JP2003211628A - Screen printing mask and screen printing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a screen printing mask and a screen printing method, by which an electronic part with a connection error can be mounted on a printed circuit board with ease by achieving miniaturization. <P>SOLUTION: The screen printing mask 1 is provided with a mask part 11 and a plurality of peripheral walls erecting from the mask part 11. The mask part 11 is provided with through-holes 13. Solder paste is supplied to an end part 16 on a side away from the mask part 11 of the inner face 14a of one peripheral wall 12a. The solder paste is brought closer to the mask part 11 by means of a squeegee, and then the squeegee is made to move along the surface 15 of the mask part 11. The solder paste is pressed into the through- holes 13 of the mask part 11. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a screen printing mask and a screen printing method for printing and supplying a solder paste in a predetermined pattern on a printed circuit board.

[0002]

2. Description of the Related Art Conventionally, a reflow soldering method has been widely used for mounting a large number of electronic components on a printed circuit board at one time. This reflow soldering method is
Solder paste is previously supplied to the printed circuit board, and the electronic components described above are placed on the printed circuit board in a state where electrodes are brought into contact with the supplied solder paste.

After that, the printed circuit board on which each electronic component is mounted is inserted into the reflow furnace. The solder paste is re-melted, and the electronic components mounted on the printed board are collectively soldered (surface mounted) to the printed board.

In order to perform such a reflow soldering method, for example, screen printing using the mask 100 shown in FIG. 15 may be performed. The mask 100 is
As shown in FIG. 15, a screen-like thin plate is provided with through holes 101 corresponding to the respective wiring patterns of the printed circuit board. At the time of printing, first, the mask 100 is overlaid on the printed circuit board. Apply solder paste on the surface of the mask 100.

A squeegee presses the mask 100 in a direction of approaching the printed circuit board to press the mask 100 against the printed circuit board, and the squeegee moves the solder paste on the surface of the mask 100. As a result, the solder paste is pushed into the through holes 101, and the solder paste is placed on the surface of the printed board according to a predetermined pattern.

[0006]

After performing the above-described reflow soldering method, in particular, BGA (Ball Grid Arra)
y) Electronic components mounted on the printed circuit board by the mounting method may have improper mounting on the printed circuit board. At this time, it is necessary to remove the improperly mounted electronic component from the printed board and perform screen printing again using the mask 100 described above.
It was difficult because it was large.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a screen printing mask and a screen printing method which can be downsized and easily mount again an electronic component that is not properly mounted on a printed circuit board.

[0008]

In order to solve the above problems and achieve the object, the screen printing mask of the present invention according to claim 1 again mounts an electronic component that is not mounted properly on a printed circuit board. A screen printing mask that prints a solder paste in a predetermined pattern on the printed circuit board when attached to the printed circuit board has a through hole formed in a flat plate shape and having a shape corresponding to the predetermined pattern for printing the solder paste. With the mask portion to be superimposed on the printed circuit board, a plurality of peripheral walls standing from the outer edge of the mask portion, a paste placement portion provided on the inner surface of one of the peripheral walls and the solder paste is applied, It is characterized by having.

A screen printing mask according to a second aspect of the present invention is the screen printing mask according to the first aspect, wherein the inner surface of the one peripheral wall extends along a direction orthogonal to the surface of the mask portion. It is characterized by that.

According to the screen printing method of the present invention, the solder paste is printed in a predetermined pattern on the printed circuit board when the defectively mounted electronic component mounted on the printed circuit board is mounted on the printed circuit board again. In addition, a mask portion which is formed in a flat plate shape and has a through hole having a shape corresponding to a predetermined pattern for printing the solder paste, and which is overlaid on the printed circuit board, and a plurality of peripheral walls erected from the outer edge of the mask portion. When,
In a screen printing method using a screen printing mask, which is provided on the inner surface of one of the peripheral walls and has a paste placement part to which the solder paste is applied, the mask part is superposed on the printed circuit board, and Apply the solder paste to the paste placement portion, move the squeegee along the inner surface of the one peripheral wall to bring the solder paste close to the mask portion, and then move the squeegee on the surface of the mask portion to cause the solder. It is characterized in that the paste is pushed into the through hole.

A screen printing method according to a fourth aspect of the present invention is the screen printing method according to the third aspect, wherein the inner surface of the one peripheral wall is along a direction orthogonal to the surface of the mask portion. Is characterized by.

According to the first aspect of the present invention, the paste placing portion on which the solder paste is applied is provided on the inner surface of one of the peripheral walls erected from the mask portion. Therefore, the squeegee can bring the solder paste applied to the paste placement portion close to the mask portion, and then move the solder paste along the surface of the mask portion to push it into the through hole. For this reason, when the squeegee is positioned on the outer edge of the mask portion, a gap is less likely to be formed between the squeegee and the solder paste and between the solder paste and the outer edge of the mask portion.

According to the second aspect of the present invention, the inner surface of one peripheral wall and the surface of the mask portion are orthogonal to each other. Therefore, the screen printing mask itself can be downsized. Further, since the inner surface of one peripheral wall and the surface of the mask portion are orthogonal to each other, the screen printing mask is less likely to be displaced when the solder paste is moved by the squeegee.

According to the present invention described in claim 3, in the squeegee, the solder paste applied to the paste placing portion provided on the inner surface of one of the peripheral walls erected from the mask portion is applied to the mask portion. After bringing them close to each other, they are moved along the surface of the mask portion. Then, the solder paste is pushed into the through holes. For this reason, when the squeegee is positioned on the outer edge of the mask portion, a gap is less likely to be formed between the squeegee and the solder paste and between the solder paste and the outer edge of the mask portion.

According to the present invention described in claim 4, the inner surface of one peripheral wall of the screen printing mask and the surface of the mask portion are orthogonal to each other. Therefore, the screen printing mask itself can be downsized. Further, since the inner surface of one peripheral wall and the surface of the mask portion are orthogonal to each other, the screen printing mask is less likely to be displaced when the solder paste is moved by the squeegee.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION A first embodiment of the present invention will be described with reference to FIGS. A screen printing mask (hereinafter simply referred to as a mask) 1 according to the first embodiment of the present invention shown in FIG. 1 and the like is used in a repair device 4 (shown in FIG. 4 and the like). Solder paste 5 (shown in FIG. 3) according to a predetermined pattern on the surface of printed circuit board 2 (shown in FIG. 5) by a known screen printing device.
Is printed and supplied, and the electronic component 3 (shown in FIG. 2) is attached to the printed circuit board 2. At this time, the electronic component 3
Some of them may be poorly mounted on the printed circuit board 2. The repair device 4 is used when the electronic component 3 that is not properly attached is attached to the printed circuit board 2 again.

The electronic component 3 shown in FIG. 2 is a BGA (Ball G).
This is a so-called BGA type electronic component that is attached to the printed circuit board 2 by a rid array) mounting method. As shown in FIGS. 2 and 3, the electronic component 3 includes a substrate 6 having a laminated structure, an LSI chip (not shown) attached to the substrate 6, and the substrate 6
A plurality of electrodes 7 provided on the lower surface of the device, and a wiring portion (not shown) that electrically connects the terminals of the LSI chip to the electrodes 7. The electrodes 7 are arranged on the lower surface in a planar shape and in a grid shape. The electrodes 7 are arranged in a so-called two-dimensional matrix.

As shown in FIG. 3 and the like, the printed circuit board 2 is composed of a substrate 8 made of an insulating synthetic resin, a plurality of pads 9 formed on the surface of the substrate 8 and connected to these pads 9. And a conductor pattern (not shown).
The surface of the substrate 8 is formed flat. Pad 9
It has conductivity. The pads 9 are arranged in a plane and in a grid pattern. The pads 9 are arranged in a so-called two-dimensional matrix. When the surface of the printed circuit board 2 and the lower surface of the substrate 6 of the electronic component 3 face each other, the pad 9 is provided with the electrode
To face.

The conductor pattern is made of a conductive metal such as copper and is formed in a thin film shape. The conductor pattern is attached to the surface of the substrate 8. The conductor pattern, according to a predetermined pattern,
The pads 9 and the like are electrically connected to each other.

In the electronic component 3 having the above-described structure, the electrode 7 is electrically connected to the pad 9 by the solder paste 5 supplied onto the pad 9 by the repair device 4, as shown in a partial cross section in FIG. In this state, it is attached to the printed circuit board 2.

When mounting the electronic component 3 that is not properly mounted on the printed circuit board 2 again, first, the electronic component 3 is removed from the printed circuit board 2. After that, the repair device 4
The solder paste 5 is printed / supplied onto the pad 9 in accordance with a predetermined pattern required to drive the electronic component 3. That is, the repair device 4 is a device that prints / supplies the solder paste 5 on the surface of the printed board 2 where the electronic component 3 is attached in a predetermined pattern.

The repair device 4 includes a base (not shown) on which the printed circuit board 2 is placed and positioned, a squeegee 10 (shown in FIG. 4) and the like. The squeegee 10 is formed in a plate shape. The repair device 4 places and positions the printed circuit board 2 on the base. Furthermore, the printed circuit board 2
A mask portion 11 of the mask 1 which will be described later is overlaid on the top.

After that, the repair device 4 supplies the solder paste 5 to the end portion 16 of the inner surface 14a of one peripheral wall 12a of the mask 1 which will be described later, and brings the solder paste 5 close to the mask portion 11 with the squeegee 10. Surface 1 of mask portion 11
Move along 5. And the solder paste 5
According to the above-mentioned predetermined pattern, the printed circuit board 2
Printed and supplied on the surface of. The solder paste 5 is formed by kneading solder powder with flux or the like.

As shown in FIG. 1, the mask 1 has a mask portion 11 and a plurality of peripheral walls 12. Mask part 11
Is made of a flat thin sheet metal or the like. The mask portion 11 is formed in a rectangular shape slightly larger than the electronic component 3. The mask portion 11 is formed in a similar shape to the substrate 6 of the electronic component 3 or the like.

A plurality of through holes 13 are formed in the mask portion 11. The through hole 13 is formed by penetrating the base material forming the mask portion 11. The through hole 13 is formed by conventionally well-known etching or the like. Through hole 13
Are arranged in a plane and in a grid. Through hole 13
Are arranged in a so-called two-dimensional matrix. The pad 9 enters the through hole 13 when the mask portion 11 is placed on the printed circuit board 2. Thus, the through holes 13 are formed according to a predetermined pattern for printing the solder paste 5.

The peripheral wall 12 is made of a flat thin metal plate or the like. Four peripheral walls 12 are provided in the illustrated example. Each peripheral wall 12 is continuous with the outer edge of the mask portion 11. The plurality of peripheral walls 12 are erected from the mask portion 11 in the same direction. Thus, the inner surface 14 of the peripheral wall 12 and the surface 15 of the mask portion 11 intersect each other. The surrounding wall 1
The inner surface 14 of No. 2 is the surface of the peripheral wall 12 located inside the mask 1. The surface 15 of the mask portion 11 is continuous with the inner surface 14 of the peripheral wall 12.

Of the four peripheral walls 12, the inner surface 1 of the pair of peripheral walls 12 facing each other in the width direction of the mask portion 11.
4 is orthogonal to the surface 15 of the mask portion 11.
The pair of peripheral walls 12 are attached to the repair device 4. Further, of the pair of peripheral walls 12 facing each other in the longitudinal direction of the mask portion 11, the mask portion of the inner surface 14 (indicated by reference numeral 14a below) of one peripheral wall 12 (indicated by reference numeral 12a below) located in the back in FIG. End 1 on the side away from 11
The solder paste 5 is supplied (applied) to 6 (indicated by dense parallel diagonal lines in FIG. 1). This one peripheral wall 1
The end portion 16 of the inner surface 14a of 2a forms the paste placing portion described in this specification. Further, the mask portion 11 is formed by a well-known welding method such as a fusion welding method, a pressure welding method, or a brazing method.
And the peripheral wall 12 are fixed to each other to assemble the mask 1.

When the solder paste 5 is printed / supplied onto the pads 9 of the printed board 2 using the mask 1 having the above-described structure, first, the printed board 2 is placed / positioned on the base of the repair device 4. At the same time, the mask 1 is attached to the repair device 4. Then, with the mask portion 11 of the mask 1 facing the printed circuit board 2, the mask 1
On the printed circuit board 2 on the base. At this time, as shown in FIG. 5 to FIG.
Is invading.

Then, as shown in FIG. 5, the solder paste 5 is supplied to the end portion 16 of the inner surface 14a of one peripheral wall 12a of the mask 1. Then, as shown in FIG. 6, the squeegee 10 is moved along the inner surface 14 a of the one peripheral wall 12 a so that the squeegee 10 brings the solder paste 5 close to the mask portion 11. Then, as shown in FIG. 7, the tip of the squeegee 10 is located at the outer edge of the mask portion 11. As shown in FIG. 7, when the tip of the squeegee 10 is located at the outer edge of the mask portion 11, between the solder paste 5 and the squeegee 10,
There is no gap between the solder paste 5 and the outer edge of the surface 15 of the mask portion 11.

Thereafter, as shown in FIG. 8, the squeegee 10
Are moved along the surface 15 of the mask portion 11. The solder paste 5 enters the through holes 13 and is printed / supplied on the pads 9 of the printed board 2.

According to this embodiment, the inner surface 1 of one peripheral wall 12a among the plurality of peripheral walls 12 provided upright from the mask portion 11 is provided.
Solder paste 5 is applied to the end 16 of 4a. After the solder paste 5 applied to the end portion 16 of the inner surface 14a is brought close to the mask portion 11 with the squeegee 10, the mask portion 11 is removed.
Along the surface 15 of the. Then, the solder paste 5 is pressed into the through holes 13 and printed / supplied onto the pads 9.

Therefore, when the squeegee 10 is positioned on the outer edge of the mask portion 11, the solder paste 5 and the squeegee 1
0, the solder paste 5 and the surface 1 of the mask portion 11
A gap is less likely to be formed between the outer edge of No. 5 and the outer edge of No. 5. Therefore, the distance D (shown in FIG. 5 and the like) between the through hole 13 closest to the outer edge of the mask portion 11 and the outer edge of the mask portion 11 can be narrowed. Therefore, the mask 1 can be downsized, and the electronic component 3 that is not properly attached can be easily attached to the printed circuit board 2 again.

The mask portion 11 and the peripheral wall 12 are fixed by welding. Therefore, the relative positions of the mask portion 11 and the peripheral wall 12 are maintained with high accuracy. Therefore, the printing accuracy of the solder paste 5 can be improved.

Next, a mask 1 according to a second embodiment of the present invention will be described with reference to FIGS. 9 to 14. In addition,
The same components as those in the first embodiment described above are designated by the same reference numerals and the description thereof will be omitted.

As shown in FIGS. 9 to 14, the inner surface 14a of one peripheral wall 12a to which the solder paste 5 of the mask 1 according to this embodiment is supplied (painted) with respect to the surface 15 of the mask portion 11 is used. Along the orthogonal direction.

The solder paste 5 is printed on the pads 9 of the printed circuit board 2 by using the mask 1 according to this embodiment.
When supplying, first, the printed circuit board 2 is placed and positioned on the base of the repair device 4, and the mask 1 is attached to the repair device 4. Then, as shown in FIG. 10, with the mask portion 11 of the mask 1 facing the printed circuit board 2, the mask 1 is placed on the printed circuit board 2 on the base.
On top of. At this time, the pads 9 have entered the through holes 13 as shown in FIGS. 11 to 14.

After that, as shown in FIG. 11, the solder paste 5 is supplied to the end portion 16 of the inner surface 14a of one peripheral wall 12a of the mask 1. Then, as shown in FIG. 12, the squeegee 10 is moved along the inner surface 14a of one peripheral wall 12a, and the solder paste 5 is applied to the mask portion 1 by the squeegee 10.
Get closer to 1. Then, as shown in FIG. 13, the squeegee 1
The tip of 0 is located on the outer edge of the mask portion 11. Note that FIG.
As shown in FIG. 3, when the tip of the squeegee 10 is located at the outer edge of the mask portion 11, a gap is formed between the solder paste 5 and the squeegee 10, and between the solder paste 5 and the outer edge of the surface 15 of the mask portion 11. Disappear.

Then, as shown in FIG. 14, the squeegee 1
0 is moved along the surface 15 of the mask portion 11. While the solder paste 5 enters the through hole 13,
It is printed / supplied on the pad 9 of the printed circuit board 2.

According to this embodiment, the inner surface 14a of one peripheral wall 12a and the surface 15 of the mask portion 11 are orthogonal to each other. Therefore, the mask 1 itself can be downsized. Also, the inner surface 14a of one peripheral wall 12a and the mask portion 1
Since the surface 15 of the mask 1 is orthogonal to the surface 15, the squeegee 10 applies a force to the mask 1 along a direction orthogonal to the surface 15 of the mask 11 when the solder paste 5 is moved toward the mask 11. . Therefore, the mask 1 is less likely to be displaced.

Further, like the first embodiment described above,
The solder paste 5 is supplied (applied) to the end portion 16 of the inner surface 14a of one peripheral wall 12a. Then, after the solder paste 5 is brought close to the mask portion 11 with the squeegee 10, the solder paste 5 is moved along the surface 15 of the mask portion 11 and printed / supplied onto the pad 9.

Therefore, when the squeegee 10 is positioned on the outer edge of the mask portion 11, the solder paste 5 and the squeegee 1
0, the solder paste 5 and the surface 1 of the mask portion 11
A gap is less likely to be formed between the outer edge of No. 5 and the outer edge of No. 5. Therefore, the distance D (shown in FIG. 11 and the like) between the through hole 13 closest to the outer edge of the mask portion 11 and the outer edge of the mask portion 11 can be narrowed. Therefore, the mask 1 can be downsized, and the electronic component 3 that is not properly attached can be easily attached to the printed circuit board 2 again.

Therefore, the electronic component 3 which is not properly attached can be easily attached to the printed circuit board 2 again, and the printing accuracy of the solder paste 5 can be improved.

[0043]

As described above, according to the present invention as set forth in claim 1, the paste placing portion on which the solder paste is applied is provided on the inner surface of one of the peripheral walls erected from the mask portion. . Therefore, the squeegee can bring the solder paste applied to the paste placement portion close to the mask portion, and then move the solder paste along the surface of the mask portion to push it into the through hole. Therefore, when the squeegee is positioned on the outer edge of the mask portion, between the squeegee and the solder paste,
A gap is less likely to occur between the solder paste and the outer edge of the mask portion. Therefore, the distance between the through hole and the outer edge of the mask portion can be narrowed. Therefore, it is possible to reduce the size of the screen printing mask, and it is possible to easily attach the electronic component that is not properly attached to the printed circuit board again.

According to the present invention described in claim 2, the inner surface of one peripheral wall and the surface of the mask portion are orthogonal to each other. Therefore, the screen printing mask itself can be downsized. Further, since the inner surface of one peripheral wall and the surface of the mask portion are orthogonal to each other, the screen printing mask is less likely to be displaced when the solder paste is moved by the squeegee. Therefore, it is possible to easily reattach the electronic component that is not properly attached to the printed circuit board and improve the printing accuracy of the solder paste.

According to the third aspect of the present invention, the squeegee uses the solder paste applied to the paste placing portion provided on the inner surface of one of the peripheral walls erected from the mask portion as the mask portion. After bringing them close to each other, they are moved along the surface of the mask portion. Then, the solder paste is pushed into the through holes. For this reason, when the squeegee is positioned on the outer edge of the mask portion, a gap is less likely to be formed between the squeegee and the solder paste and between the solder paste and the outer edge of the mask portion. Therefore, the distance between the through hole of the screen printing mask and the outer edge of the mask portion can be narrowed. Therefore,
It is possible to reduce the size of the screen printing mask, and it is possible to easily reattach electronic components that have been improperly attached to the printed circuit board.

According to the fourth aspect of the present invention, the inner surface of one peripheral wall of the screen printing mask is orthogonal to the surface of the mask portion. Therefore, the screen printing mask itself can be downsized. Further, since the inner surface of one peripheral wall and the surface of the mask portion are orthogonal to each other, the screen printing mask is less likely to be displaced when the solder paste is moved by the squeegee. Therefore,
It is possible to easily attach the electronic component that is not properly attached to the printed circuit board again and improve the printing accuracy of the solder paste.

[Brief description of drawings]

FIG. 1 is a perspective view showing a screen printing mask according to a first embodiment of the present invention.

FIG. 2 is a plan view of an electronic component attached to a printed circuit board using the screen printing mask of the same embodiment, as viewed from the lower surface side.

FIG. 3 is a diagram showing a cross section of a part of a mounting portion of the electronic component shown in FIG. 2 on a printed circuit board.

FIG. 4 is a perspective view showing a state where screen printing is performed on a printed circuit board using the screen printing mask of the same embodiment.

5 is a cross-sectional view taken along the line VV in FIG.

6 is a cross-sectional view showing a state in which a solder paste is brought close to a mask portion with a squeegee from the state shown in FIG.

FIG. 7 is a cross-sectional view showing a state in which the tip of the squeegee is located at the outer edge of the mask portion from the state shown in FIG.

8 is a cross-sectional view showing a state in which the squeegee has been moved along the surface of the mask portion from the state shown in FIG.

FIG. 9 is a perspective view showing a screen printing mask according to a second embodiment of the present invention.

10 is a perspective view showing a state in which screen printing is performed on a printed circuit board using the screen printing mask shown in FIG.

11 is a cross-sectional view taken along the line XI-XI in FIG.

FIG. 12 is a cross-sectional view showing a state where the solder paste is brought close to the mask portion with a squeegee from the state shown in FIG.

13 is a cross-sectional view showing a state in which the tip of the squeegee is located at the outer edge of the mask portion from the state shown in FIG.

FIG. 14 is a cross-sectional view showing a state in which the squeegee has been moved along the surface of the mask portion from the state shown in FIG.

FIG. 15 is a perspective view of a conventional mask.

[Explanation of symbols]

1 Screen printing mask 2 printed circuit boards 3 electronic components 5 Solder paste 11 Mask part 12 surrounding walls 12a One peripheral wall 13 through holes 14a inner surface 15 surface 16 edge (paste placement part)

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Claims (4)

[Claims] 1. A screen printing mask for printing a solder paste in a predetermined pattern on the printed circuit board when mounting an electronic component that has been improperly mounted on the printed circuit board again on the printed circuit board, and is formed into a flat plate shape. And a mask portion having a through hole having a shape corresponding to a predetermined pattern for printing the solder paste, and the mask portion to be overlaid on the printed circuit board, a plurality of peripheral walls erected from the outer edge of the mask portion, and one of the peripheral walls. A mask for screen printing, comprising: a paste placing portion provided on the inner surface of the peripheral wall and coated with the solder paste. 2. The screen printing mask according to claim 1, wherein an inner surface of the one peripheral wall extends along a direction orthogonal to a surface of the mask portion. 3. A solder paste is printed in a predetermined pattern on the printed circuit board when the electronic component which is not properly mounted on the printed circuit board is mounted on the printed circuit board again, and the solder paste is formed in a flat plate shape and is the solder paste. A mask part having a through hole having a shape corresponding to a predetermined pattern for printing, and a mask part to be overlaid on the printed circuit board, a plurality of peripheral walls standing from the outer edge of the mask part, and an inner surface of one of the peripheral walls. In a screen printing method using a screen printing mask provided with a paste placing portion to which the solder paste is applied, the mask portion is overlaid on the printed circuit board, and a solder paste is applied to the paste placing portion. Move the squeegee along the inner surface of the one peripheral wall to bring the solder paste close to the mask. After digits, screen printing method, characterized in that pushing the squeegee the solder paste in the through-hole by moving over the surface of the mask portion. 4. The screen printing method according to claim 3, wherein the inner surface of the one peripheral wall extends along a direction orthogonal to the surface of the mask portion.