JP2001315299A - Method for positioning screen mask in screen printing - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for positioning a screen mask in screen printing by which positioning of the screen mask can be efficiently performed. SOLUTION: In positioning the screen mask to a base sheet, pattern matchings of an electrode arranging pattern 6P and an opening pattern 12P formed by detecting plane shapes of electrodes 6a of the base sheet 6 and pattern holes 12a by means of a laser measuring device are performed to obtain a matching ratio and to obtain a relative position for providing the maximum matching ratio and it is outputted as a position for the mask. It is possible thereby to accurately and efficiently perform positioning even when there exists manufacturing errors and elongation and shrinkage of the base sheet 6 and the screen mask 12.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for aligning a screen mask in screen printing for printing a paste such as cream solder on a substrate.

[0002]

2. Description of the Related 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. According to this method, a screen mask having pattern holes opened according to a printing target portion is provided on a substrate, a paste is supplied on the screen mask, and a squeegee is slid, so that the squeegee slides on the substrate through the pattern holes. Prints the paste.

In this screen printing, it is necessary to accurately align a screen mask with a substrate. For this reason, when a screen mask is newly installed at the time of product change, the installation state of the screen mask,
That is, the displacement in the X, Y, and θ directions is detected and stored as an initial displacement, and when the production target board is set on the screen mask, the substrate is determined based on the stored displacement. Perform positioning.

For this alignment, position recognition by image processing has conventionally been used. That is, by performing image processing on image data obtained by imaging a plurality of electrodes and pattern holes that are set in advance as characteristic portions among the pattern holes provided in the screen mask corresponding to the electrodes of the substrate and the electrodes. The position of the center of gravity of the characteristic portion is determined, and the position of the center of gravity is matched to perform alignment.

[0005]

However, the positions of the electrodes of the substrate and the pattern holes of the screen mask may be affected by the initial manufacturing error and the expansion and contraction over time, and the relative positional relationship between the plurality of electrodes on the substrate and the position on the screen mask may be reduced. The relative positional relationship between the pattern holes does not always completely match. That is, when the substrate and the screen mask are superimposed, the center of gravity of the electrode and the center of gravity of the pattern hole, which are respectively specified as the characteristic portions, should originally coincide with each other. In many cases, they do not match due to expansion and contraction. For this reason, it has conventionally been necessary for an operator to reconfirm the relative position visually and perform manual correction after performing the image recognition of the characteristic portion and performing the alignment, and the alignment of the conventional screen mask is a great deal. It took a lot of trouble and time.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a method of aligning a screen mask in screen printing, which can efficiently perform the alignment of the screen mask.

[0007]

According to a first aspect of the present invention, there is provided a method of positioning a screen mask in screen printing.
In screen printing, in which a screen mask provided with pattern holes is brought into contact with a substrate and a paste is printed on the substrate by sliding a squeegee head on the screen mask, the screen mask is aligned with the substrate. A method of aligning a screen mask, comprising: detecting a planar shape of a characteristic portion of the substrate and a characteristic portion of the screen mask by shape detection means; and determining a substrate characteristic portion arrangement pattern and a mask characteristic portion arrangement pattern from the detection result. The process of creating,
A step of performing a pattern matching between the substrate characteristic portion arrangement pattern and the mask characteristic portion arrangement pattern to obtain a matching ratio, and calculating a relative position of the mask characteristic portion arrangement pattern with respect to the substrate characteristic portion arrangement pattern providing the maximum matching ratio as a mask position. Outputting and storing the output result in the mask position storage unit.

According to a second aspect of the present invention, there is provided a method of aligning a screen mask in screen printing, wherein the shape detecting means is a three-dimensional measuring means. The characteristic portion of the substrate and the characteristic portion of the screen mask are an electrode provided on the substrate and a pattern hole provided on the screen mask corresponding to the electrode, respectively, and the upper surface of the substrate and the screen mask are scanned by three-dimensional measuring means. Thereby, the substrate characteristic portion arrangement pattern and the mask characteristic portion arrangement pattern are created.

According to a third aspect of the present invention, there is provided a method of positioning a screen mask in screen printing.
It is a method of aligning a screen mask in the screen printing described above, wherein the substrate characteristic portion arrangement pattern and the mask characteristic portion arrangement pattern are created with only a specific portion of the substrate and the screen mask as a target range.

According to the present invention, the substrate feature arrangement pattern and the mask feature arrangement pattern created by detecting the planar shapes of the substrate feature and the screen mask feature by the shape detecting means are subjected to pattern matching. By calculating the matching rate, calculating the relative position of the mask feature arrangement pattern with respect to the board feature arrangement pattern that gives the maximum matching rate, and outputting the result as the mask position,
Even if there is a manufacturing error or expansion / contraction of the substrate or the screen mask, accurate and efficient alignment can be performed.

[0011]

Embodiments of the present invention will now be described with reference to the drawings. FIG. 1 is a front view of a screen printing apparatus according to one embodiment of the present invention, FIG. 2 is a side view of the screen printing apparatus according to one embodiment of the present invention, and FIG. 3 is a screen printing apparatus according to one embodiment of the present invention. FIG. 4 is a perspective view of a laser measuring device of the screen printing apparatus according to one embodiment of the present invention, FIG. 5 is a block diagram showing a configuration of a control system of the screen printing apparatus of one embodiment of the present invention, FIG. 6 is an explanatory diagram of an electrode arrangement pattern and an opening pattern in screen printing according to one embodiment of the present invention, and FIG. 7 is a perspective view of a substrate and a screen mask of a screen printing apparatus according to one embodiment of the present invention.

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 unit stacks a θ-axis table 4 on a moving table including an X-axis table 2 and a Y-axis table 3, and further has a Z-axis table 5 thereon. A substrate holding unit 7 is provided on the Z-axis table 5 for holding the substrate 6 sandwiched by the clampers 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 substrate 6 is carried out by the carry-out conveyor 15.

A screen mask 10 is provided above the substrate positioning unit 1. The screen mask 10 is configured by mounting a mask plate 12 on a holder 11. The substrate 6 is positioned with respect to the mask plate 12 by the substrate positioning unit 1 and abuts from below. A squeegee head 13 is disposed on the screen mask 10 so as to be able to reciprocate in a horizontal direction. With the substrate 6 in contact with the lower surface of the mask plate 12, the mask plate 12
An electrode 6a formed on the surface of the substrate 6 (see FIG. 3) is supplied by supplying cream solder 9, which is a paste, onto the surface of the substrate 6 by sliding the squeegee 13a of the squeegee head 13 into contact with the surface of the mask plate 12. The cream solder 9 is printed on the upper surface through a pattern hole 12a (see FIG. 3) provided in the mask plate 12.

Above the screen mask 10, there is provided a laser measuring device 20 which is both a three-dimensional measuring means and a shape detecting means. As shown in FIG. 3, the laser measurement device 20 includes an X-axis table 21 and a Y-axis table 2.
2 to move horizontally in the X and Y directions, and can be raised and lowered by lifting means 23 (FIGS. 1 and 2). Lifting means 2
By driving 3, the laser measurement device 20 is lowered to the measurement height position. The X-axis table 21, the Y-axis table 22, and the elevating means 23 are moving means for moving the laser measuring device 20.

The laser measuring device 20 has a function of measuring a displacement in a vertical direction by irradiating a laser beam and a scanning mechanism for scanning a laser irradiation position in XY directions.
By scanning the irradiation point P within the measurement range R as shown in FIG. 4, the vertical position of the surface of the measurement object within the measurement range R is continuously detected, and the three-dimensional shape of the measurement object can be detected. It has become.

By moving the laser measuring device 20 with respect to the substrate 6 and the mask plate 12 by the moving means, a three-dimensional shape measurement can be performed on an arbitrary range of the substrate 6 and the mask plate 12. By processing the obtained detection data, it is possible to detect the arrangement pattern of the electrodes 6a, which are the characteristic portions of the substrate 6, and the arrangement pattern of the pattern holes 12a, which are the characteristic portions of the screen mask 10, that is, the planar shape. Further, by performing three-dimensional measurement on the substrate 6 after screen printing, the cream solder 9 printed on the substrate 6 is measured.
Can be detected three-dimensionally.

Next, the configuration of the control system of the screen printing apparatus will be described with reference to FIG. In FIG.
U30 is an overall control unit that performs overall control of each unit described below. The program storage unit 31 stores various programs such as an operation program for screen printing, a processing program for detecting the shape of the substrate 6 and the mask plate 12 from a detection signal of the laser measurement device 20, and a program for determination processing in print inspection. Remember. Data storage unit 32
Stores reference value data for determination processing in print inspection, data of printing conditions set for each type, and data of a mask position used for alignment of the screen mask 10. That is, the data storage unit 32 is a mask position storage unit.

The mechanism control unit 33 includes the substrate positioning unit 1, the carry-in conveyor 14, the carry-out conveyor 15, and the X-axis table 2.
1. The operation of each mechanism such as the Y-axis table 22 is controlled. The shape detection unit 34 processes a detection signal obtained by scanning the laser measurement device 20 to form an electrode arrangement pattern (substrate characteristic unit arrangement pattern) indicating a planar arrangement of the electrodes 6 a provided on the substrate 6 and a mask. Plate 12
(See FIG. 6).

The matching processor 35 performs pattern matching between the electrode arrangement pattern of the substrate 6 thus created and the opening pattern of the screen mask 10 to obtain a matching ratio. The mask position calculation unit 36 obtains the relative position of the mask feature portion arrangement pattern with respect to the board feature portion arrangement pattern that gives the maximum matching rate by pattern matching, and determines the mask position, that is, the substrate 6 at the time of printing.
Is output as a position correction amount to be corrected at the time of alignment with the mask plate 12. The obtained mask position is stored in the data storage unit 32.

The substrate / mask determining section 37 includes the shape detecting section 3
By comparing the electrode arrangement pattern of the substrate 6 detected by the step 4 and the opening pattern of the screen mask 10 with a reference pattern on the design data, the quality of the substrate 6 and the mask plate 12 supplied to the screen printing apparatus is determined. . The print determination unit 38 determines the quality of the printed state by comparing the shape data of the cream solder 9 obtained by measuring the screen printed substrate 6 with the laser measuring device 20 with reference data stored in advance. .

Next, a method of aligning the substrate and the screen mask will be described with reference to the drawings. This alignment is performed by exchanging the screen mask 10 according to the board type, and then mounting the screen mask 10 and the board 6 on the mounted state.
This is performed for the purpose of detecting a relative displacement amount with respect to.

First, in FIG.
4 and is positioned by the substrate positioning unit 1. Next, the planar shape of the substrate 6 and the mask plate 12 is measured by the laser measuring device 20. That is,
First, three-dimensional measurement of the mask plate 12 is performed while moving the laser measurement device 20 on the mask plate 12. In the area of the pattern hole 12a of the mask plate 12, a different three-dimensional measurement result is shown from that of the other portion having no opening. Therefore, plane data indicating the position and shape of the pattern hole 12a is detected by the three-dimensional measurement.

Next, the substrate positioning unit 1 is moved from below the mask plate 12 to the substrate measurement position, and the three-dimensional measurement of the upper surface of the substrate 6 is similarly performed by the laser measurement device 20. At the position where the electrode 6a is formed on the substrate 6,
Since the three-dimensional measurement results are different from those of the other parts without the electrode 6a, the position of the electrode 6a
Plane data indicating the shape is detected.

Next, from the plane data of the substrate 6 and the mask plate 12, an electrode arrangement pattern and an opening pattern are created. Here, two-dimensional image data in which the portion of the electrode 6a and the opening of the pattern hole 12a are respectively separated from other ranges are obtained from the plane data of the substrate 6 and the mask plate 12 obtained by the measurement, as shown in FIG. An electrode arrangement pattern 6P and an opening pattern 12P are created as shown in FIGS.

In forming the electrode arrangement pattern 6P and the opening pattern 12P, not all the electrodes 6
It is not necessary that the pattern is intended for the pattern a or the pattern hole 12a, and a pattern that is partially thinned out may be created in view of the required accuracy and processing time. For example,
In the case of adopting the simplest form, only the two electrodes 6a (indicated by arrows) at diagonal positions of the substrate 6 and the two pattern holes 12a (indicated by arrows) of the mask plate 12 are targeted. Arrangement pattern 6P, opening pattern 12P
Only the portions corresponding to the electrodes 6a and the pattern holes 12a may appear.

Next, pattern matching is performed.
That is, the opening pattern 12P created by the above processing
Is moved relative to the electrode arrangement pattern 6P by a predetermined skip value to perform pattern matching, and a matching ratio at each relative position is obtained. Then, among these matching rates, the relative position that gives the largest matching rate is specified. Then, the relative position of the mask plate 12 with respect to the substrate 6 corresponding to this state is output as a mask position. Then, the detected mask position is stored in the data storage unit 32.

Next, the amount of misalignment between the substrate 6 and the mask plate 12 is determined from the detected mask position, and the necessary amount of position correction is calculated. At the time of screen printing, by driving each axis table of the substrate positioning unit 1 based on the position correction amount, the substrate 6
Correctly aligned with

As described above, the position of the screen mask shown in this embodiment with respect to the substrate
Pattern matching is performed between an electrode arrangement pattern 6P indicating the position and shape of the electrode 6a, which is a characteristic part of the above, and an opening pattern 12P indicating the position and arrangement of the pattern holes 12a of the mask plate 12, and the mask position is determined based on the pattern matching result. Is what you want. Accordingly, even when there is an initial positional shift due to a manufacturing error of the substrate 6 or the screen mask, or when there is expansion and contraction due to a temperature change after the manufacturing, the positioning can be performed in consideration of the positional shift state as a whole. Can be improved.

In this pattern matching,
If there is a specific range in the same substrate, for example, a range in which particularly high alignment accuracy is required (for example, a range in which narrow pitch electrodes are formed), as shown in FIG. To create this range A
If the pattern matching is performed with the opening pattern created for the range A ′ of the screen mask 10 corresponding to the above, the processing time required for the pattern matching can be reduced, and the portion requiring high positional accuracy is preferentially positioned. Matching can be performed.

In this embodiment, an example is shown in which a laser measuring device is used as a method for creating an electrode arrangement pattern and an opening pattern. According to this method, a substrate or mask plate is imaged with a conventional camera. By performing image processing on the image data obtained as described above, it is possible to perform processing efficiently without requiring image processing such as binarization processing, as compared with a method of obtaining an electrode arrangement pattern or an aperture pattern. Of course, the present invention can be applied to the case where an electrode arrangement pattern and an opening pattern are created by imaging with a conventional camera.

[0031]

According to the present invention, pattern matching is performed between a substrate characteristic portion arrangement pattern and a mask characteristic portion arrangement pattern created by detecting the planar shape of the characteristic portion of the substrate and the characteristic portion of the screen mask by the shape detecting means. To obtain the matching ratio, and obtain the relative position of the mask feature portion arrangement pattern with respect to the board feature portion arrangement pattern that gives the maximum matching ratio, and output it as the mask position. Even if there is, accurate and efficient alignment can be performed.

In the above-described embodiment, an example of an open squeegee head having a plate-shaped squeegee is shown as a type of squeegee head. However, the present invention is not limited to this. A closed squeegee head that slides on the mask plate while pressing the cream solder and fills the pattern hole with the cream solder may be used.

[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 the screen printing apparatus according to the embodiment of the present invention.

FIG. 3 is a plan 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 the screen printing device according to the embodiment of the present invention.

FIG. 5 is a block diagram illustrating a configuration of a control system of the screen printing apparatus according to the embodiment of the present invention.

FIG. 6 is an explanatory diagram of an electrode arrangement pattern and an opening pattern in screen printing according to an embodiment of the present invention.

FIG. 7 is a perspective view of a substrate and a screen mask of the screen printing apparatus according to one embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Substrate positioning part 6 Substrate 9 Cream solder 10 Screen mask 12 Mask plate 12a Pattern hole 13 Squeegee head 20 Laser measurement device 32 Data storage part 34 Shape detection part 35 Matching processing part 36 Mask position calculation part

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H05K 3/12 610 H05K 3/12 610P 3/34 505D 3/34 505 512B 512 G01B 11/24 A (72 ) Inventor, Shigetaka Abe 1006, Kazuma, Kazuma, Osaka Pref., Matsushita Electric Industrial Co., Ltd. FB24 FB27 FB33 FB42 FC07 FD01 2F065 AA03 AA04 AA06 AA54 BB02 BB05 BB29 CC01 CC26 DD06 FF04 FF42 FF61 GG01 MM16 PP12 QQ24 QQ38 5B057 AA03 BA01 DA07 DB03 DB09 DC32. FF13 FF30 GG18

Claims (3)

[Claims] In screen printing, a screen mask provided with a pattern hole is brought into contact with a substrate, and a squeegee head is slid on the screen mask to print a paste on the substrate. A method of aligning a screen mask in screen printing for aligning, wherein a step of detecting a planar shape of a characteristic portion of the substrate and a characteristic portion of the screen mask by shape detection means, and a substrate characteristic portion arrangement pattern and A step of creating a mask feature portion arrangement pattern; a step of performing a pattern matching between the board feature portion arrangement pattern and the mask feature portion arrangement pattern to obtain a matching ratio; and a mask feature portion for the board feature portion arrangement pattern that provides the maximum matching ratio. Find relative position of placement pattern Process and alignment process of the screen mask in the screen printing, which comprises a step of storing the output results to the mask position storage unit for outputting the disk position. 2. The method according to claim 1, wherein the shape detecting means is a three-dimensional measuring means, wherein the characteristic portion of the substrate and the characteristic portion of the screen mask are electrodes provided on the substrate and a pattern provided on the screen mask corresponding to the electrodes. 2. The screen printing method according to claim 1, wherein the hole is a hole, and the substrate characteristic portion arrangement pattern and the mask characteristic portion arrangement pattern are created by scanning the upper surface of the substrate and the screen mask by a three-dimensional measuring means. Screen mask alignment method. 3. The screen printing method according to claim 1, wherein the substrate characteristic portion arrangement pattern and the mask characteristic portion arrangement pattern are created only for a specific portion of the substrate and the screen mask. Screen mask alignment method.