Printed circuit board with reduced crosstalk noise and method of forming wiring lines on a board to form such a printed circuit board

Abstract

A printed circuit board includes a first wiring line and a second wiring line spaced apart from the first wiring line. The first wiring line has a first portion having a surface which faces the second wiring line and is smaller in area than that of the second portion, so that a crosstalk noise between the first portion of the first wiring line and the second wiring line can be reduced.

What is claimed is:  
     
         1 . A printed circuit board comprising: 
 a first wiring line; and    a second wiring line spaced apart from the first wiring line,    the first wiring line having first and second portions, the first portion having a surface which faces the second wiring line and is smaller in area than that of the second portion, so that a crosstalk noise between the first portion of the first wiring line and the second wiring line can be reduced.    
     
     
         2 . The printed circuit board as claimed in  claim 1 , wherein the second wiring line has third and fourth portions, the third portion having a surface which faces the first wiring line and is smaller in area than that of the fourth portion, so that a crosstalk noise between the third portion of the second wiring line and the first wiring line can be reduced.  
     
     
         3 . The printed circuit board as claimed in  claim 1 , wherein the first portion of the first wiring line is thinner than the second portion thereof.  
     
     
         4 . The printed circuit board as claimed in  claim 2 , wherein the first portion of the first wiring line is thinner than the second portion thereof, and the third portion of the second wiring line is thinner than the fourth portion thereof.  
     
     
         5 . The printed circuit board as claimed in  claim 4 , wherein the first portion of the first wiring line and the third portion of the second wiring line have an identical height.  
     
     
         6 . The printed circuit board as claimed in  claim 4 , wherein the first portion of the first wiring line faces the third portion of the second wiring line.  
     
     
         7 . The printed circuit board as claimed in  claim 5 , wherein the first portion of the first wiring line faces the third portion of the second wiring line.  
     
     
         8 . The printed circuit board as claimed in  claim 4 , wherein: 
 the first portion of the first wiring line faces the third portion of the second wiring line;    the second portion of the first wiring line faces the fourth portion of the second wiring line; and    a distance between the first and third portions is shorter than that between the second and fourth portions.    
     
     
         9 . The printed circuit board as claimed in  claim 5 , wherein: 
 the first portion of the first wiring line faces the third portion of the second wiring line;    the second portion of the first wiring line faces the fourth portion of the second wiring line; and    a distance between the first and third portions is shorter than that between the second and fourth portions.    
     
     
         10 . The printed circuit board as claimed in  claim 1 , wherein the first portion of the first wiring line has a triangular cross-sectional shape.  
     
     
         11 . The printed circuit board as claimed in  claim 2 , wherein the first portion of the first wiring line and the third portion of the second wiring line have a triangular cross-sectional shape.  
     
     
         12 . The printed circuit board as claimed in  claim 11 , wherein the first portion of the first wiring line and the third portion of the second wiring line have an identical height.  
     
     
         13 . The printed circuit board as claimed in  claim 11 , wherein the first portion of the first wiring line faces the third portion of the second wiring line.  
     
     
         14 . The printed circuit board as claimed in  claim 12 , wherein the first portion of the first wiring line faces the third portion of the second wiring line.  
     
     
         15 . The printed circuit board as claimed in  claim 1 , wherein the first portion of the first wiring line has a trapezoidal cross-sectional shape.  
     
     
         16 . The printed circuit board as claimed in  claim 2 , wherein the first portion of the first wiring line and the third portion of the second wiring line have a trapezoidal cross-sectional shape.  
     
     
         17 . The printed circuit board as claimed in  claim 16 , wherein the first portion of the first wiring line and the third portion of the second wiring line have an identical height.  
     
     
         18 . The printed circuit board as claimed in  claim 16 , wherein the first portion of the first wiring line faces the third portion of the second wiring line.  
     
     
         19 . The printed circuit board as claimed in  claim 17 , wherein the first portion of the first wiring line faces the third portion of the second wiring line.  
     
     
         20 . The printed circuit board as claimed in  claim 1 , further comprising: 
 a third wiring line; and    a fourth wiring line spaced apart from the third wiring line,    the third wiring line having first and second portions, the first portion having a surface which faces the fourth wiring line and is larger in area than that of the second portion.    
     
     
         21 . The printed circuit board as claimed in  claim 20 , wherein the fourth wiring line has third and fourth portions, the third portion having a surface which faces the third wiring line and is larger in area than that of the fourth portion.  
     
     
         22 . The printed circuit board as claimed in  claim 20 , wherein the first portion of the third wiring line is thicker than the second portion thereof.  
     
     
         23 . The printed circuit board as claimed in  claim 21 , wherein the first portion of the third wiring line is thicker than the second portion thereof, and the third portion of the fourth wiring line is thicker than the fourth portion thereof.  
     
     
         24 . The printed circuit board as claimed in  claim 23 , wherein the first portion of the third wiring line and the third portion of the fourth wiring line have an identical height.  
     
     
         25 . The printed circuit board as claimed in  claim 23 , wherein the first portion of the third wiring line faces the third portion of the fourth wiring line.  
     
     
         26 . The printed circuit board as claimed in  claim 24 , wherein the first portion of the third wiring line faces the third portion of the fourth wiring line.  
     
     
         27 . A printed circuit board comprising: 
 a first wiring line; and    a second wiring line spaced apart from the first wiring line,    the first wiring line including a first portion having a surface which faces the second wiring line and is smaller in area than a surface of the second wiring line which faces the first portion of the first wiring line, so that a crosstalk noise between the first portion of the first wiring line and the second wiring line can be reduced.    
     
     
         28 . The printed circuit board as claimed in  claim 27 , wherein the first portion of the first wiring line is thinner than the second wiring line.  
     
     
         29 . The printed circuit board as claimed in  claim 27 , further comprising: 
 a third wiring line; and    a fourth wiring line spaced apart from the first wiring line,    the third wiring line including a first portion having a surface which faces the fourth wiring line and is larger in area than a surface of the fourth wiring line which faces the first portion of the third wiring line.    
     
     
         30 . The printed circuit board as claimed in  claim 29 , wherein the first portion of the third wiring line is thicker than the fourth wiring line.  
     
     
         31 . A method of forming wiring lines on a board to form a printed circuit board, comprising the steps of: 
 (a) forming the wiring lines of a predetermined uniform thickness; and    (b) etching a first wiring line thereof so that the first wiring line has a first portion thinner than a second portion thereof.    
     
     
         32 . The method as claimed in  claim 31 , wherein a second wiring line thereof spaced apart from the first wiring line is etched in the step (b) so as to have a third portion thinner than a fourth portion thereof.  
     
     
         33 . A method of forming wiring lines on a board to form a printed circuit board, comprising the steps of: 
 (a) forming the wiring lines of a predetermined uniform thickness; and    (b) applying a conductive material on a first wiring line thereof so that the first wiring line has a first portion thicker than a second portion thereof.    
     
     
         34 . The method as claimed in  claim 33 , wherein the conductive material is applied on a second wiring line thereof spaced apart from the first wiring line in the step (b) so that the second wiring line has a third portion thicker than a fourth portion thereof.  
     
     
         35 . A method of forming wiring lines on a board to form a printed circuit board, comprising the steps of: 
 (a) forming the wiring lines of a predetermined uniform thickness; and    (b) grinding a first wiring line thereof so that the first wiring line has a first portion thinner than a second portion thereof.    
     
     
         36 . The method as claimed in  claim 35 , wherein a second wiring line thereof spaced apart from the first wiring line is ground in the step (b) so as to have a third portion thinner than a fourth portion thereof.