Method of forming polymide coating containing dielectric filler on surface of metallic material process for producing copper clad laminate for formation of capacitor layer for printed wiring board and copper clad laminate obtained by the process

Abstract

A method of forming a dielectric layer containing dielectric filler, which is excellent in film thickness uniformity, from a polyimide electrodeposition liquid containing dielectric filler. In particular, a method of forming a polyimide coating container dielectric filler on a surface of metallic material according to the electrodeposition coating technique, characterized in that as the dielectric filler, use is made of dielectric powder of perovskite structure in approximately spherical form which has an average particle diameter (D 1A ) of 0.05 to 1.0 μm and a weight cumulative particle diameter (D 50 ), measured in accordance with the laser diffraction scattering type particle size distribution measuring method, of 0.1 to 2.0 μm and further exhibits an aggregation degree, in terms of D 50 /D 1a wherein D 50 and D 1a represent a weight cumulative particle diameter and an average particle diameter obtained by image analysis, respectively, of 4.5 or less.

1 . A method of forming a dielectric filler-containing polyimide coating on a metallic material through an electrodeposition coating method with the use of a dielectric filler-containing polyimide electrodeposition solution, said solution being a polyimide electrodeposition solution in which a dielectric filler has been contained, 
 wherein the used as a dielectric filler is a globoid dielectric powder having perovskite structure which is 0.05 to 1.0 μm in an average particle size D IA , 0.1 to 2.0 μm in a weight cumulative particle size D 50  based on a laser diffraction scattering particle size distribution measurement method, and 4.5 or less in a coagulation degree value represented by D 50 /D IA  where the weight cumulative particle size D 50  and the average particle size D IA  obtained from an image analysis.    
   
   
       2 . A method of forming a dielectric filler-containing polyimide coating on a metallic material through an electrodeposition coating method with the use of a dielectric filler-containing polyimide electrodeposition solution, said solution being a polyimide electrodeposition solution in which a dielectric filler has been contained, 
 wherein the method comprising the steps of:    forming on a copper material a metallic seed layer of either nickel or cobalt; and    forming on a surface of said copper material a dielectric filler-containing polyimide coating through an electrodeposition coating method with the use of a dielectric filler-containing polyimide electrodeposition solution, said solution containing a dielectric powder as a dielectric filler, said dielectric powder having perovskite structure which is 0.05 to 1.0 μm in an average particle size D IA , 0.1 to 2.0 μm in a weight cumulative particle size D 50  based on a laser diffraction scattering particle size distribution measurement method, and 4.5 or less in a coagulation degree value represented by D 50 /D IA  where the weight cumulative particle size D 50  and the average particle size D IA  obtained from an image analysis.    
   
   
       3 . A method of forming a dielectric filler-containing polyimide coating on a metallic material according to  claim 1 , wherein a content of the dielectric filler in the dielectric filler-containing polyimide electrodeposition solution is 50 g/L to 350 g/L.  
   
   
       4 . A method of forming a dielectric filler-containing polyimide coating on a metallic material according to  claim 1 , wherein the dielectric filler is either calcined barium titanate or uncalcined barium titanate.  
   
   
       5 . A method of forming a dielectric filler-containing polyimide coating on a metallic material according to  claim 1 , wherein the dielectric filler is a barium titanate having either a cubic crystal structure only or a crystal structure of a mixed state between a cubic crystal structure and a tetragonal crystal structure.  
   
   
       6 . A method of manufacturing a copper clad laminate for forming a capacitor layer for use in a printed wiring board, said copper clad laminate having a layered structure consisting of a first copper foil, a dielectric filler-containing polyimide dielectric layer, and a second copper foil, comprising the steps of: 
 employing a copper foil having a dielectric filler-containing polyimide coating and a copper foil having a polyimid thin film being a polyimide thin film formed on one side of said second copper foil, said dielectric filler-containing polyimide coating having a dielectric filler-containing polyimide coating formed on a surface of said first copper foil through an electrodeposition coating method with the use of a dielectric filler-containing polyimide electrodeposition solution, said dielectric filler-containing polyimide electrodeposition solution being prepared through mixing a polyimide electrodeposition solution and a dielectric powder, as a dielectric filler, having a perovskite structure which is 0.05 to 1.0 μm in an average particle size D IA , 0.1 to 2.0 μm in a weight cumulative particle size D 50  based on a laser diffraction scattering particle size distribution measurement method, and 4.5 or less in a coagulation degree value represented by D 50 /D IA  where the weight cumulative particle size D 50  and the average particle size D IA  obtained from an image analysis; and    laminating a surface of the dielectric filler-containing polyimide coating of said copper foil having a dielectric filler-containing polyimide coating and a surface of the polyimide thin film of said copper foil having a polyimid thin film in a manner that both the surfaces come into contact with each other.    
   
   
       7 . A method of manufacturing a copper clad laminate for forming a capacitor layer for use in a printed wiring board, said copper clad laminate having a layered structure consisting of a first copper foil, a dielectric filler-containing polyimide dielectric layer, and a second copper foil, comprising the steps of: 
 forming a metallic seed layer of either nickel or cobalt on a surface of a first copper foil;    employing a copper foil having a dielectric filler-containing polyimide coating and a copper foil having a polyimid thin film being a polyimide thin film formed on one side of said second copper foil, said dielectric filler-containing polyimide coating having a dielectric filler-containing polyimide coating formed on a surface of said metal seed layer through an electrodeposition coating method with the use of a dielectric filler-containing polyimide electrodeposition solution, said dielectric filler-containing polyimide electrodeposition solution being prepared through mixing a polyimide electrodeposition solution and a dielectric powder, as a dielectric filler, having a perovskite structure which is 0.05 to 1.0 μm in an average particle size D IA , 0.1 to 2.0 μm in a weight cumulative particle size D 50  based on a laser diffraction scattering particle size distribution measurement method, and 4.5 or less in a coagulation degree value represented by D 50 /D IA  where the weight cumulative particle size D 50  and the average particle size D IA  obtained from an image analysis; and    laminating a surface of the dielectric filler-containing polyimide coating of said copper foil having a dielectric filler-containing polyimide coating and a surface of the polyimide thin film of said copper foil having a polyimid thin film in a manner that both the surfaces come into contact with each other.    
   
   
       8 . A method of forming a copper clad laminate for forming a capacitor layer for use in a printed wiring board according to  claim 6 , wherein a content of the dielectric filler in the dielectric filler-containing polyimide electrodeposition solution is 50 g/L to 350 g/L.  
   
   
       9 . A method of forming a copper clad laminate for forming a capacitor layer for use in a printed wiring board according to  claim 6 , wherein the dielectric filler is either calcined barium titanate or uncalcined barium titanate.  
   
   
       10 . A method of forming a copper clad laminate for forming a capacitor layer for use in a printed wiring board according to  claim 6 , wherein the dielectric filler is a barium titanate having either a cubic crystal structure only or a crystal structure of a mixed state between a cubic crystal structure and a tetragonal crystal structure.  
   
   
       11 . A copper clad laminate for forming a capacitor layer for use in a printed wiring board as obtained through the methods of forming a copper clad laminate for forming a capacitor layer for use in a printed wiring board according to  claim 6 .  
   
   
       12 . A method of forming a dielectric filler-containing polyimide coating on a metallic material according to  claim 2 , wherein a content of the dielectric filler in the dielectric filler-containing polyimide electrodeposition solution is 50 g/L to 350 g/L.  
   
   
       13 . A method of forming a dielectric filler-containing polyimide coating on a metallic material according to  claim 2 , wherein the dielectric filler is either calcined barium titanate or uncalcined barium titanate.  
   
   
       14 . A method of forming a dielectric filler-containing polyimide coating on a metallic material according to  claim 2 , wherein the dielectric filler is a barium titanate having either a cubic crystal structure only or a crystal structure of a mixed state between a cubic crystal structure and a tetragonal crystal structure.  
   
   
       15 . A method of forming a copper clad laminate for forming a capacitor layer for use in a printed wiring board according to  claim 7 , wherein a content of the dielectric filler in the dielectric filler-containing polyimide electrodeposition solution is 50 g/L to 350 g/L.  
   
   
       16 . A method of forming a copper clad laminate for forming a capacitor layer for use in a printed wiring board according to  claim 7 , wherein the dielectric filler is either calcined barium titanate or uncalcined barium titanate.  
   
   
       17 . A method of forming a copper clad laminate for forming a capacitor layer for use in a printed wiring board according to  claim 7 , wherein the dielectric filler is a barium titanate having either a cubic crystal structure only or a crystal structure of a mixed state between a cubic crystal structure and a tetragonal crystal structure.  
   
   
       18 . A copper clad laminate for forming a capacitor layer for use in a printed wiring board as obtained through the methods of forming a copper clad laminate for forming a capacitor layer for use in a printed wiring board according to  claim 7.