distributed air holes. Below the pad is a vacuum passage connected to the air holes.

[0027] A second object of the present invention is to provide an apparatus incorporating the vacuum suction cup of the present invention.

[0028] In one embodiment of the present invention, the apparatus can be various types of exposure machines.

[0029] A third objective of this invention is to provide a DMD structure XY multi-axis movable optical path direct writing exposure machine incorporating the vacuum chuck of this invention.

[0030] In one embodiment of the present invention, the DMD structure XY multi-axis movable optical path direct writing exposure machine further includes a support structure, a DMD structure, a DMD structure stepping axis, and multiple motion components; each motion component includes a stepping X-axis, a scanning Y-axis, and a lifting Z-axis; a vacuum chuck is located above the motion components.

[0031] In this invention, XY multi-axis refers to having two or more motion components, and the motion components include a stepping X-axis, a scanning Y-axis, and a lifting Z-axis; movable means that the DMD structure can move along the guide rail with the slider of the DMD structure's stepping axis.

[0032] In one embodiment of the present invention, the DMD structure XY multi-axis movable optical path direct writing exposure machine is a DMD structure XY dual-axis movable optical path direct writing exposure machine, which contains two moving components.

[0033] In one embodiment of the present invention, the stepping X-axis is located below the lifting Z-axis, and the scanning Y-axis is located below the stepping X-axis;

[0034] In one embodiment of the present invention, the vacuum suction cup is connected to the lifting Z-axis of the motion component.

[0035] In one embodiment of the present invention, the plurality of motion components are arranged side by side along the X-axis.

[0036] In one embodiment of the present invention, the number of the plurality of motion components is two.

[0037] In one embodiment of the present invention, the suction cup body of the vacuum suction cup has a single, integral surface or is composed of multiple surfaces. When it is composed of multiple surfaces, each surface corresponds to one or more motion components.

[0038] In one embodiment of the present invention, the suction cup body of the vacuum suction cup is formed by merging two discs of the same size on the left and right sides; each disc corresponds to a motion component.

[0039] In one embodiment of the invention, the two disks are not connected in any way, or are connected by a ball hinge structure, or are rigidly connected.

[0040] In one embodiment of the present invention, there are two stepping X-axis, namely a first stepping X-axis and a second stepping X-axis.

[0041] In one embodiment of the present invention, the supporting structure is a gantry structure.

[0042] In one embodiment of the present invention, the DMD structure is mounted on the DMD structure stepper axis and can move along the guide rail along with the slider of the DMD structure stepper axis.

[0043] In one embodiment of the present invention, the DMD structure XY multi-axis movable optical path direct writing exposure machine further includes a camera for focusing and positioning.

[0044] The fourth objective of this invention is to provide a partitioned alignment and focusing method, particularly a partitioned alignment and focusing method for a direct-write exposure machine with a DMD structure of a vacuum chuck and XY multi-axis movable optical path, to solve the problems of inaccurate positioning and focusing caused by inaccurate plate placement and plate deformation during the production process.

[0045] The partition alignment and focusing method of the present invention, namely the four-point partition automatic focusing and positioning method, includes the following steps:

[0046] (1) Before exposure, the CCD camera captures the coordinates of the positioning holes at the four corners of the PCB board and compares them with the corresponding positioning hole coordinates in the electronic graphic file to establish the actual correspondence between the electronic graphic file and the PCB board. If the positioning hole coordinates captured by the CCD camera are consistent with the corresponding coordinates in the electronic graphic file, then proceed to step (2). If the positioning hole coordinates captured by the CCD camera are inconsistent with the corresponding coordinates in the electronic graphic file, then the electronic graphic file is adjusted to be consistent with the positioning hole coordinates captured by the CCD camera, and the starting position of the optical path exposure is also determined accordingly. Then proceed to step (2).

[0047] (2) Before exposure, the area to be exposed is divided into M×N sub-regions;

[0048] (3) Calculate the optimal focal distance of the four vertices of each sub-region. If the maximum difference between the optimal focal distances of the four vertices is within the allowable error range, the average value of the optimal focal distances of the four vertices is taken as the focal distance of the exposure of the sub-region. If the maximum difference between the optimal focal distances of the four vertices is not within the allowable error range, the sub-region is further divided into A×B secondary sub-regions. The optimal focal distance of the four vertices of each secondary sub-region is calculated. This step is repeated until the optimal focal distance of each sub-region is within the error range.

[0049] In one embodiment of the present invention, the optical path starts exposure from the initial position and enters different sub-regions. If the optimal focal plane distance is different, the height will be adjusted to the optimal exposure focal plane of the sub-region by raising and lowering the Z-axis, thereby ensuring that all exposure areas are exposed at the optimal focal plane, ensuring the linewidth uniformity of the entire board and the exposure quality.

[0050] In one embodiment of the present invention, the method for determining the optimal focal plane is as follows: using a CCD camera to identify the diameter of the hole on the PCB board; if the identified hole diameter is inconsistent with the actual hole diameter, by changing the height of the lifting Z-axis up and down, the camera continuously identifies the diameter of the hole, and finds the lifting axis height that is closest to the actual diameter after the lifting Z-axis has moved its full stroke. This height is the optimal focal plane corresponding to the hole.

[0051] Advantages and effects of the present invention:

[0052] (1) The DMD structure XY multi-axis movable optical path direct writing exposure machine of the present invention mainly improves the vacuum chuck structure. The vacuum chuck of the present invention is an automated vacuum chuck with a series of air holes distributed on the surface of the chuck. When a PCB board covers the air holes, the air hole passage is working; when no PCB board covers the air holes, the air holes are closed, effectively solving the problem of insufficient suction caused by air leakage when producing small boards. Furthermore, the air holes on the chuck are distributed with sparser holes in the middle and denser holes around the edges. This ensures that when placing PCB boards of different sizes, there are always air holes at the edges, effectively preventing the problem of board edges lifting. It also saves the number of air holes in the middle where fewer air holes are needed, reducing costs and improving efficiency.

[0053] (2) The DMD structure XY multi-axis movable optical path direct writing exposure machine of the present invention can be set to a width of 55 inches, which can produce 55-inch ultra-large boards, while ensuring high precision, high density, fine line spacing and other requirements; and multiple sets of motion components are connected below the suction cup, and the motion axes of the multiple sets of motion components move synchronously, which improves the exposure accuracy and operation stability, the exposure line spacing can be lower than 30 micrometers, and the exposure defect rate is reduced to less than 0.1%.

[0054] (3) The partitioned alignment focusing method provided by the present invention performs four-point partitioned focusing and positioning before the PCB board is exposed, which can ensure that the image exposure position is accurate, control the alignment error to below 12 micrometers, and make the image exposure clear.

[0055] (4) The upper DMD structure stepping axis and the lower stepping X-axis are combined. The DMD structure and the vacuum chuck can move freely in the lateral direction, which maximizes the lateral exposure range and increases the flexibility and mobility of exposure. The multi-motion component design gives the vacuum chuck multiple support points, which makes the chuck more stable during movement and avoids the problem of weak connection that may occur when a single component supports a large chuck. Attached Figure Description

[0056] Figure 1 This is a schematic diagram of the vacuum suction cup structure of the present invention; wherein, 1 is the suction cup body, 3 are air holes, 4 are relays, and 6 are the main control device;

[0057] Figure 2 This is a schematic diagram showing the connection between the vacuum generating device and the air hole of the vacuum suction cup of the present invention; wherein, 2 is the vacuum generating device and 5 is the air hole switch;

[0058] Figure 3 This is a schematic diagram of the structure after a substrate is placed using a traditional vacuum chuck; where 14 are substrates.

[0059] Figure 4 This is a schematic diagram of a structure after the vacuum chuck of the present invention has been placed on the substrate;

[0060] Figure 5 This is a schematic diagram of a structure after adjusting the position of the substrate on the vacuum chuck of the present invention;

[0061] Figure 6 This is a DMD structure XY dual-axis movable optical path direct writing exposure machine containing the vacuum chuck of the present invention; wherein, 7 is a support structure, 8 is a DMD structure, 9 is a DMD structure stepping axis, 10 is a vacuum chuck, 11 is a stepping X-axis, 12 is a scanning Y-axis, and 13 is a lifting Z-axis;

[0062] Figure 7 This is a schematic diagram of the correspondence between images before alignment;

[0063] Figure 8 This is a schematic diagram showing the correspondence between the aligned images;

[0064] Figure 9 A schematic diagram illustrating the division of the focused exposure area for different zones;

[0065] Figure 10 This is a schematic diagram showing the re-division of the exposure area. Detailed Implementation Plan

[0066] DMD structure: A complete optical path system with DMD as the core device, including components such as laser source, DMD, and optical lenses.

[0067] PCB: Printed Circuit Board, is an important electronic component. It serves as the support for electronic components and the carrier for their electrical connections.

[0068] DMD structure stepper axis: linear motor system, the optical path is installed in the moving part of the motor to perform stepping motion.

[0069] Stepping X-axis: also called X-axis motion platform or stepping axis, it can be used to perform stepping motion or continuous scanning motion.

[0070] Y-axis scanning: also called scanning axis or Y-axis, is used to perform continuous scanning motion at a constant speed.

[0071] Lifting Z-axis: Also called lifting axis or Z-axis, it is used to control the lifting and lowering of the suction cup.

[0072] Suction cup: A stage used to attach and fix PCB boards.

[0073] The present invention will now be described in detail.

[0074] Example 1: Vacuum suction cup

[0075] The vacuum chuck structure of the present invention is as follows: Figure 1-2 As shown.

[0076] The present invention provides a vacuum suction cup, comprising a suction cup body 1 and a vacuum generating device 2; a certain number of air holes 3 are distributed on the suction cup body 1 in the form of rows and columns, each row of air holes 3 corresponds to a relay 4, and each column of air holes 3 also corresponds to a relay 4; each air hole 3 is connected to the vacuum generating device 2 by an air hole switch 5; the air hole switch 5 is simultaneously connected to the relay 4 in the row where the air hole 3 is located and the relay 4 in the column where the air hole 3 is located.

[0077] Each relay 4 is connected to the main control device 6. The vent switch 5 is located on the vacuum line connecting the vent 3 and the vacuum generator 2. The vent switch 5 can be an electromagnetic switch. The vents 3 can be evenly distributed on the suction cup body 1.

[0078] With this structure and connection method, when the vacuum chuck is working, a substrate of a certain size is placed on the vacuum chuck. For rows or columns of vents covered by the substrate, the corresponding relays are activated. For a particular vent, the vent switch is only opened when both the relays corresponding to its row and column are activated, thus connecting the vacuum generator to the vent and enabling it to operate. In this case, the vent switches of vents not covered by the substrate are closed, thereby solving the air leakage problem that exists when using vacuum chucks to produce larger PCBs.

[0079] Example 2: Vacuum suction cup

[0080] The vacuum suction cup in this embodiment is similar to that in embodiment 1. Figure 1-2 An improvement has been made to the vacuum chuck shown.

[0081] The air holes 3 are distributed in a pattern of sparse distribution in the middle and dense distribution around the edges on the suction cup body 1.

[0082] In traditional vacuum chucks, the air holes are generally evenly distributed. When producing smaller PCBs, after the substrate 14 is placed on the chuck body, one edge of the substrate may be located far from the air holes on both sides (e.g., Figure 3 As shown in the diagram, this causes the edge portion to curl up due to the lack of vacuum suction, affecting production. By adopting the sparse center and dense perimeter distribution pattern of this invention, as shown in the diagram... Figure 4-5 As shown, when a smaller substrate is placed on a vacuum chuck, the substrate is placed close to the edge of the chuck body. If the edge of the substrate near the middle area of ​​the chuck body is far from the air holes on both sides, the substrate edge can be moved to the nearest row or column of air holes to cover them. Since the air holes around the chuck body are dense, this movement will not cause the other side edge of the substrate to be far from the air holes.

[0083] Optionally, the row spacing and column spacing of the air holes decrease uniformly from the middle of the suction cup body to both sides.

[0084] Optionally, the row or column spacing of the air holes located in the central region of the suction cup body is a maximum of 1-3 inches, while the row or column spacing of the air holes located in the edge region of the suction cup body is a minimum of 5-8 mm. The opening shape of the air holes on the suction cup body can be any shape, such as circular, elliptical, square, or rectangular, for example, circular. The opening area of ​​the air holes on the suction cup body can be arbitrary, for example, 10 mm². 2 ~500mm 2 .

[0085] Optionally, the suction cup body may be a single, integral surface or a combination of multiple surfaces.

[0086] Example 3: DMD Structure XY Dual-Axis Movable Optical Path Direct Writing Exposure Machine

[0087] The following example illustrates the use of a DMD structure XY dual-axis movable optical path direct writing exposure machine containing two moving components.

[0088] like Figure 6 As shown, this is a DMD structure XY dual-axis movable optical path direct writing exposure machine containing the vacuum chuck of the present invention.

[0089] The DMD structure XY dual-axis movable optical path direct writing exposure machine includes a support structure 7, a DMD structure 8, a DMD structure stepping axis 9, multiple motion components, and a vacuum chuck 10; each motion component includes a stepping X-axis 11, a scanning Y-axis 12, and a lifting Z-axis 13; the vacuum chuck 10 is located above the motion components.

[0090] The DMD structure 8 is mounted on the DMD structure stepper axis 9 and can move along the guide rail along with the slider of the DMD structure stepper axis 9. The stepping X-axis 11 is located below the lifting Z-axis 13, and the scanning Y-axis 12 is located below the stepping X-axis 11; the vacuum chuck 10 is connected to the lifting Z-axis 13 of the motion component. The vacuum chuck changes position accordingly as the stepping X-axis, scanning Y-axis, and lifting Z-axis 13 move.

[0091] Optionally, the suction cup body of the vacuum suction cup has a single, integral surface.

[0092] Optionally, the plurality of motion components are arranged side by side along the X-axis and evenly distributed below the vacuum chuck 10. By setting multiple motion components, when producing larger PCB boards, the components operate synchronously, which can ensure better stability compared to a single motion component.

[0093] Optionally, there are two motion components; correspondingly, there are two stepping X-axis, namely a first stepping X-axis and a second stepping X-axis.

[0094] Optionally, the support structure is a gantry structure. Used for the overall system architecture support, the marble gantry structure's structural characteristics effectively maintain the stability of the platform's movement and provide excellent seismic isolation performance.

[0095] Example 4: DMD Structure XY Dual-Axis Movable Optical Path Direct Writing Exposure Machine

[0096] The following example illustrates the use of a DMD structure XY dual-axis movable optical path direct writing exposure machine containing two moving components.

[0097] The DMD structure XY dual-axis movable optical path direct writing exposure machine of this embodiment is an improvement on the embodiment 3.

[0098] The vacuum suction cup's main body is composed of multiple plates; each plate corresponds to one or more motion components.

[0099] Optionally, the suction cup body of the vacuum suction cup is formed by merging two discs of the same size on the left and right sides; each disc corresponds to a motion component.

[0100] The two surfaces that make up the suction cup body are not connected in any way, or are connected by a ball hinge structure, or by a rigid connection.

[0101] To produce 55*40 inch PCBs, due to limitations in domestic processing technology, it is impossible to manufacture suction cups with high precision and large area. Therefore, the only option is to splice two suction cup surfaces together. In this invention, the left and right suction cups are each fixed to their corresponding Z-axis mounting surfaces with a number of screws. The connection between the two suction cups can be achieved in the following three ways:

[0102] (1) No connection is made between the suction cups, and the accuracy of the two Y axes is controlled solely by the platform. The advantages are simple structure and cost-effectiveness. When producing boards smaller than 24 inches, only the area of ​​one suction cup needs to be exposed, and it is not necessary to expose both suction cups. The production board size is more flexible and closer to the needs of customers.

[0103] (2) The suction cups are connected by a ball joint structure. There may be a slight height difference between the two suction cups in the Z-direction, but consistency during Y-direction movement is achieved through platform control. The advantage is that if one Y-axis unlocks, the connection between the two suction cups will trigger the unlocking of the other Y-axis, effectively preventing damage to the board. Because conventional methods cannot accurately measure the height difference between the two Z-axis to the micrometer level, a certain height difference will always exist. This method can effectively reduce situations such as jamming during Z-axis movement caused by inconsistent Z-axis height.

[0104] (3) The suction cups are rigidly connected, that is, the two suction cups are fixed in place by screws or other means. The advantage is that the board will not be scrapped if the Y-axis suddenly loses power or the Z-axis height is inconsistent.

[0105] The three connection methods described above can be selected according to the actual situation.

[0106] Example 5: Image Partition Alignment and Focusing Method

[0107] In traditional exposure processes, there may be issues with the PCB substrate being misaligned when placed on the vacuum chuck, such as... Figure 7As shown, if the electronic pattern is directly exposed onto the substrate, the actual pattern exposed on the PCB substrate will be inconsistent with the electronic pattern, resulting in poor board quality or scrap. Furthermore, in traditional exposure processes, the entire substrate is exposed using the same focal plane distance without adjusting the focal length; however, in reality, the substrate is not perfectly horizontal, and may have protrusions or depressions in certain areas. The entire substrate may also tilt during placement. These factors can cause inaccurate focusing in certain areas during exposure, severely impacting production quality.

[0108] The partition alignment and focusing method of the present invention, namely the four-point partition automatic focusing and positioning method, is as follows: Figure 7-10 As shown, it includes the following steps:

[0109] (1) Before exposure, the CCD camera captures the coordinates of the positioning holes at the four corners of the PCB board and compares them with the corresponding positioning hole coordinates in the electronic graphic file to establish the actual correspondence between the electronic graphic file and the PCB board. If the positioning hole coordinates captured by the CCD camera are consistent with the corresponding coordinates in the electronic graphic file, then proceed to step (2). If the positioning hole coordinates captured by the CCD camera are inconsistent with the corresponding coordinates in the electronic graphic file, then the electronic graphic file is adjusted to be consistent with the positioning hole coordinates captured by the CCD camera, and the starting position of the optical path exposure is also determined accordingly. Then proceed to step (2).

[0110] (2) Before exposure, divide the area to be exposed into M×N sub-regions (e.g., Figure 9 );

[0111] (3) Calculate the optimal focal distance at each of the four vertices of each sub-region; if the maximum difference between the optimal focal distances at these four vertices is within the allowable error range, then use the average of the optimal focal distances at these four vertices as the focal distance for exposure of that sub-region; if the maximum difference between the optimal focal distances at these four vertices is not within the allowable error range, then divide the sub-region into A×B secondary sub-regions (e.g., Figure 10 ), calculate the optimal focal plane distance of the four vertices of each secondary sub-region, and repeat this step until the optimal focal plane distance of each sub-region is within the error range.

[0112] The optical path begins exposure from the starting position. When entering different sub-regions, if the optimal focal plane distance is different, the height will be adjusted by raising and lowering the Z-axis to the optimal exposure focal plane of that sub-region. This ensures that all exposure areas are exposed at the optimal focal plane, guaranteeing the linewidth uniformity and exposure quality of the entire board.

[0113] The method for determining the optimal focal plane is as follows: use a CCD camera to identify the diameter of the hole on the PCB board. If the identified hole diameter is inconsistent with the actual hole diameter, change the height of the lifting Z-axis up and down. The camera continuously identifies the diameter of the hole and finds the lifting axis height that is closest to the actual diameter after the lifting Z-axis has moved its full stroke. This height is the optimal focal plane corresponding to the hole.

[0114] Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Anyone skilled in the art can make various modifications and alterations without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention should be determined by the claims.

Claims

1. A method for partitioned alignment and focusing of an exposure machine, characterized in that, The method includes the following steps: (1) Before exposure, the CCD camera captures the coordinates of the positioning holes at the four corners of the PCB board and compares them with the corresponding positioning hole coordinates in the electronic graphic file to establish the actual correspondence between the electronic graphic file and the PCB board. If the positioning hole coordinates captured by the CCD camera are consistent with the corresponding coordinates in the electronic graphic file, proceed to step (2). If the positioning hole coordinates captured by the CCD camera are inconsistent with the corresponding coordinates in the electronic graphic file, adjust the electronic graphic file to make it consistent with the positioning hole coordinates captured by the CCD camera. The starting position of the light path exposure is also determined accordingly, and continue to step (2). (2) Before exposure, the area to be exposed is divided into M×N sub-regions; (3) Calculate the optimal focal distance of the four vertices of each sub-region; if the maximum difference of the optimal focal distance of the four vertices is within the allowable error range, then take the average of the optimal focal distance of the four vertices as the focal distance of the exposure of the sub-region; if the maximum difference of the optimal focal distance of the four vertices is not within the allowable error range, divide the sub-region into A×B secondary sub-regions, calculate the optimal focal distance of the four vertices of each secondary sub-region, and repeat this step until the optimal focal distance of each sub-region is within the error range. The method includes: the optical path starts exposure from the initial position, and when entering different sub-regions, if the optimal focal plane distance is different, the height will be adjusted to the optimal exposure focal plane of the sub-region by raising and lowering the Z-axis, so as to ensure that all exposure areas are exposed at the optimal focal plane.

2. The method for partitioned alignment and focusing of an exposure machine according to claim 1, characterized in that, The method for determining the optimal focal plane distance in step (3) is as follows: A CCD camera is used to identify the diameter of holes on a PCB board. If the identified diameter does not match the actual diameter, the camera continuously identifies the diameter of the hole by changing the height of the Z-axis. The height of the Z-axis after it has moved its full stroke is found to be the closest to the actual diameter. This height is the optimal focal plane for that hole.

3. The method for partitioned alignment and focusing of an exposure machine according to claim 2, characterized in that, The Z-axis is used to control the lifting and lowering of the suction cup, which is used to adsorb and fix the PCB board.

4. A method for partitioned alignment and focusing of an exposure machine according to any one of claims 1-3, characterized in that, The exposure machine is a DMD structure XY multi-axis movable optical path direct writing exposure machine.

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