Patent ID: 12226795

DETAILED DESCRIPTION OF THE DISCLOSURE

Various embodiments of the present disclosure are directed to viscous material dispensing systems, devices including dispensing systems. Embodiments disclosed herein are directed to techniques for dispensing material on an electronic substrate by a dispensing system. Such dispensing systems are configured to dispense an assembly material (e.g., solder paste, conductive ink, adhesive, or encapsulation material) onto an electronic substrate (e.g., a printed circuit board, referred to herein as an “electronic substrate,” a “circuit board,” a “board,” a “PCB,” a “PCB substrate,” a “substrate,” or a “PCB board”) or to perform other operations. Specifically, embodiments of the present disclosure are described below with reference to dispensing system, sometimes referred to as “dispensers,” used to produce printed circuit boards.

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. Any references to examples, embodiments, components, elements or acts of the systems and methods herein referred to in the singular may also embrace embodiments including a plurality, and any references in plural to any embodiment, component, element or act herein may also embrace embodiments including only a singularity. References in the singular or plural form are not intended to limit the presently disclosed systems or methods, their components, acts, or elements. The use herein of “including.” “comprising.” “having.” “containing.” “involving.” and variations thereof is meant to encompass the items listed thereafter and equivalents thereof as well as additional items. References to “or” may be construed as inclusive so that any terms described using “or” may indicate any of a single, more than one, and all of the described terms. In addition, in the event of inconsistent usages of terms between this document and documents incorporated herein by reference, the term usage in the incorporated reference is supplementary to that of this document; for irreconcilable inconsistencies, the term usage in this document controls.

FIG.1schematically illustrates a dispensing system, generally indicated at10, according to one embodiment of the present disclosure. The dispensing system10is used to dispense a viscous material (e.g., an adhesive, encapsulant, epoxy, solder paste, underfill material, etc.) or a semi-viscous material (e.g., soldering flux, etc.) onto an electronic substrate12, such as a printed circuit board or semiconductor wafer. The dispensing system10may alternatively be used in other applications, such as for applying automotive gasketing material or in certain medical applications or for applying conductive inks. It should be understood that references to viscous or semi-viscous materials, as used herein, are exemplary and intended to be non-limiting. In one embodiment, the dispensing system10includes first and second dispensing units, generally indicated at14and16, respectively, and a controller18to control the operation of the dispensing system. It should be understood that dispensing units also may be referred to herein as dispensing pumps and/or dispensing heads. Although two dispensing units are shown, it should be understood that a single dispensing unit or multiple dispensing units can be employed.

The dispensing system10may also include a frame20having a base or support22for supporting the electronic substrate12, a dispensing unit gantry24movably coupled to the frame20for supporting and moving the dispensing units14,16, and a weight measurement device or weigh scale26for weighing dispensed quantities of the viscous material, for example, as part of a calibration procedure, and providing weight data to the controller18. A conveyor system (not shown) or other transfer mechanism, such as a walking beam, may be used in the dispensing system10to control loading and unloading of electronic substrates to and from the dispensing system. The gantry24can be moved using motors under the control of the controller18to position the dispensing units14,16at predetermined locations over the electronic substrate. The dispensing system10may include a display unit28connected to the controller18for displaying various information to an operator. There may be an optional second controller for controlling the dispensing units. Also, each dispensing unit14,16can be configured with a z-axis sensor, e.g., a laser, to detect a height at which the dispensing unit is disposed above the electronic substrate12or above a feature mounted on the electronic substrate. The z-axis sensor is coupled to the controller18to relay information obtained by the sensor to the controller.

Prior to performing a dispensing operation, as described above, the electronic substrate, e.g., the printed circuit board, must be aligned or otherwise in registration with a dispensing unit of the dispensing system. The dispensing system further includes a vision system30, which, in one embodiment, is coupled to a vision system gantry32movably coupled to the frame20for supporting and moving the vision system. In another embodiment, the vision system30may be provided on the gantry24. As described, the vision system30is employed to verify the location of landmarks, known as fiducials, targets or reference points, on the electronic substrate. Once located, the controller can be programmed to manipulate the movement of one or more of the dispensing units14,16to dispense material on the electronic substrate.

Systems and methods of the present disclosure are directed to dispensing material onto an electronic substrate, e.g., a printed circuit board. The description of the systems and methods provided herein reference exemplary electronic substrates12(e.g., printed circuit boards), which are supported on the support22of the dispensing system10. In one embodiment, the dispense operation is controlled by the controller18, which may include a computer system configured to control material dispensing units. In another embodiment, the controller18may be manipulated by an operator. The controller18is configured to manipulate the movement of the vision system gantry32to move the vision system so as to obtain one or more images of the electronic substrate12. The controller18further is configured to manipulate the movement of the gantry24to move the dispensing units14,16to perform dispensing operations.

The methods disclosed herein further support the use of various types of dispensing units, including, but not limited to, auger, piston, time and pressure, and jetting pumps.

In one embodiment, an exemplary dispensing system described herein may embody Camalot® dispensing systems, such as PRODIGY™ dispensers, sold by ITW EAE of Hopkinton, Massachusetts.

One particular challenge is to dispense an appropriate amount of material in a gap between two features. Embodiments of a method disclosure herein are directed to adjusting a dispense volume based on the positions of the located features. The width of a gap between two features may vary along a length of the gap. In one embodiment, a vision system, such as vision system30, can be employed by the vision system gantry32to locate an edge of a component. Next, the method includes providing a measure command to measure an actual gap between an outer edge of a first feature and an inner edge of the second feature. A minimum limit on a gap between the inner and outer edges is determined. If the gap is less than the minimum limit, no dispense operation is performed. If the gap is greater than or equal to the minimum limit, the length of the gap is divided into segments and a gap width is determined for each segment. Based on the viscosity of the material and other external factors, a table is provided for each line to define a line width based on the gap measurement. The line width controls a speed of the gantry, such as gantry24, which in turn controls amount of material dispensed within a particular segment. The line width may be defined as a number of dots that are dispensed per a predefined length, e.g., millimeter (mm). The greater the line width, the slower the gantry speed. The speed at which the dots are dispensed may be defined as the number of dispensed dots per second (Hz). A single line command can be provided for all of the segments or separate line commands can be provided for each segment.

In one example, with reference toFIG.2, an image of a component40, e.g., any type of component mounted on the electronic substrate, is taken by a vision system, such as vision system30. Specifically, in one example employing the dispensing system10ofFIG.1, the vision system gantry32, under the control of the controller18, moves the vision system30over the component40to obtain the image of the component.FIG.2illustrates an image of the whole or complete component40. However, an image of a portion of the component40may also be provided. As shown, the component40is supported within a chassis42. A gap44is provided between outer edges of the component40and inner edges of the chassis42. The gap44varies along the four sides of the component40and the chassis42. Further, the gap44varies along a length of each side, meaning that the gap44is wider or narrower along a length of each side.

Based on image of the component, the controller, such as controller18, can be configured to program a measure command for each side to measure an actual distance between the outer edge of the component40and the inner edge of the chassis42. Edges on the component40and the chassis42can be beveled, radial or sharp, depending on the product design and how the edges are displayed by the vision system and the vision system software. The controller can be configured to set a minimum limit on a gap between the outer edge of the component40and the inner edge of the chassis42. In one embodiment, the gap44can be set to a predetermined minimum limit by the user, and if the gap is less than the minimum limit, the controller can be configured to skip performing a dispense operation on the whole part if any edge section is found lower than the minimum limit. With a small gap, e.g., less than 0.45 mm, a dispense operation may be omitted on the whole or in part if any edge section gap distance is found to be lower than the defined minimum limit. However, if the programmed measure command determines the measured gap44to be greater than or equal to the minimum limit, e.g., greater or equal to than 0.45 mm, the controller can be configured to perform a dispense operation.

Referring toFIG.3, to perform the measure command, the controller is configured to divide each side of the gap44between the component40and the chassis42into a number of segments, each indicated at46. In some embodiments, the number of segments46can be three to twenty segments. The measure command includes determining a gap width for each segment46. Based on found gap width, a line width is drawn from the preprogrammed template as shown below.

In one embodiment, a table may be provided for each line to define the line width based on the gap measurement obtained for each segment46. Reference can be provided below to Table 1. The determination of the line width controls a speed of the gantry to control the amount of material dispensed by the dispensing unit, e.g., dispensing unit14or16. The line width is defined as a number of dots dispensed per unit length, such as dots/mm. For example, if a line is 10 mm long and a line width is 3 dots/mm, a total dispense of 30 dots to be dispensed at calculated spacing between individual dots determined by the velocity of the gantry carrying the dispensing unit.

TABLE 1Gap Measurement, mmLowHighLine Width, Number of Dots/mm0.450.5020.500.5530.550.6040.600.655

Referring toFIG.4, in one example, an elongate gap or line48having a predefined length is divided into a number of segments based on a length of the line. In the shown example, the line48is divided into four segments. As shown below in Table 2, a first segment (Segment No. 1) has a measured gap of 0.46 mm, which is greater than a minimum gap width of 0.45 mm, and a line width of 2 dots. A second segment (Segment No. 2) has a measured gap of 0.54 mm and a line width of 3 dots. A third segment (Segment No. 3) has a measured gap of 0.59 mm and a line width of 4 dots. And finally, a fourth line segment (Segment No. 4) has a measured gap of 0.65 and a line width of 5 dots.

TABLE 2SegmentMeasured Gap,Within GapLineNumbermmLimitWidthRPM, Hz10.46Yes210020.54Yes310030.59Yes410040.65Yes5100

As shown with the example provided above, the width of line48becomes increasingly wider from left to right inFIG.4. However, aspects of the method disclosed herein can be configured to address line lengths with varying measured gap widths along the length of the line across each defined segment. The controller, e.g., controller18, can be configured to control the dispensing unit, e.g., dispensing units14,16and the dispensing unit gantry, e.g., gantry24, to dispense a line of material through each segment, e.g., Segment Nos. 1-4, of the line48.

In the shown embodiment, during a dispense operation, as the width of the line48increases, the gantry, e.g., gantry24, is configured by the controller to move at a slower speed, while the dispensing unit, e.g., dispensing unit14or16, dispenses at a continuous rate. The greater the line width, the slower the gantry speed, and conversely, the smaller the line width, the greater the gantry speed. The rate of speed of movement of the gantry depends on the amount of material being dispensed. Other factors may be considered. As used herein, revolutions per minute (RPM) or Hz may be used to define the number of dispensed dots per second. As shown in the table above, a single command can be provided to perform a dispense operation on all four segments or individual command can be provided for each segment. The latter would result in each segment having a different RPM and thus a different speed of movement.

Thus, for the example shown inFIG.4and Table 2, the gantry is configured to move the dispensing unit at a relatively higher rate of speed to dispense two dots in the first segment (Segment No. 1), at a relatively slower rate of speed to dispense three dots in the second segment (Segment No. 2), at a further relatively slower rate of speed to dispense four dots in the third segment (Segment No. 3), and at an even further relatively slower rate of speed to dispense five dots in the fourth segment (Segment No. 4). The rate at which the dispensing unit dispenses dots of material is 100 Hz, so the speed of movement of the gantry is adjusted accordingly.

In other embodiments, the rate at which dots is dispensed by the dispensing unit can be varied to address segments having varying gap widths. As referenced above, in one embodiment, the volume of material dispensed is controlled by varying the speed of the gantry having the dispensing unit, e.g., dispensing unit14or16. However, in another embodiment, the rate in which the dispensing unit dispenses dots can be modified depending on the measured gap within the segment to vary the number of dots dispensed in that segment. This is achieved while maintaining a constant speed of the dispensing unit on the gantry. Thus, in this embodiment, the rate at which material is dispensed by the dispensing unit is at a relatively slow rate to dispense two dots in the first segment, at a relatively higher rate to dispense three dots in the second segment, at a further relatively higher rate to dispense four dots in the third segment, and at an even further relatively higher rate to dispense five dots in the fourth segment.

In some embodiments, a line to be dispensed is divided into four or five segments, with each segment being between 4 and 5 mm in length. A gap width is measured for each segment. Based on the measured gap width, a number of dots is selected to be dispensed for each gap.

In some embodiments, each image is composed of pixels with each pixel being the smallest picture element the vision system can uniquely identify and interpreted as Black or White with shades of gray.

Various controllers, such as the controller18, may execute various operations discussed above. Using data stored in associated memory and/or storage, the controller18also executes one or more instructions stored on one or more non-transitory computer-readable media, which the controller18may include and/or be coupled to, that may result in manipulated data. In some examples, the controller18may include one or more processors or other types of controllers. In one example, the controller18is or includes at least one processor. In another example, the controller18performs at least a portion of the operations discussed above using an application-specific integrated circuit tailored to perform particular operations in addition to, or in lieu of, a general-purpose processor. As illustrated by these examples, examples in accordance with the present disclosure may perform the operations described herein using many specific combinations of hardware and software and the disclosure is not limited to any particular combination of hardware and software components. Examples of the disclosure may include a computer-program product configured to execute methods, processes, and/or operations discussed above. The computer-program product may be, or include, one or more controllers and/or processors configured to execute instructions to perform methods, processes, and/or operations discussed above.

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.