JP2002019084A - Cream solder printing state inspection method and inspection device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method and an apparatus for detecting the printing state of cream solder, which can accurately inspect the printing state of cream solder. SOLUTION: In step 1, a threshold value is set, in step 2, a color image of the cream solder is photographed, in step 3, the image is processed to obtain image data, and in step 4, the printing state of the cream solder is obtained. Is determined. When the determination result is abnormal in step 5, the illuminance is adjusted if the amount of solder extraction is large and exceeds the allowable range in step 6, and if the luminance of the solder is larger than the reference value in step 7,
The brightness is adjusted by inserting a polarizing film. If neither the cream solder nor the land can be extracted in step 8, a wavelength cut film is inserted and re-inspected.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for inspecting the printing condition of cream solder printed on a printed circuit board.

[0002]

2. Description of the Related Art In recent years, in mounting electronic parts, cream solder is printed on a land (circuit electrode portion) formed on a printed circuit board by a screen printing machine, and the cream solder is heated and reflowed. The method of soldering electronic components to a board is widely used, but the quality of the printed solder paste affects the quality of the printed board on which the electronic components are mounted.
It is required to accurately inspect the printing state.

A conventional method for inspecting the printing state of cream solder will be described with reference to the drawings together with a screen printing method for cream solder. FIG. 3 is a plan view showing an example of a conventional screen printing machine, FIG. 4 is a side view thereof, FIG. 5 is a block diagram showing an example of a control device of the screen printing machine, and FIG. FIG. 7 is a schematic diagram showing an example of a printed state of cream solder.

[0004] As shown in FIGS. 3 and 4, a screen printer uses a plurality of lands 12 formed on a printed circuit board 1.
Screen having an opening (pattern hole) 7 conforming to the shape of the screen 3 and a pair of squeegees 4 and 5 for printing cream solder 6 on a land 12 formed on the printed circuit board 1 A machine main body, and a table 2 arranged near the screen printing machine main body for holding and moving a printed circuit board 1 carried in from a previous process;
And a recognition camera 8 provided with an illumination device 11 capable of adjusting the illuminance in two or three stages.

[0005] The screen printing machine is controlled by a control device shown in FIG. The control device includes a CPU 14 for controlling the entire screen printing machine, a recognition camera 8 for photographing the recognition marks 9 and 10 on the printed circuit board 1 and a printing state of the cream solder in color, and a recognition camera 8 connected thereto. An image processing unit 15 for processing a color image captured by the camera, an illuminating device 11, an illuminance control unit 16 connected thereto for controlling the illuminance of the illuminating device 11, a recognition camera 8, and a printed circuit board. Detection sensor 18 (not shown in FIGS. 3 and 4) for detecting the position of table 2 or the like
And an NC (Numerical Control) unit 17 connected thereto for positioning the recognition camera 8 and the table 2 and the like.
The illuminance control unit 16 and the NC unit 17 each have a CP
It is connected to U14.

In the above configuration, first, the position of the printed circuit board 1 carried in from the previous process is regulated on the table 2.
Next, in order to correct the position when the printed circuit board 1 is aligned with the screen 3, a pair of recognition marks 9 and 10 provided on the diagonal of the printed circuit board 1 are photographed by the recognition camera 8, and are image-processed. To obtain image data. When obtaining the image data, first, the table 2 is moved to the position of the recognition camera 8 in order to photograph the recognition mark 9, the lighting device 11 is turned on, and the recognition mark 9 is photographed by the recognition camera 8. Next, the table 2 is moved again to the position of the recognition camera 8 to photograph the recognition mark 10, and the recognition mark 10 is photographed by the recognition camera 8. Next, the image of the recognition marks 9 and 10 captured by the recognition camera 8 is subjected to image processing to obtain image data.

Next, the table 2 is moved,
Is raised to the back surface of the screen 3, the printed circuit board 1 is overlapped on the lower surface of the screen 3, and the position is corrected based on the image data.

Thereafter, the squeegee 4 is moved rightward to apply the cream solder 6 to the land 12 of the printed circuit board 1 from the opening 7 of the screen 3, and the table 2 is lowered to separate the printed circuit board 1 from the screen 3. As a result, the printed board 1 on which the plate has been removed and on which the cream solder 6 has been printed is obtained.

The printed circuit board 1 is positioned at a designated position, and the printed state of the cream solder is inspected. Printed circuit board 1 for which inspection of the printing state of cream solder has been completed
Among them, those whose printing state is determined to be normal printing are carried out to the next step. Thereafter, the next printed circuit board 1 is carried into the table 2 and printing is performed by moving the squeegee 5 leftward, and the same operation is repeated. The printed circuit board 1 whose printing state is determined to be abnormal is subjected to reprinting or the like.

The printing condition of the cream solder is inspected as follows. In order to inspect the printing state of the cream solder printed on the printed circuit board 1, it is assumed that the background color such as the color of the printed circuit board, land, and wiring is distinguished from the color of the cream solder to be inspected. Becomes

Therefore, in step 1 (S1), a threshold value as a reference for determining whether the printing state of the cream solder 6 is good or bad is set. The threshold is set by selecting a specific land 12 and applying the cream solder 6 printed on the land 12 to the printed circuit board 1 and the land 1 serving as the background.
2. The image processing is performed by photographing the color with the recognition camera 8 together with the wiring and the like, and at this time, the cream solder 6
In order to distinguish and extract the background color such as the color of the color, the illuminance of the illumination of the illumination device 11 is adjusted to perform color photographing. The set threshold value is taught (input) to the memory of the image processing unit 15 together with the illuminance, the type of the printed circuit board 1, and the like.

In step 2 (S2), the designated land 12 is photographed by the recognition camera 8 to obtain a color image. In step 3 (S3), the color image is processed to obtain color image data.

In step 4 (S4), the image data is compared with a threshold value. As shown in FIG. 7, (a) normal printing, (b) blurring, (c) blurring, and (d) misalignment Is determined. In FIG. 7, reference numeral 13 denotes a wiring.

In step 5 (S5), if the result of the determination is abnormal (NO), operation stop is designated in step 6 (S6), or screen cleaning is designated in step 7 (S7). Alternatively, in step 8 (S8),
Reprint is specified.

If it is determined in step 5 (S5) that the printing is normal (OK), the printed circuit board 1 is carried out to the next step in step 9 (S9).

[0016]

However, in the conventional method for inspecting the printing state of cream solder, the illuminance of the illuminating means is adjusted in at most two or three steps, the cream solder is photographed, and image processing is performed to process the cream solder. Since the printing condition is inspected, the color of the cream solder and its background color are affected by the background color due to differences in the background color, such as the color of the printed circuit board for each lot, even for the same type of printed circuit board. In some cases, it is difficult to distinguish them.In addition, if the printed circuit board that has been judged to be abnormal by inspecting the printing state of the cream solder is subjected to printing again, the background color such as the color of the printed circuit board when reflowing the previously printed cream solder Changes, the color changes slightly when setting the threshold value of the cream solder, making it impossible to distinguish the cream solder color from its background color. Ri, there is a risk judged to be normal despite abnormal. Also, when setting the threshold value of the cream solder, the color of the cream solder and its background color cannot be distinguished, and the threshold value cannot be set accurately. Even if there was an abnormality in the printing state, it was sometimes determined that the printing was normal.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and an object of the present invention is to provide a cream solder printing state inspection method and an inspection apparatus capable of accurately inspecting the cream solder printing state. .

[0018]

Means for Solving the Problems In order to solve the above-mentioned problems, among the present invention, the invention according to claim 1 is a method in which cream solder printed on a land of a printed board by a screen printing machine has a predetermined color. And color photographing under illumination having illuminance, image processing of this color image to obtain color image data, comparison of the color image data with a preset threshold value of cream solder, printing of cream solder In the method of inspecting the state, when color printing is performed under illumination having the predetermined color and predetermined illuminance and the printing state of the cream solder is determined to be abnormal, according to the printing state of the cream solder determined to be abnormal. At least one of the following steps is selected, and the cream solder is again color-photographed and inspected again.

(A) adjusting the illuminance of the illumination to five or more levels to change it to another illuminance; (b) changing the color of the illumination to another color; and (c) adjusting the brightness of the cream solder. Step.

According to the above configuration, when the printing state of the cream solder is determined to be abnormal, (a) the illuminance of the illumination is changed in accordance with the printing state of the cream solder determined to be abnormal, and (b) the illumination is changed. Since at least one of the steps of changing the color and (c) adjusting the brightness of the cream solder is selected and the color image is taken again and inspected again, an erroneous determination based on the illuminance of the illumination, the color of the illumination and the brightness of the cream solder is made. Therefore, the possibility that a normal product is determined to be abnormal due to these causes is reduced, and erroneous determination of the printing state of the cream solder can be reduced. In addition, when changing the illuminance, the illuminance is changed by adjusting the illuminance in more steps than before, so that a more appropriate color image can be obtained. Therefore, the printed state of the cream solder can be inspected more accurately than in the past.

According to a second aspect of the present invention, the cream solder printed on the land of the printed circuit board is photographed in color under illumination having a predetermined color and a predetermined illuminance by a screen printing machine, and the color image is formed. In the method of obtaining color image data by image processing, comparing the color image data with a preset threshold value of cream solder, and inspecting the printing state of cream solder, selecting a specific land and selecting a cream When performing color photographing of the solder under illumination having a predetermined color and a predetermined illuminance and performing image processing on the photographed color image to set a threshold value of the cream solder, the color of the cream solder and its background color are compared. When it is difficult or difficult to distinguish, at least one of the following steps is selected and the cream A and color photography is used to set the threshold of the cream solder.

(A) adjusting the illuminance of the illumination in five or more steps to change it to another illuminance; (b) changing the color of the illumination to another color; and (c) adjusting the brightness of the cream solder. Step.

According to the above configuration, when the color of the cream solder and its background color cannot be distinguished or difficult to distinguish, (a) change the illumination intensity, (b) change the color of the illumination, (c) Since at least one of the steps of adjusting the brightness of the cream solder is selected, the color of the cream solder can be more clearly distinguished from its background color, and the threshold value of the cream solder can be accurately set. And it is less likely that abnormalities in the printing state are determined to be normal. Therefore, the printed state of the cream solder can be inspected more accurately than in the past.

According to a third aspect of the present invention, there is provided a color photographing means for photographing a color of cream solder printed on a land of a printed circuit board by a screen printing machine, and an illuminating means for illuminating a photographing visual field. And in a cream solder print state inspection apparatus equipped with image processing means for obtaining color image data by image processing the captured color image and control means for controlling these,
The illumination means is formed from a plurality of light sources emitting illumination lights of different colors and is formed such that the illuminance can be adjusted in five or more steps. It is provided so as to be able to enter and exit in the optical path of the means.

According to the above configuration, it is possible to accurately inspect the printing state of the cream solder.

[0026]

Embodiments of the present invention will be described below with reference to the drawings. In each of the drawings, components having the same functions as those in the related art will be described with the same reference numerals.

An embodiment of the present invention will be described with reference to FIGS. FIG. 1A is a block diagram showing a control device of a screen printing machine provided with a cream solder printing state inspection device according to an embodiment of the present invention, FIG. 1B is a schematic diagram of the lighting device, and FIG. 5 is a flowchart illustrating an example of an operation in the method for inspecting the printing state of cream solder according to the present invention. In addition, the said screen printing machine in one Embodiment of this invention removes a control apparatus and an illuminating device,
Since the configuration of the apparatus is the same as that of the conventional screen printing machine shown in FIGS. 3 and 4, the description of the configuration of the apparatus will be omitted.

In FIG. 1A, a control device in a screen machine provided with a cream solder printing state inspection device includes a CPU 14 for controlling the entire screen printing machine and a cream solder printing system, as in the conventional screen printing machine. A recognition camera 8 for capturing a color image of a state, an image processing unit 15 connected to the recognition camera 8 for processing a color image captured by the recognition camera 8 in color, and the recognition camera 8
, An illuminance controller 16 connected to the illuminator 11 for controlling the illuminance of the illuminator 11, a table (not shown) for moving the printed circuit board, and the positions of the recognition camera 8 and the like are detected. And an NC (Numerical Control) unit 17 connected thereto for positioning the recognition camera 8 and the like. The image processing unit 15, the illuminance control unit 16, and the NC unit 17 are It is connected to the. In addition, a wavelength cut filter 21 and a polarization filter 22 that are switchably attached to the illumination device 11 and a filter switching control unit 24 that is connected to the filter and switches the filter are provided. It is connected to CPU14.

The illuminance of the illuminating device 11 can be switched by the illuminance control section 16 in accordance with a command from the CPU 14 in multiple stages of, for example, 8 bits. Further, as shown in FIG. 1B, the lighting device 11 attached to the recognition camera 8 is provided with three light sources of red, green and blue, and these three light sources are controlled by the CPU 14. Lighting can be performed by appropriately combining colors. Normally, all three light sources are turned on to emit white light. Then, a wavelength cut filter 21 (for example, a filter for cutting a green wavelength), 21 (for example, a filter for cutting a red wavelength) between the illumination device 11 and the recognition camera 8 for cutting a wavelength of a specific color, and A polarization filter 22 for adjusting the brightness is provided so as to be switchable by a filter switching device 23, and is attached so as to be able to enter and exit the optical path of the illumination device 11.

The illuminance of the illumination device 11 can be finely adjusted manually, and the wavelength cut filter 21 and the polarization filter 22 can be switched manually. In the above configuration, the inspection of the printing state of the cream solder printed on the printed circuit board is performed as follows.

In step 1 (S1), a threshold value is set, and teaching (input) is made to the memory of the image processing section together with other necessary input items. The threshold setting is the same as before.
A specific land is selected, and the cream solder printed on the land is photographed in color with the recognition camera 8 together with the background of the printed circuit board, land, wiring, and the like, and image-processed. At this time, in order to extract the cream solder while distinguishing between the color of the cream solder and the background color such as the color of the printed circuit board, all the three light sources of the lighting device 11 are turned on to set the illumination color to white, Is adjusted in multiple steps of 8 bits by a command from the CPU 14 to set a predetermined illuminance, and color photographing is performed under this illumination.

Here, as the threshold value of the cream solder, first, a basic threshold for judging the acceptability of the amount of solder extraction (area), the shape of the solder, and the printing condition of the cream solder such as the printing position. Set the value. In addition, items necessary for determining the quality of the printed state of the cream solder, such as a reference value of the brightness of the cream solder, are set.

The set threshold value, luminance reference value, etc.
The illuminance, the type of the printed circuit board 1 and the like are taught (input) to the memory of the image processing unit 15 as image data. When setting the threshold value, when the color of the cream solder and its background color cannot be distinguished or are difficult to distinguish, (a) adjusting the illuminance of the illumination of the illumination device 11 to another illuminance; (B) inserting a wavelength cut filter 21 in the optical path of the lighting device 11 or (c) inserting a polarizing filter 22 in the optical path of the lighting device 11 to adjust the brightness of the cream solder, The cream solder is easily extracted, and this is photographed in color to set the threshold value of the cream solder.

Next, in Step 2 (S2), a color image is taken by the recognition camera 8 of the designated land on which the cream solder is printed. In step 3 (S3), the image is processed to obtain image data.

In step 4 (S4), the image data is compared with a threshold value to determine whether the printing state of the cream solder is normal. In step 5 (S5), when the determination result is abnormal (NO), in step 6 (S6), when the amount of solder extraction is large and exceeds the allowable range (YES),
Since it is considered that a portion other than the solder is also determined to be the solder, the illuminance of the lighting device 11 is adjusted, and the process returns to the step 2 to perform the inspection again.

In step 7 (S7), when the amount of solder extraction is within the allowable range (NO) and the luminance is larger than the reference value (Y
ES), since it is considered that there is an influence of the reflected light from the printed circuit board, the polarization filter 22 is inserted to adjust the luminance, and the process returns to step 2 (S2) to perform the inspection again.

In step 8 (S8), when the brightness of the cream solder is within the reference value (NO), and when neither the cream solder nor the land can be extracted (YES),
Since it is conceivable that the color of the printed circuit board is affected, a filter for cutting the color of the printed circuit board, for example, if the color of the printed circuit board is green, a wavelength cut filter 21 for cutting a green wavelength is inserted, and step 2 (S2) is performed. Return to and perform the inspection again.

In step 9 (S9), when both the cream solder and the land have been extracted (NO) and the cream solder is faint, the screen may be clogged. specify.

In step 10 (S10), if the cream solder is not blurred (NO), it is determined that the screen is not clogged, so whether the printing can be reprinted from the printing state (YES) or not (NO) Is determined, reprinting is designated if reprinting is possible (YES), and operation is stopped if reprinting is not possible (NO).

If the inspection result obtained in step 5 (S5) is determined to be acceptable (OK), step 11 (S1
The inspection is finished in 1), the printed circuit board is carried out, and the inspection is ended.

According to the above embodiment, when the amount of the cream solder extracted is large, when the brightness of the cream solder is large, and when neither the solder nor the land can be extracted, re-inspection is performed. Things can be reduced.

[0042]

As described above, according to the first aspect of the present invention, the illuminance of the illumination and the color of the illumination are changed, or the brightness of the cream solder is adjusted and the inspection is performed again. Accordingly, the possibility that a normal one is determined to be abnormal is reduced, and erroneous determination of the printing state of the cream solder can be reduced. Therefore, the printed state of the cream solder can be inspected more accurately than in the past.

According to the second aspect of the present invention, the threshold value is set by changing the illuminance of illumination and the color of illumination or by adjusting the brightness of the cream solder. The background color can be more clearly distinguished, the threshold value of the cream solder can be set accurately, and it is less likely that abnormalities in the printing state are determined to be normal. Therefore, the printed state of the cream solder can be inspected more accurately than in the past.

According to the third aspect of the present invention, the printed state of the cream solder can be accurately inspected.

[Brief description of the drawings]

FIG. 1A is a screen printing machine provided with a cream solder printing state inspection device according to an embodiment of the present invention, and FIG. 1A is a block diagram showing a control device thereof;
(B) is a schematic diagram showing the lighting device.

FIG. 2 is a flowchart showing an example of an operation in the method for inspecting a printed state of cream solder according to the present invention.

FIG. 3 is a plan view showing an example of a conventional screen printing machine.

FIG. 4 is a side view of the screen printing machine.

FIG. 5 is a block diagram showing an example of a control device of the screen printing machine.

FIG. 6 is a flowchart showing an operation in a conventional cream solder printing state inspection method.

FIG. 7 is a schematic diagram showing an example of a printed state of cream solder.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Printed circuit board 2 Table 3 Screen 4 Squeegee 5 Squeegee 6 Cream solder 7 Screen opening 8 Recognition camera 9 Recognition mark 10 Recognition mark 11 Lighting device 12 Land 13 Wiring 14 CPU 15 Image processing part 16 Illumination control part 17 NC part 18 Sensor Reference Signs List 21 wavelength cut filter 22 polarizing filter 23 filter switching device 24 filter switching control unit

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H05K 3/34 512 B41F 33/14 G (72) Inventor Hirono Saito 1006 Odakadoma, Kadoma City, Osaka Matsushita Inside Electric Industrial Co., Ltd. (72) Inventor Kazuyuki Nakano 1006 Kazuma Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd.F-term (reference) BB07 CA03 CA04 DA07 EA14 EA17 EB01 EB02 5E319 AA03 AC01 BB05 CD04 CD29 CD53 GG20

Claims (3)

[Claims] 1. A solder paste printed on a land of a printed board by a screen printing machine is photographed in color under illumination having a predetermined color and illuminance, and the color image is processed to obtain color image data. In the method of comparing the color image data with a preset threshold value of the cream solder and inspecting the printing condition of the cream solder, the color soldering of the cream solder is performed under illumination having the predetermined color and predetermined illuminance. When the printing state is determined to be abnormal, at least one of the following steps is selected according to the printing state of the cream solder determined to be abnormal, and the cream solder is again color-photographed and inspected again. A method for inspecting the printing condition of cream solder, characterized in that: (A) adjusting the illuminance of the illumination in five or more steps to change it to another illuminance; (b) changing the color of the illumination to another color; and (c) adjusting the brightness of the cream solder. 2. A color printing of cream solder printed on a land of a printed circuit board by a screen printing machine under illumination having a predetermined color and a predetermined illuminance, and processing the color image to obtain color image data. In a method of comparing the color image data with a preset threshold value of the cream solder and inspecting a printing state of the cream solder, a specific land is selected to apply a predetermined color and a predetermined illuminance to the cream solder. When color photographing is performed under illumination and image processing of the photographed color image is performed, and when setting the threshold value of the cream solder, when the color of the cream solder and its background color cannot be distinguished or when it is difficult to distinguish them. Selecting at least one of the following steps to photograph the cream solder in color, Cream solder printing state inspection method characterized by setting a threshold. (A) adjusting the illuminance of the illumination in five or more steps to change it to another illuminance; (b) changing the color of the illumination to another color; and (c) adjusting the brightness of the cream solder. 3. A color photographing means for taking a color image of cream solder printed on a land of a printed circuit board by a screen printing machine, an illuminating means for irradiating illumination to a photographing field of view, and image processing of the photographed color image. An image processing device for obtaining color image data and a printing condition inspection apparatus for cream solder including a control device for controlling the image processing device, wherein the illuminating device is formed from a plurality of light sources emitting illumination light of different colors. The cream solder is characterized in that the illuminance can be adjusted in five or more stages, and a brightness adjustment filter and a wavelength cut filter for cutting a wavelength of a specific color are provided so as to be able to enter and exit the optical path of the illumination means. Print condition inspection device.