JPH05200540A - Method and device for applying cream solder - Google Patents

Abstract

PURPOSE:To stably apply a constant amount of cream solder on a substrate by correcting the height, direction and position of a nozzle for discharging cream solder based on the measured result of the height of the area where the cream solder is to be applied on the substrate. CONSTITUTION:The cream solder is discharged from the nozzle 19 for discharging cream solder and applied on the position of the substrate 20 where the cream solder is to be applied. At this time, the height of such scheduled position is measured with a non-contact type measuring machine 4. Based on this measured result, the height, direction and position of the discharging nozzle 19 are corrected. Thus, in the state of maintaining a constant space between the substrate 20 and the discharging nozzle 19, the cream solder is discharged and applied on the substrate 20. The non-contact type measuring machine is the one in which a laser beam is used. Thus, a uniform soldering without variation is performed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and apparatus for applying cream solder, and particularly to measuring the height of a cream solder application site of a substrate prior to applying cream solder, and based on the measurement result, the cream Correct the height by moving the height of the cream solder discharge nozzle that discharges solder, and apply the cream solder to the board with the gap between the board and the cream solder discharge nozzle always constant, and warp, bend, twist, etc. of the board. Regardless of the above, the present invention relates to a cream solder application method and apparatus that can always apply a fixed amount of cream solder.

[0002]

2. Description of the Related Art As a method of soldering to a substrate, a reflow soldering method is mainly used in which many electronic components are simultaneously soldered by mounting electronic components on a substrate having a soldering portion coated with cream solder and heating them. It is used for soldering electronic components.

Conventionally, as a method of applying the cream solder to the substrate, a so-called metal mask having a hole formed at a position corresponding to the cream solder application portion of the substrate is prepared, and the metal mask is overlaid on the substrate. A printing method of applying cream solder on a mask has been used. On the other hand, due to the recent miniaturization of electronic components, the density of lead terminals has been further increased, the area of the soldering portion has been reduced, and the electronic components having a pitch of the lead terminals of only about 0.5 mm can be soldered. There is a strong desire to do so.

However, according to the conventional printing method, since the cream solder is applied, the holes formed in the metal mask must be made small, and when the cream solder is printed on a large number of substrates, the holes are not formed. It has a drawback that it is clogged and an application failure of cream solder occurs.

Further, it is difficult to find a defective application portion at the time of applying the cream solder before soldering, and it will be found in the substrate inspection step after the completion of soldering, so that the work efficiency is poor and the defective substrate can be repaired. It has a drawback that it requires a lot of man-hours. Further, it is necessary to prepare a metal mask for each substrate having a different pattern and set it on the printing machine, which has a drawback that setup change is difficult.

As a method for solving the above-mentioned drawbacks, a method and a device (cream solder dispenser) for discharging cream solder from a nozzle mounted on a three-dimensional moving device and applying it to a substrate have been conventionally proposed. The required amount of cream solder to be discharged from one location of a miniaturized electronic component is about several mg. However, according to the conventional coating method, the amount of cream solder to be discharged from a nozzle is greatly dependent on the distance between the nozzle and the substrate. However, if the substrate is warped or bent, the coating amount may vary due to a change in the distance between the nozzle and the substrate, and soldering cannot be performed uniformly.

[0007]

SUMMARY OF THE INVENTION The present invention has been made in order to eliminate the above-mentioned drawbacks of the prior art, and its purpose is to use a non-contact type length-measuring device for cream soldering of a substrate. By measuring the position in the height direction of the planned application site, it is possible to correct the position in the height direction of the cream solder discharge nozzle, and by this, the distance between the board and the cream solder discharge nozzle is always a predetermined fixed distance. That is, cream solder is discharged from the cream solder discharge nozzle so that a constant amount of cream solder can always be stably applied to the substrate.

Another object is to allow a stable predetermined amount of cream solder to be applied over the entire surface of a substrate having a warp or a bend due to the above-mentioned structure, and thereby a uniform and uniform coating. It is to improve the reliability of the circuit board by enabling proper soldering.

Still another object is to use a non-contact type length measuring device using a laser beam as the non-contact type length measuring device so that the position in the height direction of the cream solder application scheduled portion of the substrate can be shortened and shortened. It is to enable measurement with extremely high accuracy, and to improve the application efficiency of cream solder by this, and to enhance productivity.

Still another object is to measure the position in the height direction of the cream solder application scheduled site by reflecting the laser beam emitted from the laser displacement meter by a mirror and irradiating it to the cream solder application scheduled site of the substrate. By
Relaxing the restrictions on the installation position of the laser displacement meter to expand the degree of freedom in design, and to irradiate the laser beam from a direction near the cream solder application planned site from the direction perpendicular to the predetermined site to measure. It is to be able to measure accurately.

[0011]

SUMMARY OF THE INVENTION In summary, the method of the present invention (claim 1) is a cream solder coating method for discharging cream solder from a cream solder discharge nozzle to apply the cream solder to a required coating position on a substrate. The height of the cream solder application planned portion of the board is measured by a non-contact type length measuring device, and the board and the cream solder discharge are corrected by correcting the height direction position of the cream solder discharge nozzle based on the measurement result. It is characterized in that the cream solder is discharged from the cream solder discharge nozzle and applied to the substrate in a state where the distance from the nozzle is constant. The apparatus of the present invention (Claim 2) is in the X direction parallel to the plane of the substrate held on the substrate holder, the Y direction orthogonal to the X direction in the plane, and the X direction and the Y direction. A three-dimensional moving device that is movable in the Z direction, a cream solder ejecting device that is mounted on the three-dimensional moving device and moves in the X, Y, and Z directions to eject cream solder from a cream solder ejecting nozzle; A non-contact type length measuring device for measuring the Z-direction position of the cream solder application planned portion of the substrate, and the substrate by correcting the Z-direction position of the cream solder discharge nozzle based on the measurement result of the non-contact type length measuring device. A control device for controlling the cream solder discharge nozzle to discharge the cream solder after setting a predetermined constant distance from the cream solder discharge nozzle. Further, according to the present invention apparatus (claim 4), the X direction parallel to the plane of the substrate held by the substrate holder, the Y direction orthogonal to the X direction in the plane, the X direction and the Y direction.
A three-dimensional moving device that is movable in a Z direction orthogonal to the direction, and a cream solder discharging device that is mounted on the three-dimensional moving device and moves in the X, Y, and Z directions to discharge the cream solder from a cream solder discharging nozzle. An apparatus, a laser displacement meter that reflects a radiated laser beam by a mirror and irradiates a cream solder application planned site on the substrate to measure a Z direction position of the cream solder application planned site, and a measurement result of the laser displacement meter. Based on the above, the Z-direction position of the cream solder discharge nozzle is corrected to set the distance between the substrate and the cream solder discharge nozzle to a predetermined constant distance, and then the cream solder discharge nozzle is controlled to discharge the cream solder. And a control device that operates.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the embodiments shown in the drawings. The present invention (first embodiment) with reference to FIG. 1 to FIG.
The cream solder applying apparatus 1 according to the present invention is a three-dimensional moving apparatus 2
A cream solder ejecting device 3, a non-contact type length measuring device 4,
And a control device 5.

The three-dimensional moving device 2 is for moving the cream solder discharging device 3 to an arbitrary position in the three-dimensional space, and the X-direction moving device 8 is fixed to the base 6 and
The Y-direction moving device 9 is fixed to an X-direction moving table (not shown) of the direction moving device 8 to drive the X-direction moving device 8 to move the Y-direction moving device 9 in the X-direction.

The Y-direction moving table 10 of the Y-direction moving device 9 is also provided.
Has a Z-direction moving device 11 fixed thereto. The DC servomotor 12 provided in the Z-direction moving device 11 is operated to rotate a ball screw mechanism (not shown) to move the Z-direction moving table 13 in the Z-direction. It is designed to be moved to.

The X-direction moving device 8 and the Y-direction moving device 9
Also, like the Z-direction moving device 11, a drive mechanism including a DC servo motor and a ball screw mechanism is built in,
It is configured to move the movable portion in the X or Y direction by operating each DC servo motor.

Since the three-dimensional moving device 2 is provided with the independent DC servo motors as described above, the movable part can move linearly at high speed between two points in the three-dimensional space. For example, it is possible to stop at a predetermined position with a positional accuracy of plus or minus 0.02 mm while moving at a maximum speed of 1500 mm / sec.

A first moving table 15 to which a motor 14 is fixed is fixed to the Z-direction moving table 13, and a second moving table 16 is slidable in a dovetail groove 15a formed in the first moving table 15. They are fitted together and can be moved in the Z direction (arrow A or B direction) by being guided by the groove 15a.

A lead screw 19 which is screwed into a female screw (not shown) formed on the second moving table 16 is connected to the rotary shaft 18 of the motor 14, and the motor 14 is operated to operate the lead screw 19. The second moving table 16 is rotated to move in the arrow A or B direction.

The cream solder ejecting device 3 ejects the cream solder from the cream solder ejecting nozzle 19 to make the substrate 20.
A cylindrical container 21 filled with cream solder is mounted on the second moving table 16 with the cream solder discharge nozzle 19 mounted at the tip thereof facing downward, At the rear end of the container 21, a compressed air adjusting device 23 that adjusts the pressure of compressed air supplied from a compressed air supply source (not shown) via a pipe 22 and supplies the compressed air to the cylindrical container 21 is installed. 5
The compressed air pressure is adjusted according to the command from the air conditioner and sent into the cylindrical container 21, and the pressure inside the cylindrical container 21 is increased so that the compressed solder is acted on by the compressed air and discharged from the cream solder discharge nozzle 19. It has become.

The non-contact type length measuring device 4 is for measuring the height of the cream solder application planned portion 20a of the substrate 20, and a known laser displacement meter 4 as an example of the non-contact type length measuring device is used. It is mounted on the second moving table 16 adjacent to the cylindrical container 21.

The laser beam emitted from the laser displacement meter 4 is aimed at a position directly below the cream solder discharge nozzle 19 of the substrate 20, and the portion to be applied with cream solder of the laser beam emitted in the direction of arrow C is set. The reflected light from 20a is condensed on a position detecting element (not shown) by a lens (not shown), the distance to the cream solder application planned site 20a is measured, and the measurement result is sent to the controller 5 via the electric cord 23. It is designed to be transmitted to.

The spot diameter of the laser beam is 70 to 90 μm, the response time is extremely short at about 0.1 msec, and the distance to the cream solder application planned site 20a can be measured instantly. ..

The control device 5 is a cream solder applying device 1
DC Servo Motor, Motor 14, Compressed Air Conditioner 2
3, a computer 28 including a central processing unit 24, an input / output port 25, an external storage device 26, and the like, for inputting a command signal to the computer 28 for controlling each part of the laser displacement meter 4 and the like. Keyboard 29
And a display device 30 for displaying the processing result.

Next, the structure of the Z direction control device of the cream solder ejecting device 3, which is the main part of the present invention, will be described. The measurement result from the laser displacement meter 4 is input to the input / output port 25 by the electric cord 23. , The DC servo motor and the motor 1 are subjected to predetermined arithmetic processing based on the input signal.
The drive signal to 4 is transmitted through the electric cord 31,
The DC servomotor and the motor 14 are operated to move the cream solder ejecting device 3 in the directions of arrows A and B to control the distance between the substrate 20 and the cream solder ejecting nozzle 19 to be a predetermined distance. Has been done.

The substrate 20 is mounted on the base 6 by the three-dimensional moving device 2
A substrate transfer device (not shown) for transporting the substrate 20 below the substrate and a substrate holding table 32 for horizontally holding and holding the transported substrate 20 are provided, and the substrate 20 having a size of 60 × 90 mm to 385 × 510 mm is provided. It is designed to be transported and fixedly held at a speed of 1.5 to 2.5 m / sec.

Further, a reference stand 33 having a contact 33a is fixed to a predetermined portion of the base 6, and the tip of the cream solder discharge nozzle 19 is brought into contact with the contact 33a so that a reference position in the Z direction can be set. It has become. The cream solder applicator 1 is also provided with a switch 34 for manually operating each part.

Next, a second embodiment of the present invention will be described with reference to FIG. A mirror 35 is fixed to a second moving table 16 which is attached to the three-dimensional moving device 2 and is movable in the directions of arrows A and B, and irradiation is performed from a laser displacement meter 4 which is also fixed to the second moving table 16. The reflected laser beam to the mirror 35
It is configured to irradiate the area 20a where the cream solder is to be applied, and to collect the reflected light on the position detection element with a lens to measure the distance to the area 20a where the cream solder is to be applied.

By doing so, the angle θ formed by the perpendicular line from the cream solder discharge nozzle 19 to the substrate 20 and the laser beam emitted from the laser displacement meter 4 is made small.
The laser beam can be emitted from a direction as close to the direction perpendicular to 0 as possible, and the measurement accuracy is improved. The rest of the configuration is the same as in the first embodiment described above, so the same parts are given the same reference numerals in the drawings, and description thereof is omitted.

The method of the present invention is a method of applying cream solder in which cream solder is discharged from the cream solder discharge nozzle 19 to apply the cream solder to the required application position of the substrate 20, and the substrate 20 is applied by the non-contact length measuring device 4. The height of the cream solder application planned site 20a of the substrate 20 and the cream solder discharge nozzle 1 are corrected by correcting the position of the cream solder discharge nozzle 19 in the height direction based on the measurement result.
9 is a method of discharging the cream solder from the cream solder discharge nozzle 19 and applying the cream solder to the substrate 20 in a state where the space between the cream solder and the solder paste 9 is constant.

The present invention is configured as described above,
The operation will be described below. 1 to 4, as a preparatory work, the controller 5 is provided with the position coordinates of the cream solder application planned site 20a of the board 20 and the board 20 at the time of ejection.
To the cream solder discharge nozzle 19 (set distance),
For example, 1 mm is stored.

This storage operation may be manually input from the keyboard 29, or the data stored in a floppy disk (not shown) may be read from a floppy disk drive (not shown) and stored. .. Then, by manually operating the switch 34 to bring the cream solder discharge nozzle 19 into contact with the contact 33a of the reference table 33, the Z-direction reference position of the cream solder discharge nozzle 19 is stored and the preparation work is completed.

Referring also to FIG. 5, when the board 20 is carried by a carrying device (not shown) and horizontally fixed and held on the board holder 32, the operation of the cream solder coating apparatus 1 is started. The three-dimensional moving device 2 operates according to the data stored in the control device 5 to move the cream solder ejecting device 3 to the first cream solder application planned site 20a.

In step S ₁ , the laser displacement meter 4 irradiates a laser beam to the cream solder application scheduled site 20 a to measure the distance to the cream solder application scheduled site 20 a, and the measurement result is passed through the electric cord 23. Controller 5
Communicate to.

The spot diameter of the laser beam is 70 to 90.
Very small as μm, and response time is about 0.1 msec
Therefore, it is possible to measure an arbitrary position of the cream solder application planned site 20a in an extremely short time.

Then, the process proceeds to step S ₂ and step S ₁
It is determined whether or not the measured distance is equal to the preset distance. If not equal, step S
Proceed to step ₃ to determine if the measured distance is greater than the set distance.

If the measured distance is larger than the set distance, it is determined that the position of the cream solder ejecting device 3 is too high, and the process proceeds to step S ₄ , where the drive signal from the controller 5 is the DC servo motor 12 and the drive signal. It is transmitted to the motor 14 through the electric cord 31, and the DC servomotor 12 and the motor 14 are operated to move the cream solder ejecting device 3 in the direction of arrow B.

Then, the distance between the substrate 20 and the cream solder discharge nozzle 19 is controlled to be a set distance, for example, 1 mm. If and when the measured distance is not greater than the distance which is set, it is determined that the position of the solder paste jetting device 3 is too low the process proceeds to step S _5, the controller 5
Drive signal is transmitted from the DC servo motor 12 and the motor 14 through the electric cord 31 to operate the DC servo motor 12 and the motor 14 to move the cream solder ejecting device 3 in the direction of the arrow A, and the board 20 and the cream. A distance to the solder discharge nozzle 19 is set, for example, 1 mm
Control so that.

In step S ₆ , the distance to the cream solder application planned site 20a is measured again, and in step S ₇
It is again determined whether or not the distance measured at is equal to the preset distance. When they are not equal, the route R ₁ is returned to the point L, and it is determined again in step S ₃ whether or not the measured distance is larger than the set distance, and as a result, the cream is obtained in step S ₄ or step S ₅ . The position of the solder ejecting device 3 is corrected.

This operation is repeatedly executed until the measured distance becomes equal to the preset distance, and when the measured distance becomes equal to the preset distance, step S ₃ , step S ₄ or step S ₅ , Step S ₆ and Step S ₇ are exited and the process proceeds to Step S _{8, in} which the pressure of the compressed air from the compressed air supply source (not shown) is adjusted by the compressed air adjusting device 23 and sent into the cylindrical container 21, The pressure in the container 21 is increased to discharge a certain amount of cream solder from the cream solder discharge nozzle 19 to apply it to the substrate 20.

If it is determined in step S ₂ that the measured distance is equal to the preset distance,
Route R ₂ street step S _3, Step S ₄ or step S _5, the flow proceeds to the point M by omitting the routine of steps S ₆ and S S _7, in step S _8, constant cream solder from the solder paste ejection nozzle 19 The amount is discharged and applied to the substrate 20.

And the first cream solder application planned site 2
Exit cream solder applied to 0a by operating the three-dimensional movement apparatus 2 proceeds to step S ₉ moves the cream solder ejection device 3 to the next solder paste coated proposed site 20a,
Returning to the point N by the route R ₃ , the same operation is repeated for all the cream solder application planned sites 20a, and the application of the cream solder to the substrate 20 is completed.

The discharge speed of the cream solder is about 0.5 second each time, and the distance between the substrate 20 and the cream solder discharge nozzle 19 is plus or minus 0 with respect to the set value for each discharge of the cream solder as described above. Since it is corrected and discharged with an accuracy of 0.02 mm, the variation in the amount of cream solder discharged is extremely small, within ± 15%.
Can be applied uniformly. The number of storable cream solder application planned sites 20a is at least 300.
Since the number of points can be set to 0, a practically sufficient number of points can be stored.

In the above embodiment, the non-contact type length measuring device 4 and the drive motor of the three-dimensional movement device 2 are described as the laser displacement meter and the DC servo motor, but the non-contact type length measuring device 4 and the tertiary The drive motor of the original moving device 2 is not limited to the laser displacement meter and the DC servo motor,
It may be an optical length measuring device and a pulse motor.

[0044]

As described above, according to the present invention, the position of the cream solder discharge nozzle in the height direction is corrected by measuring the position in the height direction of the portion where the cream solder is to be applied on the substrate using the non-contact type length measuring device. As a result, the space between the board and the cream solder discharge nozzle is always set to a predetermined fixed distance, and cream solder is discharged from the cream solder discharge nozzle so that a fixed amount of cream solder is constantly applied to the board. There is an effect that can be.

Further, the above-mentioned structure has an effect that a stable predetermined amount of cream solder can be applied to the entire surface of the substrate having warpage or bending, and as a result, uniform soldering without variation can be performed. Therefore, there is an effect that the reliability of the substrate can be improved.

Further, since the non-contact type length measuring device using the laser beam is used as the non-contact type length measuring device, the position in the height direction of the cream solder application planned portion of the substrate can be shortened in a short time. There is an effect that the measurement can be performed with extremely high accuracy, and as a result, the application efficiency of the cream solder can be improved and the productivity can be improved.

Further, since the laser beam emitted from the laser displacement meter is reflected by the mirror to irradiate the cream solder application planned site of the substrate, the laser beam is measured by measuring the position in the height direction of the cream solder application planned site. It is possible to relax the restrictions on the installation position of the displacement meter, and to have the effect of expanding the degree of freedom in design, and since it is possible to measure by irradiating a laser beam from a direction close to vertical to the cream solder application planned site, There is an effect that a predetermined measurement site can be accurately measured.

[Brief description of drawings]

FIG. 1 is an overall perspective view of a cream solder applicator.

FIG. 2 is a perspective view of a main part of a cream solder applicator.

FIG. 3 is a front view of the essential parts showing the configuration of the first embodiment of the cream solder applicator.

FIG. 4 is a main part front view showing the configuration of a second embodiment of the cream solder applying apparatus.

FIG. 5 is a flowchart showing a routine of an operation of the cream solder applying apparatus.

[Explanation of symbols]

 1 Cream Solder Applying Device 2 Three-Dimensional Moving Device 3 Cream Solder Discharging Device 4 Laser Displacement Meter 5 Control Device 19 Non-contact Type Length Measuring Device 19 Cream Solder Discharging Nozzle 20 Substrate 20a Cream Solder Application Site 32 Substrate Holding Table 35 mirror

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Office reference number FI technical display location // H05K 3/34 H 9154-4E

Claims (4)

[Claims] 1. A cream solder coating method for discharging cream solder from a cream solder discharge nozzle to apply the cream solder to a required coating position on a substrate, wherein a non-contact type length measuring device is used to apply the cream solder on the substrate. Is measured, and the position in the height direction of the cream solder discharge nozzle is corrected based on the measurement result, so that the cream solder discharge nozzle is discharged in a state where the distance between the substrate and the cream solder discharge nozzle is fixed. A method for applying cream solder, characterized in that the cream solder is discharged from a nozzle and applied to the substrate. 2. It is movable in an X direction parallel to a plane of a substrate held on a substrate holder, a Y direction orthogonal to the X direction in the plane, and a Z direction orthogonal to the X direction and the Y direction. 3D moving device, a cream solder ejecting device which is mounted on the 3D moving device and moves in X, Y and Z directions to eject cream solder from a cream solder ejecting nozzle, and a cream solder applying plan of the substrate A non-contact type length measuring device for measuring the Z-direction position of a part, and the Z-direction position of the cream solder discharge nozzle is corrected based on the measurement result of the non-contact type length measuring device to determine the board and the cream solder discharge nozzle. And a controller that controls the cream solder discharge nozzle to discharge the cream solder after setting the predetermined distance to a predetermined constant distance. 3. The cream solder applicator according to claim 2, wherein the non-contact length measuring device is a non-contact length measuring device using a laser beam. 4. A substrate is held on a substrate holder and is movable in an X direction parallel to a plane, a Y direction orthogonal to the X direction in the plane, and a Z direction orthogonal to the X direction and the Y direction. 3D moving device, a cream solder ejecting device mounted on the 3D moving device to move in X, Y and Z directions to eject cream solder from a cream solder ejecting nozzle, and a mirror for emitting a laser beam. And a laser displacement meter for irradiating the portion to be applied with cream solder on the substrate to measure the Z-direction position of the portion to be applied with cream solder, and Z of the cream solder ejection nozzle based on the measurement result of the laser displacement meter. The directional position is corrected so that the distance between the substrate and the cream solder ejection nozzle is set to a predetermined constant distance, and then the cream solder ejection nozzle is controlled to eject the cream solder. A cream solder applicator comprising a control device.