JP2536127B2 - Board inspection equipment - Google Patents

Description

The present invention relates to a board inspection device used for inspecting a mounting state of a component mounted on a board.

<Prior Art> For example, in order to inspect whether or not the mounting state of a surface-mounted component on a board is good, conventionally, visual inspection is performed.
This visual inspection determines the solubility, short circuit, and poor continuity. However, in such a visual inspection, the occurrence of an inspection error is unavoidable, the judgment result varies depending on the inspector, and the inspection processing capacity is limited.

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

FIG. 7 shows an example of an automatic inspection device capable of detecting three-dimensional shape information. The apparatus shown in the figure irradiates the soldering portion on the substrate 2 with the slit light 1 from the laser light source to generate the optical cutting line 3 which is distorted along the surface shape on the surface of the substrate 2 including the soldering portion. To do. This light cutting line 3
Is reflected by the imaging device 4, and the three-dimensional shape of the soldered part is detected by checking the distortion state of the imaging pattern.

However, in the case of this inspection method, only the shape information of the portion irradiated with the slit light 1 is obtained, and it is difficult to grasp the three-dimensional shape of the other portions.

As a method of solving this problem, by irradiating the surface of the soldered part with light having different incident angles and capturing the pattern of each reflected light image of the soldered part, the orientation of the curved surface element of the soldered part can be determined. There is a way to detect. This method focuses on the fact that when a light beam of a fixed pattern is applied to the inspection target, the pattern of the reflected light beam is deformed according to the three-dimensional shape of the inspection target. It is to estimate.

FIG. 8 is a diagram for explaining the principle of this method, and shows the positional relationship between the detection system including the light projecting unit 5 and the image capturing unit 6 and the soldering site 7 to be inspected.

In the figure, when a light beam 8 is projected from the light projecting unit 5 onto the surface of the soldered portion 7 at an incident angle i, a reflected light beam 9 at an angle i '(= i) is incident on the image pickup unit 6 located right above. To be detected. As a result, it is detected that the curved surface element of the soldering portion 7 illuminated by the light flux 8 is oriented at an angle of i with respect to the reference plane 10. Therefore, the soldering part 7 consisting of a number of curved elements oriented in different directions
On the other hand, when light is projected by a plurality of light projecting devices having different incident angles, a group of curved surface elements corresponding to the respective incident angles are detected by the image pickup section 6, whereby each curved surface element of the soldered part 7 is detected. It is possible to detect what kind of orientation each has, that is, what the surface texture of the soldered portion looks like.

Further, if the light projecting unit 5 projects a light beam 8 having an incident angle of 2Δi from i + Δi to i−Δi, the imaging unit 6 detects a reflected light beam 9 having a width corresponding to the width. become. That is, in this case, it is possible to detect a curved surface element having an angle of inclination of i + Δi to i−Δi with respect to the reference plane 10.

Further, as shown in FIG. 9, if the light projecting section 5 is an annular light source installed horizontally with respect to the reference plane 10, the surface of the soldering portion 7 is relative to the axis perpendicular to the reference plane 10. No matter what the rotation angle is, the light projection part 5 and the soldering part 7
Since the distance between and is constant and the orientation of the curved surface element in the direction of the rotation angle is eliminated, only the angle of inclination with the reference plane 10 is detected.

Further, as shown in FIG. 9, if the light projecting portion 5 is constituted by a plurality of annular light sources 11, 12, 13 having different incident angles to the soldered portion 7, the light fluxes 14, 15, 16 of the respective light sources are As described above, the curved surface element having the orientation corresponding to the incident angle can be detected in detail.

Now, the heights of three annular light sources 11, 12, 13 with a radius of r _n (n = 1, 2, 3) with respect to the reference plane 10 are h _n (n = 1, 2, 3)
If it is installed horizontally at the position of, the incident angles of the light fluxes 14, 15, 16 on the soldered portion 7 are i _n (n = 1, 2, 3), respectively, and the inclination angles at the soldered portion 7 are i. Each curved surface element that is _n can be detected by the imaging unit 6.
At this time, since the size of the curved surface element is sufficiently smaller than the total optical path length from each light source 11, 12, 13 to the image pickup section 6 through the surface of the soldering portion 7, let's detect the incident angle, that is, by the following equation. The angle of inclination of the curved surface element is defined.

As a method for detecting the appearance of the soldered portion based on the above principle, a method using a white light source for each of the light sources 11, 12 and 13 has been proposed (JP-A-61-293657). In this inspection method, in order to distinguish the reflected light images from the three light sources 11, 12, and 13 having different incident angles with respect to the soldered part, the light sources 11, 12, and 13 are respectively timed at different timings. It is turned on and off.

<Problems to be Solved by the Invention> However, in the case of such a board inspection apparatus, when the surface of the soldered portion is a gentle slope, the reflected light is directed upward and guided to the image pickup unit 6, When the surface of the soldering portion is a steep slope (angle of 45 ° or more with respect to the substrate surface), the reflected light does not enter the image pickup unit 6, and the property inspection of the soldering portion becomes difficult.

The present invention has been made in view of the above problems, and provides a substrate inspection apparatus capable of inspecting the mounting state of each component in detail by enabling inspection even if the surface shape of the inspection portion is steep. The purpose is to do.

<Means for Solving the Problems> In order to achieve the above-mentioned object, in the invention of claim 1, the light projecting portion including an annular light source for irradiating the mounted component on the substrate with light, and the optical axis are the above-mentioned. A first imaging unit that is arranged so as to match the center line of the annular light source, and that images the light reflected from the surface of the inspection site along the center line, and the optical axis is set outside the annular light source. A second image capturing section that captures light reflected from the surface of the inspection site to the outside of the annular light source, and captured images of the reflected light obtained by the first and second image capturing sections. The board inspection apparatus is configured with a judgment processing unit that judges the quality of the mounting state of the component based on the pattern.

Further, in order to obtain more detailed information on the mounting state, a plurality of annular light sources constituting the light projecting portion are provided, and each light source is instantaneously operated in a time series to obtain different incident angles with respect to the components. In addition, the image obtained by each of the first and second image pickup units is taken into the determination processing unit in accordance with the irradiation timing.

<Operation> When light is emitted from the annular light source to the mounted components on the board, the light is reflected along the center line of the annular light source when the surface of the soldering portion is a gentle slope, and The reflected light image is detected by the first imaging unit.

On the other hand, when the surface of the soldered portion is a steep slope, the light is reflected to the outside of the annular light source, and the reflected light image is the second light.
Will be detected by the image pickup unit.

In this case, if the light projecting section is composed of a plurality of annular light sources that instantaneously operate in a time series, more detailed angle information of the soldered portion can be obtained, and highly accurate board inspection can be performed.

Therefore, according to the present invention, automatic inspection is possible regardless of whether the surface of the inspection portion is a gentle slope or a steep slope.

<Embodiment> FIGS. 1 and 2 show the principle of a substrate inspection apparatus according to an embodiment of the present invention.
And a light projecting portion 24 in which is horizontally arranged at a predetermined height position with respect to the reference surface 52, and one unit which is located on the center line 45 of the annular light source 28 and directly above the inspected component 21T. A second image pickup unit 25 composed of the monochrome television camera 32 and a total of four monochrome television cameras 53 to 56 arranged at respective positions at 90 degrees and equal angles around the component 21T to be inspected. A detection system is configured by the image pickup unit 57 and.

The annular light source 28 of the light projecting unit 24 is for irradiating the component 21T with white light, and the monochrome television camera 32 in the first imaging unit 25 corresponds to the incident angle of the light flux 46 by the light source 28. It is possible to detect a gently inclined curved surface element having a different orientation, and in the monochrome television camera 55 in the second imaging unit 57, a steeply inclined curved surface having an orientation corresponding to the incident angle of the light beam 47 from the light source 28. The element can be detected. In the illustrated example, the other monochrome television cameras 53, 54, 56 of the second image pickup section 57 are not involved in the detection of the curved surface element in the figure.

FIG. 3 shows the overall structure of a substrate inspection device using the above detection system.

This substrate inspection apparatus, the characteristic parameters (judgment data) of the inspection region of each component 21S on the reference substrate 20S obtained by imaging the reference substrate 20S, and the substrate 20T to be inspected Compare the characteristic parameters (inspected data) of the inspection area of each component 21T on the inspected substrate 20T,
It is for inspecting whether each of these components 21T is correctly mounted and soldered, and includes an X-axis table section 22, a Y-axis table section 23, a light projecting section 24, and a first imaging section.
25, the second imaging unit 57, the determination processing unit 26, and the like are included as its components.

The X-axis table unit 22 and the Y-axis table 23 each include a motor (not shown) that operates based on a control signal from the determination processing unit 26. The image pickup unit 25 is moved in the X direction, and the Y-axis table unit 23 moves the conveyor 27 supporting the substrates 20S and 20T in the Y direction.

The substrates 20S and 20T are imaged by the first and second imaging units 25 and 57 while receiving the irradiation light from the light projecting unit 24.

The light projecting unit 24 is provided with an annular light source 28 for generating white light based on a control signal from the determination processing unit 26 and irradiating the inspection object at a predetermined incident angle, and the white light emitted from the light source 28 is emitted. Light is projected onto the substrates 20S and 20T, and the reflected light images are obtained by the first and second imaging units 25 and 57 and converted into electric signals.

Next, the first image pickup section 25 is arranged above the light projecting section 24 and is located on the center line of the light source 28.
The upward reflected light from the substrate 20S or 20T is converted into a video signal by the monochrome television camera 32 and supplied to the determination processing unit 26.

The second image pickup unit 57 is provided with a total of four monochrome television cameras 53, 54, 55, 56 which are located around the substrate 20S or 20T in four directions around the substrate 20S or 20T.
The reflected light from T to the side is converted into a video signal by the monochrome television camera located in that direction and supplied to the determination processing unit 26.

The determination processing unit 26 includes an A / D conversion unit 33, a memory 38, a teaching table 35, an image processing unit 34, a determination unit 36, an X / Y table controller 37, an imaging controller 31, a CRT display unit 41, a printer.
42, keyboard 40, floppy disk device 43, control unit (CP
U) 39, etc., in the teaching mode, the mounting position of each component 21S, the type and mounting direction of the mounting component, and the inspection area are detected from the reference board 20S, and the video signal of the reference board 20S is detected. Is processed to detect the image pickup pattern in the inspection area of each component 21S having a good soldering state, generate characteristic parameters, and create a determination data file. Further, the determination processing unit 26, in the inspection mode, processes the video signal of the inspected substrate 20T, detects a similar imaging pattern for the inspection region of each component 21T on the substrate, generates characteristic parameters, and outputs the inspected data. Create a file. Then, the data file to be inspected is compared with the determination data file, and based on the comparison result, it is automatically determined whether the soldered portion is good or bad for the predetermined component 21T on the substrate 20T to be inspected.

When the video signal is supplied from each of the first and second image pickup units 25 and 57, the A / D conversion unit 33 performs analog / digital conversion of the video signal and outputs it to the control unit 39. The memory 38 includes a RAM and the like and is used as a work area of the control unit 39. The image processing unit 34 performs image processing on the image data supplied via the control unit 39 to create the inspection data file and the judgment data file, and supplies these to the control unit 39 and the judgment unit 36.

The teaching table 35 is controlled by the control unit 39 during teaching.
When the judgment data file is supplied from, it is stored, and when the control unit 39 outputs a transfer request at the time of inspection,
The determination data file is read out in response to this request and is supplied to the control unit 39, the determination unit 36, and the like.

The determination unit 36 compares the determination data file supplied from the control unit 39 at the time of inspection and the inspection data file transferred from the image processing unit 34, and determines whether the soldering state of the inspection substrate 20T is good or bad. The determination result is output to the control unit 39.

The image pickup controller 31 includes a control unit 39, a light projecting unit 24, and a first unit.
The light source 28 of the light projecting unit 24 is provided based on the output of the control unit 39, including an interface for connecting the first and second image pickup units 25 and 57.
And the video output of the monochrome television cameras 32, 53 to 56 of the first and second imaging units 25 and 57 are controlled.

The X, Y table controller 37 includes an interface for connecting the control unit 39 to the X-axis table unit 22 and the Y-axis table 23, and based on the output of the control unit 39, the X-axis table unit 22 and the Y-axis table unit 23 are connected. Control.

The CRT display unit 41 includes a cathode ray tube (CRT), and when image data, determination results, key input data, and the like are supplied from the control unit 39, this is displayed on the screen. When the determination result and the like are supplied from the control unit 39, the printer 42 prints out the determination result in a predetermined format. The keyboard 40 is provided with various keys necessary for inputting operation information, data relating to the reference board 20S and the reference 20T to be inspected, and the information and data input from this keyboard 40 are supplied to the control unit 39. .

The control unit 39 includes a microprocessor and the like,
The operations in teaching and inspection are controlled according to the procedure (FIGS. 4 and 5) described below.

First, at the time of teaching, the control unit 39 controls each part of the device at the start time of FIG.
The first and second imaging units 25 and 57 are turned on, and the imaging conditions and data processing conditions are adjusted. Next, the operator operates the keyboard 40 to register the name of the board to be taught in step 1 (indicated by "ST 1" in the figure), and after key-inputting the size of the board, the next step 2 Then, the reference board 20S
Is set on the Y-axis table 23 and the start key is pressed. Then, in step 3, the origin of the reference board 20S and the upper right and lower left corners are imaged by the first imaging unit 25, and the actual size of the board 20S is input according to the position of each point. The X-axis table unit 22 and the Y-axis table unit 23 are controlled based on the input data to position the reference substrate 20S at the initial position.

The reference board 20S is one in which a predetermined component 21S is properly soldered to the component mounting position to form a good mounting state, and when the reference board 20S is positioned at the initial position, the next step In step 4, the first imaging unit 25 is the reference substrate 20.
The areas on S are sequentially imaged, and the mounting position of the component and the type of the mounted component are taught.

Thus, when the teaching procedure of the component position and the type is completed, in the next step 5, the teaching procedure for setting the inspection areas for all the components is sequentially executed by using the reference board 20S.

When the teaching for setting the inspection area is completed, the procedure proceeds to the teaching procedure for the characteristic parameters.

First, at step 6, the counter n for counting the number of substrates of the control unit 39 is initialized to "1", and at next step 7, the operator sets the first reference substrate 20S to the Y-axis table unit 2
3 is set and the start key of the keyboard 40 is pressed, the control unit 39 controls the X-axis table unit 22 and the Y-axis table unit 23 based on the component position data obtained by the previous teaching, and The visual fields of the TV cameras 32, 53 to 56 are sequentially positioned on the respective parts and an image is taken.

The video signal obtained by each imaging operation is A / D converted by the A / D converter 33, and the conversion result is stored in the memory 38 in real time. Then, the control unit 39, after extracting each land area in the inspection area of each component obtained by the above teaching, the image data is transferred from the memory 38 to the image processing unit 34, and in this image processing unit 34. The normal soldering state of each land is detected as an imaging pattern by binarizing the image data with an appropriate threshold value, and the characteristics of these patterns are calculated as a characteristic parameter (step 8).

When the extraction of a plurality of types of characteristic parameters for each component is completed for the first reference board 20S, the board is unloaded and the counter n is incremented by 1 to obtain the second reference board 20S.
S is designated (step 10), and the characteristic parameter extraction processing is executed in the same procedure as described above.

When the extraction process of the characteristic parameters for the predetermined number (n) of reference boards 20S is completed in this way, step 9
The determination is “YES” and the process proceeds to step 11. Step 11
Then, in order to obtain an average feature amount for each component, the control unit 39 statistically processes each feature parameter for the n reference boards 20S to obtain average value data, and the determination data is based on this average value data. A file is created, this is stored in the teaching table 35, the data is corrected as necessary, and the teaching is finished.

When the teaching is completed as described above, this board inspection apparatus is ready for automatic inspection of the inspected board 20T after soldering.

Thus, the operator shifts to the inspection mode shown in FIG. 5, selects the name of the substrate to be inspected in steps 1 and 2, and performs the operation of starting the substrate inspection.

The next step 3 is the board 20 to be inspected to the board inspection apparatus.
The supply of T is checked, and if it is "YES", the conveyor 2
7 operates, the substrate 20T to be inspected is carried into the Y-axis table portion 23, and the substrate inspection is started (steps 4 and 5).

In step 5, the control unit 39 controls the X-axis table unit 22 and the Y-axis table unit 23 to position the visual fields of the color television cameras 32, 53 to 56 with respect to the first component 21T on the inspected board. Imaging is performed, each land area in the inspection area is automatically extracted, characteristic parameters of each land area are calculated, and an inspection data file is created. Then, the control unit 39 transfers the inspected data file to the determination unit 36, compares the inspected data file with the determination data file, and determines the quality of soldering for the first component 21T.

Such an inspection is repeatedly executed for all the components 21T on the inspected substrate 20T. As a result, if there is a soldering defect, the defective component and the content of the defect are displayed on the CRT display unit 41 or printed on the printer 42. After being tested, inspected board 20T
Are carried out from the inspection position (steps 7 and 8).

Thus, when the same inspection procedure is executed for all the inspected substrates 20T, the determination in step 9 becomes "YES", and the substrate inspection is completed.

FIG. 6 shows another embodiment of the detection system in the board inspection apparatus.

In the embodiment shown in the figure, three light sources 28, 29, 30 having different diameters are horizontally arranged at different height positions with their center lines aligned as the light projecting section 24. Light source 28,29,30
The components 21S and 21T are irradiated with white light at different incident angles by performing instantaneous operation (strobe light emitting operation) in time series. As a result, the first and second imaging units 25 and 57 generate images of the components 21S and 21T corresponding to the irradiation timing of the light sources, and the images are sequentially captured by the determination processing unit 26 and processed. Will be.

According to the second embodiment, it is possible to obtain more detailed angle information of the soldered portion as compared with the first embodiment, and it is possible to perform a highly accurate board inspection.

Note that the configuration of the determination processing unit 26 and each procedure of teaching and inspection in the second embodiment are similar to those in the first embodiment, and the description thereof is omitted here.

<Effects of the Invention> As described above, according to the present invention, the light reflected from the surface of the inspection site along the center of the annular light source is imaged by the first imaging unit and reflected from the surface of the inspection site to the outside of the annular light source. Since the light is picked up by the second image pickup unit, the reflected light image can be generated and inspected by the second image pickup unit even if the surface of the inspection is steep, and the mounting state of each component on the board Can be inspected in detail.

Further, according to the second aspect of the invention, since the light projecting portion is composed of a plurality of annular light sources, detailed angle information can be obtained for the inspection site, and high-precision board inspection can be performed.

[Brief description of drawings]

FIG. 1 is an explanatory view of the principle of a substrate inspection apparatus according to an embodiment of the present invention, FIG. 2 is a plan view showing a camera arrangement in the substrate inspection apparatus of the present invention, and FIG. 3 is an embodiment of the present invention. FIG. 4 is an explanatory diagram showing the overall structure of the substrate inspection apparatus, FIG. 4 is a flowchart showing a teaching procedure, FIG. 5 is a flowchart showing an inspection procedure, and FIG. 6 is an explanatory diagram showing another embodiment of the present invention. FIG. 7 is a principle explanatory diagram showing a conventional automatic inspection device, and FIGS. 8 and 9 are principle explanatory diagrams showing the principle of the automatic inspection device. 20T: substrate, 21T: component 24: light projecting unit, 25: first imaging unit 26: determination processing unit 28-30 ... annular light source 32: monochrome TV camera 53-56: monochrome TV camera 57 …… Second imager

Claims (2)

(57) [Claims] 1. A substrate inspection apparatus for inspecting a mounting state of a component mounted on a substrate, comprising: a light projecting unit including an annular light source for irradiating the component with light; and an optical axis of the annular light source. Is arranged so as to coincide with the center line of the inspection site, and a first imaging unit that images the light reflected along the center line from the surface of the inspection site, and the optical axis is set outside the annular light source. A second image capturing unit that captures light reflected from the surface of the inspection site to the outside of the annular light source, and captures captured images of the reflected light obtained by the first and second image capturing units and uses the image pattern. A board inspection apparatus comprising: a judgment processing unit that judges whether the mounting state of components is good or bad. 2. An inspection apparatus for inspecting a mounting state of a component mounted on a substrate, comprising: a plurality of annular light sources for instantaneously irradiating the component with different incident angles in time series. And a first image pickup unit that is arranged so that the optical axis thereof coincides with the center line of each of the annular light sources and that captures light reflected from the surface of the inspection site along the center line. A second imaging unit that is arranged with an optical axis set outside the annular light source and that captures light reflected from the surface of the inspection site to the outside of the annular light source; and at each timing of instantaneous irradiation by each light source. Corresponding first
1. A substrate inspection apparatus comprising: a determination processing unit that captures a captured image of reflected light obtained by each of the first and second imaging units and determines whether the mounting state of a component is good or bad based on the image pattern.