JP4660441B2 - Substrate inspection device, substrate inspection method, and program for causing a computer to function as the inspection device - Google Patents

Description

  The present invention relates to a technique for inspecting the mounting state of components mounted on both surfaces of a substrate. More specifically, the present invention relates to an inspection apparatus, an inspection method, and a program for causing a computer to function as the inspection apparatus for inspecting the soldering state of electronic components respectively soldered to both surfaces of a substrate. .

  When an electronic component is soldered to a substrate, there is an optical appearance inspection apparatus using an optical system such as a CCD (Charge Coupled Device) camera as a method for inspecting the soldering state. The optical appearance inspection apparatus can detect misalignment of electronic components such as chip components or ICs (Integrated Circuits) mounted on a substrate, joint defects such as solder bridges, and the like. Therefore, the appearance inspection apparatus is effective as a soldering inspection method after “reflow” which is one of the soldering methods, and is widely spread.

  Meanwhile, in recent years, in the market of electronic devices such as portable information devices, there is a demand for smaller and lighter products. For this reason, there is an increasing demand for high-density mounting on a substrate constituting an electronic device.

  Therefore, for electronic components, BGA (Ball Grid Array), in which the package size is reduced by providing electrodes on the back surface of the electronic component, and CSP (Chip Size Package) in which BGA is further reduced to the same size as the semiconductor bare chip. Such package parts are now widely adopted.

  Also, a connector that connects a mounting board on which electronic components are mounted to the mounting board adopts a structure in which the connection terminals are exposed from the lower part of the connector body as the connector itself is downsized.

  By the way, in a mounting board on which electronic components are mounted, if there is a defect in a soldered portion, the electronic device does not operate normally. For this reason, it is necessary to recover a mounted substrate having a bonding failure at the earliest possible stage in the manufacturing process of the substrate and repair or discard it.

  However, in the above-described BGA, CSP, or connector, it is difficult to confirm the quality of the soldered portion from above the mounting board because the soldered portion is on the back surface of the electronic component. For this reason, the optical appearance inspection apparatus, like conventional electronic components with leads, cannot inspect the soldered portion. As a result, the defect of the soldering portion that cannot be confirmed by the optical appearance inspection apparatus is first discovered by the function inspection after the electronic device is assembled to the operable state. That is, it has been necessary to go through a useless assembly process even on a mounting board with poor soldering.

  In order to improve this, as a method of judging the quality of the soldering part of the mounting board to which the electronic component whose soldering part cannot be confirmed is bonded, X-rays are irradiated from one surface side of the mounting board, and the other On the surface side, an effort is made to detect X-rays transmitted through the mounting board and inspect the soldered portion based on an image (X-ray transmission image) obtained from the detected X-rays.

  However, according to the inspection based on such an X-ray transmission image, when the target of the pass / fail determination is a mounting board in which electronic components are bonded on both sides (hereinafter referred to as “double-side mounting board”), In some cases, an image of an electronic component such as a chip resistor or a chip capacitor on the back surface overlaps an X-ray transmission image in the vicinity of a certain soldered portion, and the soldered portion cannot be accurately inspected.

  Therefore, as a method for inspecting a double-sided mounting board using X-rays, an X-ray generator arranged to irradiate the double-sided mounting board obliquely with X-rays and X-rays transmitted through the double-sided mounting board are detected. The X-ray detector is rotated in synchronism with each other on a plane parallel to the double-sided mounting board, and a fixed height of the double-sided mounting board is focused and other surfaces with different heights are rotated. There is a method of obtaining an image of a horizontal section of the double-sided mounting board by blurring. An X-ray inspection apparatus using a technique called X-ray laminography that can individually inspect the front side and the back side of a double-sided mounting board has been put into practical use.

  However, any of the above devices has a complicated structure, is expensive, and requires a very long inspection time, so that it can be used at the research level but cannot be used at the mass production level. is there.

  Therefore, for example, in Japanese Patent Laid-Open No. 5-288538 (Patent Document 1), since the soldering portions overlap on the front and back of the substrate, the image data on the front and back are completely independent even when they cannot be completely separated and detected. A method for inspecting soldering of a substrate that can be inspected is disclosed.

  This method includes a step of irradiating a mounting board having electronic components soldered to the front and back surfaces to obtain X-ray transmission image data, and an electronic component only on the front surface or the back surface from the X-ray transmission image data. A step of obtaining image data by subtracting X-ray transmission image data of a mounting board to which solder is normally soldered, and an X-ray transmission image of the mounting board in which electronic components are normally soldered only on the back surface or the front surface And determining whether the soldered part is good or bad from the comparison with the above.

  Japanese Patent Laid-Open No. 2001-50730 (Patent Document 2) detects distortion of a printed circuit board due to heat, corrects this distortion, and subtracts the single-sided mounted image from the double-sided mounted image, thereby causing the distortion of the printed circuit board. Disclosed is a soldering inspection method for a double-sided mounting board that can inspect the soldering state without error.

The inspection method includes a step of obtaining a first image by irradiating a printed board on which an electronic component is mounted on one side with X-rays, and an X on a printed board on which the electronic component is mounted on the other side of the printed board. Irradiating a line to obtain a second image; storing the first image and the second image in an image memory; obtaining a displacement amount from the first image and the second image; A step of correcting the first image or the second image by the determined amount of displacement, a step of subtracting the first image from the second image to obtain an image on the other side, and a soldering unit Determining whether the quality is good or bad.
JP-A-5-288538 JP 2001-50730 A

  However, according to the technique disclosed in Japanese Patent Application Laid-Open No. 5-288538, the first image data of the mounting board in which electronic components are soldered on both sides and the front surface or the back surface are normally used as the image data. Three image data of the second image data and the third image data soldered are required.

  Further, since the pass / fail judgment is made by subtracting the second image data and the third image data from the first image data, the electronic component is mounted only on the front surface and mounted only on the back surface. Two substrates for inspection of the mounted substrate are required. Since the two mounting boards need to have electronic components normally soldered, the completeness of the two mounting boards is important, and it takes time and money to manufacture these boards.

  Furthermore, since the board on which the electronic component is first mounted on the surface on which the electronic component is mounted later cannot mount the electronic component on the opposite surface after the inspection, the mounting board prototyped as a sample is There is also the problem of being wasted.

  In addition, according to the techniques disclosed in Japanese Patent Laid-Open Nos. 5-288538 and 2001-50730, a great deal of storage is required for storing an image of a mounting board on which one electronic component is mounted on one side. There was also a problem that a large amount of memory was required and it was physically impossible to realize.

  Furthermore, in order to eliminate over-determination (determining that a product is defective even though it is a non-defective product), the board on which the electronic component is mounted only on one side and the board mounted on both sides are the same mounting board. It is necessary to confirm. Therefore, there is a problem that it is necessary to make both correspond completely one-on-one.

  Moreover, even if the images of the same mounting board are matched one-on-one, in the soldering operation using reflow or the like, in addition to the warping of the mounting board disclosed in JP-A-2001-50730, The solder shape may change due to remelting. In this case, “deviation” occurs between the images. Therefore, even if the process of subtracting the transmission image disclosed in Japanese Patent Application Laid-Open No. 2001-50730 is performed, for example, a complete image of only the back surface is not always obtained, and there is a problem that noise is included. there were. That is, there is a problem in that a positional deviation occurs between the X-ray transmission image of the double-sided mounting board and the X-ray transmission image of the single-sided mounting board, and that part remains as noise, and correct inspection cannot be performed. Therefore, the X-ray inspection using the image difference has not reached a practical level until now.

  The present invention has been made to solve the above-described problems, and its purpose is to inspect a board for determining whether the soldering is good or not in a board in which electronic parts are soldered on both sides. Is to provide a device.

  Another object of the present invention is to provide a method for inspecting a substrate for judging whether or not the soldering is good in a substrate in which electronic parts are soldered on both sides.

  Still another object of the present invention is to provide a program for causing a computer to function as a board inspection apparatus for judging whether soldering is good or not in a board on which electronic parts are soldered on both sides.

  In order to solve the above problems, according to one aspect of the present invention, a substrate inspection apparatus includes a storage unit that stores data and a processing unit that performs an operation using the data. The processing unit includes means for acquiring first transmission image data representing an image based on X-rays transmitted through the substrate. A first component is bonded to the first surface of the substrate. The processing unit obtains first optical image data representing an image based on visible light irradiated on the first surface, and association means for associating the first transmission image data and the first optical image data. Means for obtaining second transmission image data representing an image based on X-rays transmitted through the substrate after the second component is bonded to the second surface opposite to the first surface; Means for obtaining second optical image data representing an image based on visible light applied to the first surface after the second part is bonded to the second surface opposite to the surface; Based on the comparison result between the optical image data and the second optical image data, and the comparison between the first optical image data and the second optical image data, the third transmission image data is compared with the third transmission image data. First generation means for generating transmission image data; and second transmission image data. And second transmission means for generating fourth transmission image data representing the second surface based on the third transmission image data, and the bonding state on the substrate based on the fourth transmission image data. Judgment means for judging.

  Preferably, the comparison unit includes an acquisition unit that acquires information representing the position of the first component on the substrate by comparing the first optical image data and the second optical image data. The first generation unit generates third transmission image data by correcting the first transmission image data based on the information. The second generation means generates fourth transmission image data by subtracting the third transmission image data from the second transmission image data. The determining means compares the teaching data representing the image based on the X-rays transmitted through the substrate to which the second component is bonded according to the predetermined design information with the fourth transmission image data, thereby comparing the second transmission image data with the second transmission image data. Judge the state of joining parts.

  Preferably, the obtaining unit recognizes a first reference image representing a predetermined position on the substrate based on the first optical image data, and the first optical image data based on the first optical image data. Means for recognizing a first partial image corresponding to a predetermined location in the part, and first calculation means for calculating first data representing a positional relationship between the first reference image and the first partial image. And a means for recognizing a second reference image representing a position based on the second optical image data, and a second partial image corresponding to a predetermined location based on the second optical image data. A means for recognizing; a second calculating means for calculating second data representing a positional relationship between the second reference image and the second partial image; and calculating a difference between the first data and the second data. Means.

  Preferably, the first calculation means applies the distance between the first reference image and the first partial image, a straight line connecting the first reference image and the first partial image, and the first component. An angle formed by a predetermined reference line is calculated. The second calculation means calculates a distance between the second reference image and the second partial image, a straight line connecting the second reference image and the second partial image, and an angle formed by the reference line. calculate.

  Preferably, the associating means represents the position from the first transmission image data, the first recognizing means for recognizing a first reference image representing a predetermined position on the substrate, and the first optical image data. Second recognition means for recognizing the second reference image, means for matching the first reference image with the second reference image, data for identifying the first component, and the first reference image Or means for associating with the second reference image.

Preferably, the predetermined position represents a position of a mark previously formed on the substrate.
Preferably, a wiring pattern based on design data defined in advance is formed on the substrate. The first recognizing unit and the second recognizing unit each recognize an image representing a wiring pattern.

  When the other situation of this invention is followed, the inspection method of the board | substrate which the processor with which a computer is provided performs is provided. The method includes obtaining first transmission image data representing an image based on X-rays transmitted through the substrate. A first component is bonded to the first surface of the substrate. The method includes obtaining first optical image data representing an image based on visible light irradiated on the first surface, and associating the first transmission image data with the first optical image data. Obtaining second transmission image data representing an image based on X-rays transmitted through the substrate after the second component is bonded to the second surface opposite to the first surface; Obtaining second optical image data representing an image based on visible light applied to the first surface after the second part is bonded to the second surface opposite to the surface; Based on the result of the comparison between the optical image data and the second optical image data, and the comparison between the first optical image data and the second optical image data, A first generation step for generating transmission image data A second generation step for generating fourth transmission image data representing the second surface based on the second transmission image data and the third transmission image data, and the fourth transmission image data. And a determination step of determining a bonding state on the substrate.

  Preferably, the comparison step includes a step of obtaining information representing the position of the first component on the substrate. In the first generation step, third transmission image data is generated by correcting the first transmission image data based on the information. In the second generation step, fourth transmission image data is generated by subtracting the third transmission image data from the second transmission image data. In the determination step, the second transmission image data is compared with teaching data representing an image based on X-rays transmitted through the substrate to which the second component is bonded in accordance with predetermined design information. Judge the state of joining parts.

  Preferably, the step of acquiring information includes recognizing a first reference image representing a predetermined position on the substrate based on the first optical image data, and based on the first optical image data. A step of recognizing a first partial image corresponding to a predetermined location in the first component, and a first data for calculating first data representing a positional relationship between the first reference image and the first partial image; A step of recognizing a second reference image representing a position based on the second optical image data, and a second corresponding to a predetermined location based on the second optical image data. A step of recognizing a partial image, a second calculation step of calculating second data representing a positional relationship between the second reference image and the second partial image, and the first data and the second data Calculate the difference Tsu and a flop.

  Preferably, in the first calculation step, the distance between the first reference image and the first partial image, a straight line connecting the first reference image and the first partial image, and the first component An angle formed by a predetermined reference line is calculated. The second calculation step includes a distance between the second reference image and the second partial image, a straight line connecting the second reference image and the second partial image, and an angle formed by the reference line. calculate.

  Preferably, the associating step recognizes a first reference image representing a predetermined position on the substrate from the first transmission image data, and a second reference representing the position from the first optical image data. A step of recognizing an image, a step of matching the first reference image and the second reference image, data for identifying the first component, and the first reference image or the second reference image. And associating.

Preferably, the predetermined position represents a position of a mark previously formed on the substrate.
Preferably, a wiring pattern based on design data defined in advance is formed on the substrate. The step of recognizing the first reference image and the step of recognizing the second reference image each recognize an image representing a wiring pattern.

  According to still another aspect of the present invention, a program for causing a computer to function as a substrate inspection apparatus is provided. The program causes the computer to execute a step of obtaining first transmission image data representing an image based on X-rays transmitted through the substrate. A first component is bonded to the first surface of the substrate. The program acquires, in the computer, first optical image data representing an image based on visible light irradiated on the first surface, and associating the first transmission image data and the first optical image data. Obtaining second transmission image data representing an image based on X-rays transmitted through the substrate after the second component is bonded to the second surface opposite to the first surface; Obtaining second optical image data representing an image based on visible light applied to the first surface after the second part is bonded to the second surface opposite to the surface; Based on the result of the comparison between the optical image data and the second optical image data and the comparison between the first optical image data and the second optical image data, the first transmission image data to the third transmission image data. Generating image data; and Generating fourth transmission image data representing the second surface based on the second transmission image data and the third transmission image data; and joining the substrate on the substrate based on the fourth transmission image data. And determining a state.

  According to the inspection apparatus according to the present invention, when the electronic component is soldered to both surfaces of the substrate, it is possible to determine whether the soldering is good or bad.

  According to the inspection method of the present invention, when an electronic component is soldered to both surfaces of a substrate, it is possible to provide a substrate inspection method for determining whether the soldering is good or bad.

  According to the program according to the present invention, the computer can function as a board inspection device for judging whether or not the soldering of the board on which the electronic components are soldered on both sides is good.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following description, the same parts are denoted by the same reference numerals. Their names and functions are also the same. Therefore, detailed description thereof will not be repeated.

  With reference to FIG. 1, the manufacturing process 100 of the board | substrate (henceforth a "mounting board | substrate") with which the electronic component was mounted is demonstrated. FIG. 1 is a diagram conceptually showing the manufacturing process 100. The manufacturing process 100 includes a joining process 110, an inspection process 120, an assembly process 130, and a determination process 140.

  In the bonding step 110, a substrate to be mounted with electronic components is carried. In addition, an electronic component to be mounted on the substrate and a bonding material (for example, “solder”) are supplied. The supplied electronic component is joined to the substrate by solder. The board is carried into, for example, a reflow furnace and the solder is melted. The mounting board on which the electronic components are soldered is carried from the joining process 110 to the inspection process 120.

  In the inspection step 120, the mounting substrate is selected. More specifically, it is determined whether or not the mounting board is a non-defective product according to a standard prepared in advance. If the mounting board is a non-defective product, the board is carried into the assembling step 130, and mounting of other electronic components and mounting of other types of mounting boards are further performed. On the other hand, when the mounting board is defective, the mounting board is transferred to the determination step 140. In the determination step, it is determined whether or not the mounting board determined to be defective can be reworked. The mounting board that is determined to be reworkable is replaced with a defective part only, or the soldered portion is repaired, and is again carried into the inspection process 120 as a rework product. On the other hand, the mounting board determined to be impossible to rework is discarded.

  With reference to FIG. 2, the bonding step 110 will be further described. FIG. 2 is a flowchart showing a series of processes in the joining step 110.

  In step S210, the solder supply device (not shown) arranged in the joining step 110 prints the solder paste on one side (or “front side”) of the carried-in board. In step S220, the component supply device (not shown) places (that is, temporarily places) the supplied electronic component on the solder paste. In step S230, the substrate (mounting substrate) on which the electronic component is arranged is carried into a reflow furnace. In the reflow furnace, melting of the solder and adhesion between the electronic component and the substrate are performed based on preset heating conditions (for example, heating time such as temperature and belt speed). In step S240, the mounting board is unloaded from the reflow furnace. Here, in a state where electronic components are mounted only on one side of the substrate, the mounting substrate is carried into the inspection system 300 shown in FIG. get. At that time, the mounting state of the electronic component on only one side may be inspected to be OK / NG. Thereafter, the mounting substrate is turned upside down.

  In step S250, the solder supply apparatus prints the solder paste on the back surface (or “B” surface) that is the surface opposite to the front surface of the mounting substrate. In step S260, the component supply device places another electronic component on the solder paste. In step S270, the mounting board on which the other electronic component is arranged is carried into a reflow furnace. In the reflow furnace, melting of the solder and fixing of the other electronic component and the substrate are performed under a predetermined heating condition in order to join the other electronic component to the substrate. In step S280, the mounting substrate on which the other electronic components are fixed is carried out of the reflow furnace.

  With reference to FIG. 3, the structure of the test | inspection system 300 which concerns on embodiment of this invention is demonstrated. FIG. 3 is a block diagram showing a configuration of functions realized by inspection system 300. The inspection system 300 includes an imaging device 310 and an inspection device 320. The imaging device 310 and the inspection device 320 are connected by cables 390 and 392. Cables 390 and 392 are, for example, cables for a LAN (Local Area Network). Alternatively, a wireless LAN may be used instead of the cables 390 and 392.

  The imaging device 310 includes an X-ray irradiation unit 311, an X-ray imaging unit 312, an imaging unit 313, a visible light supply unit 314, and an imaging device drive unit 315.

  The imaging device driving unit 315 controls each operation of the X-ray irradiation unit 311, the X-ray imaging unit 312, the imaging unit 313, and the visible light supply unit 314 based on a command input to the imaging device 310. More specifically, the imaging device driving unit 315 sends a command for irradiating X-rays to the X-ray irradiation unit 311 based on an input of an irradiation command based on a predetermined condition. The X-ray irradiation unit 311 emits X-rays corresponding to the conditions based on the command.

  In response to sending a command to the X-ray irradiation unit 311, the imaging device driving unit 315 issues a command for capturing an image based on X-rays that have passed through the subject (for example, a mounting substrate) to the X-ray imaging unit 312. Send it out.

  The X-ray imaging unit 312 captures an X-ray image of the subject based on a command issued to the imaging device driving unit 315. The X-ray imaging unit 312 is, for example, an area sensor type camera, but may be any other imaging device, at least a device capable of imaging a portion where the appearance cannot be optically captured. More specifically, any device that can observe the bonding state of BGA / CSP, the bridge of the lead under the connector, and the back fillet of the lead of the IC may be used.

  In addition, the imaging device driving unit 315 sends a command to supply visible light based on a predetermined condition to the visible light supply unit 314. Based on the command, the visible light supply unit 314 supplies visible light (for example, white light) to the subject (for example, the mounting board) based on the conditions. In response to sending a command to the visible light supply unit 314, the imaging device driving unit 315 sends a command for taking an optical image of the subject to the imaging unit 313. The imaging unit 313 acquires an image of the subject based on the command.

  Each data of the X-ray transmission image acquired by the X-ray imaging unit 312 or the optical image acquired by the imaging unit 313 is temporarily stored in a buffer memory (not shown), and then output to an output interface (not shown). It is sent to the inspection device 320 via the cable 392.

  Referring back to FIG. 3, the inspection apparatus 320 includes an image data input unit 322, a storage unit 324, an operation unit 326, a display unit 328, and a control unit 330. The control unit 330 includes an arithmetic processing unit 331, an imaging device control unit 332, a determination unit 333, and an image processing unit 340. The image processing unit 340 includes a data processing unit 341, an image comparison unit 342, an image generation unit 343, and a difference calculation unit 344.

  The image data input unit 322 receives input of data transmitted from the imaging device 310 via the cable 392. More specifically, the image data input unit 322 receives input of data representing an X-ray transmission image acquired by the X-ray imaging unit 312 and data representing an optical image acquired by the imaging unit 313.

  The storage unit 324 stores data prepared in advance for realizing the inspection device 320 (for example, a program for executing each process, data for executing a specific operation, specifically, a non-defective / non-compliant mounting board). (Reference data used for non-defective product judgment). The storage unit 324 stores data generated by the control unit 330 or data representing an X-ray transmission image and data representing an optical image input to the image data input unit 322.

  The operation unit 326 receives an input of an operation by a user of the inspection device 320. The operation unit 326 sends an electrical signal corresponding to the input of the operation to the control unit 330.

  The display unit 328 displays the result of the process executed by the inspection device 320 based on the data generated by the control unit 330. For example, the display unit 328 displays an image of a substrate to be inspected in the inspection system 300 or displays an inspection result (that is, a non-defective product / defective product) of the substrate. Further, the display unit 328 displays an image based on other data stored in the storage unit 324 based on a command from the control unit 330.

  The control unit 330 includes the image data input unit 322 and the control unit 330 so that the control unit 330 can operate based on the output from the image data input unit 322, the data stored in the storage unit 324, and the command output from the operation unit 326. The storage unit 324 and the operation unit 326 are connected.

  The arithmetic processing unit 331 stores data representing an X-ray transmission image and data representing an optical image acquired via the image data input unit 322 in an area secured in advance in the storage unit 324. The arithmetic processing unit 331 generates a command for causing the imaging device 310 to execute a predetermined operation based on data stored in the storage unit 324 or based on an operation on the operation unit 326, and the imaging device The data is sent to the control unit 332. When the imaging device 310 is in a state where the command can be input, the imaging device control unit 332 sends the command to the imaging device 310 via the cable 390.

  The arithmetic processing unit 331 further sends the data acquired by the image data input unit 322 or the data stored in the storage unit 324 to the image processing unit 340.

  More specifically, the arithmetic processing unit 331 acquires first transmission image data representing an image based on X-rays transmitted through the substrate. The arithmetic processing unit 331 acquires first optical image data representing an image based on visible light irradiated on the first surface (for example, “front surface”) of the substrate, and based on the transmitted X-ray. First transmission image data representing an image is acquired. Further, the arithmetic processing unit 331 associates the first transmission image data with the first optical image data, and stores data representing the association in the storage unit 324.

  In the image processing unit 340, the data processing unit 341 performs a predetermined process (for example, binarization process) on the input image data.

  The arithmetic processing unit 331 displays an image based on X-rays transmitted through the substrate after the second electronic component is bonded to the second surface (for example, “back surface”) opposite to the first surface of the substrate. The second transparent image data to be represented is acquired. The arithmetic processing unit 331 includes a second optical image representing an image based on visible light irradiated on the first surface after the second electronic component is bonded to the second surface opposite to the first surface. Get the data.

  The image comparison unit 342 compares the first optical image data and the second optical image data. Furthermore, the image comparison unit 342 acquires information representing the position of the component on the board based on the comparison. More specifically, the image comparison unit 342 recognizes a first reference image representing a predetermined position on the substrate based on the first optical image data. Based on the first optical image data, the image comparison unit 342 recognizes a first partial image corresponding to a location defined in advance in the first electronic component.

  The image comparison unit 342 calculates first data representing the positional relationship between the first reference image and the first partial image. The image comparison unit 342 recognizes a second reference image representing the position determined in advance on the substrate based on the second optical image data. The image comparison unit 342 recognizes a second partial image corresponding to the predetermined location based on the second optical image data. The image comparison unit 342 calculates second data representing the positional relationship between the second reference image and the second partial image. The image comparison unit 342 calculates the difference between the first data and the second data.

  The image generation unit 343 generates third transmission image data from the first transmission image data based on the comparison result by the image comparison unit 342. More specifically, the image generation unit 343 generates third transmission image data by correcting the first transmission image data based on information representing the position of the first electronic component on the board. Furthermore, the image generation unit 343 generates fourth transmission image data representing the second surface based on the second transmission image data and the third transmission image data. More specifically, the image generation unit 343 generates fourth transmission image data by subtracting the third transmission image data from the second transmission image data.

  The determination unit 333 determines the bonding state of the electronic component on the substrate based on the fourth transmission image data. More specifically, the determination unit 333, according to predetermined design information, teaching data representing an image based on X-rays transmitted through the substrate to which the second electronic component is bonded, fourth transmission image data, To determine the joining state of the second electronic component. Here, the design information is stored in advance in the storage unit 324, for example. The data structure in the storage unit 324 will be described later.

  Further, the image processing unit 340 predefines the distance between the first reference image and the first partial image, the straight line connecting the first reference image and the first partial image, and the first component. The angle formed by the reference line thus calculated is calculated. Further, the image processing unit 340 includes an angle formed by a distance between the second reference image and the second partial image, a straight line connecting the second reference image and the second partial image, and the reference line. And calculate.

  In another aspect, arithmetic processing unit 331 recognizes a first reference image representing a predetermined position on the substrate from the first transmission image data. The arithmetic processing unit 331 recognizes a second reference image representing the position from the first optical image data. The arithmetic processing unit 331 matches the first reference image with the second reference image. The arithmetic processing unit 331 associates data for identifying the first component with the first reference image or the second reference image.

  Here, the predetermined position represents the position of a mark formed in advance on the substrate, but the mark is not limited to that formed in advance. In another aspect, a wiring pattern based on design data defined in advance may be formed on a substrate to be inspected. In this case, when executing the process for recognizing the first reference image and the process for recognizing the second reference image, the arithmetic processing unit 331 can recognize each image representing the wiring pattern on the board. .

  With reference to FIG. 4, the data structure of inspection apparatus 320 according to the embodiment of the present invention will be described. FIG. 4 is a diagram conceptually showing one mode of data storage in storage unit 324 included in inspection device 320. The storage unit 324 includes a plurality of areas for storing data or programs.

  For example, data (“component code”) for identifying an electronic component to be inspected for a bonding state with respect to the substrate is stored in area 410. Dimension data representing the size of the electronic component is stored in area 412. Data for identifying the substrate to which the electronic component is bonded is stored in area 414. Data for specifying the position of the electronic component on the substrate (for example, coordinate data of four corners when the electronic component is rectangular) is stored in regions 416 to 418, respectively.

  Here, a certain component may be used for a specific substrate, and the same component may be used for a plurality of different substrates. Therefore, in the storage unit 324, each of the above data is stored as design data for each of a plurality of substrates for the same component.

  Furthermore, teaching data acquired in advance for each electronic component is also stored in the storage unit 324. More specifically, data for identifying the electronic component is stored in area 420. Data (“reference data”) of an image captured with visible light and X-rays in a state where the electronic component is bonded to the substrate is stored in the area 422. The data stored in the area 420 and the data stored in the area 422 are associated with each other. Therefore, by specifying any part code of the electronic part, the reference data is specified and can be associated with the design data.

  The storage unit 324 further includes an operating system 430 for executing basic operations (for example, data input / output, image display, operation input reception, etc.) of the inspection apparatus 320, and X-ray imaging or optical imaging by the imaging apparatus 310. And an appearance inspection program 434 for inspecting the substrate based on the image data acquired by the imaging device 310.

  Here, a method for specifying the position of the electronic component on the substrate will be described with reference to FIG. FIG. 5 is a diagram illustrating a state where electronic component 520 is arranged on substrate 500. The substrate 500 includes a position confirmation mark 510 specified based on the design data. Electronic component 520 has, for example, a rectangular shape. In this case, the electronic component 520 includes four corners (that is, P1 (x1, y1), P2 (x2, y2), P3 (x3, y3), P4 (x4, y4)). The coordinate values of these points are determined based on a reference point predetermined on the substrate 500, starting from the position confirmation mark 510. Each coordinate value is displayed in the memory | storage part 324 as 1st coordinate data to 4th coordinate data, for example, as FIG. 4 shows.

  Next, a specific configuration of the imaging apparatus 310 will be described with reference to FIG. FIG. 6 is a block diagram illustrating a hardware configuration of the imaging device 310. The imaging device 310 includes an X-ray irradiation device 611, an X-ray imaging device 612, a visible light imaging device 613, a visible light source 614, a mirror 615, a scintillator 616, and a data output interface 620. A cable 390 is connected to the data output interface 620. A substrate 618 to be inspected is carried into the imaging device 310. Two electronic components, that is, an electronic component 619 and a BGA / CSP 622 are mounted on the substrate 618 by solder.

  When the X-ray irradiation apparatus 611 emits an X-ray beam, the X-ray beam passes through the electronic component 619 and enters the scintillator 616. The scintillator 616 converts X-rays transmitted through the substrate 618 into visible light. The X-ray imaging device 612 captures visible light output from the scintillator 616, converts the signal into an electrical signal, and outputs it as X-ray transmission image data of the substrate 618. The X-ray transmission image data is sent to the inspection apparatus 320 via the data output interface 620.

  Note that the inspection apparatus 320 according to the present embodiment may be realized as an apparatus configured by a combination of circuit elements that realize each process, or may include hardware and software of a computer system as described later. In some cases, it can be realized through collaboration.

  A specific configuration of the inspection apparatus 320 according to the present embodiment will be described with reference to FIG. FIG. 7 is a block diagram illustrating a hardware configuration of a computer system 700 that functions as the inspection apparatus 320.

  The computer system 700 includes, as main components, a CPU 710 that executes a program, a mouse 720 and a keyboard 730 that receive input of instructions from a user of the computer system 700, data generated by executing a program by the CPU 710, or a mouse 720. Alternatively, a RAM (Random Access Memory) 740 that temporarily stores data input via the keyboard 730, a hard disk 750 that stores data in a nonvolatile manner, and a CD-ROM (Compact Disc-Read Only Memory) driving device 760. And a monitor 780 and a communication I / F (Interface) 790. Each component is connected to each other by a data bus. A CD-ROM 762 can be attached to the CD-ROM drive 760.

  Processing in the computer system 700 is realized by the hardware and software executed by the CPU 710. Such software may be stored in the hard disk 750 in advance. The software may be stored in a CD-ROM 762 or other recording medium and distributed as a program product. Alternatively, the software may be provided as a program product that can be downloaded by an information provider connected to the so-called Internet. Such software is read from the recording medium by the CD-ROM driving device 760 or other data reading device, or downloaded via the communication I / F 790 and then temporarily stored in the hard disk 750. The software is read from the hard disk 750 by the CPU 710 and stored in the RAM 740 in the form of an executable program. CPU 710 executes the program.

  Each element constituting the computer system 700 shown in FIG. 7 is general. Therefore, it can be said that the most essential part of the present invention is software stored in the RAM 740, the hard disk 750, the CD-ROM 762 or other recording medium, or software that can be downloaded via a network. Since the operation of each component of computer system 700 is well known, detailed description will not be repeated.

  The recording medium is not limited to a CD-ROM, FD (Flexible Disc), hard disk, etc., but is a magnetic tape, cassette tape, optical disc (MO (Magnetic Optical Disc) / MD (Mini Disc) / DVD (Digital Versatile Disc)). ), IC (Integrated Circuit) card (including memory card), optical card, mask ROM, EPROM (Electronically Programmable ROM), EEPROM (Electronically Erasable Programmable ROM), flash ROM, etc. A supported medium may be used. The program referred to here includes not only a program that can be directly executed by the CPU 710 but also a program in a source program format, a compressed program, an encrypted program, and the like.

  Next, a control structure of the inspection apparatus 320 according to the present embodiment will be described with reference to FIG. FIG. 8 is a flowchart showing a series of processes executed by CPU 710 of computer system 700 functioning as inspection apparatus 320.

  When the electronic component 619 is mounted on the front surface (surface A) of the substrate 618, the substrate 618 is carried into a reflow furnace. When the solder melts in the reflow furnace, the electronic component 619 and the substrate 618 are joined. Thereafter, the substrate 618 is unloaded from the reflow furnace and loaded into the inspection apparatus 320. When the substrate 618 is fixed at a predetermined position in the inspection device 320, a camera provided in the visible light imaging device 613, for example, a CCD camera, images the substrate 618. Image data generated by imaging is input to a computer system 700 that functions as the inspection apparatus 320. When a user (for example, a person in charge of inspection) of the computer system 700 inputs an instruction to start inspection, the CPU 710 starts image recognition processing using the image data. Alternatively, the process may be started when the CPU 710 detects the elapse of the time after a predetermined time has elapsed since the image data was input to the computer system 700.

  First, the CPU 710 recognizes a position confirmation mark formed in advance on the substrate 618. This recognition is performed using design information stored in advance in the computer system 700 for the substrate 618. For example, the CPU 710 reads design information of the board 618 from the hard disk 750 into the RAM 740 using data (for example, board code, serial number, etc.) identifying the board 618 as a key. The design information includes position information (such as coordinate values) of position confirmation marks formed on the substrate 618. Therefore, the CPU 710 determines whether an image corresponding to the position confirmation mark is included in a location corresponding to the position information in the image data to be processed. For example, the CPU 710 determines whether or not the density of the pixel at the location is higher than the density of the pixels around the location, and identifies the position confirmation mark and other portions. When the CPU 710 determines that the image data is data to be inspected, the following inspection processing is further executed.

  In step S810, CPU 710 causes optical image (hereinafter referred to as “first optical image”) of substrate 618 on which an electronic component (for example, electronic component 619) is mounted only on one surface (or front surface), and X-ray transmission. An input with an image (hereinafter referred to as “first X-ray transmission image”) is received. Data representing the optical image and the X-ray transmission image is transmitted from the imaging device 310 via the cable 392. Note that the timing at which the data representing the optical image and the X-ray transmission image is acquired, that is, the timing at which the X-ray imaging unit 312 operates and the timing at which the visible light supply unit 314 operates may be simultaneous or separate. Good.

  In step S820, the CPU 710 matches the position confirmation marks of the first optical image and the first X-ray transmission image based on the position confirmation marks formed on the substrate 618, thereby the electronic component 619. A reference image is generated. More detailed processing will be described with reference to FIGS.

  In step S830, CPU 710 causes X-ray of substrate 618 to be mounted with an electronic component (for example, BGA / CSP 622) mounted on the other surface of substrate 618 (the surface opposite to the front surface or the back surface). An input of a transmission image (hereinafter, “second X-ray transmission image”) and an optical image obtained by irradiating visible light on the same plane as the first optical image (hereinafter, “second optical image”) Accept.

  Here, the detailed operation in the inspection system 300 is, for example, as follows. A BGA / CSP 622 is mounted on the back surface of the substrate 618 on which the electronic component 619 is mounted on the front surface. When the substrate 618 is carried into a reflow furnace and soldering is performed, a substrate in which components are bonded to both surfaces of the substrate 618 (that is, a double-sided mounting substrate) is generated.

  The substrate 618 is carried into the imaging device 310 with the surface (front surface) on which the electronic component 619 is mounted facing upward. After the substrate 618 is fixed in the imaging device 310, a visible light camera (for example, a CCD camera) that is a visible light imaging device 613 installed on the top of the substrate 618 in the vertical direction is connected to the substrate 618 via the cable 392. Take a picture of the front side again. Image data acquired by photographing is transmitted to the computer system 700, and the CPU 710 recognizes a position confirmation mark formed on the front surface based on the image data.

  Next, based on a command transmitted from the CPU 710 functioning as the imaging device control unit 332, the imaging device driving unit 315 is visible light installed on the top surface of the front surface on which the electronic component 619 is mounted. The supply unit 314 is caused to emit light. Furthermore, the imaging device driving unit 315 causes the imaging unit 313 (for example, a visible light camera) to perform a shooting operation, and the second step is performed on the substrate 618 that is fixed at the same position as when the first optical image is acquired. Obtain an optical image.

  Referring to FIG. 8 again, in step S840, CPU 710 compares the second optical image with the first optical image, and calculates data representing a positional shift. The purpose of comparing the first optical image and the second optical image is to re-solder the soldered electronic component 619 so that the soldered portion is melted again and the position of the electronic component 619 is changed. This is because there is a high possibility that the same optical image will not be obtained when the same surface (front surface) is photographed again due to a shift. Details of the processing to be compared will be described with reference to FIG.

  In step S850, CPU 710 corrects the first optical image using the misregistration amount, and generates a third X-ray transmission image. The extraction method of the electronic component that needs to be corrected is, for example, by extracting the electronic component that needs to be corrected from the position information as shown in FIG. 13, or the first optical image and the second optical image. Is performed by pattern matching.

  In step S860, CPU 710 derives the fourth X-ray transmission image by subtracting the data indicating the third X-ray transmission image from the data indicating the second X-ray transmission image. This process is realized by a known image difference process.

  In step S870, CPU 710 determines whether the electronic component (for example, BGA / CSP 622) is bonded to substrate 618 (specifically, soldering) based on determination data prepared in advance and the fourth X-ray transmission image. Pass / fail status). The determination data is data stored in advance in the hard disk 750 as design information when a component is mounted on the substrate 618, for example.

  The CPU 710 repeats the above processing and writes the result to the hard disk 750. If the CPU 710 detects an abnormality in the middle of processing, the CPU 710 displays that fact on the monitor 780. In addition, the CPU 710 may issue a command for temporarily stopping the imaging operation to the imaging device 310 as the imaging device control unit 332. Or you may instruct | indicate so that arrangement | positioning may be interrupted with respect to the process of arrange | positioning components on a board | substrate.

  When the CPU 710 determines whether or not the soldering portion is acceptable, the board 618 on which the electronic component 619 is mounted is carried out of the inspection device 320 by a conveyor (not shown).

  Here, depending on the result of the inspection, the substrate 618 on which the electronic components 619 are mounted depends on the presence or absence of the bridge of the lead terminal at the lower part of the BGA or CSP or the lower part of the connector that cannot be confirmed by the optical appearance inspection apparatus. It is automatically distributed to an OK / NG stocker (not shown) provided downstream of the apparatus 320, and a series of steps is completed.

  As described above, the inspection system 300 according to the present embodiment associates the first X-ray transmission image and the first optical image of the electronic component mounted on one surface (first surface), and By comparing the second optical image of the first surface and the first optical image after the component is mounted on the other surface (second surface) opposite to the one surface, the first optical image is compared with the first optical image. The feature is that X-ray transmission images are corrected.

  Hereinafter, image processing by the inspection apparatus 320 according to the present embodiment will be described with reference to FIGS. 9 to 16 are diagrams conceptually showing images based on data generated by the computer system 700 functioning as the inspection apparatus 320. FIG.

  Referring to FIG. 9, the first optical image 900 represents an image based on data acquired by photographing the substrate 618 by the visible light imaging device 613. This data is written into the RAM 740 of the computer system 700 after the process of step S810 shown in FIG. The CPU 710 executes image recognition processing to be described later using the data written in the RAM 740.

  The first optical image 900 includes optical images 910 to 913 corresponding to position confirmation marks formed in advance on the substrate 618, and optical images 920 and 920 corresponding to the electronic components 619 mounted on the front surface of the substrate 618. 921 and optical images 930 and 931 corresponding to solder printed between the substrate 618.

  FIG. 10 is an enlarged view showing a part of the first optical image 900 shown in FIG. On the substrate 618, reference lines 1010 and 1011 are preset as design information. The reference lines 1010 and 1011 are set using, for example, a position confirmation mark as a reference. As an example, when the external shape of the electronic component is a rectangle, the positions of the points 1020 and 1021 corresponding to the two corners located on the diagonal line of the electronic component are specified in advance. This specific information is stored in advance in the image processing program.

  When the CPU 710 recognizes the optical images 910 and 911 corresponding to the position confirmation marks and the points 1020 and 1021 corresponding to the two corners located on the diagonal line of the electronic component 619, the position of the electronic component 619 on the substrate 618 is specified. To calculate the information. As the information, the CPU 710, for example, includes the distance B1 between the optical image 910 corresponding to the position confirmation mark and the point 1020 corresponding to the two corners located on the diagonal line of the electronic component, and the optical corresponding to the position confirmation mark. At least one of a distance B2 between the image 911 and a point 1021 corresponding to two corners located on the diagonal line of the electronic component is calculated. These distances are calculated as distances between the centers of the optical images, for example.

  The CPU 710 further includes an angle C1 at which the straight line connecting the optical image 910 corresponding to the position confirmation mark and the point 1020 corresponding to the two corners located on the diagonal line of the electronic component intersects the reference line 1010, and At least one of an angle C2 at which the straight line connecting the optical image 911 corresponding to the position confirmation mark and the point 1021 corresponding to the two corners located on the diagonal of the electronic component intersects with the reference line 1011 is calculated. .

  In the case of optical inspection, the position confirmation mark may be provided only in the vicinity of the electronic component 619 where it is difficult to confirm the soldered portion, or may be provided in the vicinity of all the electronic components. Further, a corner portion of the wiring pattern may be used as a position confirmation mark.

  FIG. 11 is a diagram showing a first X-ray transmission image 1100 captured by the computer system 700. Data for representing the first X-ray transmission image 1100 is stored in the RAM 740 by the CPU 710 when the process shown in step S810 is executed.

  The first X-ray transmission image 1100 includes X-ray transmission images 1110 to 1113 corresponding to the position confirmation mark, X-ray transmission images 1120 and 1121 corresponding to the electronic component 619, and an electronic component corresponding to the electronic component 619. X-ray transmission images 1130 and 1131 corresponding to solder printed between the component and the substrate are included.

  The CPU 710 displays optical images corresponding to two position confirmation marks diagonally within the matrix region of the first optical image 900 shown in FIG. 9 (for example, optical images 910 and 911 corresponding to the position confirmation marks). When the image is recognized and extracted, each position confirmation mark included in these optical images and the X-ray transmission image (first X-ray transmission image 1100 in FIG. 11) acquired corresponding to the first optical image 900. X-ray transmission images 1110 to 1113 corresponding to are matched. Note that the process for matching is well known to those skilled in the art, and therefore the description thereof is not described here.

  For example, the CPU 710 binarizes the first optical image 900 and the first X-ray transmission image 1100, performs pattern matching, and creates a reference image of each component. Next, the CPU 710 adds the component code name to the reference image, and stores the reference image of the electronic component 619 in the storage unit 324. The CPU 710 repeats such data processing for each electronic component 619 to be inspected. The CPU 710 sequentially converts the image data input as an analog signal into a digital signal, and stores it in the storage unit 324 as image data of the front surface of the substrate 618 based on the converted signal.

  Here, the information stored in the storage unit 324 includes, for example, positional information about the first optical image 900 as shown in FIG. 10 in addition to the reference image of each component.

  Further, in the present embodiment, as described above, the first X-ray transmission image 1100 for the first optical image 900 in which the position confirmation mark is recognized is acquired. Acquisition of is not limited to this. For example, as another method, data representing the position of the electronic component 619 that requires X-ray inspection, the electrode position, and the coordinates of the position confirmation mark are stored in advance in the storage unit 324 from the design data of the substrate 618, When the visible light camera that is the visible light imaging device 613 moves, the first X-ray transmission image may be acquired.

  FIG. 12 is obtained by photographing the front surface after the BGA / CSP 622 as another electronic component is mounted on the back surface of the substrate 618 (that is, the surface opposite to the front surface). FIG. 6 is a diagram illustrating two optical images 1200. The second optical image 1200 is stored in the RAM 740 when the process shown in step S830 is executed.

  The second optical image 1200 includes the optical images 1210 to 1213 corresponding to the position confirmation mark, the optical image 1220 corresponding to the electronic component 619, and other electronic components mounted on the same surface (that is, the front surface). , And optical images 1230 and 1231 corresponding to solder printed between the electronic component 619 and the substrate 618.

  FIG. 13 is an enlarged view of a part of the second optical image 1200 shown in FIG. When data represented by second optical image 1200 is stored in RAM 740, CPU 710 calculates information representing the position of electronic component 619 on substrate 618 using the data. The information is the same as that described in FIG.

  More specifically, the CPU 710 recognizes points 1320 and 1321 corresponding to two corners located on the diagonal of the electronic component in the optical image 1220 corresponding to the electronic component. Further, the CPU 710 recognizes optical images 1210 and 1211 corresponding to the position confirmation marks. The CPU 710 calculates a distance B11 between the center of the optical image 1210 corresponding to the position confirmation mark and the point 1320 corresponding to the two corners located on the diagonal line of the electronic component. Similarly, the CPU 710 also calculates a distance B21 between the center of the optical image 1211 corresponding to the position confirmation mark and the point 1321 corresponding to two corners located on the diagonal line of the electronic component. Further, the CPU 710 sets an angle C11 at which the straight line connecting the center of the optical image 1210 corresponding to the position confirmation mark and the point 1320 corresponding to the two corners located on the diagonal of the electronic component intersects the reference line 1310. calculate. Similarly, the CPU 710 also calculates an angle C21 at which the straight line connecting the optical image 1211 corresponding to the position confirmation mark and the point 1321 corresponding to the two corners located on the diagonal line of the electronic component intersects the reference line 1311. calculate. The CPU 710 stores each of these calculated data in an area secured in advance in the RAM 740.

  Here, in step S840, CPU 710 compares distances B11 and B21 and angles C11 and C21 with distances B1 and B2 and angles C1 and C2, respectively. If the CPU 710 determines that there is a difference in the position information as a result of the comparison, the CPU 710 calculates a new coordinate value from these distance and angle data, and derives a positional deviation amount, that is, a coordinate value.

  In the case where the electronic component 619 is an electrode size or more, for example, a 1608 chip component having an electrode size of 0.6 mm × 0.85 mm, the positional deviation with an X coordinate value of 0.3 mm and a Y coordinate value of 0.45 mm or more That is, if a positional deviation of ½ or more of the electrode size is found, the CPU 710 monitors whether or not a defect in the substrate 618 has been detected when acquiring the second optical image 1200 in step S840. 780 is displayed.

  FIG. 14 is a diagram illustrating a second X-ray transmission image 1400 acquired after each electronic component is mounted on both the front surface and the back surface of the substrate 618. The second X-ray transmission image 1400 is input to the computer system 700 via the communication I / F 790 after the processing in step S830 is executed, and is stored in the RAM 740 by the CPU 710.

  The second X-ray transmission image 1400 includes X-ray transmission images 1410 to 1415 corresponding to the position confirmation marks, and X-ray transmission images 1420 and 1421 corresponding to the electronic components 619 mounted on the front surface of the substrate 618. The X-ray transmission image 1430 corresponding to the solder printed between the electronic component 619 and the substrate 618, the X-ray transmission images 1441 to 1449 corresponding to the “solder balls” disposed on the back surface of the substrate 618, and the substrate And an X-ray transmission image 1450 corresponding to the BGA / CSP 622 mounted on the back surface of 618.

  FIG. 15 is a diagram showing a third X-ray transmission image 1500. The third X-ray transmission image 1500 is created by the CPU 710 (step S850).

  The third X-ray transmission image 1500 includes X-ray transmission images 1510 to 1513 corresponding to the position confirmation mark, X-ray transmission images 1520 and 1521 corresponding to the electronic component 619, and between the electronic component 619 and the substrate 618. X-ray transmission images 1530 and 1531 corresponding to the printed solder.

  The CPU 710 calculates a displacement amount using data representing the first optical image 900 stored in the RAM 740 (step S840), and corrects the first optical image 900 using the displacement amount. Thus, data representing the third X-ray transmission image 1500 is calculated.

  Specific processing is as follows. After extracting the electronic component that is determined to need correction (here, the optical image 1220 corresponding to the electronic component is suitable), the CPU 710 sets a threshold value at which the electronic component can be extracted. This threshold value is preset in the hard disk 750, for example. The CPU 710 creates a density distribution histogram based on the data of the captured optical image, performs binarization processing using a value for the valley of the density distribution as a threshold value, and acquires a binarized image. The CPU 710 performs binarization processing within the range of the data “255” in the binarized image until the area including the position confirmation mark and the mounted electronic component is divided from the area that is not, A region including the optical images 1210 and 1211 corresponding to the confirmation mark and the optical image 1220 corresponding to the electronic component 619 and a region not including the optical image 1220 are divided.

  Next, the CPU 710 extracts optical images 1210 and 1211 corresponding to the position confirmation marks included in the divided areas, and an optical image 1220 corresponding to the electronic component 619. In addition, the CPU 710 matches the X-ray transmission images 1110 and 1111 corresponding to the position confirmation marks included in the first X-ray transmission image 1100 with the optical images 1210 and 1211 corresponding to the extracted position confirmation marks.

  Further, the CPU 710 corrects the extracted position information of the electronic component only by the acquired data as shown in FIG. The CPU 710 generates a third X-ray transmission image 1500 by the image pasting process as shown in FIG. This image is not acquired by photographing. Here, the third X-ray transmission image 1500 is created by segmentation by binarization processing, image extraction, and pasting processing. However, the X-ray transmission image can be obtained by other methods. It may be corrected.

  FIG. 16 is a diagram showing a fourth X-ray transmission image 1600. Data representing the fourth X-ray transmission image 1600 is generated by arithmetic processing of CPU 710 (step S860).

  The fourth X-ray transmission image 1600 includes X-ray transmission images 1610 and 1613 corresponding to position confirmation marks provided on the back surface of the substrate 618, an X-ray transmission image 1650 corresponding to the BGA / CSP 622, and a BGA / CSP 622. X-ray transmission images 1641 to 1649 corresponding to solder balls arranged for mounting on the substrate 618 are included.

  The CPU 710 uses the data representing the third X-ray transmission image 1500 stored in the RAM 740 to obtain a third X-ray from the data representing the second X-ray transmission image 1400 of the mounting board on which the electronic components are mounted on both sides. A fourth X-ray transmission image 1600 is derived by subtracting data representing the X-ray transmission image 1500. This process is realized by a known image difference process.

  Next, the CPU 710 determines pass / fail of the joining state (specifically, the soldering state) of the electronic component to the board based on the judgment data prepared in advance and the fourth X-ray transmission image 1600. Then, a series of inspection steps is completed (step S870).

  With reference to FIG. 17, the difference between the inspection method by the inspection apparatus 320 according to the present embodiment and the conventional inspection method will be described. As shown in FIG. 17, according to the substrate inspection method using the inspection apparatus 320 according to the present embodiment, the overdetermining rate is about 9%. On the other hand, according to the conventional inspection method, the overjudgment rate is about 58%. Here, over-determination handling (over-determination mode) is performed by solder used for mounting the electronic component 619 mounted on the front surface of the substrate 618 according to the inspection apparatus 320 according to the present embodiment. This is based on the fact that the difference due to the shape change is incomplete. On the other hand, in the conventional inspection method, the over-determination is handled by over-determination of the apparent solder bridge due to the displacement of the electronic component 619 disposed on the front surface of the substrate 618.

  Here, another inspection method will be described with reference to FIG. FIG. 18 is a diagram illustrating an image used when an inspection apparatus according to another aspect inspects a substrate.

  FIG. 18A is a diagram showing an X-ray transmission image 1810 acquired after components are mounted on both surfaces (front surface and back surface) of the substrate. The X-ray transmission image 1810 includes an X-ray transmission image 1811 corresponding to an electronic component mounted on the front surface of the board and an X-ray transmission image 1812 corresponding to another electronic component mounted on the back surface of the board. Including.

  FIG. 18B is a diagram showing an X-ray transmission image 1820 acquired after components are mounted only on one side (for example, the front side) of the board. The X-ray transmission image 1820 includes an X-ray transmission image 1813 corresponding to the electronic component mounted on the front surface of the board.

  FIG. 18C is a diagram illustrating an X-ray transmission image 1830 generated by subtracting the X-ray transmission image 1820 from the X-ray transmission image 1810. The X-ray transmission image 1830 includes an X-ray transmission image 1814 corresponding to the electronic component mounted on the back surface of the substrate.

  According to the other inspection method, data representing the X-ray transmission image 1810 and the X-ray transmission image 1820 are required as data representing the X-ray transmission image. Moreover, the 1st board | substrate with which each component was mounted in the front surface and the back surface, and the 2nd board | substrate with which components were mounted in any one surface are needed. In this case, the mounting position of the component mounted on the second substrate and the component of the same type as the component mounted on the second substrate among the components mounted on the first substrate are the same. It must be done. Therefore, the processing accuracy or cost required for prototyping these substrates exceeds the processing accuracy or cost required for realizing the inspection by the inspection apparatus 320 according to the embodiment of the present invention.

  On the other hand, according to the inspection apparatus 320 according to the embodiment of the present invention, as described in detail below, it is possible to inspect a board on which components are mounted without increasing cost or time.

  First, the characteristics of the inspection apparatus according to the present embodiment are as follows. Unlike the conventional method, the substrate inspection method according to the present embodiment does not use an image of the back surface obtained by photographing a separate substrate as a reference image. Further, the X-ray transmission images on the front and back surfaces are compared with the X-ray transmission images mounted on one side, and the positional deviation amount is not obtained. The board inspection method acquires an image of a front surface from an image of a board on which components are mounted on both sides to be inspected, and a difference between the image of the front surface and an image of a board to be inspected. By inspecting the mounting state on the back surface. That is, by comparing the optical image, which is easier to compare with the X-ray transmission image, for each electronic component before and after the second reflow furnace, the X-ray transmission image for the positional deviation of each electronic component is corrected, The mounting state on the back surface is inspected by taking the difference between the image of the front surface and the image of the substrate to be inspected.

  Specifically, according to a conventional method (so-called “subtractive method”) in which a reference substrate for obtaining an image of the back surface is prepared, the apparatus determines that the observed sample is defective despite being good. There are some cases (over-judgment mode). As an example, the overjudgment rate may be slightly over 50%.

  On the other hand, according to the inspection apparatus 320 according to the embodiment of the present invention, the error due to the positional deviation of the electronic component of the back image with respect to the image after the difference that is the cause of the occurrence of the overjudgment mode or the individual difference between the substrates. The effect can be reduced to about 10% under certain conditions. As a result, the misrecognition rate of the soldered portion of the electronic component with respect to the double-sided mounting board decreases.

  Moreover, when mounting electronic components on both surfaces, it is necessary to pass through a reflow furnace twice. In the second reflow furnace, the A surface (or “front surface”) of the mounting substrate, which is the surface on which the electronic components are first mounted, is soldered due to heat during the second treatment in the reflow furnace. Melts again. Therefore, in order to prevent the electronic components from falling off inside the reflow furnace during the second processing, generally, a small and lightweight electronic component such as a resistor, a capacitor, or a small IC is used as the A of the substrate. Mounted on the surface first. Large components such as BGA and connectors, which are electronic components mounted on the B surface of the substrate, are mounted in the second reflow furnace. When the electronic component placement device is installed in the order of the steps described above, as the reverse process, the electronic component is first mounted on the back surface (B surface) of the substrate, and then the front surface (A surface) side of the mounting substrate. In order to mount electronic components on the board, useless adjustment time such as readjustment of the setting of the placement apparatus for several prototype boards is required. As a result, the efficiency is reduced and it is not practical, and the substrate manufactured in this way is actually a useless substrate.

  On the other hand, according to the substrate inspection apparatus 320 according to the embodiment of the present invention, a substrate (reference substrate) on which electronic components are mounted on the back surface of the substrate is unnecessary. As a result, the man-hours for making a prototype of a board on which electronic components are mounted only on the back surface (B surface) side, which is required in the subtractive method, are not required.

  Moreover, since the inspection apparatus 320 can extract an image of only a portion that the operator wants to observe, the inspection time can be shortened. Further, the inspection apparatus 320 stores a binarized image in the storage unit 324 for a board on which electronic components are mounted only on one surface side. Therefore, an increase in storage capacity necessary for substrate inspection can be suppressed.

  Furthermore, compared to the conventional method of correcting the position of the entire substrate by superimposing the single-sided image and the double-sided image on the basis of the position of the position confirmation mark detected by the X-ray transmitted through the substrate, Since the present invention corrects the position for each electronic component, the position detection error can be reduced without being affected by the warping of the substrate by the reflow furnace.

  As described above, the quality of the soldered portion can be easily determined, so that the inspection of the double-sided mounting board can be automated. This makes it possible to incorporate an inspection process into the manufacturing process (in-line). As a result, it is difficult to find with an optical appearance inspection apparatus, and it is possible to automatically determine a solder joint at a position that is a shadow of an electronic component that has been relied on visual or electrical inspection. Further, it is possible to reduce the error rate, shorten the visual check work time, reduce the number of visual personnel, or improve the productivity.

  In the present embodiment, the X-ray imaging device is arranged at the lower part in the vertical direction of the substrate, and the X-ray irradiation device is arranged at the upper part in the vertical direction of the substrate. It may be.

  In addition, a case is described in which a mechanism for inverting the substrate is provided in front of the inspection device 320, and the visible light imaging device is disposed only on one surface of the substrate. However, the visible light imaging device may be installed at two or more locations (for example, above and below the substrate).

  In addition, the inspection by the inspection apparatus 320 is not limited to the determination of whether the bonding state is good or not for only the portion that requires the X-ray inspection, and the mounting state of each electronic component may be inspected.

  Further, although the X-ray transmission image and the optical image are individually captured, the X-ray transmission image and the optical image may be simultaneously captured.

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

It is a figure which represents notionally the manufacturing process 100 of the board | substrate with which the electronic component was mounted. 3 is a flowchart showing a series of processes in a joining step 110. It is a block diagram showing the structure of the function implement | achieved by the test | inspection system 300 which concerns on embodiment of this invention. It is a figure which represents notionally 1 aspect of the storage of the data in the memory | storage part 324 with which the test | inspection apparatus 320 is provided. FIG. 6 is a diagram illustrating a state where electronic component 520 is arranged on substrate 500. FIG. 25 is a block diagram illustrating a hardware configuration of imaging apparatus 310. 2 is a block diagram showing a hardware configuration of a computer system 700 that functions as an inspection apparatus 320. FIG. 10 is a flowchart showing a series of processes executed by CPU 710 of computer system 700. FIG. 6 is a diagram (part 1) conceptually showing an image generated by a computer system 700 functioning as an inspection apparatus 320. FIG. 5 is a diagram (part 2) conceptually showing an image generated by a computer system 700 functioning as an inspection apparatus 320. FIG. 11 is a diagram (part 3) conceptually showing an image generated by a computer system 700 functioning as an inspection apparatus 320. FIG. 14 is a diagram (part 4) conceptually showing an image generated by the computer system 700 functioning as the inspection apparatus 320. FIG. 11 is a diagram (part 5) conceptually showing an image generated by a computer system 700 functioning as an inspection apparatus 320. FIG. 16 is a diagram (part 6) conceptually illustrating an image generated by the computer system 700 functioning as the inspection apparatus 320. FIG. 10 is a diagram (No. 7) conceptually showing an image generated by the computer system 700 functioning as the inspection apparatus 320. FIG. 18 is a diagram (No. 8) conceptually illustrating an image generated by the computer system 700 functioning as the inspection apparatus 320. It is a figure showing the difference with the inspection method by the inspection apparatus 320 which concerns on this Embodiment, and the conventional inspection method. It is a figure showing the image used when the test | inspection apparatus according to another situation test | inspects a board | substrate.

Explanation of symbols

  100 manufacturing process, 300 inspection system, 510 position confirmation mark, 611 X-ray irradiation device, 612 X-ray imaging device, 613 visible light imaging device, 614 visible light source, 615 mirror, 616 scintillator, 618 substrate, 619 electronic component, 620 data Output interface, 622 BGA / CSP, 700 computer system, 762 CD-ROM, 900 first optical image, 910, 911, 912, 913, 1210, 1211, 1212, 1213 optical image corresponding to the position confirmation mark, 920, 921, 1220, 1221 Optical images corresponding to electronic components, 930, 931, 1230, 1231 Optical images corresponding to solder, 1010, 1011, 1310, 1311 Reference line, 1020, 1021, 1320, 1321 Electronics Points corresponding to two corners located on the diagonal of the product, 1100 first X-ray transmission image, 1110-1113, 1410-1415, 1510-1513, 1610, 1613 X-ray transmission image corresponding to the position confirmation mark, 1120, 1121, 1420, 1421, 1520, 1521 X-ray transmission images corresponding to electronic components, 1130, 1131, 1530, 1531 X-ray transmission images corresponding to solder, 1200 Second optical image, 1400 Second X-ray Transmission image, 1441 to 1449, 1641 to 1649 X-ray transmission image corresponding to solder ball, 1450, 1650 X-ray transmission image corresponding to BGA / CSP, 1500 Third X-ray transmission image, 1600 Fourth X-ray transmission Images, 1810-1814, 1820, 1830 X-ray transmission images.

Claims (15)

A storage unit for storing data;
A processing unit that performs an operation using the data, the processing unit,
Means for acquiring first transmission image data representing an image based on X-rays transmitted through the substrate, wherein a first component is bonded to the first surface of the substrate;
Means for obtaining first optical image data representing an image based on visible light applied to the first surface;
Association means for associating the first transmission image data and the first optical image data;
Means for acquiring second transmission image data representing an image based on X-rays transmitted through the substrate after a second component is bonded to the second surface opposite to the first surface;
Means for obtaining second optical image data representing an image based on visible light irradiated on the first surface after the second part is bonded to the second surface opposite to the first surface. When,
Comparison means for comparing the first optical image data and the second optical image data;
First generation means for generating third transmission image data from the first transmission image data based on a result of comparison between the first optical image data and the second optical image data;
Second generation means for generating fourth transmission image data representing the second surface based on the second transmission image data and the third transmission image data;
A substrate inspection apparatus including: determination means for determining a bonding state of the substrate based on the fourth transmission image data; The comparison means includes an acquisition means for acquiring information representing a position of the first component on the substrate by comparing the first optical image data and the second optical image data,
The first generation means generates the third transmission image data by correcting the first transmission image data based on the information,
The second generation means generates the fourth transmission image data by subtracting the third transmission image data from the second transmission image data,
The determination means compares teaching data representing an image based on X-rays transmitted through the substrate to which the second component is bonded in accordance with predetermined design information with the fourth transmission image data. The board inspection apparatus according to claim 1, wherein the bonding state of the second component is determined. The acquisition means includes
Means for recognizing a first reference image representing a predetermined position on the substrate based on the first optical image data;
Means for recognizing a first partial image corresponding to a predetermined location in the first component based on the first optical image data;
First calculation means for calculating first data representing a positional relationship between the first reference image and the first partial image;
Means for recognizing a second reference image representing the position based on the second optical image data;
Means for recognizing a second partial image corresponding to the predetermined location based on the second optical image data;
Second calculating means for calculating second data representing a positional relationship between the second reference image and the second partial image;
The substrate inspection apparatus according to claim 2, further comprising means for calculating a difference between the first data and the second data. The first calculation means includes
A distance between the first reference image and the first partial image;
An angle formed by a straight line connecting the first reference image and the first partial image and a reference line defined in advance for the first component;
The second calculation means includes:
A distance between the second reference image and the second partial image;
The substrate inspection apparatus according to claim 3, wherein an angle formed by a straight line connecting the second reference image and the second partial image and the reference line is calculated. The association means includes
First recognition means for recognizing a first reference image representing a predetermined position on the substrate from the first transmission image data;
Second recognition means for recognizing a second reference image representing the position from the first optical image data;
Means for matching the first reference image and the second reference image;
The substrate inspection apparatus according to claim 1, further comprising means for associating data for identifying the first component with the first reference image or the second reference image.   6. The substrate inspection apparatus according to claim 5, wherein the predetermined position represents a position of a mark formed in advance on the substrate. A wiring pattern based on predesigned design data is formed on the substrate,
The board inspection apparatus according to claim 5, wherein the first recognition unit and the second recognition unit each recognize an image representing the wiring pattern. A substrate inspection method executed by a processor included in a computer,
Obtaining first transmission image data representing an image based on X-rays transmitted through the substrate, wherein a first component is bonded to the first surface of the substrate;
Obtaining first optical image data representing an image based on visible light applied to the first surface;
Associating the first transmission image data with the first optical image data;
Obtaining second transmission image data representing an image based on X-rays transmitted through the substrate after a second component is bonded to a second surface opposite to the first surface;
Obtaining second optical image data representing an image based on visible light applied to the first surface after the second part is bonded to the second surface opposite to the first surface; When,
A comparison step of comparing the first optical image data and the second optical image data;
A first generation step of generating third transmission image data from the first transmission image data based on a result of comparison between the first optical image data and the second optical image data;
A second generation step of generating fourth transmission image data representing the second surface based on the second transmission image data and the third transmission image data;
And a determination step of determining a bonding state on the substrate based on the fourth transmission image data. The comparing step includes a step of obtaining information representing a position of the first component on the substrate;
The first generation step generates the third transmission image data by correcting the first transmission image data based on the information,
The second generation step generates the fourth transmission image data by subtracting the third transmission image data from the second transmission image data.
In the determination step, teaching data representing an image based on X-rays transmitted through the substrate to which the second component is bonded according to predetermined design information is compared with the fourth transmission image data. The board inspection method according to claim 8, wherein a state of bonding of the second component is determined. The step of obtaining the information comprises:
Recognizing a first reference image representing a predetermined position on the substrate based on the first optical image data;
Recognizing a first partial image corresponding to a predetermined location in the first component based on the first optical image data;
A first calculation step of calculating first data representing a positional relationship between the first reference image and the first partial image;
Recognizing a second reference image representing the position based on the second optical image data;
Recognizing a second partial image corresponding to the predetermined location based on the second optical image data;
A second calculation step of calculating second data representing a positional relationship between the second reference image and the second partial image;
The substrate inspection method according to claim 9, further comprising: calculating a difference between the first data and the second data. The first calculation step includes:
A distance between the first reference image and the first partial image;
An angle formed by a straight line connecting the first reference image and the first partial image and a reference line defined in advance for the first component;
The second calculation step includes:
A distance between the second reference image and the second partial image;
The substrate inspection method according to claim 10, wherein an angle formed by a straight line connecting the second reference image and the second partial image and the reference line is calculated. The association step includes
Recognizing a first reference image representing a predetermined position on the substrate from the first transmission image data;
Recognizing a second reference image representing the position from the first optical image data;
Matching the first reference image and the second reference image;
The method for inspecting a substrate according to claim 8, comprising the step of associating data for identifying the first component with the first reference image or the second reference image.   The substrate inspection method according to claim 12, wherein the predetermined position represents a position of a mark formed in advance on the substrate. A wiring pattern based on predesigned design data is formed on the substrate,
The substrate inspection method according to claim 12, wherein the step of recognizing the first reference image and the step of recognizing the second reference image each recognize an image representing the wiring pattern. A program for causing a computer to function as a substrate inspection apparatus, the program being
Obtaining a first transmission image data representing an image based on X-rays transmitted through the substrate, wherein a first component is bonded to the first surface of the substrate;
Obtaining first optical image data representing an image based on visible light applied to the first surface;
Associating the first transmission image data with the first optical image data;
Obtaining second transmission image data representing an image based on X-rays transmitted through the substrate after a second component is bonded to a second surface opposite to the first surface;
Obtaining second optical image data representing an image based on visible light applied to the first surface after the second part is bonded to the second surface opposite to the first surface; When,
Comparing the first optical image data and the second optical image data;
Generating third transmission image data from the first transmission image data based on a result of comparison between the first optical image data and the second optical image data;
Generating fourth transmission image data representing the second surface based on the second transmission image data and the third transmission image data;
And a step of determining a bonding state on the substrate based on the fourth transmission image data.

Images