JPH033392A - Paste sucking device for forming through hole - Google Patents

Abstract

PURPOSE:To prevent paste which may possibly short-circuit a circuit pattern on a rear face of a board from being scattered to the rear face by connecting a recess of a base to a negative pressure source through a negative pressure tank and interposing solenoid valves between the tank and the recess of the base, the source. CONSTITUTION:A base 20 is moved in XY-directions, the through hole 11 of a bass 10 to be plotted is disposed directly under the nozzle 4 of a plotting device, and conductive paste is discharged from the nozzle 4 while finely moving the base 20 in the XY-directions with the position as a center, thereby plotting a through hole land part. In this case, a solenoid valve 1 of a suction hole 23 side is closed, a solenoid valve 3 of a negative pressure source 40 side is opened, and a negative pressure tank 2 is held in a negative pressure state. When the land part is completely plotted, the valve 1 is opened, the valve 3 is closed, and negative pressure in the tank 2 is supplied to the recess 22 of the base 20. When the tank 2 becomes the atmospheric pressure, the valve 1 is closed, the valve 3 is opened to introduce the negative pressure from the source 40 into the tank 2, and next through hole part is plotted.

Description

[Detailed Description of the Invention] [Industrial Field of Application] This invention applies negative pressure to the back side of a through-hole substrate by sucking paste discharged from a nozzle of a drawing device directly onto each through-hole portion of a through-hole substrate. The present invention relates to a paste suction device for forming through-holes, which forms a thick film of paste on the inner wall of a hole.

[Conventional technology]

In recent years, in order to improve the density of electronic components, for example, 2-inch square through-hole boards with more than 100 through-holes of 0.3 to 1.0-diameter have been used. .

This type of through-hole board has a large number of through holes drilled in a board made of heat-resistant ceramic material, etc.
A thick film of conductive paste is formed by a direct drawing device on the peripheral through-hole portions including each through-hole on both the front and back surfaces of the substrate, and on the inner walls of the through-holes.

The direct writing device used for this purpose moves the nozzle and the through-hole substrate (hereinafter referred to as the "substrate") relative to each other, and sequentially discharges paste from the nozzle to each through-hole section on the surface of the substrate, thereby forming a land section that covers the through-hole. form,
The through-hole suction system sucks the paste from the back surface of the substrate and draws the paste into the through-holes, forming a thick film of paste on the inner walls of each through-hole.

FIG. 5 shows an example of a paste suction device for forming through holes using such a direct drawing device, in which a substrate 10 having a large number of through holes 11 is drawn in an XY direction (not shown).
It is placed at a predetermined position on a base 20 fixed on a sub-table, and its peripheral portion is connected to a negative pressure source 30 through a substrate suction hole 21.
It is adsorbed and fixed by negative pressure.

Further, a recess 22 of the base 20 covered by the substrate 10 is connected to a negative pressure source 40 via a solenoid valve 41 through a through-hole suction hole 23 .

Then, paste is discharged into the through-hole portion of the substrate 10 from a nozzle of a well-known direct writing device (not shown).
As shown in the enlarged view, the land portion 12 is formed, and the electromagnetic valve 41 is opened to supply negative pressure from the negative pressure 1fi40 to the back surface of the substrate 10, and the paste on the land portion 12 is sucked in the direction of arrow S. By.

A thick film of paste is formed on the inner wall 11a of the through hole.

[Problem to be solved by the invention]

However, in such conventional paste suction devices for forming through-holes, the negative pressure for paste suction was supplied and stopped only by opening and closing a solenoid valve. As shown in FIG. 6, when the solenoid valve 41 was opened, the pressure suddenly rose from atmospheric pressure to the negative pressure of the negative pressure source 40, and when it was closed, the pressure suddenly returned to atmospheric pressure, and the pressure change was extremely rapid. .

Therefore, the thick film of paste formed in the through-hole portion of the substrate 10 is rapidly drawn into the through-hole by the opening of the solenoid valve, and the thick film of paste formed on the inner wall 11a of the through-hole is rapidly drawn into the through-hole.
but f! Even if the solenoid valve is closed, the flow of the paste cannot be suddenly stopped, so as shown in Figure 7, the excess paste scatters to the back side of the board, forming islands 14 and shorting out the circuit pattern drawn on the back side. There was a risk.

SUMMARY OF THE INVENTION An object of the present invention is to provide a through-hole forming paste suction device that solves these conventional problems and prevents paste from scattering to the back surface of a substrate.

[Means to solve the problem]

In order to achieve the above object, the paste suction device for forming through-holes according to the present invention moves the nozzle of the direct writing device and the base on which the through-hole substrate is placed relative to each other, so that In a paste suction device for through-hole formation, which forms a thick film of paste on the inner wall of the through-hole by discharging the paste to the recess of the base by a flow of air generated in the recess of the base by a negative pressure source for suction, the recess of the base is The first. A second solenoid valve is installed.

[For production]

With this configuration, first, the first solenoid valve on the base side is closed, and the second solenoid valve on the negative pressure source side is opened to maintain the negative pressure tank in a vacuum state, and then the direct writing device is used to write the substrate. A land portion is drawn by discharging paste onto the through-hole portion.

When drawing is completed and the first solenoid valve is opened and the second solenoid valve is closed, the negative pressure in the negative pressure tank causes air to flow through the through hole toward the base recess, and the through hole land area The paste is rapidly drawn into the through-hole, forming a thick film of paste on its inner wall.

As a result, the atmosphere that has passed through the through-hole enters the negative-pressure tank, so the inside of the negative-pressure tank gradually approaches atmospheric pressure, and the flow rate and flow rate of the paste flowing into the through-hole stops, causing the inside of the negative-pressure tank to gradually approach atmospheric pressure. When the pressure reaches atmospheric pressure, the movement of the paste also stops.

Therefore, at this point, close the first solenoid valve.

Open the second electromagnetic valve to supply negative pressure to the negative pressure tank again in preparation for the next suction.

By repeating this series of operations, paste is introduced into all the through holes to form through holes.

〔Example〕

Hereinafter, the present invention will be described in detail with reference to FIGS. 1 to 4 of the accompanying drawings.

FIG. 1 shows the configuration of an embodiment of the present invention.
Since the substrate 10 and the base 20 are the same as those shown in FIG. 5, their explanation will be omitted.

In this embodiment, a first electromagnetic valve 1. A negative pressure tank 2 and a second electromagnetic valve 3 are successively installed to form a through-hole suction system.

Note that the capacity of the negative pressure tank 2 is set according to the diameter and number of through holes 11 in the substrate 10.

In the embodiment configured as described above, prior to drawing, the substrate 10 is regulated by a plurality of positioning pins (not shown) and placed in a predetermined position, and the negative pressure source 30 for sucking the substrate passes through the substrate suction hole 21. Negative pressure is applied to the back surface of the substrate, and the suction force causes the substrate 10 to be attracted and fixed to the upper surface of the base 20.

Next, the subsequent processing will be explained with reference to the flowchart shown in FIG. 2 as well as the time chart shown in FIG. 3 as well as FIG.

First, by moving the base 20 in the XY force direction, the through hole 11 of the base 10 to be drawn is positioned directly below the nozzle 4 of the drawing device (not shown), and the base 20 is moved in the XY direction around that position. While making slight movements in the force direction, conductive paste is discharged from the nozzle 4 to draw through-hole land portions.

At this time, as shown in Fig. 3, the first solenoid valve 1 is closed and the second solenoid valve 3 is opened to maintain the negative pressure tank 2 in a negative pressure state. The first solenoid valve 1 is opened and the second solenoid valve 3 is closed to supply negative pressure in the negative pressure tank 2 to the recess 22 of the base 20. As a result, the paste on the through-hole land is strongly drawn into the through-hole 11, and the atmospheric pressure that has passed through the through-hole 11 is introduced into the negative pressure tank 2, causing the negative pressure in the through-hole suction system to gradually increase. approaches atmospheric pressure. FIG. 4 shows this state.

Along with this, the flow rate and flow rate of the paste also decrease,
Finally, when the pressure in the negative pressure tank 2 becomes equal to atmospheric pressure, the movement of the paste also stops.

When the inside of the negative pressure tank 2 reaches atmospheric pressure, the first solenoid valve 1 is closed and the second solenoid valve 3 is opened to supply a negative pressure source 4 inside the negative pressure tank 2.
After introducing negative pressure from 0 and drawing the next through-hole section, the above-described paste suction process is performed again, and this is repeated for all through-holes to complete through-hole formation.

In addition, the discharge and stop of the paste from the nozzle 4 for drawing, the first. The timing of a series of operations such as opening and closing of the second solenoid valves 1 and 3 is all controlled by a microcomputer (not shown). Also.

It is desirable to determine the time from when the inside of the negative pressure tank 2 reaches atmospheric pressure from the start of sucking the paste through actual measurement and to store the data as a parameter in the memory.

In this way, the paste in the through-hole land portion is initially very strongly drawn into the through-hole 11 and forms a thick film of paste on the inner wall 11a of the through-hole, and then the speed gradually decreases and stops, so that the substrate 10 ．． There is no risk of the paste scattering to the back side of the back side, and short circuits of the back side pattern can be prevented.

〔Effect of the invention〕

As described above, according to the present invention, the base concave portion to which the substrate is fixed is connected to the negative pressure source via the negative pressure tank, and the first recess is connected to the base side and the negative pressure source side of the negative pressure tank, respectively. ．． Since the second solenoid valve is installed, these first solenoid valves are interposed. By controlling the timing of opening and closing of the second electromagnetic valve in accordance with the drawing of the through-hole portion, the drawn paste can be sucked from the back surface of the substrate using the negative pressure in the negative pressure tank.

Since the negative pressure is equal to the negative pressure of the negative pressure source at the beginning of suction, it is possible to forcefully draw the drawn paste into the through hole and form a thick film of paste on the inner wall of the through hole. After that, the negative pressure weakens and the paste flow rate and flow rate gradually decrease.

As a result, it is possible to prevent the paste from scattering to the back surface of the substrate, and to eliminate the possibility that the circuit pattern formed on the back surface will be short-circuited by the scattered paste.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention, FIG. 2 is a flow chart showing a through hole forming method, and FIG. 3 is a time chart showing the operation timing of each part. Figure 4 is a diagram showing changes in negative pressure during paste suction;
The figure is a configuration diagram illustrating a conventional paste suction device. FIG. 6 is a diagram showing changes in the negative pressure of the through-hole suction system, and FIG. 7 is an explanatory diagram showing the undesirable state of through-hole formation. 1... First solenoid valve 2... Negative pressure tank 3
...Second solenoid valve 4...Nozzle 10...
・Through hole board 11...Through hole 20・
...Base, 22...Base recess 30...
・Negative pressure source for substrate suction 40...Negative pressure source for through hole suction

Claims (1)

[Scope of Claims] 1. A nozzle of a direct writing device and a base on which a through-hole substrate is placed are moved relative to each other, paste is discharged from the nozzle to a through-hole portion of the through-hole substrate, and a negative pressure source for suction is applied. In a paste suction device for through-hole formation, which forms a thick film of paste on the inner wall of the through-hole by the flow of air generated in the base recess by the air flow, the base recess is connected to the negative pressure source via a negative pressure tank. Paste suction for forming through-holes, characterized in that first and second solenoid valves are interposed between the negative pressure tank and the base recess and between the negative pressure source, respectively. Device.