JP3126659B2 - Cream solder printing method and apparatus - 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 apparatus for printing and applying cream solder on a printed circuit board.

[0002]

2. Description of the Related Art In recent years, in a technology for mounting an electronic component on a printed circuit board, an electrode portion of the electronic component has become increasingly finer. It is necessary to precisely apply a predetermined amount of cream solder to a land portion, so that high-precision printing is required.

[0003] Hereinafter, a conventional cream solder printing method will be described. For example, in Japanese Patent Application Laid-Open No. Hei 5-111994, as shown in FIG. 7A, the print mask 21 and the printed circuit board 22 are brought into close contact with each other, and after the cream solder is printed, the printed circuit board 22 on the stage 23 is moved up and down. Means 2
In the step of separating the plate by lowering at 4, the amount of deflection M of the print mask 21 and the amount of expansion S of the cream solder printed on the printed circuit board 22 are measured by the distance sensor 25 and recorded in the memory 26. Then, these maximum values at the time of plate separation are obtained, and this measurement operation is performed by changing the plate separation speed, and as shown in FIG. 7B, the deflection amount M of the print mask 21 and the elongation amount S of the cream solder are determined. The relative displacement amounts MR and SR obtained based on the maximum value are obtained for the plate separation speed,
A method is disclosed in which the plate separation speed is set to the speed at the point I where the relative displacements intersect to thereby prevent the cream solder from deteriorating in shape and tearing to obtain good printing results. In FIG. 7, reference numeral 27 denotes a squeegee, 28 denotes a controller of the lifting / lowering means, and 29 denotes an electronic control unit (ECU).

Japanese Patent Application Laid-Open No. 5-286113 discloses a printing mask 31 and a circuit board 32 as shown in FIG.
In the plate separation step after printing the cream solder by bringing the print mask into close contact, the downward displacement of the print mask 31 following the downward movement of the circuit board 32 by the driving means 33 is detected by the distance sensor 34, and the print mask is detected. A method of switching the lowering speed of the circuit board 32 from a low speed to a high speed on the assumption that the separation of the plate has been completed when the 31 has shifted from the downward bending displacement to the upward bending displacement is disclosed. In FIG. 8, 35
Is control means for controlling the driving of the driving means 33 based on the detection signal of the distance sensor 34.
A speed change command unit 37 and a drive control unit 38 are built in, and the drive control unit 38 includes a low speed control circuit 38 a and a high speed control circuit 3.
8b, the circuit board 32 is moved up to the printing position by the driving means 33 at a high speed, the descent is started at a low speed after printing, and the descent is performed at a high speed when the plate separation is completed. .

[0005]

However, in the method disclosed in Japanese Patent Application Laid-Open No. HEI 5-111994, the plate separation speed is uniquely determined by the speed near the intersection of the relative displacement of the print mask 21 and the relative displacement of the cream solder. However, such a method has a problem that good printing results cannot always be obtained.

In the method as disclosed in Japanese Patent Application Laid-Open No. 5-286113, the downward deflection of the print mask 31 which bends and deforms downward following the lowering of the circuit board 32 after printing is changed into an upward displacement. When it is determined that the separation of the printing mask 31 has been completed, a command to lower the circuit board 32 from a slow speed to a high speed can be given to eliminate waste of time. Since the transfer of the cream solder to the circuit board 32 has already been completed after the completion of the above, there is a problem that this does not become a solution for forming a good printing state.

In other words, in order to form a good printing state, it is important to control the condition of separation of the printing mask. This causes cream solder bleeding and bridging (connection between adjacent printing locations) that exceeds the printing area, and also causes clogging of the opening of the print mask, which causes a shortage of cream solder supply. This leads to a decrease in the mounting quality.

The present invention has been made in view of the above-mentioned conventional problems, and provides a cream solder printing method and apparatus capable of obtaining a good printing state of a solder cream by setting an appropriate printing mask release condition. It is an object.

[0009]

A cream solder printing method according to the present invention is a cream solder printing method for printing and applying cream solder to a printed circuit board using a screen mask plate and a squeegee. Until one of the printed circuit board and the screen mask plate reaches a plate separation position immediately before the mask plate and the printed circuit board are completely separated, one of the printed circuit board and the screen mask plate One is moved at a first moving speed in a direction away from one of the other, and when one of the printed circuit board and the screen mask plate reaches the plate separating position, the first speed is increased to the first speed. It is characterized by switching to a second moving speed higher than the moving speed.

[0010] Preferably, in the switching step, the first moving speed is set at the plate separation position so that brittle fracture occurs in the cream solder straddling between the printed circuit board and the screen mask plate. It is also possible to switch to the second moving speed.

In the switching step, the second moving speed may be 100 times or more higher than the first moving speed.

Further, the switching step includes a step of detecting a vibration waveform of the mask of the screen mask plate generated after the screen mask plate and the printed circuit board are separated, and thereby, the mask of the screen mask plate. Setting a maximum amplitude of the waveform based on the position of the free plane and a step of setting the plate separation position so as to minimize a vibration time of the waveform until the mask settles at the position of the free plane. It can also be provided.

Further, the switching step includes a step of measuring a cross-sectional shape of the cream solder coating printed on the printed circuit board, and a step of measuring the thickness of the cream solder coating in the measured cross-sectional shape. Setting the plate separation position so as to minimize the corner height of the cream solder.

The present invention also provides a cream solder printing apparatus for printing and applying cream solder to a printed circuit board using a screen mask plate and a squeegee. A moving device for moving one at a first moving speed and a second moving speed higher than the first moving speed in a direction away from one of the other, a screen mask plate after printing the cream solder, and the printed circuit board; Until one of the printed circuit board and the screen mask plate arrives at the plate separation position immediately before completely separated from the other, the printed circuit board and the screen mask plate are separated from one of the other. The printed circuit board is moved at a first moving speed in the direction of Control means for controlling the moving device so as to switch the first speed to the second moving speed when one of the screen mask plates arrives, and a printing state of the cream solder on the printed circuit board And a setting means for setting the plate separation position based on a detection result from the detection device.

Further, the detection device is a distance sensor disposed at a position separated from the position of a free plane of the mask of the screen mask of the screen mask plate by a predetermined distance, and the setting means is a distance sensor of the distance sensor. The vibration waveform of the mask of the screen mask plate may be detected based on the detection signal, and the plate separation position may be set from the maximum amplitude and the vibration time of the vibration waveform.

The distance sensor detects the vibration waveform of the mask of the screen mask plate generated after the screen mask plate after the cream solder printing and the printed circuit board are separated, and the setting means includes: The screen separation is performed so that the maximum amplitude of the waveform based on the position of the free plane of the mask of the screen mask plate and the vibration time of the waveform until the mask settles at the position of the free plane are minimized. The position can also be set.

Further, the detection device includes a detection sensor for measuring a cross-sectional shape of the cream solder coating printed on the printed circuit board, and a cream solder coating based on the cross-sectional shape of the cream solder coating measured by the detection sensor. Means for detecting the corner height of the plate, and the setting means may set the plate separation position based on the result detected by the detection device.

Further, the setting means sets the plate separation position such that the height of the corners with respect to the thickness of the cream solder coating film is minimized with respect to the thickness of the cream solder coating film. You can also

Further, the moving device may be a device for moving the printed circuit board with respect to a screen mask plate.

Further, the moving device may be a device for moving the screen mask plate with respect to the printed circuit board.

Further, the first moving speed is set to the second moving speed so that brittle fracture occurs in the cream solder straddling between the printed circuit board and the screen mask plate.
The plate separating position for switching to the moving speed may be set by the setting means.

Further, in the moving device, the second moving speed may be 100 times or more higher than the first moving speed.

According to the cream solder printing method of the present invention,
When the printed circuit board or the screen mask plate reaches the plate separation position just before the screen mask plate and the printed circuit board are separated, the moving speed of the printed circuit board or the screen mask plate is switched from low to high and the screen is moved immediately before the plate is separated. By brittlely breaking the cream solder that covers both the mask plate and the printed circuit board, it is possible to prevent the cream solder from adhering to the back of the screen mask plate,
In the next printing, it is possible to prevent the spread of cream solder printing, the occurrence of bridges, and the shortage of cream solder printing supply. That is, in order to reduce the shear stress when the cream solder is slipped from the opening of the mask of the screen mask plate to be smaller than the adhesive force between the cream solder and the printed circuit board, it is necessary to reduce the plate separation speed.
If you try to complete the separation at a low speed, the cream solder that straddles the screen mask plate and the printed circuit board will be ductile broken, and some of the ductile broken cream solder will appear as corners, while the other part will be screened. Although appearing as adhesion to the back surface of the mask plate, sharpening due to brittle fracture can be prevented by increasing the plate separation speed just before the plate separation as described above.

When the vibration waveform of the mask of the screen mask plate generated when the screen mask plate after the cream solder printing is separated from the printed circuit board is detected, the cream solder is sufficiently inserted into the opening of the mask of the screen mask plate. If the plate separation speed is switched from low to high at the remaining position, the amplitude and vibration time will appear large, and if the plate separation speed is reduced until completion, the amplitude will appear as a large swell, so minimize the maximum amplitude and vibration time of the vibration waveform. By setting the plate separation position as described above, the corner of the cream solder shape can be prevented.

Further, the cross-sectional shape of the cream solder coating printed on the printed circuit board is directly measured, and the plate separating position is set so as to minimize the height of the corner with respect to the thickness of the cream solder coating. The corner of the cream solder shape can be prevented.

Further, according to the cream solder printing apparatus of the present invention, by detecting the vibration waveform of the screen mask plate, or by detecting the height of the corner with respect to the thickness of the solder coating,
An optimal plate separation position can be set, and a good cream solder printing shape can be obtained by the above method.

[0027]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A cream solder printing apparatus according to an embodiment of the present invention will be described below with reference to FIGS.

In FIG. 1, 1 is a screen mask plate,
2 is a printed circuit board, 3 is a squeegee, 4 is cream solder, 5 is a stage for supporting the printed circuit board 2 so as to be able to move up and down, 6 is a vertical moving mechanism of a stage 5 composed of, for example, a ball screw and a nut, and 7 is, for example, This is driving means for the vertical movement mechanism, which is constituted by a motor for rotating the nut forward and reverse to raise and lower the ball screw. A distance sensor 8 is disposed at an appropriate distance above the screen mask plate 1, and the mask waveform detecting means 9 detects the mask of the screen mask plate 1 based on the displacement of the mask of the screen mask plate 1 detected by the distance sensor 8. Is detected by the drive control means 10 to which the detection result is input.
Is configured to be driven.

The operation of the cream solder printing apparatus configured as described above will be described. The printed circuit board 2 is lifted by the stage 5 and brought into contact with the screen mask plate 1. Next, the cream solder 4 is supplied onto the screen mask plate 1, and the cream solder 4 is scraped off with a squeegee 3 while the cream solder 4 is in the opening (hereinafter referred to as a mask opening) 11 formed in the mask of the screen mask plate 1. Is filled with cream solder 4. For example, when a squeegee 3 made of a soft elastic deformation body such as urethane rubber is used,
As shown in FIG. 2, the cream solder 4 is scraped off to restore elasticity in the mask opening 11, and the printed thickness of the cream solder, that is, the average thickness t of the printed cream solder is the thickness T of the screen mask plate 1. Thinner than that. In FIG. 2, reference numeral 12 denotes a copper foil land of the printed circuit board 2.

When the filling of the cream solder 4 is completed, a step of separating the printed circuit board 2 which is in close contact with the screen mask plate 1 from the screen mask plate 1 is started. FIG. 3 shows the behavior of the screen mask plate 1 and the state of the cream solder 4 filled in the mask opening 11 at that time. That is, FIG.
The printed circuit board 2 is lowered at a predetermined speed from the completion state of the filling of the cream solder 4 shown in FIG. 3A, and passes through the free plane state of the mask of the screen mask plate 1 shown in FIG. Further descend toward the plate release state shown. In the steps (b) to (c), the cream solder 4 filled in the mask opening 11 is gradually removed from the mask opening 11 in a state of being in close contact with the printed circuit board 2. Then, when the plate is completely separated, the mask of the screen mask plate 1 vibrates due to its elastic restoring force as shown in FIG. 3D, and then the mask of the screen mask plate 1 is moved as shown in FIG. While standing still on the free plane, the printed circuit board 2 further descends toward the transport position. The shape of the cream solder 4 to be transferred to the printed circuit board 2 is determined by controlling the lowering speed of the printed circuit board 2 in the step of separating the screen mask plate 1, particularly in the steps (b) to (c) of FIGS.

More specifically, in order for the cream solder 4 filled in the mask opening 11 to be transferred onto the printed circuit board 2, it is necessary to remove the cream solder 4 from the wall surface of the mask opening 11. The adhesive force generated between the cream solder 4 and the printed circuit board 2 must be larger than the strong force. For example, in the case of the cream solder 4 of a type comprising a viscous fluid having thixotropic properties, if the cream solder 4 is to be sheared from the wall surface of the mask opening 11 at a high speed, a large shear stress is generated. If the adhesive force between the solder paste and the circuit board 2 is smaller, the cream solder 4 is left in the mask opening 11. According to an experiment, the separation speed of the printed circuit board 2 for separating the printed circuit board 2 from the screen mask plate 1 having a mask thickness of 150 μm is appropriately about 0.1 mm / s. The appropriate value depends on the viscosity characteristics of the cream solder 4.

Next, even when the screen mask plate 1 and the printed circuit board 2 are completely separated from each other at a low plate separation speed (for example, about 0.1 mm / sec), the cream solder 4 transferred onto the printed circuit board 2 is removed. The print shape is not good. This is a screen mask plate 1 and a printed circuit board 2
This is because the corners 14 shown in FIG. 5 are generated due to the ductile fracture of the cream solder 4 straddling the two when the plate is separated from the plate. A part of the cream solder 4 that has been ductile-destructed appears as corners of the printed sectional shape, and another part appears as adhesion to the back surface of the screen mask plate 1. The cream solder adhered to the back surface causes printing spread of the cream solder at the next printing. In order to solve this problem, the cream solder 4 extending between the screen mask plate 1 and the printed circuit board 2 may be brittlely broken when the plate is separated. For this purpose, the screen mask plate 1 and the printed circuit board 2 are not completely separated from each other while maintaining the low plate separation speed. Instead, the plate separation speed is increased at an appropriate position to mask the cream solder 4 at once. It is required to be separated from the opening 11. According to an experiment, the separation speed may be about 20 mm / s. When the moving speed of the printed circuit board, that is, the plate releasing speed is switched from a low speed to a high speed, it is preferable to switch the speed to 100 times or more in order to more surely cause brittle fracture of the cream solder. For example, about 0.1 mm / se
It is preferable to switch the low speed of c to a high speed of about 20 mm / sec.

Next, a method for obtaining an appropriate position for increasing the plate separation speed (this position is referred to as "plate separation position" in the present specification) will be described with reference to FIG. FIG. 4 is a diagram showing the behavior of the mask of the screen mask plate 1 when the plate is separated. The horizontal axis indicates the descent time of the printed circuit board, and the vertical axis indicates the displacement ΔH of the central portion of the mask with respect to the free plane. I have. The points in time when the states shown in FIGS. 3 (a) to (e) are set are indicated by (a) to (e) in FIG. The part for measuring the vibration is preferable because the central part of the mask vibrates most, but is not limited to this.

Here, in the process from (b) to (c) in FIG. 4, the cream solder 4 is
If the plate separation speed is switched from a low speed to a high speed at a position where the plate is sufficiently left, the amplitude and the vibration time appear large. When the switching position is gradually delayed, in other words, when the board descent time to the switching position is gradually increased, the amplitude and the vibration time are reduced, and the cream solder 4 is completely removed from the mask opening 11. When the plate is separated at a low speed to a position away from the plate, the amplitude appears as a large swell, and the vibration time increases.

For example, specifically, as shown in FIG.
Even after the optimum plate separation position, for example, 0.1 m
If the separation of the printing plate at a low speed of about m / sec is continued, the maximum amplitude width becomes small, but the vibration time becomes long. Further, as shown in FIG. 11, when the plate separation is performed by switching from a low speed (for example, 0.1 mm / sec) to a high speed (for example, 20 mm / sec) before reaching the optimum plate separation position, the vibration time is short. However, the maximum amplitude width becomes large.

Accordingly, in order to reduce the maximum amplitude width and at the same time to shorten the vibration time and reduce the corners 14 of the cream solder 4, as shown in FIG. In other words, between the screen mask plate 1 and the printed circuit board 2 at the plate separation position after cream solder printing and immediately before the screen mask plate 1 and the printed circuit board 2 are completely separated from each other. It is necessary to switch the relative separation speed from low to high. The plate separation position is between the point (b) where the amplitude of the waveform intersects the free plane of the mask and the point (c) where the maximum amplitude of the waveform is obtained. For example, a rising portion of the waveform having the maximum amplitude width is preferable. On the other hand, Japanese Patent Application Laid-Open No. 5-286113
When the deflection of the mask in the method disclosed in Japanese Unexamined Patent Application Publication No. H10-15012 switches from below to above means when the point (c) has passed,
Since the separation of the plate has passed the point (c), the above-described problem occurs. When the moving speed is switched at the plate separating position in the above embodiment of the present invention, specifically, in FIG. 4, any moving speed, for example, 0.1 mm / sec or 20 mm / se
It may be c, but it is 0.1 mm from (b) to the plate separating position.
/ Sec, a low moving speed of 2 sec.
It is preferably set to 0 mm / sec.

Therefore, in the present embodiment, the position at which the plate separation speed is switched from low to high is changed, the displacement of the mask of the screen mask plate 1 is detected by the distance sensor 8, and the mask waveform detection means 9 detects the mask displacement. The vibration waveform of the mask of the screen mask plate 1 after separation is detected, and the relationship between the speed switching position and the amplitude and the vibration time of the screen mask plate 1 at the time of separation of the plate is obtained. Set to a remote position. In this case, instead of changing the plate separating position, the moving speed may be changed to achieve the same effect.

In this way, the plate separation speed is switched from low to high by the drive control means 10 at the plate separation position thus set, so that the screen mask plate 1 and the printed circuit board 2 are both straddled immediately before the plate separation. The screen mask plate 1 that can brittlely break the cream solder 4
Of the cream solder 4 on the back surface of the solder paste, and prevent the cream solder 4 from bleeding, bridging or shortage of the cream solder printing supply at the next printing. The shape is obtained.

In the above embodiment, the mask waveform detecting operation and the setting and changing operations of the plate separation position are performed by one mask waveform detecting means 9, but they may be performed by separate means.

Further, in the above embodiment, as shown in FIG. 1, a judging unit 91 for judging the printing condition of the cream solder is further provided, and the judging unit 91 determines that the printing condition of the cream solder is out of an allowable range. If it is determined, the plate separation position set by the mask waveform detection means 9 may be changed. It is preferable that the allowable range is such that a bridge state in which adjacent cream solder portions are erroneously connected to each other due to defective cream solder printing does not occur. It is preferable to change the allowable range as needed.

Further, in the above-described embodiment, the method of detecting the vibration waveform of the screen mask plate 1 to obtain the plate separation position has been exemplified. However, the present invention is not limited to this. For example,
If the plate separation position is not appropriate, as shown in FIG. 5, a corner 14 appears in the printed cross-sectional shape of the cream solder 4 after the cream solder printing, and therefore, as shown in FIG. The height h of the corner is measured from the printed cross-sectional shape of the cream solder 4 at various times,
Even if the position where the ridge height h is lowest is set as the plate separating position, a good cream solder print shape can be obtained. The plate separation position in FIG. 6 is indicated by the distance from the free plane of the mask.

FIG. 9 is a cross-sectional view of the above-described embodiment.
The method for detecting is shown. After the printing of the cream solder, the printed circuit board 2 is taken out of the stage 5 and positioned at a cornering measurement position indicated by a solid line, and a laser is emitted toward the printed circuit board 2 by the laser emitting / receiving device 81, and the printed circuit board 2 The reflected laser beam is received again by the laser emitting / receiving device 81 and the printed circuit board 2
The cross-sectional shape of the cream solder on the surface of is measured. The laser irradiation from the laser emitting / receiving device 81 to the printed circuit board 2 is preferably performed along the moving direction of the squeegee 3, and at least one cream solder portion is provided for each cream solder portion on the printed circuit board 2. Is irradiated so that the cross-sectional shape of the substrate can be obtained. The measured data is stored in the cross-sectional shape detecting section 82, and when the height of the corner portion of the cream solder portion stored in the cross-sectional shape detecting section 82 is greater than or equal to the allowable height by the shape determining section 83. Then, the drive control means 10 controls the drive of the drive means 7 so that the set position of the plate separation position is changed, and the descent speed of the stage 5 is switched from low speed to high speed at the changed plate separation position.

In the above embodiment, the shape determining operation and the operation for setting and changing the plate separation position are performed by one shape determining unit 83.
, But may be performed in separate parts. Preferably, the allowable height is set to a height that does not cause a bridge state in which the corner portions fall between adjacent cream solder portions and are erroneously connected to each other,
After empirically setting, it is preferable to change the print condition as appropriate by checking the print state.

In the case where the plate separation position is set by measuring the cross-sectional shape of the corner as described above, the plate separation position may be set without detecting the waveform shown in FIG.
In order to perform drive control with higher accuracy, the plate separation position by measuring the angled cross-sectional shape and the plate separation position by detecting the waveform in FIG. 1 are respectively set, and an intermediate position between the two is set as the plate separation position. Is also good. Further, when there are a large number of corners, the plate separation positions may be calculated by calculating the respective plate separation positions and taking the average of them.

In the above embodiment, as a method of separating the printed circuit board 2 from the screen mask plate 1 after the cream solder printing, the stage 5 supporting the printed circuit board 2 is driven without moving the screen mask plate 1. It is driven by means 7. However, the present invention is not limited to this. For example, the screen mask plate 1 may be separated from the printed circuit board 2 by the driving unit 71 as shown in FIG. In the embodiment of FIG. 12, the screen mask plate 1 is connected to a ball screw 61 as an example of a vertical movement mechanism by a bracket 62, and the ball screw 61 is rotated by a motor 71 as an example of a driving unit. I have. The stage 5 supporting the printed circuit board 2 includes:
When the printed circuit board 2 is carried into the stage 5 and when the printed circuit board 2 is carried out of the stage 5, the printed circuit board 2 is lowered from the printing position by the stage vertical cylinder 72.
Therefore, as in the previous embodiment, after the cream solder printing, the screen mask plate 1 is raised at a low speed with respect to the printed circuit board 2 by the motor 71, and the screen mask plate 1 and the printed circuit board 2 are moved to the plate separation position. Is reached, the speed at which the screen mask plate 1 is raised by the motor 71 is switched from a low speed to a high speed, so that the same operation and effect as described above can be achieved.

[0046]

According to the cream solder printing method of the present invention, as apparent from the above description, the printed circuit board or the screen mask plate reaches the plate separation position immediately before the screen mask plate and the printed circuit board are separated. By switching the moving speed of the printed circuit board or the screen mask plate from a low speed to a high speed, the cream solder bridging both the screen mask plate and the printed circuit board can be brittlely destroyed just before the plate is released, and thereby the screen can be screened. Prevents solder paste from adhering to the back side of the mask plate, and prevents cream solder printing bleeding, bridging, and shortage of cream solder printing supply during the next printing. You can get the status.

Further, a vibration waveform of the screen mask plate generated when the screen mask plate after the cream solder printing is separated from the printed circuit board is detected, and the maximum amplitude and the vibration time of the vibration waveform are minimized. By setting the separation position, it is possible to set appropriate printing plate separation conditions of the print mask, and it is possible to obtain a good printing state of the solder cream.

Further, by directly measuring the shape and dimensions of the cream solder coating printed on the printed circuit board and setting the plate separation position so as to minimize the height of the corner with respect to the thickness of the cream solder coating. Appropriate printing mask separation conditions can be set, and a good solder cream printing state can be obtained.

Further, according to the cream solder printing apparatus of the present invention, by detecting the vibration waveform of the screen mask plate, or by detecting the height of the corner with respect to the thickness of the solder coating,
An optimal plate separation position can be set, and a good cream solder printing shape can be obtained by the above method.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of a cream solder printing apparatus according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view showing a filling state of cream solder into a mask opening of the embodiment.

FIG. 3 is an explanatory diagram of a plate separation process between a screen mask plate and a printed circuit board in the same embodiment.

FIG. 4 is an explanatory diagram of a behavior of the screen mask plate when the plate is separated in the embodiment.

FIG. 5 is an explanatory diagram of a printed cross-sectional shape after cream solder printing.

FIG. 6 is a graph showing the relationship between the plate separation position and the ridge height in another embodiment of the present invention.

FIG. 7 shows a conventional cream solder printing method, in which (a)
FIG. 3B is a schematic configuration diagram, and FIG. 4B is a correlation diagram of the relationship between the relative displacement of the print mask and the relative displacement of the cream solder.

FIG. 8 is a schematic configuration diagram of another conventional cream solder printing method.

FIG. 9 is a schematic configuration diagram of a cream solder printing apparatus according to still another embodiment of the present invention.

FIG. 10 is an explanatory diagram of the behavior of the screen mask plate at the time of plate separation when the plate separation position is different from that of FIG. 4;

FIG. 11 is an explanatory diagram of the behavior of the screen mask plate at the time of plate separation when the plate separation position is different from that of FIG. 4;

FIG. 12 is a schematic configuration diagram of a cream solder printing apparatus according to still another embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Screen mask plate 2 Printed circuit board 3 Squeegee 4 Cream solder 5 Stage 6 Vertical movement mechanism 7 Driving means 8 Distance sensor 9 Mask waveform detection means 10 Drive control means 14 Square 61 Ball screw 71 Motor 72 Stage vertical cylinder 81 Laser emission and reception Device 82 Cross-sectional shape detection unit 83 Shape determination unit 91 Determination unit

──────────────────────────────────────────────────の Continuing on the front page (72) Inventor Hiroaki Onishi 1006 Kazuma Kadoma, Osaka Prefecture Inside Matsushita Electric Industrial Co., Ltd. (56) References JP-A-4-236490 (JP, A) JP-A-4-236491 (JP, A) JP-A-4-65243 (JP, A) JP-A-4-14288 (JP, A) JP-A-5-345406 (JP, A) JP-A-5-286113 (JP, A) JP-A-5-111994 (JP, A) JP-A-7-32578 (JP, A) JP-A-6-328659 (JP, a) JP flat 3-193449 (JP, a) JP flat 4-44848 (JP, a) JP flat 6-255078 (JP, a) (58 ) investigated the field (Int.Cl. ⁷ , DB name) B41F 15/26 B41F 15/08 303 B41M 1/12 H05K 3/34 505

Claims (14)

(57) [Claims] 1. A cream solder printing method for printing and applying cream solder to a printed circuit board using a screen mask plate and a squeegee, wherein the screen mask plate and the printed circuit board are completely separated after the cream solder printing. Until one of the printed circuit board and the screen mask plate reaches the immediately preceding plate separation position, the first movement is performed in a direction to separate one of the printed circuit board and the screen mask plate from the other. When one of the printed circuit board and the screen mask plate reaches the plate separation position, the first
A cream solder printing method, wherein the speed is switched to a second moving speed higher than the first moving speed. 2. In the switching step, the first moving speed is changed to the second moving speed at the plate separating position so that brittle fracture occurs in cream solder straddling between the printed circuit board and the screen mask plate. The cream solder printing method according to claim 1, wherein the method is switched to a moving speed. 3. The cream solder printing method according to claim 1, wherein in the switching step, the second moving speed is at least 100 times faster than the first moving speed. 4. The switching step includes: detecting a vibration waveform of a mask of the screen mask plate that occurs after the screen mask plate and the printed circuit board are separated; and thereby, the mask of the screen mask plate. Setting a maximum amplitude of the waveform based on the position of the free plane and a step of setting the plate separation position so as to minimize a vibration time of the waveform until the mask settles at the position of the free plane. The cream solder printing method according to any one of claims 1 to 3, which is provided. 5. The switching step includes: measuring a cross-sectional shape of the cream solder coating printed on the printed circuit board; and determining a cross-sectional shape of the cream solder coating with respect to a thickness of the cream solder coating. 5. The method of printing a cream solder according to claim 1, further comprising the step of: setting the plate separating position so as to minimize the height of the corner of the cream solder. 6. A cream solder printing apparatus for printing and applying cream solder to a printed circuit board using a screen mask plate and a squeegee, wherein one of the printed circuit board and the screen mask plate is separated from the other. A moving device for moving in a direction at a first moving speed and a second moving speed higher than the first moving speed; and after printing the cream solder and immediately before the screen mask plate and the printed circuit board are completely separated. Until one of the printed circuit board and the screen mask plate reaches the plate separation position, the first moving speed is set in a direction in which one of the printed circuit board and the screen mask plate is separated from the other. Move either the printed circuit board or the screen mask plate to the plate separation position. Control means for controlling the moving device so as to switch the first speed to the second moving speed when one of the two has reached; and a detecting device for detecting a printing state of the cream solder on the printed circuit board. Setting means for setting the plate separation position based on a detection result from the detection device, and a cream solder printing device. 7. The detecting device is a distance sensor disposed at a position separated by a predetermined distance from a position of a free plane of the mask of the screen mask of the screen mask plate. 7. The cream solder printing apparatus according to claim 6, wherein a vibration waveform of the mask of the screen mask plate is detected based on the detection signal, and the plate separating position is set based on a maximum amplitude and a vibration time of the vibration waveform. . 8. The distance sensor detects the vibration waveform of the mask of the screen mask plate generated after the screen mask plate after the cream solder printing and the printed circuit board are separated, and the setting means includes: The maximum amplitude of the waveform based on the position of the free plane of the mask of the screen mask plate,
8. The cream solder printing apparatus according to claim 7, wherein the plate separating position is set so as to minimize a vibration time of the waveform until the mask settles at the position of the free plane. 9. A detection sensor for measuring a cross-sectional shape of the cream solder coating printed on the printed circuit board, and a cream solder based on the cross-sectional shape of the cream solder coating measured by the detection sensor. Means for detecting the height of the corner of the plate, wherein the setting means sets the plate separation position based on a result detected by the detection device.
3. A cream solder printing apparatus according to item 1. 10. The setting means sets the plate separation position so that the height of the corners with respect to the thickness of the cream solder coating film is minimized with respect to the thickness of the cream solder coating film. The cream solder printing apparatus according to claim 9, wherein: 11. The cream solder printing apparatus according to claim 6, wherein the moving device is a device that moves the printed circuit board with respect to a screen mask plate. 12. The cream solder printing apparatus according to claim 6, wherein the moving device is a device that moves the screen mask plate with respect to the printed circuit board. 13. The plate separating position for switching the first moving speed to the second moving speed so that brittle fracture occurs in cream solder straddling between the printed circuit board and the screen mask plate. 13. The cream solder printing apparatus according to claim 6, wherein the setting is performed by a setting unit. 14. The cream solder printing apparatus according to claim 6, wherein in the moving device, the second moving speed is at least 100 times faster than the first moving speed.