JPH1016183A - Paste ink printing machine - Google Patents

Abstract

[PROBLEMS] To provide a paste ink printing machine capable of printing cream solder on a circuit board irrespective of the direction of a printing pattern and suppressing the occurrence of printing unevenness. SOLUTION: Paste ink supplied to the upper surface of a mask 20 having a print pattern perforated thereon is squeezed by a squeegee 2 which is in contact with the upper surface of the mask, so that the paste form is printed on an object to be printed placed on the lower surface of the mask. Ink printing machine 1. It has a first reciprocating mechanism 8 for reciprocating the squeegee in a direction perpendicular to the squeegee longitudinal direction, and a second reciprocating mechanism 10 for reciprocating the squeegee in a direction parallel to the squeegee longitudinal direction.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a method of supplying paste ink such as cream solder, conductive paste or insulating paste onto a mask having a printed pattern formed thereon and applying squeegee squeegee thereto. The present invention relates to a paste-type ink printing machine that prints on a printing substrate disposed on a lower surface of a mask.

[0002]

2. Description of the Related Art A cream solder printing machine, which is a typical example of a conventional paste ink printing machine, offsets a printing mask having a predetermined printing pattern perforated on a stainless steel plate or the like and a circuit board for printing the cream solder by a predetermined distance. Then, the cream solder on the print mask is squeezed with a squeegee. By this, the cream solder is passed through the holes of the print mask while rolling, and a desired print pattern made of the cream solder is transferred onto the circuit board, and is widely used because it is a simple and excellent printing machine. .

At this time, it is well known that the squeegee moves in the direction of the arrow AV perpendicular to the direction of the arrow AL parallel to the longitudinal direction of the squeegee 2 as shown in FIG. 7 (see FIG. 7).
Squeezing is performed by moving to. When printing is completed, the squeegee returns to its original position by following the same trajectory as squeezing in reverse, and printing work is performed by this reciprocating movement.

[0004]

In the cream solder printing machine described above, the finer the fine pitch of the printed pattern, the more difficult it becomes for the cream solder to enter the holes of the printed mask in which the printed pattern is formed. However, there is a problem that print unevenness occurs in the print pattern in the above.

In particular, for semiconductor ICs, the QFP (Quadrant Flat Packag) has been adopted for the surface mount type due to a drastic review of the package shape including narrowing of the lead pitch.
A multi-pin ultra-small package called e) has been realized. In this QFP, since a large number of leads are arranged in a direction orthogonal to each other, a large number of holes serving as print patterns are formed in the print mask in directions different by 90 degrees. Therefore, if the squeegee squeezes the cream solder in one direction, even if the cream solder rolls, it will be difficult for the cream solder to enter the hole, depending on the direction of the hole, causing uneven printing and corresponding to narrow pitch leads. become unable.

In order to solve the above-mentioned problem that the cream solder is hard to enter the holes of the print pattern, rollers and pistons for applying a pushing force to the cream solder are opposed to each other in two parallel squeegee blades. Instead of relying on rolling, a method is employed in which cream solder is forcibly pushed into a hole of a print mask by a roller or a piston during squeezing.

However, in such a method, a squeegee,
Therefore, the structure of the cream solder printing machine becomes complicated, and replacement with different types of cream solder becomes very troublesome.
Furthermore, since there are two squeegee blades in contact with the print mask, it is difficult to keep the blades mechanically parallel to each other, and if the parallelism is not achieved, the cream solder will leak out of the squeegee. Further, the squeegee blade basically needs to use a metal material because of the above structure. For this reason, when using a squeegee blade, it is not possible to follow the delicate irregularities of the print mask, and the scrape of the cream solder is poorly removed, and the removability of the cream solder from the hole of the print mask to the circuit board side is deteriorated. However, printing unevenness occurs in the print pattern transferred onto the circuit board.

On the other hand, as a means for solving the above-mentioned problem in the QFP, a hole serving as a print pattern is formed by rotating the hole by 45 degrees with respect to the print mask, or a squeegee is rotated by 45 degrees with respect to the X axis and the Y axis of the print mask. By tilting and squeezing at the same speed with respect to the X and Y axes,
The directionality of the squeegee for the print pattern is eliminated.

[0009] However, the print pattern is used as a print mask.
In the case of forming by rotating the print mask by a degree, it is necessary to re-create the print mask, which is a very large expense. When the squeegee is arranged at an angle of 45 degrees with respect to the X and Y axes of the print mask, the conventional print mask can be used as it is. However, since the squeegee interferes with the frame of the print mask, the squeegee must be small, and there is a problem that the area on the circuit board on which the cream solder can be printed becomes narrow.

Although the problems of the prior art have been described using a cream solder printing machine as an example, the same problem occurs in a printing machine that prints another paste ink. The present invention has been made in view of the above points, and an object of the present invention is to provide a paste ink printing machine that can print paste ink regardless of the direction of a print pattern and that can suppress the occurrence of printing unevenness. I do.

[0011]

According to the present invention, in order to achieve the above object, paste ink supplied to the upper surface of a mask having a printed pattern is squeezed by a squeegee in contact with the upper surface of the mask. Thereby, in a paste ink printing machine that prints on a printing material installed on the lower surface of the mask, a first reciprocating mechanism that reciprocates the squeegee in a direction orthogonal to the squeegee longitudinal direction, and is parallel to the squeegee longitudinal direction. And a second reciprocating mechanism for reciprocating the squeegee in the direction.

[0012] Preferably, the second reciprocating mechanism for reciprocating the squeegee in a direction parallel to the longitudinal direction of the squeegee includes a rack, a pinion, and a motor for rotating the pinion. Also preferably,
The squeegee is provided with an ink presser for pressing the paste ink toward the mask.

[0013] More preferably, a plurality of grooves having side walls orthogonal to the longitudinal direction of the squeegee and inclined from the vertical direction are formed on a surface of the ink retainer facing the mask.

[0014]

According to the first or second aspect of the present invention, since printing is performed while the squeegee moves in a zigzag manner, it is possible to eliminate the directionality with respect to the print pattern.
Good printing is possible even with a print mask in which a large number of lead patterns provided in various directions such as P are perforated.

According to the third aspect of the present invention, the paste-like ink is pressed into the pattern perforated in the print mask by the action of the ink press, thereby improving printability. Furthermore, according to the invention of claim 4, the side wall of the groove provided in the ink press hit against the rolling operation of the paste ink by the reciprocating motion parallel to the longitudinal direction of the squeegee, and the ink was perforated in the print mask. Since the effect of pushing into the pattern is further enhanced, more excellent printability can be obtained.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an embodiment of a paste ink printing machine (hereinafter, referred to as "printing machine") of the present invention will be described in detail with reference to FIGS. The description will be made taking a cream solder printing machine, which is a typical printing machine, as an example. Here, the printing press 1 has the same configuration as that of the conventional printing press except that the printing press 1 includes a reciprocating mechanism 10 for reciprocating the squeegee in a direction orthogonal to the moving direction of the squeegee within the moving surface of the squeegee. Are identical. Therefore, as shown in FIGS. 1 and 2, only the reciprocating mechanism 10 and the print mask 20 are illustrated, a substrate clamp for holding a printed substrate as a printing substrate, a print table, a table elevating device for elevating the print table, and printing. When a suction device for sucking the mask 20 is used, other components not directly related to the reciprocating mechanism 10 according to the features of the present invention, such as the suction device, are not shown.

The printing press 1 includes a squeegee 2, two guide rails 3, a moving table 4, a mounting plate 5, an air cylinder 6,
It includes two lifting guides 7, a squeezing mechanism 8, a reciprocating mechanism 10, and a print mask 20. Squeegee 2
Is moved in the direction of arrow X in FIG. 1 by the squeegee mechanism 8 to squeeze the cream solder. As shown in FIGS. 3 and 4, the squeegee 2 is provided with a solder presser 2a for pressing the cream solder S toward the print mask. The solder presser 2a has a plurality of grooves 2b whose side walls are orthogonal to the longitudinal direction of the squeegee and are inclined from the vertical direction on the surface facing the print mask 20.

The guide rails 3 are arranged on both sides of the print mask 20, respectively. The movable table 4 for guiding the movement of the movable table 4 in the direction of the arrow X (see FIG. 1) is slidable at both ends on the guide rails 3. And is moved in the direction of the arrow X by the squeezing mechanism 8. The mounting plate 5 is supported at the lower part of the two lifting guides 7, and the squeegee 2 is mounted on the lower surface thereof via a slide guide 5a (see FIG. 2).

The air cylinder 6 is supported by the moving table 4, and the tip of a rod (not shown) projecting downward is connected to the mounting plate 5. Thereby, the air cylinder 6
The squeegee 2 is moved up and down by the mounting plate 5 and the squeegee 2 by taking the rod in and out, so that the vertical offset position of the squeegee 2 with respect to the print mask 20 can be appropriately changed. The elevating guide 7 guides the elevating operation of the mounting plate 5 by the air cylinder 6, and is arranged on both sides of the moving table 4 with the air cylinder 6 interposed therebetween.

The squeegee mechanism 8 has a ball screw 8a and a squeegee motor 8b. The ball screw 8a is screwed with a nut 4a attached to the lower surface of the moving table 4. As a result, when the ball screw 8a rotates, the nut 4a moves along the ball screw 8a, and as a result, the moving table 4 moves in the arrow X direction in FIG. The reciprocating mechanism 10 reciprocates the squeegee 2 in the arrow Y direction perpendicular to the moving direction (arrow X direction) within the moving surface of the squeegee 2 when the squeegee 2 squeezes the cream solder. 12 and a motor 13.

The rack 11 is attached to the side surface of the squeegee 2 in the longitudinal direction as shown in FIGS. The pinion 12 is attached to a rotation shaft 13a of the motor 13. The motor 13 is supported by the mounting plate 5,
The pinion 12 is rotated. Thus, when the motor 13 rotates, the squeegee 2 moves leftward or rightward in FIG. 2 while being guided by the slide guide 5a. Here, the mounting plate 5 is provided with limit switches (not shown) for detecting the left and right ends of the squeegee 2, respectively. Thus, when one of the limit switches is turned on, the motor 13 is rotated in the reverse direction to change the moving direction of the squeegee 2 in the reverse direction, whereby the squeegee 2 is reciprocated. At this time, if the moving direction of the squeegee 2 changes, the limit switch that has been on is turned off.

The printing mask 20 is supported by the mask frame 21 and is arranged below the moving table 4. The printing press 1 according to the present invention includes the squeegee 2 that reciprocates in the direction perpendicular to the longitudinal direction of the squeegee 2 as described above, and reciprocates the squeegee 2 in the direction parallel to the longitudinal direction of the squeegee 2. It is characterized in that a reciprocating movement mechanism 10 is provided.

That is, when printing the cream solder on the circuit board, the printing machine 1 holds the printed board on a board clamp of a printing table, raises the printing table to a predetermined height by a table elevating device, and prints the printed board with the circuit board. The vertical positioning with respect to the mask 20 is performed. Next, the pressure of the squeegee 2 on the print mask 20 is appropriately changed by the air cylinder 6, and the squeegee 2 starts squeezing of the cream solder on the print mask 20.

At this time, the printing machine 1 squeezes the cream solder as follows while the squeegee mechanism 8 and the reciprocating mechanism 10 operate in parallel. That is, the squeegee mechanism 8 rotates the ball screw 8a by the squeegee motor 8b, and moves the moving table 4 in the direction of the arrow X shown in FIG. As a result, the lower end of the squeegee 2 is moved in the arrow X direction while making contact with the upper surface of the print mask 20, and the cream solder is squeezed along the upper surface of the print mask 20.

At the same time, the reciprocating mechanism 10 is operated, and the squeegee 2 is reciprocated in the direction of arrow Y shown in FIG. Thereby, squeegee 2
5, the cream solder is squeezed while moving zigzag on the upper surface of the print mask 20 as shown in FIG. Here, the squeegee angle θ in the zigzag locus drawn by the squeegee 2 can be arbitrarily determined by the squeegee's squeezing speed in the arrow X direction and the moving speed in the reciprocating movement in the arrow Y direction.

At this time, the squeegee 2 is provided with a solder press 2a for pressing the cream solder toward the print mask 20, and a plurality of triangular grooves 2b are formed in the solder press 2a. Therefore, in the printing press 1, the cream solder is moved in the moving plane of the squeegee 2 during squeezing in the moving direction of the squeegee 2 (in the direction of arrow X in FIG. 1) and in a direction perpendicular to the moving direction (in the direction of arrow Y in FIG. 1). Roll to For this reason, even if the printing mask 1 has holes formed in the printing mask 20 that become the printing pattern in any direction, the cream solder easily enters the holes, and the printing unevenness in the printing pattern printed on the circuit board is increased. Is suppressed.

In order to verify this, as shown in FIG. 6, a large number of holes 20a having a width W = 0.5 mm serving as a printing pattern are formed on a printing mask 20 having a thickness of 2 mm. When a conventional printing press without the reciprocating mechanism 10 for the squeegee 2 is used and the hole 20a of the print mask 20 which is the print pattern to be printed on the QFP is long in the squeezing direction (A pattern), In the case where the length is long in the direction perpendicular to the direction (B pattern), the indentation depth d (mm) of the cream solder S was measured for about 100 holes 20a, and the average value was obtained. Table 1 shows the results.

[0028]

[Table 1]

As is evident from the results shown in Table 1, in the printing machine 1 of the present invention, there is no direction in printing the printing pattern, the indentation depth of the cream solder is deeper than that of the conventional printing machine, The occurrence of uneven printing was suppressed.

Therefore, in the printing press 1, by adjusting the reciprocating speed of the squeegee 2 by the reciprocating mechanism 10, the squeegee angle θ shown in FIG.
It is also possible to adjust the depth (mm) in which the cream solder is pushed into the holes 20a of the print mask 20. In the above description, the cream solder printing machine has been described as an example, but this is merely an example, and it is clear that the present invention can be similarly applied even if the paste ink to be printed is not particularly cream solder. A printing machine that prints another paste-like ink is also included in the scope of the present invention.

Also, a mechanism using a rack and a pinion is exemplified as the simplest and preferable means for reciprocating the squeegee in a direction parallel to the longitudinal direction of the squeegee. It goes without saying that a similar mechanism can be configured by using the above-described mechanism. Claims 1, 3, and 4 of the present invention also include these.

Furthermore, as an example of the form of the paste ink press, a case where a triangular groove is provided is shown. However, a side wall is perpendicular to the longitudinal direction of the squeegee and perpendicular to the surface facing the mask of the ink press. The object of the present invention is achieved by providing a plurality of grooves inclined from the above, and the shape may be a triangular shape, a semicircular shape, or a wavy shape.

[0033]

As is apparent from the above description, according to the paste ink printer of the present invention, paste ink can be printed on a circuit board regardless of the direction of a print pattern.
Moreover, the occurrence of printing unevenness can be suppressed. At this time, since the second reciprocating mechanism includes the rack, the pinion, and the motor that drives the pinion to rotate, the squeegee can be smoothly reciprocated. In addition, since the reciprocating mechanism has a simple structure, the reciprocating mechanism has an advantage that it can be easily incorporated into an existing paste ink printing machine and that an existing printing mask can be used.

The squeegee is provided with an ink press for pressing the paste-like ink toward the mask, and a surface of the ink press facing the mask has a side wall orthogonal to a longitudinal direction of the squeegee, and Since a plurality of grooves whose side walls are inclined from the vertical direction are formed, the paste ink rolls not only in the squeegee direction but also in the reciprocating direction of the squeegee, and the printing is performed in the printing mask. The pressing force to the holes serving as the pattern increases, and the occurrence of printing unevenness is further suppressed.

[Brief description of the drawings]

FIG. 1 is a plan view showing a main part of a paste ink printer according to the present invention.

FIG. 2 is a front view of the printing press of FIG.

FIG. 3 is a sectional view of a squeegee used in the printing press of FIG. 1 as viewed from a side.

FIG. 4 is a front view of the squeegee of FIG. 3;

FIG. 5 is a model diagram showing a movement locus of a squeegee in the printing press shown in FIG. 1;

FIG. 6 is an explanatory diagram for modelly explaining a depth of pushing cream solder by a squeegee into a hole serving as a printing pattern of a printing mask in the printing press of the present invention.

FIG. 7 is a perspective view showing a direction orthogonal to a direction parallel to a longitudinal direction of a squeegee in a conventional paste ink printer.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Paste ink printer 2 Squeegee 2a Solder presser 2b Groove 3 Guide rail 4 Moving table 4a Nut 5 Mounting plate 6 Air cylinder 7 Elevating guide 8 Squeezing mechanism (first reciprocating mechanism) 8a Ball screw 8b Squeegee motor 10 Reciprocation Moving mechanism (second reciprocating mechanism) 11 Rack 12 Pinion 13 Motor 20 Print mask

Claims (4)

[Claims] 1. A paste for printing on an object to be printed placed on the lower surface of a mask by squeezing a paste-like ink supplied to the upper surface of a mask having a printed pattern formed thereon by a squeegee in contact with the upper surface of the mask. A first reciprocating mechanism for reciprocating the squeegee in a direction perpendicular to the squeegee longitudinal direction, and a second reciprocating mechanism for reciprocating the squeegee in a direction parallel to the squeegee longitudinal direction. A paste-like ink printing machine characterized by having: 2. The reciprocating mechanism for reciprocating the squeegee in a direction parallel to a longitudinal direction of the squeegee,
The paste ink printing machine according to claim 1, further comprising a rack, a pinion, and a motor that drives the pinion to rotate. 3. The paste ink printer according to claim 1, wherein the squeegee is provided with an ink presser for pressing the paste ink toward the mask. 4. The paste-like ink printing according to claim 3, wherein a plurality of grooves whose side walls are orthogonal to the longitudinal direction of the squeegee and are inclined from the vertical direction are formed on a surface of the ink retainer facing the mask. Machine.