Solder paste bead recovery system and method

Abstract

A stencil printer is configured to print assembly material on an electronic substrate. The stencil printer includes a frame, a stencil coupled to the frame, a support assembly coupled to the frame, and a print head gantry coupled to the frame. The print head gantry includes an elongated beam spanning along a track disposed on the frame, and a print head assembly supported by the print head gantry in a manner such that the print head assembly is configured to traverse the stencil during a print stroke. The print head assembly includes a print head having a squeegee blade assembly configured to cause solder paste to roll along the stencil. The stencil printer further includes a solder paste bead recovery system configured to remove solder paste beads from a top surface of the stencil and deposit the solder paste beads onto a new replacement stencil.

Description

[0001] This application is a divisional application of the invention patent application filed on June 11, 2020, with international application number PCT / US2020 / 037154, national application number 202080056656.9, and entitled "Solder Paste Bead Recycling System and Method".

[0002] Cross-references to related applications

[0003] This application is filed pursuant to 35 U.S. SC §119(e) with the following co-pending U.S. Provisional Patent Application No. 62 / 991,744, filed March 19, 2020, entitled "SOLDER PASTEBEAD RECOVERY SYSTEM AND METHOD"; U.S. Provisional Patent Application No. 62 / 861,025, filed June 13, 2019, entitled "METHOD AND SYSTEM FOR AUTOMATED CHANGEOVER AND REPLACEMENT WITHIN A STENCIL PRINTER"; U.S. Provisional Patent Application No. 62 / 861,031, filed June 13, 2019, entitled "AUTOMATED PRINTER ROBOTIC ARM"; and U.S. Provisional Patent Application No. 62 / 861,031, filed June 13, 2019, entitled "AUTOMATED PRINTER SMART". The benefit of U.S. Patent Application Serial No. 62 / 861,035 for CART [Intelligent Cart for Automated Printing Presses] is incorporated herein by reference in its entirety for all purposes. Background of the Invention

[0004] 1. Field of Invention

[0005] This application generally relates to stencil printing machines and related methods for printing adhesive materials (e.g., solder paste) on electronic substrates (e.g., printed circuit boards (PCBs)), and more specifically to systems and methods for recovering solder paste from stencils that are planned to be replaced or need to be replaced. 2. Background Technology

[0007] When manufacturing surface mount printed circuit boards (PCBs), a stencil printer is used to print solder paste onto the PCB. Typically, a PCB with solder paste deposited on it, featuring a pad pattern or other conductive surface, is automatically fed into the stencil printer; and one or more holes or marks (called "reference points") on the PCB are used to properly align the PCB with the stencil printer's template or screen before the solder paste is printed onto it. In some systems, an optical alignment system implemented as a vision system is used to align the PCB with the template.

[0008] Once the circuit board is correctly aligned with the stencil in the printing press, the board is raised onto the stencil, solder paste is dispensed onto the stencil, and a squeegee blade (or scraper) traverses the stencil to force the solder paste through the orifices in the stencil onto the circuit board. As the scraper moves across the stencil, the solder paste tends to roll in front of the blade, which as needed mixes and trims the solder paste to achieve the desired viscosity to facilitate filling the orifices in the screen or stencil. The solder paste is typically dispensed from a standard cassette onto the stencil. The stencil is then separated from the circuit board, and the adhesion between the circuit board and the solder paste leaves most of the material on the circuit board. The material remaining on the bottom surface of the stencil is removed during a cleaning process before printing another circuit board.

[0009] Another process in circuit board printing involves inspecting the board after solder paste has been deposited on its surface. Inspecting the board is crucial to determining if clean electrical connections can be manufactured. Too much solder paste can cause short circuits, while too little in the appropriate locations can prevent electrical contact. Typically, a visual inspection system is further employed to provide two-dimensional or three-dimensional inspection of the solder paste on the board.

[0010] Modern stencil printers require manual intervention to perform routine operations. For example, during changeovers, operators must perform numerous manual tasks, such as changing stencils, replacing solder paste cartridges, changing squeegee blades, and replacing support tools. Each of these tasks requires manual operation. For instance, in most stencil printers, the operator must unlock the stencil, remove it, correctly insert the replacement stencil, and lock it in place. Changeover operations can take up to 30 minutes, during which time the stencil printer is not in operation, potentially causing PCB production line downtime.

[0011] Stencil printing presses also require manual intervention to perform replacement and / or replenishment operations. For example, solder paste cartridges that supply temperature-controlled solder paste to the stencil printing press need to be replaced over time (e.g., within four hours or less). Items subjected to normal wear and tear, such as squeegee blades and stencils, may need to be replaced periodically when damaged.

[0012] Another issue is recovering solder paste from stencils that are scheduled for replacement. After a production cycle, or when a stencil is scheduled for replacement, residual solder paste is typically manually removed from the top surface of the stencil and saved for later use. This manual process is time-consuming and inefficient. Summary of the Invention

[0013] One aspect of this disclosure relates to a stencil printing machine for printing assembly material on an electronic substrate. In one embodiment, the stencil printing machine includes: a frame; a stencil coupled to the frame, the stencil having orifices formed therein; a support assembly coupled to the frame, the support assembly being configured to support the electronic substrate at a printing position below the stencil; a printhead gantry coupled to the frame, the printhead gantry including an elongated beam spanning along a track disposed on the frame; and a printhead assembly supported by the printhead gantry in such a way that the printhead assembly is configured to traverse the stencil during a printing stroke. The printhead assembly includes a printhead having a doctor blade assembly configured to roll solder paste along the stencil. The stencil printing machine further includes a solder paste bead recovery system configured to remove solder paste beads from the top surface of the stencil and deposit the solder paste beads onto a new replacement stencil.

[0014] Embodiments of the stencil printing machine may further include a solder paste tray of the recycling system, configured to be positioned from a storage location onto the top surface of the stencil. The storage location may be a track of a stencil support assembly. The storage location may be located at the front of the stencil support assembly. The solder paste tray may include a flat bottom wall configured to rest on a flat surface and allow solder paste beads to roll thereon. The elongated beam of the printhead gantry may include at least one linear bearing extending horizontally. The recycling system may further include at least one tool member configured to move laterally on the at least one linear bearing. The at least one tool member may include a downwardly extending pin having a head configured to be received within a receiving feature. The solder paste tray may include at least one receiving feature configured to be engaged by the pin of the at least one tool member to engage the solder paste tray and move it from the storage location to the top surface of the stencil. The at least one tool component may include two spaced-apart tool components, namely a first tool component and a second tool component, each tool component including a pin. The first tool component is configured to move laterally on a first linear bearing, and the second tool component is configured to move laterally on a second linear bearing. The at least one receiving feature may include two receiving features, each tool component having a receiving feature, the first and second tool components being received in corresponding mating features of the solder paste tray to releasably secure the solder paste tray. The support assembly may be configured to move along the z-axis and be raised to engage a magnet mounted in the bottom of the solder paste tray, wherein the support assembly includes a steel surface to hold the solder paste tray in place on the stencil. The scraper blade assembly may include a first scraper blade configured to engage the stencil and roll solder paste beads into the solder paste tray. The scraper blade assembly may further include a second scraper blade configured to engage the paste tray and roll solder paste beads onto the stencil.

[0015] Another aspect of this disclosure relates to a method for recovering solder paste from a stencil scheduled for replacement. In one embodiment, the method includes: moving a solder paste reel from a storage location to a position near the solder paste beads on the used stencil; using a scraper blade assembly of a printhead assembly to roll the solder paste beads onto the solder paste reel; moving the reel to a storage location; replacing the used stencil with a new stencil; moving the solder paste reel from the storage location onto the new stencil; using a scraper blade assembly to roll the solder paste beads onto the new stencil; and moving the solder paste reel to a storage location.

[0016] Embodiments of the method may further include: engaging a support assembly configured to move along the z-axis and be raised to a magnet mounted in the bottom of a solder paste tray, the support assembly including a steel surface to hold the solder paste tray in place. Moving the solder paste tray from a storage location and moving the solder paste tray to a storage location may include: positioning a downwardly extending pin of at least one tool member of the printhead assembly within a receiving feature associated with the solder paste tray. The at least one tool member may include two spaced-apart tool members, each tool member including a pin. The at least one receiving feature may include two receiving features that receive the tool members in corresponding mating features of the solder paste tray to secure it to the solder paste tray. Rolling solder paste beads onto the solder paste tray using a squeegee blade assembly of the printhead assembly may include: a first squeegee blade configured to engage a stencil and roll solder paste beads into the solder paste tray. Rolling solder paste beads onto a new stencil using a squeegee blade assembly of the printhead assembly may include: a second squeegee blade configured to engage the solder paste tray and roll solder paste beads onto the stencil. This storage location may include the track of the template support assembly. This storage location may be located at the front of the template support assembly.

[0017] Another aspect of this disclosure relates to a stencil printing machine for printing assembly material on an electronic substrate. In one embodiment, the stencil printing machine includes: a frame; a stencil coupled to the frame, the stencil having orifices formed therein; and a support assembly coupled to the frame, the support assembly being configured to support the electronic substrate. The stencil printing machine further includes: a printhead gantry coupled to the frame; and a printhead assembly supported by the printhead gantry in such a way that the printhead assembly is configured to traverse the stencil during a printing stroke. The stencil printing machine further includes an assembly material recovery system configured to remove assembly material from the top surface of the stencil and deposit the assembly material onto a new replacement stencil. The recovery system includes a receiver configured to be positioned on the top surface of the stencil.

[0018] Embodiments of the stencil printing machine may further include positioning a receiving seat from a storage location onto the top surface of the stencil, the storage location being a track of a stencil support assembly. The storage location may be located at the front of the stencil support assembly. The receiving seat may include a flat bottom wall configured to rest on a flat surface and allow assembly material to roll thereon. The printhead gantry may include an elongated beam spanning a track disposed on the frame. The elongated beam of the printhead gantry may include at least one linear bearing extending horizontally. The retrieval system may further include at least one tool member configured to move laterally on the at least one linear bearing. The at least one tool member may include a downwardly extending pin having a head configured to be received within a receiving feature. The receiving seat may include at least one receiving feature configured to be engaged by the pin of the at least one tool member to engage the receiving seat and move it from the storage location to the top surface of the stencil. The at least one tooling component includes two spaced-apart tooling components, namely a first tooling component and a second tooling component, each tooling component including a pin. The first tooling component is configured to move laterally on a first linear bearing, and the second tooling component is configured to move laterally on a second linear bearing. The at least one receiving feature may include two receiving features, each tooling component having one receiving feature, wherein the first and second tooling components are received in corresponding mating features of a receiving seat to releasably secure the receiving seat. The support assembly may be configured to move along the z-axis and be raised to engage a magnet mounted in the bottom of the receiving seat. The support assembly may include a steel surface to hold the receiving seat in place on the template. The printhead assembly may include a printhead having a doctor blade assembly configured to move assembly material along the template. The doctor blade assembly may include a first doctor blade configured to engage the template and roll the assembly material into the receiving seat. The doctor blade assembly may further include a second doctor blade configured to engage the receiving seat and roll the assembly material onto the template.

[0019] Another aspect of this disclosure relates to a method for recovering assembly material from a template to be replaced. In one embodiment, the method includes: moving a receiving seat to a position on the used template close to the assembly material; moving the assembly material onto the receiving seat; removing the receiving seat from the used template; replacing the used template with a new template; moving the receiving seat onto the new template; using a scraper blade assembly to move the assembly material onto the new template; and removing the receiving seat from the new template.

[0020] Embodiments of the method may further include: positioning a downwardly extending pin of at least one tool member of the printhead assembly within a receiving feature associated with the receiving seat when the receiving seat is moved onto a used template and removed from a new template. The at least one tool member includes two spaced-apart tool members, each including a pin. The at least one receiving feature may include two receiving features received in corresponding mating features of the receiving seat to secure the receiving seat. The method may further include: engaging a support assembly configured to move along the z-axis and be raised to a magnet mounted in the bottom of the receiving seat, wherein the support assembly includes a steel surface to hold the receiving seat in place. Moving assembly material onto the receiving seat may include: moving the assembly material using a doctor blade assembly of the printhead assembly. The doctor blade assembly may include a first doctor blade configured to engage the template and move the assembly material into the receiving seat. The doctor blade assembly may further include a second doctor blade configured to engage the assembly material and move the assembly material onto the template. Removing the receiver from a used template and removing the receiver from a new template can each include moving the receiver to a storage location. This storage location can be the track of the template support component.

[0021] Another aspect of this disclosure relates to an assembly material recycling system configured to remove assembly material from the top surface of a stencil of a stencil printing machine and deposit the assembly material onto a new replacement stencil. In one embodiment, the recycling system includes a receiving seat configured to be positioned on the top surface of the stencil.

[0022] Embodiments of the recycling system may further include configuring the receiving seat with a flat bottom wall configured to rest on a flat surface and allow assembly material to move thereon. The elongated beam of the printhead gantry may include at least one linear bearing extending horizontally. The recycling system may further include at least one tool member configured to move laterally on the at least one linear bearing. The at least one tool member may include a downwardly extending pin having a head configured to be received within a receiving feature. The receiving seat may include at least one receiving feature configured to be engaged by the pin of the at least one tool member to engage the receiving seat and move it from a storage position to the top surface of the template. The at least one tool member includes two spaced-apart tool members, namely a first tool member and a second tool member, each tool member including a pin, the first tool member being configured to move laterally on a first linear bearing, and the second tool member being configured to move laterally on a second linear bearing. The at least one receiving feature may include two receiving features, each tool member having one receiving feature, wherein the first and second tool members are received in corresponding mating features of the receiving seat to releasably secure the receiving seat. The support assembly can be configured to move along the z-axis and be raised to engage a magnet mounted in the bottom of the receiver, wherein the support assembly includes a steel surface to hold the receiver in place on the template. Attached Figure Description

[0023] The accompanying drawings are not intended to be drawn to scale. In the drawings, every identical or nearly identical component shown in each drawing is indicated by the same reference numerals. For clarity, not every component may be labeled in each drawing. In the drawings:

[0024] Figure 1 This is a front view of a template printing press;

[0025] Figure 2 This is a front-view perspective view of a template printing machine;

[0026] Figure 3 yes Figure 2 The image shows a top view of a stencil printing press, with some parts removed.

[0027] Figure 4 This is a perspective view of a printhead assembly according to an embodiment of the present disclosure, the printhead assembly being configured to move a solder paste tray configured to remove solder paste and deposit it onto a stencil to be replaced;

[0028] Figure 5 This is a perspective view of a printhead assembly having a retaining pin configured to engage a paste tray located in a storage position.

[0029] Figure 6 This is a 3D view of the printhead assembly moving the solder paste tray;

[0030] Figure 7 This is an elevation view of a portion of the printhead assembly before the solder paste balls are removed using the solder paste tray;

[0031] Figure 8 This is a perspective view of a printhead assembly having a printhead configured to move solder paste beads into a solder paste tray;

[0032] Figure 9 This is an elevation view of a portion of the printhead assembly, showing the printhead moving solder paste beads into the solder paste tray;

[0033] Figure 10 This is a 3D view of the printhead assembly moving the solder paste tray to the storage position;

[0034] Figure 11 This is a 3D view of the printhead assembly moving the solder paste tray from the storage position to the deposition position;

[0035] Figure 12 This is an elevation view of a portion of the printhead assembly, wherein the printhead is configured to deposit solder paste beads onto a replacement template;

[0036] Figure 13 This is a 3D view of the printhead assembly, in which the printhead moves solder paste beads onto the replacement template;

[0037] Figure 14 This is a 3D view of the printhead assembly moving the solder paste tray to the storage location;

[0038] Figure 15 This is a perspective view of the printhead assembly, showing the printhead in the stencil printing position; and

[0039] Figure 16 This is a perspective view of a printhead assembly according to another embodiment of the present disclosure, the printhead assembly being configured to move a solder paste tray configured to remove solder paste and deposit it onto a stencil to be replaced. Detailed Implementation

[0040] This disclosure generally relates to material application machines (referred to herein as “stencil printers,” “screen printers,” “printing machines,” or “printers”) and other equipment used in surface mount technology (SMT) production lines and configured to apply assembly materials (e.g., solder paste, conductive ink, or encapsulation materials) onto a substrate (e.g., a printed circuit board, referred herein as an “electronic substrate,” “circuit board,” “board,” “PCB,” “PCB substrate,” “substrate,” or “PCB board”) or to perform other operations such as inspection, rework, or arranging electronic components on the substrate. Specifically, embodiments of this disclosure are described below with reference to stencil printers used to produce printed circuit boards.

[0041] This disclosure will now be described in detail with reference to the accompanying drawings for illustrative purposes only and not for limiting its generality. This disclosure is not intended to limit its application to the details of the construction and arrangement of the components set forth in the following description or shown in the accompanying drawings. The principles set forth in this disclosure can be used in other embodiments and can be practiced or performed in various ways. Similarly, 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 the plural, and any reference to any embodiment, component, element, or action mentioned herein in the plural may also cover embodiments including only the singular. References in the singular or plural form are not intended to limit the systems or methods currently disclosed, their components, actions, or elements. The use of “comprising,” “including,” “having,” “containing,” “involving,” and variations thereof herein is intended to cover the items listed thereafter and their equivalents, as well as other items. References to “or” can be interpreted as inclusive, and thus any item described using “or” may indicate a single item, multiple items, or any of all items described. Furthermore, in the event of any inconsistency between the terminology used in this document and the documents incorporated herein by reference, the terminology used in the incorporated reference shall supplement the terminology used in this document; in the case of any inconsistency that cannot be reconciled, the terminology used in this document shall prevail.

[0042] For illustrative purposes, embodiments of this disclosure will now be described with reference to a stencil printer for printing assembly materials (such as solder paste) onto a circuit board. However, those skilled in the art will understand that embodiments of this disclosure are not limited to stencil printers for printing solder paste onto circuit boards, but can be used for other applications requiring the dispensing of other viscous assembly materials such as adhesives and sealants. For example, the apparatus can be used to print epoxy resin used as an underfill for chip-scale packages. Furthermore, the stencil printers according to embodiments of this disclosure are not limited to those printers for printing assembly materials on circuit boards, but include those printers for printing other materials on various substrates such as semiconductor wafers. Additionally, the terms screen and stencil are used interchangeably herein to describe means in a printer for defining a pattern to be printed onto a substrate. In some embodiments, the stencil printer may include one supplied by ITW Electronic Assembly Equipment, Hopkinton, Massachusetts. Or Edison TM Series of template printing machine platforms. Exemplary template printing machines are generally used... Figure 1 Reference numeral 5 indicates the type of printing press 5. In this embodiment, the stencil printer 5 is supplied by ITW Electronic Assembly Equipment, Inc., Hopkinton, Massachusetts. Series of template printing machine platforms.

[0043] refer to Figure 2 The stencil printing machine of the present disclosure is generally indicated by reference numeral 10. As shown, the stencil printing machine 10 includes a frame 12 that supports the components of the stencil printing machine. The components of the stencil printing machine may partially include a controller 14, a display 16, a stencil 18, and a printhead or printhead assembly, generally indicated by reference numeral 20, which is configured to apply solder paste in a manner described in more detail below.

[0044] like Figure 2 As shown and described below, the stencil and printhead assembly can be suitably coupled or otherwise connected to the frame 12. In one embodiment, the printhead assembly 20 can be mounted on a printhead assembly gantry (generally indicated by reference numeral 22, sometimes referred to as the "printhead gantry"), which can be mounted on the frame 12. The printhead gantry 22 enables the printhead assembly 20 to move along the y-axis under the control of the controller 14 and to apply pressure to the printhead assembly when it engages the stencil 18. In one embodiment, the printhead assembly 20 can be arranged above the stencil 18 and can be lowered in the z-axis direction to contact and seal the stencil.

[0045] The stencil printing press 10 may also include a conveyor system with tracks (not shown) for transporting printed circuit boards (sometimes referred to herein as “printed wiring boards,” “substrates,” or “electronic substrates”) to printing positions within the stencil printing press. The tracks, sometimes referred to herein as “traction feed mechanisms,” are configured to feed, load, or otherwise deliver the circuit boards to the working area of ​​the stencil printing press (which may be referred to herein as “printing nests”) and unload the circuit boards from the printing nests.

[0046] For further reference Figure 3 The stencil printing machine 10 has a support assembly 28 for supporting a circuit board 29 (shown in dashed lines). This support assembly raises and secures the circuit board, ensuring its stability during printing operations. In some embodiments, the substrate support assembly 28 may also include a specific substrate support system, such as a robust support member, multiple pins, or flexible tools, positioned below the circuit board when it is in the printing position. The substrate support system may be used in part to support internal areas of the circuit board to prevent it from flexing or warping during printing operations.

[0047] In one embodiment, the printhead assembly 20 may be configured to receive solder paste from a source (such as a dispenser, e.g., a solder paste cassette) that supplies solder paste to the printhead assembly during the printing operation. Instead of a solder paste cassette, other methods of supplying solder paste may be employed. For example, solder paste may be manually deposited between the blades or deposited from an external source. Additionally, in one embodiment, the controller 14 may be configured to use a system with an operating system suitable for Microsoft (such as Microsoft Corporation's Microsoft...). A personal computer with an operating system, having software specifically designed for applications to control the operation of the stencil printing machine 10. The controller 14 can be networked with a main controller used to control the production line for manufacturing circuit boards.

[0048] In one configuration, the stencil printer 10 operates as follows: A circuit board 29 is loaded into the stencil printer 10 using a conveyor track. A support assembly 28 raises and secures the circuit board 29 in the printing position. The print head assembly 20 is then lowered in the z-axis direction until the blades of the print head assembly contact the stencil 18 with the desired pressure. The print head assembly 20 is then moved across the stencil 18 in the y-axis direction via the print head gantry 22. The print head assembly 20 deposits solder paste onto the circuit board 29 through orifices in the stencil 18. Once the print head assembly has completely traversed the stencil 18 across these orifices, the print head assembly is raised away from the stencil and the circuit board 29 is lowered back onto the conveyor track. The circuit board 29 is released from the stencil printer 10 and transported so that a second circuit board can be loaded into the stencil printer. For printing on the second circuit board 29, the print head assembly is lowered in the z-axis direction to contact the stencil and moved across the stencil 18 in the opposite direction to that used for the first circuit board.

[0049] An imaging system 30 may be provided for aligning the stencil 18 with the circuit board 29 before printing and for inspecting the circuit board after printing. In one embodiment, the imaging system 30 may be positioned between the stencil 18 and a support assembly 28 on which the circuit board is supported. The imaging system 30 is coupled to an imaging gantry 32 to move the imaging system. In one embodiment, the imaging gantry 32 may be coupled to a frame 12 and include a beam extending between side rails of the frame 12 to provide reciprocating movement of the imaging system 30 on the circuit board 29 along the y-axis. The imaging gantry 32 may also include a carriage arrangement that accommodates the imaging system 30 and is configured to move along the length of the beam in the x-axis direction. The construction of the imaging gantry 32 for moving the imaging system 30 is well known in the solder paste printing industry. This arrangement allows the imaging system 30 to be positioned anywhere below the stencil 18 and above the circuit board 29 to capture images of predefined areas of the circuit board or the stencil, respectively.

[0050] After one or more applications of solder paste to the circuit board, excess solder paste may accumulate at the bottom of stencil 18, and the stencil wiper assembly (generally indicated by reference numeral 34) may move below the stencil to remove the excess solder paste. In other embodiments, stencil 18 may move above the stencil wiper assembly.

[0051] As mentioned earlier, stencil printing machines require manual intervention to perform certain parts replacement and / or replenishment operations. For example, a typical stencil needs to be replaced after a certain period of time (e.g., four hours). Furthermore, the stencil needs to be replaced for different production cycles. Additionally, the solder paste cassette that supplies temperature-controlled solder paste to the stencil printing machine needs to be replaced over time (e.g., within four hours or less). Different production cycles may require different solder paste materials. Another item that needs periodic replacement is the doctor blade, which wears down during use. And finally, the tools used to support the substrate in the printing position need to be replaced when changing from one production product to another.

[0052] As mentioned earlier, removed stencils often have solder paste beads remaining on them. Given the value of solder paste, it is desirable to preserve it for future use rather than discarding it. The systems and methods disclosed in this paper aim to automate this recycling process.

[0053] See Figure 4 The printhead assembly 20 is mounted on the printhead gantry 22 to provide movement along the y-axis under the control of the controller 14. The printhead gantry 22 includes tracks 38, 40 arranged along the frame 12 of the stencil printing machine 10. Figure 3 A long beam 36 spans the plate. Beam 36 includes a plate 42 having two sets of linear bearings 44, 46 extending horizontally along the plate, with top linear bearings 44a, 44b arranged above bottom linear bearings 46a, 46b. The printhead assembly 20 includes a printhead 48 coupled to beam 36 of the printhead gantry 22. Specifically, the printhead 48 is mounted on a bracket 50, which is fixedly mounted on the plate 42. Thus, the printhead gantry 22 provides movement of the printhead 48 along the y-axis for the printing stroke described herein. The printhead 48 includes a doctor blade assembly, indicated as 52, for rolling solder paste along the stencil in the manner described above.

[0054] The printhead assembly 20 further includes a solder paste bead recovery system configured to remove solder paste beads 54 from the top surface of the stencil 18 and deposit them onto a new replacement stencil (also shown as 18 in the figures). As shown, the recovery system includes a plate 42 mounted on the printhead assembly 20. As mentioned above, plate 42 includes two pairs of linear bearings 44a, 44b and 46a, 46b. As shown, linear bearings 44a, 46a are configured to support a first tool member 56, and linear bearings 44b, 46b are configured to support a second tool member 58, wherein linear bearings 56, 58 are configured to move laterally over their respective pairs of linear bearings. The first tool member 56 includes a downwardly extending pin 60 having a head configured to be received within a receiving feature described in more detail below. Similarly, the second tool member 58 includes a downwardly extending pin 62 having a head configured to be located within a receiving feature.

[0055] Any suitable mechanism can be used to move the tool components 56, 58. For example, a ball screw drive assembly 64 can be used to move each tool component 56, 58 along linear bearings 44a, 46a and 44b, 46b, respectively. In some embodiments, the ball screw drive assembly 64 provided for moving the tool components 56, 58 along linear bearings 44a, 44b and 46a, 46b, respectively, can also provide up-and-down movement of the print head 48 along the z-axis. As mentioned above, the print head 48 of the print head assembly 20 is configured to be lowered during printing operations to engage the stencil 18 and raised to disengage from the stencil when no printing operations are being performed. When lowered, the print head 48 applies pressure to the doctor blade assembly 52, causing the doctor blade assembly to sealably engage the stencil 18.

[0056] The solder paste bead recovery system further includes a solder paste tray (generally indicated as 66) located at a storage position on a track 68 of a stencil support assembly (generally indicated as 70). Hereinafter, the solder paste tray 66 is sometimes referred to as a solder paste receiving seat or receiving base. As shown, the storage position of the solder paste tray 66 is located at the front of the stencil support assembly 70; however, the solder paste tray can be positioned towards the rear of the stencil support assembly. The solder paste tray 66 includes a flat bottom wall 72, a rear wall 74, and two triangular side walls 76, 78, the flat bottom wall resting on a flat surface of the track 68 of the stencil support assembly 70. As shown, the side wall 76 includes a first receiving feature 80 extending beyond the peripheral edge of the side wall. Similarly, the other side wall 78 includes a second receiving feature 82 extending beyond the peripheral edge of the side wall. The receiving features 80 and 82 are configured to engage with pin 60 of the first tool member 56 and pin 62 of the second tool member 58, respectively, to engage and move the solder paste tray 66.

[0057] In one embodiment, pins 60, 62 of tool members 56, 58 are received in corresponding mating features 80, 82 of solder paste tray 66. The tool members 56, 58 may extend wider than the solder paste tray 66 and move toward each other to engage and capture the solder paste tray between pins 60, 62 via receiving features 80, 82. Thus, tool members 56, 58 are configured to accommodate solder paste trays 66 of various widths. Printhead assembly 20 is configured to move along the y-axis via printhead gantry 22 to engage and move solder paste tray 66. Pins 60, 62 of tool members 56, 58 may employ various mechanisms for engaging and moving solder paste tray 66. For example, each pin 60, 62 of tool members 56, 58 may include a magnet to facilitate attachment and disengagement of the solder paste tray 66 from the tool assembly, thereby lifting and moving the solder paste tray.

[0058] See still Figure 4 After the batching of circuit boards is completed, solder paste beads 54 remain on track 68 of the stencil support assembly 70. Subsequent batching of circuit boards may require tooling changes, including changing the stencil 18, but using the same type of solder paste. Solder paste beads 54 can be recycled using the solder paste bead recycling system and related methods discussed herein.

[0059] See Figure 5 The printhead gantry 22 is configured to move the printhead assembly 20 to remove the solder paste tray 66 from its storage position using pins 60, 62 of tool members 56, 58. In one embodiment, these pins may be configured to form articulations in the x-axis, y-axis, and z-axis directions of the stencil printing press 10 to lift the solder paste tray 66 away from the track 68 of the stencil support assembly 70 and move the solder paste tray in a desired direction (e.g., the y-axis direction). As shown, when the printhead 48 is raised, the printhead assembly 20 moves to a position above the solder paste tray 66, wherein the pins 60, 62 of tool members 58, 60 are positioned above their respective receiving features 80, 82.

[0060] See Figure 6 The printhead gantry 22 is configured to remove the solder paste tray 66 from its storage position on the track 68 of the stencil support assembly 70 and place it at a designated solder paste transfer position on the stencil 18. The movement of the solder paste tray 66 to the indicated position can be in response to a stencil change operation indicated by the controller 14. The change of the stencil 18 can be pre-planned or in response to an event related to the stencil, such as orifice blockage that the stencil wiper assembly 34 cannot adequately clean. As shown, the leading edge of the bottom wall 72 of the solder paste tray 66 is adjacent to the solder paste beads 54.

[0061] See Figure 7 and Figure 8Once positioned, the support assembly 28 (sometimes referred to as the "table") is configured to move along the z-axis and rise toward the stencil 18. The support assembly 28 includes a flipper mechanism 84 having a metal surface, such as a steel surface 86, configured to engage the bottom surface of the stencil 18 when raised. The solder paste tray 66 is configured to include one or more magnets (denoted as 88) disposed in the bottom wall 72 of the solder paste tray. This arrangement ensures that the magnets 88 of the solder paste tray 66 engage the steel surface 86 of the flipper mechanism 84, thereby holding the solder paste tray in the transfer position as solder paste beads are scraped onto it. As shown, one of these scraper blades (e.g., scraper blade 52a) is configured to engage the stencil 18 and cause solder paste beads 54 to roll into the tray. The print head 48 of the print head assembly 20 is configured to move the squeegee blade 52a along the z-axis, such that the squeegee blade engages the stencil, and move along the x-axis by moving the print head gantry 22 toward the solder paste tray 66, thereby causing the solder paste beads 54 to roll into the solder paste tray.

[0062] See Figure 9 The scraper blade 52a is shown to roll solder paste beads 54 into the solder paste tray 66. As shown, the solder paste beads 54 are supported on the bottom wall of the solder paste tray 66. Once the transfer is complete, the transfer mechanism 84 (not shown) is lowered to disengage from the magnet 88 (not shown) and thus allows the solder paste tray 66 to move relative to the template 18.

[0063] See Figure 10 The solder paste tray 66 with solder paste beads 54 is returned to its storage position on the track 68 of the stencil support assembly 70. Once the solder paste tray 66 is positioned in the storage position, tooling replacement proceeds, including removing the used stencil 18 and replacing it with a clean stencil 18. This process can be used when a defect is detected in the stencil 18 and a replacement is required.

[0064] See Figure 11 After the stencil 18 is replaced, the first tool member 56 and the second tool member 58 of the printhead assembly 20 remove the solder paste tray 66 from its storage position on the track 68 of the stencil support assembly 70. Once secured, the solder paste tray 66 is moved along the x-axis by moving the printhead gantry 22 and lowered to the solder paste transfer position on the clean stencil 18.

[0065] See Figure 12 and Figure 13The support assembly 28 moves upward along the z-axis and is raised so that the magnet 88, mounted in the bottom wall 72 of the solder paste tray 66, engages the steel surface 86 of the conversion mechanism 84 associated with the support assembly 28. As described above, the engagement of the steel surface 86 of the conversion mechanism 84 with the magnet 88 holds the solder paste tray 66 in the transfer position as the solder paste beads 54 are scraped back onto the new clean stencil 18. As shown, another of these scraper blades (e.g., scraper blade 52b) is configured to engage the bottom wall 72 of the solder paste tray 66 and cause the solder paste beads 54 to roll into the stencil 18.

[0066] See Figure 14 The printhead assembly 20 returns the paste tray 66 to the storage position as described above.

[0067] See Figure 15 The stencil printing machine 10 is ready to use the solder paste beads 54 transferred from the previous batch for printing.

[0068] See Figure 16 If the next batch of circuit boards will use a different type of solder paste, the solder paste reel 66 can be replaced along with other tools (such as tool board 90) during automatic tooling changes. A tool tray can be used to load the clean solder paste reel 66 along with other tools and then place it in the storage location. This process will prevent any cross-contamination of solder paste types between batches.

[0069] Embodiments of this disclosure include a method for recovering solder paste from a stencil scheduled for replacement. In one embodiment, the method includes moving a solder paste reel 66 from a storage location to a position on a used stencil 18 near solder paste beads 54. The method further includes using a scraper blade assembly 52 of a printhead assembly 20 to roll the solder paste beads 54 into the solder paste reel 66. Next, the solder paste reel 66 is moved back to a storage location, and the used stencil 18 is replaced with a new stencil 18. The method further includes moving the solder paste reel 66 from a storage location onto a new stencil 18, and using the scraper blade assembly 52 to roll the solder paste beads 54 onto the new stencil 18. The method further includes moving the reel 66 back to a storage location until the process is restarted.

[0070] The solder paste bead recovery system and related methods can be performed under the control of controller 14. Specifically, controller 14 can be configured to know when to perform the solder paste recovery process.

[0071] In some embodiments, the existing stencil printing machine gantry, track, and printhead of the stencil printing machine 10 can be configured to allow articles (including solder paste tray 66) to move back and forth.

[0072] In some embodiments, the printhead assembly 20 of the stencil printing machine 10 may be configured to move the paste tray 66 and make it reciprocate.

[0073] As used in this article, "automated" or "fully automated" replacement describes the replacement or replenishment of items without human intervention.

[0074] As used in this article, "partially automated" replacement describes the replacement or replenishment of items with some or limited human intervention.

[0075] As used in this article, “transporting” or “in transit” describes the manual or machine-assisted movement of items from one location to another.

[0076] As used in this article, "installing" or "in installation" describes the process of placing an item in a location ready for use.

[0077] As described above, the movable trolley can be used to replace other items within the stencil printing machine. For example, the stencil wiper assembly includes consumables such as paper and solvents that can be automatically replaced by the movable trolley.

[0078] The concepts disclosed herein can be applied to other types of equipment used to manufacture electronic substrates, including dispensers, pick-and-place machines, reflow ovens, wave soldering machines, selective soldering machines, inspection stations, and cleaning stations. For example, the concepts for recycled materials can be used in soldering and wave soldering machines as well as cleaning stations.

[0079] Therefore, having described several aspects of at least one embodiment, it will 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 and fall within the scope of this disclosure. Thus, the preceding description and figures are merely examples.

Claims

1. A stencil printing machine for printing assembly materials on an electronic substrate, the stencil printing machine comprising: frame; A template connected to the rack, the template having openings formed therein; A support assembly connected to the rack, the support assembly being configured to support the electronic substrate; A printhead gantry connected to the frame, the printhead gantry including an elongated beam spanning along a track disposed on the frame, the elongated beam of the printhead gantry having at least one linear bearing extending in a horizontal direction; A printhead assembly supported by the printhead gantry, configured to traverse the template during the printing stroke; as well as An assembly material recovery system configured to remove assembly material from the top surface of the template and deposit the assembly material onto a new replacement template, the assembly material recovery system comprising a receiving seat configured to be positioned on the top surface of the template and at least one tooling member configured to move laterally on at least one linear bearing.

2. The template printing machine as described in claim 1, wherein, The receiving seat is positioned from the storage location onto the top surface of the template, the storage location being the track of the template support assembly.

3. The template printing machine as described in claim 1, wherein, The receiving seat includes a flat bottom wall configured to rest on a flat surface and allow the assembly material to roll thereon.

4. The template printing machine as described in claim 1, wherein, The at least one tool component includes a downwardly extending pin having a head configured to be received within a receiving feature.

5. The template printing machine as described in claim 4, wherein, The receiver includes at least one receiving feature configured to be engaged by the pin of the at least one tool member to engage the receiver and move the receiver from a storage position to the top surface of the template.

6. The template printing machine as described in claim 5, wherein, The at least one tool member includes two spaced-apart tool members, namely a first tool member and a second tool member, each tool member including a pin, the first tool member being configured to move laterally on a first linear bearing, and the second tool member being configured to move laterally on a second linear bearing, wherein the at least one receiving feature includes two receiving features, one receiving feature for one tool member, the first tool member and the second tool member being received in the corresponding receiving feature of the receiving seat to releasably secure the receiving seat.

7. The template printing machine as described in claim 6, wherein, The support assembly is configured to move in the z-axis direction and be raised to engage a magnet mounted in the bottom of the receiver, the support assembly including a steel surface to secure the receiver in place on the template.

8. The template printing machine as described in claim 7, wherein, The printhead assembly includes a printhead having a scraper blade assembly configured to move assembly material along the template, the scraper blade assembly including a first scraper blade configured to engage the template and roll the assembly material into the receiver.

9. The template printing machine as described in claim 8, wherein, The scraper blade assembly further includes a second scraper blade configured to engage the receiver and roll assembly material onto the template.

10. A method for recovering assembly material from a template to be replaced within a template printing press as claimed in claim 1, the method comprising: Move the receiver to a position on the used template closer to the assembly material; Move the assembly materials onto the receiving seat; Remove the receiver from the used template; Replace the used template with a new template; Move the receiver onto the new template; The assembly material is moved to the new template using a scraper blade assembly; and Remove the receiver from the new template.

11. The method of claim 10, wherein, Moving the receiver onto the used template and removing the receiver from the new template includes: positioning a downwardly extending pin of at least one tool component of the assembly material recycling system within at least one receiving feature associated with the receiver.

12. The method of claim 11, wherein, The at least one tool component includes two spaced-apart tool components, each tool component including a pin, and wherein the at least one receiving feature includes two receiving features, the two tool components being received in corresponding receiving features of the receiving seat to secure the receiving seat.

13. The method of claim 12, further comprising engaging a support assembly configured to move in the z-axis direction and be raised to a magnet mounted in the bottom of the receiver, the support assembly including a steel surface to hold the receiver in place.

14. The method of claim 11, wherein, Moving the assembly material onto the receiving seat includes moving the assembly material using the scraper blade assembly of the printhead assembly.

15. The method of claim 14, wherein, The scraper blade assembly includes a first scraper blade configured to engage the template and move assembly material into the receiving seat.

16. The method of claim 15, wherein, The scraper blade assembly further includes a second scraper blade configured to engage assembly material and move the assembly material onto the template.

17. The method of claim 11, wherein, Removing the receiver from the used template and removing the receiver from the new template each include: moving the receiver to a storage location on the track of the template support assembly.

18. An assembly material recycling system configured to remove assembly material from the top surface of a stencil of a stencil printing machine and deposit the assembly material onto a new replacement stencil, the stencil printing machine including a printhead gantry having an elongated beam having at least one linear bearing extending in a horizontal direction, the assembly material recycling system comprising: A receiver, configured to be positioned on the top surface of the template; as well as At least one tool component, the at least one tool component being configured to move laterally on the at least one linear bearing.

19. The assembly material recycling system as described in claim 18, wherein, The receiving seat includes a flat bottom wall configured to rest on a flat surface and allow the assembly material to move thereon.

20. The assembly material recycling system as described in claim 18, wherein, The at least one tool component includes a downwardly extending pin having a head configured to be received within a receiving feature.

21. The assembly material recycling system as described in claim 20, wherein, The receiver includes at least one receiving feature configured to be engaged by the pin of the at least one tool member to engage the receiver and move the receiver from a storage position to the top surface of the template.

22. The assembly material recycling system as described in claim 21, wherein, The at least one tool member includes two spaced-apart tool members, namely a first tool member and a second tool member, each tool member including a pin, the first tool member being configured to move laterally on a first linear bearing, and the second tool member being configured to move laterally on a second linear bearing, wherein the at least one receiving feature includes two receiving features, one receiving feature for one tool member, the first tool member and the second tool member being received in the corresponding receiving feature of the receiving seat to releasably secure the receiving seat.

23. The assembly material recycling system as described in claim 22, wherein, The support assembly of the stencil printing machine is configured to move in the z-axis direction and be raised to engage a magnet mounted in the bottom of the receiver, the support assembly including a steel surface to secure the receiver in place on the stencil.

24. A stencil printing machine for printing assembly materials on an electronic substrate, the stencil printing machine comprising: frame; A template connected to the rack, the template having openings formed therein; A support assembly connected to the rack, the support assembly being configured to support the electronic substrate; A printing head gantry connected to the frame; A printhead assembly supported by the printhead gantry, configured to traverse the template during the printing stroke; as well as An assembly material recycling system is configured to remove assembly material from the top surface of a template and deposit the material onto a new replacement template. The system includes at least one tooling member and a receiving seat configured to be positioned on the top surface of the template. The tooling member is coupled to the printhead gantry and configured to move laterally on the printhead gantry. The receiving seat includes at least one receiving feature. The at least one tool component includes a downwardly extending pin having a head configured to be received within the receiving feature to engage and move the receiving seat.

25. The template printing machine as described in claim 24, wherein, The receiving seat is positioned on the top surface of the template from a storage location, which is the track of the template support assembly.

26. The template printing machine as claimed in claim 24, wherein, The receiving seat includes a flat bottom wall configured to rest on a flat surface and allow the assembly material to roll thereon.

27. The template printing machine as claimed in claim 24, wherein, The printhead gantry includes an elongated beam spanning along a track disposed on the frame, the elongated beam of the printhead gantry including at least one linear bearing extending in a horizontal direction, and the at least one tool member being configured to move laterally on the at least one linear bearing.

28. The template printing machine as claimed in claim 27, wherein, The at least one tool component includes two spaced-apart tool components, namely a first tool component and a second tool component, each tool component including a pin, the first tool component being configured to move laterally on a first linear bearing, and the second tool component being configured to move laterally on a second linear bearing.

29. The template printing machine as described in claim 28, wherein, The at least one receiving feature includes two receiving features, one receiving feature for a tool component, wherein the head of the pin of each of the first and second tool components is received in the corresponding receiving feature of the receiving seat to releasably secure the receiving seat.

30. The template printing machine as described in claim 24, wherein, The support assembly is configured to move in the z-axis direction and be raised to engage a magnet mounted in the bottom of the receiver, the support assembly including a steel surface to secure the receiver in place on the template.

31. The template printing machine as described in claim 24, wherein, The printhead assembly includes a printhead having a scraper blade assembly configured to move assembly material along the template, the scraper blade assembly including a first scraper blade configured to engage the template and roll the assembly material into the receiver.

32. The template printing machine as described in claim 31, wherein, The scraper blade assembly further includes a second scraper blade configured to engage the receiver and roll assembly material onto the template.

33. An assembly material recycling system configured to remove assembly material from the top surface of a stencil of a stencil printing machine and deposit the assembly material onto a new replacement stencil, the assembly material recycling system comprising: At least one tooling component, the at least one tooling component being coupled to the printhead gantry of the stencil printing machine and configured to move laterally on the printhead gantry; as well as A receiver, configured to be positioned on the top surface of the template, includes at least one receiving feature. The at least one tool component includes a downwardly extending pin having a head configured to be received within a receiving feature to engage and move the receiving seat.

34. The assembly material recycling system as described in claim 33, wherein, The receiving seat includes a flat bottom wall configured to rest on a flat surface and allow the assembly material to move thereon.

35. The assembly material recycling system as described in claim 33, wherein, The elongated beam of the printing head gantry includes at least one linear bearing that extends in the horizontal direction.

36. The assembly material recycling system as described in claim 35, wherein, The pin of the at least one tool component is configured to engage the receiver and move the receiver from a storage position to the top surface of the template.

37. The assembly material recycling system as described in claim 35, wherein, The at least one tool component includes two spaced-apart tool components, namely a first tool component and a second tool component, each tool component including a pin, the first tool component being configured to move laterally on a first linear bearing, and the second tool component being configured to move laterally on a second linear bearing.

38. The assembly material recycling system as described in claim 37, wherein, The at least one receiving feature includes two receiving features, one receiving feature for a tool component, wherein the head of the pin of each first tool component and second tool component is received in the corresponding receiving feature of the receiving seat to releasably secure the receiving seat.

39. The assembly material recycling system as described in claim 33, wherein, The support assembly of the stencil printing machine is configured to move in the z-axis direction and be raised to engage a magnet mounted in the bottom of the receiver, the support assembly including a steel surface to secure the receiver in place on the stencil.

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