JP3758463B2 - Screen printing inspection method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a screen printing inspection method in a screen printing apparatus that prints paste such as cream solder or conductive paste on a substrate.
[0002]
[Prior art]
In an electronic component mounting process, screen printing is used as a method for printing paste such as cream solder on a substrate. In this method, a screen mask provided with a pattern hole according to a part to be printed is brought into contact with the substrate, cream solder is supplied onto the screen mask, and a squeegee is slid to pass through the pattern hole on the substrate. The cream solder is printed on.
[0003]
After the printing process, a printing inspection for inspecting the printing state of the cream solder is performed. A screen printing apparatus having a print inspection function is known so that the print inspection can be performed in the same apparatus. Such a screen printing apparatus with an inspection function has conventionally picked up an image of a printed board by a camera provided for substrate recognition, processed the imaged result, and whether or not the cream solder is correctly printed on the print site. The print inspection is performed by determining whether or not.
[0004]
[Problems to be solved by the invention]
However, the conventional screen printing apparatus has the following problems. First, since a method for determining based on two-dimensional image data captured by a camera has been adopted in the print inspection, satisfactory inspection results have been obtained for items that can be determined only by two-dimensional data, such as the print position and the planar shape of the printing portion. Although it can be obtained, it has been difficult to accurately inspect items that are accompanied by three-dimensional data such as the print height in the quality determination such as the print amount. In the conventional print inspection, since the camera recognizes only the printed circuit board, it is possible to detect the quality of the print result itself, but to identify the cause of the failure that caused the failure. Necessary data cannot always be obtained sufficiently, and there is a problem that it is difficult to appropriately cope with printing defects.
[0005]
SUMMARY OF THE INVENTION An object of the present invention is to provide a screen printing inspection method that can perform printing inspection with high accuracy and that can acquire data for identifying the cause of failure and prevent printing failure.
[0006]
[Means for Solving the Problems]
The screen printing inspection method according to claim 1, wherein a screen mask provided with a pattern hole is brought into contact with the substrate, and a squeegee head is slid on the screen mask, whereby the paste is applied to the substrate through the pattern hole. After separating the substrate from the screen mask and separating the plate, the shape of the printed portion printed on the electrode of the substrate and the internal state of the pattern hole of the mask plate are detected by the three-dimensional measuring means, By comparing the shape detection result of the printed portion and the detection result of the internal state of the pattern hole, it is a screen printing inspection method that identifies the cause of the occurrence of printing failure, in which “notch” is detected in the printed portion, When the remaining amount of paste corresponding to the shape of the “chip” is detected in the pattern hole, the “chip” is generated in the plate separation process. In the case where “a chip” is detected in the printed portion and no residual paste corresponding to the shape of the “chip” is detected in the pattern hole, the “chip” is a paste in the pattern hole. Identified as a result of poor filling .
[0012]
In the present invention , after printing is finished and the substrate is separated from the screen printing , both the shape of the printed portion of the electrode portion of the substrate and the internal state of the screen mask are detected by the three-dimensional measuring means, and the detection result is obtained. By comparison, it is possible to easily identify the cause when printing failure occurs.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
Next, embodiments of the present invention will be described with reference to the drawings. 1 is a front view of a screen printing apparatus according to an embodiment of the present invention, FIG. 2 is a side view of the screen printing apparatus according to an embodiment of the present invention, and FIG. 3 is a screen printing apparatus according to an embodiment of the present invention. FIG. 4 is a perspective view of the laser measuring device of the screen printing apparatus according to the embodiment of the present invention. FIG. 5 is a block diagram showing the configuration of the control system of the screen printing apparatus according to the embodiment of the present invention. FIG. 6 is a partial perspective view of a substrate and a screen mask of a screen printing apparatus according to an embodiment of the present invention, and FIG. 7 is an explanatory diagram of repair printing by the screen printing apparatus according to an embodiment of the present invention.
[0015]
First, the structure of the screen printing apparatus will be described with reference to FIG. 1, FIG. 2, and FIG. 1 and 2, a substrate positioning unit 1 serving as a substrate positioning means stacks a θ-axis table 4 on a moving table composed of an X-axis table 2 and a Y-axis table 3, and further a Z-axis table 5 thereon. A substrate holding part 7 is provided on the Z-axis table 5 to hold the substrate 6 sandwiched by the clamper 8 from below. The substrate 6 to be printed is carried into the substrate positioning unit 1 by the carry-in conveyor 14 shown in FIGS. By driving the substrate positioning unit 1, the position of the substrate 6 can be adjusted. The printed circuit board 6 is unloaded by the unloading conveyor 15.
[0016]
A screen mask 10 is disposed above the substrate positioning unit 1, and the screen mask 10 is configured by attaching a mask plate 12 to a holder 11. The substrate 6 is aligned with the mask plate 12 by the substrate positioning unit 1 and abuts from below. On the screen mask 10, a squeegee head 13 is disposed so as to be able to reciprocate in the horizontal direction. In a state where the substrate 6 is in contact with the lower surface of the mask plate 12, the cream solder 9 as a paste is supplied onto the mask plate 12, and the squeegee 13 a of the squeegee head 13 is brought into contact with the surface of the mask plate 12 and is slid. Thus, the cream solder 9 is printed on the electrode 6a (see FIG. 3) formed on the surface of the substrate 6 through the pattern hole 12a (see FIG. 3) provided in the mask plate 12.
[0017]
Above the screen mask 10, a laser measuring device 20 as a three-dimensional measuring means is provided. As shown in FIG. 3, the laser measuring device 20 is horizontally moved in the XY directions by the X-axis table 21 and the Y-axis table 22, and can be moved up and down by the lifting means 23 (FIGS. 1 and 2). By driving the elevating means 23, the laser measuring device 20 is lowered to the measurement height position. The X-axis table 21, the Y-axis table 22, and the lifting / lowering means 23 are moving means for moving the laser measuring device 20.
[0018]
The laser measuring device 20 has a function of measuring the displacement in the vertical direction by irradiating a laser beam and a scanning mechanism for scanning the laser irradiation position in the XY directions. As shown in FIG. By scanning within R, the position in the vertical direction of the surface of the measurement object within the measurement range R can be continuously detected, and the three-dimensional shape of the measurement object can be detected.
[0019]
By moving the laser measuring device 20 with respect to the substrate 6 and the mask plate 12 by the moving means, it is possible to perform a three-dimensional shape measurement for an arbitrary range of the substrate 6 and the mask plate 12. Then, by processing the obtained detection data, it is possible to detect the arrangement pattern of the electrodes 6a, which is a characteristic part of the substrate 6, and the arrangement pattern of the pattern holes 12a, which is a characteristic part of the screen mask 10. The shape of the cream solder 9 printed on the substrate 6 can be detected three-dimensionally by performing three-dimensional measurement using the substrate 6 as a measurement target.
[0020]
A dispenser 24 (paste discharge means) is mounted on the X-axis table 21 and the Y-axis table 22 that move the laser measuring device 20. The dispenser 24 is provided with a discharge nozzle 25 for discharging the cream solder 9 and can be moved up and down by a vertical mechanism 26. The dispenser 24 is moved by the X-axis table 21 and the Y-axis table 22, and the discharge nozzle 25 is lowered with respect to the part to be repaired to discharge the cream solder 9 in a state where the lower end portion is aligned (FIG. 6A )), It is possible to supply the cream solder 9 for repair to the defective printing portion. That is, the dispenser 24 constitutes repair means for repairing a defective printing portion.
[0021]
Next, the configuration of the control system of the screen printing apparatus will be described with reference to FIG. In FIG. 5, a CPU 30 is an overall control unit, and performs overall control of each unit described below. The program storage unit 31 stores a screen printing operation program, a processing program for detecting the shape of the substrate 6 and the mask plate 12 from the detection signal of the laser measuring device 20, and various determination processing programs described below. The data storage unit 32 stores various data such as screen printing condition data and reference value data for determination processing.
[0022]
The mechanism control unit 33 controls the operation of each mechanism unit such as the substrate positioning unit 1, the carry-in conveyor 14, the carry-out conveyor 15, the X-axis table 21, and the Y-axis table 22. The shape detection unit 34 processes a detection signal obtained by scanning the laser measuring device 20, and thereby an electrode arrangement pattern indicating a planar arrangement of the electrodes 6 a provided on the substrate 6 and a pattern provided on the mask plate 12. An opening pattern indicating the arrangement of the holes 12a and the shape of the cream solder 9 on the printed circuit board 6 are detected.
[0023]
The substrate / mask determination unit 35 is supplied to the screen printing apparatus by comparing the electrode arrangement pattern and the opening pattern thus created with the reference pattern on the design data stored in the data storage unit 32. The quality of the substrate 6 and the mask plate 12 is determined. That is, the substrate / mask determination unit 35 is a supply material determination unit.
[0024]
The print determination unit 36 determines the quality of the printed state by comparing the shape data of the cream solder 9 obtained by measuring the substrate 6 after screen printing with the laser measuring device 20 with reference data stored in advance. . The repair determination unit 37 determines whether or not repair by the printing measure is possible and selects a repair method for the board determined to be defective by the print determination unit.
[0025]
That is, by repairing the shape data of the cream solder 9 determined by the three-dimensional shape measurement with the data stored in the repair application example library of the data storage unit 32, the repair is performed by the repair function provided in the printing apparatus. It is first determined whether or not it is possible. Then, it is selected which of the following two repair methods is applied to the board determined to be repairable.
[0026]
First, when the repair target part is partial when viewed from the entire substrate 6, repair application by the dispenser 24 is performed. Further, when the number of parts to be repaired is large, or the degree of printing failure is so great that additional application by the dispenser 24 requires time for repair, reprinting, that is, the substrate 6 is again applied to the mask plate 12. A repair method is selected in which printing is performed with contact. In this case, the printing function itself of the screen printing apparatus is a repair means for repairing a defective print portion. Thus, efficient repair printing can be performed by selecting an appropriate repair method according to the state of printing failure.
[0027]
In the above configuration, the substrate / mask determination unit 35 and the print determination unit 36 serve as inspection means for inspecting the substrate 6 and / or the screen mask 10 from the measurement result of the laser measuring device 20, and the repair determination unit 37 has a printing failure. It constitutes a repair means for repairing the part.
[0028]
The screen printing apparatus is configured as described above. Hereinafter, a screen printing method and repair printing performed on a substrate determined to be defective after screen printing will be described. First, the product type is switched to a new product type to be printed, and when the screen mask 10 is mounted corresponding to the product type, a screen mask inspection is performed. This inspection is performed by three-dimensionally measuring the upper surface of the screen mask 10 while moving the laser measuring device 20 on the screen mask 10 by the X-axis table 21 and the Y-axis table 22 with the screen mask 10 mounted. Is called. By this inspection, the quality of the mounted screen mask 10 is determined.
[0029]
Next, the substrate 6 is inspected. When the substrate 6 to be printed is loaded onto the substrate positioning unit 1 from the carry-in conveyor 14, the substrate positioning unit 1 is moved in the Y direction from below the screen mask 10 and moved to the substrate measurement position (in FIG. 2). (See the substrate positioning portion 1 and the substrate 6 indicated by broken lines). Then, three-dimensional measurement of the upper surface of the substrate 6 is similarly performed by the laser measuring device 20. Thereby, the quality of the board | substrate 6 is determined. This substrate inspection may be performed only for new varieties, or may be performed by sampling.
[0030]
If it is confirmed that both the screen mask 10 and the substrate 6 are normal, screen printing is performed. First, the cream solder 9 is supplied onto the screen mask 10, and after performing preliminary squeezing by reciprocating the squeegee 13 a to knead the cream solder 9, the Z table 5 of the substrate positioning unit 1 is lifted to bring the substrate 6 into the mask plate. 12 is brought into contact with the lower surface. Next, the squeegee head 13 is moved to print the cream solder 9 on the electrode 6a of the substrate 6 through the pattern hole 12a. Thereafter, the Z-axis table 5 is moved down to separate the plate 6 from the screen mask 10, whereby the cream solder 9 is printed on the electrodes 6 a of the substrate 6.
[0031]
After this separation , the printing state is inspected. This inspection is performed by moving the substrate positioning unit 1 again from the lower side of the screen mask 10 to the substrate measurement position and three-dimensionally measuring the upper surface of the printed substrate 6 by the laser measurement device 20. If it is determined by this inspection that the printing state is good, the board positioning unit 1 returns to the printing position on the lower surface of the screen mask, and passes the printed board 6 to the carry-out conveyor 15 to perform the cream solder printing operation. To complete.
[0032]
Further, for the substrate 6 determined to be defective by the inspection, it is determined whether or not the repair by the screen printing apparatus is possible. If it is determined that the repair is impossible, the substrate 6 is a defective product. After performing the notification, it is carried out in the same manner as the non-defective substrate, and necessary repairs and the like are performed in a later process. Thereafter, the screen mask 10 is inspected. That is, the laser measuring device 20 inspects the state in the pattern hole 12a of the screen mask 10 after performing screen printing on the substrate 6 determined to be defective.
[0033]
FIG. 6 shows an example of information obtained in this inspection. As shown in FIG. 6, the shape of the printed part on the electrode 6a is determined three-dimensionally by three-dimensional measurement of the substrate 6 after printing. Shape defects such as a) are detected. Then, the state in the pattern hole 12a corresponding to the defective electrode 6a is detected by three-dimensional measurement on the mask plate 12.
[0034]
By comparing the shape detection result of the printed part on the electrode 6a with the detection result of the internal state of the pattern hole 12a, data specifying the cause of the failure can be obtained. That is, when the remaining amount of the cream solder 9 corresponding to the shape of the “chip” is detected in the pattern hole 12a corresponding to the electrode 6a in which “chip” is detected, the “chip” is indicated by the pattern hole 12a. It can be inferred that this occurred in the plate separation process after the cream solder was filled inside. On the other hand, when the residue of the cream solder 9 is not detected in the pattern hole 12a corresponding to the “chip”, the “chip” does not occur at the time of separating the plate, and the filling into the pattern hole 12a is poor. It can be estimated that this occurred.
[0035]
Next, processing when it is determined that repair is possible based on the three-dimensional measurement result after printing will be described with reference to FIG. First, if it is determined that the defective range is partial and can be repaired by local additional supply of cream solder 9, repair by the dispenser 24 is performed. That is, the X-axis table 21 and the Y-axis table 22 are driven to move the dispenser 24 to the repair target site, the discharge nozzle 25 is lowered with respect to the site, and the solder solder is moved from the discharge nozzle 25 to the necessary fine movement. 9 is discharged.
[0036]
After the discharge, the repair site is measured again by the laser measuring device 20, and the quality of the repair result is determined. As a result, if it is determined that the substrate is good, the repaired substrate 6 is carried out in the same manner as the non-defective substrate. In addition, when it is determined that the quality is still bad by the quality determination, the necessary re-repair is repeated.
[0037]
In addition, when there are a large number of parts to be repaired on the same substrate and it takes time to repair by additional supply, re-coating is performed. That is, the substrate positioning unit 1 is moved again to the printing position below the screen mask 10, and the Z-axis table 5 is again raised and brought into contact with the mask plate 12 as shown in FIG. Thereby, the already printed part on the substrate 6 is pushed again into the pattern hole 12a of the mask plate 12. In this state, the squeegee is moved to perform screen printing.
[0038]
As a result, the normal printing portion that has already been printed normally remains as it is, and the pattern hole corresponding to the portion where the printing failure has occurred, that is, the pattern hole 12a in which the cream solder 9 has not been filled has occurred. Cream solder 9 is newly filled in the insufficient portion. Then, by removing the plate to release the substrate 6 from the mask plate 12, the cream solder 9 is added to the defective print portion and the repair printing is finished.
[0039]
As described above, in the post-printing inspection for inspecting the printing state of the cream solder 9, not only the printed substrate but also the screen mask is measured, and this post-printing inspection is performed using the laser measuring device 20. The shape of the printed portion of the cream solder 9 on 6 can be obtained in detail three-dimensionally, and the remaining state of the cream solder 9 in the pattern hole 12a of the screen mask 10 can also be detected. Thereby, since it is possible to compare the internal state of the pattern hole corresponding to the printing portion with respect to the printing failure portion, data useful for identifying the cause of occurrence of the failure can be obtained.
[0040]
In addition, a repair determination unit that determines whether or not repair printing can be performed on a substrate that is determined to be defective in the post-printing inspection is performed, and the substrate that is determined to be repairable is repaired in the same apparatus, thereby performing a post-process. This eliminates the need for repair work and makes it easy to manage complicated defective products. Furthermore, by appropriately selecting the repair printing method according to the defective state, the repair work can be performed efficiently.
[0041]
In the above embodiment, an example of an open-type squeegee head provided with a plate-like squeegee 13a is shown as a type of squeegee head. However, the present invention is not limited to this. A hermetic squeegee head that slides on the mask plate while pressurizing and filling cream solder into the pattern holes may be used.
[0042]
【The invention's effect】
In the present invention , after printing is finished and the substrate is separated from the screen printing , both the shape of the printed portion of the electrode portion of the substrate and the internal state of the screen mask are detected by the three-dimensional measuring means, and the detection result is obtained. By comparison, it is possible to easily identify the cause when printing failure occurs.
[Brief description of the drawings]
FIG. 1 is a front view of a screen printing apparatus according to an embodiment of the present invention. FIG. 2 is a side view of a screen printing apparatus according to an embodiment of the present invention. FIG. 4 is a perspective view of a laser measuring device of a screen printing apparatus according to an embodiment of the present invention. FIG. 5 is a block diagram showing a configuration of a control system of the screen printing apparatus according to an embodiment of the present invention. 6 is a partial perspective view of a substrate and a screen mask of a screen printing apparatus according to an embodiment of the present invention. FIG. 7 is an explanatory diagram of repair printing by the screen printing apparatus according to an embodiment of the present invention.
DESCRIPTION OF SYMBOLS 1 Board | substrate positioning part 6 Board | substrate 10 Screen mask 12 Mask plate 12a Pattern hole 13 Squeegee head 20 Laser measuring device 24 Dispenser 34 Shape detection part 35 Substrate / mask judgment part 36 Print judgment part 37 Repair judgment part

Claims (1)

A screen mask provided with a pattern hole is brought into contact with the substrate, and a squeegee head is slid on the screen mask to print a paste on the substrate through the pattern hole, and then the substrate is separated from the screen mask. After separating the plate, the shape of the printed portion printed on the electrode of the substrate and the internal state of the pattern hole of the mask plate are detected by the three-dimensional measuring means, and the shape detection result of the printed portion and the internal state of the pattern hole are detected. A screen printing inspection method for identifying the cause of printing failure by comparing the detection results of
If “printing” is detected in the printed portion and the remaining amount of paste corresponding to the shape of this “chip” is detected in the pattern hole, this “chip” is generated in the plate separation process. Identify,
In addition, when “a chip” is detected in the printed portion and no residue of paste corresponding to the shape of this “chip” is detected in the pattern hole, the “chip” is caused by poor filling of the paste in the pattern hole. An inspection method for screen printing, characterized in that it is identified as occurring .

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