JPH08183155A - Method and apparatus for paste printing - Google Patents

Abstract

PURPOSE: To facilitate printing of paste without causing defects such as blurring, bridging, etc., even when a printed pattern of the paste is made minute. CONSTITUTION: A platy mask 6 wherein an opening part 8 is formed at a specific position is placed on a printed surface. Printing paste 4 is added onto the mask 6. The printing paste 4 is developed on the mask 6, and filled into the opening part 8. Thereafter, the mask 6 is separated from the printed surface, and the printing paste filled in the opening part 8 is left as the paste is stuck onto the printed surface. In that case, vibration wherein its amplitude increases gradually just after the mask 6 starts to be separated from the printed surface of printed matter, is added to the mask 6. As a vibrator 7, a piezoelectric vibrator is used, which is fitted directly to the mask 6.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a paste printing method and apparatus for printing a printing paste such as cream solder on a circuit board.

[0002]

2. Description of the Related Art When a printing paste such as cream solder is printed on a circuit board, the opening is formed by a stainless plate or electroforming in which openings are punched by means such as etching according to a pattern for printing the printing paste on the circuit board. A plate-shaped mask made of a nickel plate or the like having a perforated portion is used. The mask is attached to the lower surface of the screen stretched on the screen frame and held by the screen frame.

When a printing paste is printed on a circuit board using such a mask, the circuit board, which is a printed matter, is placed on a printing table having a flat surface, and the mask supported by the screen frame is used as the circuit board. Place it on the print side of. Then, a printing paste is applied to the upper surface of the mask, the blade edge of the squeegee is pressed against the upper surface of the mask, and thus the lower surface of the mask is pressed against the printed surface of the printed matter, while the squeegee slides on the upper surface of the mask. As a result, the printing paste on the mask is developed and the opening is filled with the printing paste. Next, the mask and the printed matter are separated from each other vertically, and the printing paste filled in the opening of the mask is left on the circuit board. As a result, the printing paste is printed at a predetermined position on the circuit board.

[0004]

In recent years, circuit boards have become smaller and smaller, and circuit patterns have become finer.
For this reason, the land electrodes and the like of the circuit pattern are also small and dense, and the printing paste such as cream solder printed thereon is also compact. Along with this, the openings of the mask are also miniaturized.

For example, a lead pitch of 0.3 on a circuit board.
mm quad flat package parts (QFP parts: package parts with lead terminals led out in all directions), the land electrode is 150 μm wide and 150 μm wide
Will be arranged at intervals of. Under such a situation, a printing defect of the printing paste, for example, a blur of the pattern or a defect such as a bridge connecting adjacent patterns is likely to occur.

Such printing defects of the printing paste are mainly due to defective filling of the printing paste in the openings of the mask and poor plate separation of the printing paste from the mask when the mask and the printing surface of the printed matter are separated from each other. It is caused by. The former is a defect that occurs because a predetermined amount of the printing paste is not filled in the opening of the mask, which causes a blur of the printing pattern. The latter is a defect caused by the fact that when the mask is separated from the printing surface, the printing paste filled in the opening is separated from the printing surface while being attached to the edge of the opening of the mask. This may cause the print pattern to be scratched or bridged.

The present invention solves the above problems in the conventional paste printing method and apparatus, and enables printing of the printing paste without causing defects such as scrapes and bridges even when the printing pattern of the printing paste is made fine. An object is to provide a paste printing method and apparatus.

[0008]

In order to achieve the above object, according to the present invention, the mask is vibrated when the opening of the mask is filled with the printing paste and when the mask is separated from the printing surface. did. Moreover, the vibration pattern was appropriately selected in each case. As a result, the opening 8 of the mask 6 can be reliably filled with the printing paste 4, and the printing paste 4 filled in the opening 8 can be easily separated from the mask.

That is, in the paste printing method according to the present invention, the plate-shaped mask 6 having the opening 8 formed at a predetermined position.
Is placed on the printing surface, the printing paste 4 is applied on the mask 6, the printing paste 4 is spread on the mask 6 and filled in the opening 8, and then the mask 6 is separated from the printing surface. This is a method of leaving the printing paste 4 filled in the openings 8 on the printing surface as it is, and is characterized in that the mask 6 is vibrated when the mask 6 is separated from the printing surface. Here, it is preferable that the vibration applied to the mask 6 starts immediately after the mask 6 starts to separate from the printing surface of the printed material a, and thereafter the amplitude gradually increases. Further, when the printing paste is filled in the opening 8 of the mask 6, the mask 6 is vibrated. The vibration applied to the mask 6 at this time is preferably a vibration having a constant amplitude.

Next, the paste printing apparatus according to the present invention is
A plate-shaped mask 6 having an opening 8 formed at a predetermined position,
A support base 13 that supports the printed material a under the mask 6 to receive the printed surface, and the support base 13 is moved up and down relative to the mask 6, and the mask 6 contacts the printed surface of the printed material a. And a mechanism for separating the print paste, a print paste supply mechanism for applying the print paste 4 onto the mask 6, and the mask 6
Of the squeegee 10 that slides along the upper surface of the squeegee to spread the printing paste 4 applied to the upper surface and fills the opening 8 with the squeegee. It is characterized by having a vibrator 7. This oscillator 7 is directly attached to the mask 6, and it is preferably a piezoelectric oscillator.

[0011]

In the paste printing method according to the present invention, when the mask 6 is separated from the printing surface, the mask 6 is vibrated, so that the separation of the printing paste 4 filled in the opening 8 of the mask 6 from the mask 6 is promoted. As a result, the printing paste 4 is reliably separated from the edge of the opening 8 of the mask 6. Therefore, even if the mask 6 having the minute openings 8 is used, the printing paste 4
The so-called plate separation is improved, and as a result, defects such as scrapes and bridges in printing are eliminated.

In particular, since the mask 6 is not vibrated until the mask 6 starts to separate from the printing surface of the printed material a, and the vibration is started immediately after that, the printed material a is not directly vibrated. Therefore, the printing paste 4 attached to the printing surface of the printed matter a is not disturbed and is not peeled off from the printing surface. Further, when the mask 6 is initially separated from the printing surface, a small vibration is applied, so that the printing paste 4 with which the opening 8 of the mask 6 is filled does not shake significantly and the pattern accuracy is not disturbed. Then, as the mask 6 moves away from the printing surface of the printed material a, the amplitude of vibration applied to the mask 6 is gradually increased.
Is quickly separated. Then, at this time, since the mask 6 is already separated from the printing surface of the printed material a, there is no fear of degrading the pattern accuracy.

Further, when the printing paste is filled in the opening 8 of the mask 6, the mask 6 is vibrated, so that the vibration softens the printing paste 4 filled in the opening 8 and the viscosity thereof temporarily changes. And is leveled in the opening 8. As a result, the printing paste 4 becomes the opening 8
It is filled uniformly without bias. Therefore, it is preferable that the vibration applied to the mask 6 for such a purpose is a steady vibration having a constant amplitude.
It is possible to fill the wiring printing paste 4 in a uniform state.

Since the paste printing apparatus according to the present invention has the vibrator 7 which gives the mask 6 a vibration whose amplitude changes, when the mask 6 is separated from the printing surface as described above or inside the opening 8 of the mask 6. A required vibration can be applied to each mask 6 when the printing paste is filled.

Since the vibrator 7 is directly attached to the mask 6, it is possible to accurately and surely apply the necessary vibration to the mask 6 when needed. In particular, when a piezoelectric vibrator is used as the vibrator 7, it is convenient because the amplitude can be made constant or increased / decreased and can be freely controlled by changing the drive voltage applied thereto.

[0016]

Embodiments of the present invention will now be described specifically and in detail with reference to the drawings. FIG. 1 shows the entire paste printing apparatus according to an embodiment of the present invention. As shown in this figure, a printed circuit board a is placed on the flat upper surface of the printing table 13. The printing table 13 has a vacuum suction means (not shown) for fixing the printed material a on the upper surface thereof. A fixed positioning 17 and a movable positioning 18 are provided on both sides of the position on the printing table 13 where the printed matter a is placed, and the movable positioning 18 is movable as shown by an arrow. Fixed positioning 17 and movable positioning 1
By sandwiching the printed matter a between the printed matter a and the printed matter 8, the position on the plane is fixed at a predetermined position. Further, the printing table 13 is provided with an elevating mechanism for elevating the upper surface thereof.

On the printing table 13, a screen 11 is horizontally stretched slightly apart from the printed surface of the circuit board a, and the screen 11 has a rectangular screen frame 12.
It is stretched with a certain amount of tension applied inside. A plate-shaped mask 6 made of stainless steel or the like is attached to the lower surface of the central portion of the screen 12. As shown in FIG. 2, the mask 6 has an opening 8 at a position where the printing paste 4 such as cream solder is printed on the printed surface of the circuit board a. A vibrator 7 composed of a piezoelectric vibrator or the like is attached to the lower surface of the end portion of the mask 6, and the vibrator 7
A drive power source (not shown) is connected to.

A guide rail 3 is erected on the mask 6 from the upper surface of the printing table 13 at a constant height, and a slider 1 is attached via a guide bush 2 slidably supported by the guide rail 3. Has been. A plurality of guide rails 3 are installed in parallel in the front and rear of FIG. 1, and the slider 1 is installed in a state orthogonal to these guide rails 3 and slides in the longitudinal direction thereof. An elevating mechanism 5 such as an air cylinder is installed on the slider 1 as an elevating mechanism, and the tip of a plunger that expands and contracts in the vertical direction of the elevating mechanism 5 is connected to a squeegee support 9. Furthermore, the squeegee 1 made of an elastic member such as urethane rubber is directed downward from the squeegee support 9.
0 is provided. The squeegee 10 has a blade-like shape with a narrow lower side, and is a long member in the front-back direction of FIG. As the slider 1 moves left and right in FIG. 1, the squeegee 10 also reciprocates in the same direction.

A guide rail 15 is installed so as to be orthogonal to the guide rail 3, and a slider 16 is slidably attached to the guide rail 15. Below the slider 16, a printing paste nozzle 14 connected to a syringe pump or the like (not shown) is attached. The print paste nozzle 14 reciprocates in the front-rear direction in FIG. 1 as the slider 16 reciprocates along the guide rail 15.

When a printing paste is printed on a printed matter a such as a circuit board by using such a paste printing apparatus, first, the printed board a is placed on the printing table 13 with the printing surface facing upward, and the printed matter is printed. It is positioned by sandwiching a between the fixed positioning 17 and the movable positioning 18, and is held by negative pressure so as not to move. The mask 6 held on the screen 11 is arranged right above the printed material a in a predetermined positional relationship. Next, while moving the print paste nozzle 14 along the guide rail 15 from the back to the front in FIG. 1, the print paste such as cream solder is discharged from the tip of the nozzle 14 to mask a predetermined amount of the print paste. It is applied in the shape of a strip at the end of. After that, the printing paste nozzle 14 retracts to the back side of FIG.

Subsequently, the printing table 13 is raised, and the printing surface of the printed matter a is raised just below the mask 6. The squeegee 10 is located at the right end of the mask 6 in FIG. 1, and is lowered by the elevating / lowering drive unit 5 so that the tip of the squeegee 10 is brought into contact with the right end of the mask 6 in FIG. When the squeegee 10 is further lowered, the mask 6 is resisted against the tension of the screen 11.
The lower surface of the printed material is applied to the printed surface of the printed material a. Then, the squeegee 10 is advanced in the arrow direction. Therefore squeegee 1
The printing paste is spread on the upper surface of the mask 6 at the leading edge of 0. At this time, a driving AC voltage is applied to the vibrator 7 from the driving power supply, the vibrator 7 vibrates, and this vibration is directly transmitted to the mask 6. The vibration of the vibrator 7 at this time is preferably a standing wave having a constant amplitude and frequency, as shown in FIG.

When the printing paste 4 is spread on the upper surface of the mask 6 by the squeegee 10 in this manner, the opening 8 of the mask 6 is sequentially filled with the printing paste 4 as shown in FIG. Then, the mask 6 is formed by the vibrator 7.
The printing paste 4 filled in the opening 8 is softened by the vibration applied to the, and its viscosity is temporarily reduced, and the printing paste 4 is leveled in the opening 8. As a result, the printing paste 4 is evenly filled in the openings 8 without unevenness. When the squeegee 10 moves to the left end in FIG. 1, the squeegee 10 is raised by the elevating / lowering drive unit 5 and returns to the right end side in FIG. At this point, the vibration of the vibrator 7 is temporarily stopped.

FIG. 3A shows a state in which the opening 8 of the mask 6 is filled with the printing paste 4 in this manner, and the vibration of the vibrator 7 is stopped at this time. Next, FIG.
As shown in (b), the printing table 13 begins to descend, and the mask 6 begins to separate from the printing surface of the printed material a. At this time, the vibrator 7 starts to vibrate again, and this vibration is transmitted to the mask 6. This vibration is preferably such that the amplitude gradually increases, as shown in FIG. In FIG.
Indicates a short time from when the mask 6 starts to separate from the printing surface of the printed material a to when the vibration of the vibrator 7 starts.

As described above, the vibrator 7 does not vibrate until the mask 6 starts to separate from the printing surface of the printed matter a, and the vibrator 7 starts to vibrate immediately after that, so that the printed matter a has Vibration does not reach directly. Therefore, the printing paste 4 attached to the printing surface of the printed matter a is not disturbed and is not peeled off from the printing surface. Since the amplitude of the vibration applied to the mask 6 is gradually increased as the mask 6 moves away from the printing surface, the printed material a is not affected by the vibration and only the mask 6 is vibrated. The paste 4 is reliably separated.

FIG. 3C shows a state in which the mask 6 is separated from the printing surface of the printed matter a. By applying the vibration as described above, the printing paste 4 does not separate from the printing surface of the printed material a, and surely separates from the mask 6.

[0026]

As described above, according to the present invention, the opening 8 of the mask 6 can be uniformly filled with the printing paste 4, and the so-called printing paste 4 becomes the printed matter a when the so-called printing paste 4 is released from the plate. Mask 6 attached to the printing surface
Be sure to stay away from Therefore, even if the openings of the mask 6 are miniaturized, good printing paste can be printed without causing defects such as so-called scrapes and bridges.

[Brief description of drawings]

FIG. 1 is a partial vertical schematic side view showing an entire paste printing apparatus according to an embodiment of the present invention.

FIG. 2 is an enlarged cross-sectional view of a main part when the printing paste is filled in the opening of the mask of the paste printing apparatus according to the embodiment.

FIG. 3 is an enlarged cross-sectional view of an essential part from when the opening of the mask of the paste printing apparatus according to the embodiment is completely filled with the printing paste to when the mask is separated from the printing surface of the printed matter.

FIG. 4 is a chart showing an example of a vibration pattern of a vibrator in the paste printing apparatus according to the embodiment from when the opening of the mask is filled with the printing paste to when the mask mask completely separates from the printing surface of the printed matter.

[Explanation of symbols]

 4 Printing Paste 6 Mask 7 Transducer 8 Mask Aperture 10 Squeegee 13 Support Stand a Printed Material

Continuation of front page (51) Int.Cl. ⁶ Identification number Office reference number FI technical display location H05K 3/34 505 C 8718-4E

Claims (8)

[Claims] 1. A plate-shaped mask (6) having an opening (8) formed at a predetermined position is placed on a printing surface, and a printing paste (4) is applied onto the mask (6). (4) is developed on the mask (6), and the opening (8) is formed.
And then remove the mask (6) from the printing surface,
In a paste printing method in which the printing paste (4) filled in the opening (8) is left attached on the printing surface, the mask (6) is vibrated when the mask (6) is separated from the printing surface. And paste printing method. 2. The vibration applied to the mask (6) when the mask (6) is separated from the printing surface is started immediately after the mask (6) starts to separate from the printing surface. Paste printing method. 3. The paste printing method according to claim 1, wherein the vibration applied to the mask (6) when the mask (6) is separated from the printing surface is a vibration whose amplitude gradually increases. 4. The paste printing according to claim 1, wherein the mask (6) is vibrated when the printing paste is filled in the opening (8) of the mask (6). Method. 5. The vibration given to the mask (6) when the printing paste is filled in the opening (8) of the mask (6) is a vibration having a constant amplitude. Paste printing method. 6. A plate-shaped mask (6) having an opening (8) formed at a predetermined position, and a support for supporting a printed material (a) toward a print surface under the mask (6). Table (13)
And a mechanism for moving the support base (13) up and down relative to the mask (6) to bring the mask (6) into contact with and away from the printing surface of the printed matter (a), and printing on the mask (6). The printing paste supply mechanism for applying the paste (4) and the mask (6) are slid along the upper surface of the mask (6) to spread the printing paste (4) applied to the upper surface and fill the opening (8). A paste printing apparatus having a squeegee (10), characterized in that it has a vibrator (7) for applying a vibration whose amplitude changes to the mask (6). 7. The paste printing device according to claim 6, wherein the vibrator (7) is directly attached to the mask (6). 8. The paste printing apparatus according to claim 6, wherein the vibrator (7) is a piezoelectric vibrator.