JPH0764047B2 - Suction unit for printing machine - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a suction unit for a printing machine, which holds a material to be printed in a screen printing machine.

Conventional technology Conventional screen printing has the following advantages in terms of printing accuracy and reliability.
Manual or semi-automatic machines were mainly used. However, in recent years, such as printed circuit boards (hereinafter abbreviated as boards),
Full-automatic screen printers have begun to spread as they are applied to mass-produced parts. Under such circumstances, a highly reliable method for holding an object to be printed has been studied. For example, as in Japanese Utility Model Publication No. 48-43454, there is a method of pressing and fixing the side surface of the printed material. The structure is shown in FIG. The object to be printed 2 is placed on the table 1 provided with a step having the same depth as the thickness of the object to be printed, and the side surface of the object to be printed 2 is pressed and fixed by the pusher 3 and the roller 4. However, such a fixing method has a drawback that it cannot be applied to a flexible printed circuit board such as a flexible printed circuit board and that it can only be positioned by the end face reference. Therefore, as another method, there is a method of adsorbing and fixing an object to be printed by utilizing a negative pressure suction action.
This method is often used because the shape of the material to be printed is relatively free. FIG. 4 shows a conventional example thereof. Fourth
In the figure, the hose 5 is connected to a negative pressure generation source (not shown), and air is sucked from holes 8a, 8b, 8c passing through the air flow path of the block 6 and formed in the plate 7 to adsorb the print object 9 It is a method of fixing and printing from above. Further, as a measure for improving the above-mentioned method, there is a method of attaching a suction pad as proposed in JP-A-58-219054 or the above-mentioned JP-A-58-36186. A schematic diagram thereof is shown in FIGS. 5 and 6.

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention However, recent printed circuit boards are more and more mounted with electronic components on both front and back surfaces, and as a result, the number of boards having many through holes is also increasing. When screen-printing on a substrate with a large number of through holes, there is a gap between the substrate 10 as the printing object and the suction plate 11 as shown in FIG. , Through the gap and tends to be sucked through the suction holes. As a result, print blurring occurs on the printing material. In particular, if the conductors 13a, 13b, 13c are plated with solder and the conductor is thick, the gap with the substrate surface may be 0.1 mm or more, and the gap may be widened. Sometimes it happened.

As a countermeasure against this, it may be possible to partially hold by the suction pad by the method shown in FIGS. 5 and 6, but there is a drawback that the structure becomes complicated and the cost becomes high by using the suction pad. However, there is a drawback in that all the suction-fixed portions must be changed because the suction position is changed even when the type of the printed material is changed.

Therefore, in view of the above problems, the present invention forms a groove on the surface of the suction unit that contacts the substrate to be printed even when there are relatively many through holes and the suction and holding surface of the substrate to be printed has irregularities. The groove is machined up to the end surface of the suction unit to provide a suction unit that does not cause print blur due to a suction action.

Means for Solving the Problems In order to solve the above problems, the adsorption unit of the present invention is
A groove into which air flows is formed around the suction hole.

By providing the groove, the suction unit according to the present invention prints by causing the air sucked from the gap between the substrate and the suction unit to flow not from the screen side having the printing paste but from the groove side. It is intended to suppress the occurrence of bleeding.

Embodiment An embodiment of the present invention will be described below with reference to the drawings. First
The figure is a perspective view of the suction unit in the embodiment of the present invention. In FIG. 1, 14a and 14b are bolts for attaching to the printer body, and 15a to 15h are vacuum generation sources (not shown).
It is a hole for adsorbing an object to be printed which is connected to. Reference numerals 16a to 16d are grooves forming the air inflow path which is a feature of the present invention.

The operation of the suction unit configured as described above will be described with reference to FIG. FIG. 2 shows the suction unit of FIG.
17 is attached to the main body of the printing machine, and the longitudinal section A-
It is the figure which showed B. In the figure, reference numeral 18 is a material to be printed, which in this case is a substrate having through holes. FIG. 3 is a conceptual diagram of a case where the printing paste 20 is printed on the material to be printed 18 by the pressing force of the squeegee 21 according to the pattern formed on the screen 19. By attaching the air inflow grooves 16a and 16b as shown in the figure, the air that is about to flow in from the gap between the printing object and the suction unit flows from the air inflow groove 16a as shown by the arrow 22, The occurrence of bleeding due to the suction force disappears.

In the present embodiment, in consideration of the machining method of the suction unit, the cross-sectional shape is rectangular, and an example in which the suction unit is processed linearly from the end face to the end face is shown. Other shapes such as a circle and a curved line may be used.

EFFECTS OF THE INVENTION As described above, according to the present invention, the suction unit of the screen printing machine is provided with the groove processing for changing the air inflow path not to the upper side of the material to be printed, but to the lower side, that is, the suction unit side. Printing that is less likely to cause blurring can be enabled at a low price.

[Brief description of drawings]

FIG. 1 is a perspective view of a suction unit in an embodiment of the present invention, FIG. 2 is a sectional view showing a state at the time of printing including the vertical sectional view of FIG. 1, and FIG. FIG. 4 is a vertical sectional view of a conventional example utilizing a negative pressure suction action, and FIGS. 5 and 6 are vertical sectional views of a conventional example improved by attaching a suction pad. The drawing is a longitudinal sectional view at the time of printing showing the problems of the conventional example. 14a, 14b …… Bolts for mounting to the printer body, 15a to 15h
…… Suction holes, 16a to 16d …… Air inlet grooves, 17 …… Suction unit.

Claims (1)

[Claims] 1. A screen printing machine for holding an object to be printed, which has an uneven surface on the printing table and has holes, at a predetermined position on the printing table by a suction unit that sucks negative pressure. A suction unit for a printing press, wherein a groove reaching the end surface of the suction unit is formed in a portion of the suction unit that is in contact with the printed material and that does not include a suction hole formed for negative pressure suction.