Printed circuit board and corresponding method for producing a printed circuit board

Abstract

The printed circuit board with at least one substrate layer having signal lines on a corresponding upper surface and on a corresponding lower surface has a sleeve-sized conductive layer on a circumference of at least one via hole between the upper and lower surface for a conductive connection between at least one signal line on the upper surface and at least one signal line on the lower surface. to An axial enlargement of the sleeve-sized conductive layer is radially bent above a base layer of copper on the upper surface and below a base layer of copper on the lower surface.

What is claimed is: 
     
         1 . A printed circuit board with at least one substrate layer having signal lines on a corresponding upper surface and on a corresponding lower surface, wherein on a circumference of at least one via hole a sleeve-sized conductive layer is disposed between the upper and lower surface for a conductive connection between at least one signal line on the upper surface and at least one signal line on the lower surface and wherein an axial enlargement of the sleeve-sized conductive layer is radially bent above a metallic base layer on the upper surface and below a metallic base layer on the lower surface. 
     
     
         2 . The printed circuit board according to  claim 1 , wherein the height between the top of the radially bent enlargement of the sleeve-sized conductive layer and the top of the base layer of copper is at least 5 Micrometer, preferably at least 10 Micrometer and most preferred at least 15 Micrometer. 
     
     
         3 . The printed circuit board according to  claim 1 , wherein each via hole inside the sleeve-sized conductive layer is filled with a dielectric material. 
     
     
         4 . The printed circuit board according to  claim 3 , wherein the dielectric material is a resin, preferably an epoxy resin. 
     
     
         5 . The printed circuit board according to  claim 1 , wherein the sleeve-sized conductive layer comprises an outer chemical-vapor-deposited layer, preferably of copper, and an inner galvanically deposited layer, preferably of copper. 
     
     
         6 . The printed circuit board according to  claim 3 , wherein the dielectric material is filled between the top and the bottom of the axially enlarged and radially bent sleeve-sized conductive layer inside the via hole. 
     
     
         7 . The printed circuit board according to  claim 5 , wherein the dielectric material is filled between the top and the bottom of the chemical-vapor-deposited layer in the axially enlarged and radially bent sleeve-sized conductive layer inside the via hole. 
     
     
         8 . The printed circuit board according to  claim 7 , wherein between the top of the galvanically deposited layer and the top of the chemical-vapor-deposited layer and between the bottom of the galvanically deposited layer and the bottom of the chemical-vapor-deposited layer a conductive layer preferably of copper, is galvanically deposited. 
     
     
         9 . The printed circuit board according to  claim 1 , wherein a thickness of the base layer between the radially bent enlargement of the sleeve-sized conductive layer and the substrate layer is larger than a thickness of the neighboring base layer on the upper and lower surface. 
     
     
         10 . A method for producing a printed circuit board with at least one substrate layer having a signal line on a corresponding upper surface and on a corresponding lower surface comprising following method steps:
 boring at least one via hole through the printed circuit board,   depositing a conductive layer on the upper and lower surface and a sleeve-sized conductive layer on a circumference of each of the at least one via hole between the upper and lower surface and   removing a first sublayer of the conductive layer on the upper and lower surface in all ranges which are positioned at least a specific minimum distance from each of the at least one via hole.   
     
     
         11 . The method for producing a printed circuit board according to  claim 10 , wherein the depositing of the conductive layer on the upper and lower surface comprises a depositing of a metallic base layer preferably of copper, a chemical-vapor-depositing of a metallic layer preferably of copper and a galvanically depositing of a metallic layer preferably of copper. 
     
     
         12 . The method according to  claim 10 , wherein the depositing of the sleeve-sized conductive layer on the circumference of each of the at least via hole comprises a chemical-vapor-depositing of a metallic layer preferably of copper and a galvanically depositing of a metallic layer preferably of copper. 
     
     
         13 . The method according  claim 10 , wherein before removing the first sublayer of the conductive layer each via hole inside the corresponding sleeve-sized conductive layer is filled with a dielectric material. 
     
     
         14 . The method according to  claim 13 , wherein before removing the first sublayer of the conductive layer and after filling each via hole with a dielectric material a photo-resistant layer is deposited on ranges above the conductive layer on the upper and lower surface inside the specific minimum distance from each of the at least one via hole. 
     
     
         15 . The method according to  claim 14 , wherein after depositing the photo-resistant layer the first sublayer of the conductive layer is etched on the upper and lower surface using a light beam of a laser which is positioned on the upper and lower surface. 
     
     
         16 . The method according to  claim 15 , wherein the etched first sublayer comprises the chemical-vapor-deposited layer preferably of copper and the galvanically deposited layer preferably of copper. 
     
     
         17 . The method according to  claim 15 , wherein the etched first sublayer comprises a chemical-vapor-deposited layer preferably of copper, a galvanically deposited layer preferably of copper and a second sublayer of the base layer preferably of copper. 
     
     
         18 . The method according to  claim 13 , wherein the dielectric material is removed from each of the at least one via hole down to the top of a chemical-vapor-deposited layer preferably of copper and is refilled with a galvanically deposited layer preferably of copper