A stitching imaging method of laser segmented exposure

Abstract

The application discloses a splicing imaging method for laser segmented exposure, and belongs to the field of laser direct imaging. The splicing imaging method comprises the following steps: S1, processing of splicing area pattern height data; S2, obtaining a first actual exposure pattern and a second actual exposure pattern; and S3, alignment exposure processing. The splicing area pattern is cut according to the diagonal line of a rectangle, so that the upper part of a total exposure pattern belongs to the first actual exposure pattern, and the lower part of the total exposure pattern belongs to the second actual exposure pattern. During exposure, the first actual exposure pattern is exposed first, and then the second actual exposure pattern is exposed. The splicing area avoids secondary exposure. Even if the splicing area adopts an overlapping area exposure mode, the height h of the pattern overlapping area in the splicing area is only 0.001-0.1 mm, and thus an ideal splicing effect is achieved.

Description

Technical Field

[0001] This invention relates to a laser direct imaging method, and more particularly to a laser segmented exposure stitching imaging method. Background Technology

[0002] Direct laser imaging (DLI) uses laser scanning to directly image a photomask. It's used in the exposure process of PCB manufacturing and screen printing. After exposure, the image remains on the photomask, and combined with subsequent copper plating, the PCB or screen printing is completed. The core imaging components of DLI include an image splitting system, a DMD (Digital Micromirror Device) control system, an optical projection system, and a motion platform control system.

[0003] In PCB manufacturing and screen printing, images are formed on a photomask. First, a segmentation system divides the original graphic into multiple units. The DMD (Digital Masking Device) control system processes this segmented data to display the graphic. For graphics with significant height, segmented exposure is often necessary. Current technology uses adjusting the height of the stitching area between adjacent exposure segments to achieve graphic stitching. However, this adjustment is often mishandled, leading to excessive energy at the stitching point or gaps in the graphic. Therefore, achieving high-quality segmented exposure stitching is a pressing technical challenge. Summary of the Invention

[0004] To address the aforementioned technical problems, this invention provides a laser segmented exposure stitching imaging method. The technical solution of this invention is: a laser segmented exposure stitching imaging method, which includes the following steps:

[0005] S1: Processing graphic height data of the splicing area

[0006] A total exposure pattern on the photomask is defined as a rectangle PQTS, with dimensions W×H. This total exposure pattern is divided into a first theoretical exposure pattern and a second theoretical exposure pattern. Based on the dimensions W×H1 of the first theoretical exposure pattern and W×H2 of the second theoretical exposure pattern, the height Δy of the stitching area is calculated as H1+H2–H. The stitching area is defined as a rectangle P1BP2A, with dimensions W×Δy.

[0007] S2: Obtain the first and second actual exposure images.

[0008] Based on the stitching area graphic obtained in step S1 being a rectangle P1 BP2A, the stitching area graphic is cut along the diagonal P1 P2 of the rectangle. The upper part of the total exposure graphic belongs to the first actual exposure graphic P1 P2TS, and is defined as graphic id=0. The lower part of the total exposure graphic belongs to the second actual exposure graphic PQP2P1, and is defined as graphic id=1.

[0009] S3: Alignment Exposure Processing

[0010] Set the coordinates of point P1 on the diagonal of rectangle P1 BP2A as (X1, Y1) and the coordinates of point P2 on the diagonal of rectangle P1 BP2A as (X2, Y2). Calculate the position information of the first segment of the actual exposed graphic P1 P2TS, and expose the graphic with id = 0 within the exposure area.

[0011] The position information of the second segment of actual exposure pattern PQP2P1 is calculated, and the pattern with pattern id=1 in the exposure area is exposed.

[0012] Furthermore, in step S2, the height of the overlapping area of ​​the graphics in the splicing area is set to h. Points P1 and P2 are shifted upward by h to obtain points P3 and P4. The coordinates of point P3 are (X1, Y1+h) and the coordinates of point P4 are (X2, Y2+h). Then, the first segment of actual exposure graphics P1 P2TS is defined as graphic id = 0, and the second segment of actual exposure graphics PQP4P3 is defined as graphic id = 1.

[0013] Furthermore, repeat steps S1 and S2 to find all the images to be exposed on the mask and define them as image id=0 and image id=1 respectively. In step S3, expose all images id=0 and then expose all images id=1.

[0014] Furthermore, in step S1, the height Δy of the splicing area is 0.5-5mm.

[0015] Furthermore, in step S2, the height h of the overlapping area of ​​the graphics in the splicing area is 0.001-0.1mm.

[0016] Furthermore, in step S2, the height h of the overlapping area of ​​the graphics in the splicing area is 0.01 mm.

[0017] Furthermore, during the alignment exposure process in step S3, the laser is fixed while the mask moves on the three-dimensional motion stage.

[0018] The beneficial technical effects of this invention are:

[0019] The stitched area is divided along the diagonal of a rectangle. The portion above the upper section of the stitched area belongs to the first segment of the actual exposed image, and the portion below the lower section belongs to the second segment. During exposure, the first segment of the actual exposed image is exposed first, followed by the second segment. This avoids secondary exposure in the stitched area. Even when overlapping area exposure is used, the height h of the overlapping area in the stitched area is only 0.001-0.1mm, achieving an ideal stitching effect. Attached Figure Description

[0020] Figure 1 This is a schematic diagram illustrating the image quality of laser segmented exposure stitching in existing technologies;

[0021] Figure 2 This is a schematic diagram of a laser segmented exposure stitching imaging method in the prior art;

[0022] Figure 3 This is a schematic diagram illustrating the method for obtaining the height Δy of the spliced ​​area graphic in Examples 1 and 2;

[0023] Figure 4 This is a schematic diagram of laser segmented exposure in Example 1;

[0024] Figure 5 This is a schematic diagram of laser segmented exposure in Example 2. Figure 1 ;

[0025] Figure 6 This is a schematic diagram of laser segmented exposure in Example 2. Figure 2 ;

[0026] Figure 7 , 8 These are schematic diagrams of laser segmented exposure of the entire photomask in Examples 1 and 2;

[0027] Figure 9 (a) and (b) Schematic diagrams of the stitched imaging quality of laser segmented exposure in Examples 1 and 2. Detailed Implementation

[0028] In order to better understand the technical means of the present invention and to implement it in accordance with the contents of the specification, the specific embodiments of the present invention will be further described in detail below with reference to the accompanying drawings and examples. The following examples are used to illustrate the present invention, but are not intended to limit the scope of the present invention.

[0029] In the prior art, see Figure 1-2Assuming the total exposure pattern size on the photomask is W×H, and the pattern is directly divided into two exposure segments, the first segment has a size of W×H1, and the second segment has a size of W×H2. The height of the stitching area is Δy, then Δy = H1 + H2 – H. When Δy is large, since the stitching area is exposed in both the first and second segments, it results in repeated exposure, leading to excessively high energy in the stitching area, which does not meet process requirements. When Δy is too small, the first and second exposure segments may be disconnected, resulting in poor image quality. Examples one and two overcome the technical defects of direct segmented exposure in the prior art by adopting a segmented exposure method that divides the stitching area diagonally, resulting in excellent laser imaging image quality.

[0030] Example 1:

[0031] See Figure 3-4 7-9, Example 1 discloses a laser segmented exposure stitching imaging method, which includes the following steps:

[0032] S1: Processing graphic height data of the splicing area

[0033] A total exposure pattern on the photomask is defined as a rectangle PQTS, with dimensions W×H. This total exposure pattern is divided into a first theoretical exposure pattern and a second theoretical exposure pattern. Based on the dimensions W×H1 of the first theoretical exposure pattern and W×H2 of the second theoretical exposure pattern, the height Δy of the stitching area is calculated as H1+H2–H. The stitching area is defined as a rectangle P1BP2A, with dimensions W×Δy.

[0034] S2: Obtain the first and second actual exposure images.

[0035] Based on the stitching area graphic obtained in step S1 being a rectangle P1 BP2A, the stitching area graphic is cut along the diagonal P1 P2 of the rectangle. The upper part of the total exposure graphic belongs to the first actual exposure graphic P1 P2TS, and is defined as graphic id=0. The lower part of the total exposure graphic belongs to the second actual exposure graphic PQP2P1, and is defined as graphic id=1.

[0036] S3: Alignment Exposure Processing

[0037] Set the coordinates of point P1 on the diagonal of rectangle P1 BP2A as (X1, Y1) and the coordinates of point P2 on the diagonal of rectangle P1 BP2A as (X2, Y2). Calculate the position information of the first segment of the actual exposed graphic P1 P2TS, and expose the graphic with id = 0 within the exposure area.

[0038] The position information of the second segment of actual exposure pattern PQP2P1 is calculated, and the pattern with pattern id=1 in the exposure area is exposed.

[0039] In this specific embodiment, the stitching area is divided along the diagonal of a rectangle. The portion above the upper section of the stitching area belongs to the first segment of the actual exposure image, and the portion below the lower section belongs to the second segment of the actual exposure image. During exposure, the first segment of the actual exposure image is exposed first, followed by the second segment. The first and second segments of the actual exposure images can be seamlessly stitched together, avoiding secondary exposure in the stitching area. This specific embodiment uses a rectangular diagonal division method, which is easy to identify during image processing, has high resolution, facilitates accurate calculation, and results in excellent image quality. It is worth noting that in the prior art, the dimensions of the first and second theoretical exposure images cannot be used to achieve seamless image stitching using straight-line dividing lines. This is because there are many other types of straight-line segments in the PCB circuit board, which makes it impossible for the control system to effectively identify the straight-line dividing lines corresponding to seamless stitching.

[0040] More specifically, for the entire mask, in order to achieve the stitching and imaging of all images, steps S1 and S2 are repeated to find all the images to be exposed on the mask in sequence, and to define the images as image id=0 and image id=1 respectively. In step S3, all images id=0 are exposed and then all images id=1 are exposed.

[0041] In step S1, the height Δy of the stitching area is 0.5-5mm. The height Δy of the stitching area is calculated using the theoretical exposure pattern size of the first segment and the theoretical exposure pattern size of the second segment. In this embodiment, Δy is 0.5-5mm. The upper limit of Δy, 5mm, can be taken as the height of the rectangular area to be stitched. The pattern is cut along the diagonal of the rectangle and exposed in segments.

[0042] In step S3, during the alignment and exposure process, the laser is fixed, and the mask is moved in three dimensions using a three-dimensional motion stage. Through the movement of the mask, the laser performs segmented polishing to achieve high-quality image stitching.

[0043] Example 2:

[0044] See Figure 3 , 5-9. Example 2 discloses a laser segmented exposure stitching imaging method. The steps not mentioned in this imaging method are the same as those in Example 1. The difference is that due to system errors in the actual operation process, there may be very small stitching marks in the exposed pattern. In order to further reduce stitching marks and improve imaging quality, in step S2, the height of the overlapping area of ​​the pattern in the stitching area is set to h. Points P1 and P2 are translated upward by h to obtain points P3 and P4. The coordinates of point P3 are (X1, Y1+h) and the coordinates of point P4 are (X2, Y2+h). Then, the first segment of actual exposed pattern P1 P2TS is defined as pattern id = 0, and the second segment of actual exposed pattern PQP4P3 is defined as pattern id = 1.

[0045] More specifically, in step S1, the height Δy of the stitching area is 0.5-5mm. The height Δy is calculated using the theoretical exposure dimensions of the first and second segments. In this embodiment, Δy is 0.5-5mm, and the upper limit of Δy (5mm) can be taken as the height of the rectangular stitching area. The image is cut along the diagonal of the rectangle for segmented exposure, maintaining an overlapping image of height h at the diagonal. In step S2, the height h of the overlapping area in the stitching area is 0.001-0.1mm. The optimal height h is set to 0.01mm to obtain the best exposure effect. In actual exposure, stitching marks may appear at the straight line P1 P2. This can be eliminated by overlapping the upper and lower parts of the graphic. Assuming the height of the overlapping area is h, P1 P2 is shifted upwards by h to become P3P4. P3 is (X1, Y1 + h), and P4 is (X2, Y2 + h). The upper part of the total exposed graphic is P1 P2TS, and the lower part is PQP4P3. In this specific implementation, a method combining rectangular diagonal segmentation with overlapping area exposure is used. The height h of the overlapping area in the stitching region is only 0.001-0.1 mm, significantly reducing the overlapping area compared to the 0.5-5 mm value of Δy, achieving an ideal stitching effect.

[0046] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the technical principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for stitching imaging using laser segmented exposure, characterized in that, The imaging method includes the following steps: S1: Processing graphic height data of the splicing area A total exposure pattern on the photomask is defined as a rectangle PQTS, with dimensions W×H. This total exposure pattern is divided into a first theoretical exposure pattern and a second theoretical exposure pattern. Based on the dimensions W×H1 of the first theoretical exposure pattern and W×H2 of the second theoretical exposure pattern, the height Δy of the stitching area is calculated as H1+H2–H. The stitching area is defined as a rectangle P1BP2A, with dimensions W×Δy. S2: Obtain the first and second actual exposure images. Based on the stitching area graphic obtained in step S1 being a rectangle P1 BP2A, the stitching area graphic is cut along the diagonal P1 P2 of the rectangle. The upper part of the total exposure graphic belongs to the first actual exposure graphic P1 P2TS, and is defined as graphic id=0. The lower part of the total exposure graphic belongs to the second actual exposure graphic PQP2P1, and is defined as graphic id=1. S3: Alignment Exposure Processing Let the coordinates of point P1 on the diagonal of rectangle P1 BP2A be (X1, Y1), and the coordinates of point P2 on the diagonal of rectangle P1 BP2A be (X2, Y2). The position information of the first actual exposure pattern P1 P2TS is calculated, and the pattern with pattern id=0 in the exposure area is exposed; The position information of the second segment of actual exposure pattern PQP2P1 is calculated, and the pattern with pattern id=1 in the exposure area is exposed.

2. The laser segmented exposure stitching imaging method according to claim 1, characterized in that, In step S2, the height of the overlapping area of ​​the graphics in the splicing area is set to h. Points P1 and P2 are shifted upward by h to obtain points P3 and P4. The coordinates of point P3 are (X1, Y1+h) and the coordinates of point P4 are (X2, Y2+h). Then, the first segment of actual exposure graphics P1 P2TS is defined as graphic id=0, and the second segment of actual exposure graphics PQP4P3 is defined as graphic id=1.

3. A laser segmented exposure stitching imaging method according to claim 1 or 2, characterized in that, Repeat steps S1 and S2 to find all the images to be exposed on the mask and define them as image id=0 and image id=1 respectively. In step S3, expose all images id=0 and then expose all images id=1.

4. A laser segmented exposure stitching imaging method according to claim 1 or 2, characterized in that, In step S1, the height Δy of the splicing area is 0.5-5mm.

5. A laser segmented exposure stitching imaging method according to claim 1 or 2, characterized in that, In step S2, the height h of the overlapping area of ​​the graphics in the splicing area is 0.001-0.1mm.

6. The laser segmented exposure stitching imaging method according to claim 5, characterized in that, In step S2, the height h of the overlapping area of ​​the graphics in the splicing area is 0.01 mm.

7. The laser segmented exposure stitching imaging method according to claim 1, characterized in that, During the alignment and exposure process in step S3, the laser is fixed while the mask moves on the three-dimensional motion stage.

Images