JP2007057505A - Method and device for inspecting printed board, and manufacturing method of printed board - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an inspection method of a printed board, which enables determination of not only the number of found defects but also whether or not the printed board is defective with consideration of even expansion/contraction rate of the board, in defect inspection of the printed board. <P>SOLUTION: The expansion/contraction rate of the printed board to be inspected is measured, the expansion/contraction rate data obtained by measurement is stored in a storage section in association with the printed board to be inspected, and, based on the deviation value of the expansion/contraction rate of the printed board to be inspected in the same lot, the printed board to be inspected is automatically classified into non-defective, object to be verified, or defective. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a printed circuit board inspection method and inspection apparatus, and a printed circuit board manufacturing method.

  In a conventional printed circuit board inspection apparatus, if a defect is not found as a result of the defect inspection of the printed circuit board, the printed circuit board is classified as “good”, and if a defect is found, “defective product” or “verify (visually) Confirmation etc.) ”. In particular, when a defect is found, if a fatal defect, for example, the number of found defects exceeds the specified number, it is discarded as a “defective product” without performing “verify”, but otherwise In that case, the printed circuit board is sent to the verify process, and the operator visually confirms it. After verifying, if it is determined that a defect present on the printed circuit board does not become a problem, the printed circuit board is collected as “good”. Further, if repair is possible even if there is a defect, it is recovered as “good” after undergoing repair processing.

In Patent Document 1, in a pattern inspection method for automatically inspecting a pattern of a circuit or the like formed on a film-like belt-like workpiece, this inspection is performed at the time of inspection of a certain inspection unit in order to shorten the inspection time. It is disclosed that when the number of defective circuit patterns found in a unit exceeds an allowable number, the inspection of the inspection unit is stopped and the inspection is shifted to the next inspection unit.
JP 2004-20488 A

  Incidentally, in the pattern inspection method disclosed in Patent Document 1, when the number of defective circuit patterns exceeds an allowable number, the inspection is stopped and the sheet is discarded as a defective sheet. However, in this pattern inspection method, it is not possible to determine whether the sheet is a defective sheet based on conditions other than the number of defective circuit patterns.

  Therefore, it is an object of the present invention to determine whether a printed circuit board is “defective” in consideration of not only the number of detected defects but also the expansion / contraction rate of the printed circuit board in the defect inspection of the printed circuit board. It is to provide a substrate inspection method.

  The printed circuit board inspection method of the present invention includes a step of measuring an expansion / contraction ratio of a printed circuit board, a process of storing expansion / contraction ratio data obtained as a result of the measurement in a storage unit in association with the printed circuit board, and the printed circuit board And a process of automatically classifying the product into one of a non-defective product, a verification target, and a defective product using the expansion / contraction rate data corresponding to.

  Further, the printed circuit board inspection apparatus of the present invention obtains the expansion / contraction ratio of the printed circuit board based on the position of at least two feature points on the printed circuit board, a camera for photographing the printed circuit board, and the printed circuit board. A first control unit that adjusts the size of the inspection image obtained by photographing the image with the camera and a master image prepared in advance, and the expansion / contraction rate of the printed circuit board obtained by the first control unit is associated with the printed circuit board A storage unit that stores data as expansion / contraction rate data, and a second control unit that automatically classifies the printed circuit board into one of a non-defective product, a verification target, and a defective product using the expansion / contraction data corresponding to the printed circuit board. Yes. Note that the first control unit and the second control unit may be realized by a common control unit.

  According to the present invention, in the defect inspection of the printed circuit board, it is possible to determine whether the printed circuit board is “defective” in consideration of not only the number of found defects but also the expansion / contraction rate of the circuit board.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

  In the inspection of the printed circuit board on which the wiring pattern is formed, an image obtained by photographing the printed circuit board (hereinafter referred to as an inspection circuit board image) is compared with an image of a model board (hereinafter referred to as a model circuit board image). Is done by.

  FIG. 1 is a top view and a front view of an inspection apparatus used for inspection of a printed circuit board.

  In FIG. 1, an inspection apparatus 1 generally includes a stage transport mechanism unit 2, an imaging mechanism unit 3, and a control unit 4 (see FIG. 2). The stage transport mechanism unit 2 includes a stage unit 21, a turning unit 22, a Y-axis direction drive mechanism 23, and a base unit 24. The imaging mechanism unit 3 includes an imaging camera 31, a support member 32, an X-axis direction drive member 33, a camera support member 34, an X-axis direction drive mechanism 35, and a Z-axis direction drive mechanism 36. In FIG. 1, only the display unit 44 included in the control unit 4 is illustrated. The display unit 44 has a display screen for displaying information to the user by display control of the main control unit 41 described later.

  The stage unit 21 forms a horizontal stage surface on the top surface. A printed circuit board, which is a substrate to be inspected, is placed on the stage surface of the stage unit 21. The lower part of the stage unit 21 is supported by the turning unit 22, and the stage unit 21 is configured to be rotatable in the θ direction in the figure by the turning operation of the turning unit 22. The base portion 24 is extended and fixed in the illustrated Y-axis direction parallel to the stage surface so as to pass below the imaging mechanism portion 3. The Y-axis direction drive mechanism 23 slides along a guide provided in the Y-axis direction on the upper surface of the base portion 24, and the turning portion 22 is fixed on the upper surface thereof. The Y-axis direction drive mechanism 23 includes a Y-axis drive motor 231 and a Y-axis NC driver 232 described later (see FIG. 2). As a result, the Y-axis direction drive mechanism 23 can be moved in the Y-axis direction (main scanning direction) along the guide of the base portion 24 by the driving force from the Y-axis drive motor 231 and supported by the turning portion 22. The horizontal movement of the stage unit 21 in the main scanning direction is also possible.

  The support member 32 is installed in the upper space of the stage unit 21 that horizontally moves on the base unit 24. An X-axis direction drive mechanism 35 is provided on the support member 32, and the X-axis direction drive member 33 is parallel to the stage surface and in the illustrated X-axis direction (sub-scanning direction) perpendicular to the Y-axis direction. Move. Note that the X-axis direction drive mechanism 35 includes an X-axis drive motor 351 and an X-axis NC driver 352 described later (see FIG. 2). The X-axis direction drive member 33 is provided with a Z-axis direction drive mechanism 36, and moves the camera support member 34 in the illustrated Z-axis direction perpendicular to the X-axis and Y-axis directions. The Z-axis direction drive mechanism 36 includes a Z-axis drive motor 361 and a Z-axis NC driver 362 described later (see FIG. 2).

  The imaging camera 31 is constituted by a CCD camera, for example. The imaging camera 31 is supported by the camera support member 34 so that the imaging direction is the downward direction of the Z axis in the figure, and converts the incident light into an electrical signal indicating its color and intensity. In the example of the inspection apparatus 1 shown in FIG. 1, two imaging cameras 31a and 31b are provided, and are supported by the camera support member 34 so that their imaging directions are in the downward direction of the Z axis in the figure. For example, an imaging camera 31a for obtaining image data for pattern matching processing in the inspection apparatus 1 and an imaging camera 31b for obtaining image data for visual inspection by a user of the inspection apparatus 1 are configured, and light sources (FIG. The light irradiated to the substrate to be inspected is received from (not shown). In the present invention, a plurality of imaging cameras 31 may be fixed to the camera support member 34, or only one imaging camera 31 may be fixed to the camera support member 34.

  With such a configuration, the imaging camera 31 is movable in the illustrated X-axis direction (sub-scanning direction) and Z-axis direction (imaging direction). Then, main scanning is performed by moving the stage unit 21 in the main scanning direction (Y-axis direction) while the position of the imaging camera 31 in the X-axis direction is fixed. Next, every time main scanning from one end to the other end of the inspection area of the printed circuit board is completed, the imaging camera 31 moves by a predetermined distance along the sub-scanning direction (X-axis direction). As a result, image data for the entire inspection area of the printed circuit board is obtained from the imaging camera 31. Furthermore, the imaging camera 31 can be moved in the Z-axis direction (imaging direction) by the Z-axis direction drive mechanism 36. The Z-axis direction drive mechanism 36 appropriately moves the camera support member 34 in the Z-axis direction so that the imaging camera 31 is focused on the upper surface of the substrate to be inspected placed on the stage surface.

  Next, a schematic configuration of the control function in the inspection apparatus 1 will be described with reference to FIG. FIG. 2 is a block diagram showing a control function of the inspection apparatus 1.

  In FIG. 2, the control unit 4 of the inspection apparatus 1 includes a main control unit 41, a focus control unit 42, a storage unit 43, a display unit 44, an operation unit 45, and a memory 50. The main control unit 41 and the focus control unit 42 are constituted by, for example, a CPU board and are connected to each other. A storage unit 43 is connected to the main control unit 41 and the focus control unit 42. The storage unit 43 is used as a storage area when the main control unit 41 and the focus control unit 42 perform processing, and stores a data group necessary for processing. The storage unit 43 stores CAD data 432, master image data 433, and a substrate distortion information database 434. The CAD data 432 is stored in advance according to the board to be inspected as an inspection target in the inspection apparatus 1. The master image data 433 is stored by a master image data creation operation described later. The substrate distortion information database 434 is a database for managing the expansion rate data indicating the expansion rate of each printed circuit board to be inspected in association with the printed circuit board. The display unit 44 presents information to the user according to the display control of the main control unit 41. The operation unit 45 outputs an operation signal corresponding to a user operation to the main control unit 41, and includes a general input device such as a keyboard or a mouse.

  The main control unit 41 mainly performs creation of master image data 433, pattern inspection using the master image data 433, operation control of the X-axis NC driver 352, operation control of the focus control unit 42, and the like. Further, the main control unit 41 receives image data Im captured by the imaging camera 31. The X-axis NC driver 352 drives the X-axis drive motor 351 according to the control of the main control unit 41. Then, the X-axis drive motor 351 moves the X-axis direction drive member 33 in the X-axis direction (sub-scanning direction; see FIG. 1), and moves the imaging camera 31 in the X-axis direction. With these configurations, the main control unit 41 can control the operation of the imaging camera 31 in the sub-scanning direction.

  The focus control unit 42 mainly controls the operations of the Y-axis NC driver 232 and the Z-axis NC driver 362. The Y-axis NC driver 232 drives the Y-axis drive motor 231 according to the control of the focus control unit 42. The Y-axis drive motor 231 moves the stage unit 21 horizontally in the Y-axis direction (main scanning direction; see FIG. 1). With these configurations, the focus control unit 42 can control the operation of the stage unit 21 in the main scanning direction. The Z-axis NC driver 362 drives the Z-axis drive motor 361 according to the control of the focus control unit 42. Then, the Z-axis drive motor 361 moves the camera support member 34 in the Z-axis direction (imaging direction; see FIG. 1) to move the imaging camera 31 in the Z-axis direction. With these configurations, the focus control unit 42 can control the operation of the imaging camera 31 in the imaging direction (focal direction) so that the upper surface of the substrate to be inspected is in focus. Then, the main control unit 41 performs, for example, pattern matching processing on an image (inspection image) obtained by imaging the substrate to be inspected on which a pattern is formed by the imaging camera 31 and an image (master image) serving as a determination reference. In comparison, when there is a difference between these two images by a predetermined amount or more, the position is detected as a defective portion (see FIG. 5).

  Next, the flow of inspection of a printed circuit board using the inspection apparatus 1 will be described with reference to the flowchart of FIG.

  Inspection of the printed circuit board using the inspection apparatus 1 includes alignment processing (S10), registration processing of expansion rate data to the database (S11), inspection scanning processing (S12), defect detection processing (S13), and non-defective / defective product determination. The process proceeds in the order of processing (S14).

  The alignment process (S10) is a process for adjusting the position and size of these two images so that the inspection image and the master image can be appropriately compared in the subsequent defect detection process. In the alignment process, two or more feature points (hereinafter referred to as alignment points) on the printed board are imaged, and these positions are compared with the positions of corresponding alignment points on the master board. As the feature point, for example, a cross mark previously attached to a predetermined position of the printed circuit board or the master image can be used. The alignment process is realized by, for example, a real-time phase correction function or a three-point alignment function.

  The real-time phase correction function is based on the two alignment points M1 and M2 on the inspection target substrate shown in FIG. 4A and the two alignment points O1 and O2 on the master image shown in FIG. 4B. The X-axis direction expansion / contraction rate (ΔXo / ΔXm) is calculated, and the scanning position of the imaging camera in the inspection scan process is set based on the calculated X-axis direction expansion / contraction rate. With this function, the X-axis direction scale of the inspection image obtained by the inspection scanning process and the master image is the same.

  The three-point alignment function is based on the three alignment points M1 to M3 on the inspection target substrate shown in FIG. 4 (a) and the three alignment points O1 to O3 on the master image shown in FIG. 4 (b). X-axis direction expansion ratio (ΔXo / ΔXm) and Y-axis direction expansion ratio (ΔYo / ΔYm) are calculated respectively, and the X-axis of the master image is calculated according to the calculated X-axis direction and Y-axis direction expansion ratios. This is a function for changing the direction and the scale in the Y-axis direction. With this function, the scales in the X-axis direction and the Y-axis direction of the inspection image obtained by the inspection scanning process and the master image are the same.

  By the alignment process as described above, even if the printed circuit board is expanded or contracted from the standard state, the inspection image and the master image can be appropriately compared in the subsequent defect detection process.

  The X-axis direction expansion ratio or Y-axis direction expansion ratio calculated in the alignment process is associated with the printed circuit board that has been aligned by the main control unit 41 (that is, information that can uniquely identify the corresponding printed circuit board). It is registered in the substrate distortion information database 403 (along with the printed board identification number, production lot number, etc.) (S11).

  The inspection scan process (S12) is a process for imaging the inspection target substrate using the imaging camera 31. An inspection image of the operation target substrate is generated by the inspection scan process.

  As shown in FIG. 5, the defect detection process (S13) is a process for detecting a defect portion included in the printed circuit board to be inspected by comparing the inspection image generated by the inspection scan process with the master image.

  The non-defective product / defective product determination process (S14) is a process for automatically classifying each printed circuit board into one of “non-defective product”, “verification target”, and “defective product” according to the inspection result. The processing flow of the main control unit 41 in the non-defective / defective product determination processing will be described below with reference to the flowchart shown in FIG.

  First, in step S20, the main control unit 41 determines whether or not the number of defective portions found in the defect inspection process for the printed circuit board to be determined is equal to or less than the allowable number. In S27, the determination target printed circuit board is classified as a defective product.

  If the number of defective parts is less than the allowable number in step S20, the main control unit 41 expands / contracts corresponding to each printed circuit board in the same lot as the determination target printed circuit board from the circuit board distortion information database 434 in subsequent step S21. The rate data is acquired, and further, in step S22, the deviation value of the expansion / contraction rate of the determination target printed circuit board (deviation value in the printed circuit board in the same lot) is calculated.

  In step S23, the main control unit 41 determines whether or not the deviation value calculated in step S22 is within a predetermined range. If the deviation value is not within the predetermined range (that is, the print rate of the determination target printed circuit board is another print in the same lot). If the printed circuit board is far from the substrate), the determination target printed circuit board is classified as a defective product. In the alignment process in step S10, the expansion / contraction ratios in the X-axis direction and the Y-axis direction of the printed circuit board are calculated, and when the expansion / contraction ratios in the respective axis directions are registered in the substrate distortion information database in step S11, step In S23, when one (or both) of the deviation value of the expansion / contraction rate in the X-axis direction and the deviation value of the expansion / contraction rate in the Y-axis direction of the determination target printed circuit board is out of a predetermined range, the determination target printed circuit board is selected. You may make it classify into inferior goods.

  When the deviation value of the determination target printed circuit board is within the predetermined range in step S23, in the subsequent step S24, the main control unit 41 determines whether or not a defect portion is found on the determination target printed circuit board in the defect inspection process. to decide. When a defective part is found, the determination target printed circuit board is classified as a verification target. When a defective part is not found, the determination target printed circuit board is classified as a good product.

  As a result of such processing, printed circuit boards that have more than the allowable number of defective parts and printed circuit boards that have a deviation rate of expansion / contraction rate within the same lot are automatically classified as defective products. In the verification process, it is possible to save the operator from having to perform visual confirmation and the like. In the above, when the number of defects exceeds the allowable number, it is classified as a defective product as a fatal defect, but other than this, for example, a defect larger than the allowable size or a serious defect such as a short circuit or disconnection is fatal. You may make it judge as a general defect.

  The expansion / contraction rate data of the printed circuit board is stored only in the storage unit for the expansion / contraction rate data calculated in the alignment process and used for the non-defective / defective product determination process. It is not necessary to measure the expansion / contraction ratio of the substrate from the beginning, and the inspection efficiency is not lowered. However, if the alignment process is not performed in the inspection apparatus, it goes without saying that a process of measuring the expansion / contraction rate of the printed circuit board is necessary only for the non-defective / defective product determination process.

  In the present embodiment, the example in which it is determined whether or not the printed circuit board is classified as defective based on the deviation value of the expansion / contraction ratio of the printed circuit board has been described, but the present invention is not limited to this. For example, when the expansion / contraction rate itself of the printed board is out of a predetermined range (for example, a deviation from an ideal value is in a range of −3% to + 3%), the printed board may be classified as defective.

  Moreover, in this embodiment, although the example which judges whether this printed circuit board is classify | categorized into defect based on the expansion / contraction ratio of the printed circuit board was demonstrated, this invention is not limited to this, For example, the expansion / contraction ratio of a printed circuit board Whether or not to classify the printed circuit board as a verification target may be determined based on the above.

  In this embodiment, the expansion / contraction ratio of the printed circuit board is measured based on two or three alignment points in the alignment process. However, the present invention is not limited to this, and the printed circuit board is based on four or more alignment points. You may make it measure the expansion-contraction rate of. As the number of alignment points to be referred to increases, the local expansion / contraction rate of the printed circuit board can be measured. Accordingly, when it is recognized that the printed board is locally abnormally expanded and contracted, the printed board can be classified as a defective product.

  Note that the expansion / contraction rate data stored in the substrate strain information database 434 as in the present embodiment can be effectively used for purposes other than the non-defective / defective product determination processing in step S14. Hereinafter, an example in which the expansion / contraction rate data stored in the substrate strain information database 434 is used for manufacturing a multilayer printed board will be described.

  FIG. 7 is a flowchart showing the processing procedure of the method for manufacturing a multilayer printed board using the expansion / contraction rate data stored in the board strain information database 434.

  First, the multilayer printed circuit board on which only the basic layer is formed is supplied to the inspection apparatus 1 as an inspection target board, and the processing of steps S30 to S34 shown in FIG. Is done. The processes in steps S30 to S34 are the same as the processes in steps S10 to S14 in FIG. 3 except that the inspection target is “a multilayer printed board on which only the basic layer is formed”. Then, detailed explanation of these processes is omitted.

  The inspection target board classified as “non-defective” in step S34 (or the inspection target board classified as “non-defective” by the operator's visual confirmation after being classified as “verification target” in step S34) Then, in order to form a further layer on the basic layer, it is carried to a stacking apparatus (not shown). This laminating apparatus includes an exposure apparatus for performing an exposure process.

  In step S <b> 35, the main control unit 41 obtains the expansion / contraction rate data of the inspection target board (that is, the multilayer printed board on which only the basic layer is formed) from the board distortion information database 434.

  In step S36, the main control unit 41 (or another control unit provided to control the exposure apparatus) has different sizes prepared in advance according to the value of the expansion / contraction rate data acquired in step S35. A mask to be used in the exposure process is selected from among the different masks (more precisely, three types of mask data stored in an arbitrary storage unit). For example, when the expansion / contraction ratio indicated by the expansion / contraction ratio data acquired in step S35 is in the range of + 1% to + 3%, the mask A having a shape slightly enlarged from the normal size mask B is selected. When the expansion / contraction rate indicated by the expansion / contraction rate data acquired in step S35 is in the range of -1% to + 1%, the normal size mask B is selected. When the expansion / contraction ratio indicated by the expansion / contraction ratio data acquired in step S35 is in the range of −3% to −1%, the mask C having a shape obtained by slightly reducing the normal size mask B is selected.

  In step S37, an exposure process using the mask selected in step S36 is performed on the inspection target substrate in the exposure apparatus. Since the mask used here is a mask selected according to the expansion / contraction ratio of the base layer of the inspection target board, even if the base layer of the inspection target board is distorted, the circuit patterns of the basic layer and the upper layer are different. Upper layer circuit patterns are formed so as to have an appropriate positional relationship.

  By repeating the processes of steps S36 and S37, a multilayer printed board having a large number of layers is formed.

  In the above example, the mask of the higher hierarchy is selected according to the expansion / contraction rate of the basic hierarchy, but the present invention is not limited to this. For example, when performing exposure processing for a certain layer, a mask may be selected according to the expansion / contraction rate of the layer immediately below this layer.

  The present invention is useful for automatically classifying a printed circuit board that can expand and contract depending on the environment into a non-defective product, a verification target, or a defective product.

The top view and front view which show typically the whole structure of the inspection apparatus which concerns on one Embodiment of this invention Block diagram showing control functions of inspection equipment Flow chart showing the operation of the inspection device The figure which shows the feature point on the printed circuit board and the feature point on the master image respectively The figure which shows an example of the defect detected by comparing a master image and a test | inspection image Flow chart showing the flow of non-defective / defective product determination processing The flowchart which shows the processing procedure of the manufacturing method of the lamination type printed circuit board using expansion-contraction rate data

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Inspection apparatus 2 Stage conveyance mechanism part 21 Stage part 22 Turning part 23 Y-axis direction drive mechanism 231 Y-axis drive motor 232 Y-axis NC driver 24 Base part 3 Imaging mechanism part 31 Imaging camera 32 Support member 33 X-axis direction drive member 34 Camera support member 35 X-axis direction drive mechanism 351 X-axis drive motor 352 X-axis NC driver 36 Z-axis direction drive mechanism 361 Z-axis drive motor 362 Z-axis NC driver 4 Control unit 41 Main control unit 42 Focus control unit 43 Storage unit 432 CAD data 433 Master image data 434 Substrate distortion information database 44 Display unit 45 Operation unit 50 Memory

Claims (5)

Measuring the expansion and contraction ratio of the printed circuit board;
The step of storing the expansion ratio data obtained as a result of the measurement in the storage unit in association with the printed circuit board, and the printed circuit board using the expansion ratio data corresponding to the printed circuit board, either a non-defective product, a verification target, or a defective product A method for inspecting a printed circuit board, comprising the step of automatically classifying the printed circuit board into The printed circuit board inspection method includes:
The step of photographing the printed circuit board with a camera, and the size adjustment between the inspection image obtained by photographing the printed circuit board and the master image prepared in advance based on the positions of at least two feature points on the printed circuit board And further comprising a step of comparing the two images to detect a defective portion of the printed circuit board,
2. The storage step includes storing the expansion / contraction ratio data of the printed circuit board calculated based on the feature points for the size adjustment in the storage unit in association with the printed circuit board. Inspection method of printed circuit board of description.   3. The print according to claim 2, wherein in the sorting step, the printed circuit board is automatically sorted by using both the number of defect locations detected in the defect location detection step and the expansion / contraction rate data. Inspection method for substrates. A method of manufacturing a multilayer printed board using the printed circuit board inspection method according to claim 1,
The printed circuit board is a laminated printed circuit board,
The at least one layer higher than the basic layer of the printed circuit board is subjected to exposure processing using a mask having a size corresponding to the expansion / contraction rate data of the basic layer of the printed circuit board stored in the storage unit. A method for manufacturing a multilayer printed circuit board. Camera for shooting printed circuit boards,
The size of the inspection image obtained by photographing the printed circuit board with the camera and the size of the master image prepared in advance based on the position of at least two feature points on the printed circuit board A first control unit for combining,
A storage unit that stores the expansion / contraction ratio of the printed circuit board obtained by the first control unit in association with the printed circuit board as expansion / contraction data, and the non-defective product / verification using the expansion / contraction data corresponding to the printed circuit board A printed circuit board inspection apparatus comprising: a second control unit that automatically classifies the target / defective product.

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