Flux coating state inspection device and flux coating state inspection method

Abstract

To provide a flux coating state inspection device or the like, capable of obtaining a good inspection accuracy while enabling the inspection region setting with relatively simple processing.SOLUTION: A flux coating state inspection device 12 comprises: an illumination device 321 that can irradiate a visible light of which a color is similar to a basic material part of a substrate at a large incident angle; a camera 322 that images a light obtained by reflecting the substrate while being irradiated to the substrate from the illumination device 321; a first specific part 335 that specifies a dark part of a luminance image obtained by the camera 322 and an intermediate luminance part as an electrode region; and a second specific part 336 that specifies the intermediate luminance part positioned in the electrode region as a flux coating region, and / or specifies the dark part positioned in the electrode region as an electrode exposure region. By a determination part 337, a quality determination in accordance with a coating state of a flux against the electrode is performed on the basis the flux coating region and / or the electrode exposure region that are / is specified by the second specific part 336.SELECTED DRAWING: Figure 9

Description

[Technical field]

[0001] The present invention relates to an inspection device and an inspection method for inspecting the state of flux applied to a board. [Background technology]

[0002] Generally, when mounting electronic components on a printed circuit board, cream solder is first printed on the electrodes arranged on the printed circuit board. Next, the electronic components are temporarily attached to the printed circuit board on which the cream solder is printed, based on the viscosity of the cream solder. After the electronic components are temporarily attached, the printed circuit board is introduced into a reflow furnace, and soldering is performed by going through a predetermined reflow process.

[0003] Furthermore, in order to achieve miniaturization and suppression of mounting defects, a semiconductor package with a plurality of spherical bumps (solder balls) regularly arranged on the bottom surface, such as a ball grid array (BGA), has been proposed as an electronic component. When mounting such a semiconductor package as an electronic component on a printed circuit board, it is sufficient to place the bumps on the electrodes, and there is no need to print cream solder. However, when mounting such a semiconductor package on a printed circuit board, it is preferable to apply flux to the electrodes in order to increase the wettability of the solder before placing the bumps on the electrodes.

[0004] Here, if the flux is applied to the electrodes in an inappropriate state, there is a risk of problems such as insufficient bonding strength of the electronic component to the printed circuit board. Therefore, it is preferable to inspect the flux application state before placing the electronic component on the printed circuit board. As an inspection device for inspecting the flux application state, there is known one that inspects the flux application state by comparing the flux photographed by an imaging device with the pattern-recognized electrodes (circuit pattern) (see, for example, Patent Document 1, etc.).

[0005] Incidentally, in the inspection device described in the above Patent Document 1, the area of ​​the applied flux is set to be larger than the entire area of ​​the electrode (printed circuit), and the flux is opaque. Therefore, although it is possible to photograph the flux with a camera, it is not possible to photograph the electrode (printed circuit) to which the flux is applied. Therefore, in the inspection, the applied state of the flux is inspected by using, as the inspection area, not the actual electrode but only the pattern-recognized electrode, that is, by using the virtually estimated area of ​​the electrode. Therefore, in order to ensure sufficient inspection accuracy, it is necessary to set an appropriate inspection area to match the position of the actual electrode.

[0006] Here, as a method for setting an appropriate inspection area that matches the actual position of the electrodes, for example, a method using marks provided on a printed circuit board as a reference can be considered (for example, see Patent Document 2, etc.). [Prior art documents] [Patent documents]

[0007] [Patent Document 1] JP 2010-271165 A [Patent Document 2] JP 2005-286309 A Summary of the Invention [Problem to be solved by the invention]

[0008] However, when using marks as references, when inspecting a printed circuit board on which a plurality of electrodes are provided at an extremely small pitch (for example, a printed circuit board on which a semiconductor package such as a BGA is mounted), extremely high-precision processing may be required to set an appropriate inspection area. Such high-precision processing increases the processing load and ultimately reduces the inspection efficiency.

[0009] On the other hand, if the processing is simplified to reduce the processing burden, a "deviation" is more likely to occur between the test area and the actual electrode position, and as a result, there is a risk that sufficient test accuracy cannot be ensured.

[0010] The present invention has been made in consideration of the above-mentioned circumstances, and an object of the present invention is to provide a flux application state inspection device and the like that can obtain good inspection accuracy while enabling the inspection area to be set through relatively simple processing. [Means for solving the problem]

[0011] The following describes each of the means suitable for achieving the above object. Note that, as necessary, the specific effects of the corresponding means will be added.

[0012] Means 1. A flux application state inspection device for inspecting transparent or translucent flux applied to electrodes on a substrate having a green, red, or brown base portion, comprising: an irradiation means capable of irradiating the substrate with visible light of the same color as the color of the base portion of the substrate at an incident angle of 55° or more and 75° or less; an imaging means arranged above the substrate with its optical axis perpendicular to the substrate, capable of imaging light irradiated from the irradiating means onto the substrate and reflected by the substrate to obtain a luminance image in which the electrode becomes a dark portion, the base portion becomes a bright portion having a higher luminance than the dark portion, and a portion on the electrode where flux is present becomes an intermediate luminance portion having a luminance intermediate between the luminance of the dark portion and the bright portion; a first identification means for identifying the dark areas and the intermediate luminance areas in the luminance image as electrode areas indicative of areas where the electrodes are present on the substrate; a second identification means configured to be capable of at least one of identifying the intermediate luminance portion of the luminance image located within the electrode region as a flux-coated region indicating a region where flux is coated on the electrode, and identifying the dark portion of the luminance image located within the electrode region as an electrode-exposed region indicating a region where the electrode is exposed; and and a determination means for determining whether the flux applied to the electrode is good or bad based on at least one of the flux application area and the electrode exposed area identified by the second identification means.

[0013] According to the above-mentioned means 1, the irradiation means irradiates the substrate with visible light of the same color as the substrate of the substrate at an incident angle of 55° to 75°. Since the visible light of the same color as the substrate of the substrate is irradiated, the visible light is reflected (diffusely reflected) by the substrate of the substrate. Furthermore, since the light is incident on the substrate from the irradiation means at a relatively large incident angle, the light reflected regularly by the electrode (exposed electrode) to which no flux is applied is unlikely to reach the imaging means, whereas the light reflected by the electrode to which flux is applied is likely to reach the imaging means because the light is diffusely reflected by the flux. Therefore, in the luminance image obtained by the imaging means, the electrode becomes a dark area, the substrate becomes a bright area with a higher luminance than the dark area, and the part where the flux is present on the electrode becomes an intermediate luminance area having a luminance intermediate between the luminance of the dark area and the bright area.

[0014] The first identifying means identifies the dark and intermediate luminance areas in the luminance image as electrode areas indicating areas where electrodes are present on the board. Therefore, the electrode areas, i.e., the inspection areas that are the targets of judgment as to whether or not the flux is properly applied, can be identified more accurately and more easily. This reduces the processing load associated with setting the inspection areas, and thus improves inspection efficiency. In addition, since the inspection areas (electrode areas) can be identified without using references such as marks provided on the board, it is possible to more reliably prevent a decrease in inspection accuracy due to a change in the position of the reference caused by a change in the shape of the board (e.g., warping, shrinkage, or expansion).

[0015] On the other hand, the second identifying means identifies intermediate luminance parts and / or dark parts of the luminance image located within the electrode region as the flux-coated region and / or the electrode-exposed region, and therefore it is possible to more accurately and easily identify the flux-coated region and the electrode-exposed region, which are regions that represent the state of flux application to the electrode.

[0016] The determining means then performs a pass / fail determination on the state of flux application on the electrodes based on at least one of the flux-applied area and the electrode-exposed area identified by the second identifying means. As described above, the electrode area corresponding to the inspection area can be accurately identified, and the flux-applied area and the electrode-exposed area located within this electrode area can also be accurately identified, so that good inspection accuracy can be obtained in the pass / fail determination by the determining means. As a result, sufficient inspection accuracy can be ensured even when inspecting a board on which multiple electrodes are provided at an extremely small pitch (for example, a board on which a BGA is mounted).

[0017] Means 2. The flux application state inspection device according to Means 1, characterized in that the angle of incidence of the light irradiated from the irradiating means to the board is set to 60° or more and 75° or less.

[0018] According to the above-mentioned means 2, since the light specularly reflected by the electrode is less likely to reach the imaging means, the difference in brightness between the exposed electrode and the electrode to which the flux is applied can be made larger in the brightness image. As a result, the electrode exposed area and the flux-applied area can be more accurately identified from the brightness image, and the inspection accuracy can be further improved.

[0019] In order to further improve the inspection accuracy, it is more preferable to set the angle of incidence of light from the irradiation means to the substrate at 60° or more and 70° or less.

[0020] Means 3. An input means for inputting the color of the base part of the substrate; a wavelength control means for automatically controlling a wavelength of the visible light irradiated from the irradiating means based on the color input by the input means, The wavelength control means When the color input by the input means is green, the wavelength of the light irradiated from the irradiation means is set to 520 nm or more and 530 nm or less; The flux application state inspection device according to the first means, characterized in that when the color input by the input means is red or brown, the wavelength of the light irradiated from the irradiation means is set to 625 nm or more and 635 nm or less.

[0021] According to the above-mentioned means 3, by inputting the color (information about the color) of the base part of the board by the input means, the wavelength of the light irradiated from the irradiation means can be automatically set to an appropriate value that matches the color of the base part. Therefore, it is possible to more reliably obtain good inspection accuracy and further increase the convenience of the inspection.

[0022] Means 4. A method for inspecting a transparent or translucent flux applied to an electrode on a substrate having a green, red, or brown base, comprising the steps of: an irradiation step of irradiating the substrate with visible light of the same color as the color of the base portion of the substrate at an incident angle of 55° or more and 75° or less; an imaging step of imaging the light irradiated to the substrate in the irradiation step and reflected from the substrate by an imaging means disposed above the substrate with its optical axis perpendicular to the substrate, thereby obtaining a luminance image in which the electrode becomes a dark portion, the base portion becomes a bright portion having a higher luminance than the dark portion, and a portion on the electrode where flux is present becomes an intermediate luminance portion having a luminance intermediate between the luminance of the dark portion and the bright portion; a first identification step of identifying the dark areas and the intermediate luminance areas in the luminance image as electrode areas indicative of areas where the electrodes are present on the substrate; a second identification step of performing at least one of identifying the intermediate luminance portion of the luminance image located within the electrode region as a flux-coated region indicating a region where flux is applied to the electrode, and identifying the dark portion of the luminance image located within the electrode region as an electrode-exposed region indicating a region where the electrode is exposed; and a determination step of determining whether the state of flux applied to the electrode is good or bad based on at least one of the flux application area and the electrode exposed area identified in the second identification step.

[0023] According to the above-mentioned fourth aspect, the same effects as those of the above-mentioned first aspect can be achieved.

[0024] In addition, the technical matters related to each of the above means may be combined as appropriate. Therefore, for example, the technical matters related to the above means 2 may be combined with the technical matters related to the above means 3. In addition, at least one of the technical matters related to the above means 2 and 3 may be applied to the above means 4. [Brief description of the drawings]

[0025] [Figure 1] FIG. 2 is a schematic plan view of a printed circuit board. [Diagram 2] FIG. 2 is a schematic plan view of a printed circuit board with electronic components and the like omitted in order to show electrodes. [Diagram 3] FIG. 2 is a partially enlarged schematic cross-sectional view of a printed circuit board. [Figure 4] FIG. 2 is a schematic perspective view of an electronic component. [Diagram 5] FIG. 4 is a partially enlarged cross-sectional view showing an electronic component and the like before being mounted on an electrode. [Figure 6] FIG. 1 is a block diagram showing a configuration of a manufacturing line for printed circuit boards. [Figure 7] FIG. 2 is a partially enlarged schematic plan view of a printed circuit board showing flux applied to electrodes, etc. [Figure 8] FIG. 1 is a schematic diagram showing a flux application state inspection device; [Figure 9] FIG. 2 is a block diagram showing a functional configuration of a flux inspection state inspection device. [Figure 10] FIG. 2 is a partially enlarged schematic plan view of a printed circuit board in which all of the electrodes constituting an electrode group are appropriately covered with flux. [Figure 11] FIG. 2 is a schematic diagram showing a luminance image in a case where all of a plurality of electrodes constituting one electrode group are appropriately covered with flux. [Figure 12] 1 is a partially enlarged schematic plan view of a printed circuit board in which some of the electrodes are not properly covered with flux and are exposed. FIG. [Figure 13] 13 is a schematic diagram showing a luminance image in a case where some of the electrodes are not properly covered with flux and are exposed. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0026] An embodiment will be described below with reference to the drawings. First, the configuration of a printed circuit board as a substrate will be described.

[0027] 1 to 3, printed circuit board 1 (hereinafter simply referred to as "board 1") is a so-called glass epoxy board, in which electrodes 3 (not shown in FIG. 1) made of copper foil are formed on a flat base substrate 2 made of glass epoxy resin or the like. Electronic components 5 such as chips are mounted on electrodes 3 via cream solder 4 (hereinafter simply referred to as "solder 4") made by kneading solder particles with flux.

[0028] The area of ​​the base substrate 2 other than the electrodes 3 and the circuit pattern (electrode pattern) is a base portion 6 made of glass epoxy, resist, or the like, and is green in this embodiment.

[0029] Furthermore, as shown in FIG. 4, the electronic component 5 in this embodiment is a so-called ball grid array (BGA) having a plurality of bumps 4a regularly arranged on its bottom surface. Each bump 4a melts in a reflow process in a reflow device 14 described later and spreads over the surface of the electrode 3, eventually forming the solder 4. The base substrate 2 has an electrode group 3x (see FIG. 2) consisting of a plurality of electrodes 3 on which each bump 4a of one electronic component 5 is to be mounted, and when the electronic component 5 is mounted on the base substrate 2, each bump 4a is mounted on each electrode 3 constituting the electrode group 3x. In this embodiment, the base substrate 2 has a plurality of (for example, four) electrode groups 3x, and one electronic component 5 is mounted on each electrode group 3x. In this embodiment, the pitch of the plurality of electrodes 3 constituting one electrode group 3x is very small (for example, 1.8 mm or less or 0.5 mm or less).

[0030] 5, before electronic components 5 are mounted on an electrode group 3x, flux 7 is applied to the surfaces of the electrodes 3 constituting the electrode group 3x in advance. The flux 7 is used to remove metal oxide films on the electrodes 3, electronic components 5, and solder 4, and to enhance the wettability of the solder 4. The flux 7 is transparent or semi-transparent and difficult to see. In this embodiment, the flux 7 covers each of the electrodes 3 constituting one electrode group 3x individually.

[0031] Next, a description will be given of the manufacturing line (manufacturing process) for manufacturing the board 1. As shown in Fig. 6, the manufacturing line 10 is provided with, in order from the upstream side (upper side in Fig. 6), a flux application device 11, a flux application state inspection device 12, a component mounter 13, a reflow device 14, and a post-reflow inspection device 15. The board 1 is set up to be transported to these devices in this order.

[0032] The flux applicator 11 applies the flux 7 to at least the surface of the electrode 3 on the substrate 1. For example, the flux applicator 11 places a predetermined mask on the substrate 1 and applies the flux 7 to the surface of the electrode 3 by using screen printing. In this embodiment, as shown in FIG. 7, the flux applicator 11 applies the flux 7 so as to cover each of the electrodes 3 constituting one electrode group 3x. FIGS. 7, 10, and 12 are partial enlarged schematic plan views of the substrate 1. In these figures, the flux 7 is shaded for convenience of illustration. However, since the flux 7 is transparent or translucent, it is not easy to clearly see the applied area of ​​the flux 7 by visual inspection. The flux applicator 11 may apply the flux 7 by a predetermined dispenser.

[0033] The flux application state inspection device 12 inspects the application state of the flux 7 applied to the electrodes 3. The flux application state inspection device 12 will be described later.

[0034] The component mounter 13 performs a component mounting process (mounting process) of mounting the electronic component 5 on the electrodes 3, etc. As a result, the electronic component 5 is placed on the electrode group 3x via the bumps 4a.

[0035] The reflow device 14 performs a reflow process for heating and melting the bumps 4a, etc. In the substrate 1 that has undergone the reflow process, the bumps 4a melt and spread over the surfaces of the electrodes 3, and finally solidify to become the solder 4. Then, the electrodes 3 and the electronic components 5 are joined by the solder 4.

[0036] The post-reflow inspection device 15 performs a post-reflow inspection process to inspect whether or not the solder joint has been properly performed in the reflow process. For example, the post-reflow inspection device 15 inspects whether or not there is any misalignment in the electronic components 5 using image data of the board 1 after the reflow process.

[0037] In addition, although not shown in the figures, the manufacturing line 10 is provided with conveyors or the like for transporting the board 1 between the above-mentioned devices, such as between the flux application device 11 and the flux application state inspection device 12. Also, branching devices are provided between the flux application state inspection device 12 and the component mounter 13 and downstream of the post-reflow inspection device 15. The board 1 determined to be a non-defective product by the flux application state inspection device 12 or the post-reflow inspection device 15 is guided directly downstream, while the board 1 determined to be a defective product by at least one of the inspection devices 12, 15 is discharged by the branching device to a defective product storage section (not shown).

[0038] Next, a description will be given of the configuration of the flux application state inspection device 12. As shown in Fig. 8 and Fig. 9, the flux application state inspection device 12 includes a transport mechanism 31 which transports and positions the substrate 1, an inspection unit 32 which inspects the flux 7, and a control device 33 which controls the driving of the transport mechanism 31 and the inspection unit 32, as well as performs various controls, image processing, and arithmetic processing in the inspection device 12.

[0039] The transport mechanism 31 includes a pair of transport rails 31a arranged along the direction in which the substrate 1 is carried in and out, and an endless conveyor belt 31b rotatably disposed on each of the transport rails 31a. Although not shown, the transport mechanism 31 also includes a driving means such as a motor for driving the conveyor belt 31b, and a chuck mechanism for positioning the substrate 1 at a predetermined position. The transport mechanism 31 is driven and controlled by a control device 33 (a transport mechanism control unit 339 described later).

[0040] Under the above configuration, the board 1 carried into the flux coating state inspection device 12 has both side edges in the width direction perpendicular to the carrying-in / out direction inserted into the conveyor rails 31a, and is placed on the conveyor belt 31b. Then, the conveyor belt 31b starts to operate, and the board 1 is carried to a predetermined inspection position. When the board 1 reaches the inspection position, the conveyor belt 31b stops and the chuck mechanism is operated. The operation of this chuck mechanism pushes up the conveyor belt 31b, and both side edges of the board 1 are clamped by the conveyor belt 31b and the upper side of the conveyor rail 31a. This positions and fixes the board 1 at the inspection position. When the inspection is completed, the fixation by the chuck mechanism is released and the conveyor belt 31b starts to operate. This causes the board 1 to be carried out of the flux coating state inspection device 12. Of course, the configuration of the conveyor mechanism 31 is not limited to the above embodiment, and other configurations may be adopted.

[0041] The inspection unit 32 is disposed above the transport rail 31a (the transport path for the substrate 1). The inspection unit 32 includes an illumination device 321 and a camera 322. In this embodiment, the illumination device 321 constitutes an "illumination means" and the camera 322 constitutes an "imaging means."

[0042] The inspection unit 32 also includes an X-axis movement mechanism 323 that allows movement in the X-axis direction (left-right direction in FIG. 8) and a Y-axis movement mechanism 324 that allows movement in the Y-axis direction (front-back direction in FIG. 8). Both movement mechanisms 323, 324 are driven and controlled by the control device 33 (a movement mechanism control unit 338 described later).

[0043] The lighting device 321 irradiates the board 1, which is the subject of inspection by the flux application state inspection device 12, with visible light of the same color as the base portion 6 of the board 1. In this embodiment, since the base portion 6 is green, the lighting device 321 irradiates the board 1 with green visible light (for example, light with a wavelength of 520 nm or more and 530 nm or less).

[0044] Moreover, the lighting device 321 irradiates light at an incidence angle θ of 55° or more and 70° or less. In this embodiment in particular, the incidence angle θ of light from the lighting device 321 to the substrate 1 (particularly the inspection target range KH described below) is set to 60° or more and 75° or less. From the viewpoint of improving the inspection accuracy, it is more preferable to set the incidence angle θ to 60° or more and 70° or less. In this embodiment, the process of irradiating the substrate 1 with light from the lighting device 321 corresponds to the "irradiation process".

[0045] The camera 322 is disposed directly above the substrate 1 to be inspected with its optical axis O perpendicular to the substrate 1, and captures an image of an inspection range KH on the substrate 1 from directly above. In this embodiment, the inspection range KH is set in advance for each electronic component 5 to be mounted, and is a range that includes all of the multiple electrodes 3 that make up one electrode group 3x (see FIG. 7).

[0046] The camera 322 is composed of a CCD camera or the like having sensitivity to each light irradiated from the lighting device 321, and its operation is controlled by the control device 33 (a camera control unit 333 described later). The camera 322 captures an image of the light reflected from the substrate 1 in the inspection target range KH under the operation control of the control device 33 while the substrate 1 is being irradiated with light from the lighting device 321. This allows a luminance image of the inspection target range KH to be acquired. The luminance image includes a large number of pixels, each of which has data related to luminance. In this embodiment, the process of using the camera 322 to capture an image of the light irradiated from the lighting device 321 and reflected from the substrate 1 corresponds to the "imaging process".

[0047] In the luminance image, the electrode 3 (exposed electrode) to which the flux 7 is not applied is a dark area. This is because the light is irradiated from the lighting device 321 to the substrate 1 at a relatively large incident angle θ, so that the light specularly reflected from the exposed electrode is less likely to reach the camera 322.

[0048] In the luminance image, the substrate portion 6 appears as a bright portion having a higher luminance than the dark portion (exposed electrode). This is because the visible light irradiated from the lighting device 321 is the same color as the substrate portion 6, and the visible light is reflected (diffusely reflected) by the substrate portion 6 and reaches the camera 322. Even if the flux 7 is applied to the substrate portion 6, the substrate portion 6 appears as a bright portion.

[0049] Furthermore, in the luminance image, the portion where the flux 7 is present on the electrode 3 becomes an intermediate luminance portion (e.g., a gray portion) having an intermediate luminance between the luminance of the dark portion (exposed electrode) and the luminance of the light portion (base material portion 6). This is because the flux 7 causes diffuse reflection of light on the electrode 3 to which the flux 7 is applied, and the light reflected from this electrode 3 easily reaches the camera 322.

[0050] Therefore, when all of the electrodes 3 constituting one electrode group 3x are properly covered with the flux 7 (see, for example, FIG. 10), the base portion 6 appears as a bright portion in the luminance image, and the portion on the electrode 3 where the flux 7 is present appears as a medium luminance portion (gray portion) (see, for example, FIG. 11). On the other hand, when some or all of the electrode 3 is not properly covered with the flux 7 and an exposed electrode 3e that is an exposed electrode 3 exists (see, for example, FIG. 12), the exposed electrode 3e appears as a dark portion in the luminance image (see, for example, FIG. 13).

[0051] The luminance image acquired by the camera 322 is transferred to the control device 33 (an image acquisition unit 334 described below). The control device 33 executes an inspection process regarding the application state of the flux 7 based on the luminance image.

[0052] The control device 33 consists of a computer including a CPU (Central Processing Unit) that executes predetermined arithmetic processing, a ROM (Read Only Memory) that stores various programs and fixed value data, a RAM (Random Access Memory) that temporarily stores various data when executing various arithmetic processing, and peripheral circuits thereof.

[0053] The control device 33 functions as various functional units, such as a main control unit 331, a lighting control unit 332, a camera control unit 333, an image acquisition unit 334, a first identification unit 335, a second identification unit 336, a judgment unit 337, a movement mechanism control unit 338, and a transport mechanism control unit 339, by the CPU operating in accordance with various programs.

[0054] However, the various functional units are realized by the cooperation of various hardware such as the CPU, ROM, RAM, etc., and there is no need to clearly distinguish between functions realized by hardware and functions realized by software, and some or all of these functions may be realized by a hardware circuit such as an IC. In this embodiment, the first identification unit 335 constitutes a "first identification means", the second identification unit 336 constitutes a "second identification means", and the determination unit 337 constitutes a "determination means".

[0055] Furthermore, the control device 33 is provided with an input unit 340 consisting of a keyboard, mouse, touch panel, etc., a display unit 341 having a display screen consisting of a liquid crystal display, etc., a memory unit 342 capable of storing various data and programs, calculation results, inspection results, etc., and a communication unit 343 capable of transmitting and receiving various data to and from the outside. First, the memory unit 342 and the communication unit 343 will be described. In this embodiment, the input unit 340 constitutes the "input means."

[0056] The storage unit 342 is configured with a storage device such as a hard disk drive (HDD) or a solid state drive (SSD), and stores various information. The storage unit 342 includes an image storage unit 342a, an inspection information storage unit 342b, and an inspection result storage unit 342c.

[0057] The image storage unit 342a stores images captured and acquired by the camera 322. The images stored in the image storage unit 342a can be displayed on the display unit 341 as appropriate.

[0058] The inspection information storage unit 342b stores various information used in the inspection of the flux 7. For example, the inspection information storage unit 342b stores various thresholds and numerical ranges used when determining pass / fail, design data, manufacturing data, etc. The design data and manufacturing data include a planned application area of ​​the flux 7 and a mounting area of ​​the electronic components 5, and the inspection target range KH is set based on the design data and manufacturing data.

[0059] The inspection result storage unit 342c stores inspection result data relating to the application state of the flux 7 by the determination unit 337. The inspection result storage unit 342c also stores statistical data obtained by statistically processing the inspection result data. These inspection result data and statistical data can be displayed on the display unit 341 as appropriate.

[0060] The communication unit 343 includes a communication interface conforming to a communication standard such as a wired LAN (Local Area Network) or a wireless LAN, and is configured to be able to transmit and receive various data to and from the outside. For example, the result of the inspection performed by the determination unit 337 is output to the outside via the communication unit 343, and the result of the inspection performed by the post-reflow inspection device 15 is input via the communication unit 343.

[0061] Next, a detailed description will be given of the above-mentioned various functional units constituting the control device 33. First, the movement mechanism control unit 338 and the transport mechanism control unit 339 will be described, and then the main control unit 331 and the like will be described.

[0062] The movement mechanism control unit 338 is a functional unit that drives and controls the X-axis movement mechanism 323 and the Y-axis movement mechanism 324, and controls the position of the inspection unit 32 based on a command signal from the main control unit 331. The movement mechanism control unit 338 drives and controls the X-axis movement mechanism 323 and the Y-axis movement mechanism 324, thereby moving the inspection unit 32 to a position above any inspection target range KH on the substrate 1 that is positioned and fixed at the inspection position. Then, the inspection unit 32 is moved sequentially to a plurality of inspection target ranges KH set on the substrate 1, and inspections related to the inspection target ranges KH are performed, thereby performing inspection of the flux 7 in all of the inspection target ranges KH.

[0063] The transport mechanism control unit 339 is a functional unit that controls the drive of the transport mechanism 31 , and controls the transport position of the substrate 1 based on a command signal from the main control unit 331 .

[0064] Next, a description will be given of the main control unit 331 etc. The main control unit 331 is a functional unit that controls the entire flux application state inspection device 12, and is configured to be able to transmit and receive various signals to and from other functional units such as a lighting control unit 332 and a camera control unit 333.

[0065] The illumination control unit 332 is a functional unit that controls the driving of the illumination device 321. Based on a command signal from the main control unit 331, the illumination control unit 332 performs timing control regarding the start and end of irradiation of light from the illumination device 321 to the substrate 1.

[0066] The camera control unit 333 is a functional unit that drives and controls the camera 322. The camera control unit 333 controls the timing of the imaging operation in the camera 322 based on a command signal from the main control unit 331.

[0067] The image capture unit 334 is a functional unit for capturing luminance images captured and acquired by the camera 322. Each image captured by the image capture unit 334 is stored in the image storage unit 342a.

[0068] The first identifying unit 335 identifies an electrode region DR (see FIGS. 11 and 13) indicating an area where the electrode 3 exists on the substrate 1 based on the luminance image. More specifically, the first identifying unit 335 extracts a dark area (exposed electrode 3e) and an intermediate luminance area (a portion where the flux 7 exists on the electrode 3) in the luminance image by utilizing a numerical range stored in the inspection information storage unit 342b. Then, the first identifying unit 335 identifies the extracted dark area and intermediate luminance area as the electrode region DR. The electrode region DR indicates the location where the electrode 3 exists, and functions as an inspection area that is the target of judgment as to whether the flux 7 is appropriately applied or not. In this embodiment, the process of identifying the electrode region DR by the first identifying unit 335 corresponds to the "first identifying process".

[0069] The second identification unit 336 performs at least one of identifying an intermediate luminance portion of the luminance image located within the electrode region DR, based on the luminance image, as a flux-coated region FR (see FIGS. 11 and 13) indicating a region where the electrode 3 is coated with flux 7, and identifying a dark portion of the luminance image located within the electrode region DR as an electrode-exposed region RR (see FIG. 13) indicating a region where the electrode 3 is exposed. In this embodiment, the second identification unit 336 identifies the flux-coated region FR, based on the luminance image.

[0070] In identifying the flux-coated region FR, the second identifying unit 336 extracts a medium luminance portion (gray portion) in the luminance image by using the numerical range stored in the inspection information storage unit 342b. Then, the second identifying unit 336 identifies a portion of the extracted dark portion (gray portion) that is located within the electrode region DR as the flux-coated region FR. In this embodiment, the process of identifying the flux-coated region FR by the second identifying unit 336 corresponds to the "second identifying process."

[0071] The determination unit 337 inspects the flux 7 applied to the board 1 based on the flux-coated region FR identified by the second identification unit 336. More specifically, the determination unit 337 calculates the area (the number of pixels in this embodiment) of the flux-coated region FR for each electrode region DR. The determination unit 337 may also calculate the total area of ​​all the flux-coated regions FR located within the inspection target range KH.

[0072] Then, the determination unit 337 compares the calculated area of ​​the flux-coated region FR with an area threshold pre-stored in the inspection information storage unit 342b. If the area of ​​at least one flux-coated region FR is equal to or smaller than the area threshold, the determination unit 337 determines that the flux 7 is not sufficiently applied to at least one electrode 3 and determines the application state of the flux 7 as “bad”. On the other hand, if the areas of all the calculated flux-coated regions FR exceed the area threshold, the determination unit 337 determines that the flux 7 is properly applied to the electrodes 3 corresponding to one electronic component 5 and determines the application state of the flux 7 as “good”. If the determination unit 337 calculates the total area of ​​all the flux-coated regions FR located in the inspection target range KH, the determination unit 337 performs the pass / fail determination by comparing the calculated total area with the area threshold.

[0073] Then, the judgment unit 337 performs the above-mentioned judgment on all the inspection target ranges KH, and when the judgment unit 337 judges the application state of the flux 7 to be "bad" in at least one of the inspection target ranges KH, the judgment unit 337 judges the inspection target board 1 to be "bad" in terms of the application state of the flux 7. On the other hand, when the judgment unit 337 performs the above-mentioned judgment on all the inspection target ranges KH and judges the application state of the flux 7 to be "good" in all the inspection target ranges KH, the judgment unit 337 judges the inspection target board 1 to be "good" in terms of the application state of the flux 7. The pass / fail judgment result (inspection result data) is stored in the inspection result storage unit 342c. In this embodiment, the process of the judgment unit 337 making a pass / fail judgment on the application state of the flux 7 corresponds to the "judgment process".

[0074] As described above in detail, according to this embodiment, the lighting device 321 irradiates the substrate 1 with visible light of the same color as the base portion 6 of the substrate 1 at an incident angle θ of 55° or more and 75° or less. Therefore, a luminance image can be obtained in which the electrode 3 (exposed electrode 3e) becomes a dark area, the base portion 6 becomes a bright area, and the portion on the electrode 3 where the flux 7 is present becomes an intermediate luminance area.

[0075] The first identification unit then identifies the dark and intermediate luminance areas in the luminance image as the electrode regions DR. Therefore, the electrode regions DR, i.e., the inspection regions that are the targets of the determination of whether the flux 7 is properly applied, can be identified more accurately and more easily. This reduces the processing load associated with setting the inspection regions, and thus improves the inspection efficiency. In addition, since the inspection regions (electrode regions DR) can be identified without using references such as marks provided on the substrate 1, it is possible to more reliably prevent the inspection accuracy from decreasing due to the positional fluctuation of the reference caused by the shape change of the substrate 1 (e.g., warping, shrinkage, and expansion).

[0076] On the other hand, the second identification unit 336 identifies an intermediate luminance part of the luminance image located within the electrode region DR as the flux-coated region FR. Therefore, the flux-coated region FR, i.e., the region representing the state of flux application to the electrode 3, can be identified more accurately and more easily.

[0077] And since the electrode region DR corresponding to the inspection region and the flux application region FR showing the application state of the flux 7 can be accurately specified, good inspection accuracy can be obtained in the pass / fail judgment by the judgment unit 337. As a result, sufficient inspection accuracy can be ensured even in the case of inspecting the board 1 on which a plurality of electrodes 3 are provided at an extremely small pitch (for example, a board on which a BGA is mounted).

[0078] Furthermore, since the incident angle θ is set to be equal to or greater than 60° and equal to or less than 75°, the light specularly reflected by the electrode 3 is less likely to reach the camera 322. Therefore, the difference in brightness between the exposed electrode 3e and the electrode 3 to which the flux 7 is applied can be made larger in the brightness image. As a result, the flux-applied region FR can be more accurately identified from the brightness image, and the inspection accuracy can be further improved.

[0079] The present invention is not limited to the above-described embodiment, and may be implemented as follows: Of course, other applications and modifications not exemplified below are also possible.

[0080] (a) In the above embodiment, the base portion 6 of the substrate 1 is green, but it may be red or brown. The color (wavelength) of the visible light irradiated from the lighting device 321 is set according to the color of the base portion 6.

[0081] (b) The lighting device 321 may have a function of changing (adjusting) the wavelength of the visible light irradiated to the substrate 1. In this case, the lighting control unit 332 may be configured to be able to control the wavelength of each light irradiated from the lighting device 321.

[0082] Furthermore, the input unit 340 may be configured to be able to input the color (information about the color) of the base portion 6 of the substrate 1, and the illumination control unit 332 may be configured to control the wavelengths of the lights irradiated from the illumination device 321 based on the color input by the input unit 340. In this configuration, the illumination control unit 332 may automatically control the wavelengths of the lights irradiated from the illumination device 321 as follows.

[0083] That is, when the color input by the input unit 340 is green (when the color information corresponds to green), the illumination control unit 332 may set the wavelength of the light irradiated from the illumination device 321 to 520 nm or more and 530 nm or less. Also, when the color input by the input unit 340 is red or brown (when the color information corresponds to red or brown), the illumination control unit 332 may set the wavelength of the light irradiated from the illumination device 321 to 625 nm or more and 635 nm or less.

[0084] As described above, by adopting a configuration in which the wavelength of the irradiated light is automatically and appropriately set according to the color of the base portion 6, it is possible to more reliably obtain good inspection accuracy and to further improve convenience regarding the inspection. In this configuration, the illumination control unit 332 corresponds to the "wavelength control means."

[0085] (c) In the above embodiment, the second identification unit 336 is configured to identify the flux-coated region FR based on the luminance image, but may identify the electrode exposed region RR based on the luminance image. The electrode exposed region RR can be identified by extracting a dark portion (exposed electrode 3e) in the luminance image, for example.

[0086] Furthermore, when the electrode exposed region RR is specified, the determination unit 337 can determine whether the application state of the flux 7 is good or bad based on the area of ​​the specified electrode exposed region RR.

[0087] In addition, the second identification unit 336 may identify both the flux application area FR and the electrode exposed area RR, and the judgment unit 337 may make a pass / fail judgment regarding the application state of the flux 7 based on both the identified areas FR and RR.

[0088] (d) In the above embodiment, the determination unit 337 is configured to inspect the application state of the flux 7 by comparing the calculated area of ​​the flux-coated region FR with an area threshold value pre-stored in the inspection information storage unit 342b. Alternatively, the determination unit 337 may calculate a ratio of the area of ​​the flux-coated region FR to the area of ​​the electrode region DR and judge the application state of the flux 7 based on this ratio. Of course, the application state of the flux 7 may be judged using other determination methods (such as a determination method based on the shapes of the flux-coated region FR and the electrode exposed region RR).

[0089] (e) In the above embodiment, the substrate 1 is a glass epoxy substrate, but it may be another type of substrate, such as a ceramic substrate.

[0090] (f) In the above embodiment, a BGA is given as the electronic component 5, but the electronic component 5 may be another semiconductor package (for example, a CSP (Chip Size Package)).

[0091] (g) In the above embodiment, the flux 7 individually covers the multiple electrodes 3 constituting one electrode group 3x, but it may also cover all of these electrodes 3 collectively. [Explanation of symbols]

[0092] 1...printed circuit board (circuit board), 3...electrode, 6...base material portion, 7...flux, 12...flux application state inspection device, 321...lighting device (illumination means), 322...camera (imaging means), 332...lighting control unit (wavelength control means), 335...first identification unit (first identification means), 336...second identification unit (second identification means), 337...judgment unit (judgment means), 340...input unit (input means), DR...electrode area, FR...flux application area, RR...electrode exposed area.

Claims

1. A flux application state inspection device for inspecting a transparent or semi-transparent flux applied to an electrode of a substrate having a green, red, or brown base portion, comprising: an irradiation means capable of irradiating the substrate with visible light of the same color as the color of the base portion of the substrate at an incident angle of 55° to 75°; an imaging means arranged above the substrate with its optical axis perpendicular to the substrate, capable of imaging light irradiated from the irradiating means onto the substrate and reflected by the substrate to obtain a luminance image in which the electrode becomes a dark portion, the base portion becomes a bright portion having a higher luminance than the dark portion, and a portion on the electrode where flux is present becomes an intermediate luminance portion having a luminance intermediate between the luminance of the dark portion and the bright portion; a first identification means for identifying the dark areas and the intermediate luminance areas in the luminance image as electrode areas indicative of areas where the electrodes are present on the substrate; a second identification means configured to be capable of at least one of identifying the intermediate luminance portion of the luminance image located within the electrode region as a flux-coated region indicating a region where flux is coated on the electrode, and identifying the dark portion of the luminance image located within the electrode region as an electrode-exposed region indicating a region where the electrode is exposed; and and a determination means for determining whether the flux applied to the electrode is good or bad based on at least one of the flux application area and the electrode exposed area identified by the second identification means.

2. 2. The flux application state inspection device according to claim 1, wherein an incident angle of the light irradiated from said irradiating means to said board is set to be in the range of 60 degrees to 75 degrees.

3. an input means for inputting a color of a base portion of the substrate; a wavelength control means for automatically controlling a wavelength of the visible light irradiated from the irradiating means based on the color input by the input means, The wavelength control means When the color input by the input means is green, the wavelength of the light irradiated from the irradiation means is set to 520 nm or more and 530 nm or less; 2. The flux application state inspection device according to claim 1, wherein when the color input by the input means is red or brown, the wavelength of the light irradiated from the irradiation means is set to 625 nm or more and 635 nm or less.

4. 1. A flux application state inspection method for inspecting a transparent or semi-transparent flux applied to an electrode of a substrate having a green, red, or brown base portion, comprising: an irradiation step of irradiating the substrate with visible light of the same color as the color of the base portion of the substrate at an incident angle of 55° to 75°; an imaging step of imaging the light irradiated to the substrate in the irradiation step and reflected from the substrate by an imaging means disposed above the substrate with its optical axis perpendicular to the substrate, thereby obtaining a luminance image in which the electrode becomes a dark portion, the base portion becomes a bright portion having a higher luminance than the dark portion, and a portion on the electrode where flux is present becomes an intermediate luminance portion having a luminance intermediate between the luminance of the dark portion and the bright portion; a first identification step of identifying the dark areas and the intermediate luminance areas in the luminance image as electrode areas indicative of areas where the electrodes are present on the substrate; a second identification step of performing at least one of identifying the intermediate luminance portion of the luminance image located within the electrode region as a flux-coated region indicating a region where flux is applied to the electrode, and identifying the dark portion of the luminance image located within the electrode region as an electrode-exposed region indicating a region where the electrode is exposed; and a determination step of determining whether the state of flux applied to the electrode is good or bad based on at least one of the flux application area and the electrode exposed area identified in the second identification step.

Images