Abstract:
A method for printing conductive lines on a substrate includes printing a pattern of conductive material ( 204 ) on the substrate to; and sintering a first part of the pattern of conductive material.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    Reference is made to commonly-assigned copending U.S. patent application Ser. No. ______ (Attorney Docket No. K000148US01/NAB), filed herewith, entitled PRINTING CONDUCTIVE LINES, by Schuster; the disclosure of which is incorporated herein. 
     
    
     FIELD OF THE INVENTION 
       [0002]    The present invention relates to writing conductive lines and conductive grids on media, and in particular to writing with an inkjet and laser combination. 
       BACKGROUND OF THE INVENTION 
       [0003]    One of the ultimate goals in electronics is the ability to directly write electronic components and circuits on a variety of substrates. Advancing materials chemistry and developing printhead technology is bringing this goal closer to reality. 
         [0004]    Drop on demand inkjet printing applied to industrial processes, utilizes the piezo electric effect to deliver precise and consistent quantities of fluids to media or substrate. Such inkjet printing has a relatively low resolution, which might not be enough to print the fine details in circuit boards  100  as shown in  FIG. 1 . 
         [0005]    Current methods for printing electronics on suitable substrates, for example applying material deposition, results in relatively thick lines, i.e. greater than 30 micrometers. Other methods, such as subtractive methods, which may be based upon laser writing and etching, may consume large amounts of expensive conductive material.  FIG. 2  shows conductive grid lines  204  deposited by known printing methods such as inkjet deposition of conductive material on substrate  208 . 
         [0006]    The deposition of the conductive grid lines may also be done by flexographical means. The width of the grid lines formed depends on the printing method, but in general are not narrow enough to be used for high density circuit boards. 
       SUMMARY OF THE INVENTION 
       [0007]    Briefly, according to one aspect of the present invention a method for printing conductive lines on a substrate includes printing a pattern of conductive material on the substrate to; and sintering a first part of the pattern of conductive material. 
         [0008]    These and other objects, features, and advantages of the present invention will become apparent to those skilled in the art upon a reading of the following detailed description when taken in conjunction with the drawings wherein there is shown and described an illustrative embodiment of the invention. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0009]      FIG. 1  shows a prior art diagrammatic form of a printed circuit board; 
           [0010]      FIG. 2  represents in diagrammatic form a prior art imaging device adapted to form conductive lines using inkjet head and laser imaging head; 
           [0011]      FIG. 3  represents in diagrammatic form an imaging head for forming conductive lines; 
           [0012]      FIG. 4  represents in diagrammatic form conductive lines formed with inkjet means; 
           [0013]      FIG. 5  represents in diagrammatic form sintered conductive lines previously imaged by inkjet means; and 
           [0014]      FIG. 6  represents in diagrammatic form of sintered conductive lines after removing the non sintered inkjet material. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0015]    In the following detailed description, numerous specific details are set forth in order to provide a thorough understanding of the disclosure. However, it will be understood by those skilled in the art that the teachings of the present disclosure may be practiced without these specific details. In other instances, well-known methods, procedures, components and circuits have not been described in detail so as not to obscure the teachings of the present disclosure. 
         [0016]    While the present invention is described in connection with one of the embodiments, it will be understood that it is not intended to limit the invention to this embodiment. On the contrary, it is intended to cover all alternatives, modifications and equivalents as covered by the appended claims. 
         [0017]      FIG. 3  shows an arrangement of an imaging device  300  configured to image conductive material on substrate  208 . The substrate  208  in this arrangement is mounted on a rotating cylinder  304 . The imaging device  300  contains a carriage  312 . The carriage is adapted to move substantially in parallel to cylinder  304  guided by an advancement screw  316 . An inkjet imaging head  320  is mounted on carriage  312 , along with a laser source  324 . The inkjet imaging head  320  is positioned on carriage  312  in such a manner that during scanning of carriage  312  (in direction  332 ), it precedes the laser source  324 . Controller  328  coordinates and synchronizes the operation of inkjet head  320  and laser source  324 . Controller  328  receives the data for imaging  404  (in  FIG. 4 ) from a digital front end (not shown) and provides it to the inkjet head  320  and laser source  324 . The inkjet head  320  deposits conductive lines  204  on substrate  208 . 
         [0018]    Following the deposition of the conductive lines  204  deposition, by inkjet head  320 , a focused laser beam is applied by laser source  324 . The thickness of sintering applied by the laser source  324  is variable and is adjusted by the spot size of the laser source  324 . The laser source  324  scans lines  204  on the previously deposited lines  204 . 
         [0019]    This process (the laser imaging on lines  204 ) sinters together the nano-particles of the ink deposited on lines  204 . Since size of the laser spot can be made significantly smaller than the deposited line, the sintering process can form sintered grid lines  504  shown in  FIG. 5 , which are substantially narrower that lines  204 . After the laser imaging a sintered metallic conductive line  504  is formed surrounded with un-sintered ink  508 . 
         [0020]    The un-sintered ink  508  is then removed with appropriate materials and complementary processes such as brushing with water (not shown). Alternatively an un-sintered removal element (not shown) can be added to imaging device  300  on carriage  312 . The removal element will operate following to the laser source for sintering  324  on the un-sintered ink  508 . 
         [0021]    The result of the process using the device described above as is shown in  FIG. 6 , is a sintered metallic line  504  in the width of the focused laser beam and enhanced conductivity due to the nature of the sintering process. 
         [0022]    The invention has been described in detail with particular reference to certain preferred embodiments thereof, but it will be understood that variations and modifications can be effected within the scope of the invention. 
       PARTS LIST 
       [0000]    
       
           100  printed circuit electronic board 
           204  inkjet formed conductive lines 
           208  substrate 
           300  imaging device 
           304  rotating cylinder 
           312  carriage 
           316  screw 
           320  inkjet imaging head 
           324  laser source for sintering 
           328  controller 
           332  carriage direction 
           404  imaging data 
           504  sintered conductive lines 
           508  conductive deposited material to be washed out