Flux coating condition inspection device and flux coating condition inspection procedure

Abstract

For example, a flux deposition condition verification device is provided that achieves the high accuracy of a verification while enabling the specification of a verification area through a relatively simple process. A flux deposition condition verification device 12 includes an illumination device 321 configured to illuminate a printed circuit board with visible light of the same color as a base material section of the printed circuit board at a large angle of incidence; a camera 322 configured to capture an image of light emitted from the illumination device 321 onto the printed circuit board and reflected from the printed circuit board; and a first specification section 335 configured to specify a dark section and an intermediate luminance section of a luminance image obtained by the camera 322 as an electrode region.and a second specification section 336, configured to specify the intermediate luminance section located in the electrode area as a flux deposition area and / or to specify the dark section located in the electrode area as an electrode exposure area. A determination section 337 is configured to perform a determination of defective / non-defective with respect to a flux deposition state on an electrode based on the flux deposition area and / or the electrode exposure area specified by the second specification section 336.

Description

Technical field The present disclosure relates to a testing device and a testing method for performing a test of the application or coating condition of a flux on a printed circuit board. State of the art A general procedure for mounting an electronic component onto a printed circuit board (PCB) first involves printing solder paste onto electrodes placed on the PCB. The procedure then temporarily fixes the electronic component to the PCB using the printed solder paste and its viscosity. After this temporary fixation, the PCB is placed in a reflow oven to undergo a predetermined reflow process, which solders the electronic component. To minimize the occurrence of assembly errors, a semiconductor packing, such as a spherical grid array (BGA), with numerous spherical contact bumps (solder balls) arranged regularly and uniformly on its base, has been proposed as the electronic component. When mounting such a semiconductor packing as the electronic component on a printed circuit board (PCB), it is not necessary to print the solder paste; only the contact bumps need to be positioned relative to the electrodes. However, when mounting such a semiconductor packing on a PCB, it is preferable to apply the electrodes to improve the wettability of the solder before placing the pumps on the electrodes. An unsuitable flux deposition condition on the electrodes is likely to cause a problem, such as insufficient bond strength between the electronic component and the printed circuit board. Therefore, it is preferable to perform a flux deposition condition check before placing the electronic component on the printed circuit board. A known inspection device used to perform a flux deposition condition check compares an image of the flux, acquired by an imaging device, with pattern-detected electrodes or electrodes whose pattern is recognized (a circuit pattern), and performs a check of the flux deposition condition (as described, for example, in patent reference 1). In the inspection device described in the patent reference 1 above, the area of ​​applied flux is defined as being wider than the entire area of ​​the electrodes (the entire surface of a printed circuit board), and the flux is also opaque. This configuration allows the imaging device to capture an image of the flux, but it does not allow the imaging device to capture an image of the electrodes (an image of the printed circuit board) with the flux applied to them. Accordingly, an inspection of the flux application status uses the pattern-detected electrodes, rather than the actual electrodes, as the inspection area. In other words, an inspection of the flux application status is performed using a virtually estimated area of ​​electrode occurrence.To ensure sufficiently high accuracy of the verification, there is a need to define a suitable verification area that is appropriate for the position of the actual electrodes. One proposed technique for determining the appropriate inspection area suitable for the position of the actual electrodes is, for example, a method for using markings provided on a printed circuit board as a reference (as described, for example, in patent literature 2). Citation list Patent literature Patent literature 1: Japanese patent no. 2010-271165A Patent literature 2: Japanese patent no. 2005-286309A Brief description Technical problem However, the method of using markers as a reference may require extremely high processing accuracy to define a suitable inspection area, particularly when inspecting a printed circuit board (PCB) with a large number of electrodes positioned at extremely small intervals (for example, a PCB with a semiconductor pack mounted on it, such as a BGA). Such a requirement for extremely high processing accuracy is likely to increase the processing load and thus reduce the efficiency of the inspection. However, simplifying the processing to reduce the processing load is likely to cause a "deviation" between the inspection area and the position of the actual electrodes. Consequently, this is likely to result in failure to provide sufficiently high inspection accuracy. Taking into account the circumstances described above, it is an objective of the present disclosure to provide, for example, a flux application condition verification device that achieves the high accuracy of a verification while making it possible to define a verification area through a relatively simple process. Solution to the problem The following describes each of the various aspects that are appropriately provided to solve the problems described above. Features and beneficial effects characteristic of each aspect are also described where necessary. Aspect 1. A flux application condition verification device is provided, configured to perform a verification of a transparent or translucent flux applied to an electrode of a printed circuit board (PCB) containing a base material section of green, red, or brown color. The flux application condition verification device comprises: an irradiation unit configured to irradiate the PCB with visible light of an identical color to that of the base material section of the PCB, at an angle of incidence of not less than 55 degrees and not more than 75 degrees;an imaging unit positioned above the printed circuit board in such a way that an optical axis of the imaging unit is orthogonal to the printed circuit board, and configured to capture an image of light radiated onto the printed circuit board by the irradiation unit and reflected from the printed circuit board to obtain a luminance image that includes the electrode, which is seen as a dark section; the base material section, which is seen as a bright section having a higher luminance value than the luminance value of the dark section; and a section where the flux is present on the electrode, which is seen as an intermediate luminance section having an intermediate luminance value between the luminance value of the dark section and the luminance value of the bright section;a first specification unit configured to specify the dark section and the intermediate luminance section in the luminance image as an electrode region, identifying an existing area of ​​the electrode in the printed circuit board; a second specification unit configured to perform at least one of the specifications: specifying the intermediate luminance section of the luminance image located in the electrode region as a flux deposition region, identifying an area where the flux has been applied to the electrode, and specifying the dark section of the luminance image located in the electrode region as an electrode exposure region, identifying an area where the electrode is exposed;and a determination unit configured to perform a determination of faulty / non-faulty with respect to a flux application state on the electrode, based on at least one of the areas, flux application area and electrode exposure area, specified by the second specification unit. In the flux deposition condition verification device of aspect 1 above, the irradiation unit irradiates the printed circuit board (PCB) with visible light of the same color as the base material section of the PCB at an angle of incidence of not less than 55 degrees and not more than 75 degrees. The visible light is reflected (non-uniformly) from the base material section of the PCB. The light emitted by the irradiation unit enters the PCB at a relatively large angle of incidence. This makes it unlikely that the light, which is uniformly reflected from the electrode without flux (from the irradiated electrode), will reach the imaging unit.In contrast, in the electrode with the applied flux, light is reflected unevenly by the flux. This makes it more likely that the light reflected from this electrode will reach the imaging unit. Accordingly, this configuration causes the electrode to appear as a dark section, the base material section as a bright section with a higher luminance value than the dark section, and the section with the flux on the electrode as an intermediate luminance section with an intermediate luminance value between the dark section and the bright section, in the luminance image obtained by the imaging unit. The first specification unit defines the dark area and the intermediate luminance area in the luminance image as an electrode region, indicating an existing area of ​​the electrode on the printed circuit board (PCB). This configuration allows the first specification unit to specify the electrode region—i.e., a verification area—more precisely and easily as the object for determining whether the flux has been applied properly. This reduces the processing load associated with defining the verification area and thus improves verification efficiency. Furthermore, this configuration allows the verification area (the electrode region) to be specified without using any marker provided as a reference on the PCB.This even more effectively prevents a reduction in the accuracy of the check that accompanies a change in the position of the reference caused by a change in the shape of the printed circuit board (for example, warping, contraction or expansion of the printed circuit board). The second specification unit, in contrast, specifies the intermediate luminance section and / or the dark section of the luminance image located within the electrode area as the flux deposition area and / or the electrode exposure area. This configuration allows for a more precise and easier specification of the flux deposition area and the electrode exposure area, which are the regions that characterize the state of flux deposition on the electrode. The determination unit then performs the fault / non-fault determination with respect to the flux application state on the electrode based on at least one of the areas—flux application area and electrode exposure area—specified by the second specification unit. As described above, the configuration of this aspect allows the electrode area corresponding to a verification area to be precisely specified, as well as the flux application area and the electrode exposure area located within that electrode area. This ensures the high accuracy of the verification in the fault / non-fault determination by the determination unit.This configuration therefore ensures sufficient accuracy of the verification even in the case of a verification relating to a printed circuit board provided with a large number of electrodes arranged at extremely small intervals (for example, a printed circuit board with a BGA mounted on it). Aspect 2. In the flux application condition verification device described in Aspect 1 above, the angle of incidence of the light emitted from the irradiation unit onto the printed circuit board can be adjusted so that it is not less than 60 degrees and not more than 75 degrees. The configuration of aspect 2 above makes it less likely that the light uniformly reflected from the electrode will reach the imaging unit. This configuration therefore provides a more pronounced difference in the luminance image between the luminance value of an exposed electrode and the luminance value of an electrode with the flux applied to it. Consequently, this allows the electrode exposure area and the flux application area to be specified even more precisely in the luminance image, further improving the accuracy of the verification. With a view to further improving the accuracy of a check, it is preferable to adjust the angle of incidence of the light emitted from the irradiation unit onto the circuit board so that it is not less than 60 degrees and not more than 70 degrees. Aspect 3. The flux application condition verification device described in Aspect 1 above may further include an input unit configured to input the color of the base material section of the printed circuit board; and a wavelength control device configured to automatically control a wavelength of visible light emitted by the irradiation unit based on the color input by the input unit. If the color input by the input unit is green, the wavelength control device may be configured to adjust the wavelength of the light emitted by the irradiation unit so that it is not lower than 520 nm and not higher than 530 nm.If the color input by the input unit is red or brown, the wavelength control device can be configured to adjust the wavelength of the light emitted by the irradiation unit so that it is not lower than 625 nm and not higher than 635 nm. In the flux application condition verification device of aspect 3 above, the color (color-related information) of the base material section of the printed circuit board is input by the input unit. Accordingly, the configuration of this aspect 3 allows the wavelength of the light emitted by the irradiation unit to be automatically adjusted to a suitable wavelength based on the color of the base material section. This configuration ensures a higher degree of accuracy in the verification and further improves the suitability of the verification process. Aspect 4. A flux application condition verification procedure is provided for performing a verification of a transparent or translucent flux applied to an electrode of a printed circuit board (PCB) containing a base material section of green, red, or brown color. The flux application condition verification procedure comprises: an irradiation process to irradiate the PCB with visible light of an identical color to that of the base material section of the PCB, at an angle of incidence of not less than 55 degrees and not more than 75 degrees;an imaging process for using an imaging unit placed above the printed circuit board in such a way that an optical axis of the imaging unit is orthogonal to the printed circuit board to capture an image of light irradiated onto the printed circuit board and reflected from the printed circuit board in the irradiation process to obtain a luminance image that includes the electrode, which can be seen as a dark section; the base material section, which can be seen as a bright section having a higher luminance value than the luminance value of the dark section; and a section where the flux is present on the electrode, which can be seen as an intermediate luminance section having an intermediate luminance value between the luminance value of the dark section and the luminance value of the bright section;a first specification process to specify the dark section and the intermediate luminance section in the luminance image as an electrode region, which identifies an existing area of ​​the electrode in the printed circuit board; a second specification process to perform at least one of the specifications, specifying the intermediate luminance section of the luminance image located in the electrode region as a flux deposition region, which identifies an area where the flux is applied to the electrode, and specifying the dark section of the luminance image located in the electrode region as an electrode exposure region, which identifies an area where the electrode is exposed;and a determination process for performing a determination of defective / non-defective with respect to a flux application state on the electrode based on at least one of the areas, flux application area and electrode exposure area, specified in the second specification process. The configuration of aspect 4 above has similar functions and beneficial effects to those of aspect 1 described above. The technical characteristics described above in the respective aspects can be combined in a suitable manner. For example, the technical characteristics relating to aspect 3 above can be combined with the technical characteristics relating to aspect 2 above. In another example, at least one of the technical characteristics relating to aspects 2 and 3 above can be applied to aspect 4 above. Brief description of the drawings Fig. 1 is a schematic top view showing a printed circuit board; Fig. 2 is a schematic top view showing the printed circuit board omitting electronic components and the like to show electrodes; Fig. 3 is a schematic sectional view showing a partial closure of the printed circuit board; Fig. 4 is a schematic perspective view showing an electronic component; Fig. 5 is a sectional view showing a partial closure of the electronic component and the like before it is mounted on electrodes; Fig. 6 is a block diagram showing the configuration of a printed circuit board production line; Fig. 7 is a schematic top view showing a partial closure of the printed circuit board to show the application of flux to the electrodes; Fig.Figure 8 is a schematic configuration diagram schematically representing a flux application state verification device; Figure 9 is a block diagram showing the functional configuration of the flux application state verification device; Figure 10 is a schematic top view representing a partial closure of the printed circuit board in the case where all of a plurality of electrodes configuring an electrode group are adequately covered with flux; Figure 11 is a schematic diagram representing a luminance image in the case where all of a plurality of electrodes configuring an electrode group are adequately covered with flux; Figure 12 is a schematic top view representing a partial closure of the printed circuit board in the case where some of the plurality of electrodes are not adequately covered with flux but are exposed; and Figure 13 is a schematic top view representing a partial closure of the printed circuit board in the case where some of the plurality of electrodes are not adequately covered with flux but are exposed.Figure 13 is a schematic diagram representing a luminance image in the case where part of the multitude of electrodes is not adequately covered with flux but is exposed. Description of embodiments The following describes an embodiment with reference to drawings. The configuration of a printed circuit board (PCB) is described first. As can be seen in Fig. 1, Fig. 2 to Fig. 3, a printed circuit board 1 (hereinafter referred to simply as "circuit board 1") is a glass-epoxy circuit board, wherein electrodes 3 (not shown in Fig. 1), made of copper foil and the like, are formed on a flat, plate-like base substrate 2, made, for example, of a glass-epoxy resin. An electronic component 5, such as a chip, is mounted on the electrodes 3 via solder paste 4, which is provided by kneading solder grains with flux (hereinafter referred to simply as "solder 4"). A region of the base substrate 2, apart from the electrodes 3 and a circuit pattern (electrode pattern), is a base material section 6, which consists, for example, of a glass-epoxy resin and a photoresist or coating, and gives green color according to the embodiment. Furthermore, as can be seen in Fig. 4, the electronic component 5 according to the embodiment is a ball grid array (BGA), wherein a plurality of contact bumps 4a are arranged regularly or uniformly on a base surface of the electronic component 5. The respective contact bumps 4a are fused to be distributed over the area or surface of the electrodes 3 in a reflow process carried out by a reflow device 14 described later, and ultimately form the solder 4. The base substrate 2 has an electrode array 3x (shown in Fig. 2) consisting of a plurality of electrodes 3 as objects on which the respective contact bumps 4a are placed to mount an electronic component 5. In a process of mounting an electronic component 5 onto the base substrate 2, each contact bump 4a is fused to the surface of the electrodes 3.Each bump 4a is placed on each of the electrodes 3 that configure the electrode group 3x. According to this embodiment, the base substrate 2 has a plurality of (for example, four) electrode groups 3x, and an electronic component 5 is mounted on each electrode group 3x. According to this embodiment, the spacing of the plurality of electrodes 3 that configure an electrode group 3x is very small (for example, as small as 1.8 mm or less, or 0.5 mm or less). Furthermore, as can be seen in Fig. 5, before the electronic component 5 is mounted on the electrode group 3x, a flux 7 is applied to the surface of the plurality of electrodes 3 that configure the electrode group 3x. The flux 7 is used to remove metal oxide films in the electrodes 3, the electronic component 5, and the solder 4, and to improve the wettability of the solder 4. The flux 7 is configured to be transparent or translucent and barely visible. In addition, according to the embodiment, the flux 7 is configured to individually coat the plurality of electrodes 3 that configure an electrode group 3x. The following describes a production line (manufacturing process) for producing the printed circuit board 1. As shown in Fig. 6, in a production line 10, a flux application device 11, a flux application condition check device 12, a component assembly machine 13, a reflow device 14, and a post-reflow check device 15 are placed sequentially from an upstream side of the line (from a top side of Fig. 6). The printed circuit board 1 is positioned to be passed onto these devices in this sequence. The flux application device 11 is configured to apply the flux 7 to at least the area or surface of the electrodes 3 of the printed circuit board 1. For example, the flux application device 11 places a predetermined mask on the printed circuit board 1 and then applies the flux 7 to the area or surface of the electrodes 3 using a screen-printing process. According to this embodiment, as shown in Fig. 7, the flux application device 11 applies the flux 7 to individually cover the plurality of electrodes 3 that configure an electrode group 3x. Figs. 7, 10, and 12 are schematic top views showing a partial closure of the printed circuit board 1. In these drawings, the flux 7 is shown by diagonal lines for the sake of simplicity. However, the flux 7 is transparent or translucent.In the actual state, it is therefore difficult to clearly specify an application area of ​​the flux 7 by visual observation. According to a modification, the flux application device 11 can be configured to apply the flux 7 by using a predetermined distributor. The flux application condition inspection device 12 is configured to perform an inspection of the application condition of the flux 7 applied to the electrodes 3, i.e., the coating condition of the flux 7 with which the electrodes 3 are coated. The flux application condition inspection device 12 is described later. The component assembly machine 13 is configured to perform a component assembly process that mounts the electronic component 5 onto the electrodes 3 and the like. The electronic component 5 is accordingly mounted onto the electrode group 3x via the contact bumps 4a. The reflow device 14 is configured to perform a reflow process that heats and fuses the contact bumps 4a and the like. In the printed circuit board 1 undergoing the reflow process, the contact bumps 4a are fused to be distributed over the area of ​​the electrodes 3 and are finally solidified to form the solder 4. The solder 4 acts to connect the electronic component 5 to the electrodes 3. The post-reflow inspection device 15 is configured to perform a post-reflow inspection process that checks whether the solder joint is properly formed during the reflow process. For example, the post-reflow inspection device 15 uses image data or the like from the printed circuit board 1 after the reflow process to check for the presence or absence of any positional misalignment in the electronic component 5. Production line 10 is further equipped with conveying devices or the like between the respective devices described above, for example, between the flux application device 11 and the flux application condition check device 12, to transfer the printed circuit board 1, although this is omitted from the illustration. Additionally, a branching device is provided between the flux application condition check device 12 and the component assembly machine 13, and on a downstream side of the post-reflow check device 15. The printed circuit board 1, which is determined to be non-defective by the flux application condition check device 12 and by the post-reflow check device 15, is fed directly to the downstream side.The circuit board 1, which is identified as faulty by at least one of the inspection devices 12 and 15, is discharged by the branching device to a storage area for faulty items (not shown). The following describes the configuration of the flux application condition verification device 12. As can be seen in Fig. 8 and Fig. 9, the flux application condition verification device 12 includes a transfer mechanism 31 configured to, for example, transfer and position the printed circuit board 1; a verification unit 32 configured to perform a verification of the flux 7; and a control device 33 configured to drive and control the transfer mechanism 31 and the verification unit 32 and to perform a variety of control, image processing, and arithmetic operations in the verification device 12. The transfer mechanism 31 comprises a pair of transfer rails 31a positioned along an in / out transport direction of the printed circuit board 1; and an endless conveyor belt 31b positioned to rotate relative to each of the transfer rails 31a. The transfer mechanism 31 is also provided with a drive unit, such as a motor, configured to drive the conveyor belt 31b, and with a clamping mechanism configured to position the printed circuit board 1 at a predetermined position, although these are omitted from the illustration. The transfer mechanism 31 is driven and controlled by the control device 33 (more specifically, a transfer mechanism control device 338 of this, which will be described later). According to the configuration described above, the printed circuit board 1, which is transported into the flux application condition inspection device 12, is placed on the conveyor belt 31b in such a way that the respective edges of the printed circuit board 1 are inserted into the transfer rails 31a in a width direction perpendicular to the in / out transport direction. The conveyor belt 31b then begins to operate to transfer the printed circuit board 1 to a predetermined inspection position. When the printed circuit board 1 reaches the inspection position, the conveyor belt 31b stops and the clamping mechanism described above begins to operate. This operation of the clamping mechanism pushes the conveyor belt 31b upwards, causing the respective edges of the printed circuit board 1 to be arranged layer by layer between the conveyor belt 31b and the upper sides of the transfer rails 31a. This positions and fixes the printed circuit board 1 in the inspection position.After completion of the inspection, the clamping mechanism releases the fixation and the conveyor belt 31b begins operation. The printed circuit board 1 is accordingly transported out of the flux application condition inspection device 12. However, the configuration of the transfer mechanism 31 is not limited to the configuration of the embodiment described above; another configuration can be used. The inspection unit 32 is positioned above the transmission rails 31a (transmission path of the circuit board 1). The inspection unit 32 is equipped with a lighting device 321 and a camera 322. According to the embodiment, the lighting device 321 configures the "irradiation unit" and the camera 322 configures the "imaging unit". The inspection unit 32 is also provided with an X-axis motion mechanism 323, configured to allow movement in an X-axis direction (a left-right direction of Fig. 8), and a Y-axis motion mechanism 324, configured to allow movement in a Y-axis direction (a forward-backward direction of Fig. 8). Both motion mechanisms 323 and 324 are driven and controlled by the control device 33 (more specifically, a relay control device 338 of this, which will be described later). The illumination device 321 is configured to illuminate the printed circuit board 1, which is the object of inspection performed by the flux application condition inspection device 12, with visible light that has the same color as the base material section 6 of the printed circuit board 1. According to the embodiment, the base material section 6 is green. Accordingly, the illumination device 321 illuminates the printed circuit board 1 with green visible light (for example, light having a wavelength of not less than 520 nm and not more than 530 nm). Furthermore, the lighting device 321 emits light at an angle of incidence θ of not less than 55 degrees and not more than 70 degrees. According to the embodiment, the angle of incidence θ of the light emitted by the lighting device 321 towards the circuit board 1 (in particular towards a subsequently described inspection target area KH) is set such that it is not less than 60 degrees and not more than 75 degrees. With a view to improving the accuracy of an inspection, the angle of incidence θ is preferably not less than 60 degrees and not more than 70 degrees. According to the embodiment, the process of emitting light from the lighting device 321 towards the circuit board 1 corresponds to the "irradiation process". The camera 322 is positioned directly above the circuit board 1 as the object of inspection such that an optical axis O of the camera 322 is orthogonal to the circuit board 1, and is configured to capture an image of an inspection target area KH of the circuit board 1 from directly above. According to the embodiment, the inspection target area KH is predefined for each of the electronic components 5 to be mounted and is specified as an area containing all of the plurality of electrodes 3 that form an electrode group 3x (as shown in Fig. 7). The camera 322, for example, is configured as a CCD camera sensitive to the light emitted by the illumination device 321 and is operated and controlled by the control device 33 (more specifically, by a camera control device 333, which will be described later). The operating control of the control device 33 causes the camera 322 to take an image of the light reflected from the circuit board 1, in the state where the circuit board 1 is illuminated by the light from the illumination device 321, within the inspection target area KH. A luminance image with respect to the inspection target area KH is thus obtained. The luminance image contains a large number of pixels, each of which has data relating to the luminance.According to the embodiment, a process of causing the camera 322 to take an image of the light emitted by the lighting device 321 and reflected by the circuit board 1 corresponds to the “imaging process”. In the luminance image, the electrode 3 without flux 7 applied to it (i.e., an exposed electrode) appears as a dark section. This is because the illumination device 321 emits the light at a relatively large angle of incidence θ towards the circuit board 1, making it unlikely that the light, which is uniformly reflected from the exposed electrode, reaches the camera 322. Furthermore, in the luminance image, the base material section 6 appears as a bright section with a higher luminance than the dark section (the exposed electrode). This is because the visible light emitted by the illumination device 321 has the same color as the base material section 6, so this visible light is reflected (unevenly reflected) by the base material section 6 and reaches the camera 322. Even when the flux 7 is applied to the base material section 6, the base material section 6 is still visible as a bright section. Additionally, in the luminance image, a section where the flux 7 is present on the electrode 3 can be seen as an intermediate luminance section (for example, a gray section) that has an intermediate luminance between the luminance of the dark section (the exposed electrode) and the luminance of the light section (the base material section 6). This is because the electrode 3 with the flux 7 applied to it causes the light to be reflected unevenly through the flux 7, and the light reflected from this electrode 3 is more likely to reach the camera 322. Accordingly, in the case where all of the plurality of electrodes 3 configuring an electrode group 3x are adequately covered with the flux 7 (as can be seen, for example, in Fig. 10), the base material section 6 appears as a bright section in the luminance image, and the section where the flux 7 is present on the electrode 3 appears as an intermediate luminance section (gray section) (as can be seen, for example, in Fig. 11). In the case where some or all of the electrodes 3 are not adequately covered with the flux 7, but any exposed electrode 3e is present (as can be seen, for example, in Fig. 12), the exposed electrode 3e appears as a dark section in the luminance image (as can be seen, for example, in Fig. 13). The luminance image obtained by the camera 322 is transmitted to the control device 33 (an image import section 334 of this device, which will be described later). The control device 33 performs a verification process for the application status of the flux 7 based on this luminance image. The control device 33 is configured by a computer which includes a CPU (central processing unit) that performs predetermined arithmetic operations, a ROM (read-only memory) that stores a variety of programs, fixed-value data and the like, a RAM (random access memory) in which a variety of data is temporarily stored during the execution of various arithmetic operations, and peripheral circuits of these. The CPU operates according to the various programs, so that the control device 33 serves as different functional sections, such as a main control device 331, a lighting control device 332, a camera control device 333, an image import section 334, a first specification section 335, a second specification section 336, a destination section 337, a motion mechanism control device 338 and a transmission mechanism control device 339. The respective functional sections described above are implemented through the interaction of various hardware components, such as the CPU, ROM, and RAM, also described above. There is no need to clearly distinguish between the functions implemented by the hardware configuration and those implemented by the software configuration. Some or all of these functions may be implemented by a hardware circuit, such as an IC. According to the embodiment, the first specification section 335 configures the "first specification unit," the second specification section 336 configures the "second specification unit," and the determination section 337 configures the "determination unit." The control device 33 is further provided with, for example, an input unit 340 configured with a keyboard and mouse, a touchscreen, or the like; a display unit 341 configured with a liquid crystal display or the like and provided with a display screen; a storage unit 342 configured to store a variety of data, programs, results of arithmetic operations, results of checks, and the like; and a communication unit 343 configured to send and receive various data externally. First, the storage unit 342 and the communication unit 343 are described. According to the embodiment, the input unit 340 configures the "input unit". Storage unit 342 is configured by a storage device, such as an HDD (hard disk drive) or an SSD (solid-state drive), to store various pieces of information. Storage unit 342 contains an image storage section 342a, a verification information storage section 342b, and a verification result storage section 342c. The image storage section 342a is configured to store the images captured and received by the camera 322. The images stored in the image storage section 342a can be displayed appropriately on the display unit 341. The verification information memory section 342b is configured to store various pieces of information used for the verification of flux 7. For example, verification information memory section 342b stores a variety of thresholds and numerical ranges used to determine defective / non-defective, design data, production data, and the like. The design data and production data include, for example, planned application areas of flux 7 and assembly areas of the electronic components 5. The verification target area KH described above is determined based on the design data and production data. The verification result memory section 342c is configured to store verification result data from a verification regarding the application status of flux 7, performed by the determination section 337. Verification result memory section 342c also stores, for example, statistical data obtained through stochastic and statistical processing of the verification result data. This verification result data and statistical data can be displayed appropriately on the display unit 341. The communication unit 343, for example, is provided with a communication interface compliant with a communication standard, such as a wired LAN (Local Area Network) and a wireless LAN, and is configured to send and receive various data externally. For example, results of a check performed by the determination section 337 are output externally via the communication unit 343. Results of a check performed by the post-reflow inspection device 15 are input via the communication unit 343. The following describes the details of the above respective functional sections of the control device 33. More specifically, the following first describes the motion mechanism control device 338 and the transmission mechanism control device 339, and then the main control device 331 and the other functional sections. The motion mechanism control unit 338 is a functional section for driving and controlling the X-axis motion mechanism 323 and the Y-axis motion mechanism 324 and is configured to control the position of the inspection unit 32 based on a command signal from the main control unit 331. The motion mechanism control unit 338 drives and controls the X-axis motion mechanism 323 and the Y-axis motion mechanism 324 to move the inspection unit 32 to a position above any inspection target area KH in the printed circuit board 1, which is positioned and fixed at the inspection location. The inspection unit 32 is moved sequentially to a plurality of inspection target areas KH defined in the printed circuit board 1 and sequentially performs inspections with respect to the plurality of inspection target areas KH.This implements a check for flux 7 in all check target areas KH. The transfer mechanism control unit 339 is a functional section for driving and controlling the transfer mechanism 31 and is configured to control the transfer position of the printed circuit board 1 based on a command signal from the main control unit 331. The following describes the main control unit 331 and the other functional sections. The main control unit 331 is a functional section for controlling the entire flux application state verification device 12 and is configured to send and receive a variety of signals to and from other functional sections, including the lighting control unit 332 and the camera control unit 333. The lighting control unit 332 is a functional section for driving and controlling the lighting device 321. The lighting control unit 332 is configured to perform, for example, timing control with respect to the emission of light and stopping of emission from the lighting device 321 towards the circuit board 1 based on a command signal from the main control unit 331. The camera control unit 333 is a functional section for driving and controlling the camera 322. The camera control unit 333 is configured, for example, to control the timing of an imaging operation of the camera 322 based on a command signal from the main control unit 331. Image import section 334 is a functional section for importing the luminance image captured and received by camera 322. Each of the images imported by image import section 334 is stored in image storage section 342a. The first specification section 335 is configured to specify each electrode region DR that identifies an existing region of the electrode 3 in the printed circuit board 1 (as seen in Fig. 11 and Fig. 13) based on the luminance image. More specifically, the first specification section 335 uses the numerical ranges stored in the verification information memory section 342b to extract any dark section (any exposed electrode 3e) and any intermediate luminance section (a section where the flux 7 is present on the electrode 3) in the luminance image. The first specification section 335 then specifies the extracted dark section and intermediate luminance section as the electrode region DR.The electrode area DR marks the position where the electrode 3 is located and serves as a verification area to determine whether the flux 7 has been applied appropriately. According to the embodiment, a process of specifying the electrode area DR by the first specification section 335 corresponds to the “first specification process”. The second specification section 336 is configured to perform at least one of the following specifications: specifying the intermediate luminance section of the luminance image located in the electrode region DR as a flux application region FR, which designates an area with the flux 7 applied thereon (as seen in Fig. 11 and Fig. 13), and specifying the dark section of the luminance image located in the electrode region DR as an electrode exposure region RR, which designates an area with the electrode 3 exposed thereon (as seen in Fig. 13), based on the luminance image. According to the embodiment, the second specification section 336 specifies the flux application region FR based on the luminance image. In the process of specifying the flux application area FR, the second specification section 336 uses the numerical ranges stored in the verification information memory section 342b to extract any intermediate luminance section (gray area) in the luminance image. The second specification section 336 then specifies a region located in the electrode area DR within the extracted dark area (gray area) as the flux application area FR. According to the embodiment, a process of specifying the flux application area FR by the second specification section 336 corresponds to the “second specification process”. The determination section 337 performs a check on the flux 7 applied to the printed circuit board 1, based on the flux application area FR specified by the second specification section 336. More specifically, the determination section 337 calculates an area (the number of pixels according to this embodiment) of the flux application area FR with respect to each electrode area DR. According to a modification, the determination section 337 can calculate a total area of ​​all flux application areas FR located within the check target area KH. Determination section 337 then compares the calculated area of ​​each flux application area FR with an area threshold value that is pre-stored in the verification information memory section 342b. If the area of ​​at least one flux application area FR is equal to or less than the area threshold value, determination section 337 determines that the application of the flux 7 to at least one electrode 3 is insufficient, thereby determining the application condition of the flux 7 as "defective". Conversely, if the calculated areas of all flux application areas FR are greater than the area threshold value, determination section 337 determines that the flux 7 is adequately applied to all of the plurality of electrodes 3 corresponding to an electronic component 5, thereby determining the application condition of the flux 7 as "not defective".In the modified configuration of determination section 337, which calculates the total area of ​​all flux application areas FR located within the verification target area KH, determination section 337 compares the calculated total area with an area threshold to perform the faulty / non-faulty determination. Determination Section 337 performs the above determination with respect to all inspection target areas KH. If the flux 7 application state is determined to be "defective" with respect to at least one inspection target area KH, Determination Section 337 determines that the printed circuit board 1, as an inspection object, has a "defective" flux 7 application state. Conversely, if the flux 7 application state is determined to be "not defective" with respect to all inspection target areas KH as a result of the above determination for all inspection target areas KH, Determination Section 337 determines that the printed circuit board 1, as an inspection object, has a "not defective" flux 7 application state. The defective / not defective determination results (inspection result data) are stored in Inspection Result Memory Section 342c.According to the embodiment, a process of initiating the determination section 337 to perform the determination of faulty / non-faulty with respect to the application state of the flux 7 corresponds to the “determination process”. As described in detail above, according to the embodiment, the illumination device 321 illuminates the circuit board 1 with visible light that has the same color as the base material section 6 of the circuit board 1, at an angle of incidence θ of not less than 55 degrees and not more than 75 degrees. The configuration of the embodiment accordingly obtains the luminance image that includes the electrode 3 (the illuminated electrode 3e), which is visible as a dark section, the base material section 6, which is visible as a light section, and the section where the flux 7 is present on the electrode 3, which is visible as an intermediate luminance section. The first specification section 335 specifies the dark area and the intermediate luminance area in the luminance image as the electrode area DR. Consequently, the first specification section 335 can specify the electrode area DR, i.e., a verification area, as an object for determining whether the flux 7 has been applied appropriately, more precisely and easily. This reduces the processing load associated with defining the verification area and thus improves verification efficiency. Furthermore, this configuration allows the verification area (the electrode area DR) to be specified without using any marker provided as a reference on the printed circuit board 1.This even more effectively prevents a reduction in the accuracy of the verification that accompanies a change in the position of the reference caused by a change in the shape of the printed circuit board 1 (for example, a warping, contraction or expansion of the printed circuit board 1). In contrast, the second specification section 336 specifies the intermediate luminance section of the luminance image, which is located in the electrode region DR, as the flux application region FR. Accordingly, this configuration allows the flux application region FR, i.e., a region that characterizes the application state of the flux 7 to the electrode 3, to be specified even more precisely and easily. This configuration, precisely specifying the electrode area DR, which corresponds to a verification area, and the flux application area FR, which indicates the application state of the flux 7, provides the high accuracy of a verification in determining faulty / non-faulty by the determination section 337. Accordingly, this configuration ensures sufficient accuracy of the verification even in the case of a verification with respect to the printed circuit board 1, which is provided with a multitude of electrodes 3 arranged at extremely small intervals (for example, a printed circuit board with a BGA mounted on it). Furthermore, the configuration of the embodiment sets the angle of incidence θ such that it is no less than 60 degrees and no more than 75 degrees, making it less likely that the light uniformly reflected from the electrode 3 will reach the camera 322. This configuration provides a more pronounced difference between the luminance value of the exposed electrode 3e and the luminance value of the electrode 3 with the flux 7 applied to it in the luminance image. Consequently, this allows the flux application area FR to be specified even more precisely in the luminance image, thereby further improving the accuracy of the inspection. The present disclosure is not limited to the description of the embodiment above, but can, for example, be implemented by configurations described below. The present disclosure can, of course, also be implemented by applications and modifications other than those illustrated below. (a) According to the embodiment described above, the base material section 6 of the printed circuit board 1 is green. However, the base material section 6 can be red or brown. The color (wavelength) of the visible light emitted by the lighting device 321 is adjusted according to the color of the base material section 6. (b) According to one modification, the lighting device 321 can have a function of changing (adjusting) the wavelength of the visible light emitted towards the circuit board 1. In this modification, the lighting control device 332 can be configured to control the wavelength of the light emitted by the lighting device 321. According to another modification, the input unit 340 can be configured to input the color (color-related information) of the base material section 6 of the printed circuit board 1. The lighting control unit 332 can be configured to control the wavelength of the light emitted by the lighting device 321 based on the color input by the input unit 340. In this modified configuration, the lighting control unit 332 can be configured to automatically control the wavelength of the light emitted by the lighting device 321, as described below. In one example, if the color input by the input unit 340 is green (if the color information corresponds to green), the lighting control unit 332 can be configured to adjust the wavelength of the light emitted by the lighting device 321 so that it is not lower than 520 nm and not higher than 530 nm. In another example, if the color input by the input unit 340 is red or brown (if the color information corresponds to red or brown), the lighting control unit 332 can be configured to adjust the wavelength of the light emitted by the lighting device 321 so that it is not lower than 625 nm and not higher than 635 nm. The configuration of an automatic and appropriate adjustment of the wavelength of the irradiation light according to the color of the base material section 6, as described above, ensures even greater accuracy of the inspection and further improves the ease of inspection. In this modified configuration, the illumination control device 332 corresponds to the "wavelength control device". (c) According to the embodiment described above, the second specification section 336 is configured to specify the flux application area FR based on the luminance image. According to a modification, the second specification section 336 can be configured to specify an electrode exposure area RR based on the luminance image. The electrode exposure area RR can be specified, for example, by extracting a dark section (of the exposed electrode 3e) from the luminance image. In the modified configuration of specifying the electrode exposure area RR, the determination section 337 can be configured to perform the determination of faulty / non-faulty with respect to the application state of the flux 7, for example, based on the area of ​​the specified electrode exposure area RR. According to another modification, the second specification section 336 can be configured to specify both the flux application area FR and the electrode exposure area RR. The determination section 337 can be configured to perform the determination of faulty / non-faulty with respect to the application state of the flux 7 based on both specified areas FR and RR. (d) According to the embodiment described above, the determination section 337 is configured to perform a verification of the application state of the flux 7 by comparing the calculated area of ​​the flux application area FR with the area threshold value pre-stored in the verification information memory section 342b. According to a modification, the determination section 337 can be configured to calculate a ratio of the area of ​​the flux application area FR to the area of ​​the electrode area DR and to determine the application state of the flux 7 based on the calculated ratio. The determination section 337 can use any other determination technique (for example, a determination technique based on the shape of the flux application area FR and the shape of the electrode exposure area RR) to determine the application state of the flux 7. (e) According to the embodiment described above, the printed circuit board 1 is configured with a glass-epoxy substrate. However, the printed circuit board 1 can be configured with a different type of substrate. For example, the printed circuit board 1 can be configured with a ceramic substrate. (f) According to the embodiment described above, a BGA is used as an example of the electronic component 5. However, the electronic component 5 can be a different semiconductor package (for example, a CSP (Chip Size Package)). (g) According to the embodiment described above, the flux 7 is configured to individually cover the plurality of electrodes 3 that constitute an electrode group 3x. However, according to a modification, the flux 7 can be configured to collectively cover all of these electrodes 3. Reference symbol list 1... printed circuit board (PCB), 3... electrode, 6... base material section, 7... flux, 12... flux application condition check device, 321... illumination device (irradiation unit), 322... camera (imaging unit), 332... illumination control device (wavelength control device), 335... first specification section (first specification unit), 336... second specification section (second specification unit), 337... determination section (determination unit), 340... input unit (input unit), DR... electrode area, FR... flux application area, RR... electrode exposure area QUOTES INCLUDED IN THE DESCRIPTION This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature JP 2010-271165A

[0006] JP ​​2005-286309A

[0006]

Claims

Flux application condition verification device configured to perform a verification of a transparent or translucent flux applied to an electrode of a printed circuit board containing a base material section of a green, red, or brown color, wherein the flux application condition verification device comprises: an irradiation unit configured to irradiate the printed circuit board with visible light of an identical color to the color of the base material section of the printed circuit board at an angle of incidence of not less than 55 degrees and not more than 75 degrees;an imaging unit positioned above the printed circuit board such that an optical axis of the imaging unit is orthogonal to the printed circuit board, and configured to capture an image of light emitted from the irradiation unit onto the printed circuit board and reflected from the printed circuit board to obtain a luminance image that includes the electrode, which is seen as a dark section; the base material section, which is seen as a bright section having a higher luminance value than the dark section; and a section where the flux is present on the electrode, which is seen as an intermediate luminance section having an intermediate luminance value between the dark section and the bright section;a first specification unit configured to specify the dark section and the intermediate luminance section in the luminance image as an electrode region, indicating an existing area of ​​the electrode, on the printed circuit board; a second specification unit configured to perform at least one of the specifications: specifying the intermediate luminance section of the luminance image located in the electrode region as a flux deposition region, indicating an area where the flux is applied to the electrode, and specifying the dark section of the luminance image located in the electrode region as an electrode exposure region, indicating an area where the electrode is exposed;and a determination unit configured to perform a determination of faulty / non-faulty with respect to a flux application state on the electrode based on at least one of the areas, flux application area and electrode exposure area, specified by the second specification unit. Flux application condition verification device according to claim 1, wherein the angle of incidence of the light emitted from the irradiation unit onto the circuit board is adjusted such that it is not less than 60 degrees and not more than 75 degrees. Flux application condition verification device according to claim 1, further comprising: an input unit configured to input the color of the base material section of the printed circuit board;and a wavelength control device configured to automatically control a wavelength of visible light emitted by the irradiation unit based on the color input by the input unit, wherein if the color input by the input unit is green, the wavelength control device is configured to set the wavelength of the light emitted by the irradiation unit so that it is not lower than 520 nm and not higher than 530 nm, and if the color input by the input unit is red or brown, the wavelength control device is configured to set the wavelength of the light emitted by the irradiation unit so that it is not lower than 625 nm and not higher than 635 nm. Flux application condition verification method for performing a verification of a transparent or translucent flux applied to an electrode of a printed circuit board containing a base material section of a green, red, or brown color, wherein the flux application condition verification method comprises: an irradiation process of irradiating the printed circuit board with a visible light of an identical color to the color of the base material section of the printed circuit board, at an angle of incidence of not less than 55 degrees and not more than 75 degrees;an imaging process of using an imaging unit placed above the printed circuit board such that an optical axis of the imaging unit is orthogonal to the printed circuit board to capture an image of light emitted onto the printed circuit board in the irradiation process and reflected from the printed circuit board to obtain a luminance image that includes the electrode, which can be seen as a dark section; the base material section, which can be seen as a bright section having a higher luminance value than the luminance value of the dark section; and a section where the flux is present on the electrode, which can be seen as an intermediate luminance section having an intermediate luminance value between the luminance value of the dark section and the luminance value of the bright section;a first specification process of specifying the dark section and the intermediate luminance section in the luminance image as an electrode region, which designates an existing area of ​​the electrode, in the printed circuit board; a second specification process of performing at least one of the specifications, specifying the intermediate luminance section of the luminance image, which is located in the electrode region, as a flux deposition region, which designates an area where the flux is applied to the electrode, and specifying the dark section of the luminance image, which is located in the electrode region, as an electrode exposure region, which designates an area where the electrode is exposed;and a determination process of performing a determination of defective / non-defective with respect to a flux application state on the electrode based on at least one of the areas, flux application area and electrode exposure area, specified in the second specification process.

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