JP4187332B2 - Screen printing inspection method and screen printing apparatus - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for inspecting a printing result of a screen printing apparatus.
[0002]
[Prior art]
The screen printing device prints at a predetermined position on a printed board such as a printed circuit board, such as when applying adhesive to the electronic component bonding position of a printed circuit board or printing cream solder at a lead wire connection position. This is a device for printing the agent. In this screen printing apparatus, generally, by moving a squeegee on a screen, a printing agent placed on the screen is printed on a printing plate through a through hole formed in the screen.
[0003]
In this way, when printing agent is printed on a printing plate, printing may be defective. For example, the printing agent may not be printed at some printing positions, the printing amount may be insufficient, and the printing position may be shifted. Such printing defects may occur due to clogging caused by clogging of the printing agent in the through holes of the screen, lack of printing agent, misalignment between the screen and the printing plate, etc. It is known that printing results such as printing amount, printing position and presence / absence of printing, printing area, and the like can be obtained and inspected based on inspection data prepared in advance to determine whether or not printing is defective. The inspection data is data for determining whether or not there is a defect in the printing result. If there is a printing defect, good printing is performed by removing the cause of the detected printing defect. Can do.
[0004]
A conventional inspection method for determining a print result using inspection data will be described with reference to FIGS. FIG. 4 is a block diagram of a screen printing apparatus having a conventional inspection apparatus.
[0005]
In FIG. 4, reference numeral 41 denotes inspection data storage means for storing inspection data for inspecting the result of screen printing created in advance by another means, and reference numeral 42 denotes a plane for obtaining a planar view image on the printing plate. The visual image acquisition means 43 is a printing result determination means for determining a printing result from the inspection data stored in the inspection data storage means 41 and the planar image of the printing plate acquired by the planar vision image acquisition means 42. is there. A control unit 44 includes an inspection data storage unit 41 and a print result determination unit 43. Incidentally, 45 is a printing means for executing screen printing, and 46 is a printing failure cause removal means for removing the cause of printing failure.
[0006]
The operation of the screen printing apparatus configured as described above will be described with reference to the flowchart of FIG. First, in step 1, inspection data is created and stored in the inspection data storage means 41 before printing. A method for creating inspection data will be described later. Thereafter, printing is performed by the printing unit 45 in step 2, and a planar view image on the printed board after printing is obtained by the planar view image obtaining unit 42 in step 3. In step 4, the print result determination means 43 determines pass / fail of the print result based on the inspection data and the planar image after printing after printing. If it is determined that there is a printing failure, the cause of the printing failure is removed by the printing failure cause removing means 46 in step 5. In step 6, it is determined whether or not the production is to be terminated.
[0007]
Next, three methods generally used as methods for creating inspection data will be described.
1. Method of creating inspection data using a model printed board When the printing agent is actually printed on the printed board and all of the printing amount, printing position, and printing area are printed properly, the printed board is The printing plate is used, and the printed printing agent is imaged with a camera to create inspection data.
2. Method of creating inspection data using CAD data Method of using CAD data for creating printed circuit board as a method of creating inspection data when printing results are inspected when cream solder is printed on printed circuit board There is. CAD data is data for forming a wiring pattern on a printed circuit board. Since the position where electronic circuit components are attached can be known from the wiring pattern, the print position, printing area, etc. of cream solder are obtained from that position and inspected. Create data.
3. Method for creating inspection data from a planar image on the screen The position and area of the through hole on the screen correspond to the position and area of the printing agent printed on the printing plate. The inspection data such as the printing position and the printing area of the printing agent is created based on the planar view image including
[0008]
[Problems to be solved by the invention]
However, there are some problems in the method for determining the printing result using the inspection data as described above.
[0009]
First, one problem is that it is difficult and troublesome to create inspection data. When creating test data by creating a model printing board, screen printing must be performed many times until the printing agent is printed on the printing board in a state where appropriate testing data can be created. In addition, it takes time for the operator to prepare inspection data. Furthermore, since screen printing is performed many times until an appropriate model printing plate can be created, there is a problem that the printing agent and the printing plate are wasted.
[0010]
When creating inspection data based on CAD data, there is a problem that processing of CAD data is necessary. Generally, cream solder is printed on a part of a wiring pattern defined by CAD data. Therefore, it cannot be used as it is for inspection data for inspecting a print result, and it is necessary to process CAD data. The CAD data is design data, and does not necessarily represent the state of being actually printed properly using a screen, and may be inaccurate as inspection data for inspecting the print result.
[0011]
The inspection data includes only data such as the print position and print area. Therefore, when trying to use an image in plan view of the printing plate when inspecting the printing result, the color tone of the pattern printed on the printing plate before screen printing is similar to the color tone of the printing agent In this case, only the printing agent cannot be extracted, and there is a possibility of making a false determination. In order to prevent this, parameters for detecting the color difference between the printing agent and the printing plate may be prepared in the inspection data, but even in that case, all the printing plates used for production have the same color tone. Therefore, there is a variation in color tone depending on the printing plate, and the inspection may not be performed correctly. Although such a problem does not exist when inspection is performed using a laser displacement meter rather than using an image in a plan view, generally a screen printing apparatus has a printing target for positioning a printing plate. Although means for obtaining a planar image of the plate is prepared, there is a problem that the cost of the equipment is increased because a laser displacement meter is not prepared.
[0012]
SUMMARY OF THE INVENTION The present invention solves the above-mentioned problems, and can reduce the inspection data that must be prepared before printing for the inspection of the printing result, and can reduce the erroneous determination caused by the variation in the color tone of the printing plate. It is an object of the present invention to provide a screen printing inspection method and a screen printing apparatus.
[0013]
[Means for Solving the Problems]
In order to solve the above problems, the screen printing inspection method of the present invention inspects a printing result after printing a printing agent on a printing plate through a plurality of through holes formed on the screen by moving a squeegee. A screen printing inspection method for obtaining an image obtained by planarly viewing a portion including a through hole on a screen, and obtaining a position and a printing area where a printing agent is to be printed from the obtained planar image of the screen And a step of acquiring a planar view image of the printing plate corresponding to the acquisition position of the planar view image of the screen before the screen printing is performed, and on the printing plate before printing from the obtained planar view image of the printing plate. Extracting the features on the image where the printing agent should be printed and where the printing agent should not be printed, obtaining the image in plan view of the printed board after screen printing, Extracting the features on the image of the printed material on the printed board after printing and the unprinted image features from the planar image of the printed board after screen printing, And a step of comparing a feature on the image of the planar view image of the printing plate and determining a printing result.
[0014]
According to this method, it is possible to reduce the inspection data that must be prepared before printing for the inspection of the printing result, and it is possible to reduce the erroneous determination caused by the variation in the color tone of the printing plate.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
The screen printing inspection method of the present invention is a screen printing inspection method for inspecting a printing result after a printing agent is printed on a printing plate through a plurality of through holes formed in the screen by moving a squeegee. Obtaining a plan view image of a portion including the through hole on the screen, obtaining a position and a printing area where the printing agent is to be printed from the obtained plan view image of the screen, and a plan view image of the screen A step of acquiring a planar view image of the printing plate corresponding to the acquisition position of the printing plate before screen printing, and a printing agent on the printing plate before printing from the obtained planar view image of the printing plate A step of extracting features on an image of a portion and a portion that should not be printed, a step of obtaining a planar view of a printed board after screen printing execution, and execution of acquired screen printing Extracting the features on the image of the printed and unprinted areas on the printed board from the planar image of the printed board, and the planar view of the printed board before and after printing And a step of comparing the characteristics of the images on the image and determining the print result.
[0016]
The screen printing apparatus of the present invention is a screen printing apparatus for printing a printing agent on a printing plate through a plurality of through holes formed in the screen by moving a squeegee on the screen. In addition to the print defect cause removing means 19 for removing the cause of the print defect, the inspection execution position storage means 11 for storing the position for performing the inspection on the print result of the screen printing, and the plane of the portion including the through hole on the screen A printing position / printing area for obtaining a printing agent printing position and area from a first planar image acquisition unit 12 that acquires an image in viewing and a planar image acquired by the first planar image acquisition unit 12 Extraction means 13 and second planar image acquisition means 1 for acquiring an image of the printed board corresponding to the acquisition position of the planar image on the screen in planar view And feature extraction for extracting the features on the image of the printed portion and the non-printed portion of the printing agent obtained by the printing position / printing area extracting unit 13 from the planar image acquired by the second planar image acquiring unit 14 And means 15 and a print result determination means 16 for determining the print result by comparing the features on the image of the planar image of the printing plate before and after printing obtained by the feature extraction means 15. Is.
[0017]
In the screen printing inspection method and the screen printing apparatus, when a planar view image of the screen is acquired, the position and area of the through hole are known, and the position and area of the through hole are the position and area of the printing agent to be printed on the printing plate. It corresponds. By acquiring a planar view image of the corresponding portion of the printing plate before printing, the features on the image of the portion where the printing agent is printed and the portion where the printing agent is not printed are acquired. The feature on the image acquired here may be any feature representing the feature of the point, such as luminance, hue, saturation, brightness, or any combination thereof. Even after the printing is actually executed, a planar view image of the same portion on the printing plate is acquired, and similarly, the features on the image of the printed portion and the unprinted portion are acquired. In the area where the printing agent is not printed, the characteristics of the planar image of the printed board do not change before and after printing, and in the area where the printing material is printed, the characteristics of the planar image of the printed board depend on before and after printing. Since it changes, it is possible to determine the printing result by comparing the features on the image of the planar image of the printing plate obtained before and after printing. In this way, it is possible to correctly determine the print result without preparing inspection data for inspecting the print result by taking a lot of time and effort as in the prior art.
[0018]
Hereinafter, embodiments of the present invention will be described with reference to FIGS.
[0019]
FIG. 1 is a block diagram showing the configuration of a screen printing apparatus having an inspection apparatus according to the present invention.
[0020]
As shown in FIG. 1, this screen printing apparatus includes an inspection execution position storage unit 11 that stores a position for performing an inspection on a printing result of screen printing, and an image in plan view of a portion including a through hole on the screen. The first planar image acquisition means 12 for acquiring the print position and the printing position / print area extraction means 13 for obtaining the printing agent printing position and its area from the planar image acquired by the first planar image acquisition means 12. A second planar image acquisition unit 14 that acquires an image in a planar view of the printing plate corresponding to the acquisition point of the planar image on the screen, and a plane acquired by the second planar image acquisition unit 14 A feature extraction unit 15 for extracting features on the image of the printing portion and non-printing portion of the printing agent obtained by the printing position / printing area extraction unit 13 from the visual image, and a mark obtained by the feature extraction unit 15 A print result determining means 16 for determining the characteristics to compare with the print result on the image of the viewed image of the front and rear of the printing plate is provided. Reference numeral 17 denotes a control unit having an inspection execution position storage unit 11, a print position / area extraction unit 13, a feature extraction unit 15, and a print result determination unit 16, 18 a printing unit for executing screen printing, and 19 a printing failure. This is a printing defect cause removing means for removing the cause of the above.
[0021]
FIG. 2 is a perspective view of the screen printing apparatus. As shown in FIG. 2, the printing means 18 of the screen printing apparatus holds an XY table unit 21 that holds a printing plate and moves it to a printing position, a screen holding unit 22 that holds the screen, and a squeegee. In this state, a print head unit 23 that performs screen printing by moving the screen is provided. Further, in this screen printing apparatus, a printing defect cause removing unit is configured by a cleaner unit for wiping and removing the printing agent adhering to the screen using paper. The two plane view image acquisition means 14 are constituted by one plane view image acquisition means, and the plane view image acquisition means 12 (14) acquires a plane view image on the screen or the printing plate.
[0022]
Further, as an example of the defective print cause removing means 19 in FIG. 1, the case of the cleaner portion is shown in FIG. 2, but the cause of the defective print is present other than the stain on the screen. Any means may be used as long as it can eliminate the cause of printing failure.
[0023]
The operation of the screen printing apparatus configured as shown in FIGS. 1 and 2 will be described with reference to the flowchart of FIG.
[0024]
First, in step 1, an image obtained by planarly viewing a portion including a through-hole on the screen, which is an inspection position stored in the inspection execution position storage unit 11, is acquired by the (first) plane-view image acquisition unit 12. . At that time, it is not always necessary to acquire an image of the entire screen. In general, printing defects are likely to occur in small through holes, and high printing accuracy is required. Therefore, only these small through holes may be inspected. In that case, the peripheral portion including the small through holes may be inspected. All you have to do is get an image. Alternatively, an image of only a portion where the through holes are concentrated or only a portion having special circumstances such as a peripheral portion of the screen may be acquired. This inspection execution position may be one place or a plurality of places.
[0025]
Since the position and area of the through hole correspond to the printing position and area of the printing agent to be printed on the printing plate, in step 2, the printing position / area extracting means is obtained from the planar view image of the screen acquired in step 1. 13 is used to obtain the printing position and printing area of the printing agent to be printed on the printing plate.
[0026]
In step 3, the (second) planar image acquisition means 14 is used to acquire a planar image of the printed board before screen printing. Here, the acquired planar view image must correspond to the location corresponding to the planar view image of the screen in Step 1.
[0027]
After that, in step 4, the printing agent should be printed before screen printing is performed using the feature extraction unit 15 from the printing position / area of the printing agent obtained in step 2 and the planar image obtained in step 3 Find image features of locations and locations that should not be printed. The acquired feature on the image may be any feature representing the feature of the point, such as brightness, hue, saturation, brightness, or any combination thereof.
[0028]
In the next step 5, screen printing is executed by the printing means 18. In step 6, a planar view image of the printing plate after screen printing is obtained using the (second) planar view image acquisition means 14. In step 7, as on step 4, printing on the printing plate after screen printing is performed using feature extraction means 15 from the printing position / area of the printing agent obtained in step 2 and the planar image obtained in step 6. The feature on the image of the printed part and the non-printed part of the agent is obtained.
[0029]
In step 8, the image characteristics of the planar image of the printing plate before and after the screen printing obtained in step 4 and step 7 are compared between the printing place of the printing agent and the non-printing place, and the printing result is determined. The printing result is determined by means 16. If the printing agent is printed correctly, the image characteristics of the planar image of the printing plate change before and after the screen printing at the place where the printing agent is to be printed, and the printing material is printed at the place where the printing agent is not to be printed. Since the feature on the image of the plan view image of the plate does not change before and after the screen printing, it is possible to determine the printing result.
[0030]
If it is determined in step 8 that the print result is NG, the cause of print failure is removed in step 9 using the print failure cause removing means 19. In step 10, it is determined whether or not the production is to be ended. If the production is continued, the process returns to step 3.
[0031]
In this way, it is possible to correctly determine the print result without much effort and time.
[0032]
As in the above embodiment, the first planar image acquisition unit 12 and the second planar image acquisition unit 14 may be the same, which is superior in cost. It is not limited, and different ones can be used. Further, although the step of extracting the features from the planar view image of the printing plate before printing is performed immediately after obtaining the planar view image, it may be performed anywhere before the step of determining the printing result. Furthermore, when the printing result is NG, the cause of the printing failure is removed by the printing failure cause removing unit 19, but the operator may be notified without using the printing failure cause removing unit 19.
[0033]
【The invention's effect】
As described above, according to the present invention, as inspection data that must be prepared before actual printing, it is only necessary to extract the features by imaging the screen and the printing plate at the position where the inspection is performed. It is possible to create quick and accurate data without requiring the skill of an operator. In addition, although the printing result can be determined satisfactorily, the laser displacement meter is not used, so that there is no cost. In addition, since the features on the image of the planar image of the printed board before and after printing are acquired for each printing and the printing result is inspected by comparison, correct inspection is performed even if the printed board has color variations. It is possible to prevent the occurrence of erroneous determination as in the prior art, and the reliability is improved.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a configuration of a screen printing apparatus according to an embodiment of the present invention. FIG. 2 is a perspective view of the screen printing apparatus. FIG. 3 is a flowchart showing an operation of a screen printing inspection method by the screen printing apparatus. FIG. 4 is a block diagram showing the configuration of a conventional screen printing apparatus. FIG. 5 is a flowchart showing the operation of a conventional screen printing inspection method.
DESCRIPTION OF SYMBOLS 11 Inspection execution position memory | storage means 12 1st plane view image acquisition means 13 Print position and area extraction means 14 2nd plane view image acquisition means 15 Feature extraction means 16 Print result determination means 17 Control part 18 Print means 19 Cause of printing defect Removal means

Claims (2)

A screen printing inspection method for inspecting a printing result after moving a squeegee on a screen and printing a printing agent on a printing plate through a plurality of through holes formed in the screen, including a through hole on the screen A step of obtaining an image obtained by planarly viewing the portion, a step of obtaining a position and a printing area where the printing agent is to be printed from the obtained planar image of the screen, and a printing plate corresponding to the acquisition position of the planar image of the screen A step of acquiring a planar image before screen printing is performed, and a portion on which the printing agent on the printing plate before printing is to be printed and a portion not to be printed from the obtained planar image of the printing substrate A step of extracting features on the image of the image, a step of obtaining a plan view image of the printed board after execution of screen printing, and a plan view image of the printed board after execution of screen printing. The process of extracting the features on the image of the printing agent on the printing plate where the printing agent is printed and the portion where the printing agent is not printed is compared with the features on the image of the planar image of the printed board before and after printing, and the printing result And a step of performing the determination. In a screen printing apparatus that prints a printing agent on a printing plate through a plurality of through holes formed in the screen by moving the squeegee on the screen, the printing means 18 for performing screen printing and the cause of printing failure are eliminated. In addition to the defective printing cause removing unit 19, an inspection execution position storage unit 11 that stores a position for performing an inspection on a printing result of screen printing, and a first image that obtains an image in a plan view of a portion including a through hole on the screen. A plane-view image acquisition unit 12, a print-position / print-area extraction unit 13 for obtaining a printing agent printing position and area from the plane-view image acquired by the first plane-view image acquisition unit 12, and a screen Second planar image acquisition means 14 for acquiring an image of the printed board corresponding to the acquisition position of the planar image in planar view; and second planar image acquisition means 1 Obtained by the printing position / printing area extracting unit 13 from the planar image acquired by the feature extraction unit 15 for extracting the features on the image of the printing portion and the non-printing portion of the printing agent, and obtained by the feature extracting unit 15 A screen printing apparatus, comprising: a printing result determination unit 16 configured to determine a printing result by comparing characteristics on a planar view image of a printing plate before and after printing.

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