JPH07266537A - Screen printing machine - Google Patents

Abstract

(57) [Summary] [Purpose] Solder paste can be printed without causing blurring or bleeding at a fine pitch. [Structure] A step portion 120 is provided on the metal mask 3. As a result, the force with which the squeegee 10 press-fits the solder paste 9 into the vertical opening 5 can be reduced, so that the printing status in the vertical opening 5 can be matched with the printing status in the horizontal opening 7, and a fine pattern can be obtained. The solder paste 9 can be printed without causing blurring or bleeding in the pitch openings 5 and 7. In addition, the step portion 120 is provided with an overhanging portion 11e.
To provide. As a result, even when the squeegee 10 moves in a posture inclined with respect to the moving direction I, the squeegee 1
Since 0 deforms to a state substantially similar to the deformed state by the stepped portion 120 described above, there is no fear that blurring or blurring will occur when the squeegee 10 is not deformed in the vertical opening 5.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention provides a printed wiring board on one side of a screen mask and moves a squeegee on the other side of the screen mask to remove the solder paste from the screen mask. The present invention relates to a screen printing machine that presses the solder paste on the other surface and prints the solder paste in the shape of the openings on the printed wiring board through the openings provided in the screen mask, and is arranged at a particularly fine pitch. The present invention relates to a screen printing machine capable of printing a solder paste without causing blurring or bleeding even in an opening.

[0002]

2. Description of the Related Art In order to mount (fix) electronic components such as semiconductor devices, resistors and capacitors on a printed wiring board to realize a desired electronic circuit, a solder paste is applied to the printed wiring board by using a screen printing machine. Is being printed. A conventional screen printer of this type is shown in FIGS.
It will be described based on 1. 16 to 21, 1
Is a printed wiring board. The printed wiring board 1 is provided with a plurality of wiring pads 2 on the upper surface of which a solder paste 9 described later is printed. The wiring pad 2 is connected to a lead terminal 14 of an electronic component 13 described later via a solder paste 9 described later, and the electronic component 1 to be mounted is mounted.
It is arranged so as to follow the lead terminal 14 of No. 3. For example,
16 and 17, since the number of lead terminals 14R of the electronic component 13R mounted on the right side R is relatively small and the pitch between the lead terminals 14R is relatively coarse,
The number of wiring pads 2 on the right side R is relatively small,
Moreover, the pitch between the wiring pads 2 is relatively coarse. on the other hand,
Lead terminal 14L of electronic component 13L mounted on the left side L
, And the pitch between the lead terminals 14L is relatively fine, the number of wiring pads 2 on the left side L is relatively large, and the pitch between the wiring pads 2 is relatively fine. Is.

Reference numeral 3 indicates one surface of the printed wiring board 1 (see FIG. 1).
It is a screen mask made of, for example, a metal (metal), which is arranged so that the inner middle and lower surfaces 7 thereof face each other. This metal mask 3
A plurality of openings 5 and 7 are provided corresponding to the positions of the wiring pad 2. As a result, the number of openings 5 and 7 on the right side R is relatively small, and the pitch between the openings 5 and 7 is relatively coarse, following the position of the wiring pad 2. On the other hand, the number of openings 5 and 7 on the left side L is relatively large, and the pitch between the openings 5 and 7 is relatively fine. For convenience of explanation, of the openings, the first opening (the longitudinal direction is vertical in FIG. 16 has a vertical direction in the moving direction (arrow A direction) of the squeegee 10 and the longitudinal direction of the opening). 5) is attached to the vertical opening)
Further, the reference numeral 7 is assigned to the second opening (the horizontal opening in which the longitudinal direction lies in FIG. 16) in which the moving direction of the squeegee 10 and the longitudinal direction of the opening 7 substantially match (are parallel to). Attach.

The electronic component 13 is, for example, a lead terminal 1.
4 is a quarter flat package type (QFP type) extended in four directions.

The shape of the wiring pad 2 and the openings 5 and 7 described above is a slender shape as viewed from above, following the lead terminals 14 of the electronic component 13 to be mounted. For example, as shown in FIG. 16, the lead terminal 14 has a substantially rectangular shape in which the extending direction side is the long side and the row direction side of the lead terminal 14 is the short side. The size of the openings 5 and 7 is such that the solder paste 9 described later is the wiring pad 2.
It is slightly smaller than the wiring pad 2 to the extent that it does not ooze out (does not ooze out). Furthermore, the above-mentioned wiring pad 2
And the openings 5 and 7, as shown in FIG.
Following the lead terminals 14 of the FP type electronic component 13, they are arranged in a square shape (in a state where the wiring pads 2 and the openings 5 and 7 are arranged in the direction of the short side) in a square shape.

Reference numeral 4 denotes a concave portion provided on the other surface of the metal mask 3 (the upper surface in FIG. 17, which is the surface on which the squeegee 10 moves). The concave portion 4 is provided in a quadrangle shape within the region range that surrounds the entire left and right fine pitch side openings 5 and 7 groups. As a result, the depths of the openings 5 and 7 on the fine pitch side on the left side L are shallower than the depths of the openings 5 and 7 on the right side R. The depths of the openings 5 and 7 determine the amount of the solder paste 9 printed on the wiring pad 2. That is, if the depth of the openings 5 and 7 is shallow, the amount of the printed solder paste 9 is small.
Therefore, the amount of the solder paste 9 printed on the wiring pad 2 on the fine pitch side on the left side L is smaller than the amount 9 of the solder paste printed on the wiring pad 2 on the right side R.

Reference numeral 8 is a solder paste placed on the metal mask 3, and 9 is a solder paste printed on the wiring pad 2 through the openings 5 and 7.

Next, the operation operation of the screen printing machine having the above construction will be described. First, by moving the squeegee 10 in the direction indicated by the arrow a, the squeegee on the other surface (upper surface) side of the metal mask 3 and the front surface of the squeegee 10 (when the moving direction a of the squeegee 10 is the front). Solder paste 8 placed on the surface 10 on the moving direction side)
Receives the acting force in the direction toward the printed wiring board 1 on the surface of the metal mask 3 from the squeegee 10 and the rotating force on the surface, and the solder paste is placed on the wiring pad 2 through the openings 5 and 7. Printed as strike 9. Next, after the metal mask 3 is separated from the printed wiring board 1, a lead terminal 14 of the electronic component 13 is mounted on the solder paste 9 on each wiring pad 2 by a component mounting machine (a mounter, not shown). Then, the solder paste 9 is melted by passing through the reflow furnace. After that, the electronic component 13 is cooled and cooled.
The printed circuit board 1 fixed to the printed wiring board 1 via the solder paste 9 is completed. Incidentally, as an example of such a screen printing machine, Japanese Patent Laid-Open No. 4-201
No. 389 publication.

[0009]

However, in the above-mentioned conventional screen printing machine, the squeegee 10 causes the solder paste 9 to be press-fitted into the vertical opening 5 and the horizontal opening 7 to be pressed. Since the printed state is different as described below, a solder paste printed on the wiring pad 2 is printed.
The strike 9 may be blurred or bleeding. In particular, the above-described blurring and bleeding are likely to occur in the vertical opening 5 and the horizontal opening 7 with the fine pitch in the region on the left side L in FIG. Hereinafter, the difference between the printing status of the vertical opening 5 and the printing status of the horizontal opening 7 will be described in detail.

18 (a) to 18 (d) and FIG. 20 show a printing condition in the vertical opening 5. First, FIG.
As shown in (a) and FIG. 20, immediately after the squeegee 10 passes through the long side (longitudinal edge) 50 of the vertical opening 5,
The tip of the squeegee 10 enters the vertical opening 5, and the press-fitting of the solder paste 9 into the vertical opening 5 is started. Here, since the short side (edge in the lateral direction) 51 of the vertical opening 5 substantially coincides with the moving direction a of the squeegee 10, the vertical opening 5 in the moving direction a of the squeegee 10.
The size of the gap is small. Therefore, as shown in FIG. 18B, the press-fitting of the solder paste 9 is immediately completed. However, even if the press-fitting of the solder paste 9 is immediately completed, the squeegee 10 continues to pass through the vertical opening 5, so that the solder paste 9 is further filled into the vertical opening 5. There is still pressure input to try,
The solder paste 9 which receives the pressurizing force loses the escape place in the vertical opening 5 and presses the long side (long side on the side opposite to the side on which the squeegee 10 enters) 50 of the vertical opening 5. . The long side 50 of the vertical opening 5 is the squeegee 10.
Since it is substantially parallel to the tip of the squeegee, the tip of the squeegee 10 easily enters the vertical opening 5 along the long side 50, as shown by the arrow in FIG. To this end, squeegee 1
The force that presses the solder paste 9 into the vertical opening 5 due to 0 is large, and the solder paste 9 that has lost the escape in the vertical opening 5 has The power to press the long side 50 is also great. As a result, a reaction action of pushing up the metal mask 3 and the squeegee 10 works, and FIG.
As shown in (c), the adhesion between the wiring pad 2 and the metal mask 3 is impaired, the solder paste 9 leaks out at that location, and the printed solder paste 9 becomes thick and wide. According to the pattern, the bleeding 90 is generated. Then, as the openings are further miniaturized and the distance between the adjacent vertical openings 5 becomes shorter, the force for keeping the plane of the portion 30 of the metal mask 3 between the vertical openings 5 becomes smaller, Adhesion between the portion 30 of the metal mask 3 and the wiring pad 2 is further impaired, the portion 30 of the metal mask 3 easily separates from the wiring pad 2, and the above-described bleeding 90 tends to increase. As a result, as shown in FIG. 18D, the bleeding 90 short-circuits between the adjacent wiring pads 2, so that miniaturization of the vertical openings 5 is more difficult than expected.

On the other hand, FIGS. 19A to 19D and FIG.
Shows the printing situation in the lateral opening 7. First, FIG.
As shown in (a) and FIG. 21, immediately after the squeegee 10 passes through the short side 71 of the lateral opening 7, the squeegee 10 is squeezed.
By this, press-fitting of the solder paste 9 into the lateral opening 7 is started. Here, since the long side 70 of the lateral opening 7 substantially coincides with the moving direction B of the squeegee 10, the squeegee 1
The size of the gap between the lateral openings 7 in the moving direction 0 of 0 is large. For this reason, as shown in FIG. 19 (b), even after the squeegee 10 has passed the short side 71 of the lateral opening 7, the press-fitting of the solder paste 9 is not completed, and the squeegee is not squeezed. 10
The press-fitting of the solder paste 9 is continued in accordance with the movement of the solder paste. In this case, the solder paste 9 that receives the pressure input can escape onto the metal mask 3 in the moving direction of the squeegee 10, and the solder paste 9 rarely presses the short side 71 of the opening 7. In addition, the short side 71 of the opening 7 beside this
Is substantially parallel to the tip of the squeegee 10, the tip of the squeegee 10 has a horizontal opening 7 as compared with the vertical opening 5 described above, as shown by the arrow in FIG. It's hard to get inside. For this reason, the force by which the squeegee 10 presses the solder paste 9 into the lateral opening 7 is smaller than that in the vertical opening 5 described above. As a result, the metal mask 3
The force that pushes up the squeegee 10 is hardly generated, and
As shown in (c) and (d), the adhesiveness between the wiring pad 2 and the metal mask 3 is good, and it is possible to obtain a bleed-free print of the solder paste 9 having a desired thickness and width. it can. Even if the openings are further miniaturized and the distance between the adjacent horizontal openings 7 is shortened, the force for pushing up the metal mask 3 or the squeegee 10 is hardly generated, and the solder does not have bleeding. A paste 9 is obtained.

If the pressing force of the solder paste 9 by the squeegee 10 is reduced so that the desired solder paste 9 can be printed in the vertical opening 5, the horizontal displacement of the solder paste 9 can be reduced. The press-in force of the solder paste 9 in the opening 7 may be reduced to cause blurring.

As described above, miniaturization of the printing pattern and improvement of the printing accuracy are contradictory requirements.

An object of the present invention is to provide a screen printing machine capable of printing a solder paste without causing blur or bleeding even in openings arranged at a fine pitch.

[0015]

In order to achieve the above object, the present invention provides a screen mask having a vertical opening (opening in which the longitudinal direction of the opening and the moving direction of the squeegee are substantially perpendicular to each other). ), A thin portion is provided in the peripheral edge portion, and a thick portion projecting from the other surface side of the screen mask is provided in the vicinity of both short sides (both edges in the lateral direction) of the vertical opening. It is characterized in that an overhanging portion that integrally overhangs from the thick portion to the thin portion is provided on the surface side.

[0016]

The present invention has a thin portion at the peripheral portion of the vertical opening,
By the thick part in the vicinity of both short sides of the vertical opening,
A step portion is formed on the other surface side of the screen mask. Due to this step portion, the squeegee is largely deformed in the thick portion and slightly deformed in the thin portion. Therefore, it is possible to reduce the force with which the squeegee press-fits the solder paste into the vertical opening in the thin portion. As a result, the force input in the vertical opening is changed to the force input in the horizontal opening (the opening in which the longitudinal direction of the opening is substantially parallel to the moving direction of the squeegee) that acts smaller than the force input. Can be matched. That is, since the printing condition in the vertical opening can be matched with the printing condition in the horizontal opening, the soldering can be performed without causing blurring or bleeding in the vertical opening and the horizontal opening arranged at a fine pitch. The paste can be printed.

Further, according to the present invention, when the squeegee is moved in a posture inclined with respect to the moving direction, the squeegee is extended to the other surface side of the thin portion from the thick portion to the thin portion integrally. The deformed state is almost the same as the deformed state by the stepped portion. As a result, even if the squeegee moves in a posture inclined with respect to the moving direction, the squeegee is surely deformed, and there is a possibility that blurring or blurring occurs when the squeegee is not deformed especially in the vertical opening. There is no.

[0018]

EXAMPLES Two examples of the screen printing machine according to the present invention will be specifically described below with reference to FIGS. 1 to 7 and 9 to 15. 1 to 7 show a first embodiment of the screen printing machine according to the present invention. 16 to 21 in the figure
The same reference numerals denote the same items. In the figure, 12 is a concave portion. The concave surface portion 12 is provided on the other surface side of the metal mask 3, in particular, a plurality of vertical opening portions 5 on the fine pitch side on the left side L.
And is provided in a square shape within a region surrounding the entire plurality of lateral openings 7. Of the concave portion 12, particularly the peripheral edge portion of the vertical opening 5 is formed in a thin portion 1 having a thickness H2.
1c, and particularly in the portions on both sides of the concave surface portion 12 in the vicinity of both short sides 51 of the vertical opening portion 5, a thick portion 11a having a thickness H1 (thickness outside the vertical opening portion 5). Portion) and a thick portion 11b (thickness portion inside the vertical opening 5), and at least one of both short sides 51 of the vertical opening 5 on the other surface side of the concave portion 12 On the other hand, in this example, the other surface side of the thin portion 11c from the inner short side 51 of the vertical opening 5 to the inner thick portion 11b is formed as a contact surface portion 11d with which the squeegee 10 contacts, and the concave surface is formed. Part 12
Four corners (four corners) of the thick portion 11b on the inner side of the other surface side
A portion of the thin portion 11c that is integrally and substantially vertically projected to the other surface side is defined as a protruding portion 11e having a wall thickness H1. As a result, the thick portion 11b on the inner side has a shape of I or a letter of construction (H-shape in the figure from the opening 5 side) when viewed in the moving direction a of the squeegee 1. .

The step portion 120 formed at the boundary between the thick portions 11a and 11b and the thin portion 11c by the concave portion 12 described above deforms the squeegee 10 to vertically open the solder paste 9 by the squeegee 10. A squeegee deforming means for reducing the pressure input to the portion 5 is configured. Also,
The above-mentioned contact surface portion 11d constitutes a squeegee contact means by which a squeegee 10 can obtain a press-fitting force to press the solder paste 9 into the vertical opening 5 in the longitudinal direction. Further, when the squeegee 10 moves in a posture inclined with respect to the movement direction a as shown in FIG. 1, the above-mentioned overhanging portion 11e moves the squeegee 10 to the squeegee deforming means (step portion 120).
The tilting squeegee deforming means is configured to deform in a manner substantially similar to the deformed state by.

It should be noted that the above-mentioned concave portion 12 having a rectangular shape is formed on the wiring pad 2 by the depth of the plurality of vertical openings 5 and the plurality of horizontal openings 7 on the fine pitch side of the left side L. The amount of the solder paste 9 to be printed is restricted to a small amount.

FIG. 3 is a partial plan view of the metal mask 3 showing the detailed dimensional relationship. In this figure, squeegee 1
The length X2 of the protrusion 11b in the direction in which 0 moves is greater than the distance X1 between the long sides 50 on the outside of the openings 5A located at both ends of the plurality of vertical openings 5, and the thickness of the inside The short side 71 inside the lateral opening 7 that is located across the portion 11b
It is smaller than the distance X3 between them. The overhanging portion 11e having the width X4 in the direction b in which the squeegee 10 moves has the long side 50 on the outside of the vertical opening 5A located at both ends and the horizontal opening 7a.
It is located between the inner short side 71 and the short side 71. Also, the overhanging portion 11 in a direction substantially perpendicular to the moving direction B of the squeegee 10.
The length Y2 of e is smaller than the distance Y1 between the inner short sides 51 of the vertical opening 5 that is located across the inner thick portion 11b, and is located at both ends of the plurality of horizontal openings 7. It is larger than the distance Y3 between the long sides 70 on the outside of the opening 7. Then, assuming that the length of the thick portion 11b on the inner side in the direction substantially perpendicular to the moving direction B of the squeegee 10 is Y4, according to the experiments by the present inventors, Y4≈ (0.2 to 0. 6) Good print results are obtained by selecting an arbitrary value of Y1.

The screen printing machine of the present invention in this embodiment has the above-mentioned construction, and its operation and operation will be described below. First, as the squeegee 10 is moved in the direction indicated by the arrow A, the solder paste 8 placed on the other side of the metal mask 3 and in front of the squeegee 10 is removed from the squeegee 10 by the metal. On the surface of the mask 3, the acting force in the direction toward the printed wiring board 1 and the rotating force on the surface are received, and the wiring pad 2 is placed on the wiring pad 2 through the plurality of vertical openings 5 and the plurality of horizontal openings 7. Printed as solder paste 9.

At this time, in the vertical opening 5, the thin portion 11c at the peripheral edge of the vertical opening 5 and the thick portions 11a and 11b near the short sides 51 of the vertical opening 5 are formed.
The stepped portion 120 formed by means of the squeegee 10 in the thick portions 11a and 11b as shown by the solid line in FIG.
4 is greatly deformed, and at the thin portion 11c, as shown in FIG.
The squeegee 10 is slightly deformed as shown by the chain double-dashed line. Therefore, it is possible to reduce the force with which the squeegee 10 press-fits the solder paste 9 into the vertical opening 5 in the thin portion 11c. As a result, it is possible to match the pressure input in the vertical opening 5 with the pressure input in the horizontal opening 7 that acts less than the pressure input. That is, FIG.
Since the printing conditions in the vertical openings 5 shown in (a) to (c) can be matched with the printing conditions in the horizontal opening 7 shown in FIGS. 6 (a) to (c), they are arranged in a fine pitch. The solder paste 9 can be printed without causing blurring or bleeding in the vertical openings 5 and the horizontal openings 7 that are formed. Here, the printing situation in the vertical opening 5 and the printing situation in the horizontal opening 7 are shown in FIG.
It will be described with reference to FIGS. 6A to 6C and FIGS. First, as shown in FIG. 5A, even after the squeegee 10 has passed through the long side 50 of the vertical opening 5, the tip of the squeegee 10 in the above-described deformed state is in the vertical opening 5. However, the force for press-fitting the solder paste 9 into the vertical opening 5 becomes small. To this end, FIG.
As shown in FIG.
The solder paste 9 is not press-fitted into the entire inside, and the press-fitted area of the solder paste 9 expands as the squeegee 10 moves. The situation is shown in Figure 6.
Similar to the lateral openings 7 shown in (a) and (b), the reaction force that pushes up the metal mask 3 and the squeegee 10 does not work. Therefore, as shown in comparison between FIG. 5C and FIG. 6C, unevenness in thickness, bleeding or blurring occurs regardless of the directionality of the vertical opening 5 and the horizontal opening 7. The solder 9 can be printed without it.

Further, in the screen printing machine of the present invention in this embodiment, among the other surface side of the concave portion 12, the four corners (four corners) of the thick portion 11b on the inside are integrally formed from the other surface side of the thin portion 11c. Overhanging portion 11e with thickness H1
Therefore, when the squeegee 10 moves in a posture inclined with respect to the moving direction a as shown by the two-dot chain line in FIG. 1 and FIG. As a result, the stepped portion 120 (squeegee deforming means) is deformed into a state substantially similar to the deformed state. As a result, even when the squeegee 10 moves in a posture inclined with respect to the moving direction (a), the tip of the squeegee 10 is surely deformed as described above, so that the squeegee 10 is particularly prominent in the vertical opening 5. There is no risk of blurring or bleeding when not deformed. Here, the cause of blurring or bleeding when the squeegee 10 moves in a posture inclined with respect to the moving direction a in the metal mask 3 not including the overhanging portion 11e of the present invention will be described. That is, as shown by the chain double-dashed line in FIG. 3, the squeegee 10 extends over the outer thick portion 11a, but the inner thick portion 1a.
Since it does not rest on 1b, the tip of the squeegee 10 only deforms to a state similar to the deformed state of the metal mask 3 of the conventional screen printing machine without the thick portion 11b on the inner side, and as a result, especially a plurality of The squeegee 10 is not sufficiently deformed in the end opening 5 of the vertical opening 5,
There is a risk of fading or blurring. However, since the screen printing machine of the present invention is provided with the above-mentioned overhanging portion 11e, there is no possibility that the above-mentioned blur or bleeding will occur.

As shown by the chain double-dashed line in FIGS. 1 and 3, the squeegee 10 is inclined with respect to the moving direction (a), whether or not it is intentional. It became slightly slanted by the play of time, and in the actual measurement by the inventors,
The inclination of 1 to 3 degrees is always observed, and therefore, in the opening portions 5A at both ends of the plurality of vertical opening portions 5, the squeegee 10 always has a tip because of the protruding portions 11e. , And is deformed at the thick portions 11a and 11b. Depending on the arrangement of the lead terminals of the electronic component, it may be possible to incline up to about 20 degrees, but even in this case, the screen printing machine of the present invention does not have the above-mentioned blurring and bleeding.

Further, in the screen printing machine of the present invention in this embodiment, the squeegee 10 contacts the other surface side of the thin portion 11c from the inner short side 51 of the vertical opening 5 to the inner thick portion 11b. Since the contact surface portion 11d is formed, the squeegee 10 comes into contact with the contact surface portion 11d, so that the press-fitting force that allows the solder paste 9 to be press-fitted into the vertical opening portion 5 in the longitudinal direction is obtained. As a result, as shown in FIG. 7, the squeegee 10 does not come into contact with the other surface side of the thin portion 11c on the side of the short side 51 on the outside of the vertical opening 5, and the press force acts on the solder paste 9. Even if the dead space DS is formed, the thin portion 11c on the short side 51 side inside the vertical opening 5 is formed.
The squeegee 10 comes into contact with the other surface of the (contact surface portion 11d) so that the solder paste 9 is inserted into the vertical opening portion 5 in the longitudinal direction toward the dead space DS side (the short side 51 outside the vertical silkworm portion 5). Since it can be press-fitted to the side), the solder paste 9 can be reliably printed. At this time, as shown in FIG.
If the dead space DS is formed on the other surface side of the thin portion 11c of both short sides 51 of the vertical opening 5, the pressing force for press-fitting the solder paste 9 into the vertical opening 5 cannot be obtained. There is a problem that the solder paste 9 is not pressed into both short side portions of the vertical opening 5. The screen printing machine of the present invention can solve the above-mentioned problems. Then, in the screen printing machine of the present invention, the above-mentioned contact surface portion 11d.
Is provided on the other surface side of the thin portion 11c on the short side 51 side inside the vertical opening 5 in the above example, but on the other surface of the thin portion 11c on the short side 51 side outside the vertical opening 5 Side or the other side of the thin portion 11c on both short sides 51 side of the vertical opening 5 may be provided.

9 to 12 show thick portions 11a and 11b.
It is a partial top view of the metal mask 3 which showed the modification of the shape of the overhanging part 11e and the concave part 12. Regarding the formation of the concave portion 12 on the metal mask 3, it is advisable to make the corners of the concave portion 12 (step portion 120) round or chamfered to facilitate the working operation as shown in FIGS. 9 and 10. In addition,
In FIG. 10, the thick portion 11'b on the inner side has two elongated U-shapes, but as shown by the chain double-dashed line, it has one I or D shape (11b). It may be. Further, as shown in FIG. 11, the inner wall thickness surrounded by the vertical opening 5 and the horizontal opening 7 is an advanced form of the processing for rounding the corners of the concave surface portion 12 (step portion 12). Part 11
The b may be shaped like a drum or a side view of the pulley. further,
As shown in FIG. 12, the overhanging portion 11'e is attached to the squeegee 10
It may be provided obliquely with respect to the moving direction B.

13 and 14 show a second embodiment of the screen printing machine according to the present invention. In the figure, the same reference numerals as those in FIGS. 1 to 12 and 16 to 21 indicate the same components. In the first embodiment described above, the electronic component 13 of the quarter flat package type (QFP type) in which the lead terminals 14 are extended in four directions is mounted as the electronic component.
In the second embodiment, two dual line type electronic components 130 having lead terminals 140 extending in two directions are mounted vertically and horizontally as electronic components.

In FIG. 13, two dual line type electronic components 130 are mounted vertically (vertically) in a direction substantially perpendicular to the moving direction a of the squeegee 10, and in FIG. Mold electronic component 130
2 are mounted on the left and right (horizontal) in the moving direction a of the squeegee 10, and a plurality of vertical openings 5 and a plurality of horizontal openings 7 are arranged in a row in the metal mask 3. Two
The columns are arranged in parallel. A square-shaped concave portion 12A is provided on the other surface side of the metal mask 3 so as to surround the plurality of vertical openings 5 in the two rows. As a result, the vertical opening 5
A thin portion 110c is formed in the peripheral edge portion of the vertical opening portion 5, and an outer thick portion 110a and an inner thick portion 110b are formed in the vicinity of both short sides 51 of the vertical opening portion 5, respectively. The thin portion 11 from at least one of the two short sides 51 to the thick portions 110a and 110b.
0c has a contact surface portion 110d formed on the other surface side thereof, and the thin portion 110d is formed from four corners of the thick portion 110b on the inner side thereof.
An overhanging portion 11e is formed on the other surface side of c.

On the other hand, in FIGS. 15 and 16 described above,
On the other surface side of the metal mask 3, a square concave surface portion 40 is formed.
Each is provided so as to surround a plurality of lateral openings 7 in a row. The second embodiment can achieve the same effects as those of the first embodiment described above.

FIGS. 15A and 15B are explanatory views showing modifications of the vertical opening and the horizontal opening. The opening is
In addition to the rectangular shape (5, 7) described above, the elliptical shape (5A, 7A) shown in (A), the elliptical shape (5B, 7B) shown in (B), etc. , 130, the lead terminals 14 and 140 may be elongated.

In the above embodiment, the overhanging portion 11
e, 11'e, 110e are the inner thick portions 11b, 1
1'b, 110b are integrally projected to the thin portions 11c, 110c, but the outer thick portions 11a, 110
A may be integrally projected from the thin portion 11c, 110c, or both the inner and outer thick portions 11a, 110a and 11b,
You may project from 11'b and 110b to the thin parts 11c and 110c integrally.

[0033]

As described above, according to the screen printing machine of the present invention, the difference in the printing condition (solder paste printing amount) depending on the direction of the opening provided in the screen mask with respect to the moving direction of the squeegee. In addition, the solder paste can be printed without causing blur or bleeding even at a fine pitch.

[Brief description of drawings]

FIG. 1 is a plan view of a printing unit of a screen printing machine, showing a first embodiment of the screen printing machine of the present invention.

FIG. 2 is a partially enlarged perspective view of a main part of a metal mask (screen mask).

FIG. 3 is a partially enlarged plan view of a main part of a metal mask (screen mask).

FIG. 4 is a sectional view taken along line IV-IV in FIG.

5 (a), (b) and (c) are V in FIG.
FIG. 6 is a cross-sectional view taken along the line V, which is an explanatory diagram showing a printing situation in a vertical opening.

6 (a), (b) and (c) are V in FIG.
FIG. 6 is a cross-sectional view taken along the line I-VI and is an explanatory diagram showing a printing situation in a lateral opening.

7 is a sectional view taken along line VII-VII in FIG.

FIG. 8 is an explanatory diagram showing a problem in the case where a dead space is formed on the other surface side of the thin portion on both short sides of the vertical opening.

FIG. 9 is a partial plan view showing a modification of the metal mask in which the shape of the corner of the step portion of the vertical opening is changed.

FIG. 10 is a partial plan view showing a modification of the metal mask in which the shape of the corner of the step portion of the vertical opening and the shape of the thick portion on the inner side are changed.

FIG. 11 is a partial plan view showing a modification of the metal mask in which the shape of the thick portion inside the vertical opening is changed.

FIG. 12 is a partial plan view showing a modification of the metal mask in which the shape of the thick portion inside the vertical opening is changed.

FIG. 13 is a plan view of a printing section of the screen printing machine showing the second embodiment of the screen printing machine of the present invention.

FIG. 14 is a plan view of a printing unit of the screen printing machine, showing a modification of the second embodiment of the screen printing machine of the present invention.

FIG. 15 (A) is an explanatory view showing an oval-shaped opening,
(B) is an explanatory view showing an elliptical opening.

FIG. 16 is an enlarged plan view of a printing unit of a conventional screen printing machine.

17 is a cross-sectional view taken along the line AA in FIG.

18 (a), (b), (c), and (d) are cross-sectional views taken along the line BB in FIG. 18, which are explanatory views showing a printing state in a vertical opening portion.

19 (a), (b), (c), and (d) are cross-sectional views taken along the line CC in FIG. 18, and are explanatory views showing a printing situation in a lateral opening.

20 is a cross-sectional view taken along the line DD in FIG.

21 is a cross-sectional view taken along the line EE in FIG.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Printed wiring board, 2 ... Wiring pad, 3 ... Metal mask (screen mask), 4 ... Thin part, 5 ... Vertical opening, 50 ... Long side, 51 ... Short side, 7 ... Horizontal opening, 8 And 9 ... Solder paste, 10 ... Squeegee, 11a and 11
0a ... outer thick part, 11b and 11'b and 110b
... Inner thick part, 11c and 110c ... Thin part, 11d
And 110d ... Contact part, 11e and 11'e and 110
e ... Overhang portion, 12 and 12A ... Recessed surface portion, 13 ... Quarter flat package type electronic component, 130 ... Dual line type electronic component, 14 and 140 ... Lead terminal.

Front page continuation (72) Inventor Hiroshi Okada 5-2 Koyodai, Ryugasaki-shi, Ibaraki Hitachi Techno Engineering Co., Ltd.

Claims (6)

[Claims] 1. A printed wiring board is provided on one side of a screen mask, and a scan is provided on the other side of the screen mask.
By moving the solder paste, the solder paste is pressed against the other surface of the screen mask, and the solder paste is printed in the shape of the opening on the printed wiring board through the opening provided in the screen mask. In the screen printing machine, in the screen mask, a peripheral portion of the opening whose longitudinal direction and the moving direction of the squeege are substantially perpendicular to each other is a thin portion, and The vicinity of both edges is a thick portion protruding from the other surface side of the screen mask, and the other surface side of the thin portion has a protruding portion integrally protruding from the thick portion to the thin portion. Characteristic screen printing machine. 2. A printed wiring board is provided on one side of the screen mask, and a scan is made on the other side of the screen mask.
By moving the solder paste, the solder paste is pressed against the other surface of the screen mask, and the solder paste is printed in the shape of the opening on the printed wiring board through the opening provided in the screen mask. In the screen printing machine, in the screen mask, on the other surface side of the vicinity of both edges in the lateral direction of the opening in which the longitudinal direction of the opening and the moving direction of the squeege are substantially right angles, The squeegee has a squeegee deforming means for deforming the squeegee to reduce the pressure input of the solder paste into the opening by the squeegee, and the squeegee deforming means moves the squeegee in a posture inclined with respect to the moving direction. When the squeegee is deformed, the squeegee deforming means deforms the squeegee in substantially the same manner as the squeegee deforming means. Characteristic screen printing machine. 3. The electronic component to be mounted on the printed wiring board is a quarter flat package type electronic component having lead terminals extending in four directions, and the screen mask has a longitudinal direction of the opening and a squeegee. A first opening whose moving direction is substantially perpendicular to the first opening and a second opening whose longitudinal direction is substantially parallel to the moving direction of the squeegee are arranged in a row in a square shape. In the case of the screen mask having the above-mentioned structure, a square-shaped concave surface portion is provided on the other surface side of the screen mask so as to surround the first opening portion and the second opening portion, and The peripheral portion of the first opening is formed as a thin portion, and portions of both sides of the concave portion near both edges in the lateral direction of the first opening are formed as thick portions, and the concave portion is formed. From the thick portion to the thin portion on the other surface side. The screen printing machine according to claim 1, wherein a portion protruding from the body serves as a protruding portion. 4. The electronic component to be mounted on the printed wiring board is a quarter flat package type electronic component in which lead terminals are extended in four directions, and the screen mask includes a longitudinal direction of the opening and a squeegee. A first opening whose moving direction is substantially perpendicular to the first opening and a second opening whose longitudinal direction is substantially parallel to the moving direction of the squeegee are arranged in a row in a square shape. In the case of a screen mask having a rectangular shape, a square-shaped concave surface portion is provided on the other surface side of the screen mask so as to surround the first opening and the second opening portion, and the other surface side of the concave surface portion is provided. The step portion on the other surface side of the step portion near the both edges in the lateral direction of the first opening is defined as the squeegee deforming means, and the other surface side of the concave surface portion is integrally formed from the squeegee deforming means. Squeegee deformation for tilting overhanging part The screen printing machine according to claim 2, which is a means. 5. A dual line type electronic component having lead terminals extending in two directions as an electronic component to be mounted on a printed wiring board, and as a screen mask, a longitudinal direction of an opening and movement of a squeegee. A screen in which a first opening whose direction is substantially perpendicular to each other and a second opening whose longitudinal direction and the moving direction of the squeegee are substantially parallel are arranged in two rows and two rows. In the case of a mask, a square-shaped concave surface portion is provided on the other surface side of the screen mask so as to surround at least the first opening portion, and a peripheral portion of the first opening portion of the concave surface portion. Is a thin portion, and portions of both sides of the concave surface portion in the vicinity of both edges in the lateral direction of the first opening are thin portions, and the thickness of the other surface side of the concave surface portion is Overhanging part that is integrally projected from the thin part to the thin part The screen printing machine according to claim 1, wherein the screen printing machine is formed as a part. 6. An electronic component mounted on a printed wiring board is a dual line type electronic component having lead terminals extending in two directions, and as a screen mask, a longitudinal direction of an opening and movement of a squeegee. A screen in which a first opening whose direction is substantially perpendicular to each other and a second opening whose longitudinal direction and the moving direction of the squeegee are substantially parallel are arranged in two rows and two rows. In the case of a mask, a square-shaped concave surface portion is provided on the other surface side of the screen mask so as to surround at least the first opening portion, and the first step among the step portions on the other surface side of the concave surface portion is provided. The stepped portion on the other surface side in the vicinity of both edges in the lateral direction of the opening is used as the squeegee deforming means, and the portion of the other surface side of the concave portion integrally projecting from the squeegee deforming means is deformed for tilting. Characterized by the means The screen printing machine according to claim 2.