JPH0423344Y2 - - Google Patents

Description

[Detailed Description of the Invention] Technical Field The present invention relates to a screen printing machine that prints adhesive or creamy solder on a predetermined portion of a printed circuit board, and particularly relates to improving printing accuracy.

2. Description of the Related Art It is widely practiced to construct an electronic circuit by attaching chip-shaped circuit components to a printed circuit board on which a wiring pattern is formed. To do this, adhesive is applied in spots to predetermined areas on the printed circuit board, and the lead wires of the circuit components are soldered to the wiring pattern while the circuit components are temporarily attached to the printed circuit board using the adhesive. However, a screen printing machine is used as one device for applying this adhesive. In addition, creamy solder is applied to the wiring pattern in advance and the lead wires of circuit components are soldered to the wiring pattern using the creamy solder. A screen printing machine is used.

This screen printing machine includes a substrate support stand, a squeegee, a screen whose peripheral portion is fixed to a screen frame, and a screen support stand that supports the screen in the screen frame, and the squeegee moves over the screen. In particular, it prints adhesive or creamy solder on a predetermined portion of a printed circuit board supported on a board support stand, and the screen printing machine described in JP-A-62-84588 is an example of this. .

The screen used for screen printing includes
Broadly speaking, there are mesh screens, metal screens, and combination screens. A mesh screen is a mesh made of Tetron, nylon, silk, etc., with synthetic resin coating or metal coating applied on both sides, leaving transparent areas of adhesive or creamy solder in predetermined areas, and is inexpensive. However, there are problems with low durability and printing accuracy. In addition, metal screens are made of a thin plate of metal such as stainless steel or copper with transparent parts such as adhesives provided at predetermined locations, and are excellent in durability, precision, and sharpness of printing, but they are not suitable for continuous printing. There is a problem with bad sex. On the other hand, in a combination screen, the central part where the transparent part of adhesive and creamy solder is formed is made of metal, and the part fixed to the surrounding screen frame is made of elastic cloth, film, etc.
It is formed from mesh, etc., and has high durability, precision, and long-lasting clarity, and the supported part is highly elastic, so when separating the printed circuit board and screen, there is a gap between the two. Since air can easily enter and the screen can be easily separated from the printed circuit board, it has the advantage of being able to print with high definition.

Problems to be Solved by the Invention In the above-mentioned screen printing machine, there was a problem that the screen shifted during printing, resulting in a decrease in printing accuracy. When the squeegee moves, a load is applied to the screen in the direction of the movement, causing misalignment. In particular, in mesh screens and combination screens, the mesh part is highly elastic, so the screen tends to shift even if the screen frame does not shift. For example, in a combination screen, a shift of about 0.05 to 0.15 mm occurs. It's not uncommon. On the other hand,
For example, flat package ICs, which have become increasingly popular in recent years, have multiple leads around the main body, and are attached to a printed circuit board using the leads, but the lead spacing is 0.45~
Since it is extremely narrow at 0.65 mm, even a deviation of the above degree has a large effect, so it is necessary to print with high precision.

Since the metal screen has low elasticity, it is difficult for the metal screen to shift, but even so, if the screen frame is allowed to move slightly relative to the screen support, it may shift as the squeegee moves.

Means for Solving the Problems In order to solve the above problems, the present invention provides a screen printing machine including the substrate support, the squeegee, a screen, a screen frame, and a screen support, in which a printed circuit board of the substrate support is provided. A plurality of nozzles each having a suction surface that is discontinuous with the substrate support surface and that suctions a portion inside the screen frame of the screen is disposed on the side of the substrate support surface that supports the screen.
These nozzles are connected to a vacuum source.

Function and Effect If the part of the screen inside the screen frame is attracted to the suction surface in this way and the horizontal position of the screen relative to the board support is fixed, the horizontal position relative to the printed circuit board supported by the board support is fixed. Since it is fixed, there is no fear that the screen will shift relative to the printed circuit board even if a load is applied when the squeegee moves, and printing can be performed with high precision.

Furthermore, in the present invention, since the screen is suctioned by vacuum, all kinds of conventionally used screens can be suctioned. It is also possible to attract the screen by magnetic force, but in that case it is necessary that the screen be made of a magnetic material. When adsorbing with a vacuum, there are no such restrictions on the material, and all types of screens can be adsorbed.

Moreover, in the present invention, the nozzles that attract the screen are provided on the sides of the substrate support surface of the substrate support base, and these suction surfaces are discontinuous with the substrate support surface, so that the adhesive and creamy solder are Intrusion into the gap between the screen and the printed circuit board or the gap between the printed circuit board and the substrate support can be effectively avoided.

When the substrate support surface itself is used as the suction surface, or when the suction surface and the substrate support surface are separate but continuous, the vacuum generated in the gap between the back surface of the screen and the suction surface is The vacuum spreads into the gap between the back side of the screen and the front surface of the printed circuit board, and the gap between the back side of the printed circuit board and the board support surface, and this vacuum sucks adhesive, etc. from the transparent part of the screen, causing it to leak into the printed circuit board. This causes inconveniences such as adhesion to the surface, lowering printing accuracy, and staining the back side of the screen and substrate support surface, but this inconvenience can be avoided in the present invention.

Embodiments Hereinafter, embodiments of the present invention will be described in detail based on the drawings.

The printed circuit board screen printing machine shown in FIGS. 4 and 5 includes a printed circuit board positioning and supporting device 1.
0, a screen positioning support device 12, a squeegee device 14, a substrate conveyor 16, and a substrate holding device 17.

The substrate positioning support device 10 includes a substrate support stand 18
The screen positioning support position 12 positions the screen 24 and the screen frame 26 fixed to the periphery thereof on the screen support stand 22. This is what we support. The squeegee device 14 moves a squeegee 28 up and down between a lowered position where it contacts the screen 24 and an upper position, and also moves it in a linear direction along the screen 24. The substrate conveyor 16 functions as a substrate conveyance device,
The printed circuit board 20 is guided by a fixed rail 30 and a movable rail 32, and is carried into between the board support stand 18 and the screen 24 by a pair of endlessly wound ropes 33, and carried out from there. It is something. Then, the board holding device 17 holds the printed circuit board 20 placed on the board support stand 18 using a board holding plate (generally a board holding member).
34 to press against the substrate support stand 18.

Of the above devices, the substrate conveyor 16 and the substrate holding device 17 are fixed to the bed 36 by a plurality of support legs 35, as is clear from FIG. The device 12 and the squeegee device 14 are installed on a movable base 38 that is movable with respect to the bed 36. The movable table 38 is supported by two guide rods 40 arranged parallel to each other on the bed 36 so as to be movable in the left-right direction in FIG. 4 and in the direction perpendicular to the plane of the paper in FIG. Further, the screen positioning support device 12 and the squeegee device 14 are always in a state of covering the upper part of the substrate positioning support device 10, the substrate conveyor 16, and the substrate holding device 17, but the space above them can be opened by rotation. It's like that. Screen positioning support device 12 and squeegee device 1
A frame 42 supporting 4 is rotatably attached to a pair of columns 44 erected on a movable base 38 by a shaft 46, and is connected to a connecting portion 47 by an actuator (not shown). It can be rotated. The end of the frame 42 remote from the axis 46 is supported by a column 50 via an adjustment screw 48, thereby connecting the screen positioning support device 12, the squeegee device 14, the substrate positioning support device 10, the substrate conveyor 16, and the substrate. The height relative to the presser support device 17 can be adjusted.

Hereinafter, the configuration of each part of this screen printing apparatus will be explained in detail.

(Substrate positioning support device) As is clear from FIG. 5, the substrate positioning support device 10 includes a height adjustment device 60 on the movable base 38
It is equipped with a support plate 62 placed through the support plate 62. That is, there are a plurality of guide locks 6 on the movable base 38.
A cam follower 66 is provided on the upper surface of the support plate 62 and has a slope corresponding to the slope. A total of four support plates 67 are provided, two for each cam rod 66, so that the height of the support plate 62 can be adjusted as the cam rod 66 moves in the longitudinal direction. . The two cam rods 66 are connected by a connecting rod 68, and a feed screw 70 parallel to the cam rod 66 is threaded onto the connecting rod 68, and the handle is engaged with the feed screw 70 to rotate. By doing so, the two cam rods 66 can be moved integrally. In addition, the support plate 6
Two guide tubes 72 are fixed to 2 in a posture extending in the vertical direction. Each guide tube 72 is slidably fitted into another guide tube 74 fixed to the movable table 38 to guide the vertical movement of the support plate 62. A spring 76 is disposed between them, and by pulling the support plate 62 toward the movable table 38, the guide lock 64,
The cam rod 66 and the cam follower 67 are kept in close contact with each other to accurately maintain the support plate 62 at a predetermined height.

A rod 78 is slidably fitted into each guide cylinder 72 fixed to the support plate 62, and a longitudinal mounting member 80 extending along the moving direction of the squeegee 28 is fixed to the upper end of the rod 78. ing. Board supports 18 corresponding to printed circuit boards 20 of various sizes are selectively attached to this mounting member 80. A piston rod 84 of a multi-stage cylinder 82 attached to the support plate 62 is fixed to the mounting member 80, and the mounting member 80 and the substrate support stand 18 can be moved to four height positions, namely, a rising end position, a first intermediate position, and a second position. It is adapted to be moved to an intermediate position and a lowering end position. Each of these positions is detected by a proximity switch 86 fixed to the mounting member 80 and four detected objects 88 fixed to the support plate 62.

As is clear from FIG. 4, the substrate support stand 18 is provided with a large number of suction holes 90 on the upper surface, which is the substrate support surface.
Each suction hole 90 is connected to the substrate support 18 and the mounting member 8.
The suction pipe 92 passes through the suction passage formed inside the
By connecting this suction pipe 92 to the vacuum device via a switching valve (not shown), the board support stand 18 is connected to the printed circuit board 2.
0 is adsorbed and held using negative pressure.

(Screen positioning support device) The screen support stand 22 of the screen positioning support device 12 is constituted by a part of the rotatable frame 42. Screen support stand 2
As is clear from FIG. 5, a positioning block 100, a dial gauge 102, and a fixed cylinder 104 are provided on the cylinder 2. The screen support base 22 is a rectangular frame body, and two positioning blocks 100 are disposed on the screen support base 22 along one side, and one positioning block 100 is disposed along the other side perpendicular to the one side. Positioning block 10
0 is placed. Adjustment bolts 106 are screwed into the portions of the screen frame 26 facing each positioning block 100 in a posture perpendicular to each side of the screen frame 26.
A dial gauge 102 is attached to a portion adjacent to the portion that comes into contact with each adjusting bolt 106 of 00.

Therefore, with the adjusting bolt 106 in contact with the positioning block 100, adjust the adjusting bolt 1 while watching the indication on the dial gauge 102.
By rotating the screen frame 26, the position of the screen frame 26 can be adjusted accurately. After the adjustment is completed, the fixed cylinder 104 is operated to fix the screen frame 26 to the screen support base 22, and the numerous small holes formed in the screen 24 become areas on the printed circuit board 20 to which creamy solder is to be applied. It can be fixed in an exact match. Once the position is adjusted in this way, even if the screen frame 26 is removed from the screen support stand 22, the adjustment bolts 106 remain fixed to the screen frame 26, so next, move the screen frame 26 to the screen support stand. 22, there is no need to perform adjustment work, which improves the efficiency of setup change work.

If the printed circuit board 20 is large and the difference from the screen frame 26 is small, the screen 24 is a metal screen, but if the printed circuit board 20 is small, it is a combination screen. As shown in Figure 3, screen 2
4, a portion larger by a certain amount than the printed circuit board 20 is a metal portion 108 formed of a thin plate of stainless steel or copper;
The area around 8 is a mesh part 109 in which both sides of the Tetron mesh are coated with synthetic resin, and the mesh part 109 is fixed to the screen frame 26 at its outer periphery.

(Squeegee device) The squeegee device 14 includes two guide rods 110 disposed horizontally and parallel to each other on the rotatable frame 42, and the guide rods 110.
A slide 112 that slides on the top of the slide 112 is provided. As is clear from FIG. 4, the slide 112 is provided with two pairs of guide tubes 114 separated by a distance in a direction perpendicular to the direction of movement of the slide 112. A mounting member 118 is fixed to the lower ends of the two rods 116 that are vertically slidably fitted into each pair of guide tubes 114.
A squeegee 28 is removably attached to. Each mounting member 118 is raised and lowered by a lifting cylinder 120 shown in FIG. 4, thereby moving the squeegee 28 to a lowered position in contact with the screen 24 and a raised position away from it. A nut 122 is fixed to the slide 112, and a feed screw 124 is attached to the frame 42 so as to be rotatable but immovable in the axial direction.
When both are screwed together and the feed screw 124 is rotated by the servo motor 126, the squeegee 28 is reciprocated linearly along the screen 24.

(Substrate Conveyor) As is clear from FIG. 4, the substrate conveyor 16 includes, in addition to the fixed rail 30 and the movable rail 32, a frame 130 parallel to these. A plurality of rail feed screws 132 are rotatably but immovably spanned in the axial direction. These rail feed screws 132 are screwed into rail nuts 133 fixed to the movable rail 32 at a distance in its longitudinal direction and at right angles to the longitudinal direction. All rail lead screws 132 are connected to sprockets 134 and chain 1 shown in FIG.
35, so that they can be rotated by the same amount in the same direction. Therefore, by rotating one rail feed screw 132, the movable rail 32 is moved toward or away from the fixed rail 30 while maintaining an attitude parallel to the fixed rail 30, and the substrate conveyor 16 width can be easily changed.

The rope 33 that supports and conveys the printed circuit board 20 is guided by guide members 136 and 138 fixed to the fixed rail 30 and movable rail 32, respectively, and is driven by a drive pulley attached to a motor (not shown). It's becoming like that. When the printed circuit board 20 carried in by the rope 33 reaches a position directly above the board support stand 18, it is stopped by a stopper device 140 shown in FIG. The stopper device 140 includes a lifting cylinder 142 attached to the support plate 62.
In the raised position, this stopper member 144 comes into contact with the front end of the printed circuit board 20 to prevent further advancement, and in the lowered position, the printed circuit board 20 is prevented from further advancing. is allowed.

The printed circuit board 20 stopped by the stopper device 140 is accurately positioned by the positioning pins 146 shown in FIG. The positioning pins 146 are provided at two locations apart from each other in a direction parallel to the board surface of the printed circuit board 20, and are used to position the printed circuit board by fitting into positioning holes formed in the printed circuit board 20. It is always in the lowered position and is raised as the substrate support stand 18 is raised. That is, the positioning pin 146 is biased in the upward direction by a spring 148, and a protrusion 150 fixed to the positioning pin 146 is engaged with the lower end of the substrate support 18, so that the substrate support 18 is in the lowered position, the positioning pin 146
is also in a lowered position where it does not fit into the positioning hole of the printed circuit board 20. In addition, the positioning pin 14
6 being raised and fitted into the positioning hole of the printed circuit board 20 is detected by a proximity switch 152 shown in FIG.

(Movable Rail, Movable Platform Moving Device) As the width of the substrate conveyor 16 is changed, the movable platform 38 can be moved by one-half distance in the same direction as the movable rail 32. As mentioned above, the movable rail 32 is moved by the rail feed screw 132, rail nut 133, sprocket 134, and chain 135, but these are further connected to the movable base feed screw 168 by the sprocket 162, chain 164, and sprocket 166. has been done. The movable table feed screw 168 is rotatably but immovably supported in the axial direction by the bed 36, and a handle 170 is fixed to one end thereof. Movable base feed screw 16
8 is screwed into a movable base nut 172 fixed to the movable base 38 in a position parallel to the rail nut 133. The rail feed screw 132 and the movable table feed screw 168 have the same pitch, but the diameter of the sprocket 166 is different from that of the sprocket 134.
Since the rotation transmission mechanism consisting of the chains 162, 166 and the chains 135, 164 is supposed to transmit rotation at twice the speed, when the movable base feed screw 168 is rotated by the handle 170, the rail feed The screw 132 is rotated at twice the speed and eventually the movable rail 32 is rotated as shown in FIG.
is moved by a distance, the movable base 38 will be moved by /2 in the same direction.
In this embodiment, a moving device that moves the movable rail 32 and the movable base 38 in conjunction with each other is provided by the rotation transmission mechanism, the rail feed screw 132, the rail nut 133, the movable base feed screw 168, and the movable base nut 172. It is composed of

(Screen holder) As shown in FIG. 6, a screen holder 182 is fixed to the movable rail 32 by a support member 180, and together with a screen holder 186 fixed to the fixed rail 30 by a support member 184, the screen The support member 180 supports the middle part of the rail feed screw 13 from below.
Support plate 6 via guide rod 188 parallel to 2
2, and the difference in the amount of movement between the movable rail 32 and the movable base 38 is allowed by the sliding movement of the support member 180 with respect to the guide rod 188. Furthermore, the support member 184 is supported by the support plate 62 via a sliding member 190, thereby allowing relative movement between the support member 184 and the support plate 62.

In the screen receivers 182, 186, two rows of suction holes 192 are provided at equal intervals in the longitudinal direction, with one end opening on the upper surface, as the screen receiver 186 is typically shown in FIG. Each suction hole 192 has a stepped shape, the large diameter hole 194 is opened on the upper surface of the screen receiver 186, and the small diameter hole 194 is opened on the upper surface of the screen receiver 186.
6 is communicated with a passage 198 extending in the longitudinal direction of the screen receiver 186 for each row. These passages 198 have a passage 200 that opens on the outer surface of the screen receiver 186 at the center in the longitudinal direction.
and are connected to a vacuum source (not shown) by a supply pipe 202 connected to the opening of the passage 200. The vacuum source is provided with an electromagnetic directional switching valve, and by switching the switching valve, the suction hole 192 is switched between communicating with the vacuum source and communicating with the atmosphere. If the opening of the suction hole 192 is covered by the screen 24 and communicated with a vacuum source, the screen 24 will be suctioned from below and fixed to the screen receivers 182, 186, and the screen 24 will be fixed to the screen receivers 182, 186 during printing. It is in a state where it is fixed to the substrate support stand 18 whose position is fixed. The screen receivers 182, 186 are integrally provided with a plurality of nozzles each having a suction hole 192, and in this embodiment, the screen receivers 182, 186, the suction hole 192, the passage 19
8,200, a supply pipe 202, a vacuum source, etc. constitute an adsorption device.

As is clear from the above explanation, the upper surfaces of the screen receivers 182 and 186 function as suction surfaces, and this suction surface is used as the substrate support stand 18.
The substrate support surface is discontinuously formed on the side of the substrate support surface. The substrate support stand 18 and the screen receivers 182, 186 are constructed separately, and an atmospheric layer is formed between the suction surface and the substrate support surface.

If the screen 24 has a short length in the longitudinal direction and there is a suction hole 192 whose opening is not covered by the screen 24, the opening is hermetically closed with a plug 204 as shown in FIG. Stopper 2
04 has a stepped shape and is made of urethane rubber, and its small diameter portion 206 is sized to be press-fitted into the small diameter hole 196 of the suction hole 192, and the diameter of the large diameter portion 208 is larger than that of the large diameter hole. 194, and its surface is plated with iron. Therefore, although the plug 204 is attached and removed by an operator, removal can be easily done by using a magnet.

(Substrate holding device) As is clear from FIG. 6, the substrate holding device 17 includes a pair of holding plate guides 210 fixed to the support members 180 and 184, respectively. The holding plate guide 210 has a U-shaped cross section, and engages with both side edges of the substrate holding plate 34 to limit the movable direction of the substrate holding plate 34 to one direction. That is, movement of the substrate holding plate 34 in the vertical direction (direction parallel to the moving direction of the substrate support stand 18) and in a direction perpendicular to the vertical direction and the conveyance direction of the substrate conveyor 16 is prevented, and the movement in the conveyance direction of the substrate conveyor 16 is prevented. It is designed to only allow movement in the direction parallel to . However, the presser plate guide 21
0 has an L-shaped cross section by removing a portion that engages the side edge of the substrate holding plate 34 from above at a portion away from the upper position of the substrate support stand 18. Board holding plate 3
4 can be removed upwards.

Further, a bar 212 is disposed parallel to the fixed rail 30 and the presser plate guide 210 so as to be movable in the longitudinal direction while being guided by a guide member (not shown). As shown in FIG. 7, an endless chain 214 is connected to the chain 21.
The bar 212 is moved in the longitudinal direction by being driven by a chain drive device 4 comprising a sprocket, a motor, etc. (not shown). Engagement members 216 are attached to two locations separated in the longitudinal direction of this bar 212, and as the bar 212 moves, these engagement members 216
16 engages with the front end and lower end of the substrate holding plate 34 to move the substrate holding plate 34 along the holding plate guide 210.

(Operation) Next, this printing machine prints a small printed circuit board 20.
The case of printing using a combination screen will be explained below. Note that before this printing, a large printed circuit board 20 is installed as shown in FIG.
It is assumed that adhesive printing has been carried out.

When printing on a large printed circuit board 20 is finished, remove the board support stand 18, screen 24, squeegee 28, and board holding plate 34 that have been attached to the printed circuit board 20, and remove the handle as shown in FIG. 170 is rotated to adjust the width of the board conveyor 16 to a width suitable for the small printed circuit board 20. Thereby,
The spacing between the screen supports 182 and 186 is narrowed to support the screen 24 just outside the printed circuit board 20, and the rail feed screw 132 and movable base feed screw 168 are connected to the sprocket 134 etc. as described above. Since the movable rail 32 is connected by a rotation transmission mechanism consisting of
is moved relative to the fixed rail 30, the movable platform 38 is moved in the same direction by one-half distance. Therefore, the substrate positioning and supporting device 10, screen positioning and supporting device 12, and squeegee device 14 installed on the movable table 38 also move by one-half of the moving distance of the movable rail 32, and the substrate conveyor 16 Even if the width of the board is changed, as shown in FIG.
and the center of the squeegee 28 in the width direction are maintained in alignment.

Once the width of the board conveyor 16 has been adjusted, the board support stand 18, screen 24, squeegee 28, and board holding plate 34 corresponding to the new printed circuit board 20 are attached to the mounting member 80, screen support stand 22, mounting member 118, and Attach to the presser plate guide 210. The screen 24 is fixed to the screen receivers 182 and 186 by suction by communicating the suction hole 192 with a vacuum source, but since the screen receivers 182 and 186 are located just outside the printed circuit board 20, the screen 24 The metal portion 108 will be attracted. The suction hole 192 is maintained in communication with the vacuum source until printing on one type of printed circuit board 20 is completed.

When the printing machine is started after the above-mentioned setup change is completed, the printed circuit board 20 is moved by the board conveyor 16 to the board supporting table 18 which is at the lower end position and above it, as shown in FIG. 9a. While being carried between the screen 24 and the substrate holding plate 3
4 is moved into the working position. Printed circuit board 2
0 reaches above the substrate support stand 18, the stopper device 140 prevents further advancement.

Subsequently, the substrate support stand 18 is raised by the multistage cylinder 82 to the first intermediate position shown in FIG. 9b. In this process, the board support stand 18 scoops up the printed circuit board 20 from below, and at the same time, the positioning pins 146 fit into the positioning holes of the printed board 20, and the printed board 20 is moved to the board support stand 18.
Position accurately against. After this positioning, the board support stand 18 reaches the first intermediate position, and the printed circuit board 20 is pressed against the board support stand 18 by the board holding plate 34. In this state, the suction tube 92
Negative pressure is supplied to the printed circuit board 20, so that the printed circuit board 20 is reliably attracted to the board support stand 18.

Subsequently, as shown in FIG. 9c, the substrate support stand 18 is
is lowered to the second intermediate position, and the printed circuit board 20 held thereby is slightly separated from the board holding plate 34. Thereafter, the substrate holding plate 34 is retracted from the position above the substrate support stand 18, as shown in FIG. 9d. Therefore, the substrate support stand 18
can be raised to the rising end position as shown in FIG. 9e, and the printed circuit board 20 held by it comes into contact with or approaches the lower surface of the screen 24.

Subsequently, in FIG. 5, the left squeegee 28 is raised, and the right squeegee 28 is moved from right to left in contact with the top surface of the screen 24.
A portion of the creamy solder that is pushed over the screen 24 by the right squeegee 28 appears on the screen 2.
It is pushed into a large number of small holes formed in 4 and attached to the upper surface of the printed circuit board 20. After passing above the printed circuit board 20, the right squeegee 28
is raised, the left squeegee 28 is lowered, and the next printed circuit board 20 is ready to be printed by moving the left squeegee 28 from left to right.

After the above operation, the board support stand 18 is lowered to the lower end position, and the printed board 20, which has been printed, is
is again supported by the substrate conveyor 16. Therefore, when the stopper member 144 of the stopper device 140 is lowered and the rope 33 of the board conveyor 16 is driven, the printed printed circuit board 20 is carried out from the position above the board support stand 18, and one cycle of the printed circuit board 20 is carried out. The printing operation ends.

In the printing of this embodiment, the screen 24 is a combination screen, and the surrounding part is formed of a mesh, but the central metal part 108 is attracted by the screen receivers 182 and 186, and its horizontal position is fixed. Therefore, even if force is applied as the squeegee 28 moves, it will not shift relative to the screen receivers 182, 186. Since the screen supports 182 and 186 are fixed in position with respect to the substrate support stand 18 during printing, the screen 24 is fixed to the screen support stand 182 and 186, so that the screen 24 is fixed to the substrate support stand 18 and, by extension, to the substrate support stand 18. Since the horizontal position relative to the supported printed circuit board 20 is fixed, the position relative to the printed circuit board 20 does not shift during printing, and the advantages of the combination screen can be enjoyed without causing a decrease in printing accuracy. be able to.

Furthermore, when the screen 24 is attracted to the screen receivers 182 and 186, a vacuum acts on the gap between the lower surface of the screen 24 and the upper surface of the screen receivers 182 and 186; Printed circuit board 2
0 or the printed circuit board 2
0 and the upper surface of the substrate support stand 18. If the vacuum spreads into these gaps, the adhesive pushed into the small holes of the screen 24 during printing will be sucked deeper into the vacuum and adhere to the top surface of the printed circuit board 20, resulting in poor printing accuracy or the bottom surface of the screen 24. However, in this embodiment, the vacuum acting on the gap between the lower surface of the screen 24 and the upper surface of the screen receivers 182, 186 is removed from the screen receivers 182, 186. The screen 24 is blocked by an atmospheric layer interposed between it and the substrate support 18.
Since the gap does not spread to the gap between the bottom surface of the printed circuit board 20 and the top surface of the printed circuit board 20 or the gap between the bottom surface of the printed circuit board 20 and the top surface of the board support stand 18, the above-mentioned inconvenience can be avoided.

In addition, in this embodiment, a large number of suction nozzles are provided integrally with the screen receivers 182 and 186, and compared to a case where they are provided separately, the installation space of the device is smaller and the number of parts is smaller. It's over.

In the embodiment described above, the plug 204 that closes the suction hole 192 is removed by being attracted by a magnet, but it may be removed by being grasped by an operator using a hand or a tool. In this case, as shown in FIGS. 10 and 11, the suction hole 22
It is preferable that the large diameter hole 222 of 0 is an elongated hole, and a gap is provided on both sides of the large diameter part 226 of the plug 224 for inserting a hand, a tool, or the like. The plug 224 is made of urethane rubber, and its small diameter part 228 is press-fitted into the small diameter hole 230 of the suction hole 220, and the outer circumferential surface of the large diameter part 226 is attached to the small diameter part 230 of the suction hole 220.
It is desirable that the tapered surface approaches the center closer to the 28th side to make it easier to grip.

In addition, in the above embodiment, the screen 24
Although we have explained the case where the screen is a combination screen, even when the screen is a mesh screen or a metal screen, by adsorbing it with a suction device, the deviation when moving the squeegee can be reduced.
The effect of improving printing accuracy can be obtained.

In addition, it goes without saying that the present invention can be implemented with various modifications and improvements based on the knowledge of those skilled in the art, although not illustrated individually.

[Brief explanation of the drawing]

FIG. 1 is a front cross-sectional view showing the main parts of a suction device for a printed circuit board screen printer, which is an embodiment of the present invention. FIG. 2 is a front sectional view showing a state in which the suction hole of the suction device is closed with a stopper.
FIG. 3 is a plan view schematically showing a combination screen used in the screen printing machine. FIG. 4 is a side sectional view of the main parts of the screen printing machine. FIG. 5 is a partially cutaway front view of the main parts of the printing press. FIG. 6 is an enlarged side sectional view showing the vicinity of the substrate conveyor in FIG. 5. FIG. FIG. 7 is a view taken along arrow A in FIG. 6 (however, the presser plate guide is omitted). FIG. 8 is a side sectional view showing the main parts of a screen printing machine when printing on a small printed circuit board. Figure 9 a, b, c, d,
FIG. 4e is an explanatory diagram schematically showing different operating states of the printing press. FIG. 10 is a plan view showing another aspect of the suction hole of the suction device, and the first
FIG. 1 is a front sectional view showing a state in which the suction hole is closed with a stopper. 10... Board positioning support device, 12... Screen positioning support device, 14... Squeegee device, 16... Board conveyor, 17... Board holding device, 18... Board support stand, 20... Printed circuit board, 22... ... Screen support stand, 24 ... Screen, 26 ... Screen frame, 28 ... Squeegee, 108 ... Metal part, 109 ... Mesh part, 192 ... Suction hole, 198, 200 ... Passage, 202 ... Supply Pipe, 204... Stopper, 220...
...Suction hole, 224...Plug.

Claims (1)

[Claims for Utility Model Registration] (1) A screen comprising: a substrate support stand, a squeegee, a screen whose peripheral portion is fixed to the screen frame, and a screen support stand that supports the screen in the screen frame; In a screen printing machine that prints adhesive, creamy solder, etc. on a printed circuit board supported on a substrate support by moving a squeegee linearly above the substrate support, the printed circuit board is supported on the substrate support. A plurality of nozzles each having a suction surface that is discontinuous with the substrate support surface and that suctions a portion of the screen inside the screen frame are disposed on the side of the substrate support surface, and these nozzles are connected to a vacuum source. A printed circuit board screen printing machine characterized by a connection. (2) The plurality of nozzles are formed by forming a plurality of suction holes opening on the upper surface of the flat plate in one flat plate, and connecting the suction holes to the vacuum source through an air passage. A printed circuit board screen printing machine according to claim 1, which has been registered as a utility model. (3) The plurality of nozzles are connected to the vacuum source through a common air passage, and the plurality of nozzles are provided with a closing member that airtightly closes the openings of the nozzles that are not covered by the screen. The printed circuit board screen printing machine according to item 1 or 2.