JP2696878B2 - Substrate inspection method and apparatus - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a board inspection method and apparatus for processing data obtained by imaging a board and inspecting a component mounting state on the board. .

<Prior Art> Conventionally, automatic mounting devices have been used to mount various chip components such as resistors and semiconductor elements on a printed circuit board. However, when using this type of device, the components may not be mounted according to the mounting data.Therefore, after mounting, check the printed circuit board to see if the specified chip components are mounted in the correct positions and in the correct position, It is necessary to inspect whether parts are missing. Conventionally, as this kind of inspection, a manual visual inspection has been performed. However, this does not completely eliminate the occurrence of inspection errors, and it is also difficult to increase the inspection speed.

Therefore, in recent years, various automatic inspection devices for automatically performing this kind of inspection have been proposed.

FIG. 13 shows an example of a conventional automatic inspection device.
It includes a television camera 3, a storage unit 4, a determination circuit 5, a monitor 6, a keyboard 7, and the like as its components. The television camera 3 is for imaging the printed circuit board 2T on which the component 1 is mounted, and the keyboard 7 is for data on the type of the reference printed circuit board 2S serving as an inspection standard as shown in FIG. This is for inputting data relating to the type, arrangement position, mounting posture, shape, etc. of each component 1 placed on the reference printed circuit board 2S, as well as information (data) relating to the inspection processing procedure of each component 1. is there.
The storage unit 4 stores data input from the keyboard 7 and the like, and the determination circuit 5 compares the stored information with information indicated by an image from the television camera 3 and stores the data on the printed circuit board 2T to be inspected. It is determined whether all the parts 1 are present and whether or not these parts 1 are out of position. The monitor 6 displays the judgment result of the judgment circuit 5 and prints out the result.

<Problems to be Solved by the Invention> Incidentally, some components to be inspected have a color similar to the ground color of a printed circuit board. When such a component is inspected by the above-described automatic inspection device, the signal level of the component portion substantially coincides with the signal level of the background portion, so that it is difficult to detect dropout or displacement of the component. .

Therefore, a method has been proposed in which an ultraviolet fluorescent substance is applied to a component mounting position on a printed circuit board, and the presence or absence of a component on the fluorescent substance is inspected by irradiating ultraviolet light and observing (particularly). No. 57-94672). In this method, if the component is dropped from the component mounting position on the printed circuit board, the ultraviolet fluorescent substance is exposed, and the fluorescent substance emits strong fluorescent light upon irradiation with ultraviolet light.

FIG. 15 shows the above inspection method, in which an ultraviolet fluorescent substance 9 is applied between a pair of lands 8, 8 on which components are to be mounted. FIG. 15 (A) shows that no parts are present on the ultraviolet fluorescent substance 9,
Strong fluorescence is generated. On the other hand, in FIG. 15 (B), since the component 1 is present on the ultraviolet fluorescent substance 9, the ultraviolet fluorescent substance 10 is not irradiated with ultraviolet rays, and the fluorescent light is hardly generated.

However, in the case of the above method, since the irradiation light is not visible light, even if the substrate is observed with a television camera, a reflection image of the part due to the irradiation light is not obtained, and information on the part itself, that is, what the part is, In addition, if the component is a resistor, the color code indicating the resistance value is not obtained, and if the component is a capacitor, information such as the location of the polarity mark cannot be obtained. It was difficult to implement.

The present invention has been made in view of the above-described problem, and obtains information on components themselves by enabling use of visible light as irradiation light for component inspection.
Accordingly, it is an object of the present invention to provide a board inspection method and apparatus that realize detailed inspection of mounted components.

<Means for Solving the Problems> In order to achieve the above object, according to the present invention, in a board inspection method for processing data obtained by imaging a board and inspecting a component mounting state on the board, After a paint that gives a high color signal value is applied to a portion where the component contacts the board at the component mounting position on the board surface, the board on which the component is mounted is imaged while irradiating white light to the board, and the component is mounted. The component mounting state on the substrate is inspected based on the reflected light from the mounting position.

According to the inventions of claims 2 and 3, in order to inspect the component mounting state of the board being transferred, the component mounting board is irradiated with white light instantaneously or the component mounting board is imaged instantaneously. I'm going to do it. Further, according to the present invention, an apparatus for processing data obtained by imaging a substrate and inspecting a component mounting state on the substrate has a high reflection at a portion where the component contacts the substrate at a component mounting position on the surface. Light irradiating means for irradiating visible light to a substrate coated with a paint that gives a luminance signal value of light, and imaging means for imaging a substrate under a state where visible light is irradiated by the light irradiating means,
Detecting means for detecting reflected light information of visible light due to application of the paint at a component mounting position on an image of the board imaged by the imaging means, and determining a component mounting state using a detection result by the detecting means And determination means for performing the determination.

<Operation> When a paint that gives a high color signal value is applied to a part where the component contacts the board at the component mounting position, there is a difference between when the component is at an appropriate position and when the component is dropped or misaligned. Then, a difference occurs in the exposed state of the paint applied portion. Therefore, by observing the state of color reflection on an image by irradiating the substrate with white light, the presence or absence of components on the substrate and the state of displacement can be grasped. Further, since the light applied to the substrate is white light, it is possible to read various information on the component from the reflected image, and it is possible to perform a detailed inspection.

Further, if white light irradiation is performed instantaneously or an image of the component mounting board is captured instantaneously, the same inspection can be performed on the board that is in transition. Further, in the invention according to claim 4, while irradiating visible light to a substrate coated with a paint that gives a high luminance signal value of reflected light to a portion where the component contacts the substrate, this substrate is imaged, and the component mounting on the image is performed. By determining the mounting state of the component using the reflected light information of visible light from the position, it is possible to provide a board inspection apparatus capable of determining the mounting state of the component and various pieces of information on the component in detail.

<Embodiment> FIG. 1 shows an example of a board inspection apparatus used for carrying out a board inspection method according to the present invention.

The board inspection apparatus in the illustrated example was obtained by imaging the parameter (determination data) of each component 13S on the reference printed circuit board 10S obtained by imaging the reference printed circuit board 10S and the printed circuit board 10T to be inspected. The inspected printed circuit board 10T
The X-Y table unit 14 and the illumination unit are used to inspect whether each of the components 13T is correctly mounted by comparing the parameters (data to be inspected) of each of the components 13T above. 12, an imaging unit 15, a processing unit 16, and the like are included as components.

The reference printed circuit board 10S is manufactured by performing the steps shown in FIG. 2. First, an etching process, a resist process, a drilling process, etc. are performed on a raw substrate having copper foil on both sides (or one side). Then, the elementary substrate 11 shown in FIG. 2A is formed. Next, as shown in FIG. 2 (B), a paint (for example, yellow 5G or orange 3H manufactured by Taiyo Ink Manufacturing Co., Ltd.) which gives a high color signal value with high brightness or high saturation is provided at each component mounting position on the substrate 11 as shown in FIG. (Paints or inks) 33 are applied by silk screen printing to form a fixed colored area 34, and a predetermined part 13S is mounted on the colored area 34 as shown in FIG. Then, the reference printed circuit board 10S is formed.

FIG. 3 (A) shows rectangular lands 35, 3 having the same shape.
6, a rectangular colored region 34 (shown by oblique lines in the figure) having a width corresponding to the width of the mounted component 13S and having a length corresponding to the land interval is formed. When the component is correctly placed on the upper side, as shown in FIG. 4, the coloring region 34 is completely overlapped and hidden under the component 13S.

The printed circuit board 10T to be inspected is also manufactured in the same procedure as the reference printed circuit board 10S, and the description thereof is omitted here.

Returning to FIG. 1, the XY table section 14 includes an XY table 19 on which the printed circuit boards 10S and 10T are fixed, and an XY table 19 based on a control signal from the processing section 16. And two pulse motors 17 and 18 for driving the printed circuit board. The printed circuit board 10S or 10T fixed on the XY table 19 by the chuck mechanism 20 is imaged by the imaging unit 15 while being illuminated by the illumination unit 12. .

The illumination unit 12 includes a ring-shaped white light source 52 that is turned on / off or light-controlled based on a control signal from the processing unit 16, and the white light from the white light source 52 hits the coloring region 34. Then, reflected light having a higher color signal value than the coloring area 34 is generated and the light is captured by the imaging unit 15, while the white light impinges on the component 13S or 13T, the reflection according to the color intensity of the component. The light is taken into the imaging unit 15.

The imaging unit 15 includes a color television camera 21 positioned above the illumination unit 12, and light from the printed circuit board 10S or 10T is converted into three primary color signals R, G, and B by the color television camera 21. The data is converted and supplied to the processing unit 16.

In this case, when each of the printed circuit boards 10S and 10T is illuminated by the illumination unit 12 and the white light hits the colored area 34, the colored area 34 is reflected strongly by chromatic reflection (here, for example, red light).
Therefore, even when the ground color of the printed circuit boards 10S, 10T is brown, and the color of each of the components 13S, 13T mounted on these printed circuit boards 10S, 10T is brown or black,
Focusing on the portion of the color signals R, G, and B output from the imaging unit 15 corresponding to the scanning line a of the red color signal R as shown in FIG. The signal level is higher than the signal levels of other parts.

If the components 13S and 13T are correctly mounted on the coloring region 34 as shown in FIG. 4 (A), the coloring region 34 is hidden under the component and does not receive white light. There is no strong color reflection, so that the signal level of the red color signal R drops to the signal level of the red color signal R of the component 13S or 13T as shown in FIG. 4 (C).

FIG. 5 shows a specific example of a component mounting state in the coloring area 34. FIG. 5A shows a proper mounting state in which the component 13S or 13T is overlaid on the coloring area 34,
FIGS. 5B, 5C, and 5D show a state in which the component 13S or 13T is displaced in either direction, and a part of the coloring area 34 is exposed. Therefore, FIG. 5 (B) (C) (D)
When the component 13S or 13T in the state is irradiated with white light, strong color reflection occurs in the exposed portion of the coloring area 34, and a high-level red color signal R is detected. Therefore, by detecting the position, shape, number, area, and the like of the region where the signal is generated, the nature (horizontal displacement, vertical displacement, rotation, and the like) of the mounting failure and its degree can be qualitatively and quantitatively automatically detected.

FIG. 6 shows an example in which a coloring area 34 corresponding to the planar shape of the parts 13S, 13T is formed between three rectangular lands 37, 38, 39. FIG. 6 (B) and 6 (C) show an improper component mounting state in which a positional shift has occurred, respectively.

7 and 8 show an example in which the coloring area 34 is set to be larger than the planar shape of the components 13S and 13T. FIGS. 7 (A) and 8 (A) show an appropriate component mounting state. 7 (B) (C) (D) and FIGS. 8 (B) (C)
Indicates an improper component mounting state in which displacement has occurred. Also in this case, as in the previous example, by detecting the high-level red color signal R, the nature of the mounting failure can be qualitatively and quantitatively automatically identified.

When focusing on the color signals of other colors (here, for example, a green color signal G) among the color signals R, G, and B output from the imaging unit 15, the lands 35 and 36 and the component 13S (13T)
Has a value corresponding to the green intensity of the reflected light from the substrate, as shown in FIG. 4 (B). In FIG. 4 (A),
Reference numerals 40 and 41 denote electrodes of a component having a metallic luster, and reference numeral 42 denotes a white polarity mark. The signal level of the green color signal G shown in FIG. 40, 41, the component 13S (13T), and the polarity mark 42 have different values according to the respective colors, and the signal waveform has an uneven shape.
FIG. 3B shows the signal level of the green color signal G for the coloring area 34, and the signal level in this area is lower than the signal levels of the lands 35 and 36.

By checking the signal level of such a red color signal R, it is possible to detect a component mounting defect (dropout or displacement),
If the signal level of the green color signal G is checked, the type of the component, the position of the electrode and the polarity mark, etc. can be read.

In each of the above embodiments, only the example in which the component 13S (13T) is a square component and the shape of the coloring area 34 is set to a rectangle is shown. Needless to say, the shape of the coloring area 34 can be set to an arbitrary shape other than a rectangle.

Returning to FIG. 1, the processing unit 16 includes an A / D conversion unit 23, a memory 24,
Teaching table 25, image processing unit 26, judgment unit 22, XY
It comprises a stage controller 27, an imaging controller 32, a CRT display unit 28, a printer 29, a keyboard 30, a control unit (CPU) 31, and the like. In a teaching mode, color signals R, G, B is processed to extract the characteristic parameters of each part 13S and the coloring area 34 on the board to create a judgment data file.In the inspection mode, the color signals R, G, B for the inspected printed circuit board 10T
To extract the characteristic parameters of each component 13T and the coloring area 34 on the board to create a data file to be inspected. Then, the inspected data file is compared with the judgment data file, and based on the comparison result, the inspected printed circuit board 10 is inspected.
It is inspected whether or not the predetermined component 13T is mounted on the T without being dropped or displaced.

When the color signals R, G, and B are supplied from the imaging unit 15, the A / D conversion unit 23 converts the color signals into digital signals and outputs the analog signals to the control unit 31. The memory 24 includes a RAM and the like, and is used as a work area of the control unit 31. The image processing unit 26 performs image processing on the image data supplied via the control unit 31 to create the inspection target data file and the determination data file,
These are supplied to the control unit 31 and the determination unit 22.

The teaching table 25 is provided with a floppy disk device and the like.When the teaching data file is supplied from the control unit 31 during teaching, it is stored.When the control unit 31 outputs a transfer request during inspection, the The determination data file is read out accordingly and supplied to the control unit, the determination unit 22, and the like.

The determination unit 22 compares the determination data file supplied from the control unit 31 at the time of inspection with the data file to be inspected transferred from the image processing unit 26, and determines whether the component mounting state of the inspected printed circuit board 10T is good. And outputs the result of the determination to the control unit 31.

The imaging controller 32 includes an interface for connecting the control unit 31, the illumination unit 12, and the imaging unit 15, and the like, and controls the illumination unit 12 and the imaging unit 15 based on the output of the control unit 31.
The XY stage controller 27 includes a control unit 31 and the XY stage.
An interface for connecting to the table unit 14 is provided, and the XY table unit 14 is controlled based on the output of the control unit 31.

The CRT display unit 28 includes a cathode ray tube (CRT), and when image data, a determination result, key input data, and the like are supplied from the control unit 31, these are displayed on a screen. When the determination result or the like is supplied from the control unit 31, the printer 29 prints out the determination result in a predetermined format.
The keyboard 30 has various keys necessary for inputting operation information, data relating to the reference printed circuit board 10S, data relating to the components 13S on the reference printed circuit board 10S, and information and data input from the keyboard 30. Is supplied to the control unit 31.

The control unit 31 includes a microprocessor and the like,
It operates according to the procedure shown in FIG.

First, when inspecting a new printed circuit board 10T to be inspected, the control unit 31 performs the operation shown in FIG. 9 (B) in step 1 (indicated by “ST1” in the figure) of the main flowchart shown in FIG. 9 (A). Call the teaching routine. Then, in step 2 of this routine, the respective sections of the apparatus are controlled to turn on the illumination section 12 and the imaging section 15 and the imaging conditions and data processing conditions are adjusted. In step 3, the reference print is performed on the XY table section 14. Check whether the substrate 10S is set.

If the reference printed circuit board 10S is set on the XY table section 14, the process proceeds to step 4, where the control section 31
After controlling the Y table section 14 to position the reference printed circuit board 10S, the image pickup section 15 causes the reference printed circuit board 10S to image. The three primary color signals R,
G and B are A / D converted by the A / D converter 23, and the conversion result is stored in the memory 24 in real time.

Next, the control unit 31 transfers the red image data from the memory 24 to the image processing unit 26 in step 5, and the image processing unit 26 binarizes the red image data with an appropriate threshold. First, a silhouette image of the coloring area 34 is extracted. In this case, if the coloring area 34 is completely hidden under the part, no silhouette image is extracted. Next, in step 6, green image data is transferred from the memory 24 to the image processing unit 26, and each component is used by using the green image data.
The 13S image is extracted. In the next step 7, the control unit 31
Controls the image processing unit 26 to identify the position of the electrode 40 and the position of the polarity mark 42 of each part 13S by checking the brightness of each part (such as an electrode) of the green image of each part 13S. If necessary, the brightness of the three primary colors can be obtained by using the red, green, and blue image data to obtain more detailed information.

In step 8 thereafter, the control unit 31 creates a determination data file necessary for inspecting the inspected printed circuit board 10T based on the silhouette image and the identification result in step 7, and stores this in the teaching table 25. After the storage, the teaching routine is terminated.

Next, when the mode is shifted to the inspection mode, the control unit 31 calls the inspection routine shown in FIG. 9C in step 9 of the main flowchart. Next, in step 10 of this inspection routine, the date data of the day and the ID number (identification number) of the printed circuit board 10T to be inspected are taken in from the teaching table 25 and the keyboard 30, and the judgment data file is read out from the teaching table 25, and this is read. It is supplied to the determination unit 22.

Thereafter, the control unit 31 prepares the imaging conditions and the data processing conditions, and then checks in step 11 whether the printed circuit board 10T to be inspected is set on the XY table unit 14.

If step 11 is "YES", the control unit 31 extracts the silhouette image of the coloring area 34, the extraction of the green image of each component 13T, the After the identification of the polarity marks is sequentially performed, a data file to be inspected is created in step 16 based on the silhouette image and the identification result in step 15. Next, in step 17, the control unit 31 determines the inspection data file as a determination unit.
Then, the inspection data file is compared with the judgment data file, and the inspection printed circuit board 10T is
It is determined whether or not all of the predetermined components 13T are mounted without dropping or displacement, and in a proper orientation.
Supply them to the display unit 28 and print 29 to display them,
Also print out.

FIG. 10 shows another embodiment of the substrate inspection apparatus used to carry out the present invention.

The apparatus example shown in the figure supplies a reference printed circuit board 10S and a printed circuit board 10T to be inspected on a belt conveyor section 43, and inspects the boards when these boards are conveyed to a position below the illumination section 12 and the imaging section 15. Is implemented. The operation of the belt conveyor unit 43 is controlled by a conveyor controller 44.

The imaging unit 15 includes a light distributor 45 for dividing light from the printed circuit boards 10S and 10T into three light beams, and red, green, and blue filters 46 for filtering light emitted from the light distributor 45.
a, 46b, and 46c, and three line sensors 47a, 47b, and 47c for receiving light from each filter and converting the light into an electric signal. The output of each line sensor is This is provided to the D conversion unit 23.

This embodiment is for supplying the inspected printed circuit boards 10T to the substrate inspection position below the imaging unit 15 one after another by the belt conveyor unit 43 for high-speed inspection, and in order to respond to such a demand for high-speed processing. Three line sensors 47a, 47b, and 47c are used as the imaging unit 15. In FIG. 10, each configuration other than the above is the same as that of the first embodiment of FIG. 1, and the corresponding components are denoted by the same reference numerals and description thereof will be omitted.

FIG. 11 shows still another embodiment of the substrate inspection apparatus for carrying out the present invention.

In this embodiment, the imaging unit 15 includes a light distributor 48 for dividing light from the printed circuit boards 10S and 10T into three light beams, and red, green, and blue light for filtering light emitted from the light distributor 48. It is composed of filters 46a, 46b, 46c, and three monochrome television cameras 50a, 50b, 50c for receiving light from each filter and converting them into electric signals. In the case of this embodiment, By replacing the color television camera 21 in the first embodiment with these monochrome television cameras 50a, 50b, 50c, the manufacturing cost of the apparatus is reduced. Note that
In FIG. 11, each configuration other than the above is the same as that of the first embodiment in FIG. 1, and the corresponding components are denoted by the same reference numerals and description thereof will be omitted.

In the first and third embodiments, the XY table 14
Are driven in both the X and Y directions to position the printed circuit boards 10S and 10T.For example, the table unit is not movable in the Y direction, and the illumination unit 12 and the imaging unit 15 are movable in the X direction. None, table part is fixed table and none, lighting part
The design can be changed as appropriate, for example, by making the imaging unit 12 and the imaging unit 15 movable in both X and Y directions.

FIG. 12 shows still another embodiment of the substrate inspection apparatus for carrying out the present invention.

In the example of the apparatus shown in the figure, the reference printed circuit board 10S and the inspected printed circuit board 10T
And inspects the board when the board is conveyed to a position below the illumination unit 12 and the imaging unit 15.

In the case of this embodiment, a ring-shaped strobe light source 51 that instantaneously generates white light is used as the illumination unit 12, and the printed circuit board 10 on which the imaging unit 15 is moving under the strobe illumination.
It is configured to capture S and 10T to generate a still image.

In addition, to inspect the moving printed circuit boards 10S, 10T,
Not limited to the above strobe lighting method, for example, an imaging unit
By using a color television camera with a shutter function as 15, the moving printed circuit boards 10 </ b> S and 10 </ b> T may be imaged to generate an instantaneous still image.

In the embodiment of FIG. 12, the other components are the same as those of the above-described embodiments, and the corresponding components are denoted by the same reference numerals and description thereof will be omitted.

<Effect of the Invention> As described above, the present invention applies white light to a board on which a component is mounted after a paint that gives a high color signal value is applied to a portion where the component contacts the board at the component mounting position on the board surface. This board is imaged while being illuminated, and the component mounting state on the board is inspected based on the reflected light from the component mounting position. Is irradiated with white light, so that it is possible to read out various information on the component from the reflected light and perform a more detailed inspection. Further, according to the present invention, the white light is emitted instantaneously or the component mounting position is imaged instantaneously.
The same inspection can be performed on the board during the transfer. Further, in the invention according to claim 4, while irradiating visible light to a substrate coated with a paint that gives a high luminance signal value of reflected light to a portion where the component contacts the substrate, this substrate is imaged, and the component mounting on the image is performed. By determining the mounting state of the component using the reflected light information of the visible light from the position, it is possible to provide a board inspection apparatus capable of determining the mounting state of the component and various pieces of information on the component in detail.

[Brief description of the drawings]

FIG. 1 is an explanatory view showing a board inspection apparatus for carrying out the present invention, FIG. 2 is a perspective view showing a manufacturing process of a printed board, and FIG. 3 is a diagram showing a relationship between a colored region and a signal waveform of a color signal. FIG. 4 is an explanatory diagram showing the relationship between components on a colored region and the signal waveform of the color signal. FIGS. 5 and 6 are plan views showing the component mounting state in the colored region, and FIG. And FIG. 8 is a plan view showing a component mounting state with respect to a colored area of another embodiment, FIG. 9 is a flowchart showing an operation procedure of the board inspection apparatus, and FIGS. 10 to 12 are other embodiments of the board inspection apparatus. FIG. 13 is an explanatory view showing an example of a conventional board inspection apparatus, FIG. 14 is a front view showing a reference printed board, and FIG. 15 is a conventional board inspection method using an ultraviolet fluorescent substance. FIG. 10S, 10T Printed circuit board 13S, 13T Parts 12 Illumination unit 15 Imaging unit 16 Processing unit 34 Colored area

Claims (4)

(57) [Claims] 1. A board inspection method for processing data obtained by capturing an image of a board and inspecting a component mounting state on the board, the method comprising: After the paint giving the color signal value is applied,
A board inspection method, wherein a board on which components are mounted is imaged while irradiating the substrate with white light, and a component mounting state on the board is inspected based on reflected light from a mounting position of the components. 2. The method according to claim 1, wherein the irradiation of the component mounting board with white light is performed instantaneously. 3. The board inspection method according to claim 1, wherein the imaging of the component mounting board is performed instantaneously. 4. An apparatus for processing data obtained by imaging a substrate and inspecting a component mounting state on the substrate, wherein a high luminance of reflected light at a portion where the component contacts the substrate at a component mounting position on the surface. Light irradiating means for irradiating visible light to a substrate coated with a paint giving a signal value; imaging means for imaging a substrate under a state where visible light is irradiated by the light irradiating means; and imaging by the imaging means Detecting means for detecting reflected light information of visible light due to application of the coating material at a component mounting position on the image of the board, and determining means for determining a component mounting state using a detection result by the detecting means. Substrate inspection device provided.