Patent Publication Number: US-2023134676-A1

Title: Component mounting machine

Description:
TECHNICAL FIELD 
     The present disclosure relates to a component mounting machine that measures a mounting position of an electronic component mounted on a circuit base material to determine whether the mounting position is good or bad. 
     BACKGROUND ART 
     Patent Literature 1 discloses an electronic component mounting machine including an inspection device for inspecting whether a component type or an attaching position of an electronic component mounted on a printed circuit board is good or bad. 
     In the electronic component mounting machine, an abnormality in the type of the mounted electronic component and the position of the mounted component is detected by comparing an image of the printed circuit board imaged before the mounting of the electronic component with an image of the printed circuit board imaged after the mounting of the electronic component. Then, when the abnormality is detected in the mounting, as a content of the mounting abnormality, in a case where the electronic component has not fallen to another location on the printed circuit board, a new electronic component is supplied to perform the mounting on the printed circuit board surface, or the location of the mounting abnormality is notified to the operator. Meanwhile, when the electronic component is found elsewhere on the printed circuit board as the content of the mounting abnormality, the location of the dropped electronic component is notified to the operator. 
     PATENT LITERATURE 
     Patent Literature 1: JP-A-2006-319332 
     BRIEF SUMMARY 
     Technical Problem 
     However, in the electronic component mounting machine described in Patent Literature 1, although the abnormality in the component type or the attaching position of the electronic component mounted on the printed circuit board can be detected, since the detection result is not reflected in the mounting of the next electronic component, the same abnormality may occur again. 
     Accordingly, an object of the present disclosure is to provide a component mounting machine capable of reflecting a result of measuring a mounting position of an electronic component mounted on a circuit base material in mounting of a next electronic component. 
     Solution to Problem 
     According to an aspect of the present disclosure, there is provided a component mounting machine including: a base material conveyance/holding device configured to convey a circuit base material and hold the circuit base material at a predetermined position; a component mounting device configured to mount an electronic component supplied by a component supply device on the circuit base material held at the predetermined position; an imaging device configured to capture, in a field of view of the imaging device, an entirety of a predetermined region including the circuit base material held at the predetermined position; an imaging command section configured to command the imaging device to image the predetermined region; a first detection section configured to detect at least one device mark provided on the base material conveyance/holding device and at least one base material mark provided on the circuit base material, based on imaging data imaged according to the command of the imaging command section; a calculation section configured to calculate a position on the circuit base material where the electronic component is to be mounted, based on the device mark and the base material mark detected by the first detection section; a mounting command section configured to command the component mounting device to mount the electronic component at the position on the circuit base material calculated by the calculation section; a second detection section configured to detect a deviation amount between a position on the circuit base material where the component mounting device actually mounts the electronic component according to the command of the mounting command section and the position on the circuit base material calculated by the calculation section; and a feedback section configured to feed back, as a correction value for correcting a position on the circuit base material to be calculated next by the calculation section, a part of the deviation amount detected by the second detection section. 
     Advantageous Effects 
     According to the present disclosure, it is possible to reflect a result of measuring a mounting position of an electronic component mounted on a circuit base material in mounting of the next electronic component. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG.  1    is a perspective view illustrating a schematic configuration of a component mounting machine according to an embodiment of the present disclosure. 
         FIG.  2    is a block diagram illustrating a control device included in the component mounting machine in  FIG.  1   . 
         FIG.  3    is a diagram illustrating an example of transition of a deviation amount of an electronic component when mounting of the electronic component on a circuit base material is repeated. 
         FIG.  4    is a flowchart illustrating a procedure of a mounting inspection process executed by a controller included in the control device in  FIG.  2   . 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     Hereinafter, embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. 
       FIG.  1    illustrates a schematic configuration of component mounting machine  10  according to an embodiment of the present disclosure. It should be noted that when referring to a direction in  FIG.  1   , a direction of an arrow illustrated in the drawing is used. 
     Component mounting machine  10  includes base material conveyance/holding device  22  which conveys and fixes a circuit base material (not illustrated) to a predetermined position, ceiling camera  26  which can capture, in the field of view thereof, the entirety of the circuit base material fixed at the predetermined position by base material conveyance/holding device  22 , component mounting device  24  and mark camera  27  having work head  60  provided on a moving platform (not illustrated) supported so as to be movable in an X-direction and a Y-direction with respect to base material conveyance/holding device  22 , part camera  28  which is fixed to base material conveyance/holding device  22 , and control device  34  which controls imaging by ceiling camera  26 , mounting by component mounting device  24 , and the like. 
     Base material conveyance/holding device  22  includes conveyance device  50  (refer to  FIG.  2   ) which conveys a circuit base material to a predetermined position, that is, a predetermined mounting position where the electronic component is disposed, and clamping device  52  (refer to  FIG.  2   ) which fixes the conveyed circuit base material at the mounting position. For example, conveyance device  50  is configured as a device for conveying the circuit base material by a belt conveyor, and includes a guide member (not illustrated) provided on each of pair of conveyor rails  23 , a conveyor belt (not illustrated) provided on each of pair of conveyor rails  23 , and a belt revolving device (not illustrated) for revolving and driving the conveyor belt. For example, clamping device  52  includes a support section (not illustrated) which supports the circuit base material from below, and a clamp section (not illustrated) which clamps an edge portion of the circuit base material. Examples of the circuit base material include a circuit board, a base material having a three-dimensional structure, or the like, and examples of the circuit board include a printed wiring board, a printed circuit board, or the like. 
     Two cameras serving as ceiling cameras  26  are disposed in parallel at a center of a ceiling portion of component mounting machine  10 , and a predetermined rectangular region including the circuit base material fixed at a predetermined position is imaged by ceiling camera  26  from above. The imaged rectangular region is divided into two sections by the center lines of a pair of facing sides, and each of the divided sections corresponds to the field of view of one camera. As a result, the entire rectangular region including the circuit base material can be imaged by two cameras at once. The imaging timing of ceiling camera  26  is controlled by control device  34 . 
     An X-direction beam (not illustrated) is provided above base material conveyance/holding device  22 , and a Y-direction moving platform (not illustrated) is provided in the X-direction beam so as to be movable in the X-direction. Component mounting device  24  including work head  60  and mark camera  27  are held on the Y-direction moving platform so as to be movable in the Y-direction. An optical axis of mark camera  27  is parallel to a Z direction perpendicular to the X-direction and the Y-direction. The X-direction beam and the Y-direction moving platform are each controlled by a servo motor (not illustrated) via a ball screw, and the operation of the servo motor is controlled by control device  34 . Mark camera  27  is a camera provided on the circuit base material to image a base material mark described later. 
     Component mounting device  24  includes work head moving device  64  which is attached to a Y-direction moving platform, work head  60  which is guided and supported by work head moving device  64  so as to be movable up and down in the Z direction perpendicular to the X-direction and the Y-direction while being controlled to move up and down by a servo motor, and suction nozzle  66  which protrudes downward from work head  60 . Suction nozzle  66  is formed in a cylindrical shape, and suction nozzle  66  is configured to pick up and hold the electronic component at a lower end thereof. A mounting timing by component mounting device  24  is controlled by control device  34 . 
     Component supply device  30  (refer to  FIG.  2   ) is provided on one end side of component mounting machine  10 . Part camera  28  having an optical axis parallel to the Z direction is provided on base material conveyance/holding device  22  between base material conveyance/holding device  22  and component supply device  30 . Part camera  28  is a camera for imaging the electronic component. 
     Component supply device  30  includes tray-type component supply device  78  (refer to  FIG.  2   ) and feeder-type component supply device  80  (refer to  FIG.  2   ). Tray-type component supply device  78  is a device which supplies the component in a state of being placed on the tray. Feeder-type component supply device  80  is a device which supplies the component by a tape feeder and a stick feeder (not illustrated). 
     As illustrated in  FIG.  2   , control device  34  includes controller  82 , multiple drive circuits  86 , and image processing device  88 . Multiple drive circuits  86  are connected to conveyance device  50 , clamping device  52 , work head  60 , work head moving device  64 , tray-type component supply device  78 , and feeder-type component supply device  80 . Controller  82  includes a Central Processing Unit (CPU), a Read Only Memory (ROM), a Random Access Memory (RAM), and the like, is mainly constituted by a computer, and is connected to multiple drive circuits  86 . As a result, the operations of base material conveyance/holding device  22 , component mounting device  24 , component supply device  30 , and the like are controlled by controller  82 . Controller  82  is also connected to image processing device  88 . Image processing device  88  is configured to process imaging data obtained by ceiling camera  26 , mark camera  27 , and part camera  28 , and controller  82  acquires various types of information from the imaging data. 
     An inspection process of the electronic component mounted on the circuit base material using component mounting machine  10  configured as described above will be described below with reference to the flowchart in  FIG.  4   . Hereinafter, in descriptions of the procedures of each process, a step is denoted by “S”. 
     First, controller  82  controls conveyance device  50  to convey the circuit base material to a positioned conveyance position, so that the circuit base material is supported by the support section. Controller  82  controls clamping device  52  to clamp and fix the supported circuit base material by the clamp section (S 10 ). 
     Next, controller  82  commands component mounting device  24  to mount the electronic component on the fixed circuit base material (S 12 ). In the mounting, a position of the base material mark (not illustrated) provided on the circuit base material is detected by mark camera  27 , a positional correction is performed based on the position of the base material mark, and a coordinate position to be mounted is calculated. 
     In the present embodiment, multiple base material marks are provided on the circuit base material, and two or more base material marks to be used as a reference for each electronic component and a mounting position having the base material mark as a reference are determined in advance. For example, the mounting position is determined to be a position separated from one base material mark in the direction of another base material mark by  1 /predetermined number of distances between the two base material marks. Accordingly, two base material marks corresponding to the electronic component which is a mounting target are detected from the imaging data, the distance between the two base material marks is calculated, and the position separated from one base material mark in the direction of another base material mark by  1 /predetermined number of the calculated distance is set as the mounting position. It should be noted that when an effective feedback deviation amount is stored in a feedback deviation amount storage region (described later) in S 26 , the mounting position is determined by correcting the deviation amount. 
     Then, with respect to the electronic component picked up to a tip end of suction nozzle  66 , misalignment of the electronic component with respect to the center line of suction nozzle  66  is detected by part camera  28 , amounts of movement of suction nozzle  66  in the X-direction and the Y-direction are corrected, and the electronic component is mounted at the coordinate positions on the circuit base material. 
     Next, controller  82  commands ceiling camera  26  to perform the imaging. In response to this, ceiling camera  26  images a predetermined rectangular region including the circuit base material after the mounting (S 14 ). Since ceiling camera  26  includes two cameras as described above, the imaging is simultaneously performed by the two cameras. The reason why the imaging is performed by the two cameras in this manner is that, in the present embodiment, since ceiling camera  26  is installed above the circuit base material at a distance of, for example,  500  mm or more, it is difficult to improve resolution with respect to a subject by one camera. However, as long as the necessary resolution can be obtained, one camera may be used, or as long as the necessary resolution is not obtained by two cameras, three or more cameras may be used. 
     The “predetermined rectangular region including the circuit base material” which is an imaging region is a rectangular region including the clamped circuit base material and the pair of conveyor rails  23  therearound. As illustrated in  FIG.  1   , two calibration marks  23   a  are provided on each conveyor rail  23 . Two calibration marks  23   a  on each conveyor rail  23  are provided at a predetermined distance, for example,  300  mm apart from each other on a thin plate of a material of which thermal expansion is difficult to occur, for example, quartz glass. In the present embodiment, since conveyor rail  23  is made of steel, a thin plate of quartz glass is fixed on conveyor rail  23 . As described above, since calibration mark  23   a  is hardly affected by thermal expansion caused by heat generated when component mounting machine  10  mounts the electronic component, the distance between calibration marks  23   a  is substantially unchanged at  300  mm in the present embodiment. Accordingly, by detecting calibration marks  23   a  on each conveyor rail  23  from the imaging data of the rectangular region and calculating the distance between calibration marks  23   a , the calculated distance actually corresponds to  300  mm. Controller  82  performs calibration on the imaging data based on the invariant distance, and calculates the mounting position on the circuit base material on which the electronic component is to be mounted based on the imaging data after the calibration. 
     It should be noted that the mounting position is calculated based on the base material mark included in the imaging data after the calibration, as described above. 
     As described above, the images of both calibration mark  23   a  and the base material mark are included in the imaging data. That is, the calibration and the calculation of the mounting position are performed using the same imaging data. This is because, since both calibration mark  23   a  and base material mark are shaken by vibration generated when component mounting machine  10  mounts the electronic component, by performing the calibration based on calibration mark  23   a  and calculating the mounting position based on the base material mark detected from the imaging data after the calibration, it is possible to cancel a shake component mixed in the imaging data. 
     Next, controller  82  detects calibration mark  23   a  and the base material mark from the imaging data (S 16 ). 
     Next, controller  82  performs the calibration on the imaging data based on calibration mark  23   a  detected in S 16  (S 18 ). Specifically, controller  82  first calculates the distance between two calibration marks  23   a  on each conveyor rail  23 . Since the calculated distances are the same for each conveyor rail  23 , when both distances are different from each other, it means that ceiling camera  26  does not correctly image a predetermined rectangular region including the circuit base material. Accordingly, controller  82  corrects the imaging data so that both distances coincide with each other. In the present embodiment, the calibration of S 16  is performed each time the mounting inspection process is executed, but the present disclosure is not limited to this, and may be performed at a predetermined timing. In addition, in addition to the calibration in S 16 , it is necessary to perform camera calibration of ceiling camera  26 , that is, matrix correction (lens distortion correction). 
     Next, controller  82  calculates the mounting position as described above based on the base material mark detected in S 16  (S 20 ). 
     Controller  82  calculates a deviation amount of the mounted electronic component based on the imaging data acquired in S 14  (S 22 ). For example, the deviation amount is calculated by calculating the distance between the coordinate of the center point on the circuit base material to which the electronic component is mounted and the coordinate of the center point of the electronic component in the imaging data. 
     Next, controller  82  determines whether the calculated deviation amount is within a predetermined allowable amount (S 24 ). In this determination, when it is determined that the calculated deviation amount is not within the predetermined allowable amount (S 24 : NO), controller  82  stores a part of the calculated deviation amount, for example, ½ of the calculated deviation amount in a region (hereinafter, referred to as a “feedback deviation amount storage region”) secured in the RAM provided in controller  82  (S 26 ). As described above, the reason why a part of the calculated deviation amount is set as the feedback deviation amount instead of the entire calculated deviation amount is because since a reading error by ceiling camera  26  is inevitably included in the imaging data used when calculating the deviation amount, when the entire calculated deviation amount is set as the feedback deviation amount, the reading error amount is also fed back, and thus, mounting accuracy may be reduced by the reading error amount. 
     Next, after incrementing the counter by “1” (S 28 ), controller  82  advances the processing to S 32 . Here, the counter is a software counter secured in the RAM, and is used to determine whether the deviation amount of the mounted electronic component converges within a predetermined allowable amount. 
     Meanwhile, when the calculated deviation amount is within the predetermined allowable amount in the determination of S 24  (S 24 : YES), controller  82  resets the counter (S 30 ), and then advances the processing to S 32 . 
     In S 32 , controller  82  determines whether the count value of the counter ≥N. However, “N” is a predetermined integer value. In this determination, when it is determined that a count value of the counter ≥N (S 32 : YES), controller  82  determines that component mounting machine  10  is now in its device life (S 34 ), resets the counter (S 36 ), and then terminates the mounting inspection process. 
       FIG.  3    illustrates an example of transition of the deviation amount of one electronic component when the electronic component is repeatedly mounted on the circuit base material. In  FIG.  3   , transition before an arrow represents transition before the feedback control of S 12  is performed, and transition after the arrow represents transition after the feedback control of S 12  is performed. 
     Then,  FIG.  3 ( a )  illustrates a state in which the deviation amount of the electronic component after the mounting converges within the predetermined allowable amount (in the illustrated example, ±α) when the feedback control of S 12  is performed. Meanwhile  FIG.  3 ( b )  illustrates a state in which the deviation amount of the electronic component after the mounting does not converge within a predetermined allowable amount (in the illustrated example, ±α) even when the feedback control of S 12  is performed. 
     Even when rattling occurs due to a long-term use, component mounting machine  10  has a repeatability such that the deviation amount of the electronic component after the mounting does not fall within a predetermined allowable amount, as in the transition before the arrow in  FIG.  3 ( a ) , but falls within the predetermined range as long as the same operation is performed. When the feedback control of S 12  is performed on component mounting machine  10  having the repeatability, as in the transition after the arrow in  FIG.  3 ( a ) , the deviation amount of the electronic component after the mounting falls within the predetermined allowable amount, and thus, the mounting accuracy at the time of new mounting can be maintained even in a device with reduced mounting accuracy. 
     Meanwhile, in a case where component mounting machine  10  does not have the repeatability as in the transition before the arrow in  FIG.  3 ( b ) , even when the feedback control of S 12  is performed, the deviation amount of the electronic component after the mounting does not fall within the predetermined allowable amount as in the transition after the arrow in  FIG.  3 ( b ) . Accordingly, in the example of  FIG.  3 ( b ) , it is determined that the count value of the counter ≥N in S 32 , and it is determined in S 34  such that the device life of component mounting machine  10  has come. 
     Meanwhile, when it is determined that the count value of the counter &lt;N in the determination of S 32  (S 32 : NO), controller  82  terminates the mounting inspection process. 
     As described above, component mounting machine  10  of the present embodiment includes base material conveyance/holding device  22  configured to convey the circuit base material and hold the circuit base material at the predetermined position, component mounting device  24  configured to mount the electronic component supplied by component supply device  30  on the circuit base material held at the predetermined position, ceiling camera  26  configured to capture, in a field of view of ceiling camera  26 , an entirety of a predetermined region including the circuit base material held at the predetermined position, imaging command section  160  configured to command ceiling camera  26  to image the predetermined region, first detection section  162  configured to detect at least one calibration mark  23   a  provided on base material conveyance/holding device  22  and at least one base material mark provided on the circuit base material, based on imaging data imaged according to the command of imaging command section  160 , calculation section  164  configured to calculate a position on the circuit base material where the electronic component is to be mounted, based on calibration mark  23   a  and the base material mark detected by first detection section  162 , mounting command section  166  configured to command component mounting device  24  to mount the electronic component at the position on the circuit base material calculated by calculation section  164 , second detection section  168  configured to detect the deviation amount between a position on the circuit base material where component mounting device  24  actually mounts the electronic component according to the command of mounting command section  166  and the position on the circuit base material calculated by calculation section  164 , and feedback section  170  configured to feed back, as a correction value for correcting a position on the circuit base material to be calculated next by calculation section  164 , a part of the deviation amount detected by second detection section  168 . 
     As described above, in component mounting machine  10  of the present embodiment, it is possible to reflect the result of measuring the mounting position of the electronic component mounted on the circuit base material in the mounting of the next electronic component. 
     Incidentally, in the present embodiment, ceiling camera  26  is an example of an “imaging device”. Calibration mark  23   a  is an example of a “device mark”. 
     Ceiling camera  26  includes one or more cameras. 
     As a result, it is possible to improve resolution with respect to a subject. 
     Ceiling camera  26  is installed in a ceiling portion of component mounting machine  10 . 
     As a result, the entire predetermined region including the circuit base material can be captured in the field of view. 
     In addition, base material conveyance/holding device  22  includes conveyor rail  23  for conveying the circuit base material, and calibration mark  23   a  is provided on conveyor rail  23 . 
     As a result, since both calibration mark  23   a  and the base material mark are included in the predetermined region including the circuit base material, both calibration mark  23   a  and the base material mark are included in the imaging data. Then, since both calibration mark  23   a  and the base material mark are shaken by the vibration generated when component mounting machine  10  mounts the electronic component, by performing the calibration based on calibration mark  23   a  and calculating the mounting position based on the base material mark detected from the imaging data after the calibration, it is possible to cancel the shake component mixed in the imaging data. 
     In addition, component mounting machine  10  further includes first determination section  172  configured to determine whether the deviation amount converges within a predetermined range, and second determination section  174  configured to determine that there is an abnormality in component mounting machine  10  when it is determined that the deviation amount does not converge within the predetermined range by first determination section  172 . 
     As a result, it is possible to self-determine the abnormality of component mounting machine  10 . 
     Incidentally, the device life is an example of the “abnormality”. 
     It should be noted that the present disclosure is not limited to the above embodiment, and various modifications can be made without departing from the gist thereof. 
     (1) In the above embodiment, multiple calibration marks  23   a  and multiple base material marks are provided in order to specify the direction. Accordingly, as long as the direction can be specified by one mark, for example, by the shape, multiple marks need not be provided. 
     (2) In the above embodiment, ½ of the deviation amount of the mounted electronic component is adopted as the feedback deviation amount, but the present disclosure is not limited to this, and other values such as ¼ and ⅙ may be employed. However, the entire deviation amount cannot be set as the feedback deviation amount. This is because, as described above, since the imaging data used when calculating the deviation amount inevitably includes the reading error by ceiling camera  26 , the mounting accuracy is prevented from being reduced by the reading error. 
     (3) In the above embodiment, the mounting position of the electronic component on the circuit base material is calculated based on the base material mark detected from imaging data in S 20 , but the present disclosure is not limited to this, and may be calculated or determined based on a land detected from the imaging data. 
     REFERENCE SIGNS LIST 
       10 : component mounting machine,  22 : base material conveyance/holding device,  26 : ceiling camera,  30 : component supply device,  82 : controller,  160 : imaging command section,  162 : first detection section,  164 : calculation section,  166 : mounting command section,  168 : second detection section,  170 : feedback section,  172 : first determination section,  174 : second determination section