JPH03189544A - Substrate inspecting device - Google Patents

Abstract

PURPOSE:To efficiently execute inspection with high accuracy by changing the lens magnification of an image pickup device in an optimum state after discriminating resolution necessary for the inspection concerning each inspected part. CONSTITUTION:The zoom lens 45 of an image pickup part 25 exists in order to change the lens magnification of a color television camera 32 in accordance with the resolution necessary for the inspection. When the inspected part is a minute soldered part, the inspection with high resolution where the lens magnification is made high is executed and when the inspected part is a large soldered part, the inspection with wide visual field where the lens magnification is made low is executed. Then, a decision part 36 compares decided data file supplied from a control part 39 with the data file to be inspected which is transferred from an image processing part 34 and the propriety of the soldered state is decided concerning a substrate to be inspected 20T and the decided result is outputted to the control part 39. An image pickup controller 31 controls to adjust the light quantity of the respective light sources 28-30 of a light projecting part 24 based on the output of the control part 39, to keep the mutual balance of the light output of each hue of the camera 32, and to change the lens magnification of the lens 45.

Description

[Detailed Description of the Invention] <Industrial Application Field> This invention is a board inspection method used for inspecting a board on which components are mounted, such as missing components, two positions, and the quality of soldering. Regarding equipment.

<Conventional technology> Conventionally, parts mounted on a board have been inspected by visual inspection. For example, in the case of soldering, the condition of soldering is checked, that is, the presence, amount, and solubility of solder.

Short circuits, poor continuity, etc. are determined by this visual inspection.

However, in such a visual inspection method, the occurrence of inspection errors is unavoidable, the judgment results vary depending on the person conducting the inspection, and there is a limit to the inspection processing capacity.

Therefore, in recent years, various automatic inspection devices that can automatically perform this type of inspection have been proposed.

By the way, the surface shape of a soldering part is a three-dimensional shape with three-dimensional expansion, and in order to inspect this, it is essential to be able to detect three-dimensional shape information.

FIG. 5 shows an example of an automatic inspection device that satisfies this condition, in which a plate-shaped slit light 1 is irradiated from a light source such as a laser onto a soldering area on a board 2. By irradiating this slit light 1, a light cutting line 3 that is distorted along the three-dimensional shape is generated on the surface of the substrate 2 including the soldering part, and a reflected light image of the light cutting line 3 is generated. Imaging device 4
By taking an image and checking the distortion state of the imaged pattern, the three-dimensional shape of the soldering part is detected.

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 way to solve this problem, soldering is performed by irradiating light with different incident angles onto the surface of the part and capturing the pattern of each reflected light image of the part. There are methods for detecting orientation.

This method focuses on the fact that when a fixed pattern of light beams is applied to an inspection object, the pattern of the reflected light beam is deformed according to the three-dimensional shape of the inspection object, and the shape of the inspection object can be determined from the deformation pattern. It is estimated.

FIG. 6 is a diagram explaining the principle of this method, and shows the positional relationship between a detection system consisting of a light source 5 and an imaging section 6, and a soldered part 7 to be inspected.

In the figure, when a light beam 8 is projected from a light source 5 onto the surface of a soldering part 7 at an incident angle i, a reflected light beam 9 at an angle of V (=i) enters the imaging unit 6 located directly above and is detected. Ru. This means that it has been detected that the curved surface element of the soldering area 7 illuminated by the light beam 8 is oriented at an angle of i with respect to the reference plane 10. Therefore, when soldering is made up of a large number of curved elements oriented in different directions, if multiple light projectors with different incident angles are used to project light onto the part 7, a group of curved elements corresponding to each incident angle will be imaged. 6, and as a result, it is possible to detect the orientation of each curved surface element of the soldered portion 7, that is, the surface texture of the soldered portion.

In addition, the light source 5 has an incident angle of 2Δ from i+Δi to i−Δi.
If a beam 8 having a width of i is projected, a reflected beam 9 having a width corresponding to the width will be detected by the imaging unit 6. That is, in this case, it is possible to detect a curved surface element whose inclination angle with respect to the reference plane 10 ranges from i+Δi to i−Δi.

Furthermore, if the light source 5 is an annular light source installed horizontally to the reference plane 10 as shown in FIG. Even with such a rotation angle, the distance between the light source 5 and the soldering part 7 is constant, and the orientation of the curved surface element in the rotation angle direction is erased, so only the inclination angle formed with the reference plane 10 is detected. That will happen.

Further, as shown in FIG. 7, when the light source 5 is soldered, a plurality of annular light sources 11, 12.
3, the light beams 14, 15 .
As described above, a curved surface element having an orientation corresponding to an angle of incidence of 16 can be detected in greater detail.

Now, three annular light sources 11, 12, and 13 with radius r (where n=1.2.3) are placed at a height relative to the reference plane 10 and positioned at (n=1.2.3). If installed horizontally, the angle of incidence of each light beam 14, 15, 16 on the soldering part 7 will be in (n=1.2.3), and the inclination angle at the soldering part 7 will be i. The imaging unit 6 can detect each curved surface element. At this time, since the size of the curved surface element from each light source 11, 12, 13 through the surface of the soldering part 7 to the imaging part 6 is sufficiently small compared to the total optical path length, the incident angle, that is, the detection What is necessary is to determine the inclination angle of the curved surface element to be used.

Based on the above principle, a method using a white light source for each of the above-mentioned lights ix1, 12°13 has been proposed as a method for inspecting the appearance of soldering parts (Japanese Patent Laid-Open No. 61-29365
No. 7). In this inspection method, in order to mutually identify the reflected light images from the three light sources 11, 12, 13 having different incident angles to the part, the soldering is carried out at different timings for each light source 11, 12, 13. Light it up with
The lights are turned off again.

However, this method requires a memory to store each image obtained at different light emitting timings, a calculation device to process these images as the same visual field image, and a computer to instantaneously turn on each light emitting body. A lighting device and the like are required, which is technically complicated, and this also poses problems in terms of cost and reliability.

Therefore, in order to solve the problems of this time sharing system all at once, the inventor of this invention recently proposed a new board inspection device. The details of this board inspection device will be described later, but the soldering type has a light projecting part that irradiates the surface of the part with light of different hues at different angles of incidence, and the soldering type uses the light reflected from the surface of the part. An imaging unit that captures an image on each hue side at a position directly above the component, and processing that detects the properties of each curved surface element of the soldering part from the imaging pattern obtained by this imaging unit and determines whether the soldering is good or bad. It consists of
The light projecting section uses, for example, three annular light sources that respectively generate red light, green light, and blue light.

The imaging unit uses a color television camera based on the principle of additive mixing of the three primary colors of red, green, and blue.The built-in three-color separation optical system separates the incident light into the three primary colors, and then separates the incident light into the three primary colors. is being detected.

According to the above board inspection equipment, when soldering is performed by irradiating red light, green light, and blue light from each light source at different incident angles to the soldering part, the soldering is performed by irradiating red, green, and blue light from the surface of the part. The optical images are simultaneously separated and detected by an imaging section located directly above the optical images.

FIG. 8 shows the cross-sectional form of the solder 44 when the soldering is good, when a component is missing, and when there is insufficient solder, and the imaging patterns in each case, a red pattern, a green pattern, and a blue pattern. It shows the relationship with the patterns in a list, and since there are clear differences between any hue patterns, it is possible to judge the presence or absence of parts and the quality of soldering.

Incidentally, in recent years, parts have become smaller and smaller, and the size of the parts soldered onto the boards of parts has also become smaller. Conventionally, in order to automatically inspect soldering parts, the resolution of board inspection equipment has been required to be around 100 μm, which is said to be the resolution of the human eye, but as parts become smaller, there is a need to further increase this. There is.

Currently, the pin spacing of integrated circuit components (RC) is 0.5 m.
m, and the size of the surface mount chip component is 1.6
xo, a mm or 1. OXo, 5 mm, but these dimensions are becoming smaller due to miniaturization of parts.

As the soldering parts become smaller, the resolution of the board inspection device must be increased as necessary to 70 μm, 50 μm, 30 μm, etc., thereby ensuring the desired inspection accuracy. And to increase this resolution,
This increases the lens magnification of the color television camera.

<Problem to be solved by the invention> However, increasing the lens magnification inevitably results in a reduction in the field of view for the board to be imaged, so when automatically inspecting the entire board surface, the number of fields of view to be imaged is significantly reduced. It will increase.

In this type of board inspection, the time required to automatically inspect one component-mounted board consists of the time required for image processing and the time required to move the imaging field of view, but usually the latter time is required to move the field of view. Since this takes up a large portion of the time, an increase in the number of fields of view lengthens the inspection time, which is a factor that hinders the practical use of board inspection equipment.

This invention was made with a focus on the above-mentioned problem, and after imaging the inspection area and determining the required resolution, it automatically changes the lens magnification depending on the determination result, thereby achieving high precision. It is an object of the present invention to provide a new board inspection device that can efficiently perform inspections.

<Means for Solving the Problems> In order to achieve the above object, the board inspection apparatus of the present invention includes an annular light source that irradiates light of different hues to inspection parts on the board at different angles of incidence; An imaging device capable of changing lens magnification for capturing reflected light from a surface in each hue side, a determining means for determining the resolution required for inspection from an input image obtained under a standard lens magnification, and a determining means. A control means for executing control for changing the lens magnification of the imaging device to an optimal state according to the determination result obtained by the method, and a judgment means for determining the mounting state of the component from the imaging pattern obtained under the optimal lens magnification. I'm letting you do it.

<Operation> The lens magnification of the imaging device is changed to the optimal state after determining the resolution required for inspection for each inspection site, so if the inspection site is a minute area, high-resolution inspection can be performed with increased lens magnification. If the area is large, a wide field of view inspection is performed with a lower lens magnification. Therefore, even if the number of fields of view increases in high-resolution inspection and the time required for inspection increases, the degree of increase is suppressed to the minimum required by wide-field inspection, so that high-precision inspection can be carried out efficiently.

<Embodiment> FIG. 1 shows a schematic configuration of a board inspection apparatus according to an embodiment of the present invention.

The illustrated example of the board inspection apparatus includes each component 21 on the positioning board 2O3 obtained by imaging the positioning board 20S.
Comparing the parameters (determination data) of the inspection area of No. 3 with the parameters (inspection data) of the inspection area of each component 21T on the substrate 2OT to be inspected obtained by imaging the substrate 20T to be inspected, This is for inspecting whether each of these parts 21T is correctly mounted and soldered. Y-axis table section 23. Light projecting section 24° imaging section 25. The entire configuration includes a processing section 26 and the like.

The X-axis table section 22 and the Y-axis table section 23 are each equipped with a motor (not shown) that operates based on a control signal from the processing section 26, and the drive of these motors causes the X-axis table section 22 to operate as an imaging section. 25 in the X direction, and the conveyor 27 on which the Y-axis table section 23 supports the substrates 203, 20T is moved in the Y direction.

These substrates 20S and 20T are imaged by the imaging unit 25 while receiving irradiation light from the light projecting unit 24.

The light projection unit 24 includes three annular light sources 2B and 29 that generate red light, green light, and blue light respectively based on the control signal from the processing unit 26 and irradiate the inspection target at different angles of incidence.
．． 30, and the substrates 205, 20 are illuminated by the mixed light of the three primary colors emitted from these light sources 28, 29, 30.
T is projected, and an image of the reflected light is obtained by the imaging section 25 and converted into an electrical signal. In this embodiment, each of the light sources 28,
29.30 is red with white light source.

Although a structure in which green and blue filters are covered is used, it is of course not limited to such a structure as long as it generates light of each hue of the three primary colors.

Moreover, this light projecting unit 24 illuminates the substrate 203.20 under its illumination.
Each light a2s, 29.30
It is designed so that when the light of each hue emitted by the light is mixed, it becomes completely white light. That is, each light source 28.29.
30 is constituted by a light emitting body that emits light in a red light spectrum, a green light spectrum, and a blue light spectrum having a wavelength-to-wavelength emission energy distribution such that white light is produced by color mixing, and is irradiated from each light source 2B, 29.30. Just as red light, green light, and blue light mix to form white light,
The imaging controller 31 allows the amount of light of each hue to be adjusted.

Next, the imaging section 25 consists of a color television camera 32 located above the light projecting section 24, and an electric zoom lens (for example, J6X11REA manufactured by Canon Corporation) attached to this camera 32. Said substrate 2O3
Alternatively, the reflected light from 20T is converted into a three-primary color signal R by a three-primary color separation optical system built into the color television camera 32.
The signal is converted into 1G and 1B and supplied to the processing section 26.

The zoom lens 45 is used to change the lens magnification of the color television camera 32 depending on the resolution required for inspection. If the inspection area is a large soldering area, a wide field of view inspection will be performed with a lower lens magnification.

Figures 3 and 4 show QFP46, which is a type of LSI.
This figure shows the external appearance of a package part 47, in which a large number of lead pins 48 are provided around a rectangular package part 47.

In this type of component, the interval ρ between the lead pins 48 is 0.
In the case of 65 mm, the width W of the pin 48 is 0.3 nu
n, the width W of the pads 49 on the substrate is 0.36 mm, and the spacing between the pads 49 is 0.29 mm. If the resolution of the image is 40 μm, the width W of the pads 49 is 9 pixels on the image. becomes.

On the other hand, the distance between lead pins 48! is 0.5 rtm, the width W of the pin 48 is 0.2 am, the width W of the pad 49 on the substrate is 0.2 mm, and the spacing between the pads 49 is 0.3 mm. Image resolution is 40μm
Then, the width W of the pad 49 is 5 pixels on the image,
Inspection accuracy is not sufficient. Therefore, by increasing the resolution to 20 μm, the width W of the pad 49 becomes 10 pixels,
It becomes possible to perform inspection with accuracy equivalent to that of a case where the interval l between the pins 48 is 0.65 mm.

On the other hand, in the case where the spacing l between the lead pins 48 is 0.8 mm, the width W of the pins 48 is 0.351 mm, the width W of the pads 49 on the substrate is 0.49 mm, and the spacing between the pads 49 is 0.35 mm.
If it is 31 mm and the resolution of the image is 40 μm, the width W of the pad 49 will be 12 pixels on the image, which is more than sufficient for inspection accuracy. Therefore, the resolution is set to 5
By lowering the width W to 5 μm, the width W of the pad 49 becomes 9 pixels, which makes it possible to perform inspection with accuracy equivalent to that of a pin 48 with an interval l of 0.65 mm.

In this embodiment, the standard resolution is 40 μm and the magnification of the zoom lens 45 is set, and if the QFP 46 exists within the field of view of the color television camera 32 in this state, it is imaged and the IQ hat 49 is Extract the image. Then, the width W of the pad 49 is measured on the image, and the lens magnification of the zoom lens 45 is changed in accordance with the measurement result to set the resolution.

Returning to FIG. 1, the processing section 26 includes the A/D conversion section 33. Memory 38. Teaching table 35, image processing section 34
9 determination unit 36. X, Y full controller 37.
tH & controller 31, CRT display unit 41. Printer 42. Keyboard 40. Floppy disk device 43.
It is composed of a control unit (CPU) 39, etc., and when in the teaching mode, processes the color signals R, G, and B for the positioning board 20S, and displays red, red, and red for predetermined areas of each component 213 that are in good soldering condition. It detects each hue pattern of green and blue to create a judgment data file, and when in the inspection mode, processes the color signals R, G, and B of the board to be inspected 20T, and processes the color signals for a predetermined area of each component 21T on the board. A data file to be inspected is created by detecting each similar hue pattern.

Then, this inspection data file and the judgment data file are compared, and based on the comparison result, the inspection target board 2OT
For the above predetermined part 21T, it is automatically determined whether the soldering part is good or bad.

The A/D converter 33 receives the color signals R,
When G and B are supplied, they are converted from analog to digital and output to the control section 39. Memory 38 is RAM
It is used as a work area for the control section 39.

The image processing section 34 performs image processing on the image data supplied via the control section 39 to create the above-mentioned inspected data file and judgment data file.
Supply to 6.

The teaching table 35 is connected to the control unit 3 during teaching.
When the judgment data file is supplied from the control unit 9, it is stored, and when the control unit 39 outputs a transfer request during inspection, the judgment data file is read out in response to this request and sent to the control unit 39 and the judgment unit. 36 etc.

The determination unit 36 compares the determination data file supplied from the control unit 39 at the time of inspection with the data file to be inspected transferred from the image processing unit 34, and determines the quality of the board 2 to be inspected.
For 'OT', the soldering state is determined whether the condition is good or not, and the determination result is output to the control section 39.

The imaging controller 3■ includes an interface for connecting the control section 39 with the light projecting section 24 and the imaging section 25, and controls each light source 28, of the light projecting section 24 based on the output of the control section 39.
Controls include adjusting the amount of light of 29.30, maintaining the mutual balance of the light outputs of each hue of the color television camera 32 of the imaging unit 25, and changing the lens magnification of the zoom lens 45.

The X, Y table controller 37 includes a control section 39 and the
It includes an interface for connecting the axis table section 22 and the Y-axis table section 23, and controls the X-axis table section 22 and the Y-axis table section 23 based on the output of the control section 39.

The CR7 display section 41 is equipped with a cathode ray tube (CRT), and when image data, judgment results, key manual data, etc. are supplied from the control section 39, they are displayed on the screen. When the printer 42 is supplied with the determination result etc. from the control unit 39,
This is printed out in a predetermined format. The keyboard 40 is equipped with various keys necessary for inputting operation information, data regarding the positioning board 20S, data regarding the parts 21S on the positioning board 20S, etc., and the information and data entered from the keyboard 40 are controlled. 39.

The control unit 39 includes a microprocessor, etc.
Control operations are performed according to the test procedure shown in FIG.

First, prior to the procedure shown in the figure, teaching is performed using the positioning board 20S, and as a result, a determination data file is created and stored in the teaching table 35.

In the inspection mode, at the start point in the figure, the control unit 39 inputs the date data of the day and the ID of the substrate to be inspected ttIi 20T from the teaching table 35 and the keyboard 40.
At the same time as taking in the number (identification number), the determination data file is read from the teaching table 35 and supplied to the determination section 36.

Next, in step 1 (indicated by rsTIJ in the figure), the control unit 3
9 controls each part of the apparatus to turn on the light projecting section 24 and the imaging section 25, and also sets imaging conditions and data processing conditions. In this case, the lens magnification of the zoom lens 45 in the imaging unit 25 is initially set so that the resolution is in a standard state (here, 40 μm).

Next, when the substrate to be inspected 20, T is set on the Y-axis table section 23, the control section 39 controls the X-axis table section 22 and the Y-axis table section 23 to position the substrate to be inspected 20T. If the QFP 46 exists within the field of view of the color television camera 32 at that position, the determination in step 2 is “
YES" and the process proceeds to step 3, where the process moves to measuring the pad width W.

In this step 3, when the color television camera 32 images the substrate to be inspected 20T under standard lens magnification, the image information obtained by this imaging operation is taken into the image processing section 34, and then the control section 39 An image of the pad 49 inside is extracted and the pad width W is measured.

Step 4 determines whether the pad width W is 5 pixels or less, and Step 5 determines whether the pad width W is 10 pixels or more.
Each is determined by the control unit 39, and if step 4
If the determination is “YES”, in step 6 the control unit 39
issues an instruction to the imaging controller 31 to change the lens magnification of the zoom lens 45 and set the resolution to 20 μm. Upon receiving this instruction, the imaging controller 31 increases the lens magnification of the zoom lens 45, and then the color television camera 32 executes imaging of the target area (step 8).
). If the determination in step 4 is NO' and the determination in step 5 is "YES", the lens magnification of the zoom lens 45 is changed in step 7 and the resolution is set to 55 μm, and then the imaging operation in step 8 is performed. It will be done.

If the determination in step 5 is “No” or if there is no QFP46 within the field of view (step 2 is “NO”)
), the process moves to step 8 while maintaining the lens magnification of the zoom lens 45 in the standard state.

In the imaging operation in step 8, the three primary color signals R, G, and B are
Once obtained, these signals are converted to A/D by the A/D converter 33.
The conversion result is stored in memory 38 in real time. Next, the control section 39 causes the image data corresponding to each hue to be transferred from the memory 38 to the image processing section 34, and the image processing section 34 converts the image data of each hue into binary values using an appropriate threshold value on each hue side. to detect red, green, and blue patterns. In this case, the control unit 39
controls the image processing unit 34 to check the brightness of each part (electrode, etc.) of the imaged pattern of each part 21T, and thereby identify the position of the electrode, the position of the polarity mark, etc. of each part 21T.

After this, the control unit 39 creates a data file to be inspected based on each of the hue patterns and the identification results, and then transfers this data file to the determination unit 36, and then transfers the data file to the determination unit 36. A predetermined component 21 on the board to be inspected 20T is compared with the determination data file.
The quality of the soldering is determined based on T, and the determination results are supplied to the CRT display section 41 and printer 42,
Display these and print them out.

When the same procedure is executed for all areas on the board, the determination in step 100 becomes ``YES'', and the inspection of one board is completed.

In the above embodiment, the magnification of the zoom lens 45 is changed only for the QFP 46, but the same magnification may be changed for minute chip components.

Further, this magnification change can be applied not only in the inspection mode but also in the teaching mode.

<Effects of the Invention> As described above, the present invention irradiates different hues of light to inspection areas on a board and images the reflected light on each hue side to inspect the mounting state of components. After determining the resolution required for inspection, the lens magnification of the imaging device is changed to the optimal state, so high-resolution inspection can be performed for minute areas, and wide-field inspection can be performed for large areas. The invention achieves the purpose of the invention and has remarkable effects, such as being able to carry out highly accurate inspections efficiently.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram showing the overall configuration of a board inspection device according to an embodiment of the present invention, FIG. 2 is a flowchart showing the inspection procedure of this board inspection device, and FIG. 3 is a plan view showing the external appearance of the QFP. Fig. 4 is an enlarged plan view of the same, Figs. 5 to 7 are principle explanatory diagrams showing a conventional automatic soldering condition inspection device, and Fig. 8 is a diagram showing the quality of the soldering condition and the imaging pattern of the ideal form. FIG. 24... Light projecting section 25... Imaging section 26...
...Processing unit 28, 29.30. ...Light source 3
1... Imaging controller 32... Color TV camera

Claims (1)

[Scope of Claims] A board inspection device for inspecting the mounting state of components mounted on a board, comprising: an annular light source for irradiating light of different hues at different incident angles to inspection parts on the board. an imaging device capable of changing the lens magnification for imaging the reflected light from the substrate surface for each hue; and a determining means for determining the resolution required for inspection from an input image obtained under a standard lens magnification. A control means that executes control to change the lens magnification of the imaging device to an optimal state according to the determination result by the determination means, and a determination means that determines the mounting state of the component from the imaging pattern obtained under the optimal lens magnification. A board inspection device comprising: