WO2012164233A2 - Screen printing machine and method - Google Patents

Screen printing machine and method Download PDF

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Publication number
WO2012164233A2
WO2012164233A2 PCT/GB2011/000535 GB2011000535W WO2012164233A2 WO 2012164233 A2 WO2012164233 A2 WO 2012164233A2 GB 2011000535 W GB2011000535 W GB 2011000535W WO 2012164233 A2 WO2012164233 A2 WO 2012164233A2
Authority
WO
WIPO (PCT)
Prior art keywords
printing
screen printing
screen
workpiece
machine
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Ceased
Application number
PCT/GB2011/000535
Other languages
French (fr)
Other versions
WO2012164233A3 (en
Inventor
Ian Broadhurst
David GAUKROGER
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
ASM Assembly Systems Switzerland GmbH
Original Assignee
DTG International GmbH
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by DTG International GmbH filed Critical DTG International GmbH
Anticipated expiration legal-status Critical
Publication of WO2012164233A2 publication Critical patent/WO2012164233A2/en
Publication of WO2012164233A3 publication Critical patent/WO2012164233A3/en
Ceased legal-status Critical Current

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Classifications

    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
    • H05K3/00—Apparatus or processes for manufacturing printed circuits
    • H05K3/10—Apparatus or processes for manufacturing printed circuits in which conductive material is applied to the insulating support in such a manner as to form the desired conductive pattern
    • H05K3/12—Apparatus or processes for manufacturing printed circuits in which conductive material is applied to the insulating support in such a manner as to form the desired conductive pattern using thick film techniques, e.g. printing techniques to apply the conductive material or similar techniques for applying conductive paste or ink patterns
    • H05K3/1216—Apparatus or processes for manufacturing printed circuits in which conductive material is applied to the insulating support in such a manner as to form the desired conductive pattern using thick film techniques, e.g. printing techniques to apply the conductive material or similar techniques for applying conductive paste or ink patterns by screen printing or stencil printing
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
    • B41F—PRINTING MACHINES OR PRESSES
    • B41F15/00—Screen printers
    • B41F15/08—Machines
    • B41F15/0881—Machines for printing on polyhedral articles
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
    • B41F—PRINTING MACHINES OR PRESSES
    • B41F33/00—Indicating, counting, warning, control or safety devices
    • B41F33/0036—Devices for scanning or checking the printed matter for quality control
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
    • B41F—PRINTING MACHINES OR PRESSES
    • B41F33/00—Indicating, counting, warning, control or safety devices
    • B41F33/0081—Devices for scanning register marks
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
    • B41P—INDEXING SCHEME RELATING TO PRINTING, LINING MACHINES, TYPEWRITERS, AND TO STAMPS
    • B41P2215/00—Screen printing machines
    • B41P2215/10—Screen printing machines characterised by their constructional features
    • B41P2215/11—Registering devices
    • B41P2215/112—Registering devices with means for displacing the frame
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
    • B41P—INDEXING SCHEME RELATING TO PRINTING, LINING MACHINES, TYPEWRITERS, AND TO STAMPS
    • B41P2215/00—Screen printing machines
    • B41P2215/50—Screen printing machines for particular purposes
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
    • H05K3/00—Apparatus or processes for manufacturing printed circuits
    • H05K3/30—Assembling printed circuits with electric components, e.g. with resistors
    • H05K3/32—Assembling printed circuits with electric components, e.g. with resistors electrically connecting electric components or wires to printed circuits
    • H05K3/34—Assembling printed circuits with electric components, e.g. with resistors electrically connecting electric components or wires to printed circuits by soldering
    • H05K3/3465—Application of solder
    • H05K3/3485—Application of solder paste, slurry or powder

Definitions

  • the present invention relates to a screen printing machine and method for printing onto workpieces, such as circuit boards or solar cell wafers, through a printing screen, often alternatively referred to as a stencil or foil.
  • the present invention provides a screen printing machine, comprising : a printing station at which workpieces are printed; an inspection station downstream of the printing station for inspecting printed workpieces; and a printing machine controller for controlling one or more operating parameters of the screen printing machine based on results obtained from inspections performed at the inspection station and/or results obtained from inspections performed at one or more other screen printing machines.
  • the present invention provides a machine control system, comprising : a plurality of screen printing machines, each comprising a printing station at which workpieces are printed, an inspection station downstream of the printing station for inspecting printed workpieces, and a printing machine controller for controlling one or more operating parameters of the screen printing machine; and a remote processing station which is in communication with the plurality of screen printing machines to receive inspection results associated with inspected workpieces as printed by the screen printing machines, and comprises a trend recognition application which provides for identification of trends from within the received inspection results.
  • the present invention provides a screen printing machine, comprising : a printing station at which workpieces are printed; an inspection station downstream of the printing station for inspecting printed workpieces; a printing machine controller for controlling operation of the screen printing machine; and storage which stores inspection results for printed workpieces.
  • the present invention provides a machine control system, comprising : a plurality of screen -printing machines, each comprising a printing station at which workpieces are printed, an inspection station downstream of the printing station for inspecting printed workpieces, and a printing machine controller for controlling operation of the screen printing machine; and a remote processing station which is in communication with the plurality of screen printing machines to receive inspection results associated with inspected workpieces as printed by the screen printing machines, and comprises storage which stores inspection results for printed workpieces.
  • the present invention provides a screen printing method, comprising the steps of: providing a screen printing machine comprising a printing station and an inspection station; printing workpieces at the printing station; inspecting printed workpieces at the inspection station; and controlling one or more operating parameters of the screen printing machine based on results obtained from inspections performed at the inspection station and/or results obtained from inspections performed at one or more other screen printing machines.
  • the present invention provides a screen printing method, comprising the steps of: providing a plurality of screen printing machines, each comprising a printing station and an inspection station; printing workpieces at the printing stations of the screen printing machines; inspecting printed workpieces at the inspection stations of the screen printing machines; providing a remote processing station which is in communication with the plurality of screen printing machines; communicating inspection results associated with inspected workpieces as printed by the screen printing machines to the processing station; identifying trends from within the communicated inspection results; and controlling one or more operating parameters of one or more of the screen printing machines in response to the identified trends.
  • the present invention provides a screen printing method, comprising the steps of: providing a screen printing machine comprising a printing station and an inspection station; printing workpieces at the printing station; inspecting printed workpieces at the inspection station; and storing inspection results for printed workpieces.
  • the present invention provides a screen printing method, comprising the steps of: providing a plurality of screen printing machines, each comprising a printing station and an inspection station ; printing workpieces at the printing stations of the screen printing machines; inspecting printed workpieces at the inspection stations of the screen printing machines; providing a remote processing station which is in communication with the plurality of screen printing machines; communicating inspection results associated with inspected workpieces as printed by the screen printing machines to the processing station; and storing inspection results for printed workpieces at the processing station.
  • the present invention provides a screen printing machine and method in which one or more of the machine parameters are controlled in real time based on results obtained from an inspection performed downstream of the printing zone of the screen printing machine, preferably by closed-loop feedback control.
  • This mode of control enables real-time optimization and robust error recognition.
  • the present invention enables trend identification, both at a component level, for example, being an artefact specific to a particular printing screen or support tooling, or at a general, machine level, being an artefact of particular kinds of printing screen, support tooling, print media and cleaning materials.
  • the downstream inspection is performed in parallel with the printing operation and within the print cycle, thereby enabling process and workpiece verification for all printed workpieces at the line beat rate, typically between 5 and 7 s for a 150 mm x 200 mm workpiece, and consequently enabling all defective workpieces to be rejected automatically, improving yield and quality without any penalty in terms of cycle time.
  • the screen printing machine and method allows for serial processing, which is suited to lower-volume operations and allows additional processes, such as dispensing and corrective actions, for example, cleaning, to be performed before the next workpiece is printed.
  • the printing station and the inspection station are fully integrated, providing a much smaller footprint than existing machine solutions and requiring only a single user interface, reducing setup and training requirements and also facilitating reporting.
  • the screen printing machine and method provides for traceability to workpiece and pad level, with pad level results and the printed workpiece image being recorded for every workpiece.
  • the present invention provides a screen printing machine and method in which one or more of the machine parameters are controlled in real time based on results obtained from inspections performed in one or more other screen printing machines, preferably by closed-loop feedback control.
  • Figure 1 schematically represents a screen printing machine in accordance with a preferred embodiment of the present invention.
  • Figure 2 illustrates the configuration of the printing machine and inspection station controllers of the printing machine of Figure 1.
  • the screen printing machine 1 comprises a printing station 3 at which workpieces W are printed, an inspection station 5 downstream of the printing station 3 for inspecting the printed workpieces W, a review/rejection station 6 at which defective workpieces W are reviewed/rejected, a conveyor assembly 7 for conveying workpieces W to and from the printing machine 1, and a printing machine controller 8 for controlling operation of the printing machine 1.
  • the printing machine 1 provides for the printing of solder paste, but many other kinds of print media could be employed, such as an adhesive or a loaded silver paste.
  • the printing station 3 comprises a workpiece support 11 on which a workpiece W is supported in the printing operation, a printing screen S which includes a pattern of printing apertures and through which print medium is printed onto a supported workpiece W, an imaging module 15 for imaging fiducials on the upper surface of the workpiece W and the lower surface of the printing screen S, an alignment mechanism 17 for aligning the printing screen S relative to the workpiece W based on the imaged locations of the fiducials on the workpiece W and the printing screen S, and a print module 19 which is operative to print deposits of print medium through the pattern of apertures in the printing screen S onto the upper surface of the workpiece W.
  • the workpiece support 11 is operative to support a workpiece W thereat, in this embodiment by raising the workpiece W from the conveyor assembly 7 to a first, imaging position to allow for imaging by the imaging module 15 and a second, printing position to allow for printing by the print module 19.
  • the imaging module 15 comprises an imaging camera 21 and a drive 23, which, when a workpiece W is supported by the workpiece support 11 at the imaging position, is operative to drive the imaging camera 21 between the supported workpiece W and the printing screen S, and acquire images of fiduciais on the upper surface of the supported workpiece W and the lower surface of the printing screen S.
  • the alignment mechanism 17 comprises a drive 25 for moving the printing screen S in X, Y and ⁇ based on the locations of the fiduciais on the workpiece W and the printing screen S, such as to align the printing screen S relative to the supported workpiece W.
  • the print module 19 comprises a printing element 31 , here in the form of a pair of squeegees, and a drive 33 which is operable to drive the printing element 31 over the printing screen S and print deposits of print medium through the pattern of apertures in the printing screen S onto a workpiece W when supported therebelow at the printing position by the workpiece support 11.
  • the printing element 31 could comprise an enclosed print head, such as the ProFlow (RT ) print head as supplied by DEK.
  • the inspection station 5 comprises a camera module 51 for acquiring and processing an image of each printed workpiece W within the line beat of the printing machine 1, and an inspection station controller 53 for controlling operation of the inspection station 5.
  • the camera module 51 comprises an imaging camera 55, here illuminated by strobe illumination, which provides for a full-width workpiece inspection, here 300 mm, and beneath which the workpieces W are transported to perform a full-area workpiece inspection of each workpiece W.
  • a full-area workpiece inspection comprises an inspection of at least 50 % of the workpiece area, preferably at least 75 % of the workpiece area, more preferably at least 90 % of the workpiece area, and still more preferably the entire workpiece area .
  • the imaging camera 55 is configured to perform a full- area workpiece inspection at workpiece transport speeds of up to 150 mm/s, with an image resolution of 15 pm and an image acquisition speed of 36000 mrnVs.
  • the inspection station controller 53 is a PC-based controller which has an API 57 for the camera module 51 and a server application 59 for communication with the printing machine controller 8, and includes RAM 61 for storing the current stitched workpiece image and inspection results, and storage 63, here a hard drive, for archiving the stitched workpiece images and inspection results for all inspected workpieces W.
  • the camera module 51 is supplied with the Gerber data, here in converted form as expected by the API 57, which allows the camera module 51 to registrate and process the stitched workpiece image to provide the required inspection results, including print medium on pad and bridging data.
  • the user is prompted to provide this data, and otherwise no inspection is performed.
  • the review/reject station 6 allows for a failed workpiece W to be rejected automatically, removing the failed workpieces W from the line without user intervention, or allows for . one or both of a failed workpiece W or the printing screen S to be reviewed prior to performing the next print operation.
  • the conveyor assembly 7 comprises a first, infeed conveyor 7a which receives workpieces W and successively delivers the same to the printing station 3, a second, print conveyor 7b which receives a workpiece W from the infeed conveyor 7a, locates the same at a print zone within the printing station 3 and, subsequent to printing, transfers the printed workpiece W downstream, and a third, inspection conveyor 7c which receives a workpiece W from the print conveyor 7b, transfers the same through and downstream of the inspection station 5 to the review/reject station 6.
  • the conveyor assembly 7 is configured simultaneously to handle up to three workpieces W at any one time by operation of the infeed, print and inspection conveyors 7a, 7b, 7c.
  • the infeed conveyor 7a is operative to receive and hold a workpiece W thereat, and transfer the workpiece W to the print conveyor 7b when there is no workpiece W on the print conveyor 7b.
  • the print conveyor 7b is operative to transfer a workpiece W to the print zone of the printing station 3, and, following printing, transfer the printed workpiece W to the inspection station 5 when there is no workpiece W at the inspection conveyor 7c.
  • the inspection conveyor 7c is operative to transfer a printed workpiece W through the inspection station 5 to the review/reject station 6.
  • the printing machine controller 8 is a PC-based controller which controls operation of the printing machine 1, and provides for control input both from an operator and also automatically by closed- loop control based on results from inspections performed by the inspection station 5 and/or results from inspections performed at other screen printing machines l 1-n , as will be described in more detail hereinbelow.
  • the printing station controller 8 has a user interface 71 by means of which operational status of the printing machine 1, including the inspection results determined by the inspection station 5, is displayed to the user and the user can provide control inputs to control operation of the printing machine 1.
  • the printing machine controller 8 has a client application 73 for communicating with the inspection station controller 53 of the inspection station 5, in this embodiment over a LAN, and also with a remote server 81, as will be described in more detail hereinbelow.
  • client/server applications 73, 59 provide a mechanism for passing requests to the API 57 of the camera module 51 and enable the supply of more manageable amounts of data therebetween.
  • client/server applications 73, 59 provide for the following tasks:
  • the printing machine controller 8 has a closed-loop control application 75 which provides for closed-loop control of the printing station 3, in particular to alignment of the printing screen S, cleaning of the printing screen S and dispensing of the print medium onto the printing screen S, based on the inspection results determined by the inspection station 5.
  • the parameters can be environmental factors, including ambient factors, such as temperature, humidity, contamination and vibration.
  • the parameters can be method parameters, including process parameters, such as cleaning frequency, print pressure, print speed, cleaning mode, print gap, print medium dispensing rate, print length and recovery actions, and process control parameters, such as continuous improvement, print deposit verification, recovery actions, and on-board SPC.
  • process parameters such as cleaning frequency, print pressure, print speed, cleaning mode, print gap, print medium dispensing rate, print length and recovery actions
  • process control parameters such as continuous improvement, print deposit verification, recovery actions, and on-board SPC.
  • the parameters can be external material parameters, including printing medium parameters, such as metallurgy, metal content, particle size, particle shape, viscosity, flux type, rheology and slump properties, workpiece parameters, such as mask material, pad finish, pad geometry, warpage, topography, thickness, registration, panelization, pad density and pad-to-edge distance, and peripheral parameters, such as temperature control unit, conveyors and flippers.
  • printing medium parameters such as metallurgy, metal content, particle size, particle shape, viscosity, flux type, rheology and slump properties
  • workpiece parameters such as mask material, pad finish, pad geometry, warpage, topography, thickness, registration, panelization, pad density and pad-to-edge distance
  • peripheral parameters such as temperature control unit, conveyors and flippers.
  • the parameters can be process hardware parameters, including print element/squeegee parameters, such as overhang, material, length, coating and angle, cleaning agent parameters, including activation, odour, evaporation, hazard, residuals/solids, storage risk, flashpoint, compatibility with print medium and toxicology, cleaning fabric parameters, such as wicking, absorbency, lint content, porosity and length, support tooling parameters, such as flatness, topography, architecture design, vacuum and type, and printing screen parameters, such as material, mounting system, aperture finish, foil size, foil thickness, registration, architecture design, wall definition and fabrication method.
  • print element/squeegee parameters such as overhang, material, length, coating and angle
  • cleaning agent parameters including activation, odour, evaporation, hazard, residuals/solids, storage risk, flashpoint, compatibility with print medium and toxicology
  • cleaning fabric parameters such as wicking, absorbency, lint content, porosity and length
  • support tooling parameters such as flatness,
  • the parameters can include machine parameters, including print head parameters, such as pressure feedback, speed feedback and compliancy, rail system parameters, such as configurability, width adjustment, robustness and flatness, calibration parameters, such as pressure, speed, alignment and position, requirements, such as serviceability, repeatability and accuracy, and utilisation parameters, such as ease of set-up, speed of set-up, ease of use and repeatability of set-up.
  • print head parameters such as pressure feedback, speed feedback and compliancy
  • rail system parameters such as configurability, width adjustment, robustness and flatness
  • calibration parameters such as pressure, speed, alignment and position
  • requirements such as serviceability, repeatability and accuracy
  • utilisation parameters such as ease of set-up, speed of set-up, ease of use and repeatability of set-up.
  • the input parameter is a user-related parameter, including user-education parameters, such as working practices, operator, machine type and process type, user set-up parameters, such as print platform set-up, print medium bead size, print medium storage, print element/squeegee assemblies and consumables, and local support parameters, such as operator, machine type and process type.
  • user-education parameters such as working practices, operator, machine type and process type
  • user set-up parameters such as print platform set-up, print medium bead size, print medium storage, print element/squeegee assemblies and consumables
  • local support parameters such as operator, machine type and process type.
  • Table 1 below represents these variables which can provide for real-time control of the printing machine 1.
  • the printing machine controller 8 also has a trend recognition application 77 which provides for identification of trends, allowing for user prompting, such as to more optimal configurations, and/or automatic invocation of the closed-loop control application 75 on identification of a rectifiable trend.
  • trend identification is achieved using classification, regression and/or fuzzy logic techniques.
  • the present invention provides a machine control system which includes a remote processing station 81, which provides for processing of the inspection results from a plurality of printing machines l 1-n .
  • the remote processing station 81 has a server application 83 for enabling communication with the plurality of printing machines li- n , and also a trend recognition application 85 for identifying trends from the inspection results from the plurality of printing machi nes li- n and providing for user prompting, such as to more optimal configurations, and/or automatic invocation of the closed-loop control application 75 of all subscribing printing machines li -n .
  • the knowledge base is extended.

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  • Engineering & Computer Science (AREA)
  • Manufacturing & Machinery (AREA)
  • Microelectronics & Electronic Packaging (AREA)
  • Quality & Reliability (AREA)
  • Mechanical Engineering (AREA)
  • Inking, Control Or Cleaning Of Printing Machines (AREA)
  • Screen Printers (AREA)

Abstract

A screen printing machine and method, the screen printing machine comprising : a printing station at which workpieces are printed; an inspection station downstream of the printing station for inspecting printed workpieces; and a printing machine controller for controlling one or more operating parameters of the screen printing machine based on results obtained from inspections performed at the inspection station and/or results obtained from inspections performed at one or more other screen printing machines.

Description

SCREEN PRINTING MACHINE AND METHOD
The present invention relates to a screen printing machine and method for printing onto workpieces, such as circuit boards or solar cell wafers, through a printing screen, often alternatively referred to as a stencil or foil.
In one aspect the present invention provides a screen printing machine, comprising : a printing station at which workpieces are printed; an inspection station downstream of the printing station for inspecting printed workpieces; and a printing machine controller for controlling one or more operating parameters of the screen printing machine based on results obtained from inspections performed at the inspection station and/or results obtained from inspections performed at one or more other screen printing machines.
In another aspect the present invention provides a machine control system, comprising : a plurality of screen printing machines, each comprising a printing station at which workpieces are printed, an inspection station downstream of the printing station for inspecting printed workpieces, and a printing machine controller for controlling one or more operating parameters of the screen printing machine; and a remote processing station which is in communication with the plurality of screen printing machines to receive inspection results associated with inspected workpieces as printed by the screen printing machines, and comprises a trend recognition application which provides for identification of trends from within the received inspection results.
In a further aspect the present invention provides a screen printing machine, comprising : a printing station at which workpieces are printed; an inspection station downstream of the printing station for inspecting printed workpieces; a printing machine controller for controlling operation of the screen printing machine; and storage which stores inspection results for printed workpieces. In yet another aspect the present invention provides a machine control system, comprising : a plurality of screen -printing machines, each comprising a printing station at which workpieces are printed, an inspection station downstream of the printing station for inspecting printed workpieces, and a printing machine controller for controlling operation of the screen printing machine; and a remote processing station which is in communication with the plurality of screen printing machines to receive inspection results associated with inspected workpieces as printed by the screen printing machines, and comprises storage which stores inspection results for printed workpieces.
In yet another aspect the present invention provides a screen printing method, comprising the steps of: providing a screen printing machine comprising a printing station and an inspection station; printing workpieces at the printing station; inspecting printed workpieces at the inspection station; and controlling one or more operating parameters of the screen printing machine based on results obtained from inspections performed at the inspection station and/or results obtained from inspections performed at one or more other screen printing machines.
In still another aspect the present invention provides a screen printing method, comprising the steps of: providing a plurality of screen printing machines, each comprising a printing station and an inspection station; printing workpieces at the printing stations of the screen printing machines; inspecting printed workpieces at the inspection stations of the screen printing machines; providing a remote processing station which is in communication with the plurality of screen printing machines; communicating inspection results associated with inspected workpieces as printed by the screen printing machines to the processing station; identifying trends from within the communicated inspection results; and controlling one or more operating parameters of one or more of the screen printing machines in response to the identified trends. In yet another aspect the present invention provides a screen printing method, comprising the steps of: providing a screen printing machine comprising a printing station and an inspection station; printing workpieces at the printing station; inspecting printed workpieces at the inspection station; and storing inspection results for printed workpieces.
In still another aspect the present invention provides a screen printing method, comprising the steps of: providing a plurality of screen printing machines, each comprising a printing station and an inspection station ; printing workpieces at the printing stations of the screen printing machines; inspecting printed workpieces at the inspection stations of the screen printing machines; providing a remote processing station which is in communication with the plurality of screen printing machines; communicating inspection results associated with inspected workpieces as printed by the screen printing machines to the processing station; and storing inspection results for printed workpieces at the processing station.
In a still further aspect the present invention provides a screen printing machine and method in which one or more of the machine parameters are controlled in real time based on results obtained from an inspection performed downstream of the printing zone of the screen printing machine, preferably by closed-loop feedback control.
This mode of control enables real-time optimization and robust error recognition.
In addition, through post-print analysis, the present invention enables trend identification, both at a component level, for example, being an artefact specific to a particular printing screen or support tooling, or at a general, machine level, being an artefact of particular kinds of printing screen, support tooling, print media and cleaning materials. In a preferred embodiment the downstream inspection is performed in parallel with the printing operation and within the print cycle, thereby enabling process and workpiece verification for all printed workpieces at the line beat rate, typically between 5 and 7 s for a 150 mm x 200 mm workpiece, and consequently enabling all defective workpieces to be rejected automatically, improving yield and quality without any penalty in terms of cycle time.
In another embodiment the screen printing machine and method allows for serial processing, which is suited to lower-volume operations and allows additional processes, such as dispensing and corrective actions, for example, cleaning, to be performed before the next workpiece is printed.
In a preferred embodiment the printing station and the inspection station are fully integrated, providing a much smaller footprint than existing machine solutions and requiring only a single user interface, reducing setup and training requirements and also facilitating reporting.
In a preferred embodiment the screen printing machine and method provides for traceability to workpiece and pad level, with pad level results and the printed workpiece image being recorded for every workpiece.
In still yet another aspect the present invention provides a screen printing machine and method in which one or more of the machine parameters are controlled in real time based on results obtained from inspections performed in one or more other screen printing machines, preferably by closed-loop feedback control.
Preferred embodiments of the present invention will now be described hereinbelow by way of example only with reference to the accompanying drawings, in which : Figure 1 schematically represents a screen printing machine in accordance with a preferred embodiment of the present invention; and
Figure 2 illustrates the configuration of the printing machine and inspection station controllers of the printing machine of Figure 1.
The screen printing machine 1 comprises a printing station 3 at which workpieces W are printed, an inspection station 5 downstream of the printing station 3 for inspecting the printed workpieces W, a review/rejection station 6 at which defective workpieces W are reviewed/rejected, a conveyor assembly 7 for conveying workpieces W to and from the printing machine 1, and a printing machine controller 8 for controlling operation of the printing machine 1.
In this embodiment the printing machine 1 provides for the printing of solder paste, but many other kinds of print media could be employed, such as an adhesive or a loaded silver paste.
In this embodiment the printing station 3 comprises a workpiece support 11 on which a workpiece W is supported in the printing operation, a printing screen S which includes a pattern of printing apertures and through which print medium is printed onto a supported workpiece W, an imaging module 15 for imaging fiducials on the upper surface of the workpiece W and the lower surface of the printing screen S, an alignment mechanism 17 for aligning the printing screen S relative to the workpiece W based on the imaged locations of the fiducials on the workpiece W and the printing screen S, and a print module 19 which is operative to print deposits of print medium through the pattern of apertures in the printing screen S onto the upper surface of the workpiece W.
In this embodiment the workpiece support 11 is operative to support a workpiece W thereat, in this embodiment by raising the workpiece W from the conveyor assembly 7 to a first, imaging position to allow for imaging by the imaging module 15 and a second, printing position to allow for printing by the print module 19.
In this embodiment the imaging module 15 comprises an imaging camera 21 and a drive 23, which, when a workpiece W is supported by the workpiece support 11 at the imaging position, is operative to drive the imaging camera 21 between the supported workpiece W and the printing screen S, and acquire images of fiduciais on the upper surface of the supported workpiece W and the lower surface of the printing screen S.
In this embodiment the alignment mechanism 17 comprises a drive 25 for moving the printing screen S in X, Y and Θ based on the locations of the fiduciais on the workpiece W and the printing screen S, such as to align the printing screen S relative to the supported workpiece W.
In this embodiment the print module 19 comprises a printing element 31 , here in the form of a pair of squeegees, and a drive 33 which is operable to drive the printing element 31 over the printing screen S and print deposits of print medium through the pattern of apertures in the printing screen S onto a workpiece W when supported therebelow at the printing position by the workpiece support 11. In an alternative embodiment the printing element 31 could comprise an enclosed print head, such as the ProFlow (RT ) print head as supplied by DEK.
In this embodiment the inspection station 5 comprises a camera module 51 for acquiring and processing an image of each printed workpiece W within the line beat of the printing machine 1, and an inspection station controller 53 for controlling operation of the inspection station 5.
In this embodiment the camera module 51 comprises an imaging camera 55, here illuminated by strobe illumination, which provides for a full-width workpiece inspection, here 300 mm, and beneath which the workpieces W are transported to perform a full-area workpiece inspection of each workpiece W. In this embodiment a full-area workpiece inspection comprises an inspection of at least 50 % of the workpiece area, preferably at least 75 % of the workpiece area, more preferably at least 90 % of the workpiece area, and still more preferably the entire workpiece area .
In this embodiment the imaging camera 55 is configured to perform a full- area workpiece inspection at workpiece transport speeds of up to 150 mm/s, with an image resolution of 15 pm and an image acquisition speed of 36000 mrnVs.
In this embodiment the inspection station controller 53, as illustrated in Figure 2, is a PC-based controller which has an API 57 for the camera module 51 and a server application 59 for communication with the printing machine controller 8, and includes RAM 61 for storing the current stitched workpiece image and inspection results, and storage 63, here a hard drive, for archiving the stitched workpiece images and inspection results for all inspected workpieces W.
In this embodiment the camera module 51 is supplied with the Gerber data, here in converted form as expected by the API 57, which allows the camera module 51 to registrate and process the stitched workpiece image to provide the required inspection results, including print medium on pad and bridging data. In the event that no Gerber data is associated with the product, the user is prompted to provide this data, and otherwise no inspection is performed.
In this embodiment the review/reject station 6 allows for a failed workpiece W to be rejected automatically, removing the failed workpieces W from the line without user intervention, or allows for . one or both of a failed workpiece W or the printing screen S to be reviewed prior to performing the next print operation. In this embodiment the conveyor assembly 7 comprises a first, infeed conveyor 7a which receives workpieces W and successively delivers the same to the printing station 3, a second, print conveyor 7b which receives a workpiece W from the infeed conveyor 7a, locates the same at a print zone within the printing station 3 and, subsequent to printing, transfers the printed workpiece W downstream, and a third, inspection conveyor 7c which receives a workpiece W from the print conveyor 7b, transfers the same through and downstream of the inspection station 5 to the review/reject station 6.
In this embodiment the conveyor assembly 7 is configured simultaneously to handle up to three workpieces W at any one time by operation of the infeed, print and inspection conveyors 7a, 7b, 7c.
In this embodiment the infeed conveyor 7a is operative to receive and hold a workpiece W thereat, and transfer the workpiece W to the print conveyor 7b when there is no workpiece W on the print conveyor 7b.
In this embodiment the print conveyor 7b is operative to transfer a workpiece W to the print zone of the printing station 3, and, following printing, transfer the printed workpiece W to the inspection station 5 when there is no workpiece W at the inspection conveyor 7c.
In this embodiment the inspection conveyor 7c is operative to transfer a printed workpiece W through the inspection station 5 to the review/reject station 6.
In this embodiment the printing machine controller 8 is a PC-based controller which controls operation of the printing machine 1, and provides for control input both from an operator and also automatically by closed- loop control based on results from inspections performed by the inspection station 5 and/or results from inspections performed at other screen printing machines l1-n, as will be described in more detail hereinbelow. In this embodiment the printing station controller 8 has a user interface 71 by means of which operational status of the printing machine 1, including the inspection results determined by the inspection station 5, is displayed to the user and the user can provide control inputs to control operation of the printing machine 1.
In this embodiment the printing machine controller 8 has a client application 73 for communicating with the inspection station controller 53 of the inspection station 5, in this embodiment over a LAN, and also with a remote server 81, as will be described in more detail hereinbelow.
In this embodiment the client/server applications 73, 59 provide a mechanism for passing requests to the API 57 of the camera module 51 and enable the supply of more manageable amounts of data therebetween.
In this embodiment the client/server applications 73, 59 provide for the following tasks:
- supply converted Gerber data to the API 57;
- start/ stop inspection;
- request/receive area of inspected workpiece W to be displayed at the user interface 71;
- update camera image with current image;
- request/receive print medium and bridge inspection data for an area of the inspected workpiece W;
- update data tables with current image inspection data;
- perform handshaking with the API 57, such as Gerber conversion ready, completion of the inspection and results available
In this embodiment the printing machine controller 8 has a closed-loop control application 75 which provides for closed-loop control of the printing station 3, in particular to alignment of the printing screen S, cleaning of the printing screen S and dispensing of the print medium onto the printing screen S, based on the inspection results determined by the inspection station 5.
In one embodiment the parameters can be environmental factors, including ambient factors, such as temperature, humidity, contamination and vibration.
In another embodiment the parameters can be method parameters, including process parameters, such as cleaning frequency, print pressure, print speed, cleaning mode, print gap, print medium dispensing rate, print length and recovery actions, and process control parameters, such as continuous improvement, print deposit verification, recovery actions, and on-board SPC.
In another embodiment the parameters can be external material parameters, including printing medium parameters, such as metallurgy, metal content, particle size, particle shape, viscosity, flux type, rheology and slump properties, workpiece parameters, such as mask material, pad finish, pad geometry, warpage, topography, thickness, registration, panelization, pad density and pad-to-edge distance, and peripheral parameters, such as temperature control unit, conveyors and flippers.
In another embodiment the parameters can be process hardware parameters, including print element/squeegee parameters, such as overhang, material, length, coating and angle, cleaning agent parameters, including activation, odour, evaporation, hazard, residuals/solids, storage risk, flashpoint, compatibility with print medium and toxicology, cleaning fabric parameters, such as wicking, absorbency, lint content, porosity and length, support tooling parameters, such as flatness, topography, architecture design, vacuum and type, and printing screen parameters, such as material, mounting system, aperture finish, foil size, foil thickness, registration, architecture design, wall definition and fabrication method. In another embodiment the parameters can include machine parameters, including print head parameters, such as pressure feedback, speed feedback and compliancy, rail system parameters, such as configurability, width adjustment, robustness and flatness, calibration parameters, such as pressure, speed, alignment and position, requirements, such as serviceability, repeatability and accuracy, and utilisation parameters, such as ease of set-up, speed of set-up, ease of use and repeatability of set-up.
In another embodiment the input parameter is a user-related parameter, including user-education parameters, such as working practices, operator, machine type and process type, user set-up parameters, such as print platform set-up, print medium bead size, print medium storage, print element/squeegee assemblies and consumables, and local support parameters, such as operator, machine type and process type.
Table 1 below represents these variables which can provide for real-time control of the printing machine 1.
Figure imgf000014_0001
In this embodiment the printing machine controller 8 also has a trend recognition application 77 which provides for identification of trends, allowing for user prompting, such as to more optimal configurations, and/or automatic invocation of the closed-loop control application 75 on identification of a rectifiable trend. In one embodiment trend identification is achieved using classification, regression and/or fuzzy logic techniques.
In one embodiment, as illustrated in Figure 1, the present invention provides a machine control system which includes a remote processing station 81, which provides for processing of the inspection results from a plurality of printing machines l1-n.
In this embodiment the remote processing station 81 has a server application 83 for enabling communication with the plurality of printing machines li-n, and also a trend recognition application 85 for identifying trends from the inspection results from the plurality of printing machi nes li- n and providing for user prompting, such as to more optimal configurations, and/or automatic invocation of the closed-loop control application 75 of all subscribing printing machines li-n. By utilizing inspection results from a plurality of printing machines li-n, the knowledge base is extended.
Finally, it will be understood that the present invention has been described in its preferred embodiments and can be modified in many different ways without departing from the scope of the invention as defined by the appended claims.

Claims

1. A screen printing machine, comprising :
a printing station at which workpieces are printed;
an inspection station downstream of the printing station for inspecting printed workpieces; and
a printing machine controller for controlling one or more operating parameters of the screen printing machine based on results obtained from inspections performed at the inspection station and/or results obtained from inspections performed at one or more other screen printing machines.
2. The screen printing machine of claim 1, wherein the printing machine controller has a closed-loop control application which provides for closed-loop feedback control of one or more operating parameters of the screen printing machine based on results obtained from inspections performed at the inspection station and/or results obtained from inspections performed at one or more other screen printing machines.
3. The screen printing machine of claim 1 or 2, wherein the printing machine controller has a trend recognition application which provides for identification of trends in the results obtained from inspections performed at the inspection station and/or the results obtained from inspections performed at one or more other screen printing machines.
4. The screen printing machine of claim 3, wherein the trend identification is at a machine component level, such as an artefact specific to a particular printing screen, support tooling, print medium and cleaning material.
5. The screen printing machine of claim 3, wherein the trend identification is at a general, machine level, such as an artefact of particular kinds of printing screen, support tooling, print media and cleaning materials.
6. The screen printing machine of claim 3, wherein the trend identification is both at a component level, such as an artefact specific to a particular printing screen, support tooling, print medium and cleaning material, and at a general, machine level, such as an artefact of particular kinds of printing screen, support tooling, print media and cleaning materials.
7. The screen printing machine of any of claims 3 to 6, wherein an identified trend is notified as a user prompt, allowing a user to trigger the closed-loop control application.
8. The screen printing machine of any of claims 3 to 6, wherein the trend recognition application is configured, on identification of a rectifiable trend, automatically to trigger the closed-loop control application.
9. The screen printing machine of any of claims 1 to 8, wherein the inspection operation is performed in parallel with the printing operation.
10. The screen printing machine of claim 9, wherein the inspection operation is performed within a print cycle, thereby enabling process and workpiece verification for all printed workpieces at a line beat rate of the screen printing machine.
11. The screen printing machine of claim 10, wherein the printing cycle is less than 7 seconds.
12. The screen printing machine of claim 11, wherein the printing cycle is less than 5 seconds.
13. The screen printing machine of claim 10, wherein the printing cycle is between 5 and 7 seconds.
14. The screen printing machine of any of claims 1 to 8, wherein the inspection operation is performed subsequently to the printing operation.
15. The screen printing machine of any of claims 1 to 14, wherein the printing station and the inspection station are integrated, and further comprising:
a single user interface for the screen printing machine.
16. The screen printing machine of any of claims 1 to 15, further comprising:
storage which stores inspection results for printed workpieces.
17. The screen printing machine of claim 16, wherein the stored inspection results comprise workpiece-level results, enabling traceability of individual printed workpieces.
18. The screen printing machine of claim 17, wherein the stored inspection results comprise pad-level results, enabling traceability of individual printed pads on individual workpieces.
19. The screen printing machine of any of claims 16 to 18, wherein the storage stores printed workpiece images for the respective workpieces.
20. The screen printing machine of any of claims 1 to 19, wherein the printing station comprises a workpiece support on which a workpiece is supported in the printing operation, a printing screen which includes a pattern of printing apertures and through which print medium is printed onto a supported workpiece, and a print module which is operative to print deposits of print medium through the pattern of apertures in the printing screen onto an upper surface of the workpiece.
21. The screen printing machine of claim 20, wherein the printing station comprises an imaging module for imaging fiducials on an upper surface of the workpiece and a lower surface of the printing screen, and an alignment mechanism for aligning the printing screen relative to the workpiece based on the imaged locations of the fiducials on the workpiece and the printing screen.
22. The screen printing machine of claim 21, wherein the imaging module comprises an imaging camera and a drive, which is operative to drive the imaging camera between the supported workpiece and the printing screen, and acquire images of fiducials on the upper surface of the supported workpiece and the lower surface of the printing screen.
23. The screen printing machine of claim 21 or 22, wherein the workpiece support is operative to support a workpiece at a first, imaging position to allow for imaging by the imaging module and a second, printing position to allow for printing by the print module.
24. The screen printing machine of any of claims 21 to 23, wherein the alignment mechanism comprises a drive for moving the printing screen based on imaged locations of the fiducials on the workpiece and the printing screen, such as to align the printing screen relative to the supported workpiece.
25. The screen printing machine of any of claims 20 to 24, wherein the print module comprises a printing element, and a drive which is operable to drive the printing element over the printing screen and print deposits of print medium through the pattern of apertures in the printing screen onto a workpiece supported therebelow by the workpiece support.
26. The screen printing machine of any of claims 1 to 25, wherein the inspection station comprises a camera module for acquiring and processing images of printed workpieces, and an inspection station controller for controlling operation of the inspection station.
27. The screen printing machine of claim 26, wherein the camera module comprises an imaging camera which provides for a full-width workpiece inspection, and beneath which the workpieces are transported to perform a full-area workpiece inspection of workpieces.
28. The screen printing machine of claim 27, wherein a full-area workpiece inspection comprises an inspection of at least 50 % of the workpiece area, preferably at least 75 % of the workpiece area, more preferably at least 90 % of the workpiece area, and still more preferably the entire workpiece area.
29. The screen printing machine of claim 27 or 28, wherein the imaging camera is configured to perform a full-area workpiece inspection at workpiece transport speeds of up to 150 mm/s.
30. A machine control system, comprising:
a plurality of screen printing machines, each comprising a printing station at which workpieces are printed, an inspection station downstream of the printing station for inspecting printed workpieces, and a printing machine controller for controlling one or more operating parameters of the respective screen printing machine; and a remote processing station which is in communication with the plurality of screen printing machines to receive inspection results associated with inspected workpieces as printed by the screen printing machines, and comprises a trend recognition application which provides for identification of trends from within the received inspection results.
31. The machine control system of claim 30, wherein an identified trend is notified as a user prompt, allowing a user to adjust one or more operating parameters of the respective screen printing machine.
32. The machine control system of claim 30, wherein the trend recognition application is configured, on identification of a rectifiable trend, automatically to adjust one or more operating parameters of the respective screen printing machine.
33. The machine control system of claim 30, wherein the printing machine controller has a closed-loop control application which provides for closed-loop feedback control of one or more operating parameters of the respective screen printing machine.
34. The machine control system of claim . 33, wherein the trend recognition application is configured, on identification of a rectifiable trend, automatically to trigger the closed-loop control application.
35. The machine control system of any of claims 30 to 34, wherein the trend identification is at a machine component level, such as an artefact specific to a particular printing screen, support tooling, print medium and cleaning material.
36. The machine control system of any of claims 30 to 34, wherein the trend identification is at a general, machine level, such as an artefact of particular kinds of printing screen, support tooling, print media and cleaning materials.
37. The machine control system of any of claims 30 to 34, wherein the trend identification is both at a component level, such as an artefact specific to a particular printing screen, support tooling, print medium and cleaning material, and at a general, machine level, such as an artefact of particular kinds of printing screen, support tooling, print media and cleaning materials.
38. The machine control system of any of claims 30 to 37, wherein the inspection operation is performed in parallel with the printing operation.
39. The machine control system of claim 38, wherein the inspection operation is performed within a print cycle, thereby enabling process and workpiece verification for all printed workpieces at a line beat rate of each screen printing machine.
40. The machine control system of claim 39, wherein the printing cycle is less than 7 seconds.
41. The machine control system of claim 40, wherein the printing cycle is less than 5 seconds.
42. The machine control system of claim 39, wherein the printing cycle is between 5 and 7 seconds.
43. The machine control system of any of claims 30 to 37, wherein the inspection operation is performed subsequently to the printing operation.
44. The machine control system of any of claims 30 to 43, wherein the printing station and the inspection station of each screen printing machine are integrated, and each screen printing machine further comprises a single user interface.
45. The machine control system of any of claims 30 to 44, further comprising :
storage which stores inspection results for printed workpieces.
46. The machine control system of any of claims 30 to 44, wherein each screen printing machine further comprises storage which stores inspection results for printed workpieces.
47. The machine control system of claim 45 or 46, wherein the stored inspection results comprise workpiece-level results, enabling traceability of individual printed workpieces.
48. The machine control system of claim 47, wherein the stored inspection results comprise pad-level results, enabling traceability of individual printed pads on individual workpieces.
49. The machine control system of any of claims 45 to 48, wherein the storage stores printed workpiece images for the respective workpieces.
50. The machine control system of any of claims 30 to 49, wherein the printing station comprises a workpiece support on which a workpiece is supported in the printing operation, a printing screen which includes a pattern of printing apertures and through which print medium is printed onto a supported workpiece, and a print module which is operative to print deposits of print medium through the pattern of apertures in the printing screen onto an upper surface of the workpiece.
51. The machine control system of claim 50, wherein the printing station comprises an imaging module for imaging fiducials on an upper surface of the workpiece and a lower surface of the printing screen, and an alignment mechanism for aligning the printing screen relative to the workpiece based on the imaged locations of the fiducials on the workpiece and the printing screen.
52. The machine control system of claim 51, wherein the imaging module comprises an imaging camera and a drive, which is operative to drive the imaging camera between the supported workpiece and the printing screen, and acquire images of fiducials on the upper surface of the supported workpiece and the lower surface of the printing screen.
53. The machine control system of claim 51 or 52, wherein the workpiece support is operative to support a workpiece at a first, imaging position to allow for imaging by the imaging module and a second, printing position to allow for printing by the print module.
54. The machine control system of any of claims 51 to 53, wherein the alignment mechanism comprises a drive for moving the printing screen based on imaged locations of the fiducials on the workpiece and the printing screen, such as to align the printing screen relative to the supported workpiece.
55. The machine control system of any of claims 50 to 54, wherein the print module comprises a printing element, and a drive which is operable to drive the printing element over the printing screen and print deposits of print medium through the pattern of apertures in the printing screen onto a workpiece supported therebelow by the workpiece support.
56. The machine control system of any of claims 30 to 55, wherein the inspection station comprises a camera module for acquiring and processing images of printed workpieces, and an inspection station controller for controlling operation of the inspection station.
57. The machine control system of claim 56, wherein the camera module comprises an imaging camera which provides for a full-width workpiece inspection, and beneath which the workpieces are transported to perform a full-area workpiece inspection of workpieces.
58. The machine control system of claim 57, wherein a full-area workpiece inspection comprises an inspection of at least 50 % of the workpiece area, preferably at least 75 % of the workpiece area, more preferably at least 90 % of the workpiece area, and still more preferably the entire workpiece area.
59. The machine control system of claim 57 or 58, wherein the imaging camera is configured to perform a full-area workpiece inspection at workpiece transport speeds of up to 150 mm/s.
60. A screen printing machine, comprising :
a printing station at which workpieces are printed;
an inspection station downstream of the printing station for inspecting printed workpieces;
a printing machine controller for controlling operation of the screen printing machine; and
storage which stores inspection results for printed workpieces.
61. The screen printing machine of claim 60, wherein the inspection operation is performed in parallel with the printing operation.
62. The screen printing machine of claim 61, wherein the inspection operation is performed within a print cycle, thereby enabling process and workpiece verification for all printed workpieces at a line beat rate of the screen printing machine.
63. The screen printing machine of claim 62, wherein the printing cycle is less than 7 seconds.
64. The screen printing machine of claim 63, wherein the printing cycle is less than 5 seconds.
65. The screen printing machine of claim 62, wherein the printing cycle is between 5 and 7 seconds.
66. The screen printing machine of claim 60, wherein the inspection operation is performed subsequently to the printing operation.
67. The screen printing machine of any of claims 60 to 66, wherein the printing station and the inspection station are integrated, and further comprising :
a single user interface for the screen printing machine.
68. The screen printing machine of any of claims 60 to 67, wherein the stored inspection results comprise workpiece-level results, enabling traceability of individual printed workpieces.
69. The screen printing machine of claim 68, wherein the stored inspection results comprise pad-level results, enabling traceability of individual printed pads on individual workpieces.
70. The screen printing machine of any of claims 60 to 69, wherein the storage stores printed workpiece images for the respective workpieces.
71. A machine control system, comprising :
a plurality of screen printing machines, each comprising a printing station at which workpieces are printed, an inspection station downstream of the printing station for inspecting printed workpieces, and a printing machine controller for controlling operation of the screen printing machine; and a remote processing station which is in communication with the plurality of screen printing machines to receive inspection results associated with inspected workpieces as printed by the screen printing machines, and comprises storage which stores inspection results for printed workpieces.
72. The machine control system of claim 71, wherein the inspection operation is performed in parallel with the printing operation.
73. The machine control system of claim 72, wherein the inspection operation is performed within a print cycle, thereby enabling process and workpiece verification for all printed workpieces at a line beat rate of the screen printing machine.
74. The machine control system of claim 73, wherein the printing cycle is less than 7 seconds.
75. The machine control system of claim 74, wherein the printing cycle is less than 5 seconds.
76. The machine control system of claim 73, wherein the printing cycle is between 5 and 7 seconds.
77. The machine control system of claim 71, wherein the inspection operation is performed subsequently to the printing operation.
78. The machine control system of any of claims 71 to 77, wherein the printing station and the inspection station of each screen printing machine are integrated, and each screen printing machine further comprises a single user interface.
79. The machine control system of any of claims 71 to 78, wherein the stored inspection results comprise workpiece-level results, enabling traceability of individual printed workpieces.
80. The machine control system of claim 79, wherein the stored inspection results comprise pad-level results, enabling traceability of individual printed pads on individual workpieces.
81. The machine control system of any of claims 71 to 80, wherein the storage stores printed workpiece images for the respective workpieces.
82. A screen printing machine in which one or more of machine parameters are controlled in real time based on results obtained from an inspection performed downstream of a printing zone of the screen printing machine, preferably by closed-loop feedback control.
83. A screen printing machine in which one or more machine parameters are controlled in real time based on results obtained from inspections performed in one or more other screen printing machines, preferably by closed-loop feedback control.
84. A screen printing method, comprising the steps of:
providing a screen printing machine comprising a printing station and an inspection station;
printing workpieces at the printing station;
inspecting printed workpieces at the inspection station; and
controlling one or more operating parameters of the screen printing machine based on results obtained from inspections performed at the inspection station and/or results obtained from inspections performed at one or more other screen printing machines.
85. The screen printing method of claim 84, wherein the controlling step provides for closed-loop feedback control of one or more operating parameters of the screen printing machine based on results obtained from inspections performed at the inspection station and/or results obtained from inspections performed at one or more other screen printing machines.
86. The screen printing method of claim 84 or 85, wherein the controlling step provides for identification of trends in the results obtained from inspections performed at the inspection station and/or the results obtained from inspections performed at one or more other screen printing machines.
87. The screen printing method of claim 86, wherein the trend identification is at a machine component level, such as an artefact specific to a particular printing screen, support tooling, print medium and cleaning material.
88. The screen printing method of claim 87, wherein the trend identification is at a general, machine level, such as an artefact of particular kinds of printing screen, support tooling, print media and cleaning materials.
89. The screen printing method of claim 86, wherein the trend identification is both at a component level, such as an artefact specific to a particular printing screen, support tooling, print medium and cleaning material, and at a general, machine level, such as an artefact of particular kinds of printing screen, support tooling, print media and cleaning materials.
90. The screen printing method of any of claims 86 to 89, wherein the parameters utilized in trend identification include environmental factors, including ambient factors, such as temperature, humidity, contamination and vibration.
91. The screen printing method of any of claims 86 to 90, wherein the parameters utilized in trend identification include process-related parameters, including process parameters, such as cleaning frequency, print pressure, print speed, cleaning mode, print gap, print medium dispensing rate, print length and recovery actions, and/or process control parameters, such as continuous improvement, print deposit verification, recovery actions and on-board SPC.
92. The screen printing method of any of claims 86 to 91, wherein the parameters utilized in trend identification include external material parameters, including print medium parameters, such as metallurgy, metal content, particle size, particle shape, viscosity, flux type, rheology and slump properties, workpiece parameters, such as mask material, pad finish, pad geometry, warpage, topography, thickness, registration, panelization, pad density and pad-to-edge distance, and/or peripheral device parameters, such as temperature control unit, conveyors and flippers.
93. The screen printing method of any of claims 86 to 92, wherein the parameters utilized in trend identification include process hardware parameters, including print element/squeegee parameters, such as overhang, material, length, coating and angle, cleaning agent parameters, such as activation, odour, evaporation, hazard, residuals/solids, storage risk, flashpoint, compatibility with print medium and toxicology, cleaning fabric parameters, such as wicking, absorbency, lint content, porosity and length, support tooling parameters, such as flatness, topography, architecture design, vacuum and type, and/or printing screen parameters, such as material, mounting system, aperture finish, foil size, foil thickness, registration, architecture design, wall definition and fabrication method.
94. The screen printing method of any of claims 86 to 93, wherein the parameters utilized in trend identification include machine parameters, including print head parameters, such as pressure feedback, speed feedback and compliancy, rail system parameters, such as configurability, width adjustment, robustness and flatness, calibration parameters, such as pressure, speed, alignment and position, requirements, such as serviceability, repeatability and accuracy, and/or utilization parameters, such as ease of set-up, speed of set-up, ease of use and repeatability of set-up.
95. The screen printing method of any of claims 86 to 94, wherein the parameters utilized in trend identification include a user-related parameter, including user-education parameters, such as working practices, operator, machine type and process type, user set-up parameters, such as print platform set-up, print medium bead size, print medium storage, print element/squeegee assemblies and consumables, and/or local support parameters, such as operator, machine type and process type.
96. The screen printing method of any of claims 86 to 95, further comprising the step of:
notifying an identified trend as a user prompt, allowing a user to trigger the closed-loop control application.
97. The screen printing method of any of claims 86 to 95, further comprising the step of:
on identification of a rectifiable trend, automatically triggering the closed-loop feedback control.
98. The screen printing method of any of claims 84 to 97, wherein the inspection operation is performed in parallel with the printing operation.
99. The screen printing method of claim 98, wherein the inspection operation is performed within a print cycle, thereby enabling process and workpiece verification for all printed workpieces at a line beat rate of the screen printing machine.
100. The screen printing method of claim 99, wherein the printing cycle is less than 7 seconds.
101. The screen printing method of claim 100, wherein the printing cycle is less than 5 seconds.
102. The screen printing method of claim 99, wherein the printing cycle is between 5 and 7 seconds.
103. The screen printing method of any of claims 84 to 97, wherein the inspection operation is performed subsequently to the printing operation.
104. The screen printing method of any of claims 84 to 103, wherein the printing station and the inspection station are integrated, and the screen printing machine comprises a single user interface.
105. The screen printing method of any of claims 84 to 104, further comprising the step of:
storing inspection results for printed workpieces at the screen printing machine and/or remotely at a processing station.
106. The screen printing method of claim 105, wherein the stored inspection results comprise workpiece-level results, enabling traceability of individual printed workpieces.
107. The screen printing method of claim 106, wherein the stored inspection results comprise pad-level results, enabling traceability of individual printed pads on individual workpieces.
108. The screen printing method of any of claims 105 to 107, further comprising the step of:
storing printed workpiece images for the respective workpieces at the screen printing machine and/or remotely at a processing station.
109. The screen printing method of any of claims 84 to 108, wherein the printing station comprises a workpiece support on which a workpiece is supported in the printing operation, a printing screen which includes a pattern of printing apertures and through which print medium is printed onto a supported workpiece, and a print module which is operated to print deposits of print medium through the pattern of apertures in the printing screen onto an upper surface of the workpiece.
110. The screen printing method of claim 109, wherein the printing station comprises an imaging module for imaging fiducials on an upper surface of the workpiece and a lower surface of the printing screen, and an alignment mechanism for aligning the printing screen relative to the workpiece based on the imaged locations of the fiducials on the workpiece and the printing screen.
111. The screen printing method of claim 110, wherein the imaging module comprises an imaging camera and a drive, which is operated to drive the imaging camera between the supported workpiece and the printing screen, and acquire images of fiducials on the upper surface of the supported workpiece and the lower surface of the printing screen.
112. The screen printing method of claim 110 or 111, wherein the workpiece support is operated to support a workpiece at a first, imaging position to allow for imaging by the imaging module and a second, printing position to allow for printing by the print module.
113. The screen printing method of any of claims 110 to 112, wherein the alignment mechanism comprises a drive for moving the printing screen based on imaged locations of the fiducials on the workpiece and the printing screen, such as to align the printing screen relative to the supported workpiece.
114. The screen printing method of any of claims 109 to 113, wherein the print module comprises a printing element, and a drive which is operated to drive the printing element over the printing screen and print deposits of print medium through the pattern of apertures in the printing screen onto a workpiece supported therebelow by the workpiece support.
115. The screen printing method of any of claims 84 to 114, wherein the inspection station comprises a camera module for acquiring and processing images of printed workpieces.
116. The screen printing method of claim 115, wherein the camera module comprises an imaging camera which provides for a full-width workpiece inspection, and beneath which the workpieces are transported to perform a full-area workpiece inspection of workpieces.
117. The screen printing method of claim 116, wherein a full-area workpiece inspection comprises an inspection of at least 50 % of the workpiece area, preferably at least 75 % of the workpiece area, more preferably at least 90 % of the workpiece area, and still more preferably the entire workpiece area.
118. The screen printing method of claim 116 or 117, wherein the imaging camera is configured to perform a full-area workpiece inspection at workpiece transport speeds of up to 150 mm/s.
119. A screen printing method, comprising the steps of:
providing a plurality of screen printing machines, each comprising a printing station and an inspection station;
printing workpieces at the printing stations of the screen printing machines;
inspecting printed workpieces at the inspection stations of the screen printing machines;
providing a remote processing station which is in communication with the plurality of screen printing machines;
communicating inspection results associated with inspected workpieces as printed by the screen printing machines to the processing station;
identifying trends from within the communicated inspection results; and
controlling one or more operating parameters of one or more of the screen printing machines in response to the identified trends.
120. The screen printing method of claim 119, further comprising the step of:
notifying an identified trend as a user prompt, allowing a user to adjust one or more operating parameters of the respective screen printing machine.
121. The screen printing method of claim 119, further comprising the step of: on identification of a rectifiable trend, automatically adjusting one or more operating parameters of the respective screen printing machine.
122. The screen printing method of claim 119, wherein the controlling step provides for closed-loop feedback control of one or more operating parameters of the one or more screen printing machines.
123. The screen printing method of claim 122, wherein, on identification of a rectifiable trend in the trend identification step, the controlling step provides for automatic triggering of the closed-loop feedback control.
124. The screen printing method of any of claims 119 to 123, wherein the trend identification is at a machine component level, such as an artefact specific to a particular printing screen, support tooling, print medium and cleaning material.
125. The screen printing method of any of claims 119 to 123, wherein the trend identification is at a general, machine level, such as an artefact of particular kinds of printing screen, support tooling, print media and cleaning materials.
126. The screen printing method of any of claims 119 to 123, wherein the trend identification is both at a component level, such as an artefact specific to a particular printing screen, support tooling, print medium and cleaning material, and at a general, machine level, such as an artefact of particular kinds of printing screen, support tooling, print media and cleaning materials.
127. The screen printing method of any of claims 123 to 126, wherein the inspection operation is performed in parallel with the printing operation.
128. The screen printing method of claim 127, wherein the inspection operation is performed within a print cycle, thereby enabling process and workpiece verification for all printed workpieces at a line beat rate of each screen printing machine.
129. The screen printing method of claim 128, wherein the printing cycle is less than 7 seconds.
130. The screen printing method of claim 129, wherein the printing cycle is less than 5 seconds.
131. The screen printing method of claim 128, wherein the printing cycle is between 5 and 7 seconds.
132. The screen printing method of any of claims 119 to 126, wherein the inspection operation is performed subsequently to the printing operation.
133. The screen printing method of any of claims 119 to 132, wherein the printing station and the inspection station of each screen printing machine are integrated, and each screen printing machine further comprises a single user interface.
134. The screen printing method of any of claims 119 to 133, further comprising the step of:
storing inspection results for printed workpieces at the screen printing machines and/or the processing station.
135. The screen printing method of claim 134, wherein the stored inspection results comprise workpiece-level . results, enabling traceability of individual printed workpieces.
136. The screen printing method of claim 135, wherein the stored inspection results comprise pad-level results, enabling traceability of individual printed pads on individual workpieces.
137. The screen printing method of any of claims 119 to 136, further comprising the step of:
storing printed workpiece images for the respective workpieces at the screen printing machines and/or the processing station.
138. The screen printing method of any of claims 119 to 137, wherein the printing station comprises a workpiece support on which a workpiece is supported in the printing operation, a printing screen which includes a pattern of printing apertures and through which print medium is printed onto a supported workpiece, and a print module which is operated to print deposits of print medium through the pattern of apertures in the printing screen onto an upper surface of the workpiece.
139. The screen printing method of claim 138, wherein the printing station comprises an imaging module for imaging fiducials on an upper surface of the workpiece and a lower surface of the printing screen, and an alignment mechanism for aligning the printing screen relative to the workpiece based on the imaged locations of the fiducials on the workpiece and the printing screen.
140. The screen printing method of claim 139, wherein the imaging module comprises an imaging camera and a drive, which is operated to drive the imaging camera between the supported workpiece and the printing screen, and acquire images of fiducials on the upper surface of the supported workpiece and the lower surface of the printing screen.
141. The screen printing method of claim 139 or 140, wherein the workpiece support is operated to support a workpiece at a first, imaging position to allow for imaging by the imaging module and a second, printing position to allow for printing by the print module.
142. The screen printing method of any of claims 139 to 141, wherein the alignment mechanism comprises a drive for moving the printing screen based on imaged locations of the fiducials on the workpiece and the printing screen, such as to align the printing screen relative to the supported workpiece.
143. The screen printing method of any of claims 138 to 142, wherein the print module comprises a printing element, and a drive which is operated to drive the printing element over the printing screen and print deposits of print medium through the pattern of apertures in the printing screen onto a workpiece supported therebelow by the workpiece support.
144. The screen printing method of any of claims 119 to 143, wherein the inspection station comprises a camera module for acquiring and processing images of printed workpieces.
145. The screen printing method of claim 144, wherein the camera module comprises an imaging camera which provides for a full-width workpiece inspection, and beneath which the workpieces are transported to perform a full-area workpiece inspection of workpieces.
146. The screen printing method of claim 145, wherein a full-area workpiece inspection comprises an inspection of at least 50 % of the workpiece area, preferably at least 75 % of the workpiece area, more preferably at least 90 % of the workpiece area, and still more preferably the entire workpiece area.
147. The screen printing method of claim 145 or 146, wherein the imaging camera can perform a full-area workpiece inspection at workpiece transport speeds of up to 150 mm/s.
148. A screen printing method, comprising the steps of:
providing a screen printing machine comprising a printing station and an inspection station;
printing workpieces at the printing station;
inspecting printed workpieces at the inspection station; and
storing inspection results for printed workpieces.
149. The screen printing method of claim 148, wherein the inspection operation is performed in parallel with the printing operation.
150. The screen printing method of claim 149, wherein the inspection operation is performed within a print cycle, thereby enabling process and workpiece verification for all printed workpieces at a line beat rate of the screen printing machine.
151. The screen printing method of claim 150, wherein the printing cycle is less than 7 seconds.
152. The screen printing method of claim 151, wherein the printing cycle is less than 5 seconds.
153. The screen printing method of claim 150, wherein the printing cycle is between 5 and 7 seconds.
154. The screen printing method of claim 148, wherein the inspection operation is performed subsequently to the printing operation.
155. The screen printing method of any of claims 148 to 154, wherein the printing station and the inspection station are integrated, and the screen printing machine further comprises a single user interface.
156. The screen printing method of any of claims 148 to 155, wherein the stored inspection results comprise workpiece-level results, enabling traceability of individual printed workpieces.
157. The screen printing method of claim 156, wherein the stored inspection results comprise pad-level results, enabling traceability of individual printed pads on individual workpieces.
158. The screen printing method of any of claims 148 to 157, wherein the inspection results for printed workpieces are stored at the screen printing machine and/or a remote processing station.
159. The screen printing method of any of claims 148 to 158, further comprising the step of:
storing printed workpiece images for the respective workpieces.
160. The screen printing method of claim 159, wherein the printed workpiece images for the respective workpieces are stored at the screen printing machine and/or a remote processing station.
161. A screen printing method, comprising the steps of:
providing a plurality of screen printing machines, each comprising a printing station and an inspection station ;
printing workpieces at the printing stations of the screen printing machines;
inspecting printed workpieces at the inspection stations of the screen printing machines;
providing a remote processing station which is in communication with the plurality of screen printing machines; communicating inspection results associated with inspected workpieces as printed by the screen printing machines to the processing station; and
storing inspection results for printed workpieces at the processing station.
162. The screen printing method of claim 161, wherein the inspection operation is performed in parallel with the printing operation.
163. The screen printing method of claim 162, wherein the inspection operation is performed within a print cycle, thereby enabling process and workpiece verification for all printed workpieces at a line beat rate of the screen printing machine.
164. The screen printing method of claim 163, wherein the printing cycle is less than 7 seconds.
165. The screen printing method of claim 164, wherein the printing cycle is less than 5 seconds.
166. The screen printing method of claim 163, wherein the printing cycle is between 5 and 7 seconds.
167. The screen printing method of claim 161, wherein the inspection operation is performed subsequently to the printing operation.
168. The screen printing method of any of claims 161 to 167, wherein the printing station and the inspection station of each screen printing machine are integrated, and each screen printing machine further comprises a single user interface.
169. The screen printing method of any of claims 161 to 168, wherein the stored inspection results comprise workpiece-level results, enabling traceability of individual printed workpieces.
170. The screen printing method of claim 169, wherein the stored inspection results comprise pad-level results, enabling traceability of individual printed pads on individual workpieces.
171. The screen printing method of any of claims 161 to 170, further comprising the step of:
storing printed workpiece images for the respective workpieces at the processing station.
172. A screen printing method in which one or more machine parameters of a screen printing machine are controlled in real time based on results obtained from an inspection performed downstream of a printing zone of the screen printing machine, preferably by closed- loop feedback control.
173. A screen printing method in which one or more machine parameters of a screen printing machine are controlled in real time based on results obtained from inspections performed in one or more other screen printing machines, preferably by closed-loop feedback control.
174. A screen printing machine substantially as hereinbefore described with reference to the accompanying drawings.
175. A machine control system substantially as hereinbefore described with reference to the accompanying drawings.
176. A screen printing method substantially as hereinbefore described with reference to the accompanying drawings.
PCT/GB2011/000535 2010-04-06 2011-04-06 Screen printing machine and method Ceased WO2012164233A2 (en)

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EP3184302A4 (en) * 2014-08-18 2017-09-20 Koh Young Technology Inc. Solder inspection apparatus and feedback information generation method for solder inspection apparatus
US10747198B2 (en) 2014-08-18 2020-08-18 Koh Young Technology Inc. Solder inspection apparatus and method of generating feedback information of solder inspection apparatus
EP3566872A4 (en) * 2017-01-06 2020-01-08 Fuji Corporation SERIGRAPH PRINTER
EP3501829A1 (en) * 2017-12-21 2019-06-26 Koh Young Technology Inc. Printed circuit board inspecting apparatus, method for determining fault type of screen printer and computer readable recording medium
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EP3851276A1 (en) * 2020-01-14 2021-07-21 Lambotec GmbH Computer-implemented method for controlling a screen printing machine and computer-controlled screen printing machine
CN116141829A (en) * 2022-12-30 2023-05-23 苏州江天电子材料有限公司 A screen printing intelligent process method and system
CN116141829B (en) * 2022-12-30 2024-02-13 苏州江天电子材料有限公司 An intelligent screen printing process method and system

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GB201005750D0 (en) 2010-05-19
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