JP2002001913A - Method and device for screen printing - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method and a device for screen printing that can print in minute parts easily and cheaply. SOLUTION: The device is provided with squeegees 6a and 6b that fill the penetration holes 2a of fixed pattern formed in a screen 2 with a print material 5 supplied on the screen 2 that is superimposed on a body to be printed 3 and ultrasonic wave vibration means 7a and 7b for giving ultrasonic wave vibration to the screen 2. The means 7a and 7b are installed to convey the ultrasonic vibrations to the squeegees 6a and 6b. After filling the penetration holes 2a with the print material 5 and giving the ultrasonic wave vibrations to the screen 2 through the squeegees 6a and 6b from the means 7a and 7b or separating the screen 2 from the printing body 3 by giving the ultrasonic wave vibrations, the device finishes printing by separating the print material 5 inside the penetration holes 2a from the inside of the penetration holes 2a and leaving it on the printing body 3.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a screen printing method and apparatus for improving the removability of a printing material from a screen by applying ultrasonic vibration to the screen when the screen is separated from a printing medium.

[0002]

2. Description of the Related Art In screen printing, a printing material supplied on a screen opposite to a printing material in a state where a printing material and a screen having through holes formed in a predetermined pattern are overlapped and in contact with each other. Is pushed out through the through-hole by a squeegee moving along the upper surface of the screen, and thereafter, the printing material is separated from the screen and the printing material is removed from the through-hole and left on the printing material by leaving the screen. How to print.

For example, it is used when printing a solder paste (also referred to as solder paste or cream solder) on the wiring of a printed wiring board. Electronic components are mounted on the solder paste printed on the wiring, and the solder paste is heated and melted to connect the electronic components and the wiring (reflow soldering).

In recent years, with the increase in the number of fine components in electronic circuits and high-density mounting, the size of through holes formed in screens has become very small, and printing materials in the through holes have been printed. It is becoming difficult to completely transfer it to a wiring board. That is, as shown in FIG. 5, when separating the printing medium 3 and the screen 2, the through holes 2
There is a problem that the printing material 5a adheres and remains on the inner surface a, and the amount of the printing material 5b on the printing medium 3 becomes insufficient, and a pattern formed by the printing material 5b is chipped.

In order to solve this problem, for example, Japanese Patent Application Laid-Open
In JP-A-246005 and JP-A-6-106705, ultrasonic vibration is applied to the screen prior to the separation between the screen and the printing medium, or the screen is separated from the printing medium while applying the ultrasonic vibration. Thus, it is possible to improve the removability of the printing material in the fine through-hole portion.

[0006] In Japanese Patent Application Laid-Open No. Hei 5-246005, a worker or a robot directly touches a vibration head of an ultrasonic vibration unit to a screen by a gripping operation. In addition, an ultrasonic vibration head (comprising an ultrasonic vibrator and a horn) is mounted movably up, down, left and right, and the vibration of the ultrasonic vibrator is transmitted to the screen via the horn.

[0007]

In the above conventional example, the vibration is transmitted by the ultrasonic vibration head which comes into contact with the screen with a relatively small contact area. Therefore, when the through-hole patterns are distributed over a wide area on the screen, vibration cannot be efficiently transmitted to all the through-holes without unevenness. Vibration is not sufficiently transmitted through the through-hole located far from the contact point of the ultrasonic vibration head, so that the printing material may not be able to be completely removed from the through-hole.

Japanese Patent Application Laid-Open No. 6-106705 discloses that an ultrasonic vibration head is moved to vibrate a plurality of locations, or a plurality of ultrasonic vibration heads are provided at locations where vibration is required. However, it takes time and effort to move one ultrasonic vibration head to vibrate a plurality of locations, and providing a plurality of ultrasonic vibration heads increases the size, complexity and cost of the apparatus.

The present invention has been made in view of the above problems, and has as its object to provide a screen printing method and apparatus that can easily and inexpensively print fine parts.

[0010]

In order to solve the above-mentioned problems, according to the screen printing method of the present invention, a screen having a through hole of a predetermined pattern is superimposed on a printing medium, and a printing material is formed on the screen. The printing material is filled into the through hole of the screen using a squeegee, and after the filling, after applying ultrasonic vibration to the screen through the squeegee or while applying ultrasonic vibration, To transfer the printing material in the through-hole to the printing medium.

According to a third aspect of the present invention, there is provided a screen printing apparatus, comprising: a squeegee for filling a printing material supplied on a screen superimposed on a printing medium into through holes of a predetermined pattern formed on the screen; Ultrasonic vibration means for providing ultrasonic vibration, the ultrasonic vibration means is provided to be able to transmit ultrasonic vibration to the squeegee,
After filling the through-hole with the printing material, after applying ultrasonic vibration to the screen through the squeegee from the ultrasonic vibrating means or while applying the ultrasonic vibration, the printing medium is separated from the screen, and printing in the through-hole is performed. Transfer the material to the substrate.

As described above, even if the through-hole pattern is wide, the squeegee can be brought into contact with the screen to fill the through-hole with the printing material. Ultrasonic vibration can be applied to all through-hole portions without unevenness.

[0013]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 3 is a schematic view of a screen printing apparatus 1 according to the present embodiment, and FIG. 1 is an enlarged perspective view of a main part thereof. For example, a printed wiring board 3 as a printing medium
Is placed on a table 4 which can be moved up and down. Then, the screen 2 in which the through holes 2a are formed in a predetermined pattern is positioned on the printed wiring board 3 and is superposed. On the screen 2, the printed wiring board 3
For example, a solder paste 5 is supplied as a printing material on the surface opposite to the surface in contact with the solder paste 5.

Above the screen 2, two squeegees 6a and 6b are arranged. The squeegees 6a and 6b are fitted to lower ends of the squeegee holders 8a and 8b, respectively, and are fixed by bolts 13. Squeegee holder 8a, 8
b can be moved up and down with respect to the slide member 9 that can move in the horizontal direction. That is, the squeegee holder 8a,
Lifting rods 10a, 10a integrally attached to 8b
b is driven by a cylinder (not shown) to move up and down with respect to the slide member 9.

Above each of the squeegee holders 8a and 8b, ultrasonic vibrating means 7a and 7b are provided. The ultrasonic vibrating means 7a will be described. A vibrator 12a which receives an output from an ultrasonic oscillator (not shown) and vibrates ultrasonically, and a tip of the vibrator 12a is brought into contact with the upper surface of the squeegee holder 8a. Horn 1
1a. The vibrator 12a is a piezoelectric element, a magnetostrictive element, or the like, and is housed in a case. The other ultrasonic vibration means 7b is similarly configured.

The ultrasonic vibrating means 7a and 7b are detachable or fixed to the squeegee holders 8a and 8b, and can move up and down with respect to the slide member 9 together with the squeegee holders 8a and 8b. Alternatively, the ultrasonic vibration means 7
Elevating means for a and 7b may be separately provided.

Next, the printing process of the screen printing apparatus 1 configured as described above will be described with reference to FIG.

As shown in FIG. 2A, the slide member 9
Ultrasonic vibration means 7a, 7b, squeegee holders 8a, 8b
And is moved horizontally with the squeegees 6a and 6b,
It is positioned with respect to the screen 2. Thereafter, for example, one squeegee holder 8a descends, and the squeegee 6a attached to the lower end of the squeegee holder 8a contacts the screen 2. Then, as shown in FIG. 2B, the solder paste 5 supplied on the screen 2 is transferred to the through hole 2a of the screen 2 by the movement of the squeegee 6a by the movement of the slide member 9.
Filling into. Thereby, the solder paste 5 is extruded onto the wiring pattern of the printed wiring board 3 through the through holes 2a.

After the squeegee 6a fills all the through holes 2a with the solder paste 5, the squeegee 6
Ultrasonic vibration is applied to a. That is, the vibration of the vibrator 12a is transmitted to the squeegee holder 8a and the squeegee 6a via the horn 11a. Thereby, ultrasonic vibration is given to the screen 2 with which the squeegee 6a is in contact.

Thereafter, as shown in FIG. 2C, the squeegee 6
a moves upward from the screen 2 and the table 4 descends with respect to the fixed base 14. At this time, the screen 2 is kept in its position by the holding means (not shown). 2 leaves. Alternatively, the squeegee 6a is kept in contact with the screen 2, that is, the table 4 is lowered while applying ultrasonic vibration to the screen 2 to separate the printed wiring board 3 from the screen 2.

By applying the ultrasonic vibration to the screen 2, the solder paste 5 in the through hole 2a and the screen 2 cause a minute relative movement, and as shown in FIG. Also, the solder paste 5 can be satisfactorily removed without remaining in the through hole 2a.

The solder paste 5 is formed in all the through holes 2a.
Ultrasonic vibration is applied to the screen 2 via a squeegee 6a that is in contact with the screen 2 over a wide range in order to fill the screen. Therefore, vibration can be transmitted over a wide range without unevenness. In addition, the squeegee is a member originally provided in the screen printing apparatus, and simply attaches a conventionally known ultrasonic vibration means to the squeegee so that ultrasonic vibration can be transmitted to the squeegee, so that the mechanism is simple and the cost is low. can do. In addition, if the horn resonance phenomenon is used, even ultrasonic vibration having a small output can be transmitted while being enhanced.

Although the embodiments of the present invention have been described above, the present invention is, of course, not limited thereto, and various modifications can be made based on the technical concept of the present invention.

In the above embodiment, the present invention is applied to the printing of the solder paste on the printed wiring board. However, the present invention is not limited to this, and may be applied to other screen printing, for example, the formation of circuit wiring on an IC board.

Further, in the above embodiment, the ultrasonic vibration is transmitted to the squeegee holder via the horn, but the ultrasonic vibrator may be directly applied to the squeegee holder or the squeegee. When the size of the squeegee holder or squeegee is small and the ultrasonic vibrator cannot be directly attached, it is effective to use a horn. Further, the number of squeegees is not limited to two.

[0027]

According to the screen printing method according to the first aspect of the present invention or the screen printing apparatus according to the third aspect of the present invention, the ultrasonic vibration can be uniformly applied to the screen over a wide range with a simple configuration and at a low cost. And enables good printing on fine parts.

[Brief description of the drawings]

FIG. 1 is an enlarged perspective view of a main part of a screen printing apparatus according to an embodiment of the present invention.

FIG. 2 is a diagram showing a screen printing process according to an embodiment of the present invention, wherein A shows a process of filling a printing material into a through hole by a squeegee, and B shows a squeegee after the printing material is completely filled into the through hole. Shows a step of applying ultrasonic vibrations to the screen through the screen, and C shows a step of separating the screen and the printing medium.

FIG. 3 is a schematic perspective view of a screen printing apparatus according to an embodiment of the present invention.

FIG. 4 is a diagram showing good removability of a printing material from a through hole in a screen printing method according to an embodiment of the present invention.

FIG. 5 is a view showing poor removability of a printing material from a through hole when no ultrasonic vibration is applied to a screen.

[Explanation of symbols]

1. Screen printing device 2. Screen 2a
... Through hole, 3 ... Printed object, 4 ... Table 5, 5 ... Printing material, 6a ... Squeegee, 6b ... Squeegee, 7a ...
... Ultrasonic vibrating means, 7b ... Ultrasonic vibrating means, 8a ...
Squeegee holder, 8b Squeegee holder, 9 Slide member, 11a Horn, 11b Horn, 12
a: Ultrasonic vibrator, 12b: Ultrasonic vibrator.

Claims (4)

[Claims] 1. A screen in which a predetermined pattern of through-holes is formed is superimposed on a printing medium, a printing material is supplied on the screen, and the printing material is filled into the through-holes using a squeegee. After filling the holes with the printing material, after applying the ultrasonic vibration to the screen or while applying the ultrasonic vibration, the printing medium and the screen are separated from each other. A screen printing method, wherein the screen printing method is detached from an inner surface and is left on the printing medium, wherein ultrasonic vibration is applied to the screen via the squeegee. 2. The screen printing method according to claim 1, wherein the ultrasonic vibration is transmitted from the ultrasonic vibrator to the squeegee via a horn. 3. A squeegee for filling a printing material supplied on a screen superimposed on a printing medium into through holes of a predetermined pattern formed on the screen, and an ultrasonic wave applying means for applying ultrasonic vibration to the screen. After the filling of the printing material into the through-hole, after applying the ultrasonic vibration to the screen by the ultrasonic vibration means or while applying the ultrasonic vibration, the printing medium and the screen In a screen printing apparatus, the printing material in the through-hole is separated from the inner surface of the through-hole and is left on the printing medium. The ultrasonic vibration unit can transmit ultrasonic vibration to the squeegee. A screen printing apparatus provided with the squeegee and applying ultrasonic vibration to the screen via the squeegee. 4. The screen printing according to claim 3, wherein the ultrasonic vibrating means includes an ultrasonic vibrator and a horn for transmitting ultrasonic vibration of the ultrasonic vibrator to the squeegee. apparatus.