Compound for forming wiring conductor, fabrication method of circuit board using the same and circuit board

Abstract

The present invention sufficiently secures conductor component content ratio in wiring formed on a multilayer circuit board and increases reliability by fabricating the multilayer circuit board by steps of drawing wiring precursor patterns containing a paste of compound for forming wiring conductor containing (a) superfine metal particles (metal nanoparticles) whose average particle size is 1-10 nm; (b) an organic coating compound coated on the surface of the superfine metal particle in the film thickness of 1-10 nm; (c) a latent reactive organic compound reacting with the organic coating compound in the range of 100-250° C., (d) metal particles whose average particle size is 0.5-10 μm, and (e) dispersion medium that stably disperses components (a) through (d) on a substrate by screen printing, sintering by heating the patterns to 100-250° C., and electrochemically treating the patterns to allow the conductor to deposit in a desired cross-sectional area in the inside.

1 . A fabrication method of circuit boards, comprising the steps of: 
 (a) preparing paste containing superfine metal particles whose average particle size is 1 through 10 nm, an organic coating compound coated on the surface of the superfine metal particle in the film thickness of 1 through 10 nm, a latent reactive organic compound that reacts with the organic coating compound in the range from 100 to 250° C., metal particles whose average particle size is 0.5 through 10 μm, and dispersion medium which can stably disperse these components;    (b) directly drawing patterns to be wiring precursor with the paste through screen printing mask having desired opening patterns;    (c) sintering the wiring precursor by heating the substrate to 100 to 250° C.; and    (d) electrochemically treating the sintered wiring precursor to have a desired conductor cross-sectional area.    
   
   
       2 . The fabrication method of circuit boards according to  claim 1 , 
 wherein the screen printing mask is the mask that corresponds to the finest fine-line pattern in the wiring portion of the circuit board, and the wiring portion with the line width bigger than the fine-line pattern is formed by increasing the conductor cross-sectional area to the desired film thickness by the electrochemical treatment.    
   
   
       3 . The fabrication method of circuit boards according to  claim 1 , 
 wherein the electrochemical treatment is the plating treatment provided for the wiring precursor.    
   
   
       4 . A fabrication method of circuit boards, comprising the steps of: 
 drawing patterns for wiring on a substrate using a compound for forming wiring conductor with varying metal particles of average particle sizes dispersed in a dispersion medium;    sintering the drawn patterns; and    filling voids after getting rid of the dispersion medium in the drawn patterns after sintering with the conductor to form a wiring conductor.    
   
   
       5 . The fabrication method of circuit boards according to  claim 4 , 
 wherein the compound for forming wiring conductor is a paste that contains (a) superfine metal particles whose average particle size is 1 through 10 nm; (b) an organic coating compound coated on the surface of the superfine metal particle in the film thickness of 1 through 10 nm; (c) a latent reactive organic compound that reacts with the organic coating compound in the range from 100 to 250° C.; (d) metal particles whose average particle size is 0.5 through 10 μm; and (e) dispersion medium that stably disperses components (a) through (d).    
   
   
       6 . The fabrication method of circuit boards according to  claim 4 , 
 wherein the filling of conductor is performed by plating the drawn patterns after Wintering with conductor metal.