JPH08336946A - Cream solder printing method and apparatus therefor - Google Patents

Abstract

PURPOSE: To obtain good printing conditions of solder cream by setting proper snap off conditions in cream solder printing with the use of a screen mask plate and a squeegee. CONSTITUTION: In a process in which a printed circuit board 2 or a screen mask plate 1 are moved relatively to separate from each other after printing of cream solder, when the circuit board 2 or the mask plate 1 reaches a snap off position right before the mask plate 1 and the circuit board 2 separate from each other, the transfer speed of the circuit board 2 or the mask plate 1 is shifted from low to high. The snap off position is set up in such a way that the oscillation wave form of the mask of the mask plate 1 which is generated when the mask plate 1 and the circuit board 2 separate from each other after the cream solder printing is detected by a mask wave form detection means, and the maximum amplitude and the oscillation time are minimized.

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 to a printed circuit board.

[0002]

2. Description of the Related Art In recent years, in the technology of mounting electronic parts on a printed circuit board, the electrode parts of electronic parts are becoming finer and finer, and the fine parts formed on the printed circuit board in correspondence with the electrode parts. It is necessary to accurately apply a predetermined amount of cream solder to the land portion, and therefore highly accurate printing is required.

A conventional cream solder printing method will be described below. For example, in Japanese Patent Laid-Open No. 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 to print cream solder, and then the printed circuit board 22 on the stage 23 is moved up and down. Means 2
In the step of lowering at 4 to separate the plate, the deflection amount M of the print mask 21 and the extension amount 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, the maximum values of them at the time of plate separation are obtained, and this measurement work is performed by changing the plate separation speed. As shown in FIG. 7B, the deflection amount M of the printing mask 21 and the elongation amount S of the cream solder S Relative displacements MR and SR calculated based on the maximum value are calculated for the plate separation speed,
There is disclosed a method in which the plate separation speed is set to a speed at a point I where the relative displacement amount intersects to prevent the shape deterioration and tearing of the cream solder and obtain a good printing result. In addition, in FIG. 7, 27 is a squeegee, 28 is a controller of an elevating means, and 29 is an electronic control unit (ECU).

Further, in Japanese Patent Laid-Open No. 5-286113, as shown in FIG. 8, a print mask 31 and a circuit board 32 are provided.
In the plate separating step after the printing of the cream solder by bringing them into close contact with each other, the downward displacement of the print mask 31 following the lowering of the circuit board 32 by the drive means 33 is detected by the distance sensor 34, and the print mask is detected. A method is disclosed in which the lowering speed of the circuit board 32 is switched from low speed to high speed on the assumption that the plate separation is completed when the downward deflection displacement of 31 changes to the upward deflection displacement. In FIG. 8, 35
Is a control means for driving and controlling the drive means 33 based on the detection signal of the distance sensor 34, and includes a lift stop command section 36,
A speed conversion command unit 37 and a drive control unit 38 are built in, and the drive control unit 38 includes a low speed control circuit 38a 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 the printing, and is lowered at a high speed when the plate separation is completed. .

[0005]

However, in the method disclosed in Japanese Patent Laid-Open No. 5-111994, the plate separation speed is unique to the speed in the vicinity of the intersection of the relative displacement amount of the printing mask 21 and the relative displacement amount of the cream solder. However, there is a problem that a good printing result cannot always be obtained by such a method.

Further, in the method disclosed in Japanese Patent Laid-Open No. 5-286113, the downward flexural displacement of the print mask 31, which is flexibly deformed downward following the downward movement of the circuit board 32 after printing, is changed to upward displacement. When it is determined that the plate separation of the print mask 31 is completed, a waste of time can be eliminated by issuing a command to lower the circuit board 32 from a slow speed to a high speed. Since the transfer of the cream solder to the circuit board 32 has already been completed after completion of the above, there is a problem that this is not a solution for forming a good printed state.

That is, in order to form a good printing state, it is important to control the plate separation condition of the print mask. If an inappropriate plate separation condition is set, a predetermined printing area is gathered at a predetermined area. This may cause bleeding of the cream solder that exceeds the printing area, bridges (connection between adjacent printing points), and may also cause clogging of the openings of the printing mask, which causes insufficient supply of cream solder, and This leads to a deterioration of the attachment quality.

In view of the above-mentioned conventional problems, the present invention 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 plate separation condition. It is an object.

[0009]

A cream solder printing method of the present invention is a cream solder printing method in which cream solder is printed and applied to a printed circuit board by using a screen mask plate and a squeegee. Either the printed circuit board or the screen mask plate until either the printed circuit board or the screen mask plate reaches the plate separation position immediately before the mask plate and the printed circuit board are completely separated. When one of the printed circuit board and the screen mask plate reaches the plate separation position, the first speed is set to the first speed by moving the one at a first moving speed in a direction away from the other. It is characterized in that the second moving speed which is faster than the moving speed is switched.

[0010] Preferably, in the switching step, the first moving speed is set at the plate separating position so that brittle fracture occurs in the cream solder extending 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 faster than the first moving speed.

The switching step includes a step of detecting a vibration waveform of the mask of the screen mask plate that occurs after the screen mask plate and the printed circuit board are separated from each other, and thereby, the mask of the screen mask plate. And the step of setting the plate separation position so as to minimize the maximum amplitude of the waveform based on the position of the free plane and the vibration time of the waveform until the mask settles at the position of the free plane. It can be provided.

Further, the switching step includes a step of measuring a sectional shape of the cream solder coating film printed on the printed circuit board, and a step of measuring the sectional shape of the cream solder coating film with respect to the thickness of the cream solder coating film. The step of setting the plate separation position so as to minimize the corner rising height of the cream solder.

Further, the cream solder device of the present invention is a cream solder printing device for printing and applying cream solder to a printed circuit board by using a screen mask plate and a squeegee. A moving device that moves one of them in a direction away from the other at a first moving speed and a second moving speed that is faster than the first moving speed; and after the printing of the cream solder, the screen mask plate and the printed circuit board. Until either one of the printed circuit board and the screen mask plate reaches the plate separation position immediately before and completely separating, one of the printed circuit board and the screen mask plate is separated from the other. The printed circuit board at the plate separating position while moving at a first moving speed in a direction Control means for controlling the moving device so as to switch the first speed to the second moving speed when either one of the screen mask plates reaches, and a printing state of the cream solder on the printed circuit board. And a setting device for setting the plate separation position based on the detection result from the detection device.

Further, the detecting device is a distance sensor arranged at a position separated from the position of the free plane of the mask of the screen mask of the screen mask plate by a predetermined distance, and the setting means is the distance sensor. It is also possible to detect the vibration waveform of the mask of the screen mask plate based on the detection signal and set the plate separation position from the maximum amplitude of the vibration waveform and the vibration time.

Further, 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, The maximum amplitude of the waveform based on the position of the free plane of the mask of the screen mask plate, and the plate separation so as to minimize the vibration time of the waveform until the mask settles at the position of the free plane. It is also possible to set the position.

Further, the above-mentioned detecting device detects the cross-sectional shape of the cream solder coating film printed on the printed circuit board and the cream solder from the cross-sectional shape of the cream solder coating film measured by the detection sensor. It is also possible to provide a means for detecting the corner rising height of, and the setting means to set the plate separation position based on the result detected by the detection device.

Further, the setting means sets the plate separating 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. You can also

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

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 the brittle fracture occurs in the cream solder extending 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.

In the moving device, the second moving speed may be 100 times faster 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 speed to high speed and the screen is moved immediately before the plate separation. By brittlely breaking the cream solder that extends over both the mask plate and the printed circuit board, it is possible to prevent the cream solder from adhering to the back surface of the screen mask plate,
It is possible to prevent printing bleeding of cream solder, generation of a bridge, and insufficient supply of cream solder printing during the next printing. That is, it is necessary to slow down the plate separation speed in order to make shear stress when the cream solder is removed from the opening of the mask of the screen mask plate smaller than the adhesive force between the cream solder and the printed circuit board.
When attempting to complete the plate separation at a slow speed, the cream solder that spreads over the screen mask plate and the printed circuit board undergoes ductile fracture, some of this ductile fractured cream solder appears as corners, and the other part of the screen. Although it appears as adhesion to the back surface of the mask plate, the sharpness due to brittle fracture can be prevented by increasing the plate separation speed as described above immediately before the plate separation.

Further, 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 in the opening of the mask of the screen mask plate. When the plate separation speed is switched from low speed to high speed at the remaining position, the amplitude and vibration time become large, and when the plate separation speed is made low, the amplitude appears as a large swell, so the maximum amplitude and vibration time of the vibration waveform are minimized. By setting the plate separation position as described above, it is possible to prevent cornering of the cream solder shape.

Also, the plate separation position is set so that the cross-sectional shape of the cream solder coating film printed on the printed circuit board is directly measured and the height of the corners is minimized with respect to the thickness of the cream solder coating film. It is possible to prevent the corners of the cream solder shape from rising.

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 corner rising height with respect to the solder coating film thickness,
The optimum plate separation position can be set, and a good cream solder printing shape can be obtained by the above method.

[0027]

BEST MODE FOR CARRYING OUT THE INVENTION 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,
Reference numeral 2 is a printed circuit board, 3 is a squeegee, 4 is cream solder, 5 is a stage that supports the printed circuit board 2 so as to be movable up and down, 6 is a vertical movement mechanism of the stage 5 including, for example, a ball screw and a nut, and 7 is, for example, It is a drive means of the up-and-down moving mechanism, which is composed of a motor for rotating the nut forward and backward to move the ball screw up and down. A distance sensor 8 is arranged at an appropriate distance above the screen mask plate 1, and the mask waveform detecting means 9 detects the mask displacement of the screen mask plate 1 from the displacement amount of the mask of the screen mask plate 1 detected by the distance sensor 8. Of the vibration waveform of the driving means 7 and the driving control means 10 to which the detection result is input.
Is configured to be driven and controlled.

The operation of the cream solder printing apparatus configured as described above will be described. The printed circuit board 2 is lifted on 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 while the cream solder 4 is scraped off by the squeegee 3, the inside of an opening (hereinafter referred to as a mask opening) 11 formed in the mask of the screen mask plate 1 Fill with cream solder 4. For example, when using a squeegee 3 made of a soft elastic deformable body such as urethane rubber,
As shown in FIG. 2, the cream solder 4 is scraped to elastically restore in the mask opening 11, and the cream solder printing thickness, that is, the average thickness t of the printed cream solder is the thickness T of the screen mask plate 1. It becomes thinner than that. In FIG. 2, reference numeral 12 is a copper foil land of the printed circuit board 2.

When the filling of the cream solder 4 is completed, the 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 filling state of the cream solder 4 shown in FIG. 3A, and the state of the mask of the screen mask plate 1 shown in FIG. Further lower to the plate separation state shown. In the process of (b) to (c), the cream solder 4 filled in the mask opening 11 is gradually removed from the mask opening 11 while being in close contact with the printed circuit board 2. When the plate is completely released, 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 as shown in FIG. The printed circuit board 2 stands still on the free plane and further descends toward the transport position. The shape of the cream solder 4 transferred to the printed circuit board 2 is determined by the lowering speed control of the printed circuit board 2 in the step of separating the screen mask plate 1, particularly in the steps (b) to (c) of FIG.

More specifically, in order that the cream solder 4 filled in the mask opening 11 is 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 appropriate force. For example, in the case of the cream solder 4 of a type made of a viscous fluid having thixotropy, a large shear stress is generated when the cream solder 4 is slipped off the wall surface of the mask opening 11 at a high speed, and at that time, the cream solder 4 and the print are printed. If the adhesion between the circuit board 2 and the circuit board 2 is smaller, the cream solder 4 will be left in the mask opening 11. According to experiments, a plate separation speed of 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 at the slow 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 cream solder 4 that straddles both of the two is broken into ductile fractures to cause the corner rise 14 shown in FIG. A part of the cream solder 4 that has undergone ductile fracture appears as corners of the printed cross-sectional shape, and another part appears as adhesion to the back surface of the screen mask plate 1. The cream solder that adheres to the back surface causes printing bleeding of the cream solder during the next printing. In order to solve this, when the screen mask plate 1 and the printed circuit board 2 are separated from each other, the cream solder 4 straddling the screen mask plate 1 and the printed circuit board 2 may be brittlely broken. For this purpose, the screen mask plate 1 and the printed circuit board 2 are not completely separated at the slow plate separation speed, but the plate solder 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 experiments, this plate separation speed may be about 20 mm / s. When the moving speed of the printed circuit board, that is, the plate separating speed is switched from low speed to high speed, it is preferable to switch the speed to 100 times or more in order to more reliably 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, how to obtain an appropriate position for increasing the plate separation speed (this is referred to as "plate separation position" in this 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 represents the descent time of the printed circuit board, and the vertical axis represents the displacement ΔH of the central portion of the mask with respect to the free plane. There is. It should be noted that the time points at which the states of (a) to (e) of FIG. 3 are reached are indicated by (a) to (e) of FIG. 4, respectively. The portion for measuring the vibration is preferable because the central portion of the mask vibrates most, but the invention is not limited to this.

Here, in the process of going from (b) to (c) in FIG.
When the plate separation speed is switched from low speed to high speed at a position that is sufficiently left inside, the amplitude and vibration time become large. When the switching position is gradually delayed, in other words, when the substrate descending time to the switching position is gradually lengthened, 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 amplitude appears as a large swell, and the vibration time also increases.

For example, specifically, as shown in FIG.
Even after passing the optimal plate separation position, for example, 0.1m
When the plate separation 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 the low speed (for example, 0.1 mm / sec) to the high speed (for example, 20 mm / sec) until the optimum plate separation position is reached, the vibration time is short. However, the maximum amplitude width becomes large.

Therefore, in order to reduce the maximum amplitude width and at the same time shorten the vibration time to reduce the corner rise 14 of the cream solder 4, as shown in FIG. 4, it is optimal between (b) and (c). Between the screen mask plate 1 and the printed circuit board 2 at the plate separation position after the 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 of the from low speed to high speed. The plate separation position is from a point (b) where the waveform amplitude intersects the free plane of the mask to a point (c) where the waveform has the maximum amplitude, and for example, a rising portion of the waveform having the maximum amplitude width is preferable. On the other hand, the conventional Japanese Patent Laid-Open No. 5-286113
In the method of the publication, when the deflection of the mask is switched from the lower side to the upper side, it means when the point of (c) is passed,
Since the point (c) where the plate separation is completed is over, the above-mentioned problems occur. When switching the moving speed at the plate separating position in the above embodiment of the present invention, specifically, in FIG. 4, in the range of (a) to (b), an arbitrary moving speed, for example, 0.1 mm / sec or 20 mm / se
c may be used, but 0.1 mm from (b) to the plate separation position
/ Sec is a low moving speed, and 2 after the plate separation position.
It is preferably 0 mm / sec.

Therefore, in the present embodiment, the position at which the plate separation speed is switched from low speed to high speed is changed, and the displacement amount of the mask of the screen mask plate 1 is detected by the distance sensor 8 and the plate is detected by the mask waveform detecting means 9. The vibration waveform of the mask of the screen mask plate 1 after separation is detected, the relationship between the speed switching position and the amplitude and vibration time of the screen mask plate 1 when the plate is separated is obtained, and the position where the amplitude and vibration time are minimized is determined. It is set at a remote location. In this case, instead of changing the plate separating position, the moving speed may be changed to obtain the same effect.

Thus, by switching the plate separation speed from the low speed to the high speed by the drive control means 10 at the plate separation position thus set, the screen mask plate 1 and the printed circuit board 2 are straddled immediately before the plate separation. The cream solder 4 can be brittlely broken, and the screen mask plate 1
It is possible to prevent the cream solder 4 from adhering to the back surface of the same, and to prevent printing bleeding of the cream solder 4 during the next printing, generation of a bridge, and insufficient supply of cream solder printing, and good cream solder printing. The shape is obtained.

Although the mask waveform detecting operation and the plate separation position setting / changing operation are performed by one mask waveform detecting means 9 in the above embodiment, they may be performed by different means.

Further, in the above-described embodiment, as shown in FIG. 1, a judging section 91 for judging the quality of the printed state of the cream solder is further provided, and the printed state of the cream solder is outside the allowable range in the judging section 91. If it is determined that the plate separation position set by the mask waveform detection means 9 may be changed. It is preferable that this allowable range is such that a bridge state in which the cream solder is improperly connected to each other does not occur due to a defective cream solder printing between adjacent cream solder portions. It is preferable to appropriately change the permissible range.

Further, in the above embodiment, the method of detecting the vibration waveform of the screen mask plate 1 to obtain the plate separation position is exemplified, but the present invention is not limited to this. For example,
When the plate separation position is not appropriate, a corner 14 appears in the print cross-sectional shape of the cream solder 4 after the cream solder printing as shown in FIG. 5, so that the position at which the plate separation speed is switched to a high speed as shown in FIG. Various changes are made, and the corner standing height h is measured from the print cross-sectional shape of the cream solder 4 at that time,
Even if the position where the corner standing height h is the lowest is set as the plate separation position, a good cream solder printing 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 shows the corner stand 14 in the above embodiment.
The method of detecting After the cream solder printing, the printed circuit board 2 is taken out from the stage 5 and positioned at the angled measurement position indicated by the solid line, and the laser emitting / receiving device 81 emits a laser toward the printed circuit board 2 and the printed circuit board 2 The reflected laser reflected 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. 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. The laser is irradiated so that the cross-sectional shape of can be taken. The measured data is stored in the cross-sectional shape detection unit 82, and when the height of the corner portion of the cream solder portion stored in the cross-sectional shape detection unit 82 is equal to or greater than the allowable height by the shape determination unit 83. The setting position of the plate separating position is changed, and the drive control unit 10 controls the driving of the driving unit 7 so that the descending speed of the stage 5 is switched from low speed to high speed at the changed plate separating position.

The shape determining operation and the plate separation position setting / changing operation are performed by one shape determining unit 83 in the above embodiment.
However, it may be performed in separate parts. The allowable height is preferably a height that does not cause a bridge state in which the corner portions fall between the adjacent cream solder portions and are accidentally connected to each other,
It is preferable to make an empirical setting and then appropriately change it by checking the printing state.

In the case of setting the plate separating position by measuring the cross-sectional shape of the corners as described above, the plate separating position may be set without detecting the above waveform of FIG.
In order to perform drive control with higher accuracy, the plate separation position by measuring the rectangular cross-sectional shape and the plate separation position by detecting the waveform of FIG. 1 are set respectively, and the intermediate position between them is set as the plate separation position. Good. Further, when there are a large number of corner portions, the plate separation positions may be calculated and the plate separation positions may be set by taking the average thereof.

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, and for example, as shown in FIG. 12, the screen mask plate 1 may be separated from the printed circuit board 2 by the driving unit 71. 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 driven to rotate by a motor 71 as an example of driving means. There is. The stage 5 supporting the printed circuit board 2 is
When the printed circuit board 2 is carried into the stage 5 and when the printed circuit board 2 is carried out from the stage 5, the stage vertical cylinder 72 descends from the printing position.
Therefore, similarly to 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 separated from each other at the plate separating position. It is also possible to switch the ascending speed of the screen mask plate 1 by the motor 71 from a low speed to a high speed when the above condition is reached, so that the same operational effect as described above can be obtained.

[0046]

According to the cream solder printing method of the present invention, as is apparent from the above description, the printed circuit board or the screen mask plate reaches the plate separating 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 low speed to high speed, the cream solder that crosses both the screen mask plate and the printed circuit board can be brittlely broken just before the plate is released, and thereby the screen Prevents the solder paste from sticking to the back side of the mask plate, and prevents the solder paste from bleeding during the next printing, the occurrence of bridging, and the insufficient supply of solder paste printing. You can get the status.

Further, the 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 of the vibration waveform and the vibration time are minimized. By setting the separation position, it is possible to set an appropriate printing mask plate separation condition, and it is possible to obtain a good printed state of the solder cream.

Further, by directly measuring the shape dimensions of the cream solder coating film printed on the printed circuit board and setting the plate separation position so as to minimize the height of the corners with respect to the thickness of the cream solder coating film. It is possible to set an appropriate printing mask separation condition and obtain a good printing state of the solder cream.

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 corner rising height with respect to the solder coating film thickness,
The optimum plate separation position can be set, and a good cream solder printing shape can be obtained by the above method.

[Brief description of 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 same embodiment.

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

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

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

FIG. 6 is a graph showing a relationship between a plate separation position and a corner standing height according to another embodiment of the present invention.

FIG. 7 shows a conventional cream solder printing method, (a)
Is a schematic configuration diagram, and (b) is a correlation diagram of the relationship between the relative displacement amount of the print mask and the relative displacement amount of the cream solder.

FIG. 8 is a schematic configuration diagram of another conventional solder paste 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 view 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.

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]

 1 Screen Mask Plate 2 Printed Circuit Board 3 Squeegee 4 Cream Solder 5 Stage 6 Vertical Moving Mechanism 7 Driving Means 8 Distance Sensor 9 Mask Waveform Detecting Means 10 Drive Control Means 14 Corner Standing 61 Ball Screw 71 Motor 72 Stage Vertical Cylinder 81 Laser Emitting and Receiving Device 82 Cross-sectional shape detection unit 83 Shape determination unit 91 Determination unit

(72) Inventor Hiroaki Onishi 1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. (72) Shinya Matsumura, 1006 Kadoma, Kadoma City, Osaka Matsushita Electric Industrial Co., Ltd.

Claims (14)

[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 cream solder printing. First movement in a direction of separating one of the printed circuit board and the screen mask plate from the other until one of the printed circuit board and the screen mask plate reaches the immediately preceding plate separating position. When the printed circuit board or the screen mask plate reaches the plate separation position at a speed, the first plate is moved.
A cream solder printing method characterized in that the speed is switched to a second moving speed which is faster than the first moving speed. 2. In the switching step, the first moving speed is set to the second moving speed at the plate separating position so that brittle fracture occurs in the cream solder extending between the printed circuit board and the screen mask plate. The cream solder printing method according to claim 1, wherein the moving speed is switched. 3. The cream solder printing method according to claim 1, wherein in the switching step, the second moving speed is 100 times or more faster than the first moving speed. 4. The switching step includes a step of 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 from each other, and thereby, the mask of the screen mask plate. And the step of setting the plate separation position so as to minimize the maximum amplitude of the waveform based on the position of the free plane and the vibration time of the waveform until the mask settles at the position of the free plane. The cream solder printing method according to claim 1, wherein the method is provided. 5. The switching step includes a step of measuring a cross-sectional shape of the cream solder coating film printed on the printed circuit board, and a step of measuring the cross-sectional shape of the cream solder coating film with respect to the thickness of the cream solder coating film. 5. The cream solder printing method according to any one of claims 1 to 4, further comprising the step of setting the plate separation position so as to minimize the corner rising height 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 the first moving speed in a direction at a second moving speed higher than the first moving speed, and immediately before the screen mask plate and the printed circuit board are completely separated after printing the cream solder. Until one of the printed circuit board and the screen mask plate reaches the plate separating position, at a first moving speed in a direction of separating one of the printed circuit board and the screen mask plate from the other. Either the printed circuit board or the screen mask plate is moved to the plate separating position while being moved. Control means for controlling the moving device so as to switch the first speed to the second moving speed when one of them reaches, and a detection device for detecting a printing state of the cream solder on the printed circuit board. A cream solder printing apparatus comprising: a setting unit configured to set the plate separation position based on a detection result from the detection apparatus. 7. The detection device is a distance sensor arranged at a position distant from the position of the free plane of the mask of the screen mask of the screen mask plate by a certain distance, and the setting means is the distance sensor. 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 a detection signal, and the plate separation position is set based on a maximum amplitude of the vibration waveform and a vibration time. . 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 is separated from the printed circuit board, and the setting means, With 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 separation position is set so as to minimize the vibration time of the waveform until the mask settles at the position of the free plane. 9. The detection device comprises a detection sensor for measuring the cross-sectional shape of the cream solder coating film printed on the printed circuit board, and the cream solder from the cross-sectional shape of the cream solder coating film measured by the detection sensor. And a means for detecting a corner rising height of the plate, wherein the setting means sets the plate separation position based on a result detected by the detection device.
The cream solder printing device according to. 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 solder paste 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 the cream solder extending between the printed circuit board and the screen mask plate. The cream solder printing apparatus according to any one of claims 6 to 12, wherein the cream solder printing apparatus is set by a setting unit. 14. The cream solder printing apparatus according to claim 6, wherein in the moving device, the second moving speed is 100 times or more faster than the first moving speed.