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: a first specification part 335 that specifies an electrode region as an inspection region on the basis of a first imaging image obtained by an imaging of a camera 322 in a state where a light is irradiated to a substrate from a first illumination device 321a; and a second specification part 336 that specifies a flux coating region and / or an electrode exposure region in accordance with an electrode region on the basis of a second imaging image obtained by the imaging of the camera 322 in a state where the light is irradiated to the substrate from a second illumination device 321b. By a determination part 337, a quality determination in accordance with a coating state of a flux against an electrode is performed on the basis of the flux coating region and / or the electrode exposure region specified by the second specification 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 of a substrate, comprising: a first irradiation means capable of irradiating the substrate with ultraviolet light having a wavelength of 320 nm or more and 400 nm or visible light having a color complementary to the color of the base portion of the substrate at an incident angle of 0° or more and 30° or less; a second irradiation means capable of irradiating the substrate with red or green visible light at an incident angle larger than an incident angle of the light from the first irradiation means to the substrate; an imaging means arranged above the substrate such that its optical axis is perpendicular to the substrate, and capable of imaging light irradiated from the first irradiating means to the substrate and reflected by the substrate, and light irradiated from the second irradiating means to the substrate and reflected by the substrate; a first identification means for identifying an electrode region indicating an area where the electrode is present on the substrate based on a first captured image obtained by the imaging means in a state in which the substrate is irradiated with light from the first irradiation means; a second identification means for identifying at least one of a flux-coated region, which is located within the electrode region and indicates a region where flux is applied, and an electrode-exposed region, which is located within the electrode region and indicates a region where the electrode is exposed, based on a second captured image obtained by the imaging means in a state in which the substrate is irradiated with light from the second irradiation means; 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 first irradiating means irradiates the substrate with ultraviolet light having a wavelength of 320 nm or more and 400 nm or visible light having a color complementary to the color of the substrate of the substrate at an incident angle of 0° or more and 30° or less. Here, since the light is irradiated from the first irradiating means to the substrate at a relatively small incident angle, the light is reflected specularly at the electrodes regardless of whether flux is applied or not, and the light reflected specularly from the electrodes is likely to reach the imaging means. On the other hand, the other parts (substrate of the substrate) absorb the irradiated light. Therefore, in the first captured image obtained by the imaging means while the first irradiating means is irradiating the substrate with light, the electrodes are bright, while the other parts are dark. Therefore, the first identifying means can identify the electrode area indicating the area where the electrodes are present on the substrate, i.e., the inspection area to be determined as to whether flux is appropriately applied or not, more accurately and more easily based on the first captured image. This can reduce the processing load related to the setting of the inspection area, and thus improve the inspection efficiency. Furthermore, since the inspection area (electrode area) can be identified without using references such as marks on the substrate, it is possible to more reliably prevent a decrease in inspection accuracy due to fluctuations in the position of the reference caused by changes in the shape of the substrate (e.g., warping, shrinkage, or expansion).

[0014] On the other hand, the second irradiating means irradiates the substrate with red or green visible light at an angle of incidence larger than the angle of incidence of light from the first irradiating means to the substrate. Here, since the light is incident from the second irradiating means to the substrate at a relatively large angle of incidence, the light reflected specularly from the electrode (exposed electrode) to which no flux is applied is unlikely to reach the imaging means. On the other hand, in the electrode to which flux is applied, diffuse reflection of light occurs due to the flux, so the light reflected from the electrode is likely to reach the imaging means. Therefore, in the second captured image obtained by the imaging means while the substrate is irradiated with light from the second irradiating means, the exposed electrode becomes a dark area, while the electrode to which flux is applied becomes a brighter area (e.g., a gray area) than the exposed electrode. Therefore, the second identifying means can identify the flux-applied area (gray area in the second captured image) and the electrode exposed area (dark area in the second captured image) more accurately and more easily based on the second captured image.

[0015] 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).

[0016] In terms of improving the inspection accuracy, the greater the difference between the angle of incidence of light from the first irradiation means to the substrate and the angle of incidence of light from the second irradiation means to the substrate, the more preferable it is. Therefore, it is more preferable for the difference between the two angles of incidence to be 30° or more, and even more preferable for it to be 45° or more.

[0017] Means 2. The wavelength of the light irradiated from the first irradiation means and the wavelength of the light irradiated from the second irradiation means are set to be different from each other; The flux application state inspection device described in Means 1 is characterized in that the imaging means is configured to be able to obtain the first captured image and the second captured image by simultaneously capturing light irradiated from the first irradiation means to the substrate and reflected by the substrate, and light irradiated from the second irradiation means to the substrate and reflected by the substrate.

[0018] According to the above-mentioned means 2, the first captured image and the second captured image can be obtained by one image capture by the imaging means, and therefore the efficiency of the inspection can be further improved.

[0019] Means 3. The flux application state inspection device according to Means 1, characterized in that the angle of incidence of the light irradiated from the first irradiating means to the board is set to be between 0° and 20°.

[0020] According to the above-mentioned means 3, since the light specularly reflected by the electrode can reach the imaging means more easily, the difference between the brightness of the electrode and the brightness of other parts in the first captured image can be made larger. As a result, the electrode area (inspection area) can be more accurately specified from the first captured image, and the inspection accuracy can be further improved.

[0021] In order to further improve the inspection accuracy, the incident angle of the light from the first irradiation means to the substrate is more preferably 0° or more and 15° or less, and even more preferably 0° or more and 10° or less.

[0022] Means 4. The flux application state inspection device according to Means 1, characterized in that the angle of incidence of the light irradiated from the second irradiating means to the board is set to 55° or more and 75° or less.

[0023] According to the above-mentioned means 4, 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 second captured image. As a result, the electrode exposed area and the flux-applied area can be more accurately identified from the second captured image, and the inspection accuracy can be further improved.

[0024] In order to further improve the inspection accuracy, it is more preferable that the incident angle of the light from the second irradiation means to the substrate is set to 60° or more and 70° or less.

[0025] Means 5. The flux application state inspection device according to Means 1, wherein the first irradiation means irradiates ultraviolet light having a wavelength of 320 nm or more and 400 nm or less.

[0026] According to the above-mentioned means 5, the first irradiating means irradiates ultraviolet light instead of visible light that matches the color of the base part of the substrate. Therefore, when obtaining the first captured image, it is not necessary to set the irradiation light that matches the color of the base part of the substrate. This can improve the convenience of the inspection.

[0027] Means 6. The first irradiation means irradiates visible light of a color complementary to the color of the base part of the substrate, an input means for inputting a color of a base portion of the substrate; a wavelength control means for automatically controlling the wavelength of each of the lights irradiated from the first irradiating means and the second 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 first irradiating means is set to 625 nm or more and 635 nm or less or 445 nm or more and 455 nm or less, and the wavelength of the light irradiated from the second irradiating means is set to 520 nm or more and 635 nm or less, When the color input by the input means is blue, the wavelength of the light irradiated from the first irradiating means is set to 520 nm or more and 635 nm or less, and the wavelength of the light irradiated from the second irradiating means is set to 520 nm or more and 635 nm or less, The flux application state inspection device according to Means 1, characterized in that, when the color input by the input means is red or brown, the wavelength of the light irradiated from the first irradiation means is set to 445 nm or more and 530 nm or less, and the wavelength of the light irradiated from the second irradiation means is set to 520 nm or more and 635 nm or less.

[0028] According to the above-mentioned means 6, 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 both 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.

[0029] Means 7. A method for inspecting a transparent or translucent flux applied to an electrode of a substrate, comprising the steps of: A first irradiation step in which ultraviolet light having a wavelength of 320 nm or more and 400 nm or visible light having a color complementary to the color of the base part of the substrate can be irradiated onto the substrate at an incident angle of 0° or more and 30° or less; a second irradiation step of irradiating the substrate with red or green visible light at an angle of incidence larger than the angle of incidence of light on the substrate in the first irradiation step; a first imaging step of imaging the light irradiated to the substrate in the first irradiation step and reflected by the substrate by an imaging means disposed above the substrate such that the optical axis of the imaging means is perpendicular to the substrate; a second imaging step of imaging the light irradiated to the substrate in the second irradiation step and reflected by the substrate by the imaging means; a first identification step of identifying an electrode region indicating an area where the electrode is present on the substrate based on a first captured image obtained by the first imaging step; a second identification step of identifying at least one of a flux-coated region, which is located within the electrode region and indicates a region where flux is applied, and an electrode-exposed region, which is located within the electrode region and indicates a region where the electrode is exposed, based on a second captured image obtained by the second imaging step; 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.

[0030] According to the seventh aspect, the same effects as those of the first aspect can be achieved.

[0031] The technical matters related to the above-mentioned respective means may be combined as appropriate. Therefore, for example, the technical matters related to the above-mentioned means 3 may be combined with the technical matters related to the above-mentioned means 4. Moreover, at least one of the technical matters related to the above-mentioned means 2 to 6 may be applied to the above-mentioned means 7. [Brief description of the drawings]

[0032] [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. 1 is a schematic diagram showing a first captured image; [Figure 11] 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 12] 13 is a schematic diagram showing a second captured image in a case where all of a plurality of electrodes constituting one electrode group are appropriately covered with flux. FIG. [Figure 13] 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 14] 13 is a schematic diagram showing a second captured image in a case where some of the multiple electrodes are not properly covered with flux and are exposed. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0033] 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.

[0034] 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.

[0035] 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 resin, resist, or the like, and is green in this embodiment.

[0036] 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).

[0037] 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. The flux 7 also covers each of the electrodes 3 constituting one electrode group 3x.

[0038] 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.

[0039] The flux applicator 11 applies the flux 7 to at least the surface of the electrode 3 on the substrate 1. The flux applicator 11, for example, 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, 11, and 13 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.

[0040] 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.

[0041] 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.

[0042] 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.

[0043] 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.

[0044] 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).

[0045] 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.

[0046] 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).

[0047] 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.

[0048] The inspection unit 32 is disposed above the transport rail 31a (the transport path for the substrate 1). The inspection unit 32 includes a first illumination device 321a, a second illumination device 321b, and a camera 322. In this embodiment, the first illumination device 321a constitutes a "first illumination means", the second illumination device 321b constitutes a "second illumination means", and the camera 322 constitutes an "imaging means".

[0049] 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).

[0050] The first lighting device 321a irradiates the board 1 to be inspected by the flux application state inspection device 12 with visible light that is complementary to the color of the base part 6 of the board 1. In this embodiment, since the base part 6 is green, the first lighting device 321a irradiates red visible light (for example, light with a wavelength of 625 nm or more and 635 nm or less).

[0051] The first lighting device 321a irradiates the substrate 1 with light from vertically above or obliquely above, and the incidence angle θ1 of the light from the first lighting device 321a to the substrate 1 (particularly the inspection target range KH described below) is set to be 0° or more and 30° or less. In particular, in this embodiment, the incidence angle θ1 is set to be 0° or more and 20° or less. In terms of improving the inspection accuracy, it is more preferable to set the incidence angle θ1 to be 0° or more and 15° or less, and even more preferable to set the incidence angle θ1 to be 0° or more and 10° or less. In this embodiment, the process of irradiating the substrate 1 with light from the first lighting device 321a corresponds to the "first irradiation process".

[0052] The second illumination device 321b irradiates the board 1 to be inspected with red (for example, light having a wavelength of 625 nm or more and 635 nm or less) or green (for example, light having a wavelength of 520 nm or more and 530 nm or less) visible light. The second illumination device 321b also irradiates the board 1 with light at an incidence angle θ2 larger than the incidence angle θ1 of the light from the first illumination device 321a to the board 1. In this embodiment, the incidence angle θ2 of the light from the second illumination device 321b to the board 1 (particularly the inspection target range KH described later) is set to 55° or more and 75° or less. In terms of improving the inspection accuracy, it is more preferable to set the incidence angle θ2 to 60° or more and 75° or less, and even more preferable to set it to 60° or more and 70° or less. In this embodiment, the process of irradiating the board 1 with light from the second illumination device 321b corresponds to the "second illumination process".

[0053] 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).

[0054] Moreover, the camera 322 is composed of a CCD camera or the like having sensitivity to each light irradiated from the first lighting device 321a and the second lighting device 321b, and its operation is controlled by the control device 33 (a camera control unit 333 described later).

[0055] Then, under the operational control of the control device 33, the camera 322 captures an image of the light reflected from the substrate 1 in the inspection range KH while the substrate 1 is being irradiated with light from the first illumination device 321a. This results in a first captured image relating to the inspection range KH. The first captured image is a luminance image having a large number of pixels, each having data relating to luminance. In this embodiment, the process of using the camera 322 to capture an image of the light irradiated from the first illumination device 321a and reflected from the substrate 1 corresponds to the "first imaging process."

[0056] Further, under the operational control of the control device 33, the camera 322 captures an image of the light reflected from the substrate 1 in the inspection range KH while the substrate 1 is being irradiated with light from the second illumination device 321b. This results in a second captured image relating to the inspection range KH. The second captured image is a luminance image like the first captured image, and has a large number of pixels, each having data relating to luminance. In this embodiment, the process of using the camera 322 to capture an image of the light irradiated from the second illumination device 321b and reflected from the substrate 1 corresponds to the "second imaging process."

[0057] In the first captured image, the electrode 3 appears as a bright area regardless of whether the flux 7 is applied or not, and the other areas (base material portion 6) appear as dark areas (see, for example, FIG. 10). This is because light is irradiated from the first lighting device 321a to the substrate 1 at a relatively small incident angle θ1, causing specular reflection of the light at the electrode 3 and making it easier for the light specularly reflected from the electrode 3 to reach the camera 322, while visible light that is complementary to the color of the base material portion 6 is irradiated from the first lighting device 321a, causing the irradiated light to be absorbed by the other areas (base material portion 6).

[0058] In the second captured image, the electrodes 3 not coated with the flux 7 (exposed electrodes) are dark, whereas the electrodes 3 coated with the flux 7 are gray, which is brighter (higher luminance) than the exposed electrodes. This is because the light is irradiated from the second illumination device 321b to the substrate 1 at a relatively large incident angle θ2, so that the light specularly reflected from the exposed electrodes is less likely to reach the camera 322, whereas the light diffusely reflected by the flux 7 occurs in the electrodes 3 coated with the flux 7, so that the light reflected from the electrodes 3 is more likely to reach the camera 322. Therefore, when all of the electrodes 3 constituting one electrode group 3x are appropriately covered with the flux 7 (see, for example, FIG. 11), all of the electrodes 3 are gray in the second captured image (see, for example, FIG. 12). On the other hand, when a part or all of the electrode 3 is not properly covered with the flux 7 and an exposed electrode 3e exists (see, for example, FIG. 13), the exposed electrode 3e appears in the second captured image as a dark area that is darker (lower brightness) than the gray area (see, for example, FIG. 14).

[0059] The first captured image and the second captured image acquired by the camera 322 are 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 these images.

[0060] 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.

[0061] 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.

[0062] 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".

[0063] 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."

[0064] 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.

[0065] 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.

[0066] 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 performing binarization processing of an image and performing pass / fail judgment, design data, manufacturing data, and the like. 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.

[0067] 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.

[0068] 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.

[0069] 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.

[0070] 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.

[0071] 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 .

[0072] 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.

[0073] The illumination control unit 332 is a functional unit that controls the driving of the first illumination device 321a and the second illumination device 321b. The illumination control unit 332 performs timing control regarding the irradiation or stop of irradiation of light from the illumination devices 321a and 321b to the substrate 1 based on a command signal from the main control unit 331. In this embodiment, the illumination control unit 332 controls the illumination devices 321a and 321b so that the irradiation of light from the first illumination device 321a to the substrate 1 and the irradiation of light from the second illumination device 321b to the substrate 1 are performed at different timings.

[0074] 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. In this embodiment, the camera control unit 333 controls the camera 322 so that imaging is performed both when light is irradiated from the first lighting device 321a and when light is irradiated from the second lighting device 321b. This allows a first captured image and a second captured image to be obtained.

[0075] The image capture unit 334 is a functional unit for capturing the first captured image and the second captured image captured and acquired by the camera 322. Each image captured by the image capture unit 334 is stored in the image storage unit 342a.

[0076] The first identification unit 335 identifies an electrode region DR (see FIG. 10) indicating an area where the electrode 3 is present on the substrate 1 based on the first captured image. More specifically, the first identification unit 335 acquires a binary image by performing a binary process on the first captured image based on a threshold value stored in the inspection information storage unit 342b. In the binary image, a portion corresponding to the electrode 3 becomes a bright portion (1) regardless of whether the flux 7 is applied or not, and a portion corresponding to the other portion (base portion 6) becomes a dark portion (0). Then, the first identification unit 335 identifies the bright portion in the binary image as the electrode region DR. The electrode region DR functions as an inspection region that is a target for determining whether the flux 7 is appropriately applied or not. In this embodiment, the process of identifying the electrode region DR by the first identification unit 335 corresponds to the "first identification process".

[0077] The second identification unit 336 identifies, based on the second captured image, at least one of a flux-coated region FR (see FIGS. 12 and 14) that is located within the electrode region DR and indicates a region where the flux 7 is applied, and an electrode-exposed region RR (see FIG. 14) that is located within the electrode region DR and indicates 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 second captured image.

[0078] In identifying the flux-coated region FR, the second identifying unit 336 extracts a portion of the second captured image having a brightness within the numerical range stored in the inspection information storage unit 342b, thereby extracting a gray portion in the second captured image. Then, the second identifying unit 336 identifies a portion of the extracted 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."

[0079] 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.

[0080] 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 346b. 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.

[0081] 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".

[0082] As described above in detail, according to this embodiment, in the first captured image, the electrode 3 is a bright part, while the other parts are dark. Therefore, the first identification unit 335 can more accurately and easily identify the electrode region DR, that is, the inspection region to be determined whether the flux 7 is properly applied or not, based on the first captured image. This can reduce the processing load related to setting the inspection region, and thus can improve the inspection efficiency. In addition, since the inspection region (electrode region DR) can be identified without using a reference such as a mark 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 (for example, warping, shrinkage, expansion).

[0083] On the other hand, in the second captured image, the exposed electrode 3e appears as a dark area, while the electrode 3 to which the flux 7 is applied appears as a brighter area (e.g., a gray area) than the exposed electrode 3e. Therefore, the second identifying unit 336 can identify the flux-coated area FR more accurately and more easily based on the second captured image.

[0084] And since the electrode region DR and the flux applied region FR corresponding to the inspection region 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 inspection of 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).

[0085] In addition, since the incident angle θ1 is set to be equal to or greater than 0° and equal to or less than 20°, the light regularly reflected by the electrode 3 is more likely to reach the camera 322. Therefore, the difference in brightness between the electrode 3 and the other parts in the first captured image can be made larger, and the electrode region DR can be more accurately identified from the first captured image. This can further improve the inspection accuracy.

[0086] Furthermore, since the incident angle θ2 is set to be equal to or greater than 55° and equal to or less than 75°, the light specularly reflected by the electrode 3 is less likely to reach the camera 322. Therefore, in the second captured image, the difference in luminance between the exposed electrode 3e and the electrode 3 to which the flux 7 is applied can be made larger. As a result, the flux-applied region FR can be more accurately identified from the second captured image, and the inspection accuracy can be further improved.

[0087] 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.

[0088] (a) In the above embodiment, the base portion 6 of the substrate 1 is green, but it may be another color. For example, the base portion 6 may be blue, red, or brown.

[0089] (b) The first lighting device 321a and the second lighting device 321b may have a function of changing (adjusting) the wavelength of 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 of the lights irradiated from the first lighting device 321a and the second lighting device 321b.

[0090] 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 first illumination device 321a and the second illumination device 321b 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 first illumination device 321a and the second illumination device 321b as follows.

[0091] That is, when the color inputted 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 first illumination device 321a to 625 nm or more and 635 nm or less, or 445 nm or more and 455 nm or less, and the wavelength of the light irradiated from the second illumination device 321b to 520 nm or more and 635 nm or less. Also, when the color inputted by the input unit 340 is blue (when the color information corresponds to blue), the illumination control unit 332 may set the wavelength of the light irradiated from the first illumination device 321a to 520 nm or more and 635 nm or less, and the wavelength of the light irradiated from the second illumination device 321b to 520 nm or more and 635 nm or less. Furthermore, when the color input by the input unit 340 is red or brown (when the color information corresponds to red or brown), the lighting control unit 332 may set the wavelength of the light irradiated from the first lighting device 321a to be greater than or equal to 445 nm and less than or equal to 530 nm, and the wavelength of the light irradiated from the second lighting device 321b to be greater than or equal to 520 nm and less than or equal to 635 nm.

[0092] 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 substrate 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."

[0093] (c) In the above embodiment, the camera 322 is configured to perform imaging for obtaining a first captured image and imaging for obtaining a second captured image at different timings. In contrast, the camera 322 may simultaneously capture light irradiated from the first illumination device 321a to the substrate 1 and reflected by the substrate 1, and light irradiated from the second illumination device 321b to the substrate 1 and reflected by the substrate 1, that is, imaging for obtaining a first captured image and imaging for obtaining a second captured image may be performed at the same timing. In this case, the first captured image and the second captured image can be obtained by imaging once by the camera 322. Therefore, the inspection efficiency can be further improved.

[0094] In addition, when the camera 322 is configured to be able to acquire both images by capturing an image once, the wavelength of the light irradiated from the first illumination device 321a and the wavelength of the light irradiated from the second illumination device 321b are set to be different from each other. For example, the first illumination device 321a is set to irradiate red visible light, and the second illumination device 321b is set to irradiate green visible light. The camera 322 is also set to have sensitivity to each of the lights irradiated from the first illumination device 321a and the second illumination device 321b.

[0095] (d) In the above embodiment, the second identification unit 336 is configured to identify the flux-coated region FR based on the second captured image, but may identify the electrode exposed region RR based on the second captured image. The electrode exposed region RR can be identified by extracting a dark area in the second captured image by binarization processing or the like.

[0096] 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.

[0097] 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.

[0098] (e) 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).

[0099] (f) In the above embodiment, the first illumination device 321a irradiates visible light that is complementary to the color of the base portion 6, but it may irradiate ultraviolet light of 320 nm or more and 400 nm or less. In this case, it is not necessary to set the illumination light to match the color of the base portion 6 of the substrate 1 when obtaining the first captured image. This can improve the convenience of the inspection.

[0100] (g) 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.

[0101] (h) 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)).

[0102] (i) In the above embodiment, the flux 7 covers each of the electrodes 3 constituting one electrode group 3x individually. However, the flux 7 may cover all of the electrodes 3 collectively. [Explanation of symbols]

[0103] 1...printed circuit board (circuit board), 3...electrode, 6...base material portion, 7...flux, 12...flux application state inspection device, 321a...first lighting device (first illumination means), 321b...second lighting device (second illumination means), 322...camera (imaging means), 332...illumination 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, comprising: a first irradiation means capable of irradiating the substrate with ultraviolet light having a wavelength of 320 nm or more and 400 nm or visible light having a color complementary to the color of the base portion of the substrate at an incident angle of 0° or more and 30° or less; a second irradiation means capable of irradiating the substrate with red or green visible light at an incident angle larger than an incident angle of the light from the first irradiation means to the substrate; an imaging means arranged above the substrate such that its optical axis is perpendicular to the substrate, and capable of imaging light irradiated from the first irradiating means to the substrate and reflected by the substrate, and light irradiated from the second irradiating means to the substrate and reflected by the substrate; a first identification means for identifying an electrode region indicating an area where the electrode is present on the substrate based on a first captured image obtained by the imaging means in a state in which the substrate is irradiated with light from the first irradiation means; and a second identification means for identifying at least one of a flux-coated region, which is located within the electrode region and indicates a region where flux is applied, and an electrode-exposed region, which is located within the electrode region and indicates a region where the electrode is exposed, based on a second captured image obtained by the imaging means in a state in which the substrate is irradiated with light from the second irradiation means; 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. the wavelength of the light irradiated from the first irradiating means and the wavelength of the light irradiated from the second irradiating means are set to be different from each other, 2. The flux application state inspection device according to claim 1, wherein the imaging means is configured to be able to obtain the first captured image and the second captured image by simultaneously capturing an image of light irradiated from the first irradiating means to the substrate and reflected by the substrate, and a image of light irradiated from the second irradiating means to the substrate and reflected by the substrate.

3. 2. The flux application state inspection device according to claim 1, wherein an incident angle of the light irradiated from the first irradiating means onto the board is set to be equal to or greater than 0° and equal to or less than 20°.

4. 2. The flux application state inspection device according to claim 1, wherein an incident angle of the light irradiated from the second irradiating means onto the board is set to be equal to or greater than 55 degrees and equal to or less than 75 degrees.

5. 2. The flux application state inspection device according to claim 1, wherein the first irradiating means irradiates ultraviolet light having a wavelength of 320 nm or more and 400 nm or less.

6. the first irradiation means irradiates visible light of a color complementary to the color of the base portion of the substrate, an input means for inputting a color of a base portion of the substrate; a wavelength control means for automatically controlling the wavelength of each of the lights irradiated from the first irradiating means and the second 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 first irradiating means is set to 625 nm or more and 635 nm or less or 445 nm or more and 455 nm or less, and the wavelength of the light irradiated from the second irradiating means is set to 520 nm or more and 635 nm or less, When the color input by the input means is blue, the wavelength of the light irradiated from the first irradiating means is set to 520 nm or more and 635 nm or less, and the wavelength of the light irradiated from the second irradiating means is set to 520 nm or more and 635 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 first irradiating means is set to 445 nm or more and 530 nm or less, and the wavelength of the light irradiated from the second irradiating means is set to 520 nm or more and 635 nm or less.

7. A flux application state inspection method for inspecting a transparent or semi-transparent flux applied to an electrode of a substrate, comprising the steps of: A first irradiation step in which ultraviolet light having a wavelength of 320 nm or more and 400 nm or visible light having a color complementary to the color of the base portion of the substrate can be irradiated onto the substrate at an incident angle of 0° or more and 30° or less; a second irradiation step of irradiating the substrate with red or green visible light at an angle of incidence larger than the angle of incidence of light on the substrate in the first irradiation step; a first imaging step of imaging the light irradiated to the substrate in the first irradiation step and reflected by the substrate by an imaging means disposed above the substrate such that the optical axis of the imaging means is perpendicular to the substrate; a second imaging step of imaging the light irradiated to the substrate in the second irradiation step and reflected by the substrate by the imaging means; a first identification step of identifying an electrode region indicating an area where the electrode is present on the substrate based on a first captured image obtained by the first imaging step; a second identification step of identifying at least one of a flux-coated region, which is located within the electrode region and indicates a region where flux is applied, and an electrode-exposed region, which is located within the electrode region and indicates a region where the electrode is exposed, based on a second captured image obtained by the second imaging step; 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