JP4750792B2 - Diagnostic tool for component feeder replacement - Google Patents

Description

  Pick and place devices are commonly used to manufacture electronic circuit boards. The blank printed circuit board is typically supplied to a pick and place device, which then picks up the electronic structural element from the component feeder and places the component on the circuit board. The component is temporarily held on the circuit by a soldering paste or adhesive, after which subsequent steps take place, the soldering paste melts or the adhesive completely cures.

  The operation of pick and place equipment has many challenges to address. Since the device speed corresponds to the throughput, the higher the operating speed of the pick and place device, the lower the cost of the manufactured circuit board. Furthermore, placement accuracy is extremely important. Many electrical components, such as chip capacitors and chip resistors, are relatively small and must be accurately placed in equally small placement locations. The other components are large but have a significant number of leads or conductors separated from each other by a relatively fine pitch. Such components must be accurately positioned to ensure that each of the leads is positioned on the proper pad. For this reason, not only must the device operate very quickly, but the device must mount the components very precisely.

  In order to improve the quality of circuit board manufacture, the fully or partially mounted substrate, both before and after solder reflow, should be inspected thoroughly to ensure that any components placed or inaccurately occur. Be able to identify any lost or any wide variety of errors. An automated system that performs such a process helps identify component place issues prior to solder reflow and allows or substantially requires rework after reflow. This is extremely useful in helping to identify bad circuit boards. An example of such a system is sold under the brand name KS Flex, available from CyberOptics Corporation, Golden Valley, Minnesota. This system is used to identify problems such as alignment and rotation errors, missing and inverted components, billboards, tombstones, component defects, inaccurate polarity and incorrect components can do. As a result of identifying errors before reflow, a number of advantages are obtained. That is, reworking is easy. Closed loop manufacturing control is facilitated. Less inter-process work exists between the occurrence of errors and the repair. Such a system allows very useful inspections, but takes up factory floor space and consumes programming time, maintenance effort and the like.

  One relatively recent attempt to be placed within the pick and place device itself to provide the beneficial effects of post-placement inspection is US Pat. No. 6,317 to Asai and others. 972. In this document, an image of the mounting position is obtained before placing the component, and after placing the component, it is compared with the image of the mounting position to inspect the placement process at the component level. A method of attaching electrical components has been reported.

  While the technology of component placement devices has advanced, such devices still require relatively much preparation and operator attention. Such an operation requires the placement device to be removed off-line, so that the product may not be manufactured during preparation or maintenance operations. Therefore, if the work time is shortened, the effective production amount of a predetermined apparatus can be remarkably improved. Pick and place devices require operations such as programming, changing conveyors, attaching workpieces and changing feeders. In particular, advances in printed circuit board design and assembly have led to changes towards high-mix, low-volume (HMLV) manufacturing that requires lines to be replaced more frequently.

  When all components are gone from a given component feeder, the feeder is generally replaced with a new feeder with a new supply of the same component. However, new feeders may have incorrect component values, incorrect component types, and incorrect polarity. Therefore, when such feeder replacement is required, a new feeder and / or components mounted from that feeder are carefully analyzed by technicians to ensure that the placement process can be resumed. There must be. The time required by this technician will be labor intensive while keeping the device offline. Therefore, it is important to minimize the time required to perform a feeder replacement of any given component.

  A method and apparatus is provided that facilitates confirmation of component feeder replacement in a pick and place device. A pre-replacement image of the component from the feeder is acquired and compared to the component image from the replaced feeder placed after the feeder is replaced. Comparing the image before replacement with the image after replacement facilitates a simple and quick confirmation of feeder replacement. Embodiments of the present invention can be implemented on different types of pick and place devices and can use information provided by sensors and / or technicians to automatically display confirmation of feeder replacement. Useful in that it can.

  1A and 1B are plan and top views, respectively, of a Cartesian coordinate pick and place device 150 in which embodiments of the present invention are particularly useful. While the description of FIGS. 1A and 1B is described with respect to a pick and place device 150, other forms of pick and place devices such as split gantry and / or turret design may be used.

  FIG. 1A is a plan view of the pick and place device 150. Pick and place device 150 receives a workpiece such as circuit board 157 via a transport system or conveyor 152. Next, the placement head 162 is configured to obtain one or more electrical components to be mounted on the workpiece 157 from the component feeder (shown in FIG. 1B) and move in the x, y, and z directions. Place the element in the proper orientation on the work piece 157 in the proper position. The placement head 162 can include a sensor 184 that can pass below the components held by the nozzles 210, 212 as the placement head 162 moves the components from the pick-up position to the placement position. The sensor 162 allows the placement device 150 to see the underside of the component held by the nozzles 210, 212 and also while the component moves from the component pick-up position to the placement position. Orientation and some inspection of components can be performed. Other pick and place devices can employ a placement head that moves over a stationary camera to obtain an image of the component. It is also preferred that a reference camera 165 looking down is mounted on the head 162 and arranged so that one or more images of the workpiece 157 can be obtained.

  As illustrated in FIG. 1B, the transport mechanism 152 includes an attachment portion 154 and a conveyor 156. The transport mechanism 152 is disposed on the base 158 and allows the workpiece to be conveyed to the attachment portion 154 by the conveyor 156. The feeder mechanism 160 is generally disposed on both sides of the transport mechanism 152 and supplies electronic components to the transport mechanism. The feeder 160 can be any suitable device adapted to provide electronic components. Each of the feeders 160 can provide different specific components to be placed. Replacing any of the feeders 160 is an undesirable task because, as described above, the entire device 150 needs to be taken offline. The manner in which embodiments of the present invention reduce this work time will become apparent later in this specification.

  The pick and place device 150 has a head 162 disposed above the base 158. The head 162 can move between either the feeder mechanism 160 and the attachment portion 154. As can be appreciated, the head support 164 is movable on the rail 166, thereby allowing the head 162 to move on the base 158 in the y direction. In response to the motor actuation signal, the motor 170 rotates a ball screw 172 that engages one of the head supports 164, thereby causing the head 162 to move in the y direction when the support 164 is displaced in the y direction. Arise. Head 162 is also supported on rail 168 to allow the head to move in the x direction relative to base 158. When the motor 174 rotates the ball screw 176 that engages the head 162 and displaces the head 162 in the x direction in response to the rotation signal of the motor, the head 162 moves in the x direction. Other pick and place designs can be used with the present invention, even devices that do not operate professionally in motion in the x and y directions.

  The head 162 includes a main body 178, a nozzle mount 180, a nozzle 182 and a sensor 184 as a whole. The nozzle mount 180 is disposed within the body 178 and attaches each of the nozzles 182 within the body 178. As used herein, “nozzle” is intended to mean any device capable of releasably holding a single component. Each of the nozzles 182 is movable in the z direction (up and down), the x direction, and the y direction, and can be rotated around the z axis by any appropriate actuating member such as a servo motor.

  From the above description, it is clear that modern pick and place devices include one or more imaging systems (such as reference camera 165 and / or component sensor 184).

  Recently, pick and place devices have realized the ability to inspect component placement by looking at predetermined placement positions immediately before and after the component placement process. FIG. 2 illustrates an example image acquisition device 300 that is arranged to acquire an image of the placement position 360 of the component 304 before the component 304 is positioned at the position 360 by the nozzle 210. ing. The apparatus 300 acquires an image of the placement position 360 on the workpiece 157 before and immediately after placing the component 304. Comparing these pre- and post-placement images facilitates component level placement inspection and validation. The acquisition of the placement position image is generally performed when a nozzle, such as nozzle 210, holds the component 304 above the placement position, so that the component itself or has already been attached to the workpiece. It is important to be able to acquire an image of the placement position 360 while minimizing or reducing interference from wax adjacent components. Thus, the apparatus 300 preferably employs an optical axis that allows an image tilted at an angle θ with respect to the plane of the workpiece 157.

  Embodiments of the present invention generally utilize an image acquisition device that currently exists in a pick and place device to facilitate replacement of component feeders. Specifically, it compares the image of the component placed or being placed before replacing the feeder with the image after replacement from the new feeder, making it easier to replace the feeder, or else the quality of the replacement The guarantee can be improved.

  FIG. 3 is a flow diagram illustrating a method of operating a pick and place device according to one embodiment of the present invention. The method 400 begins at block 402, where the pick and place device 150 obtains an image of the component. This image can be acquired by any suitable device including the reference camera 165, the sensor 184, and the image acquisition system 300. Further, an image can be acquired while the component is being placed (from sensor 184) or after the component is placed on workpiece 157 (eg, using camera 150 or system 300). In this embodiment, the device 150 preferably knows that the component being placed is the last component to be placed from the feeder to be replaced. This information can be provided to the device 150 manually by a technician, including indicating the number of components that the feeder holds when the feeder is loaded. Next, the device 150 counts the number of these mounted components and knows when it is the last component. Alternatively, a sensor signal can be generated to indicate that the feeder is empty when there are no components in the feeder.

  After the feeder replacement has been performed by a technician or automatically, block 404 is executed. At block 404, the pick and place device acquires an image of the component from the newly replaced feeder. This image may be an image of the component while being transported for placement (using sensor 184), or an image of the component when placed on the workpiece (camera 165 or system). 300). At block 406, these images are compared. This comparison can be made by providing the operator with images before and after the exchange and determining whether the operator accepts or rejects the feeder exchange. An example of such an image is shown in FIG. Alternatively, according to a known image analysis method and an automated comparison method using a viewing instrument, confirmation of replacement can be displayed automatically. For example, the host controller 301 (shown in FIG. 2) can be configured to analyze the image before replacement and the image after replacement to automatically generate a confirmation of replacement. Such a technique can confirm differences in the dimensions and shapes of the components. In addition, some polarity indications (such as a polarity indicator on a chip capacitor) can be viewed from the top of the component and as such can easily accommodate automated techniques. In addition, some techniques include optical character recognition methods that can read or image and compare component specification displays at the top of the component.

  Because acquisition of component images occurs during the normal pick and place process, some embodiments of the present invention may acquire or synchronize additional images other than those already being performed. Even is unnecessary.

  FIG. 4 is a flow diagram illustrating a method of operating a pick and place device in accordance with another embodiment of the present invention. Method 420 is similar to method 400, but is better suited to situations where the device does not know in advance that a feeder replacement should be performed. In addition, the method 420 can handle a large number of feeders that are being replaced while technicians intervene. The method 420 includes a block 422 that, as a whole, stores an image of one component being mounted or being mounted for each of the operable feeders, along with an indication of the feeder to which the image relates. Thus, if ten feeders are operational, block 422 of method 420 requires ten images stored with each feeder display. When a new component of a given feeder is placed, the image of the new component is overwritten on the image stored for that feeder. Thus, there will be a substantial number of image buffers, each storing the latest component images for those feeders.

  At block 424, the device 150 receives an indication that one or more feeder replacements should be made, and therefore moves offline. This display can be provided directly, such as by a technician entering data or displaying feeder replacement, providing some form of input, etc. However, this indication may be done indirectly, such as by moving or displacing the component feeder, and this movement is aligned by a switch physically connected to the feeder and electronically connected to the device 150. be able to. Furthermore, an indication of which feeder has been exchanged can also be provided in exactly the same manner. Once the exchange is complete, the technician will display this on the pick and place device 150 (through any appropriate input) and the exchange validation process will begin. The device 150 knows which feeder has been replaced, and since the device 150 also has an image of the pre-replacement components stored for all feeders, what is needed is from each replaced feeder. It only takes an image of the component. Accordingly, at block 426, the device 150 obtains an image of each component picked up from the newly replaced feeder.

  At block 428, each of the component images from the newly replaced feeder is compared to the associated pre-replacement image. This process is preferably simply a repetition of that described above with respect to block 406, but can also be accomplished by displaying all of the forms after the exchange and all of their related pre-exchange forms. Furthermore, this comparison can be automated using any suitable known image analysis technique and algorithm.

  FIG. 5 shows a comparison of the placement images of the two components. The upper half of FIG. 5 provides an image of the component before replacement of the component labeled “12R4”, while the lower portion provides an image of the replacement of another component. As can be appreciated, the upper part is substantially identical to the lower part, so technicians can quickly and easily verify that feeder replacement is acceptable simply by displaying “OK”. I can do it.

  Although the present invention has been described with reference to preferred embodiments, workers skilled in the art will recognize that changes may be made in form and detail without departing from the spirit and scope of the invention.

1A is a front view of a pick-and-place apparatus that can implement an embodiment of the present invention. FIG. 1B is a top view of a pick and place device that can implement embodiments of the present invention. 1 is a simplified schematic diagram of an image acquisition system of a pick and place device. FIG. 3 is a flow diagram illustrating a method of operating a pick and place device in accordance with one embodiment of the present invention. FIG. 6 is a flow diagram illustrating a method of operating a pick and place device according to another embodiment of the present invention. It is a figure which compares the placement image of two components.

Claims (19)

In a pick and place device configured to facilitate confirmation of feeder replacement,
A placement head having at least one nozzle that releasably holds at least one component;
A robotic system that generates relative movement between the placement head and the workpiece;
An image acquisition system arranged to acquire an image of a component located at a placement position in the workpiece;
A feeder coupled to the apparatus and configured to provide a plurality of components;
An image acquisition system acquires and stores an image before replacement of at least one component arranged at a placement position in the workpiece before replacement of a feeder, and placement in the workpiece after replacement of a feeder A pick and place device configured to acquire an exchanged image of at least one component placed in position.   2. The pick and place device according to claim 1, further comprising a display device configured to display an image before replacement of the at least one component and an image after replacement of the at least one component. Place equipment.   2. The pick-and-place apparatus according to claim 1, wherein an image before replacement of the at least one component and an image after replacement of the at least one component are analyzed to automatically generate a confirmation of replacement. A pick and place device further comprising an image processing device in the form.   The pick and place apparatus according to claim 1, wherein the image acquisition system is a camera attached to the placement head.   2. The pick and place device according to claim 1, wherein the image acquisition system has an optical axis that is inclined with respect to the workpiece.   2. The pick and place device according to claim 1, wherein the pick and place device is a Cartesian coordinate type pick and place device.   2. The pick and place device according to claim 1, wherein the pick and place device is a split gantry type device.   2. The pick and place device according to claim 1, wherein the pick and place device is a turret type device. In the method of confirming the replacement of the feeder holding the component before replacement and the feeder holding the component after replacement in the pick and place device,
Obtaining an image of the component prior to replacement using a pick and place device;
Replacing the feeder;
Obtaining an image of the replaced component using a pick and place device;
Performing a comparison between the image of the components of the previous image and the replacement of components after the replacement,
And a step of confirming the replacement of the feeder on the basis of said comparison, how to determine the replacement of the feeder. 10. The method of claim 9, wherein obtaining the pre-replacement image is performed when the pre-replacement component is being transported for placement. 11. The method of claim 10, wherein the step of obtaining a replacement image is performed when the replacement component is being transported for placement.   10. The method of claim 9, wherein obtaining the pre-replacement image is performed after placing the pre-replacement component.   13. The method of claim 12, wherein obtaining the replacement image is performed after placing the replacement component.   The method of claim 9, wherein generating the comparison includes providing a technician with a pre-replacement image and a post-replacement image, and receiving input from the technician regarding confirmation of feeder replacement. Method.   The method of claim 9, wherein the step of confirming feeder replacement based on the comparison is performed by a pick and place device. In a method for confirming replacement of at least one feeder in a pick and place device,
Acquiring and storing at least one pre-replacement component image for a plurality of operable feeders;
Receiving an indication regarding at least one feeder change;
Obtaining an image of at least one post-replacement component for the replaced feeder;
And performing at least one comparison between the image of the image with the exchange before the components of the component after the replacement,
And a step of confirming the replacement based on the comparison, a method of confirming the replacement of the feeder. 17. The method of claim 16, wherein the indication regarding the at least one feeder change is made manually by a technician. 17. The method of claim 16, wherein the indication regarding the at least one feeder change is made based on detection by at least one sensor coupled to the feeder.   The method of claim 16, wherein the step of confirming a feeder replacement based on the comparison is performed by a pick and place device.

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