System and method for improving reliability of item replacement in a stencil printer

Abstract

The mobile cart includes a housing configured to move along a horizontal plane and a plurality of shelves supported by the housing. Each shelf of the plurality of shelves is configured to move between a retracted position in which the shelf is positioned within the housing and an extended position in which the shelf extends from the housing. The mobile cart further includes a sensing system configured to determine whether each shelf of the plurality of shelves is in the retracted position and the type of item supported by the shelf. Other aspects of the mobile cart are further disclosed.

Description

[Technical Field]

[0001] This application relates generally to stencil printers and related methods for printing viscous materials, such as solder paste, onto electronic substrates, such as printed circuit boards (PCBs), and more particularly to systems and methods for replacing items in stencil printers. [Background technology]

[0002] In manufacturing surface mount printed circuit boards, a stencil printer can be used to print solder paste onto the circuit board. Typically, a circuit board having a pattern of pads or some other conductive surface onto which the solder paste will be deposited is automatically fed into the stencil printer, and one or more small holes or marks (known as "fiducials") on the circuit board are used to properly align the circuit board with the stencil printer's stencil or screen before printing the solder paste onto the circuit board. In some systems, an optical alignment system embodying a vision system is used to align the circuit board with the stencil.

[0003] In such printers, once the circuit board is properly aligned with the stencil, it is raised up to the stencil and solder paste is dispensed onto the stencil. A wiper blade (i.e., squeegee) moves across the stencil, forcing the solder paste through the holes in the stencil and onto the circuit board. As the squeegee moves across the stencil, the solder paste tends to spread out in front of the blade. This desirably mixes and shears the solder paste to achieve the desired viscosity to facilitate filling the holes in the screen or stencil. The solder paste is typically dispensed onto the stencil from a standard cartridge. The stencil is then separated from the circuit board, and the majority of the material remains on the circuit board due to the adhesion between the circuit board and the solder paste. The material remaining on the surface of the stencil is removed in a cleaning process before additional circuit boards are printed.

[0004] Another process in printing circuit boards involves inspecting the circuit board after the solder paste has been deposited on the surface of the circuit board. Inspecting the circuit board is important to determine whether a clean electrical connection can be made. Too much solder paste can cause a short circuit, while too little solder paste in the right location can prevent electrical contact. Typically, a visual inspection system is also utilized to provide two-dimensional or three-dimensional inspection of the solder paste on the circuit board.

[0005] Modern stencil printers require manual intervention to perform routine operations. For example, during changeover, an operator must perform many manual tasks, such as changing stencils, replacing solder paste cartridges, replacing squeegee blades, and replacing support tooling. Each of these tasks requires the operator to perform the task manually. For example, in most stencil printers, the operator must unlock the stencil, remove the stencil, properly insert the replacement stencil, and lock the replacement stencil in place. Changeover operations can take as long as 30 minutes, during which time the stencil printer is not operational, potentially resulting in an idle PCB fabrication line. Summary of the Invention

[0006] One aspect of the present disclosure relates to a mobile cart comprising a housing configured to move along a horizontal plane and a plurality of shelves supported by the housing, each shelf of the plurality of shelves configured to move between a retracted position in which the shelf is positioned within the housing and an extended position in which the shelf extends from the housing, the mobile cart further comprising a sensing system configured to determine whether each shelf of the plurality of shelves is in the retracted position and the type of item supported by the shelf.

[0007] The mobile cart embodiment may further include configuring the sensing system with at least one sensor coupled to the housing and at least one flag coupled to the housing for each shelf. The sensing system may include, for each shelf, a first sensor associated with a first flag positioned at an upper location relative to the shelf and a second sensor associated with a second flag positioned at a lower location relative to the shelf. When the shelf is in the retracted position within the housing of the mobile cart, the sensors may be configured to return one of the following signals: "Top low (off), bottom low (off) = shelf empty," "Top high (on), bottom low (off) = loaded tool tray," "Top low (off), bottom high (on) = unloaded tool tray," and "Top high (on), bottom high (on) = stencil." The first and second sensors may be further configured to generate signals indicating whether the item is fully inserted into the respective shelf.

[0008] Another aspect of the present disclosure relates to a method for determining whether a shelf of a mobile cart is in a retracted position. In one embodiment, the method includes sensing a flag associated with the shelf to determine the position of the shelf.

[0009] Embodiments of the method may further include providing a first sensor associated with a first flag positioned at an upper location relative to the shelf and a second sensor associated with a second flag positioned at a lower location relative to the shelf. When the shelf is in the retracted position within the housing of the mobile cart, the sensors may be configured to return one of the following signals: "Top low (off), bottom low (off) = shelf empty," "Top high (on), bottom low (off) = loaded tool tray," "Top low (off), bottom high (on) = unloaded tool tray," and "Top high (on), bottom high (on) = stencil." The first and second sensors may be further configured to generate signals indicating whether the item is fully inserted into the respective shelf.

[0010] Yet another aspect of the present disclosure relates to a system for mechanically and electrically coupling a movable cart to a stencil printer, the stencil printer having at least one item of a plurality of items for replacement within the stencil printer, the stencil printer including a docking station configured to receive the movable cart, the movable cart configured to receive used items and / or provide new items to the stencil printer. In one embodiment, the system includes a first interface panel associated with one of the stencil printer and the movable cart. The first interface panel includes a latch magnet and an array of metal pads. The system further includes a second interface panel associated with the other of the stencil printer and the movable cart. The second interface panel includes a metal plate and an array of contacts. When the movable cart is docked to the stencil printer, the latch magnet of the first interface panel is configured to magnetically secure the metal plate of the second interface panel, and the array of contacts of the second interface panel is configured to engage the array of metal pads of the first interface panel.

[0011] An embodiment of the system may further include a third interface panel associated with the stencil printer and spaced apart from the first interface panel, and a fourth interface panel associated with the movable cart and spaced apart from the second interface panel. The first interface panel may be associated with the stencil printer, and the second interface panel may be associated with the movable cart. The metal plate may be a steel plate. The latch magnet of the first interface panel may be configured to communicate with a controller associated with the movable cart or a controller of the stencil printer to control operation of the latch magnet and secure or unlock the movable cart from the stencil printer. The array of contacts may include a plurality of spring contacts. The metal pads may include a plurality of hard gold pads. The system may further include a guide assembly that guides the movable cart to the stencil printer when the movable cart is docked to the stencil printer. The guide assembly may include at least one forward roller fixed to the housing of the movable cart. The at least one forward roller can be configured to contact at least one guide member provided on a surface of the stencil printer. The at least one forward roller can include two spaced-apart forward rollers, and the at least one guide member includes two spaced-apart guide members. The two spaced-apart forward rollers can be configured to contact the two spaced-apart guide members to guide the movable cart relative to the stencil printer.

[0012] Another aspect of the present disclosure relates to a method of mechanically and electrically coupling a movable cart to a stencil printer, the stencil printer having at least one item of a plurality of items for replacement within the stencil printer, the stencil printer including a docking station configured to receive the movable cart, the movable cart configured to receive used items and / or provide new items to the stencil printer. In one embodiment, the method includes providing a first interface panel associated with one of the stencil printer and the movable cart, the first interface panel including a latch magnet and an array of metal pads, and providing a second interface panel associated with the other of the stencil printer and the movable cart, the second interface panel including a metal plate and an array of contacts, magnetically securing the metal plate of the second interface panel with the latch magnet of the first interface panel, and engaging the array of metal pads of the first interface panel with the array of contacts of the second interface panel.

[0013] An embodiment of the method may further include a third interface panel associated with the stencil printer and spaced apart from the first interface panel, and a fourth interface panel associated with the movable cart and spaced apart from the second interface panel. The first interface panel may be associated with the stencil printer, and the second interface panel may be associated with the movable cart. The latch magnet of the first interface panel may be configured to communicate with a controller associated with the movable cart or a controller of the stencil printer to control operation of the latch magnet to secure or unlock the movable cart from the stencil printer. The method may further include guiding movement of the movable cart to the stencil printer when docking the movable cart to the stencil printer. Guiding movement of the movable cart may further include a guide assembly having at least one forward-facing roller fixed to a housing of the movable cart. The at least one forward-facing roller may be configured to contact at least one guide portion provided on a surface of the stencil printer. The at least one forward roller may include two spaced-apart forward rollers, and the at least one guide portion may include two spaced-apart guide portions, and the two spaced-apart forward rollers may be configured to contact the two spaced-apart guide portions to guide the movable cart relative to the stencil printer.

[0014] Another aspect of the present disclosure relates to a system for measuring assembly material within a cartridge tube of a stencil printer including a carousel configured to support at least one cartridge tube. In one embodiment, the system includes a laser height sensor coupled to a frame of the stencil printer. The laser height sensor is positioned above the at least one cartridge tube and configured to generate a laser beam directed toward the at least one cartridge tube to determine the height of assembly material within the at least one cartridge tube.

[0015] Another aspect of the present disclosure relates to a method for measuring assembly material in a cartridge tube of a stencil printer including a carousel configured to support at least one cartridge tube. In one embodiment, the method includes sensing a height of assembly material in the at least one cartridge tube supported by the carousel, providing a warning to replace the at least one cartridge tube with a new cartridge tube if the at least one cartridge tube is determined to be empty, and continuing to use the at least one cartridge tube if the at least one cartridge tube is determined to have a sufficient amount of assembly material.

[0016] Embodiments of the method may further include sensing the height of the assembly material by a laser height sensor coupled to a frame of the stencil printer. The laser height sensor may be positioned above the at least one cartridge tube and configured to generate a laser beam toward the at least one cartridge tube to determine the height of the assembly material within the at least one cartridge tube. The method may further include calibrating the laser height sensor to determine a zero reference position.

[0017] The accompanying drawings are not intended to be drawn to scale. In the drawings, each identical or nearly identical component shown in various figures is represented by a like reference numeral. For clarity, not every component may be labeled in every drawing. [Brief explanation of the drawings]

[0018] [Figure 1] FIG. 2 is a front perspective view of the stencil printer. [Figure 2] FIG. 2 is a front view of the stencil printer. [Figure 3] FIG. 3 is a top view, with portions removed, of the stencil printer shown in FIG. 2. [Figure 4] FIG. 1 is a perspective view of a mobile cart according to an embodiment of the present disclosure. [Figure 5] FIG. 1 is an enlarged perspective view of a mobile cart with portions removed to reveal aspects of the mobile cart, particularly a sleeve or shelf of the mobile cart in a home position. [Figure 6] FIG. 1 is an enlarged perspective view of a mobile cart with portions removed to reveal aspects of the mobile cart, particularly a sleeve or shelf of the mobile cart in a home position. [Figure 7] FIG. 10 is an enlarged perspective view of the upper and lower pivoting flags and sensors of the mobile cart; [Figure 8] FIG. 1 is a perspective view of a magnetic lock used to secure the movable cart to the stencil printer. [Figure 9] FIG. 2 is a top view of the movable cart and stencil printer prior to docking of the movable cart to the stencil printer. [Figure 10] FIG. 10 is an enlarged perspective view of the latch magnet. [Figure 11] FIG. 10 is a side view of the movable cart showing the alignment sensor and mating features of the movable cart. [Figure 12] FIG. [Figure 13] FIG. [Figure 14] FIG. 10 is a perspective view of a first connector half having multiple spring contacts provided in a stencil printer. [Figure 15] FIG. 10 is a front view of a second connector half having multiple pads. [Figure 16] FIG. 10 is a perspective view of a laser sensor used to determine the level of material in the material cartridge tube. [Figure 17] FIG. 1 is a perspective view of a stencil printer with portions removed to show a laser sensor positioned to sense the level of material in the material cartridge tube. [Figure 18] FIG. 1 is a perspective view of a stencil printer with portions removed to show a laser sensor positioned to sense the level of material in the material cartridge tube. [Figure 19] FIG. [Figure 20] FIG. 1 is a perspective view of a bending force sensor. [Figure 21] FIG. 10 is a perspective view of a drive mechanism used to extend and retract the shelves of the movable cart. [Figure 22] 22 is a perspective view of a shelf of a movable cart including a drive bar of the drive mechanism shown in FIG. 21. [Figure 23] FIG. 10 is another perspective view of a drive mechanism having a drive bar. [Figure 24] FIG. 10 is another perspective view of the drive mechanism showing the home sensor. [Figure 25] FIG. 10 is another perspective view of the drive mechanism. DETAILED DESCRIPTION OF THE INVENTION

[0019] The present disclosure relates generally to material dispensing machines (referred to herein as "stencil printers," "screen printers," "printers," or "printers") and other equipment utilized in surface mount technology (SMT) process lines and configured to dispense assembly materials (e.g., solder paste, conductive ink, or encapsulant) onto substrates (e.g., printed circuit boards, referred to herein as "electronic boards," "circuit boards," "boards," "PCBs," "PCB substrates," "substrates," or "PCB plates") or to perform other operations such as inspection, rework, or placement of electronic components onto substrates. Specifically, embodiments of the present disclosure are described below with reference to stencil printers used to fabricate printed circuit boards.

[0020] By way of example only and not limitation, the present disclosure will now be described in detail with reference to the accompanying drawings. The present 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 described in this disclosure may be used in other embodiments and may be practiced or carried out in various ways. Furthermore, the phraseology and terminology used herein are for purposes of description and should not be considered limiting. Any reference to system and method examples, embodiments, components, elements, or operations referred to in the singular herein can also encompass embodiments that include the plural, and any reference to any embodiment, component, element, or operation referred to in the plural herein can also encompass embodiments that include only the singular. References in the singular or plural are not intended to limit the systems or methods, their components, operations, or elements disclosed herein. The use of the terms "including," "comprising," "having," "containing," "with," and variations thereof herein is meant to encompass the items listed thereafter, as well as equivalents thereof and additional items. References to "or / or" may be construed as inclusive such that any term described with "or / or" may refer to any of one, more than one, and all of the described terms. Additionally, in the event of an inconsistency in the usage of a term between this application document and a document incorporated by reference, the usage of the term in the document incorporated by reference is supplementary to the usage in this application document, and in the event of an inconsistency resulting in a conflict, the usage of the term in the application document shall control.

[0021] For illustrative purposes, the following embodiments of the present disclosure will be described with reference to a stencil printer used to print assembly materials, such as solder paste, onto circuit boards. However, those skilled in the art will appreciate that the present disclosure is not limited to stencil printers that print solder paste onto circuit boards, but can also be used in other applications requiring the dispensing of other adhesive assembly materials, such as glues and encapsulants. For example, the device can be used to print epoxies used as underfill for chip-scale packages. Furthermore, the stencil printers of the present disclosure are not limited to those that print assembly materials onto circuit boards, but also include those used to print other materials onto various substrates, such as semiconductor wafers. Additionally, the terms screen and stencil are used interchangeably herein to describe devices within the printer that define the pattern printed on the substrate. In certain embodiments, the stencil printer may include a Momentum™ or Edison™ series stencil printer platform offered by ITW Electronic Assembly Equipment of Hopkinton, Massachusetts. An exemplary stencil printer is generally designated 5 in FIG. 1 . In this embodiment, the stencil printer 5 is a Momentum™ series stencil printer platform offered by ITW Electronic Assembly Equipment of Hopkinton, Massachusetts.

[0022] 2, a stencil printer according to an embodiment of the present disclosure is generally indicated at 10. As shown, the stencil printer 10 has a frame 12 that supports the stencil printer's components, which may include, in part, a controller 14, a display 16, a stencil 18, and a printhead or printhead assembly. The printhead or printhead assembly is generally indicated at 20 and is configured to apply solder paste in a manner described in more detail below.

[0023] As shown in FIG. 2 and described below, the stencil and printhead assembly can be coupled or otherwise connected to frame 12, as appropriate. In one embodiment, printhead assembly 20 can be mounted on printhead assembly gantry 22, which can be mounted on frame 12. Printhead assembly gantry 22 allows printhead assembly 20 to move in the y-axis direction under the control of controller 14 and to engage stencil 18 to apply pressure to the printhead assembly. In one particular embodiment, printhead assembly 20 can rest above stencil 18 and can be lowered in the z-axis direction to contact and sealingly engage the stencil.

[0024] Stencil printer 10 may also have a conveyor system having rails (not shown) for transporting printed circuit boards (sometimes referred to herein as "printed wiring boards," "boards," or "electronic boards") to a printing position within the stencil printer. The rails may be referred to herein as a "tractor feed mechanism." The tractor feed mechanism is configured to feed, load, or otherwise deliver circuit boards to and from a work area of the stencil printer, sometimes referred to herein as a "print nest."

[0025] 3 , the stencil printer 10 includes a support assembly 28 that supports a circuit board 29 (shown in dashed lines). The support assembly 28 elevates and secures the circuit board so that it is stable during printing operations. In certain embodiments, the substrate support assembly 28 can further include a specific substrate support system, such as a rigid support, multiple pins, or flexible tooling, that is positioned below the circuit board when it is in the printing position. The substrate support system can be used in part to support an interior region of the circuit board to prevent bending or warping of the circuit board during printing operations.

[0026] In one embodiment, the printhead assembly 20 can be configured to receive solder paste from a supply source, such as a dispenser, e.g., a solder paste cartridge, that provides the solder paste to the printhead assembly during printing operations. Instead of cartridges, other methods of supplying solder paste can be utilized. For example, the solder paste can be manually deposited between blades or from an external source. Additionally, in certain embodiments, the controller 14 can be configured to control the operation of the stencil printer 10 using application-specific software using a personal computer having a suitable operating system, such as the Microsoft Windows® operating system provided by Microsoft Corporation. The controller 14 can be networked with a master controller used to control a production line for fabricating circuit boards.

[0027] In one configuration, the stencil printer 10 operates as follows: A circuit board 29 is loaded into the stencil printer 10 using conveyor rails. The support assembly 28 raises and secures the circuit board 29 in the printing position. The printhead assembly 20 is then lowered in the z-axis direction until the printhead assembly blade contacts the stencil 18 with the desired pressure. The printhead assembly 20 is then moved in the y-axis direction across the stencil 18 by the printhead assembly gantry 22. The printhead assembly 20 deposits solder paste onto the circuit board 29 through the holes in the stencil 18. Once the printhead assembly has completely traversed the stencil 18 across the holes, the printhead assembly is lifted from the stencil, and the circuit board 29 is lowered back onto the conveyor rails. The circuit board 29 is then released and transported from the stencil printer 10, allowing a second circuit board to be loaded into the stencil printer. To print on the second circuit board 29, the printhead assembly is lowered in the z-axis direction into contact with the stencil and moved across the stencil 18 in the opposite direction to that used for the first circuit board.

[0028] An imaging system 30 can be provided for the purposes of aligning the stencil 18 with respect to the circuit board 29 before printing and inspecting the circuit board after printing. In one embodiment, the imaging system 30 can be disposed between the stencil 18 and the support assembly 28 on which the circuit board is supported. The imaging system 30 is coupled to an imaging gantry 32 for moving the imaging system. In one embodiment, the imaging gantry 32 can be coupled to the frame 12 and have a beam extending between the side rails of the frame 12, providing back and forth movement of the imaging system 30 above the circuit board 29 in the y-axis direction. The imaging gantry 32 can further include a carriage device that houses the imaging system 30 and is configured to move along the length of the beam in the x-axis direction. The structure of the imaging gantry 32 used to move the imaging system 30 is known in the art of solder paste printing. The imaging system 30 is configured to be positioned anywhere below the stencil 18 and above the circuit board 29 to capture images of predetermined areas of the circuit board or stencil, respectively.

[0029] After one or more applications of solder paste to the circuit board, excess solder paste may accumulate on the bottom of the stencil 18, and a stencil wiper assembly, generally indicated at 34, may travel underneath the stencil to remove the excess solder paste. In other embodiments, the stencil 18 may travel above the stencil wiper assembly.

[0030] As mentioned above, stencil printers have traditionally required manual intervention to replace and / or replenish certain parts. For example, a typical stencil requires replacement after a certain period of time, e.g., four hours. Stencils also require replacement for separate production runs. Additionally, solder paste cartridges, which supply temperature-controlled solder paste to stencil printers, require replacement over time, e.g., within four hours. Separate production runs may require different types of solder paste material. Another item requiring periodic replacement is the squeegee blade, which wears out with use. And finally, tooling used to support the substrate at the print station is replaced when changing from one production run to another.

[0031] Embodiments of the present disclosure relate to a delivery system configured to automate the changeover process for stencil printers or any other type of assembly processing equipment, including, but not limited to, dispensers, pick-and-place machines, wave and selective soldering machines, reflow ovens, cleaners, and inspection machines. In one embodiment, the delivery system includes a movable cart configured to engage the stencil printer and supply and receive replacement and replenishment parts and materials to the stencil printer for changeover. For example, the stencil printer can include a docking station configured to receive the movable cart. The docking station can have an interface that allows the movable cart to communicate with the stencil printer. A single movable cart can be configured to include a changeover stencil, a replacement stencil, a replacement solder paste cartridge, a replenishment solder paste cartridge, a replacement squeegee blade, a replenishment squeegee blade, and replacement support tooling. During changeover, for example, the stencil printer must be reconfigured to produce a different item. Thus, for example, different types of solder paste may be employed within the stencil printer to produce different products.

[0032] It should be understood that the concepts described herein are not limited to replacing items in stencil printers, but apply to the other types of equipment described above as well.

[0033] The changeover process described herein may be accomplished with a single mobile cart configured to replace and / or replenish each item. In other embodiments, two or more mobile carts may be provided. For example, a mobile cart may be configured to support a predetermined number of stencils, squeegee blades, tooling, and paste cartridges selected for a production run expected on a particular day or during a particular time period. The mobile cart and / or stencil printer may be configured to identify items for replacement, transport the items to and from the stencil printer, inspect the items, and interface with the stencil printer. The mobile cart may also be configured to remove (dismount, remove) used items from the stencil printer. Additionally, the mobile cart may be configured for long-term storage of items.

[0034] For paste cartridges, the mobile cart and / or stencil printer may be configured to identify the paste cartridge, store the paste cartridge in an appropriate environment, transport the paste cartridge to and from the stencil printer and dispenser, inspect the paste cartridge, and interface with the stencil printer. The mobile cart may also be configured to remove used parts, such as paste cartridges, from the stencil printer and dispenser. Additionally, the mobile cart may be configured for long-term storage of the paste cartridge. In one embodiment, long-term storage of solder paste may be achieved by refrigeration between 0°C and 10°C (32°F and 50°F). The paste cartridge may be stored in a location in the mobile cart to maintain this temperature range. In another embodiment, the mobile cart may be configured to preheat the paste cartridge prior to use, preparing the cartridge for use in the stencil printer.

[0035] Referring to FIG. 4 , in one embodiment, a mobile cart, generally designated 100, includes a frame or housing 102 configured to support replacement and / or replenishment items. As shown, the housing 102 of the mobile cart 100 is generally rectangular and is supported on wheels or casters, each designated 104. In one embodiment, the mobile cart 100 is configured to be moved manually by an operator by pushing the housing 102 of the mobile cart. In this embodiment, the mobile cart 100 may be configured with a push bar or handle 106. In another embodiment, the mobile cart 100 is configured to be moved automatically by remote control or by an automated controller associated with the mobile cart, the stencil printer 10, the production line, and / or some other dedicated controller. In this embodiment, the mobile cart 100 may include wheels driven by a suitable motor and drive train and a controller associated with the mobile cart. Alternatively, in other embodiments, the controller may be associated with the stencil printer 10, the production line, and / or some other dedicated controller configured to control the mobile cart. The mobile cart 100 may further include one or more sensors and / or vision systems, such as cameras, to guide the mobile cart from the storage room to, for example, the stencil printer 10 .

[0036] In one embodiment, the mobile cart includes one or more shelves, each indicated generally at 110, configured to store items for the stencil printer 10. For example, the shelves 110 may be specifically designed to support stencils, such as stencil 18, and / or tooling trays, each indicated generally at 112. As shown, the mobile cart 100 supports a single stencil 18 on one shelf 110 and two tooling trays 112 on two shelves 110 located above the shelf 110 supporting the stencil. The shelves 110 may be configured to move vertically within the housing to achieve a height suitable for operation with the stencil printer 10. In one embodiment, the shelves 110 are mounted within a carriage, which is designed to move up and down within the housing 102 of the mobile cart 100. Additionally, the shelves 110 may be configured to extend and retract within the housing 102 of the mobile cart 100. Specifically, each shelf 110 may be configured to extend from the housing 102 to transfer items to or receive items from the stencil printer, and possibly to present a stencil 18 or tooling tray 112 to the stencil printer. Figure 4 shows the shelf 110 extending the stencil 18 and tooling tray 112. When extended, the shelf 112 is configured to retract back into the housing 102 of the mobile cart 100.

[0037] In some embodiments, some shelves 110 may be designated as "clean shelves" that support clean or new items ready to be used in the stencil printer 10. Some shelves 110 may be designated as "unclean shelves" that support used items to be removed from the stencil printer 10. The shelves 110 may be spaced a specific distance from each other to accommodate various items. For example, the shelves 110 may be spaced 3 / 8 inch (approximately 9.5 mm) to 1 1 / 2 inches (approximately 38.1 mm) from each other to accommodate the thickness of the stencil frame.

[0038] 4 is shown fully loaded for automated transfer of items to and from the stencil printer. Specifically, as described above, the mobile cart 100 includes a new stencil 18 and two tooling trays 112, one tray full of items including squeegee blades and tooling, and the other tray empty for receiving used items from the stencil printer.

[0039] The mobile cart 100 may be configured with both a mechanical interface and an electronics communication interface designed to dock within a docking station provided on the stencil printer 10. In certain embodiments, the mobile cart 100 may be configured with a unique mechanical interface that mates with the stencil printer 10's unique mechanical docking station. The unique mechanical interface / docking station may include geometric features. In another embodiment, the mobile cart 100 may be configured with pins that are received within guides associated with the stencil printer 10 to align the mobile cart with the stencil printer prior to fully docking the mobile cart. Other types of guides, such as electrical / magnetic guides, visual guides, sensors, latches, etc., may also be used. When docked within the stencil printer 10's docking station, the mobile cart 100 may physically engage with the stencil printer or may be spaced apart from the stencil printer.

[0040] As shown in FIG. 4 , the mobile cart 100 includes two spaced-apart roller assemblies, each designated 116, designed to interact with features associated with a stencil printer, such as stencil printer 10, to guide the mobile cart to a docking position. Each roller assembly 116 includes an arm extending from the mobile cart housing 102 and a roller coupled to the arm at the end of the arm. The roller assemblies 116 are positioned to engage features formed in the stencil printer when the mobile cart 100 is docked to the stencil printer. Additionally, the mobile cart 100 includes two interface panels, each designated 118, that provide mechanical connection and electrical communication between the mobile cart 100 and the stencil printer. A description of the interface panels 118 is provided in more detail below.

[0041] 5 and 6, as described above, mobile cart 100 includes shelf 110 that is fully retracted within mobile cart housing 102 in the home position. The manner in which the shelf operates to extend and retract within mobile cart housing 102 is described below with reference to FIGS. 21-25.

[0042] A sensor system is provided to determine the location and type of item contained by each shelf 110. Specifically, each shelf 110 is sized and shaped to support generally planar items, such as stencils 18 or tooling trays 112. The sensor system is designed to notify the operator of the type of item contained within the shelf 110, such as a stencil 18 or tooling tray 112, and whether the item is fully received within the shelf in what may be referred to as a home position. For each shelf, the sensor system includes two sensors, upper sensor 120A and lower sensor 120B, and two pivot flags, upper pivot flag 122A and lower pivot flag 122B, which may be provided to indicate when each shelf 110 is in its home or fully retracted position. With further reference to FIG. 7 , the contents of each shelf 110 of the four cart shelves are known and verified prior to and during transfer to or from the stencil printer. In one embodiment, two optical sensors 120A, 120B and two pivoting flags 122A, 122B are mounted in the housing 102 of the mobile cart 100. For each shelf, a first sensor 120A is associated with the first flag 122A and is positioned at an upper location relative to the shelf, and a second sensor 120B is associated with the second flag 122B and is positioned at a lower location relative to the shelf. In the illustrated embodiment, there are four shelves, with the first (upper) shelf shown empty, the second shelf positioned below the first shelf shown with a loaded (loaded) tooling tray, the third shelf positioned below the second shelf shown with an unloaded tooling tray, and the fourth (lower) shelf shown with a stencil. When shelf 110 is in its home position, each type of item, such as stencils 18 or tooling trays 112 (loaded and unloaded), will engage pivot flags 122A and / or 122B differently due to their geometric shapes. Therefore, when shelf 110 is in its home position within housing 102 of mobile cart 100, sensor 120 will return one of the following signals: "Top row (off), bottom row (off) = empty shelves" "Top high (on), bottom low (off) = loading tool tray", "Upper low (off), lower high (on) = non-loading tool tray", and "Top high (on), bottom high (on) = stencil."

[0043] This method is also useful for ensuring that the operator properly inserts the stencil 18 and / or tooling tray 112 into the shelf 110 and does not protrude too far, which could cause interference with the stencil printer during the transfer process.

[0044] The roller assembly 116 may be employed to facilitate pre-alignment and ease of use of the method of docking the mobile cart 100 to the stencil printer.

[0045] Specifically, roller assembly 116 ensures that there is no unintended movement of mobile cart 100 in the x-, y-, and z-axes when the mobile cart is docked with the stencil printer.

[0046] As described herein, the mobile cart 100 is used to transport new supplies to the stencil printer and is coupled or otherwise connected to the stencil printer to transfer items from the mobile cart to the stencil printer. When the mobile cart 100 is pre-positioned to engage the stencil printer, it is pre-aligned with respect to the stencil printer to facilitate power and electronic communication between the mobile cart and the stencil printer.

[0047] 9, in one embodiment, the moveable cart 100 has two forward-facing rollers 116, one roller assembly located on the lower left side of the moveable cart housing 102 and the other roller assembly located on the lower right side of the moveable cart housing. The roller assemblies 116 are positioned to contact guides, each indicated at 130, on the face of the stencil printer 10 to pre-align the moveable cart 100 in the x-axis direction.

[0048] The mobile cart 100 is then pushed further forward until the steel plates, each designated 134, are positioned on the interface panel 118 located on the lower left side of the mobile cart, and the other steel plate 134 is positioned on the interface panel 118 located on the lower right side of the mobile cart, as shown in FIG. 4. Each steel plate 134 comes into contact with a magnetic field generated by a respective latch magnet 136 of the stencil printer, shown in FIG. 8. In one embodiment, the latch magnets 136 included in the stencil printer are electromagnets, Model E300, manufactured by Security Door Controls. The latch magnets 136 eliminate the need for keys and increase the operating range of the access control system.

[0049] Latch magnet 136 is compact and provides a higher level of security than other types of locking devices. Latch magnet 136 is configured to communicate with a controller associated with movable cart 100 or a controller of stencil printer 10, such as controller 14, to control operation of the latch magnet's electromagnet to secure or unlock the movable cart from stencil printer 10. A display, such as display 16 associated with stencil printer 10, may be provided to indicate the status of latch magnet 136, locked or unlocked relative to movable cart 100.

[0050] Each latch magnet 136 is in a "power on" state, ready to asynchronously dock the mobile cart 100 to the stencil printer to maximize stencil printer efficiency and eliminate cycle time impacts. When the mobile cart 100 is fully engaged with the latch magnet 136, software associated with the stencil printer's controller is notified by safety sensors on the left and right sides of the mobile cart to ensure full engagement before power and communications are applied to the mobile cart. One advantage of this configuration is that each electromagnet in the latch magnet has a pulling force of approximately 600 pounds (lbs) and excellent shear resistance, allowing the latch magnet 136 to generate a strong magnetic force to hold the mobile cart 100 in place relative to the stencil printer and prevent movement of the mobile cart in the x-, y-, and z-axes when engaged. This type of latch magnet 136 also has a unique magnetic flux path that allows full force only within 0.010 inches (approximately 0.25 mm) of the steel plate 135 engagement for safety reasons.

[0051] Figure 9 shows the movable cart 100 approaching the stencil printer 10, with the roller assemblies 116 of the movable cart aligned with the respective guide portions 130 of the stencil printer. Figure 10 shows the interface panel 118 with the latch magnets 136 on the stencil printer 10. Figure 11 shows the alignment sensor 138 and steel plate 134 on the movable cart 100.

[0052] When the mobile cart 100 is ready to be replenished (or removed from the stencil printer 10), power is removed from the mobile cart and the latch magnets 136 associated with the stencil printer are de-energized, allowing an operator to move the mobile cart away from the stencil printer. Left and right alignment sensors 138 instruct the software in the controller 14 of the stencil printer 10 to remove the mobile cart 100 from the stencil printer and re-energize the latch magnets 136, ready for the next docking cycle.

[0053] The method of connection between the movable cart 100 and the stencil printer 10 includes two mating connector halves, one connector half having an array of spring-loaded contacts to assist in misalignment, and the other connector half having a complementary array of hard gold pads, specifically gold pads reinforced with nickel for durability, to complete the circuit between the movable cart and the stencil printer.

[0054] The first connector half includes an array of spring contacts. Figure 14 shows a first connector half 144 with an array of spring contacts 146. Exemplary spring contacts 146 are shown in Figures 12 and 13. In the illustrated embodiment, the spring contacts 146 are part number 101247 manufactured by Smiths Interconnect Americas. The first connector half 144 is assembled in an array that is installed in the stencil printer 10 and assists in the event of minor misalignment of the mobile cart 100 due to imperfections in the manufacturing facility beyond the control of the mobile cart manufacturer.

[0055] Deficiencies in facilities include uneven floors or floors that are not rigid enough and allow flooring to collapse.

[0056] The second connector half, having hard gold pads, is mounted and rigidly attached to the mobile cart 100 as part of the interface panel 118. This ensures a smooth and flat interface for the spring-loaded contacts 146 described above. Figure 15 shows the second connector half 150, having an array of hard gold pads, each designated 152. The array of hard gold pads 152 on the second connector half 150 mates with the array of spring contacts on the first connector half.

[0057] When the two connector halves 144, 150 are mated, i.e., when the mobile cart 100 is docked to the stencil printer 10, the two connector halves are first aligned by setting the stencil printer's adjusted height according to SEMA industry standards, and then the mobile cart is mated to the stencil printer. Once mated, an additional step is performed to adjust the final height of the first connector half 144, i.e., the spring contact side, so that the spring contact 146 is centered within approximately 1 millimeter (mm) with the mating hard gold pad 152 of the second connector half 150 on the mobile cart 100. This ensures that any subsequent mobile carts mated to the stencil printer 10 are properly mated and ensures proper connection of all signals passing between the stencil printer and the mobile cart.

[0058] The configuration is such that the two connector halves 144, 150 are laid out to provide a maximum misalignment of ±4 mm along the x-axis, ±2 mm along the y-axis, and ±4 mm along the z-axis, which also corresponds to a roll pitch and yaw flexibility of ±2 degrees.

[0059] Another aspect of the present disclosure relates to a method for measuring material in cartridge tubes for a carousel dispenser. Material cartridge tubes installed in a stencil printer have a finite amount of material in the cartridge tube. As material is used in the stencil printer, it may become necessary to return a cartridge tube that is not completely empty to the material carousel. This creates a problem for an operator to know exactly when to transfer additional material cartridge tubes to the carousel, or for a manufacturing execution system (MES) to track the material used during production. Referring to FIG. 16 , an assembly can utilize a laser height sensor, generally designated 160, to sense the plunger seal in any material cartridge tube to determine how to accurately measure the remaining contents with the material cartridge tube. As shown, the laser height sensor is configured to generate a laser beam 162.

[0060] 17, the stencil printer 10 is configured with a carousel 170 configured to store and deliver paste cartridges, such as paste cartridges or tubes 172, to the stencil printer's printhead assembly 20. A laser height sensor 160 is strategically positioned above the carousel 170 to point downward to sense a zero reference position and is then calibrated. In one embodiment, the laser height sensor 160 is part number Q4XTKLAF600-Q8 manufactured by Banner Engineering Corporation. The electrical output of the laser height sensor 160 is then read by the controller 14 of the stencil printer 10, and the zero reference position is stored.

[0061] 18, when a material cartridge tube 172 is placed in one of the material slots provided in the carousel 170, the carousel will rotate the material cartridge tube to a pick-up location. At the pick-up location, the electrical output of the laser height sensor 160 is read and recorded by the controller 14 of the stencil printer 10 and compared to a zero reference position to determine the content of the material cartridge tube 172.

[0062] If the contents of the material cartridge tube 172 are determined to be empty, that information is sent through the facility's MES system for an operator to replace the cartridge tube 172, and an external indicator flashes to alert any local operators that the material is ready to be replaced. The external indicator may be part of the display 16 of the stencil printer 10. If the material cartridge tube 172 is determined to have enough material for production, that information is used by the controller 14 to determine how many PCBs can be processed before it is emptied and returned to an empty slot position on the carousel.

[0063] An alternative method of determining the remaining volume of the material cartridge tube 172 may be performed by measuring the weight of the cartridge tube. Referring to FIG. 19, a strain gauge 180 may be employed to convert force into an electrical output that is read by the controller 14 of the stencil printer 10 to determine the weight of the material cartridge tube 172 in the slot of the carousel 170. An example of a type of force gauge that can be utilized is a linear strain gauge. In one embodiment, the strain gauge 180 may be model number MMF403994 manufactured by Vishay Precision Group. Referring to FIG. 20, a bending force sensor 182 may be used in place of the strain gauge 180. In this embodiment, the bending force sensor 182 may be model number A101 manufactured by Tekscan.

[0064] 21 and 22, the mobile cart 100 includes a drive mechanism, generally designated 200, configured to move each shelf 110 laterally, thereby enabling the shelf to be extended into and retracted from the stencil printer 10. The drive mechanism 200 includes a motor-driven lead screw 202 for extending and retracting each shelf 110 of the mobile cart 100 into and from the stencil printer 10. When the mobile cart 100 is raised to the appropriate height, a drive button 204 (FIG. 21) engages a drive bar 206 (FIG. 22) attached to the side of each shelf 110. When the lead screw 202 is rotated, the drive button 204 on each side of the shelf either pushes the drive bar 206 and the shelf 110 out of the mobile cart 100 or retracts the drive bar and shelf into the mobile cart, depending on the direction of rotation of the lead screw.

[0065] 23, drive mechanism 200 includes a bracket 208 on each side of shelf 110 to which drive button 204 is secured. Bracket 208 is secured to linear bearings 210 and lead screw 202 such that the bracket moves laterally when the lead screw is rotated. Drive bar 206 is attached to bracket 208 to allow movement of the drive bar and shelf 110.

[0066] Referring to FIG. 24, a home sensor 212 is provided to determine whether the drive bar 206 and shelf 110 are in the home (retracted) position.

[0067] 25, for shelves 110 configured to support a stencil, such as stencil 18, a spring-loaded plunger 214 is provided to ensure that the stencil is properly positioned when it is returned to stencil printer 10. Additionally, a plunger sensor 216 is provided to determine whether the stencil is positioned far enough into shelf 110 that the stencil printer will stop pushing on the stencil when it is returned from stencil printer 10 to mobile cart 100. As its name suggests, plunger sensor 216 monitors spring-loaded plunger 214.

[0068] In one embodiment, the movable cart may be configured with one or more devices used to transfer items from the movable cart to the stencil printer and from the stencil printer to the movable cart. For example, the devices may include grippers to engage items such as substrate tooling trays, move tooling trays from the stencil printer to trays on the movable cart, and move different tooling trays from the movable cart to the stencil printer.

[0069] In one embodiment, the movable cart includes wheels driven by suitable motors and drivetrains, and a controller configured to control movement of the movable cart. The movable cart further includes a power source, such as a battery, for providing power for movement of the movable cart via the motors and drivetrain.

[0070] In some embodiments, the mobile cart includes a controller adapted to control operation of the mobile cart based on operating parameters obtained by the controller. The controller can be configured to communicate with a controller in the stencil printer and / or a controller associated with the production line. In an embodiment having multiple mobile carts, the controller can embody multiple controllers within each mobile cart that communicate with each other via a Controller Area Network (CAN) bus or other type of network. In other embodiments, a master controller can be provided to control operation of the mobile cart controllers. Each mobile cart can include a display operably coupled to the controller. The display can be adapted to display operating parameters of the mobile cart, such as, but not limited to, the number of full and used paste cartridges. A suitable monitor can be provided to obtain such information. Alternatively, or in addition to the above embodiment, the operating parameters can be displayed on a display within the stencil printer and / or a display associated with the production line.

[0071] In other embodiments, the controller may be a dedicated controller for one or more mobile carts.

[0072] In some embodiments, material identification for items on a mobile cart can include a device for manipulating the items and a scanner for scanning and identifying the items. For example, for paste cartridges, the mobile cart can be configured to include a pinch wheel that rotates the paste cartridge so that a code or predetermined identification mark on the paste cartridge aligns with the scanner on the mobile cart. The system can be configured to link the material identification associated with the paste cartridge to a recipe, production time, etc. for a stencil printer. In one embodiment, a barcode can be provided to identify the items. For example, the barcode can include a 1D scanner for UPC codes, a 2D scanner for QRC codes, a printed label affixed to the item, or a laser-etched label etched on the item. In another embodiment, an RFID system can be applied to identify the items. For example, the RFID system can include an RFID tag affixed to the item and an RFID reader associated with the mobile cart. Using an RFID system eliminates the need for a line-of-sight between the reader and the item. Also, scanning is not required to identify all items within the mobile cart. In another embodiment, an imaging or vision system can be applied to identify the items. The vision system can be an imaging system similar to that associated with a stencil printer or dispenser or on a mobile cart.

[0073] In some embodiments, a database is provided to track items stocked on the mobile cart. In one embodiment, the database can include an open application (App) architecture and can be configured to push data to the stencil printer. The mobile cart can be configured to communicate with the stencil printer to push / pull data to the stencil printer and / or the production line, or to communicate directly with the production line. The database can include job information or material information. The database can further communicate with a manufacturing execution system (MES) associated with the production line, the stencil printer, or both. The MES system can be configured to know which materials are needed for a production run. The mobile cart can be configured to communicate with the MES system to coordinate delivery of items to the stencil printer.

[0074] The database can be further configured to retrieve information about the items based on identification information, such as a barcode number. In one embodiment, a central management system can be provided in which the stencil printer and / or mobile cart are programmed to accept material from the mobile cart. The mobile cart is programmed to update the database to identify the material on the mobile cart and load information from the network into a database associated with the mobile cart and / or stencil printer, which information is further linked to an MES system.

[0075] The database may be further configured to store additional information, such as usage and consumption amounts. The database may be configured to store information locally or remotely and may be configured to store data associated with one or more production runs. For example, the database may be configured to capture and store data including, but not limited to, traceability of stencils, paste cartridges, squeegee blades and tooling, paste usage, cycles, etc.

[0076] The database can be configured to share predictive data when replacement / replenishment is necessary. For example, with respect to storing information about paste cartridges, the database may be configured to do one or more of the following: store information about when a paste cartridge needs refilling; perform a specific function when a paste cartridge is low on paste; trigger an alarm and / or report that the paste cartridge is low; signal an inventory management system associated with the stencil printer and / or production line; perform an analysis of consumable usage based on operating parameters and actual usage and upstream / downstream equipment activity; predict replacement or maintenance (for the stencil printer and / or for the mobile cart); and correlate across multiple sites to predict when a paste cartridge should be replaced. The database may also be configured to share predictive data about other changeable / consumable items, such as stencils, paste cartridges, squeegee blades, and tots.

[0077] The database can be configured to store data associated with lot traceability. Additionally, RFID or mechanical keying of plates or stencil frames of stencils is provided to ensure proper alignment, orientation, direction, front-to-back, and top-to-bottom (up-and-down) when these items are inserted into the stencil printer. This information can be used to verify proper orientation and / or fit before items are transported from the warehouse and / or before items are placed in the stencil printer. Low-cost readers can perform this function.

[0078] In one embodiment, the remote control may be configured to communicate with a database via the cloud or an ISP to provide the functionality described above, hi another embodiment, the database may be part of a computer control system for a stencil printer or a mobile cart or production line.

[0079] In some embodiments, the mobile cart can be configured to store materials. The mobile cart can be configured to have flexibility to accommodate where materials are coming from and where they are going. Additionally, the mobile cart can be configured to identify where a particular material is located on the mobile cart. In certain embodiments, the location can be remote, local, on the mobile cart, and / or on the stencil printer, whether delivered automatically or manually. As described above, the mobile cart can be configured to control environmental parameters. For example, the mobile cart can be configured to control the temperature of paste contained within the paste cartridges by cooling stored paste cartridges, heating paste cartridges ready for use, and cooling used paste cartridges that still contain paste. In one embodiment, the housing can be insulated, and a cooling / heating unit can be included to cool or heat the interior of the housing and, therefore, the paste cartridges. The mobile cart can also be configured to predict when to begin heating / cooling paste cartridges based on future production, track the time until shelf life, and individually control each paste cartridge to the appropriate temperature and time. In other embodiments, the mobile cart may include a cartridge shooter for moving the paste cartridge. The mobile cart may further be configured to control humidity to avoid condensation. The mobile cart may further be configured to operate in a clean environment, such as a standard mechanical interface (SMIF) environment.

[0080] In some embodiments, the mobile cart can be configured to perform inventory control, specifically, the mobile cart can be configured to identify where materials are located, how much material is used, how the material is used, when the material is used, associate materials and information about the materials with a customer inventory control system, and track the types of materials consumed per board or lot of boards.

[0081] In some embodiments, the mobile cart can be configured to organize items stored on the mobile cart. As noted above, in one embodiment, a single mobile cart can be provided to store, transport, and deliver multiple resources, including, but not limited to, paste cartridges. In another embodiment, the mobile cart can be configured to store, transport, and deliver a single resource or item to a stencil printer. The mobile cart can be configured to service multiple production lines. In another embodiment, the mobile cart can be configured to service a single stencil printer.

[0082] In some embodiments, the mobile cart can be configured to transport items from the mobile cart to the stencil printer and from the stencil printer to the mobile cart, and can be configured to account for differences in elevation between the mobile cart and the stencil printer. The transport can be automated or manual. In one embodiment, the mobile cart can be moved by automated guided vehicle (AVG) technology associated with the mobile cart or can be remotely controlled. In another embodiment, the mobile cart can be configured to move autonomously. In another embodiment, the mobile cart can be configured to be moved manually. In yet other embodiments, the mobile cart can be configured to automatically and / or manually move items stored on the mobile cart. For example, the mobile cart can be configured to automatically move items and can provide for interruptions in pre-planned activities where items are moved manually.

[0083] In some embodiments, the timing associated with the performance of the transport functions of the mobile carts can be programmed to account for shift changes, e.g., worker shifts, scheduled maintenance, on-demand activities, e.g., recipe changes, and precursor events (just-in-time replacement). The timing can be programmed to meet multiple line balancing control requirements using one or more mobile carts, as well as to meet the demands of real-time, on-demand material supply on a production line.

[0084] In some embodiments, the mobile cart is configured to perform inspections. For example, the mobile cart can inspect items on and off the cart, including stencils, paste cartridges, squeegee blades, and tooling. In one embodiment, a vision system associated with the mobile cart can be configured to obtain images of the items. The vision system in conjunction with the controller can be configured to inspect for cleanliness, damage, wear, and identity readability, for example, whether a barcode label is worn, unclean, or torn. The vision system can embody any type of 2D, 3D, or color camera.

[0085] In some embodiments, the mobile cart is configured to interface with the stencil printer through both a mechanical interface and an electrical communication interface. In one embodiment, the mobile cart can be configured with a unique mechanical interface that mates with a unique mechanical interface of the stencil printer. The unique mechanical interface can be a geometric feature. In another embodiment, the mobile cart can be configured with pins that are received within guides associated with the stencil printer to align the mobile cart with the stencil printer before fully docking the mobile cart. The pins and guides can be reversed, with the pins on the stencil printer and the guides within the mobile cart. Other types of guides can be used, such as electric / magnetic guides, visual guides, sensors, latches, etc.

[0086] In some embodiments, the interface and docking station can be configured with a clamping system that holds the movable cart in place relative to the stencil printer. For example, a magnetic clamping system can be utilized.

[0087] In some embodiments, the stencil printer can be configured with multiple docking stations, for example, 5. The docking stations can be located at the front of the stencil printer or at the rear of the stencil printer.

[0088] The mobile cart and / or stencil printer can be configured to verify whether the mobile cart can dock and interface with the stencil printer. In one embodiment, verification can be provided to confirm whether the mobile cart is in the proper position and ready to interface with the stencil printer. This verification process can further determine whether the correct material is on the mobile cart and whether the mobile cart material information can be received from the MES system or identified locally. If not, the mobile cart can be configured to activate an alarm and / or alert an operator if incorrect or damaged material is on the mobile cart.

[0089] In some embodiments, the mobile cart can be configured with actuation devices or actuators that move items onto and off the mobile cart when the mobile cart is docked with the stencil printer. Embodiments of the actuators can be implemented in the mobile cart, the stencil printer, or both. In another embodiment, items can be manually loaded and unloaded from the mobile cart.

[0090] In some embodiments, the mobile cart can be configured to interface with a production line, allowing a production line operator to verify the correct location of the mobile cart on the stencil printer and acknowledge receipt.

[0091] In some embodiments, the mobile cart can be configured to communicate with the stencil printer, the production line, and / or selected machines within the production line via an open platform. Communication systems can include wired systems, wireless systems (via common networks, mesh, Bluetooth, Wi-Fi, Zigbee, WAN, Nodes, Li-Fi, etc.), combinations of wired and wireless systems, and infrared (IR) systems.

[0092] In some embodiments, the mobile cart can be configured with its own power source. In one embodiment, the mobile cart includes a battery configured to power automated components included with the mobile cart, such as mechanisms used to move stencils into and out of the mobile cart, mechanisms used to move paste cartridges into and out of the mobile cart, mechanisms used to move squeegee blades into and out of the mobile cart, and mechanisms used to move tooling into and out of the mobile cart. In other embodiments, the mobile cart can be configured with an uninterruptible power supply. The power source can be configured to support operation while "docked" (high voltage from the stencil printer when docked, low voltage when undocked). The power source can be configured to recharge for autonomous operation, for example, to recharge the battery from power provided by the stencil printer.

[0093] In some embodiments, the mobile cart can be configured to function with the stencil printer. For example, the mobile cart can be configured to provide handshaking functionality with the stencil printer 10 before transferring an item, e.g., "Give me paste cartridge #1234." The mobile cart and stencil printer can be configured with a communication protocol and / or a library reference for what is consumable. The mobile cart can be configured to determine whether the mobile cart has the correct item. The handshaking functionality can be configured to ensure the correct transfer of the item, e.g., "Here's paste cartridge #1234," and / or to ensure the subsequent transfer of the item, e.g., "I have paste cartridge #1234." In one embodiment, a mobile device can be configured to scan and identify items in the mobile cart and determine, for example, whether the item is ready for use, whether it needs cleaning, etc.

[0094] In some embodiments, the mobile cart can be configured to address errors associated with handling and retrieving items within the mobile cart. For example, the mobile cart can be configured to detect incomplete actions by one party, incomplete transfer of an item, e.g., an item getting stuck or jammed, a dropped transfer, e.g., "I gave you paste cartridge #1234, do you have it?", and manual intervention or override, e.g., "Let me help you." In one embodiment, a controller associated with the mobile cart can be configured to perform electrostatic discharge control, data recovery and / or protection.

[0095] In some embodiments, the mobile cart can be configured with greater capacity: in addition to indexing all equipment to the correct height, the mobile cart may need to pull in / push out all equipment to mount the machine gantry.

[0096] In some embodiments, the stencil printer's existing mechanical gantry, rails, and print head can be configured to load and unload items.

[0097] In some embodiments, the movable cart may be configured with a paste cartridge indexer for loading / unloading paste cartridges.

[0098] In some embodiments, the mobile cart can be configured to communicate with the stencil printer, the production line, and a warehouse associated with the production line.

[0099] In some embodiments, the mobile cart can be configured with an electrical / pneumatic interface.

[0100] In some embodiments, the mobile cart can be configured to track new and used consumables, such as solder paste cartridges, on the mobile cart, including location, temperature, and other data.

[0101] In some embodiments, the mobile cart can be configured to scan all consumables using a suitable scanning device, such as a barcode reader or RFID reader.

[0102] In some embodiments, the mobile cart can be configured with an indexing mechanism to properly position the consumables.

[0103] In some embodiments, the mobile cart can be configured with a bypass switch that disconnects the mobile cart from the stencil printer if there is a problem with the mobile cart.

[0104] In some embodiments, the mobile cart can be configured to be actively or passively environmentally controlled.

[0105] In some embodiments, the mobile cart can be configured to be controlled by a smartphone integratable application (App).

[0106] As used herein, "automated" or "fully automated" changeover describes replacing or replenishing items without human intervention.

[0107] As used herein, "partially automated" changeover describes replacing or replenishing items with some or limited human intervention.

[0108] As used herein, "transport" or "transporting" describes the manual or mechanical movement of an item from one location to another.

[0109] As used herein, "install" or "installing" describes the process of placing an item in a location ready for use.

[0110] The concepts disclosed herein may be used in other types of equipment used to fabricate electronic boards, including pick-and-place machines, reflow ovens, wave soldering machines, selective soldering machines, inspection stations, and cleaning stations. For example, concepts related to tooling replacement can be used in pick-and-place machines used to attach electronic components to electronic boards. In another example, concepts related to item replacement can be used to replace solder in wave soldering machines and selective soldering machines, and to clean products in cleaning stations.

[0111] Having thus described several aspects of at least one embodiment, it will be understood that 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 scope of this disclosure. Accordingly, the foregoing description and drawings are by way of example only.

Claims

1. A movable cart, a housing configured to move along a horizontal plane; a plurality of shelves supported by the housing, each shelf of the plurality of shelves configured to move between a retracted position in which the shelf is positioned within the housing and an extended position in which the shelf extends from the housing; a sensing system configured to determine whether each shelf of the plurality of shelves is in the retracted position and the type of item supported by the shelf; A movable cart comprising:

2. The mobile cart of claim 1 , wherein the sensing system includes, for each shelf, at least one sensor coupled to the housing and at least one flag coupled to the housing.

3. 2. The mobile cart of claim 1, wherein the sensing system includes, for each shelf, a first sensor associated with a first flag positioned at an upper location relative to the shelf and a second sensor associated with a second flag positioned at a lower location relative to the shelf.

4. When the shelf is in the retracted position within the housing of the mobile cart, the sensor "Top low (off), bottom low (off) = empty shelf" signal, "Top high (on), bottom low (off) = loaded tool tray" signal, "Upper low (off), lower high (on) = no loaded tool tray" signal, and "Upper high (on), lower high (on) = stencil" signal, 4. The mobile cart of claim 3, wherein the mobile cart is configured to return one of:

5. 5. The mobile cart of claim 4, wherein the first sensor and the second sensor are further configured to generate a signal indicating whether the item is fully inserted into the respective shelf.

6. 1. A method for determining whether a shelf of a mobile cart is in a retracted position, comprising: sensing a flag associated with the shelf to determine the location of the shelf; A method comprising:

7. 7. The method of claim 6, further comprising providing a first sensor associated with a first flag positioned at an upper location relative to the shelf and a second sensor associated with a second flag positioned at a lower location relative to the shelf.

8. When the shelf is in the retracted position within the housing of the mobile cart, the sensor "Top low (off), bottom low (off) = empty shelf" signal, "Top high (on), bottom low (off) = loaded tool tray" signal, "Upper low (off), lower high (on) = no loaded tool tray" signal, and "Upper high (on), lower high (on) = stencil" signal, The method of claim 7 , wherein the method is configured to return one of:

9. The method of claim 8 , wherein the first sensor and the second sensor are further configured to generate a signal indicating whether the item is fully inserted into the respective shelf.

10. 1. A system for mechanically and electrically coupling a movable cart to a stencil printer, the stencil printer having at least one item of a plurality of items for exchange within the stencil printer, the stencil printer including a docking station configured to receive the movable cart, the movable cart configured to receive used items and / or provide new items to the stencil printer, the system comprising: a first interface panel associated with one of the stencil printer and the movable cart, the first interface panel including a latch magnet and an array of metal pads; a second interface panel associated with the other of the stencil printer and the movable cart, the second interface panel including a metal plate and an array of contacts; Equipped with when the movable cart is docked to the stencil printer, the latch magnet of the first interface panel is configured to magnetically secure the metal plate of the second interface panel, and the array of contacts of the second interface panel is configured to engage the array of metal pads of the first interface panel; system.

11. The system of claim 10 , wherein the first interface panel is associated with the stencil printer and the second interface panel is associated with the mobile cart.

12. 12. The system of claim 11, further comprising: a third interface panel associated with the stencil printer, the third interface panel being spaced apart from the first interface panel; and a fourth interface panel associated with the mobile cart, the fourth interface panel being spaced apart from the second interface panel.

13. The system of claim 10 , wherein the metal plate is a steel plate.

14. 11. The system of claim 10, wherein the latch magnet of the first interface panel is configured to communicate with a controller associated with the movable cart or a controller of the stencil printer to control operation of the latch magnet to lock or unlock the movable cart from the stencil printer.

15. The system of claim 10 , wherein the array of contacts comprises a plurality of spring contacts.

16. The system of claim 15 , wherein the metal pads include a plurality of hard gold pads.

17. The system of claim 10 , further comprising a guide assembly that guides the movable cart to the stencil printer when the movable cart is docked to the stencil printer.

18. 18. The system of claim 17, wherein the guide assembly includes at least one forward roller fixed to the housing of the movable cart, the at least one forward roller configured to contact at least one guide portion provided on a surface of the stencil printer.

19. 20. The system of claim 18, wherein the at least one forward roller includes two spaced-apart forward rollers, the at least one guide portion includes two spaced-apart guide portions, and the two spaced-apart forward rollers are configured to contact the two spaced-apart guide portions to guide the movable cart relative to the stencil printer.

20. 1. A method for mechanically and electrically coupling a movable cart to a stencil printer, the stencil printer having at least one item of a plurality of items for exchange within the stencil printer, the stencil printer including a docking station configured to receive the movable cart, the movable cart configured to receive used items and / or to provide new items to the stencil printer, the method comprising: providing a first interface panel associated with one of the stencil printer and the movable cart, the first interface panel including a latch magnet and an array of metal pads; providing a second interface panel associated with the other of the stencil printer and the movable cart, the second interface panel including a metal plate and an array of contacts; magnetically securing the metal plate of the second interface panel with the latch magnet of the first interface panel; engaging the array of metal pads of the first interface panel with the array of contacts of the second interface panel; A method comprising:

21. The method of claim 20 , wherein the first interface panel is associated with the stencil printer and the second interface panel is associated with the mobile cart.

22. 22. The method of claim 21, further comprising: a third interface panel associated with the stencil printer, the third interface panel being spaced apart from the first interface panel; and a fourth interface panel associated with the mobile cart, the fourth interface panel being spaced apart from the second interface panel.

23. 21. The method of claim 20, wherein the latch magnet of the first interface panel is configured to communicate with a controller associated with the moveable cart or a controller of the stencil printer to control operation of the latch magnet to lock or unlock the moveable cart from the stencil printer.

24. 21. The method of claim 20, further comprising guiding movement of the movable cart to the stencil printer when docking the movable cart to the stencil printer.

25. 25. The method of claim 24, wherein guiding the movement of the movable cart includes a guide assembly having at least one forward-facing roller fixed to a housing of the movable cart, the at least one forward-facing roller configured to contact at least one guide portion provided on a surface of the stencil printer.

26. 26. The method of claim 25, wherein the at least one forward roller includes two spaced-apart forward rollers, the at least one guide portion includes two spaced-apart guide portions, and the two spaced-apart forward rollers are configured to contact the two spaced-apart guide portions to guide the movable cart relative to the stencil printer.

27. 1. A system for measuring assembly material in a cartridge tube of a stencil printer including a carousel configured to support at least one cartridge tube, the system comprising: a laser height sensor coupled to a frame of the stencil printer, the laser height sensor being positioned above the at least one cartridge tube and configured to generate a laser beam toward the at least one cartridge tube to determine a height of assembly material within the at least one cartridge tube; A system comprising:

28. 1. A method for measuring assembly material in a cartridge tube of a stencil printer including a carousel configured to support at least one cartridge tube, comprising: sensing a height of assembly material within the at least one cartridge tube supported by the carousel; providing a warning to replace the at least one cartridge tube with a new cartridge tube if the at least one cartridge tube is determined to be empty, and continuing to use the at least one cartridge tube if the at least one cartridge tube is determined to have a sufficient amount of assembly material; A method comprising:

29. 30. The method of claim 28, wherein sensing the height of the assembly material is accomplished by a laser height sensor coupled to a frame of the stencil printer.

30. 30. The method of claim 29, wherein the laser height sensor is positioned above the at least one cartridge tube and configured to generate a laser beam toward the at least one cartridge tube to determine a height of assembly material within the at least one cartridge tube.

31. 30. The method of claim 29, further comprising calibrating the laser height sensor to determine a zero reference position.

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