JP3218059B2 - Screen printing machine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a screen printing machine, and more particularly to an automatic elimination of a cause of a defect when a defect occurs in printing.

[0002]

2. Description of the Related Art A screen printing machine prints a printing agent at a predetermined position on a plate to be printed, as in the case where an adhesive or cream solder is applied to a position where electronic components are bonded to a printed circuit board or a position where a lead wire is connected. It is a device,
It is known from Japanese Patent Publication No. This screen printing machine includes a printing plate support, a screen support, and a squeegee device, and the squeegee of the squeegee device moves on a screen supported by the screen support, so that the printing plate support is The printing agent is printed on the supported printing plate. The printing agent is printed on the printing plate through small holes formed in the screen while being moved on the screen by the squeegee. In the case where the printing agent is printed on the printing plate in this way, printing may be defective. For example, the printing agent may not be printed at all or some of the printing positions, the printing amount may be insufficient, or the printing position may be shifted. Causes of such printing defects include clogging of the screen with the printing agent in the small holes (hereinafter referred to as clogging of the screen) , shortage of the printing agent, misalignment between the screen and the plate to be printed, and the like. Conventionally, an operator removes the cause of the defect.
They had to clean the screen to remove clogs, replenish the printing agent, and correct the position of the screen.

[0003]

However, it is troublesome for an operator to remove the cause of the defect each time a defect occurs in the printing, and there is a problem that the automation of the screen printing is hindered. In view of the above circumstances, the present invention has a function provided with a function capable of automatically removing at least the causes of a plurality of printing defects including screen clogging and a shortage of printing agent that have occurred during screen printing. It has been made to provide a clean printing machine.

[0004]

SUMMARY OF THE INVENTION According to the present invention, there is provided a screen printing machine comprising a printing plate support, a screen support, and a squeegee device.
(A) a detection device for detecting a printing state of the printing agent to the printing plate, a screen cleaning device which performs screen cleaning to remove the printing agent adhered to (b) a screen, (c) Suki
A printing agent replenishing device for replenishing a printing device with a printing agent; and (d)
As a result of the detection by the detection device, the printing position equal to or more than the first set number
If it is detected that the printing amount of the printing agent is
In this case, the printing material supply device is instructed to supply the printing material, and the
Most of the print positions in the number print successfully,
It is detected that at least a part is not printed at the printing position equal to or less than the second set number that is smaller than the first set number.
And an instruction device for instructing the screen cleaning device to perform an operation when the screen cleaning device is operated.

[0005]

By detecting the printing state of the printing agent on the plate to be printed, it is possible to determine the occurrence of a printing failure and to estimate the cause from the state of the printing failure. That is, if the small holes in the screen are clogged, printing is normally performed at most of the plurality of printing positions, but only a small portion of the printing positions (such as
In other words , printing failures such as no printing at the second set number or less , or missing part of the pattern
Live. Further, when the amount of the printing agent decreases and becomes insufficient, a phenomenon occurs in which the amount of the printing agent printed on the printing plate becomes insufficient. The thickness of the printing agent is insufficient, or the printing pattern is missing. Therefore, in the present invention,
Screen cleaning equipment that automatically cleans the screen
And a printing agent replenishment device that automatically replenishes the printing agent.
Prints more than the first set number as a result of inspection by the detector
Insufficient amount of printing agent is detected at the position
The printing device replenishes the printing agent supply device
Instructions and print successfully in most of the multiple print positions.
However, the number of print positions less than the second
If it is detected that a part is not printed
At the same time, the screen cleaning device was instructed to operate.
It is. In addition, the following equipment should be provided as necessary.
Can be. If there is a misalignment between the screen and the printing plate, there will be a misalignment between the actual printing position and the normal printing position where the printing agent is to be printed. Therefore, the position and the screen of the screen support table on, set <br/> only that the device for automatically correcting the screen support table or the printing plate support position. Then, when the printing position shifts, the correcting device is operated to automatically eliminate the printing position shift.
It is possible. Further, when there are a plurality of causes of failure for one printing failure, a plurality of failure cause removing devices for removing each of the causes of failure may be provided and operated. Even when a plurality of types of printing failures occur at the same time, it is only necessary to operate a device for removing the cause of each failure.

[0006]

[Effect of the Invention] Oite screen printing machine according to the present invention as described above, when the shortage of the printing amount of the printing agent occurs,
Depending on the situation of the shortage, a screen cleaning device
The replenishing device is selectively activated. Accordingly
Printing defects such as screen clogging and insufficient printing agent
This automatically eliminates the cause of the occurrence, reduces the burden on the operator, and facilitates automatic printing of the screen.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail with reference to the drawings, taking as an example the case where the present invention is applied to a screen printer for printing creamy solder on a printed circuit board.

As shown in FIGS. 1 and 2, the screen printing machine of this embodiment includes a screen printing device 10, a substrate conveyor 12, a screen transport device 14, a screen storage device 16, and a screen cleaning device 18. The board conveyor 12 is provided on a bed 22 provided at a fixed position, and has a fixed rail 24 and a movable rail 26 arranged in the X-axis direction (vertical direction in FIG. 1). A rope (not shown) is wound around the inside of each of the rails 24 and 26 endlessly, and a printed board 28 as a plate to be printed is placed on the rope, and the rope is moved to move in the X-axis direction. Conveyed. A plurality of screw shafts 30 are bridged between the fixed rail 24 and the movable rail 26, and the movable rail 26 is moved toward and away from the fixed rail 24 by rotating the screw shaft 30. Are set in accordance with the dimensions of the printed circuit board 28.

[0009] The screen printing apparatus 10 is disclosed in
The configuration is almost the same as that of the screen printing apparatus described in Japanese Patent No. 84871, and will be briefly described. The screen printing apparatus 10 includes a printed board positioning and supporting device 34, a screen positioning and supporting device 36, a squeegee device 38, and a substrate pressing device 40. Among these devices, the substrate holding device 40 is provided on the bed 22 together with the substrate conveyor 12. The board holding device 40 has a board holding plate 42 that is moved in the X-axis direction, and plays a role of holding the printed board 28 from above when the printed board 28 is supported by the printed board positioning and supporting device 34.

Printed circuit board positioning and supporting device 34, screen positioning and supporting device 36, and squeegee device 38
Is provided on a movable table 46 provided on the bed 22 so as to be movable in a Y-axis direction orthogonal to the X-axis direction. When the width of the board conveyor 12 is changed, the movable table 46 is moved in the same direction as the movable rail 26 by a half distance, and when the width of the board conveyor 12 is changed, Y of the printed board positioning support device 34, the screen positioning support device 36, and the squeegee device 38
The center in the axial direction coincides with the center in the Y-axis direction of the board conveyor 12.

The printed board positioning and supporting device 34 is provided so as to be able to move up and down, and has a board supporting base 50 as a printed board supporting base which is raised and lowered to four levels by a multi-stage cylinder (not shown). The substrate supporting base 50 sucks the printed circuit board 28 by vacuum while sandwiching the printed circuit board 28 together with the substrate pressing plate 42, and rises to a position where the cream solder is printed.

The screen positioning support device 36 and the squeegee device 38 are supported by a frame 54 mounted on a movable base 46 so as to be rotatable around an axis parallel to the Y-axis direction. A screen support 56 is provided on the frame 54.
Are fixed, and as shown in FIG. 3, the screen 58 and a screen frame 60 fixed to the peripheral edge thereof are supported. The screen support 56 is a rectangular frame, and two frames parallel to the X-axis direction (vertical direction in the drawing) are provided with two frames on the side opposite to the screen transport device 14.
The two Y-axis direction position setting devices 64 are provided at a distance in the X-axis direction, while the other frame portion has a Y-axis direction pressing device 66 corresponding to the two Y-axis direction position setting devices 64, respectively.
Is provided. Further, among the frame portions parallel to the Y-axis direction (the left-right direction in the figure) of the screen support 56, one X-axis direction position setting device 68 is provided on the frame portion on the frame 54 side, and on the other frame portion. Is provided with an X-axis direction pressing device 70, and these Y-axis direction and X-axis direction position setting devices 64, 68, Y-axis direction, X-axis direction pressing devices 66,
70 constitutes the screen positioning support device 36.

The Y-axis direction position setting device 64 includes a screen 5
8 is set in the Y-axis direction, and as shown in FIG. 4, a positioning lever 72 rotatable about a vertical axis.
It has. The lever 72 is connected to the screen support 56.
And two arm portions 76 and 78 rotatably supported by a bracket 74 fixed to the arm and extending in directions different in phase. Rollers 80 and 82 are rotatably attached to the distal ends of the arms 76 and 78, respectively. The return spring 84 urges the upper arm 76 in a direction away from the screen frame 60, and Arm part 78
Roller 82 is in contact with the tip of the push rod 86.

The push rod 86 is fitted to a block 88 fixed to the bracket 74 so as to be slidable in the X-axis direction, and is screwed to a screw shaft 92 connected to an output shaft of a step motor 90. It is moved in the X-axis direction by the rotation of the step motor 90. Step motor 90
The forward rotation of the push rod 86 advances (FIG. 4).
Is moved to the left), the positioning lever 72 rotates against the biasing force of the return spring 84, and the upper arm 76 approaches the screen frame 60. Step motor 9
With the rotation in the reverse direction of 0, the arm portion 76
To separate from the screen frame 60. Therefore, by appropriately setting the movement position of the push rod 86, the upper arm portion 76,
8 in the Y-axis direction can be set.

As shown in FIG. 3, the Y-axis direction pressing device 66 has a push lever 98 provided on the screen support 56 so as to be rotatable around a vertical axis by a shaft 96. The push lever 98 has a dogleg shape and is connected at one end to the piston rod 102 of the air cylinder 100. The air cylinder 100 is attached to the screen support base 60 so as to be rotatable about a vertical axis, and the push lever 98 is located on the side opposite to the side connected to the piston rod 102 when the piston rod 102 is at the retracted end position. Is located outside the side surface parallel to the Y-axis direction of the screen frame 60 as shown by the solid line, while approaching the screen frame 60 when the piston rod 102 is moved toward the forward end position. The screen frame 6 as shown by the two-dot chain line.
0 engages with the side surface parallel to the X-axis direction of the screen frame 60.
Is pressed against the Y-axis direction position setting device 64, whereby the screen frame 60 is positioned in the Y-axis direction.

The push lever 98 of the Y-axis direction pressing device 66 provided on the downstream side of the screen support 56 in the printed board conveying direction is attached to the upper portion of the shaft 96 and located above the screen support 56. An arm portion 104 and an arm portion 106 attached to a lower portion of the shaft 96 and located below the screen support 56.
As shown by the solid line, when the push lever 98 is rotated to a position where the screen frame 60 is not pressed, the arm portions 104 and 106 move toward the screen transport device 14 in the Y-axis direction of the screen frame 60 (the right side in FIG. 3). , And the movement to the downstream side (downward in FIG. 3) in the printed circuit board transport direction in the X-axis direction.

The X-axis direction position setting device 68 is constructed in the same manner as the Y-axis direction position setting device 64, and a positioning lever 114 having two arm portions 110 and 112 is provided with a step motor 118 for pressing a push rod 116. The screen frame 60 is set in the X-axis direction by being rotated by the forward and backward movements and by the urging force of a return spring (not shown).

As shown in FIG. 5, the X-axis direction pressing device 70 has a
The screen frame 60 is pushed by being rotated by 24. An elongated hole 126 is formed in the screen support 56, and the push lever 122 is attached so as to be rotatable around an axis parallel to the Y-axis direction. One end of the push lever 122 is connected to the air cylinder 12.
4 is rotatably connected to the piston rod 128, and the other end of the push lever 122 projects on the screen support 56 and pushes the screen frame 60 by the expansion and contraction of the piston rod 128.
Is moved from the upper surface to a position retracted into the elongated hole 126.

On the screen support 56, furthermore,
A fixing cylinder 134 is provided at each corner.
These fixing cylinders 134 are provided downward, and when positioning the screen frame 60, the piston rod is at the contracted end position and is separated from the screen frame 60. However, after positioning, the piston rod is extended and the screen frame 60 is extended. It is fixed to the screen support 56. The two fixing cylinders 134 provided on the downstream side (the lower side in FIG. 3) in the transport direction of the printed board 28 are provided at positions where the movement of the screen frame 60 in the same direction is not hindered.

Next, the squeegee device 38 will be described.
As shown in FIG. 1, two guide rods 140 are provided between the frame 54 and a gate-shaped frame 138 erected on a portion of the screen support 56 opposite to the frame 54. And the slide 14
2 are slidably fitted. A squeegee unit 144 shown in FIG. 6 is attached to the slide 142 so as to be able to move up and down, and is moved up and down by a raising and lowering cylinder 146 between a position where the cream solder is printed in contact with the screen 58 and a position separated from the screen 58. Let me do. The slide 142 is screwed to the feed screw 148 with a nut 147, and the feed screw 148 is
, The slide 142 is moved, and the squeegee unit 144 is linearly reciprocated in the X-axis direction.

As shown in FIG. 6, the squeegee unit 144 includes a stirrer 154 that is long in the width direction of the screen 58,
And a syringe 158 in which the creamy solder 156 is accommodated. The syringe 158 is a casing 1 of the stirrer 154.
60 and is detachably attached to the casing 16.
0, the creamy solder 156
Flows into the casing 160 by the low-pressure nitrogen gas supplied into the syringe 158 and its own weight. A float 162 floats on the cream solder 156. The float 162 is formed by fitting an iron ring 164 around the outer periphery of a disk made of synthetic resin, and the ring 164 is detected by a first magnetic switch 166 provided outside the syringe 158, whereby the cream-like shape in the syringe 158 is formed. It is detected that the amount of the solder 156 has reached the lower limit amount. Outside the syringe 158 is also the first magnetic switch 1
A second magnetic switch 168 is provided at a position above 66 so as to detect that the amount of the creamy solder 156 in the syringe 158 has reached the upper limit.

Further, the syringe 158 is connected to a creamy solder replenishing device 172 by a hose 170. The cream-like solder replenishing device 172 is
The cream-like solder placed on the top 2 is constantly stirred by a stirrer to maintain a viscosity suitable for printing. This creamy solder replenishing device 172
Automatically supplies creamy solder to the syringe 158 based on the supply command.

The casing 160 of the agitator 154 is rotatably attached to a frame (not shown) which is raised and lowered by a lifting cylinder 146. Casing 1
A shaft 176 is rotatably accommodated in the shaft 60, and a stirring roller 178 is eccentrically attached to the shaft 60.
When the shaft 176 is rotated by a drive motor (not shown), the agitating roller 178 rotates to agitate the cream-like solder 156 in the casing 160 and maintain the viscosity suitable for printing. An opening 180 is provided on the lower surface of the casing 160.
Is formed, and a pair of rubber squeegee members 1 are formed.
82 are attached to form a discharge port 184. These squeegee members 182 are such that the casing 160
6, the squeegee member 182 on the upstream side contacts the screen 58 in the moving direction of the squeegee unit 144, and the squeegee member 182 on the downstream side slightly moves from the screen 58 in the moving direction of the squeegee unit 144. It is assumed to be in a raised state.

The screen 58 needs to be replaced when the type of the printed circuit board 28 is changed. At the time of screen replacement, the screen 58 is
4, the screen is pulled out from the screen support 58 and is stored in the screen storage device 16, and another screen 58 is taken out of the screen storage device 16 and positioned on the screen support 56.

The screen transport device 14 has an X-axis slide 188 that moves in the X-axis direction, and a Y-axis slide 190 provided on the X-axis slide 188 so as to be movable in the Y-axis direction. The X-axis slide 188 is slidably fitted to a pair of guide rails 192 arranged in the X-axis direction, and is screwed to a ball screw 194. By being rotated by 196, it is moved in the X-axis direction.

A guide rail (not shown) and a ball screw (not shown) are provided on the X-axis slide 188 in the Y-axis direction, and the Y-axis slide 190 is rotated by the Y-axis direction driving motor 198 to rotate the Y-axis slide 190. Moved in the axial direction. The X-axis slide 188 is also provided with a plate-shaped guide member 200 parallel to the Y-axis direction.

The Y-axis slide 190 has a long shape extending in the Y-axis direction, and engagement members 202 and 204 having a U-shaped cross section are attached to the lower surface of the tip. The engaging member 202 is lowered by the lowering cylinder 206 and is urged upward by a spring (not shown), and the pair of U-shaped side walls is attached in a direction parallel to the X-axis direction. The engaging member 204 is also moved up and down by the lowering cylinder 208 and the spring in the same manner as the engaging member 202, but a pair of U-shaped side walls are attached in a direction parallel to the Y-axis direction.

On the rear end side of the Y-axis slide 190,
An engagement pin 212, an engagement member 214 having a U-shaped cross section, and a support member 216 are attached. Engaging member 214
Are mounted so that a pair of U-shaped side walls are parallel to the Y-axis direction.
14 is raised and lowered by a lowering cylinder and a spring. Further, the support member 216 is provided in parallel with the X-axis direction.

Further, a laser displacement sensor 220 is attached to the tip of the Y-axis slide 190. As shown in FIG. 7, the laser displacement sensor 220 emits a laser beam emitted from a laser beam generator 222 to a projection optical system 224.
And irradiates the cream-like solder 156 printed on the printed circuit board 28 with the reflected light.
6, the light is focused on the semiconductor position detecting element 228, and the reflected light focusing position is calculated by the analog processing circuit 230. Cream solder 156
Since the light condensing position on the semiconductor position detecting element 228 changes depending on the height of the solder paste, the position on the printed circuit board 28 where the cream solder 156 is printed and its height can be determined by calculating the light condensing position.

The screen accommodating device 16 has a screen accommodating portion 236 provided in two stages in a casing 234 thereof.
As the casing 234 is raised and lowered by the lifting cylinder 238, the casing 234 is alternatively positioned at the screen transfer position. Automatic screen replacement is described in
This is similar to the screen printing machine described in JP-A-317768, and will be briefly described.

When the screen 58 is replaced in accordance with the change of the type of the printed circuit board 28, the Y-axis slide 190
Is engaged with the screen frame 60 and the screen frame 60 is pulled out from the screen support base 56 by approximately half the length in the Y-axis direction. The screen frame 60 is pulled out from the screen support 56 while being guided by the guide member 200. When the X-axis slide 188 is moved in that state, the screen frame 60 is pushed by the guide member 200 and moved toward the screen storage device 16 by a distance of about half the length in the X-axis direction. The screen frame 60 is accommodated in the upper screen accommodating portion 236 by the engagement member 214 being engaged with the screen frame 60 and moving in the X-axis direction. Then, the lower screen accommodating portion 236 is positioned at the screen transfer position, and the screen 58 to be used next is conveyed onto the screen support 56 in the reverse procedure to the case where the screen 58 is accommodated, and positioned. Used for screen printing.

Next, the screen cleaning device 18 will be described. The screen cleaning device 18 is provided on the downstream side (the lower side in FIG. 1) of the screen printing device 10 of the bed 22 in the transport direction of the printed circuit board 28. As shown in FIG. 1, a pair of guide rails 248 is provided above the substrate conveyor 12 and the screen cleaning device 18 of the bed 22, and serves as a guide when the screen frame 60 is lowered from the screen support 56.

The screen cleaning device 18 is provided with a width slightly smaller than the width when the fixed rail 24 and the movable rail 26 of the board conveyor 12 are opened to the maximum.
As shown in FIG. 2, the bed 22 includes a lifting table 250 that can be raised and lowered. Four guide rods 252 are fixed to the lower surface of the elevating table 250 and slidably fitted to a bush 254 provided in the bed 22.
The piston rod 258 of the lifting cylinder 256 housed in the bed 22 is connected to the piston rod 258.
The elevating table 250 is moved up and down by the expansion and contraction of 58.

On the lift 250, a pair of guides 2
62 are provided in a direction extending in the X-axis direction,
4 are slidably fitted. Slide 264 is shown in FIG.
As shown in FIG. 5, a nut 268 (see FIG. 2) is screwed to a ball screw 266 provided on the elevating table 250, and the ball screw 266 is rotated by a drive motor 270 to move the slide 264 in the X-axis direction. It is moved to. On this slide 264, a brush 274 long in the Y-axis direction is attached by a shaft 276 so as to be rotatable around an axis parallel to the Y-axis direction.

As shown in FIG. 2, the shaft 276 is rotated by the rotation of a rotation driving motor 280 transmitted by a pulley fixed to one end thereof, a belt 278, or the like.
As shown in FIGS. 8 and 9, a solvent ejection nozzle 284 and a solvent supply device 286 are provided on the slide 264, and the solvent for dropping the creamy solder 156 is sprayed from the solvent ejection nozzle 284 by the principle of spraying. At the screen 58. A vacuum suction unit 290 is further provided on the slide 264 along the brush 274. Vacuum suction device 2
Numeral 90 is connected to a vacuum device 292 (see FIG. 10), and sucks the creamy solder 156 attached to the brush 274 by supplying the vacuum.

This screen printing machine is controlled by a control device 300 shown in FIG. This control device 300
Is mainly composed of a computer having a CPU 302, a ROM 304, a RAM 306 and a bus 308 connecting them. An input interface 310 is connected to the bus 308, and the first and second magnetic switches 16 are connected to the bus 308.
6, 168 and the laser displacement sensor 220 are connected. The bus 308 also has an output interface 312
Are connected, and drive circuits 316, 318, 320, 32
2,324,326,328,330,332,33
4, 336, 338 and 340, step motors 90 and 118, fixing cylinders 134, pressing cylinders 100 and 124, solder replenishing device 172, elevating and lowering cylinders 256, moving motors 270, rotation driving motors 28
0, solvent supply device 286, vacuum device 292, X-axis direction driving motor 196, Y-axis direction driving motor 198
Is connected. In addition, in addition to these, a motor for driving the screen printing apparatus 10 and the board conveyor 12 and the like are connected, but here, only those closely related to the description of the present invention are illustrated, and connection of other members is illustrated. Is omitted from the drawing.

Next, the operation will be described. At the time of screen printing, a screen 58 used for screen printing is positioned on the screen support 56 and the substrate conveyor 12
Is adjusted to a size corresponding to the width of the printed circuit board 28. Then, when the printed board 28 is transported to a position directly below the screen 58 by the board conveyor 12, the printed board 28 is positioned and supported by the board support table 50, raised to the printing position, and brought into close contact with the lower surface of the screen 58. In this state, the squeegee unit 144 is moved, and the creamy solder 156 is attached to the printed circuit board 28 via the screen 58.
Is printed, and after the printing is completed, the printed circuit board 28 is printed.
Is lowered to be separated from the screen 58, carried out to the downstream side of the screen printing apparatus 10 by the board conveyor 12, and the printing state of the creamy solder 156 is detected by the laser displacement sensor 220 at that position. The movement of the X-axis slide 188 and the Y-axis slide 190 of the screen transfer device 14 causes the laser displacement sensor 220 to move all over the printed circuit board 28 to detect the position and height of all the printed cream solder 156. It is.

This detection result is supplied to the control device 300. If there is a defect in the printing state, the control device 300 removes the cause of the defect by using the screen cleaning device 18, the screen positioning support device 36, and the creamy solder replenishment. Instruct the device 172 to operate. In the control device 300, first, the cream solder 156 is printed at all the printing positions, the distribution of the positions where the cream solder 156 is printed, the cream solder 156 at each printing position.
6, the distribution of the amount of the creamy solder 156, and the printing position of the creamy solder 156 are checked. The amount of the creamy solder 156 is determined from its height.

Based on the result of the examination, if there is a defect in the printing state, the cause thereof is obtained, and an operation instruction is issued to the device for eliminating the cause. Although most of the printing positions are normally printed, only a few printing positions (second setting)
If at least a portion is not printed at the printing position (less than or equal to the constant) , the cause is a clogged hole in the screen 58 and the screen cleaning device 18 is operated. First, the screen frame 6 by the fixing cylinder 134 is used.
0 is released, and the pressing of the screen frame 60 by the pressing devices 70 and 66 in the X-axis direction and the Y-axis direction is released.
88 and the Y-axis slide 190 are moved so that the engagement member 204 is engaged with a frame portion of the screen frame 60 parallel to the Y-axis direction. The movement of the X-axis slide 188 causes the screen frame 60 to be moved by the guide rail 248. It is guided and pulled out of the screen support 56 onto the screen cleaning device 18.

In this state, after the board conveyor 12 is spread to the maximum distance, the lift 250 is raised and the brush 2
74 is brought into contact with the lower surface of the screen 58 and the brush 2
74 is moved along the screen 58 by the slide 264 while being rotated, and the creamy solder 156 clogged in the small hole of the screen 58 is removed. At this time, the solvent is ejected from the screen 5 by the solvent ejection nozzle 284.
8, the cream-like solder 156 attached to the screen 58 is removed, and the cream-like solder 156 attached to the brush 274 is sucked by the vacuum suction device 290, and the cream-like solder 156 clogged in the small hole of the screen 58 is removed. Cleanly removed.

When the printing amount of the cream solder 156 at the printing position equal to or more than the set number (first setting number) is smaller than the normal amount, the cream solder 15 in the syringe 158 is not used.
6 was reduced, and the creamy solder replenishing device 1
An operation command is issued to 72, and creamy solder 156 is supplied to the syringe 158. This replenishment is performed at such a small pressure that the creamy solder 156 is not discharged from the discharge port 184 until the ring 164 of the float 162 is detected by the second magnetic switch 168.

When the shortage of the cream solder 156 in the syringe 158 is detected by the first magnetic switch 166, the cream solder 156 is supplied by the cream solder replenishing device 172 based on the detection. However, the failure of the first magnetic switch 166 or the control device 3
00, a lack of cream solder 156 is not detected, or even if it is detected,
6 may not be replenished. In this case, the shortage of the creamy solder 156 is detected based on the printing state on the printed circuit board 28 as described above, and the creamy solder 156 is supplied based on the detection, so that printing is continued without any trouble. be able to. The occurrence of an abnormality in the first magnetic switch 166 or the control device 300 is determined by the first magnetic switch 1
Because the cream-like solder 156 is supplied and the second magnetic switch 168 emits a signal even though the signal is not supplied from 66, or the cream-like solder 156 is supplied based on the detection of the printing state. understand,
By storing this information, it is possible to use it for abnormality diagnosis and maintenance of the apparatus.

Further, when the printed position of the cream solder 156 is shifted from the normal position, the position of the screen 58 is corrected. In this case, screen 5
8, the correction direction and the correction amount of the position 8 are calculated. First, the fixing of the screen frame 60 by the fixing cylinder 134 and the pressing by the pressing devices 66 and 70 are released, and then the step motors 90 and 118 are activated and the positioning lever 7
The positions of 2,114 are corrected. After correction, X axis direction, Y
The axial pressing devices 70, 66 allow the screen frame 60
Is pressed and pressed against the positioning levers 72 and 114, whereby the position of the screen 58 is corrected to a position where the cream solder 156 is printed on the printed circuit board 28 without shifting. Each position setting device 6 in X-axis direction and Y-axis direction
8, 64 and each pressing device 70 in the X-axis direction and the Y-axis direction,
66 functions as a screen position correcting device for automatically correcting the position of the screen 58 on the screen support 56.

Furthermore, when a solder bridge is generated in which the cream solders 156 printed at different printing positions are connected to each other, one of the causes is dirt on the back surface of the screen 58, and the screen 58 is cleaned. The cause of this case is a change in the viscosity or the material of the creamy solder 156. If the generation of the solder bridge is not eliminated by cleaning the screen 58, the occurrence of the defect is notified to the operator, and the operator prints. The condition and the creamy solder 156 are checked.

As is apparent from the above description, in the present embodiment, the cream-like solder replenishing device 172 is provided with the printing agent supplement.
A screen cleaning device 18, a screen positioning support device 36, and a creamy solder replenishing device 172.
Respectively constitute a defect cause removing device, the laser displacement sensor 220 constitutes a detecting device, and the control device 300 constitutes an indicating device.

In the above embodiment, the printing state of the creamy solder is detected by the laser displacement sensor 220, but may be detected by using a CCD camera. The CCD camera may obtain an image in a plane, or may obtain an image in a line. In this case, it is desirable to use a color CCD camera to distinguish between the printed circuit board 28 and the creamy solder 156.

In the above embodiment, the cream displacement solder 156 printed at all the printing positions is detected by moving the laser displacement sensor 220. However, a portion may be picked up and detected. Alternatively, after moving the laser displacement sensor 220 substantially above the printing position, the cream-like solder 156 may be detected by changing the irradiation direction of the laser beam.

Further, in the above embodiment, the screen cleaning device 18 applies a solvent to the screen 58 to
Although the cream-like solder 156 is supposed to be removed at 74, the cream-like solder 156 may be removed by applying a solvent and then pressing the roll of paper or cloth against the screen 58 with a sponge roller. Alternatively, the creamy solder 156 may be removed without applying a solvent.

The defect cause removing device is not limited to the screen cleaning device 18, the screen positioning and supporting device 36, and the creamy solder replenishing device 172, but may be any device capable of automatically removing the cause of printing failure.

In addition, without departing from the scope of the claims, the present invention can be implemented in various modified and improved embodiments based on the knowledge of those skilled in the art.

[Brief description of the drawings]

FIG. 1 is a plan view schematically showing a screen printing machine according to an embodiment of the present invention.

FIG. 2 is a side view showing a screen printing device and a screen cleaning device of the screen printing machine.

FIG. 3 is a plan view showing a screen positioning support device of the screen printing device.

FIG. 4 is a front sectional view showing a Y-axis direction position setting device of the screen positioning and supporting device.

FIG. 5 is a front view showing an X-axis direction pressing device of the screen positioning and supporting device.

FIG. 6 is a front sectional view showing a squeegee unit of the screen printing apparatus.

FIG. 7 is a diagram illustrating the principle of a laser displacement sensor that detects creamy solder printed on a printed circuit board.

FIG. 8 is a plan view showing the screen cleaning device.

FIG. 9 is a front view of the screen cleaning device.

FIG. 10 is a block diagram of a control device for controlling the screen printing machine.

[Explanation of symbols]

 REFERENCE SIGNS LIST 10 screen printing device 18 screen cleaning device 28 printed board 36 screen positioning and supporting device 38 squeegee device 50 substrate support 56 screen support 58 screen 64 Y-axis position setting device 66 Y-axis pressing device 68 X-axis position setting device 70 X-axis direction pressing device 156 Creamy solder 172 Creamy solder replenishing device 220 Laser displacement sensor 274 Brush 300 Control device

Continuation of the front page (56) References JP-A-2-60748 (JP, A) JP-A-55-2041 (JP, A) JP-A-1-209140 (JP, A) JP-A-3-193449 (JP) , A) (58) Field surveyed (Int. Cl. ⁷ , DB name) B41F 15/08

Claims (1)

(57) [Claims] 1. A printing plate support, a screen support, and a squeegee device. The squeegee of the squeegee device moves on a screen supported by the screen support. Of the supported printing plate
A screen printing machine for printing a printing agent such as an adhesive or cream solder at a plurality of positions, a detection device for detecting a printing state of the printing agent on the printing plate, and a screen for removing the printing agent attached to the screen. A screen cleaning device for cleaning and a printing agent replenishing device for replenishing the squeegee device with printing agent
And the result of the detection by the detection device, the printing of the first set number or more
Insufficient amount of printing agent is detected at the position
Command to supply the printing agent to the printing agent supply device
And, to be printed normally in most of the plurality of print position, at least a portion in <br/> printing position below the first set is smaller than the number the second set number is not printed
An instructing device for instructing the screen cleaning device to operate when it is detected .