Exposure machine inspection method

Abstract

The invention relates to the technical field of circuit board manufacturing, and discloses an exposure machine inspection method which comprises the following steps: S1, preparing a light copper plate, pre-processing the light copper plate, and then screen-printing solder resist ink on the light copper plate to form a solder resist plate; s2, pasting a plurality of exposure rulers on the solder mask; s3, exposing the light copper plate according to a preset exposure pattern by using an exposure machine to be checked; the area, where the exposure ruler is pasted, on the solder mask is defined as an oil covering area, the drawing area and the oil covering area are arranged at intervals, and the drawing area comprises at least four drawing subareas; each drawing subarea comprises a plurality of marking areas; s4, taking down the exposure ruler, carrying out developing by using a developing solution, carrying out visual inspection after developing, and confirming the position of an abnormal DMD drawing head; and S5, measuring the developed fourth drawing subarea by using a 3D measuring instrument. According to the method, the windowing stability of the exposure machine and the performance of each DMD drawing head can be accurately and efficiently evaluated, so that the quality scrap caused by poor exposure, drawing offset and the like is reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of circuit board manufacturing, and in particular to an exposure machine inspection method. Background Art

[0002] In the printed circuit board (PCB) industry, as customer design requirements for products continue to increase, particularly in system-in-package (SIP) substrate design, requirements for solder mask window size and alignment are becoming increasingly stringent. Currently, solder mask window size has shrunk to a limit of 80 to 150 microns, while alignment tolerances have also been reduced to ±15 to 20 microns. This shift places even higher demands on the accuracy and window stability of laser direct imaging (LDI) exposure systems.

[0003] Exposure machine performance directly impacts the yield of finished boards, especially quality defects like window misalignment, poor exposure, and misaligned window pattern segments, which can easily lead to reduced production efficiency and financial losses. Furthermore, the drawing performance of each exposure machine's drawing heads is affected not only by ambient environmental factors (such as air conditioning temperature and cleanroom humidity), but also by the degradation of LED lamps, which can cause fluctuations in window size and accuracy. Therefore, regular measurement and monitoring of exposure machines is crucial to ensure stability and avoid batch scrapping.

[0004] In actual quality monitoring and maintenance, in addition to relying on the exposure machine's built-in inspection routines, solder mask ink is printed, exposed, and developed on bare copper boards using specialized exposure patterns to simulate the window quality of actual production boards. The developed pattern is then measured using tools such as 3D linewidth meters to evaluate the exposure machine's performance. However, exposure pattern inspection requires multiple process steps, which is time-consuming and difficult to meet the needs of rapid monitoring. Furthermore, existing inspection accuracy cannot meet the requirements for evaluating ultra-small window openings and high-precision alignment.

[0005] Therefore, there is an urgent need for a technical solution that can accurately and efficiently evaluate the stability of the exposure machine window opening to address the shortcomings of the existing technology. Summary of the Invention

[0006] The purpose of the present invention is to design an exposure machine inspection method and an inspection substrate thereof that can accurately and efficiently evaluate the stability of the exposure machine window.

[0007] In order to achieve the above object, the present invention provides an exposure machine inspection method, comprising the following steps:

[0008] S1 prepares a bare copper plate, pre-treats it, and then screen-prints solder mask ink onto the bare copper plate to form a solder mask.

[0009] S2 sequentially places a plurality of exposure rulers on the solder mask along a first direction, wherein the number of exposure rulers is the same as the number of DMD drawing heads in the exposure machine to be inspected;

[0010] S3 uses an exposure machine to be inspected to expose the bare copper plate according to a preset exposure pattern to form a drawing area on the solder resist plate;

[0011] The area on the solder mask where the exposure ruler is posted is defined as a cover oil area, the drawing area and the cover oil area are spaced apart along a first direction, and the drawing area includes at least four drawing partitions spaced apart in the first direction, which are respectively defined as a first drawing partition for marking a horizontal line, a second drawing partition for marking a vertical line, a third drawing partition for marking an oblique line, and a fourth drawing partition for marking a rectangle;

[0012] Each of the drawing subareas includes a plurality of marking areas sequentially arranged along the second direction, and the number of the marking areas is the same as the number of the DMD drawing heads in the exposure machine to be inspected;

[0013] S4: Remove the exposure ruler, develop with developer, and visually inspect the first drawing partition, the second drawing partition, the third drawing partition, and the oil-covered area after development to confirm the abnormal DMD drawing head position;

[0014] S5 uses 3D measuring instruments to measure the fourth drawn partition after development to obtain window size compensation data;

[0015] The first direction and the second direction are perpendicular to each other.

[0016] Furthermore, the first drawing partition mark has multiple straight lines extending along the second direction, the second drawing partition mark has multiple straight lines extending along the first direction, and the third drawing partition mark has multiple straight lines extending along the third direction, the line width of each straight line is 0.2 mm, and the interval between two adjacent straight lines is 0.25 mm; wherein, the third direction is on the same plane as the first direction and the second direction.

[0017] Furthermore, the marking area includes a plurality of marking partitions sequentially connected along the second direction, and the number of the marking partitions is the same as the number of sub-heads of the DMD drawing head.

[0018] Furthermore, a spacer mark is provided between two adjacent marking areas and between two adjacent marking subareas.

[0019] Furthermore, the fourth drawing zone is marked with a plurality of groups of rectangular patterns, and the plurality of groups of rectangular patterns are arranged in an array in each of the marking zones of the fourth drawing zone, and each group of rectangular patterns includes two rectangles arranged at intervals.

[0020] Furthermore, the size of the rectangle in the first direction is 217.5 um, and the size in the second direction is 187.5 um; or

[0021] The size of the rectangle in the first direction is 187.5 um, and the size in the second direction is 217.5 um.

[0022] Furthermore, the pretreatment in S1 is: using H2SO4 / H202 micro-etching solution to ultra-roughen the bare copper plate; controlling the wet film thickness to 22-24um during screen printing, and pre-baking at 78°C for 38 minutes after screen printing.

[0023] Furthermore, the exposure energy during exposure in S3 is 60 mj / cm 2 The specific steps of developing in S5 are: soaking in K2CO3 with a concentration of 8.3-8.5 g / L and a temperature of 35-40°C for 55-60 seconds.

[0024] Furthermore, the visual inspection includes: using a 10X magnification lens to perform a visual inspection of the first drawing partition, the second drawing partition, and the third drawing partition to observe whether the straight line is offset, staggered, or has a step difference, so as to locate the abnormal position and affected area of the DMD drawing head.

[0025] Furthermore, the S5 includes the following specific steps: measuring the actual size of each rectangle after development and outputting the data to the analysis software, and the analysis software confirms after data analysis whether the window size of the DMD drawing head is too high or too low to adjust the subsequent work of the exposure machine.

[0026] Compared with the prior art, the exposure machine inspection method according to the embodiment of the present invention has the following advantages:

[0027] The exposure machine inspection method of the embodiment of the present invention can efficiently and accurately inspect the window size stability, step difference detection and exposure energy uniformity of each DMD drawing head of the exposure machine through the design of the exposure pattern, and accurately and efficiently evaluate its window stability, thereby reducing quality scrap caused by poor exposure and drawing offset, improving economic benefits, and has important practical application value and market prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 1 is a schematic plan view of an exposure pattern preset in an exposure machine inspection method according to an embodiment of the present invention;

[0029] Figure 2 yes Figure 1 A magnified schematic diagram of point A in the middle;

[0030] Figure 3 yes Figure 1A magnified schematic diagram of point B in the middle;

[0031] Figure 4 is a box plot of the deviation in the y-direction of the DMD head window size output by the analysis software according to the size of the rectangle in the fourth drawing partition in the exposure machine inspection method according to an embodiment of the present invention;

[0032] Figure 5 It is a box plot of the deviation of the DMD head window size in the x-direction output by the analysis software according to the rectangular size in the fourth drawing partition in the exposure machine inspection method according to an embodiment of the present invention.

[0033] In the figure, 1, solder mask; 2, oil cover area; 3, first drawing partition; 4, second drawing partition; 5, third drawing partition; 6, fourth drawing partition; 7, mark partition; 8, rectangular pattern; x, first direction; y, second direction; z, third direction. DETAILED DESCRIPTION

[0034] The following embodiments of the present invention are described in further detail 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.

[0035] In the description of the present invention, it should be understood that the terms "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside" and "outside" used in the present invention to indicate the orientation or position relationship are based on the orientation or position relationship shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operate in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0036] In the description of the present invention, it should be understood that the terms "connected," "connected," "fixed," etc. used in the present invention should be interpreted broadly. For example, the terms may be fixedly connected, detachably connected, or integrated; may be mechanically connected or welded; may be directly connected or indirectly connected through an intermediate medium; may be internal communication between two elements or an interactive relationship between two elements, unless otherwise clearly defined. For those skilled in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0037] The present invention uses terms such as "first" and "second" to describe various types of information, but the information should not be limited to these terms. These terms are used only to distinguish information of the same type from each other. For example, "first" information can also be referred to as "second" information, and similarly, "second" information can also be referred to as "first" information without departing from the scope of the present invention.

[0038] In the description of the present invention, the first direction x, the second direction y, and the third direction z are all located on the same plane, and the first direction x and the second direction y are perpendicular or approximately perpendicular to each other.

[0039] Reference Figures 1 to 3 , an exposure machine inspection method according to an embodiment of the present invention includes the following steps:

[0040] S1 prepares a bare copper plate, pre-treats it, and then screen-prints solder mask ink onto the bare copper plate to form a solder mask.

[0041] S2 sequentially places a plurality of exposure rulers on the solder mask along a first direction x, wherein the number of exposure rulers is the same as the number of DMD drawing heads in the exposure machine to be inspected;

[0042] S3 uses an exposure machine to be inspected to expose the bare copper plate according to a preset exposure pattern to form a drawing area on the solder resist plate;

[0043] The area on the solder mask where the exposure ruler is posted is defined as the oil covering area 2, the drawing area is spaced apart from the oil covering area 2 along a first direction x, and the drawing area includes at least four drawing partitions spaced apart in the first direction x, which are defined as a first drawing partition 3 for marking a horizontal line, a second drawing partition 4 for marking a vertical line, a third drawing partition 5 for marking an oblique line, and a fourth drawing partition 6 for marking a rectangle;

[0044] Each of the drawing subareas includes a plurality of marking areas sequentially arranged along the second direction y, and the number of the marking areas is the same as the number of the DMD drawing heads in the exposure machine to be inspected;

[0045] S4: Remove the exposure ruler, develop with developer, and visually inspect the first drawing area 3, the second drawing area 4, the third drawing area 5, and the oil-covered area 2 after development to confirm the abnormal DM drawing head position;

[0046] S5 uses a 3D measuring instrument to measure the fourth drawn subarea 6 after development to obtain window size compensation data.

[0047] In some improved solutions of the present application, the first drawing partition 3 is marked with multiple straight lines extending along the second direction y, the second drawing partition 4 is marked with multiple straight lines extending along the first direction x, and the third drawing partition 5 is marked with multiple straight lines extending along the third direction z. The line width of each straight line is 0.2 mm, and the interval between two adjacent straight lines is 0.25 mm; wherein, the third direction z is on the same plane as the first direction x and the second direction y.

[0048] In some improved solutions of the present application, the marking area includes a plurality of marking partitions 7 sequentially connected along the second direction y, and the number of the marking partitions 7 is the same as the number of sub-heads of the DMD drawing head.

[0049] In some improved solutions of the present application, a spacer symbol mark is provided between two adjacent marking areas and between two adjacent marking subareas 7 .

[0050] In some improved solutions of the present application, the fourth drawing zone 6 is marked with multiple groups of rectangular patterns, which are arranged in an array in each of the marking zones 7 of the fourth drawing zone 6, and each group of rectangular patterns includes two rectangles arranged at intervals.

[0051] In some improved solutions of the present application, the size of the rectangle in the first direction x is 217.5um, and the size in the second direction y is 187.5um; the size of the rectangle in the first direction x is 187.5um, and the size in the second direction y is 217.5um.

[0052] In some improved solutions of the present application, the pretreatment in S1 is: using H2SO4 / H202 micro-etching solution to ultra-roughen the bare copper plate; controlling the wet film thickness to 22-24um during silk screen printing, and pre-baking at 78°C for 38 minutes after silk screen printing.

[0053] In some improved solutions of the present application, the specific step of developing in S5 is: soaking in K2CO3 with a concentration of 8.3-8.5 g / L and a temperature of 35-40°C for 55-60 seconds.

[0054] In some improved solutions of the present application, the visual inspection includes: using a 10X magnification lens to visually inspect the first drawing partition 3, the second drawing partition 4, and the third drawing partition 5 to observe whether the straight line is offset, misaligned or has a step difference, so as to lock the abnormal position and affected area of the DMD drawing head.

[0055] In some improved solutions of the present application, the S5 includes the following specific steps: measuring the actual size of each rectangle after development and outputting the data to the analysis software. After the analysis software performs data analysis, it is confirmed that the window size of the DMD drawing head is too high or too low to adjust the subsequent work of the exposure machine.

[0056] In the specific embodiment of this application, the specific operating steps are as follows:

[0057] First, a 1.0mm thick FR4 copper plate was prepared. Its width (i.e., its dimension in the first direction x) was 540mm, and its length (i.e., its dimension in the second direction y) was 650mm. The surface was roughened using an H2SO4 / H2O2 solution to enhance ink adhesion. A 62T mesh screen-printed solder mask ink was applied to the copper plate, with a wet film thickness of 22-24µm. The printed pattern was completely covered with ink, specifically, a length of 630mm and a width of 530mm. After screen printing, the plate was pre-baked at 78°C for 38 minutes to remove the solvent and initially cure the ink, forming the solder mask.

[0058] The solder mask is exposed using the exposure machine to be tested. The exposed pattern is pre-designed. In this specific implementation, an ORC, DXP-3512 exposure machine is used for testing. The exposure machine has 8 DMD drawing heads, each of which is divided into three sub-heads, with a total of 24 marking partitions 7. The exposure energy of the exposure machine is 60mj / cm 2 ,

[0059] The pre-designed exposure pattern measures 520mm in the first x-direction and 620mm in the second y-direction. The solder mask is divided into the first, second, third, and fourth drawing zones 3, 4, 5, and 6, spaced apart along the second y-direction. Each drawing zone is divided into eight marking zones, spaced 67.5mm apart from the center, corresponding to the 67.5mm spacing of a DMD head. Each marking zone is evenly divided into three smaller marking zones 7, corresponding to the three sub-heads of a single drawing head. The 24 marking zones within each marking zone are labeled DMD1-1, DMD1-2, DMD1-3, and so on, along the first x-direction as DMD8-3. Inverted diamond-shaped markers serve as separators between the marking zones, and dashed line separators serve as separators between the marking zones 7.

[0060] The first drawing zone 3 is designed with straight lines extending along the first direction x, the second drawing zone 4 is designed with straight lines extending along the second direction y, and the third drawing zone 5 is designed with straight lines extending along the third direction z. There are 10 straight lines, each with a line width of 0.2 mm and a spacing of 0.25 mm. Specifically, the angle between the third direction z and the first direction x and the second direction y can be 45°. After development, a 10X magnification microscope is used to visually inspect the straight lines in each DMD marking zone 7 for any deviation, misalignment, or step differences. If deviation occurs, the line smoothness can be observed, allowing for quick visual identification of the abnormal position and affected area of the DMD drawing head.

[0061] The fourth mapping zone 6 is used to monitor the dimensional stability of the window openings of the eight DMD heads, specifically the 24 sub-heads. Specifically, each marking zone 7 within the fourth mapping zone 6 features a rectangular pattern, eight in the first direction x and ten in the second direction y, arranged in an 8x10 matrix. Each rectangular pattern consists of a pair of two rectangular windows, each measuring 217.5 μm long by 187.5 μm wide. The long sides of the rectangular windows can be parallel to either the first direction x or the second direction y, respectively, to monitor the window openings of the sub-heads in the first x and second y directions. A small square with an inner circle length*width of 0.8 mm*0.8 mm and an inner circle length*width of 1 mm*1 mm is also located in the upper left corner of the marking zone 7 as an alignment target for subsequent alignment when the system measures the window openings.

[0062] In the middle of the board, an oil covering area 2 with a size of 150 mm in the second direction y is reserved for posting an exposure scale before exposure. Specifically, 33-level exposure scales can be posted at intervals along the first direction x with a spacing of 67.5 mm, which can just ensure that all 8 DMD drawing heads can measure the corresponding exposure technology through the exposure scale. The exposure level difference of the 8 DMDs is required to be ≤ 2 levels.

[0063] According to the above exposure energy and the designed exposure pattern, development is carried out, and the development adopts K-ray dilution with a concentration of 8.3-8.5 g / L and a temperature of 35-40 ° C. 2 CO 3 , the immersion time is 55-60s. After development, a visual inspection is performed with a 10X magnification microscope. The line graphics of the first drawing area 3, the second drawing area 4, and the third drawing area 5 are mainly used to check whether the drawing head is skewed, misaligned, or has a step difference. The rectangular window array of the fourth drawing area 6 is mainly used to measure the difference between the average window size and the target value, so as to facilitate the equipment supplier to adjust the window compensation of each DMD drawing head. The oil cover area 2 is used to check the uniformity of the exposure energy to avoid excessive energy differences in some areas, resulting in color difference on the ink surface, insufficient light curing, and other quality abnormalities.

[0064] The specific measurement of the window size can be achieved by using a 3D measuring instrument. By grabbing the rectangular window array pattern and the alignment target on the corresponding marking partition 7, the actual size of the rectangular window in the first direction x and the second direction y after development is measured. At least 32 sets of data are output and a box plot is made using the corresponding output software (refer to Figure 4 and Figure 5 ) can identify areas where the DMD window is too small, facilitating subsequent window compensation adjustments to the exposure machine. Through software output and corresponding output box plots, data analysis software can be used to identify DMD heads with low or high DMD window openings, facilitating subsequent adjustments by equipment suppliers.

[0065] In summary, the embodiment of the present invention provides an exposure machine inspection method, which can efficiently and accurately inspect the window size stability, step difference detection and exposure energy uniformity of each DMD drawing head of the exposure machine through the design of the exposure pattern, thereby improving production efficiency, preventing and reducing quality scrap caused by equipment abnormalities, and thus improving economic benefits; it can also shorten the maintenance and inspection time of the exposure machine, and can accurately confirm the abnormal drawing head position and window size, with significant improvement effects, further improving production efficiency, and overall improving the economic benefits of the product.

[0066] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and substitutions can be made without departing from the technical principles of the present invention. These improvements and substitutions should also be regarded as the scope of protection of the present invention.

Claims

1. An exposure machine inspection method, characterized in that: The following steps are involved: S1 prepares a bare copper plate, pre-treats it, and then screen-prints solder mask ink onto the bare copper plate to form a solder mask; S2 sequentially places a plurality of exposure rulers on the solder mask along a first direction, wherein the number of exposure rulers is the same as the number of DMD drawing heads in the exposure machine to be inspected; S3 uses an exposure machine to be inspected to expose the bare copper plate according to a preset exposure pattern to form a drawing area on the solder resist plate; The area on the solder mask where the exposure ruler is posted is defined as a cover oil area, the drawing area and the cover oil area are spaced apart along a first direction, and the drawing area includes at least four drawing partitions spaced apart in the first direction, which are respectively defined as a first drawing partition for marking a horizontal line, a second drawing partition for marking a vertical line, a third drawing partition for marking an oblique line, and a fourth drawing partition for marking a rectangle; Each of the drawing subareas includes a plurality of marking areas sequentially arranged along the second direction, and the number of the marking areas is the same as the number of the DMD drawing heads in the exposure machine to be inspected; S4: Remove the exposure ruler, develop with developer, and visually inspect the first drawing partition, the second drawing partition, the third drawing partition, and the oil-covered area after development to confirm the abnormal DMD drawing head position; S5 uses 3D measuring instruments to measure the fourth drawn partition after development to obtain window size compensation data; The first direction and the second direction are perpendicular to each other.

2. The exposure machine inspection method according to claim 1, wherein: The first drawing partition mark has multiple straight lines extending along the second direction, the second drawing partition mark has multiple straight lines extending along the first direction, and the third drawing partition mark has multiple straight lines extending along the third direction. The line width of each straight line is 0.2 mm, and the interval between two adjacent straight lines is 0.25 mm; wherein the third direction is on the same plane as the first direction and the second direction.

3. The exposure machine inspection method according to claim 1, wherein: The marking area includes a plurality of marking partitions sequentially connected along the second direction, and the number of the marking partitions is the same as the number of sub-heads of the DMD drawing head.

4. The exposure machine inspection method according to claim 3, wherein: A spacer mark is provided between two adjacent marking areas and between two adjacent marking subareas.

5. The exposure machine inspection method according to claim 3, wherein: The fourth drawing zone is marked with a plurality of groups of rectangular patterns, which are arranged in an array in each of the marking zones of the fourth drawing zone, and each group of rectangular patterns includes two rectangles arranged at intervals.

6. The exposure machine inspection method according to claim 5, wherein: The size of the rectangle in the first direction is 217.5 μm, and the size in the second direction is 187.5 μm; or The size of the rectangle in the first direction is 187.5 um, and the size in the second direction is 217.5 um.

7. The exposure machine inspection method according to claim 1, wherein: The pretreatment in S1 is as follows: using H2SO4 / H2O2 micro-etching solution to super-roughen the bare copper plate; controlling the wet film thickness to 22-24 μm during screen printing, and pre-baking at 78° C. for 38 minutes after screen printing.

8. The exposure machine inspection method according to claim 1, wherein: The specific steps of the development in S5 are: soaking in K2CO3 with a concentration of 8.3-8.5 g / L and a temperature of 35-40°C for 55-60 seconds.

9. The exposure machine inspection method according to claim 2, wherein: The visual inspection includes: using a 10X magnification lens to visually inspect the first drawing partition, the second drawing partition, and the third drawing partition to observe whether the straight line is offset, staggered, or has a step difference, so as to locate the abnormal position and affected area of the DMD drawing head.

10. The exposure machine inspection method according to claim 6, wherein: The S5 includes the following specific steps: measuring the actual size of each rectangle after development and outputting the data to the analysis software, and the analysis software confirms after data analysis whether the window size of the DMD drawing head is too high or too low to adjust the subsequent work of the exposure machine.

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