Metal pattern formation

Abstract

A method of reproducibly manufacturing circuit carriers with very fine circuit structures and an electrophoretic varnish to be applied in this method are described in which a dielectric substrate comprising a base metal surface is provide, a varnish layer is applied onto the substrate surface electrodepositing the electrophoretic varnish, thereafter the varnish layer is ablated in at least parts of the regions that do not correspond to the metal pattern to be formed by means of ultraviolet radiation, the base metal surface being laid bare, and finally the bare base metal surface is etched.

1 . Method of forming a metal pattern on a dielectric substrate comprising the following method steps: 
 a) providing a substrate comprising a base metal surface;    b) applying a varnish layer to the substrate by means of an electrophoretic process,    c) ablating the varnish layer in at least parts of regions that do not correspond to the metal pattern to be formed, the base metal surface being laid bare by means of ultraviolet radiation;    d) etching of the base metal surface that has been laid bare,    wherein the varnish contains at least one ablation amplifier adjusted to ultraviolet radiation.    
     
     
         2 . Method according to  claim 1 , wherein the at least one ablation amplifier is selected from the group comprising aromatic carbonyl compounds, polycyclic hydrocarbon compounds, heterocyclic compounds and aromatic nitro compounds.  
     
     
         3 . Method according to one of the previous claims, wherein the ablation amplifier is selected from the group comprising derivatives of acetophenone, benzophenone, cinnamic acid, tropolone, further diphenylbutadienes and the derivatives thereof, chrysenes, diphenylfulvenes, dipyridyl amines, phenoxazines, 2-phenyl benzimidazoles, isoquinoline oxides, nitrophenoles, nitroanilines, ω-nitrostyrenes and 1.5-dinitronaphthalines  
     
     
         4 . Method according to one of the previous claims, wherein the ultraviolet radiation is generated by a laser.  
     
     
         5 . Method according to one of the previous claims, wherein the ultraviolet radiation is generated by an excimer laser.  
     
     
         6 . Method according to one of the previous claims, wherein the varnish layer is formed with an anaphoretic varnish.  
     
     
         7 . Method according to one of the previous claims, wherein the varnish is formed with at least one copolymer produced by copolymerization of monomers, selected from the group comprising methacrylic acid, C 1 -C 2  alkyl methacrylate, C 3 -C 10  alkyl (meth)acrylate and hydroxy alkyl methacrylate; the alkyl groups of which have 2-4 carbon atoms.  
     
     
         8 . Method according to  claim 7 , wherein C 1 -C 2  alkyl methacrylate is methyl methacrylate; C 3 -C 10  alkyl (meth)acrylate is butyl acrylate; and/or hydroxy alkyl methacrylate is 1-hydroxy ethyl methacrylate and/or 2-hydroxy ethyl methacrylate.  
     
     
         9 . Method according to one of claims  7  and  8 , wherein the copolymer is formed from monomers with the following amounts: 
 a) methacrylic acid: 1-25% by weight  
 b) C 1 -C 2  alkyl methacrylate: 20-80% by weight  
 c) C 3 -C 10  alkyl acrylate: 1-50% by weight  
 d) hydroxy alkyl methacrylate: 0-20% by weight,  
 the sum of the aforementioned monomers amounting to a total of 100% by weight.  
 
     
     
         10 . Method according to one of  claims 7  to  9 , wherein the mean value by weight of the molecular weight M W  of the copolymer is set in the range of from 15,000 to 100,000 g/mol.  
     
     
         11 . Method according to  claim 10 , wherein M W  is set in the range of from 50,000 to 60,000 g/mol.  
     
     
         12 . Method according to one of  claims 7  to  11 , wherein the index of polydispersiveness P I  of the copolymer is set to a value in the range of from 1.5 to 3.5.  
     
     
         13 . Method according to  claim 12 , wherein the value of P I  is set in the range of from 2.0 to 2.5.  
     
     
         14 . Method according to one of the previous claims, wherein the varnish is anaphoretic and contains at least one base selected from the group comprising mono, di, trialkyl amines, monoethanol amine, morpholine, ammonia and sodium hydroxide.  
     
     
         15 . Method according to one of the previous claims, wherein the varnish layer is removed from the based metal surface after method step d).  
     
     
         16 . Electrophoretic varnish containing at least one ablation amplifier adjusted to ultraviolet radiation.  
     
     
         17 . Electrophoretic varnish according to  claim 16 , wherein the at least one ablation amplifier is selected from the group comprising aromatic carbonyl compounds, polycyclic hydrocarbon compounds, heterocyclic compounds and aromatic nitro compounds.  
     
     
         18 . Electrophoretic varnish according to one of claims  16  and  17 , wherein the ablation amplifier is selected from the group comprising derivatives of acetophenone, benzophenone, cinnamic acid, tropolone, further diphenylbutadienes and the derivatives thereof, chrysenes, diphenylfulvenes, dipyridyl amines, phenoxazines, 2-phenyl benzimidazoles, isoquinoline oxides, nitrophenoles, nitroanilines, ω-nitrostyrenes and 1.5-dinitronaphthalines  
     
     
         19 . Electrophoretic varnish according to one of  claims 16  to  18 , wherein the varnish is an anaphoretic varnish.  
     
     
         20 . Electrophoretic varnish according to one of  claims 16  to  19 , wherein the varnish is formed with at least one copolymer produced by copolymerization of monomers, selected from the group comprising methacrylic acid, C 1 -C 2  alkyl methacrylate, C 3 -C 10  alkyl (meth)acrylate and hydroxy alkyl methacrylate; the alkyl groups of which have 2-4 carbon atoms.  
     
     
         21 . Electrophoretic varnish according to  claim 20 , wherein C 1 -C 2  alkyl methacrylate is methyl methacrylate; C 3 -C 10  alkyl (meth)acrylate is butyl acrylate; and/or hydroxy alkyl methacrylate is 1-hydroxy ethyl methacrylate and/or 2-hydroxy ethyl methacrylate.  
     
     
         22 . Electrophoretic varnish according to one of claims  20  and  21 , wherein the copolymer is formed from monomers with the following amounts: 
 a) methacrylic acid: 1-25% by weight  
 b) C 1 -C 2  alkyl methacrylate: 20-80% by weight  
 c) C 3 -C 10  alkyl acrylate: 1-50% by weight  
 d) hydroxy alkyl methacrylate: 0-20% by weight,  
 the sum of the aforementioned monomers amounting to a total of 100% by weight.  
 
     
     
         23 . Electrophoretic varnish according to one of  claims 20  to  22 , wherein the mean value by weight of the molecular weight M W  of the copolymer is set in the range of from 15,000 to 100,000 g/mol.  
     
     
         24 . Electrophoretic varnish according to one of  claims 20  to  23 , wherein the index of polydispersiveness P I  of the copolymer is set to a value in the range of from 1.5 to 3.5.  
     
     
         25 . Substrate coated with the electrophoretic varnish according to one of  claims 16  to  24 .