Patent Application
20140093638
1. Field of the Disclosure
This disclosure relates generally to apparatus and methods for dispensing a viscous material on a substrate, such as a printed circuit board, and more particularly to a system and related methods for accurately dispensing material based on locating an angular feature on the circuit board.
2. Discussion of Related Art
There are several types of prior art dispensing systems used for dispensing precise amounts of liquid or paste for a variety of applications. One such application is the assembly of integrated circuit chips and other electronic components onto circuit board substrates. In this application, automated dispensing systems are used for dispensing very small amounts, or dots, of viscous material onto a circuit board. The viscous material may include liquid epoxy or solder paste, or some other related material. Prior to performing a dispensing operation, the circuit board must be aligned or otherwise registered with a dispenser of the dispensing system. In one known method, this may be achieved by employing a vision system of the dispensing system to verify the location of landmarks, otherwise known as fiducials, on the circuit board. Specifically, to align the circuit board with the dispensing unit of the dispensing system, images of at least two fiducials are taken by a camera of the vision system. If the circuit board is out of position, a gantry capable of moving the dispenser may be manipulated to account for the actual position of the circuit board. In another embodiment, a support surface upon which the circuit board rests may be manipulated to accurately position the circuit board prior to performing a dispense operation.
One issue associated with the use of identifying fiducials to align the circuit board with the dispensing unit is when the area requiring dispensing is not well defined with reference to the fiducials. For example, if the area to dispense is not referenced with respect to the fiducials, the resulting dispense operation may be very inaccurate, and under many instances, may not meet the processing requirements.
The present disclosure describes a technique of dispensing material onto substrates having areas that are not well defined by locating one or more angular features on the substrate (as well as one or more fiducials) and dispensing material based on the angular feature(s).
This technique includes using a single fiducial to determine the location and orientation of an object to be dispensed on and using this information to orient a dispensing unit relative to the found object to enhance the ability to accurately dispense a line of material or one or more dots of material located on a substrate, such as a circuit board. To dispense a line accurately on a substrate, an object (e.g., a component mounted on a circuit board or the like) is located on the circuit board and the location, orientation and angle of the object is determined to dispense a line relative to the object. While the dispensed line is frequently perpendicular or parallel to the found orientation of the object, the dispensed line is not required to be perpendicular or parallel. The dispensed line may be straight or in the form of an arc. The dispensed line may be contiguous or in the form of one or more dots or line segments. Line patterns and sub-patterns may be utilized as well. When dispensing, sensing a z-axis height above the circuit board may be used. To enhance the accuracy of the dispense operation, a subset of features of the object may be selected.
One aspect of the present disclosure is directed to a dispensing system for depositing material on an electronic substrate. In one embodiment, the dispensing system includes a frame, a dispensing unit gantry movably coupled to the frame, and a dispensing unit coupled to the dispensing unit gantry. The dispensing unit is configured to deposit material onto the substrate during the dispense operation. The dispensing unit further includes a vision system gantry coupled to the frame and a vision system coupled to the vision system gantry. The vision system is configured to obtain one or more images of the electronic substrate prior to performing the dispense operation. A controller is coupled to the dispensing unit gantry, the dispensing unit, the vision system gantry, and the vision system. The controller is configured to obtain an image of a fiducial provided on the electronic substrate, obtain an image of at least a portion of an object positioned on the electronic substrate, orient the object with respect to the dispensing unit, and perform a dispense operation to secure the object to the electronic substrate.
Embodiments of the dispensing system further may include a support assembly coupled to the frame. The support assembly may be configured to support the electronic substrate during a dispense operation. The controller further may be configured to manipulate the vision system with the vision gantry system to move to a position defined by a feature of the object and to acquire the image. Performing a dispense operation may include dispensing material in the shape of an arc. The object may be a camera having a body and a plurality of tabs extending from a periphery of the body. The dispensing unit may be configured to dispense material between adjacent tabs. The controller further may be configured to dispense lines of material and/or dots of material. The dispensing unit may include a sensor configured to sense a z-axis height on the electronic substrate.
Another aspect of the disclosure is directed to a method of depositing material on an electronic substrate with a dispensing system of the type including a frame, a dispensing unit gantry movably coupled to the frame, a dispensing unit coupled to the dispensing unit gantry, the dispensing unit being configured to deposit material onto the substrate during the dispense operation, a vision system gantry coupled to the frame, and a vision system coupled to the vision system gantry, the vision system being configured to obtain one or more images of the electronic substrate prior to performing the dispense operation. In one embodiment, the method comprises: obtaining an image of a fiducial provided on the electronic substrate; obtaining an image of at least a portion of an object positioned on the electronic substrate; orienting the object with respect to the dispensing unit; and performing a dispense operation to secure the object to the electronic substrate.
Embodiments of the method further may include sensing a z-axis height on the electronic substrate and/or supporting the electronic substrate during a dispense operation with a support assembly coupled to the frame. The method may be performed under the control of a controller configured to manipulate the vision system with the vision gantry system to move to a position defined by a feature of the object and to acquire the image. The controller further may be configured to dispense lines of material and/or dots of material. Performing a dispense operation may include dispensing material in the shape of an arc. The object may be a camera having a body and a plurality of tabs extending from a periphery of the body. The dispensing unit may be configured to dispense material between adjacent tabs.
The accompanying drawings are not intended to be drawn to scale. In the drawings, each identical or nearly identical component that is illustrated in various figures is represented by a like numeral. For purposes of clarity, not every component may be labeled in every drawing. In the drawings:
For the purposes of illustration only, and not to limit the generality, the present disclosure will now be described in detail with reference to the accompanying figures. This disclosure is not limited in its application to the details of construction and the arrangement of components set forth in the following description or illustrated in the drawings. The principles set forth in this disclosure are capable of other embodiments and of being practiced or carried out in various ways. Also the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting. The use of “including,” “comprising,” “having,” “containing,” “involving,” and variations thereof herein, is meant to encompass the items listed thereafter and equivalents thereof as well as additional items.
Various embodiments of the present disclosure are directed to viscous material dispensing systems, devices including dispensing systems, and methods of locating objects on electronic substrates, such as printed circuit boards, and performing dispensing operations on the substrates. Embodiments disclosed herein are directed to techniques for dispensing material on an electronic substrate by using a single fiducial and by locating and orienting an object, and using the location of the object to orient a dispensing unit or pump of the dispensing system to enhance a dispense operation.
The systems and methods disclosed herein may frequently perform a dispense operation that is perpendicular or parallel to the found orientation of the object; however, this is not a requirement. The dispensed line may be straight or in the form of an arc.
The systems and methods further enable the accurate dispense of dots or line segments. Specifically, a dispensing unit of the dispensing system may be modified to dispense dots.
The dispenser 10 may also include a frame 20 having a base or support 22 for supporting the substrate 12, a dispensing unit gantry 24 movably coupled to the frame 20 for supporting and moving the dispensing units 14, 16, and a weight measurement device or weigh scale 26 for weighing dispensed quantities of the viscous material, for example, as part of a calibration procedure, and providing weight data to the controller 18. A conveyor system (not shown) or other transfer mechanism, such as a walking beam may be used in the dispenser 10 to control loading and unloading of substrates to and from the dispenser. The gantry 24 can be moved using motors under the control of the controller 18 to position the dispensing units 14, 16 at predetermined locations over the substrate. The dispenser 10 may include a display unit 28 connected to the controller 18 for displaying various information to an operator. There may be an optional second controller for controlling the dispensing units. Also, each dispensing unit 14, 16 can be configured with a z-axis sensor to detect a height at which the dispensing unit is disposed above the electronic substrate 12 or above a feature mounted on the electronic substrate. The z-axis sensor is coupled to the controller 18 to relay information obtained by the sensor to the controller.
Prior to performing a dispensing operation, as described above, the substrate, e.g., printed circuit board, must be aligned or otherwise in registration with a dispenser of the dispensing system. The dispenser further includes a vision system 30, which is coupled to a vision system gantry 32 movably coupled to the frame 20 for supporting and moving the vision system. As described, the vision system 30 is employed to verify the location of landmarks, known as fiducials, on the substrate. Once located, the controller can be programmed to manipulate the movement of one or both of the dispensing units 14, 16 to dispense material on the electronic substrate.
Systems and methods of the present disclosure are directed to dispensing material onto a substrate, e.g., a circuit board, by locating an object provided on the substrate with both location and angular components. The description of the systems and methods provided herein reference exemplary electronic substrates 12 (e.g., printed circuit boards), which are supported on the support 22 of the dispenser 10. In one embodiment, the dispense operation is controlled by the controller 18, which may include a computer system configured to control material dispensers. In another embodiment, the controller 18 may be manipulated by an operator. The controller 18 is configured to manipulate the movement of the vision system gantry 32 to move the vision system so as to obtain one or more images of the electronic substrate 12. The controller 18 further is configured to manipulate the movement of the dispensing unit gantry 24 to move the dispensing units 14, 16 to perform dispensing operations.
The angular locate feature of the systems and methods of the present disclosure uses the known geometry of a special object, which provides x-axis, y-axis and theta information derived from its relative position with respect to one or more fiducials provided on the electronic substrate. In one embodiment, the special object may be an item that is mounted on the substrate, such as a mega pixel camera. Such a camera typically includes features that are difficult to orient with respect to the electronic substrate and the dispenser. Specifically, one issue associated with the use of such cameras is the difficulty of aligning the camera and the electronic substrate with the dispensing unit is when the area requiring dispensing is not well defined with reference to the camera. For example, if the area to dispense is not referenced with respect to the camera, the resulting dispense operation may be very inaccurate, and under many instances, may not meet the processing requirements.
In one embodiment, an exemplary method is illustrated in
As shown, the method begins at 202. At 204, the vision system is employed to obtain an image of at least one known fiducial. In most applications fiducials are located in known locations on the substrate or carrier, such as the corners of the electronic substrate, and two fiducials are located. The location of the fiducial is stored by the controller of the dispenser.
At 206, the vision system is further employed to obtain an image or images of the object. In a certain embodiment, the object is a camera having features, such as tabs. In some embodiments, the camera may be inserted into a feature mounted on the electronic substrate, such as a circular barrel or rim. When inserted, the orientation of the features with respect to the electronic substrate is unknown. As with the fiducial, the location of the object is stored by the controller of the dispenser.
At 208, the controller determines the orientation of the object based on the location of the features of the object with respect to the known location of the fiducial of the electronic substrate and the position of the dispensing unit of the dispenser. With the orientation of the object known, the areas requiring dispensing, e.g., the areas between the features of the object, can be determined.
At 210, a dispense operation is performed. In one embodiment, material, such as epoxy, is dispensed between the tabs of the camera in a slot between the camera and an inner wall of the barrel. The dispense operation is performed under the control of the controller.
At 212, once the dispense operation completes dispensing material the method ends.
When inserted, the camera 304 is not oriented with respect to the barrel 302 and the electronic substrate 300. Thus, the tabs 308, 310, 312, 314 of the camera 304 are oriented randomly with respect to the barrel 302 and the board 300. When securing the camera 304 to the electronic substrate 300, assembly material (e.g., adhesive) is dispensed within slots 316, 318, 320, 322 defined between an outer surface of the body 306 of the camera 302, the tabs 308, 310, 312, 314 of the camera and an inner surface of the barrel. The system and method of the present disclosure is designed to enable the dispensing unit of the dispenser to dispense material within the slots, which are randomly oriented with respect to the barrel 302 and the electronic substrate 300.
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The computer system may include an operating system that manages at least a portion of the hardware elements included in the computer system. Usually, a processor or controller executes an operating system which may be, for example, a Windows-based operating system, such as, Windows NT, Windows 2000 (Windows ME), Windows XP or Windows Vista operating systems, available from the Microsoft Corporation, a MAC OS System X operating system available from Apple Computer, one of many Linux-based operating system distributions, for example, the Enterprise Linux operating system available from Red Hat Inc., a Solaris operating system available from Sun Microsystems, or a UNIX operating system available from various sources. Many other operating systems may be used, and the embodiments disclosed herein are not intended to be limited to any particular implementation.
The processor and operating system together define a computer platform for which application programs in high level programming languages may be written. These component applications may be executable, intermediate, for example, C-, bytecode or interpreted code which communicates over a communication network, for example, the Internet, using a communication protocol, for example, TCP/IP. Similarly, aspects in accord with the present disclosure may be implemented using an object-oriented programming language, such as .Net, SmallTalk, Java, C++, Ada, or C# (C-Sharp). Other object-oriented programming languages may also be used. Alternatively, functional, scripting, or logical programming languages may be used.
Additionally, various aspects and functions in accordance with the present disclosure may be implemented in a non-programmed environment, for example, documents created in HTML, XML or other format that, when viewed in a window of a browser program, render aspects of a graphical-user interface or perform other functions. Further, various embodiments in accord with the present disclosure may be implemented as programmed or non-programmed elements, or any combination thereof. For example, a web page may be implemented using HTML while a data object called from within the web page may be written in C++. Thus, the disclosure is not limited to a specific programming language and any suitable programming language could also be used.
It should be noted that systems and methods described herein may be performed on objects other than mega pixel cameras. For example, the method may be performed on any type of electronic component mounted on an electronic substrate. The geometry of the object should be known prior to performing the method.
Having thus described several aspects of at least one embodiment of this disclosure, it is to be appreciated various alterations, modifications, and improvements will readily occur to those skilled in the art. Such alterations, modifications, and improvements are intended to be part of this disclosure, and are intended to be within the spirit and scope of the invention. Accordingly, the foregoing description and drawings are by way of example only.
