Flux application state inspection apparatus and flux application state inspection method

Abstract

Provided is, for example, a flux application state inspection apparatus capable of obtaining excellent inspection accuracy while enabling setting of an inspection region by relatively simple processing. A flux application state inspection apparatus 12 comprises: an illumination device 321 for irradiating a substrate with ultraviolet light; a camera 322 for imaging the ultraviolet light with which the substrate has been irradiated; an inspection region setting section 335 for setting, for each component to be mounted, an inspection region of the substrate 1 that corresponds to the component and includes a plurality of electrodes on which the component is mounted, with reference to a reference portion provided on the substrate; and a determination section 336 for performing quality determination related to the state of application of flux on the basis of a luminance image obtained by imaging, by means of the camera 322, the ultraviolet light with which the inspection region has been irradiated. The determination section 336 calculates, for each inspection region, the area of a portion having a luminance equal to or greater than a predetermined luminance threshold in the inspection region, and determines the state of application of the flux on the basis of the calculated area.

Description

Flux application state inspection device and flux application state inspection method

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

[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 using the viscosity of the cream solder. After the electronic components are temporarily attached, the printed circuit board is then introduced into a reflow furnace and soldered through a specified reflow process.

[0003] Furthermore, in order to achieve miniaturization and prevent mounting defects, semiconductor packages have been proposed as electronic components, such as ball grid arrays (BGAs), which have a plurality of spherical bumps (solder balls) regularly arranged on the bottom surface. When mounting such semiconductor packages as electronic components 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 semiconductor packages on a printed circuit board, it is preferable to apply flux to the electrodes before placing the bumps on them to improve the wettability of the solder.

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

[0005] In the inspection device described in 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, while a camera can capture an image of the flux, it cannot capture an image of the electrode (printed circuit) to which the flux is applied. Therefore, during inspection, the state of application of the flux is inspected using a pattern-recognized electrode, rather than an actual electrode, as the inspection area, i.e., a virtually estimated area where the electrode exists. Therefore, to ensure sufficient inspection accuracy, it is necessary to set an appropriate inspection area to match the position of the actual electrode.

[0006] Here, one possible method for setting an appropriate inspection area that matches the actual electrode position is to use marks provided on a printed circuit board as a reference (see, for example, Patent Document 2).

[0007] JP 2010-271165 A JP 2005-286309 A

[0008] However, when using marks as references, when inspecting a printed circuit board on which multiple electrodes are provided at extremely small pitches (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 the appropriate inspection area. Such high-precision processing increases the processing load and ultimately reduces 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 view of the above circumstances, and its object is to provide a flux application state inspection device and the like that can obtain good inspection accuracy while allowing the inspection area to be set by a relatively simple process.

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

[0012] Means 1. A flux application state inspection device for inspecting flux that is applied to electrodes of a circuit board and is capable of absorbing ultraviolet light, comprising: an irradiation means capable of irradiating the circuit board with ultraviolet light; an imaging means capable of imaging the ultraviolet light irradiated onto the circuit board; an inspection area setting means for setting, for each component, an inspection area on the circuit board that corresponds to a component to be mounted and includes a plurality of electrodes on which the component will be mounted, using a reference portion provided on the circuit board as a reference; and a judgment means for irradiating the inspection area with ultraviolet light by the irradiation means and judging whether the flux application state is good or bad based on the image obtained by imaging the ultraviolet light irradiated onto the inspection area by the imaging means, wherein the judgment means is configured to calculate, for each inspection area, the area of ​​a portion in the inspection area that has a brightness equal to or greater than a predetermined brightness threshold, and judge the flux application state based on the calculated area.

[0013] According to the above-described means 1, the inspection area setting means sets an inspection area that corresponds to the component to be mounted and includes the plurality of electrodes on which the component will be mounted. For example, if the component to be mounted is a BGA and the component will be mounted on a plurality of electrodes, the area including these electrodes is set as the inspection area. In other words, rather than setting an inspection area for each individual electrode, one inspection area is set corresponding to the plurality of electrodes on which one component will be mounted. Therefore, the inspection area only needs to be set relatively roughly, and the inspection area can be set with a relatively simple process. This reduces the processing burden and thereby improves inspection efficiency.

[0014] Furthermore, according to the above-described means 1, the determining means calculates the area of ​​each inspection region having a brightness equal to or greater than a predetermined brightness threshold, and determines the flux application state based on the calculated area. That is, because ultraviolet light is absorbed by the flux and reflected by the electrodes, the flux appears as a dark area in the captured image, and the electrodes appear as bright areas. The area of ​​the electrodes not covered by the flux (which should be covered by the flux) is calculated as the area of ​​the portion having a brightness equal to or greater than the brightness threshold. The flux application state is then inspected based on the area of ​​the portion having a brightness equal to or greater than the brightness threshold (the area of ​​the electrodes not covered by the flux). Therefore, the flux application state can be inspected collectively for all electrodes, rather than for each electrode corresponding to a single component. This allows for high inspection accuracy even when the inspection region is set relatively roughly. This ensures sufficient inspection accuracy even when inspecting a board with multiple electrodes arranged at extremely small pitches (e.g., a board with BGAs mounted).

[0015] Means 2. The flux application state inspection device according to Means 1, characterized in that the wavelength of the ultraviolet light irradiated from the irradiating means is set to 100 nm or more and 300 nm or less.

[0016] According to the above-mentioned method 2, the flux is more likely to absorb ultraviolet light, so that the flux appears darker in the captured image. This increases the difference in brightness between the electrodes and the flux in the captured image, allowing the flux and electrodes to be identified more accurately. This further improves the inspection accuracy.

[0017] In order to further improve the inspection accuracy, it is more preferable that the wavelength of the ultraviolet light be 200 nm or more and 300 nm or less, even more preferable that it be 220 nm or more and 280 nm or less, and most preferable that it be 230 nm or more and 260 nm or less.

[0018] Means 3. The flux application state inspection device according to Means 1, wherein the imaging means is disposed above the substrate with its optical axis perpendicular to the substrate, and the angle of incidence of the ultraviolet light irradiated onto the substrate from the irradiation means is set to be between 0° and 30°.

[0019] According to the above-mentioned means 3, ultraviolet light reflected by the electrodes can more easily reach the imaging means, so that the difference between the brightness of the electrodes and the brightness of the flux in the captured image can be made larger, which makes it possible to more accurately identify the flux and the electrodes in the captured image, thereby further improving the inspection accuracy.

[0020] In order to further improve the inspection accuracy, it is more preferable that the incident angle of the ultraviolet light on the substrate be 0° or more and 20° or less, even more preferable that it be 0° or more and 15° or less, and most preferable that it be 0° or more and 10° or less.

[0021] Means 4: The flux application state inspection device according to Means 1, characterized in that it is used to inspect transparent or translucent flux.

[0022] The irradiation means irradiates ultraviolet light instead of visible light, so even if the flux is transparent or translucent as in the above-described means 4, the flux can be displayed as a dark area in the captured image. Therefore, even if the flux to be inspected is transparent or translucent, the application state of the flux can be inspected with high accuracy.

[0023] Means 5. The flux application state inspection device according to Means 1, characterized in that it is used to inspect the flux applied to the electrodes of a glass epoxy substrate as the substrate.

[0024] According to the above-mentioned means 5, the electrodes and the substrate (particularly the substrate) are more easily distinguished from each other in the captured image, and the area of ​​the bright part (electrode) can be more accurately identified, thereby further improving the inspection accuracy.

[0025] Means 6. A flux application state inspection method for inspecting flux that is applied to electrodes of a board and is capable of absorbing ultraviolet light, comprising: an irradiation step of irradiating the board with ultraviolet light; an imaging step of imaging the ultraviolet light irradiated onto the board; an inspection area setting step of setting, for each component, an inspection area on the board that corresponds to a component to be mounted and includes a plurality of electrodes on which the component will be mounted, using a reference portion provided on the board as a reference; and a judging step of judging the quality of the flux application state based on the image obtained by imaging the ultraviolet light irradiated onto the inspection area in the imaging step while irradiating the inspection area with ultraviolet light in the irradiation step, wherein the judging step calculates the area of ​​a portion in the inspection area that has a brightness equal to or greater than a predetermined brightness threshold, and judges the flux application state based on the calculated area.

[0026] According to the sixth aspect, the same effects as those of the first aspect can be achieved.

[0027] The technical matters relating to the above means may be combined as appropriate. For example, the technical matters relating to the above means 2 may be combined with the technical matters relating to the above means 4. Furthermore, at least one of the technical matters relating to the above means 2 to 5 may be applied to the above means 6.

[0028] 1 is a schematic plan view of a printed circuit board; FIG. 1 is a schematic plan view of a printed circuit board from which electronic components and the like are omitted to show the electrodes; FIG. 2 is a partially enlarged schematic cross-sectional view of a printed circuit board; FIG. 3 is a schematic perspective view of an electronic component; FIG. 4 is a partially enlarged schematic cross-sectional view showing electronic components and the like before being mounted on electrodes; FIG. 5 is a block diagram showing the configuration of a printed circuit board manufacturing line; FIG. 6 is a partially enlarged schematic plan view of a printed circuit board showing flux and the like applied to electrodes; FIG. 7 is a schematic configuration diagram showing a flux application state inspection device; FIG. 8 is a block diagram showing the functional configuration of a flux inspection state inspection device; FIG. 9 is a partially enlarged schematic plan view of a printed circuit board in a case where all of a plurality of electrodes constituting one electrode group are appropriately collectively covered with flux; FIG. 10 is a schematic diagram showing a luminance image in a case where all of a plurality of electrodes constituting one electrode group are appropriately collectively covered with flux; FIG. 11 is a partially enlarged schematic plan view of a printed circuit board in a case where some of the plurality of electrodes are not appropriately covered with flux and are exposed; FIG. 12 is a schematic diagram showing a luminance image in a case where some of the plurality of electrodes are not appropriately covered with flux and are exposed. 1 is a schematic diagram showing a partially enlarged plan view of a printed circuit board in a case where a plurality of electrodes are individually covered with flux and some of the electrodes are not properly covered and are exposed, and a schematic diagram showing a luminance image in a case where a plurality of electrodes are individually covered with flux and some of the electrodes are not properly covered and are exposed.

[0029] 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.

[0030] As shown in Figures 1 to 3, the printed circuit board 1 (hereinafter simply referred to as "board 1") is a so-called glass epoxy board, and is formed by forming electrodes 3 (not shown in Figure 1) made of copper foil on a flat base substrate 2 made of glass epoxy resin or the like. An electronic component 5 such as a chip is mounted on the electrode 3 via solder 4 made by kneading solder particles with flux. In this embodiment, the electronic component 5 corresponds to the "component."

[0031] 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.

[0032] Furthermore, as shown in FIG. 4 , the electronic component 5 in this embodiment is a so-called ball grid array (BGA) having multiple bumps 4 a regularly arranged on its bottom surface. Each bump 4 a melts and spreads over the surface of the electrode 3 during a reflow process in a reflow device 14 (described later), ultimately forming solder 4. The base substrate 2 has an electrode group 3 x (see FIG. 2 ) consisting of multiple electrodes 3 on which each bump 4 a of one electronic component 5 is mounted. When the electronic component 5 is mounted on the base substrate 2, each bump 4 a is mounted on each electrode 3 constituting the electrode group 3 x. The base substrate 2 also has multiple (e.g., four) electrode groups 3 x, and one electronic component 5 is mounted on each electrode group 3 x. In this embodiment, the pitch between the multiple electrodes 3 constituting one electrode group 3 x is very small (e.g., 1.8 mm or less, or 0.5 mm or less).

[0033] 5, before the electronic components 5 are mounted on the electrode groups 3x, flux 7 is applied to the surface of the base substrate 2, including the surfaces of the electrode groups 3x (electrodes 3). The flux 7 is used to remove metal oxide films on the electrodes 3, the electronic components 5, and the solder 4, and to improve the wettability of the solder 4. The flux 7 is capable of absorbing ultraviolet light and is transparent or translucent, making it difficult to see. Furthermore, in this embodiment, the flux 7 does not individually cover the multiple electrodes 3 constituting one electrode group 3x, but covers all of these electrodes 3 collectively.

[0034] In addition, the base substrate 2 is provided with marks 8 for identifying the mounting positions of the electronic components 5 (see FIGS. 1 and 2). The marks 8 are provided in portions of the base substrate 2 that are not covered with the flux 7, and are also used to identify the inspection region KR, which will be described later. In this embodiment, the marks 8 correspond to the "reference portion." Note that the "reference portion" may be a predetermined electrode 3, a circuit pattern (electrode pattern), a printed portion, or the like.

[0035] 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.

[0036] The flux applicator 11 applies the flux 7 to at least the surfaces of the electrodes 3 on the substrate 1. The flux applicator 11, for example, places a predetermined mask on the substrate 1 and then applies the flux 7 to the surfaces of the electrodes 3 by screen printing. Of course, the flux applicator 11 may also be one that applies the flux 7 using a predetermined dispenser.

[0037] 7, the flux application device 11 applies the flux 7 so as to collectively cover the plurality of electrodes 3 constituting one electrode group 3x. In these figures, the flux 7 is hatched for the sake of convenience, but because the flux 7 is transparent or translucent, it is not easy to clearly see the area to which the flux 7 is applied.

[0038] The flux application state inspection device 12 is used to inspect the application state of the flux 7 applied to the electrode 3. The flux application state inspection device 12 will be described later.

[0039] The component mounter 13 performs a component mounting process (mounting process) in which the electronic component 5 is mounted on the electrodes 3 etc. As a result, the electronic component 5 is placed on the electrode group 3x via the bumps 4a.

[0040] The reflow device 14 performs a reflow process for heating and melting the bumps 4a, etc. After the reflow process, the bumps 4a melt and spread over the surfaces of the electrodes 3 on the substrate 1, and finally solidify to become solder 4. The electrodes 3 and the electronic components 5 are then joined by the solder 4.

[0041] The post-reflow inspection device 15 performs a post-reflow inspection process to inspect whether the solder joints have been properly formed in the reflow process. For example, the post-reflow inspection device 15 inspects whether there is any misalignment in the electronic components 5 using image data of the board 1 after the reflow process.

[0042] In addition, although not shown, the production line 10 is equipped with conveyors or the like for transporting the boards 1 between the above-mentioned devices, such as between the flux application device 11 and the flux application state inspection device 12. Branching devices are also provided between the flux application state inspection device 12 and the component mounter 13 and downstream of the post-reflow inspection device 15. Boards 1 that have been determined to be non-defective by the flux application state inspection device 12 or the post-reflow inspection device 15 are guided directly downstream, while boards 1 that have been determined to be defective by at least one of the inspection devices 12, 15 are discharged by the branching device to a defective product storage area (not shown).

[0043] Next, we will explain the configuration of the flux application state inspection device 12. As shown in Figures 8 and 9, the flux application state inspection device 12 includes a transport mechanism 31 that transports and positions the substrate 1, an inspection unit 32 that inspects the flux 7, and a control device 33 that drives and controls 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.

[0044] 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 338 described later).

[0045] With the above configuration, when the board 1 is carried into the flux coating state inspection device 12, both side edges in the width direction perpendicular to the carrying-in / out direction are inserted into the transport rails 31a, and the board 1 is placed on the conveyor belt 31b. The conveyor belt 31b then starts operating, transporting the board 1 to a predetermined inspection position. When the board 1 reaches the inspection position, the conveyor belt 31b stops, and the chucking mechanism is activated. The operation of this chucking mechanism pushes up the conveyor belt 31b, and both side edges of the board 1 are clamped between the conveyor belt 31b and the upper edge of the transport rail 31a. This positions and fixes the board 1 at the inspection position. When the inspection is completed, the fixation by the chucking mechanism is released, and the conveyor belt 31b starts operating. This allows the board 1 to be carried out of the flux coating state inspection device 12. Of course, the configuration of the transport mechanism 31 is not limited to the above, and other configurations may be adopted.

[0046] The inspection unit 32 is disposed above the transport rail 31a (the transport path of the board 1) and 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."

[0047] 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 and 324 are driven and controlled by the control device 33 (a movement mechanism control unit 337 described later).

[0048] The lighting device 321 irradiates ultraviolet light onto the board 1 to be inspected by the flux application state inspection device 12. The wavelength of the ultraviolet light irradiated from the lighting device 321 is set to be 100 nm or more and 300 nm or less. The wavelength of the ultraviolet light is more preferably 200 nm or more and 300 nm or less, even more preferably 220 nm or more and 280 nm or less, and most preferably 230 nm or more and 260 nm or less.

[0049] Furthermore, the lighting device 321 irradiates the substrate 1 with light from vertically above or obliquely above. The incident angle θ of the ultraviolet light from the lighting device 321 onto the substrate 1 (particularly the inspection region) is set to be equal to or greater than 0° and equal to or less than 30°. It is more preferable that the incident angle θ be equal to or greater than 0° and equal to or less than 20°, even more preferably equal to or greater than 0° and equal to or less than 15°, and most preferably equal to or greater than 0° and equal to or less than 10°. In this embodiment, the process of irradiating the substrate 1 with ultraviolet light from the lighting device 321 corresponds to the "irradiation process."

[0050] 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 a predetermined inspection region KR (a region surrounded by a rectangle formed by two-dot chain lines in FIG. 7 and other figures) on the substrate 1 from directly above. In this embodiment, the inspection region KR is set for each electronic component 5 to be mounted, and is an area that includes all of the multiple electrodes 3 that make up one electrode group 3x. The inspection region KR is set by an inspection region setting unit 335, which will be described later.

[0051] The camera 322 is composed of a CCD camera or the like that is sensitive to the ultraviolet light irradiated from the lighting device 321, and its operation is controlled by the control device 33 (camera control unit 333 described later). Under the control of the control device 33, the camera 322 captures an image of the ultraviolet light reflected from the substrate 1 in the inspection region KR while the substrate 1 is being irradiated with ultraviolet light from the lighting device 321. This allows a luminance image of the inspection region KR to be acquired. The luminance image comprises 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 ultraviolet light irradiated from the lighting device 321 and reflected from the substrate 1 corresponds to the "imaging process." Furthermore, the luminance image corresponds to the "captured image."

[0052] When all of the electrodes 3 constituting one electrode group 3x are properly collectively covered with the flux 7 (see, for example, FIG. 10 ), the electrodes 3 do not appear in the inspection region KR of the luminance image, and the flux 7 appears as a dark area (see, for example, FIG. 11 ). On the other hand, when some or all of the electrodes 3 are not properly covered with the flux 7, and exposed electrodes 3e (see, for example, FIG. 12 ) are present, the exposed electrodes 3e appear as bright areas in the inspection region KR of the luminance image (see, for example, FIG. 13 ). When the electrodes 3 are individually covered with the flux 7, and some of the electrodes 3 are not properly covered, and exposed electrodes 3e (see, for example, FIG. 14 ) are present, the exposed electrodes 3e also appear as bright areas in the inspection region KR of the luminance image (see, for example, FIG. 15 ).

[0053] The luminance image acquired by the camera 322 is transferred to the control device 33 (an image acquisition unit 334 described later). The control device 33 performs an inspection process for the application state of the flux 7 based on the luminance image.

[0054] The control device 33 is composed 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 for these.

[0055] The control device 33 functions as various functional parts such as a main control unit 331, an illumination control unit 332, a camera control unit 333, an image acquisition unit 334, an inspection area setting unit 335, a judgment unit 336, a movement mechanism control unit 337, and a transport mechanism control unit 338, as the CPU operates in accordance with various programs.

[0056] However, the various functional units are realized by 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 inspection area setting unit 335 constitutes the "inspection area setting means," and the determination unit 336 constitutes the "determination means."

[0057] 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, programs, calculation results, inspection results, etc., a communication unit 343 capable of sending and receiving various data to and from the outside, etc. First, the memory unit 342 and the communication unit 343 will be described.

[0058] 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 types of information. The storage unit 342 includes an image storage unit 342a, an inspection information storage unit 342b, and an inspection result storage unit 342c.

[0059] The image storage unit 342a stores the luminance 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.

[0060] The inspection information storage unit 342b stores various information used in inspecting the flux 7. For example, the inspection information storage unit 342b stores various thresholds used when binarizing a luminance image or determining whether the flux 7 is good or bad, as well as design data and manufacturing data. The design data and manufacturing data include the planned application area of ​​the flux 7, the size of the flux 7 in an ideal application state (e.g., the area and contour length of the flux 7), the mounting area of ​​the electronic component 5, etc.

[0061] The inspection result storage unit 342c stores inspection result data relating to the application state of the flux 7 by the determination unit 336. The inspection result storage unit 342c also stores statistical data obtained by processing the inspection result data probabilistically. The inspection result data and statistical data can be displayed on the display unit 341 as appropriate.

[0062] 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 results of the inspection performed by the determination unit 336 are output to the outside via the communication unit 343, and the results of the inspection performed by the post-reflow inspection device 15 are input via the communication unit 343.

[0063] Next, a detailed description will be given of the various functional units that constitute the control device 33. First, the movement mechanism control unit 337 and the transport mechanism control unit 338 will be described, and then the main control unit 331 and the like will be described.

[0064] The movement mechanism control unit 337 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. By driving and controlling the X-axis movement mechanism 323 and the Y-axis movement mechanism 324, the movement mechanism control unit 337 can move the inspection unit 32 to a position above any inspection region KR on the substrate 1 that is positioned and fixed at the inspection position. Then, the inspection unit 32 is moved sequentially to the multiple inspection regions KR set on the substrate 1, and inspections related to the inspection regions KR are performed, thereby inspecting the flux 7 in all of the inspection regions KR.

[0065] The transport mechanism control unit 338 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 .

[0066] 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 send and receive various signals to and from other functional units such as the illumination control unit 332 and the camera control unit 333.

[0067] 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 controls the timing of starting and stopping irradiation of light from the illumination device 321 onto the substrate 1.

[0068] The camera control unit 333 is a functional unit that controls the driving of the camera 322. The camera control unit 333 controls the timing of the imaging operation of the camera 322 based on a command signal from the main control unit 331.

[0069] The image capture unit 334 is a functional unit for capturing the luminance image captured and acquired by the camera 322. The luminance image captured by the image capture unit 334 is stored in the image storage unit 342a.

[0070] The inspection area setting unit 335 sets an inspection area KR for each electronic component 5 based on the marks 8 provided on the board 1. In this embodiment, the inspection area setting unit 335 sets the inspection area KR corresponding to the area to be coated with flux 7. More specifically, the inspection area setting unit 335 determines the area to be coated with flux 7 based on the predetermined marks 8 provided on the board 1 and the design data and manufacturing data stored in the inspection information storage unit 342b, and sets the inspection area KR from the determined area to be coated. In this embodiment, the inspection area KR is set to an area slightly larger than the area to be coated with flux 7 and to an area that includes all electrodes 3 to which the flux 7 is to be applied. In this embodiment, the process of setting the inspection area KR by the inspection area setting unit 335 corresponds to the "inspection area setting process." Note that the inspection area KR may also be set based on the mounting area of ​​the electronic component 5 in the design data and manufacturing data.

[0071] The determination unit 336 inspects the flux 7 applied to the substrate 1. More specifically, the determination unit 336 first obtains a binary image by performing a binarization process on the brightness image based on the threshold value stored in the inspection information storage unit 342b. In the binary image, areas corresponding to the flux 7 are dark areas (0), and areas corresponding to the electrodes 3 that are not covered with the flux 7 and are exposed to the outside are bright areas (1).

[0072] Next, the determination unit 336 performs a process of identifying connected components of pixels corresponding to bright areas in the binarized image, and calculates the area (number of pixels in this embodiment) of each identified connected component (clump portion). As a result, the determination unit 336 calculates the area of ​​the portion not covered by the flux 7 in each of the plurality of electrodes 3 constituting the electrode group 3 x.

[0073] The determination unit 336 then compares the calculated area of ​​the lump portion with an area threshold pre-stored in the inspection information storage unit 342b. If the area of ​​at least one lump portion is equal to or greater than the area threshold, the determination unit 336 determines that the flux 7 has not been sufficiently applied to at least one electrode 3, and determines the application state of the flux 7 to be "poor." On the other hand, if the areas of all the lump portions are below the area threshold, the determination unit 336 determines that the flux 7 has been properly applied to the multiple electrodes 3 constituting one electrode group 3x, and determines the application state of the flux 7 to be "good."

[0074] The determination unit 336 then performs the above-described determination on all of the inspection regions KR, and if the determination unit 336 determines that the application state of the flux 7 in at least one of the inspection regions KR is "bad," the determination unit 336 determines the substrate 1 to be inspected as "bad" in terms of the application state of the flux 7. On the other hand, if the determination unit 336 performs the above-described determination on all of the inspection regions KR and determines that the application state of the flux 7 in all of the inspection regions KR is "good," the determination unit 336 determines the substrate 1 to be inspected as "good" in terms of the application state of the flux 7. The pass / fail determination result (inspection result data) is stored in the inspection result storage unit 342c. In this embodiment, the process in which the determination unit 336 performs a pass / fail determination on the application state of the flux 7 corresponds to the "determination process."

[0075] As described above in detail, according to this embodiment, the inspection area setting unit 335 does not set an inspection area for each individual electrode 3, but sets one inspection area KR corresponding to multiple electrodes 3 on which one electronic component 5 will be mounted. Therefore, it is sufficient to set the inspection area KR relatively roughly, and the inspection area KR can be set through relatively simple processing. This reduces the processing load and thereby improves inspection efficiency.

[0076] Furthermore, the determination unit 336 calculates the area of ​​each inspection region KR (the area of ​​the bright connected components) having a brightness equal to or greater than a predetermined brightness threshold, and determines the state of application of the flux 7 based on the calculated area. Therefore, the state of application of the flux 7 can be inspected not for each of the electrodes 3 corresponding to one electronic component 5, but for all of these electrodes 3 at once. This makes it possible to obtain good inspection accuracy even while setting a relatively rough inspection region KR. This ensures sufficient inspection accuracy even when inspecting a board 1 on which multiple electrodes 3 are provided at an extremely small pitch (e.g., a board on which a BGA is mounted).

[0077] Furthermore, since the wavelength of the ultraviolet light emitted from the lighting device 321 is set to 100 nm or more and 300 nm or less, the ultraviolet light is more easily absorbed by the flux 7. Therefore, the flux 7 can be made darker in the luminance image, and the difference in luminance between the electrode 3 and the flux 7 can be made larger. This allows the flux 7 and the electrode 3 to be identified more accurately, further improving the inspection accuracy.

[0078] Furthermore, because the incident angle θ of the ultraviolet light irradiated onto the substrate 1 from the lighting device 321 is set to be between 0° and 30°, the ultraviolet light reflected by the electrode 3 is more likely to reach the imaging means. Therefore, the difference in brightness between the electrode 3 and the flux 7 in the brightness image can be made even larger. As a result, the flux 7 and the electrode 3 can be more accurately identified in the brightness image, thereby further improving inspection accuracy.

[0079] In addition, since the illumination device 321 irradiates ultraviolet light instead of visible light, even if the flux 7 is transparent or translucent, the flux 7 can be displayed as a dark area in the luminance image. Therefore, even if the flux 7 to be inspected is transparent or translucent, the application state of the flux 7 can be inspected with high accuracy.

[0080] In addition, because the substrate 1 is a glass epoxy substrate, the electrodes 3 and the substrate 1 (particularly the substrate portion 6) are more easily differentiated in the brightness image, allowing the area of ​​the bright portion (electrodes 3) to be identified more accurately, thereby further improving inspection accuracy.

[0081] 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.

[0082] (a) In the above embodiment, the determination unit 336 calculates the area of ​​the portion of each of the plurality of electrodes 3 constituting the electrode group 3x that is not covered with the flux 7. Alternatively, the determination unit 336 may calculate the total area of ​​the portions of these electrodes 3 that are not covered with the flux 7. The determination unit 336 may then compare the calculated total area with an area threshold to determine whether the application state of the flux 7 is good or bad.

[0083] (b) In the above embodiment, the substrate 1 is a glass epoxy substrate, but other types of substrates may also be used. For example, the substrate 1 may be a ceramic substrate.

[0084] (c) In the above embodiment, the flux 7 is transparent or translucent, but it may also be opaque.

[0085] In the above embodiment, the flux 7 covers all of the electrodes 3 constituting one electrode group 3x collectively, but it may also cover these electrodes 3 individually.

[0086] (d) In the above embodiment, a BGA is used as the electronic component 5, but the electronic component 5 may be other semiconductor packages (for example, a CSP (Chip Size Package)).

[0087] 1...printed circuit board (circuit board), 3...electrode, 5...electronic component (component), 7...flux, 12...flux application state inspection device, 321...illumination device (irradiation means), 322...camera (imaging means), 335...inspection area setting section (inspection area setting means), 336...judgment section (judgment means), KR...inspection area.

Claims

1. A flux application state inspection device for inspecting flux that is applied to electrodes of a circuit board and is capable of absorbing ultraviolet light, comprising: an irradiation means capable of irradiating ultraviolet light onto the circuit board; an imaging means capable of imaging the ultraviolet light irradiated onto the circuit board; an inspection area setting means for setting, for each component, an inspection area on the circuit board that corresponds to a component to be mounted and includes a plurality of electrodes on which the component will be mounted, using a reference portion provided on the circuit board as a reference; and a judgment means for irradiating the inspection area with ultraviolet light by the irradiation means while imaging the ultraviolet light irradiated onto the inspection area by the imaging means, and for making a pass / fail judgment regarding the application state of the flux, wherein the judgment means is configured to calculate, for each inspection area, an area of ​​a portion in the inspection area that has a brightness equal to or greater than a predetermined brightness threshold, and to judge the application state of the flux based on the calculated area.

2. The flux application state inspection device according to claim 1, characterized in that the wavelength of the ultraviolet light irradiated from said irradiating means is set to 100 nm or more and 300 nm or less.

3. The flux application state inspection device according to claim 1, characterized in that the imaging means is disposed above the substrate with its optical axis perpendicular to the substrate, and the angle of incidence of the ultraviolet light irradiated from the irradiation means onto the substrate is set to be between 0° and 30°.

4. The flux application state inspection device according to claim 1, characterized in that it is used to inspect transparent or semi-transparent flux.

5. The flux application state inspection device according to claim 1, which is used to inspect the flux applied to the electrodes of a glass epoxy board as the board.

6. A flux application state inspection method for inspecting flux that is applied to electrodes of a substrate and is capable of absorbing ultraviolet light, comprising: an irradiation step of irradiating the substrate with ultraviolet light; an imaging step of imaging the ultraviolet light irradiated onto the substrate; an inspection area setting step of setting, for each component, an inspection area on the substrate that corresponds to the component to be mounted and includes a plurality of electrodes on which the component will be mounted, using a reference portion provided on the substrate as a reference; and a judgment step of judging the pass / fail state of the flux application state based on an image obtained by imaging the ultraviolet light irradiated onto the inspection area in the imaging step while irradiating the inspection area with ultraviolet light in the irradiation step, wherein the judgment step calculates an area of ​​a portion in the inspection area that has a brightness equal to or higher than a predetermined brightness threshold value, and judges the application state of the flux based on the calculated area.

Images