JP2012253059A - Electronic component mounting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electronic component mounting device for achieving higher speed in a mounting step and improvement in accuracy of mounting while reducing an amount of vertical motion of a suction nozzle for sucking electronic components.SOLUTION: In a surface mounting device, a suction nozzle A for sucking electronic components B is provided to a nozzle holding member so as to be movable in the vertical direction, and the nozzle holding member makes displacement in a horizontal plane relative to a base for placing a printed board C and the suction nozzle moves vertically so that electronic component sucked to the suction nozzle is mounted on the printed board. Side imaging means for imaging the tip end of the suction nozzle from a side position is provided to the nozzle holding member. The side imaging means images the electronic component B in a state that an optical axis of its optical system D is not in horizontal with respect to a suction face of the suction nozzle A but makes a prescribed angle θ from the above.

Description

  The present invention relates to an electronic component mounting apparatus for mounting an electronic component such as an IC chip on a printed board. In this specification, the electronic component mounting apparatus is also simply referred to as a mounting apparatus, and the electronic component is simply referred to as a component.

  Generally, a mounting apparatus is configured to suck an electronic component from a component supply unit by using a nozzle holding member having a suction nozzle that sucks the electronic component, transfer the electronic component onto a printed board, and mount the electronic component at a predetermined position on the printed board. It is configured.

  In such a mounting device, in order to prevent mounting of defective parts, mounting displacement, mounting mistakes (unmounted), etc., after picking up the components, the tip of the suction nozzle is imaged prior to mounting on the printed circuit board. Then, the image recognition of the presence / absence of a component or the suction state of the component is performed. Further, in order to confirm that the component has been mounted, after the mounting process, the tip portion of the suction nozzle is imaged again to recognize the presence / absence of the component (component take-back).

  As one of imaging means for imaging the tip portion of the suction nozzle, a side imaging means for illuminating and imaging the tip portion of the suction nozzle from the side is known. The conventional side imaging means illuminates and images the tip of the suction nozzle from the horizontal direction as can be seen in Patent Documents 1 to 3. The optical system of the side imaging means is provided on the nozzle holding member together with the suction nozzle. The suction nozzle can be moved up and down, whereas the optical system of the side imaging means is fixed to the nozzle holding member. That is, the optical axis of the optical system of the conventional side image pickup means is horizontal.

  In such a configuration where the optical axis of the optical system is horizontal, when inspecting the suction state to the suction nozzle before mounting the part, the part sucked by the suction nozzle is used to image the part. It is necessary to move the suction nozzle up and down to the substantially same height as the optical axis of the optical system. On the other hand, when mounting a component, since the component already mounted is on the printed circuit board, it is necessary to arrange the lower end of the optical system at a position higher than the maximum height of the component in order to avoid interference with the component. . That is, when the optical axis of the optical system is horizontal, the amount of vertical movement (lowering amount) of the suction nozzle from when the component is sucked and the suction state is inspected until it is mounted on the printed circuit board will be described in detail later. Is a distance corresponding to (maximum part height + distance to the lower end of the optical system).

  In order to speed up the mounting process and improve mounting accuracy, the amount of movement of the suction nozzle in the vertical direction is desired to be reduced, but the actual situation is that the amount of movement cannot be reduced due to the limitations described above. . Also, in order to reduce the amount of movement, it is necessary to reduce the height of the parts, which is a drawback in the device specifications.

JP-A-10-78309 JP 2004-349346 A JP 2006-41158 A

  The problem to be solved by the present invention is to provide an electronic component mounting apparatus capable of reducing the amount of vertical movement of the suction nozzle that sucks the electronic component, speeding up the mounting process, and improving the mounting accuracy. is there.

  In the mounting apparatus of the present invention, a suction nozzle for sucking an electronic component is provided on the nozzle holding member so as to be movable in the vertical direction, and the nozzle holding member is relatively displaced in a horizontal plane with respect to a base on which the printed circuit board is placed. In addition, an electronic component mounting machine configured to mount the electronic component sucked by the suction nozzle on the printed circuit board by moving the suction nozzle in the vertical direction, the tip portion of the suction nozzle from the side The lateral imaging means is capable of imaging and the optical system is fixed to the nozzle holding member, and the lateral imaging means is configured such that the optical axis of the optical system is not horizontal with respect to the suction surface of the suction nozzle. The electronic component is imaged so as to form a predetermined angle from above.

  In the present invention, it is preferable that the optical axis of the optical system of the side image pickup unit forms an angle of 4 degrees or more and 40 degrees or less upward from the horizontal plane that is the suction surface of the suction nozzle.

  In addition, the electronic component mounting apparatus of the present invention includes a pixel rate storage unit that stores a pixel rate obtained by imaging the electronic component normally sucked by the suction nozzle in advance by the side imaging unit; An image correction unit that corrects image data of the electronic component imaged by the side imaging unit using the pixel rate stored in the pixel rate storage unit may be provided.

  In the mounting apparatus of the present invention, since the optical axis of the optical system of the side imaging means is not horizontal with respect to the suction surface of the suction nozzle, but takes an image at a predetermined angle from above, the optical axis of the optical system is In contrast to the horizontal case, the optical system can be arranged at a higher position, and the lower end of the optical system does not become a limiting condition for avoiding interference with parts. Therefore, the part can be imaged with the suction nozzle positioned further downward, and as a result, the lowering distance until the mounting on the printed circuit board after imaging is shortened, the amount of vertical movement of the suction nozzle Can be reduced. Thereby, it is possible to easily increase the speed of the mounting process and improve the mounting accuracy.

It is a conceptual diagram explaining the effect of the mounting apparatus of this invention. It is a conceptual diagram which shows the adsorption | suction state of the components to an adsorption | suction nozzle, (a) is a normal adsorption state, (b) is an abnormal adsorption state, (c) shows the component attracted | sucked. It is a conceptual diagram which shows the positional relationship of the optical system of a suction nozzle and a side imaging means. It is a conceptual diagram which shows the relationship between the focal plane of the optical system of the side imaging means in this invention, and a to-be-imaged surface. FIG. 3 is a conceptual diagram showing a change in an image of a subject (component) due to a difference in pixel rate in the Z-axis direction, where (a) shows the actual shape of the component and (b) shows a captured image. It is a conceptual diagram which shows the change of the pixel rate of a Z-axis direction. It is a perspective view which shows one Example of the mounting apparatus of this invention, (a) is the structure of the principal part, (b) shows the structure of a nozzle holding member vicinity. It is sectional drawing which shows the structural example of a side imaging means.

  FIG. 1 is a conceptual diagram for explaining the effect of the mounting apparatus of the present invention.

  As shown in FIG. 1A, when the component is not attracted to the suction nozzle A, the distance between the lower end surface of the suction nozzle A and the surface of the printed circuit board D is that of the component B ′ already mounted on the printed circuit board D. If the maximum height is a and the allowance considering the variation in component dimensions and warping of the printed circuit board D is b (about 1 to 2 mm), the suction nozzle A will interfere with the component B ′ if (a + b). There is no. When the component B is attracted to the suction nozzle A as shown in FIG. 1B, it is necessary to raise the suction nozzle A by the component thickness c, but the amount of movement of the suction nozzle A for mounting on the printed circuit board D Remains (a + b).

  Next, in order to confirm the suction state of the component B to the suction nozzle A, the side imaging means images the tip of the suction nozzle. In the conventional side imaging means, as shown in FIG. Since the optical axis of the optical system D is horizontal, when the distance between the optical axis of the optical system D and the lower end is d, when the thickness c of the component B is c <d, the lower end of the optical system D is the component B ′. It becomes a limiting condition for avoiding interference with. Further, in order to image the tip portion of the suction nozzle A, it is necessary to align the tip of the suction nozzle A with the optical axis of the optical system D. Therefore, only (dc) is required for the state of FIG. It is necessary to raise the suction nozzle A. As a result, the amount of movement of the suction nozzle A for mounting the component B on the printed circuit board D is (a + b + (dc)).

  On the other hand, in the present invention, as shown in FIG. 1 (d), the side imaging means is such that the optical axis of the optical system D is not horizontal with respect to the suction surface of the suction nozzle A that sucks the component B, The component B is imaged so as to form a predetermined angle θ from above. Therefore, the optical system D can be installed upward, and the lower end of the optical system D is not a limiting condition. Therefore, as shown in FIG. 1 (d), the suction nozzle A can be disposed at a position where the movement amount for mounting is (a + b), and only (d−c) compared with the conventional example of FIG. 1 (c). The amount of movement can be reduced. The magnitude of (dc) is proportional to the inclination angle θ of the optical axis of the optical system D.

  The inclination angle θ is preferably 4 degrees or more and 40 degrees or less. The reason will be described below.

  The quality of the suction state of the component to the suction nozzle is determined by imaging the nozzle tip with the side imaging means, recognizing the image, and analyzing the image. There are various image analysis techniques for determining pass / fail, but a method based on comparison of the heights of the imaged parts is simple, accurate, and frequently used. Specifically, the suction state shown in FIG. 2A is normal, and the suction state shown in FIG. 2B is abnormal. By comparing the heights of the parts B recognized by the side imaging means, the suction state Judge the quality of the.

  Here, as shown in FIG. 2C, the ceramic capacitor which is a typical mounting component has a ratio of length L, width W and height T of L: W: T = 2: 1: 1. It is common. Further, the suction nozzle is often manufactured with a diameter of about W = T = 1. If these are presupposed, the imaging height of the component B in the normal suction state shown in FIG. 2A is T1 + T2 = sin θ + cos θ when the inclination angle of the optical axis of the optical system is θ. On the other hand, the height of the component B in the abnormal suction state shown in FIG. 2B is 2 cos θ. The quality of the suction state is determined by comparing the imaging height (sin θ + cos θ) of the component B in the normal suction state with the imaging height (2 cos θ) of the component B in the abnormal suction state. As the value increases, the difference between (sin θ + cos θ) and (2 cos θ) decreases, and when θ reaches 45 degrees, (sin θ + cos θ) = (2 cos θ), and the quality of the suction state cannot be determined by the imaging height. Accordingly, in this case, the inclination angle θ of the optical axis of the optical system needs to be less than 45 degrees, and the inclination angle θ is preferably set to 40 degrees or less in consideration of variations in component dimensions.

On the other hand, the lower limit of the inclination angle θ is defined by the influence of the lower end of the optical system as a condition. That is, as shown in FIG. 3, due to the structure of the lens D1 constituting the optical system D, the distance Y from the lower end of the optical system to the substantial lower end of the lens D1 needs to be at least about 2 mm. On the other hand, the distance X that the suction nozzle A moves up and down and does not affect the component suction needs to be about 30 mm. Therefore, it is preferable that the inclination angle θ of the optical axis of the optical system is at least tan ⁻¹ (2/30) = 3.8≈4 degrees.

  As described above, in the mounting apparatus of the present invention, the optical axis of the optical system of the side imaging means is inclined at an inclination angle θ with respect to the suction surface of the suction nozzle, that is, the horizontal plane, so that the component is relative to the optical system. The magnification of the captured image differs depending on the location. For example, when the component is a rectangular parallelepiped, the focal plane E of the optical system is shifted by the inclination angle θ with respect to the vertical plane in the Z-axis direction where the side surface (rectangle) of the rectangular parallelepiped is located as shown in FIG. The rectangle (FIG. 5A) positioned at is deformed into a trapezoid when captured by the optical system D (FIG. 5B). That is, a change in magnification occurs along the upper and lower Z-axis directions. In other words, the pixel rate (μm / pixel) which is the size per pixel of the camera on the surface to be imaged differs.

  This pixel rate can be an average value (the one-dot chain line in FIG. 6) with respect to the Z-axis direction. However, since there are actually parts of various heights, the actual pixel rate (solid line in FIG. 4) is There is a case where the value is far from the average value. In this case, since the actual pixel rate is different from the pixel rate used for the calculation, an error occurs in the measurement. When determining the suction state of a component, this error may cause a component shape determination error.

  Therefore, in a preferred embodiment of the present invention, the actual pixel rate (solid line in FIG. 6) is obtained by imaging the part normally sucked by the suction nozzle in advance by the side imaging means, and this is obtained in the pixel rate storage means. Remember. In actual imaging, the image correction unit corrects the image data of the component imaged by the side imaging unit using the pixel rate stored in the pixel rate storage unit. Thereby, it is possible to more accurately determine the quality of the component suction state. In addition, although the continuous line of FIG. 6 is a straight line, it is not necessarily a straight line.

  7A and 7B are perspective views showing an embodiment of the mounting apparatus according to the present invention, in which FIG. 7A shows the configuration of the main part thereof, and FIG. 7B shows the configuration in the vicinity of the nozzle holding member.

  The suction nozzle 1 that sucks an electronic component is provided on the nozzle holding member 2 so as to be movable in the vertical direction. In this embodiment, a plurality of suction nozzles 1 are provided on the lower surface portion of the nozzle holding member 2 along the circumferential direction. The nozzle holding member 2 is movable along an X-direction guide rail 3 and a Y-direction guide rail 4 provided on the apparatus main body, and is movable in the XY direction within a horizontal plane. That is, in the mounting apparatus shown in FIG. 7, the nozzle holding member 2 is relatively displaced in the horizontal plane with respect to the base 6 on which the printed circuit board 5 is placed, and the suction nozzle 1 moves in the vertical direction. The electronic component attracted to 1 is mounted on the printed circuit board 5.

  As shown in FIG. 7B, the side imaging means 7 is fixed to the nozzle holding member 2. The side imaging means 7 images the tip of the suction nozzle 1 from the side. In the present embodiment, a plurality of suction nozzles 1 are provided on the nozzle holding member 2, but these are provided so as to be able to rotate in a horizontal plane. The part can be imaged.

  FIG. 8 is a cross-sectional view showing a configuration example of the side imaging means 7. The side imaging means 7 shown in FIG. 8 includes a CCD sensor 7a, an illumination 7b made of LEDs, and a lens 7c and a reflection mirror 7d as an optical system. The illumination light from the illumination 7b reflected by the tip portion of the suction nozzle 1 that sucks the component B is reflected by the reflection mirror 7d, and then reaches the CCD sensor 7a via the lens 7c and is recognized as an image. In the mounting apparatus of the present invention, as described above, the side imaging means 7 has an optical axis of the optical system that is not horizontal with respect to the suction surface of the suction nozzle 1 that sucks the component B, and is a predetermined angle from above. The component B is imaged so as to form θ. In the present embodiment, the tilt angle θ of the optical axis of the optical system is set to 7 degrees by tilting the reflecting mirror 7d by 3.5 degrees from the horizontal.

A suction nozzle B component C printed circuit board D optical system of the side imaging means E focal plane of the optical system 1 suction nozzle 2 nozzle holding member 3, 4 guide rail 5 printed circuit board 6 base 7 side imaging means 7a CCD sensor 7b illumination 7c Lens (optical system)
7d Reflection mirror (optical system)

Claims (3)

An adsorption nozzle for adsorbing electronic components is provided on the nozzle holding member so as to be movable in the vertical direction. The nozzle holding member is relatively displaced in a horizontal plane with respect to a base on which the printed circuit board is placed, and the adsorption nozzle is in the vertical direction. An electronic component mounting machine configured to mount the electronic component sucked by the suction nozzle on the printed circuit board by moving to
The tip portion of the suction nozzle can be imaged from the side, and the optical system includes a side imaging means fixed to the nozzle holding member,
The side image pickup device picks up an image of an electronic component so that the optical axis of the optical system is not horizontal with respect to the suction surface of the suction nozzle but forms a predetermined angle from above.   The electronic component mounting apparatus according to claim 1, wherein an optical axis of an optical system of the side imaging unit forms an angle of 4 degrees or more and 40 degrees or less upward from a horizontal plane that is a suction surface of the suction nozzle. Pixel rate storage means for storing a pixel rate obtained by imaging the electronic component normally sucked by the suction nozzle in advance by the side imaging means;
3. The electronic component mounting according to claim 1, further comprising: an image correction unit that corrects image data of the electronic component imaged by the side imaging unit using the pixel rate stored in the pixel rate storage unit. apparatus.

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