JPH02253956A - Printing method and printing press - Google Patents

Abstract

PURPOSE:To always efficiently perform accurate pattern printing by moving at least one of a substrate and a mask when the positional relation between the mask and the substrate is shifted from normal one to correct the positional relation. CONSTITUTION:Optical recognition apparatuses 51, 54 of optically recognizing the detection part PB on the substrate P corresponding to a specific screen mesh 24 through the through-hole of the screen mesh 24, a judging means 51 judging the presence and quantity of the shift between the substrate P and a mask 15 on the basis of the recognition due to the recognition apparatuses and correction means 15, 16, 17, 18 correcting the positional relation between the mask and the substrate corresponding to shift quantity when the shift is present are mounted. Therefore, the optical recognition apparatuses recognize the part PB to be detected in the pattern PA of the substrate through the specific screen mesh of the mask and, when it is judged that shift is generated between the mask and the substrate on the basis of the recognition of the part PB to be detected, at least one of the substrate and the mask is revolved or linearly moved within a horizontal plane to correct the shift between both of them.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a printing method and a printing machine for screen printing a pattern such as a circuit on a substrate using a mask.

[Prior Art] In screen printing of circuits, etc., it is necessary to accurately place a pattern at a predetermined position on the board based on the mounting position of components on the board, alignment with other printed circuits on the board, etc. Need to print.

For this reason, in the past, the position was confirmed through trial printing and the misalignment between the mask and the substrate was manually corrected before proceeding to the normal printing process. In the separated state, the position of the mask and the substrate can be image-recognized using a camera, etc., and the misalignment can be corrected, or just before the substrate is sent under the mask, the substrate and the mask can be moved on the substrate transport route. A method has been adopted in which the image fIi is recognized using a camera or the like at a different position and the deviation is corrected.

[Problem to be Solved by the Invention] In this case, the above-mentioned method of test printing requires that test printing be performed every predetermined number of printing cycles to prevent misalignment from accumulating and increasing with each printing. be. Therefore,
It is not possible to print continuously and it is impossible to continue the printing work efficiently. Moreover, even if a positional shift occurs after a test print, printing continues as is until the next test print, and the frequency of defective products increases. In addition, in the method of recognizing the positional relationship between the substrate and the mask while the mask is separated from the substrate, when the mask moves toward the substrate after recognition, the movement causes a misalignment between the substrate and the mask. There are many risks and this requires a very high level of mechanical precision in the printing press. In addition, if a camera lens or the like is placed in the space between the mask and the substrate that is too wide or too dark when the masks are separated, the camera lens or the like will be removed during printing. There is also the problem that a mechanism for avoiding the problem is required, which makes the configuration complicated.

Furthermore, in the method of recognizing the substrate and the mask at different positions on the substrate transport route, mechanical precision is required because there is a possibility that a shift may occur when the substrate is moved, as described above. Not only that, but a device is required to stop and recognize the position of the board before the mask position, that is, the printing position, in the board transport direction, so the entire printing machine is large in the board transport direction. There was also the problem of becoming

An object of the present invention is to provide a printing method that can efficiently print patterns without placing excessive demands on the mechanical accuracy of a printing machine or the accuracy of a board's external shape, and can also print patterns accurately at all times. and to provide printing machines.

[Means for Solving the Problems] In order to achieve the above object, in the present invention, in a printable state in which a mask is placed close to a substrate, a pattern corresponding to the same screen pattern is printed through a predetermined screen pattern. The non-detection part inside is optically nl to determine the positional relationship between the mask and the substrate, and if the positional relationship in A deviates from the normal one, at least one of the substrate and the mask is moved to determine the positional relationship. Correct.

Further, in the present invention, there is provided an optical [device] for optically recognizing a detected portion on a substrate corresponding to a specific screen pattern through the through-hole of the screen pattern; It is provided with a discriminating means for determining the presence or absence of a misalignment with the mask and the amount of misalignment, and a correcting means for correcting the positional relationship between the mask and the substrate in accordance with the misalignment when a misalignment exists.

[Operation] Therefore, when the mask is in a printable state where the mask is close to the top surface of the substrate, the optical recognition device recognizes the detected portion in the pattern of the substrate through the specific screen eyes of the mask, thereby detecting the area between the mask and the substrate. If it is determined that there is a misalignment, at least one of the substrate and the mask is moved in a horizontal plane or linearly to correct the misalignment between them.

[Example] Hereinafter, an example embodying the present invention will be described based on the drawings.

First, the configuration of the printing press will be explained. As shown in Fig. 2, the machine frame 1 has a control box 2 on the upper surface of one side, and various keys (not shown) are provided on the front of the control box 2.
A keyboard 3 is arranged, and a monitor shaker 4 is placed on the top surface. A pair of conveyors 5 are arranged facing each other on the upper surface of the machine frame 1.
The substrate P is transported in the direction of the arrow X in FIGS. 2 and 3. A sizing chuck 6 is disposed at an intermediate position in the conveyor direction of the conveyor 5, as shown in FIG. 5, so that the substrate P can be gripped and fixed at the printing position.

The machine frame 1 has a cylinder (
A support plate 7 is provided which can be moved up and down by a screw (not shown) or the like, and supports the substrate P at the printing position from the bottom side thereof so as not to curve. Further, a sensor 8 shown in FIG. 7 is arranged near the chuck 6, and a detection signal is output from the sensor 8 via a comparator 9 when the substrate P reaches the printing position and is chucked.

An elevating frame 11 is arranged on the upper surface of the machine frame 1 and is moved up and down while maintaining a horizontal state by a driving means such as a motor (not shown). It is mounted rotatably. A frame holding plate 13 is fixed within the screen frame 12,
A mask 15 is held in a holding hole 14 formed in the center. As shown in FIG. 1, two pulse motors 16. ．． 17 is arranged and fixed, and one pulse motor 18 is arranged and fixed on another side adjacent to the - side, and these pulse motors 16
, 17. The output shafts (not shown) of 18 include a retractable shaft 19 which is retracted and retracted by the action of a screw as the output shaft rotates.
are screwed together, and a roller 20 is supported at the tip of each output shaft 19 so as to be rotatable around a vertical axis.

Between the screen frame 12 and the lifting frame 11 are springs 21, 22, 23 for pressing the screen frame 12 toward the rollers 20 of the pulse motors 16 and 17 and the roller 20 of the pulse motor 18, respectively. It is stretched. Therefore, when the pulse motors 16, 17, 18 are rotated in either the forward or reverse direction and the protruding/retracting shaft 19 protrudes/retracts, the screen frame 12 is moved by the springs 21, 22, .
It is linearly moved or rotated against the spring force of 23.

The mask 15 has transparent screen holes 24 (only partially shown) for transferring paste (not shown) onto the upper surface of the substrate P.

Cylinders 32 and 33 are provided between a pair of rails 31 disposed oppositely on both sides of the lifting frame 11 and reciprocated along the transport direction of the substrate P by a motor (not shown).
A squeegee 34 and a doctor 35 are fixed to the lower ends of the pistons of the cylinders 32 and 33, respectively. And cylinder 32. ．． Squeegee 34 and doctor 3 based on the protruding action of screws 1 to 33
5 is placed in the lower position, the cylinders 32 and 33 are reciprocated along the rail 31, thereby filling the screen openings 24 with the paste,
Transfer of the paste to the substrate P, that is, pattern printing is performed.

As shown in FIGS. 2 and 4, a rail 41 extending parallel to the rail 31 is arranged and fixed above the machine frame 1, and a motor (not shown) is mounted on the rail 41. Another rail 42 is supported which is reciprocated in the direction in which rail 41 extends. On the same rail 42 is a motor (
(not shown) supports a bracket 43 that is reciprocated in the extending direction of the rail 42, and a television camera 45 that is moved up and down by a cylinder 44 is supported on the bracket 43.
is supported. Therefore, the television camera 45 is
Can move in either direction.

As shown in FIGS. 3 and 6, a conductive pattern PΔ is previously formed on the upper surface of the substrate P so as to correspond to the screen openings 24 of the mask 15. As shown in FIGS. Then, a pair of specific portions of the paste filling screen 24 that are approximately square and are respectively close to the two diagonal corners of the substrate P are defined as the detection windows 2.
4a.

24, b) is selected at 2B, and the detection window 24 is selected.
A specific part of the conductor pattern PA corresponding to a, 24b (hereinafter referred to as the detected part PB) is the detection window 2.
It is optically recognized by the television camera 45 through 4a and 24b.

Next, the electrical configuration of the printing press will be explained based on FIGS. 1 and 7. The T1lilJ control circuit 51 shown in FIG. 1 and FIG. A third control circuit 51 constitutes an optical recognition device for optically recognizing the detected portion PB of P.
and pulse motor 16°17, . Reference numeral 18 constitutes a correction means for correcting the misalignment between the substrate P and the mask 15. In this control means 51, a binarization processing circuit 52
converts the analog video signal of the camera 45 into a binary signal via the interface 61 and stores it in the image memory 5.
Output for 3. The image memory 53 stores a plurality of double-sided images of the binary signal, and outputs the image data to a microprocessor (hereinafter simply referred to as MPIJ) 54 as necessary. A run-length memory 55 performs run-length encoding processing on the image stored in the image memory 53 and stores the encoded image.

A read-only memory (hereinafter simply referred to as ROM) 56 stores programs shown in FIGS. 8 and 9FgJ, which will be described later, for controlling the operation of the mark finR.

Random access memory (hereinafter simply referred to as RAM) 62
temporarily stores position data of the detection windows 24a, 24b of the pre-screw 15. And MPLJ54 is ROM56
The camera 45 and sensor 8
The necessary images are displayed on the monitor television 4 via the video mixer 57 based on the input from the pulse motor 16.1 via the drive circuits 58, 59 and 60.
7. 18 is rotated to move the screen frame 12.

Next, the operation of the printing press configured as described above will be explained with reference to the flowchart shown in FIG.

As mentioned above, the flowchart shown in FIG.
The process proceeds under the control of the MPU 54 according to the program stored in the OM 56. Now, the substrate P that has been transported to the printing position is gripped by the chuck 6 at the printing position, supported from below by the support plate 7, and its state is detected by the sensor 8 (step S1゜).
(hereinafter, "step" will be omitted), the screen frame 12 is lowered and the mask 15 closely faces the upper surface of the substrate P (
S2). Next, the camera 45 is moved from the home position H to a position facing one detection window 24a of the mask 15 (the position of this detection window 24a is defined as point A) (S3).
Then, the camera 45 is lowered by the cylinder 44 (S4).

Then, as shown in FIG. 6, the detection window 24a is arranged at point A1, and one corner a of the detected part PB is located at the detection window 24a.
The mass bar 15 is moved by the operation of the pulse motors 16 to 18, and the amount of movement is stored in the RAM 62 (S5). Next, the corner a of the detected part P8 is detected by the camera 45. It is optically recognized and the position is detected with corner C of the detection window 24a as a reference, and the position of corner a is stored in the RA, M 62 (S6).The position of corner a etc. is binarized. This can be determined based on the data obtained.

Next, the detection window 24a is arranged at two points 1jA as shown in FIG. The mask 15 moves due to the operation of
The amount of movement is stored in the RAM 62 (S7). Then, the position of the corner b is detected based on another corner d diagonally corresponding to the corner C of the detection window P8, and is stored in the RAM 62 (88).

Next, based on the positions of the corners a and b, the detected part P
The center position of a is calculated and stored in the RAM 62 (S
9). Then, the center position of the detection window 24a is compared with the center position of the detected portion PB detected in the routine up to S9 (S10). Note that the center position of the detection window 24a is stored in advance in RA Mo2,
When the pulse motors 16 to 18 are rotated, the detection window 24 a is detected based on the amount of rotation of the pulse motors 16 to 18.
The center position of the detection window 24a and the center position of the detected part l]8 are then calculated. Based on this, it is determined whether there is a shift (Sll.

512). If there is a deviation, pulse motor 1
At least one of the elements 6 to 18 is rotated to open the detection window 2.
The correction movement of the mask 15 is performed so that the centers of each of the detection part 4a and the detection part Pa coincide and the deviation is corrected (3
13). In this case, as a method for correcting the mask 15, for example, the mask 15 is linearly moved in the X direction and the Y direction by simultaneous rotation of the pulse motors 16 and 17 in the same direction or by rotation of the pulse motor 18 alone.
The pulse motors 16 to 16 are operated so that the center position data of
Rotate 18.

Next, another detection corresponding approximately on the diagonal line of the substrate P with respect to the point A! 24b and the position of the detected part PB (hereinafter this position will be referred to as 8 points) (814),
Detection of the position of corner a at point 81 (S15 and 816) and detection of the position of corner b at point 82 (817) in the same manner as the routine shown in FIG.
and 818), the respective center positions of the detection window 24b and the detected portion PB are compared (819). In addition, 814
The movement of the mask 15 in steps 819 to 819 is performed by rotating the mask 15 about the same center so that the centers of the detection window 24b and the detected part Pa at the point A do not deviate. Then, the camera 45 rises and returns to the home position H (820), and the center positions of the detection 'H, 24b and the detected part Pa are compared (821), and based on the comparison, the deviation between the two center stations is determined. The amount is calculated (822)
, the presence or absence of positional deviation is determined (823). The mask 25 is operated by the pulse motors 16 to 18 so that the positional deviation is corrected when the positional deviation occurs.
is corrected and moved (S24), and then moves to the printing process (825). If no positional deviation has occurred, the process skips S24 and proceeds to the printing process. Since the centers of the detection window 24a and the detected part PB are already aligned at the point A, the positional deviation at the 8 points is due to the position in the rotational direction about the center of the detection window 24a and the detected part PB at the point A. It is calculated as a passing. Therefore, the rotation angle difference between the eight detection windows 24b and the center of the detected part PB is defined as
Instead of the difference in position data in the direction and Y direction,
If the substrate P is rotated around point A so that these differences converge, the positional deviations at the eight points will be corrected. Therefore, the positional deviation with respect to the mask 15 near the two diagonal corners of the substrate P is completely corrected, so that the mask 15 and the substrate P are accurately aligned with a predetermined positional relationship, and the paste is transferred to the substrate P. The image is transferred with accurate positional relationship.

As described above, in the printing method using this printing machine, there is no need for test printing, and detection target 1! By detecting ll5PB, it is possible to perform printing while accurately matching the positional relationship between the substrate P and the mask 15.

Moreover, the alignment between the substrate P and the mask 15 is performed at a printable position where the mask 15 closely faces the substrate P,
After the position is detected, there is no need for the board to be transported or the mask to be moved away from the board, so it has nothing to do with the mechanical accuracy of the printing machine, the accuracy of the external dimensions of the board, or the accuracy of the holes in the screen. In addition, the camera only takes pictures from one side of the mask downwards, and there is no need for a mechanism to move the camera in and out between the mask and the substrate, which requires high mechanical precision and complicates the configuration. There isn't.

Moreover, since the positions of the substrate P and the mask 15 are not detected at different positions, there is no need to provide a mechanism for position detection other than the printing position, and the entire printing machine does not become large.

It should be noted that this invention is not limited to the above embodiments, and may be embodied in the following S.

(1) Arbitrarily changing the shapes of the detected portion PB and the detection windows 24a and 24b. In short, the detection windows 24a, 2
The shapes of the detection marks 124a and 24b and the recognition mark Pa are not limited to squares, as long as the center position of the detected portion PB can be recognized from the detection mark 4b.

(2) Set the camera 45 to 2 locations corresponding to point A and point 8, respectively.
A stand must be provided. In this way, it is not necessary to move the camera 45, and the printing time can be shortened accordingly.

(3) Aligning the mask 15 and the substrate P by moving the substrate P within a horizontal plane. In this case, it is preferable that the positioning be performed by the movement of the chuck 6 that grips the substrate P.

(4) Mask] 5 and the substrate P are aligned so that both the substrate P and the mask 15 are moved. In this case, one of the mask 15 and the substrate P rotates within a horizontal plane, and the other moves linearly within the same horizontal plane.

(5) In the above embodiment, the center of one of the detected parts PB is detected, the deviation of the center position is corrected, and then the center position of the other detected part PB is detected and the deviation of the position is corrected. The configuration is such that the center position of the detected part PB at points A and B is first detected, and then the deviations at points A and B are corrected. In this case, similarly to the embodiment described above, after aligning the center position of the detection window 24a with the center position of one detected portion PB, the other position is adjusted by rotating the substrate P around the center position. Even if the center position is adjusted, another method is to simultaneously rotate the pulse motors 16 and 17 in different directions and to rotate the pulse motor 18
The mask 15 and the substrate P are aligned in the same direction by normal rotation or reverse rotation of the mask 15, and then the mask 15 is linearly moved in the X direction 9Y direction by simultaneous rotation of the pulse motors 16 and 17 in the same direction or by normal rotation or reverse rotation of the pulse motor 18. It is also possible to correct the positional deviation.

(6) Before the detection operation of the detected part PB, the detection windows 24a, 2
4b, the center of the detection windows 24a, 24b is set, and the center position of the detected part PB is detected accordingly. In this way, alignment can be performed even more accurately.

(7) By detecting one corner of the detected part Pa and one or two sides extending from its second corner,
The center position detection operation for each detected part PB should be configured to be completed in one operation. However, when configured in this way, it is essential that the detected portion PB is always accurately formed to have a predetermined shape and size.

(8) In the above embodiment, the detected parts Pa near the two diagonal corners of the board P were detected, but for example, the detected part PB could be set near both ends of one side of the board P. , change the position and number of the detected parts, such as setting the detected part Pa to four corners.

(9) Other modifications may be made to the structure of each part without departing from the spirit of the invention.

[Effects of the Invention] As exemplified in the embodiments above, in this invention, the position of the substrate is detected through a part of the screen openings when the mask is in a printable state where the mask is close to and opposed to the substrate. This eliminates the need for printing work, which makes printing work more efficient, and prevents the need for high mechanical precision, the complexity of the configuration, and the overall size. It exhibits an effect that does not require any configuration.

[Brief explanation of drawings]

Fig. 1 is a plan view showing the configuration for correcting movement of the mask, Fig. 2 is a front view of the printing press, Fig. 3 is a simplified perspective view showing the printing mechanism, and Fig. 4 shows the relationship between the mask and the television camera. A plan view, FIG. 5 is an exploded perspective view showing the position detection state, FIG. 6 is a partial plan view showing the relationship between the detection window and the detected part, and FIG. 7 is a block diagram showing the electrical configuration of the printing press. , FIG. 8 is an operation flowchart of the printing press including the detection operation. 15...Mask, 16,17.18...Pulse motor, 24...Screen, 24a, 24b...
Detection window, 34... Squeegee, 45... Television camera, 51... Control circuit, tiIj-circuit 51 constitutes a discrimination means, control circuit 51 and television camera 45 constitute an optical recognition device, and controls The circuit 51 and the pulse motor 16.17.18 constitute the correction means. Patent applicant CKD Co., Ltd. Agent
Patent Attorney On 1) Hironobu (and 1 other person) Fig. Fig.

Claims (2)

[Claims] 1. A printing method in which a mask with transparent screen holes for forming a printing pattern is placed on a substrate, and paste is transferred onto the substrate via the screen holes using a squeegee.The mask is placed close to the substrate. In this state, the positional relationship between the mask and the substrate is determined by optically recognizing the detected part in the pattern corresponding to the same screen through a predetermined screen, and the positional relationship deviates from the normal one. A printing method characterized in that, in some cases, at least one of a substrate and a mask is moved to correct the positional relationship between the two. 2. The screen that forms the printing pattern is transparent,
In a screen printing machine that has a mask that can be moved into and out of contact with a substrate and a squeegee that transfers paste onto the substrate through a screen pattern, the paste is transferred onto the substrate corresponding to the same screen pattern through a specific screen pattern. an optical recognition device for optically recognizing the detection section; a determining means for determining the presence or absence of a misalignment between the substrate and the mask and the amount of misalignment based on the recognition by the optical recognition device; A printing machine characterized by comprising a correction means for correcting the positional relationship between the mask and the substrate accordingly.