JP5113406B2 - Electronic component mounting equipment - Google Patents

Description

  The present invention relates to an electronic component mounting apparatus, and more particularly to an imaging unit provided on a transfer head for improving three-dimensional imaging accuracy with respect to an electronic component mounting target and improving component mounting accuracy. And a suitable electronic component mounting apparatus.

  In order to mount (mount) an electronic component on a wiring board such as a printed circuit board, an electronic component mounting apparatus is generally used (see, for example, Patent Document 1). In such an electronic component mounting apparatus, an electronic component supplied to a predetermined position is sucked and held by a suction nozzle mounted on a transfer head and then mounted on a target position on a positioned substrate. ing.

  Thus, in order to accurately mount the electronic component held by the suction nozzle at the target position on the wiring board, it is necessary to accurately grasp the position of the wiring board. Therefore, for example, in the electronic component mounting apparatus disclosed in Patent Document 2, the imaging means fixed on the transfer head images the fiducial mark (reference mark) on the wiring board, and the imaging result Thus, so-called image recognition is performed in which the exact position of the substrate is specified by calculation.

JP 2003-168899 A JP 2000-294996 A

  However, in the conventional electronic component mounting apparatus disclosed in Patent Documents 1 and 2 and the like, the mounting target recognized by the imaging unit is only a flat wiring substrate such as a printed circuit board. When three-dimensional mounting is performed with different (changing) heights, such as mounting other electronic components, the reference mark on the mounting surface is recognized and the electronic components after mounting are installed. The mounting position cannot be confirmed by image recognition.

  Also, if the mounting surface of the wiring board or the like is greatly warped or bent, the mounting position accuracy is reduced due to defocusing when recognizing the reference mark or the mounting height variation. There was also.

  The present invention has been made to solve the above-described conventional problems, and provides an electronic component mounting apparatus that can accurately mount an electronic component at a target position even when the electronic component is mounted on a non-flat mounting target. Let it be an issue.

The present invention relates to an electronic component mounting apparatus in which an electronic component is held by a nozzle mounted on the tip of a shaft that is attached to a transfer head so as to be movable back and forth in the vertical direction, and the electronic component is mounted on the mounting target. recognizing the image pickup means a specific site, and drive means for advancing and retreating the image pickup means in the vertical direction is arranged on the transfer head, when moved back and forth movement of the imaging means in the vertical direction by said driving means Means for storing a horizontal displacement amount corresponding to the vertical position of the imaging means acquired, and acquiring a horizontal displacement amount corresponding to the vertical position of the imaging means. In this case, the imaging means is moved directly above a three-dimensional calibration jig for correcting an optical axis shift when the imaging means moves back and forth in the vertical direction. is there

  In the present invention, there may be further provided means for storing a relative displacement amount in the horizontal direction with respect to the vertical position of the nozzle acquired when the nozzle is moved forward and backward in the vertical direction.

  According to the present invention, the image pickup means for picking up a reference position (specific part) such as a mark on the mounting target can be moved in the vertical direction, and the positional deviation amount acquired in advance by actually moving the image pickup means is obtained. On the basis of this, since the horizontal displacement of the image pickup means can be corrected at an arbitrary position in the vertical direction, it is possible to accurately recognize the positions on the mounting objects having different heights. Therefore, by imaging the reference position on the mounting target having an arbitrary height by the imaging means, an accurate position on the mounting target can be determined based on the reference position in the captured image. It can be accurately mounted on a mounting target such as a mounting surface.

  In addition, when storing the amount of displacement in the horizontal direction with respect to the vertical direction of the nozzle, conventionally, it occurs due to the linear motion accuracy of the nozzle shaft when the mounting height is different or the thickness of the suction component is greatly different. Since the displacement of the mounting position can be corrected, more accurate component mounting is possible.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a perspective view showing an appearance of an electronic component mounting apparatus according to an embodiment of the present invention.

  In FIG. 1, a transport path 2 is disposed at the center of a base 1. The conveyance path 2 conveys the substrate 3 in the X direction, and also serves as a substrate holding unit that positions and holds the substrate 3 at the illustrated position.

  On both sides of the transport path 2, electronic component supply units 4 are arranged, and a large number of parts feeders 5 are mounted in parallel on each supply unit 4. Each parts feeder 5 is configured to sequentially supply the electronic components housed and held in the tape to the pickup position by feeding the tape in the longitudinal direction.

  The X-axis table 6 is mounted with an electronic component transfer head 7. The X-axis table 6 is supported and installed at both ends by a Y-axis table 8A and a guide 8B arranged in parallel to face the Y-axis table 8A.

  By driving the X-axis table 6 and the Y-axis table 8A by a motor (not shown), the transfer head 7 can be moved in the horizontal direction, and as shown in an enlarged view in FIG. An electronic component is picked up and picked up from the pickup position of the parts feeder 5 by the nozzle 10 and transferred (mounted) onto the substrate 3. Therefore, the X-axis table 6 and the Y-axis table 8 </ b> A serve as horizontal driving means for the transfer head 7.

  A component imaging means 9 is disposed in an area between the conveyance path 2 and the supply unit 4 where the movement path of the transfer head 7 is set. The component imaging means 9 images the suction nozzle 10 mounted on the transfer head 7 from below and images the suctioned and held electronic component, thereby identifying the electronic component and shifting the position from the nozzle center. Detection is performed.

  The transfer head 7 provided in the electronic component mounting apparatus of this embodiment will be described in detail.

  In FIG. 2, four suction heads are mounted on the transfer head 7, and a nozzle shaft 11 is attached to the θ-axis motor 12 for each suction head, and each nozzle shaft 11 can rotate independently in the θ direction. Yes.

  Each nozzle shaft 11 can be moved up and down independently by a Z-axis motor 13, and a suction nozzle 10 provided with a suction hole for sucking air at the tip of the nozzle shaft is detachable. It is installed.

  These four suction heads are arranged on the head plate 14 which is the base of the transfer head 7 so as to be aligned in the X-axis direction.

  A substrate imaging means 16 for recognizing the fiducial mark 15 on the substrate 3 is attached to the head plate 14. In this board imaging means 16, a CCD camera 16 </ b> A and a lens 16 </ b> B are integrally movable through a linear guide 17 by a ball screw 18 in the vertical direction. The ball screw 18 is connected to a servo motor 19 for driving the image pickup unit, and the CCD camera 16A and the lens 16B, which are the image pickup unit, can be moved and stopped at arbitrary heights by driving the servo motor 19. It has become.

  Further, as shown in FIG. 2, below the substrate imaging means 16, a coaxial illumination substrate 20A including LEDs, a beam splitter (or half mirror) 21 for coaxial illumination, and a circular oblique illumination substrate also including LEDs. 20B is arranged, and the illumination means suitable for the recognition object is selected at appropriate times by the CPU of a control device (not shown) built in the apparatus main body. The illumination substrates 20A and 20B and the beam splitter 21 are fixed to the head plate 14 and are not moved together with the substrate imaging means 16.

  In the electronic component mounting apparatus of the present embodiment, a three-dimensional calibration jig 22 for correcting an optical axis shift when the board imaging unit 16 is driven in the vertical direction is provided at a predetermined position of the base 1. ing. However, the jig 22 can be removed as necessary.

  As shown in FIG. 3A, the three-dimensional calibration jig 22 has a shape in which a plurality of circular marks are drawn (or grooves are cut) at equal intervals on the conical surface. When seen, as shown in FIG. 5B, the shape is such that a plurality of concentric marks having different diameters are arranged at different heights.

  The mark size is designed so that the maximum jig bottom surface is within the visual field range (for example, φ20 mm) of the substrate imaging unit 16 and the height is within the driving range of the substrate imaging unit 16 (for example, 20 mm). . Further, these concentric circle marks are drawn at regular height intervals (for example, 1 mm).

  Further, as shown in FIG. 4, the bottom surface of the calibration jig 22 is positioned lower than the upper surface (electronic component mounting surface) of the substrate 3 by a predetermined height (for example, 2 mm), and the substrate 3. It is installed at a predetermined location of the base 1 so that the central axis is perpendicular to the upper surface of the base 1.

  The transfer head 7 is moved in the horizontal direction by the X-axis table 6 and the Y-axis table 8, and the substrate imaging unit 16 is moved immediately above the calibration jig 22. The calibration jig 22 can be imaged at this timing. In this case, according to the height of the board imaging means 16, a concentric circle mark having the same focal height as shown in FIG. 5 is clearly imaged.

  Further, in the present embodiment, as shown in FIG. 6, a calibration jig nozzle 22A (the three-dimensional calibration jig 22 in FIG. Equivalent) is attached. Therefore, by moving the transfer head 7 so that the jig 22A is directly above the component imaging means 9 by XY driving, the calibration jig nozzle 22A can be imaged using the component imaging means 9. Thus, an image similar to that in FIG. 5 can be acquired according to the moving height of the nozzle shaft 11.

  The calibration jig nozzle 22A is detachable at an arbitrary timing by an automatic nozzle changer (not shown) provided in the apparatus main body, and can be converted into the suction nozzle 10.

  As described above, the electronic component mounting apparatus according to the present embodiment uses the calibration jig 22 to measure the amount of horizontal misalignment according to the vertical position of the board imaging unit 16 and perform three-dimensional correction. A function of correcting the horizontal position of the imaging target in accordance with the height at the time of actual imaging is obtained by acquiring the data in advance and storing it in the storage means. The acquisition of the three-dimensional correction data will be described later.

  Similarly, the electronic component mounting apparatus according to the present embodiment uses the calibration jig nozzle 22A to measure the amount of horizontal displacement according to the vertical position of the nozzle shaft 11 with respect to the component imaging means 9, It has a function of correcting the horizontal position of the mounting target in accordance with the height of the nozzle shaft 11 when actually mounting the component by acquiring it in advance as three-dimensional correction data and storing it in the storage means. It is like that.

  Next, the operation of this embodiment will be described with reference to the flowchart shown in FIG.

  The loading of the substrate is started (step 1), it is determined whether or not it is a substrate that needs three-dimensional correction (step 2), and if necessary, the three-dimensional correction relating to the substrate imaging means 16 and the nozzle shaft 11 is performed. Data (correlation equations (1) and (2)) is acquired (steps 3 and 4).

  First, acquisition of the three-dimensional correction data in steps 3 and 4 will be described in detail. This operation may be performed until the completion of the substrate loading in step 5, that is, before the start of the production operation such as when the apparatus is turned on or when the substrate is loaded.

  In acquiring the correction data, the transfer head 7 and the substrate imaging means 16 on the head are mounted on the base 1 as shown in FIG. Move so that it is directly above 22.

  Next, the servo motor 19 is driven, and the board imaging means 16 is moved to a height where the bottom surface of the three-dimensional calibration jig 22 (the top surface of the base 1) is in focus.

  Thereafter, by driving the servo motor 19, the board imaging means 16 is raised at a predetermined speed by the height of the calibration jig 22 (for example, 20 mm). At the time of this rise, the reference image is picked up by the substrate image pickup means 16 at every mark height interval (for example, 1 mm) provided on the calibration jig 22. As shown in FIG. 5, the captured image is focused only on a mark with any height that matches the imaging height, and the reference marks at other heights are different in focus height. Will be taken out of focus.

From the images thus obtained, the center coordinates of the circular mark corresponding to the height at the time of imaging are calculated by image recognition processing. Originally, all the circular marks provided on the calibration jig 22 are all concentric circles, so the center coordinates of the circular marks should not fluctuate theoretically. Depending on the straightness of the rail and the like, the center of the recognition position varies in the horizontal direction according to the imaging height. Therefore, the fluctuation amount is acquired as correction data by image recognition.

Thereby, the correlation formula between the height of the board imaging means 16 (encoder value of the servo motor 19: z) and the center coordinates (X, Y) of the mark obtained from each image X = f (z), Y = g (z) (1)
Is stored in a storage device (RAM) (not shown) inside the apparatus main body.

At this time, the center coordinates (X, Y) of the mark are calculated as deviations from the center coordinates at the substrate recognition height (H ₀ ), which is the upper surface of the substrate 3, as a reference (X ₀ , Y ₀ ).

  FIG. 8 shows an image of a function representing a deviation only in the X direction. Although illustration is omitted, a similar relational expression is obtained for the Y direction.

  Next, the transfer head 7 moves so that the center of the calibration jig nozzle 22A is located immediately above the component imaging means 9 on the apparatus main body with the calibration jig nozzle 22A mounted on the nozzle shaft 11. .

Thereafter, the nozzle shaft 11 is raised by the height of the calibration jig nozzle 22 </ b> A (= corresponding to the height (20 mm) of the calibration jig 22) by driving the Z-axis motor 13. At that time, similarly to the calculation method of the above formula (1), the correlation formula between the height of the suction nozzle (encoder value of the Z-axis motor 13: z ′) and the nozzle center coordinates (X ′, Y ′). X ′ ₁ = f (z ′ ₁ ), Y ′ ₁ = g (z ′ ₁ )
Is stored in a storage device (RAM) (not shown) inside the apparatus main body.

At this time, when the nozzle shaft (shaft) 11 are a plurality (= n) obtains a relational expression for each axis, including the z _'1 relationship,
X ′ ₂ = f (z ′ ₂ ), Y ′ ₂ = g (z ′ ₂ )
_{~X 'n = f (z'} n), Y 'n = g (z' n) ... (2)
Are stored in the storage device (RAM) in the same manner.

  Subsequently, a production operation by the electronic component mounting apparatus of the present embodiment having a correction function by storing the three-dimensional correction data of the above formulas (1) and (2) in a storage device will be described.

  First, the substrate 3 is loaded onto the transport path 2 and positioned, thereby completing the substrate loading (step 5).

  Thereafter, in order for the transfer head 7 to recognize the position of a reference mark (fiducial mark 15 on the substrate 3 or an IC mark (not shown)) serving as a reference for the mounting position, the substrate imaging means 16 on the head uses the reference mark ( It moves so that it may be just above a board | substrate mark in the figure (step 6).

  At this time, a focus adjustment preparation position (base 1 in FIG. 4) lower than a predetermined recognition height of the reference mark (in the case of fiducial mark 15, the upper surface of the substrate 3) by a predetermined height (for example, 2 mm). The servo motor 19 is driven so that the focal height of the substrate imaging means 16 coincides with the upper surface of the substrate imaging means 16, and the substrate imaging means 16 is moved (step 7).

  Next, at the same time as the transfer head 7 reaches the reference mark recognition position by the XY movement of step 6, the servo motor 19 is driven, and the board imaging means 16 is set in advance to the measurement range ( For example, 4 mm). At that time, the reference mark is imaged by the substrate imaging means 16 at a predetermined interval (for example, 0.5 mm) at the time of ascent (step 8).

For each image obtained here, a contrast value (for example, a differential value of brightness gradation change) is obtained, and the peak position (Z) when the highest image contrast is obtained as shown in FIG. _p ) is calculated from the approximate expression.

Subsequently, the substrate imaging means 16 is positioned at the contrast peak position (Z _p ) based on the above results, and the reference marks are recognized again by the substrate imaging means 16.

Thereafter, the reference peak recognition position (X _zp , Y _zp ), the contrast peak position (Z _p ) obtained from the correlation equation (1) between the imaging height obtained in advance and the center coordinate position of the calibration jig 22. ) In the horizontal direction (that is, the value obtained by substituting Z _p into the relational expression (1): X _p = f (Z _p ), Y _p = g (Z _p )) The true reference mark position in the horizontal direction at the imaging height is calculated (steps 9 and 10).

  By the above operation, not only the substrate 3 but also the height of the reference mark on the mounting target fluctuates (when the substrate is bent, the mark on the upper surface of the IC chip is recognized, etc.), the substrate imaging means 16 on the head. An accurate reference mark position can be recognized regardless of the linear motion accuracy. That is, the horizontal position of the mounting target can be determined.

  After the height and horizontal position of the mounting target are determined as described above, the transfer head 7 moves onto the supply unit 4 in order to pick up electronic components (step 11). At this time, a predetermined suction nozzle 10 replaced from the jig nozzle 22 </ b> A is attached to the tip of the nozzle shaft 11.

  After the transfer head 7 is set to the component suction position, the nozzle shaft 11 is lowered by driving the Z-axis motor 13. At that time, immediately before the suction nozzle 10 attached to the tip of the nozzle shaft is lowered to the component suction height and comes into contact with the electronic component housed in the parts feeder 5, a vacuum generator (not shown) is operated to operate the nozzle shaft 11. By making the inside of the pipe line into a negative pressure, the electronic component contacting the tip of the suction nozzle 10 is sucked (step 12).

  After the electronic component is picked up by the suction nozzle 10, the transfer head 7 moves onto the component imaging means 9 provided in the apparatus main body in order to recognize the suction position and angle of the suction component, and recognizes the position of the suction component. To do.

At this time, the nozzle center position shift amount at the mounting height (Z ′ _c ) obtained from the correlation formula (2) between the suction nozzle height and the center coordinate position of the suction nozzle obtained in advance (that is, Z 'The value obtained by substituting _c : X _c = f (Z' _c ), Y _c = g (Z ' _c )) is added to the calculated nozzle center position to obtain the true nozzle center position at the mounting height. Is calculated (steps 13 and 14). However, the mounting height (Z ′ _c ) is determined by the height of the component mounting surface and the thickness of the suction component.

  Next, based on the result of the position recognition above, the transfer head 7 moves to a predetermined mounting position on the substrate 3 fixed to the transport path 2 (step 15), and the θ-axis motor 12 and the Z-axis motor 13 The electronic component is mounted on the substrate 3 by driving (steps 16 and 17).

  Even if the mounting height fluctuates, such as when the substrate is bent or mounted on the upper surface of the IC chip, the accurate target position is not affected by the linear motion accuracy of the nozzle shaft 11 due to the operations of steps 13 to 17 described above. An electronic component can be mounted on.

  In the electronic component mounting apparatus of the present embodiment, electronic components can be sequentially mounted on the substrate by repeating the above operations (step 18), and the substrate is unloaded after all components are mounted (step 19). .

  According to the embodiment described above in detail, the following effects can be obtained.

  (1) Even when the height of the reference mark fluctuates (is not constant), it is possible to automatically adjust the substrate imaging means 16 to a height at which the focal position matches, and to accurately recognize the mark position. .

  (2) Even when the height of the mounting surface varies, the electronic component can be mounted at an accurate position.

  (3) Due to the two effects described above, it is possible to provide a highly versatile electronic component mounting apparatus that can support three-dimensional mounting and the like.

  In the above-described embodiment, the CCD camera 16A acquires an image of the entire field of view at the time of focus adjustment for recognizing the reference mark. However, only a part of the effective area of the CCD camera is used as imaging data, The focus value may be adjusted by calculating a contrast value. For example, only a horizontal line near the center of the visual field is acquired by the partial imaging function, as shown in FIG. As a result, the transfer time and the recognition processing time of the image data are shortened, and the focus adjustment can be performed with a higher tact time.

  Further, a correlation formula (1) with the calibration jig center position for each height of the substrate imaging means 16 and a correlation formula (2) with the nozzle center position for each height of the suction nozzle (nozzle shaft). ) Is acquired before the production operation, but the above relational expression is re-acquired at any timing during the production operation at the request of the user, and the device main body is rewritten to the storage device (RAM). May be. Or, when the desired mounting accuracy cannot be obtained, or when the temperature in the head exceeds a preset threshold by a temperature detection sensor (not shown) inside the transfer head, the above acquisition is automatically performed. You may make it perform operation | movement.

  In addition, the reference mark is recognized after the board is loaded. However, if higher mounting accuracy is required or if there is an IC mark or the like for each mounting location, the timely reference mark can be set for each mounting operation. You may make it recognize.

  Further, although a calibration jig provided with a plurality of circular marks on a conical surface is used, any shape may be used as long as a reference mark recognizable at different heights is provided. As shown in the perspective view in FIG. 11A and the plan view from the camera direction in FIG. 11B, a stair-like jig provided with a reference mark such as ○ for each stair Good.

  In the embodiment, the main purpose is to recognize the fiducial mark before mounting, but it goes without saying that the board imaging means 16 can also be used for component mounting position inspection after mounting. .

The perspective view which shows the external appearance of the electronic component mounting apparatus of one Embodiment which concerns on this invention The perspective view which shows the transfer head mounted in the electronic component mounting apparatus of this embodiment A perspective view and a plan view showing the characteristics of the three-dimensional calibration jig Explanatory drawing showing how to install the 3D calibration jig Explanatory drawing which shows the characteristic of the image obtained by imaging a three-dimensional calibration jig The perspective view which shows the attachment state of the three-dimensional calibration jig for nozzle shafts Flow chart showing the operation of this embodiment Diagram showing the image of the obtained correction function Diagram showing the method for determining the height based on the image of the fiducial mark Explanatory drawing which shows the other processing method of the image which imaged the fiducial mark A perspective view and a plan view showing a modification of the three-dimensional calibration jig

Explanation of symbols

DESCRIPTION OF SYMBOLS 2 ... Conveyance path 3 ... Board | substrate 6 ... X-axis table 8A ... Y-axis table 9 ... Component imaging means 10 ... Adsorption nozzle 11 ... Nozzle shaft 12 ... (theta) motor 13 ... Z-axis motor 16 ... Board imaging means 22 ... Three-dimensional calibration Jig 22A ... Three-dimensional calibration jig nozzle

Claims (2)

In an electronic component mounting apparatus for holding an electronic component by a nozzle attached to the tip of a shaft attached to a transfer head so as to be movable back and forth in the vertical direction, and mounting the electronic component on a mounting target,
An imaging unit for recognizing a specific part to be mounted and a driving unit for moving the imaging unit forward and backward in the vertical direction are disposed in the transfer head ,
Means for storing a horizontal displacement amount corresponding to the vertical position of the imaging means acquired when the imaging means is moved forward and backward by the driving means ;
When acquiring the horizontal displacement amount according to the vertical position of the imaging means, the imaging means is a tertiary for correcting the optical axis deviation when the imaging means is moved back and forth in the vertical direction. An electronic component mounting apparatus that is moved directly above an original calibration jig .   2. The apparatus according to claim 1, further comprising means for storing a relative displacement amount in a horizontal direction with respect to a vertical position of the nozzle acquired when the nozzle is advanced and retracted in the vertical direction. Electronic component mounting equipment.

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