Distribution volume adjustment based on positioning feature gap width

Abstract

A method of depositing material on an electronic substrate using a dispensing system includes: acquiring an image of a first feature of a first component and an adjacent second feature of a second component; executing a measurement command to measure an actual distance of a gap between a first feature of the first component and a second feature of the second component; a length of the gap is divided into a plurality of segments to determine a gap width for each segment based on the gap width, determine a number of points assigned by the assignment unit for each segment, and perform an assignment operation for each segment.

Description

[0001] BACKGROUND OF THE DISCLOSURE 1. TECHNICAL FIELD The present disclosure relates generally to apparatuses and methods for dispensing viscous material on electronic substrates, such as printed circuit boards, and more particularly to an apparatus and method for dispensing material on an electronic substrate using a dispensing unit configured to adjust the volume of material dispensed based on a positioned feature.

[0002] 2. DISCUSSION OF RELATED ART There are several types of dispensing systems used to dispense precise amounts of liquid or paste for various applications. One such application is the assembly of integrated circuit chips and other electronic components onto circuit board substrates. In the present application, an automated dispensing system is used to dispense a dot of liquid epoxy or solder paste or some other related material onto a printed circuit board. Automated dispensing systems are also used to dispense linear lines of underfill material and encapsulants that can be used to mechanically secure components to a printed circuit board. Exemplary dispensing systems described above include those manufactured and distributed by Illinois Tool Works Electronic Assembly Equipment (ITWEAE), with offices in Hingham, Massachusetts.

[0003] In a typical dispensing system, a dispensing unit is mounted to a moving assembly or gantry for moving the dispensing unit along three mutually orthogonal axes (x, y, and z) using servo motors controlled by a computer system or controller. To dispense a dot of liquid at a desired location on a printed circuit board or other substrate, the dispensing unit is moved along the coplanar horizontal x and y axis directions until the dispensing unit is positioned above the desired location. The dispensing unit is then lowered along the vertically oriented vertical z axis direction until the dispensing unit and the dispensing system's nozzle / needle are at the proper dispensing height above the electronic substrate. The dispensing unit dispenses the dot of liquid, then is raised along the z axis, moved to a new location along the x and y axes, and lowered along the z axis to dispense the next dot of liquid. For applications such as encapsulation or dispensing underfill material as described previously, the dispensing unit is typically controlled to dispense a line of material as the dispensing unit moves along a desired path of the line of material in the x and y axes. For some types of dispensing units, such as jet pumps, z axis movement can not be required before and after the dispensing operation.

[0004] Vision systems are used to locate objects on electronic substrates. It can be difficult to determine the volume of material to dispense. For gaps with different widths and small gaps, it is difficult to control the volume of material and dispense the material under the components on the substrate. SUMMARY

[0005] One aspect of the present disclosure relates to a method of depositing material on an electronic substrate with a dispensing system, the dispensing system comprising: a frame, a dispensing unit rack movably coupled to the frame, a dispensing unit coupled to the dispensing unit rack, the dispensing unit configured to deposit material onto the electronic substrate during a dispensing operation, a vision system rack coupled to the frame, and a vision system coupled to the vision system rack. The vision system is configured to obtain one or more images of the electronic substrate having two adjacent features prior to performing the dispensing operation. In one embodiment, the method comprises: obtaining an image of a first feature of a first component and an adjacent second feature of a second component; executing a measurement command to measure an actual distance of a gap between the first feature of the first component and the second feature of the second component; segmenting a length of the gap into a number of segments to determine a gap width of each segment; determining a number of dots to be dispensed by the dispensing unit for each segment based on the gap width; and performing a dispensing operation for each segment.

[0006] Embodiments of the method can further comprise determining the number of dots by having a table of dots to be dispensed based on the gap width. Performing the dispensing operation can comprise controlling a speed of the rack to dispense the desired number of dots within the respective segment. Performing the dispensing operation can further comprise controlling a rate of dots dispensed by the dispensing unit to be a substantially uniform rate along the length of the gap. Performing the dispensing operation can comprise controlling a rate of dots dispensed by the dispensing unit to dispense the desired number of dots within the respective segment. Performing the dispensing operation can further comprise controlling a speed of the rack to be a substantially uniform speed along the length of the gap. Each image can be comprised of pixels, where each pixel is a smallest image element that the vision system can uniquely recognize and interpret as black or white with shades of gray. The method can further comprise determining whether the actual gap is less than a predetermined minimum limit, and if less than the predetermined minimum limit, not performing an action.

[0007] A computer readable medium comprising instructions which, when executed by a computer, cause the computer to perform a method of: obtaining an image of a first feature of a first component and an adjacent second feature of a second component; executing a measurement command to measure an actual distance of a gap between the first feature of the first component and the second feature of the second component; segmenting a length of the gap into a number of segments to determine a gap width of each segment; determining a number of dots to be dispensed by the dispensing unit for each segment based on the gap width; and performing a dispensing operation for each segment.

[0008] Embodiments of the computer-readable medium may further include determining the number of points by means of a table having points to be allocated based on the gap width. Performing the allocation operation may include controlling the speed of the rack to allocate the desired number of points within the corresponding segment. Performing the allocation operation may further include controlling the rate at which the points allocated by the allocation unit are at a substantially consistent rate along the length of the gap. Performing the allocation operation may further include controlling the speed of the rack to a substantially consistent rate along the length of the gap. Each image may consist of pixels, wherein each pixel is the smallest image element that a vision system can uniquely identify and interpret as black or white with gray shading. The computer-readable medium may further include determining whether the actual gap width is less than a predetermined minimum limit, and if it is less than the predetermined minimum limit, then no action is performed. Attached Figure Description

[0009] At least one embodiment will be discussed below with reference to the accompanying drawings, which are not intended to be drawn to scale. The drawings are included to provide illustration and further understanding of the aspects and embodiments, and are incorporated in and form part of this specification, but are not intended to be a definition of limitation on any particular embodiment. The drawings, together with the remainder of the specification, serve to explain the principles and operation of the described and claimed aspects and embodiments. In the drawings, each identical or substantially identical component shown in the various figures is indicated by the same reference numerals. For clarity, not every component may be labeled in every figure. In the drawings: Figure 1 This is a schematic diagram of the distribution system; Figure 2 It is a plan view of the components on the electronic substrate; Figure 3 This is an enlarged plan view of a portion of the component, showing the gaps divided by several segmented lines; and Figure 4 This is an enlarged plan view of a section component, showing four sections. Detailed Implementation

[0010] Various embodiments of this disclosure relate to adhesive material dispensing systems, including means for dispensing such systems. The embodiments disclosed herein relate to techniques for dispensing materials on electronic substrates using a dispensing system. Such dispensing systems are configured to dispense assembly materials (e.g., solder paste, conductive ink, adhesive, or encapsulation materials) onto electronic substrates (e.g., printed circuit boards, referred to herein as electronic substrates, "circuit boards," boards, "PCBs," "PCB substrates," "substrates," or "PCB boards") or perform other operations. Specifically, embodiments of this disclosure are described below with reference to dispensing systems (sometimes referred to as dispensers) used in the production of printed circuit boards.

[0011] For illustrative purposes only and not for limiting its generality, this disclosure will now be described in detail with reference to the accompanying drawings. The application of this disclosure is not limited to the details of the construction and arrangement of the components set forth in the following description or shown in the drawings. The principles set forth in this disclosure can have other embodiments and can be practiced or performed in various ways. Furthermore, the wording and terminology used herein are for descriptive purposes and should not be considered limiting. Any reference to examples, embodiments, components, elements, or actions of systems and methods mentioned herein in the singular may also cover embodiments including multiple embodiments, and any reference to multiple embodiments, components, elements, or actions herein may also cover embodiments including only the singular. References in the singular or plural form are not intended to limit the systems or methods, components, actions, or elements currently disclosed. The terms "comprising," "including," "having," "containing," "involving," and variations thereof, as used herein, are intended to cover the items listed thereafter and their equivalents, as well as additional items. References to "or" may be interpreted as inclusive, such that any term used with "or" may indicate a single, more than one, or any of all described items. In addition, in the event of any inconsistency in the use of terminology between this document and any document incorporated herein by reference, the terminology used in the incorporated referenced document shall supplement the terminology used in this document; in the case of irreconcilable inconsistencies, the terminology used in this document shall prevail.

[0012] Figure 1 A dispensing system, generally indicated by 10, according to one embodiment of the present disclosure is schematically illustrated. Dispensing system 10 is used to dispense viscous materials (e.g., adhesives, sealants, epoxy resins, solder pastes, underfill materials, etc.) or semi-viscous materials (e.g., flux, etc.) onto an electronic substrate 12 (such as a printed circuit board or semiconductor wafer). Dispensing system 10 may alternatively be used in other applications, such as for applying automotive liner materials or for 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, dispensing system 10 includes first and second dispensing units generally indicated by 14 and 16, respectively, and a controller 18 for controlling the operation of the dispensing system. It should be understood that the dispensing units may also 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 may be employed.

[0013] The dispensing system 10 may further include: a frame 20 having a base or support 22 for supporting the electronic substrate 12; a dispensing unit platform 24 movably coupled to the frame 20 to support and move the dispensing units 14, 16; and a weight measuring device or weighing scale 26 for weighing the amount of viscous material dispensed (e.g., as part of a calibration procedure) and providing weight data to the controller 18. A conveying system (not shown) or other conveying mechanism (such as a stepping beam) may be used in the dispensing system 10 to control the loading and unloading of the electronic substrate into and out of the dispensing system. The platform 24 may be moved using a motor under the control of the controller 18 to position the dispensing units 14, 16 at predetermined positions above the electronic substrate. The dispensing system 10 may include a display unit 28 connected to the controller 18 for displaying various information to an operator. An optional second controller may be present for controlling the dispensing units. Furthermore, each dispensing unit 14, 16 may be configured with a z-axis sensor, such as a laser, to detect the height at which the dispensing unit is positioned 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 forward the information obtained by the sensor to the controller.

[0014] As described above, before performing the dispensing operation, the electronic substrate (e.g., a printed circuit board) must be aligned or otherwise registered with the dispensing units of the dispensing system. The dispensing system also includes a vision system 30, which in one embodiment is coupled to a vision system rack 32, movably coupled to a frame 20 for supporting and moving the vision system. In another embodiment, the vision system 30 may be mounted on a platform 24. As described, the vision system 30 is used to verify the position of landmarks (referred to as reference points), objects, or reference points on the electronic substrate. Once positioned, a controller can be programmed to manipulate movement in one or more dispensing units 14, 16 to dispense material onto the electronic substrate.

[0015] The systems and methods relate to dispensing material onto an electronic substrate (e.g., a printed circuit board). The description of the systems and methods provided herein refers to an exemplary electronic substrate 12 (e.g., a printed circuit board) supported on a support 22 of a dispensing system 10. In one embodiment, the dispensing operation is controlled by a controller 18, which may include a computer system configured to control material dispensing units. In another embodiment, the controller 18 may be operated by an operator. The controller 18 is configured to manipulate movement of a vision system rack 32 to move the vision system to obtain one or more images of the electronic substrate 12. The controller 18 is also configured to manipulate movement of a rack 24 to move dispensing units 14, 16 to perform dispensing operations.

[0016] The method disclosed herein also supports the use of various types of distribution units, including but not limited to screw conveyors, pistons, time and pressure, and jet pumps.

[0017] In one embodiment, the exemplary distribution system described herein can be implemented using Camalot, sold by ITW EAE of Hopkinton, Massachusetts. ® Distribution systems, such as PRODIGY TM Distributor.

[0018] A particular challenge is distributing an appropriate amount of material in the gap between two features. Embodiments of the method disclosed herein involve adjusting the distribution volume based on the location of the positioned features. The width of the gap between the two features can vary along the length of the gap. In one embodiment, a vision system gantry 32 may employ a vision system (such as vision system 30) to locate the edges of the component. Next, the method includes providing a measurement command to measure the actual gap between the outer edge of the first feature and the inner edge of the second feature. A minimum limit for the gap between the inner and outer edges is determined. If the gap is less than the minimum limit, no distribution 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. A table is provided for each line to define the line width based on the gap measurement, based on the material viscosity and other external factors. The line width controls the speed of a gantry (such as gantry 24), which in turn controls the amount of material distributed within a specific segment. The line width can be defined as a plurality of points distributed over a predefined length (e.g., millimeters (mm)). The larger the line width, the slower the gantry speed. The rate at which points are distributed can be defined as the number of points distributed per second (Hz). A single line command can be provided for all segments, or a separate line command can be provided for each segment.

[0019] In one example, reference Figure 2 Images of component 40 (e.g., any type of component mounted on an electronic substrate) are captured by a vision system (such as vision system 30). Specifically, in employing... Figure 1 In one example of the distribution system 10, the vision system stand 32, under the control of the controller 18, moves the vision system 30 above the component 40 to obtain an image of the component. Figure 2 An image of the entire or complete component 40 is shown. However, an image of a portion of component 40 may also be provided. As shown, component 40 is supported within chassis 42, and a gap 44 is provided between the outer edge of component 40 and the inner edge of chassis 42. The gap 44 varies along the four sides of component 40 and chassis 42, and the length of the gap 44 varies along each side, meaning that the gap 44 may be wider or narrower along the length of each side.

[0020] Based on the image of the component, a controller (such as controller 18) can be configured to program measurement commands for each side to measure the actual distance between the outer edge of component 40 and the inner edge of chassis 42. The edges on component 40 and chassis 42 can be beveled, radial, or sharp, depending on the product design and how the edges are displayed by the vision system and vision system software. The controller can be configured to set a minimum limit for the gap between the outer edge of component 40 and the inner edge of chassis 42. In one embodiment, the gap 44 can 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 an allocation operation on the entire portion if any edge segment is found to be below the minimum limit. In the case of small gaps (e.g., less than 0.45 mm), if any edge segment gap distance is found to be below the defined minimum limit, the allocation operation can be omitted on the whole or part. However, if the programmed measurement command determines that the measured gap 44 is greater than or equal to the minimum limit, for example, greater than or equal to 0.45 mm, the controller can be configured to perform an allocation operation.

[0021] refer to Figure 3 To execute the measurement command, the controller is configured to divide each side of the gap 44 between component 40 and chassis 42 into multiple segments, each segment indicated by 46. In some embodiments, the number of segments 46 can be three to twenty. The measurement command includes determining the gap width for each segment 46. Based on the found gap width, a line width is drawn from a pre-programmed template, as shown below.

[0022] In one embodiment, a table may be provided for each line to define the line width based on gap measurements obtained for each segment 46. Reference values ​​may be provided in Table 1 below. The determination of the line width controls the speed of the control frame to control the amount of material dispensed by the dispensing unit (e.g., dispensing unit 14 or 16). The line width is defined as the number of points dispensed per unit length, such as points / mm. For example, if the line is 10 mm long and the line width is 3 points / mm, then a total dispensing of 30 points is made at a calculated interval between the individual points determined by the speed of the control frame carrying the dispensing unit.

[0023] Table 1

[0024] refer to Figure 4In one example, a thin gap or line 48 with a predefined length is divided into multiple segments based on the line length. In the example shown, line 48 is divided into four segments. As shown in Table 2, the first segment (segment No. 1) has a measuring gap of 0.46 mm, which is greater than the minimum gap width of 0.45 mm and a line width of 2 points. The second segment (segment No. 2) has a measuring gap of 0.54 mm and a line width of 3 points. The third segment (segment No. 3) has a measuring gap of 0.59 mm and a line width of 4 points. Finally, the fourth segment (segment No. 4) has a measuring gap of 0.65 mm and a line width of 5 points.

[0025] Table 2

[0026] As shown in the example above, the width of line 48 is... Figure 4 The line widens from left to right; however, aspects of the method disclosed herein can be configured to address the length of the line along the length of each defined segment, having a varying measurement gap width. A controller (e.g., controller 18) can be configured to control the dispensing units (e.g., dispensing units 14, 16 and dispensing unit racks (e.g., rack 24)) to dispense material lines through each segment of line 48 (e.g., segments No. 1-4).

[0027] In the illustrated embodiment, during the dispensing operation, as the width of line 48 increases, the bench (e.g., bench 24) is configured by the controller to move at a slower speed, while the dispensing units (e.g., dispensing units 14 or 16) dispense at a continuous rate. The larger the line width, the slower the bench speed; conversely, the smaller the line width, the faster the bench speed. The speed at which the bench moves depends on the amount of material being dispensed. Other factors may be considered. As used herein, revolutions per minute (RPM) or Hz can be used to define the number of dispensing points per second. As shown in the table above, a single command can be provided to perform the dispensing operation on all four segments, or a separate command can be provided for each segment. The latter will result in each segment having a different RPM and therefore a different moving speed.

[0028] Therefore, for Figure 4 As shown in the example in Table 2, the test bench is configured to move the dispensing unit at a relatively high speed to dispense two points in the first segment (segment No. 1), three points in the second segment (segment No. 2) at a relatively slower speed, four points in the third segment (segment No. 3) at an even slower speed, and five points in the fourth segment (segment No. 4) at an even slower speed. The rate at which the dispensing unit dispenses material points is 100 Hz, therefore the speed of the test bench is adjusted accordingly.

[0029] In other embodiments, the rate at which the points are dispensed by the dispensing unit can be varied to accommodate segments with different gap widths. As described above, in one embodiment, the volume of material dispensed is controlled by varying the speed of the stand with the dispensing units (e.g., dispensing units 14 or 16). However, in another embodiment, the rate at which the dispensing unit dispenses the points can be modified based on the measured gap within the segment to vary the number of points dispensed in that segment. This is achieved while maintaining a constant speed of the dispensing units on the stand. Thus, in this embodiment, the rate at which the dispensing unit dispenses material is two points in the first segment at a relatively slow rate, three points in the second segment at a relatively high rate, four points in the third segment at a further relatively high rate, and five points in the fourth segment at an even higher rate.

[0030] In some embodiments, the line to be assigned is divided into four or five segments, each with a length between 4 mm and 5 mm. The gap width is measured for each segment. Based on the measured gap width, multiple points are selected to be assigned to each gap.

[0031] In some embodiments, each image consists of pixels, where each pixel is the smallest image element that the visual system can uniquely identify and interpret as black or white with gray shading.

[0032] Various controllers, such as controller 18, can perform the various operations discussed above. Using data stored in associated memory and / or storage devices, controller 18 also executes one or more instructions stored on one or more non-transitory computer-readable media, which controller 18 may include and / or be coupled to, such non-transitory computer-readable media, to obtain operational data. In some examples, controller 18 may include one or more processors or other types of controllers. In one example, controller 18 is or includes at least one processor. In another instance, controller 18 uses an application-specific integrated circuit (ASIC) to perform at least a portion of the operations described above, the ASIC being customized to perform specific operations as an alternative to or addition to a general-purpose processor. As these examples show, examples of this disclosure can use many specific combinations of hardware and software to perform the operations described herein, and this disclosure is not limited to any specific combination of hardware and software components. Examples of this disclosure may include computer program products configured to perform the methods, processes, and / or operations discussed above. Computer program products may be or include one or more controllers and / or processors configured to execute instructions to perform the methods, processes, and / or operations discussed above.

[0033] Therefore, having described several aspects of at least one embodiment of this disclosure, it should be understood that various changes, modifications, and improvements will readily occur to those skilled in the art. Such changes, modifications, and improvements are intended to be part of this disclosure and are intended to fall within the spirit and scope of the invention. Therefore, the foregoing description and drawings are merely illustrative.

[0034] What is required is...

Claims

1. A method for depositing material on an electronic substrate, said electronic substrate having a type of dispensing system, comprising: frame; A distribution unit rack, which is movably connected to the frame; A dispensing unit, connected to a dispensing unit rack, configured to deposit material onto the electronic substrate during a dispensing operation; A vision system rack, which is connected to the frame; The method includes a vision system coupled to a vision system rack, the vision system being configured to acquire one or more images of the electronic substrate having two adjacent features prior to performing the assignment operation, the method comprising: Acquire images of the first feature of the first component and the adjacent second features of the second component; Execute a measurement command to measure the actual distance between the first feature of the first component and the second feature of the second component; The length of the gap is divided into multiple segments to determine the gap width of each segment; Based on the gap width, determine the number of points to be allocated by the allocation unit for each segment; and Perform the allocation operation for each segment.

2. The method according to claim 1, wherein, The number of points to be determined is limited by a table of points to be assigned based on the gap width.

3. The method of claim 1, wherein performing the allocation operation includes controlling the speed of the rack to allocate a desired number of points within the corresponding segment.

4. The method of claim 3, wherein performing the allocation operation further comprises controlling the rate at which the points allocated by the allocation unit are at a rate substantially consistent along the length of the gap.

5. The method of claim 1, wherein performing the allocation operation includes controlling the rate at which points are allocated by the allocation unit to allocate a desired number of points within the corresponding segment.

6. The method of claim 5, wherein performing the allocation operation further comprises controlling the speed of the rack to be substantially consistent along the length of the gap.

7. The method according to claim 1, wherein, Each image consists of pixels, where each pixel is the smallest image element that the visual system can uniquely identify and interpret as black or white with gray shading.

8. The method of claim 1, further comprising determining whether the actual gap is less than a predetermined minimum limit, and if it is less than the predetermined minimum limit, then not performing any action.

9. A computer-readable medium including instructions that, when executed by a computer, cause the computer to perform the following methods: Acquire images of the first feature of the first component and the adjacent second features of the second component; Execute a measurement command to measure the actual distance between the first feature of the first component and the second feature of the second component; The length of the gap is divided into multiple segments to determine the gap width of each segment; Based on the gap width, determine the number of points to be allocated by the allocation unit for each segment; as well as Perform the allocation operation for each segment.

10. The computer-readable medium according to claim 9, wherein, The number of points to be determined is limited by a table of points to be assigned based on the gap width.

11. The computer-readable medium of claim 9, wherein performing the allocation operation includes controlling the speed of the rack to allocate a desired number of points within the corresponding segment.

12. The computer-readable medium of claim 11, wherein performing the allocation operation further comprises controlling the rate at which the points allocated by the allocation unit are at a substantially consistent rate along the length of the gap.

13. The computer-readable medium of claim 9, wherein performing the allocation operation includes controlling the rate at which points are allocated by the allocation unit to allocate a desired number of points within a corresponding segment.

14. The computer-readable medium of claim 13, wherein performing the allocation operation further comprises controlling the speed of the rack to be substantially consistent along the length of the gap.

15. The computer-readable medium according to claim 9, wherein, Each image consists of pixels, where each pixel is the smallest image element that the visual system can uniquely identify and interpret as black or white with gray shading.

16. The computer-readable medium of claim 9, further comprising determining whether the actual gap width is less than a predetermined minimum limit, and if it is less than the predetermined minimum limit, then not performing any action.

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