Metal fusion bonding – Process – Applying or distributing fused filler
Reexamination Certificate
2001-04-24
2004-08-10
Dunn, Tom (Department: 1725)
Metal fusion bonding
Process
Applying or distributing fused filler
C228S025000, C228S033000, C228S043000, C228S214000, C118S200000, C118S209000, C118S313000, C118S413000
Reexamination Certificate
active
06772937
ABSTRACT:
BACKGROUND OF THE PRESENT INVENTION
The present invention relates to viscous material application method and apparatus for applying a viscous material such as adhesive, solder paste or electrically conductive paste to a circuit board or other application object, which is an object to which the viscous material is to be applied, via a screen mask in a specified pattern.
As a conventional viscous material application apparatus, there has generally been known a screen printing apparatus which applies a viscous material
4
such as adhesive or solder paste onto lands
51
of a circuit board or the like, which is the application object
50
, via a screen mask
53
as shown in
FIGS. 12A-12E
.
The screen mask
53
has openings
52
formed as through holes provided in a specified pattern corresponding to the lands
51
of the application object
50
, and the application object
50
is positioned by an unshown table section so as to be in contact with the screen mask
53
as shown in
FIGS. 12A and 12B
. Next, as shown in
FIG. 12C
, the viscous material
4
fed to an end of the screen mask
53
is moved in a specified direction by a squeegee
54
, so that the viscous material
4
is filled into the openings
52
. Next, the application object
50
is separated away from the screen mask
53
as shown in
FIG. 12D
, by which the viscous material
4
within the openings
52
is transferred onto the lands
51
of the application object
50
so that the viscous material
4
is applied onto the lands
51
of the application object
50
as shown in FIG.
12
E.
Also, the inventor has proposed in Japanese Patent Application 10-232164 (Unexamined Japanese Patent Publication 2000-62138) a tightly closed type squeegee including, on a filling unit movable on a screen mask, a chamber which has a tightly closed structure capable of shutting off print paste from the atmospheric air and also has a discharge hole in opposition to the screen mask and which is to be filled with print paste, a pressurizing device for pressurizing the print paste in the chamber to push the print paste out of the discharge hole, a pair of scraper blades which slide in press contact with the screen mask back and forth along the direction of move of the filling unit, a paste tank which forms a part of the pressurizing device and which is removably mountable, and a shutter mechanism which can open and close the discharge hole.
However, in this conventional viscous material application apparatus, since the apparatus adopts a method that the squeegee
54
is moved on the screen mask
53
to thereby fill the viscous material
4
into the openings
52
, and since the viscous material
4
is in contact with the air at all times, the viscous material
4
easily tends to vary in state, causing an issue that stable application becomes unachievable and another issue that the viscous material
4
overflowing the squeegee
54
needs to be scraped into the squeegee
54
.
Also, there is a large amount of know-how for obtaining proper application state, and skilled engineers are necessitated therefor. In particular, it is more difficult to achieve the proper application while recent years' demand for finer pitches of the openings
52
is met and moreover a demand for faster speed is satisfied. This has been a cause of another issue that increasingly larger amount of know-how and skillfulness is required.
On the other hand, in the structure of above-mentioned Japanese Patent Application 10-232164 (Unexamined Japanese Patent Publication 2000-62138), indeed the viscous material
4
does not need scraping up, and moreover the viscous material
4
is kept away from contact with the air, thus preventable from any changes in state. However, since one device is shared for feeding the viscous material toward the discharge hole as well as for imparting a discharge pressure thereto, it is difficult to control the discharge pressure at high precision because of viscous resistance or the like, and moreover the responsivity is poor. As a result of this, there have been an issue that finer pitches and higher speeds cannot be satisfied. Particularly with high-viscosity viscous materials such as solder paste, pressure is highly transferable near the place at which the feeding device and the chamber are communicating with each other, causing the discharge pressure to become higher with the result of greater variations in the discharge pressure, as an issue.
Then, it is conceivable to provide a storage chamber which communicates with the discharge hole and a device which imparts a discharge pressure to this storage chamber, and further to provide a device for feeding the viscous material to the storage chamber. In this case, however, when the viscous material within the storage chamber decreases so that the discharge pressure can no longer be imparted, there arises a need for feeding the viscous material into the storage chamber, which would interrupt the application operation during the feed. This would cause an issue of decrease in productivity. Furthermore, during the feed of the viscous material to the storage chamber by pushing out the viscous material from the feeding device to the storage chamber, the pressure that has arisen to the storage chamber remains (residual pressure), causing a further issue that it becomes difficult to control the discharge pressure at high precision.
Accordingly, in view of these and other issues, an object of the present invention is to provide viscous material application apparatus and method by which a viscous material can be prevented from contact with the air at all times so as to be applied stably, and in which the viscous material never overflows during the operation based on an arrangement that a viscous-material storage chamber provided therefor so as to communicate with a discharge hole is constantly replenished with the viscous material, and also in which even if the viscous material is fed at high pressure so as to reduce the time for feeding the viscous material to the storage chamber, it never affects the discharge control, and further in which the discharge amount by one-time feed of the viscous material can be increased.
SUMMARY OF THE PRESENT INVENTION
In order to achieve the above object, the present invention has the following constitutions.
According to a first aspect of the present invention, there is provided a method for applying a viscous material, by using an application unit having: a storage chamber for the viscous material; a discharge hole, for the viscous material, provided so as to communicate with the storage chamber, where a viscous-material feeding device for feeding the viscous material to the storage chamber is coupled to the application unit; and a discharge-pressure adjusting device for imparting a discharge pressure to the viscous material stored in the storage chamber, the method comprising:
bringing a screen mask having openings corresponding to the application object or the application object itself and the discharge hole of the application unit into contact with each other;
moving either the application unit and the screen mask or the application unit and the application object relative to each other while imparting the discharge pressure to the viscous material in the storage chamber; and
applying the viscous material onto the application object while replenishing the storage chamber at all times with the viscous material by the viscous-material feeding device with a pressure smaller than the discharge pressure imparted by the discharge-pressure adjusting device.
According to a second aspect of the present invention, there is provided a method for applying a viscous material, by using an application unit having: a storage chamber for the viscous material; a discharge hole for the viscous material provided so as to communicate with the storage chamber, where a viscous-material feeding device for feeding the viscous material to the storage chamber is coupled to the application unit; and a discharge-pressure adjusting device for imparting a discharge pressure to the viscous mate
Fujiwara Muneyoshi
Mimura Toshinori
Nagai Yoshiyuki
Onishi Hiroaki
Shirai Jun
Dunn Tom
Edmondson L.
Matsushita Electric - Industrial Co., Ltd.
Wenderoth , Lind & Ponack, L.L.P.
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