Electronic component inspection method and electronic component inspection device

Abstract

In the present invention, a first optical image and a second optical image are acquired, and from such optical images it is possible to detect a plane of a solder connection part of a first electrode in an electronic component and a plane of a solder connection part of a second electrode in the electronic component. The relative position between the plane of the solder connection part of the first electrode and the plane of the solder connection part of the second electrode in the electronic component is calculated from at least one of the first optical image and the second optical image, and the flatness of the first electrode and the second electrode is calculated to determine the quality of the appearance of the electronic component.

Description

Electronic component inspection method and electronic component inspection device

[0001] The present invention relates to an electronic component inspection method and an electronic component inspection device.

[0002] In the manufacturing process of small electronic components such as diodes, visual inspection currently relies largely on the visual work of inspectors. Therefore, tasks such as distinguishing between normal and defective electronic components and detecting defects are performed using human senses. In response to this, techniques have been proposed that observe electronic components before mounting them on a board using a camera and detect visual defects using image processing technology. For example, a method has been disclosed in which multiple cameras are arranged around the object to be inspected and lead wire bending is automatically detected using image processing (see, for example, Patent Document 1). In this method, the cameras are arranged so that the optical axis of the optical system used for observation is 90° or less or 180° or less for an axial lead-type electronic component. Also, an optical system configuration has been disclosed for inspecting rectangular parallelepiped electronic components such as wafer chips in a short time to inspect the appearance of the front, back, and side surfaces of the object to be inspected (see, for example, Patent Document 2).

[0003] JP 8-159732 A JP 2016-128781 A

[0004] In surface-mount electronic components, dimensional errors in the flatness of the two poles (anode and cathode) soldered to the mounting board directly lead to mounting defects. However, the inspection method described in Patent Document 1 targets axial-lead electronic components and can only evaluate the coaxiality or parallelism of the two lead wires. For this reason, the inspection method described in Patent Document 1 cannot be applied to inspecting electronic components with other configurations, including the flatness of surface-mount diode elements. Furthermore, the inspection method described in Patent Document 2 only performs visual inspection of the electronic component to be inspected, such as for cracks, chips, and scratches, by capturing an image of the electronic component. For this reason, the inspection method described in Patent Document 2 does not mention inspecting the flatness of the electrodes of surface-mount electronic components.

[0005] In order to solve the above-mentioned problems, the present invention provides an electronic component inspection method and an electronic component inspection device that are capable of inspecting the flatness of two electrodes of a surface-mounted electronic component by visual inspection.

[0006] The above and other objects of the present invention and novel features of the present invention will become apparent from the description of this specification and the accompanying drawings.

[0007] An electronic component inspection method according to the present invention inspects an electronic component having first and second electrodes surface-mounted on a substrate. This inspection method acquires a first optical image capable of detecting the planes of the solder connections of the first and second electrodes of the electronic component, and a second optical image capable of detecting the planes of the solder connections of the first and second electrodes at an angle different from that of the first optical image. Then, from at least one of the first and second optical images, the relative position of the planes of the solder connections of the first and second electrodes of the electronic component is calculated, and the flatness of the first and second electrodes is calculated to determine whether the appearance of the electronic component is good or bad.

[0008] An electronic component inspection apparatus according to the present invention inspects an electronic component having first and second electrodes surface-mounted on a substrate, and includes a transport device that transports the electronic component to an observation position, an imaging device that captures a first optical image capable of detecting the planes of the solder connections of the first and second electrodes of the electronic component, and a second optical image at an angle different from the angle of the first optical image, capable of detecting the planes of the solder connections of the first and second electrodes, an observation optical system disposed between the electronic component and the imaging device, and an apparatus controller that controls the transport device and the imaging device. The device control unit has an image analysis unit that analyzes information in at least one of the first optical image and the second optical image acquired by the imaging device and calculates the relative position between the plane of the solder connection portion of the first electrode of the electronic component and the plane of the solder connection portion of the second electrode, and an inspection unit that compares the flatness of the solder connection portion of the first electrode and the solder connection portion of the second electrode with a threshold value based on the information calculated by the image analysis unit.

[0009] According to the present invention, it is possible to provide an electronic component inspection method and an electronic component inspection device that are capable of inspecting the flatness of two electrodes of a surface-mounted electronic component by visual inspection.

[0010] Problems, configurations, and effects other than those described above will become clear from the following description of the embodiments.

[0011] 12A and 12B are diagrams illustrating the configuration of a surface-mounted diode element, which is an example of an electronic component; FIG. 13A is a cross-sectional view of a surface-mounted diode element, which is an example of an electronic component; FIG. 13B is a diagram illustrating an example of a diode element whose flatness has deteriorated due to an assembly error; FIG. 13C is a perspective view illustrating the configuration of an inspection device for electronic components; FIG. 13D is a functional block diagram of an inspection device control unit; FIG. 13E is a flowchart of an inspection method for electronic components; FIG. 13F is a diagram illustrating the difference in inclination θy between the solder connection portion of the lead and the solder connection portion of the base; FIG. 13G is a diagram illustrating the step [Zb-Zt] in the z-axis direction between the solder connection portion of the lead and the solder connection portion of the base; FIG. 13H is a diagram illustrating an optical image (yz side view) of a diode element detected by a camera; FIG. 13I is a bottom view (xy plan view) of the solder connection portion of the base of the diode element; FIG. 13I is a diagram illustrating the displacement of the height of point P on the outer periphery of the solder connection portion; FIG. 13I is a diagram illustrating the configuration of an inspection device in a state where the diode element is positioned within the observation field; FIG. 13I is an xz cross-sectional view of a prism in the observation optical system of the inspection device shown in FIG. 12A; and FIG. 13I is a diagram illustrating an optical image of a diode element photographed by a camera in the inspection device.

[0012] An example of an electronic component inspection method and an electronic component inspection device according to an embodiment of the present invention will be described below with reference to the drawings. Note that the present invention is not limited to the following example. In the drawings described below, common components are given the same reference numerals. Furthermore, in the drawings used in this specification, identical or corresponding components are given the same reference numerals, and repeated explanations of these components may be omitted.

[0013] [Structure of Electronic Components] First, the structure of an electronic component to be applied to the electronic component inspection method and electronic component inspection device of this embodiment will be described. The electronic component to be inspected in this embodiment is, for example, a small electronic component such as a diode product. Small electronic components are mass-produced on a monthly basis, with monthly production of several million units. Small electronic components come in a wide variety of product types and shapes. Furthermore, because small electronic components are small and lightweight (weighing a few grams), it is difficult to inexpensively build a mechanism for transporting and positioning electronic components individually. For these reasons, automating the visual inspection process for electronic components is considered difficult. In the following description, a product in which a semiconductor element is housed in a dedicated package and mounted on a mounting board as an electronic component will be referred to as a "diode element" or simply an "element."

[0014] 1 and 2 show, as an example of an electronic component, a surface-mounted diode element, which is a type of Zener diode and is used for surge absorption. Fig. 1 is an external view of the diode element, and Fig. 2 is a cross-sectional view of the diode element. In the diode element 100 shown in Fig. 1, a plan view is shown as diode element 100a, side views are shown as diode elements 100b and 100c, and a bottom view is shown as diode element 100d.

[0015] The diode element 100 has two electrodes: a base 101 (first electrode) and a lead 102 (second electrode). The diode element 100 is a surface-mount electronic component, and the two electrodes (anode and cathode) of the base 101 and the lead 102 are soldered to a mounting substrate. The base 101 corresponds to the anode of the diode element 100, and the lead 102 corresponds to the cathode of the diode element 100. Both the base 101 and the lead 102 are made of metal. The outer diameter 101a of the base 101 is about 10 mm. The diode element 100 weighs only about 2 g per element, and is easily deformed if handled improperly.

[0016] The base 101 is formed in the shape of a bottomed case with an opening at the top. The semiconductor element 110 is built into the base 101. Inside the base 101, the bottom surface of the semiconductor element 110 is electrically connected to the bottom surface of the inner surface of the base 101 by solder 111b. The top surface of the semiconductor element 110 is electrically connected to the metal electrode 103 by solders 111a and 111b. The metal electrode 103 is electrically connected to the lead 102 by an annular ring solder 112. The inside of the base 101 is filled with insulating resin 104. The insulating resin 104 seals the entire semiconductor element 110 and the metal electrode 103 except for the portion connected to the ring solder 112.

[0017] The lead 102 has a crank-like shape in which straight metal segments are alternately bent at approximately 90° angles. The lead 102 has an adsorption portion 102a that comes into contact with a suction nozzle (not shown) when the diode element 100 is individually transported, and a terminal portion 102b that is used for mounting (solder connection) on a printed circuit board (not shown). The adsorption portion 102a, the terminal portion 102b, and the portion connecting them are each formed in a straight line (flat). The adsorption portion 102a and the terminal portion 102b are formed so as to be parallel to each other. The lead 102 is electrically connected to the semiconductor element 110 via a ring solder 112 at the end of the adsorption portion 102a.

[0018] The back side of the terminal portion 102b is the solder connection portion 102c when mounted on the printed circuit board. Therefore, the solder connection portion 102c has an area large enough to allow connection by soldering and is formed as a substantially flat surface. The bottom of the outer surface of the base 101 is the solder connection portion 101b, similar to the connection portion 102c on the back side of the terminal portion 102b. Therefore, the solder connection portion 101b has an area large enough to allow connection by soldering and is formed as a substantially flat surface. To reliably mount the diode element 100 on the printed circuit board, it is desirable that the flat surfaces of the solder connection portion 101b and the solder connection portion 102c be flush with each other. Note that deviation from the flush surface of the solder connection portion 101b and the flat surfaces of the solder connection portion 102c is permissible within a predetermined tolerance range that does not impair the mounting reliability of the diode element 100 on the board.

[0019] 2, in the diode element 100, the base 101 and the semiconductor element 110, the semiconductor element 110 and the metal electrode 103, and the metal electrode 103 and the lead 102 are connected by solders 111a, 111b, and 112, respectively. Therefore, if poor leveling occurs during the reflow process of the solders 111a, 111b, and 112, the flatness between the solder connection portion 101b of the base 101 and the adsorption portion 102a of the lead 102 deteriorates. In other words, the flatness between the solder connection portion 101b of the base 101 and the solder connection portion 102c of the lead 102 deteriorates.

[0020] 3 shows an example of the configuration of a diode element 100 in which the flatness between the solder connection portion 101b of the base 101 and the solder connection portion 102c of the lead 102 has deteriorated due to an assembly error. FIG. 3(a) is an xz-plane view of the diode element 100, and FIG. 3(b) is a yz-plane view of the diode element 100. In the diode element 100 shown in FIG. 3, the z-axis is a direction perpendicular to the surface of a substrate when the diode element 100 is mounted on the substrate. For example, when the plane of the solder connection portion 101b of the base 101 and the plane of the solder connection portion 102c of the lead 102 are the same horizontal plane, the z-axis is a direction perpendicular to the plane of the solder connection portion 101b and the solder connection portion 102c. The x-axis is perpendicular to the z-axis and corresponds to the direction in which the lead 102 extends, i.e., parallel to the line connecting the center of the suction portion 102a of the lead 102 to the center of the terminal portion 102b. The y-axis is perpendicular to the z-axis and x-axis. The definitions of the x-axis, y-axis, and z-axis in the diode element 100 are the same in all figures other than FIG. 3.

[0021] FIG. 3 shows a state in which the base 101 is tilted θy in the x-z plane due to assembly errors or the like, when the suction portion 102a of the lead 102 is used as a reference. As shown in FIG. 3( a), in the diode element 100, one end of the flat portion of the solder connection portion 101b of the base 101 in the x-axis direction is designated P1, and the other end is designated P2. In this case, if the diameter (P1-P2) of the solder connection portion 101b of the base 101 is 7 mm and the difference θy in the inclination between the y-axis and the plane of the solder connection portion 101b in the y-axis direction is 1°, a difference of 122 μm occurs between the heights of P1 and P2 (in the z-axis direction). Under these conditions, when viewed in the y-z plane of the diode element 100 shown in FIG. 3( b), a step G occurs between the end P2 of the solder connection portion 101b of the base 101 and the plane of the solder connection portion 102c of the lead 102 (in the z-axis direction). Therefore, the solder connection portion 101b of the base 101 and the solder connection portion 102c of the lead 102 cannot be considered to be on the same plane. As a result, when the diode element 100 is mounted on a printed circuit board, the step between the solder connection portion 101b of the base 101 and the solder connection portion 102c of the lead 102 causes at least one of the electrodes to float above the board. This causes poor bonding between the board and the diode element 100. In this way, dimensional errors in the flatness of the two electrodes of the diode element 100 directly lead to poor mounting and reduced reliability.

[0022] The diode element 100 is primarily used in rectifier circuits. The diode element 100 is also widely used in protection circuits for protecting electronic circuits from sudden electrical noise. The diode element 100 is also implemented and used in advanced driving assistance systems, complex operation control systems, and the like in automobiles and railway vehicles, and high reliability is required to prevent the loss of important functions due to electrical noise. Therefore, it is important for the diode element 100 to ensure the reliability of its individual electrical characteristics, and accurate mounting (solder connection) of the element on a mounting board is a condition for ensuring the performance of the entire circuit system.

[0023] [Electronic Component Inspection Apparatus (1)] Next, the configuration of an electronic component inspection apparatus according to this embodiment will be described. In the description of the inspection apparatus, the above-described diode element 100 is used as the electronic component to be inspected. Fig. 4 is a perspective view showing the configuration of the electronic component inspection apparatus.

[0024] The inspection device 200 shown in FIG. 4 inspects the relative position between the solder connection 101b of the base 101 and the solder connection 102c of the lead 102, which are between two electrode surfaces of the diode element 100. The inspection device 200 then quickly determines whether the product is good or bad. The inspection device 200 includes observation lenses 220 and 221, cameras 230 and 231, surface illuminators 210 and 211, and a suction nozzle 243. The inspection device 200 also includes an illumination control unit 241, a conveyance mechanism 242, and an image processing unit 240, which control the above components. The inspection device 200 also includes a device control unit 250, which controls the above components. The observation lenses 220 and 221 are examples of an observation optical system that guides an optical image of the diode element 100. The cameras 230 and 231 are examples of an imaging device that captures an optical image of the diode element 100. The suction nozzle 243 is an example of a transport device for transporting the diode element 100 to a predetermined observation position. The surface illuminators 210 and 211 are examples of illumination devices for adjusting the brightness of the diode element 100 when acquiring an optical image.

[0025] The device control unit 250 is composed of, for example, a central processing unit (CPU), read-only memory (ROM), random access memory (RAM), etc. (not shown). The CPU is an example of a calculation unit related to the inspection device 200. The CPU centrally controls the operation of each unit of the inspection device 200. The CPU reads out program code of software related to various processes of the inspection device 200 stored in a ROM (an example of a recording medium) and loads it into the RAM. The CPU then controls the inspection device 200 in accordance with the loaded program. Note that the device control unit 250 may include another calculation unit, such as an MPU (micro processing unit), instead of a CPU.

[0026] The inspection device 200 vacuum-sucks the suction portion 102a of the diode element 100 with the suction nozzle 243 and positions it at an observation position within the field of view of the observation lenses 220 and 221. The operation of the suction nozzle 243 is controlled by a transport mechanism 242. The transport mechanism 242 is a device that moves the suction nozzle 243 in the horizontal and vertical directions. The transport mechanism 242 controls the operation of the suction nozzle 243 based on the control of the device control unit 250. The transport mechanism 242 is made up of a power source such as a motor or actuator for operating the suction nozzle 243, a pump for vacuum-sucking the diode element 100, and various members for transmitting this power to the suction nozzle 243.

[0027] In the inspection device 200, the observation lenses 220 and 221 constituting the observation optical system are arranged at positions where the observation optical axes 220' and 221' are orthogonal to each other in the xy plane. The cameras 230 and 231 detect the side surfaces (xz and yz planes) of the diode element 100 along the observation optical axes 220' and 221'. The surface illuminators 210 and 211 are arranged at positions facing the observation lenses 220 and 221 across the diode element 100. The normals 210' and 211' of the light-emitting surfaces of the surface illuminators 210 and 211 are coaxial with the optical axes 220' and 221'. The illumination control unit 241 controls the illuminance and lighting timing of the surface illuminators 210 and 211 based on the control of the device control unit 250.

[0028] Furthermore, image capture control of cameras 230 and 231 is performed by image processing unit 240 based on control of device control unit 250. Image processing unit 240 controls activation, image capture, etc. of cameras 230 and 231. Furthermore, image processing unit 240 takes in image information captured by cameras 230 and 231, and performs processes such as conversion, deformation, analysis of specific information, and extraction of specific information on the acquired image information.

[0029] (Functional Configuration of Device Control Unit) Next, the functional configuration of the device control unit 250 will be described. Fig. 5 shows a functional block diagram of the device control unit 250. The transport control unit 251 controls the driving of the transport mechanism 242. As a result, the transport control unit 251 controls the operation of the suction nozzle 243 via the transport mechanism 242, and performs suction, transport, and positioning of the diode element 100.

[0030] The imaging control unit 252 controls the driving of the surface illuminator 210 and the driving of the cameras 230 and 231. The imaging control unit 252 controls the turning on and off of the surface illuminator 210. Furthermore, the imaging control unit 252 controls the driving of the cameras 230 and 231, thereby controlling the acquisition of an optical image of the diode element 100. Furthermore, the imaging control unit 252 outputs image data acquired by the cameras 230 and 231 to the image processing unit 240.

[0031] The image analysis unit 253 acquires the image of the diode element 100 created by the image processing unit 240. Then, the image analysis unit 253 analyzes information in the acquired image based on predetermined image processing parameters. For example, the image analysis unit 253 extracts a specific area for analysis from the acquired image. Then, the image analysis unit 253 detects the positions of various components in the extracted image, converts them into mathematical expressions, quantifies them, and performs other calculations.

[0032] The inspection unit 254 compares the various components of the diode element 100 with standards for determining quality based on the detection, mathematical expression, and digitization of the positions of the various components calculated by the image analysis unit 253. For example, the inspection unit 254 compares the value of the step between the solder connection portion 101b and the solder connection portion 102c of the diode element 100 acquired from the image with a threshold value for determining quality, assuming the flatness of the bipolar electrodes. The inspection unit 254 also compares the value of the slope difference θy of the plane of the solder connection portion 101b with a threshold value for determining quality, assuming the flatness of the bipolar electrodes. The inspection unit 254 also compares the value of the flatness of the solder connection portion 101b with a threshold value for determining quality, assuming the flatness of the bipolar electrodes.

[0033] The determination unit 255 determines whether the appearance of the inspected diode element 100 is a pass or not. Specifically, the determination unit 255 determines whether the appearance of the diode element 100 is a pass or not based on the result of comparing the values ​​of various components of the diode element 100 inspected by the inspection unit 254 with a threshold value for determining whether the diode element 100 is a pass or not. If all the results of the inspection by the inspection unit 254 are within the threshold value, the determination unit 255 determines the diode element 100 to be a pass or not. Furthermore, if one or more of all the results of the inspection by the inspection unit 254 exceed the threshold value, the determination unit 255 determines the diode element 100 to be a defective product.

[0034] 4, the transport mechanism 242, the illumination control unit 241, and the image processing unit 240 are shown as components separate from the device control unit 250, but some or all of these may be included in the device control unit 250. For example, the device control unit 250 may include the image processing unit 240, and the device control unit 250 may perform image processing by the image processing unit 240. Alternatively, the device control unit 250 may include the illumination control unit 241, and the device control unit 250 may perform illumination control processing by the illumination control unit 241. Furthermore, the device control unit 250 may include an internal control function of the transport mechanism 242, and the device control unit 250 may control the operation of the suction nozzle 243 by the transport mechanism 242.

[0035] [Electronic Component Inspection Method] Next, an electronic component inspection method using the above-described inspection device will be described. A flowchart of the electronic component inspection method is shown in Fig. 6. The flowchart shown in Fig. 6 is an explanatory diagram of the operation of inspection device 200. The diode element 100 to be inspected is taken out from a group of diode elements stored in a tray (not shown).

[0036] First, the transport control unit 251 drives the transport mechanism 242 and the suction nozzle 243 to pick up the diode elements 100 one by one from the tray (step S300). Then, the suction nozzle 243 is moved along the transport path 201 to position the picked-up diode elements 100 at desired observation positions within the imaging areas of the cameras 230 and 231 (step S301).

[0037] Next, the imaging control unit 252 turns on the surface illuminator 210 and causes the camera 230 to capture an image, thereby detecting an optical image (xz side view; first optical image) of the diode element 100 (step S302). The imaging control unit 252 also turns on the surface illuminator 211 and causes the camera 231 to capture an image, thereby detecting an optical image (yz side view; second optical image) of the diode element 100 (step S303). Steps S302 and S303 are preferably performed simultaneously. The observation lenses 220 and 221 each incorporate an illumination mechanism (not shown) coaxial with the observation optical axes 220' and 221'. Therefore, the imaging control unit 252 controls the illumination mechanisms of the observation lenses 220 and 221 to be turned on simultaneously with the surface illuminators 210 and 211 disposed opposite the observation lenses 220 and 221.

[0038] Next, based on the optical image (xz side view), the inspection unit 254 determines whether the step [Zb-Zt] in the z-axis direction between a straight line 411 (FIG. 7) parallel to the plane of the solder connection 101b and the plane of the solder connection 102c is within a threshold value (first threshold value) (step S304). If the step [Zb-Zt] is within the threshold value (Yes in step S304), the inspection unit 254 determines whether the difference in inclination θy between the y-axis and the plane of the solder connection 101b in the y-axis direction is within a threshold value (second threshold value) (step S305).

[0039] The step [Zb-Zt] in the z-axis direction between the straight line 411 (FIG. 7) and the solder connection portion 102c in step S304, and the tilt difference θy of the solder connection portion 101b in step S305 will be described with reference to FIGS. 7 and 8. FIGS. 7 and 8 show an optical image (xz side view) of the diode element 100 detected by the camera 230 in step S302. FIG. 7 is a diagram showing the entire detection field of the camera 230. FIG. 8 is an enlarged view of the periphery of the terminal portion 102b.

[0040] 7 , the image analysis unit 253 acquires an image (xz side view) of the diode element 100 created by the image processing unit 240. Then, the image analysis unit 253 extracts the range of an area 400 that is predetermined by image processing parameters and includes the solder connection portion 101b of the base 101. Furthermore, the image analysis unit 253 calculates a straight line 411 that is parallel to the plane of the solder connection portion 101b of the base 101 in the image of the extracted area 400.

[0041] 8, the image analysis unit 253 extracts the range of an area 401 that is predetermined by the image processing parameters and that includes the bottom surface (solder connection portion 102c) of the terminal portion 102b of the lead 102. Furthermore, the image analysis unit 253 calculates a straight line 410 that is parallel to the plane of the solder connection portion 102c of the lead 102 in the image of the extracted area 401.

[0042] The image analysis unit 253 then defines the center position of the region 401 on the x-axis on the straight line 410 as the height Zt of the solder connection portion 102c in the z-axis direction. Furthermore, the image analysis unit 253 defines the position on the straight line 411 that is closest to the position where the height Zt is defined as the height Zb of the straight line 411 in the z-axis direction.

[0043] Next, the inspection unit 254 calculates the difference (step) between the height Zt of the solder connection 102c in the z-axis direction and the height Zb of the straight line 411 in the z-axis direction using the formula [Zb-Zt]. Furthermore, the inspection unit 254 determines whether the calculated step [Zb-Zt] is within a predetermined threshold value (first threshold value) that has been set in advance. The above is the processing of the image analysis unit 253 and the inspection unit 254 in step S304.

[0044] Next, the image analysis unit 253 detects the difference in slope θy of the line 411 parallel to the plane of the solder connection portion 101b of the base 101, with respect to the line 410 parallel to the plane of the solder connection portion 102c of the lead 102. As a result, the image analysis unit 253 calculates the difference in slope θy of the line 411 parallel to the plane of the solder connection portion 101b of the base 101, relative to the line 410 parallel to the plane of the solder connection portion 102c of the lead 102. The inspection unit 254 then determines whether the difference in slope θy calculated by the image analysis unit 253 is within a predetermined threshold value (second threshold value) that has been set in advance. This completes the processing of the image analysis unit 253 and the inspection unit 254 in step S305.

[0045] Returning to the explanation of FIG. 6 , if the difference in slope θy is within the threshold value (Yes in step S305), the inspection unit 254 determines whether the flatness of the solder connection portion 101b of the base 101 is within a threshold value (third threshold value) (step S306). The method of calculating the flatness of the solder connection portion 101b of the base 101 in step S306 will be described with reference to FIGS. 9 and 10 . FIG. 9 shows an optical image (yz side view) of the diode element 100 detected by the camera 231 in step S303. Also, FIG. 10 shows a bottom view (xy plan view) of the solder connection portion 101b of the base 101 of the diode element 100.

[0046] 9 , the image analysis unit 253 acquires an image (yz side view) of the diode element 100 created by the image processing unit 240. Then, the image analysis unit 253 extracts the range of a region 500 that is predetermined by the image processing parameters and includes the bottom surface (solder connection portion 102c) of the terminal portion 102b of the lead 102. Furthermore, the image analysis unit 253 calculates a straight line 510 that is parallel to the plane of the solder connection portion 102c of the lead 102 in the image of the extracted region 500.

[0047] 9 , the image analysis unit 253 extracts the ranges of an area 501 and an area 502, which are predetermined by the image processing parameters and include the solder connection portion 101b of the base 101. Furthermore, the image analysis unit 253 calculates a straight line 511 that is parallel to the plane of the solder connection portion 101b of the base 101 in the images of the extracted areas 501 and 502.

[0048] Next, the image analysis unit 253 detects the difference in inclination θx of the line 511 parallel to the plane of the solder connection portion 101b of the base 101, with reference to the line 510 parallel to the plane of the solder connection portion 102c of the lead 102. As a result, the image analysis unit 253 calculates the difference in inclination θx of the line 511 parallel to the plane of the solder connection portion 101b of the base 101 with respect to the line 510 parallel to the plane of the solder connection portion 102c of the lead 102.

[0049] Next, the image analysis unit 253 calculates the flatness of the solder connection portion 101b using the difference in slope θx between the line 510 and the line 511, and the difference in slope θy between the line 410 and the line 411. The image analysis unit 253 calculates the flatness of the solder connection portion 101b using the plane of the solder connection portion 102c as a reference. FIG. 10 shows a bottom view of the diode element 100. As shown in FIG. 10, the radius of the solder connection portion 101b is defined as r, and the height of an arbitrary point P on its outer periphery is calculated. Let Z1 be the amount of variation in the height of point P due to the influence of the slope difference θy in the x-z cross-sectional view shown in FIG. 7, and Z2 be the amount of variation in the height of point P due to the influence of the slope difference θx in the y-z cross-sectional view shown in FIG. 9. Z1 and Z2 can be calculated using Equations (1) and (2), respectively.

[0050] Z1=r・cosφ・tanθy...(1) Z2=r・sinφ・tanθx...(2)

[0051] The height of point P on the outer periphery of solder connection 101b is affected by the slope differences θy and θx, resulting in a value of [Z1 + Z2]. FIG. 11 is an explanatory diagram showing the variation in height of point P on the outer periphery of solder connection 101b. As shown in FIG. 11, the flatness of solder connection 101b is calculated as the difference between the maximum and minimum values ​​of [Z1 + Z2]. Note that FIG. 11 shows the results of calculations under the conditions of radius r of solder connection 101b = 4 mm, θy = 0.8° in the x-z cross section, and θx = -0.5° in the y-z cross section. In the above example, the flatness of solder connection 101b is calculated to be 132 μm. This concludes the calculation process for the flatness of solder connection 101b of base 101 in step S306.

[0052] Returning to the description of FIG. 6 , if the step difference [Zb-Zt] is not within the threshold value (No in step S304), if the difference in slope θy is not within the threshold value (No in step S305), or if the flatness of the solder connection portion 101b is not within the threshold value (No in step S306), the determination unit 255 identifies the inspected diode element 100 as defective (step S307). For example, in step S304, if the distance L from the center of the metal electrode 103 to point Zt is 10 mm and θy is 1°, the step difference [Zb-Zt=175 μm] is calculated. If the threshold value (first threshold value) of the step difference [Zb-Zt] is set to ±100 μm, the determination unit 255 identifies a diode element 100 with a step difference "Zb-Zt=175 μm" as defective. Furthermore, if the threshold value (second threshold value) of the tilt difference [θy] is set to ±1° in step S305, the determination unit 255 identifies the diode element 100 having the tilt difference [θy=−2°] as a defective product. Furthermore, if the threshold value (third threshold value) of the flatness is set to 100 μm in step S306, the determination unit 255 identifies the diode element 100 having the flatness calculated to be 132 μm under the above conditions as a defective product.

[0053] If the flatness of the solder connection portion 101b is within the threshold value (Yes in step S306), or after the diode element 100 is identified as a defective product, the transport control unit 251 moves the inspected diode element 100 from the observation position (step S308). The transport control unit 251 drives the transport mechanism 242 and the suction nozzle 243 to move the inspected diode element 100. The transport control unit 251 also drives the transport mechanism 242 and the suction nozzle 243 to remove the next diode element to be inspected from the tray and transport it to the observation position.

[0054] Next, the determination unit 255 determines whether the appearance of the diode element 100 after inspection is pass-quality (step S309). The determination unit 255 determines that the appearance of the diode element 100, which is determined to be within the threshold in all of steps S304, S305, and S306, is pass-quality. If the appearance of the diode element 100 is pass-quality (Yes in step S309), the transport control unit 251 sorts the pass-quality diode element 100 for shipment (step S310). On the other hand, if the appearance of the diode element 100 is not pass-quality (No in step S309), the transport control unit 251 collects the defective diode element 100 into a collection box (step S311). After sorting or collecting the diode element 100 for shipment, the processing according to this flowchart ends.

[0055] According to the above-described electronic component inspection method, two cameras 230, 231 with orthogonal observation fields capture images of the diode element 100, which is the same inspection target. The relative positional relationship between the solder connection 101b on the base 101 side and the solder connection 102c on the lead 102 side is then detected from each captured image. This allows the step, inclination, and flatness between the solder connection 101b and the solder connection 102c to be calculated from the two optical images. As a result, visual inspection of the diode element 100 can be performed in a short time without using three-dimensional measurement, making it possible to perform visual inspection of all products before shipment for electronic components mass-produced at a monthly production scale of several million units.

[0056] In the above-described electronic component inspection method, images of the diode element 100 are acquired from the x-z side view and the y-z side view, but the acquired images are not limited to these positions. As described above, the acquired images are preferably the x-z side view shown in FIG. 7 and the y-z side view shown in FIG. 9 , but the imaging angle of the diode element 100 is not particularly important. In the electronic component inspection method, images of the diode element 100 must be captured from two different angles at positions where at least the planes of the solder connection portions 101b and 102c of the diode element 100 can both be recognized. Then, a line 410 parallel to the plane of the solder connection portion 102c and a line 411 parallel to the plane of the solder connection portion 101b are calculated from the planes of the solder connection portions 101b and 102c of the diode element 100 in one of the captured images. Furthermore, a line 510 parallel to the plane of solder connection 102c and a line 511 parallel to the plane of solder connection 101b are calculated from the plane of solder connection 101b and the plane of solder connection 102c of diode element 100 in the other captured image. Therefore, in the electronic component inspection method, it is sufficient to acquire two images captured from an xy plane that is perpendicular to the z-axis and horizontal to solder connection 101b and solder connection 102c. Acquiring images from this position allows the planes of solder connection 101b and solder connection 102c to be extracted and analyzed more accurately.

[0057] Furthermore, in the above-described electronic component inspection method, three types of comparison judgments, namely, steps S304, S305, and S306, are performed to determine whether an electronic component is good or bad, but it is not necessary to perform all of these. In the electronic component inspection method, it is sufficient to perform the quality determination of an electronic component using at least one of the comparison judgment methods of steps S304, S305, and S306. It is preferable to use at least the comparison judgment method of step S304 because of its ease of image analysis and calculation and high inspection accuracy. It is also preferable to combine the comparison judgment method of step S304 with one or more of the judgment methods of steps S305 and S306.

[0058] [Electronic Component Inspection Apparatus (2)] Next, another configuration of the electronic component inspection apparatus according to this embodiment will be described. Fig. 12 shows the configuration (perspective view) of another form of electronic component inspection apparatus. The inspection apparatus 200A shown in Fig. 12 includes a telecentric lens 600, a camera 610, prisms 601, 602, 603, and 604, and suction nozzles 243 and 244. Similar to the inspection apparatus 200 shown in Fig. 4 above, the inspection apparatus 200A also includes an illumination control unit 241, which controls each component, a conveyance mechanism 242, an image processing unit 240, and an apparatus control unit 250 (not shown) that controls each component.

[0059] In the inspection device 200A, an observation optical system is configured by prisms 601, 602, 603, and 604, and a telecentric lens 600. In the inspection device 200A, the telecentric lens 600 has an aperture diameter that encompasses observation regions 601', 602', 603', and 604' obtained by the prisms 601, 602, 603, and 604. Therefore, in the inspection device 200A, an optical image detected by the telecentric lens 600 via the prisms 601, 602, 603, and 604 is observed by a camera 610.

[0060] The inspection device 200A sucks the diode elements 100 and 100A with suction nozzles 243 and 244, transports them to the observation field of view, and positions them at regular intervals. Figure 12 shows the state in which the diode element 100 is positioned within the observation field of view. Four identical prisms 601, 602, 603, and 604, each with a 45° angle at its tip, are arranged facing each other around the diode element 100. Therefore, the diode element 100 is moved horizontally along a transport path 620 by a transport mechanism (not shown) to the top of the observation field of view, where it stops, and then descends along a transport path 621 in the negative z-axis direction. This positions the diode element 100 in the desired observation field of view within the imaging area of ​​the camera 610. Furthermore, after capturing an optical image of the diode element 100, the transport mechanism (not shown) moves the diode element 100 upward along a transport path 622 in the positive z-axis direction, moves horizontally along a transport path 623, and is removed from the observation field of view. Simultaneously with the ejection of the diode element 100, the next diode element 100A is transported and positioned in the observation field.

[0061] The inspection device 200A observes the side surface of the diode element 100 from four directions using prisms 601, 602, 603, and 604 arranged opposite to each other. FIG. 13 is an xz cross-sectional view of the prisms 602 and 604 of the observation optical system shown in FIG. 12 . Note that the suction nozzle 244 is omitted from FIG. 13 . By placing the diode element 100 between the opposing prisms 602 and 604, the inspection device 200A can observe the yz side surface of the diode element 100 with a camera 610 via the prisms 602 and 604 and the telecentric lens 600. At the same time, the inspection device 200A can directly observe the bottom surface (xy bottom surface) of the diode element 100 with the camera 610 via the telecentric lens 600.

[0062] 14 shows an optical image of the diode element 100 captured by the camera 610 in the above-described inspection device 200A. As shown in FIG. 14, an xy plan view (bottom surface) of the diode element 100 is obtained in the center of the field of view. In addition, a yz side view of the diode element 100 is obtained in observation areas 602' and 604', and an xz side view of the diode element 100 is obtained in observation areas 601' and 603'.

[0063] Therefore, the inspection device 200A can calculate the step (Zb-Zt) between the solder connection portion 101b of the base 101 and the solder connection portion 102c of the lead 102 shown in FIG. 8 using the optical image of the observation region 601' or 603'. Furthermore, the inspection device 200A can calculate the tilt difference θy of the plane of the solder connection portion 101b of the base 101, with respect to the solder connection portion 102c of the lead 102, using the optical image of the observation region 601' or 603'. Furthermore, the inspection device 200A can calculate the tilt difference θx of the line 511 parallel to the plane of the solder connection portion 101b of the base 101, with respect to the line 510 parallel to the plane of the solder connection portion 102c of the lead 102 shown in FIG. 7, using the optical image of the observation region 602'.

[0064] According to the above-described electronic component inspection device, multiple prisms 601, 602, 603, and 604 are arranged around the diode element 100 to be inspected, and the same diode element 100 to be inspected is simultaneously observed from multiple directions. This allows optical images of the diode element 100 in five directions, including the four side surfaces and the bottom surface, to be acquired from a single acquired image data. The relative positional relationship between the solder connection 101b on the base 101 side and the solder connection 102c on the lead 102 side is then detected from each observation region. This makes it possible to calculate the step, inclination, and flatness between the solder connection 101b and the solder connection 102c from a single image data set. This allows for the miniaturization of the observation optical system of the visual inspection device. Furthermore, according to the above-described electronic component inspection device, by acquiring optical images of the diode element 100 in five directions, including the four side surfaces and the bottom surface, it is possible to inspect the surface of the diode element 100 to detect visual defects such as scratches and discoloration.

[0065] It should be noted that the present invention is not limited to the above-described embodiments and various modifications are possible. For example, the above-described embodiments have been described in detail to clearly explain the present invention, and the present invention is not necessarily limited to embodiments that include all of the described configurations. Furthermore, it is possible to replace part of the configuration of one embodiment with the configuration of another embodiment. It is also possible to add the configuration of another embodiment to the configuration of one embodiment. It is also possible to delete part of the configuration of each embodiment, or to add or replace other configurations.

[0066] 100, 100a, 100b, 100d, 100A...diode element, 101...base, 101a...outer diameter, 101b, 102c...solder connection portion, 102...lead, 102a...suction portion, 102b...terminal portion, 103...metal electrode, 104...insulating resin, 110...semiconductor element, 200, 200A...inspection device, 201, 620, 621, 622, 623...transport path, 210, 211...surface illuminator, 210'...normal, 220...observation lens, 220'...observation optical axis, 230, 231, 6 10... camera, 240... image processing unit, 241... illumination control unit, 242... transport mechanism, 243, 244... suction nozzle, 250... device control unit, 251... transport control unit, 252... imaging control unit, 253... image analysis unit, 254... inspection unit, 255... judgment unit, 400, 401, 500, 50, 502... area, 410, 411, 510, 511... line, 600... telecentric lens, 601, 602, 603, 604... prism, 601', 602', 603', 604'... observation area

Claims

1. A method for inspecting an electronic component having a first electrode and a second electrode surface-mounted on a substrate, comprising: acquiring a first optical image capable of detecting the plane of the solder connection of the first electrode of the electronic component and the plane of the solder connection of the second electrode of the electronic component; and acquiring an optical image capable of detecting the plane of the solder connection of the first electrode and the plane of the solder connection of the second electrode at an angle different from that of the first optical image; calculating the relative position of the plane of the solder connection of the first electrode of the electronic component and the plane of the solder connection of the second electrode of the electronic component from at least one of the first optical image and the second optical image; and calculating the flatness of the first electrode and the second electrode to determine whether the appearance of the electronic component is good or bad.

2. The method for inspecting electronic components according to claim 1, wherein the flatness of the first electrode and the second electrode is determined by calculating the difference in level [Zb-Zt] between the height Zb of the plane of the solder connection portion of the first electrode in the z-axis direction and the height Zt of the solder connection portion of the second electrode in the z-axis direction based on the first optical image, and the difference in level [Zb-Zt] is compared with a first threshold value to determine whether the appearance of the electronic component is good or bad.

3. The method for inspecting an electronic component according to claim 1, wherein the flatness of the first electrode and the second electrode is determined by calculating, based on the first optical image, a difference in inclination θy in the y-axis direction of the plane of the solder connection portion of the first electrode, with a straight line parallel to the plane of the solder connection portion of the second electrode as a reference, and comparing the difference in inclination θy with a second threshold value to determine whether the appearance of the electronic component is good or bad.

4. The method for inspecting an electronic component according to claim 1, wherein the flatness of the first electrode and the second electrode is determined by: calculating, based on the first optical image, a difference in tilt θy in the y-axis direction of the plane of the solder connection portion of the first electrode, with a straight line parallel to the plane of the solder connection portion of the second electrode as a reference; calculating, based on the second optical image, a difference in tilt θx in the x-axis direction of the plane of the solder connection portion of the first electrode, with a straight line parallel to the plane of the solder connection portion of the second electrode as a reference; calculating the flatness of the plane of the solder connection portion of the first electrode based on the difference in tilt θx and the difference in tilt θy; and comparing the flatness of the plane of the solder connection portion of the first electrode with a third threshold value to determine whether the appearance of the electronic component is good or bad.

5. An inspection device for an electronic component having a first electrode and a second electrode surface-mounted on a board, comprising: a transport device that transports the electronic component to an observation position; an imaging device that acquires a first optical image capable of detecting the plane of the solder connection portion of the first electrode and the plane of the solder connection portion of the second electrode of the electronic component, and a second optical image that can detect the plane of the solder connection portion of the first electrode and the plane of the solder connection portion of the second electrode at an angle different from the angle of the first optical image; an observation optical system disposed between the electronic component and the imaging device; and a device control unit that controls the transport device and the imaging device, wherein the device control unit comprises: an image analysis unit that analyzes information in at least one of the first optical image and the second optical image acquired by the imaging device, and calculates the relative position of the plane of the solder connection portion of the first electrode of the electronic component and the plane of the solder connection portion of the second electrode; an inspection unit that compares the flatness of the solder connection portion of the first electrode and the solder connection portion of the second electrode with a threshold value based on the information calculated by the image analysis unit.

6. An electronic component inspection device according to claim 5, wherein the observation optical system comprises four prisms arranged opposite each other around the observation position of the electronic component, and the imaging device uses the prisms to obtain the first optical image, the second optical image, the third optical image, and the fourth optical image of the side of the electronic component from four different angles.

Images