JPS60239091A - Screen printing machine - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a screen printing machine for producing thick film circuits which can be used in radios, televisions, video tape recorders and the like.

Conventional structure and problems thereof FIG. 1 shows an example of a thick film circuit. The thick film paste printed on the alumina substrate 1 is dried and fired to form a thick film conductor layer 2. A thick film resistor 3 is formed. Thick film paste for conductors is generally composed of silver-palladium alloy powder, glass frit, resin binder, organic solvent, etc. Further, the (7) thick film paste for resistors uses ruthenium oxide instead of silver-palladium, and is otherwise composed of approximately the same material as the paste for conductors. A chip capacitor 4 is connected to the thick film conductor layer 2 by solder 6 on the alumina substrate 1 . With the recent demand for downsizing of electronic devices, there is an increasing need for circuit boards used therein to be downsized and highly integrated. Therefore, from the conventional general board that fully utilizes only one side as shown in FIG. 1, to the one shown in FIG. Double-sided thick film circuits have come into use.

The screen printing machine used in the conventional manufacturing process of double-sided thick film circuits has a board thickness of 0.5ffff to 0.5ffff, as shown in Figure 3.
Q. A stage 10 for fixing a 6MM alumina substrate 1 to the substrate
Place the silver-palladium paste 2 on the ink cartridge 7.
Spread it on the screen 8 in advance, and use one squeegee 9 to vacuum the circuit section 1 of the board 2 through the suction port 11.
A method of applying conductive paste 2 into the through holes 3 and 6 is generally practiced. However, in this method, the paste is spread over the entire surface of the screen, and when the squeegee starts suction while descending, the entire surface of the screen is attracted to the substrate, the paste is sucked from the patterned part of the screen, and the paste adheres to the emulsion 12, causing all the bleeding to occur. It is the cause. Furthermore, if the suction force is reduced in order to reduce the amount of paste smudged out, the smudges in the pattern area tend to decrease, but there is a problem in that the paste is not sufficiently coated within the through-holes. As shown in FIG. 4, in conventional screen printing, the suction force is maximum at the beginning and end of printing, and decreases as it approaches the latter. First, the above-mentioned problem occurred because the suction force was not constant during printing.

Furthermore, since a hydraulic cylinder is used as the drive source for the squeegee, the squeegee speed changes slightly due to changes in the fat content of the oil, making it impossible to print with high precision.

OBJECTS OF THE INVENTION The object of the present invention is to provide a screen printing machine that solves the above-mentioned drawbacks and simultaneously prints the conductor pattern on the substrate and coats the conductor inside the through-holes, thereby eliminating smearing on the conductor pattern and increasing the reliability of the through-holes. That is.

Structure of the Invention The screen printing machine of the present invention includes a stage for fixing a board, which is provided to fix a board and to be able to draw vacuum from one side of the board, and a stage for fixing the board, which can be brought into contact with the other side of the board, and a stage for holding a conductor. It has a screen on which a paste If can be placed, and a pair of squeegees each operating in only one direction, which can be applied to the substrate by vacuum suction of the substrate fixing stage through the conductor paste T screen on the screen. The suction pressure is constant from the start of printing to the completion of printing, and a substrate with high printing accuracy can be obtained.

DESCRIPTION OF EMBODIMENTS An embodiment of the present invention will be described with reference to FIG. Board size 10
0mmX100mmX90tmm, diameter is 0.6φ
An alumina substrate 1 having through-holes 6 of mm in diameter was set on the substrate fixing stage 10, and while suctioning with a vacuum pump from the suction port 11, a silver-palladium paste't screen was applied using a first flat squeegee 9ai with a squeegee down stop of 0.5 mm. 350 mesh stainless steel screen 8 attached to the holding frame 14 f e cm 7
Printing was done at a speed of seconds.

Next, the printed substrate is discharged, a new alumina substrate 1' is set on the substrate fixing stage 1° as shown in FIG. I did screen printing in the same way. Note that a DC servo motor was used as the drive source for the squeegee. Further, the pitch C of the first squeegee and the second squeegee is 40 degrees, and the squeegee angle is 86 degrees from the substrate.

As a result, as shown in Fig. 4, in the screen printing machine according to the present invention, the suction pressure is constant because the paste is not spread on the screen in advance, and the board screen printed with the first squeegee and the second squeegee is a conductor. A substrate with no bleeding in the circuit portion 13 and a through hole formation yield of 100% was obtained.

The squeegee pitch C1 The squeegee angle and squeegee shape from the substrate are not the key points of the present invention; the squeegee pitch is 40ffff and the squeegee angle is 85 degrees.

It is not limited to flat squeegee.

Effects of the Invention As described above, according to the present invention, unlike conventional screen printing machines, the paste is not spread on the screen in advance with an ink return, so the suction pressure is constant, and a substrate with extremely high printing accuracy can be obtained. It will be done. In addition, conventionally, one squeegee was used to print once in one round trip, but since the screen printing machine of the present invention uses a pair of squeegees, it is possible to print twice in one round trip, improving productivity. This is something that can be achieved.

7...-

[Brief explanation of drawings]

Fig. 1 is a sectional view showing an example of a thick film circuit, Fig. 2 is a sectional view showing a thick film circuit using both sides of a substrate, Fig. 3 is a sectional view of a conventional screen printing machine, and Fig. 4 is a sectional view of a conventional screen printing machine. A diagram showing the relationship between the squeegee position and vacuum suction force in a screen printing machine and the screen printing machine of the present invention, FIG. 6 is a sectional view of the printing machine using the first squeegee of the apparatus implementing an embodiment of the present invention, FIG. 6 is a cross-sectional view of the second squeegee during printing. 1... Alumina substrate, 1'... New alumina substrate, 2... Silver-palladium paste, 6
...Through hole, 7 ...Ink return, 8
...Screen, 9...Squeegee, 9&
...First squeegee, 9b... Second squeegee, 10... Stage for fixing substrate, 11.
...Suction port, 13...Conductor circuit section, 14...
...Mounting frame that holds the screen. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 1
Figure 3 Figure 4 Skishii Ritsuka - Figure 5

Claims (1)

[Claims] A board fixing stage that fixes the board and is capable of vacuum suction from one side of the board, a screen that can come into contact with the other side of the board and on which a conductor paste can be placed, and a A screen printing machine comprising a pair of squeegees each operating in only one direction, capable of applying conductive paste to the substrate by vacuum suction of the substrate fixing stage through a gold screen.