JPH05185580A - Cream solder printing machine - Google Patents

Abstract

PURPOSE:To improve performance in contact printing to be made between a printing mask and a circuit substrate, and to improve furthermore printing accuracy in cream solder printing by a method wherein pulling-off of the cream solder is controlled when a plate is separated. CONSTITUTION:A substrate attracting port 32 is provided to a backup plate 27, and a circuit substrate 2 is fixed to the backup plate 27 by attraction of vacuum suction. Clamp plates 25a and 25b are provided on both sides of the backup plate 27 and vacuum suction ports 30 are provided to plate surfaces 26. In printing of cream solder to the circuit substrate 2, the reverse face of a printing mask 3 is fixed by suction to the plate surfaces 26 and thereby the reverse face of the printing mask 3 is stuck forcibly to the circuit substrate 2. The backup plate 27 is so constructed that the plate can move vertically by operation of a servomotor 18. When separating the plate after printing of the cream solder to the circuit substrate 2, the backup plate 27 is lowered slowly by operation of the servomotor 18.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cream solder printing machine for printing cream solder on a circuit board.

[0002]

2. Description of the Related Art FIG. 5 shows a general cream solder printing machine. In the figure, the print table 1
Is a movement in the directions of three orthogonal axes of X, Y and Z and a θ rotation movement (X,
The circuit board 2 is fixed to the upper side of the printing table 1 by using a clamp or the like. A printing mask 3 is arranged on the upper side of the printing table 1, and when printing the cream solder on the circuit board 2, the printing table 1 is moved upward to bring the front surface of the circuit board 2 into close contact with the back surface of the printing mask 3. In this state, the drive mechanism (not shown) is operated to move the squeegee 5 while pressingly contacting the surface of the print mask 3 on which the cream solder 4 is applied, and the opening 6 of the print mask 3 is moved.
The layer of cream solder 4 corresponding to the pattern shape is transferred onto the circuit board 2.

At the end of printing of the cream solder 4, as shown in FIG. 6, the printing table 1 is lowered from the position shown in FIG. 1A to separate the circuit board 2 from the back surface of the printing mask 3 and the printing mask 3. With the printing plate 1 separated from the circuit board 2 and the printing table 1 lowered to a predetermined position, the printed circuit board 2 is removed, the next circuit board is attached, and the cream solder 4 printing operation continues. Done.

[0004]

When the cream solder 4 is printed by bringing the front surface of the circuit board 1 into close contact with the back surface of the printing mask 3, the surface of the circuit board 1 is actually printed with a silk-printed portion, There is a solder resist forming part and it is not smooth, dust or the like adheres to the substrate surface, or the parallelism between the back surface of the print mask 3 and the surface of the circuit board 2 is incorrect, or the circuit board There is a problem that the printing accuracy of the cream solder cannot be increased due to various factors such as the warp of 2 and the various reasons that the surface of the circuit board 2 cannot be surely brought into close contact with the back surface of the print mask 3.

Further, when the printing table 1 is lowered to separate the printing plate after the printing of the cream solder is completed, the state shown in FIG. 6A and FIG. When the circuit board 2 side starts to descend as shown in b), the adhesive force of the cream solder 4 causes the circuit board 2 to move.
The print mask 3 also flexes and deforms downward as a result of being integrated with the above.
Then, as shown in (c) of these figures, when the restoring force due to the bending of the print mask 3 is lowered to a position where it overcomes the adhesive force of the cream solder 4, the print mask 3 separates from the circuit board 2, but At this time, the print mask 3 is separated from the circuit board 2 by an elastic restoring force so as to bounce upward, so that the cream solder 4 extended as shown in FIG. 4B is torn off at the time of the bounce up. The shape of the cream solder die-cut from the opening 6 does not become sharp, resulting in a problem of poor printing accuracy.

FIG. 3 is a graph showing the results of measuring the displacement of the circuit board 2, the print mask 3 and the cream solder 4 when the circuit board 2 is lowered after printing the cream solder 4 using a laser displacement meter. Yes, the vertical axis represents displacement, and the horizontal axis represents time. When the circuit board 2 starts to descend from the point A, the printing mask 3 flexes and follows downward due to the adhesive force of the cream solder 4, and at point B, plate separation occurs. At this time, the print mask 3 jumps up due to the elastic restoring force and returns to the free position where there is no bending. In the figure, H indicates the amount of pressing in which the surface of the circuit board 2 is pressed against the printing mask 3 in order to bring it into close contact with the printing mask 3. The amount of flexure of the print mask 3 due to the adhesive force of the cream solder 4 depends on the circuit board 2
The higher the descending speed of, the greater the jumping force at the time of releasing the plate, and the tearing of the cream solder is likely to occur. This tearing was a factor that deteriorated the printing accuracy of the cream solder.

The present invention has been made in order to solve the above-mentioned conventional problems, and an object of the present invention is to reliably adhere the front surface of a circuit board to the back surface of a printing mask when printing cream solder. An object of the present invention is to provide a cream solder printing machine capable of increasing the printing accuracy by controlling the descending speed of the circuit board at the time of separation and suppressing the phenomenon of tearing of the cream solder at the time of plate separation.

[0008]

In order to achieve the above object, the present invention is constructed as follows. That is, according to the present invention, a circuit board is brought into close contact with the back surface of the printing mask, and a squeegee is pressed against the surface of the printing mask coated with cream solder to move the cream solder layer having a shape corresponding to the opening pattern of the printing mask. In a cream solder printing machine for printing on both sides of the circuit board, clamp plates are arranged on both sides of the circuit board so that the plate surface is flush with or slightly lower than the surface of the circuit board at the printing position. A backup plate for mounting and holding the substrate is arranged so as to be movable up and down relative to the clamp plate, and a back face of the print mask is brought into contact with and fixed to the plate surface of the clamp plate to face the circuit substrate. Forcibly attach the back side of the A substrate fixing means for holding and fixing the Pupureto is configured as characterized by comprising a controllable backup plate vertical drive means moving speed of the backup plate.

[0009]

In the present invention having the above structure, the circuit board is placed on the upper surface of the backup plate, the circuit board is held and fixed by the board fixing means, and the front surface of the circuit board is pushed into the back surface of the printing mask, or By operating the mask forced contact means in the state of being close to each other, the back surface of the print mask is forcibly brought into contact with and fixed to the front surface of the clamp plate, and the back surface of the print mask facing the circuit board is pressed against the circuit board to ensure contact. Stick to.

In this state, the solder paste is printed on the circuit board. At the end of this printing, the back surface of the print mask is fixedly held by the clamp plate, and the backup plate is slowly lowered by speed control. , The plate is released without tearing the cream solder.

[0011]

Embodiments of the present invention will be described below with reference to the drawings. In the description of this embodiment, the same members as those described in the conventional example are designated by the same reference numerals, and the duplicate description thereof will be omitted. 1 and 2 show an embodiment of the cream solder printing machine according to the present invention. In these figures, the rotary table 7 is mounted on a movable table 8 which can be moved in the X and Y directions of X, Y and Z triaxial Cartesian coordinates and in the θ direction (rotational direction on the X and Y planes). The rotary table 7 is fixed, and the rotary table 7 can be freely moved in the X and Y directions and can be rotated on a horizontal plane by the operation of the moving table 8. The air cylinders are provided at four corners of the rotary table 7. 10 is fixed. A base table 12 is fixed to the tip of the rod 11 of each air cylinder 10, and the base table 12 can be moved vertically (moved in the Z direction) by the air cylinder 10.

A base end side of a ball screw 13 is rotatably attached to the base table 12, and a height adjusting base 14 is arranged above the ball screw 13. This height adjustment stand
A nut 15 for a ball screw is fixed to the ball screw 14.The nut 15 is fitted to the ball screw 13 so that the height adjusting table 14 can be moved up and down by rotating the ball screw 13 in a desired direction. There is. Sliding bearings 16a and 16b are provided on the rotary table 7 and the height adjusting table 14, and a sliding shaft 17 is vertically slidably inserted through the sliding bearings 16a and 16b. Reference numeral 17 is fixed to the base table 12, and when the base table 12 moves up and down by driving the air cylinder 10, the movement is restricted by the sliding shaft 17. Also,
A servo motor 18 is attached to the base table 12, and an output shaft 20 of the servo motor 18 is projected above the base table 12, and a drive pulley 21 is attached to the output shaft 20.
Are fitted and fixed. The drive pulley 21 is meshed with a timing belt 22, and the timing belt 22 is wound around a timing belt pulley 23 attached to the shaft of the ball screw 13 to provide a servo motor.
The ball screw 13 is rotated through the timing belt 22 by the rotation of 18 in the desired forward and reverse directions, so that the height adjustment table 14 is moved up and down.

The base ends of a pair of leg arms 24 are fixed to the height adjusting base 14, and a pair of clamp plates 25a and 25b are provided on the upper end surfaces of the leg arms 24.
It is fixed with 26 horizontal. This clamp plate
A backup plate 27 is arranged between 25a and 25b, and the lower end of the backup plate 27 is fixed to the height adjusting table 14. The upper end surface of the backup plate 27 is a horizontal surface.
When the circuit board 2 is mounted and fixed on the upper end surface of 27, the height position of the plate surface 26 of the clamp plates 25a and 25b with respect to the surface of the board 2 at the cream solder printing work position is
The surface is set to be equal to or slightly lower than the surface of the circuit board 2.

A plurality of suction grooves 28 are formed on the plate surfaces 26 of the clamp plates 25a and 25b along the length direction of the clamp plates, and vacuum suction holes 30 are formed on the bottom surface of each suction groove 28. The vacuum suction hole 30 is connected to a vacuum generator 31 such as a vacuum pump. The suction groove 28 and the vacuum suction hole 30 function as a mask forced contact means for suction-fixing the back surface of the print mask 3.

The backup plate 27 is provided with a substrate suction hole 32 as a substrate fixing means for sucking and fixing the circuit board 2, and this substrate suction hole 32 is also the vacuum generator.
The circuit board 2 mounted on the backup plate 27 is fixedly held by the vacuum generator 31 connected to the vacuum generator 31. The servo motor 18 functions as a vertical drive means for the backup plate 27.

This embodiment is constructed as described above,
Next, the printing operation of the cream solder will be described. First, at a position where the base table 12 is lowered, the circuit board 2 is transferred onto the backup plate 27 by a transfer unit (not shown), and placed on the upper surface of the backup plate 27 in an aligned state. In this state, by driving the vacuum generator 31, the circuit board 2 is sucked and held and fixed on the backup plate 27 using the board suction holes 32. Next, the servo motor 18 is rotated, and the timing belt 22 is driven by the drive pulley 21 accordingly, and the pulley 23
By rotating around, the ball screw 13 is rotated, and the height adjusting base 14 on the nut 15 side that is screwed into the ball screw 13 moves up, and the backup plate 27 fixed to this height adjusting base 14 also interlocks. The circuit board 2 that has been moved upwardly and is mounted and fixed on the backup plate 27 is set at a predetermined height position for the printing operation. In this set state, the surface of the circuit board 2 is the plate surface of the clamp plates 25a and 25b.
It is at the same height as 26 or slightly higher than the plate surface 26.

Next, the air cylinder 10 is driven and the base table 12 is moved upward, and along with this, the backup plate 27 is also moved upward together with the base table 12 and the surface of the circuit board 2 is printed. It is pressed against or brought close to the back surface of the mask 3.

Next, the vacuum generator 31 performs vacuum suction of the vacuum suction holes 30, and the back surface of the print mask 3 is suction-fixed to the plate surface 26 of the clamp plates 25a and 25b. By fixing the print mask 3 by suction,
Even if the horizontality of the print mask 3 is a little unbalanced, or the circuit board 2 has undulations or warpage, the print mask 3
Is adsorbed to the plate surface 26 on both the left and right sides of the circuit board 2, so that the back surface of the print mask 3 facing the circuit board 2 surely adheres to the surface of the circuit board 2.

In this state, similarly to the conventional example, the squeegee 5 is moved while pressing the upper surface of the printing mask 3 to which the cream solder 4 is applied, so that the cream solder corresponding to the pattern shape of the opening 6 of the printing mask 3 is moved. Is transferred to the surface of the circuit board 2. After the transfer of the cream solder 4, the servo motor 18 is rotated in the reverse direction while the back surface of the print mask 3 is still attracted to the plate surface 26, and the backup plate 27 is lowered to separate the plate. At the time of this plate separation operation, the servo motor 18 is first rotated at a low speed, the backup plate 27 is slowly lowered to separate the plate, and after the completion of the plate separation, the rotation speed of the servo motor 18 is increased to increase the backup plate. Immediately lower 27 to the home position. Further, after the plate separation is completed, the vacuum suction from the vacuum suction hole 30 is stopped to release the suction fixing state of the print mask 3 on the plate surface 26. Next, the air cylinder 10 is operated to lower the base table 12, the suction of the substrate using the substrate suction holes 32 by the vacuum generator 31 is stopped, and the circuit board 2 on which the cream solder is printed is taken out. Then, the circuit board 2 for the next printing is conveyed and set on the backup plate 27. From this set of circuit board 2, cream solder printing, plate separation,
By repeating the work of taking out the printed circuit board 2, cream solder is printed on the circuit board 2 one after another.

According to this embodiment, when the cream solder is printed on the circuit board 2, the back surface of the printing mask 3 is on both sides of the circuit board 2 and is the same as or slightly lower than the front surface of the board 2. Since the circuit board 2 and the print mask 3 are firmly adhered to each other in a direction in which they are forcibly pressed against the 26, the printing accuracy of the cream solder 4 can be sufficiently increased.

Further, when the printing mask 3 is separated from the printing plate after the printing of the cream solder is completed, the backup plate 27 is slowly lowered by the control of the rotation speed of the servo motor 18, so that the printing mask 3 is printed on the plate. The leaping of the cream solder becomes gentle when separated, and the cream solder is sharply punched from the opening 6 of the print mask 3 without being torn off. It is possible to dramatically increase it.

Further, when the plate separation is performed, since the back surface of the printing mask 3 is sucked and fixed to the plate surface 26 of the clamp plates 25a and 25b, the printing mask 3 is removed.
Since the span L ₂ between the fixed holding portions of is sufficiently shorter than the span L ₁ between the frames 9 of the print mask 3 (FIG. 1),
Apparently, the rigidity of the print mask 3 is increased, and therefore, when the plate separation is performed, the amount of flexure of the print mask 3 which follows the lowering of the circuit board 2 due to the adhesive force of the cream solder 4 is reduced, and the print mask 3 is slightly bent. Since plate separation can be performed at the flexed position, the time required to slowly lower the backup plate 27 until the completion of plate separation is shortened, and thus the work efficiency of printing work can be improved.

The present invention is not limited to the above-mentioned embodiments, and various embodiments can be adopted. For example, in the above embodiment, the print mask 3 is attached to the clamp plates 25a and 25b.
The mask forcibly adhering means for fixing to the plate surface 26 of No. 1 was constituted by an adsorbing means utilizing the vacuum suction holes 30. For example, the printing mask 3 is pressed against the plate surface 26 from above by an elastic member such as a rubber roll. It may be fixed, and various means other than adsorption can be adopted.

In the above embodiment, the circuit board 2 is fixed to the backup plate 27 by suction, but it may be fixed using mechanical means such as a claw.

Further, the servo motor 18 is used as a driving means for moving the backup plate 27 up and down, but this driving means slowly lowers the circuit board 2 when separating the plate, and after the plate separating, the speed is lowered. Any motor that can perform speed control for accelerating and lowering the speed can be used, and can be configured using another motor such as a pulse motor, a DC motor, or an AC motor.

[0026]

According to the present invention, the clamp plates are arranged on both sides of the backup plate for mounting and fixing the circuit board,
Since the back surface of the printing mask is fixed to the surface of the plate by contact, the parallelism of the printing mask may be a little misaligned, the surface of the circuit board may not be smooth, or undulations or warpage may occur. Even if there is a problem, the back side of the print mask can be firmly attached to the front side of the circuit board,
Thereby, the printing accuracy of cream solder can be improved.

Further, since the vertical movement speed of the backup plate can be controlled, when the circuit board and the printing mask are separated from each other after the cream solder is printed on the circuit board, the circuit board side should be slowly moved. Since it is possible to lower the plate to separate it, it is possible to suppress the phenomenon of tearing of the cream solder by slowing up the jumping due to the elastic restoring force of the print mask that occurs when separating the plate. As a result of being able to sharply remove the cream solder, it is possible to print the cream solder on the circuit board without losing its shape, and in combination with the adhesion performance of the printing mask, the printing accuracy of the cream solder is dramatically improved. Is possible.

[Brief description of drawings]

FIG. 1 is a side view of essential parts showing an embodiment of a cream solder printer according to the present invention with a squeegee part omitted.

FIG. 2 is a perspective view showing a cream solder printing machine according to the embodiment with a print mask and a squeegee portion omitted.

FIG. 3 is a graph showing the displacement behavior of the circuit board, the print mask, and the cream solder when the plate is separated.

FIG. 4 is a detailed explanatory diagram of an operation from cream solder printing to plate separation.

FIG. 5 is a schematic explanatory diagram of an operating state of a general cream solder printing machine.

FIG. 6 is an explanatory diagram of an operation from printing to plate separation in a conventional cream solder printing machine.

[Explanation of symbols]

 2 Circuit board 3 Printing mask 4 Cream solder 10 Air cylinder 12 Base table 14 Height adjustment table 18 Servo motor 26 Plate surface 27 Backup plate 30 Vacuum suction hole 31 Vacuum generator 32 Board suction hole

Claims (1)

[Claims] 1. A circuit board is adhered to the back surface of the print mask, and a squeegee is pressed against the surface of the print mask coated with cream solder to move the cream solder layer having a shape corresponding to the opening pattern of the print mask on the circuit board. In a cream solder printing machine for printing, clamp plates are arranged on both sides of the circuit board so that the plate surface is flush with or slightly lower than the surface of the circuit board at the printing position, and the circuit board is placed between the clamp plates. A backup plate for mounting and holding the print mask is arranged so as to be movable up and down relative to the clamp plate, and the back surface of the print mask is abutted and fixed to the plate surface of the clamp plate so as to face the circuit board. A mask forcible adhesion means that forcibly adheres the back surface to the circuit board, and a backup plate for the circuit board. A cream solder printing machine comprising: a board fixing means for holding and fixing the same on a board; and a backup plate vertical drive means capable of controlling the moving speed of the backup plate.