JPH01313995A - Through hole printing equipment - Google Patents

Abstract

PURPOSE:To uniformize the spreading of print paste on the inner wall surface of a through hole by installing a funnel-type vacuum chamber to roughly straighten the air flow at the time of sucking the air in the vacuum chamber, or a vacuum chamber provided with a straightening vane in a funnel type vacuum chamber. CONSTITUTION:A vacuum chamber 6 is in the form of a funnel; the air flow for sucking or dischaging is straightened in accordance with approach to a discharging vent 7; in the vacuum side 1b of through holes 11, 12 covered with a screen 2 just before printing, and a through hole 13 covered with print paste 4' just after printing, a large negative pressure generates, not only by the pressure difference between the air of the upper surface 1a of a circuit board 1 and the vacuum chamber 6 side, but also by the generation of Karman vortex phenomena; the print paste 4' is intensely sucked and spread on the inner wall surface of the through hole to surely form the through holes 11-14; after the through holes 11-14 are formed, the air is discharged along an air channel in the vacuum chamber 6. Thereby the spreading of print paste on the inner wall of the through hole can be uniformized.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a through-hole printing device, and particularly to a vacuum chamber suitable for reliably and stably forming printing paste on the inner wall surface of a through-hole by vacuum suction. The present invention relates to a through-hole printing device having a through-hole printing device.

[Conventional technology]

Conventional through-hole printing devices include, for example, Japanese Patent Application Laid-open No. 60-1
As described in Publication No. 32386, an exhaust hole is provided in the substrate support of a screen printing device, the pressure in the exhaust hole is detected by a pressure sensor, and a control circuit opens and closes a throttle valve to adjust the exhaust amount of the exhaust device. A technique is known in which through-hole printing can be performed with high yield under the same suction conditions over the entire surface of a large-sized substrate. That is, although the above-mentioned publication describes vacuum suction for obtaining a through hole, it does not describe the structure or shape of the vacuum chamber.

[Problem to be solved by the invention]

The above-mentioned conventional technology is effective in reducing the difference in suction vacuum pressure between the surface to be printed and the opposite surface of the circuit board when there are many through holes per unit area of the circuit board or when there are many variations in the diameter of the through holes. Only by using
No consideration was given to air flow during the operating time of the squeegee in the screen printing mechanism, and the printing paste was applied unevenly to the inner wall surface of the through hole, making it impossible to reliably obtain the through hole.

The present invention was made in order to solve the problems of the prior art described above, and it is possible to reduce the flow of air in the vacuum chamber to the exhaust port, especially for circuit boards with a large number of holes and variations in hole diameter. To provide a through-hole printing device that reduces resistance by rectifying current, strengthens suction of printing paste by eddy current under a circuit board, uniformizes application of printing paste to the inner wall surface of a through-hole, and reliably forms a through-hole. That,
That is the purpose.

[Means to solve the problem]

In order to achieve the above object, the configuration of the through-hole printing apparatus according to the present invention includes a screen printing mechanism, a circuit board as a printing medium placed on the side of the screen printing mechanism, and a vacuum chamber formed inside. In a through-hole printing apparatus that is equipped with a support stand having an exhaust port on the side opposite to printing and an exhaust device connected to the exhaust port, and applies printing paste to the inner wall surface of the through-hole of a circuit board by vacuum suction, the support stand is A circuit board is placed on the top of the vacuum chamber, an exhaust port is opened at the bottom of the vacuum chamber, and the vacuum is shaped so that the flow of air sucked and exhausted in the vacuum chamber from the back of the circuit board to the exhaust port is rectified. It forms a chamber.

Further, a rectifying plate is provided in the vacuum chamber to rectify the flow of air sucked and exhausted within the vacuum chamber.

As an additional note, the above purpose is to provide a vacuum chamber with a funnel-shaped shape that macroscopically rectifies the air flow when suctioning the air in the vacuum chamber during through-hole printing, or to create a vacuum chamber with a funnel-shaped shape This is achieved by providing a vacuum chamber equipped with a rectifying plate.

[Effect]

Generally, in through-hole printing, the circuit board is placed on a support stand, and during printing, the air in the vacuum chamber formed inside the support stand is sucked and exhausted from the exhaust port using an exhaust device such as a vacuum pump or pump. A conductor layer is formed by applying negative pressure to the lower surface (background) on the side opposite to printing, and applying suction to the inner wall of the through hole with the printed printing paste.

In the through-hole printing device of the present invention, the vacuum chamber has a funnel-like shape, and the flow of suction and exhaust air becomes rectified as it approaches the exhaust port, and the through-hole is covered with a screen immediately before printing and the printing paste immediately after printing. On the vacuum side between the through holes covered by the circuit board, there is not only a pressure difference between the atmosphere on the top surface of the circuit board and the vacuum chamber side, but also a Karman vortex phenomenon, which creates a strong negative pressure, which attracts the printing paste even more strongly. A printing paste is applied to the inner wall surface of the through hole to ensure the formation of the through hole, and after the through hole is formed, it is evacuated along with the air flow inside the vacuum chamber.

〔Example〕

Hereinafter, each embodiment of the present invention will be explained with reference to FIGS. 1 to 4, and an embodiment of the prior art will be explained with reference to FIG. 5.

FIG. 1 is a configuration diagram of main parts of a through-hole printing apparatus according to an embodiment of the present invention, and FIG. 2 is a vertical cross-sectional view of the vacuum chamber of FIG. 1 showing air flow during through-hole printing. .

In Fig. 1, "C, l" is a printed circuit board,
is a screen that constitutes a screen printing mechanism; 3 is a screen that constitutes a screen printing mechanism;
A squeegee 4 constitutes a screen printing mechanism, and 4 is a printing paste.

5 is a support stand that supports one circuit board 1, 6 is a vacuum chamber, and 7 is an exhaust port. That is, the support stand 5 has the circuit board 1 placed on the upper part of the support stand (at the upper part of the vacuum chamber) so as to face the screen printing mechanism, and has an exhaust lower opening at the lower part of the support stand (at the lower part of the vacuum chamber) to create a vacuum inside. A chamber 6 is formed therein. Then, C1, this vacuum chamber 6 is located on the lower surface (back) of the circuit board lb.
The vacuum chamber 7 is shaped so that the flow of air sucked and exhausted in the vacuum chamber from the exhaust lower to the exhaust lower becomes rectified as it approaches the exhaust lower.
For example, as shown in FIG. 1, the vacuum chamber 6 has a funnel-like shape.

The circuit board 1 has through holes 11, 12, 13, and 14 for electrical connection between both sides of the board.

7' is an exhaust pipe, 8 is a control valve, 9 is a vacuum pump, 10
is an electric motor that drives the vacuum pump 9, and these constitute an exhaust device connected to the exhaust lower.

In this way, this device has through holes 11°12.13
, and 14 is placed on the support stand 5, and printing paste 4 is printed on the upper surface 1a of the circuit board 1 while moving the squeegee 3 in the direction of the arrow through the screen 2. The lower exhaust lower, exhaust pipe 7', and control valve 8 are connected to a vacuum pump 9, and the air inside the vacuum chamber 6 is sucked and exhausted.

FIG. 2 shows a situation in which the squeegee 3 performs printing while moving in the direction of the arrow, and also sucks and exhausts air from the vacuum chamber 6 from the exhaust lower. Solid arrows indicate air flow.

As shown in Figure 2, the atmosphere is exposed to the through hole 11 before printing.
The printing paste 4' flows into the through hole 14 that penetrates after printing, is rectified at the exhaust lower part, and is sucked and exhausted, and the through hole 12 covered with the screen 2 immediately before printing and the upper surface 1a immediately after printing are covered with printing paste 4'. On the lower surface 1b of the covered through-hole 13, the flow of air in the vacuum chamber 6 creates a strong negative pressure due to the Karman vortex phenomenon, which locally strongly attracts the printing paste 4', penetrating the hole and forming the conductor layer. A through hole is formed, and after passing through, the atmosphere above the circuit board 1 is sucked in, and the flow of air in the vacuum chamber 6 is rectified toward the exhaust lower.

Compared to the above, the air flow in a conventional box-shaped vacuum chamber is as shown in FIG.

FIG. 5 is a longitudinal sectional view showing air flow in a vacuum chamber in a conventional through-hole printing device.

In the figure, parts with the same symbols as in Figure 2 are equivalent parts, so
The explanation will be omitted.

A conventional vacuum chamber 6' shown in FIG. 5 is box-shaped and has a plurality of exhaust lowers a and 7b opened at the bottom.

When the squeegee 3 prints while moving in the direction of the arrow and sucks and exhausts the air in the vacuum chamber 6' from the exhaust lowers a and 7b, the air flow in the vacuum chamber 6' becomes turbulent and the circuit board 1 is Since a stable vortex is not generated in the lower part of the lower surface 1b, it is not possible to reliably form a through hole.

As described above, according to the present embodiment shown in FIGS. 1 and 2, the air flow inside the vacuum chamber is rectified at the exhaust port to reduce resistance, and under the circuit board, the printing paste is generated by the eddy current. After passing through the through-hole, the speed of the air flow increases due to the rectification effect, which makes the printing paste evenly applied to the inner wall of the through-hole, and further strengthens the vortex flow on the bottom of the non-penetrated part, creating a negative pressure. This strengthens the suction of the printing paste and ensures the formation of through holes that will become conductive layers. The above enables through-hole printing with a low defect rate and shortening of takt time.

Next, FIG. 3(a) is a vertical cross-sectional view of a vacuum chamber provided with a rectifying plate according to another embodiment of the present invention, and FIG. 3(b) is a longitudinal sectional view taken along the line X-X in FIG. 3(c) is a vertical sectional view of a vacuum chamber in which a circuit board is placed, and FIG. 4(a) is a sectional view of a vacuum chamber provided with a rectifying plate according to still another embodiment of the present invention. The longitudinal cross-sectional view of the chamber, FIG. 4(b), is a cross-sectional view taken along the YY arrow in FIG. 4(a). In each figure, parts with the same reference numerals as those in FIG. 1 are equivalent parts, so a description thereof will be omitted.

In the embodiment shown in FIGS. 3(a) and 3(b), a grid-like rectifying plate 15 is provided in a funnel-shaped vacuum chamber 6 to rectify the air flow before it reaches the exhaust lower. It is.

Furthermore, in the case shown in FIG. 3(Q), the positions of the grid holes of the rectifying plate 15' are set to match the through holes of the circuit board 1. This example is particularly effective for large circuit boards.

By adding the current plate shown in FIG. 3, the effects of the embodiments shown in FIGS. 1 and 2 can be made more pronounced.

In the embodiment shown in FIGS. 4(a) and 4(b), a spiral rectifier plate 16 is provided in a funnel-shaped vacuum chamber 6 to rectify the air flow before it reaches the exhaust lower. It is.

According to the embodiment shown in FIG. 4, the effects of the embodiments shown in FIGS. 1 and 2 can be made more pronounced.

Note that the current plate is not limited to the embodiments shown in FIGS. 3 and 4, and it goes without saying that a concentric current plate, for example, may be used as long as it provides a rectifying effect before reaching the exhaust port. .

〔Effect of the invention〕

As described above, according to the present invention, the number of holes is particularly large;
In addition, even for circuit boards with uneven hole diameters, the air flow inside the vacuum chamber is rectified at the exhaust port to reduce resistance, and under the circuit board, the suction of the printing paste is strengthened by the eddy current, allowing it to reach the inner wall of the through-hole. It is possible to provide a through-hole printing device that uniformizes the application of printing paste and reliably forms through-holes.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram of main parts of a through-hole printing apparatus according to an embodiment of the present invention, and FIG. 2 is a longitudinal sectional view of the vacuum chamber in FIG. 3(a) is a longitudinal sectional view of a vacuum chamber provided with a rectifying plate according to another embodiment of the present invention, and FIG. 3(b) is a sectional view taken along the line X-X in FIG. 3(a). , FIG. 3(c) is a vertical cross-sectional view of a vacuum chamber in which a circuit board is placed, and FIG. 4(a) is a vertical cross-sectional view of a vacuum chamber provided with a rectifying plate according to still another embodiment of the present invention. 4(b) is a sectional view taken along the Y-Y arrow in FIG. 4(a), and FIG. 5 is a vertical sectional view showing the air flow in the vacuum chamber in a conventional through-hole printing device. be. 1...Circuit board, 1a...Top surface, 1b...Bottom surface,
2... Screen, 3... Squeegee, 4.4' ・
...Printing paste, 5...Supporting stand, 6...Vacuum chamber,
7...Exhaust port, 7'...Exhaust pipe, 9...Vacuum pump, 11,12. , L3゜14...Through hole, 1
5, 15', 16... rectifier plate. Figure 101 Figure Z Figure 3 Figure 4 ((L) .,) ts, ts', (6++- Rectifier plate Figure 5 1et 7!L

Claims (1)

[Claims] 1. A screen printing mechanism, a support base on which a circuit board to be printed is placed on the side of the screen printing mechanism, a vacuum chamber formed inside, and an exhaust port on the side opposite to printing, and an exhaust device connected to the exhaust port. In a through-hole printing device that applies printing paste to the inner wall surface of the through-hole of a circuit board by vacuum suction, the circuit board is placed on the upper part of the vacuum chamber of the support base, and an exhaust port is opened in the lower part of the vacuum chamber. death,
A through-hole printing device characterized in that the vacuum chamber is formed in a shape that rectifies the flow of air sucked and exhausted in the vacuum chamber from the back of the circuit board to the exhaust port.