JPH0821773B2 - Cream solder printing method and printing machine - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cream solder printing method and a printing machine for applying cream solder in a desired pattern on a printed circuit board.

[0002]

2. Description of the Related Art In the manufacture of electronic circuit boards, cream solder is used when soldering electronic circuit parts such as chip parts onto a printed circuit board. In order to apply this cream solder to a desired pattern, cream solder is used. A printing machine is used.

Conventional cream solder printing is performed by the method and apparatus as described below. This will be described with reference to FIG. 8 and FIG. 9. In FIG. 8, 1 is a printed circuit board, 2 is a land for printing the cream solder 3, 4 is a metal mask in which a desired pattern opening 5 is formed, and 6a. , 6b are printing squeegees that linearly move on the mask 4, and 7 is a solder resist. In the cream solder printing, the squeegees 6a and 6b are linearly moved in a state of being in contact with the mask 4 with an appropriate printing pressure to cause the cream solder 3 to perform a rotational movement called rolling (hereinafter referred to as rolling) while the mask 4 is being moved. Move the top and roll the cream solder 3 and squeegees 6a and 6b.
The cream solder 3 is filled in the opening 5 of the mask 4 by the pushing force by the method, and the cream solder 3 is printed and applied onto the printed circuit board 1 through the mask 4.

Normally, a cream solder printing machine is provided with two squeegees 6a and 6b for the purpose of improving the efficiency of the printing process. However, as shown in FIG. 8, this is done by printing from left to right. When performing, that is, when the squeegee 6a moves from left to right, the left squeegee 6a descends and contacts the mask 4, and printing is performed.
As shown in FIG. 9, for printing from right to left, the squeegee 6a on the left side is raised, and instead, the squeegee 6b on the right side is replaced.
Is moved downward and similarly moved to the left to perform printing. As described above, the cream solder printing machine alternately moves the two squeegees 6a and 6b up and down in correspondence with the printing direction, and the squeegees 6a and 6b roll and move the cream solder 3 to perform printing. It is something to do.

[0005]

By the way, conventionally, when cream solder printing is performed, a distance (hereinafter referred to as a gap) of several hundreds μm (depending on the mask thickness) is usually provided between the mask 4 and the printed board 1. It is provided. Therefore, at the time of printing, as shown in FIG. 10, the mask 4 is deformed by the printing pressure of the squeegee 6a, and the mask 4 and the printed circuit board 1 are in contact with each other only in the squeegee pressing portion, and in other portions, a minute gap is present. Occurs.

Since the cream solder 3 is filled in the mask opening 5 by the rolling of the cream solder 3 itself and the pushing force of the squeegee 6a, the mask 4 and the printed circuit board 1 come into contact with each other as shown in FIG. The filling of the cream solder 3 by rolling is also started in the mask opening 5 in front of the squeegee pressing portion. But,
Due to the gap formed between the mask 4 and the printed circuit board 1, the cream solder 3 not only fills the mask opening 5 but also flows out between the mask 4 and the printed circuit board 1.
As a result, as shown in FIG. 11, print defects such as print bleeding and excess print amount occur, which is a problem.

By the way, in recent years, a method of performing printing without providing a gap between the mask and the printed circuit board has been carried out for the purpose of preventing printing misalignment caused by deformation of the mask. Due to the occurrence of warp of the substrate and the manual adjustment of the gap, the mask and the printed circuit board cannot be completely brought into close contact with each other, and a small gap still occurs. In recent years, the particle size of solder particles in cream solder has also been very small (particle size
Since it becomes 50 μm or less), a printing defect also occurs in the minute gap between the mask and the printed circuit board in the same manner as described above, and it is difficult to prevent the printing defect only by adjustment by a person.

The present invention solves the above problems, and an object of the present invention is to provide a cream solder printing method and a printing machine which can prevent defective printing of cream solder.

[0009]

SUMMARY OF THE INVENTION In order to solve the above problems, the present invention aims to press a mask in front of a cream solder moving on a mask against a moving direction of a squeegee for printing, onto a printed circuit board. A mask pressing mechanism for pressing the printed circuit board from above the mask of the mask portion is provided.

[0010]

By the above means, printing is performed even when a gap is provided between the mask and the printed circuit board, or when a minute gap is generated due to warpage of the printed circuit board or manual adjustment of the gap. The squeegee pressing portion by the printing squeegee and the pressing portion by the mask pressing member by pressing the mask in the front part of the cream solder moving on the mask against the printed circuit board from above the mask in the moving direction of the squeegee. The mask and the printed circuit board can be completely brought into close contact with each other. That is, the mask and the printed board can be brought into close contact with each other in the portion where the cream solder rolls and moves (see FIG. 2).

Therefore, not only when the cream solder is filled in the mask opening by the squeegee pushing force, but also when the cream solder is filled in the mask opening in front of the squeegee pressing portion by the rolling of the cream solder itself, the mask and the printed circuit board are not filled. Since the cream solder does not flow out in the meantime, printing bleeding does not occur and a uniform amount of solder can be printed on the printed circuit board (see FIG. 3).

[0012]

An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic cross-sectional view showing a cream solder printer according to this embodiment. The same parts as those of the conventional one are designated by the same reference numerals, and the description thereof will be omitted.

In addition to the conventional structure, the cream solder printing machine operates in conjunction with the descending and ascending operations of the squeegees 6a and 6b, and when either one of the squeegees 6a and 6b descends, it descends in conjunction therewith. Then, the mask 4 is pressed against the printed circuit board 1 from above, and when both squeegees 6a and 6b are lifted, a mask pressing mechanism 8 is provided which is lifted in conjunction with this. A mask pressing member 9 is composed of a rotatable roller. The mask pressing mechanism 8 is provided between the squeegee 6a and the squeegee 6b,
The cream solder 3 is provided so as to be positioned between the masking members 9 and 6a and 6b.

In the cream solder printing machine configured as described above, for printing from the left to the right, as shown in FIG. 1, the squeegee 6a on the left side of the cream solder 3 is placed on the mask 4. It is moved to the left and lowered (the squeegee 6b on the right is in a raised state). In conjunction with this, the mask pressing mechanism 8 lowers the mask pressing member 9 onto the mask 4 on the right side of the cream solder 3, and as shown in the enlarged view of FIG.
The mask 4 and the printed circuit board 1 are brought into close contact with each other. While maintaining this state, the squeegees 6a and 6b and the mask pressing mechanism 8 are moved to the right, and the cream solder 3 filled in the mask opening 5 is passed through the mask 4 by the rolling of the cream solder 3 and the pushing force of the squeegee 6a. To print on the printed circuit board 1. Thereby, as shown in FIG. 3, the cream solder is printed in good condition. After printing, the squeegee 6a is raised, and in conjunction with this, the mask pressing member 9 is also raised. Next, for subsequent printing from right to left, the right squeegee 6b is moved to the right side of the cream solder 3 placed on the mask 4 and lowered. In conjunction with this, the mask pressing mechanism 8 lowers the mask pressing member 9 onto the mask 4 on the left side of the cream solder 3, and similarly between the squeegee 6b and the mask pressing member 9, the mask 4 and the printed circuit board 1 are provided. And close
While maintaining this state, printing is performed by moving the squeegees 6a and 6b and the mask pressing mechanism 8 to the left. After printing, the squeegee 6b and the mask pressing member 9 are raised. By repeating the above-described operation, continuous printing is performed without causing print defects.

Although a rotatable roller is used as the mask pressing member in the above-mentioned embodiment, members 10 and 11 each having an acute tip as shown in FIGS.
The same effect can be obtained by using a plate-shaped member or the like. Further, the material of the mask pressing members 9, 10, 11 is rubber (such as rubber normally used for squeegee materials).
Alternatively, a metal or the like can be used.

Further, although the mask pressing mechanism 8 and the mask pressing member 9 are provided in the above embodiment, as shown in FIG. 7, for example, for printing from left to right, the squeegee 6a is used.
Is used as a squeegee for printing, the squeegee 6b is used as a member for pressing a mask, and both squeegees 6a and 6b are lowered to perform printing (the same effect can be obtained for right-to-left printing). For example, the squeegee 6b is used as a printing squeegee and the squeegee 6a is used as a mask pressing member). According to this, it is not necessary to separately provide a pressing member, but it is more preferable to press the vicinity of the cream solder 3.

[0017]

As described above, according to the present invention, the cream solder which rolls and moves by pressing the mask in front of the cream solder moving on the mask with respect to the moving direction of the squeegee against the printed circuit board. The solder paste is applied to the printed circuit board while the mask and printed circuit board are in close contact with each other, or the mask in front of the cream solder that moves on the mask in the moving direction of the squeegee is pressed from above the mask. When a gap is provided between the mask and the printed circuit board by providing a mask pressing mechanism that presses the printed circuit board so as to closely contact the printed circuit board from this pressed portion of the mask to the portion pressed by the squeegee. And again
Even if a small gap occurs due to warpage of the printed circuit board or manual adjustment of the gap, the mask and the printed circuit board can be brought into complete contact with each other, printing bleeding does not occur, and a uniform amount of solder is printed. It is possible to print on the substrate. In addition, it is possible to shorten the adjustment time such as gap adjustment.

[Brief description of drawings]

FIG. 1 is a schematic sectional view of a cream solder printing machine according to an embodiment of the present invention.

FIG. 2 is an enlarged cross-sectional view near a squeegee pressing portion in FIG.

FIG. 3 is a cross-sectional view showing a state of cream solder printed according to the present invention.

FIG. 4 is a perspective view of a mask pressing member according to an embodiment of the present invention.

FIG. 5 is a perspective view of a mask pressing member according to an embodiment of the present invention.

FIG. 6 is a perspective view of a mask pressing member according to an embodiment of the present invention.

FIG. 7 is a schematic sectional view showing an embodiment of the present invention.

FIG. 8 is a schematic sectional view illustrating a conventional printing method.

FIG. 9 is a schematic sectional view illustrating a conventional printing method.

10 is an enlarged cross-sectional view near the squeegee pressing portion in FIG.

FIG. 11 is a cross-sectional view showing a state of cream solder printed by a conventional method.

[Explanation of symbols]

 1 Printed Circuit Board 2 Land 3 Cream Solder 4 Mask 5 Mask Opening 6a, 6b Squeegee 7 Cream Solder 8 Mask Pressing Mechanism 9, 10, 11 Mask Pressing Member

Claims (5)

[Claims] 1. A cream solder printing method for applying cream solder onto a printed circuit board by moving a squeegee through a mask having openings of a desired pattern, wherein the squeegee moves on the mask. Press the mask in front of the cream solder against the printed circuit board, and the cream solder rolls and moves.
Make sure that the mask and printed circuit board
While applying the cream solder to the printed circuit board, the cream solder printing method. 2. A mask provided with an opening having a desired pattern and a squeegee that can be moved linearly on the mask. The movement of the squeegee causes cream solder on the mask to pass through the mask to a printed circuit board. In the cream solder printing machine for applying the mask onto the printed circuit board, the mask in front of the cream solder moving on the mask in the moving direction of the squeegee is pressed against the printed circuit board from above the mask.
Press with the squeegee from this pressing part on the
A cream solder printing machine equipped with a mask pressing mechanism that allows the printed circuit board to be in intimate contact with all the parts . 3. The cream solder printing machine according to claim 2, wherein the pressing member of the mask pressing mechanism is a rotatable roller. 4. The cream solder printing machine according to claim 2, wherein the tip of the pressing member of the mask pressing mechanism has an acute angle. 5. At least two squeegees are provided, and one of the squeegees moves the cream solder on the mask, and the other.
The cream solder printing machine according to claim 2 , wherein the squeegee is used to press the mask.