Cleaning and liquid contact with solids – Processes – Combined
Reexamination Certificate
1998-10-06
2001-04-17
El-Arini, Zeinab (Department: 1746)
Cleaning and liquid contact with solids
Processes
Combined
C134S021000, C015S308000, C015S309200, C015S312100
Reexamination Certificate
active
06217669
ABSTRACT:
This is a national stage application of PCT/JP97/01784 filed May 26, 1997.
TECHNICAL FIELD
The present invention relates in general to a cleaning device for screen masks used in a screen printing device and specifically to a device and a method for cleaning the edges of pattern holes in a screen mask to remove a printing material adhering to said edges.
BACKGROUND ART
Heretofore, for example, in the production of electronic circuit boards, a printing material, such as cream solder, has been used to solder electronic parts, such as chip parts, on a circuit board, and a cream solder printing device has been used to print or apply said cream solder in a desired pattern. Conventional printing of cream solder has been effected by using the following method and device. Referring to
FIG. 4
, the numeral
1
denotes a circuit board;
2
denotes a land to have cream solder
4
printed thereon;
3
denotes a solder resist;
5
denotes a screen mask of metal formed with openings
6
in a desired pattern; and
7
denotes a printing squeegee adapted to make a linear movement on the screen mask
5
.
Cream solder printing comprises the steps of placing a screen mask
5
in position on a circuit board
1
, feeding cream solder
4
onto the screen mask
5
, linearly moving said squeegee
7
in contact with the screen mask
5
under a suitable printing pressure to fill the cream solder
4
into openings
6
in the screen mask
5
, and separating the screen mask
5
from the circuit board
1
, whereby the cream solder
4
is printed or applied on the circuit board
1
in a desired pattern through the screen mask
5
.
In this connection, if the cream solder printing is continuously performed, the cream solder
4
moves around to the back of the screen mask
5
to adhere thereto as shown in
FIG. 4
(
b
).
When such adhering cream solder
4
is transferred to the circuit board
1
, it forms a cause of short circuit or the like. Therefore, usually the printing device is provided with a cleaning device
9
as shown in
FIG. 5
so as to make it possible to remove the adhering cream solder
4
. In this figure, the numeral
10
denotes a cleaning squeegee;
11
denotes a cleaning paper;
12
denotes a cleaning paper supply source; and
13
denotes a cleaning paper winding section. In addition,
8
denotes a frame.
The cleaning operation is performed as follows. First, the cleaning device
9
is moved in its entirety to the position A, where the cleaning squeegee
10
is then lifted until it comes in contact with the screen mask
5
through the cleaning paper
11
. And with this state maintained, the cleaning device
9
is moved toward the position B. When the cleaning device
9
reaches the position B, the cleaning squeegee
10
is lowered, and the portion of the cleaning paper
11
which has been used for cleaning is wound by the cleaning paper winding section
13
while the cleaning paper
11
is fed from the cleaning paper supply source
12
. Thereafter, the cleaning squeegee
10
is lifted again and moved toward the position A in the same manner as described above. When it reaches the position A, the cleaning squeegee
10
is lowered and the cleaning device
9
is returned to its original position to complete the cleaning.
Further, in recent years, in addition to the above arrangement, as shown in
FIG. 6
, there has been proposed an arrangement comprising a cleaning device
14
provided with an air sucking section
15
connected to an air suction mechanism
19
. The numeral
17
denotes a supply source which supplies a cleaning paper
16
and
18
denotes a winding section therefor. In cleaning operation, the air sucking section
15
is moved to the position A and lifted until its front end contacts with the screen mask
5
. With this state maintained, the air sucking section
15
is moved toward the position B along the screen mask
5
to remove the cream solder
4
adhering to the openings and the back of the screen mask
5
. That is, the air sucking section
15
connected to the air suction mechanism
19
is held in contact with the screen mask
5
through the cleaning paper
16
which is air-permeable to the extent that air easily passes therethrough, while the cream solder
4
adhering to the openings
6
is recovered by the cleaning paper
16
through the suction of air. After the cream solder
4
adhering to the openings
6
has been removed in this manner, the suction of air by means of the air suction mechanism is brought to an end and the air sucking section
15
is lowered, whereupon the initial state is restored to complete the cleaning operation.
According to this printing device using air suction, the rate of removal of cream solder
4
can be increased as compared with the cleaning using the cleaning paper
11
alone.
However, even with said conventional printing device used, some amount of cream solder
4
remains on the screen mask
5
, presenting a problem that such remnant results in disfigurement or blur on the print surface. Particularly, the physical properties of the cream solder
4
influence this problem such that if the cream solder
4
has high viscosity, it tends to remain.
The present invention solves the foregoing problem and has an object to provide a cleaning device and a cleaning method that eliminate the possibility of allowing a printing material such as cream solder to be left over on the screen mask.
DISCLOSURE OF THE INVENTION
A cleaning device according to the present invention is used for removing a remnant printing material from a screen mask used in a screen printing process in which a printing material is printed on or applied to the surface of a to-be-printed object through the screen mask having openings formed therein in a predetermined pattern, and comprises suction means for sucking said remnant printing material from the screen mask, reciprocating means for reciprocating said suction means along the screen mask, flow rate selecting means for registering in advance a plurality of values as registered set values for the suction flow rate in said suction means and selecting a suitable suction flow rate from said registered set values according to said object or said printing material, and flow rate variable control means for controlling the suction flow rate in said suction means to make it equal to the suction flow rate selected by said flow rate selecting means, wherein flow control is effected such that a suction flow rate suitable for the type of cream solder to be used and the shape of the openings in the screen mask is properly selected by said flow rate selecting means.
Another cleaning device according to the present invention is used for removing a remnant printing material from a screen mask used in a screen printing process in which a printing material is printed on or applied to the surface of a to-be-printed object through the screen mask having openings formed therein in a predetermined pattern, and comprises suction means for sucking a remnant printing material from the screen mask, reciprocating means for reciprocating said suction means along the screen mask, flow rate selecting means for registering in advance a plurality of values as registered set values for the suction flow rate in said suction means and selecting a suitable flow rate from said registered set values according to said to-be-printed object or said printing material, flow rate variable control means for controlling the suction flow rate in said suction means to make it equal to the suction flow rate selected by said flow rate selecting means and inspecting means for inspecting the printing material printed on or applied to the surface of said object after printing, said flow rate variable control means being further controlled according to the results of the inspection conducted by said inspecting means, wherein the printed surface of said object is inspected after printing and if disfigurement, blur or the like is found in said object, a decision is made that the printing material such as cream solder remains on the screen mask, whereupon the flow rate in the sucki
Masui Masuo
Naito Takao
Sarashina Eigo
Takahashi Ken
El-Arini Zeinab
Matsushita Electric - Industrial Co., Ltd.
Parkhurst & Wendel LLP
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