JP4322340B2 - Screen printing machine - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a screen printer for printing a solder paste on a substrate.
[0002]
[Prior art]
This type of screen printing machine sandwiches a substrate supporting means, a screen that is relatively in contact with and away from the printed surface of the substrate supported by the substrate supporting means, and a screen that is close to the printed surface of the substrate. And a squeegee arranged so as to face the printing surface. The squeegee slides on the screen to print the solder paste on the printing surface of the substrate. The printed board is inspected for quality (area, position, etc.) of the printed solder paste by visual inspection by an inspector or by an inspection mechanism provided in a screen printer.
[0003]
[Problems to be solved by the invention]
In the case of the above-described prior art, all the substrates determined to be defective in printing have been subjected to the screen printing machine again after the solder paste has been wiped off, which has been problematic in that it takes time and production efficiency is not good. .
[0004]
In addition, when the printing standby time is lengthened, the viscosity of the solder paste increases, and it becomes difficult to sufficiently fill the opening of the screen with the solder paste at the start of printing. However, there is a problem that the production efficiency is lowered with the increase.
[0005]
The present invention has been made in view of the above-described problems, and an object of the present invention is to provide a screen printer configured to reduce the labor involved in processing a defective substrate and improve the manufacturing efficiency. .
[0006]
[Means for Solving the Problems]
In order to achieve the above-described object, the invention of claim 1 is directed to a substrate support means, a screen that comes in contact with and separates from a print surface of a substrate supported by the substrate support means, and the print surface. A squeegee disposed so as to face the printed surface across the screen close to the screen, and the squeegee slides on the screen to print a solder paste on the printed surface. In the screen printing machine, the previous printing time storage means for storing the previous printing time, the standby time calculating means for calculating the difference between the time stored by the previous printing time storage means and the current time, and at the start of printing A determination unit that compares the time calculated by the waiting time calculation unit with a preset upper limit value and determines whether or not the time is larger than the upper limit value, and the determination unit And control means for performing a printing process of a plurality of times more the waiting time when the calculation means time calculated is is determined to be larger than the upper limit by driving a plurality of times the squeegee only substrate at the beginning of a predetermined number Is provided .
[0008]
According to a second aspect of the invention, the screen printing machine of the first aspect includes a pair of reciprocating squeegees, and when the squeegees move in one direction, one squeegee slides on the screen. When moving in the other direction, the other squeegee slides on the screen, so that the printing process is performed twice with one reciprocation of the pair of squeegees. The control means reciprocally moves the pair of squeegees only for the first predetermined number of substrates when the determination means determines that the time calculated by the standby time calculation means is greater than the upper limit value. This is characterized in that the printing process is performed once.
[0009]
In the invention of claim 3 , the screen printing machine of claim 1 or claim 2 moves in the direction of the X axis extending in the horizontal direction and the first moving mechanism for moving in the direction of the X axis extending in the horizontal direction. A substrate supporting table having a second moving mechanism for rotating and a rotating mechanism for rotating in a horizontal plane, and a substrate disposed on the substrate supporting table and irradiating light on the substrate supporting table. An illumination device, a screen support unit disposed above the substrate support table and having a moving mechanism for moving in the direction of the Y axis extending in the horizontal direction, and disposed between the substrate support table and the screen support unit. The first image pickup means having a camera for picking up an image of the substrate, which is movable in the X-axis and Y-axis directions, is disposed above the screen support means and moves in the X-axis and Y-axis directions. And a second imaging unit having a camera for imaging the screen supported by the screen supporting unit, and before performing screen printing on the substrate, the first imaging unit images the substrate to position the substrate. Recognizing, causing the second imaging means to image the screen, recognizing the position of the screen, and calculating the amount of positional deviation between the substrate and the screen from the obtained substrate and the position information of the screen. A first movement mechanism and a rotation mechanism of the substrate support table, and a control means for driving the movement mechanism of the screen support means to correct a positional deviation between the substrate and the screen. Is.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, specific embodiments of the present invention will be described with reference to the drawings.
1 is a front view of a main part of a screen printer according to an embodiment of the present invention, FIG. 2 is a right side view of the screen printer, FIG. 3 is a right side view of the main part of the screen printer, and FIG. FIG. 5 is a flowchart showing an outline of a printing processing procedure of the screen printing machine.
[0011]
As shown in FIG. 1, the screen printing machine includes a substrate support table 2 installed on a base 1, screen support means 3 disposed above the substrate support table 2, substrate support table 2, and screen. The first image pickup means 4 that is arranged between the support means 3 and picks up an image of the printing surface of the substrate P supported by the substrate support table 2 and the screen support means 3 are arranged above and supported by the screen support means 3. A second image pickup means 5 for picking up an image of the screen S, a pair of print heads 6A and 6B (see FIG. 3) disposed above the screen S, and a supply conveyor 7 for supplying the substrate P onto the substrate support table 2. The discharge conveyor 8 for discharging the substrate P from the substrate support table 2, the display 9 (see FIG. 2) for displaying the images captured by the first and second imaging means 4, 5, and the substrate support And a control means 10 (see FIG. 4) for controlling the table 2, screen support means 3, first and second imaging means 4, 5, print heads 6A, 6B, supply conveyor 7, discharge conveyor 8, display 9 and the like. ing.
[0012]
The substrate support table 2 is provided on the first moving mechanism 11 for moving in the direction of the X axis extending in the horizontal direction (see FIG. 1), and rotating for rotating in the horizontal plane. A mechanism 12, a second moving mechanism 13 provided on the rotating mechanism 12 for moving in the direction of the Z-axis extending in the vertical direction, a substrate support plate 14 provided on the second moving mechanism 13, A transport mechanism (not shown) is provided on the upper surface of the substrate support plate 14 and transports the substrate P in the X-axis direction. Two position recognition marks (not shown) are attached to the printed surface of the substrate P.
[0013]
The screen support means 3 includes a screen support frame 15 that supports the peripheral edge of the lower surface of the screen S, cylinders 16 and 16 that are disposed above the screen support frame 15 and press the screen S against the screen support frame 15, and a horizontal direction. And a moving mechanism 17 for moving in the direction of the Y axis (see FIG. 2). Two recognition marks (not shown) are attached to the upper surface of the screen S.
[0014]
The first imaging means 4 includes a camera 18, a moving mechanism 19 that moves the camera 18 in the X-axis and Y-axis directions, and an illumination device 20 that irradiates light onto the substrate P on the substrate support table 2 (see FIG. 4). And. The second imaging means 5 includes a camera 21, a moving mechanism 22 that moves the camera 21 in the X-axis direction, and an illumination device (not shown) that irradiates light onto the substrate P on the substrate support table 2. The camera 21 is moved in the Y-axis direction by a moving mechanism 24 (described later) of the print heads 6A and 6B.
[0015]
As shown in FIG. 3, the print heads 6A and 6B are arranged at intervals in the Y-axis direction, and squeegees 23A and 23B are respectively attached to the lower end portions thereof, and simultaneously the Y-axis is moved by the moving mechanism 24 (see FIG. 1). And the vertical movement mechanisms 25A and 25B individually move in the Z-axis direction. When the print heads 6A and 6B move to the left in FIG. 3, the right print head 6A descends and the squeegee 23A slides on the screen S, and when the print head 6A moves to the right in FIG. The print head 6B descends and the squeegee 23B slides on the screen S. Therefore, two printing processes are performed by one reciprocating movement of the print heads 6A and 6B.
[0016]
The supply conveyor 7 is connected to the substrate support table 2 by moving the substrate support table 2 to the left in FIG. 1, and when the supply conveyor 7 is driven in this state, the transport mechanism of the substrate support table 2 is interlocked. ing.
[0017]
The discharge conveyor 8 is connected to the substrate support table 2 by moving the substrate support table 2 in the right direction in FIG. 1. When the discharge conveyor 8 is driven in this state, the transport mechanism of the substrate support table 2 is interlocked. ing.
[0018]
As shown in FIG. 4, the control system of the screen printing machine 1 includes a first imaging unit 4, an image processing unit 26, a discrimination unit 27, a control unit 10, a previous printing time storage unit 28, a standby time calculation unit 29, and the like. The image processing unit 26, the determination unit 27, the control unit 10, the previous printing time storage unit 28, and the standby time calculation unit 29 are constituted by a microcomputer.
[0019]
The image processing unit 26 captures the printed surface of the substrate P with the camera 18 while irradiating the printed surface of the substrate P after printing with the illumination device 20 of the first imaging unit 4. Is subjected to edge extraction processing. Since the solder paste is formed of a group of solder balls having a diameter of several tens of μm, an image in which a large number of edges are extracted in the area of the solder paste (hereinafter referred to as an edge information image) is obtained. Since the solder level group and the board do not include a group of solder balls, these regions do not have a large number of edges extracted as described above.
[0020]
The image processing means 26 performs an expansion process and a compression process on the edge information image to fill the solder paste area, and calculates the area of the solder paste area by counting the pixels of the filled solder paste area. The position is also calculated. The discriminating means 27 discriminates whether or not the area of the solder paste area calculated by the image processing means 26 is smaller than a preset lower limit, and the position of the solder paste area calculated by the image processing means 26. Is determined to be within a preset allowable range.
[0021]
The previous printing time storage unit 28 stores the time of printing performed last time, and the standby time calculation time 29 is the difference between the time stored in the previous printing time storage unit 28 at the start of printing and the current time (hereinafter, referred to as “the printing time”). (Referred to as standby time). Then, the determination unit 27 also determines whether or not the standby time calculated by the standby time calculation time 29 is greater than a preset upper limit value.
[0022]
In FIG. 3, 30 is a housing, and 31 and 31 are gull-wing doors for opening and closing openings (not shown) provided on the front surface and the back surface of the housing 30. In addition, an operation input unit 32 for inputting various instructions is provided at the upper part of the front surface of the housing 30.
[0023]
Next, the operation of the screen printing machine 1 configured as described above will be described.
First, prior to printing, the relative displacement between the substrate P and the screen S is corrected.
[0024]
When the substrate P is placed on the supply conveyor 7, a photo sensor (not shown) detects this, and a substrate stopper (not shown) descends to hold the substrate P so that it does not move during transport. Next, the substrate support table 2 moves to the left in FIG. 1 and is connected to the supply conveyor 7. Then, the supply conveyor 7 is driven, the substrate P is transferred onto the substrate support table 2 in conjunction with the transfer mechanism of the substrate support table 2, and the supply conveyor 7 stops when it reaches a predetermined position. Then, after the substrate P is positioned on the substrate support table 2 by a positioning mechanism (not shown), the substrate support table 2 moves rightward and returns to the initial position (hereinafter referred to as the origin position).
[0025]
Next, the camera 18 of the first image pickup means 4 moves in the X-axis direction and the Y-axis direction to pick up two recognition marks on the printing surface of the substrate P, and the image is displayed on the recognition board of the control means 10. Remembered. Then, the control means 10 recognizes the position of each position recognition mark from the image stored on the recognition board, and stores this position information in the memory. Further, the camera 21 of the second image pickup means 5 moves in the X-axis direction and the Y-axis direction to pick up two recognition marks on the screen S, and the images are stored in the recognition board of the control means 10. Then, the control means 10 recognizes the position of each position recognition mark from the image stored in the recognition board, and compares the position information with the position information of the position recognition mark of the substrate P stored in the memory. The relative displacement amount between the substrate P and the screen S is calculated.
[0026]
The control means 10 drives the moving mechanism 11 of the substrate support table 2, the rotating mechanism 12, and the moving mechanism 17 of the screen support means 3 on the basis of the positional deviation amount, and corrects the relative positional deviation between the substrate P and the screen S. To do.
[0027]
Next, a printing process procedure of the screen printer 1 will be described.
First, an outline of the print processing procedure will be described with reference to FIG.
The previous printing time storage means 28 stores the time when the previous printing was performed (hereinafter referred to as the previous printing time), and the waiting time calculation means 29 calculates the waiting time at the start of printing (step # 10). ), It is determined whether or not the determination means 27 is larger than the upper limit value stored in the memory (step # 20). If NO, the control means 10 performs normal printing (step # 30). If YES, the control means 10 executes reciprocal printing only for the first printing (step # 40).
[0028]
When the printing is completed, the previous printing time stored in the previous printing time storage unit 28 is updated (step # 50), and then the first image pickup unit 4, the image processing unit 26, and the determination unit 27 print on the substrate P. The quality of the solder paste is determined. That is, whether or not the area of the solder paste is smaller than the lower limit value stored in the determination unit 27 (defective if small), and whether or not the position of the solder paste is within the allowable range stored in the determination unit 27. Is discriminated (step # 60).
[0029]
Then, the control means 10 reads this determination result (step # 70), and if it is OK, reads whether or not a print processing stop command has been input from the operation input unit 32 (step # 80), and YES. In this case, the printing process is terminated. In the case of NO, the process returns to step # 10 to perform the printing process on the next substrate P. If the determination result of the solder paste is NG in step # 70, the control means 10 reads whether or not it is a defective area (step # 90). Reprinting is executed (step # 100), and then the process returns to step # 50. If NO, a warning is issued (step # 110), and the printing operation is stopped.
[0030]
Next, the printing process procedure of the screen printer 1 will be described in more detail.
Here, a case where the standby time is longer than the upper limit value in step # 10 will be described.
First, the camera 18 of the first imaging means 4 and the camera 21 of the second imaging means 5 are retracted from above the substrate P and the screen S, respectively, the substrate support table 2 is raised, and stops when the substrate P reaches the printing position. . Then, the print head 6A is lowered, the solder paste is supplied onto the screen S by a solder paste supply means (not shown), and the squeegee 23A slides along the upper surface of the screen S to print the solder paste on the substrate P. To do. Next, the print head 6B is lowered, and the solder paste is supplied onto the screen S by a solder paste supply means (not shown), and the squeegee 23B slides along the upper surface of the screen S to again apply the solder paste onto the substrate P. Print.
[0031]
When printing is completed, the time stored in the previous printing time storage means 28 is updated, and the substrate support table 2 is lowered to the origin position. Then, the camera 18 of the first imaging unit 4 moves above the substrate P, the illumination device 20 irradiates the substrate P with light, and the camera 18 images the printing surface of the substrate P. The obtained planar image of the substrate P is sent to the image processing means 26 and subjected to edge extraction processing. As described above, since the solder paste includes a group of solder balls having a diameter of several tens of μm, an edge information image in which a large number of edges are extracted can be obtained.
[0032]
Next, the image processing unit 26 performs a predetermined number of expansion processing and compression processing on the edge information image, fills the solder paste area, and binarizes the image based on a predetermined threshold value. Process. Then, the image processing unit 26 calculates the area of the solder paste region by counting the number of pixels in the solder paste region, and further calculates the position of the solder paste region. The discriminating means 27 compares these numerical values with the numerical values stored in the memory, and discriminates the quality of the solder paste area and position.
[0033]
If the determination result is OK, the substrate support table 2 moves to the right, the positioning mechanism that fixes the substrate P is released, the discharge conveyor 8 is driven, and the transport mechanism of the substrate support table 2 is added thereto. In conjunction with each other, the substrate P is conveyed toward the discharge conveyor 8, and when the substrate P reaches a predetermined position on the discharge conveyor 8, the discharge conveyor 8 stops. Then, the substrate support table 2 returns to the origin position and the discharge conveyor 8 is driven to transport the substrate P to the next process. When no print processing stop command is input from the operation input unit 32, the substrate support table 2 moves to the left, and the next substrate P is supplied onto the substrate support table 2, and the same procedure as described above is performed. Printing is performed on the substrate P. If a print processing stop command is input, the operation ends.
[0034]
In addition, when the determination result of the quality of the solder paste by the determination unit 27 is NO, it is read whether or not it is the area of the solder paste. In this case, the camera 18 of the first imaging unit 4 is read. Withdrawing from above the substrate P and the screen S, the substrate support table 2 is raised, and the squeegee 6A slides on the screen S to perform reprinting on the substrate P. And the previous printing time memorize | stored in the last printing time memory | storage means 28 is updated, the quality determination of a solder paste is performed again, and when it is a non-defective product, after the board | substrate P is discharged | emitted as above-mentioned, The presence / absence of a print process stop command is read, and the print process is performed on the next substrate P, or the print operation ends.
[0035]
If the determination result by the determination means 27 is negative and it is a misalignment of the solder paste, an alarm is issued and the printing operation is stopped. Then, the control unit 10 drives the motors of the first moving mechanism 11, the rotating mechanism 12 of the substrate support table 2, and the moving mechanism 17 of the screen support unit 3 to correct the positional deviation between the substrate P and the screen S.
[0036]
In addition, this invention is not limited to embodiment mentioned above, A various modification is considered.
[0037]
For example, in the above-described embodiment, the substrate support table 2 moves up and down so that the substrate P contacts and separates from the screen S. However, the screen S moves up and down and the substrate P contacts and separates from the screen S. It may be.
[0038]
Further, in the above-described embodiment, when the standby time is larger than the preset upper limit value, the printing process is performed twice for the first substrate, and for the subsequent substrates, the standby time must be larger than the upper limit value. For example, the printing process is performed once, but the printing process may be forcibly performed twice for the first few substrates. In addition, when the standby time is larger than the upper limit value, the number of times of forcibly performing the printing process for the first or first few substrates is not limited to two, but may be three or more.
[0039]
In addition to the above, various modifications can be made without departing from the scope of the present invention.
[0040]
【The invention's effect】
As described above, according to the first aspect of the present invention, since a plurality of times of printing process is performed only for the substrate of the beginning of the predetermined number when the waiting time at the start of printing is larger than the preset upper limit value The number of defective substrates is reduced. Therefore, the labor involved in processing the defective substrate is reduced and the manufacturing efficiency is improved.
[Brief description of the drawings]
FIG. 1 is a front view of a main part of a screen printing machine 1 according to an embodiment of the present invention.
FIG. 2 is a right side view of the screen printing machine 1. FIG.
FIG. 3 is a right side view of a main part of the screen printing machine 1;
FIG. 4 is a block diagram showing a schematic configuration of a control system mounted on the screen printing machine 1;
FIG. 5 is a flowchart showing an outline of a printing processing procedure of the screen printing machine 1;
[Explanation of symbols]
1 Screen printer 2 Substrate support table (substrate support means)
3 Screen support means 4 First imaging means (substrate imaging means)
5 Second imaging means 10 Control means 11 First moving mechanism 12 Rotating mechanism 13 Second moving mechanism 17 Moving mechanism 18 of screen support means 3 Camera 20 of first imaging means 4 Illumination device 21 Camera 23A of second imaging means 5 23B Squeegee 26 Image processing means 27 Discriminating means 28 Previous printing time storage means 29 Standby time calculation time P Substrate S Screen

Claims (3)

A substrate support means, a screen that is relatively close to and away from the printing surface of the substrate supported by the substrate supporting means, and the printing surface facing the printing surface across the screen that is close to the printing surface. A screen printing machine that is configured to print a solder paste on the printing surface by sliding the squeegee on the screen.
The previous printing time storage means for storing the previous printing time, the standby time calculation means for calculating the difference between the time stored in the previous printing time storage means and the current time, and the standby time calculation means at the start of printing. Comparing the calculated time with a preset upper limit value and determining whether or not the calculated time is larger than the upper limit value; and the time calculated by the waiting time calculating means by the determining means is greater than the upper limit value. A screen printing machine comprising: a control unit that drives the squeegee a plurality of times only for the first predetermined number of substrates when it is determined to be large, and performs a plurality of printing processes . A pair of reciprocating squeegees are provided. When these squeegees move in one direction, one squeegee slides on the screen, and when moving in the other direction, the other squeegee moves on the screen. , And the printing unit performs the printing process twice by one reciprocating movement of the pair of squeegees. The control unit calculates the time calculated by the waiting time calculation unit by the determination unit. 2. The screen according to claim 1, wherein when it is determined that is larger than the upper limit value, the pair of squeegees are reciprocated only for the first predetermined number of substrates to perform the printing process twice. Printer. A substrate support table having a first moving mechanism for moving in the X-axis direction extending in the horizontal direction, a second moving mechanism for moving in the Z-axis direction extending in the vertical direction, and a rotating mechanism for rotating in a horizontal plane When,
An illumination device that is disposed above the substrate support table and irradiates light onto the substrate placed on the substrate support table;
A screen support means disposed above the substrate support table and having a moving mechanism for moving in the direction of the Y-axis extending in the horizontal direction;
A first imaging means disposed between the substrate support table and the screen support means, and having a camera which is movable in the X-axis and Y-axis directions and images the substrate;
A second image pickup means disposed above the screen support means, movable in the X-axis and Y-axis directions, and having a camera for picking up an image of the screen supported by the screen support means;
Before performing screen printing on the substrate, the first imaging unit images the substrate to recognize the position of the substrate, the second imaging unit images the screen to perform screen position recognition, A positional shift amount between the substrate and the screen is calculated from the obtained positional information of the substrate and the screen, and a first moving mechanism and a rotating mechanism of the substrate supporting table and a moving mechanism of the screen supporting means are driven. The screen printing machine according to claim 1, further comprising: a control unit that corrects misalignment between the substrate and the screen.

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