JPH081907A - Printing amount inspection method for cream solder - Google Patents

Abstract

(57) [Summary] [Object] An object of the present invention is to provide a method for inspecting a print amount of cream solder, which can accurately determine the quality of the print amount of cream solder printed on an electrode of a substrate by a screen printing device at high speed. . [Structure] After a cream solder 16 is printed on an electrode of a substrate 7 by a screen mask 11 and a squeegee 15, a plane image of a pattern hole is obtained by a mask recognition camera 9, and a cream printed on the electrode by a substrate recognition camera 10. Solder 1
Acquire 6 plane images. The quality of the printing amount of the cream solder 16 is determined based on these two plane images. [Effect] Since two plane images are obtained, there is much information for the quality judgment, and therefore the quality judgment can be performed accurately.
Further, since the mask recognition camera 9 and the board recognition camera 10 are used, inspection can be performed at high speed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cream solder print amount inspection method for inspecting the quality of the print amount of cream solder printed on an electrode of a substrate by a screen printing device having a screen mask and a squeegee. .

[0002]

2. Description of the Related Art A screen printing device is often used as a means for applying cream solder for soldering electronic parts to electrodes on a substrate. The screen printing device is equipped with a screen mask with squeegees that have pattern holes.The electrodes of the substrate and the pattern holes of the screen mask are aligned, and the screen mask is superposed on the upper surface of the substrate. After the squeegee is slid on the top surface to fill the pattern holes with the cream solder, the screen mask and the substrate are separated in the vertical direction, and the cream solder is removed from the pattern holes to print the cream solder on the electrodes. It has become.

In recent years, substrates are becoming smaller and more highly integrated, and the opening area of the pattern holes of the screen mask is becoming smaller accordingly. For this reason, the ability of the cream solder to escape from the pattern holes is deteriorated, and cream solder having a poor printing state tends to be easily produced.

If the shape of the cream solder printed on the electrodes of the substrate is bad, especially when the amount of cream solder is insufficient,
Since the soldering state of the electronic component also becomes defective, after the cream solder is printed, an inspection is performed to determine whether the printed amount of the cream solder is good or bad. As the inspection method, firstly, the cream solder printed on the substrate is observed from above by a camera, a plane image of the cream solder is obtained, and the area of the cream solder based on the plane image is used to determine the printing amount of the cream solder. A method of determining pass / fail is known. Secondly, the cream solder printed on the substrate is repeatedly scanned with a laser beam at a small pitch to measure a precise height distribution of the cream solder, and based on this height distribution, the cream solder A method for determining whether the print amount is good or bad is known.

[0005]

However, the first method using a camera has an advantage that the inspection speed is high because the plane information of the cream solder is collectively obtained by the camera, but the camera is two-dimensional (flat). Since only information is available and the amount of information is small, there is a problem that the quality of the print amount cannot be accurately determined, and many erroneous determinations are made. In addition, the second method using the laser light includes the height information 3
Since the dimensional information can be obtained, it is possible to accurately estimate the print amount of the cream solder, and thus it is possible to accurately judge the quality of the print amount. Since it is necessary to measure the size distribution, there is a problem that a long inspection time is required and work efficiency is not improved. In addition, there is a problem that the laser device for irradiating the laser beam is expensive and the facility cost is too high.

SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a method for inspecting a print amount of cream solder, which can accurately determine the quality of the print amount of cream solder at a high speed by using a camera.

[0007]

To this end, the present invention obtains a planar image of the pattern holes of the screen mask with a mask recognition camera and a planar image of the cream solder printed on the substrate with the substrate recognition camera. Based on the plane image of the pattern hole and the plane image of the cream solder, the quality determination unit determines whether the print amount of the cream solder is good or bad.

[0008]

According to the above construction, two image data of the pattern hole planar image and the cream solder planar image are obtained, and based on these two image data, the quality of the cream solder printing amount is accurately determined at high speed. Can be determined.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will now be described with reference to the drawings. FIG. 1 is a side view of a screen printing apparatus according to an embodiment of the present invention, and FIG. 2 is a block diagram of an image processing system of the screen printing apparatus. In FIG. 1, 1 is a Y table section, 2 is an X table section, and 3 is a Z table section, which are stacked. Reference numeral 4 is a motor for driving the Y table portion, and 5 is a motor for driving the X table portion. A holding unit 6 is placed on the Z table unit 3, and a substrate 7 is held on the holding unit 6. A bracket 8 is attached to a side portion of the X table portion 2, and a mask recognition camera 9 is held on the bracket 8.

A board recognition camera 10 is provided above the board 7. Moreover, a screen mask 11 is provided on the side thereof.
Is provided. Holder 12 of screen mask 11
Are held by the mask holder 13. A print head 14 is provided on the screen mask 11. The print head 14 includes two squeegees 15, and cream solder 16 is stored between the squeegees 15.

In the above structure, the Y table portion 1 is driven to move the substrate 7 directly below the screen mask 11,
Then, the Z table portion 3 is driven to raise the substrate 7, and the upper surface of the substrate 7 is brought close to the lower surface of the screen mask 11. Next, attach the squeegee 15 to the screen mask 11
The cream solder 16 is filled in the pattern holes (not shown) opened in the screen mask 11 by sliding the cream solder 16 on the top. Next, the Z table portion 3 is driven to lower the substrate 7 to separate the substrate 7 from the screen mask 11. At this time, the cream solder 16 filled in the pattern holes is released from the pattern holes to cause the substrate 7 to escape. Printed on 7 electrodes.

In FIG. 2, the mask recognition camera 9 has a first
Is connected to the recognition unit 21 and the print state determination unit 23.
The board recognition camera 10 is connected to the second recognition unit 22 and the print state determination unit 23. First recognition unit 21, second
The recognition unit 22 and the print state determination unit 23 are composed of a CPU. FIG. 3 is an explanatory view of an image of one embodiment of the present invention and a cross-sectional shape of cream solder. (A) to (F) show typical examples of the image and the cross-sectional shape of the cream solder 16. (A)
Is a plane image of the pattern hole 18 of the screen mask 11 obtained by the mask recognition camera 9, (b) is a plane image of the cream solder 16 obtained by the board recognition camera 10,
(C) is an actual sectional shape of the cream solder 16 printed on the electrode 19 of the substrate 7.

Next, a method of inspecting the print amount of the cream solder 16 will be described with reference to FIGS. First, before printing the cream solder 16 on the substrate 7, the area S of the pattern hole 18 of the screen mask 11 is measured. That is, in FIG. 1, the Y table portion 1 is driven to move the mask recognition camera 9 below the screen mask 11. Therefore, the X table portion 2 and the Y table portion 1 are driven to move the mask recognition camera 9 in the X direction and the Y direction, and each pattern hole 18 is observed and the area S thereof is measured. This area calculation and calculation result data are
Is stored in the recognition unit 21.

After the area S of each pattern hole 18 is obtained in advance as described above, the substrate 7 is moved below the screen mask 11 and the squeegee 15 is moved as described above.
The cream solder 16 is printed on the electrode 19 of the substrate 7 by sliding.

After the cream solder 16 is printed as described above, a quality check of the printing amount is performed as follows. First, the mask recognition camera 9 is moved below the screen mask 11 and then moved in the X direction and the Y direction to obtain a plane image of the pattern hole 18. FIG.
In (a), the planar image of the obtained pattern hole 18 is shown. In the figure, 18 is a pattern hole, and 16 is a cream solder attached to the edge of the pattern hole 18. The cream solder 16 adheres to the edge of the pattern hole 18 due to poor printing removal, and the pattern hole 18 is clogged due to the cream solder 16. The image of this embodiment is a binary or multi-valued bright / dark image, and its image data is stored in the first recognition unit 21.

Next, the board 7 is moved to the lower side of the board recognition camera 10, and the board 7 is moved there in the X and Y directions to obtain a plane image of the cream solder 16 printed on the electrodes 19 of the board 7. To do. FIG. 3B shows the plane image. This plane image is also a light and dark image,
The image data is stored in the second recognition unit 22.

Next, each image and a method for judging quality will be described. The cream solder 16 is not attached to the pattern holes 18 shown in (A)-(a), and the cream solder 16 filled in the pattern holes 18 is all transferred and printed on the electrodes 19 of the substrate 7. . In this case, the cross-sectional shape of the cream solder 16 is a quadrangle without deformation as shown in (A)-(c), and the cream solder 16 is a good product.

The cream solder 16 is partially adhered to both side portions of the pattern holes 18 of (B)-(a), and only the central portion of the pattern hole 18 is completely removed. In this case, as shown in (B)-(c), the cross-sectional shape of the cream solder 16 is normal only in the central portion, and both side portions are deformed and thin. The amount of such cream solder 16 is insufficient and is a defective product.

Here, the first by the conventional camera described above.
In the above method, only the plane image of the cream solder 16 shown in (B)-(b) is obtained. However, since the images of (B)-(b) cannot be distinguished from the images of (A)-(b), the cream solder 16 is erroneously determined as a non-defective product in the conventional method. On the other hand, in this method,
(B)-(a) image of the pattern hole 18, and (B)
Since the image of the cream solder 16 shown in-(b) is obtained, the cross-sectional shape of the cream solder 16 is shown in (B)-(c) from the plan image of the pattern hole 18 in (B)-(a). It is presumed to have a shape, so this cream solder 16
Can be correctly determined to be defective. That is, this method determines that the print amount of the cream solder 16 is good only when both the plane images shown in (a) and (b) are good. It should be noted that the print state determination unit 23 performs the quality determination based on the planar images of (a) and (b).

Another example will be briefly described below.
The cream solder 16 is attached to the left half of the pattern hole 18 of (C)-(a), and the cream solder 16 is partially applied to the electrode 19 as shown in (C)-(b). .
In this case, the cream solder 16 is presumed to have a shape that adheres only to the right half of the electrode 19, as shown in (C)-(c). The distribution of the cream solder 16 on the electrode 19 is non-uniform and the amount is insufficient, so that the product is defective.

Although the pattern holes 18 of (D)-(a) and (E)-(a) are completely removed from the printing plate, (D)-
The images of (c) and (E)-(b) have a horizontally long thin elliptical shape. In this case, the cream solder 1 on the electrode 19
It is presumed that the edge of No. 6 is raised as shown in (D)-(c), or the center is raised as shown in (E)-(c). The amount of this cream solder 16 is also insufficient and is determined to be a defective product.

The pattern holes 18 of (F)-(a) are completely clogged with the cream solder 16. in this case,
The cream solder 16 does not exist on the electrode 19 and is defective.

Next, a supplementary explanation will be given on the above-mentioned quality judgment. The cream solder 16 is partially attached to the pattern holes 18 shown in (B)-(a) and (C)-(a). In this case, it is necessary to set the threshold value for the quality judgment. Here, as described above, the area of the pattern hole 18 obtained by observing the pattern hole 18 in advance with the mask recognition camera 9 before printing the cream solder 16 is S. Further, the area Si of the opening of (B)-(a) is obtained. This area Si is obtained from the image of (B)-(a). These areas S and Si are stored in the first recognition unit 21. Next, the ratio of the area Si to the area S is obtained, and if this ratio is less than or equal to the threshold value, it is determined as a good product. (C)-
Also in the case of (a), the area Si of the opening is similarly obtained,
If the ratio is less than or equal to the threshold value, it is determined to be non-defective.
The quality determination methods of (B)-(a) and (C)-(a) are not limited to this method, and may be determined from the size of the area Si of the opening, for example.

The quality judgment by introducing such a threshold value is similarly performed in the case of the images shown in (D)-(b) and (E)-(b). That is, if the areas of these images are equal to or larger than a predetermined threshold value, it is determined that the image is good.
The first recognizing unit 21 and the second recognizing unit 22 store these threshold values and perform necessary calculations.

In addition, the quality judgment criterion of the print amount of the cream solder 16 differs depending on the substrate 7, the type of electronic component to be soldered on the substrate 7, and the like. Therefore, the above-mentioned threshold value is arbitrarily set according to the type of the board 7 and electronic components. In the above embodiment, for example, (D)-
In the case of (E), it is judged as a defective product, but the quality judgment standard also differs depending on the type of the substrate 7 and the electronic parts. Therefore, in the case of (D)-(E), it is judged as a non-defective product. You may. As described above, the quality determination standard is arbitrarily determined. Also, the above inspection is performed for all pattern holes 18 and electrodes 19.
However, it takes a long time to inspect everything. Therefore, an arbitrary number of pattern holes 18 and electrodes 19 may be selected and the above inspection may be performed only for these. In this case, those having a high degree of difficulty in screen printing (specifically, those having a small opening area of the pattern hole 18)
It is desirable to select.

[0026]

As described above, according to the present invention, two image data, that is, a plane image of a pattern hole and a plane image of cream solder, are obtained, and the printing amount of cream solder is determined based on these two image data. Since the quality determination is performed, the quality determination can be accurately performed. In addition, since two planar images are collectively obtained by using two cameras, inspection at high speed is possible.

[Brief description of drawings]

FIG. 1 is a side view of a screen printing apparatus according to an embodiment of the present invention.

FIG. 2 is a block diagram of an image processing system of a screen printing apparatus according to an embodiment of the present invention.

FIG. 3 is an illustration of an image of one embodiment of the present invention and a sectional shape of cream solder.

[Explanation of symbols]

 7 Substrate 9 Mask Recognition Camera 10 Substrate Recognition Camera 11 Screen Mask 15 Squeegee 16 Cream Solder 18 Pattern Hole 19 Electrode 23 Printing State Judgment Section

Claims (1)

[Claims] 1. A method of inspecting the amount of cream solder printed on an electrode of a substrate by a screen printing device equipped with a screen mask and a squeegee, the method comprising: The step of obtaining the plane image of the pattern hole, the step of obtaining the plane image of the cream solder printed on the board by the board recognition camera, and the pass / fail based on the plane image of the pattern hole and the plane image of the cream solder. A method of inspecting a print amount of cream solder, comprising the step of determining whether the print amount of cream solder is good or bad by a determination means.