JPH05200542A - How to apply cream solder - Google Patents

Abstract

PURPOSE:To prevent the defect of a substrate and to improve productivity by comparing, after the cream solder is applied, the; condition of a cream solder applied on plural dummy places for application. CONSTITUTION:Adjacently to many prescribed places 20a on a substrate 20 to which cream solder 41 is to be applied, a plural number of dummy places 2Ob, 20c, 20d to apply the cream solder are provided. After the cream solder 41 is applied at least to the place 20a where the application is originally required, the cream solder is applied to the dummy places 20b, 20c, 20d. Then, while the condition of the cream solder 41 applied to the place 20a is checked by comparing the condition of the application to the plural places 20b, 20c, 20d, the cream solder 41 is applied to the rest of the substrate 20. Thus, whether or not the normal application was performed is easily checked.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for applying cream solder, and more particularly to applying cream solder to a dummy application site a plurality of times during the process of applying cream solder to a substrate and applying it to the dummy application site. The present invention also relates to a method for applying cream solder, which makes it possible to check the application state on a substrate extremely easily by comparing the application states 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, the holes formed in the metal mask must be made small in order to apply the cream solder, 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. The purpose of the present invention is to apply the cream solder immediately before, during or after the application of cream solder. It is possible to easily check whether or not normal application has been performed in all the application steps by applying cream solder to multiple dummy application sites on the board at multiple points immediately after that and comparing the application states. To be able to
When coating defects occur, they are discovered in an early process to prevent substrate defects and to dramatically improve production efficiency.

[0008]

In summary, the method of the present invention comprises:
A plurality of dummy solder application sites are provided adjacent to a predetermined location on the substrate to which cream solder is applied, and at least immediately before applying the cream solder to the cream solder application sites After applying the cream solder to the solder application site, applying the cream solder to the dummy application site, and comparing the application states of the cream solder applied to the plurality of dummy application sites to apply the cream solder application It is characterized in that the cream solder is applied to the substrate while checking the application state of the cream solder to the site.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the embodiments shown in the drawings. First, referring to FIGS. 1 and 2, the basic configuration of the cream solder coating device 1 will be described. The cream solder coating device 1 includes a three-dimensional moving device 2, a cream solder discharging device 3, and 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 ejecting 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 X-direction moving device 8 is fixed.
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 independent DC servo motors are provided in the three-dimensional moving device 2 as described above, the movable portion 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 attached to the second moving table 16 with the cream solder discharge nozzle 19 attached to 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, the pressure inside the cylindrical container 21 is increased, and the compressed air pressure is applied to the cream solder to be 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 gauge 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 of the laser beam emitted in the direction of arrow C is to be applied with cream solder. 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 will be described. The measurement result from the laser displacement meter 4 is input / output port 25 by the electric cord 23.
To the DC servo motor and the motor 14, and the drive signal to the DC servo motor and the motor 14 is transmitted through the electric cord 31 to operate the DC servo motor and the motor 14, The solder ejecting device 3 is moved 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.

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.

Referring to FIG. 3, the board 20 is provided with a large number of cream solder application sites 20a for soldering lead wires of electronic components (not shown) and is separated from the cream solder application site 20a. A plurality of dummy application parts 20b, 2 are provided on a predetermined part (usually the peripheral part of the substrate 20).
0c and 20d are provided adjacent to each other.

In the method of the present invention, the substrate 2 on which the cream solder 41 is applied to a large number of cream solder application sites 20a.
A plurality of dummy application parts 20b, 20c, 20d are provided adjacent to a predetermined position of 0, and at least immediately before applying the cream solder 41 to the cream solder applying part 20a and at the cream solder applying part 20a.
After applying the, the dummy application parts 20b, 20c, 20d
The cream solder 41 is applied to a plurality of dummy application sites, and the application states of the cream solder 41 applied to the plurality of dummy application sites are compared to check the application state of the cream solder 41 to the cream solder application site 20a requiring cream solder 41.
Is a method for applying cream solder to the substrate 20.

The present invention is configured as described above,
The operation will be described below. 1 to 3, the position coordinates of the cream solder application planned site 20a of the substrate 20 and the substrate 2 at the time of discharge are controlled by the control device 5 as preparatory work.
The distance (set distance) between 0 and the cream solder ejection nozzle 19, for example, 1 mm is stored.

This storage operation may be manually input from the keyboard 29, or the data stored in the floppy disk (not shown) may be read from a floppy disk drive (not shown) and stored. ..

The cream solder discharge nozzle 19 is brought into contact with the contact 33a of the reference table 33 by manually operating the switch 34 so that the Z of the cream solder discharge nozzle 19 is changed.
The reference position of the direction is stored and the preparation work is completed.

After the board 20 is carried by a carrying device (not shown) and horizontally fixed and held on the board holding table 32, when the operation of the cream solder applying apparatus 1 is started, the controller 5
First, the three-dimensional moving device 2 is operated to move the cream solder ejecting device 3 to the first dummy application site 20b according to the data stored in the first position.
The distance to the dummy application site 20b is measured, and the DC servomotor 12 and the motor 14 are controlled as described later to control the distance between the substrate 20 and the cream solder discharge nozzle 19 to a set distance, for example, 1 mm. The solder ejecting device 3 is moved.

Then, the compressed air whose pressure is adjusted by the pressure adjusting device 23 is sent into the cylindrical container 21,
The cream solder 41 is increased by increasing the pressure in the cylindrical container 21.
Is ejected from the cream solder ejection nozzle 19 and applied to the first dummy application site 20b.

Next, the three-dimensional moving device 2 is operated again to move the nozzle 19 to the first cream solder application scheduled site 20a, and then the laser beam is irradiated from the laser displacement meter 4 to the cream solder application scheduled site 20a. The distance to the cream solder application planned site 20a is measured, and the measurement result is transmitted to the control device 5 via the electric cord 23. The spot diameter of the laser beam is as small as 70 to 90 μm,
Further, since the response time is approximately 0.1 msec, it is possible to measure an arbitrary position of the cream solder application planned site 20a in an extremely short time.

Then, it is determined whether the measured distance is equal to the preset distance. If they are not equal, it is determined whether the measured distance is greater than the set distance.

When 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 drive signal from the control device 5 sends the electric cord 31 to the DC servo motor 12 and the motor 14. Is transmitted via the DC servo motor 12 and the DC servo motor 12 to operate the DC servo motor 12 and the motor 14 to move the cream solder ejecting device 3 downward.
And the cream solder discharge nozzle 19 are controlled to be a set distance, for example, 1 mm.

If the measured distance is not larger than the set distance, it is determined that the position of the cream solder ejecting device 3 is too low, and the drive signal from the control device 5 is sent to the DC servo motor 12 and the motor 14 by an electric cord. Then, the DC servomotor 12 and the motor 14 are driven to move the cream solder ejecting device 3 upward, and the distance between the substrate 20 and the cream solder ejecting nozzle 19 is set to a set distance, for example, 1 mm. Control to be.

As described above, after the distance from the substrate 20 to the cream solder discharge nozzle 19 is corrected to the set distance, the pressure of the compressed air supplied from the compressed air supply source (not shown) is adjusted by the pressure adjusting device 23. It is adjusted and fed into the cylindrical container 21, the pressure inside the cylindrical container 21 is increased, and a certain amount of the cream solder 41 is discharged from the cream solder discharge nozzle 19 to be applied to the substrate 20.

The state in which the pressure of compressed air is applied to the cream solder 41 in the cylindrical container 21 to discharge the cream solder 41 will be described in detail. When the residual amount of the cream solder 41 in the cylindrical container 21 is large, The energy required for discharging the cream solder 41 is different from when the remaining amount of the cream solder 41 is small, and it is necessary to change the pressure of the compressed air to act. Generally, the appropriate supply air pressure consumes a large amount of energy for flowing a large amount of cream solder 41 having high viscosity when the remaining amount of cream solder 41 is large, and therefore a large amount of energy must be supplied. When a relatively high air pressure is required and the remaining amount is small, a predetermined amount of cream solder 41 can be discharged even with a low air pressure.

Since the air is a compressive fluid, the proper supply air pressure varies depending not only on the remaining amount of the cream solder 41 but also on the volume of the cylindrical container 21, and the remaining amount of the cream solder 41 and a fixed amount of the cream solder 41. It is convenient to empirically obtain the relationship with the appropriate supply air pressure required for discharging and create data in advance and store the data in the external storage device of the computer 28.

An ultrasonic wave length measuring device (not shown) emits an ultrasonic wave toward the surface of the cream solder 41, receives a reflected wave from the surface of the cream solder 41 and receives it from the emission of the ultrasonic wave. Until the surface of the cream solder 41 is measured, the measurement result is input to the computer 28, processed according to a predetermined calculation process, and the remaining amount of the cream solder 41 in the cylindrical container 21 is measured. Is calculated and the appropriate supply air pressure according to the remaining amount of the cream solder 41 is obtained from the above-described data of the appropriate supply air pressure.

Then, the pressure adjusting device 23 is operated to send the compressed air having the proper supply air pressure into the cylindrical container 21, and the cream solder discharge nozzle 19 is used to supply the cream solder 4
A fixed amount of 1 is discharged and applied onto the substrate 20.

As mentioned above, a certain amount of cream solder 41
Is discharged to finish the cream solder application to the first cream solder application scheduled site 20a, the three-dimensional moving device 2 is operated to move the cream solder dispense apparatus 3 to the next cream solder application scheduled site 20a, and so on. Repeat the operation of.

When the cream solder application to about half of the cream solder application planned site 20a is completed, the cream solder ejecting device 3 is moved to the second dummy application site 20c according to the procedure pre-programmed in the controller 5. The cream solder is applied in the same manner as described above.

Then, the operation for applying the cream solder to the remaining portion 20a for applying the cream solder is continued again. In this way, after the cream solder application to all the planned cream solder application sites 20a is completed, the cream solder ejecting device 3 is moved to the third dummy application site 20d, and the cream solder 41 is applied thereto. That is, the dummy application site 20b,
20c and 20d, just before the cream solder application work,
This means that the cream solder 41 has been applied during and after the application work.

Dummy coating parts 20b, 20c and 20d
Are provided adjacent to each other, the dummy application site 2
Cream solder 41 applied to 0b, 20c and 20d
The amount, coating state, etc. can be easily compared by visual inspection, and the coating state in all steps of cream solder coating can be easily determined.

That is, a plurality of dummy application parts 20b, 20
If the amount of cream solder 41 applied to c and 20d, the application state, etc. are within certain ranges, it is determined that good application has been performed, and if the application state is abnormal even at one place, either of the application steps is performed. It can be seen that there was a coating error. Also,
The comparative inspection of the amount of cream solder 41, the application state, and the like can also be performed by an image processing apparatus to inspect the application state of cream solder.

The discharge speed of the cream solder 41 is
One time is about 0.5 seconds, and as described above, the cream solder 41
The amount of the cream solder 41 remaining is detected for each discharge, and the proper supply air pressure is applied to the surface of the cream solder 41, and the distance between the substrate 20 and the cream solder discharge nozzle 19 is plus or minus 0.02 mm with respect to the set value. Since the amount of the cream solder 41 is ejected after being corrected with the accuracy of, the variation in the amount of ejection of the cream solder 41 is extremely small, within ± 15%, and the cream solder 41 can be uniformly applied to the substrate 20. Further, the number of storable cream solder application sites 20a is at least 30.
Since it can be set to 00 points, a practically sufficient number of points can be stored.

[0046]

As described above, according to the present invention, cream solder is applied to a plurality of dummy application sites provided on a predetermined portion of the substrate several times, such as immediately before application of cream solder, during application and immediately after application. However, since the coating states are compared, there is an effect that it is possible to easily check whether or not normal coating has been performed in all the coating steps, and when a coating failure occurs as a result, it can be found in an early step. Therefore, it is possible to prevent the defects of the substrate and to dramatically improve the production efficiency.

[Brief description of drawings]

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

FIG. 2 is a main part perspective view showing the configuration of a cream solder coating device.

FIG. 3 is a perspective view showing a state in which cream solder is applied to a dummy application site by a cream solder ejecting device.

[Explanation of symbols]

 20 board 20a cream solder application site 20b dummy application site 20c dummy application site 20d dummy application site 41 cream solder

Claims (1)

[Claims] A plurality of dummy solder application sites are provided adjacent to a predetermined site of a substrate on which cream solder is applied, and a plurality of dummy solder application sites are provided at least immediately before applying the cream solder to the cream solder application sites. And, after applying the cream solder to the cream solder application site, applying the cream solder to the dummy application site,
Characterized in that the cream solder is applied to the substrate while checking the application state of the cream solder applied to the cream solder application site by comparing the application states of the cream solder applied to the plurality of dummy application sites. How to apply cream solder.