KR101641392B1 - Method and system for nozzle compensation in non-contact material deposition - Google Patents

Abstract

A method of printing is provided where printing is using a first printing unit (220) having redundant nozzles (221, 222, 223). Then, the method may include stopping the printing with the first printing unit while continuing the printing with active nozzles of a second printing unit (210, 230). The method may include inspecting the first printing unit and identifying faulty nozzles, then designating the faulty nozzles (225) as inactive and designating inactive nozzles (221, 222, 223) of the first printing unit as a new active nozzle. According to some embodiments the method may include moving the first printing unit to an inspection zone prior to inspecting while continuing the printing with active nozzles of a second printing unit and moving the first printing unit back to the printing zone after inspection and continuing the printing with the first printing unit.

Description

[0001] METHOD AND SYSTEM FOR NOZZLE COMPENSATION IN NON-CONTACT MATERIAL DEPOSITION [0002]

Non-contact material deposition printing is an attractive method for patterning and depositing materials in the printed electronics and solar cell industries.

For example, forming conductive wirings by directly depositing a conductive material on the back surface or the front surface of a solar cell to provide a conduction path of charge generated in the battery can improve not only the efficiency of the solar cell but also the productivity of mass production.

Deposition printing techniques such as inkjet printing or aerosol printing involve moving the printhead and substrate relative to each other along the printing direction to deposit droplets of printing material from the nozzles. One of the problems associated with deposition printing is in the defective nozzle where the injection is stopped or weakly sprayed. Thus, the defective nozzle can cause uneven conductive wiring, which can lead to inefficient or inoperable solar cells.

What is believed to be the present invention is pointed out and particularly pointed out in the concluding portion of the specification. BRIEF DESCRIPTION OF THE DRAWINGS The invention will be best understood by reference to the following detailed description when read in conjunction with the accompanying drawings, in which:
1 shows an exemplary printing system according to an embodiment of the present invention.
Fig. 2 shows a printing unit, which includes extra nozzles and is arranged in parallel to the printing direction, useful in explaining embodiments of the present invention.
3 is a flow chart illustrating a method for printing in accordance with some embodiments of the present invention.
It will be appreciated that for simplicity and clarity of illustration, components shown in the figures are not necessarily drawn to scale. For example, the dimensions of some components may be exaggerated relative to other components for clarity. Also, wherever considered appropriate to refer to corresponding or analogous elements, reference numerals may be repeated between figures.

In the following detailed description, numerous specific details are set forth in order to provide a thorough understanding of the present invention. However, it will be understood by those skilled in the art that the present invention may be practiced without these specific details. In other instances, well-known methods, procedures, components, modules, units and / or circuits have not been described in detail so as not to obscure the present invention.

Embodiments of the present invention can be applied to various printing systems and methods. For clarity and simplicity, embodiments and references of non-contact material deposition systems will be applied to the manufacture of conductive metal lines for solar cells primarily using ink jet systems. However, the scope of the present invention is not limited by these embodiments, but may be applied to other deposition systems, such as aerosol spray deposition systems or dispensers, and may be applied in different ways such as in graphics, publications, mass media, packaging, .

Embodiments of the present invention are directed to systems and methods for inspecting print nozzles and replacing activated print nozzles as needed during the course of a printing or printing operation. According to an embodiment, the system may include an extra printhead or print unit such that the number of printheads is greater than the number of printheads required to perform a desired desired print job. A portion of the head may be activated at a given time during printing, while the remaining printheads may be extra heads.

Thus, during the course of the printing process, a first subset selected from a plurality of printheads installed in the system may be designated to deposit material on the substrate, and another second subset of the printheads may be subjected to a repair procedure Receive or pass through. For example, while the first printhead is activated to deposit the material on the substrate, the second printhead may be relocated to the inspection, inspection, or maintenance area in the print area or area. While the second printhead is being inspected, inspected, repaired, or otherwise maintained, the first printhead may continue to print and / or deposit the material.

In some embodiments, the method includes printing the wiring on the substrate, for example, depositing material from a printing unit comprising nozzles arranged in one or more rows to print the contact wiring on the semiconductor wafer. According to an embodiment, the printing unit may include extra nozzles. The number of nozzles in the printing unit may be greater than the number of nozzles required to accomplish the desired printing operation, e.g., printing the wiring at the desired resolution. At a given time during printing, a portion of the nozzles in the print unit may be activated, while the remaining nozzles may be left over or deactivated. Printing is performed only by nozzles designated as active nozzles while extra nozzles are designated as inactive nozzles. In a particular row, the material may be selectively deposited.

The method may further comprise moving the printing unit to the inspection zone while continuing printing by the active nozzles of another printing unit capable of performing the operations of the previous printing unit. The nozzles are inspected in the inspection zone, and one of the active nozzles can be identified as a defective nozzle. According to some embodiments, the inspection can be performed in the printing zone without moving the printing unit to the inspection zone.

The identified defective nozzle may then be designated as inactive, and one of the nozzles previously designated as an inactive nozzle may become the active nozzle to replace the defective nozzle. The method may further comprise moving the print unit back from the inspection zone to the printing zone and continuing printing by the unit so that the new active nozzle replaces the defective nozzle.

According to an embodiment of the present invention, after all the nozzles are inspected in the inspection zone or printing zone, the system can analyze the inspection data and select the optimum nozzle set as the active nozzle based on predetermined considerations. Then, the selected nozzles will be designated or specified as active nozzles, while the remaining nozzles of the print unit will be designated as inactive. The step of determining the optimal nozzle set may be based on the choice of nozzles that are substantially similar in size to the required droplet size, stability of injection, and / or deviations in the direction of nozzle injection from the normal to the nozzle plate (orifice plate). Other factors may be considered to select the optimal nozzle set without departing from the scope of the present invention.

Reference is made to Fig. 1 which shows a high-level block diagram of an exemplary printing system according to an embodiment of the present invention. An exemplary system labeled as system 100 is capable of performing continuous high-speed, high-volume printing operations without frequent shutdown for maintenance or inspection. It is noted that the system 100 may be applied to a variety of printing systems, such as ink jet or aerosol deposition systems. The system 100 may include a print unit or printheads 105A-105F and may include a printhead such as a platform (not shown) or a conveyor A zone 110 and a check zone 125 where maintenance and inspection of the nozzles of the print unit and print unit can take place.

The inspection zone 125 may include one or more maintenance stations for performing various maintenance operations on the print unit. Although only six exemplary printing units are shown, a suitable number of printing units can be used without departing from the scope of the present invention. The number of printing units is determined to be an extra of one or more printing units. The redundancy allows the active nozzles to be inspected simultaneously when the active nozzle continues the printing process. Thus, one or more of the units 105A-105F allows the other printing unit to remain independently movable between the printing zone 110 and the inspection zone 125 while remaining in the printing zone and continuing with the printing process. The inspection area 125 may be adjacent or close to the printing area 110. According to some embodiments of the present invention, the printing units 105A-105F may be mounted on the rails such that they can be moved from the printing area 110 to the inspection area 125. [ Other transport units or mechanisms may be used without departing from the scope of the present invention.

Each print unit 105A-105F may include a nozzle 106 arranged in one or more rows. In the exemplary illustration of Figure 1, each row has eight nozzles arranged in parallel to the scanning direction or printing direction X. [ However, those skilled in the art will appreciate that each row may contain dozens or hundreds of nozzles. Each row may include extra nozzles to replace defective nozzles upon detection. For example, a defective nozzle can be a nozzle that is jetted in a direction that is largely deviated from the jetting direction of a nozzle or a majority of nozzles that are jammed or partially clogged with jets that can only partially eject from a desired amount of material, .

The print units 105A-105C can be positioned adjacent to the print zone 110 so that the heat is parallel to the print direction X. [ If the substrate is moved by the conveyor, the printing direction can be indicated by the advancing direction of the substrate. In this configuration, each column can print one metal wiring in a direction parallel to the printing direction in one scan. According to another embodiment of the present invention, another configuration or arrangement of the printing unit with respect to the printing direction is possible.

The system 100 may also include a controller 115 for controlling the printing process and an image acquisition unit 120 coupled to the controller 115. In accordance with an embodiment of the present invention, the controller 115 may perform tasks or functions such as, but not limited to, adjusting, configuring, scheduling, arbitrating, supervising, operating and / Or may be accompanied by the operation of the < / RTI > For example, the controller 115 may control the movement of the printed object and the printing units 105A-105F in the printing zone 110. [ The controller 115 may include any required or appropriate hardware, software, firmware, or a combination thereof. For example, the controller 115 may be a computing device that includes a controller and / or a central processing unit (CPU), a memory and an input unit and an output unit.

The image acquisition unit 120 may include an imaging device or sensor 121, such as a camera or a charge coupled device (CCD), for example, to obtain an image of a droplet of material exiting the nozzle to inspect the condition or condition of the nozzle . Other suitable visual sensors or other methods of identifying the state of the nozzle may be used. The image acquisition unit 120 may also include an image processing unit 122 for analyzing the image and determining the current state of the inspected nozzle and a storage device 123 for storing data relating to the state of the nozzle .

In accordance with an embodiment of the present invention, the detector 121 may be coupled to a dedicated computer device and storage device for storing and processing the acquired image, or alternatively, the controller 115 may perform these operations have. According to embodiments of the present invention, a pulsed light source, such as a pulsed laser source or a pulsed light emitting diode (LED), may be coupled to the sensor 121 to produce an image of a droplet deposited from the nozzle. In addition, the controller 115 can control and manage inspection procedures, such as the dispensing of liquid droplets, the procedures for adjusting the operation of the optical pulses and the camera.

Reference is now made to Fig. 2, which illustrates an arrangement of printing units that include extra nozzles and are positioned parallel to the printing direction to illustrate embodiments of the present invention. The printing units 210, 220 and 230 can be used for printing conductive wirings on semiconductor wafers in the production of solar cells. According to an embodiment of the present invention, during printing, the first subset of nozzles may be designated as active nozzles, e.g., nozzles 224-228 may be designated as active. A second subset of the nozzles in the print unit 220, such as nozzles 221-223, may be designated as inactive. If a nozzle, e.g., nozzle 225, is identified as defective, the defective nozzle may be replaced by any of the inactive nozzles 221-223. For example, the nozzle 225 may be re-designated as inactive, and the nozzle 222 may be re-designated as active.

According to an embodiment of the present invention, during the course of the printing process, and during the deposition of one or more printing units forming the first subset of printing units, the other one or more The printing unit may be moved to the inspection area 125 for maintenance and / or inspection. In addition, if desired, the state of one or more of the pair of nozzles may be interchanged so that the previous active nozzle becomes inactive and the previous inactive nozzle becomes active.

The print units relocated to the check area 125 can be inspected, checked and placed. For example, a nozzle can be inspected by acquiring an image of a droplet that is ejected or ejected by the nozzle of the inspected unit. Then, the image can be analyzed by the image processing unit 122. [ Based on this analysis, the defective nozzle can be identified and replaced by an extra nozzle. In addition, various work factors can be modified or changed. For example, based on inspection of the nozzle, operating factors such as pressure, temperature or voltage can be modified.

Referring again to Figure 1, the image processing unit 122 may receive the image from the detector 121 and may process such an image by applying suitable image processing techniques. For example, an analysis of the shape, the locus and the velocity of the droplet jetted by the image processing unit can be performed. For example, the image processing can be used to determine the state of the nozzle based on the image of the droplet ejected from the nozzle. As another example, two or more images that can be obtained for a predetermined time can be compared. By comparing or otherwise correlating images, various states, defects, or other aspects of the nozzle can be determined. For example, degradation of nozzle performance can be detected through comparison of continuous or continuous images.

While the video camera provides images for visible light, other images may be generated. For example, the sensor 121 may be an infrared camera that records the temperature to provide a temperature distribution of the ejected ink or aerosol. Unlike the description herein, the imaging device or sensor 121 can be placed in a check area, and other configurations are possible. For example, one or more cameras may be disposed adjacent to or in the vicinity of, or around, the printing area, for example, Such a camera can obtain an image during a printing procedure in which the nozzle deposits material on a test substrate.

The storage system or unit 123 accepts and stores an image obtained by the detector 121, for example a removable storage medium such as a compact disk (CD) or memory chip, or an image obtained from another source such as a remote server . For example, a well-discharged reference image may be loaded or stored in the storage device and used to compare with or correlate with the image acquired by the sensor 121. [ The reference image may ideally or preferably include an ejected or deposited image and may thus be used, for example, to determine whether an image ejected in the second image is appropriate by comparing the reference image with the second image, Or other functional parameters associated with the nozzles into which the droplets of the image are ejected.

Those skilled in the art will appreciate that a redundant portion of the print unit or printhead can dynamically select a printhead that participates in the print process. Thus, extra printheads, spare printheads, unused printheads or un-actuated printheads may be present and / or available during the printing process. Such extra printheads may enable dynamic replacement of the printhead while the printing process is in progress, active or continuing. For example, if the first printhead is activated and is actively involved in the printing process by, for example, depositing material on the medium, and if a check or inspection of the first printhead is required, or is selected to be checked or inspected, , The non-active print head, the un-activated print head, or the extra print head may be activated to replace the first print head. Thus, the replaced first printhead can now be deactivated and can be inspected, checked or otherwise subjected to further repair procedures.

According to the embodiment of the present invention, the printing unit or the print head may be provided with an extra nozzle. For example, a printhead requiring 100 nozzles to perform a predetermined task may have 500 nozzles. Thus, a subset of the nozzles mounted, included, or installed in the printhead can be activated to participate in the printing process and can, for example, actually dispense the material onto the substrate or media. According to an embodiment of the present invention, the redundancy of the nozzles described herein dynamically enables active selection or designation of a subset of the nozzles. In addition, such a redundancy of the nozzles may enable the active nozzle to be replaced by an inert nozzle. For example, if the first nozzle in the printhead is determined to require replacement or inspection, e.g., by failure, or as part of a scheduled or periodic routine repair, a second nozzle, an inactive nozzle, or an extra nozzle is selected, And can replace the first nozzle by ejecting the material onto the substrate or medium.

Reference is made to Fig. 3 which shows a flow chart illustrating a method for printing according to some embodiments of the present invention. As shown in block 310, the method includes initiating a printing process using a first printing unit or printhead. For example, the information in the print file may be provided to a printing system such as the system 100 described in FIG. In accordance with the provision of this information, the controller 115 can cause the conveyor to position the wafer so that a subset of nozzles designated as active nozzles in both print units 220 and 230 can deposit conductive material on the wafer . Based on the information in this print file, the controller 115 can control the nozzles and the print unit so that the material is deposited according to the manual or parameters in the print file.

As shown in block 320, the method may include moving one or more print units, e.g., print unit 220, to the inspection area. During the time that the print unit is inspected and / or checked in the check area, another print unit, such as the print unit 210 that was previously redundant, is activated and the print process may continue by the print units 210, 230. As shown in block 330, the method may include inspecting the nozzles of the print unit 200 and identifying one or more nozzles, e.g., nozzles 225, as defective or defective nozzles.

The method may include determining whether the defect can be repaired. For example, if a complete failure of the orifice of the nozzle is detected, a fault may be removed from the orifice to repair the defect. Other detected faults may require complicated and manual procedures for repair. The step of classifying defects as being during the printing process or as being immediately processable or repairable may depend on various parameters and / or configurations. If the defect is repaired, the process flow may include checking the nozzle. For example, the operating parameters may be modified or an automatic control procedure may be performed.

As shown in block 335, the method may include selecting an optimal nozzle set as an optimal nozzle based on the inspection. Thus, the method may include designating the defective nozzle as inactive when repair is undesirable or undesirable. The nozzles identified as inactive may not participate in the printing process until the state of the nozzles is changed to "active ". As shown in block 340, the method may include designating the selected set of nozzles as active, and designating the remaining nozzles and defective nozzles of the print unit as inactive. For example, the method may include designating a nozzle that was previously designated as an inactive nozzle in the same column of a new defective nozzle as active. For example, after determining the nozzle 225 to be defective, an extra nozzle, such as the nozzle 223 that was previously inactive and not participating in the printing process, may be designated as an active nozzle replacing the defective nozzle 225.

In contrast to the description herein, the first nozzle, the defective nozzle may be designated as inactive to compensate for the defective nozzle, the second nozzle, the inactive nozzle may be designated as the active nozzle, and other scenarios are possible. For example, the same print unit and nozzles in the same row as possible can be replaced based on a predetermined schedule. For example, in order to avoid the ink in the nozzle from drying out, the nozzle may be designated as active or inactive periodically. In some embodiments, the first nozzle is replaced with the second nozzle, but other combinations are possible. For example, the defective nozzle may be replaced by two extra nozzles. For example, these two nozzles may be indicated such that the combined operation of the two nozzles is identical to the predetermined operation of the defective nozzle, i.e., the replaced nozzle.

As shown in block 345, the method may include moving the first print unit back to the print zone after the inspection is complete. As another printhead prints at this time, for example, the print unit 220 can replace the print unit 210 in performing an ongoing print process, and the print unit 210 can be used as a check area for inspection Can be moved. Alternatively, for example, in performing an ongoing printing process, the printing unit 220 may replace the printing unit 230, and the printing unit 230 may be moved to the inspection area for inspection. Thus, as shown in block 350, the method may include stopping printing by the printing unit in operation and continuing the printing process using the first printing unit. The first print unit may be, for example, a unit 220 that replaces a new active nozzle, that is, a nozzle 225 that has previously been used and is now defective.

Embodiments of the present invention may be practiced with the use of a computer-readable storage medium having stored thereon instructions for performing the methods described herein when executed by a processor or controller, such as a memory, disk drive, or USB flash memory for encoding, ), Or a product such as a computer or processor storage medium.

Although the embodiment of the present invention is not limited in this regard, the term "plurality" as used herein may include, for example, "plurality" Throughout the specification, the word "plural" may be used to describe two or more elements, devices, components, units, elements, or other similar matter.

Although not explicitly described, the method embodiments described herein are not limited to any particular order or order. In addition, the described method embodiments or portions of these elements may occur or be performed at the same time point in time, or at a time point in time. As is known in the art, the execution of executable code portions such as functions, tasks, sub-tasks, or programs can be referred to in the execution of a function, program, or other element.

Although the embodiments of the present invention are not limited in this regard, the terms used in the discussion, such as "processing "," computing ", &Quot; or other similar terminology may be used to manipulate and / or manipulate data represented by physical (e.g., electronic) amounts in computer registers and / or memory into other data represented in computer registers and / Or other information storage medium storing instructions for performing operations and / or processing, or operation and / or processing of a computer, computing platform, computing system, or other electronic computing device, have.

While certain features of the invention have been illustrated and described herein, many modifications, substitutions, changes, and equivalents may occur to those skilled in the art. It is therefore to be understood that the following claims, including all such modifications and variations, are included in the true spirit of the invention.

Claims (13)

Printing a metal wiring using a first printing unit having nozzles, wherein a first portion of the nozzle is designated as an active nozzle and a second portion of the nozzle is designated as an inactive nozzle, Performing selective deposition of a metal material from the active nozzle of the unit,
Stopping printing using the first printing unit;
Inspecting the nozzles of the first printing unit,
Selecting a new active nozzle set based on the inspection results,
And continuing to print using the first printing unit with the new active nozzle set. 2. The method of claim 1, further comprising: moving the first printing unit to an inspection zone prior to inspecting the nozzles of the first printing unit; and continuing printing using the first printing unit with the new active nozzle set And returning the first printing unit to the printing zone. The printing method according to claim 1, further comprising the step of stopping printing using the first printing unit while continuing printing using an active nozzle of the second printing unit. 2. The method of claim 1, further comprising: inspecting at least a portion of the nozzle
And selecting a new active nozzle set based on the inspection result. 2. The method of claim 1, further comprising: identifying one of the active nozzles as a defective nozzle; and
Designating the defective nozzle as inactive and designating one of the inactive nozzles as a new active nozzle to replace the defective nozzle with the new active nozzle. 2. The method of claim 1, further comprising: obtaining an image of ejection of droplets from the active nozzle;
And identifying a defective nozzle based on an analysis of the image. 7. The printing method according to claim 6, wherein the analysis of the image comprises determining the size of the droplet and the deviation of the direction of injection from a predetermined direction. 7. The printing method according to claim 6, wherein the analysis of the image comprises determining the size of the droplet ejected from the nozzle. 7. The printing method according to claim 6, wherein the analysis of the image includes a step of determining a deviation in the direction of injection from a predetermined direction. 7. The method of claim 6, wherein the analysis of the image comprises determining the degree of spray stability of the metallic material from the nozzle. 2. The method of claim 1, wherein depositing comprises depositing an electrically conductive material on the substrate to produce a metallized conductive wiring. The printing method according to claim 1, wherein the deposition includes depositing an electrically conductive material on an object to produce a printed electronic device. 5. The printing method according to claim 4, wherein the step of selecting the new set is based on a test result including at least one of droplet size, injection stability of a metal material, and deviation of an injection direction of a metal material.

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