JP3613055B2 - Substrate alignment method in screen printing - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a substrate alignment method in screen printing in which a substrate is aligned with a mask plate in screen printing.
[0002]
[Prior art]
In an electronic component mounting process, screen printing is used as a method for printing cream solder, conductive paste, or the like on a substrate. In this method, a mask plate having a pattern hole opened according to a printing target portion is brought into contact with the substrate, a paste is supplied onto the mask plate, and a squeegee is slid on the substrate through the pattern hole. The paste is printed. In this screen printing, it is necessary to accurately align the substrate with respect to the mask plate. For this reason, a recognition mark for position detection is provided on the substrate. After the substrate is carried into the screen printing apparatus, the recognition mark is optically recognized to detect the positional deviation of the substrate. The substrate is positioned after correcting the shift amount. Conventionally, two recognition marks provided in the vicinity of the diagonal position of the substrate have been widely used as recognition marks. By recognizing these two points, the positional deviation amount in the orthogonal coordinate axis direction and the position in the rotation direction of the substrate are recognized. The deviation angle was calculated.
[0003]
[Problems to be solved by the invention]
By the way, since the substrate is made of a material that expands and contracts by heat or external force such as resin, deformation occurs in the manufacturing process. Moreover, the deformation is not necessarily uniform over the entire substrate, and may cause partial deformation. For this reason, the relative positional relationship between the two recognition marks provided at the diagonal positions of the substrate and the respective portions in the substrate is not necessarily constant.
[0004]
However, in many cases, the portion that is the target of the original alignment, that is, the portion that most wants to ensure the alignment accuracy is usually another portion that is separated from the diagonal position inside the substrate. However, conventionally, since the position of the entire substrate is corrected based on the position detection result of the two recognition marks provided at the diagonal positions, the portion requiring the highest position accuracy is not necessarily aligned correctly, and the required position accuracy There was a problem that was not secured.
[0005]
Therefore, an object of the present invention is to provide a method for aligning a substrate in screen printing, which can correctly align the substrate and improve the positional accuracy.
[0006]
[Means for Solving the Problems]
2. The method of aligning a substrate in screen printing according to claim 1, wherein a mask plate provided with a pattern hole is brought into contact with the substrate, a paste is supplied onto the mask plate, and a squeegee is slid to paste onto the substrate. The method of aligning a substrate in screen printing for printing a substrate, wherein the position deviation angle in the rotation direction of the substrate is detected by detecting the inclination of a straight line connecting feature points formed at two points remote from each other on the substrate. calculated, also recognized as a specific feature point two land portions in diagonal positions of the plurality of land portions in the predetermined region is a mounting region where an electronic component positional accuracy on the substrate is required to be implemented, this the Rukoto obtain the position of the midpoint of the two land portions obtain the position deviation amount of the orthogonal coordinate axis direction of the predetermined portion, the positional deviation angle and the positional deviation amount And to correct the position of the substrate Zui.
[0008]
According to the present invention obtains a positional shift angle of the rotation direction of the substrate by detecting the inclination of a straight line connecting the mutual feature points provided in two points remotely over a substrate, and the position accuracy is required on the substrate The two land portions at the diagonal positions in the plurality of land portions at the predetermined portion which is the mounting portion on which the electronic component is mounted are recognized as specific feature points , and the position of the midpoint between the two land portions is obtained. since so as to obtain an amount of positional shift orthogonal coordinate axis direction of the predetermined portion by, it is possible to improve the positional accuracy of the predetermined portion that require positional correction accuracy.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
Next, embodiments of the present invention will be described with reference to the drawings. 1 is a side view of a screen printing apparatus according to an embodiment of the present invention, FIG. 2 is a plan view of the screen printing apparatus, FIG. 3A is a plan view of the substrate, and FIG. FIG. 4 is a block diagram showing the configuration of the control system of the screen printing apparatus, FIG. 5 is a flow chart of substrate alignment in the screen printing, and FIGS. 6A and 6B are positions of the substrate. It is explanatory drawing of matching.
[0010]
First, the structure of the screen printing apparatus will be described with reference to FIGS. In FIG. 1, 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 arranges a Z-axis table 5 thereon. A substrate holding part 7 for holding the substrate 6 by the clamper 8 is provided on the Z-axis table 5. The board 6 to be printed is carried into the board positioning unit 1 by the carry-in conveyor 14 shown in FIG. 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.
[0011]
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. A squeegee unit 13 is disposed on the screen mask 10 so as to be reciprocally movable in the horizontal direction. In a state where the substrate 6 is in contact with the lower surface of the mask plate 12, cream solder as paste is supplied onto the mask plate 12, and the squeegee of the squeegee unit 13 is brought into contact with the surface of the mask plate 12 to slide. The cream solder is printed on the surface of the substrate 6 through the pattern holes 12a (see FIG. 2) provided in the mask plate 12.
[0012]
Above the screen mask 10, a camera 20 that is an imaging means is provided. As shown in FIG. 2, the camera 20 is horizontally moved in the XY directions by the X-axis table 21 and the Y-axis table 22. That is, the X-axis table 21 and the Y-axis table 22 are moving means. The camera 20 images each recognition mark as a feature point provided on the substrate 6 and a specific position correction site. Based on the image data obtained by imaging, the position of each recognition mark or specific position correction part is obtained.
[0013]
As shown in FIG. 3A, the substrate 6 is provided with recognition marks 6a and 6b as characteristic points at diagonal positions. The electrode portion 6c as a predetermined portion located on the inner side of the substrate 6 is a mounting portion on which an electronic component such as QFP that requires the highest positional accuracy is mounted on the substrate 6, and is prioritized at the time of position correction. Is a high specific position correction region. As shown in FIG. 3B, the electrode part 6c is composed of a plurality of electrodes, and in order to accurately correct the position of the entire electrode part 6c on average, the two land parts pa and pb at the diagonal positions are positioned. An image is taken as a specific feature point to be detected, and the midpoint 6p of the two detected land portions pa and pb is set as a representative point of the electrode part 6c.
[0014]
Next, the configuration of the control system of the screen printing apparatus will be described with reference to FIG. In FIG. 4, a CPU 30 is an overall control unit and performs overall control of each unit described below. The recognition mark position storage unit 31 stores the positions of the recognition marks 6a and 6b and the electrode part 6c on the substrate 6. The printing position data storage unit 32 calculates the positional deviation amount between the substrate 6 and the mask plate 12 obtained by recognizing the recognition marks 6a and 6b and the electrode portion 6c, that is, the substrate 6 is placed on the mask plate 12 during printing. The position correction amount to be corrected when the alignment is performed is stored. The recognition parameter storage unit 33 recognizes parameters necessary for specifying the recognition marks 6a and 6b and the electrode part 6c provided on the substrate 6 as feature parts by image recognition, that is, recognition marks, shapes and dimensions of land portions, and the like. The parameters and illumination data when the recognition marks 6a and 6b and the electrode part 6c are imaged by the camera 20 are stored.
[0015]
The image processing unit 34 detects the positions of the recognition marks 6 a and 6 b and the electrode part 6 c by performing image processing on image data obtained by imaging the substrate 6 with the camera 20. Here, the recognition parameters indicating the shapes and sizes of the recognition marks 6a and 6b and the electrode part 6c are read from the recognition parameter storage unit 33, and the reference patterns of the recognition marks 6a and 6b and the electrode 6c are automatically generated. By performing a position search process while pattern matching the obtained image data, the positions of the recognition marks 6a and 6b and the electrode part 6c are detected. The table driving unit 35 drives the substrate positioning X-axis table 2, Y-axis table 3, θ-axis table 4, Z-axis table 5, camera movement X-axis table 21, and Y-axis table 22.
[0016]
Next, a substrate alignment method will be described with reference to the drawings along the flow of FIG. This alignment is performed for the purpose of detecting the relative displacement amount between the carried substrate and the screen mask during screen printing. First, in FIG. 1, the substrate 6 is carried by the carry-in conveyor 14 and positioned by the substrate positioning unit 1.
[0017]
Next, the camera 20 images the recognition marks 6a and 6b and the electrode part 6c on the substrate 6 (ST1). Next, the positions on the optical coordinates of the two land portions pa and pb at the diagonal positions of the recognition marks 6a and 6b and the electrode part 6c are detected, and the detection result is stored in the recognition mark position storage unit 31 (ST2). .
[0018]
Next, as shown in FIG. 6A, the inclination of the straight line connecting the recognition marks 6a and 6b is detected from the position detection result of the recognition marks 6a and 6b, and the normal angle (the angle formed by the straight line connecting the points A and B) is detected. ) Is determined (ST3). Next, the position of the midpoint 6p of the land portions pa and pb is obtained from the position detection result of the land portions pa and pb, and set as the representative point of the electrode part 6c (ST4). Then, the positional deviation amounts Δx and Δy of the representative point 6p in the orthogonal coordinate axis direction with respect to the normal position (point P) are obtained (ST5), and the obtained Δx, Δ and Δθ are stored as position correction amounts (ST6).
[0019]
When the table driving unit 35 is driven to align the substrate 6, the respective axes are driven based on these position correction amounts (ST7). Thereby, as shown in FIG. 6B, the representative point 6p of the electrode part 6c which is the specific position correction part is superimposed on the normal position point P. Therefore, highly accurate alignment is realized in the vicinity of the electrode part 6c where the positional accuracy is most required. After the substrate 6 is aligned with the screen mask 10 in this way, screen printing is performed (ST8).
[0020]
By using the above-described alignment method, it is possible to accurately correct the mounting position of an electronic component such as QFP that requires mounting position accuracy, and to accurately align the deviation angle in the rotation direction of the entire board.
[0021]
【The invention's effect】
According to the present invention obtains a positional shift angle of the rotation direction of the substrate to find each other feature points provided in two points remotely on a substrate, also electronic components mounting position accuracy on the substrate is required The two land portions at the diagonal positions in the plurality of land portions in the predetermined portion that is the mounting portion to be recognized are recognized as specific feature points , and the position of the midpoint of these two land portions is obtained by since to obtain the positional deviation amount of the orthogonal coordinate axis direction, it is possible to improves the positional accuracy of the predetermined portion that require positional correction accuracy, to accurately correct the positional deviation in the rotational direction of the substrate.
[Brief description of the drawings]
FIG. 1 is a side view of a screen printing apparatus according to an embodiment of the present invention. FIG. 2 is a plan view of the screen printing apparatus according to an embodiment of the present invention. FIG. 4 is a block diagram showing a configuration of a control system of the screen printing apparatus according to the embodiment of the present invention. FIG. 6 is a flow chart of substrate alignment in screen printing according to an embodiment of the present invention. FIG. 6A is an explanatory diagram of substrate alignment according to an embodiment of the present invention. Illustration of substrate alignment [Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Board | substrate positioning part 6 Board | substrate 6a, 6b Recognition mark 6c Electrode site | part 6p Representative point 12 Mask plate 12a Pattern hole 13 Squeegee unit 20 Camera 31 Recognition mark position memory | storage part 34 Image recognition part

Claims (1)

A method of aligning a substrate in screen printing in which a mask plate provided with a pattern hole is brought into contact with the substrate, and paste is supplied onto the mask plate and a squeegee is slid to print the paste on the substrate, mutually determine the positional deviation angle of the rotation direction of the substrate by detecting the inclination of a straight line connecting the point feature formed in two points remotely on said substrate and an electronic component position accuracy is required on the substrate recognizes two land portions in diagonal positions of the plurality of land portions in the predetermined portion is a mounting portion to be mounted as a specific feature point, the by Rukoto obtain the position of the middle point of the two land portions In screen printing, a positional deviation amount of a predetermined part in the orthogonal coordinate axis direction is obtained, and a positional correction of the substrate is performed based on the positional deviation amount and the positional deviation angle. Alignment method of kick board.

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