JPH08150697A - Solder printer - Google Patents

Abstract

PURPOSE: To embody a solder printer in which the printing amount of a solder material can be quantitatively determined without necessity of regulation by skilled technique. CONSTITUTION: A solder printer 10 moves squeegees 22A and 22B along a screen 19 to print pastelike solder material 12 on a printed circuit board 15, and controls the quantity protruding from the ends of the squeegee 22A or 22B into an opening hole 19A by elasticity by regulating the pressure in the case of bringing the squeegee 22A or 22B. Thus, the printed quantity of the material 23 printed on the board 15 can be quantitatively determined and hence the printer 10 can quantitatively determined the printed quantity of the material 23 without necessity of regulating by the skilled technique.

Description

Detailed Description of the Invention

[0001]

[Table of Contents] The present invention will be described in the following order. Field of Industrial Application Conventional Technology Problem to be Solved by the Invention (FIG. 11) Means for Solving the Problem (FIG. 3) Action (FIG. 5) Example (1) Chip Mounting Process (FIG. 1) (2) Overall structure of cream solder printing machine (FIGS. 2 and 3) (3) Principle of quantifying the amount of cream solder printing (FIGS. 4 to 6) (4) Structure of pressure control system (FIGS. 7 and 8) (5) ) Operation and effect (FIGS. 4 and 9) (6) Other embodiment (FIG. 10) Effect of the invention

[0002]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a solder printing apparatus, and is particularly suitable for application to a cream solder printing machine for printing cream solder on a printed wiring board through a screen.

[0003]

2. Description of the Related Art Conventionally, in this type of cream solder printer, a printed wiring board to be processed (hereinafter referred to as a PC
B (Print-Circuit-Board) substrate) is carried onto the printing table by a carry-in conveyor, and then the PCB is brought into contact with the lower surface of the screen by raising the printing table, and then the cream. By supplying the solder onto the screen and moving the squeegee along the upper surface of the screen, the cream solder is printed on the PCB substrate.

In this case, in the cream solder printer, the cream solder is supplied onto the PCB substrate by pushing the cream solder into the opening formed in the screen with a squeegee, and as a result, the cream solder is pressed as described above. The PC
Printed on the B substrate. When the printing is completed, the cream solder printer descends the printing table to separate the PCB substrate from the screen, and then carries out the PCB substrate by the carry-out conveyor.

[0005]

By the way, the thickness of the cream solder printed on the PCB substrate generally depends on the hardness of the squeegee, the pressure of the squeegee, the amount of pushing in of the squeegee, etc. even when a screen having the same thickness is used. Change.
Therefore, in the conventional cream solder printer, the thickness of the solder is set to a desired value by adjusting the pushing amount of the squeegee to an appropriate value according to the hardness of the squeegee and the squeegee pressure. The pushing amount of the squeegee is generally determined by the stroke end position of the cylinder that moves the squeegee up and down, and is manually adjusted by the adjuster. The adjustment of the pushing amount is very difficult and requires a high level of skill. For this reason, the adjustment time varies depending on the skill level of the adjuster (about 20
(~ 40 minutes), there is a problem that the adjustment itself will vary.

For example, as shown in FIG. 11, a screen 1
If the thickness of the squeegee is 200 [μm] and the pushing amount u of the squeegee 2 is set to -0.1 to -0.2 [mm], the PCB board 3
The thickness h of the cream solder 4 to be printed on is a desired value 1
It can be 70 to 190 [μm]. However, due to the variation in adjustment, the pushing amount u is 0 to +0.1 [mm]
When set to, the thickness h of cream solder 4 is 200
To 220 [μm], which may cause defects such as solder bridging. When the pushing amount u is set to -0.3 to -0.5 [mm] due to the variation of the adjustment, the thickness h of the cream solder 4 becomes 140 to 160 [μm] (the squeegee pressure and the squeegee parallel are equal to each other). 50 [μm] depending on the relationship
The following may also occur), and a defect such as tempura (so-called solder floating state) or insufficient solder may occur. As described above, in the conventional cream solder printing machine, the thickness of the solder is adjusted by the pushing amount of the squeegee 2 which is difficult to adjust, so that the adjustment itself causes variations and the thickness of the solder also varies. As a result, there is a problem that various solder defects occur.

Incidentally, the type of squeegee 2 to be used (corner,
Since the recommended squeegee pressure and pushing amount are completely different depending on the sword and flat, it was essential for the coordinator to understand the characteristics of each. Such a point is also a factor that requires the adjuster to have a high level of skill.

By the way, in the conventional cream solder printing machine,
During printing, the squeegee 2 is moved in a predetermined direction while being in contact with the screen 1, so that the tip of the squeegee 2 is worn depending on the frequency of use. Since the abrasion of the squeegee 2 affects the thickness of the solder and causes the print quality to be deteriorated, the squeegee 2 usually needs to be replaced regularly. At this time, the replacement squeegee 2 does not have perfect compatibility in almost all cases, and in the case of replacement of the squeegee, the pushing amount must be adjusted as described above. As described above, the adjustment of the pushing amount requires a skilled technique, so that the adjustment tends to vary, and the solder thickness may change every time the squeegee is replaced.

In the chip component mounting process, a plurality of cream solder printers are usually used to form a plurality of lines, and in this case also, there is a variation in the adjustment among the cream solder printers as described above. May occur and the thickness of the solder may change. As described above, in the conventional cream solder printing machine, since the solder thickness is adjusted by adjusting the pushing amount of the squeegee 2 which requires skill, there is a problem that the adjustment itself cannot be unified.

The present invention has been made in consideration of the above points, and it is an object of the present invention to propose a solder printing apparatus capable of quantifying the printing amount of a solder material without requiring adjustment by a skilled technique.

[0011]

In order to solve the above problems, in the present invention, the squeegee 22A or 22B in which the printed wiring board 15 is brought into contact with one surface of the screen 19 and the other surface of the screen 19 is brought into contact with the screen. By moving the paste-like solder material 23 supplied to the other surface of the screen 19 by moving it along the screen 19, the printed wiring board 15 is opened through the opening holes 19A formed in the screen 19.
In the solder printing apparatus 10 that prints on the surface of the squeegee 22A or 22B, the tip of the squeegee 22A or 22B is elastically deformed to open the opening hole 19A.
The amount of protrusion is controlled by adjusting the pressure when the squeegee 22A or 22B is brought into contact with the other surface of the screen 19.

[0012]

When printing, the amount by which the tip of the squeegee 22A or 22B projects into the opening hole 19A due to elasticity is determined by the squeegee 2
By controlling by adjusting the pressure when 2A or 22B is brought into contact with the other surface of the screen 19, the squeegee 22A or 22 in the opening hole 19A is controlled.
The amount w of the solder material 23 scooped by B can be controlled, and thus, the printing amount of the solder material 23 printed on the printed wiring board 15 can be quantified.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described in detail below with reference to the drawings.

(1) Chip mounting process FIG. 1 shows the whole process of mounting a chip component on a PCB board. First, the PCB substrate is conveyed to the cream solder printing machine 10, where cream solder is printed on each land. Next, the PCB board is conveyed to the high-speed mounter 11, where parts such as resistors and capacitors are mounted at predetermined positions. In this case, the high-speed mounter 11 is mounted so that the joint terminals of each component are placed on the land.

Next, the PCB substrate is conveyed to the odd-shaped mounter 12, where a specially shaped component such as a connector is mounted. Also in this case, the odd-shaped mounter 12 is mounted so that the joint terminals of the respective parts are placed on the lands. The PCB board on which each component is mounted is the reflow furnace 1
Then, the bonding terminals of each component are soldered to each land by melting the cream solder there. The PCB board on which component mounting has been completed is then conveyed to the inspection machine 14, where the quality of the mounting state (for example, missing parts, misalignment, solder bridging, etc.) is inspected for each component. A chip component is mounted on the PCB substrate through such a series of steps.

(2) Overall Structure of Cream Solder Printing Machine FIG. 2 shows a cream solder printing machine 10 to which the present invention is applied.
The PCB substrate 15 to be printed is carried onto the printing table 16 by a carry-in conveyor (not shown), and is held and fixed on the printing table 16 by a predetermined holding member. In this state, by driving the table cylinder 18 provided on the base portion 17 to raise the printing table 16, the PCB substrate 15 is arranged so as to abut on the lower surface of the screen 19 made of a metal material. . Next, by driving the cylinder 21A or 21B of the squeegee unit 20, the squeegee 22A or 2B is driven.
2B is lowered and the squeegee 22A or 22B is brought into contact with the upper surface of the screen 19. Incidentally, a device having two squeegees is generally called a double squeegee.

After the above setting, the squeegee unit 20 is moved in the direction indicated by the arrow a or in the opposite direction to print the cream solder supplied on the screen 19 on the PCB substrate 15. In this case, as shown in FIG. 3, the opening 1 in which the cream solder 23 is formed in the screen 19 by the squeegee 22A or 22B.
By embedding in 9A, the cream solder 23 is supplied and printed on the PCB substrate 15.

In the case of this embodiment, squeegees 22A and 2A
As 2B, a square squeegee made of hard urethane and having a substantially rectangular cross section is used. Further, the squeegees 22A and 22B are squeegee holders 24A and 2A, respectively.
It is held by 4B and fixed to the squeegee unit 20. Further, in the solder paste printing machine 10, when printing an odd number of PCB boards 15, for example, the squeegee unit 20 is moved in the direction indicated by the arrow a, and the squeegee 22 is moved.
When the cream solder 23 is printed with A and the even-numbered PCB boards 15 are printed, the squeegee unit 20 is moved in the direction opposite to the direction indicated by the arrow a, and the cream solder 23 is printed with the squeegee 22B. That is, the cream solder printing machine 10
Then, the squeegees 22A and 22B are alternately used for printing.

(3) Principle of Quantifying the Print Amount of Cream Solder Here, the squeegee pressure (that is, the squeegee 22A or 22) is used.
When the squeegee hardness is 90 A (which is slightly hard and has excellent wear resistance) between the pressure when B touches the screen 19) and the degree of deformation of the tip of the squeegee, as shown in FIG. There is a correlation as shown. As is clear from FIG. 4, when the squeegee pressure is 1.0 [kgf / cm ² ], the average value of the deformation degree is about 0.01 [mm]. When the degree of deformation is about 0.01 [mm], the amount by which the tip of the squeegee projects into the screen opening due to its elasticity (hereinafter referred to as the squeegee protrusion amount).
Is approximately 0.01 [mm], which is almost equal to the degree of deformation even if the plus α amount due to the squeegee movement during printing is taken into consideration.

In this case, as shown in FIG. 5, the squeegee 22A (or 22) is provided at the opening 19A of the screen 19.
The amount w of the solder paste 23 scooped off by B) (hereinafter referred to as the amount of scooping) is about 0.
It becomes 01 [mm]. Accordingly, the thickness h of the cream solder 23 to be printed is calculated by the following formula when the thickness of the screen 19 is 200 [μm].

[Equation 1] It is expected to be 190 [μm] as shown in. Thus, from the correlation between the squeegee pressure and the degree of squeegee deformation, PC
The thickness h of the cream solder 23 printed on the B board 15 can be predicted (see FIG. 4).

Incidentally, when the squeegee hardness is 80B (which is slightly soft and has excellent chemical resistance), there is generally a correlation between the squeegee pressure and the squeegee deformation degree as shown in FIG. As is clear from FIG. 6, when the squeegee pressure is 1.0 [kgf / cm ² ], the average value of the degree of deformation is about 0.03 [mm]. Therefore, in this case, the amount w of the cream solder is about 0.03 [mm], and assuming that the thickness of the screen is 200 [μm], the thickness h of the cream solder is

[Equation 2] It is expected to be 170 [μm] as shown in.

In this way, there is a correlation between the squeegee pressure and the degree of squeegee deformation, and from this correlation, the amount of squeegee 22A (or 22B) protruding into the opening 19A of the screen 19 during printing (ie, squeegee protrusion). amount)
Can be predicted, so that the actual PCB board 1
The thickness of the cream solder 23 printed on No. 5 can be predicted. Therefore, by utilizing this principle, the squeegee protrusion amount can be controlled by adjusting and controlling the squeegee pressure during printing, and thus the thickness h of the cream solder 23 (that is, the printing amount of the cream solder 23) can be quantified. .

(4) Configuration of Pressure Control System Here, the cream solder printing machine 10 is provided with a pressure control system 25 having a configuration as shown in FIG. 7 based on the above-mentioned principle. Therefore, the squeegee pressure is controlled. In this case, the pressure control system 25
The air pressure of about 6 [kgf / cm ² ] is reduced by the reguulator 26 to about 2 [kgf / cm ² ] (error ± 0.2 [kgf / cm ² ]). At this time, the pressure value of the air output from the reguulator 26 is displayed on the analog pressure gauge 27. Next, the pressure control system 25 uses about 2 [kgf / cm ² ] of air by the precision regulator 28 to about 1 [kgf / cm ² ] (error ± 0.05).
Reduce the pressure to [kgf / cm ² ]). At this time, the pressure value of the air output from the precision regulator 28 is displayed on the digital pressure gauge 29 and is monitored by the operator. Thus, the pressure control system 25 supplies about 1 [kgf / cm ² ] (error ± 0.05 [kgf / cm ² ]) of air output from the precision regulator 28 to the cylinder 21A or 2 of the squeegee unit 20.
The squeegee pressure is kept constant during printing by supplying 1B.

Incidentally, in the cream solder printing machine 10, as shown in FIG. 8, the pressing amount of the squeegee 22A or 22B with respect to the screen is free within the range of 0 to -2.0 [mm], for example. That is, in the cream solder printing machine 10, in order to make the squeegee pressure constant during printing as described above, the pushing amount is not fixed.

(5) Operation and Effect With the above configuration, at the time of printing, the cream solder printing machine 10
Moves the squeegee 22A or 22B along the upper surface of the screen 19 to remove the cream solder 23 from the PCB.
Print on the substrate 15. At that time, the cream solder printing machine 10
Uses a pressure control system 25 to make the squeegee pressure during printing constant at a predetermined value.

In this case, there is a correlation between the squeegee pressure and the degree of squeegee deformation, and if the squeegee pressure is constant at a predetermined value, the tip end of the squeegee 22A or 22B will open due to its elasticity. The amount of protrusion to the portion 19A (that is, the squeegee protrusion amount) is constant at a predetermined value. As a result, the thickness h of the cream solder 23 printed on the PCB substrate 15 becomes constant at a predetermined value (that is, the printing amount of the cream solder 23 can be quantified). For example, as shown in FIG. 4, when the squeegee pressure is constant at 1.0 [kgf / cm ² ], the degree of squeegee deformation is 0.01 [mm], so the squeegee protrusion amount is approximately 0.01 [mm]. Therefore, if the thickness of the screen 19 is 200 [μm], the thickness h of the cream solder 23 is constant at 190 [μm].

As described above, in the cream solder printing machine 10,
At the time of printing, by controlling the squeegee pressure by controlling the squeegee protrusion amount, it is possible to quantify the thickness h of the cream solder 23 printed on the PCB substrate 15 (that is, the printing amount of the cream solder 23). As a result, it is possible to reduce solder defects such as conventional solder bridging and insufficient solder. In this case, since it is not necessary to adjust the pushing amount of the squeegee, which requires skill in the art as in the conventional case, the variation in the adjustment between the squeegees of the double squeegee is theoretically eliminated, and the stable cream solder 23 can be printed.

Here, FIGS. 9A and 9B show a comparison of the amount of cream solder printed between the conventional cream solder printing machine and the cream solder printing machine 10 of this embodiment. As is apparent from FIG. 9, in the conventional cream solder printing machine, the variation in printing amount was about 0.112 [g] between the squeegees of the double squeegee.
Can be reduced to about 0.034 [g]. The reason for this is that, as described above, the cream solder printer 10 eliminates the need to adjust the pushing amount of the squeegee, which requires skill.

Similarly, since there is no variation in adjustment among the cream solder printing machines provided in a plurality of lines, the thickness h of the cream solder 23 (that is, the printing amount of the cream solder 23) is unified among the cream solder printing machines. it can. Further, in the cream solder printing machine 10, since it is not necessary to adjust the pushing amount of the squeegee as described above, the adjustment time (about 20 to 40 minutes) conventionally required is substantially eliminated, and the work efficiency can be improved. .

According to the above configuration, the squeegee protrusion amount is controlled by the squeegee pressure during printing, so that the PC
The printing amount of the cream solder 23 printed on the B board 15 can be quantified. In this case, since it is not necessary to adjust the pushing amount of the squeegee, which requires skill, it is possible to improve the working efficiency as a whole.

(6) Other Embodiments In the above embodiments, the present invention is applied to the cream solder printing machine using the square squeegees (squeegees 22A and 22B). Is not limited to this, and can be applied to a cream solder printing machine using a sword squeegee or a flat squeegee. This is because the squeegee pressure and the squeegee deformation degree have a similar correlation in the case of a sword squeegee and a flat squeegee, and the same principle holds.

In the above embodiment, the case of the double squeegee consisting of the two squeegees 22A and 22B has been described, but the present invention is not limited to this, and the number of squeegees may be another number.

Further, in the above-mentioned embodiment, the case where the squeegee pressure is made constant by using the pressure control system 25 having the structure shown in FIG. 7 has been described, but the present invention is not limited to this. A pressure control system 3 having a configuration as shown in FIG.
0 may be used to make the squeegee pressure constant. In this case, the pressure control system 30 supplies a predetermined pressure (for example, approximately 1 [kgf / cm ² ]) to the cylinder 21A or 21B by the precision regulator 31 (similar to the pressure control system 25 shown in FIG. 7). The squeegee pressure is measured by the total 32. Then, the pressure control system 30 controls the precision regulator 31 by the control unit 33 based on the pressure value measured by the pressure gauge 32, so that the cylinder 21A or 21B is controlled.
The pressure supplied to is constant. By controlling the squeegee pressure in this way, the squeegee pressure can be made more constant and the pressure adjustment can be automated.

[0034]

As described above, according to the present invention, at the time of printing,
Printing the printed wiring board by controlling the amount by which the tip of the squeegee projects into the opening due to elasticity by adjusting the pressure when the squeegee is brought into contact with the other surface of the screen. It is possible to realize a solder printing apparatus that can quantify the printing amount of the solder material to be used, and thus can quantify the printing amount of the solder material without requiring adjustment by a skilled technique.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing a mounting process of a chip component.

FIG. 2 is a schematic diagram showing a configuration of a cream solder printing machine according to an embodiment of the present invention.

FIG. 3 is a schematic diagram for explaining the operation.

FIG. 4 is a schematic diagram showing a correlation between a squeegee pressure and a squeegee deformation degree when the squeegee hardness is 90A.

FIG. 5 is a schematic diagram showing the relationship between the amount of squeegee gouging and the thickness of solder at the opening of the screen.

FIG. 6 is a schematic diagram showing a correlation between a squeegee pressure and a squeegee deformation degree when the squeegee hardness is 80B.

FIG. 7 is a block diagram showing the configuration of a pressure control system.

FIG. 8 is a schematic diagram showing a setting state of a pressing amount of a squeegee.

FIG. 9 is a schematic diagram showing a comparison of print amounts of cream solder.

FIG. 10 is a block diagram showing the configuration of a pressure control system according to another embodiment.

FIG. 11 is a schematic diagram showing a relationship between a squeegee pushing amount and a cream solder thickness in a conventional cream solder printing machine.

[Explanation of symbols]

10: Cream solder printer, 15: PCB board, 1
6 ... Printing table, 17 ... Base part, 18 ... Table cylinder, 19 ... Screen, 19A ... Opening part,
20 ... Squeegee unit, 21A, 21B ... Cylinder, 22A, 22B ... Squeegee, 23 ... Cream solder, 24A, 24B ... Squeegee holder, 25, 30 ...
… Pressure control system.

Claims (4)

[Claims] 1. A paste-like material supplied to the other surface of the screen by bringing the printed wiring board into contact with one surface of the screen and moving a squeegee in contact with the other surface of the screen along the screen. In a solder printing apparatus for printing the solder material on the printed wiring board through an opening hole formed in the screen, at the time of printing, the amount of the tip of the squeegee protruding into the opening hole by elasticity, A solder printing apparatus, wherein the squeegee is controlled by adjusting the pressure when the squeegee is brought into contact with the other surface of the screen. 2. The solder printing apparatus according to claim 1, wherein the squeegee is a square squeegee having a substantially rectangular cross section. 3. The solder printing apparatus according to claim 1, wherein a plurality of the squeegees are arranged on the screen. 4. The solder printing apparatus according to claim 1, wherein the screen is made of a metal material.