JP2004235671A - Electronic component mounting device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electronic component mounting device in which the mounting cycle time for an electronic component requiring a three-dimensional shape inspection is shortened at mounting. <P>SOLUTION: The electronic component mounting device comprises a tray supply part 4 for supplying an electronic component 2 to be mounted, an x-axis robot 5 and a y-axis robot 6 for moving the electronic component 2 to be mounted, a head part 7 for holding/moving the electronic component 2, a three-dimensional sensor 8, and an image memory for storing height data as three-dimensional image data. Positioning for the electronic component 2 and three-dimensional component shape inspection can be performed at the same time in one process. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

  The present invention relates to an electronic component mounting apparatus that automatically mounts electronic components on a printed circuit board, a liquid crystal display, a plasma display panel substrate, or the like.

  2. Description of the Related Art Conventionally, when mounting electronic components such as QFPs and connectors having a narrow lead pitch and a narrow lead width in an electronic component mounting apparatus, it is necessary to automatically inspect lead floating of the components before mounting them on a printed circuit board. General.

FIG. 9 is a mounting process diagram of a conventional electronic component mounting apparatus. Many conventional electronic component mounting apparatuses mount an electronic component having a narrow lead pitch through a series of processes as shown in FIG.
That is, in the process shown in FIG. 9A, the electronic component 2 stored in the tray 3 is picked up by the head unit 7 of the mounting apparatus. In the step shown in FIG. 9B, an image of the sucked electronic component 2 is picked up by the positioning camera 47 and is positioned by using the image processing device to obtain the positioning information.

  In the step shown in FIG. 9C, using the positioning information obtained in the step of FIG. 9B, the electronic component 2 is inspected for lead floating by the transmission type lead floating sensor 48, or the lead floating inspection is performed. The leading end of the lead or the shadow of the leading end is imaged by the camera 49, and the lead floating inspection is performed by the image processing apparatus.

If there is no abnormality in the inspection result, the correction calculation of the printed circuit board 9 and the mounted electronic component 2 is performed in the step shown in FIG. 9D based on the positioning information obtained in the step of FIG. 9B. Then, the electronic component 2 is mounted at a predetermined position on the printed circuit board 9.
JP-A-04-105341 JP-A-07-193398

  However, in the above-described conventional electronic component mounting apparatus, when components are mounted through a series of processes performed according to the process illustrated in FIG. 9, the positioning camera 47 in the process illustrated in FIG. The lead floating sensor 48 and the lead floating inspection camera 49 in the step shown in FIG. 9C are physically set apart from each other, and the positioning information obtained in the step shown in FIG. Since it is necessary to mechanically position components in the process shown in (c), the processes in each process cannot be parallelized, and are necessarily serial processes, and the mounted components are moved for each process.・ Operations such as stop and vertical movement are required.

  Therefore, as a result, the processing time of the steps shown in FIGS. 9B and 9C, including the operation time such as movement, stop, and vertical movement of the mounted component, directly benefits the entire mounting time. Therefore, there is a problem that the total mounting time is increased by the operation time.

  In addition, as shown in the step shown in FIG. 9C, when the lead floating is inspected by the transmission type lead floating sensor 48, it is necessary to individually scan four sides of the physically mounted component. The processing time is usually about 1 to 3 seconds. This processing time is a factor that increases the mounting time of such components. This is a significant disadvantage particularly when a large number of QFPs and connectors are mounted.

  On the other hand, in the case where the lead floating inspection is performed using the lead floating inspection camera 49, the lead floating inspection takes a long time in the same manner as described above due to the focusing of the camera and the capture of divided images due to lack of resolution. Required, and the problem of mounting tact time also occurs.

  The present invention has been made in view of the above problems, and can reduce a mounting tact time when mounting a component that requires a three-dimensional shape inspection such as lead floating inspection. Can guarantee the pixel size (resolution) in both horizontal and vertical directions, and when mounting narrow-pitch components such as QFPs and connectors, speed up the mounting and increase the resolution (higher accuracy). It is an object of the present invention to provide an electronic component mounting apparatus capable of flexibly responding.

  The electronic component mounting apparatus according to the present invention includes a control unit that performs image processing on three-dimensional image data of the electronic component, and the control unit is arranged so that the control unit is perpendicular to the moving direction of the electronic component moving on the three-dimensional image capturing unit. The three-dimensional image of the electronic component obtained by the laser beam scanning in the direction is taken into the image memory, and the operating speed of the moving device for moving the electronic component is configured to be constant. Can reduce the mounting tact time when mounting components that need to be inspected for 3D shapes, etc., and guarantee both horizontal and vertical pixel sizes (resolution) for captured images when mounting components In addition, when mounting narrow-pitch components such as QFPs and connectors, it is possible to flexibly respond to high-speed and high-resolution (high-precision) mounting. .

  As described above, according to the present invention, a height image is captured by using the three-dimensional image capturing means, and image processing is performed on the three-dimensional image captured by the three-dimensional image capturing means. Thus, the positioning of the electronic component to be mounted and the three-dimensional component shape inspection represented by the lead floating inspection can be performed simultaneously.

  For this reason, it is possible to reduce the mounting tact time when mounting a component requiring a three-dimensional shape inspection such as a lead floating inspection. In addition, the operation speed of a head moving device (for example, an x-axis or y-axis robot) for moving the head is kept constant, and during the mounting operation before and after this, the movement of the components is not stopped, and the two-axis basically asynchronous. (For example, a driving axis and a polygon motor axis along the moving direction of the moving device) are mechanically operated to capture a three-dimensional image by the three-dimensional image capturing means, so that the pixel size (resolution) in both the horizontal and vertical directions is reduced. The system can be guaranteed.

  Therefore, the pixel size (resolution) in both the horizontal and vertical directions with respect to the captured image at the time of component mounting can be guaranteed. In addition, when mounting a narrow pitch component such as a QFP or a connector, a high-resolution image is captured in a captured image of the mounted component, while when mounting a component that can be measured with a somewhat coarse resolution, the mounting is performed. In the captured image of the component, the resolution can be reduced while maintaining the normality of the pixel (compared to the case where the resolution is increased), and the image can be captured by fast scanning.

  Therefore, when mounting a narrow-pitch component such as a QFP or a connector, it is possible to flexibly cope with high-speed and high-resolution (high-precision) mounting.

  The electronic component mounting apparatus according to claim 1 of the present invention, a component supply unit that supplies an electronic component to be mounted on a substrate, and holds the electronic component supplied to the component supply unit and mounts the electronic component on the substrate. A head unit for moving the electronic component held by the head unit onto the substrate; and projecting a laser beam onto the electronic component held by the head unit to move the head unit. A three-dimensional image capturing unit that obtains height data of the electronic component by scanning the entire surface of the electronic component by moving the electronic component by a device and performing line scanning by the laser light; An image memory for storing height data as three-dimensional image data, and a control unit for performing image processing on the three-dimensional image data are provided.

  According to this configuration, the three-dimensional image of the mounted component is captured by the three-dimensional image capturing unit, and image processing is performed on the three-dimensional image, so that positioning of the electronic component and inspection of the three-dimensional component shape are performed simultaneously. Make it possible.

  This is because, in the prior art, as shown in FIG. 9, the positioning by the camera and the three-dimensional shape inspection such as the lead floating inspection are serial (separate processes) processing. This enables simultaneous processing of three-dimensional inspection, and as a result, leads to a significant reduction in component mounting time. Here, the difference between the present invention and the prior art shown in FIG. 9 will be briefly described with reference to FIG.

  In FIG. 10, reference numeral 2 denotes an electronic component to be mounted, 3 denotes a tray on which the electronic component 2 is placed, 7 denotes a head for moving the electronic component 2, and 8 denotes a three-dimensional image capturing means for capturing a three-dimensional image. The dimension sensor 9 is a printed circuit board on which the electronic component 2 is mounted.

  In the step shown in FIG. 10A, the electronic component 2 is picked up (adsorbed) from the tray 3 by the head unit 7. In the step shown in FIG. 10B, when the electronic component 2 moves on the three-dimensional sensor 8 as the head unit 7 moves, the moving operation and the scanning by the laser light 8a emitted from the three-dimensional sensor 8 are performed. The three-dimensional image of the bottom surface portion 2a of the electronic component 2 being sucked and moved is taken into an image memory M1 in the image processing device G1, and the image is processed to perform positioning and three-dimensional shape inspection of the electronic component 2. And do both. In the step shown in FIG. 10C, the electronic component 2 is mounted on the printed circuit board 9 based on the positioning information obtained by the image processing of the image processing device G1.

  According to a second aspect of the present invention, in the electronic component mounting apparatus according to the first aspect, the laser beam is scanned in a direction perpendicular to the movement of the electronic component, and the moving speed of the electronic component is kept constant. It is characterized by having done.

  According to a third aspect of the present invention, in the electronic component mounting apparatus according to the first or second aspect, the control unit performs a component shape inspection of the electronic component by the image processing and performs positioning of the electronic component. It is characterized by the following.

Hereinafter, embodiments of the present invention will be specifically described with reference to the drawings.
FIG. 1 shows an electronic component mounting apparatus according to an embodiment of the present invention. In FIG. 1, reference numeral 1 denotes a mounting apparatus main body of an electronic component mounting apparatus, 2 denotes an electronic component (hereinafter abbreviated as a component) mounted by the present apparatus, 3 denotes a tray on which the component 2 is mounted, and 4 denotes a tray mounted on the tray 3. A tray supply unit as a component supply unit for automatically supplying the component 2, a head unit 7 for sucking and mounting the component 2 during mounting, and a moving unit 5 for moving the head unit 7 in the x-axis direction. The robots on the x-axis (hereinafter abbreviated as x-axis robots), 6a and 6b, which constitute the unit, move the head unit 7 together with the x-axis robot 5 in the y-axis direction. Is a three-dimensional (hereinafter abbreviated as 3D) sensor, and picks up a height image of the component 2. 9 is a printed circuit board on which the component 2 is mounted.

  When the component 2 placed on the tray 3 is sucked by the head unit 7 and moves on the 3D sensor 8 along the x-axis robot 5, a 3D (height) image of the component 2 is captured by the 3D sensor 8. The (height) image obtained by the 3D sensor 8 is subjected to software processing to perform 3D shape inspection such as positioning of the component 2 and floating of the lead, and the component 2 is positioned at a predetermined position on the printed circuit board 9 according to the positioning information. Be attached.

  FIG. 2 illustrates the capture of a three-dimensional image. In FIG. 2, reference numeral 2 denotes a component moving by the operation of the x-axis robot 5, reference numeral 8 denotes a three-dimensional sensor, reference numeral 44 denotes a laser beam scanned by a polygon mirror, and reference numeral 45 denotes one of the leads of the component 2; Leads 46 that are bent (floating) on the opposite side are height data when the lead 45 is imaged by the 3D sensor 8.

  FIGS. 2A to 2C show that the component 2 is moved on the 3D sensor 8, the laser beam 44 is scanned in a direction perpendicular to the movement of the component 2, and the laser beam 44 is projected on the bottom surface of the component 2. The reflection of the laser light 44 is imaged on the semiconductor position detecting element, and the height of the output of the semiconductor position detecting element is sequentially calculated, whereby the three-dimensional image of the component 2 is taken into the image memory 35. It shows the situation.

  Data taken in each horizontal row of the image memory 35 is obtained from the 3D sensor 8 side of an object (in this case, a lead of the component 2 or a package portion) on each of the laser scanning lines whose height has been calculated by the above method. The height data is as shown in the XY sectional view.

  FIGS. 2D to 2F show the state of the image memory 35 when the component 2 has finished passing over the 3D sensor 8. In particular, if the lead 45 is floating, ZW In the sectional view, the height data 46 corresponding to the lead 45 has a larger value than those of the other leads. By this data comparison, a three-dimensional shape inspection such as a lead floating inspection of a lead becomes possible.

  Since image data of the two-dimensional component 2 is input to the image memory 35, if this information is subjected to image processing, there is a difference between luminance data and height data. The parts can be positioned in the same manner as in image processing.

  FIG. 3 shows the mounting operation. In FIG. 3A, the trajectory represented by each arrow from point A to point B, point B to point C, and point C to point D indicates that the electronic component mounting apparatus of the present embodiment The 3D sensor 8 picks up and passes over the 3D sensor 8, captures a three-dimensional image of the component 2, and processes the image data to perform component positioning / inspection and calculate the mounting position correction. 3 shows a series of operations for mounting the component 2 at a required position on the printed circuit board 9.

  FIGS. 3B and 3C show changes in acceleration and deceleration of the movement of the robot in the x-axis direction and the y-axis direction corresponding to the locus of the part 2 shown in FIG. 3A at this time. It represents. Here, the part 2 passes over the 3D sensor 8 during the movement in the x-axis direction between the point B and the point C, where a three-dimensional image is captured. Is constant, and the y-axis robot is stopped.

  For the remaining operations, in order to minimize the total mounting time, the operation between points A and B is changed to the operation between points B and C, and the operation between points B and C is changed to points C and C. Acceleration / deceleration operations involving a temporary stop at the speed switching point, which is an operation during D, are eliminated, and the speed of the machine mounting operation is increased.

  The configuration and operation of the 3D sensor 8 will be described in detail below. FIG. 4 is a view of the 3D sensor 8 viewed in the x-axis direction, and FIG. 5 is a view of the 3D sensor 8 viewed in the y-axis direction. 4 and 5, reference numeral 10 denotes a semiconductor laser that emits laser light, 11 denotes a condensing / shaping lens that condenses / shapes the laser light, and 12 denotes a polygon mirror that scans the laser light hitting the mirror surface by mechanical rotation. , 13 are half mirrors that allow a part of the laser light to pass and partially reflect the laser light, and 14 is a mirror that reflects the light.

  Reference numeral 15 denotes an F-θ lens for converting the optical path of the laser light mechanically shaken by the polygon mirror 12 so that the laser light is projected perpendicularly onto the component 2 which is a subject, and 16a and 16b reflect (scatter) the laser light impinging on the component 2. The imaging lens 17a, 17b is a semiconductor position detection element (hereinafter, referred to as PSD) as a position detection element in which reflected light of laser light hitting the component 2 is imaged through the imaging lenses 16a, 16b. Abbreviated) and has a function of generating an electric signal correlated with the position of the imaged light. 18a and 18b are output signals of the PSDs 17a and 17b.

  Here, the laser light emitted by the semiconductor laser 10 is condensed and shaped by a condensing and shaping lens 11, passes through a half mirror 13, reflects off a mirror 14, and impinges on a polygon mirror 12. The polygon mirror 12 is rotating at a constant speed, and the laser light hitting the mirror surface is swung. Further, the laser light whose optical path has been converted by the F-θ lens 15 is applied vertically to the component 2, and the reflected light is imaged on the PSDs 17 a and 17 b via the imaging lenses 16 a and 16 b, and the PSDs 17 a and 17 b are Output signals 18a and 18b capable of measuring the height of the laser reflecting surface of the laser beam.

  In FIG. 5, reference numeral 19 denotes an optical sensor for detecting that light has been input, and reference numeral 20 denotes a signal for notifying that light has been input to the optical sensor 19. When the angle of the polygon mirror 12 is reached, it corresponds to the origin signal of each surface of the polygon mirror 12 (surface origin). Further, for example, in the case of the polygon mirror 12 having 18 planes, the signal is output 18 times per rotation when rotated by an angle of equal intervals (every 20 degrees in the case of 18 planes). This is called a rotation amount signal of the polygon mirror 12.

  The 3D sensor 8 in the present embodiment has two PSD circuits. However, in one system, when a laser beam hits a component, reflected light may not return to the PSD in an angle when the laser beam hits a component. Therefore, the main purpose is to supplement this. In some cases, it is more effective to provide three or more systems, but it is technically the same, and here, two systems will be described.

  Here, an example of the method of measuring the height above the component 2 which is the measurement target by the semiconductor position detecting elements (PSDs) 17a and 17b is shown in FIG. It will be described based on the following.

In FIG. 11, a laser beam that is scanned from the F-θ lens 15 in the direction perpendicular to the paper and projected onto the component 2 is irregularly reflected from the component 2. In this case, the point projected is assumed to be a and B ₁ point height H A ₁ point height 0 on the bottom surface of the component 2 from the bottom surface.

Irregularly reflected laser beam is condensed by the imaging lens 16a, each of which forms an image on the _two-point and B ₂ points A on the semiconductor position sensitive device 17a. As a result, electromotive force is generated in a _{two-point two} points _A and _B, the current _I 3, _{I 4} is taken out from the current _{I 1, I} 2, D points from each point C.

Current _I 1, _{I 3} is determined by the resistance component proportional to the distance between the distance _{x A} and _{A 2} points and point D between the point A2 and point C, current _I 2, _{I 4} is _{B 2} since determined by resistance components in proportion to the distance between the distance x _B and B ₂ points and point D between the point and the point C, and the length of the semiconductor position sensitive device 17a and L, x in FIG. 11 _{a, x B} is determined as follows.

x _A = LI ₃ / (I ₁ + I ₃ )
_{x B = LI 4 / (I} 2 + I 4)
Accordingly, the distance H between the _two points and the B ₂ points A in on the semiconductor position sensitive device 17a of FIG. 11 'is determined by the following equation.

H _'= x A -x _B
The height H is determined based on the height H ′ above the PSD thus obtained.
Next, a mechanism for capturing a 3D image will be described with reference to FIGS. 6, reference numeral 21 denotes a main control unit of the electronic component mounting apparatus; 22, a reference position sensor for notifying the main control unit 21 of a reference position for capturing a 3D image on the x-axis robot 5; A reference position signal notifying the main control unit 21 when the signal passes through the reference position sensor 22, an encoder 24 of a motor for moving the x-axis robot 5, and an encoder signal 25 output from the encoder 24.

  When the component 2 picked up from the tray 3 moves on the x-axis by the x-axis robot 5, the encoder 24 always supplies an encoder signal (AB phase, Z phase or a signal equivalent thereto) 25 to the main control unit 21. When the component 2 passes through the reference position sensor 22, the reference position signal 23 is given to the main control unit 21, and the relative position of the component 2 from the reference position on the x-axis is mainly used by these two signals. The control unit 21 can calculate.

  On the other hand, the rotation amount of the polygon mirror 12 in the 3D sensor 8 is always given to the main control unit 21 as the rotation amount signal 20 while the polygon mirror 12 is rotating. The rotation amount after passing the reference position can be calculated.

  Here, the amount of rotation of the polygon mirror 12 increases in proportion to its speed, and the same can be said for the amount of movement of the x-axis robot 5. On the other hand, in the 3D sensor 8 according to the present embodiment, it is assumed that the polygon mirror 12 and the x-axis robot 5 at the time of capturing a 3D image rotate and go straight at a constant speed, respectively. If this condition is disturbed, the resolution (pixel size) per pixel in the horizontal and vertical directions of the captured 3D image varies according to the speed unevenness. This is an error factor in measurement accuracy. Therefore, in the electronic component mounting apparatus according to the present embodiment, the 3D sensor 8 having the above-described configuration captures a 3D image into the image memory 35 in the main control unit 21, and the polygon mirror 12 that basically rotates at a constant speed. In order to monitor and control the operation consistency between the head units 7 driven by a motor such as a servo motor, the rotation amount signal 20 of the polygon mirror 12 and the encoder signal 25 of the motor are used.

  In FIG. 7, reference numeral 26 denotes a movement amount detection circuit which receives the encoder signal 25 and calculates the movement amount (distance) of the x-axis robot 5 from the reference position, and 27 denotes each time of the x-axis robot 5 receiving the encoder signal 25. A rotation speed detection circuit that calculates the rotation speed of the x-axis robot 5 from the reference position by receiving a rotation amount signal 20 of the polygon mirror 12; A rotation speed detection circuit for calculating the rotation speed of the polygon mirror 12 at each time upon receipt, a first comparison circuit 30 for comparing the movement of the x-axis robot with the movement of the polygon mirror, and a reference numeral 31 for the x-axis robot A second comparison circuit for comparing the operation of the polygon mirror with the movement speed between the rotations of the polygon mirror; 32 and 33, storage circuits for storing the comparison results of the comparison circuits 30 and 31; A processor circuit for controlling and monitoring the whole; 35, an image memory for capturing and storing 3D images (height images); 36, for capturing PSD outputs 18a, 18b sent from the 3D sensor 8 into the image memory 35; A timing generating circuit for generating various timing signals; 37, an interface circuit for receiving the PSD outputs 18a, 18b by the main control unit 21; 38, a height calculating circuit for converting and correcting the PSD outputs 18a, 18b into height signals It is.

  The PSD outputs 18a and 18b generated by the 3D sensor 8 are input to the main control unit 21 by the interface circuit 37. The input PSD outputs 18a and 18b are basically the original signals output by the PSDs 17a and 17b. In order to perform software-based processing on the height image, various types of operations such as height conversion and correction calculations are performed. The operation needs to be performed on the PSD outputs 18a and 18b, and this is performed by the height operation circuit 38. The signal calculated by the height calculation circuit 38 is taken into the image memory 35 as height data, and subjected to various software processes by the processor circuit 34.

  The height data is taken into the image memory 35 sequentially for each horizontal row of the image memory 35, but the rotation amount signal 20 of the polygon mirror 12 is used as a synchronization signal (reference signal) for each polygon surface. is there.

  In such a series of imaging operations, the operation of the x-axis robot 5 (i.e., the movement of the imaging target component) and the operation of the polygon mirror 12 are performed independently. The speed is calculated by a movement amount detection circuit 26 and a movement speed detection circuit 27, and the rotation amount / rotation speed of the polygon mirror 12 is determined based on the rotation amount signal 20 of the polygon mirror 12 by a rotation amount detection circuit 28 and a rotation speed detection circuit 29. The moving amounts and the moving speeds of the x-axis robot 5 and the polygon mirror 12 are compared by the comparison circuits 30 and 31, and the comparison results are stored in the storage circuits 32 and 33. It monitors or controls the synchronous operation of both the movement and the rotation of the polygon mirror 12.

  As an example of monitoring, if the difference between the comparison circuits 30 and 31 is within the allowable range as a result of the comparison, the data recorded in the image memory is treated as valid data while the difference is within the allowable range. If the data is outside the range, the data is invalidated. If the comparison error is larger than a certain value, it is determined that the image is defective, and the image is retaken, or the 3D image in the image memory 35 is added by software or by referring to the comparison result. Normalization and correction processing can be considered by providing a circuit.

  Here, an example of converting the rotation amount of the polygon mirror 12 into the movement amount will be described. Now, it is assumed that the polygon mirror 12 is a dodecahedron, and the component 2 is designed to move by 40 μm while the polygon mirror 12 rotates by 30 ° (= 360 ° ÷ 12). At this time, assuming that the rotation amount of the polygon mirror 12 after the start of image capturing is 125.5 rotations, the component 2 has only 125.5 (rotation) × 12 (plane / rotation) × 40 (μm) = 60240 (μm) You are moving.

  In order to realize this in a circuit, the number of pulses of the rotation amount signal 20 from the polygon mirror 12 (the number of signals from the plane origin which is the reference point of each plane of the polygon mirror 12) is counted during image capture. Good. In the above example, when the rotation is 125.5, the surface origin is counted by 125.5 (rotation) × 12 (the number of surface origins) = 1506.

Therefore, when the number of pulses of the rotation amount signal 20 becomes 1506, it can be considered that the component 2 has moved by 40 μm, and the rotation amount of the polygon mirror 12 can be converted into the movement amount.
FIG. 8 is a diagram showing the internal configuration of the height calculation circuit 38. Reference numeral 41 denotes an A / D conversion circuit for performing A / D conversion of the PSD outputs 18a and 18b; 42, a clock generation circuit; A clock selection circuit as a clock speed changing means for selecting one of a plurality of clocks to be supplied to the A / D conversion circuit 41 and the image memory 35 at one speed (frequency), 44 is a PSD output 18a, A height conversion circuit for calculating the position of light to be imaged on the surfaces of the PSDs 17a and 17b and a position of a laser beam which strikes the object to be measured. Here, two or more kinds of clocks generated by the clock generation circuit 42 are selected by the clock selection circuit 43 and the main control unit The selected clock is supplied to a required circuit such as the A / D conversion circuit 41 or the image memory 35 which requires this signal within 1, and at the same time, the operating speed of the x-axis robot is inversely proportional to the speed of this clock. Acceleration / deceleration makes it possible to change the resolution while keeping the horizontal and vertical pixel sizes of the captured image (3D image) equal without adding a special circuit.

  For example, assume that A / D conversion is performed at 4 MHz, and when the x-axis robot 5 is moved at 100 mm / s, the pixel size in the horizontal and vertical directions is equal to 50 μm. At this time, if an 8 MHz clock is selected and given to each required circuit and the x-axis robot is moved at 50 mm / s, the pixel size (resolution) of the captured image can be 25 μm pixels.

  At this time, the data amount per row (horizontal row) is doubled, and the same can be said for the vertical direction. Therefore, in order to obtain an image with double resolution for the same visual field size, the capacity of the image memory 35 is quadrupled. In this regard, the user has a choice of selecting to increase the capacity of the image memory 35 or limiting the size of the field of view when improving the resolution.

  Next, the relationship between the image capturing by the main control unit 21 and each signal in the image processing operation will be described with reference to FIGS. 7 and 8 and FIGS. 12 and 13. The motor is built in the x-axis robot 5 that moves the head unit 7 that sucks the component 2, and an AB-phase signal indicating a normal movement distance from an encoder added to the motor and a fixed position ( And a Z-phase signal representing a certain rotation angle of the motor).

  When both the Z-phase signal and a position detection sensor signal from a position detection sensor (a photosensor or a Hall element is used as the sensor) for detecting the reference position are received, image data capturing operation is performed. Be started.

  Since the time from when both the Z-phase signal and the position detection sensor signal are received until the start of the image data capture is very short, the polygon mirror 12 receives the two types of signals and receives the two types of signals as shown in FIG. In synchronization with the rotation amount signal indicating the plane origin, the timing generation circuit sets the image data acquisition timing so that a series of operations of laser emission and image data acquisition are performed automatically by hardware without going through the processor circuit. Output.

  With this output, for example, image data for 1000 lines is captured. In this way, the point in time when the rotation amount signal 20 is captured is treated as a reference position (surface origin) of each surface of the polygon mirror 12, and is used as a reference for starting the capture of image data. Then, for example, when 1000 lines of image data are fetched per component, when 1000 lines of image data are fetched, the image fetching for the component is automatically terminated.

  As described above, two analog signals are input from the PSD outputs 18a and 18b, and are amplified by the amplifier circuit 202 as shown in FIG. The A / D conversion is performed by the A / D conversion circuit 41 of the arithmetic circuit 38. Thereafter, the height calculation described above is performed based on each of the two digitized signals of the PSD outputs 18a and 18b to calculate the height position of the lead. Here, if the value of the digitized signal is within the allowable range, the subsequent processing is performed as normal data. If the value is out of the allowable range, the subsequent processing is stopped as abnormal data. That is, if the value of one of the two PSD outputs 18a and 18b is within the allowable range, only the PSD output within the allowable range is used. take. If the values of both outputs are out of the allowable range, the subsequent processing for both PSD outputs is not performed, and processing is performed assuming that an error has occurred.

  After calculating the lead height data in this manner, the height correction circuit 45 performs height correction. This height correction is performed because the position on the PSDs 17a and 17b does not change linearly even if the position of the incident light with respect to the PSDs 17a and 17b changes linearly. The calculated height data is stored and corrected to obtain accurate height data.

  The height data corrected in height is input to the image memory circuit 35, and the timing obtained from the timing generation circuit 36 is stored as an address. Then, from the data stored in the storage circuit 32 as a result of the comparison between the rotation amount detection circuit 28 and the movement amount detection circuit 26 by the comparison circuit 30, it is determined whether or not the image data is within the allowable range. If it is out of the allowable range, the image data stored in the image memory circuit 35 is treated as invalid. If it is within the allowable range, the data stored in the image memory circuit 35 is read from the processor circuit 34 and image processing such as positioning of components is performed.

  Hereinafter, an example of the flow of the image capturing operation for the one component 2 and the processing operation of the captured image will be described in more detail with reference to FIG. First, in step # 60, an image of the component 2 is captured.

  Next, at step # 61, the positioning of the lead of the component 2 from which the image has been captured is performed. There are various methods (algorithms) for this positioning, but a representative one will be described here.

  First, as shown in FIG. 15A, the inclination of a lead on one side of a rectangular electronic component 2 such as a QFP is roughly detected. Next, as shown in FIG. 15B, the positions of two leads arbitrarily selected from the detected leads are roughly detected.

  Finally, as shown in FIG. 15C, the lead position is accurately detected based on the roughly detected lead position. If the position of the lead on one side of a quadrangular component such as QFP is detected in this way, the lead on the other side is determined based on this lead position as shown in FIG. What is necessary is just to detect a lead position accurately.

Next, it is determined at # 62 whether or not the lead pitch is appropriate. If it is appropriate, the height of each lead is calculated in step # 63 as described above. As shown in FIG. 17, the calculation of the height is based on the lead position information obtained in step # 61. For each lead, a plurality of pixels (in FIG. The lead height is obtained by averaging the height information (which is the data itself stored in the image memory) of each small square. The position of the leads obtained by the positioning information obtained by adding the lead heights _{(x i, y i, z} i) is the three-dimensional position of each lead. Here, i = 1,..., N, and n is the number of leads. Next, in step # 64, a virtual plane (seating plane) is calculated. Here, the virtual plane will be described.

  Generally, when a component having a plurality of leads such as a QFP is mounted on a board, a part of the leads may be separated from an electrode portion of the board, that is, a so-called lead floating state may occur. The process for detecting the floating of the lead of the component before mounting the component is the detection of the floating of the lead performed in step # 65. If this process is to be performed in a state where the component is sucked by the nozzle, FIG. Since there is a possibility that the component 2 is inclined and adsorbed to the nozzle 7a as shown in ()), simply determining the height of each point of the lead cannot accurately determine the floating of the lead. Therefore, it is necessary to obtain a virtual plane that becomes a ground plane when components are mounted, obtain a distance from the virtual plane to each lead, and evaluate the lead floating amount.

In FIG. 16A, reference numeral 201 denotes a reference plane, and reference numeral 200 denotes an error (H ₁ −H ₂ ) between the heights of the two leads due to the inclination generated in the component 2 due to the suction of the nozzle 7a.
The virtual plane 202 is a plane composed of three lead positions of the component 2, and a plane satisfying the following two conditions can be a constituent point of the virtual plane 202.

(1) As shown in FIG. 16 (b), all lead positions exist above or on the virtual plane 202.
(2) As shown in FIG. 16C, a point 203 where the center of gravity of the component 2 is projected on the virtual plane 202 (center-of-gravity projected point) 203 is within a triangle generated by three points of the lead positions constituting the virtual plane 202. To exist.

  Next, based on the height calculated in step # 63 and the virtual plane obtained in step # 64, it is determined in step # 65 whether the float of the lead is within an allowable range. The lifting of the leads is performed by calculating the distance from the three-dimensional position of the leads to the virtual plane determined for all the leads. This distance is the lead floating amount of each lead from the virtual plane, and if this value is within the allowable range, the image processing operation ends. If it is out of the allowable range, the image processing operation is terminated in step # 67 as a lead floating error. If the lead pitch is out of the allowable range in step # 62, the image processing operation ends as a pitch error in step # 66.

  Next, an example of a process for correcting a shift in image capture timing will be described. FIG. 12 is a diagram showing the relationship between the main controller 21 of FIG. 7 and each device. The detection circuits 26 to 29, the comparison circuits 30, 31, the storage circuits 32, 33, and the processor circuit 34 are one polygon mirror. The control unit 200 is shown. FIG. 13 is a timing chart showing the image capture timing.

  12 and 13, when the component 2 is located at a specific position according to the movement of the head unit 7, the three-dimensional sensor 8 outputs the position detection sensor signal, and is constant at one of the encoder outputs of the motor for moving the component. At the timing when the Z phase comes out to guarantee the position, the polygon mirror control unit 200 starts a preparation operation for capturing image data.

  After the preparation operation is started, the actual image data is taken in line by line in synchronization with the operation of detecting the plane origin of the polygon mirror 12. That is, when the rotation amount signal 20 indicating the surface origin of the polygon mirror 12 is detected and the laser light of the semiconductor laser 10 is emitted, the image is taken in at the same time.

  At this time, as shown in FIG. 13, there is a time lag from when the head unit 7 is positioned at the image data capture start position to when the image data capture operation is actually started. Since the operation of the head unit 7 and the operation of the polygon mirror 12 are asynchronous, the time lag is determined by an amount t by which the component 2 moves until image capturing and a fixed time “preparation period” due to circuit setup. This is due to the delay.

  After the time lag, an image for one frame is captured in synchronization with the polygon mirror 12. Accordingly, the distance that the component 2 moves during the time from when the component 2 is located at the image capturing start position of the three-dimensional sensor 8 to when the polygon mirror 12 of the three-dimensional sensor 8 is located at the scanning start position is determined by moving the component. The encoder output (AB phase) of the motor being driven is counted and obtained in a circuit by a counting circuit 300 and output to the processing circuit 34. If the positioning of the component 2 is performed based on the result, it is possible to prevent a decrease in the positioning accuracy due to a variation in the timing shift, and to perform the positioning with higher accuracy.

  In the above embodiment, the case where the head unit 7 sucks one electronic component 2 with one suction nozzle has been described. However, the present invention can be applied to a case where the head unit 7 has a plurality of nozzles. In addition, when continuously performing positioning and component shape inspection in a state where a plurality of components are sucked by a plurality of nozzles as described above, for example, when it is assumed that image data of 1000 lines per component is taken, four The nozzle fetches 4000 lines of image data and handles it as image data of one component every 1000 lines.

  The time required for component positioning and three-dimensional shape inspection in the tact time is extremely large. However, according to the present invention, when a plurality of components are successively captured by a 3D sensor with a plurality of nozzles and a three-dimensional image is successively mounted, the time required for component movement from the removal of the component to the mounting target board is one. Regardless of whether it is a single component of a nozzle or a multiple component of a plurality of nozzles, it is substantially constant, and is particularly effective in reducing the tact time.

  Further, in the head unit 7 having a plurality of nozzles as described above, the image processing order can be appropriately changed in consideration of the mounting order of the electronic components 2 as shown in FIG. That is, for example, four nozzles (No. 1 to No. 4) suck the part 2 in this order and take in the image data into the image memory circuit 35, 4-No. When four nozzles are mounted on the board in the order of 1, every time image data of each component is captured, image processing of the captured image data is prioritized over image processing of image data of other components. It is also possible to judge whether or not to perform the process, and to prioritize the image processing of the component to be given the highest priority.

  In such a case, since the image processing is performed in the order of earliest mounting, if image processing is completed, mounting can be performed even during image processing of another component. Further, as is apparent from the above description, in order to increase the resolution, it is necessary to reduce the speed of the x-axis robot 5 at the same time as improving the clock speed.

  In any case, high resolution of the image is indispensable in order to respond to the narrow pitch of components such as QFPs and connectors. On the other hand, for components that can be measured with a somewhat coarse resolution, we want to capture images with the fastest possible scanning become. In such a case, the means for increasing the resolution is very effective.

  In the above embodiment, the output of the encoder 24 is used to detect the relative position of the head unit 7 from the reference position on the x-axis robot 5, but the linear scale is directly applied to the x-axis robot 5. By doing so, the position of the head unit 7 can also be detected.

Overall schematic view of an electronic component mounting apparatus according to an embodiment of the present invention. Explanatory drawing of 3D image capture in the embodiment Explanatory drawing of the component mounting operation in the embodiment Configuration sectional view in the x-axis direction of the 3D sensor according to the embodiment. Configuration sectional view of the 3D sensor in the same embodiment in the y-axis direction Explanatory drawing of the output signal from the 3D sensor in the embodiment Internal configuration diagram of main control unit in the same embodiment Internal configuration diagram of height operation circuit in the same embodiment Mounting process diagram in conventional electronic component mounting equipment Mounting process diagram in the electronic component mounting apparatus according to the embodiment of the present invention Explanatory drawing which shows the example of the height measuring method in the said embodiment. Explanatory diagram showing the relationship between the main control unit and each device in the embodiment. FIG. 5 is a timing chart showing image capture timing in the embodiment. FIG. 4 is a flowchart showing an operation from image capture to image processing in the embodiment. Explanatory diagram showing an algorithm as an example regarding recognition of leads of electronic components Explanatory drawing about measurement of height of floating of lead of electronic component Illustration of height calculation of each lead of electronic component Timing chart of an embodiment in the case of performing image capture and image processing of a plurality of electronic components

Explanation of reference numerals

Reference Signs List 4 tray supply unit 5 x-axis robot 6a, 6b y-axis robot 7 head unit 8 three-dimensional sensor 10 semiconductor laser 12 polygon mirror 17a, 17b semiconductor position detection element (PSD)
16a, 16b Imaging lens 21 Main controller 26 Moving amount detecting circuit 27 Moving speed detecting circuit 28 Rotating amount detecting circuit 29 Rotating speed detecting circuit 30 First comparing circuit 31 Second comparing circuit 35 Image memory 43 Clock selecting circuit

Claims (3)

A component supply unit that supplies electronic components to be mounted on the board,
A head unit that holds the electronic component supplied to the component supply unit and mounts the electronic component on the substrate,
A head unit moving device that moves the electronic component held by the head unit onto the substrate,
The electronic component is projected by irradiating a laser beam onto the electronic component held by the head unit, and scanning the entire surface of the electronic component by moving the electronic component by the head unit moving device and line scanning by the laser beam. Three-dimensional image capturing means for obtaining height data of a part;
An image memory for storing the height data from the three-dimensional image capturing means as three-dimensional image data;
An electronic component mounting apparatus comprising: a control unit that performs image processing on the three-dimensional image data. 2. The electronic component mounting apparatus according to claim 1, wherein the laser light is scanned in a direction perpendicular to the movement of the electronic component, and the moving speed of the electronic component is made constant. The electronic component mounting apparatus according to claim 1, wherein the control unit is configured to perform a component shape inspection of the electronic component by the image processing and to perform positioning of the electronic component.

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