JPH02207590A - Printing method and printing machine - Google Patents

Abstract

PURPOSE:To assure pattern printing accurate at all times with high efficiency by permitting, in a printable state where a mask is disposed in close vicinity to a substrate, an optical recognition device to recognize a mark on the board through a transparent hole formed through the mask and correct any displacement of at least one of the substrate and the mask. CONSTITUTION:A substrate P conveyed to a printing position is detected in its state by a sensor at that position, and a screen frame 12 is lowered to force a mask 15 to approach and oppose the upper surface of the substrate P. Then, a camera 45 is lowered to compare positional pre-registered data of a transparent hole 25 formed through the mask 15 with that of a transparent hole 25 detected by the camera 45 for detection of a mask 15 position and further compare a position of a mark PB on the substrate P with the position of the transparent hole 25 through the mask 15 for decision of the presence of any displacement therebetween. Further, at least one of pulsed motors 16, 17, and 18 is rotated to move the mask 15 for correction of the position of the same such that the transparent hole 25 through the mask 15 is coincident with the recognition mark PB on the substrate P at the centers thereof.

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. The positional relationship between the mask and the substrate can be image-recognized using a camera or the like while they are separated, and the misalignment can be corrected, or the substrate and the mask can be separated from each other on different substrate transport routes just before the substrate is sent under the mask. A method has been adopted in which the image is recognized using a camera or the like at the 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 when the mask is separated from the substrate, when the mask moves toward the substrate after recognition, the gap between the substrate and the mask is caused by the movement. There are many possibilities for misalignment, which requires a very high level of mechanical precision in the printing press.

In addition, if a camera lens, etc. is placed in the not-so-wide space between the mask and the substrate when the masks are separated, a mechanism for retracting the camera lens, etc. will be required during printing, which will complicate the configuration. There were also problems.

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 was needed to temporarily stop and recognize the position of the board before the mask position in the board transport direction, which caused the problem that the entire printing machine became larger in the board transport direction. .

An object of the present invention is to enable efficient pattern printing without excessively demanding mechanical precision, substrate external shape precision, and hole precision of a printing machine, and to always be able to perform accurate pattern printing. An object of the present invention is to provide a method and a printing machine.

Means for Solving Problems] To achieve the above object, in the present invention, a through hole is formed in a mask, a mark is attached to a substrate corresponding to the through hole, and the mask is attached to a substrate. The mark is optically recognized through the through hole in a printable state placed close to the top of the mask to determine the positional relationship between the mask and the substrate, and if the positional relationship deviates from the normal one, the mark is At least one of the masks is moved to correct the positional relationship.

Further, in the present invention, the mask has a through hole, an optical recognition device for optically recognizing a mark made on the substrate through the through hole, and a recognition device by the optical recognition device. The apparatus is provided with a determining means for determining the presence or absence and amount of misalignment between the substrate and the mask, and a correcting means for correcting the positional relationship between the mask and the substrate in accordance with the amount of misalignment, if any 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 marks the substrate through the through hole of the mask! ! ! If it is determined that a misalignment has occurred between the mask and the substrate, at least one of the substrate and the mask is rotated or linearly moved in a horizontal plane to correct the misalignment between the two. .

[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 television 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 chuck 6 shown in FIG. 5 is disposed at an intermediate position in the conveyor direction of the conveyor 5, and is capable of gripping and fixing the substrate P 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 and 17 are arranged and fixed on one side of the lifting frame 11, and one pulse motor 18 is arranged on another side adjacent to the - side. fixed, those pulse motors 16,
A retractable shaft 19 that is retracted and retracted by the action of a screw as the output shaft rotates is screwed to the output shaft (not shown) of 17 and 18, and a roller 20 is connected to a vertical shaft at the tip of each output shaft 19. is rotatably supported around the 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 rotated by the springs 21, 22.
It is moved linearly or rotated against the spring force of 3.

The mask 15 is provided with a transparent screen 24 for transferring paste (not shown) onto the upper surface of the substrate P (only a portion of which is visible) 24 is formed through the mask 15, and square holes are formed at two diagonal corners. A through hole 25 is formed.

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. Then, based on the protruding movement of the pistons of the cylinders 32 and 33, the cylinders 32 and 33
By reciprocating along the rail 31, the paste is filled in the screen openings 24, and the paste is transferred to the substrate P, that is, pattern printing is performed.

As shown in FIGS. 3 and 6, a mark forming member PA having the same shape and size as the through hole 25 is attached to a part of the corner of the substrate P so as to correspond to the through hole 25 of the mask 15. , a small square recognition mark PB is formed at its center. In this embodiment, a conductor layer (not shown) such as a terminal is printed on the substrate P before pattern printing using paste, and at the same time, the mark forming member PA is printed using the same material as the conductor layer, and the mark is printed on the substrate P. The recognition mark PB is formed by printing and punching out a square from the center of the forming member PA.

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 the same 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.

Next, the electrical configuration of the printing press will be explained based on FIGS. 1 and 7. A control circuit 51J shown in FIGS. 1 and 7,
The control circuit 51 and the camera 45 constitute an optical recognition device for optically recognizing the mark PB on the substrate P. The control circuit 51 and pulse motors 16, 17, and 18 constitute 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 controls the camera 4.
The analog video signal of No. 5 is converted into a binary signal via the interface 61 and outputted to the image memory 53. The image memory 53 stores a plurality of double-sided images of binary signals, and outputs the image data to a microprocessor (hereinafter simply referred to as MPLJ) 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 9, which will be described later, for controlling the operation of this printing press. A random access memory (hereinafter simply referred to as RAM) 62 temporarily stores position data of the through holes 25 of the mask 15 and the like. Then, the MPU 54 displays a necessary image on the monitor television 4 via the drive circuit 57 based on the input from the camera 45 and the sensor 8 according to the program in the ROM 56, and
The pulse motor 1 via the drive circuits 58, 59, 60
6, 17, and 18 are rotated to move the screen frame 12.

Next, the operation of the printing system configured as described above will be explained with reference to the flowcharts of FIGS. 8 and 9.

As mentioned above, the flowcharts shown in FIGS. 8 and 9 indicate that the MP
Proceed under the control of LJ54. Now, the substrate P that has been conveyed 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゜Note that the following steps (omitted), the screen frame 12 is lowered and the mask 15 approaches and 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 of the through holes 25 of the mask 15 (the position of this through hole is referred to as point A) (83), and then the camera 45 is lowered by the cylinder 44. (S
4). Then, the focus is set on the through hole 25 at point A (S
5), the position of the center of the through hole 25 is calculated (S6).

Note that the center position of the through hole 25 can be determined based on the binarized data. Next, the calculated center position is stored in the RAM 62 as position data (S7).
.

Next, the recognition mark PB on the board P at point A is focused (S8), and its center position is calculated (
S9), which is stored in the RAM 62 as position data (810).

Then, the camera 45 moves to the position of the other through hole 25 of the mask 15 (hereinafter referred to as point B), and focuses on the recognition mark Pa of the substrate P at the point B (
S12>. Then, the center position of the recognition mark PB is calculated (813), and the center position is stored in the RAM as position data.
62 (314). Next, the through hole 25 at point B
(S15), and the through hole 2
5 is calculated (816), and the center position is stored in the RAM 62 as position data (817).

Then, the camera 45 is raised and moved back to the home position H, and the mask 15 registered in advance is
The position data of the through hole 25 in the mask 15 is compared with the position data of the through hole 25 detected by the camera 45.
The position of the through hole 25 of the same max 15 is detected.
The position of the mark PB on the substrate P is compared with the position of the mark PB, the amount of deviation between the substrate P and the mask 15 is calculated, and based on this, it is determined whether there is any deviation (8
19,820). If there is a deviation, at least one of the pulse motors 16, 17, 18 is rotated, and the centers of the through hole 25 of the mask 15 and the recognition mark PB of the substrate P are aligned to correct the deviation. The corrective movement of the mask 15 is performed as follows (S21). In this case, the method of correcting movement of the mask 15 is to linearly move the mask 15 in the X direction and the Y direction by simultaneously rotating the pulse motors 16 and 17 in the same direction or by rotating only the pulse motor 18, and then moving the mask 15 linearly to point A or B. After aligning the center of the through hole 25 with the center of the recognition mark Pa, the pulse motors 16 and 17 are rotated in opposite directions, and the pulse motor 18 is rotated in the forward or reverse direction to remove the mask 15.
There is a method of aligning the center of the other hole 25 at point B or point A with the center of the recognition mark Pa by rotating the center of the hole 25 and the recognition mark PB, which have already been aligned. Another method is to align the directions of the mask 15 and the substrate P by simultaneously rotating the pulse motors 16 and 17 in different directions and rotating the pulse motor 18 in the forward or reverse direction, that is, point A and point B. After that, 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 forward or reverse rotation of the pulse motor 18, and the two-way hole 2 is
There is a method of aligning the centers of 5 and both recognition marks Pa.

After the centers of the two-way hole 25 and the two recognition marks PB are aligned as described above, the process moves to the normal printing process (S22
). If no deviation has occurred in the determination at step 820, step 821 is skipped and the process proceeds to the printing process. In this printing process, the mask 15 and the substrate P are accurately aligned in a predetermined positional relationship by matching the through hole 25 and the recognition mark Pa, so that the paste is placed in an accurate position with respect to the substrate P. transcribed with relation.

In the above, the position of the through hole 25 of the mask 15 and the position of the recognition mark PB of the substrate P are detected at both points A and B, but the center position data of the through hole 25 of the mask 15 is detected every time the mask 15 moves. Therefore, it is not necessary to detect the position of the through hole 25 every time printing is performed, and only the recognition mark PB of the substrate P is detected, and this will be explained below. That is, in FIG. 9, the chuck of the substrate P is confirmed! (831), lowering the mask (
832), after moving the camera 45 from home position 1 to point A (833) and lowering the camera 45 (S34), the detection of the center position of the through hole 25 is omitted and the center position of the recognition mark Pa is detected. Detection is performed (S35 and 836
). Next, the center position is stored in the RAM 62 (83
7), the camera 45 is moved to point B (838), and the center position of the recognition mark Pa is detected again, omitting the position detection of the through hole 25 (S39 and 540), and the center position of the recognition mark Pa is detected.
(841).

After the camera 45 rises and returns to the home position (842), the position data of the KLi mark Pa set in 337.41 and the position data of the through hole 25 set in the previous printing process are The amount of deviation between the substrate P and the mask 15 is calculated based on (S43)
, if it is determined that a deviation has occurred (844),
In the same manner as in the case of FIG. 8, the correction movement of the seven screens 15 for correcting the deviation is performed. Then, since the position of the through hole 25 of the mask 15 is moved by the correction movement of the mask 15, the position data of the through hole 25 is rewritten based on the data of the rotation amount of the pulse motors 16, 17L 18 ( 346). If it is determined that there is no deviation in the determination in S44, the steps in 845 and S
46 is naturally skipped. Then, it is determined whether the number of times of printing has reached the set number of times (847), and if the number of times of printing has not reached the set number of times, the process returns to step S31. If the number of times of printing reaches a set number of times, for example, 50 times, the process proceeds to step S1 in FIG.
After the corrective movement is performed, step 83 in FIG. 9 is performed again.
Proceed to 1.

In other words, each time the mask 15 is corrected, the position data of the through hole 25 is rewritten.
There is almost no risk of WAm occurring when determining the positional deviation between the through hole 25 and the actual through hole 2.
It cannot be said that there will be no deviation between the position of 5.
But every time the number of prints reaches the set number of times? Sufu 15
The position of the through hole 25 is actually detected. Therefore, it is natural that the position of the through hole 25 may be detected every time printing is performed without performing the operation shown in FIG. Compared to the operation, the time required to detect the through hole 25 is only slightly longer, and the overall time is not different from that.

As described above, in the printing method using this printing machine, printing can be performed by accurately aligning the positional relationship between the substrate P and the mask 15 by detecting the recognition mark PB without requiring trial printing. Can be done. Moreover, the alignment between the substrate P and the mask 15 is performed at a printable position where the mask 15 is closely facing the substrate P, and after the position detection, the substrate is transported or the mask is moved in the closing direction. Therefore, it has nothing to do with the mechanical accuracy of the printing machine, the external dimensional accuracy of the board, or the hole accuracy, and the camera is only used to outline the mask from the top to the bottom, and the camera is placed between the mask and the board. There is no need for a mechanism to move the device in and out, so there is no need for high mechanical precision or a complicated configuration. However, 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 printing machine as a whole does not become larger. .

It should be noted that the present invention is not limited to the above embodiments, but may be embodied in the following manner.

(1) Recognition mark Pa on substrate P and through hole 2 on mask 15
5. Change the shape arbitrarily. In short, through hole 25
If the position of the recognition mark PB can be recognized from
The shape of the through hole 25 and the recognition mark P [3 is not limited to a square.

(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) The mask 15 and the substrate P are aligned so that the substrate P is moved 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) The mask 15 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) The configuration is such that one recognition mark Pa is recognized and the deviation correction is performed first, and then the other recognition mark PB is recognized and the deviation correction is performed for the second time.

(6) Make various other changes to the configuration of each part of the printing press 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 the through hole of the mask in a printable state where the mask is close to and facing the substrate, so there is no need for trial printing, etc. This makes it possible to perform printing operations efficiently, and also prevents the need for high mechanical precision, the complexity of the configuration, and the overall size of the printer.

[Brief explanation of the drawing]

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 through hole and the recognition mark, 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 a through hole detection operation, and FIG. 9 is a flow chart not including a through hole detection operation. 15...Mask, 16,17.18...Pulse motor, 24...Screen eye, 25...Through hole, 34...
... squeegee, 45 ... television camera, 51 ... control circuit, the control circuit 51 constitutes a determining means, and the control circuit 5
1 and the television camera 45 constitute an optical recognition device, and the control circuit 51 and the pulse motors 16, 17, and 18 constitute correction means. Patent applicant CKD Co., Ltd. Agent
Patent Attorney On 1) Hironobu Diagram

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 with a squeegee, including forming through holes in the mask; A mark is attached to the substrate corresponding to the through hole, and when the mask is placed close to the substrate in a printable state, the mark is optically recognized through the through hole to determine the positional relationship between the mask and the substrate. A printing method characterized in that, if the positional relationship deviates from a normal one, at least one of the substrate and the 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 having a mask that can be moved into and out of contact with a substrate, and a squeegee that transfers paste onto the substrate through screen openings, the mask has through holes; an optical recognition device for optically recognizing the mark attached to the substrate by the optical recognition device; and a determining means for determining whether or not there is 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 according to the amount of deviation.