JP2002127361A - Method for forming paste thin film layer by squeegee - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for forming a thin film layer by a squeegee capable of reducing a quantity of a paste material to be left out of the squeegee' s moving range when the squeegee changes its moving direction. SOLUTION: On condition that the thin film layer 4 is formed with a method that the paste material is coated and broadened by moving the squeegee 1 on a screen 2, before a moving direction of the squeegee 1 is changed, the squeegee 1 is once set back. Then, after the squeegee 1 is drawn away from an accumulation 3a of the paste material existing in a moving direction of the squeegee, the squeegee 1 is raised and got over the accumulation 3a of the paste material.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a transfer technique for applying a paste material such as a flux or a solder paste to a printed circuit board or the like, and applies a paste material using a squeegee required for this transfer. The present invention relates to a method of forming a paste thin film layer on a screen by spreading.

[0002]

2. Description of the Related Art When mounting electronic components on a printed circuit board or forming electrodes on a semiconductor integrated circuit called a BGA (Ball Grid Array), it is necessary to apply a flux or a solder paste to the electrode portions in advance. As the coating method, a printing method and a pin transfer method are known, but the pin transfer method is frequently used especially in BGA due to advantages in size and maintenance of the apparatus.

In the pin transfer method, as shown in FIGS. 1A and 2, a paste material 3 is thinly spread on a screen 2 using a squeegee 1 to form a paste thin film layer 4 (Japanese Patent Laid-Open No. 3-1066651). After that, the transfer tool 6 having the plurality of pins 5 extending downward is lowered to the paste thin film layer 4, and the paste material 4 a is attached to the tips of the pins 5. Then, as shown in FIG.
The transfer tool 6 is moved to a position above the work 7, the transfer tool 6 is lowered, and the pins 5 are connected to the electrode portions 8 of the work 7.
Then, the paste material is transferred to a predetermined position of the work 7 by being brought into contact with the work.

A uniform paste thin film layer 4 is formed on a screen 2.
In order to form the paste material, as shown in Japanese Patent Application Laid-Open No. 3-1066651, the paste material 3 is flattened in a state in which a hill or pool 3a of a paste material 3 or more is formed in a squeegee 1 in a traveling direction. preferable. Specifically, the squeegee 1 is repeatedly moved to the left and right on the screen 2, and the pool 3 a of the paste material on the screen 2 is spread by the squeegee 1 and flattened. It is preferable to form the layer 4, but conventionally, as shown in FIGS. 3 and 4, when the moving direction of the squeegee 1 is changed to the opposite direction,
The operation of jumping over the peak 3a of the paste material has been performed.

More specifically, immediately after the squeegee 1 pushes the mountain 3a of paste material to one end of the screen 2, the squeegee 1 is raised as shown in FIG. 3, and then the squeegee 1 is advanced to a position over the mountain 3a of paste material. After that, it is lowered, and as shown in FIG.
The operation of pushing and spreading in the opposite direction of a was performed.

However, the hills or pools 3a of the paste material formed in the direction of travel of the squeegee 1 are shown in FIGS.
As shown in the figure, when the squeegee 1 rises, a part of the squeegee 1 is attached to the squeegee 1 and carried away.
Squeegee 1
The problem that the paste material 3b attached to the squeegee 1 is left outside the moving range of the squeegee 1 is likely to occur.

Due to such a phenomenon, the paste material 3 on the screen 2 cannot be sufficiently spread on the screen 2 and it becomes difficult to maintain a predetermined thickness of the paste thin film layer 4. Described and explained,
Disturbing the transfer of the paste material by the transfer tool 6,
Transfer defects are likely to occur.

Further, if paste material 3 more than necessary is placed on screen 2 in advance in order to avoid the occurrence of such transfer failure, substantial waste of the paste material is incurred, resulting in a cost increase factor. Become.

[0009]

SUMMARY OF THE INVENTION Accordingly, the present invention provides a conventional method for changing the direction of movement of a squeegee.
It is an object of the present invention to provide a method of forming a paste thin film layer using a squeegee that can reduce the amount of paste material left outside the squeegee moving range.

[0010]

According to the present invention, there is provided a method for forming a paste thin film layer by spreading a paste material by moving a squeegee on a screen. Before converting, the squeegee is once retracted to separate the squeegee from the pool of the paste material existing in the direction of travel of the squeegee, and then the squeegee is raised to overcome the pool of the paste material. This is achieved by providing a method of forming a paste thin film layer by a squeegee, which is characterized by the following.

That is, according to the present invention, while forming a pool of the paste material with a squeegee, the paste material is spread and spread.
Next, when changing the moving direction of the squeegee to the opposite direction, the squeegee is retracted once and the squeegee is separated from the pool of the paste material existing adjacent to the traveling direction. The amount of the squeegee carried away from the pool of the paste material during the overcoming operation can be reduced.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below with reference to examples. 7 and 8 are views for explaining a method of forming a paste thin film layer using a squeegee according to the present invention. According to the method of the present invention, after the squeegee 1 pushes the mountain of the paste material, that is, the pool 3a, to one end of the screen 2, and then raises the squeegee 1,
Once the squeegee 1 is retracted (FIG. 7), the squeegee 1 is raised and the squeegee 1
a, and then lowered (FIG. 8). Thereafter, the squeegee 1 is moved in the opposite direction, and the paste material peaks or pools 3a are moved in the same manner as before.
Is spread to the other end of the screen 2 and this operation is repeated.

Before the squeegee 1 is raised, the squeegee 1 is once retracted, and the squeegee 1 is separated from the pile 3a of the paste material. During operation, the amount of the squeegee 1 taken out of the paste material pool 3a can be reduced.

Therefore, when the squeegee 1 descends to the upper surface of the screen 2 again by reducing the amount of the paste material pool 3a brought out by the squeegee 1,
The amount of the paste material left outside the moving range of the squeegee 1 on the screen 2 can be reduced.

As a result, it is possible to improve the use efficiency of the paste material that can be spread on the screen 2 and to reduce the problem of the transfer failure to the subsequent work. be able to.

[0016]

As described above in detail, according to the present invention, since the above-mentioned method is employed, the paste material which is left outside the squeegee moving range when the squeegee moving direction is changed. It is possible to provide a method of forming a paste thin film layer using a squeegee that can reduce the amount of the paste.

[Brief description of the drawings]

FIG. 1 is a diagram for explaining formation of a paste thin film layer by a squeegee and subsequent transfer of a paste material to a work as background art.

FIG. 2 is an enlarged view of FIG.

FIG. 3 is a diagram for explaining a conventional operation of the squeegee when the direction of movement of the squeegee is changed.

FIG. 4 is a diagram showing the operation of the squeegee after changing the moving direction of the squeegee.

FIG. 5 is a diagram for explaining a conventional problem when changing the moving direction of a squeegee.

FIG. 6 is a diagram for explaining a conventional problem together with FIG. 5;

FIG. 7 is a diagram for explaining the operation of the squeegee according to the present invention when the direction of movement of the squeegee is changed.

FIG. 8 is a diagram for explaining the operation of the squeegee according to the present invention, similarly to FIG. 7;

[Explanation of symbols]

Reference Signs List 1 squeegee 2 screen 3a pool of paste material formed adjacent to the squeegee traveling direction 4 paste thin film layer formed on screen

Claims (1)

[Claims] 1. A method of forming a paste thin film layer by spreading a paste material by moving a squeegee on a screen, wherein the squeegee is temporarily retracted before changing the moving direction of the squeegee to change the moving direction of the squeegee. After separating the squeegee from the pool of existing paste material,
A method of forming a paste thin film layer using a squeegee, wherein the squeegee is lifted to overcome the pool of the paste material.