System and method for forming high resolution electronic circuits on a substrate

Abstract

A system and method for forming high resolution electronic circuits on a substrate is provided. The system ( 10 ) includes a substrate ( 12 ), a source of radiant energy ( 34 ) and a focusing means ( 16 ). The source of radiant energy ( 34 ) directs an energy beam ( 14 ) through the focusing means ( 16 ) in order to direct a focused energy beam ( 18 ) onto the surface of the substrate ( 12 ). The focused energy beam ( 18 ) creates a plurality of channels ( 20 ) in the surface of the substrate ( 12 ). A paste applicator ( 22 ) fills the channels ( 20 ) with an electrically conductive paste ( 24 ). Once heated and cured, the electrically conductive paste ( 24 ) makes up the electrically conductive pathways of the electronic circuit.

1 . A system for forming high resolution electronic circuits on a substrate comprising: 
 a substrate;    a source of radiant energy;    focusing means for focusing an energy beam generated by said source of radiant energy onto said substrate, said focused energy beam forming at least one channel in said substrate, said at least one channel having pre-selected orientation and dimensions;    a stage selectively translatable along a pair of orthogonal axes, said substrate being removably mounted on said stage; and,    a paste applicator for filling said channels with an electrically conductive paste or slurry material, said electrically conductive paste or slurry material being formed of silver particles and silver precursor compounds which convert to solid-phase electrically conductive materials at temperatures of less than 250° C., said silver particles each having an average diameter of 5 micrometers.    
   
   
       2 . The system for forming high resolution electronic circuits on a substrate as recited in  claim 1  wherein said substrate is formed of a polyimide material.  
   
   
       3 . The system for forming high resolution electronic circuits on a substrate as recited in  claim 1  wherein said source of radiant energy is a laser.  
   
   
       4 . The system for forming high resolution electronic circuits on a substrate as recited in  claim 1  wherein said focusing means includes at least one movable mirror for directing said energy beam.  
   
   
       5 . The system for forming high resolution electronic circuits on a substrate as recited in  claim 4  further comprising control means for controlling rotation and translation of said at least one movable mirror.  
   
   
       6 . The system for forming high resolution electronic circuits on a substrate as recited in  claim 1  wherein said focusing means includes at least one optical lens.  
   
   
       7 . The system for forming high resolution electronic circuits on a substrate as recited in  claim 1  further comprising control means for controlling translation of said stage.  
   
   
       8 . The system for forming high resolution electronic circuits on a substrate as recited in  claim 1  wherein said electrically conductive paste or slurry material contains silver.  
   
   
       9 . The system for forming high resolution electronic circuits on a substrate as recited in  claim 1  wherein said electrically conductive paste or slurry material includes compounds promoting adhesion to said substrate.  
   
   
       10 . The system for forming high resolution electronic circuits on a substrate as recited in  claim 1  wherein said substrate is formed of a polymeric material.  
   
   
       11 . The system for forming high resolution electronic circuits on a substrate as recited in  claim 1  wherein said source of radiant energy is a laser having a wavelength shorter than 400 nanometers.  
   
   
       12 . The system for forming high resolution electronic circuits on a substrate as recited in  claim 1  wherein said focused energy beam has a substantially Gaussian distribution.  
   
   
       13 . The system for forming high resolution electronic circuits on a substrate as recited in  claim 1  wherein said focusing means includes a galvanometric mirror scanning system.  
   
   
       14 . The system for forming high resolution electronic circuits on a substrate as recited in  claim 1  wherein said focusing means includes a vector mode scanner.  
   
   
       15 . A method for forming high resolution electronic circuits on a substrate including the steps of: 
 (a) forming at least one channel in a substrate with a focused energy beam;    (b) cleaning said substrate to remove residue from said step of forming at least one channel;    (c) filling said at least one channel with an electrically conductive paste or slurry material, said slurry material being formed of silver particles and silver precursor compounds which convert to solid-phase electrically conductive materials at temperatures of less than 250° C., said silver particles each having an average diameter of less than or equal to 5 micrometers; and,    (d) heating said substrate to temperatures less than 250° C. to cure said electrically conductive paste or slurry material.    
   
   
       16 . The method for forming high resolution electronic circuits on a substrate as recited in  claim 15  wherein said substrate is formed of polyimide.  
   
   
       17 . The method for forming high resolution electronic circuits on a substrate as recited in  claim 15  wherein said focused energy beam is generated by a laser.  
   
   
       18 . The method for forming high resolution electronic circuits on a substrate as recited in  claim 15  wherein said focused energy beam is directed by a movable mirror.  
   
   
       19 . The method for forming high resolution electronic circuits on a substrate as recited in  claim 18  wherein said movable mirror is user controlled.  
   
   
       20 . The method for forming high resolution electronic circuits on a substrate as recited in  claim 15  wherein said focused energy beam is focused by at least one optical lens.  
   
   
       21 . The method for forming high resolution electronic circuits on a substrate as recited in  claim 15  wherein said step of forming at least one channel in a substrate includes translation of said substrate along a pair of orthogonal axes.  
   
   
       22 . The method for forming high resolution electronic circuits on a substrate as recited in  claim 21  wherein said translation of said substrate is user controlled.  
   
   
       23 . The method for forming high resolution electronic circuits on a substrate as recited in  claim 15  wherein said electrically conductive paste or slurry material contains silver.  
   
   
       24 . The method for forming high resolution electronic circuits on a substrate as recited in  claim 15  wherein said focused energy beam is a focused electron beam.  
   
   
       25 . A method for forming high resolution electronic circuits on a substrate including the steps of: 
 (a) forming at least one channel in a substrate with a focused energy beam;    (b) cleaning said substrate to remove residue from said step of forming at least one channel;    (c) filling said at least one channel with an electrically conductive paste or slurry material, said electrically conductive paste or slurry material including silver flake and silver necadecanoate in neodecanoic acid with a 6 to 1 ratio of silver flake to silver neodecanoate; and,    (d) heating said substrate to temperatures less than 250° C. to convert said electrically conductive paste or slurry material to a solid phase conductive material.    
   
   
       26 . The method for forming high resolution electronic circuits on a substrate as recited in  claim 25  wherein said step of cleaning said substrate includes sonication in a liquid.  
   
   
       27 . The method for forming high resolution electronic circuits on a substrate as recited in  claim 26  wherein said sonication in said step of cleaning said substrate is followed by the step of drying said substrate in an oven.  
   
   
       28 . The method for forming high resolution electronic circuits on a substrate as recited in  claim 25  wherein said electrically conductive paste or slurry material further includes liquid solvents.  
   
   
       29 . The method for forming high resolution electronic circuits on a substrate as recited in  claim 28  wherein said liquid solvents include dipropylene glycol methyl ether added at a 1.1 weight percentage.  
   
   
       30 . The method for forming high resolution electronic circuits on a substrate as recited in  claim 25  wherein said electrically conductive paste or slurry material further includes compounds promoting adhesion of said solid phase conductive material to said substrate.  
   
   
       31 . The method for forming high resolution electronic circuits on a substrate as recited in  claim 30  wherein said adhesion-promoting compounds are diamines.  
   
   
       32 . The method for forming high resolution electronic circuits on a substrate as recited in  claim 25  wherein said substrate is formed of polymer materials.  
   
   
       33 . The method for forming high resolution electronic circuits on a substrate as recited in  claim 32  wherein said polymer materials include polyimide materials.  
   
   
       34 . The method for forming high resolution electronic circuits on a substrate as recited in  claim 32  wherein said polymer materials include liquid crystal polymers.  
   
   
       35 . The method for forming high resolution electronic circuits on a substrate as recited in  claim 25  wherein said step of forming at least one channel in said substrate is accomplished by using a laser operating at wavelengths shorter than 400 nm.  
   
   
       36 . The method for forming high resolution electronic circuits on a substrate as recited in  claim 35  wherein said laser is a frequency-converted solid state laser.  
   
   
       37 . The method for forming high resolution electronic circuits on a substrate as recited in  claim 36  wherein said step of forming at least one channel in said substrate includes the step of directing a laser beam generated by said laser using galvanometrically-driven mirrors.  
   
   
       38 . A method for the fabrication of conducting elements on planar insulating substrates comprising the steps of: 
 (a) laser ablation of at least one channel or hole in a substrate;    (b) cleaning laser ablation debris formed in the step of laser ablation from said substrate;    (c) filling said channels or holes with a silver conductive paste material, said silver conductive paste material including silver flake and silver necadecanoate in neodecanoic acid with a 6 to 1 ratio of silver flake to silver neodecanoate;    (d) soft baking said substrate at temperatures of less than 100° C. for a period of 1 to 30 minutes;    (e) sequentially repeating said steps of filling said channels or holes and said soft baking said substrate until said channels or holes are completely filled;    (f) removing excess conductive filler material from an upper surface of said substrate; and,    (g) heating said substrate to temperatures of less than 250° C. to convert said conductive paste filler material to solid phase conductive material.    
   
   
       39 . The method for the fabrication of conducting elements on planar insulating substrates as recited in  claim 38  wherein said step of cleaning laser ablation debris includes sonication in a liquid.  
   
   
       40 . The method for the fabrication of conducting elements on planar insulating substrates as recited in  claim 39  wherein said liquid is water containing a mild detergent.  
   
   
       41 . The method for the fabrication of conducting elements on planar insulating substrates as recited in  claim 39  wherein said sonication is followed by the step of drying said substrate in an oven.  
   
   
       42 . The method for the fabrication of conducting elements on planar insulating substrates as recited in  claim 38  wherein said step of removal of excess conductive filler material is performed by an abrasion process.  
   
   
       43 . The method for the fabrication of conducting elements on planar insulating substrates as recited in  claim 38  wherein said conductive filler material includes liquid solvents.  
   
   
       44 . The method for the fabrication of conducting elements on planar insulating substrates as recited in  claim 43  wherein said liquid solvents include dipropylene glycol methyl ether added at a 1.1 weight percentage.  
   
   
       45 . The method for the fabrication of conducting elements on planar insulating substrates as recited in  claim 38  wherein said conductive filler material further includes compounds promoting adhesion of said solid phase conductive material to said substrate.  
   
   
       46 . The method for the fabrication of conducting elements on planar insulating substrates as recited in  claim 45  wherein said adhesion-promoting compounds are diamines.  
   
   
       47 . The method for the fabrication of conducting elements on planar insulating substrates as recited in  claim 38  wherein said substrate is formed of a polymer material.  
   
   
       48 . The method for the fabrication of conducting elements on planar insulating substrates as recited in  claim 47  wherein said polymer material is a polyimide material.  
   
   
       49 . The method for the fabrication of conducting elements on planar insulating substrates as recited in  claim 47  wherein said polymer material includes liquid crystal polymer.  
   
   
       50 . The method for the fabrication of conducting elements on planar insulating substrates as recited in  claim 38  wherein said step of laser ablation is performed using a laser operating at wavelengths shorter than 400 nm.  
   
   
       51 . The method for the fabrication of conducting elements on planar insulating substrates as recited in  claim 50  wherein said laser is a frequency-converted solid state laser.  
   
   
       52 . The method for the fabrication of conducting elements on planar insulating substrates as recited in  claim 50  wherein radiation generated by said laser is directed to said substrate using galvanometrically-driven mirrors.