JPH06320706A - Screen printing device of cream solder - Google Patents

Abstract

PURPOSE:To obtain a screen printing device of cream solder which enables a printing plate to be separated more efficiently by installing a pressing member for pressing a mask against a substrate when vibration is applied to a vibration means provided on a support table side so as to allow the means to come in contact with the mask. CONSTITUTION:A squeegee 6 becomes separated from a substrate 13 or a transport conveyor 14 when cream solder 21 is applied. In this case, a cylinder 7 presses the squeegee 6 so that its lower end part is positioned far below the upper surface of the substrate 13. Under this state, a piezoelectric element 15 is driven to transmit oscillation to a mask 9 directly. Further, in this case, the squeegee 6 presses the mask 9 to the substrate 13. Consequently, the mask 9 is bound to generate oscillation which results in a deterioration of the structural viscosity, in a part near a pattern hole 9a, of cream solder 21. Thus the cream solder 21 is easily separable from the pattern hole 9a, that is, is apt to stick to a substrate 13 side more easily, which contributes to the separation of a printing plate significantly.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a screen printing apparatus for cream solder, which has good plate releasability.

[0002]

Prior to the surface mounting of electronic components on a board, cream solder is applied to the upper surface of the board by a screen printing device. However, when the board is relatively lowered with respect to the mask and the plate separation is performed, the cream solder in the pattern holes formed in the mask is not completely transferred to the substrate, and the cream solder of the pattern solder is separated after the plate separation. Part of the solder may remain in the pattern hole, and the solder paste on the substrate may be chipped or not transferred at all.

Recently, as the circuit pattern on the substrate has become finer, the pattern holes have become finer. For this reason, the thickness of the mask is relatively increased with respect to the bottom area of the pattern hole, and it becomes more and more likely that the cream solder will be chipped or dropped.

In view of this, a technique has been proposed in which minute vibration is applied to the mask at the time of releasing the plate to improve the plate releasing property (Japanese Utility Model Laid-Open No. 2-131374).

[0005]

However, in this technique, the vibrating means is attached to the mask holder, and a minute vibration is applied to the mask via the mask holder. However, the periphery of the mask is usually supported by the mask holder in a tensioned state by a flexible resin film. Therefore, if such a configuration is adopted, the vibration is blocked by the resin film and is hardly propagated to the mask. Further, the substrate overlaps in the vicinity of the center of the mask, but it is considerably distant from the mask holder to the vicinity of the center of the mask, and it is more difficult for vibration to reach the vicinity of the substrate. Therefore, the above-mentioned conventional technique has a problem that it is difficult to improve the effect of improving the releasability.

In view of the above-mentioned problems, it is an object of the present invention to provide a cream solder screen printing apparatus which can surely improve the releasability.

[0007]

According to the present invention, a vibrating means for applying a minute vibration to a mask is provided on a support table side so as to contact the mask, and the vibrating means applies the mask to the mask when the vibration is applied to the mask. By providing a pressing member that presses against the board,
A screen printing device for cream solder is constructed.

[0008]

According to the above construction, when the substrate is released from the mask, the mask is pressed against the substrate by the pressing member,
The substrate and the mask come into close contact. At the same time, minute vibrations are directly transmitted to the mask from the vibrating means in contact with the mask. As a result, sufficient vibration is applied to the pattern hole and the vicinity of the boundary surface of the cream solder in the pattern hole to reduce the structural viscosity of the cream solder in the vicinity of the boundary surface to perform plate separation.

[0009]

An embodiment of the present invention will now be described with reference to the drawings.

FIG. 1 is a perspective view of a screen printing apparatus for cream solder according to an embodiment of the present invention. Reference numeral 1 denotes a mask holder, and a feed screw 2 is rotatably mounted on the inner side of the mask holder 1 in FIG. 3 is this lead screw 2
A driving motor, 4 is a feed nut screwed to the feed screw 2, 5 is a moving plate connected to the upper portion of the feed nut 4, 6 is a squeegee hung down from the moving plate 5, and 7 is this squeegee 6. Is a cylinder provided with a rod 7a (FIG. 3) for moving up and down. The mask holder 1 also holds a mask frame 8. As shown in FIG. 2, the mask frame 8 supports a mask 9 having a plurality of pattern holes 9a, and the periphery of the mask 9 has a flexible resin film 1
0 holds the mask frame 8 in a tensioned state.

Reference numeral 11 is a base, and 12 is a support table which moves up and down with respect to the base 11 to position the substrate 13 by a pair of transfer conveyors 14 and receive it under the table. A piezoelectric element 15 as a vibrating means is provided integrally with the transfer conveyor 14. An ultrasonic oscillator may be used as the vibrating means. As shown in FIG. 4, the upper end portion of the piezoelectric element 15 slightly protrudes from the upper surface of the transport conveyor 14,
The piezoelectric element 15 is in direct contact with the mask 9, and minute vibrations due to the piezoelectric element 15 are directly transmitted to the mask 9.

As shown in FIG. 3, a rod 16 extends downward from the lower portion of the support table 12, and the rod 16 is slidably inserted into a linear guide 17 provided on the upper portion of the base 11. Support table 12 is base 11
It is supported so that it can move up and down. 18 is a base 11
It is a servomotor provided inside, and its output is transmitted to the screw shaft 19. This screw shaft 19 corresponds to the support table 1
It is screwed into a feed nut (not shown) provided in the No. 2.
Reference numeral 20 is a control unit of the servo motor 18, and the control unit 20 can drive the servo motor 18 to move the support table 12 (that is, the substrate 13) up and down relative to the mask 9.

The cream solder screen printing apparatus according to the present embodiment has the above-mentioned structure. Next, a printing step in which vibration is applied by a piezoelectric element among printing steps using this apparatus will be described. First, as shown in FIG. 5A, the cylinder 7 is driven to move the rod 7a and the squeegee 6 to the arrow N.
Lower in one direction. On the other hand, the servo motor 18 is driven to raise the support table 12 and the substrate 13 in the direction of arrow N2. Next, as shown in FIG. 3B, the motor 3 is driven to move the squeegee 6 in the direction of the arrow N3, so that the cream solder 21 supplied on the mask 9 is
It is applied to the substrate 13 through the pattern holes 9a. Then, when the application of the cream solder 21 is completed ((c) in the figure), the squeegee 6 is placed on the substrate 13 or the conveyor 14.
At this time, the cylinder 7 is pressed so that the lower end of the squeegee 6 is located below the upper surface of the substrate 13. In this state, the piezoelectric element 15 is driven to directly transmit the minute vibration to the mask 9. Moreover, at this time, the squeegee 6 attaches the mask 9 to the substrate 13
Is pressed against. As a result, the mask 9 surely causes a minute vibration, the structural viscosity in the portion of the cream solder 21 near the pattern hole 9a is reduced, and the cream solder 21 easily separates from the pattern hole 9a.
It becomes easier to adhere to the side and very easy to separate.

Next, when the above vibration is sufficiently given, as shown in FIG. 3D, the servo motor 18 is driven to continue the pressing by the squeegee 6 as the pressing member to drive the support table 12 and the substrate 13. Is slowly lowered in the direction of arrow N4. Here, since the support table 12 is lowered to release the plate while the pressing is continued, the speed component that the mask 9 or the like tries to restore at the time of plate release can be suppressed to almost zero, and the plate removal speed can be suppressed. It is possible to prevent the solder paste 21 from cracking or coming off properly. Thereby, the releasability can be made extremely good ((e) in the same figure). In this embodiment, the squeegee 6 also serves as the pressing member, but it goes without saying that another member dedicated to the pressing member may be provided.

[0015]

The screen printing apparatus for cream solder according to the present invention has a vibrating means for applying a minute vibration to the mask.
It is provided on the side of the support table so as to be in contact with the mask, and this vibrating means is provided with a pressing member that presses the mask against the substrate when applying vibration to the mask, thus improving the plate release property,
It is possible to prevent chipping of cream solder.

[Brief description of drawings]

FIG. 1 is a perspective view of a screen printing apparatus for cream solder according to an embodiment of the present invention.

FIG. 2 is a partially enlarged view of a screen mask according to an embodiment of the present invention.

FIG. 3 is a sectional view of an essential part of a screen printing apparatus for cream solder according to an embodiment of the present invention.

FIG. 4 is an enlarged view of a screen printing apparatus for cream solder according to an embodiment of the present invention.

5A is a process explanatory diagram of a screen printing device for cream solder according to an embodiment of the present invention. FIG. 5B is a process explanatory diagram of a screen printing device for cream solder according to an embodiment of the present invention. Process explanatory drawing of a cream solder screen printing device according to one embodiment of the invention (d) Process explanatory drawing of a cream solder screen printing device according to one embodiment of the present invention (e) Cream according to one embodiment of the present invention Other process explanation drawing of solder screen printing device

[Explanation of symbols]

 6 Squeegee 8 Mask Frame 9 Mask 9a Pattern Hole 10 Resin Film 12 Support Table 13 Substrate 15 Piezoelectric Element 21 Cream Solder

Claims (1)

[Claims] 1. A support table for supporting a substrate, a mask frame supported so as to be vertically movable or vertically rotatable relative to the support table, a mask having a plurality of pattern holes, and A screen printing device for cream solder, comprising: a squeegee for applying the cream solder supplied onto the mask to the substrate through the pattern holes by sliding on the upper surface of the mask, wherein microvibration is applied to the mask. A vibrating means is provided on the support table side so as to be in contact with the mask, and when the vibrating means applies vibration to the mask, a pressing member for pressing the mask against the substrate is provided. Solder screen printing device.