# US 8,783,174 B2 · Screen printing method > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 8,783,174 B2 - Document ID: US8783174B2 - Status: Granted - Kind: B2 - Application number: 12/702,695 - Filed: 2010-02-09 - Published: 2010-09-16 - Granted: 2014-07-22 - Earliest claimed: 2009-02-10 - Assignees: Shin-Etsu Chemical Co., Ltd. - Applicants: Ryo Mitta; Hiroyuki Otsuka; Ikuo Sakai; Kenji Abe; Naoki Ishikawa - Inventors: Ryo Mitta; Hiroyuki Otsuka; Ikuo Sakai; Kenji Abe; Naoki Ishikawa - Web page: https://patentgrep.com/patent/US8783174B2 ## CPC - B41F 33/0081: {Devices for scanning register marks} - B41F 15/0881: {for printing on polyhedral articles} - B41F 15/26: for articles with flat surfaces - B41M 1/12: Stencil printing; Silk-screen printing - H05K 3/1216: {by screen printing or stencil printing} - H10F 71/00: Manufacture or treatment of devices covered by this subclass (patterning processes to connect thin photovoltaic cells in integrated devices, or assemblies of multiple devices, having photovoltaic cells H10F19/33; manufacture or treatment of encapsulations or containers for integrated devices, or assemblies of multiple devices, having photovoltaic cells H10F19/80; manufacture or treatment of integrated devices, or assemblies of multiple devices, comprising at least one element in which radiation controls the flow of current H10F39/00) - H10F 77/211: {for photovoltaic cells} - B41M 1/26: Printing on other surfaces than ordinary paper (B41M1/40 takes precedence) - B41M 3/00: Printing processes to produce particular kinds of printed work, e.g. patterns ({printing apparatus or machines of special type or for particular purposes B41F17/00;} special designs or pictures per se B44F; manufacturing printed circuits using printing techniques H05K3/12 {; manufacturing organic semiconductor devices using printing techniques H10K71/13}) - B41P 2233/52: for registering - H05K 1/0269: {for visual or optical inspection} - H05K 3/0008: {for aligning or positioning of tools relative to the circuit board (H05K3/4638, H05K3/4679 take precedence; for manufacturing assemblages of components H05K13/0015)} - H05K 2201/09918: Optically detected marks used for aligning tool relative to the PCB, e.g. for mounting of components - H05K 2203/1476: Same or similar kind of process performed in phases, e.g. coarse patterning followed by fine patterning - Y02E 10/50: Photovoltaic [PV] energy - B41F: PRINTING MACHINES OR PRESSES (manifolding devices or office printing machines B41L) - B41M: PRINTING, DUPLICATING, MARKING, OR COPYING PROCESSES; COLOUR PRINTING, (correction of typographical errors B41J; processes for applying transfer pictures or the like B44C1/16; fluid media for correction of typographical errors by coating C09D10/00; printing textiles D06P) - H05K: PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS - H10F: INORGANIC SEMICONDUCTOR DEVICES SENSITIVE TO INFRARED RADIATION, LIGHT, ELECTROMAGNETIC RADIATION OF SHORTER WAVELENGTH OR CORPUSCULAR RADIATION - B41P: INDEXING SCHEME RELATING TO PRINTING, LINING MACHINES, TYPEWRITERS, AND TO STAMPS - Y02E: REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION ## Abstract The method for screen printing improves accuracy during a plurality of screen printing steps. After a first layer and an alignment mark are printed on a workpiece, the alignment mark is imaged by a camera so that the alignment mark is stored as image data in an image processing device adapted to deliver reference data for subsequent printing, and the image data is used to renew the reference data in the image processing device. ## Claims ### Claim 1 A screen printing method which applies a plurality of screen printing steps to a workpiece to form plural layers thereon, comprising: printing a first layer and at least one alignment mark on a workpiece in a first screen printing step; imaging the at least one alignment mark printed on the workpiece using a camera; using an imaging processing device to compare the at least one printed alignment mark with stored alignment mark reference data to register the workpiece position for subsequent printing steps; storing the at least one alignment mark as alignment mark image data in the image processing device; renewing the stored alignment mark reference data in the image processing device by overwriting the stored alignment mark reference data with the alignment mark image data after a predetermined number of printing steps; and delivering the renewed alignment mark reference data for use in subsequent printing steps so as to improve accuracy of the printing during the plurality of screen printing steps. ### Claim 2 (depends on 1) The screen printing method of claim 1 wherein the alignment mark is of such shape that a ratio of a total length of sides of a smallest rectangle that circumscribes the outermost periphery of the alignment mark to a total length of outer sides of the alignment mark is from 1:0.1 to 1:50. ### Claim 3 (depends on 1) The screen printing method of claim 1 wherein the alignment mark is T-shaped. ### Claim 4 (depends on 1) The screen printing method of claim 1 further comprising; printing at least two alignment marks on the workpiece; and using the at least two alignment marks for image processing. ### Claim 5 (depends on 1) The screen printing method of claim 1 further comprising renewing the reference data with the alignment mark image data every 1 to 5,000 printing steps. ### Claim 6 (depends on 1) The screen printing method of claim 1 wherein the first layer constitutes an electrode of a solar cell. ### Claim 7 (depends on 6) The screen printing method of claim 6 wherein the workpiece is a wafer of a solar cell on which an electrode pattern is printed as the first layer, and further comprising: printing at least one more layer of electrode pattern to form an electrode of multilayer structure while the alignment mark printed at the same time as the first layer is used as a registration reference on the side of the workpiece, and using an alignment mark at the same time as the first layer or any alignment mark printed within 5,000 printing steps at maximum as a registration reference on the side of the image processing device. ### Claim 8 (depends on 6) The screen printing method of claim 6 wherein the solar cell has a first layer of a finger electrode pattern, and further comprising forming the alignment mark by utilizing a part of the first layer of the finger electrode pattern. ### Claim 9 (depends on 1) The screen printing method of claim 1 further comprising utilizing a part of printed pattern as the alignment mark so that no partition is defined between the alignment mark and the printed pattern, and feeding all the region viewed by the camera to the image processing device as the alignment mark image data.