JPH01260586A - Substrate inspecting device - Google Patents

Abstract

PURPOSE:To easily perform the accurate inspection of soldering by projecting light which illuminates a limited belt area including plural pins on a component to be inspected in a prescribed direction, and discriminating the normal/defective condition of the soldering of each pin by finding the brightness of the image of each pin in the image of the component to be inspected image-picked up under the above irradiation. CONSTITUTION:The light illuminating the limited belt area including the plural pins (8a-8d) is projected on the component 6 to be inspected in the prescribed direction, and an image pickup device 3 image-picks up the component 6 to be inspected at a prescribed position under the irradiation, and outputs the image to an arithmetic controller 14, and the arithmetic controller 14 finds the brightness of the image at each pin position for an input image. When proper soldering on the pins (8a-8d) are applied on a land part, a soldering fillet forms a proper three-dimensional curved surface, therefore, the image pickup device 3 detects a high luminance point by reflected light, and the image at the pin position is brightened, and the arithmetic controller 14 judges that the soldering is performed properly. In such a way, it is possible to perform the accurate inspection of the soldering easily.

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention relates to a printed wiring board #Fy, (hereinafter simply "
The present invention relates to a board inspection device used to inspect whether or not components mounted on a board (referred to as a soldering board) are properly soldered.
The present invention relates to a board inspection device for inspecting the quality of soldering on a part of a run 1 of each pin of a surface mount component called a "SOP component".

<Prior art> Conventionally, this type of board inspection apparatus has a method of irradiating an I/-the beam onto an inspection part of an inspection part and inspecting the quality of soldering using the reflected light,
A method has been proposed in which the quality of soldering is inspected by illuminating the entire device from two directions and binarizing and composing the defective images under each illumination.

<Problems to be solved by the invention> However, in the single-handed method, it is necessary to scan the laser beam 1 and guide the laser beam to each pin position of the inspection part, and moreover, it is necessary to scan the laser beam 1 and guide the laser beam to each pin position of the inspection part. In order to set the position, it is necessary to perform processing such as detecting the amount of deviation of the component mounting position and correcting the observation position.

In addition, the latter method requires processing such as cutting out and compositing the inspection area from the image of the inspection part obtained by the imaging device, and there is also the problem that it is necessary to consider the influence of parts outside the inspection area. there were.

This invention was made in view of the above problem, and involves irradiating light that illuminates a limited band-shaped area including a plurality of pins onto a part to be inspected from a predetermined direction to observe the part to be inspected. To provide a new board inspection device that realizes accurate hike inspection without requiring processing such as correcting the observation position or cutting out the inspection 'imp area, and without taking in information on unnecessary parts. With the goal.

<Means for Solving the Problems> In order to achieve the second object, the present invention provides a method for soldering a part of the run of each pin for a surface mount component having a large number of pins mounted on a board. In a board inspection device for inspecting the attachment state, a device for irradiating a test component with light that illuminates a limited band-shaped area including a plurality of pins from an obliquely upper position in a direction orthogonal to the protruding direction of the pins. a light projecting device, an imaging device for capturing an image of the inspection part under illumination by the light projecting device at a diagonally upward position opposite to the protruding direction of the pin, and each image of the test component obtained by the imaging device; The apparatus is equipped with an arithmetic and control unit for determining the brightness of the image of the pin position and sequentially determining the quality of the hand die reflex for the land portion of each pin based on the brightness.

In addition to the above-mentioned configuration, the present invention also includes a method in which light for illuminating a limited band-shaped area including a plurality of pins on the inspection component is illuminated from an obliquely upper position in a direction opposite to the protruding direction of the pins.
A second light projecting device is added for the purpose of It provides a function to detect the reference pin position from the image.

Furthermore, in this invention, in addition to the above-mentioned configuration, the arithmetic and control device determines the brightness of the image at each pin position for the image of the inspection part obtained by the imaging device under illumination by each of the second projecting devices. A function is provided to sequentially determine the quality of soldering to the land portion of each pin based on the brightness.

<Operation> When a board on which a component is mounted is given, the light projection device is activated, and light illuminating a limited band-shaped area including a plurality of pins is irradiated onto the component to be inspected from a predetermined direction. Under this illumination, the imaging device images the inspection component at a predetermined position and outputs the image to the arithmetic and control device. In this case, since the illumination area is limited to the necessary minimum, there is no need to consider the influence of other components. The arithmetic and control unit determines the brightness of the image at each pin position for the input image. If each pin is properly soldered to the land, the solder fillet will form a unique three-dimensional curved surface due to the surface tension when melted, and the high brightness point will be detected by the reflected light from the imaging device. . Therefore, the image at that pin position becomes bright, and the arithmetic and control unit determines that the soldering condition is good. If the soldering is defective, the solder fillet 1 having a unique three-dimensional curved surface will not be formed, and no high-brightness point will be detected by the imaging device.

In a configuration having a second light projecting device, when a component mounting board is provided, the second light projecting device is first activated.
Light that illuminates a limited band-shaped area including a plurality of pins is irradiated onto the inspection component from a predetermined direction. When the inspected part is imaged under this illumination, contrast occurs between the root portion of each pin and the pan cage portion, making it easy to detect the root portion of each pin. Therefore, the arithmetic and control unit uses the image of this part to detect the reference pin position, and specifies the inspection site by setting a window for each of the following pin positions.

Furthermore, the arithmetic and control device determines the brightness of the image at each pin position for the image of the inspection component obtained under illumination by the second light projector. If each pin is correctly soldered to the land portion, the reflected light from the solder fillet will not match the direction of the imaging device. Therefore, the image at that pin position becomes dark, and the arithmetic and control unit determines that the soldering is good. If the soldering is poor, the illumination light will be reflected towards the imaging device and the image at that pin location will become brighter.

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

In the illustrated example, a measurement table 1 consisting of an XY child table
An inspection object 2 (a plurality of surface-mounted components mounted on a board) is placed on top of the inspection object 2, and an imaging device 3 and a first... Second light projecting devices 4 and 5 are provided. The inspection part 6 is
As shown in FIG. 2, the component body 7 is covered with a black package, and on both sides there are four pins 8a to 8 each with metallic luster.
d are arranged at predetermined intervals.

The tip of each pin is soldered onto the land of the board, and when properly soldered, the solder fillet
9 forms a unique three-dimensional curved surface due to the effect of surface tension, as shown in FIG. In the example of FIG. 2, the first pin 8a and the third pin 8a. The fourth pins 8c and 8d are in a good soldered state, but the second pin 8b is in a poor soldered state with the solder fillet 9 missing.

The first light projecting device 4 is disposed at an obliquely upper position in a direction perpendicular to the direction in which the pins protrude (for example, at an angular position of 45°), and has four wooden pins 8a to 8d on one side with respect to the inspection part 6. Light is irradiated to illuminate a limited band-shaped region 1.0 (indicated by diagonal lines in FIG. 2).

FIG. 5 is a plan view of this band-shaped region]O, and this region 10 includes the entire four-wood pins 8a to 8d on one side and a part of the component body 7 on the base side of the pin. It is.

The reason why the illumination range is limited to the vicinity of the pin in this way is to eliminate the influence of other components and eliminate noise from parts unnecessary for inspection.

Next, the imaging device 3 is disposed at an obliquely upper position (for example, at an angular position of 45°) in a direction opposite to the protruding direction of the pins 8a to 8d, and the inspection component 6 is illuminated with illumination 1ζ by the first light projecting device 4. A second light projecting device 5 to be described later
The inspection component 6 is similarly imaged under the illumination by the above.

Fig. 3 shows the relationship between the imaging device 3 and the illumination light 11 when the first pin 8a is viewed from directly above (X direction), and Fig. 4 shows the relationship between the first pin 8d when viewed from the side (X direction). Imaging device 3 in case
and the relationship between the illumination light 11 and the illumination light 11 are shown.

In FIG. 3, the illumination light 11 (not shown with numbers 1 to 7) advances along the X direction, and the imaging device 3 is positioned 2 facing the Y direction. At this time, the illumination light indicated by number 5 is specularly reflected toward the imaging device 3 on the surface of the solder fillet 9 that is inclined at 45 degrees with respect to the X direction.

In addition, in FIG. 4, the illumination light 11 not indicated by numbers 1 to 6 is
The imaging device 3 is located in a direction making an angle of 45° with the Y direction. At this time, the illumination light indicated by number 3 is specularly reflected toward the imaging device 3 on the surface of the solder fillet 1-9 having an inclination of 22.5 degrees with respect to the Y direction.

Note that in FIGS. 3 and 4, the light 12 indicated by numbers 1' and 6' is the reflected light of the illumination light 11 indicated by numbers 1 to [j on the surface of Hunter Fileno [-9].

Since the hank fillets 71 to 9 thus form a three-dimensional curved surface, there is always a point in the soldering soy 1 hole 97 where light is generated once per year, as described above, toward the imaging device 3. Moreover, since the solder surface is a mirror surface, that point on the solder fillet 9 is detected as a high brightness point every time. Therefore, the presence or absence of the bank fillet 9 can be determined by checking the presence or absence of high brightness points on the image.

FIG. 6 shows an image 6' of the inspection part 6 obtained by the imaging device 3. In this image 6', the first. Third. Each image 8a' of each fourth pin.

In 8c' and 8d', a high brightness point 13 appears at the corresponding position of the solder fillet 1-, or no high brightness point appears in the image 81]' of the missing second pin of the solder fillet 1-.

Returning to FIG. 1, the imaging device 3. 1st. Each of the second light projecting devices 4.5 and the measurement table 1 are connected to an arithmetic and control unit 14 consisting of a microphone and a computer CPU.
The image capturing operation of the image capturing device 3 is performed by decoding and executing the program.
The light emitting operation of the light projecting devices 4 and 5, the movement of the measurement table, etc. are controlled by control signals, and the image 1) is taken in from the image pickup device 3 and stored in the image pickup device 16. Executes various calculations and processes related to inspection of the hanger.

In FIG. 1, a monitor section 1.8 is for monitoring images obtained by the imaging device 3, and a display section 1.8 and a printing section 19.
is for displaying or printing the test results.

The arithmetic control device 14 and the inspected parts 6 obtained by the imaging device 3
For image 6' (see Figure 6), each pin (first qNA
Find the average value of the brightness of images 8a' to 8d' in part),
Depending on the magnitude of the value, the quality of soldering to the land portion of each pin 8a to 8d is sequentially determined. In this embodiment, in order to prevent objects other than the solder fillet 1-, such as lands, from being detected as high-brightness points, the brightness of each pin image 8a' to 8d' obtained by the imaging device 3 is adjusted. Based on the average value, a deviation value and a peak value are determined, and each of these values is compared with the determination criteria, and if a predetermined condition is satisfied, it is determined that solder fillet No. 1 is present.

In other words, if the solder surface is in poor condition, sufficient reflected light may not be obtained and it may be incorrectly determined that there is no solder fillet, even if the solder solder is in good condition if only the average value of brightness is used. There is a risk that the decision will be made. Therefore, the stability and reliability of the judgment is improved by adding the brightness deviation value and peak value to the judgment criteria.

FIG. 7(1) shows the brightness distribution characteristics of an image when a high brightness point due to a solder fillet is detected. In the figure, the horizontal axis represents brightness and the vertical axis represents the number of pixels, and in this case, the deviation value is small and the peak value is large.

On the other hand, the seventh [F(2)L;l] shows the distribution characteristics when diffuse reflection other than the solder fillet is detected,
In this case, the deviation value will be large and the peak value will be small.

Next, as shown in FIG. 8, the second light projecting device 5 is disposed at an obliquely upper position (for example, at a 45° angle position) in a direction opposite to the protruding direction of the pins 8a to 8d of the inspection component 6. , the inspection component 6 is irradiated with light that illuminates a limited strip area 10 (indicated by diagonal lines in the figure) including four pins 8a to 8d on one side. Here, this band-shaped area 10 is made to coincide with the illumination range by the first floodlighting device 4 (shown in the fifth part), and within this area 10 there are all four wooden pins 8a to 8d on one side and the pins. A part of the component body 7 on the root side is included.

FIG. 9 shows the relationship between the imaging device 3 and the illumination light 20 when the first pin 8a is viewed from the side (X direction), and the illumination light 20 at this time is reflected by the surface of the solder fillet 9. However, the reflected light is not directed toward the imaging bag N3.

On the other hand, in Fig. 10, the second pin 8b is directly beside (X direction)
The relationship between the imaging device 3 and the illumination light 20 when viewed from above is shown, and the illumination light 20 at this time is the solder fillet 9
Since there is no light, the reflected light is reflected by the end face and land portion of the pin 8b and is directed toward the imaging device 3.

Thus, in the arithmetic and control unit 14, each pin 8a to 8d
The presence or absence of the solder fillet 9 can be determined by determining the brightness of the image for the tip of the solder fillet 9 and comparing it with the determination criteria.

FIG. 11 shows an image 6'' of the inspection component 6 taken by the imaging device 3 under illumination by the second floodlight device 5. In this image 6'', the 1st, 3rd, and 3rd. Each image 8a'' of each fourth pin tip.

8c''+'8d'' is bright, but the image 8b'' of the second pin is dark.

The twelfth time shows a situation in which the inspection component 6 is imaged under illumination by the second light projecting device 5 to inspect the presence or absence of solder bridges. A bridge 21 is generated between the pin 8b and the third pin 8c.

FIG. 13 shows the relationship between the imaging device 3 and the illumination light 20 when the second pin 8b is viewed from the side (X direction). Since the bridge 21 forms a curved surface due to surface tension when melted, a portion of the illumination light 20 is specularly reflected toward the imaging device 3 . Moreover, since the solder surface is a mirror surface, this bridge 21 is visible in the high brightness area 21' on the image.
(shown in Figure 14). Therefore, in the arithmetic and control unit 14, the bridge 21 is
It is possible to determine the presence or absence of

Furthermore, in the arithmetic and control device 14 of this embodiment, the second
When the imaging bag W3 images the inspection component 6 under illumination by the light projector 5, the position of the first pin 8a serving as a reference is detected from the image.

FIGS. 15 and 16 both show the procedure for detecting the first pin 8a by the arithmetic and control unit 14 and the subsequent procedure for inspecting the soldered state.

Now, when the inspection part 6 is conveyed by the conveyance mechanism and set on the measurement table 1 at the star 1- point in FIG.
The measurement table 1 moves in the X direction and the Y direction to position the inspection component 6 at a position below the imaging device 3 and the light projecting devices 4 and 5. Next step] (In the figure, rsTIJ
), the second light projecting device 5 is activated and irradiates the inspection component 6 with light, and the four wooden pins 8. on the J1 side are activated. ]~8
d and a part of the component body 7 at the base of the pin is illuminated, and under this illumination, the imaging device 3
is activated to take an image of the inspection part 6, and the image is taken into the image memory 16.

Next, in step 2, the arithmetic and control unit 14 adjusts the image position of the component body 7 by utilizing the fact that the package of the component body 7 is black and the contrast I- occurs between the pins 8a to 8d. By setting a window W+ (see FIG. 16(1)) and checking the images within this window W, the root positions of the pin images 8a'' to 8d'' are determined. In this case, if the brightness within the window Wl is clearly dark, 1, the test is terminated as undeterminable (step 3).

In the next step 4, the arithmetic and control unit 14 places Win 1 to W at the root position of the pin image (in this case, 8 b'').
2 (see 16C(2)), find the center of gravity of the image in this window W2, and use this as the pin position. In step 5, the arithmetic and control unit 14 checks whether or not there is an image 80'' of an adjacent pin on the pin arrangement pitch in order to confirm that the image is not noise (see FIG. 16 (3)). ). If there is no pin image on the pin pitch, step 6 becomes "NO", and the process returns to step 4 to detect the pin position again.

If step 6 is "'Y [43"], in order to detect the image 8a of the first pin which becomes the reference in the next step 7, move the win I/tsu W2 to the left by the pin pitch,
Check the brightness in window W7 (16th
(See Figure (4)). If window W2 becomes bright,
This pin is selected as a candidate for the first pin image 8a'', the window W2 is further moved to the left, and the brightness is checked in the same way.

If the inside of the window W2 is dark, the original pin is determined to be the first pin image 8a''.

Next, in step 8, iJ, the picture of the first pin (jJ 8 a
” From the root position and pin length, find the tip position of the pin image, and insert window W3 (161m
(5)) is set, the average value of the brightness within the window W3 is determined, and it is determined whether the value is equal to or less than the determination criterion. Similarly, images 8 b of the second to fourth pins,
8c and 86'', the brightness within window W3 is also determined and compared with the judgment standard. If there is a pin with brightness below the judgment standard, step 9 becomes 'YES' and that pin is is stored as a candidate for poor soldering (step 10). Furthermore, if there is no pin with brightness below the determination standard, the result of step 9 becomes 'NO', and it is stored that there is no candidate for a defect to be rejected (step 11).

Next, in step 12, a window W4 (16th
1m (see 6)), the average value of the brightness within the window W4 is determined, and it is determined whether the value is equal to or greater than the determination criterion. Similarly, for other pins, window W4
Find the brightness within and compare it with the criteria. As a result, if the brightness of the judgment standard "2" is detected, step 13 becomes "YES" and the fact that there is a bridge is memorized, and if the brightness exceeding the judgment standard is not detected, Step 13 becomes "NO", and a note is made that there is no bridge (steps 14 and 15).
.

Next, in step 16, the first light projecting device 4 is activated to irradiate the inspection component 6 with light, and the four wooden pins 8a to 8 on one side are
While illuminating a limited strip area 10 including 8d,
The imaging device 3 operates under this illumination to take an image of the inspection component 6, and the image is taken into the image memory 16.

Next, in step 17, the arithmetic and control unit 14 sets a window W3 (see FIG. 16 (7)) at the leading edge position of the image for each pin listed as a defective candidate, and the average brightness within the window W3 is set. value, deviation value, and peak value, and determine whether all of them satisfy the criteria. In the same way, other defect candidates are compared with the determination criteria, and if there is a pin that does not meet the determination criteria, step 18 becomes "'YES", and an output indicating that there is a soldering defect is performed (step 19). ). If there are no pins that do not satisfy the determination criteria and no blemishes or jigs occur, step 18 becomes ``No'' and an output indicating that there is no defective soldering is performed (step 20).

Note that in the above embodiment, for images captured under illumination by the first light projector 4, the brightness, etc., are checked only for pins that are defective candidates; however, the present invention is not limited to this.
All pins may also be checked.

<Effects of the Invention> As described above, the present invention irradiates a part to be inspected with light that illuminates a limited band-shaped area including a plurality of pins from a predetermined direction, and obtains an image of the part to be inspected taken under this illumination. Since the brightness of the image of each pin is determined to determine whether the soldering of each pin is good or bad, the observation position is different from the conventional method of irradiating a laser beam or illuminating the entire surface from two directions. Accurate soldering inspection can be achieved without the need for processing such as modifying the parts or cutting out the inspection area.Moreover, since the illumination area is limited to the minimum necessary, there is no need to take into account the influence of other parts. Nor.

In addition, if it is equipped with a second floodlight device that emits the same strip-shaped illumination from another direction, it is possible to detect the reference pin position, and in addition, it is possible to detect the reference pin position. The soldering of each pin can be comprehensively inspected from different angles for each image obtained under illumination, and highly accurate judgment data can be obtained, achieving the remarkable effects of achieving the purpose of the invention.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram showing a schematic configuration of a board inspection device according to an embodiment of the present invention, and FIG. 2 is a perspective view showing a state in which an inspection component is imaged under illumination by a first floodlight device. Third
The figure is a plan view showing the relationship between the imaging device and the illumination light when the pin is viewed from directly above, FIG. 4 is a front view showing the relationship between the imaging device and the illumination light when the pin is viewed from the side, and FIG. Fig. 5 is an explanatory diagram showing the illumination range by the floodlighting device, Fig. 6 is a plan view showing an image captured under illumination by the first floodlighting device, and Fig. 7 shows the brightness distribution of the image of the pin. Explanatory diagram, Figure 8 is the second
Fig. 9 is a perspective view showing a state in which an inspection component is imaged under illumination by a floodlight device, and Fig. 9 is a front view showing the relationship between the imaging device and illumination light when a well-soldered pin is viewed from the side. , Fig. 10 is a front view showing the relationship between the imaging device and illumination light when a pin with poor soldering is viewed from the side, and Fig. 11 shows an image taken under illumination by the second floodlight device. FIG. 12 is a plan view, and FIG. 12 is a perspective view showing a state in which an inspection component having a bridge is imaged under illumination by a second floodlight device;
Fig. 13 is a front view showing the relationship between the imaging device and illumination light when a pin with a bridge is viewed from the side, and Fig. 14 is an image in which the bridge appears, taken under illumination by the second floodlighting device. FIG. 15 is a flowchart showing the inspection procedure for the soldered state, and FIG. 16 is an explanatory diagram showing the inspection procedure for the soldered state. 3... Imaging device 4... First light projecting device 5...
...Second light projector 6...Inspection parts 8a to 8d...
・Pin 10... Strip area 14... Arithmetic control device

Claims (1)

[Claims] 1. In a board inspection device for inspecting the soldering state of each pin to the land portion of a surface mount component having a large number of pins mounted on a board, a plurality of pins are mounted on the component to be inspected. A light projecting device for illuminating a limited band-shaped area including the pins of a book from a diagonally upward position in a direction perpendicular to the direction in which the pins protrude; an image pickup device for taking an image of the inspection part under illumination by the above-mentioned floodlight device; 1. A board inspection device comprising: an arithmetic control device for sequentially determining whether soldering to a land portion is good or bad; 2. In a board inspection device for inspecting the soldering state of each pin to the land portion of a surface mount component having a large number of pins mounted on a board, the limitation is that the test component includes multiple pins. a first light projecting device for illuminating the strip-shaped area where the inspection part is inspected from an obliquely upper position in a direction perpendicular to the protruding direction of the pin; and a limited strip-shaped area including a plurality of pins for the inspection part a second light projecting device for emitting light for illuminating the pin from a diagonally upper position in a direction opposite to the protruding direction of the pin; An imaging device for capturing an image of the inspection component under illumination by each floodlighting device, and a reference pin position is detected from an image of the inspection component obtained by the imaging device under illumination by a second floodlighting device. In order to determine the brightness of the image of each pin position from the image of the inspection part obtained by the imaging device under illumination by the floodlight device 1, and to sequentially determine whether the soldering to the land portion of each pin is good or bad based on the brightness. A board inspection device comprising: an arithmetic and control unit; 3. In a board inspection device for inspecting the soldering state of each pin to the land portion of a surface mount component having a large number of pins mounted on a board, the limitation is that the test component includes multiple pins. a first light projecting device for illuminating the strip-shaped area where the inspection part is inspected from an obliquely upper position in a direction perpendicular to the protruding direction of the pin; and a limited strip-shaped area including a plurality of pins for the inspection part a second light projecting device for emitting light for illuminating the pin from a diagonally upper position in a direction opposite to the protruding direction of the pin; An imaging device for capturing an image of the inspection component under illumination by each floodlighting device, and a reference pin position is detected from an image of the inspection component obtained by the imaging device under illumination by a second floodlighting device. 1. Determine the brightness of the image at each pin position for each image of the inspection component obtained by the imaging device under illumination by each of the second projectors, and determine whether the soldering to the land portion of each pin is good or bad based on the brightness. 1. A board inspection device comprising: an arithmetic and control device for sequentially determining .