GB2346584A

GB2346584A - Screen printing apparatus

Info

Publication number: GB2346584A
Application number: GB9928131A
Authority: GB
Inventors: Takehiko Murakami
Original assignee: Minami Co Ltd
Current assignee: Minami Co Ltd
Priority date: 1999-02-16
Filing date: 1999-11-30
Publication date: 2000-08-16
Anticipated expiration: 2019-11-30
Also published as: GB9928131D0; JP2000236405A; GB2346584B

Abstract

A screen printing apparatus is structured such that a printing agent is not left within a screen hole of a mask after printing, having a main body (1) of the screen printing apparatus whose upper side within it is formed as a chamber which can be sealed by setting a mask supporting table as a boundary, and a pressure within the chamber can be ascended and descended at a desired timing by suitable pressure ascending and descending means such as air bags and the like.

Description

SPECIFICATION TITLE OF THE INVENTION SCREEN PRINTING APPARATUS BACKGROUND OF THE INVENTION FIELD OF THE INVENTION The present invention relates to a screen printing apparatus, and more particularly to a screen printing apparatus which is structured such that a printing agent is not left : within a screen hole of a mask after printing.

DESCRIPTION OF THE PRIOR ART A screen printing apparatus is structured such that a mask is arranged on a plate to be printed such as a printed circuit board and the like, a printing agent such as a creamed solder and the like mounted on the mask is expanded by a squeegee, and a printing is performed at a predetermined position of the plate to be printed via a screen hole provided on the mask.

At a time of printing by the squeegee, a printing agent 103 such as a creamed solder and the like within a screen hole 102 of a mask 101 is taken out from the screen hole 102 only by an own weight of the printing agent 103 itself and a adhesive force as shown in Fig. 3 when the plate to be printed is peeled out from the mask in accordance with a downward movement of the plate to be printed such as the printed circuit board and the like, so that a power at a time of the printing g ager. t being taken out therefrom is poor and there is a case in which the printing agent is attached to an inner surface of the screen hole 1C2 and left therein. Further, the printing agent gradually sticks thereto or is expanded around the screen hole at a back side thereof.

Further, there is a case in which the printing agent itself printed on a base plate lacks a sharp property. In this case, reference numeral 104 in the drawing denotes a plate to be printed such as a printed circuit board and the like.

Accordingly, it is necessary to frequently perform a cleaning of the mask while stopping the operation of a machine.

SUMMARY OF THE INVENTION The present invention is made by taking the points mentioned above into consideration, and an object of the present invention is to provide a screen printing apparatus which ? structured such that a printing agent is not left within a screen hole of a mask after printing, thereby dispensing with cleaning of the mask or extending greatly a period required for performing the mask cleaning operation.

In accordance with a gist of the present invention, there is provided a screen printing apparatus comprising the main body of a screen printing apparatus, wherein an upper side within the main body thereof is formed as a chamber which can be sealed by setting a mask supporting table as a boundary, and a pressure within the chamber can be ascended and descended at a desired timing by suitable pressure ascending and descending means.

Further, it is desirable to use an air bag placed at a suitable position within the upper side chamber as the pressure ascending and descending means for the pressure within the upper side chamber of the main body of the screen printing apparatus.

Still further, it is possible to provide a pair of the air bags within the upper side chamber, thereby inflating one of them so as to ascend the pressure and extracting a gas from another air bag after a predetermined time passed so that the pressure may return to the original state.

Furthermore, it is possible to use one air bag and repeat an injection and a discharge of the gas.

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a schematic view of an embodiment in accordance with the present invention; Fig. 2 is a schematic view which explains an operation in accardance vlth the present invention; and Fig. 3 is a schematic view which explains a relation between a screen hole and a printing agent in the case of printing by the conventional apparatus.

DESCRIPTION OF THE PREFERRED EMBODIMENT An embodiment in accordance with the present invention will be described below with reference to the accompanying drawings.

Fig. 1 is a schematic view and Fig. 2 is a schematic view explaining an operation.

In the drawings, reference numeral 1 denotes a main body of a screen printing apparatus. Further, referme. ce numeral 2 denotes a mask supporting table. Then, a main body 1 of the screen printing apparatus forms a chamber la capable of being sealed by setting the mask supporting table 2 as a boundary in an upper side within a main body 1 the screen printing apparatus. In this case, reference numeral lb denotes a lower side chamber. Further, reference numeral 3 denotes a mask, reference numeral 4 denotes a screen hole, reference numeral 5 denotes a printing agent such as a creamed solder and the like, reference numeral 6 denotes a plate to be printed such as a printed circuit board and the like, and reference numeral 7 denotes a squeegee. Then, the plate 6 to be printed is closely attached to a back surface of the screen hole 4 in the mask 3, whereby the upper side chamber la becomes sealed.

Further, the structure is made such that a pressure within the upper side chamber la can be ascended and descended at a desired timing by an operation of air bags 8 and 9. In this case, in accordance with the present embodiment, two air bags are employed, whereby one air bag 9 is set filled with an air in advance and another air bag 8 is set empty and to be injected an air. Further, the air may be injected by known suitable means s such as a pump and the like.

Then, as shown in Fig. 2, the air is injected into the air bag 8 until the printing agent 5 within the screen hole 4 of the mask 3 is taken out from the screen hole 4 at a level of about 80 % thereof, thereby ascending the pressure within the upper side chamber la to a pressure more than the pressure (for example, 1013 hPa) of the lower side chamber lb. In this case the increase in the pressure therein is enough to be a level of about 1126 hPa. Accordingly, the printing agent 5 is totally pressed with force, and the printing agent 5 in an outer peripheral portion is pressed out together therewith and is not left in the inner surface of the screen hole 4. when the printing agent 5 is taken out from the screen hole 4 at about 80 %, the air in the air bag 9 is taken out.

Accordingly, the pressure within the upper side chamber la gradually descends and gradually comes closer to the pressure within the lower side chamber lb. Therefore, the pressure is weakened in the end when the printing agent 5 is taken out from the screen hole 4, so that it is possible to prevent a sudden come-out.

Further, in accordance with the present embodiment, the the air bags are used for ascending and descending the pressure within the upper side chamber la for the following reasons. For example, in accordance with the scope of the present invention, it is possible to increase or decrease the pressure by piercing a hole at a suitable portion of the chamber la and directly injecting the air into the chamber la, however, in this case, a temperature descends due to a slight air blow and there is a risk that the printing agent is oxidized so as to be deteriorated or the printing agent on the plate to be printed is deformed. Accordingly, the air bags are used for completely preventing the above matter.

Further, in accordance with the present embodiment, two air bags are employed, however, it is possible to repeat an injection and a discharge only by one air bag.

Since the present invention is structured in the manner mentioned above, it is possible to make the printing agent not being left within the screen hole of the mask after printing. Accordingly, it is possible to dispense with a cleaning operation of the mask or it is possible to greatly extend the period required for performing the mask cleaning operation.

The reader's attention is directed to all papers and documents which are filed concurrently with or previous to this specification in connection with this application and which are open to public inspection with this specification, and the contents of all such papers and documents are incorporated herein by reference.

All of the features disclosed in this specification (including any accompanying claims, abstract and drawings), and/or all of the steps of any method or process so disclosed, may be combined in any combination, except combinations where at least some of such features and/or steps are mutually exclusive.

Each feature disclosed in this specification (including any accompanying claims, abstract and drawings), may be replaced by alternative features serving the same, equivalent or similar purpose, unless expressly stated otherwise. Thus, unless expressly stated otherwise, each feature disclosed is one example only of a generic series of equivalent or similar features.

The invention is not restricted to the details of the foregoing embodiment (s). The invention extend to any novel one, or any novel combination, of the features disclosed in this specification (including any accompanying claims, abstract and drawings), or to any novel one, or any novel combination, of the steps of any method or process so disclosed.

Claims

WHAT IS CLAIMED IS:

1. A screen printing apparatus comprising a main body of a screen printing apparatus, whose upper side within the main body is formed as a chamber which can be sealed by setting a mask supporting table as a boundary, and a pressure within said chamber can be ascended and descended at a desired timing by suitable pressure ascending and descending means.

2. A screen printing apparatus as claimed in claim 1, wherein said pressure ascending and descending means for the pressure within the upper side chamber of the main body of the screen printing apparatus is formed of an air bag placed at a suitable position within the upper side chamber.

3. A screen printing apparatus as claimed in claim 1, wherein a pair of air bags are provided within the upper side chamber.

4. A screen printing apparatus constructed and arranged substantially as herein described with reference to the accompanying drawings.

4.-A screen printing apparatus as claimed in claim 2, wherein said air bag is constituted by a pair of air'bars provided within the upper side chamber.

5. A screen printing apparatus as claimed in claim 1, wherein only one air bag for injecting and discharging a gas is provided within the upper side chamber.

5. A screen printing apparatus as claimed in claim 2, wherein only one air bag for injecting and discharging a gas is provided within the upper side chamber. 7. A screen printing apparatus constructed and arranged substantially as herein described with reference to the accompanying drawings.

Amendments to the claims have been filed as follows CLAIMS 1. A screen printing apparatus comprising a main of a screen printing apparatus, whose upper side within the main body is formed as a chamber which can be sealed by setting a mask supporting table as a boundary, and a pressure within said chamber can be ascended and descended at a desired timing by an air bag placed at a suitable position within the upper side chamber.

2. A screen printing apparatus as claimed in Claim 1, wherein a pair of air bags are provided within the upper side chamber.

3. A screen printing apparatus as claimed in Claim 1, wherein only one air bag for injecting and discharging a gas is provided within the upper side chamber.