JPH033295A - Forming method for metal film of through hole - Google Patents

Abstract

PURPOSE:To completely remove excess remaining metal paste in a through hole by raising metal paste in the hole of the state communicating with a passed hole, forming a metal film on the inner wall of the through hole, and then feeding gas from the outside of a vessel toward the inside of the passed hole of the communicating state and the through hole. CONSTITUTION:A through hole 2 is disposed on a passed hole 3a formed at the cover 3 of a vessel 4, and a component element 1 is placed on the cover 3. Then, a cylinder 7 is pressed down. Thus, the surface level of metal paste 5 is raised from a home position H, the paste is discharged from the hole 3a, and then raised in the hole 2 communicating therewith to be filled therein. Thereafter, the cylinder 7 is lifted to return the paste 5 filled in the hole 2 into the vessel 4, and the surface level of the paste 5 is lowered down from the cover 3. Subsequently, a vacuum pump P is driven. Then, a space A is reduced under pressure, and excess paste 5 remaining in the hole 2 is blown by the flowing atmospheric air to be removed from the hole 2.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for forming a metal film on a through hole, which forms a metal film on the inner wall of a through hole provided in a component body.

' and i For example, when forming a metal film on the entire inner wall of a through hole, initially, as shown in FIG. To attach the pins, use the plate 10, and immerse the bottle 11 side in a paste bath 12 made by melting the desired metal, or as shown in the figure, to attach the pins, use the plate 10 by immersing the entire plate 10.
Attach the paste 13 around or all over the bottle 11,
A metal film was formed on the entire inner wall of the through hole 2 by inserting the pin 11 to which the paste 13 was attached into the through hole 2.

By the way, when using the above method, strict precision is required for the clearance between the through hole and the bottle. In other words, if the clearance is small, a part of the paste 13 on the tip end of the pin 11 will enter the through hole 2, as shown in FIG.
The lower entrance part of the through hole 2 is scraped off.
This is because a large amount of paste is applied to the lower side, but it is not applied to the upper side, or even if it is applied, only a small amount is applied.

However, if the upper side is left uncoated, after drying, turn the component body 1 upside down and apply the paste again in the same way to ensure that the paste adheres to the entire inner wall of the through hole. It was inconvenient because it required two coats.

Furthermore, when forming metal films on various component bodies with different through-hole diameters, lengths, etc., it is necessary to prepare many plates for pin mounting designed according to each component body, which is unnecessary. It was not only economical but also complicated to manage. This means that in order to form many through holes in one component body at the same time in one process, pin mounting with pins corresponding to the positions of each through hole is recommended when using a plate. becomes more prominent.

Furthermore, since the top of the paste bath is open, the solvent evaporates and the paste viscosity gradually increases, which requires control and management.

Therefore, in order to solve the various difficulties mentioned above, the applicant of the present application
For example, as shown in FIG. 10, a component element is placed on the lid 3 of a container 4 whose upper surface is closed with a lid 3 in which a through hole 3a is formed so that the through hole 2 and the through hole 3a are in communication. The body 1 is positioned, and then the metal paste 5 stored in the container 4 is pressurized by a cylinder 7 that communicates with the container 4 via a communication pipe 6, so that the metal paste 5 is inserted into the through hole 3a and the through hole 3a. Raise the inside of the upper through hole 2, and
proposed a method of forming a metal film on the inner wall (patent application 1983)
-310436).

However, in the case of the proposed method, although the metal film can be formed in the through-hole, excess metal paste remains in the through-hole, and there is a possibility that the thickness of the metal film cannot be made constant.

The present invention was made in view of such circumstances, and not only can it prevent excess metal paste from remaining in the through-hole, but it also eliminates the need for high-precision machining of the equipment used. Another object of the present invention is to provide a method for forming a metal film on through-holes that allows for easy alignment, allows application in the same way for through-holes with different diameters, and suppresses changes in paste viscosity. .

The present invention is directed to a method of forming a metal film on the inner wall of a through hole provided in a component body. Position the component body so that the holes and through-holes communicate with each other, and then reduce the atmospheric pressure acting on the bath surface of the metal paste stored in the container, or pressurize the metal paste below the bath surface. Then, the metal paste is raised in the through hole and the through hole above it, a metal film is applied to the inner wall of the through hole, and then the bath surface of the metal paste is lowered below the lid, and finally, It is characterized by allowing gas to flow from the outside of the container to the inside of the container through the through-holes and through-holes that are in communication with each other.

Production - November 1 In the present invention, by adjusting the atmospheric pressure acting on the bath surface of the metal paste stored in the container, or by increasing or decreasing the pressure in the metal paste part below the bath surface, the metal paste is The through-hole is used as a simple passageway to enter and exit the container. If the component body is placed on the lid in such a state that the through hole through which entry and exit is performed and the through hole are in communication with each other, the metal paste can be raised and lowered within the through hole.

Therefore, in this state, the metal paste is raised to form a metal film inside the through hole, and then the metal paste is lowered below the lid, and then the metal paste is poured into the through hole and the through hole in communication from the outside of the container to the inside. When gas is passed through,
This flowing gas blows away the excess metal paste remaining in the holes.

Furthermore, since the metal paste is stored in a substantially sealed container, evaporation of the solvent and the like can be prevented.

The present invention will be explained in detail below. FIG. 1 is a side sectional view showing the state of implementation of the present invention. Reference numeral 1 in the figure is a component body in which, for example, circular through holes 2 are provided at a plurality of predetermined positions. placed on top. Here, the component body 1 corresponds to a circuit board provided with through holes, a multilayer board partially including electronic components such as a multilayer capacitor, and the like. A plurality of through holes 3a having substantially the same inner diameter as the through holes 2 are formed in advance in the lid 3 in accordance with the position and number of the through holes 2.

One end of a communication pipe 6 is attached to the side wall of the container 4, and a pressure regulator, for example, a cylinder 7, is attached to the other end of the communication pipe 6. When this cylinder 7 is pushed down, melt is released inside the container 4, etc. The bath level of the metal paste 5 stored in this state rises from the fixed position H and is pushed out through the through hole 3a, and when it is pulled up conversely, the bath level of the metal paste 5 can be lowered to the fixed position H. It has become.

A suction hole 9 is opened in the side wall portion of the container 4 above the fixed position H, and a suction device, for example, a vacuum pump P is attached to the other end of a suction pipe 20 whose one end is connected to the suction hole 9. and when this vacuum pump P is operated,
The inside of the container 4 can be suctioned. A door (not shown) is provided at the opening inside the container of the suction hole 9 so as to be openable and closable, and is closed when the metal paste rises to prevent the metal paste from entering the suction hole 9.

Next, a case will be described in which a metal paste is formed only on the inner wall of a through hole by the method of the present invention using such an apparatus. First, the component body 1 is placed on M3 so that the through holes 2 are located above the through holes 3a formed in accordance with the position and number of the through holes 2. Regarding this positioning, it is not necessary to precisely align the through hole 3a and the through hole 2, it is only necessary that the through hole 3a and the through hole 2 are at least partially overlapped and communicated with each other as shown in FIG.
Doesn't require much precision.

Next, after closing the opening/closing door (not shown), the cylinder 7 is pushed down as shown in FIG. As a result, the bath surface of the metal paste 5 rises from the fixed position H, is pushed out from the through hole 3a, and then rises to fill the inside of the through hole 2 communicating therewith. The rising height of this metal paste 5 is made to approximately match the same height as the upper end of the through hole 2. Therefore, metal paste 5
is in contact with and adheres to the entire inner wall of the through hole 2.

Thereafter, as shown in FIG. 4, the cylinder 7 is pulled up to return the metal paste 5 contained in the through hole 2 into the container 4, and the bath surface of the metal paste 5 is lowered below the lid 3. As a result, a space A is created between the bath surface of the metal paste 5 and the lid 3.

After that, the opening/closing door (not shown) is opened and the vacuum pump P is driven. Then, the pressure in the space A is reduced, and gas, in this case, the atmosphere outside the container (atmospheric atmosphere), flows from the outside of the container toward the inside through the through hole 2 and the through hole 3a, which are in communication with each other.

As a result, the excess metal paste 5 remaining in the through hole 2 is blown away by the flowing atmosphere, removed from the through hole 2, and returned to the container 4. In addition, lid 3
It is preferable to use a material to which the metal paste 5 does not easily adhere, or to perform a surface treatment on the through hole 3a portion to prevent the through hole 3a from being blocked by the metal paste 5 adhesion.

When forming metal paste on the entire inner wall of through-hole 2 in this way, the through-hole only needs to function as a passage, so the diameter of the through-hole should be the same as that of through-hole 2 as described above. It is not necessarily necessary, as long as it has a minimum size that allows the paste to flow through. Further, it is not necessary to provide one through hole for each through hole 2, but a plurality of small through holes 3a set as shown in FIG. 5 may be provided for each through hole 2. I don't mind.

In addition, if the metal paste is to be formed not only on the inner wall of the through hole but also on the upper and lower edges as shown in Fig. 6, the diameter of the through hole should be set to a desired size larger than the diameter of the through hole. After that, the through hole is positioned in a part of this through hole, the component body is placed, and then the paste is raised and lowered in the same manner. However, regarding the upper edge, the paste is slightly overflowed from the upper end of the through-hole to form a heaped-up shape (indicated by a broken line), and then returned to the container.

In addition, for component bodies 1 with different positions and numbers of through holes, lids with through holes formed according to the positions and numbers are prepared in advance, and the corresponding lids are attached to the container 4. It's good to do.

In this embodiment, the component body 1 is placed directly on the lid 3, but the present invention is not limited thereto.As shown in FIG. The metal paste may be formed in the through-hole in the same manner by pasting and holding the component body 1 in a pressed state from above. By doing this, even if there is a warp in the M33, it is possible to prevent the paste from getting around to the bottom surface of the component body 1, and it is possible to reliably form a metal film without contaminating the component body 1. Become.

In the above embodiment, the pressure inside the container 4 is reduced to allow gas to flow through the through holes, but the gas flow through the through holes is not limited to this method, and other methods may also be used. For example, the gas may be blown from above the lid.

Further, in the above embodiment, the metal paste is deposited in the through hole by pushing down and pulling up the cylinder 7, and then returned to the container, but the present invention is not limited to this, and the container 4 portion is housed in a vacuum case. The other end of the communication tube 6 is placed outside the vacuum case, and the pressure inside the vacuum case is reduced using a vacuum pump or the like to suck up the metal paste inside the container 4 from above the lid 3, and then the pressure inside the vacuum case is increased. Of course, it is also possible to return the metal paste into the container 4.

Furthermore, in the present invention, a plurality of component bodies 1 are placed side by side on the lid 3, and a metal film is formed in the through-hole portion as described above, thereby performing multi-processing on a plurality of component bodies at the same time. Is possible.

13B As described in detail above, in the case of the present invention, the metal paste is raised into the through hole that is in communication with the through hole,
After a metal film is formed on the inner wall of the through-hole, gas is passed through the through-hole and the through-hole from the outside of the container to the inside of the container. In addition to being able to make the image uniform in the vertical direction and improving quality, there are other effects as follows.

(1) By controlling the time that the metal paste is allowed to rise in the through hole, the thickness of the metal film can be adjusted, which eliminates the need for two coats depending on the thickness when applying mechanically with a pin. can be avoided and productivity can be improved.

(2) For component bodies with different through-hole diameters and positions, prepare lids with corresponding through-holes in advance, and place the corresponding lids on top of the container. good. In addition, since the through hole basically functions as a passage, if only the diameter is different, especially if the through hole is made smaller than the through hole, the same lid can be used for both purposes. Holes can be easily drilled with a machine, eliminating the need for high-precision machining.

(3) Since the through-hole basically functions as a passage, coating is possible as long as the through-hole is at least within the diameter of the through-hole, which eliminates the need for highly accurate positioning.

(4) Even if the length of the through hole is different, it is easy to apply the metal paste to the desired area by simply controlling the amount of extrusion.

(5) Since the paste is contained in a nearly sealed container and only the through-holes are in contact with the atmosphere, the paste viscosity hardly changes due to evaporation of the solvent. Therefore, paste viscosity must be controlled. This can be made unnecessary and the quality of the formed metal film can be stabilized.

[Brief explanation of drawings]

Fig. 1 is a side cross-sectional view showing the implementation state of the present invention, Fig. 2 is a cross-sectional view showing an example of alignment between a through hole and a through hole in the case of the present invention, and Fig. 3.4 explains the method of the present invention. 5 is a perspective view showing another example of the through hole that can be used in the present invention together with the through hole, and FIG. 6 is a side sectional view showing the inner surface and upper and lower edges of the through hole according to the present invention. FIG. 7 is a cross-sectional view showing the case of forming a metal film, which is suitable for the present invention.
A cross-sectional view showing a lid with an elastic sheet pasted on the top surface, FIG. 8 is a side cross-sectional view showing the conventional technique, FIG. 9 is a side cross-sectional view used to explain the problem with the conventional technique, and FIG. 10 is a side cross-sectional view showing the conventional technique. FIG. 3 is a side cross-sectional view used to explain a method proposed by a person. DESCRIPTION OF SYMBOLS 1... Part element body, 2... Through hole, 3... Lid, 3a... Through hole, 4... Container, 5... Metal paste, 7... Cylinder (pressurizing/decreasing device) ), 9... Suction hole, P... Vacuum pump.

Claims (1)

[Claims] (1) In a method of forming a metal film on the inner wall of a through hole provided in a component body, the through hole and the through hole communicate with each other on the lid of a container whose top surface is closed with a lid in which a through hole is formed. Then, the atmospheric pressure acting on the surface of the metal paste bath stored in the container is reduced, or the metal paste below the bath surface is pressurized to penetrate the metal paste. The inside of the hole and the through-hole above it are raised, a metal film is applied to the inner wall of the through-hole, and then the bath surface of the metal paste is lowered to below the lid, and finally the through-hole in communication with the metal film is applied. A method for forming a metal film in a through-hole, the method comprising passing gas through the through-hole from the outside of the container toward the inside.