Appearance inspection device and defect inspection method

Abstract

The present invention provides a technique capable of more accurately determining a solder protrusion defect in an appearance inspection apparatus that acquires an image of an inspection region of an inspection object and measures the height of a specified part in the inspection region using a height measurement device. The appearance inspection apparatus includes: a photographing unit (3) that photographs the inspection region on the inspection object (30); a height measurement unit (20) that measures the height of a specified part in the inspection region by emitting measurement light and receiving its reflected light; a moving mechanism (5) that relatively moves the photographing unit (3) and the height measurement unit (20) with respect to the inspection object; and a determination unit that determines whether there is a defect in the inspection object in the inspection region based on the image of the inspection region and information on the height of the specified part. When the measurement light emitted from the height measurement unit (20) is irradiated onto a restricted region (M) in the inspection object, the restricted determination unit makes a defect determination based on the information on the height of the specified part measured by the height measurement unit (20).

Description

Technical Field

[0001] The present invention relates to an appearance inspection device for inspecting the appearance of an object to be inspected in a manufacturing process or a distribution process, and a defect inspection method using the appearance inspection device. Background Art

[0002] In an appearance inspection device for inspecting the appearance of an object to be inspected such as a circuit board, a planar image of an inspection area in the object to be inspected is sometimes obtained and height measurement is performed. This is because defects cannot sometimes be detected only by the planar image of the inspection area. For example, when a lead 30a of a circuit component is normally soldered to a circuit board 30, as shown in (a) of Figure 11 , a solder foot 30b having an inclined surface is formed around the lead 30a. However, especially when soldering is performed using an automatic machine, as shown in (b) of Figure 11 , a solder protrusion defect sometimes occurs in which solder 30c protrudes angularly further upward from the end of the lead 30a. Such a solder protrusion defect is difficult to detect only based on the planar image of the circuit board 30, and it is necessary to measure the height of the solder portion.

[0003] Moreover, in order to efficiently measure the height of the solder portion, it is preferable that the appearance inspection device includes, in addition to an imaging device that acquires an image of the inspection area, a height measurement device that measures the height of the solder portion by irradiating the solder portion with measurement light and receiving the reflected light thereof, and measures the height of the solder portion in a non-contact manner. However, in such height measurement, when the measurement light irradiates the lead 30a and the angularly protruding solder 30c, the height of the solder portion can be accurately measured. However, when the measurement light irradiates the inclined surface of the solder foot 30b, the reflected light is further reflected by other parts of the circuit board and is sometimes received by the height measurement device as stray light. As a result, false detection of solder protrusion defects sometimes occurs.

[0004] Prior Art Documents

[0005] Patent Documents

[0006] Patent Document 1: Japanese Patent Application Laid-Open No. 2006-30094 Summary of the Invention

[0007] Problems to be Solved by the Invention

[0008] The present invention has been made in view of the above circumstances, and an object thereof is to provide a technique capable of making a more accurate defect determination in an appearance inspection device that acquires an image of an inspection area of an object to be inspected and measures the height of a specified portion in the inspection area.

[0009] Means for Solving the Problems

[0010] The present invention for solving the above problems is an inspection device, comprising: a photographing unit that photographs an inspection area on an inspection object; a height measurement unit that measures the height of a specified part of the inspection object by emitting measurement light and receiving the reflected light thereof; a moving mechanism that relatively moves the photographing unit and the height measurement unit with respect to the inspection object to change the inspection area photographed by the photographing unit and the specified part whose height is measured by the height measurement unit; and a determination unit that determines whether there is a defect in the inspection object in the inspection area based on the image of the inspection area photographed by the photographing unit and the information on the height of the specified part measured by the height measurement unit. The appearance inspection device is characterized in that it further comprises a restriction unit that restricts the determination unit from determining whether there is the defect based on the information on the height of the specified part measured by the height measurement unit when the measurement light emitted from the height measurement unit irradiates a specified restriction area of the inspection object.

[0011] In the appearance inspection device of the present invention, basically, the determination unit determines whether there is a defect in the inspection object in the inspection area based on the image of the inspection area photographed by the photographing unit and the information on the height of the specified part measured by the height measurement unit. On the other hand, when the measurement light emitted from the height measurement unit irradiates a specified restriction area of the inspection object, the determination unit is restricted from determining whether there is a defect based on the information on the height of the specified part measured by the height measurement unit. That is, for a place where, as a result of multiple reflections where the reflected light is not directly received by the height measurement unit when the measurement light is irradiated on the inspection object and is received by the height measurement unit as stray light, the information measured by the height measurement unit is restricted from being used for determining whether there is a defect. Thereby, it is possible to suppress false detection of a defect due to the reflected light of the measurement light not being received by the height measurement unit in a manner capable of measuring the height but being received by the height measurement unit as stray light.

[0012] In addition, in the present invention, it may be that the inspection object is a circuit board on which a circuit component is mounted, the restriction area includes a lead foot part, and in this lead foot part, solder forms a slope around the lead of the circuit component soldered to the circuit board.

[0013] Thereby, when the measurement light is reflected in an unexpected direction by the lead foot formed when the lead of the circuit component is soldered to the circuit board and is received by the height measurement unit as stray light, the use of the height information of the height measurement unit for defect determination is restricted, so that the accuracy of defect determination of the appearance inspection device can be improved.

[0014] In addition, in the present invention, it may also be that the inspection object is a circuit board on which circuit components are mounted, and the restricted area includes the following area: when the height measurement unit moves relative to the circuit board, this area is the area irradiated with the measurement light immediately before or immediately after the moment when the measurement light is irradiated onto the leads of the circuit components soldered to the circuit board.

[0015] Here, when the height measurement unit measures the height of the solder part while moving relative to the circuit board, immediately before or immediately after the moment when the measurement light is irradiated onto the leads, the measurement light irradiates the solder feet, and the possibility that the reflected light is received by the height measurement unit as stray light becomes high. Therefore, the area irradiated with the measurement light at this moment is set as the restricted area. When irradiating the measurement light to the restricted area, the determination of whether there is a defect is restricted based on the height information of the specified part measured by the height measurement unit. Therefore, it is possible to more reliably suppress the false detection of defects caused by stray light.

[0016] In addition, in the present invention, it may also be that there are other leads and solder foot parts adjacent to the lead irradiated with the measurement light in the direction of relative movement of the height measurement unit relative to the circuit board or in the opposite direction with respect to the restricted area. In other words, in addition to the above conditions, the restricted area may also be an area where there are other leads and solder foot parts adjacent to the lead in the direction of relative movement of the height measurement unit relative to the circuit board or in the opposite direction with respect to the restricted area. In such a case, the determination unit restricts the determination of whether there is a defect based on the height information of the specified part measured by the height measurement unit.

[0017] That is, when there are other solder parts near the solder part of the lead irradiated with the measurement light, the possibility that the measurement light reflected by the solder feet in the solder part irradiated with the measurement light is reflected again by the solder feet in the adjacent solder part and received by the height measurement unit as stray light becomes high. Therefore, in such a case, by restricting the determination unit to determine whether there is a defect based on the height information of the specified part measured by the height measurement unit, it is possible to more efficiently suppress the false detection of defects caused by stray light.

[0018] In addition, in the present invention, it may also be that a setting unit is further provided, and the setting unit automatically sets the restricted area based on the positions of the leads in the circuit board.

[0019] That is, in the present invention, as long as the position of the lead is known, the position where the solder joint exists can be estimated. Therefore, the position of the solder joint can also be estimated based on the position of the lead, and this area can be automatically set as the restricted area. Thus, it is possible to more easily set the restricted area for various circuit boards. In addition, the position of the lead in this case can be measured in advance or obtained based on the design information of the circuit board.

[0020] In addition, in the present invention, the defect may also be a solder protrusion defect where solder protrudes from the end of the lead during the soldering of the lead of the circuit component to the circuit board.

[0021] It is difficult to detect the solder protrusion defect only based on the planar image captured by the imaging unit, and the stray light caused by the reflection of the solder joint has a great influence on its detection accuracy. Therefore, by applying the present invention to the determination of the solder protrusion defect, it is possible to more efficiently suppress the false detection of defects.

[0022] The present invention may also be a defect inspection method using an appearance inspection device, which includes: an imaging unit that captures an inspection area on an inspection object; a height measurement unit that measures the height of a specified part of the inspection object by emitting measurement light and receiving its reflected light; and a moving mechanism that relatively moves the imaging unit and the height measurement unit with respect to the inspection object to change the inspection area captured by the imaging unit and the specified part whose height is measured by the height measurement unit. The defect inspection method determines whether there is a defect in the inspection object in the inspection area based on the image of the inspection area captured by the imaging unit and the information on the height of the specified part measured by the height measurement unit. The characteristic of the defect inspection method is that when the measurement light irradiates a specified restricted area of the inspection object, the determination of whether there is a defect based on the information on the height of the specified part measured by the height measurement unit is restricted.

[0023] In addition, in the present invention, it may also be that the characteristic of the defect inspection method is that the inspection object is a circuit board on which circuit components are mounted, the restricted area includes the solder joint part, and in this solder joint part, solder forms an inclined surface around the lead of the circuit component soldered to the circuit board.

[0024] In addition, in the present invention, it may also be that the characteristic of the defect inspection method is that the inspection object is a circuit board on which circuit components are mounted, and the restricted area includes the following area: when the height measurement unit relatively moves with respect to the circuit board, the area irradiated with the measurement light immediately before or immediately after the moment when the measurement light irradiates the lead of the circuit component soldered to the circuit board.

[0025] In addition, in the present invention, it may also be that the defective inspection method is characterized in that, in the direction of relative movement of the height measurement unit with respect to the circuit board or the opposite direction with respect to the restricted area, there are other leads and solder pad portions adjacent to the lead irradiated with the measurement light.

[0026] In addition, in the present invention, it may also be that the defective inspection method is characterized in that the defect is a solder protrusion defect in which solder protrudes from the end of the lead during soldering of the lead of the circuit component to the circuit board.

[0027] It should be noted that, in the present invention, the means for solving the above problems can be combined as much as possible.

[0028] Advantages of the Invention

[0029] According to the present invention, in an appearance inspection apparatus that acquires an image of an inspection area of an object to be inspected and measures the height of a specified portion within the inspection area, the accuracy of defect determination can be improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 is a perspective view showing a schematic configuration of the appearance inspection apparatus in the application example.

[0031] Figure 2 is a diagram for explaining the generation mechanism of stray light in the prior art.

[0032] Figure 3 is a diagram showing an example of the output signal of the height measurement apparatus obtained in the prior art.

[0033] Figure 4 is a schematic diagram showing the masking area in the application example.

[0034] Figure 5 is a diagram showing the substrate to be inspected, the solder portion, and the masking area in the embodiment.

[0035] Figure 6 is a flowchart showing the setting process for defect inspection in the embodiment.

[0036] Figure 7 is a flowchart showing the defect inspection process in the embodiment.

[0037] Figure 8 is a perspective view showing a schematic configuration of another example of the appearance inspection apparatus applying the actual invention.

[0038] Figure 9 is a diagram for explaining a second example of the generation mechanism of stray light in the prior art. ​​​​​​​​​

[0039] Figure 10 is a diagram showing a second example of the substrate to be inspected, the solder portion, and the masking region in the embodiment.

[0040] Figure 11 is a diagram for explaining the solder protrusion defect in the actual invention. Detailed implementation mode

[0041] 〔Application example〕

[0042] Hereinafter, the appearance inspection apparatus 1 as an application example of the present invention will be described with reference to the drawings. Figure 1 is a perspective view showing a schematic structure of the main part of the appearance inspection apparatus 1. The appearance inspection apparatus 1 mainly includes: a gantry 4 that supports a photographing unit 3 as a photographing part including a camera 2 for photographing an object to be inspected so as to be movable in the X-axis direction; a ball screw 5 that drives the gantry 4 in the Y-axis direction; a guide member 6 that guides the gantry 4 driven by the ball screw 5 in the Y-axis direction; and a frame 7 that supports the above components. A linear scale 8 for detecting the position of the gantry 4 in parallel with the ball screw 5 is provided at a ball screw support portion 7a extending in the Y-axis direction of the frame 7.

[0043] Moreover, at a guide member support portion 7b that also extends in the Y-axis direction of the frame 7, a linear scale 9 for detecting the position of the gantry 4 is provided in parallel with a track that guides a slider provided on the gantry 4. In addition, a linear scale 10 for detecting the position of the photographing unit 3 is provided along the gantry 4 extending in the X-axis direction. These linear scales 8, 9, and 10 are respectively composed of a detected portion arranged along the frame 7 and the gantry 4, and a detection portion provided on the gantry 4 and the photographing unit 3, and the detection portion detects position information relative to the detected portion.

[0044] In Figure 1 of the appearance inspection apparatus 1, a camera 2 having a field of view downward is provided in the photographing unit 3. A conveyor for transporting a circuit board as an inspection object in the X-axis direction is arranged below the camera 2. The circuit board carried into the appearance inspection apparatus 1 from the outside by the conveyor stops below the camera 2 and is clamped at a specified position. Then, when the inspection is completed, the inspection object is transported out of the appearance inspection apparatus 1 from below the camera 2 by the conveyor.

[0045] ​​In a state where the object to be inspected stops below the camera 2, the stage 4 is moved in the Y-axis direction by the drive of the ball screw 5. Furthermore, by the drive of a ball screw (not shown), the imaging unit 3 is also moved in the X-axis direction relative to the stage 4, so that the imaging unit 3 is moved to the inspection position in the circuit board, and the object to be inspected is imaged. The area imaged by the imaging unit 3 corresponds to the inspection area in this embodiment. Then, when the acquisition of the image for appearance inspection is completed, thereafter, the height of the leads of the circuit components soldered on the circuit board is measured by the laser displacement meter 20 serving as a height measurement unit, and inspection for solder protrusion defects is performed. In addition, Figure 1 Only the sensor part of the laser displacement meter 20 is shown, but hereinafter this sensor part will also be referred to as the laser displacement meter 20.

[0046] In addition, the appearance inspection device 1 includes a control device 15 and a servo driver 16 that controls the ball screw 5 of the appearance inspection device 1 and the like according to the instructions of the control device 15. The image of the imaging unit 3 and the information on the height detected by the laser displacement meter 20 are sent to the control device 15, and defect determination for solder protrusion defects is performed by the arithmetic unit 15b provided in the control device 15 according to the program stored in the storage unit 15a provided in the control device 15. Here, the ball screw 5 that drives the stage 4 in the Y-axis direction and the ball screw that moves the imaging unit 3 in the X-axis direction relative to the stage 4 correspond to the moving mechanism in this embodiment.

[0047] Next, use Figure 2 , to describe the defective conditions in the case where the height of the leads is measured by the laser displacement meter 20 and inspection for solder protrusion defects is performed as described above. In Figure 2 , the state of the reflection of the laser at each moment when inspecting for solder protrusion defects using the laser displacement meter 20 is shown. In Figure 2 , the laser displacement meter 20 measures the height of the leads 30a of each circuit component of the circuit board 30 while moving from the left side to the right side in the figure. In addition, in the laser displacement meter 20, the laser is emitted downward vertically from the light emitting part 20a, and the reflected light from the object to be inspected is received by the light receiving part 20b. Regarding the light receiving sensitivity of the light receiving part 20b, the light receiving sensitivity is provided on the light emitting part 20a side of the laser displacement meter 20, and there is no light receiving sensitivity on the side opposite to the light emitting part 20a.

[0048] In Figure 2 , Figure 2 (a) shows the state immediately after the emitted light from the light emitting part 20a passes through the lead 30a. Figure 2 (b) shows the state when the emitted light from the light emitting part 20a irradiates the top of the lead 30a. Figure 2(c) represents the state before the emitted light from the light emitting section 20a is about to irradiate the top of the lead 30a. First, in Figure 2 in the state of (b), the emitted light from the light emitting section 20a of the laser displacement meter 20 directly irradiates the top of the lead 30a, and the reflected light thereof directly enters the light receiving section 20b. In this state, the height of the lead 30a can be accurately measured. Next, in Figure 2 in the state of (a), the emitted light from the light emitting section 20a of the laser displacement meter 20 does not directly irradiate the top of the lead 30a, but irradiates the inclined surface of the lead foot 30b which is the lead foot portion. Moreover, the laser reflected by the lead foot 30b is further reflected by the lead foot 30b of the adjacent lead 30a on its front side, and the reflected light enters the light receiving section 20b as stray light. In this state, due to this stray light, a noise signal larger than the actual height of the lead 30a is output from the laser displacement meter 20.

[0049] Next, in Figure 2 in the state of (c), the emitted light from the light emitting section 20a of the laser displacement meter 20 also does not directly irradiate the top of the lead 30a, but irradiates the inclined surface of the lead foot 30b on the rear side of the lead 30a. Moreover, the laser reflected by the lead foot 30b is further reflected by the lead foot 30b of the adjacent lead 30a on its rear side, and the reflected light enters the light receiving section 20b. In this state, the light receiving section 20b does not have sensitivity to the incident light in this direction, so a noise signal caused by stray light is not output from the laser displacement meter 20.

[0050] Figure 3 represents the change in the output of the laser displacement meter 20 in this case. Figure 3 In the figure, the horizontal axis represents time, and the vertical axis represents the output of the laser displacement meter 20. The solid line in the figure represents the output signal based on the light reflected after the emitted light from the laser displacement meter 20 directly irradiates the top of the lead 30a, and it is a signal reflecting the actual height of the lead 30a. On the other hand, the dotted line represents the Figure 2 noise signal caused by the stray light from the lead foot 30a of the adjacent lead 30 on the front side as shown in (a). In addition, the horizontally extended dotted line in the figure is the inspection threshold. If the output signal based on the light reflected after irradiating the top of the lead 30a is above this threshold, it is determined that the solder further protrudes upward from the upper part of the lead 30a, and it is determined as a defective solder protrusion. As Figure 3 shown, the noise signal is larger than the signal of the actual reflected light from the top of the lead 30a and exceeds the inspection threshold, so it is sometimes misjudged as a defective solder protrusion.

[0051] In contrast, in this application example, the noise signal caused by stray light resulting from the reflection of the inclined surface of the solder joint 30a in the output signal of the laser displacement meter 20 is not used for the determination of solder protrusion defects. More specifically, when the emitted light from the laser displacement meter 20 irradiates Figure 4 the masking area M shown shaded in the figure as a restricted area, the output of the laser displacement meter 20 is not used for the determination of solder protrusion defects. Thereby, it is possible to prevent a defective situation where, due to stray light caused by the reflected light of the inclined surface of the solder joint 30b, it is erroneously determined that there is a solder protrusion defect although there is no solder protrusion defect.

[0052] 〔Example 1〕

[0053] Figure 5 Fig. shows a bottom view of a part of the back surface of the circuit board 30 to be inspected, which is magnified. As shown in the figure, on the back surface of the circuit board 30, the leads 30a and the solder joints 30b formed by soldering the leads 30a to the board 30 are arranged side by side in two columns. Additionally, it is provided that Figure 4 the laser displacement meter 20 moves from left to right in the figure. In this embodiment, in Figure 4 a situation like that shown in the figure, when the measurement light is emitted to the masking area M shown by the dashed line, the output of the laser displacement meter 20 is not used for the determination of solder protrusion defects.

[0054] Furthermore, from Figure 5 it can be seen that the masking area M in the juxtaposed solder joints 30b is set only in the area adjacent to other solder joints 30b in the traveling direction of the laser displacement meter 20. This is because, when the laser displacement meter 20 is not adjacent to other solder joints 30b in its traveling direction, there will be no Figure 2 noise output caused by stray light as shown in (a) of the figure. In other words, in this embodiment, for the solder joints 30a that are not adjacent to other solder joints 30b in the traveling direction of the laser displacement meter 20, the masking area M is not set. Thereby, for the solder joints 30b with a low possibility of generating a noise output caused by stray light among the solder joints 30b, the masking area M is not set, and more detailed height measurement can be performed.

[0055] Next, the control related to the determination of solder protrusion defects will be described using Figure 6 and Figure 7 . Figure 5The figure shows a flowchart related to various setting processes in the determination of solder protrusion defects. This flowchart is stored in the storage unit 15a within the control device 15 and executed by the arithmetic unit 15b. When this process is executed, first, in step S101, the inspection position on the circuit board 30 to be inspected and the start and end positions of the scan by the laser displacement meter 20 are set. Next, in step S102, based on the design information of the circuit board 30, the positions of the connection holes of the leads 30a on the circuit board 30 are obtained, thereby setting the positions of the leads 30a.

[0056] Next, in step S103, the position of the masking region M is automatically set from the position of the lead 30a. More specifically, it can be in the range of, for example, 0.1 mm to 1 mm with respect to the traveling direction of the laser displacement meter 20 starting from the position of the lead 30a, and in the range of ±1 mm from the center of the lead 30a with respect to the direction perpendicular to the traveling direction of the laser displacement meter 20. Regarding the position (range) of this masking region M, it can be determined according to the thickness of the lead 30a and the size of the solder pad 30b. Next, in step S104, the determination threshold for solder protrusion defects is determined. This threshold is set to a value that is larger than the maximum value of the deviation of the height of the lead 30a in the case where no solder protrusion defects occur and smaller than the minimum value of the deviation of the solder end height in the case where solder protrusion defects occur. When the process of step S104 ends, this routine ends. Here, the arithmetic unit 15b of the control device 15 that executes the step S103 of automatically setting the masking region M corresponds to the setting unit in this embodiment.

[0057] Next, in Figure 7 the figure shows a flowchart of the determination routine for solder protrusion defects. When this routine is executed, first, in step S201, the circuit board 30 to be inspected is carried into the appearance inspection device 1. Next, in step S202, the height of the lead 30a of the solder part is measured by the laser displacement meter 20 (actually, before this, the appearance of each inspection region on the circuit board 30 is photographed by the photographing unit 3). Next, in step S203, the masking region M is excluded from the inspection region of the two-dimensional image obtained by the laser displacement meter 20. More specifically, for the masking region M, the height is also measured by the laser displacement meter 20, but the height information obtained from this region is not used for the determination of solder protrusion defects.

[0058] Then, proceed to step S204 to determine whether the maximum height of the peripheral area of the lead 30 is above the inspection threshold set in step S104. At this time, the masking area M is removed from the above-mentioned peripheral area. In addition, the peripheral area of this lead 30 corresponds to a specified part in this embodiment. Here, when the maximum height of the peripheral area of the lead 30 (from which the masking area M has been removed) is smaller than the inspection threshold set in step S104, proceed to step S205. On the other hand, when the maximum height of the peripheral area of the lead 30 (from which the masking area M has been removed) is above the inspection threshold set in step S104, proceed to step S206.

[0059] In step S205, it is determined that there is no solder protrusion defect. On the other hand, in step S206, it is determined that a solder protrusion defect has occurred. When the processing of step S205 or step S206 ends, this routine ends.

[0060] As described above, according to this embodiment, for the area where the measurement light from the laser displacement meter 20 is reflected by the solder leg 30b and becomes stray light and may be received by the laser displacement meter 20, the information of the measured height is not used for the determination of solder protrusion defects. Thereby, it is possible to suppress false determination in the determination of solder protrusion defects. Here, the arithmetic unit 15b of the control device 15 that executes the process of step S203 of excluding the masking area M from the inspection area of the two-dimensional image obtained by the laser displacement meter 20 corresponds to a restricting unit in this embodiment. In addition, the arithmetic unit 15b of the control device 15 that executes the processes of steps S204 to S206 corresponds to a determining unit in this embodiment.

[0061] In addition, in this embodiment, as Figure 1 shown, the case where the laser displacement meter 20 is fixed to the photographing unit 3 of the appearance inspection device 1 and the photographing unit 3 is moved to measure the height of the inspection part of the circuit board 30 as the inspection object has been described, but the appearance inspection device 1 applying the present invention is not limited to Figure 1 the structure shown. For example, as Figure 8 shown, it can also be applied to a type in which the laser displacement meters 11 and 12 are provided in the guide member support portion 7b of the appearance inspection device 1, and when the circuit board 30 is carried into the appearance inspection device 1, the height of the inspection part in the board 30 is measured.

[0062] In addition, in this embodiment, as Figure 2As shown, an example has been described in which, with respect to the probe of the laser displacement meter 20, the light-emitting portion 20a is disposed on the front side of the light-receiving portion 20b with respect to its traveling direction. However, the configuration of the laser displacement meter 20 to which the present invention is applied is not limited to the above configuration. The present invention can also be applied to a device in which the light-emitting portion 20a is disposed on the rear side of the light-receiving portion 20b with respect to the traveling direction of the laser displacement meter 20. Use Figure 9 A case where the light-emitting portion 20a is disposed on the rear side of the light-receiving portion 20b with respect to the traveling direction of the laser displacement meter 20 will be described. Figure 9 It shows the state of reflection of the laser at each moment when the solder protrusion defect is inspected using the laser displacement meter 20 in this case.

[0063] Same as Figure 2 the case of, Figure 9 (a) of shows the state immediately after the emitted light from the light-emitting portion 20a has passed through the lead 30a. Figure 9 (b) of shows the state when the emitted light from the light-emitting portion 20a irradiates the top of the lead 30a. Figure 9 (c) of shows the state immediately before the emitted light from the light-emitting portion 20a irradiates the top of the lead 30a. In Figure 9 (b) of the state, the emitted light from the light-emitting portion 20a of the laser displacement meter 20 directly irradiates the top of the lead 30a, and its reflected light directly enters the light-receiving portion 20b. Then, in Figure 9 (a) of the state, the emitted light from the light-emitting portion 20a of the laser displacement meter 20 irradiates the inclined surface of the lead 30b. Moreover, the laser reflected by the lead 30b is further reflected by the lead 30b of the adjacent lead 30a in front of it, and its reflected light enters the light-receiving portion 20b as stray light. At this time, since the light-receiving portion 20b does not have sensitivity to the incident light in this direction, no noise signal caused by the stray light is output from the laser displacement meter 20.

[0064] Next, in Figure 9 (c) of the state, the emitted light from the light-emitting portion 20a of the laser displacement meter 20 does not directly irradiate the top of the lead 30a either, but irradiates the inclined surface of the lead 30b on the rear side of the lead 30a. Moreover, the laser reflected by the lead 30b is further reflected by the lead 30b of the adjacent lead 30a behind it, and the reflected light enters the light-receiving portion 20b. In this state, due to this stray light, a noise signal larger than the actual height of the lead 30a is output from the laser displacement meter 20.

[0065] Therefore, in the case where the light-emitting portion 20a is disposed on the rear side of the light-receiving portion 20b with respect to the traveling direction of the laser displacement meter 20, as Figure 10As shown, the masking area M can also be set in the area irradiated by the measurement light of the laser displacement meter 20 immediately before the measurement light irradiates the lead 30a.

[0066] In addition, the present invention can also be applied to a device in which the light emitting unit 20a and the light receiving unit 20b are arranged perpendicular to the traveling direction of the laser displacement meter 20. In this case, in two states, namely, immediately after the emitted light from the light emitting unit 20a passes through the lead 30a and immediately before the emitted light from the light emitting unit 20a irradiates the top of the lead 30a, the measurement light reflected by the solder joint 30b sometimes enters the light receiving unit 20b as stray light. Therefore, in this case, the masking area M can also be set for both the area irradiated by the measurement light of the laser displacement meter 20 immediately before irradiating the lead 30a and the area irradiated after irradiating the lead 30a. Regarding the area irradiated by the measurement light of the laser displacement meter 20 immediately before irradiating the lead 30a and the area irradiated after irradiating the lead 30a in the present embodiment, as described above, it can be a range of, for example, 0.1 mm to 1 mm in the traveling direction of the laser displacement meter 20 or its opposite direction starting from the position of the lead 30a.

[0067] In addition, in the above embodiment, the masking area M is excluded from the inspection area of the two-dimensional image obtained by the laser displacement meter 20. More specifically, regarding the masking area M, the height is also measured by the laser displacement meter 20, but the height information obtained from this area is not used for the determination of solder protrusion defects. However, the processing of the masking area M in the present invention is not limited to this. For example, regarding the masking area M, the height may not be measured by the laser displacement meter 20. Or, regarding the masking area M, the height information measured by the laser displacement meter 20 may be uniformly set to a value significantly lower than the height of the lead 30a. Further, regarding the masking area M, the height information measured by the laser displacement meter 20 may be multiplied by a specified coefficient (for example, a coefficient of 1 or less such as ×0.1). In the present embodiment, these processes are equivalent to "limiting the determination unit from determining the presence or absence of defects based on the height information of the specified part measured by the height measurement unit".

[0068] Furthermore, in the above embodiment, the circuit board 30 to be inspected is fixed in the appearance inspection device 1, and the photographing unit 3 and the laser displacement meter 20 are moved, so that the photographing unit 3 and the laser displacement meter 20 move relative to the circuit board 30. However, the appearance inspection device applying the present invention may also be a device in which the photographing unit 3 and the laser displacement meter 20 are fixed and the inspection object moves, so that the photographing unit 3 and the laser displacement meter 20 move relative to the inspection object.

[0069] It should be noted that hereinafter, in order to be able to compare the constituent elements of the present invention and the structure of the embodiment, the constituent elements of the present invention are described with reference numerals of the accompanying drawings.

[0070] <Invention 1>

[0071] An appearance inspection device (1), comprising:

[0072] An imaging unit (3) that images an inspection area on an inspection object (30);

[0073] An altitude measurement unit (20) that measures the altitude of a specified part of the inspection object by emitting measurement light and receiving its reflected light;

[0074] A moving mechanism (5) that changes the inspection area imaged by the imaging unit (3) and the specified part whose altitude is measured by the altitude measurement unit (20) by relatively moving the imaging unit (3) and the altitude measurement unit (20) with respect to the inspection object; and

[0075] A determination unit (15) that determines whether there are defects in the inspection object in the inspection area based on the image of the inspection area imaged by the imaging unit (3) and the information on the altitude of the specified part measured by the altitude measurement unit (20),

[0076] The appearance inspection device (1) is characterized in that it further comprises a restriction unit (15) that restricts the determination unit from determining whether there are defects based on the information on the altitude of the specified part measured by the altitude measurement unit (20) when the measurement light emitted from the altitude measurement unit (20) irradiates a specified restriction area (M) of the inspection object.

[0077] <Invention 7>

[0078] A defect inspection method using an appearance inspection device (1), the appearance inspection device (1) comprising:

[0079] An imaging unit (3) that images an inspection area on an inspection object;

[0080] An altitude measurement unit (20) that measures the altitude of a specified part of the inspection object by emitting measurement light and receiving its reflected light; and

[0081] A moving mechanism (5) that changes the inspection area imaged by the imaging unit (3) and the specified part whose altitude is measured by the altitude measurement unit by relatively moving the imaging unit (3) and the altitude measurement unit (20) with respect to the inspection object,

[0082] This defect inspection method determines whether there are defects in the inspection object in the inspection area based on the image of the inspection area imaged by the imaging unit (3) and the information on the altitude of the specified part measured by the altitude measurement unit (20),

[0083] The defective inspection method is characterized in that, when the measurement light is irradiated onto a prescribed restricted area (M) of the inspection object, determination of the presence or absence of the defect is restricted based on information on the height of the prescribed part measured by the height measurement unit (20).

[0084] Reference Signs Explanation

[0085] 1: Appearance inspection device; 2: Camera; 3: Photographing unit; 8, 9, 10: Linear scale; 15: Control device; 16: Servo driver; 20: Laser displacement meter; 30: Circuit board; 30a: Lead; 30b: Soldering leg; 30c: Solder protrusion defect; M: Masking area.

Claims

1. An appearance inspection device, comprising: a photographing unit that photographs an inspection area on an object to be inspected; a laser displacement meter that measures the height of a specified part of the object to be inspected by emitting measurement light and receiving its reflected light; a moving mechanism that moves the photographing unit and the laser displacement meter relative to the object to be inspected, and changes the inspection area photographed by the photographing unit and the specified part where the height is measured by the laser displacement meter; a determination unit that determines whether there is a defect in the object to be inspected in the inspection area based on the image of the inspection area photographed by the photographing unit and the information on the height of the specified part measured by the laser displacement meter; and a restricting unit that restricts the determination unit from determining whether there is the defect based on the information on the height of the specified part measured by the laser displacement meter when the measurement light emitted from the laser displacement meter irradiates a specified restricted area of the object to be inspected, wherein the object to be inspected is a circuit board on which circuit components are mounted, the restricted area includes an area that is the area irradiated by the measurement light immediately before or immediately after the moment when the measurement light is irradiated onto the lead of the circuit component soldered to the circuit board when the laser displacement meter moves relative to the circuit board, when the light emitting part of the measurement light is arranged on the front side of the light receiving part with respect to the traveling direction of the laser displacement meter, the restricted area is the area irradiated by the measurement light immediately after it irradiates the lead; when the light emitting part of the measurement light is arranged on the rear side of the light receiving part with respect to the traveling direction of the laser displacement meter, the restricted area is the area irradiated by the measurement light immediately before it irradiates the lead; when the light emitting part and the light receiving part of the measurement light are arranged side by side in a direction perpendicular to the traveling direction of the laser displacement meter, the restricted area is the area irradiated by the measurement light immediately before it irradiates the lead and the area irradiated by the measurement light immediately after it irradiates the lead.

2. The appearance inspection device according to claim 1, wherein the restricted area includes a solder fillet part where solder forms a slope around the lead of the circuit component soldered to the circuit board.

3. The appearance inspection device according to claim 1 or 2, wherein in the direction of relative movement of the laser displacement meter with respect to the circuit board or the opposite direction with respect to the restricted area, there are other leads and solder fillet parts adjacent to the lead irradiated by the measurement light.

4. The appearance inspection device according to claim 1 or 2, wherein the appearance inspection device further includes a setting unit that automatically sets the restricted area based on the position of the lead in the circuit board.

5. The appearance inspection device according to claim 1, wherein the defect is a solder protrusion defect in which solder protrudes from the end of the lead during soldering of the lead of the circuit component to the circuit board.

6. A defective inspection method using an appearance inspection device, the appearance inspection device comprising: a photographing unit that photographs an inspection area on an object to be inspected; a laser displacement meter that measures the height of a specified part of the object to be inspected by emitting measurement light and receiving the reflected light thereof; and a moving mechanism that relatively moves the photographing unit and the laser displacement meter with respect to the object to be inspected, thereby changing the inspection area photographed by the photographing unit and the specified part whose height is measured by the laser displacement meter, the defective inspection method determines whether there is a defect in the object to be inspected in the inspection area based on the image of the inspection area photographed by the photographing unit and the information on the height of the specified part measured by the laser displacement meter, the object to be inspected is a circuit board on which a circuit component is mounted, and the defective inspection method restricts the determination of whether there is a defect based on the information on the height of the specified part measured by the laser displacement meter when the measurement light irradiates a specified restricted area of the object to be inspected, the restricted area includes the following area: when the laser displacement meter relatively moves with respect to the circuit board, the area irradiated by the measurement light immediately before or immediately after the moment when the measurement light irradiates the lead of the circuit component soldered to the circuit board, when the light emitting part of the measurement light is arranged on the front side of the light receiving part with respect to the traveling direction of the laser displacement meter, the restricted area is the area irradiated by the measurement light immediately after irradiating the lead, when the light emitting part of the measurement light is arranged on the rear side of the light receiving part with respect to the traveling direction of the laser displacement meter, the restricted area is the area irradiated by the measurement light immediately before irradiating the lead, when the light emitting part and the light receiving part of the measurement light are arranged side by side in a direction perpendicular to the traveling direction of the laser displacement meter, the restricted area is the area irradiated by the measurement light immediately before irradiating the lead and the area irradiated by the measurement light immediately after irradiating the lead.

7. The defective inspection method according to claim 6, wherein the restricted area includes a solder foot part, in which solder forms a slope around the lead of the circuit component soldered to the circuit board.

8. The defective inspection method according to claim 6 or 7, wherein in the direction of relative movement of the laser displacement meter with respect to the circuit board or the opposite direction with respect to the restricted area, there are other leads and solder foot parts adjacent to the lead irradiated by the measurement light.

9. The defective inspection method according to claim 6 or 7, wherein the defect is a solder protrusion defect in which solder protrudes from the end of the lead during the soldering of the lead of the circuit component to the circuit board.

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