JP2008021706A - Three-dimensional measuring method of electronic part - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To surely measure an electronic part held by a suction nozzle or the like for a short time, even if it is being held inclined to horizontal direction when it is subjected to three-dimensional measurement. <P>SOLUTION: Line light is projected to an electronic part held by a holding means, and the line-cutting line is sensed. Based on the obtained image data, the flatness of the electronic part is measured in three-dimensional manner. In this case, the scanning range of line light is set exceeding the existence predicted range of the held electronic part, and, after an electronic part P is held by the holding means, light is intermittently projected at a specified pitch of 1 to 10 in the scanning range while scanning line light, so as to determine a measuring position beforehand from the images sensed every pitch. The line light is positioned at the determined measuring positions (2) and (9) to image a light cutting line when the light is projected. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a three-dimensional measurement method for electronic components, and more particularly to a three-dimensional measurement method for electronic components suitable for application to an electronic component mounting apparatus that automatically mounts on a printed circuit board or a substrate such as a liquid crystal display or a display substrate.

  For example, Patent Document 1 discloses an electronic component mounting apparatus that mounts electronic components such as so-called QFP and SOP on a substrate after three-dimensional measurement.

  As shown in FIG. 1, the three-dimensional measuring apparatus provided in the mounting apparatus illuminates the electronic component 130 held by the suction nozzle 117 by the LED illumination light source 131, and below the electronic component 130. Two-dimensional data for positioning is acquired by imaging with a CCD camera 126 arranged.

  Thereafter, after correcting the suction angle of the electronic component 130 from the two-dimensional data, the laser diode 121 is turned on, and the spot light that has passed through the collimator lens 122 and the focus lens 123 is reflected by the light projection mirror 124, thereby producing a line. The generator lens 125 projects line light 125 </ b> A onto the terminal portion 130 </ b> A of the electronic component 130 from an angle of 45 ° downward.

  Further, the light projection unit 127 is moved in the horizontal direction in the figure by the linear motor 128 to scan the electronic component 130 with line light. The projected image of the line light 125A is picked up by the CCD camera 126, the height data of each terminal is acquired from the light cutting line by the line light, and the flatness of the terminal portion 130A is inspected. If the flatness is appropriate, the electronic component 130 is mounted on the substrate based on the positioning data.

JP 2001-60800 A

  However, in the three-dimensional measuring apparatus disclosed in Patent Document 1, the height measurement (three-dimensional measurement) of the electronic component is performed by irradiating the electronic component with line light from obliquely below as shown in FIG. Because the height data of the terminal is acquired using a part of the diffusely reflected light (light reaching the camera), the posture of the electronic component to be inspected at the inspection location is tilted from the horizontal direction in this method. In such a case, the line light may not be applied to the terminal portion to be measured, which may make measurement impossible.In this case, the scanning and imaging are performed while slightly shifting the line light irradiation position. There is a problem that the measurement time becomes very long because it is necessary to repeat the operation several times until it reaches a position where the line light can be irradiated.

  The present invention was made to solve the above-mentioned conventional problems, and when the electronic component held by the suction nozzle or the like is three-dimensionally measured, even when the electronic component is held tilted from the horizontal direction, It is an object of the present invention to provide a three-dimensional measurement method of an electronic component that can be measured in a short time.

  The present invention relates to a third order of an electronic component that images a light cutting line when line light is projected onto the electronic component held by the holding means and measures the flatness of the electronic component based on the obtained image data. In the original measurement method, the scanning range of the line light is set beyond the expected range of the electronic component to be held, and after the electronic component is held by the holding means, the line light is scanned within the scanning range. However, light is intermittently projected at a predetermined pitch, a measurement position is determined in advance from an image captured at each pitch, and a light cutting line when the line light is positioned and projected at the determined measurement position. By taking an image, the above-mentioned problem is solved.

  In the present invention, the determination of the measurement position may be performed when imaging at a normal measurement position assumed for a normal holding part fails.

  According to the present invention, since the three-dimensional measurement can be started after the measurement position is confirmed and determined in advance, it is not necessary to repeat scanning and imaging until the measurement position is found even if the electronic component is tilted and held. As a result, it is possible to significantly reduce the time required for measuring electronic components that are not normally held.

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

  FIG. 2 is a perspective view showing an overview of the electronic component mounting apparatus used in the embodiment according to the present invention.

  In this electronic component mounting apparatus, a transport path 2 is disposed in the center of the base 1 in the X direction. The transport path 2 also serves as a substrate holding unit, transports the substrate 3 in the X direction, and holds and positions the substrate 3 at a predetermined position on the transport path 2.

  In addition, electronic parts supply units 4 are arranged on both sides of the conveyance path 2, and a large number of parts feeders 5 are arranged in parallel in each supply unit 4. Each of the parts feeders 5 sequentially supplies the electronic components by feeding a tape that stores and holds the electronic components in the length direction.

  The X-axis table 6 is mounted with a transfer head 7 for electronic components. Both ends of the X-axis table 6 are supported by Y-axis tables 8A and 8B arranged in parallel to face each other. It is erected. By driving the X-axis table 6 and the Y-axis tables 8A and 8B, the transfer head 7 is moved in the horizontal direction, and the parts feeder 5 is attached by a suction nozzle 10 shown in FIG. The electronic component is picked up from the component suction position and transferred onto the substrate 3.

  The transfer head 7 is moved by XY direction driving means comprising the X-axis table 6 and the Y-axis tables 8A and 8B. Below the movement path between the conveyance path 2 and the supply unit 4 is from a CCD camera or the like. A component recognition camera 9 is provided, and the transfer head 7 and the suction nozzle 10 are imaged from below by the camera 9.

  Then, the electronic component held by the transfer head 7 is imaged by the camera 9 so that the electronic component is identified and the displacement is detected. A three-dimensional measuring device 14 for inspecting the flatness of the terminal portion of the electronic component is disposed in the vicinity of the camera 9. The three-dimensional measuring device 14 will be described in detail later.

  A plurality of nozzle shafts 11 are respectively attached to the θ-axis motor 12 in the transfer head 7 as shown in an enlarged view in FIG. 3, and each nozzle shaft 11 can be independently rotated in the θ direction. The transfer head 7 is provided with a Z-axis motor 13 corresponding to each nozzle shaft 11 so that each nozzle shaft 11 can be moved up and down independently. A suction nozzle 10 is detachably mounted at the tip of each nozzle shaft 11, and a suction hole for sucking air and holding an electronic component is provided at the tip of the suction nozzle 10.

  When the laser light from the laser diode 15 is incident on the light projecting mirror 18 via the collimator lens 16 and the focus lens 17, as shown in FIG. The reflected light is irradiated (projected) to the electronic component P held by the suction nozzle 10 as line light by the line generator lens 19. An imaging mirror 20 is disposed below the component P held by the suction nozzle 10, and an imaging camera 21 is disposed in the reflection direction of the imaging mirror 20.

  The light projecting unit 26 in which the focus lens 17, the light projecting mirror 18, and the line generator lens 19 are integrally incorporated is directly connected to the linear actuator 22, and the electronic component P that is normally held in the horizontal direction. Driven in a direction parallel to the lower surface (in the direction of the double arrow in the drawing) and perpendicular to the irradiation line at the tip of the irradiated line light L, as shown in the top view of the main part of FIG. It has become.

  The three-dimensional measuring device 14 applied to the present embodiment has the basic configuration described above except that the direction of reflection of the laser light by the light projection mirror 18 differs by 90 ° and has a structure in response thereto. This is substantially the same as that shown in FIG. Therefore, the principle of three-dimensional measurement is substantially the same.

  Next, the three-dimensional measurement operation of the present embodiment having the above configuration will be described with reference to the flowchart shown in FIG.

  First, when the substrate 3 is loaded and positioned on the transport path 2 shown in FIG. 2 (steps 1 and 2), the transfer head 7 is mounted on the tip of the nozzle shaft 11 to pick up electronic components. The suction nozzle 10 that has been moved is moved onto the supply unit 4 (step 3).

  After the transfer head 7 is set to the component suction position, when the nozzle shaft 11 is lowered by driving the Z-axis motor 13, the suction nozzle 10 at the tip of the nozzle shaft 11 is lowered to the component suction height and is stored in the parts feeder 5. Immediately before coming into contact with the component, a vacuum generator (not shown) is actuated to create a negative pressure in the pipe line of the nozzle shaft 11, thereby sucking the electronic component in contact with the tip of the suction nozzle 10 (step 4). .

  Thereafter, in order to recognize the picked-up position and angle of the picked-up electronic component, it moves onto the component recognition camera 9 provided in the mounting apparatus body (step 5), and the position of the picked-up component is recognized (step 6). . Based on the result of the position recognition, the transfer head 7 moves onto the three-dimensional measuring device 14 disposed in the vicinity of the camera 9 (step 7), and the height measurement location of the sucked electronic component Are positioned so as to be the measurement position of the three-dimensional measuring device 14 (focal position of the line light).

  Next, the three-dimensional measurement by the three-dimensional measuring apparatus shown in FIG.

  The light emitted from the laser diode 15 which is a light source is condensed by the collimating lens 16 and becomes parallel light. The focus lens 17 narrows down the parallel light to become spot light. Spot light from the focus lens 17 is bent by the light projection mirror 18 so as to form an angle of 45 ° with the vertical axis.

  The line generator lens 19 placed immediately behind the bent optical path is a line light having a width (thickness) of 30 μm and a length of 40 mm (direction perpendicular to the paper surface of FIG. 4, dimension W of FIG. 5). As L, the light is projected to the terminal Pa of the electronic component P to be measured.

  Part of the diffusely reflected light from the terminal Pa of the electronic component P (component perpendicular to the terminal of the electronic component) is reflected by the imaging mirror 20 and captured by the imaging camera 21. Also, at this time, the light projecting unit 26 connected to the linear actuator 22 is driven by the linear actuator 22 in the direction of the left and right arrows shown in the figure (with respect to the irradiation line of the line light that is parallel to the electronic component lower surface and is irradiated Perform a linear motion back and forth in the orthogonal direction.

  As a result, the light projecting unit 26 performs forward / backward linear movement toward the parallel light beam formed by the collimator lens 16. Since the image forming action of the lens 17 is not affected, when the electronic component P to be measured is normally held in the horizontal direction, the line light of a certain width is always irradiated to the terminal. Become.

  Therefore, in FIG. 4, the light projecting unit 26 is moved from right to left at a constant speed (for example, 700 mm / sec). When the light reaches the position where the diffuse reflected light can enter the predetermined location in the field of view of the imaging camera 21, the laser diode 15 is turned on for a predetermined time (for example, 50 μsec). Then, since the light reflected by the terminal of the electronic component in a light projection position enters into the imaging camera 21, it can measure height by imaging it.

  This height measurement can be performed without problems if the position of the electronic component being held is horizontal, so the measurement position can be assumed, but if it is tilted from the horizontal direction, there is no terminal at the light projection position. There is a case. In this case, since it is necessary to shift the light projection position little by little and repeat until the light hits the terminal, and repeatedly perform light projection and imaging, it takes a long time for measurement.

  Therefore, in the present embodiment, before performing the three-dimensional measurement by scanning the line light L, the projection position is sufficiently short, for example, at an interval of 0.5 mm, regardless of the size (pitch) of the terminal position of the electronic component. Thus, the light reflected on the electronic component to be measured is similarly intermittently captured by the imaging camera.

  Then, if the attitude is horizontal depending on the attitude of the imaged electronic component, the reflected light projected to the normal measurement location assumed in advance is imaged, but the attitude of the electronic component is inclined as described above. If so, the reflected light from the assumed normal measurement location may not be imaged.

  However, when the electronic component P is held by the suction nozzle 10, the scanning range of the line light is set in advance so as to exceed the maximum range where the electronic component P is expected to exist, and the entire scanning range is as described above. By intermittently projecting line light and capturing an image, it is possible to estimate the posture of the electronic component from the captured intermittent reflected light pattern and to determine an optimal light projecting position. When the optimum light projection position is determined in this way, the height can be accurately measured only by setting it as the measurement position, scanning again, and imaging at the measurement position. The determination of the projection position (measurement position) will be described later with a specific example.

  By performing image processing on the image data thus captured, three-dimensional measurement of the electronic component can be performed. The principle of this three-dimensional measurement will be briefly described below.

  FIG. 7 is a diagram showing a state in which the example of the electronic component is QFP and the lead terminal is three-dimensionally measured.

  FIG. 7A shows that the electronic component P is parallel to each of the XY axes on the top of the three-dimensional measuring device 14 by driving the respective axes of XYθ, and the field of view of the three-dimensional measuring device 14 is shown. It is a top view which shows the state positioned so that it might correspond to a center position, and has shown the image of the state in which the line light L scanned by the linear actuator 22 is irradiated to the lead terminal Pa of the electronic component P. FIG.

  FIG. 7B is a side view showing a state where a part of the light diffusely reflected by the lead terminal Pa is reflected in the vertical direction (light captured by the imaging camera). C) is an enlarged view of the lead terminal Pa irradiated with the line light L in FIG.

  Here, among the lead terminals Pa to be measured, there is a lead terminal Pb having a different height compared to others due to deformation or the like, and the height at which the line light L is irradiated by this is shown in FIG. As shown, suppose that it differs from the normal terminal Pa by Δt. When the line light L is irradiated, the lead terminal Pa is picked up as an optical section line image as shown in FIG. 8 by an imaging camera provided below the lead terminal Pa, but the lead terminal Pb having a different height is Δx as shown in FIG. The image is taken at a position that is far away. Since the projection angle of the line light L is 45 ° with respect to the lead terminal Pb, Δx = Δt and three-dimensional (height) measurement is possible.

  As a result of the three-dimensional measurement in step 8, when a terminal having a different height is detected in the measurement component and the measured value Δx is larger than a threshold that can be arbitrarily set, the measured electronic component is abnormal (NG). Accordingly, an appropriate error process such as moving to a return tray (not shown) in the apparatus and returning the suction component by air blow is performed (step 9).

  Next, a detailed description will be given of a method for selecting an optimum light projection position using line light that is intermittently projected at a predetermined pitch within a preset scanning range of line light.

  As described above, before the height (three-dimensional) measurement is performed, the terminal position in the planar direction of the corresponding part is selected and determined in advance. At that time, if the line light is scanned and projected at a normal measurement position on the assumption that the electronic component is normally held, as shown in FIG. 9, if the electronic component P actually held is in a horizontal posture, The line light projected to the terminal Pa of the light reaches the diffused reflected light for height measurement and returns to the camera. However, if the electronic component is not even as shown in P ′, the terminal Pa is used. It happens that the scanning light does not strike ′ and is transmitted.

  Therefore, as shown in FIG. 10, the scanning range of the line light is set beyond a range that is slightly larger than the size of the electronic component held by the suction nozzle 10, that is, a range in which the presence of the electronic component P is assumed. In addition, if line light is projected intermittently at a constant pitch within that range, some of them hit the target terminal. As a result, a high brightness image corresponding to the pattern shown in FIG. 8 is obtained.

  Therefore, the coordinates of the scanning position of the line light obtained from the encoder output of the linear motor 22 at that time are stored in a memory of a control device (not shown), and the line light is projected at the timing when the coordinates are scanned at the next scanning. If it is illuminated, it is possible to project the scanning light necessary for the optimum height measurement. In the case of FIG. 10, it is sufficient to project the scanning light at the timings of (2) and (9).

  Further, in this first intermittent scanning / projection of line light, some terminals may be superimposed on the adjacent pitch and may not have a specified pitch. At that time, it means that the terminal has a bend of a specified value or more, and it is possible to determine the quality of the measurement component only by the first intermittent scan.

  As a result of the three-dimensional measurement in step 8 described in detail above, in the case where the abnormality of the electronic component is not recognized, the transfer head 7 is placed at a predetermined position on the substrate 3 fixed to the transport path 2. The electronic component is mounted on the substrate 3 by driving the θ-axis motor 12 and the Z-axis motor 13 (step 11).

  Thereafter, the production operation is continued until all the electronic components are mounted on the substrate 3 (step 12).

  According to the present embodiment described in detail above, the measurement position of the electronic component P held by the suction nozzle 10 can be reliably determined in advance, so that the conventional method takes time. Even an electronic component whose posture is tilted before measurement is impossible can perform three-dimensional measurement in a short time.

  In addition, since an optimal light projection (measurement) position can be selected and determined in advance, highly accurate three-dimensional measurement can be performed reliably.

  At that time, the measurement position can be determined in a shorter time by performing the determination of the measurement position only when imaging at the normal measurement position assumed for the normally held electronic component fails.

  Furthermore, if the purpose is not measurement but determination of whether a part is good or bad, it becomes possible to sort defective products in a shorter time.

  In the above embodiment, the line light is intermittently projected at a constant 0.5 mm pitch. However, the present invention is not limited to this, and the pitch interval may be changed alternately. It may be possible to select an optimum position by partially changing the pitch interval, for example, by making the pitch finer in a range where the target existence probability is high.

Side view showing the outline of the three-dimensional measuring device The perspective view which shows the general view of the electronic component mounting apparatus applied to one Embodiment which concerns on this invention The perspective view which shows the transfer head mounted in the said electronic component mounting apparatus Schematic side view showing a three-dimensional measuring device applied to one embodiment according to the present embodiment Explanatory drawing which shows the state which looked at the principal part of the said three-dimensional measuring apparatus from the upper surface Flow chart showing the operation of this embodiment Explanatory diagram showing the principle of three-dimensional measurement Other explanatory diagram showing the principle of three-dimensional measurement Explanatory diagram showing normal and abnormal state of 3D measurement Explanatory drawing which shows the effect | action and effect of this embodiment

Explanation of symbols

10 ... Suction nozzle (holding means)
DESCRIPTION OF SYMBOLS 14 ... Three-dimensional measuring apparatus 15 ... Laser diode 16 ... Collimating lens 17 ... Focus lens 18 ... Projection mirror 20 ... Imaging mirror 21 ... Imaging camera 22 ... Linear actuator 26 ... Projection unit P ... Electronic component Pa ... Terminal L ... Line light

Claims (2)

In a three-dimensional measurement method for an electronic component that images an optical cutting line when line light is projected onto an electronic component held by a holding unit and measures flatness of the electronic component based on obtained image data ,
Set the scanning range of the line light beyond the expected range of electronic components to be held,
After holding the electronic component in the holding means, while scanning the line light within the scanning range, intermittently project light at a predetermined pitch, determine the measurement position in advance from the image captured for each pitch,
A three-dimensional measurement method for an electronic component, characterized in that an optical cutting line is imaged when a line light is positioned and projected at a determined measurement position.   The method of three-dimensional measurement of an electronic component according to claim 1, wherein the measurement position is determined when imaging at a normal measurement position assumed for a normal holding component fails.

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